The Harang Reversal and the Interchange Stability of the Magnetotail
Ohtani, S.; Gkioulidou, M.; Wang, C. P.; Wolf, R.
2015-12-01
During the substorm growth phase the overall convection, electric currents, and aurora structures in the nightside ionosphere often change very gradually over prolonged (> 1 hr) periods, and therefore the magnetosphere-ionosphere (M-I) system can be considered to be in a quasi-steady state. For the source region of a downward field-aligned current (FAC) the cross-tail current, which is carried mostly by ions, closes with a FAC, which is carried by electrons moving away from the ionosphere. Thus both ions and electrons accumulate there and accordingly, the plasma pressure increases. In the source region of an upward FAC, in contrast, the reduction of plasma pressure is expected. Since the plasma pressure, more precisely the entropy parameter (pVr), is most critical for the interchange stability of the magnetotail, this simple assessment raises a fundamental question about the magnetotail dynamics, that is, how the magnetotail remains to be steady. In this study we argue that if the magnetosphere is in a steady state, those expected increase and decrease in plasma pressure need to balance with the change due to the plasma transport by convection. This requirement, along with the condition for the interchange stability, leads to the conclusion that the associated pattern of convection has a structure that is presumably the magnetospheric counter part of the Harang reversal. More specifically, for the dusk convection cell, the convection flow is directed azimuthally westward in the source region of the downward R2 current, whereas it is directed sunward in the source region of the upward R1 current. We verify this idea by examining a quasi-steady magnetotail modeled by the RCM-Dungey code. Using equi-potential contours as a reference we also suggest that auroral arcs mapped to the equator tend to be oriented in the east-west and Sun-Earth direction if they are located in the premidnight R2 and R1 currents, respectively.
Auroral research at the Tromsø Northern Lights Observatory: the Harang directorship, 1928-1946
Egeland, Alv; Burke, William J.
2016-03-01
The Northern Lights Observatory in Tromsø began as Professor Lars Vegard's dream for a permanent facility in northern Norway, dedicated to the continuous study of auroral phenomenology and dynamics. Fortunately, not only was Vegard an internationally recognized spectroscopist, he was a great salesman and persuaded the Rockefeller Foundation that such an observatory represented an important long-term investment. A shrewd judge of talent, Vegard recognized the scientific and managerial skills of Leiv Harang, a recent graduate from the University of Oslo, and recommended that he become the observatory's first director. In 1929, subsequent to receiving the Rockefeller Foundation grant, the University of Oslo established a low temperature laboratory to support Vegard's spectroscopic investigations. This paper follows the scientific accomplishments of observatory personnel during the 18 years of Harang's directorship. These include: identifying the chemical sources of auroral emissions, discovering the Vegard-Kaplan bands, quantifying height distributions of different auroral forms, interpreting patterns of magnetic field variations, remotely probing auroral electron distribution profiles in the polar ionosphere, and monitoring the evolving states of the ozone layer. The Rockefeller Foundation judges got it right: the Tromsø Nordlysobservatoriet was, and for decades remained, an outstanding scientific investment.
Farrugia, C. J.; Sandholt, P. E.; Denig, W. F.
2013-12-01
By ground - satellite conjunctions across the auroral oval at dusk we study events of dynamical magnetosphere--ionosphere (M-I) coupling from the plasma sheet - ring current system via R1 and R2 field-aligned currents (FACs) during auroral electrojet activations appearing on the poleward and equatorward sides of the Harang reversal (HR), respectively. The interval of ICME passage at Earth we study is characterized by repetitive substorm activity appearing as a series of westward expansions--eastward retreats of the westward electrojet (WEJ) across the 1800 MLT meridian. Harang region-north (HR-N) is characterized by R1 FAC closure, WEJ activity, poleward boundary intensifications (PBIs) - equatorward - moving auroral streamers (inverted V - arcs), and (at different times) poleward auroral expansions. Harang region-south (HR-S) is characterized by R2 FAC closure leading to eastward electrojet (EEJ) activity and precipitation in the southern auroral branch. Using this approach we documented the detailed temporal evolution of polar cap convection, as derived from the PCN index, in relation to direct observations of the dynamical behaviour of the two basic branches of the substorm current system, i. e. the R2 FAC coupling from the partial ring current (PRC) and the R1 FAC coupling from the plasma sheet. We distinguish between two activity levels: (i) major AL-excursions beyond -1000 nT (accompanied by large-scale field dipolarizations in the inner magnetotail), followed by SYM-H dips (plasma injections enhancing the PRC) and R2 FAC - EEJ enhancements, and (ii) partial AL - recovery (AL within -300 to -600 nT) characterized by a series of M - I coupling events with manifestations on both sides of the HR, including streamer events in HR-N, leading to equatorward/poleward motions of the HR boundary.
Nakamizo, A.; Yoshikawa, A.
2016-12-01
Whereas it is generally thought that Birkeland Currents (FACs) are generated in the magnetosphere and that the ionospheric convection reflects the magnetospheric convection, we present a possibility that the ionosphere drives FACs and the convection field in the M-I system. We apply this idea to the Harang Reversal (HR) for demonstration. By using an ionospheric potential solver we calculate the electrostatic field for given distributions of FACs and conductance. The result shows that a conspicuous structure resembling HR is generated even for a symmetric distribution of the R1-type FACs and that the Hall polarization field is produced at the equatorward boundary of the auroral region as the primary currents diverge/converge at the conductance gradient there, which causes the potential deformation (HR). Conventionally HR has been considered to be of the magnetospheric origin, and a ring current model actually produces the corresponding structure in the magnetosphere [e.g., Erickson et al., 1991]. Observationally the divE equivalent to HR is consistent with the premidnight upward-FAC seen in Iijima and Potemra's diagram. A recent theoretical study [Ohtani et al., 2016] proposes that HR is a required structure for the interchange stability of the magnetotail in the presence of the R1 and R2-FAC systems including a premidnight upward-FAC. Returning to our result, the important point is that HR is reproduced at the conductance edge by the ionospheric polarization field, for which the primary field originates from the R1-FACs distributed far from that region. We also suggest: (i) In a more realistic finite ΣA, the total ionospheric polarization is partly released by a FAC, which may be a part of the premidnight upward-FAC. (ii) However, existing simulation models do not allow this type of current closure, and accordingly they may enhance the HR structure in the magnetosphere. This discussion should hold generally and would promote the global M-I coupling studies to the
Discontinuous symplectic capacities
Zehmisch, K.; Ziltener, F.J.
2014-01-01
We show that the spherical capacity is discontinuous on a smooth family of ellipsoidal shells. Moreover, we prove that the shell capacity is discontinuous on a family of open sets with smooth connected boundaries.
Organising medication discontinuation
Nixon, Michael; Kousgaard, Marius Brostrøm
2016-01-01
Background: Discontinuing medications is a complex decision making process and an important medical practice. It is a tool in reducing polypharmacy, reducing health system expenditure and improving patient quality of life. Few studies have looked at how general practitioners (GPs) discontinue...... a medication, in agreement with the patients, from a professional perspective. Three research questions were examined in this study: when does medication discontinuation occur in general practice, how is discontinuing medication handled in the GP’s practice and how do GPs make decisions about discontinuing...... medication? Methods: Twenty four GPs were interviewed using a maximum variation sample strategy. Participant observations were done in three general practices, for one day each, totalling approximately 30 consultations. Results: The results show that different discontinuation cues (related to the type...
Controllability of Discontinuous Systems
Veliov, V. M.; Krastanov, M.
1988-01-01
This report presents an approach to the local controllability problem for a discontinuous system. The approach is based on a concept of tangent vector field to a generalized dynamic system, which makes possible the differential geometry tools to be applied in the discontinuous case. Sufficient controllability conditions are derived.
Pratelli, Aldo
2016-01-01
This book presents a series of lectures on three of the best known examples of free discontinuity problems: the Mumford-Shah model for image segmentation, a variational model for the epitaxial growth of thin films, and the sharp interface limit of the Ohta-Kawasaki model for pattern formation in dyblock copolymers.
IS DISCONTINUOUS BERGSONISM POSSIBLE?
TERESA CASTELÃO-LAWLESS
2010-11-01
Full Text Available Gaston Bachelard’s position toward the philosophy of Henri Bergson is most interesting. In La Dialectique de la durée (1936, Bachelard claims that “of Bergsonism we accept everything but continuity” and that the rest of his book will be an attempt to show the possibility of a “discontinuous Bergsonism”. In this paper, I focus on the reaction of Bachelard to works of Bergson such as the Essai sur les données immédiates de la conscience (1889, L’Evolution créatrice (1907, and Durée et simultanéité: à propos de la théorie d’Einstein (1922 and demonstrate that even though the conditions necessary for the possibility of a discontinuous Bergsonism are not the same ones which Bachelard had in mind when he accepted most of Bergsonism, their phenomenologies of the scientific spirit were analogous.
System dynamics with interaction discontinuity
Luo, Albert C J
2015-01-01
This book describes system dynamics with discontinuity caused by system interactions and presents the theory of flow singularity and switchability at the boundary in discontinuous dynamical systems. Based on such a theory, the authors address dynamics and motion mechanism of engineering discontinuous systems due to interaction. Stability and bifurcations of fixed points in nonlinear discrete dynamical systems are presented, and mapping dynamics are developed for analytical predictions of periodic motions in engineering discontinuous dynamical systems. Ultimately, the book provides an alternative way to discuss the periodic and chaotic behaviors in discontinuous dynamical systems.
Testing discontinuities in nonparametric regression
Dai, Wenlin
2017-01-19
In nonparametric regression, it is often needed to detect whether there are jump discontinuities in the mean function. In this paper, we revisit the difference-based method in [13 H.-G. Müller and U. Stadtmüller, Discontinuous versus smooth regression, Ann. Stat. 27 (1999), pp. 299–337. doi: 10.1214/aos/1018031100
Mixing of discontinuously deforming media
Smith, Lachlan D; Lester, Daniel R; Metcalfe, Guy
2016-01-01
Mixing of materials is fundamental to many natural phenomena and engineering applications. The presence of discontinuous deformations - such as shear banding or wall slip - creates new mechanisms for mixing and transport beyond those predicted by classical dynamical systems theory. Here we show how a novel mixing mechanism combining stretching with cutting and shuffling yields exponential mixing rates, quantified by a positive Lyapunov exponent, an impossibility for systems with cutting and shuffling alone or bounded systems with stretching alone, and demonstrate it in a fluid flow. While dynamical systems theory provides a framework for understanding mixing in smoothly deforming media, a theory of discontinuous mixing is yet to be fully developed. New methods are needed to systematize, explain and extrapolate measurements on systems with discontinuous deformations. Here we investigate 'webs' of Lagrangian discontinuities and show that they provide a template for the overall transport dynamics. Considering sl...
Mixing of discontinuously deforming media
Smith, L. D.; Rudman, M.; Lester, D. R.; Metcalfe, G.
2016-02-01
Mixing of materials is fundamental to many natural phenomena and engineering applications. The presence of discontinuous deformations—such as shear banding or wall slip—creates new mechanisms for mixing and transport beyond those predicted by classical dynamical systems theory. Here, we show how a novel mixing mechanism combining stretching with cutting and shuffling yields exponential mixing rates, quantified by a positive Lyapunov exponent, an impossibility for systems with cutting and shuffling alone or bounded systems with stretching alone, and demonstrate it in a fluid flow. While dynamical systems theory provides a framework for understanding mixing in smoothly deforming media, a theory of discontinuous mixing is yet to be fully developed. New methods are needed to systematize, explain, and extrapolate measurements on systems with discontinuous deformations. Here, we investigate "webs" of Lagrangian discontinuities and show that they provide a template for the overall transport dynamics. Considering slip deformations as the asymptotic limit of increasingly localised smooth shear, we also demonstrate exactly how some of the new structures introduced by discontinuous deformations are analogous to structures in smoothly deforming systems.
The structure of rotational discontinuities
Neugebauer, M. (California Institute of Technology, Pasadena (USA))
1989-11-01
This study examines the structures of a set of rotational discontinuities detected in the solar wind by the ISEE-3 spacecraft. It is found that the complexity of the structure increases as the angle {theta} between the propagation vector k and the magnetic field decreases. For rotational discontinuities that propagate at a large angle to the field with an ion (left-hand) sense of rotation, the magnetic hodograms tend to be flattened, in agreement with prior numerical simulations. When {theta} is large, angular overshoots are often observed at one or both ends of the discontinuity. When the propagation is nearly parallel to the field (i.e., when {theta} is small), many different types of structure are seen, ranging from straight lines, the S-shaped curves, to complex, disorganized shapes.
Constrained Optimization of Discontinuous Systems
Y.M. Ermoliev; V.I. Norkin
1996-01-01
In this paper we extend the results of Ermoliev, Norkin and Wets [8] and Ermoliev and Norkin [7] to the case of constrained discontinuous optimization problems. In contrast to [7] the attention is concentrated on the proof of general optimality conditions for problems with nonconvex feasible sets. Easily implementable random search technique is proposed.
Strategies for discontinuation of proton pump inhibitors
Haastrup, Peter; Paulsen, Maja S; Begtrup, Luise M
2014-01-01
PURPOSE: Proton pump inhibitors (PPIs) are considered to be overprescribed. Consensus on how to attempt discontinuation is, however, lacking. We therefore conducted a systematic review of clinical studies on discontinuation of PPIs. METHODS: Systematic review based on clinical studies investigating...
Discontinuities in recurrent neural networks.
Gavaldá, R; Siegelmann, H T
1999-04-01
This article studies the computational power of various discontinuous real computational models that are based on the classical analog recurrent neural network (ARNN). This ARNN consists of finite number of neurons; each neuron computes a polynomial net function and a sigmoid-like continuous activation function. We introduce arithmetic networks as ARNN augmented with a few simple discontinuous (e.g., threshold or zero test) neurons. We argue that even with weights restricted to polynomial time computable reals, arithmetic networks are able to compute arbitrarily complex recursive functions. We identify many types of neural networks that are at least as powerful as arithmetic nets, some of which are not in fact discontinuous, but they boost other arithmetic operations in the net function (e.g., neurons that can use divisions and polynomial net functions inside sigmoid-like continuous activation functions). These arithmetic networks are equivalent to the Blum-Shub-Smale model, when the latter is restricted to a bounded number of registers. With respect to implementation on digital computers, we show that arithmetic networks with rational weights can be simulated with exponential precision, but even with polynomial-time computable real weights, arithmetic networks are not subject to any fixed precision bounds. This is in contrast with the ARNN that are known to demand precision that is linear in the computation time. When nontrivial periodic functions (e.g., fractional part, sine, tangent) are added to arithmetic networks, the resulting networks are computationally equivalent to a massively parallel machine. Thus, these highly discontinuous networks can solve the presumably intractable class of PSPACE-complete problems in polynomial time.
Discontinuous mixed covolume methods for parabolic problems.
Zhu, Ailing; Jiang, Ziwen
2014-01-01
We present the semidiscrete and the backward Euler fully discrete discontinuous mixed covolume schemes for parabolic problems on triangular meshes. We give the error analysis of the discontinuous mixed covolume schemes and obtain optimal order error estimates in discontinuous H(div) and first-order error estimate in L(2).
Observations of double discontinuities in the magnetotail
Whang, Y. C.; Fairfield, D.; Smith, E. J.; Lepping, R. P.; Kokubun, S.; Saito, Y.
Observations of slow shocks in the Earth's magnetotail at the plasma sheet-lobe boundaries have been well documented. We restudy the magnetic field data of two slow shocks: one was observed from Geotail on January 17, 1994 at XGSE = -92 RE, and another was observed from ISEE-3 on February 2, 1983 at XGSE = -220 RE. In both cases, the slow shock layer was followed by an adjoining rotational discontinuity layer on the postshock side. Compound structures each composed of a slow shock layer and an adjoining rotational discontinuity layer have been recently observed in interplanetary space from Wind, Geotail and Imp-8. Because the two successive discontinuities are very close to each other, the compound structure looks like a new kind of MHD discontinuity. It may be called a double discontinuity. Since double discontinuities exist not only in interplanetary space but also in the magnetotail region, they could be a general MHD structure in space plasma.
Spatially discontinuous ionization phenomenon in inhomogeneous soil
无
2010-01-01
By using X-ray film imaging technology,a phenomenon of discontinuous ionization was observed in the inhomogeneous soil around the grounding electrode on which a surge voltage was applied.A simplified two-phase solid-gas model was built to study the electric field distribution in the soil to explain the discontinuous ionization phenomenon.Analysis showed the differences of the dielectric properties,the shapes and sizes of soil particles can cause discontinuous ionization in the soil.
Discontinuities during UV writing of waveguides
Svalgaard, Mikael; Harpøth, Anders; Andersen, Marc
2005-01-01
UV writing of waveguides can be hampered by discontinuities where the index change process suddenly shuts down. We show that thermal effects may account for this behaviour.......UV writing of waveguides can be hampered by discontinuities where the index change process suddenly shuts down. We show that thermal effects may account for this behaviour....
A generalized discrete strong discontinuity approach
Dias-da-Costa, D.; Alfaiate, J.; Sluys, L.J.; Julio, E.
2010-01-01
Several local embedded discontinuity formulations have already been developed, in which constant strain triangles and constant jumps are adopted. However, these formulations lead to jump and traction discontinuity across element boundaries and stress locking effects. Herein, a new contribution to em
Forecasting Technological Discontinuities in the ICT Industry
Hoisl, Karin; Stelzer, Tobias; Biala, Stefanie
2015-01-01
Building on the existing literature on evolutionary innovation and technological change, this paper aims to identify potential signals of technological discontinuities and to obtain assessments of experts to what extent these signals help them to predict discontinuities. Furthermore, we analyze...... in the ICT industry. The conjoint approach allows for a simulation of the forecasting process and considers utility trade-offs. The results show that for both types of experts the perceived benefit of users most highly contributes to predicting technological discontinuities. Internal experts assign more...... insights to the literature on R&D and innovation management....
Discontinuation of Preventive Drugs in General Practice
Andersen, John Sahl; Lindberg, Laura Maria Glahder; Nixon, Michael Simon
the most preventive drugs are prescribed in general practice. Special considerations exist in relation to medication of elderly patients. The prevalence of polypharmacy and the subsequent increased risk of side effects and drug interactions is high. Drug-related problems represent the fifth leading cause...... of death in the United States. The public expenses to drug treatment are constantly increasing. The possibility to withdraw the medication must be taken into account but the decision to discontinue drugs is complex and poorly understood. Planned studies: 1. Patients’ views upon discontinuation...... of preventive drugs. Qualitative interviews with patients experiencing discontinuation of preventive drugs addressing: Which attitudes do the patients have towards preventive drugs? Which thoughts do the patients have in relation to discontinuation of the drugs? How do they understand their own and the GP...
Beam Coupling Impedances of Small Discontinuities
Kurennoy, S S
2000-01-01
A general derivation of the beam coupling impedances produced by small discontinuities on the wall of the vacuum chamber of an accelerator is reviewed. A collection of analytical formulas for the impedances of small obstacles is presented.
Discontinuous spirals of stable periodic oscillations.
Sack, Achim; Freire, Joana G; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A C
2013-11-27
We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators.
Discontinuous Spirals of Stable Periodic Oscillations
Sack, Achim; Freire, Joana G.; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A. C.
2013-01-01
We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators. PMID:24284508
Discontinuous Galerkin for the Radiative Transport Equation
Guermond, Jean-Luc
2013-10-11
This note presents some recent results regarding the approximation of the linear radiative transfer equation using discontinuous Galerkin methods. The locking effect occurring in the diffusion limit with the upwind numerical flux is investigated and a correction technique is proposed.
Conforming finite elements with embedded strong discontinuities
Dias-da-Costa, D.; Alfaiate, J.; Sluys, L.J.; Areias, P.; Fernandes, C.; Julio, E.
2012-01-01
The possibility of embedding strong discontinuities into finite elements allowed the simulation of different problems, namely, brickwork masonry fracture, dynamic fracture, failure in finite strain problems and simulation of reinforcement concrete members. However, despite the significant contributi
Improved Edge Awareness in Discontinuity Preserving Smoothing
Heinrich, Stuart B
2011-01-01
Discontinuity preserving smoothing is a fundamentally important procedure that is useful in a wide variety of image processing contexts. It is directly useful for noise reduction, and frequently used as an intermediate step in higher level algorithms. For example, it can be particularly useful in edge detection and segmentation. Three well known algorithms for discontinuity preserving smoothing are nonlinear anisotropic diffusion, bilateral filtering, and mean shift filtering. Although slight differences make them each better suited to different tasks, all are designed to preserve discontinuities while smoothing. However, none of them satisfy this goal perfectly: they each have exception cases in which smoothing may occur across hard edges. The principal contribution of this paper is the identification of a property we call edge awareness that should be satisfied by any discontinuity preserving smoothing algorithm. This constraint can be incorporated into existing algorithms to improve quality, and usually ha...
Neural networks with discontinuous/impact activations
Akhmet, Marat
2014-01-01
This book presents as its main subject new models in mathematical neuroscience. A wide range of neural networks models with discontinuities are discussed, including impulsive differential equations, differential equations with piecewise constant arguments, and models of mixed type. These models involve discontinuities, which are natural because huge velocities and short distances are usually observed in devices modeling the networks. A discussion of the models, appropriate for the proposed applications, is also provided. This book also: Explores questions related to the biological underpinning for models of neural networks\\ Considers neural networks modeling using differential equations with impulsive and piecewise constant argument discontinuities Provides all necessary mathematical basics for application to the theory of neural networks Neural Networks with Discontinuous/Impact Activations is an ideal book for researchers and professionals in the field of engineering mathematics that have an interest in app...
Discontinuance of ADHD Treatment in Adolescents
J Gordon Millichap
2009-04-01
Full Text Available Prevalence of ADHD drug discontinuance in adolescents and young adults was studied in the UK by using the General Practice Database for patients aged 15-21 years from 1999 to 2006.
On stochastic and discontinuous optimization methods
Ermoliev, Y.
1994-12-31
The talk is based on a joint article by Y. Ermoliev, V. Norkin and R. Wets. A new notion of subgradient is introduced which allows to develop easily implementable procedures of discontinuous optimization, in particular, finite-difference approximation schemes. The approach relies on the notion of differentiability in the sense of distributions converting a discontinuous optimization problem into a problem of the stochastic optimization. Applications involving risks and abrupt transitions are discussed.
Variations of Hales Discontinuity beneath South India
Goyal, Ayush; Kosre, Goukaran Kumar; Borah, Kajaljyoti
2016-04-01
Thermodynamic studies show the spinel-garnet transition in fertile and hot mantle should be relatively narrow and should show up in the seismological studies as a discontinuity. The evidence for a shallow lithospheric mantle discontinuity was first proposed by Hales (1969) based on seismological travel time measurement from the Early Rise experiment in the Central United States, where a ~4% increase in the S-wave velocity at a depth of 75 km was observed. The recent studies show, in cratonic blocks with colder geotherms, that it appears at greater depths and over broader intervals, that is, from the Moho to 150 km depth. Different studies interpreted that Hales discontinuity may be due to seismic anisotropy or pervasive partial melts or cation ordering in mantle olivine. In the present study an attempt is made to model the Hales discontinuity in the South Indian shield, by jointly inverting group velocity dispersion and receiver functions, calculated from teleseismic earthquakes recorded at 20 broadband seismograph locations in the study region. South Indian shield is an amalgamation of several crustal blocks, namely, Eastern Dharwar Craton (EDC), Western Dharwar Craton (WDC), Southern Granulite Terrain (SGT) etc. Inversion modeling results show deeper Hales discontinuity (~104-110 km depth) in the south of WDC and SGT, while in the north of Western Dharwar Craton and Eastern Dharwar Craton it varies from ~70-80 km. It is also observed that the Hales Discontinuity is present at greater depth in the western part of Dharwar Craton, compared to the eastern part. Details of the depth, thickness, and the cause of the Hales discontinuity are also investigated. Keywords: Hales Discontinuity, South Indian Shield, Receiver Function, Craton, Inversion modeling.
Discontinuities of multi-Regge amplitudes
Fadin, V S
2014-01-01
In the BFKL approach, discontinuities of multiple production amplitudes in invariant masses of produced particles are discussed. It turns out that they are in evident contradiction with the BDS ansatz for $n$-gluon amplitudes in the planar $N$=4 SYM at $n\\ge 6$. An explicit expression for the NLO discontinuity of the two-to-four amplitude in the invariant mass of two produced gluons is is presented.
Discontinuous Galerkin Method for Hyperbolic Conservation Laws
Mousikou, Ioanna
2016-11-11
Hyperbolic conservation laws form a special class of partial differential equations. They describe phenomena that involve conserved quantities and their solutions show discontinuities which reflect the formation of shock waves. We consider one-dimensional systems of hyperbolic conservation laws and produce approximations using finite difference, finite volume and finite element methods. Due to stability issues of classical finite element methods for hyperbolic conservation laws, we study the discontinuous Galerkin method, which was recently introduced. The method involves completely discontinuous basis functions across each element and it can be considered as a combination of finite volume and finite element methods. We illustrate the implementation of discontinuous Galerkin method using Legendre polynomials, in case of scalar equations and in case of quasi-linear systems, and we review important theoretical results about stability and convergence of the method. The applications of finite volume and discontinuous Galerkin methods to linear and non-linear scalar equations, as well as to the system of elastodynamics, are exhibited.
Discontinuation Decision in Assisted Reproductive Techniques
Ashraf Moini
2009-01-01
Full Text Available Background: In vitro fertilization (IVF and intra cytoplasmic sperm injection (ICSI are recognizedas established and increasingly successful forms of treatment for infertility, yet significant numbersof couples discontinue treatment without achieving a live birth. This study aims to identify majorfactors that influence the decision to discontinue IVF/ICSI treatments.Materials and Methods: We studied the data of 338 couples who discontinued their infertilitytreatments after three cycles; based on medical records and phone contact. The main measure wasthe reason for stopping their treatments.Results: Economical problems were cited by 212 couples (62.7%, as their mean income wassignificantly less than other couples (p<0.0001. Lack of success was reported as a reason by229 (67.8%, from whom 165 (72% also had economical problems. Achieving independent-ART pregnancy was the reason for discontinuation in 20 (5.9% couples. Psychological stress,depression and anxiety were reported as other cessation factors by 169 (50%, 148 (43.8% and 182(53.8% couples, respectively.Conclusion: This survey suggests that the most common reasons for assisted reproductivetechnique (ART discontinuation after three cycles are: prior unsuccessful cycles, economicaland psychological problems. Therefore, the substantial proportion of couples could benefit frompsychological intervention, increasing awareness of ART outcomes and health funding to copemore adequately with failed treatments.
27 CFR 555.128 - Discontinuance of business.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Discontinuance of business. Where an explosive materials business or operations is discontinued and succeeded by... such facts and shall be delivered to the successor. Where discontinuance of the business or operations...
27 CFR 478.127 - Discontinuance of business.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Records § 478.127 Discontinuance of business. Where a licensed business is discontinued and succeeded by a... be delivered to the successor. Where discontinuance of the business is absolute, the records shall be...
27 CFR 478.57 - Discontinuance of business.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Discontinuance of business... Licenses § 478.57 Discontinuance of business. (a) Where a firearm or ammunition business is either discontinued or succeeded by a new owner, the owner of the business discontinued or succeeded shall within 30...
PLASTIC LIMIT ANALYSIS OF DISCONTINUOUS LINING UNDERGROUND PRESSURE
龙春安
1999-01-01
Discontinuous lining is a special form of support in underground excavation. Based on the method of plastic limit analysis, it is found the upper and the lower bound solution of the pressure of circular discontinuous lining and discussed support parameter of discontinuous lining and its applicable conditions, which provides theoretical basis for the design and calculation of discontinuous lining.
Method for simulating discontinuous physical systems
Baty, Roy S.; Vaughn, Mark R.
2001-01-01
The mathematical foundations of conventional numerical simulation of physical systems provide no consistent description of the behavior of such systems when subjected to discontinuous physical influences. As a result, the numerical simulation of such problems requires ad hoc encoding of specific experimental results in order to address the behavior of such discontinuous physical systems. In the present invention, these foundations are replaced by a new combination of generalized function theory and nonstandard analysis. The result is a class of new approaches to the numerical simulation of physical systems which allows the accurate and well-behaved simulation of discontinuous and other difficult physical systems, as well as simpler physical systems. Applications of this new class of numerical simulation techniques to process control, robotics, and apparatus design are outlined.
Discontinuous Spirals of Stable Periodic Oscillations
Sack, Achim; Freire, Joana G.; Lindberg, Erik
2013-01-01
We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...... orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy...... specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization...
Identification of discontinuities in plasma plume evolution
Gojani, Ardian B; Obayashi, Shigeru
2013-01-01
The ejection of material during laser ablation gives rise to the development of discontinuities in the ambient gas. Several of these discontinuities are observed and characterized, including externally and internally propagating shock waves, contact surface, and the ionization front. Qualitative experimental observations and analysis of these discontinuities is presented. Results from shadowgraphy enabled determination of an irradiance threshold between two different ablation mechanisms, and determination of several stages of plasma plume evolution. Consideration of the refractive index as a dynamic sum of the contributions from gas and electrons led to separate identification of ionization front from the contact surface. Furthermore, ionization front was observed to lead the shock wave at the earlier stage of the ablation.
Rockburst Generation in Discontinuous Rock Masses
He, Ben-Guo; Zelig, Ravit; Hatzor, Yossef H.; Feng, Xia-Ting
2016-10-01
We study rockburst generation in discontinuous rock masses using theoretical and numerical approaches. We begin by developing an analytical solution for the energy change due to tunneling in a continuous rock mass using linear elasticity. We show that the affected zone where most of the increase in elastic strain energy takes place is restricted to an annulus that extends to a distance of three diameters from the tunnel center, regardless of initial tunnel diameter, magnitude of in situ stress, and in situ stress ratio. By considering local elastic strain concentrations, we further delineate the Rockbursting Prone Zone found to be concentrated in an annulus that extends to one diameter from the tunnel center, regardless of original stress ratio, magnitude, and the stiffness of the rock mass. We proceed by arguing that in initially discontinuous rock masses shear stress amplification due to tunneling will inevitably trigger block displacements along preexisting discontinuities much before shear failure of intact rock elements will ensue, because of the lower shear strength of discontinuities with respect to intact rock elements, provided of course that the blocks are removable. We employ the numerical discrete element DDA method to obtain, quantitatively, the kinetic energy, the elastic strain energy, and the dissipated energy in the affected zone in a discontinuous rock due to tunneling. We show that the kinetic energy of ejected blocks due to strain relaxation increases with increasing initial stress and with decreasing frictional resistance of preexisting discontinuities. Finally, we demonstrate how controlled strain energy release by means of top heading and bench excavation methodology can assist in mitigating rockburst hazards due to stain relaxation.
Current discontinuities on superconducting cosmic strings
Troyan, E., E-mail: et@iaaru.astronautiko.org; Vlasov, Yu. V. [Moscow Institute of Physics and Technology (Russian Federation)
2011-07-15
The propagation of current perturbations on superconducting cosmic strings is considered. The conditions for the existence of discontinuities similar to shock waves have been found. The formulas relating the string parameters and the discontinuity propagation speed are derived. The current growth law in a shock wave is deduced. The propagation speeds of shock waves with arbitrary amplitudes are calculated. The reason why there are no shock waves in the case of time-like currents (in the 'electric' regime) is explained; this is attributable to the shock wave instability with respect to perturbations of the string world sheet.
Discontinuity-preserving optical flow algorithm
Yuan Lei; Li Jinzong; Li Dongdong
2007-01-01
A modification of Horn and Schunk's approach is investigated, which leads to a better preservation of flow discontinuities.It improves Horn-Schunk model in three aspects: (1) It replaces the smooth weight coefficient in the energy equation by the variable weight coefficient.(2) It adopts a novel method to compute the mean velocity.The novel method also reflects the effect of the intensity difference on the image velocity diffusion.(3) It introduces a more efficient iterative method than the Gauss-Seidel method to solve the associated Euler-Lagrange equation.The experiment results validate the better effect of the improved method on preserving discontinuities.
Discontinuity effects on radial cavity transmission lines
Seidel, D.B.
1979-04-01
Pulse propagation in radial cavity transmission lines such as those found on a radial line accelerator is considered. Specifically, the effects of discontinuities along the line are examined in detail. It is found that previous analyses of such effects have been incorrect, and here two alternate solution techniques are presented. Depending upon the parameters of such a radial line, the discontinuity effects considered here may or may not be significant; however, if they are significant, it is recommended that the alternate solution techniques presented here be used.
77 FR 26185 - POSTNET Barcode Discontinuation
2012-05-03
... From the Federal Register Online via the Government Publishing Office ] POSTAL SERVICE 39 CFR Part 111 POSTNET Barcode Discontinuation AGENCY: Postal Service TM . ACTION: Final rule. SUMMARY: The... March 2, 2012, the Postal Service published a proposed rule in the Federal Register (77 FR 12764-12769...
Problems with Discontinuous Diffusion/Dispersion Coefficients
Stefano Ferraris
2012-01-01
accurate on smooth solutions and based on a special numerical treatment of the diffusion/dispersion coefficients that makes its application possible also when such coefficients are discontinuous. Numerical experiments confirm the convergence of the numerical approximation and show a good behavior on a set of benchmark problems in two space dimensions.
General practitioners’ decisions about discontinuation of medication
Nixon, Michael Simon; Vendelø, Morten Thanning
2016-01-01
Purpose – The purpose of this paper is to investigate how general practitioners’ (GPs) decisions about discontinuation of medication are influenced by their institutional context. Design/methodology/approach – In total, 24 GPs were interviewed, three practices were observed and documents were col...
Continuous-Discontinuous Modelling of Failure
Simone, A.
2003-01-01
The foundations of a safe structural design lie on the understanding of failure processes of engineering materials and in their correct representation. In a numerical context, failure representation in engineering materials can be pursued either in a continuous or in a discontinuous setting. Both ap
ELECTRIC FIELD MEASUREMENT IN ROD-DISCONTINUED ...
2014-06-30
Jun 30, 2014 ... The used arrangement with homogeneous system is made up of a square metallic sheet ... This distance is considered positive when the rod is located ... in the case of the discontinuous earth which were defined according to ...
An equilibrium closure result for discontinuous games
Balder, E.J.
2011-01-01
For games with discontinuous payoffs Simon and Zame (1990) introduced payoff indeterminacy, in the form of endogenous sharing rules, which are measurable selections of a certain payoff correspondence. Their main result concerns the existence of a mixed Nash equilibrium and an associated sharing
Olanzapine discontinuation emergent recurrence in bipolar disorder
Manu Arora
2014-01-01
Full Text Available Objective: The efficacy of atypical antipsychotics including olanzapine in acute treatment of manic episode has been established, whereas its role in maintenance treatment is not clear. Materials and Methods: Thirteen patients of bipolar disorder who were on regular treatment with mood stabilizer and subsequently relapsed into mania or depressive episode after discontinuation of olanzapine were studied for various socio-demographic and clinical factors using retrospective chart review. Results: There was no correlation found between the period of tapering olanzapine, time to recurrence of episode after discontinuation, and the dosage of olanzapine at the time of discontinuation. The predominant early signs of relapse after discontinuation of olanzapine included sleep disturbance (72.7%, lack of insight for change in behavior (72.7%, irritability (54.5%, and elevated mood (45.5%. Conclusion: Mood stabilizer alone as a maintenance therapy of bipolar disorder may be inadequate for long-term management. A low dose of olanzapine along with mood stabilizers might be useful for prevention of recurrence in bipolar disorder.
Discontinued drugs in 2008: endocrine and metabolic.
Colca, Jerry R
2009-09-01
This perspective summarizes key compounds from the endocrine and metabolic area that were discontinued during the calendar year 2008. This is a continuation in a series of perspectives of each of the editorial areas summarized by Expert Opinion on Investigational Drugs. The candidates covered in this summary were being developed for the treatment of diabetes, diabetic complications, anti-atherosclerosis and obesity.
Unstructured discontinuous Galerkin for seismic inversion.
van Bloemen Waanders, Bart Gustaaf; Ober, Curtis Curry; Collis, Samuel Scott
2010-04-01
This abstract explores the potential advantages of discontinuous Galerkin (DG) methods for the time-domain inversion of media parameters within the earth's interior. In particular, DG methods enable local polynomial refinement to better capture localized geological features within an area of interest while also allowing the use of unstructured meshes that can accurately capture discontinuous material interfaces. This abstract describes our initial findings when using DG methods combined with Runge-Kutta time integration and adjoint-based optimization algorithms for full-waveform inversion. Our initial results suggest that DG methods allow great flexibility in matching the media characteristics (faults, ocean bottom and salt structures) while also providing higher fidelity representations in target regions. Time-domain inversion using discontinuous Galerkin on unstructured meshes and with local polynomial refinement is shown to better capture localized geological features and accurately capture discontinuous-material interfaces. These approaches provide the ability to surgically refine representations in order to improve predicted models for specific geological features. Our future work will entail automated extensions to directly incorporate local refinement and adaptive unstructured meshes within the inversion process.
Excursions in fluvial (dis)continuity
Grant, Gordon E.; O'Connor, James E.; Safran, Elizabeth
2017-01-01
Lurking below the twin concepts of connectivity and disconnectivity are their first, and in some ways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in landscapes and rivers. We examine the historical roots of continuum and discontinuum thinking, and how much of our understanding of geomorphology rests on contrasting views of continuity and discontinuity. By continuum thinking we refer to a conception of geomorphic processes as well as geomorphic features that are expressed along continuous gradients without abrupt changes, transitions, or thresholds. Balance of forces, graded streams, and hydraulic geometry are all examples of this perspective. The continuum view has played a prominent role in diverse disciplinary fields, including ecology, paleontology, and evolutionary biology, in large part because it allows us to treat complex phenomena as orderly progressions and invoke or assume equilibrium processes that introduce order and prediction into our sciences.In contrast the discontinuous view is a distinct though complementary conceptual framework that incorporates non-uniform, non-progressive, and non-equilibrium thinking into understanding geomorphic processes and landscapes. We distinguish and discuss examples of three different ways in which discontinuous thinking can be expressed: 1) discontinuous spatial arrangements or singular events; 2) specific process domains generally associated with thresholds, either intrinsic or extrinsic; and 3) physical dynamics or changes in state, again often threshold-linked. In moving beyond the continuous perspective, a fertile set of ideas comes into focus: thresholds, non-equilibrium states, heterogeneity, catastrophe. The range of phenomena that is thereby opened up to scientific exploration similarly expands
In-process discontinuity detection during friction stir welding
Shrivastava, Amber
The objective of this work is to develop a method for detecting the creation of discontinuities (e.g., voids) during friction stir welding. Friction stir welding is inherently cost-effective, however, the need for significant weld inspection can make the process cost-prohibitive. A new approach to weld inspection is required -- where an in-situ characterization of weld quality can be obtained, reducing the need for post-process inspection. Friction stir welds with discontinuity and without discontinuity were created. In this work, discontinuities are generated by reducing the friction stir tool rotation frequency and increasing the tool traverse speed in order to create "colder" welds. During the welds, forces are measured. Discontinuity sizes for welds are measured by computerized tomography. The relationship between the force transients and the discontinuity sizes indicate that the force measurement during friction stir welding can be effectively used for detecting discontinuities in friction stir welds. The normalized force transient data and normalized discontinuity size are correlated to develop a criterion for discontinuity detection. Additional welds are performed to validate the discontinuity detection method. The discontinuity sizes estimated by the force measurement based method are in good agreement with the discontinuity sizes measured by computerized tomography. These results show that the force measurement based discontinuity detection model method can be effectively used to detect discontinuities during friction stir welding.
Spacetime Meshing for Discontinuous Galerkin Methods
Thite, Shripad Vidyadhar
2008-01-01
Spacetime discontinuous Galerkin (SDG) finite element methods are used to solve such PDEs involving space and time variables arising from wave propagation phenomena in important applications in science and engineering. To support an accurate and efficient solution procedure using SDG methods and to exploit the flexibility of these methods, we give a meshing algorithm to construct an unstructured simplicial spacetime mesh over an arbitrary simplicial space domain. Our algorithm is the first spacetime meshing algorithm suitable for efficient solution of nonlinear phenomena in anisotropic media using novel discontinuous Galerkin finite element methods for implicit solutions directly in spacetime. Given a triangulated d-dimensional Euclidean space domain M (a simplicial complex) and initial conditions of the underlying hyperbolic spacetime PDE, we construct an unstructured simplicial mesh of the (d+1)-dimensional spacetime domain M x [0,infinity). Our algorithm uses a near-optimal number of spacetime elements, ea...
Archetypal oscillator for smooth and discontinuous dynamics.
Cao, Qingjie; Wiercigroch, Marian; Pavlovskaia, Ekaterina E; Grebogi, Celso; Thompson, J Michael T
2006-10-01
We propose an archetypal system to investigate transitions from smooth to discontinuous dynamics. In the smooth regime, the system bears significant similarities to the Duffing oscillator, exhibiting the standard dynamics governed by the hyperbolic structure associated with the stationary state of the double well. At the discontinuous limit, however, there is a substantial departure in the dynamics from the standard one. In particular, the velocity flow suffers a jump in crossing from one well to another, caused by the loss of local hyperbolicity due to the collapse of the stable and unstable manifolds of the stationary state. In the presence of damping and external excitation, the system has coexisting attractors and also a chaotic saddle which becomes a chaotic attractor when a smoothness parameter drops to zero. This attractor can bifurcate to a high-period periodic attractor or a chaotic sea with islands of quasiperiodic attractors depending on the strength of damping.
High-temperature discontinuously reinforced aluminum
Zedalis, M. S.; Bryant, J. D.; Gilman, P. S.; Das, S. K.
1991-08-01
High-temperature discontinuously reinforced aluminum (HTDRA) composites have been developed for elevated-temperature applications by incorporating SiC particulate reinforcement into a rapidly solidified, high-temperature Al-Fe-V-Si (alloy 8009) matrix. HTDRA combines the superior elevated-temperature strength, stability and corrosion resistance of the 8009 matrix with the excellent specific stiffness and abrasion resistance of the discontinuous SiC particulate reinforcement. On a specific stiffness basis, HTDRA is competitive with Ti-6-Al-4V and 17-4 PH stainless steel to temperatures approaching 480°C. Potential aerospace applications being considered for HTDRA include aircraft wing skins, missile bodies, and miscellaneous engine, spacecraft and hypersonic vehicle components.
Integer Discontinuity of Density Functional Theory
Mosquera, Martin A
2014-01-01
Density functional approximations to the exchange-correlation energy of Kohn-Sham theory, such as the local density approximation and generalized gradient approximations, lack the well-known integer discontinuity, a feature that is critical to describe molecular dissociation correctly. Moreover, standard approximations to the exchange-correlation energy also fail to yield the correct linear dependence of the ground-state energy on the number of electrons when this is a non-integer number obtained from the grand canonical ensemble statistics. We present a formal framework to restore the integer discontinuity of any density functional approximation. Our formalism derives from a formula for the exact energy functional and a new constrained search functional that recovers the linear dependence of the energy on the number of electrons.
Discontinued drugs 2011: endocrine and metabolic.
Colca, Jerry R
2012-11-01
This perspective summarizes key compounds from the endocrine and metabolic area that were discontinued during the calendar year 2011. Metabolic diseases continue to comprise some of the most important, but underserved areas of medical management. The candidates covered in this summary were primarily being developed for treatment of type 2 and type 1 diabetes, obesity and inflammatory gastrointestinal disease. Candidates were identified from a search by informahealthcare including data available on TreasureTrove. Discontinuation of programs during this period include older and newer projects but apparently all suffer from inability to provide timely evidence of clear benefit in clinical trials in the face of growing costs of development. There is a key need for targets that when modulated clearly affect the pathophysiology of the disease in way that is evident early in clinical trials.
Discontinuous Operation of Geothermal Heat Exchangers
方肇洪; 刁乃仁; 崔萍
2002-01-01
Ground-source heat pump (GSHP) systems for HVAC have aroused more and more interest in China in recent years because of their higher energy efficiency compared with conventional systems. The design and performance simulation of the geothermal heat exchangers is vital to the success of this technology. In GSHP systems, the load of the geothermal heat exchanger varies greatly and is usually discontinuous even during a heating or cooling season. This paper outlines a heat transfer model for geothermal heat exchangers. The model was used to study the influence of the discontinuous operation of the heat pumps on the performance of the geothermal heat exchangers. A simple and practical approach is presented for sizing the geothermal heat exchangers.
Mantle discontinuities beneath Izu-Bonin and the implications
臧绍先; 周元泽; 蒋志勇
2003-01-01
The SdP, pdP and sdP phases are picked up with the Nth root slant stack method from the digital waveform data recorded by the networks and arrays in USA, Germany and Switzerland for the earthquakes occurring beneath Izu-Bonin and Japan Sea. The mantle discontinuities and the effects of subducting slab on the 660 km and 410 km discontinuities are studied. It is found that there are mantle discontinuities existing at the depths of 170, 220, 300, 410, 660, 850 and 1150 km. Beneath Izu-Bonin, the 410 km discontinuity is elevated, while the 660 km discontinuity is depressed; for both discontinuities, there are regionalized differences. Beneath Japan Sea, however, there is no depth variation of the 410 km discontinuity, and the 660 km discontinuity is depressed without obvious effect of the subducting slab.
33 CFR 66.01-25 - Discontinuance and removal.
2010-07-01
... Discontinuance and removal. (a) No person, public body or instrumentality shall change, move or discontinue any... body or instrumentality establishing or maintaining such aids when so directed by the...
SENSITIVITY OF DARCY'S LAW TO DISCONTINUITIES
无
2003-01-01
The authors investigate the sensitivity of hydrostatic pressure of flows through porous mediawith respect to the position of the soil layers. Indeed, these induce discontinuities of the porositypressure u and it leads to the computation of the derivative of u with respect to changes inThe analysis relies on a mixed formulation of the problem. Preliminary numerical simu-lations are given to illustrate the theory. An application to a simple inverse problem is also given.
Modeling Storm Surges Using Discontinuous Galerkin Methods
2016-06-01
discontinuous Galerkin solutions of the compressible Euler equations with applications to atmospheric simulations,” Journal of Computational Physics, vol...order continuous Galerkin methods were used for the SWE on a sphere [9]. In 2002, Giraldo et al. [10] introduced an efficient DG method for the SWE... hard time transitioning from changing bathymetry slopes causing distortions in the model to include extra line segments. The discrepancies caused us to
Metabolic effects of discontinuing growth hormone treatment
Cowan, F; Evans, W.; Gregory, J
1999-01-01
AIMS—To evaluate the effects of discontinuing growth hormone (GH) treatment on energy expenditure and body composition, which might help predict those most likely to benefit from early reintroduction of GH treatment in young adult life. METHODS—Body composition was calculated from skinfold thicknesses and dual energy x ray absorptometry (DXA). Resting metabolic rate (RMR) and whole body bone mineral content (BMC) were also measured. Measurements were made before stoppi...
Discontinuities, Feynman parameters and d-lines
Halliday, I G
1977-01-01
The calculation of asymptotic limits of Feynman diagrams using Feynman parameter techniques has developed a powerful and useful technology. A major gap in this armory has concerned the calculation of specific discontinuities of Feynman diagrams. The author remedies this gap and illustrates the new technique on a series of familiar situations. These include in the Regge limit, the ladder and the AFS diagrams, and the x approximately 1 deep inelastic electroproduction region. (4 refs).
Discontinuous precipitation in copper base alloys
K T Kashyap
2009-08-01
Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show DP while others do not. In this paper the misfit strain parameter, , has been calculated and predicted that if 100 > ± 0.1, DP is observed. This criterion points to diffusional coherency strain theory to be the operative mechanism for DP.
Field Discontinuities and the Memory Effect
Tolish, Alexander; Wald, Robert
2017-01-01
The ``memory effect,'' a permanent change in the separation of test particles after the passage of a pulse of gravitational radiation, is a well-defined and fairly well-understood phenomenon in spacetimes with a notion of null infinity. However, many valid questions remain unanswered. For example, how do we define memory in the absence of null infinity? Or, does memory depend on the precise details of the radiation source or just on the source's asymptotic behavior? We believe that such questions are best answered using a simplified, distributional model of memory. If we consider linearized gravity on fixed background spacetimes, we can study the scattering of point particles, which radiate metric perturbations with sharp, step-function wave fronts. These steps correspond to derivative-of-delta-function discontinuities in the curvature, and according to the geodesic deviation equation, it is these discontinuities (and these alone) that contribute to permanent, finite changes in test particle separation-i.e., memory. Using this analysis of field discontinuities (as well as scalar and electromagnetic analogues of gravitational memory) we can isolate the physics of the memory effect from other, background phenomena.
Seismic wave propagation in fractured media: A discontinuous Galerkin approach
De Basabe, Jonás D.
2011-01-01
We formulate and implement a discontinuous Galekin method for elastic wave propagation that allows for discontinuities in the displacement field to simulate fractures or faults using the linear- slip model. We show numerical results using a 2D model with one linear- slip discontinuity and different frequencies. The results show a good agreement with analytic solutions. © 2011 Society of Exploration Geophysicists.
27 CFR 22.68 - Notice of permanent discontinuance.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Notice of permanent discontinuance. 22.68 Section 22.68 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Permanent Discontinuance of Use of Tax-Free Alcohol § 22.68 Notice of permanent discontinuance. A...
Discontinuity effects in dynamically loaded tilting pad journal bearings
Thomsen, Kim; Klit, Peder; Vølund, Anders
2011-01-01
This paper describes two discontinuity effects that can occur when modelling radial tilting pad bearings subjected to high dynamic loads. The first effect to be treated is a pressure build-up discontinuity effect. The second effect is a contact-related discontinuity that disappears when a contact...
Yue Sun
2016-01-01
Full Text Available A novel coupling scheme is presented to combine the discontinuous deformation analysis (DDA and the interior penalty Galerkin (IPG method for the modeling of contacts. The simultaneous equilibrium equations are assembled in a mixed strategy, where the entries are derived from both discontinuous Galerkin variational formulations and the strain energies of DDA contact springs. The contact algorithms of the DDA are generalized for element contacts, including contact detection criteria, open-close iteration, and contact submatrices. Three representative numerical examples on contact problems are conducted. Comparative investigations on the results obtained by our coupling scheme, ANSYS, and analytical theories demonstrate the accuracy and effectiveness of the proposed method.
Discontinuous deformation analysis based on complementary theory
无
2009-01-01
The contact between blocks is treated by the open-close iteration in the conventional discontinuous deformation analysis (DDA),which needs to introduce spurious springs between two blocks in contact and to assume the normal stiffness and the tangential stiffness (the penalty factors). Unreasonable values of stiffness would result in numerical problems. To avoid the penalty factors and the open-close iteration,we reformulate the DDA as a mixed complementary problem (MiCP) and then choose the path Newton method (PNM) to solve the problem. Some examples including those originally designed by Shi are reanalyzed,which proves feasibility of the proposed procedure.
Singularity and dynamics on discontinuous vector fields
Luo, Albert CJ
2006-01-01
This book discussed fundamental problems in dynamics, which extensively exist in engineering, natural and social sciences. The book presented a basic theory for the interactions among many dynamical systems and for a system whose motions are constrained naturally or artificially. The methodology and techniques presented in this book are applicable to discontinuous dynamical systems in physics, engineering and control. In addition, they may provide useful tools to solve non-traditional dynamics in biology, stock market and internet network et al, which cannot be easily solved by the traditional
Discontinuation of the Bulletin's menu page
Publications Section
2005-01-01
The menus of the various CERN restaurants will no longer be published in the Bulletin as of Monday 4 April (issue No. 14/2005). The menu pages are being discontinued both as a savings measure and due to the low level of interest in this section of the Bulletin. The most recent survey of Bulletin readers showed that only 13% of the people questioned regularly read the menu section, compared to between 40% and 85% in the case of the other sections. Publications Section SG/CO Tel. 79971
Discontinuation of the Bulletin's menu page
Publications Section
2005-01-01
The menus of the various CERN restaurants will no longer be published in the Bulletin as of Monday 4 April (issue No. 14/2005). The menu pages are being discontinued both as a savings measure and due to the low level of interest in this section of the Bulletin. The most recent survey of Bulletin readers showed that only 13% of the people questioned regularly read the menu section, compared to between 40% and 85% in the case of the other sections. Publications Section DSU-CO Tel. 79971
Discontinued drugs in 2012: endocrine and metabolic.
Colca, Jerry R
2013-10-01
This perspective summarizes 42 drug projects in the general areas of endocrine and metabolic diseases that were reported discontinued during 2012. These programs include development projects against diabetes, metabolic complications (including kidney and liver disease), as well as projects that can be described as approaches to treatment of obesity/anorexia, lipids and various inflammatory diseases. Candidates were identified from a search by Informa Healthcare including data available on TreasureTrove as provided by EOID. Additional information was sought using Google, PubMed, HighWire and ClinicalTrials.gov. The summary of discontinued projects in this area for 2012 provides little in the way of specific guidance especially since details of the fate of most projects are often lacking. Nonetheless, it seems clear that none of these projects has hit upon the key aspects of the pathophysiology of the disorders that they were intended to treat, and the most likely cause of failure is the lack of the ability to produce compelling evidence to support the respective business case in the sense of efficacy/potential therapeutic profile.
Rock discontinuity surface roughness variation with scale
Bitenc, Maja; Kieffer, D. Scott; Khoshelham, Kourosh
2017-04-01
ABSTRACT: Rock discontinuity surface roughness refers to local departures of the discontinuity surface from planarity and is an important factor influencing the shear resistance. In practice, the Joint Roughness Coefficient (JRC) roughness parameter is commonly relied upon and input to a shear strength criterion such as developed by Barton and Choubey [1977]. The estimation of roughness by JRC is hindered firstly by the subjective nature of visually comparing the joint profile to the ten standard profiles. Secondly, when correlating the standard JRC values and other objective measures of roughness, the roughness idealization is limited to a 2D profile of 10 cm length. With the advance of measuring technologies that provide accurate and high resolution 3D data of surface topography on different scales, new 3D roughness parameters have been developed. A desirable parameter is one that describes rock surface geometry as well as the direction and scale dependency of roughness. In this research a 3D roughness parameter developed by Grasselli [2001] and adapted by Tatone and Grasselli [2009] is adopted. It characterizes surface topography as the cumulative distribution of local apparent inclination of asperities with respect to the shear strength (analysis) direction. Thus, the 3D roughness parameter describes the roughness amplitude and anisotropy (direction dependency), but does not capture the scale properties. In different studies the roughness scale-dependency has been attributed to data resolution or size of the surface joint (see a summary of researches in [Tatone and Grasselli, 2012]). Clearly, the lower resolution results in lower roughness. On the other hand, have the investigations of surface size effect produced conflicting results. While some studies have shown a decrease in roughness with increasing discontinuity size (negative scale effect), others have shown the existence of positive scale effects, or both positive and negative scale effects. We
Schatzberg, A F; Haddad, P; Kaplan, E M; Lejoyeux, M; Rosenbaum, J F; Young, A H; Zajecka, J
1997-01-01
Adverse events following discontinuation from serotonin reuptake inhibitors (SRIs) are being reported in the literature with increasing frequency; the frequency and severity of these symptoms appear to vary according to the half-life of the SRI, e.g., the incidence appears higher with the shorter half-life agents than with fluoxetine, which has an extended half-life. Yet, there have been no systematic studies of the phenomenon to date. Therefore, a group of experts convened in Phoenix, Arizona, to develop a clear description or definition of the phenomenon based on these reports. The SRI discontinuation syndrome, referred to as "withdrawal symptoms" in many anecdotal case reports, is distinctly different from the classic withdrawal syndrome associated with alcohol and barbiturates. Anti-depressants are not associated with dependence or drug-seeking behavior. SRI discontinuation symptoms tend to be short-lived and self-limiting, but can be troublesome. They may emerge when an SRI is abruptly discontinued, when doses are missed, and less frequently, during dosage reduction. In addition, the symptoms are not attributable to any other cause and can be reversed when the original agent is reinstituted, or one that is pharmacologically similar is substituted. SRI discontinuation symptoms, in most cases, may be minimized by slowly tapering antidepressant therapy, but there have been several case reports where symptoms occurred consistently even through repeated attempts to taper therapy. Physical symptoms include problems with balance, gastrointestinal and flu-like symptoms, and sensory and sleep disturbances. Psychological symptoms include anxiety and/or agitation, crying spells, and irritability. Further analyses of data bases and clinical studies are needed to define this proposed syndrome more clearly.
[Discontinuation of depression treatment from the perspective of suicide prevention].
Cho, Yoshinori
2012-01-01
It is assumed that discontinuation of treatment for depression may increase the risk of suicide. A population-based register study in Denmark did not find a lower risk among people over age 50 who followed treatment in comparison with those who discontinued treatment with antidepressants at an early stage. This result, however, does not allow us to think superficially that early discontinuation of treatment does not increase the risk of suicide. It is because the study has limitations without information of such as psychiatric diagnoses, severity of the depressed state, and reasons of discontinuation. It is safe for clinicians to aim at preventing discontinuation of treatment. Particularly, in Japan and South Korea where there is a sociocultural climate of tolerability for suicide, suicide can occur in milder depressed state and discontinuation of treatment should be taken more seriously than in Western countries.
Quantitative identification of technological discontinuities using simulation modeling
Park, Hyunseok
2016-01-01
The aim of this paper is to develop and test metrics to quantitatively identify technological discontinuities in a knowledge network. We developed five metrics based on innovation theories and tested the metrics by a simulation model-based knowledge network and hypothetically designed discontinuity. The designed discontinuity is modeled as a node which combines two different knowledge streams and whose knowledge is dominantly persistent in the knowledge network. The performances of the proposed metrics were evaluated by how well the metrics can distinguish the designed discontinuity from other nodes on the knowledge network. The simulation results show that the persistence times # of converging main paths provides the best performance in identifying the designed discontinuity: the designed discontinuity was identified as one of the top 3 patents with 96~99% probability by Metric 5 and it is, according to the size of a domain, 12~34% better than the performance of the second best metric. Beyond the simulation ...
Evaluating Discontinuities in Complex Systems: Toward Quantitative Measures of Resilience
Craig Stow
2007-06-01
Full Text Available The textural discontinuity hypothesis (TDH is based on the observation that animal body mass distributions exhibit discontinuities that may reflect the texture of the landscape available for exploitation. This idea has been extended to other complex systems, hinting that the identification and quantification of discontinuities in the distributions of appropriate variables may provide clues to emergent system properties such as resilience. We propose a discontinuity index, based on the vector norm of the full assemblage of observed discontinuities, as a means to quantify and compare this characteristic among systems. We also evaluate four methods to identify the number and location of the most prominent discontinuities. Although results of the four methods are similar, they are not identical, and we conclude that this problem is best addressed with a consistent operationally defined approach in an adaptive inference framework.
A general approach for calculating coupling impedances of small discontinuities
Kurennoy, S S; Stupakov, G V; Kurennoy, Sergey S; Gluckstern, Robert L; Stupakov, Gennady V
1995-01-01
A general theory of the beam interaction with small discontinuities of the vacuum chamber is developed taking into account the reaction of radiated waves back on the discontinuity. The reactive impedance calculated earlier is reproduced as the first order, and the resistive one as the second order of a perturbation theory based on this general approach. The theory also gives, in a very natural way, the results for the trapped modes due to small discontinuities obtained earlier by a different method.
A General approach for calculating coupling impedances of small discontinuities
Kurennoy, Sergei S.; Gluckstern, Robert L.; Stupakov, Gennady V.
A general theory of the beam interaction with small discontinuities of the vacuum chamber is developed taking into account the reaction of radiated waves back on the discontinuity. The reactive impedance calculated earlier is reproduced as the first order, and the resistive one as the second order of a perturbation theory based on this general approach. The theory also gives, in a very natural way, the results for the trapped modes due to small discontinuities obtained earlier by a different method.
Discontinuous Mixed Covolume Methods for Linear Parabolic Integrodifferential Problems
Ailing Zhu
2014-01-01
Full Text Available The semidiscrete and fully discrete discontinuous mixed covolume schemes for the linear parabolic integrodifferential problems on triangular meshes are proposed. The error analysis of the semidiscrete and fully discrete discontinuous mixed covolume scheme is presented and the optimal order error estimate in discontinuous H(div and first-order error estimate in L2 are obtained with the lowest order Raviart-Thomas mixed element space.
On stability of discontinuous systems via vector Lyapunov functions
无
2007-01-01
This paper deals with the stability of systems with discontinuous righthand side (with solutions in Filippov's sense) via locally Lipschitz continuous and regular vector Lyapunov functions. A new type of "set-valued derivative" of vector Lyapunov functions is introduced, some generalized comparison principles on dis(c)ontinuous systems are shown. Furthermore, Lyapunov stability theory is developed for a class of discontinuous systems based on locally Lipschitz continuous and regular vector Lyapunov functions.
Discontinuation of denosumab and associated fracture incidence
Brown, Jacques P; Roux, Christian; Törring, Ove;
2012-01-01
Osteoporosis is a chronic disease and requires long-term treatment with pharmacologic therapy to ensure sustained anti-fracture benefit. Denosumab reduced the risk for new vertebral, nonvertebral, and hip fractures over 36 months in the FREEDOM trial. While discontinuation of denosumab has been...... associated with transient increases in bone remodeling and declines in bone mineral density (BMD), the effect on fracture risk during treatment cessation is not as well characterized. To understand the fracture incidence between treatment groups after cessation of investigational product, we evaluated...... of 797 subjects (470 placebo, 327 denosumab), who were evaluable during the off-treatment period, showed similar baseline characteristics for age, prevalent fracture, and lumbar spine and total hip BMD T-scores. During treatment, more placebo-treated subjects as compared with denosumab-treated subjects...
Discontinuous Galerkin Methods with Trefftz Approximation
Kretzschmar, Fritz; Tsukerman, Igor; Weiland, Thomas
2013-01-01
We present a novel Discontinuous Galerkin Finite Element Method for wave propagation problems. The method employs space-time Trefftz-type basis functions that satisfy the underlying partial differential equations and the respective interface boundary conditions exactly in an element-wise fashion. The basis functions can be of arbitrary high order, and we demonstrate spectral convergence in the $\\Lebesgue_2$-norm. In this context, spectral convergence is obtained with respect to the approximation error in the entire space-time domain of interest, i.e. in space and time simultaneously. Formulating the approximation in terms of a space-time Trefftz basis makes high order time integration an inherent property of the method and clearly sets it apart from methods, that employ a high order approximation in space only.
RURAL TOURISM IN ROMANIA - EVOLUTIONS AND DISCONTINUITIES
Silviu COSTACHIE
2011-12-01
Full Text Available This paper analyzes the evolution of rural tourism since the early '70s, the time of onset, and indicates the discontinuity recorded especially after 1989 until the brink of the preparation for Romania's joining the European Union and the present state, one far behind the countries with extremely high degree of urbanization and industrialization, probably as a result of a lack of strategy for this form of tourism in which the beneficiary is the Ministry of Tourism, as the health tourism and ecotourism have recently had. The location of many villages in areas of outstanding natural landscapes, the richness and variety of cultural heritage that endows them, are issues related to an increased tourism potential that can be capitalized and those unique tourism products that can not be seen, admired and offered by other countries.
Interfaces of the discontinuation of breastfeeding
Mirna Albuquerque Frota
2016-06-01
Full Text Available The objective was to identify conditions for the discontinuation of exclusive breastfeeding. This is a qualitative study developed in a Primary Health Care Unit (PHCU in Fortaleza, Ceará, Brazil. It included 20 mothers of children aged 0-6 months old who were breastfeeding. The reports evidenced three categories: Guidance received during prenatal care; Meanings of breastfeeding; Determinants of early weaning. It can be concluded that part of the determinants of early weaning is in the building of or failure to build knowledge about breastfeeding. Cultural concepts or myths are inadequate and socially reproduced due to failure, on the part of health professionals who assist expectant mothers during prenatal care or those who assist postpartum women, to deconstruct them.
Discontinuous Galerkin Methods for Turbulence Simulation
Collis, S. Scott
2002-01-01
A discontinuous Galerkin (DG) method is formulated, implemented, and tested for simulation of compressible turbulent flows. The method is applied to turbulent channel flow at low Reynolds number, where it is found to successfully predict low-order statistics with fewer degrees of freedom than traditional numerical methods. This reduction is achieved by utilizing local hp-refinement such that the computational grid is refined simultaneously in all three spatial coordinates with decreasing distance from the wall. Another advantage of DG is that Dirichlet boundary conditions can be enforced weakly through integrals of the numerical fluxes. Both for a model advection-diffusion problem and for turbulent channel flow, weak enforcement of wall boundaries is found to improve results at low resolution. Such weak boundary conditions may play a pivotal role in wall modeling for large-eddy simulation.
Discontinuity and complexity in nonlinear physical systems
Baleanu, Dumitru; Luo, Albert
2014-01-01
This unique book explores recent developments in experimental research in this broad field, organized in four distinct sections. Part I introduces the reader to the fractional dynamics and Lie group analysis for nonlinear partial differential equations. Part II covers chaos and complexity in nonlinear Hamiltonian systems, important to understand the resonance interactions in nonlinear dynamical systems, such as Tsunami waves and wildfire propagations; as well as Lev flights in chaotic trajectories, dynamical system synchronization and DNA information complexity analysis. Part III examines chaos and periodic motions in discontinuous dynamical systems, extensively present in a range of systems, including piecewise linear systems, vibro-impact systems and drilling systems in engineering. And in Part IV, engineering and financial nonlinearity are discussed. The mechanism of shock wave with saddle-node bifurcation and rotating disk stability will be presented, and the financial nonlinear models will be discussed....
DISCONTINUOUS SOLUTIONS IN L∞ FOR HAMILTON-JACOBI EQUATIONS
无
2000-01-01
An approach is introduced to construct global discontinuous solutions in L∞ for Hamilton Jacobi equations. This approach allows the initial data only in L∞ and applies to the equations with nonconvex Hamiltonians. The profit functions are introduced to formulate the notion of discontinuous solutions in L. The existence of global discontinuous solutions in L∞ is established. These solutions in L∞ coincide with the viscosity solutions and the minimax solutions, provided that the initial data are continuous. A prototypical equation is analyzed to examine the L∞ stability of our L∞ solutions. The analysis also shows that global discontinuous solutions are determined by the topology in which the initial data are approximated.
High order discontinuous Galerkin discretizations with discontinuity resolution within the cell
Ekaterinaris, John; Panourgias, Konstantinos
2016-11-01
The nonlinear filter of Yee et al. and used for low dissipative well-balanced high order accurate finite-difference schemes is adapted to the finite element context of discontinuous Galerkin (DG) discretizations. The performance of the proposed nonlinear filter for DG discretizations is demonstrated for different orders of expansions for one- and multi-dimensional problems with exact solutions. It is shown that for higher order discretizations discontinuity resolution within the cell is achieved and the design order of accuracy is preserved. The filter is applied for inviscid and viscous flow test problems including strong shocks interactions to demonstrate that the proposed dissipative mechanism for DG discretizations yields superior results compared to the results obtained with the TVB limiter and high-order hierarchical limiting. The proposed approach is suitable for p-adaptivity in order to locally enhance resolution of three-dimensional flow simulations.
Panourgias, Konstantinos T.; Ekaterinaris, John A.
2016-12-01
The nonlinear filter introduced by Yee et al. (1999) [27] and extensively used in the development of low dissipative well-balanced high order accurate finite-difference schemes is adapted to the finite element context of discontinuous Galerkin (DG) discretizations. The filter operator is constructed in the canonical computational domain for the standard cubical element where it is applied to the computed conservative variables in a direction per direction basis. Filtering becomes possible for all element types in unstructured meshes using collapsed coordinate transformations. The performance of the proposed nonlinear filter for DG discretizations is demonstrated and evaluated for different orders of expansions for one-dimensional and multidimensional problems with exact solutions. It is shown that for higher order discretizations discontinuity resolution within the cell is achieved and the design order of accuracy is preserved. The filter is applied for a number of standard inviscid flow test problems including strong shocks interactions to demonstrate that the proposed dissipative mechanism for DG discretizations yields superior results compared to the results obtained with the total variation bounded (TVB) limiter and high-order hierarchical limiting. The proposed approach is suitable for p-adaptivity in order to locally enhance resolution of three-dimensional flow simulations that include discontinuities and complex flow features.
27 CFR 25.277 - Discontinuance of operations.
2010-04-01
... BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Pilot Brewing Plants § 25.277 Discontinuance of operations. When operations of a pilot brewing plant are to be discontinued, the operator shall notify the... operations have been completed and all beer at the premises has been disposed of and accounted for, the...
EVALUATING DISCONTINUITIES IN COMPLEX SYSTEMS: TOWARD QUANTITATIVE MEASURE OF RESILIENCE
The textural discontinuity hypothesis (TDH) is based on the observation that animal body mass distributions exhibit discontinuities that may reflect the texture of the landscape available for exploitation. This idea has been extended to other complex systems, hinting that the ide...
DISCONTINUOUS FINITE ELEMENT METHOD FOR CONVECTION-DIFFUSION EQUATIONS
Abdellatif Agouzal
2000-01-01
A discontinuous finite element method for convection-diffusion equations is proposed and analyzed. This scheme is designed to produce an approximate solution which is completely discontinuous. Optimal order of convergence is obtained for model problem. This is the same convergence rate known for the classical methods.
19 CFR 142.25 - Discontinuance of immediate delivery privileges.
2010-04-01
... SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) ENTRY PROCESS Special Permit for Immediate Delivery § 142.25 Discontinuance of immediate delivery privileges. (a) Authority of port director. The port director... 19 Customs Duties 2 2010-04-01 2010-04-01 false Discontinuance of immediate delivery privileges...
Contraceptive discontinuation and unintended pregnancy: an imperfect relationship.
Curtis, Siân; Evens, Emily; Sambisa, William
2011-06-01
Contraceptive discontinuation is a common event that may be associated with low motivation to avoid pregnancy. If this is the case, a substantial proportion of pregnancies that follow discontinuation will be reported as intended. Demographic and Health Survey data from six countries (Bangladesh, the Dominican Republic, Kazakhstan, Kenya, the Philippines and Zimbabwe) over the period 1999-2003 were used to explore the proportions of pregnancies women reported as intended or unintended following various contraceptive behaviors. Multivariate logistic regression analysis was used to examine the characteristics of women who reported births as intended when they followed contraceptive failure or discontinuation for reasons other than a desire for pregnancy. The proportion of births reported as intended following contraceptive failure ranged from 16% in Bangladesh to 54% in Kazakhstan, and the proportion reported as intended following discontinuation for reasons other than a desire for pregnancy ranged from 37% in Kenya to 51% in Kazakhstan. In at least half the countries, associations were found between selected women's characteristics and their reports that births following either contraceptive failure or discontinuation were intended: Factors that were positively associated were women's age and the time elapsed between contraceptive discontinuation and the index conception; factors that were negatively associated were increasing number of living children and reporting method failure as opposed to method discontinuation. These findings suggest that underlying variation in the motivation to avoid pregnancy is an important factor in contraceptive discontinuation.
27 CFR 20.68 - Notice of permanent discontinuance.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Notice of permanent discontinuance. 20.68 Section 20.68 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Qualification of Dealers and Users Permanent Discontinuance of Business § 20.68 Notice of...
14 CFR Section 16 - Objective Classification-Discontinued Operations
2010-01-01
... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Objective Classification-Discontinued... AIR CARRIERS Profit and Loss Classification Section 16 Objective Classification—Discontinued... the disposal of investor controlled companies and nontransport ventures whether sold, abandoned,...
Discontinuous Electromagnetic Fields Using Huygens Sources For Wavefront Manipulation
Selvanayagam, Michael
2013-01-01
We introduce the idea of discontinuous electric and magnetic fields at a boundary to design and shape wavefronts in an arbitrary manner. To create this discontinuity in the field we use electric and magnetic currents which act like a Huygens source to radiate the desired wavefront. These currents can be synthesized either by an array of electric and magnetic dipoles or by a combined impedance and admittance surface. A dipole array is an active implementation to impose discontinuous fields while the impedance/admittance surface acts as a passive one. We then expand on our previous work showing how electric and magnetic dipole arrays can be used to cloak an object demonstrating two novel cloaking schemes. We also show how to arbitrarily refract a beam using a set of impedance and admittance surfaces. Refraction using the idea of discontinuous fields is shown to be a more general case of refraction using phase discontinuities.
Modelling discontinuities and Kelvin-Helmholtz instabilities in SPH
Price, Daniel J
2007-01-01
In this paper we discuss the treatment of discontinuities in Smoothed Particle Hydrodynamics (SPH) simulations. In particular we discuss the difference between integral and differential representations of the fluid equations in an SPH context and how this relates to the formulation of dissipative terms for the capture of shocks and other discontinuities. This has important implications for many problems, in particular related to recently highlighted problems related to treating Kelvin-Helmholtz instabilities across contact discontinuities in SPH. We highlight in this paper that the ``fundamental differences'' between SPH and grid based methods suggested by Agertz et al. (2007) are actually more like ``fundamental similarities'' relating to the fact that both types of method require an appropriate treatment of all flow discontinuities. The specific problems pointed out by Agertz et al. are shown to be related in particular to the treatment of contact discontinuities in SPH which can be cured by the simple appl...
MHD discontinuities in solar flares: continuous transitions and plasma heating
Ledentsov, L S
2015-01-01
The boundary conditions for the ideal MHD equations on a plane dis- continuity surface are investigated. It is shown that, for a given mass flux through a discontinuity, its type depends only on the relation between inclina- tion angles of a magnetic field. Moreover, the conservation laws on a surface of discontinuity allow changing a discontinuity type with gradual (continu- ous) changes in the conditions of plasma flow. Then there are the so-called transition solutions that satisfy simultaneously two types of discontinuities. We obtain all transition solutions on the basis of the complete system of boundary conditions for the MHD equations. We also found the expression describing a jump of internal energy of the plasma flowing through the dis- continuity. Firstly, this allows constructing a generalized scheme of possible continuous transitions between MHD discontinuities. Secondly, it enables the examination of the dependence of plasma heating by plasma density and configuration of the magnetic field near t...
Polar constellations design for discontinuous coverage
Sarno, Salvatore; Graziano, Maria Daniela; D'Errico, Marco
2016-10-01
A novel constellation design method is developed for discontinuous coverage of the globe and polar caps. It integrates and extends the applicability of the coverage regions and mitigates the limitations of the existing techniques based on streets-of-coverage (SOC) theory. In particular, the visibility conditions of the targets are mapped in the (Ω, u)-domain to identify the number of satellites per plane and the distance between successive orbits, whereas the planes are arranged around the equator exploiting satellites both in ascending and descending phase. The proposed approach is applied to design potential space segments in polar LEO supporting the existing maritime surveillance services over the globe and on the future polar routes. Results show they require a smaller total number of satellites with respect to the SOC-based configurations for revisit times less than one hour and wide range of swaths. In details, it is observed a reduction between 6% and 22% for global coverage and between 24% and 33% for the coverage of polar caps.
A conservative discontinuous target volatility strategy
Simone Cirelli
2017-07-01
Full Text Available The asset management sector is constantly looking for a reliable investment strategy, which is able to keep its promises. One of the most used approaches is the target volatility strategy that combines a risky asset with a risk-free trying to maintain the portfolio volatility constant over time. Several analyses highlight that such target is fulfilled on average, but in periods of crisis, the portfolio still suffers market’s turmoils. In this paper, the authors introduce an innovative target volatility strategy: the discontinuous target volatility. Such approach turns out to be more conservative in high volatility periods. Moreover, the authors compare the adoption of the VIX Index as a risk measure instead of the classical standard deviation and show whether the former is better than the latter. In the last section, the authors also extend the analysis to remove the risk-free assumption and to include the correlation structure between two risky assets. Empirical results on a wide time span show the capability of the new proposed strategy to enhance the portfolio performance in terms of standard measures and according to stochastic dominance theory.
Capillary surface discontinuities above reentrant corners
Korevaar, H. J.
1982-01-01
A particular configuration of a vertical capillary tube for which S is the equilibrium interface between two fluids in the presence of a downward pointing gravitational field was investigated. S is the graph a function u whose domain is the (horizontal) cross section gamma of the tube. The mean curvature of S is proportional to its height above a fixed reference plane and lambda is a prescribed constant and may be taken between zero and pi/2. Domains gamma for which us is a bounded function but does not extend continuously to d gamma are sought. Simple domains are found and the behavior of u in those domains is studied. An important comparison principle that has been used in the literature to derive many of the results in capillarity is reviewed. It allows one to deduce the approximate shape of a capillary surface by constructing comparison surfaces with mean curvature and contact angle close to those of the (unknown) solution surface. In the context of nonparametric problems the comparison principle leads to height estimates above and below for the function u. An example from the literature where these height estimates have been used successfully is described. The promised domains for which the bounded u does not extend continuously to the boundary are constructed. The point on the boundary at which u has a jump discontinuity will be the vertext of a re-entrant corner having any interior angle theta pi. Using the comparison principle the behavior of u near this point is studied.
Dynamics of Discontinuous Shear Thickening suspensions
Brown, Eric
2015-03-01
Concentrated suspensions of hard particles such as cornstarch in water exhibit Discontinuous Shear Thickening, in which an increasing shear rate drives a transition from liquid- to solid-like mechanical behavior. In steady-state shear this phenomena is a result of a dynamic version of jamming in which forces are transmitted along particle contact networks that span to system boundaries and repeatedly form and break up. Several dynamic phenomena observed in such suspensions have long been assumed to be a consequence of this shear thickening, but cannot be explained as a direct result of shear thickening; for example a uniquely strong impact response which allows a person to run on the fluid surface. We perform experiments in which a concentrated suspension is subjected to transient impact. We find that the strong impact response is due a short-lived jammed contact network spanning to the boundaries and a delay time required for this dynamically jammed region to propagate to the boundary. The resulting ability of this system-spanning solid-like region to support loads can explain the ability of a person to run on the surface of these fluids. This delay before a solid-like response may also explain several other dynamic phenomena observed in these fluids.
Airborne electromagnetic imaging of discontinuous permafrost
Minsley, Burke J.; Abraham, Jared D.; Smith, Bruce D.; Cannia, James C.; Voss, Clifford I.; Jorgenson, M. Torre; Walvoord, Michelle A.; Wylie, Bruce K.; Anderson, Lesleigh; Ball, Lyndsay B.; Deszcz-Pan, Maryla; Wellman, Tristan P.; Ager, Thomas A.
2012-01-01
The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering ˜1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past ˜4 million years and the configuration of permafrost to depths of ˜100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the boundary between continuous permafrost to the north and discontinuous permafrost to the south, making it an important location for examining permafrost dynamics. Our results not only provide a detailed snapshot of the present-day configuration of permafrost, but they also expose previously unseen details about potential surface - groundwater connections and the thermal legacy of surface water features that has been recorded in the permafrost over the past ˜1,000 years. This work will be a critical baseline for future permafrost studies aimed at exploring the connections between hydrogeologic, climatic, and ecological processes, and has significant implications for the stewardship of Arctic environments.
Predictors of premature discontinuation of treatment in multiple disease states
Eric Nantz
2009-01-01
Full Text Available Eric Nantz1, Hong Liu-Seifert2, Vladimir Skljarevski21Department of Statistics, Western Michigan University, Kalamazoo, MI, USA; 2Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USABackground: Premature discontinuation of treatment impacts outcomes of clinical practice. The traditional perception has been patient discontinuation is mainly driven by unwanted side effects. Systematic analysis of data from clinical trials across several disease states was performed to identify predictors of premature discontinuation during clinical interventions.Methods: A post hoc analysis was conducted on 22 randomized, double-blind, placebo-controlled clinical trials for treatment of fibromyalgia, diabetic peripheral neuropathic pain, major depressive disorder, and generalized anxiety disorder. Analyses were conducted on pooled data within each disease state.Results: Lack of early therapeutic response was a significant predictor of patient discontinuation in each disease state. Visit-wise changes in therapeutic response and severity of adverse events were also significant risk factors, with change in therapeutic response having a higher significance level in three disease states. Patients who discontinued due to adverse events had similar therapeutic responses as patients completing treatment.Conclusion: Contrary to the conventional belief that premature treatment discontinuation is primarily related to adverse events, our findings suggest lack of therapeutic response also plays a significant role in patient attrition. This research highlights the importance of systematic monitoring of therapeutic response in clinical practice as a measure to prevent patients’ discontinuation from pharmacological treatments.Keywords: attrition, depression, generalized anxiety disorder, fibromyalgia, therapeutic response, adverse event
Magnetic discontinuities in magnetohydrodynamic turbulence and in the solar wind.
Zhdankin, Vladimir; Boldyrev, Stanislav; Mason, Joanne; Perez, Jean Carlos
2012-04-27
Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) turbulence. We detect the discontinuities by measuring the fluctuations of the magnetic field direction, Δθ, across fixed spatial increments Δx in direct numerical simulations of MHD turbulence with an imposed uniform guide field B(0). A large region of the probability density function (pdf) for Δθ is found to follow an exponential decay, proportional to exp(-Δθ/θ(*)), with characteristic angle θ(*)≈(14°)(b(rms)/B(0))(0.65) for a broad range of guide-field strengths. We find that discontinuities observed in the solar wind can be reproduced by MHD turbulence with reasonable ratios of b(rms)/B(0). We also observe an excess of small angular discontinuities when Δx becomes small, possibly indicating an increasing statistical significance of dissipation-scale structures. The structure of the pdf in this case closely resembles the two-population pdf seen in the solar wind. We thus propose that strong discontinuities are associated with inertial-range MHD turbulence, while weak discontinuities emerge from dissipation-range turbulence. In addition, we find that the structure functions of the magnetic field direction exhibit anomalous scaling exponents, which indicates the existence of intermittent structures.
Adaptive Finite Element Methods for Elliptic Problems with Discontinuous Coefficients
Bonito, Andrea
2013-01-01
Elliptic PDEs with discontinuous diffusion coefficients occur in application domains such as diffusions through porous media, electromagnetic field propagation on heterogeneous media, and diffusion processes on rough surfaces. The standard approach to numerically treating such problems using finite element methods is to assume that the discontinuities lie on the boundaries of the cells in the initial triangulation. However, this does not match applications where discontinuities occur on curves, surfaces, or manifolds, and could even be unknown beforehand. One of the obstacles to treating such discontinuity problems is that the usual perturbation theory for elliptic PDEs assumes bounds for the distortion of the coefficients in the L∞ norm and this in turn requires that the discontinuities are matched exactly when the coefficients are approximated. We present a new approach based on distortion of the coefficients in an Lq norm with q < ∞ which therefore does not require the exact matching of the discontinuities. We then use this new distortion theory to formulate new adaptive finite element methods (AFEMs) for such discontinuity problems. We show that such AFEMs are optimal in the sense of distortion versus number of computations, and report insightful numerical results supporting our analysis. © 2013 Societ y for Industrial and Applied Mathematics.
Outcomes of patients with chronic lymphocytic leukemia after discontinuing ibrutinib.
Jain, Preetesh; Keating, Michael; Wierda, William; Estrov, Zeev; Ferrajoli, Alessandra; Jain, Nitin; George, Binsah; James, Danelle; Kantarjian, Hagop; Burger, Jan; O'Brien, Susan
2015-03-26
Ibrutinib is a Bruton tyrosine kinase inhibitor approved for the treatment of patients with relapsed refractory chronic lymphocytic leukemia (RR-CLL). We describe the characteristics, causes of discontinuation, and outcomes in patients who discontinued treatment with ibrutinib. One hundred twenty-seven patients were enrolled in various clinical trials of ibrutinib, with or without rituximab, at our center. Thirty-three (26%) patients have discontinued ibrutinib to date. The majority of those patients had high-risk features: 94% with unmutated immunoglobulin heavy chain variable gene rearrangement, 58% with del(17p) by fluorescence in situ hybridization, and 54% with a complex karyotype. Causes of discontinuation were disease transformation (7), progressive CLL (7), stem cell transplantation (3), adverse events (11), serious adverse events/deaths (3), and miscellaneous reasons (2). Twenty five patients (76%) died after discontinuing ibrutinib; the median overall survival was 3.1 months after discontinuation. Most patients with RR-CLL who discontinued ibrutinib early were difficult to treat and had poor outcomes.
MHD discontinuities in solar flares: continuous transitions and plasma heating
Ledentsov, Leonid; Somov, Boris
The conservation laws on a surface of discontinuity in the ideal magnetohydrodynamics (MHD) allow changing a discontinuity type with gradual (continuous) changes in conditions of plasma. Then there are the so-called transition solutions that satisfy simultaneously two types of discontinuities. We obtain all transition solutions on the basis of a complete system of boundary conditions for the MHD equations. We also found an expression describing a jump of internal energy of the plasma flowing through the discontinuity. It allows, firstly, to construct a generalized scheme of possible transitions between MHD discontinuities, and secondly, to examine the dependence of plasma heating by plasma density and configuration of the magnetic field near the surface of the discontinuity (i.e., by the type of the MHD discontinuity). The problem of the heating of "superhot" plasma (with the electron temperature is greater than 10 keV) in solar flares are discussed. It is shown that the best conditions for heating are carried out in the vicinity of the reconnecting current layer near the areas of reverse currents. Bibl.: B.V.Somov. Plasma Astrophysics, Part II: Reconnection and Flares, Second Edition. (New York: Springer SBM, 2013).
Risk of discontinuation of Advanced Therapy Medicinal Products clinical trials.
Hanna, Eve; Rémuzat, Cecile; Auquier, Pascal; Toumi, Mondher
2016-01-01
Advanced therapy medicinal products (ATMPs) constitute a class of innovative products that encompasses gene therapy, somatic cell therapy, and tissue-engineered products (TEP). There is an increased investment of commercial and non-commercial sponsors in this field and a growing number of ATMPs randomized clinical trials (RCT) and patients enrolled in such trials. RCT generate data to prove the efficacy of a new therapy, but the discontinuation of RCTs wastes scarce resources. Our objective is to identify the number and characteristics of discontinued ATMPs trials in order to evaluate the rate of discontinuation. We searched for ATMPs trials conducted between 1999 to June 2015 using three databases, which are Clinicaltrials.gov, the International Clinical Trials Registry Platform (ICTRP), and the EU Drug Regulating Authorities Clinical Trials (EudraCT). We selected the ATMPs trials after elimination of the duplicates. We identified the disease areas and the sponsors as commercial or non-commercial organizations. We classified ATMPs by type and trial status, that is, ongoing, completed, terminated, discontinued, and prematurely ended. Then, we calculated the rate of discontinuation. Between 1999 and June 2015, 143 withdrawn, terminated, or prematurely ended ATMPs clinical trials were identified. Between 1999 and June 2013, 474 ongoing and completed clinical trials were identified. Therefore, the rate of discontinuation of ATMPs trials is 23.18%, similar to that for non-ATMPs drugs in development. The probability of discontinuation is, respectively, 27.35, 16.28, and 16.34% for cell therapies, gene therapies, and TEP. The highest discontinuation rate is for oncology (43%), followed by cardiology (19.2%). It is almost the same for commercial and non-commercial sponsors; therefore, the discontinuation reason may not be financially driven. No failure risk rate per development phase is available for ATMPs. The discontinuation rate may prove helpful when assessing the
Coupling impedances of small discontinuities: A general approach
Kurennoy, Sergey S.; Gluckstern, Robert L.; Stupakov, Gennady V.
1995-10-01
A general theory of the beam interaction with small discontinuities of the vacuum chamber of an accelerator is developed taking into account the reaction of radiated waves back on the discontinuity. The reactive impedance calculated earlier is reproduced as the first order and the resistive one as the second order of a perturbation theory based on this general approach. The theory also gives, in an easy and natural way, the analytical results for the frequencies and coupling impedances of the trapped modes due to small discontinuities on the vacuum chamber of a general cross section. Formulas for two important particular cases-a circular and a rectangular chamber-are presented.
Coupling impedances of small discontinuities: A general approach
Kurennoy, S.S.; Gluckstern, R.L. [Physics Department, University of Maryland, College Park, Maryland 20742 (United States); Stupakov, G.V. [Stanford Linear Accelerator Center, Stanford, California 94309 (United States)
1995-10-01
A general theory of the beam interaction with small discontinuities of the vacuum chamber of an accelerator is developed taking into account the reaction of radiated waves back on the discontinuity. The reactive impedance calculated earlier is reproduced as the first order and the resistive one as the second order of a perturbation theory based on this general approach. The theory also gives, in an easy and natural way, the analytical results for the frequencies and coupling impedances of the trapped modes due to small discontinuities on the vacuum chamber of a general cross section. Formulas for two important particular cases---a circular and a rectangular chamber---are presented.
The relation of solar wind structure to hydromagnetic discontinuities
Alexander, C.J.; Neugebauer, M.; Smith, E.J.; Bame, S.J.
1987-01-01
High resolution ISEE-3 data have been used to examine the relative abundances of tangential (TD) vs rotational (RD) discontinuities in different types of solar wind flow. Three types of flow were examined; flow from coronal holes, sector boundary flow and transient flow. It has been found that coronal hole flow has substantially more discontinuities and a greater ratio of RD's to TD's than do the other types of flow. Discontinuities are least frequent in transient flows characterized by bidirectional streaming of electrons. This leads us to the conclusion that meaningful studies of the velocity dependence of the rates of occurrence of different types of discontinuities must take the type of flow (coronal hole versus transient) into account. 7 refs., 3 figs., 1 tab.
UPWIND DISCONTINUOUS GALERKIN METHODS FOR TWO DIMENSIONAL NEUTRON TRANSPORT EQUATIONS
袁光伟; 沈智军; 闫伟
2003-01-01
In this paper the upwind discontinuous Galerkin methods with triangle meshes for two dimensional neutron transport equations will be studied.The stability for both of the semi-discrete and full-discrete method will be proved.
Propagating plasma discontinuity in a tube immersed in distilled water
Song, Jian; Tang, Jingfeng; Wei, Liqiu; Zhang, Nan; Wang, Youyin; Yu, Daren
2016-04-01
In a dielectric tube partially surrounded by distilled water, a propagating discontinuity is observed in a cold argon plasma jet at atmospheric pressure in both the laminar and turbulent flow regimes. Through electrical and optical diagnostics, the mechanism of formation for this phenomenon is investigated. Results show that the strong polarization of the distilled water, the constraint from the electric field (or a sufficiently high electric field), and the transport of the active species are in combination responsible for the propagating plasma discontinuity. Indeed, smaller surface areas of the tube surrounded by distilled water, shorter distances between the distilled water and the ground electrodes, as well as larger gas flow rates can together make the discontinuous discharge channel appear more readily. In particular, when the flow switches from laminar to turbulent, the plasma behavior of the discontinuity no longer depends on the gas flow rate. This is mostly attributed to the extreme instability of turbulence which further suppresses the transport of active species.
Minimizers with discontinuous velocities for the electromagnetic variational method
De Luca, Jayme
2010-01-01
The electromagnetic two-body problem has \\emph{neutral-delay} equations of motion that, for generic boundary data, can have solutions with \\emph{% discontinuous} derivatives. If one wants to use these neutral-delay equations with \\emph{arbitrary} boundary data, solutions with discontinuous derivatives must be expected and allowed. Surprisingly, the Wheeler-Feynman electrodynamics has a variational method with mixed-type boundary conditions for which minimizer trajectories with discontinuous derivatives are also expected, as we show here. The variational method defines continuous trajectories with piecewise-defined velocities and accelerations, with electromagnetic fields defined \\emph{by} the equations of motion \\emph{on} trajectory points. Here we use the piecewise-defined minimizers with the Li{% \\'{e}}nard-Wierchert formulas to define generalized electromagnetic fields almost everywhere (but on sets of points of zero measure where the advanced/retarded velocities and/or accelerations are discontinuous). Al...
Necessary Conditions for Discontinuities of Multidimensional Size Functions
Cerri, Andrea
2008-01-01
Some new results about multidimensional topological persistence are presented, proving that the discontinuity points of a k-dimensional size function are necessarily related to the pseudocritical values of the associated measuring function.
47 CFR 80.471 - Discontinuance or impairment of service.
2010-10-01
... commercial mobile radio service providers, a public coast station must not discontinue or impair service unless authorized to do so by the Commission. Automated Systems ... Section 80.471 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL...
Calculation of Accurate Hexagonal Discontinuity Factors for PARCS
Pounders. J., Bandini, B. R. , Xu, Y, and Downar, T. J.
2007-11-01
In this study we derive a methodology for calculating discontinuity factors consistent with the Triangle-based Polynomial Expansion Nodal (TPEN) method implemented in PARCS for hexagonal reactor geometries. The accuracy of coarse-mesh nodal methods is greatly enhanced by permitting flux discontinuities at node boundaries, but the practice of calculating discontinuity factors from infinite-medium (zero-current) single bundle calculations may not be sufficiently accurate for more challenging problems in which there is a large amount of internodal neutron streaming. The authors therefore derive a TPEN-based method for calculating discontinuity factors that are exact with respect to generalized equivalence theory. The method is validated by reproducing the reference solution for a small hexagonal core.
Actor Bonds in Situations of Discontinuous Business Activities
Skaates, Maria Anne
2000-01-01
in situations of discontinuity. Therefore an analysis and comparison of relevant concepts that capture the key generative features of actor bonds in both socially constructed networks and socially constructed markets is undertaken. These concepts include the "milieu" of project marketing (Cova et al., 1996......Demand in many industrial buying situations, e.g. project purchases or procurement related to virtual organizations, is discontinuous. In situations of discontinuity, networks are often more of an ad hos informational and social nature, as strong activity and resource links are not present......) and the institutional concept of the "field". Finally this paper introduces the concept of "social capital" (Bourdieu, 1983) and discusses whether it can be used to conceptualize the dynamic features of actor bonds in situations of discontinuity....
Solutions of the Wheeler-Feynman equations with discontinuous velocities
de Souza, Daniel Câmara; De Luca, Jayme
2014-01-01
We generalize Wheeler-Feynman electrodynamics with a variational boundary-value problem with past and future boundary segments that can include velocity discontinuity points. Critical-point trajectories must satisfy the Euler-Lagrange equations of the action functional, which are neutral-differential delay equations of motion (the Wheeler-Feynman equations of motion). At velocity discontinuity points, critical-point orbits must satisfy the Weierstrass-Erdmann conditions of continuity of parti...
Modified Burgers' equation by the local discontinuous Galerkin method
Zhang Rong-Pei; Yu Xi-Jun; Zhao Guo-Zhong
2013-01-01
In this paper,we present the local discontinuous Galerkin method for solving Burgers' equation and the modified Burgers' equation.We describe the algorithm formulation and practical implementation of the local discontinuous Galerkin method in detail.The method is applied to the solution of the one-dimensional viscous Burgers' equation and two forms of the modified Burgers' equation.The numerical results indicate that the method is very accurate and efficient.
Discontinued drug in 2007: renal, endocrine and metabolic drugs.
Colca, Jerry R
2008-11-01
This perspective is the first part of an annual series of papers discussing drugs dropped from clinical development in the previous year. Specifically, this paper focuses on the 14 renal, endocrine and metabolic drugs discontinued in 2007. The candidates covered in this summary were being developed for treatment of diabetes, obesity, reproductive and urogenital health issues, and growth hormone deficiency. Information for this perspective was derived from a search of the Pharmaprojects database for drugs discontinued after reaching Phase I - III clinical trials.
Clopidogrel discontinuation after myocardial infarction and risk of thrombosis
Charlot, Mette; Nielsen, Lars Hougaard; Lindhardsen, Jesper
2012-01-01
The benefit of extending clopidogrel treatment beyond the 12-month period recommended in current guidelines after myocardial infarction (MI) is debated. We analysed the risk of adverse cardiovascular outcomes after discontinuation of 12 months of clopidogrel treatment.......The benefit of extending clopidogrel treatment beyond the 12-month period recommended in current guidelines after myocardial infarction (MI) is debated. We analysed the risk of adverse cardiovascular outcomes after discontinuation of 12 months of clopidogrel treatment....
Trapped modes in waveguides with many small discontinuities
Kurennoy, S.S. (Physics Department, University of Maryland, College Park, Maryland 20742 (United States))
1995-03-01
It has been demonstrated recently [G. V. Stupakov and S. S. Kurennoy, Phys. Rev. E 49, 794 (1994)] that a single small discontinuity (such as an enlargement or a hole) on a smooth waveguide can result in the appearance of trapped electromagnetic modes with frequencies slightly below the waveguide cutoff frequencies. The present paper studies a similar phenomenon for a waveguide with many small discontinuities, which is a good model for the vacuum chamber of large accelerators. Frequencies of trapped modes and their contributions to the coupling impedance are calculated. The frequencies for the cases of a few discontinuities or a periodic structure coincide well with those from numerical simulations. The trapped modes produce sharp resonance peaks of the coupling impedance near the cutoff frequencies. The magnitude of these peaks, as well as the existence itself of a trapped mode, strongly depends on the distribution of discontinuities, or on the distance between them if a regular array is considered. The impedance in the extreme case can be as large as [ital N][sup 3] times that for a single discontinuity, where [ital N] is the number of discontinuities.
Trapped modes in waveguides with many small discontinuities
Kurennoy, Sergey S.
1995-03-01
It has been demonstrated recently [G. V. Stupakov and S. S. Kurennoy, Phys. Rev. E 49, 794 (1994)] that a single small discontinuity (such as an enlargement or a hole) on a smooth waveguide can result in the appearance of trapped electromagnetic modes with frequencies slightly below the waveguide cutoff frequencies. The present paper studies a similar phenomenon for a waveguide with many small discontinuities, which is a good model for the vacuum chamber of large accelerators. Frequencies of trapped modes and their contributions to the coupling impedance are calculated. The frequencies for the cases of a few discontinuities or a periodic structure coincide well with those from numerical simulations. The trapped modes produce sharp resonance peaks of the coupling impedance near the cutoff frequencies. The magnitude of these peaks, as well as the existence itself of a trapped mode, strongly depends on the distribution of discontinuities, or on the distance between them if a regular array is considered. The impedance in the extreme case can be as large as N3 times that for a single discontinuity, where N is the number of discontinuities.
Research progress on criteria for discontinuation of EGFR inhibitor therapy
Zhuang HQ
2012-10-01
Full Text Available Hong-qing Zhuang, Zhi-yong Yuan, Jun Wang, Ping Wang, Lu-jun Zhao, Bai-lin ZhangDepartment of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin Lung Cancer Center, Tianjin, People's Republic of ChinaAbstract: The clinical success of the epidermal growth factor receptor (EGFR tyrosine kinase inhibitors (TKI as therapeutic agents has prompted great interest in their further development and clinical testing for a wide variety of malignancies. However, most studies have focused on the efficacy of TKI, and few studies have been done on the criteria for their discontinuation. The current standard for drug discontinuation is “until progression”, based on change in tumor size. However, tumor size is not related to the gene expression which determines the efficacy of TKI in the final analysis, and it is also difficult to make a thorough and correct prediction based on tumor size when the TKI is discontinued. Nevertheless, clinical evaluation of the criteria for TKI discontinuation is still in its early days. Some promising findings have started to emerge. With the improving knowledge of EGFR and its inhibitors, it is expected that the criteria for discontinuation of EGFR inhibitor therapy will become clearer.Keywords: epidermal growth factor receptor, drug discontinuation, acquired drug-resistance
Minimizers with discontinuous velocities for the electromagnetic variational method
de Luca, Jayme
2010-08-01
The electromagnetic two-body problem has neutral differential delay equations of motion that, for generic boundary data, can have solutions with discontinuous derivatives. If one wants to use these neutral differential delay equations with arbitrary boundary data, solutions with discontinuous derivatives must be expected and allowed. Surprisingly, Wheeler-Feynman electrodynamics has a boundary value variational method for which minimizer trajectories with discontinuous derivatives are also expected, as we show here. The variational method defines continuous trajectories with piecewise defined velocities and accelerations, and electromagnetic fields defined by the Euler-Lagrange equations on trajectory points. Here we use the piecewise defined minimizers with the Liénard-Wierchert formulas to define generalized electromagnetic fields almost everywhere (but on sets of points of zero measure where the advanced/retarded velocities and/or accelerations are discontinuous). Along with this generalization we formulate the generalized absorber hypothesis that the far fields vanish asymptotically almost everywhere and show that localized orbits with far fields vanishing almost everywhere must have discontinuous velocities on sewing chains of breaking points. We give the general solution for localized orbits with vanishing far fields by solving a (linear) neutral differential delay equation for these far fields. We discuss the physics of orbits with discontinuous derivatives stressing the differences to the variational methods of classical mechanics and the existence of a spinorial four-current associated with the generalized variational electrodynamics.
A Discontinuous Galerkin Chimera Overset Solver
Galbraith, Marshall Christopher
This work summarizes the development of an accurate, efficient, and flexible Computational Fluid Dynamics computer code that is an improvement relative to the state of the art. The improved accuracy and efficiency is obtained by using a high-order discontinuous Galerkin (DG) discretization scheme. In order to maximize the computational efficiency, quadrature-free integration and numerical integration optimized as matrix-vector multiplications is employed and implemented through a pre-processor (PyDG). Using the PyDG pre-processor, a C++ polynomial library has been developed that uses overloaded operators to design an efficient Domain Specific Language (DSL) that allows expressions involving polynomials to be written as if they are scalars. The DSL, which makes the syntax of computer code legible and intuitive, promotes maintainability of the software and simplifies the development of additional capabilities. The flexibility of the code is achieved by combining the DG scheme with the Chimera overset method. The Chimera overset method produces solutions on a set of overlapping grids that communicate through an exchange of data on grid boundaries (known as artificial boundaries). Finite volume and finite difference discretizations use fringe points, which are layers of points on the artificial boundaries, to maintain the interior stencil on artificial boundaries. The fringe points receive solution values interpolated from overset grids. Proper interpolation requires fringe points to be contained in overset grids. Insufficient overlap must be corrected by modifying the grid system. The Chimera scheme can also exclude regions of grids that lie outside the computational domain; a process commonly known as hole cutting. The Chimera overset method has traditionally enabled the use of high-order finite difference and finite volume approaches such as WENO and compact differencing schemes, which require structured meshes, for modeling fluid flow associated with complex
Socio-Economic Differentials in Contraceptive Discontinuation in India
Kiran Agrahari
2016-05-01
Full Text Available Fertility divergence amid declining in use of modern contraception in many states of India needs urgent research and programmatic attention. Although utilization of antenatal, natal, and post-natal care has shown spectacular increase in post National Rural Health Mission (NRHM period, the contraceptive use had shown a declining trend. Using the calendar data from the National Family Health Survey–3, this article examines the reasons of contraceptive discontinuation among spacing method users by socio-economic groups in India. Bivariate and multivariate analyses and life table discontinuation rates are used in the analyses. Results suggest that about half of the pill users, two fifths of the condom users, one third of traditional method users, and one fifth of IUD users discontinue a method in first 12 months of use. However, the discontinuation of all three modern spacing methods declines in subsequent period (within 12-36 months. The probability of method failure was highest among traditional method users and higher among poor and less educated that may lead to unwanted/mistimed birth. Although discontinuation of condom declines with economic status, it does not show any large variation for pill users. The contraceptive discontinuation was significantly associated with duration of use, age, parity, contraceptive method, religion, and contraceptive intention. Based on these findings, it is suggested that follow-up services to modern spacing method users, increasing counseling for spacing method users, motivating the traditional method user to use modern spacing method, and improving the overall quality of family planning services can reduce the discontinuation of spacing method.
The effect of mechanical discontinuities on the growth of faults
Bonini, Lorenzo; Basili, Roberto; Bonanno, Emanuele; Toscani, Giovanni; Burrato, Pierfrancesco; Seno, Silvio; Valensise, Gianluca
2016-04-01
The growth of natural faults is controlled by several factors, including the nature of host rocks, the strain rate, the temperature, and the presence of fluids. In this work we focus on the mechanical characteristics of host rocks, and in particular on the role played by thin mechanical discontinuities on the upward propagation of faults and on associated secondary effects such as folding and fracturing. Our approach uses scaled, analogue models where natural rocks are simulated by wet clay (kaolin). A clay cake is placed above two rigid blocks in a hanging wall/footwall configuration on either side of a planar fault. Fault activity is simulated by motor-controlled movements of the hanging wall. We reproduce three types of faults: a 45°-dipping normal fault, a 45°-dipping reverse fault and a 30°-dipping reverse fault. These angles are selected as representative of most natural dip-slip faults. The analogues of the mechanical discontinuities are obtained by precutting the wet clay cake before starting the hanging wall movement. We monitor the experiments with high-resolution cameras and then obtain most of the data through the Digital Image Correlation method (D.I.C.). This technique accurately tracks the trajectories of the particles of the analogue material during the deformation process: this allows us to extract displacement field vectors plus the strain and shear rate distributions on the lateral side of the clay block, where the growth of new faults is best seen. Initially we run a series of isotropic experiments, i.e. experiments without discontinuities, to generate a reference model: then we introduce the discontinuities. For the extensional models they are cut at different dip angles, from horizontal to 45°-dipping, both synthetic and antithetic with respect to the master fault, whereas only horizontal discontinuities are introduced in the contractional models. Our experiments show that such discontinuities control: 1) the propagation rate of faults
Solutions of the Wheeler-Feynman equations with discontinuous velocities.
de Souza, Daniel Câmara; De Luca, Jayme
2015-01-01
We generalize Wheeler-Feynman electrodynamics with a variational boundary value problem for continuous boundary segments that might include velocity discontinuity points. Critical-point orbits must satisfy the Euler-Lagrange equations of the action functional at most points, which are neutral differential delay equations (the Wheeler-Feynman equations of motion). At velocity discontinuity points, critical-point orbits must satisfy the Weierstrass-Erdmann continuity conditions for the partial momenta and the partial energies. We study a special setup having the shortest time-separation between the (infinite-dimensional) boundary segments, for which case the critical-point orbit can be found using a two-point boundary problem for an ordinary differential equation. For this simplest setup, we prove that orbits can have discontinuous velocities. We construct a numerical method to solve the Wheeler-Feynman equations together with the Weierstrass-Erdmann conditions and calculate some numerical orbits with discontinuous velocities. We also prove that the variational boundary value problem has a unique solution depending continuously on boundary data, if the continuous boundary segments have velocity discontinuities along a reduced local space.
Biologic Discontinuations Studies: A Systematic Review of Methods
Yoshida, Kazuki; Sung, Yoon-Kyoung; Kavanaugh, Arthur; Bae, Sang-Cheol; Weinblatt, Michael E.; Kishimoto, Mitsumasa; Matsui, Kazuo; Tohma, Shigeto; Solomon, Daniel H.
2016-01-01
Objectives We conducted a systematic review to assess the design and “failure definition” in studies of biologic discontinuation in rheumatoid arthritis (RA). Methods We found 403 studies on PubMed, and included 9 published papers and 5 abstracts from scientific meetings. We used a structured extraction form to collect information regarding study design and outcome (failure) definition. Results Three types of studies were found: randomized controlled trials, long-term extension studies of clinical trials, and prospective discontinuation studies. The largest study had 196 subjects in the discontinuation arm. Most studies allowed concomitant use of non-biologic drugs at biologic discontinuation. Heterogeneity was also found in the failure definition. Although all studies used measures of disease activity, the threshold for failure and the time point of assessment differed among studies. Few studies incorporated changing use of non-biologic drugs or glucocorticoids into the failure definition. Conclusions Although many studies have examined the outcome of biologic discontinuation, they have all been relatively small. Typical practice studies from registries may add important information, but will likely need to rely on a broader failure definition. PMID:23723316
Solutions of the Wheeler-Feynman equations with discontinuous velocities
de Souza, Daniel Câmara; De Luca, Jayme
2015-01-01
We generalize Wheeler-Feynman electrodynamics with a variational boundary value problem for continuous boundary segments that might include velocity discontinuity points. Critical-point orbits must satisfy the Euler-Lagrange equations of the action functional at most points, which are neutral differential delay equations (the Wheeler-Feynman equations of motion). At velocity discontinuity points, critical-point orbits must satisfy the Weierstrass-Erdmann continuity conditions for the partial momenta and the partial energies. We study a special setup having the shortest time-separation between the (infinite-dimensional) boundary segments, for which case the critical-point orbit can be found using a two-point boundary problem for an ordinary differential equation. For this simplest setup, we prove that orbits can have discontinuous velocities. We construct a numerical method to solve the Wheeler-Feynman equations together with the Weierstrass-Erdmann conditions and calculate some numerical orbits with discontinuous velocities. We also prove that the variational boundary value problem has a unique solution depending continuously on boundary data, if the continuous boundary segments have velocity discontinuities along a reduced local space.
Model for vortex turbulence with discontinuities in the solar wind
O. P. Verkhoglyadova
2003-01-01
Full Text Available A model of vortex with embedded discontinuities in plasma flow is developed in the framework of ideal MHD in a low b plasma. Vortex structures are considered as a result of 2-D evolution of nonlinear shear Alfvén waves in the heliosphere. Physical properties of the solutions and vector fields are analyzed and the observational aspects of the model are discussed. The ratio of normal components to the discontinuity Br /Vr can be close to -2. The alignment between velocity and magnetic field vectors takes place. Spacecraft crossing such vortices will typically observe a pair of discontinuities, but with dissimilar properties. Occurrence rate for different discontinuity types is estimated and agrees with observations in high-speed solar wind stream. Discontinuity crossing provides a backward rotation of magnetic field vector and can be observed as part of a backward arc. The Ulysses magnetometer data obtained in the fast solar wind are compared with the results of theoretical modelling.
Discontinuous dual-primal mixed finite elements for elliptic problems
Bottasso, Carlo L.; Micheletti, Stefano; Sacco, Riccardo
2000-01-01
We propose a novel discontinuous mixed finite element formulation for the solution of second-order elliptic problems. Fully discontinuous piecewise polynomial finite element spaces are used for the trial and test functions. The discontinuous nature of the test functions at the element interfaces allows to introduce new boundary unknowns that, on the one hand enforce the weak continuity of the trial functions, and on the other avoid the need to define a priori algorithmic fluxes as in standard discontinuous Galerkin methods. Static condensation is performed at the element level, leading to a solution procedure based on the sole interface unknowns. The resulting family of discontinuous dual-primal mixed finite element methods is presented in the one and two-dimensional cases. In the one-dimensional case, we show the equivalence of the method with implicit Runge-Kutta schemes of the collocation type exhibiting optimal behavior. Numerical experiments in one and two dimensions demonstrate the order accuracy of the new method, confirming the results of the analysis.
Clozapine underutilization and discontinuation in African Americans due to leucopenia.
Kelly, Deanna L; Kreyenbuhl, Julie; Dixon, Lisa; Love, Raymond C; Medoff, Deborah; Conley, Robert R
2007-09-01
Clozapine use has been notably lower in African American patients than in Caucasians. It has been suggested that lower normal ranges for white blood cell (WBC) counts in African Americans, known as benign ethnic neutropenia, may account partially for the disparity. We examined the rates of leucopenia and agranulocytosis as reasons for discontinuation of clozapine in a sample of 1875 patients with schizophrenia treated in the State of Maryland. Between 1989 and 1999, 5.3% (31/588) of African Americans and 2.4% (31/1287) of Caucasians discontinued clozapine treatment due to leucopenia (chi square = 10.35, df = 1, P = 0.001). No African American patients developed agranulocytosis while 8 Caucasian patients (0.62%) developed this blood dyscrasia. Discontinuations due to leucopenia occurred throughout treatment. Discontinuations due to agranulocytosis occurred primarily in the first 18 weeks (7/8; 87.5% patients with agranulocytosis). It is likely that African Americans had clozapine discontinued unnecessarily due to benign ethnic neutropenia. We concur with recent recommendations to acknowledge differences in WBC values in African Americans and to modify prescribing guidelines or formally acknowledge benign ethnic leucopenia like in other countries in order to facilitate greater use of clozapine in these patients.
Occupy the Financial Niche – Saturation and Crisis (discontinuous decisions
Ionut PURICA
2014-09-01
Full Text Available The model presented is proposing an approach that could verify the nonlinear behaviour during a crisis, such that to quantify and predict potential discontinuous behaviour. In this case, the crisis behaviour associated with financial funds reallocation among various credit instruments, described as memes with the sense of Dawkins, is shown to be of discontinuous nature stemming from a logistic penetration in the financial behaviour niche. Actually the logistic penetration is typical in creating cyclic behaviour of economic structures as shown by Marchetti and others from IIASA. A Fokker-Planck equation description results in a stationary solution having a bifurcation like solution with evolution trajectories on a ‘cusp’ type catastrophe that may describe discontinuous decision behaviour
Delta-Measure Perturbations of a Contact Discontinuity
Baty, Roy
2012-11-01
In this presentation, nonstandard analysis is applied to study generalized function perturbations of contact discontinuities in compressible, inviscid fluids. Nonstandard analysis is an area of modern mathematics that studies extensions of the real number system to nonstandard number systems that contain infinitely large and infinitely small numbers. Perturbations of a contact discontinuity are considered that represent one-dimensional analogs of the two-dimensional perturbations observed in the initial evolution of a Richtmyer-Meshkov instability on a density interface. Nonstandard predistributions of the Dirac delta measure and its derivatives are applied as the perturbations of a contact discontinuity. The one-dimensional Euler equations are used to model the flow field of a fluid containing a perturbed density interface and generalized solutions are constructed for the perturbed flow field.
Actor Bonds in Situations of Discontinuous Business Activities
Skaates, Maria Anne
2000-01-01
. Furthermore the governance structure of markets characterized by discontinuous business activities is either that of the "socially constructed market" (Skaates, 2000) or that of the (socially constructed) network (Håkansson and Johanson, 1993). Additionally relationships and actor bonds vary substantially...... in situations of discontinuity. Therefore an analysis and comparison of relevant concepts that capture the key generative features of actor bonds in both socially constructed networks and socially constructed markets is undertaken. These concepts include the "milieu" of project marketing (Cova et al., 1996......) and the institutional concept of the "field". Finally this paper introduces the concept of "social capital" (Bourdieu, 1983) and discusses whether it can be used to conceptualize the dynamic features of actor bonds in situations of discontinuity....
Discontinuities of BFKL amplitudes and the BDS ansatz
Fadin, V. S.; Fiore, R.
2015-12-01
We perform an examination of discontinuities of multiple production amplitudes, which are required for further development of the BFKL approach. It turns out that the discontinuities of 2 → 2 + n amplitudes obtained in the BFKL approach contradict to the BDS ansatz for amplitudes with maximal helicity violation in N = 4 supersymmetric Yang-Mills theory with large number of colors starting with n = 2. Explicit expressions for the discontinuities of the 2 → 3 and 2 → 4 amplitudes in the invariant mass of pairs of produced gluons are obtained in the planar N = 4 SYM in the next-to-leading logarithmic approximation. These expressions can be used for checking the conjectured duality between the light-like Wilson loops and the MHV amplitudes.
Magnetic and transport properties of discontinuous metal-oxides multilayers
Dinia, A.; Schmerber, G.; Ulhaq, C.; El Bahraoui, T
2003-02-15
We report on structural, magnetic and transport properties of Al{sub 2}O{sub 3}/CoFe discontinuous multilayers deposited by RF sputtering at room temperature on silicon substrate. Transmission electron microscopy observations show that these multilayers consist of discontinuous layers of CoFe particles embedded in an insulating Al{sub 2}O{sub 3} matrix. This is further supported by magnetization measurements showing the presence at room temperature of both superparamagnetic and ferromagnetic components. The current-in-plane resistivity of the discontinuous multilayers has shown a negative magnetoresistance due to a spin-dependent tunneling between the CoFe magnetic particles through the insulating Al{sub 2}O{sub 3} barrier. The magnetoresistance response gives rise to two spin-dependent tunneling contributions. A contribution at small applied fields due to ferromagnetic particles and a contribution at larger magnetic applied fields due to a superparamagnetic particles.
Discontinuities of BFKL amplitudes and the BDS ansatz
V.S. Fadin
2015-12-01
Full Text Available We perform an examination of discontinuities of multiple production amplitudes, which are required for further development of the BFKL approach. It turns out that the discontinuities of 2→2+n amplitudes obtained in the BFKL approach contradict to the BDS ansatz for amplitudes with maximal helicity violation in N=4 supersymmetric Yang–Mills theory with large number of colors starting with n=2. Explicit expressions for the discontinuities of the 2→3 and 2→4 amplitudes in the invariant mass of pairs of produced gluons are obtained in the planar N=4 SYM in the next-to-leading logarithmic approximation. These expressions can be used for checking the conjectured duality between the light-like Wilson loops and the MHV amplitudes.
Solutions of the Wheeler-Feynman equations with discontinuous velocities
de Souza, Daniel Câmara
2014-01-01
We generalize Wheeler-Feynman electrodynamics with a variational boundary-value problem having boundary conditions in past and future. The extended variational problem accepts trajectories with discontinuous velocities as critical points of the action functional. Critical-point trajectories must satisfy the Euler-Lagrange equations of the action functional, which are neutral-differential delay equations of motion. Moreover, at velocity discontinuity points critical-point orbits must satisfy the Weierstrass-Erdmann corner conditions of continuity of the partial momenta and partial energies. We study a special class of boundary data having the shortest time-separation between boundary segments, for which case the Wheeler-Feynman equations reduce to a two-point boundary problem for an ordinary differential equation. For this simple case we prove that solutions of the Wheeler-Feynman equations can have discontinuous velocities. We construct a numerical method to find critical-point orbits with a shooting method f...
Discontinuous Galerkin method analysis and applications to compressible flow
Dolejší, Vít
2015-01-01
The subject of the book is the mathematical theory of the discontinuous Galerkin method (DGM), which is a relatively new technique for the numerical solution of partial differential equations. The book is concerned with the DGM developed for elliptic and parabolic equations and its applications to the numerical simulation of compressible flow. It deals with the theoretical as well as practical aspects of the DGM and treats the basic concepts and ideas of the DGM, as well as the latest significant findings and achievements in this area. The main benefit for readers and the book’s uniqueness lie in the fact that it is sufficiently detailed, extensive and mathematically precise, while at the same time providing a comprehensible guide through a wide spectrum of discontinuous Galerkin techniques and a survey of the latest efficient, accurate and robust discontinuous Galerkin schemes for the solution of compressible flow.
A tessellated continuum approach to thermal analysis: discontinuity networks
Jiang, C.; Davey, K.; Prosser, R.
2017-01-01
Tessellated continuum mechanics is an approach for the representation of thermo-mechanical behaviour of porous media on tessellated continua. It involves the application of iteration function schemes using affine contraction and expansion maps, respectively, for the creation of porous fractal materials and associated tessellated continua. Highly complex geometries can be produced using a modest number of contraction mappings. The associated tessellations form the mesh in a numerical procedure. This paper tests the hypothesis that thermal analysis of porous structures can be achieved using a discontinuous Galerkin finite element method on a tessellation. Discontinuous behaviour is identified at a discontinuity network in a tessellation; its use is shown to provide a good representation of the physics relating to cellular heat exchanger designs. Results for different cellular designs (with corresponding tessellations) are contrasted against those obtained from direct analysis and very high accuracy is observed.
A non-conventional discontinuous Lagrangian for viscous flow
Scholle, M.; Marner, F.
2017-02-01
Drawing an analogy with quantum mechanics, a new Lagrangian is proposed for a variational formulation of the Navier-Stokes equations which to-date has remained elusive. A key feature is that the resulting Lagrangian is discontinuous in nature, posing additional challenges apropos the mathematical treatment of the related variational problem, all of which are resolvable. In addition to extending Lagrange's formalism to problems involving discontinuous behaviour, it is demonstrated that the associated equations of motion can self-consistently be interpreted within the framework of thermodynamics beyond local equilibrium, with the limiting case recovering the classical Navier-Stokes equations. Perspectives for applying the new formalism to discontinuous physical phenomena such as phase and grain boundaries, shock waves and flame fronts are provided.
Active postoperative acromegaly: sustained remission after discontinuation of somatostatin analogues
Cardenas-Salas, Jersy
2016-01-01
Summary In patients with active acromegaly after pituitary surgery, somatostatin analogues are effective in controlling the disease and can even be curative in some cases. After treatment discontinuation, the likelihood of disease recurrence is high. However, a small subset of patients remains symptom-free after discontinuation, with normalized growth hormone (GH) and insulin-like growth factor (IGF1) levels. The characteristics of patients most likely to achieve sustained remission after treatment discontinuation are not well understood, although limited evidence suggests that sustained remission is more likely in patients with lower GH and IGF1 levels before treatment withdrawal, in those who respond well to low-dose treatment, in those without evidence of adenoma on an MRI scan and/or in patients who receive long-term treatment. In this report, we describe the case of a 56-year-old female patient treated with lanreotide Autogel for 11 years. Treatment was successfully discontinued, and the patient is currently disease-free on all relevant parameters (clinical, biochemical and tumour status). The successful outcome in this case adds to the small body of literature suggesting that some well-selected patients who receive long-term treatment with somatostatin analogues may achieve sustained remission. Learning points: The probability of disease recurrence is high after discontinuation of treatment with somatostatin analogues. Current data indicate that remission after treatment discontinuation may be more likely in patients with low GH and IGF1 levels before treatment withdrawal, in those who respond well to low-dose treatment, in those without evidence of adenoma on MRI, and/or in patients receiving prolonged treatment. This case report suggests that prolonged treatment with somatostatin analogues can be curative in carefully selected patients. PMID:27933171
NUMERICAL SIMULATION OF SHOCK WAVE REFRACTION ON INCLINED CONTACT DISCONTINUITY
P. V. Bulat
2016-05-01
Full Text Available We consider numerical simulation of shock wave refraction on plane contact discontinuity, separating two gases with different density. Discretization of Euler equations is based on finite volume method and WENO finite difference schemes, implemented on unstructured meshes. Integration over time is performed with the use of the third-order Runge–Kutta stepping procedure. The procedure of identification and classification of gas dynamic discontinuities based on conditions of dynamic consistency and image processing methods is applied to visualize and interpret the results of numerical calculations. The flow structure and its quantitative characteristics are defined. The results of numerical and experimental visualization (shadowgraphs, schlieren images, and interferograms are compared.
Monotonicity Formula and Regularity for General Free Discontinuity Problems
Bucur, Dorin; Luckhaus, Stephan
2014-02-01
We give a general monotonicity formula for local minimizers of free discontinuity problems which have a critical deviation from minimality, of order d - 1. This result allows us to prove partial regularity results (that is closure and density estimates for the jump set) for a large class of free discontinuity problems involving general energies associated to the jump set, as for example free boundary problems with Robin conditions. In particular, we give a short proof to the De Giorgi-Carriero-Leaci result for the Mumford-Shah functional.
Trapped electromagnetic modes in a waveguide with a small discontinuity
Stupakov, G. V.; Kurennoy, S. S.
1994-01-01
We demonstrate that a small discontinuity (such as an enlargement or a hole) on a smooth waveguide can result in the appearance of trapped modes localized in the vicinity of the discontinuity. The frequencies of these modes lie slightly below the cutoff frequencies of the corresponding propagating modes in the waveguide. We find the distribution of the electromagnetic field in the modes and calculate their damping rate due to a finite conductivity of the walls. The contribution of the trapped modes to the longitudinal impedance is calculated.
Quantitative Estimation of Transmitted and Reflected Lamb Waves at Discontinuity
Lim, Hyung Jin; Sohn, Hoon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)
2010-08-15
For the application of Lamb wave to structural health monitoring(SHM), understanding its physical characteristic and interaction between Lamb wave and defect of the host structure is an important issue. In this study, reflected, transmitted and mode converted Lamb waves at discontinuity of a plate structure were simulated and the amplitude ratios are calculated theoretically using Modal decomposition method. The predicted results were verified comparing with finite element method(FEM) and experimental results simulating attached PZTs. The result shows that the theoretical prediction is close to the FEM and the experimental verification. Moreover, quantitative estimation method was suggested using amplitude ratio of Lamb wave at discontinuity
Analytical large deformation shear strength for bolted rough discontinuous rock
LIU Bo(刘波); TAO Long-guang(陶龙光); YUE Zhong-qi(岳中琦)
2004-01-01
Presented a new analytical model for studying the shear-tensile large deformation behavior near the vicinity of joint interface for bolted rough discontinuous rock, and presented the formulation estimating global shear strength for bolted joints under shearing-tensile loads. The analytical strength curves of bolts contribution on reinforced discontinuous rocks as the function of joint displacements or deformation angle of a bolt at rock joints was obtained. Based on Barton's equation on JRC roughness profiles, the theoretical shearing strength of bolted rough joints was also established. Test results on bolted granite and marble specimen confirm the validity of the analytical approach.
Becoming an English language teacher: Continuities and Discontinuities
Werbińska Dorota
2015-01-01
Full Text Available The aim of the paper is to report a three-year phenomenographic study conducted on seven EFL Polish teachers with the focus on presenting how they experience different aspects of language teaching at three crucial stages: 1 the time of ELT theory studying, 2 the time of school placement, 3 the time of first-year working as professional teachers. Each stage of the study is presented from the perspective of affordances standing for the respondents’ expectations (continuities as well as constraints (discontinuities. The article concludes that discontinuities, rather than continuities, can prove invaluable in language teacher identity development.
Straight to the point: how people encode linear discontinuations
Rodrigo I. Mora
2012-12-01
Full Text Available Spatial discontinuations, as those found in cities and buildings, are everyday events. But, how do we encode and classify such misalignments? This is the topic of this paper. Twenty participants were asked to classify a total of 51 icons showing an upward-moving line being misaligned to the right, left and straight down. The results show that subjects were very sensitive to slight discontinuations occurring to vertical lines and that there was not exact symmetry between the left and right axis, meaning that the pieces slightly misaligned to the left were encoded differently than those misaligned to the right
Discontinuous Galerkin finite element methods for gradient plasticity.
Garikipati, Krishna. (University of Michigan, Ann Arbor, MI); Ostien, Jakob T.
2010-10-01
In this report we apply discontinuous Galerkin finite element methods to the equations of an incompatibility based formulation of gradient plasticity. The presentation is motivated with a brief overview of the description of dislocations within a crystal lattice. A tensor representing a measure of the incompatibility with the lattice is used in the formulation of a gradient plasticity model. This model is cast in a variational formulation, and discontinuous Galerkin machinery is employed to implement the formulation into a finite element code. Finally numerical examples of the model are shown.
Faranoff-Riley type I jet deceleration at density discontinuities
Meliani, Z.; Keppens, R.; Giacomazzo, B.
2008-01-01
Aims. We propose a model that could explain the sudden jet deceleration in active galactic nuclei, thereby invoking density discontinuities. Motivated particularly by recent indications from HYbrid MOrphology Radio Sources (HYMORS) that Fanaroff-Riley classification is induced in some cases by varia
Active postoperative acromegaly: sustained remission after discontinuation of somatostatin analogues
Cristina Alvarez-Escola
2016-11-01
Full Text Available In patients with active acromegaly after pituitary surgery, somatostatin analogues are effective in controlling the disease and can even be curative in some cases. After treatment discontinuation, the likelihood of disease recurrence is high. However, a small subset of patients remains symptom-free after discontinuation, with normalized growth hormone (GH and insulin-like growth factor (IGF1 levels. The characteristics of patients most likely to achieve sustained remission after treatment discontinuation are not well understood, although limited evidence suggests that sustained remission is more likely in patients with lower GH and IGF1 levels before treatment withdrawal, in those who respond well to low-dose treatment, in those without evidence of adenoma on an MRI scan and/or in patients who receive long-term treatment. In this report, we describe the case of a 56-year-old female patient treated with lanreotide Autogel for 11 years. Treatment was successfully discontinued, and the patient is currently disease-free on all relevant parameters (clinical, biochemical and tumour status. The successful outcome in this case adds to the small body of literature suggesting that some well-selected patients who receive long-term treatment with somatostatin analogues may achieve sustained remission.
Effects of discontinuous magnetic permeability on magnetodynamic problems
Guermond, J.-L.
2011-07-01
A novel approximation technique using Lagrange finite elements is proposed to solve magneto-dynamics problems involving discontinuous magnetic permeability and non-smooth interfaces. The algorithm is validated on benchmark problems and is used for kinematic studies of the Cadarache von Kármán Sodium 2 (VKS2) experimental fluid dynamo. © 2011 Elsevier Inc.
19 CFR 112.14 - Discontinuance of carrier bonds.
2010-04-01
... 19 Customs Duties 1 2010-04-01 2010-04-01 false Discontinuance of carrier bonds. 112.14 Section 112.14 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT... Commissioner of Customs or by the director of the port where the bond is filed. Authorized carriers desiring...
38 CFR 8.17 - Discontinuance of premium waiver.
2010-07-01
... SERVICE LIFE INSURANCE Premium Waivers and Total Disability § 8.17 Discontinuance of premium waiver. (a... premiums shall cease as of the date of such finding, and the insurance may be continued by payment of..., and if such premium was not paid within 31 days after the due date, the insurance lapsed. (c) If...
MONOTONE ITERATION FOR ELLIPTIC PDEs WITH DISCONTINUOUS NONLINEAR TERMS
Zou Qingsong
2005-01-01
In this paper, we use monotone iterative techniques to show the existence of maximal or minimal solutions of some elliptic PDEs with nonlinear discontinuous terms. As the numerical analysis of this PDEs is concerned, we prove the convergence of discrete extremal solutions.
Predictors of benzodiazepine discontinuation in subjects manifesting complicated dependence.
Vorma, Helena; Naukkarinen, Hannu H; Sarna, Seppo J; Kuoppasalmi, Kimmo I
2005-01-01
We described characteristics of subjects with benzodiazepine dependence that was typically complicated by harmful and hazardous alcohol use or high benzodiazepine doses, and assessed predictors of successful discontinuation of benzodiazepines for this group. Seventy-six patients who participated in a randomized clinical trial of two different gradual withdrawal treatment approaches were assessed. The trial was conducted between February 1995 and July 1999. The mean age +/- SD of subjects was 40.0 +/- 9.6 years, 55% were male, 38% were married or cohabiting, and 70% had received more than nine years of education. The median benzodiazepine dose was 35 mg/day (range 2.5-180) in diazepam equivalents. The median duration of benzodiazepine use was 84 (range 8-360) months. Subjects with lower benzodiazepine doses and no previous withdrawal attempts were more successful at benzodiazepine discontinuation. Cluster B personality/borderline personality disorder was associated with an inability to stop benzodiazepine use and with "dropping out" of treatment. Alcohol use-related disorders or other psychiatric diagnoses were not associated with outcome. Further studies on predictors of successful benzodiazepine discontinuation in different populations are required. Patients manifesting cluster B personality/borderline personality disorder and benzodiazepine dependence may need concomitant treatment for their personality disorders to benefit from benzodiazepine discontinuation treatment.
The influence of Discontinuous Transmission on RXQUAL statistics in GSM
Wigard, Jeroen; Nielsen, Thomas Toftegaard; Skjærris, Søren
1999-01-01
Discontinuous transmission (DTX) is a feature which has been reported to give about 2.5 dB gain in C/I performance. However in real life, network operators, who switch on DTX, often experience a loss in performance. They measure the performance by the RXQUAL distribution. RXQUAL is a quality para...
Premature Discontinuation in Adult Psychotherapy: A Meta-Analysis
Swift, Joshua K.; Greenberg, Roger P.
2012-01-01
Objective: Premature discontinuation from therapy is a widespread problem that impedes the delivery of otherwise effective psychological interventions. The most recent comprehensive review found an average dropout rate of 47% across 125 studies (Wierzbicki & Pekarik, 1993); however, given a number of changes in the field over the past 2 decades,…
Regression Discontinuity Designs with Multiple Rating-Score Variables
Reardon, Sean F.; Robinson, Joseph P.
2012-01-01
In the absence of a randomized control trial, regression discontinuity (RD) designs can produce plausible estimates of the treatment effect on an outcome for individuals near a cutoff score. In the standard RD design, individuals with rating scores higher than some exogenously determined cutoff score are assigned to one treatment condition; those…
Reflected Backward Doubly Stochastic Differential Equations with Discontinuous Coefficients
Zhi LI; Jiao Wan LUO
2013-01-01
In this paper,we study one-dimensional reflected backward doubly stochastic differential equations (RBDSDEs) with one continuous barrier and discontinuous (left or right continuous) generator.We obtain an existence theorem and a comparison theorem for solutions of the class of RBDSDEs.
An implicit discontinuous Galerkin finite element model for water waves
van der Vegt, Jacobus J.W.; Ambati, V.R.; Bokhove, Onno
2005-01-01
We discuss a new higher order accurate discontinuous Galerkin finite element method for non-linear free surface gravity waves. The algorithm is based on an arbitrary Lagrangian Eulerian description of the flow field using deforming elements and a moving mesh, which makes it possible to represent
Local discontinuous Galerkin methods for phase transition problems
Tian, Lulu
2015-01-01
In this thesis we develop a local discontinuous Galerkin (LDG) finite element method to solve mathematical models for phase transitions in solids and fluids. The first model we study is called a viscosity-capillarity (VC) system associated with phase transitions in elastic bars and Van der Waals
Effects of discontinuities on penetration of TBM cutters
刘杰; 曹平; 杜春黄; 蒋喆; 刘京铄
2015-01-01
Based on the triaxial testing machine and discrete element method, the effects of embedded crack on rock fragmentation are investigated in laboratory tests and a series of numerical investigations are conducted on the effects of discontinuities on cutting characteristics and cutting efficiency. In laboratory tests, five propagation patterns of radial cracks are observed. And in the numerical tests, firstly, it is similar to laboratory tests that cracks ahead of cutters mainly initiate from the crushed zone, and some minor cracks will initiate from joints. The cracks initiating from crushed zones will run through the thinner joints while they will be held back by thick joints. Cracks tend to propagate towards the tips of embedded cracks, and minor cracks will initiate from the tips of embedded cracks, which may result in the decrease of specific area, and disturbing layers play as ‘screens’, which will prevent cracks from developing greatly. The peak penetration forces, the consumed energy in the penetration process and the uniaxial compression strength will decrease with the increase of discontinuities. The existence of discontinuities will result in the decrease of the cutting efficiency when the spacing between cutters is 70 mm. Some modifications should be made to improve the efficiency when the rocks containing groups of discontinuities are encountered.
QUASILINEAR ELLIPTIC BOUNDARY VALUE PROBLEMS WITH DISCONTINUOUS NONLINEARITIES
无
2000-01-01
In this paper we shall consider a discontinuous nonlinear nonmonotone elliptic boundary value problem, i.e. a quasilinear elliptic hemivariational inequality. This kind of problems is strongly motivated by various problems in mechanics. By use of the notion of the generalized gradient of Clarke and the theory of pseudomonotone operators, we will prove the existence of solutions.
Kinetic theory and turbulent discontinuities. [shock tube flow
Johnson, J. A., III; I, L.; Li, Y.; Ramaian, R.; Santigo, J. P.
1981-01-01
Shock tube discontinuities were used to test and extend a kinetic theory of turbulence. In shock wave and contact surface fluctuations, coherent phenomena were found which provide new support for the microscopic nonempirical approach to turbulent systems, especially those with boundary layer-like instabilities.
Lighting of discontinuities in the course of roads.
Schreuder, D.A.
1966-01-01
It immediately follows from the definition of discontinuities that some thought must be devoted to the consequences of their presence with regard to the lighting-arrangements to be made for the road system, because in the first place the road user must be warned in good time that he is approaching p
DESIGN OF NONCIRCULAR GEARS WITH DISCONTINUOUS PITCH CURVE
ZHANG Rui; WU Xutang
2006-01-01
When the noncircular gear pair is applied to the continuously variable transmission (CVT)with gear, the transmission ratio function is discontinuous. In accordance with this unique characteristic, a new approach to design and analyze noncircular gears with discontinuous pitch curve is proposed. The design courses of various noncircular gear pairs with discontinuous pitch curve are unified based on the numerical algorithm of spline fitting and "fairing boundary condition".According to the particularity of discontinuous pitch curve, the rules and procedures for teeth distribution are recommended. It is explained in detail why the undercut is formed and how to manage the undercut based on meshing principle. In addition, the calculation formulas for each tooth profile segment are also derived. If the tooth profile data are calculated, the measurement and the incision process for noncircular gear can be conducted and the CAD simulation can be achieved easily. To ensure the continuity of the transmission, the transmission interference of the tooth which is located at ratio of gear pair is obtained. The case study shows that this approach is successful and opens up a new way for the design ofnoncircular gear.
Discontinuous Galerkin error estimation for linear symmetric hyperbolic systems
Adjerid, Slimane; Weinhart, Thomas
2009-01-01
In this manuscript we present an error analysis for the discontinuous Galerkin discretization error of multi-dimensional first-order linear symmetric hyperbolic systems of partial differential equations. We perform a local error analysis by writing the local error as a series and showing that its le
20 CFR 658.501 - Basis for discontinuation of services.
2010-04-01
... pursuant to § 653.503; or (8) Repeatedly cause the initiation of the procedures for discontinuation of....501 Section 658.501 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR... procedures set forth in this subpart at §§ 658.501 through 658.502 would cause substantial harm to a...
Dialogic Reverberations: Police, Domestic Abuse, and the Discontinuance of Cases
Lea, Susan J.; Lynn, Nick
2012-01-01
This study investigated the social construction of domestic abuse by police officers, specifically in the context of arguments presented to the prosecutor for a decision on whether to proceed with or discontinue the case. Nineteen police files were examined with a particular focus on the MG3, the "Report to Crown Prosecutors for Charging…
A Bayesian Nonparametric Causal Model for Regression Discontinuity Designs
Karabatsos, George; Walker, Stephen G.
2013-01-01
The regression discontinuity (RD) design (Thistlewaite & Campbell, 1960; Cook, 2008) provides a framework to identify and estimate causal effects from a non-randomized design. Each subject of a RD design is assigned to the treatment (versus assignment to a non-treatment) whenever her/his observed value of the assignment variable equals or…
The Analysis of the Regression-Discontinuity Design in R
Thoemmes, Felix; Liao, Wang; Jin, Ze
2017-01-01
This article describes the analysis of regression-discontinuity designs (RDDs) using the R packages rdd, rdrobust, and rddtools. We discuss similarities and differences between these packages and provide directions on how to use them effectively. We use real data from the Carolina Abecedarian Project to show how an analysis of an RDD can be…
Application of Discontinuous PWM Modulation in Active Power Filters
Blaabjerg, Frede; Asiminoaei, Lucian; Rodriguez, Pedro
2008-01-01
Classical discontinuous pulsewidth modulations (DPWMs) may not be efficiently applied in active power filters (APFs), because it is hard to predict the peak values of the inverter current, and consequently it is difficult to calculate the position of the clamped interval, that minimizes the switc...
Reversible brain inactivation induces discontinuous gas exchange in cockroaches.
Matthews, Philip G D; White, Craig R
2013-06-01
Many insects at rest breathe discontinuously, alternating between brief bouts of gas exchange and extended periods of breath-holding. The association between discontinuous gas exchange cycles (DGCs) and inactivity has long been recognised, leading to speculation that DGCs lie at one end of a continuum of gas exchange patterns, from continuous to discontinuous, linked to metabolic rate (MR). However, the neural hypothesis posits that it is the downregulation of brain activity and a change in the neural control of gas exchange, rather than low MR per se, which is responsible for the emergence of DGCs during inactivity. To test this, Nauphoeta cinerea cockroaches had their brains inactivated by applying a Peltier-chilled cold probe to the head. Once brain temperature fell to 8°C, cockroaches switched from a continuous to a discontinuous breathing pattern. Re-warming the brain abolished the DGC and re-established a continuous breathing pattern. Chilling the brain did not significantly reduce the cockroaches' MR and there was no association between the gas exchange pattern displayed by the insect and its MR. This demonstrates that DGCs can arise due to a decrease in brain activity and a change in the underlying regulation of gas exchange, and are not necessarily a simple consequence of low respiratory demand.
Continuities and Discontinuities in Psychopathology between Childhood and Adult Life
Rutter, Michael; Kim-Cohen, Julia; Maughan, Barbara
2006-01-01
The possible mechanisms involved in continuities and discontinuities in psychopathology between childhood and adult life are considered in relation to the findings from systematic, prospective, long-term longitudinal studies. Findings on schizophrenia, neurodevelopmental disorders, emotional disturbances, antisocial behaviour and substance abuse…
Reasons for Intrauterine Device Use, Discontinuation and Non-Use ...
AJRH Managing Editor
insights into reasons for using, discontinuing, or not using the IUD. We conducted ... Reasons for IUD use in Malawi ... who never received the IUD (“IUD non-user,” n=7). Women .... heart and cause death, and that the IUD impedes sex. .... Interviewer: Okay, is there anyone who assisted you in your decision not to take part?
Data-oriented parsing with discontinuous constituents and function tags
Andreas van Cranenburgh
2016-04-01
Full Text Available Statistical parsers are e ective but are typically limited to producing projective dependencies or constituents. On the other hand, linguisti- cally rich parsers recognize non-local relations and analyze both form and function phenomena but rely on extensive manual grammar development. We combine advantages of the two by building a statistical parser that produces richer analyses. We investigate new techniques to implement treebank-based parsers that allow for discontinuous constituents. We present two systems. One system is based on a string-rewriting Linear Context-Free Rewriting System (LCFRS, while using a Probabilistic Discontinuous Tree Substitution Grammar (PDTSG to improve disambiguation performance. Another system encodes the discontinuities in the labels of phrase structure trees, allowing for efficient context-free grammar parsing.The two systems demonstrate that tree fragments as used in tree-substitution grammar improve disambiguation performance while capturing non-local relations on an as-needed basis. Additionally, we present results of models that produce function tags, resulting in a more linguistically adequate model of the data. We report substantial accuracy improvements in discontinuous parsing for German, English, and Dutch, including results on spoken Dutch.
Grades, Gender, and Encouragement: A Regression Discontinuity Analysis
Owen, Ann L.
2010-01-01
The author employs a regression discontinuity design to provide direct evidence on the effects of grades earned in economics principles classes on the decision to major in economics and finds a differential effect for male and female students. Specifically, for female students, receiving an A for a final grade in the first economics class is…
A Simple Stochastic Differential Equation with Discontinuous Drift
Simonsen, Maria; Leth, John-Josef; Schiøler, Henrik
2013-01-01
In this paper we study solutions to stochastic differential equations (SDEs) with discontinuous drift. We apply two approaches: The Euler-Maruyama method and the Fokker-Planck equation and show that a candidate density function based on the Euler-Maruyama method approximates a candidate density f...
Space-time discontinuous Galerkin finite element methods
Vegt, van der J.J.W.; Deconinck, H.; Ricchiuto, M.
2006-01-01
In these notes an introduction is given to space-time discontinuous Galerkin (DG) finite element methods for hyperbolic and parabolic conservation laws on time dependent domains. the space-time DG discretization is explained in detail, including the definition of the numerical fluxes and stabilizati
Faranoff-Riley type I jet deceleration at density discontinuities
Meliani, Z.; Keppens, R.; Giacomazzo, B.
2008-01-01
Aims. We propose a model that could explain the sudden jet deceleration in active galactic nuclei, thereby invoking density discontinuities. Motivated particularly by recent indications from HYbrid MOrphology Radio Sources (HYMORS) that Fanaroff-Riley classification is induced in some cases by
Space-time discontinuous Galerkin method for compressible flow
Klaij, C.M.
2006-01-01
The space-time discontinuous Galerkin method allows the simulation of compressible flow in complex aerodynamical applications requiring moving, deforming and locally refined meshes. This thesis contains the space-time discretization of the physical model, a fully explicit solver for the resulting
Prolonged effect of Rosiglitazone one year after discontinuation
Gram-Kampmann, Eva-Marie; Olesen, Thomas Bastholm; Olsen, Michael Hecht
2015-01-01
Hypotese og formål: Rosiglitazone is a PPARγ-receptor agonist. It enhances glycemic control by increasing insulin sensitivity in fat- and muscle cells. This study addresses what to expect when discontinuing Rosiglitazone in type 2-diabetic patients who are also treated with insulin. Metoder...
Error Analysis for Discontinuous Galerkin Method for Parabolic Problems
Kaneko, Hideaki
2004-01-01
In the proposal, the following three objectives are stated: (1) A p-version of the discontinuous Galerkin method for a one dimensional parabolic problem will be established. It should be recalled that the h-version in space was used for the discontinuous Galerkin method. An a priori error estimate as well as a posteriori estimate of this p-finite element discontinuous Galerkin method will be given. (2) The parameter alpha that describes the behavior double vertical line u(sub t)(t) double vertical line 2 was computed exactly. This was made feasible because of the explicitly specified initial condition. For practical heat transfer problems, the initial condition may have to be approximated. Also, if the parabolic problem is proposed on a multi-dimensional region, the parameter alpha, for most cases, would be difficult to compute exactly even in the case that the initial condition is known exactly. The second objective of this proposed research is to establish a method to estimate this parameter. This will be done by computing two discontinuous Galerkin approximate solutions at two different time steps starting from the initial time and use them to derive alpha. (3) The third objective is to consider the heat transfer problem over a two dimensional thin plate. The technique developed by Vogelius and Babuska will be used to establish a discontinuous Galerkin method in which the p-element will be used for through thickness approximation. This h-p finite element approach, that results in a dimensional reduction method, was used for elliptic problems, but the application appears new for the parabolic problem. The dimension reduction method will be discussed together with the time discretization method.
Discontinuation of oxytocin in the active phase of labor.
Girard, Bénédicte; Vardon, Delphine; Creveuil, Christian; Herlicoviez, Michel; Dreyfus, Michel
2009-01-01
To show that early discontinuation of oxytocin will not increase the mean duration of the active labor phase in a clinically significant way. Controlled non-inferiority study. Department of Obstetrics and Gynecology, University of Caen, Clemenceau Hospital, France. A total of 138 women with singleton pregnancy and a vertex presentation of over 34 gestational weeks, presenting a medical indication of induction of labor or a dystocia at onset of labor, from May 2005 to June 2006. Two parallel groups were compared: continuation of oxytocin until delivery versus discontinuation of oxytocin at the onset of the active phase. The clinically acceptable increase in mean duration of the active phase of labor (non-inferiority margin) was set at 60 minutes. Primary outcome measure was duration of the active labor phase. Secondary outcome measures included total duration of labor, parameters concerning oxytocin use, rates of uterine hyperstimulation and fetal heart rate (FHR) abnormalities, and mode of delivery. Some neonatal outcomes were also analyzed. Equivalence of the two strategies (continuation vs. discontinuation of oxytocin) was not demonstrated (p=0.97 testing for non-inferiority), the active phase even being significantly longer by a mean of 113 minutes (p=0.0001 testing for superiority). The rates of cesarean sections, alterations of FHR and delivery hemorrhage were higher when oxytocin was continued, but not significantly. There were significantly more infants hospitalized in neonatology when oxytocin was continued (p=0.028). Discontinuation of oxytocin at the onset of the active phase prolongs labor. We found no argument for discontinuing the infusion of oxytocin at the onset of the active phase.
Reasons given by mothers for discontinuing breastfeeding in Iran
Olang Beheshteh
2012-05-01
Full Text Available Abstract Background We have previously shown that in Iran, only 28% of infants were exclusively breastfed at six months, despite a high prevalence of breastfeeding at two years of age. The primary aim of this study was to investigate the reasons women discontinued exclusive breastfeeding. Method This retrospective study was based on questionnaires and interviews with 63,071 mothers of infants up to 24 months of age, divided into two populations: infants younger than six months and six months or older. The data were collected in 2005–2006 from all 30 provinces of Iran. Results Only 5.3% of infants less than six months of age stopped breastfeeding (mean age of 3.2 months; more commonly in urban than rural areas. The most frequently cited reasons mothers gave for discontinuing exclusive breastfeeding were physicians’ recommendation (54% and insufficient breast milk (self-perceived or true, 28%. Breastfeeding was common after six months of age: only 11% of infants discontinued breastfeeding, at a mean of 13.8 months. The most common reason for discontinuation at this age was insufficient breast milk (self-perceived or true, 45%. Maternal illness or medication (10%, infant illness (6%, and return to work (3% were uncommon causes. Use of a pacifier was correlated with breastfeeding discontinuation. Maternal age and education was not associated with duration of breastfeeding. Multivariate analysis showed that using a pacifier and formula or other bottle feeding increased the risk of early cessation of breastfeeding. Conclusions Physicians and other health professionals have an important role to play in encouraging and supporting mothers to maintain breastfeeding.
Clopidogrel discontinuation and platelet reactivity following coronary stenting
2011-01-01
Summary. Aims: Antiplatelet therapy with aspirin and clopidogrel is recommended for 1 year after drug-eluting stent (DES) implantation or myocardial infarction. However, the discontinuation of antiplatelet therapy has become an important issue as recent studies have suggested a clustering of ischemic events within 90 days of clopidogrel withdrawal. The objective of this investigation was to explore the hypothesis that there is a transient ‘rebound’ increase in platelet reactivity within 3 months of clopidogrel discontinuation. Methods and Results: In this prospective study, platelet function was assessed in patients taking aspirin and clopidogrel for at least 1 year following DES implantation. Platelet aggregation was measured using a modification of light transmission aggregometry in response to multiple concentrations of adenosine diphosphate (ADP), epinephrine, arachidonic acid, thrombin receptor activating peptide and collagen. Clopidogrel was stopped and platelet function was reassessed 1 week, 1 month and 3 months later. Thirty-two patients on dual antiplatelet therapy were recruited. Discontinuation of clopidogrel increased platelet aggregation to all agonists, except arachidonic acid. Platelet aggregation in response to ADP (2.5, 5, 10, and 20 μm) and epinephrine (5 and 20 μm) was significantly increased at 1 month compared with 3 months following clopidogrel withdrawal. Thus, a transient period of increased platelet reactivity to both ADP and epinephrine was observed 1 month after clopidogrel discontinuation. Conclusions: This study demonstrates a transient increase in platelet reactivity 1 month after clopidogrel withdrawal. This phenomenon may, in part, explain the known clustering of thrombotic events observed after clopidogrel discontinuation. This observation requires confirmation in larger populations.
Gradual vs. wait-and-gradual discontinuation in antipsychotic switching: A meta-analysis.
Takeuchi, Hiroyoshi; Thiyanavadivel, Sadhana; Agid, Ofer; Remington, Gary
2017-02-24
To address whether wait discontinuation (i.e., introducing the new antipsychotic while maintaining the first for a period before initiating its discontinuation) is superior to non-wait discontinuation (i.e., initiating the first antipsychotic's discontinuation when introducing the new antipsychotic) in antipsychotic switching, we conducted a meta-analysis of randomized controlled trials comparing gradual vs. wait-and-gradual antipsychotic discontinuation in patients with schizophrenia. The meta-analysis of 5 studies (n=410) demonstrated no significant differences in any clinical outcomes, including study discontinuation, psychopathology, extrapyramidal symptoms, and treatment-emergent adverse events, between the two groups. These findings indicate either strategy can be used in clinical practice.
Unintentional Discontinuation of Chronic Medications for Seniors in Nursing Homes
Stall, Nathan M.; Fischer, Hadas D.; Wu, C. Fangyun; Bierman, Arlene S.; Brener, Stacey; Bronskill, Susan; Etchells, Edward; Fernandes, Olavo; Lau, Davina; Mamdani, Muhammad M.; Rochon, Paula; Urbach, David R.; Bell, Chaim M.
2015-01-01
Abstract Transitions of care leave patients vulnerable to the unintentional discontinuation of medications with proven efficacy for treating chronic diseases. Older adults residing in nursing homes may be especially susceptible to this preventable adverse event. The effect of large-scale policy changes on improving this practice is unknown. The objective of this study was to analyze the effect of a national medication reconciliation accreditation requirement for nursing homes on rates of unintentional medication discontinuation after hospital discharge. It was a population-based retrospective cohort study that used linked administrative records between 2003 and 2012 of all hospitalizations in Ontario, Canada. We identified nursing home residents aged ≥66 years who had continuous use of ≥1 of the 3 selected medications for chronic disease: levothyroxine, HMG-CoA reductase inhibitors (statins), and proton pump inhibitors (PPIs). In 2008 medication reconciliation became a required practice for accreditation of Canadian nursing homes. The main outcome measures included the proportion of patients who restarted the medication of interest after hospital discharge at 7 days. We also performed a time series analysis to examine the impact of the accreditation requirement on rates of unintentional medication discontinuation. The study included 113,088 adults aged ≥66 years who were nursing home residents, had an acute hospitalization, and were discharged alive to the same nursing home. Overall rates of discontinuation at 7-days after hospital discharge were highest in 2003–2004 for all nursing homes: 23.9% for thyroxine, 26.4% for statins, and 23.9% for PPIs. In most of the cases, these overall rates decreased annually and were lowest in 2011–2012: 4.0% for thyroxine, 10.6% for statins, and 8.3% for PPIs. The time series analysis found that nursing home accreditation did not significantly lower medication discontinuation rates for any of the 3 drug groups. From 2003
Finite element and discontinuous Galerkin methods for transient wave equations
Cohen, Gary
2017-01-01
This monograph presents numerical methods for solving transient wave equations (i.e. in time domain). More precisely, it provides an overview of continuous and discontinuous finite element methods for these equations, including their implementation in physical models, an extensive description of 2D and 3D elements with different shapes, such as prisms or pyramids, an analysis of the accuracy of the methods and the study of the Maxwell’s system and the important problem of its spurious free approximations. After recalling the classical models, i.e. acoustics, linear elastodynamics and electromagnetism and their variational formulations, the authors present a wide variety of finite elements of different shapes useful for the numerical resolution of wave equations. Then, they focus on the construction of efficient continuous and discontinuous Galerkin methods and study their accuracy by plane wave techniques and a priori error estimates. A chapter is devoted to the Maxwell’s system and the important problem ...
Coupling Impedances of Small Discontinuities: Dependence on Beam Velocity
Kurennoy, S S
2006-01-01
The beam coupling impedances of small discontinuities of an accelerator vacuum chamber have been calculated [e.g., S.S. Kurennoy, R.L. Gluckstern, and G.V. Stupakov, Phys. Rev. E 52, 4354 (1995)] for ultrarelativistic beams using the Bethe diffraction theory. Here we extend the results to an arbitrary beam velocity. The vacuum chamber is assumed to have an arbitrary, but uniform along the beam path, cross section. The longitudinal and transverse coupling impedances are derived in terms of series over cross-section eigenfunctions, while the discontinuity shape enters via its polarizabilities. Simple explicit formulas for two important particular cases - circular and rectangular chamber cross sections - are presented. The impedance dependence on the beam velocity exhibits some unusual features: for example, the reactive impedance, which dominates in the ultrarelativistic limit, can vanish at a certain beam velocity, or its magnitude can exceed the ultrarelativistic value many times. In addition, we demonstrate ...
Constitutive model of discontinuous plastic flow at cryogenic temperatures
Skoczen, B; Bielski, J; Marcinek, D
2010-01-01
FCC metals and alloys are frequently used in cryogenic applications, nearly down to the temperature of absolute zero, because of their excellent physical and mechanical properties including ductility. Some of these materials, often characterized by the low stacking fault energy (LSFE), undergo at low temperatures three distinct phenomena: dynamic strain ageing (DSA), plastic strain induced transformation from the parent phase (gamma) to the secondary phase (alpha) and evolution of micro-damage. The constitutive model presented in the paper is focused on the discontinuous plastic flow (serrated yielding) and takes into account the relevant thermodynamic background. The discontinuous plastic flow reflecting the DSA effect is described by the mechanism of local catastrophic failure of Lomer-Cottrell (LC) locks under the stress fields related to the accumulating edge dislocations (below the transition temperature from the screw dislocations to the edge dislocations mode T-1). The failure of LC locks leads to mass...
Assessment of shock capturing schemes for discontinuous Galerkin method
于剑; 阎超; 赵瑞
2014-01-01
This paper carries out systematical investigations on the performance of several typical shock-capturing schemes for the discontinuous Galerkin (DG) method, including the total variation bounded (TVB) limiter and three artificial diffusivity schemes (the basis function-based (BF) scheme, the face residual-based (FR) scheme, and the element residual-based (ER) scheme). Shock-dominated flows (the Sod problem, the Shu-Osher problem, the double Mach reflection problem, and the transonic NACA0012 flow) are considered, addressing the issues of accuracy, non-oscillatory property, dependence on user-specified constants, resolution of discontinuities, and capability for steady solutions. Numerical results indicate that the TVB limiter is more eﬃcient and robust, while the artificial diffusivity schemes are able to preserve small-scale flow structures better. In high order cases, the artificial diffusivity schemes have demonstrated superior performance over the TVB limiter.
Radio Scintillation due to Discontinuities in the Interstellar Plasma Density
Lambert, H; Lambert, Hendrik; Rickett, Barney
1999-01-01
We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial density spectrum with a spectral exponent of 4 corresponding to a medium with abrupt changes in its density. An ``outer scale'' is included in the model representing the typical scale over which the density of the medium remains uniform. Such a spectrum could be used to model plasma shock fronts in supernova remnants or other plasma discontinuities. We investigate and develop equations for the decorrelation bandwidth of diffractive scintillations and the refractive scintillation index and compare our results with pulsar measurements. We consider both a medium concentrated in a thin layer and an extended irregular medium. We conclude that the discontinuity model gives satisfactory agreement for many diffractive measurements, in particular the VLBI meaurements of the structure function exponent between 5/3 and 2. However, it gives less satisfactory agreement for the refractive scintillation index than...
Continuous and Discontinuous Modelling of Fracture in Concrete Using FEM
Tejchman, Jacek
2013-01-01
The book analyzes a quasi-static fracture process in concrete and reinforced concrete by means of constitutive models formulated within continuum mechanics. A continuous and discontinuous modelling approach was used. Using a continuous approach, numerical analyses were performed using a finite element method and three different enhanced continuum models: isotropic elasto-plastic, isotropic damage and anisotropic smeared crack one. The models were equipped with a characteristic length of micro-structure by means of a non-local and a second-gradient theory. So they could properly describe the formation of localized zones with a certain thickness and spacing and a related deterministic size effect. Using a discontinuous FE approach, numerical results of cracks using a cohesive crack model and XFEM were presented which were also properly regularized. Finite element analyses were performed with concrete elements under monotonic uniaxial compression, uniaxial tension, bending and shear-extension. Concrete beams un...
The Gutenberg discontinuity: melt at the lithosphere-asthenosphere boundary.
Schmerr, Nicholas
2012-03-23
The lithosphere-asthenosphere boundary (LAB) beneath ocean basins separates the upper thermal boundary layer of rigid, conductively cooling plates from the underlying ductile, convecting mantle. The origin of a seismic discontinuity associated with this interface, known as the Gutenberg discontinuity (G), remains enigmatic. High-frequency SS precursors sampling below the Pacific plate intermittently detect the G as a sharp, negative velocity contrast at 40- to 75-kilometer depth. These observations lie near the depth of the LAB in regions associated with recent surface volcanism and mantle melt production and are consistent with an intermittent layer of asthenospheric partial melt residing at the lithospheric base. I propose that the G reflectivity is regionally enhanced by dynamical processes that produce melt, including hot mantle upwellings, small-scale convection, and fluid release during subduction.
GH administration and discontinuation in healthy elderly men
Lange, K H; Isaksson, F; Rasmussen, M H;
2001-01-01
GH administration results in increased lean body mass (LBM), decreased fat mass (FM) and increased energy expenditure (EE). GH therapy may therefore have potential benefits, especially in the elderly, who are known to have decreased function of the GH/IGF-I axis. Several studies have focused...... on effects of GH administration in the elderly in the last decade. However, very limited information is available regarding changes in body composition and EE upon GH discontinuation in the elderly. The present study therefore investigated the effects of 12 weeks of GH administration and subsequent...... discontinuation on body composition, resting oxygen uptake (VO2), resting heart rate (HR) and GH related serum markers in healthy elderly men....
Fourier analysis for discontinuous Galerkin and related methods
ZHANG MengPing; SHU Chi-Wang
2009-01-01
In this paper we review a series of recent work on using a Fourier analysis technique to study the sta-bility and error estimates for the discontinuous Galerkin method and other related schemes. The ad-vantage of this approach is that it can reveal instability of certain "bad"' schemes; it can verify stability for certain good schemes which are not easily amendable to standard finite element stability analysis techniques; it can provide quantitative error comparisons among different schemes; and it can be used to study superconvergence and time evolution of errors for the discontinuous Galerkin method. We will briefly describe this Fourier analysis technique, summarize its usage in stability and error estimates for various schemes, and indicate the advantages and disadvantages of this technique in comparison with other finite element techniques.
A Streaming Language Implementation of the Discontinuous Galerkin Method
Barth, Timothy; Knight, Timothy
2005-01-01
We present a Brook streaming language implementation of the 3-D discontinuous Galerkin method for compressible fluid flow on tetrahedral meshes. Efficient implementation of the discontinuous Galerkin method using the streaming model of computation introduces several algorithmic design challenges. Using a cycle-accurate simulator, performance characteristics have been obtained for the Stanford Merrimac stream processor. The current Merrimac design achieves 128 Gflops per chip and the desktop board is populated with 16 chips yielding a peak performance of 2 Teraflops. Total parts cost for the desktop board is less than $20K. Current cycle-accurate simulations for discretizations of the 3-D compressible flow equations yield approximately 40-50% of the peak performance of the Merrimac streaming processor chip. Ongoing work includes the assessment of the performance of the same algorithm on the 2 Teraflop desktop board with a target goal of achieving 1 Teraflop performance.
Computational aeroacoustics applications based on a discontinuous Galerkin method
Delorme, Philippe; Mazet, Pierre; Peyret, Christophe; Ventribout, Yoan
2005-09-01
CAA simulation requires the calculation of the propagation of acoustic waves with low numerical dissipation and dispersion error, and to take into account complex geometries. To give, at the same time, an answer to both challenges, a Discontinuous Galerkin Method is developed for Computational AeroAcoustics. Euler's linearized equations are solved with the Discontinuous Galerkin Method using flux splitting technics. Boundary conditions are established for rigid wall, non-reflective boundary and imposed values. A first validation, for induct propagation is realized. Then, applications illustrate: the Chu and Kovasznay's decomposition of perturbation inside uniform flow in term of independent acoustic and rotational modes, Kelvin-Helmholtz instability and acoustic diffraction by an air wing. To cite this article: Ph. Delorme et al., C. R. Mecanique 333 (2005).
High-scale discontinuity detection applied to Landsat images
Jones, Katharine J.
1999-03-01
Landsat image data were produced from a multispectral scanner on Landsat satellites. Vegetation indices are based on the distinctive rise in the reflectance of green vegetation: a wavelength increase from visible red to reflective infrared caused by the selective absorption of red light by chlorophyll for photosynthesis. The spectral bandwidth of different Landsat crops are uniquely different and provide a basis for High Scale Discontinuity Detection. High Scale Discontinuity Detection applied to Landsat cross sections (1D signals) detects boundaries between urban areas and agricultural areas and different crops. These boundaries will be used to reconstruct an image based on boundaries. This approach might be usefully applied to IR images, laser remote sensing or any image where vegetation changes abruptly because of altitude or moisture.
Early postoperative acetabular discontinuity after total hip arthroplasty.
Desai, Gaurav; Ries, Michael D
2011-12-01
Periprosthetic acetabular fracture is a rare complication after total hip arthroplasty (THA). However, we have treated 2 patients with acute postoperative acetabular discontinuity that occurred 2 and 3 weeks after primary THA. Both fractures were in elderly osteoporotic female patients with minimal trauma and may have developed from unrecognized intraoperative fractures. Pelvic stability was restored with acetabular revision using medial morselized bone grafting and a cemented reconstruction cage. This report demonstrates that early postoperative periprosthetic acetabular discontinuity after THA is a risk in elderly patients with severe osteoporosis and that salvage of acetabular fixation can be achieved with cemented cage reconstruction and medial morselized bone grafting. Copyright © 2011 Elsevier Inc. All rights reserved.
Forced-air warming discontinued: periprosthetic joint infection rates drop
Scott D. Augustine
2017-06-01
Full Text Available Several studies have shown that the waste heat from forced-air warming (FAW escapes near the floor and warms the contaminated air resident near the floor. The waste heat then forms into convection currents that rise up and contaminate the sterile field above the surgical table. It has been shown that a single airborne bacterium can cause a periprosthetic joint infection (PJI following joint replacement surgery. We retrospectively compared PJI rates during a period of FAW to a period of air-free conductive fabric electric warming (CFW at three hospitals. Surgical and antibiotic protocols were held constant. The pooled multicenter data showed a decreased PJI rate of 78% following the discontinuation of FAW and a switch to air-free CFW (n=2034; P=0.002. The 78% reduction in joint implant infections observed when FAW was discontinued suggests that there is a link between the waste FAW heat and PJIs.
Discontinuously reinforced intermetallic matrix composites via XD synthesis. [exothermal dispersion
Kumar, K. S.; Whittenberger, J. D.
1992-01-01
A review is given of recent results obtained for discontinuously reinforced intermetallic matrix composites produced using the XD process. Intermetallic matrices investigated include NiAl, multiphase NiAl + Ni2AlTi, CoAl, near-gamma titanium aluminides, and Ll2 trialuminides containing minor amounts of second phase. Such mechanical properties as low and high temperature strength, compressive and tensile creep, elastic modulus, ambient ductility, and fracture toughness are discussed as functions of reinforcement size, shape, and volume fraction. Microstructures before and after deformation are examined and correlated with measured properties. An observation of interest in many of the systems examined is 'dispersion weakening' at high temperatures and high strain rates. This behavior is not specific to the XD process; rather similar observations have been reported in other discontinuous composites. Proposed mechanisms for this behavior are presented.
Existence Theorem for Integral and Functional Integral Equations with Discontinuous Kernels
2012-01-01
Existence of extremal solutions of nonlinear discontinuous integral equations of Volterra type is proved. This result is extended herein to functional Volterra integral equations (FVIEs) and to a system of discontinuous VIEs as well.
无
2002-01-01
The existence of discontinuities, the topographies of the 410 km and 660 km discontinuities, and the penetrations of subducting slabs near the 660 km discontinuities beneath the Sea of Okhotsk were studied using Nth root slant stack and digital records from networks in Germany and the western United States. Results show the obvious evidence for reflected and refractive phases associated with the 410 km and 660 km discontinuities. There may be discontinuities at other depths such as 150 km, 220 km and 520 km. The 410 km discontinuity is elevated and the 660 km discontinuity is depressed respectively, consistent with the expected thermal signature of the phase transitions. The subducting slab has penetrated into the lower mantle in the northern part of the Sea of Okhotsk, while it is stagnant on the 660 km discontinuity in the southern part.
Zhao, MingHao; Pan, YiBo; Fan, CuiYing; Xu, GuangTao
2017-08-01
The extended displacement discontinuities method has previously been used for crack analysis of elastic materials, piezoelectric media, magneto-electro-elastic media and piezoelectric semiconductors. Here, this method is extended to study cracks in two-dimensional n-type thermal piezoelectric semiconductors. The extended displacement discontinuities include the conventional displacement discontinuity, electric potential discontinuity, carrier density discontinuity, as well as temperature discontinuity across crack faces; correspondingly, the extended stresses represent conventional stress, electric displacement, electric current, and heat flux. Employing a Fourier transform, the fundamental solutions for a line crack under uniformly distributed extended displacement discontinuities on the crack faces are derived under mechanical, electrical, and heat loading. Based on the obtained fundamental solutions, an extended displacement discontinuity boundary element method is developed. The stress and heat flux intensity factors at the crack tip are calculated under different combined loadings.
Faranoff-Riley type I jet deceleration at density discontinuities
Meliani, Z.; Keppens, R.; Giacomazzo, B.
2008-01-01
Aims. We propose a model that could explain the sudden jet deceleration in active galactic nuclei, thereby invoking density discontinuities. Motivated particularly by recent indications from HYbrid MOrphology Radio Sources (HYMORS) that Fanaroff-Riley classification is induced in some cases by variations in the density of the external medium. We explore how one-sided jet deceleration and a transition to FR I type can occur in HYMORS, which start as FR II (and remain so on the other side). Met...
Discontinuous Galerkin methods for Hamiltonian ODEs and PDEs
Tang, Wensheng; Sun, Yajuan; Cai, Wenjun
2017-02-01
In this article, we present a unified framework of discontinuous Galerkin (DG) discretizations for Hamiltonian ODEs and PDEs. We show that with appropriate numerical fluxes the numerical algorithms deduced from DG discretizations can be combined with the symplectic methods in time to derive the multi-symplectic PRK schemes. The resulting numerical discretizations are applied to the linear and nonlinear Schrödinger equations. Some conservative properties of the numerical schemes are investigated and confirmed in the numerical experiments.
Imaging of discontinuities in nonlinear 3-D seismic inversion
Carrion, P.M.; Cerveny, V. (PPPG/UFBA, Salvador (Brazil))
1990-09-01
The authors present a nonlinear approach for reconstruction of discontinuities in geological environment (earth's crust, say). The advantage of the proposed method is that it is not limited to a Born approximation (small angles of propagation and weak scatterers). One can expect significantly better images since larger apertures including wide angle reflection arrivals can be incorporated into the imaging operator. In this paper, they treat only compressional body waves: shear and surface waves are considered as noise.
Topological equivalence for discontinuous random dynamical systems and applications
Qiao, Huijie; Duan, Jinqiao
2012-01-01
After defining non-Gaussian L\\'evy processes for two-sided time, stochastic differential equations with such L\\'evy processes are considered. Solution paths for these stochastic differential equations have countable jump discontinuities in time. Topological equivalence (or conjugacy) for such an It\\^o stochastic differential equation and its transformed random differential equation is established. Consequently, a stochastic Hartman-Grobman theorem is proved for the linearization of the It\\^o ...
Anomalous discontinuity at the percolation critical point of active gels.
Sheinman, M; Sharma, A; Alvarado, J; Koenderink, G H; MacKintosh, F C
2015-03-06
We develop a percolation model motivated by recent experimental studies of gels with active network remodeling by molecular motors. This remodeling was found to lead to a critical state reminiscent of random percolation (RP), but with a cluster distribution inconsistent with RP. Our model not only can account for these experiments, but also exhibits an unusual type of mixed phase transition: We find that the transition is characterized by signatures of criticality, but with a discontinuity in the order parameter.
HYBRID METHOD FOR ANALYSE DISCONTINUITIES IN SHIELDED MICROSTRIP
MOHAMMED EL AMINE EL GOUZI
2010-07-01
Full Text Available A rigorous full-wave analysis is employed to analyze discontinuity in shielded Microstrip (open end, uniform bend. An accurate and efficient method of moments solution combined with the source method(SM formulation is proposed in order to achieve a full-wave characterization of the analyzed structures. A wavelet matrix transform(WMT, operated by wavelet-like transform (WLT allows a significant reduction of the central processing unit time and the memory storage.
Discontinuation of hypnotics during cognitive behavioural therapy for insomnia
Brunovsky Martin
2008-09-01
Full Text Available Abstract Background In practical sleep medicine, therapists face the question of whether or not to discontinue the ongoing use of hypnotics in patients, as well as the possible effects of discontinuation. The aim of this study was to evaluate the effects of discontinuing third-generation hypnotics on the results of cognitive-behavioural therapy (CBT for primary insomnia in patients after long-term abuse. Methods Twenty-eight outpatients were treated by CBT for 8 weeks. The treatment outcome was estimated by means of differences among subjective clinical scales and polysomnography variables assessed before and after the treatment period. The therapeutic effect in a subgroup of 15 patients who had previously received hypnotics and were successively withdrawn during weeks 2–6 was compared to the effect achieved in patients who had not used hypnotics before CBT. Results There were no significant differences in baseline subjective and objective sleep characteristics between the hypnotic abusers and non-abusers. According to clinical scales and most polysomnographic measures, CBT was highly effective in both groups of subjects; it produced the greatest changes in total sleep time, REM sleep and sleep efficiency. Unexpectedly, discontinuation of hypnotics, as a factor in the analysis, was followed by an additional improvement of sleep efficiency and wake after sleep onset parameters. Conclusion Our study confirmed the efficacy of CBT in both hypnotic-abusing and non-abusing patients with chronic insomnia. The results of this study suggest that tapered withdrawal of third-generation hypnotics during CBT therapy for chronic insomnia could be associated with improvement rather than worsening of sleep continuity.
Continued versus discontinued oxytocin stimulation, protocol of an rct
Boie, Sidsel; Glavind, Julie; Uldbjerg, Niels
outcome Caesarean delivery Secondary outcomes Postpartum haemorrhage Duration of labour Instrumental delivery Neonatal morbidity Birth experience Breastfeeding Results: Results are expected in 2018. Conclusions: This is the first double-blind RCT on discontinuation or continuation of oxytocin stimulation......, when the active phase of labour is established. The trial will have a major impact on both national and international clinical practice concerning induction of labour with Syntocinon®....
Stability Analysis of Discontinuous Galerkin Approximations to the Elastodynamics Problem
Antonietti, Paola F.
2015-11-21
We consider semi-discrete discontinuous Galerkin approximations of both displacement and displacement-stress formulations of the elastodynamics problem. We prove the stability analysis in the natural energy norm and derive optimal a-priori error estimates. For the displacement-stress formulation, schemes preserving the total energy of the system are introduced and discussed. We verify our theoretical estimates on two and three dimensions test problems.
On the Existence of Feller Semigroups with Discontinuous Coefficients Ⅱ
Kazuaki TAIRA
2009-01-01
This paper is devoted to the functional analytic approach to the problem of existence of Markov processes with Dirichlet boundary condition, oblique derivative boundary condition and first-order Wentzell boundary condition for second-order, uniformly elliptic differential operators with discontinuous coefficients. More precisely, we construct Feller semigroups associated with absorption,reflection, drift and sticking phenomena at the boundary. The approach here is distinguished by the Zygmund theory of singular integral operators with non-smooth kernels.
Oscillations with one degree of freedom and discontinuous energy
Miguel V. S. Frasson
2015-10-01
Full Text Available In 1995 for a linear oscillator, Myshkis imposed a constant impulse to the velocity, each moment the energy reaches a certain level. The main feature of the resulting system is that it defines a nonlinear discontinuous semigroup. In this note we study the orbital stability of a one-parameter family of periodic solutions and state the existence of a period-doubling bifurcation of such solutions.
Multiband Software Defined Radar for Soil Discontinuities Detection
S. Costanzo
2013-01-01
Full Text Available A multiband Software Defined Radar based on orthogonal frequency-division multiplexing technique is proposed in this work for an accurate soil discontinuities detection, taking into account also the dispersive behavior of media. A multilayer soil structure is assumed as a validation test to demonstrate the effectiveness of the proposed approach, by accurately retrieving the unknown thicknesses and permittivities of the soil layers.
Why do couples discontinue unlimited free IVF treatments?
Lande, Yechezkel; Seidman, Daniel S; Maman, Ettie; Baum, Micha; Hourvitz, Ariel
2015-03-01
Worldwide, IVF is often discontinued before a live birth is achieved due to high costs. Even when partial financial coverage is provided, often medical providers advise treatment discontinuation. In Israel, unlimited IVF is offered free of charge for a couples' first two children. Our objective was to assess the reasons couples discontinue IVF treatments before achieving two children in a completely unlimited cost-free environment. This cohort study included all primary infertile women, reason they ceased treatments. Of the 134 couples included, only 46 ceased IVF treatments without achieving two children, after performing an average of 6.2 IVF cycles to achieve their first birth. The reasons given were: lost hope of success (13), psychological burden (18), divorce (6), medical staff recommendation (5), bureaucratic difficulties (3) and general medical condition (1). The main reasons for "drop out" in our cost-free environment were as follows: psychological burden and lost hope of success. Due to high availability of treatments, medical staff recommendation was a less significant factor in our study.
Priapism Followed by Discontinuation of Methadone: A rare Case Report
Seyed-Ali Mostafavi
2015-10-01
Full Text Available Objective: Priapism is defined by persistent, painful penile erection which occurs without sexual stimulation. Methadone is used as an analgesic and is also used in detoxification and maintenance protocol for opioid dependence treatment. Here we will report a case of a male with priapism after rapid discontinuation doses of methadone.Case presentation: The case was a young married male who referred to a psychiatry clinic due to long-time spontaneous erections. The patient had no history of mental disorders, trauma or sickle cell anemia. He used to smoke opium for five years and used methadone for four years at a dose of 17 cc daily, which he abruptly discontinued. Then he often experienced spontaneous and painful erections without physical or mental stimulation that caused him shame and embarrassment .Conclusion: In this case, chronology indicates that rapid discontinuation of methadone was possibly responsible for the occurrence of priapism. This may have happened due to a compensatory reaction to methadone side effect of erectile dysfunction, followed by its rapid withdrawal.
Effects of discontinuities of the derivatives of the inflaton potential
Gallego Cadavid, Alexander [Universidad de Antioquia, Instituto de Fisica, Medellin (Colombia); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Enea Romano, Antonio [Universidad de Antioquia, Instituto de Fisica, Medellin (Colombia); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); University of Crete, Department of Physics, Heraklion (Greece)
2015-12-15
We study the effects of a class of features of the inflaton potential, corresponding to discontinuities in its derivatives. We perform fully numerical calculations and derive analytical approximations for the curvature perturbations spectrum and the bispectrum which are in good agreement with the numerical results. The spectrum of primordial perturbations has oscillations around the scale k{sub 0} which leaves the horizon at the time τ{sub 0} when the feature occurs, with the amplitude and phase of the oscillations determined by the size and the order of the discontinuity. The large scale bispectrum in the squeezed and equilateral limits have a very similar form and are linearly suppressed. Both in the squeezed and the equilateral small scale limit the bispectrum has an oscillatory behavior whose phase depends on the parameters determining the discontinuity, and whose amplitude is inversely proportional to the scale. Given the generality of this class of features they could be used to model or classify phenomenologically different types of non-Gaussian features encountered in observational data such as the cosmic microwave background radiation or large scale structure. (orig.)
Effects of discontinuities of the derivatives of the inflaton potential
Cadavid, Alexander Gallego [Instituto de Fisica, Universidad de Antioquia, A.A.1226, Medellin (Colombia); Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto (Japan); Romano, Antonio Enea, E-mail: aer@physics.uoc.gr [Instituto de Fisica, Universidad de Antioquia, A.A.1226, Medellin (Colombia); Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto (Japan); Department of Physics, University of Crete, 71003, Heraklion (Greece)
2015-12-12
We study the effects of a class of features of the inflaton potential, corresponding to discontinuities in its derivatives. We perform fully numerical calculations and derive analytical approximations for the curvature perturbations spectrum and the bispectrum which are in good agreement with the numerical results. The spectrum of primordial perturbations has oscillations around the scale k{sub 0} which leaves the horizon at the time τ{sub 0} when the feature occurs, with the amplitude and phase of the oscillations determined by the size and the order of the discontinuity. The large scale bispectrum in the squeezed and equilateral limits have a very similar form and are linearly suppressed. Both in the squeezed and the equilateral small scale limit the bispectrum has an oscillatory behavior whose phase depends on the parameters determining the discontinuity, and whose amplitude is inversely proportional to the scale. Given the generality of this class of features they could be used to model or classify phenomenologically different types of non-Gaussian features encountered in observational data such as the cosmic microwave background radiation or large scale structure.
Discontinued students in nursing education - Who and why?
Kukkonen, Pia; Suhonen, Riitta; Salminen, Leena
2016-03-01
There has been increasing interest in student nurse attrition due to the high level of attrition rates in many countries. Studies about nursing education and attrition have been conducted internationally, but only a few have explored attrition from the perspective of the students' own experiences. The purpose of this study was to describe who is a discontinued student in nursing education and the students' own experiences of reasons for leaving a nursing school. A descriptive design and qualitative approach was used. 25 nursing students were interviewed at two different universities of applied sciences in Finland. Four different types of discontinued nursing students were identified: those who moved to another school, those who faced a life crisis, those who made the wrong career choice and those who lived 'busy years'. The results show that the nursing student population is diverse, which has an effect on the students' career intentions, their learning and their ability to cope with studies. In nursing education, it is important to identify students who are at risk of discontinue their studies and develop individual support systems to help nursing students complete their studies and enter into the workforce.
Oxytocin discontinuation after the active phase of labor is established.
Vlachos, Dimitrios-Efthymios G; Pergialiotis, Vasilios; Papantoniou, Nikolaos; Trompoukis, Stamoulis; Vlachos, Georgios D
2015-08-01
Despite the widespread usage of oxytocin, there is still no consensus on its mode of administration. The scope of the present meta-analysis was to assess the effect of oxytocin discontinuation after the active phase of labor is established on maternal fetal and neonatal outcomes. We searched Medline, Scopus, Popline, ClinicalTrials.gov and Google Scholar databases. Eight studies were finally retrieved, which involved 1232 parturient. We observed significantly decreased rates of cesarean sections among parturient that discontinued oxytocin (OR 0.51, 95% CI 0.35, 0.74) as well as decreased rates of uterine hyperstimulation (OR 0.33, 95% CI 0.19, 0.58). Similarly, cases of non-reassuring fetal heart rates were fewer among women that did not receive oxytocin after the establishment of the active phase of labor (OR 0.63, 95% CI 0.41, 0.97). Keeping in mind the aforementioned maternal and neonatal adverse effects that seem to result from infusion of oxytocin until delivery, future practice should aim towards its discontinuation after the establishment of the active phase of labor, as it does not seem to influence the total duration of labor. Future studies should aim towards specific populations of parturient in order to clarify whether different approaches are needed.
Darwin's mistake: explaining the discontinuity between human and nonhuman minds.
Penn, Derek C; Holyoak, Keith J; Povinelli, Daniel J
2008-04-01
Over the last quarter century, the dominant tendency in comparative cognitive psychology has been to emphasize the similarities between human and nonhuman minds and to downplay the differences as "one of degree and not of kind" (Darwin 1871). In the present target article, we argue that Darwin was mistaken: the profound biological continuity between human and nonhuman animals masks an equally profound discontinuity between human and nonhuman minds. To wit, there is a significant discontinuity in the degree to which human and nonhuman animals are able to approximate the higher-order, systematic, relational capabilities of a physical symbol system (PSS) (Newell 1980). We show that this symbolic-relational discontinuity pervades nearly every domain of cognition and runs much deeper than even the spectacular scaffolding provided by language or culture alone can explain. We propose a representational-level specification as to where human and nonhuman animals' abilities to approximate a PSS are similar and where they differ. We conclude by suggesting that recent symbolic-connectionist models of cognition shed new light on the mechanisms that underlie the gap between human and nonhuman minds.
47 CFR 63.63 - Emergency discontinuance, reduction, or impairment of service.
2010-10-01
... service. (a) Application for authority for emergency discontinuance, reduction, or impairment of service... comparable service as expeditiously as possible. (b) Authority for the emergency discontinuance, reduction... 47 Telecommunication 3 2010-10-01 2010-10-01 false Emergency discontinuance, reduction,...
Physico-chemical constraints on cratonic lithosphere discontinuities
Aulbach, Sonja; Rondenay, Stéphane; Huismans, Ritske
2014-05-01
The origins of the mid-lithospheric discontinuity (MLD) and lithosphere-asthenosphere boundary (LAB) have received much attention over the recent years. Peculiarities of cratonic lithosphere construction - compositional and rheological stratification due to thickening in collisional settings or by plume subcretion, multiple metasomatic overprints due to longevity - offer a variety of possibilities for the generation of discontinuities. Interconnected small degrees of conductive partial melt (carbonate-rich melts, such as carbonatites and kimberlites, or highly alkaline melts) at the cratonic LAB, which produce seismic discontinuities, may be generated in the presence of volatiles. These depress the peridotite solidus sufficiently to intersect the mantle adiabat at depths near the cratonic LAB at ~160-220 km, i.e. above the depth of metal saturation where carbonatite becomes unstable. The absence of agreement between the different seismic and magnetotelluric estimates for the depth of the LAB beneath Kaapvaal may be due to impingement of a plume, leading to a pervasively, but heterogeneously metasomatised ('asthenospherised') hot and deep root. Such a root and hot sublithosphere may yield conflicting seismic-thermal-geochemical depths for the LAB. The question arises whether the chemical boundary layer should be defined as above or below the asthenospherised part of the SCLM, which has preserved isotopic, compositional (non-primitive olivine forsterite content) and physical evidence (e.g. from teleseismic tomography and receiver functions) for a cratonic heritage and which therefore is still distinguishable from the asthenospheric mantle. If cratonic lithosphere overlies anomalously hot mantle for extended periods of time, the LAB may be significantly thinned, aided by penetration of relatively high-degree Fe-rich partial melts, as has occurred beneath the Tanzanian craton. Xenoliths from the deep Slave craton show little evidence for 'asthenospherisation'. Its root
Automatic extraction of discontinuity orientation from rock mass surface 3D point cloud
Chen, Jianqin; Zhu, Hehua; Li, Xiaojun
2016-10-01
This paper presents a new method for extracting discontinuity orientation automatically from rock mass surface 3D point cloud. The proposed method consists of four steps: (1) automatic grouping of discontinuity sets using an improved K-means clustering method, (2) discontinuity segmentation and optimization, (3) discontinuity plane fitting using Random Sample Consensus (RANSAC) method, and (4) coordinate transformation of discontinuity plane. The method is first validated by the point cloud of a small piece of a rock slope acquired by photogrammetry. The extracted discontinuity orientations are compared with measured ones in the field. Then it is applied to a publicly available LiDAR data of a road cut rock slope at Rockbench repository. The extracted discontinuity orientations are compared with the method proposed by Riquelme et al. (2014). The results show that the presented method is reliable and of high accuracy, and can meet the engineering needs.
Persistent sexual dysfunction after discontinuation of selective serotonin reuptake inhibitors.
Csoka, Antonei B; Csoka, A; Bahrick, Audrey; Mehtonen, Olli-Pekka
2008-01-01
Sexual dysfunctions such as low libido, anorgasmia, genital anesthesia, and erectile dysfunction are very common in patients taking selective serotonin reuptake inhibitors (SSRIs). It has been assumed that these side effects always resolve after discontinuing treatment, but recently, four cases were presented in which sexual function did not return to baseline. Here, we describe three more cases. Case #1: A 29-year-old with apparently permanent erectile dysfunction after taking fluoxetine 20 mg once daily for a 4-month period in 1996. Case #2: A 44-year-old male with persistent loss of libido, genital anesthesia, ejaculatory anhedonia, and erectile dysfunction after taking 20-mg once daily citalopram for 18 months. Case #3: A 28-year-old male with persistent loss of libido, genital anesthesia, and ejaculatory anhedonia since taking several different SSRIs over a 2-year period from 2003-2005. No psychological issues related to sexuality were found in any of the three cases, and all common causes of sexual dysfunction such as decreased testosterone, increased prolactin or diabetes were ruled out. Erectile capacity is temporarily restored for Case #1 with injectable alprostadil, and for Case #2 with oral sildenafil, but their other symptoms remain. Case #3 has had some reversal of symptoms with extended-release methylphenidate, although it is not yet known if these prosexual effects will persist when the drug is discontinued. SSRIs can cause long-term effects on all aspects of the sexual response cycle that may persist after they are discontinued. Mechanistic hypotheses including persistent endocrine and epigenetic gene expression alterations were briefly discussed.
Temperature Discontinuity Caused by Relocation of Meteorological Stations in Taiwan
Chih-wen Hung
2009-01-01
Full Text Available With global warming upon us, it has be come increasingly important to identify the extent of this warming trend and in doing so be able to rank mean temperature changes in particular seasons and years. This requires a need for homogeneous climate data, which do not reflect individual anomalies in instruments, station locations or local environments (urbanization. Ac curate homogeneous long-term meteorological data helps show how temperature variations have truly occurred in the climate. Many possible factors contribute to artificial abrupt changes or sharp discontinuities in long time series data, such as the impact of station relocation, changes in observational schedules and instrumentation. Homogeneity adjustments of in situ climate data are very important processes for preparing observational data to be used in further analysis and research. Users require a well-documented history of stations to make appropriate homogeneity adjustments because precise historical back ground records of stations can provide researchers with knowledge of when artificial discontinuity has occurred and its causes. With out such de tailed historical data for each meteorological station, abrupt changes are difficult to interpret. Unfortunately, no homogeneity adjustments for temperature records have been con ducted previously in Tai wan, and present available sources of the history of Taiwan's meteorological stations exhibit in consistencies. In this study, information pertaining to station history, especially relocation records, is pro vided. This information is essential for anal y sis of continuous time series data for temperature and climate warming studies. Temperature data from several stations is given in this study to show how artificial discontinuity occurs due to station relocation. Al though there is no homogeneous adjusted climate data provided in this preliminary work, the summarizing of information regarding station relocations should be of assistance
Efficient Large Eddy Simulation for the Discontinuous Galerkin Method
Creech, Angus; Maddison, James; Percival, James; Bruce, Tom
2016-01-01
In this paper we present a new technique for efficiently implementing Large Eddy Simulation with the Discontin- uous Galerkin method on unstructured meshes. In particular, we will focus upon the approach to overcome the computational complexity that the additional degrees of freedom in Discontinuous Galerkin methods entail. The turbulence algorithms have been implemented within Fluidity, an open-source computational fluid dynamics solver. The model is tested with the well known backward-facing step problem, and is shown to concur with published results.
BIOVENTING - Groundwater Aeration by Discontinuous Oxygen Gas Pulse Injections
Schirmer, M.
2003-12-01
Groundwater aeration by discontinuous oxygen gas pulse injections appears to be a promising concept for enhanced natural attenuation of dissolved contaminants that are susceptible for oxygenase enzyme attacks. Oxygen amendments facilitate indigenous microbiota to catabolize groundwater pollutants, such as aromatics, that are considered to be recalcitrant in absence of dissolved oxygen. As a rule, natural attenuation of many pollutants under aerobic conditions is considerably faster than under anaerobic conditions. Thus, enhancing the dissolved oxygen level appears to be worthwhile. In situ aeration of groundwater has been accomplished by air sparging, H2O2-supply, or by utilization of oxygen release compounds. However, continuous aeration of previously anaerobic groundwater is not desirable for several reasons: (a) economic efforts too high, (b) pollutant dislocation towards surface (desired only in air sparging), (c) risk of aquifer clogging (gas clogging, oxidation of ferrous iron, formation of bioslimes). In contrast, discontinuous oxygen gas sparging provides only for periodical groundwater aeration which is followed by microaerobic and suboxic conditions. Microaerobic conditions can prevail spatially (e.g., at plume fringes or within biofilms) or temporarily (e.g., at discontinuous bioventing). They still allow adapted bacteria to transform environmental pollutants to less toxic compounds, e.g., aromatic ring cleavage after dioxygenasis attack. Ring cleavage products, on the other hand, may be degraded more easily by anaerobic consortia than the initial aromatic compounds, making oxygen depletion periods highly intriguing in regard to an initiation of natural attenuation processes at plume fringes. In our work we outline the effect of oxygen depletion conditions on biodegradation of monchlorobenzene (MCB) as they occur subsequently to temporary aeration periods. For microaerobic conditions, relative to the oxygen supply, a stoichiometric transformation of MCB
On the Existence of Feller Semigroups with Discontinuous Coefficients
Kazuaki TAIRA
2006-01-01
This paper is devoted to the functional analytic approach to the problem of the existence of Markov processes in probability theory. More precisely, we construct Feller semigroups with Dirichlet conditions for second-order, uniformly elliptic integro-differential operators with discontinuous coefficients. In other words, we prove that there exists a Feller semigroup corresponding to such a diffusion phenomenon that a Markovian particle moves both by jumps and continuously in the state space until it dies at the time when it reaches the boundary.
GPU-accelerated discontinuous Galerkin methods on hybrid meshes
Chan, Jesse; Wang, Zheng; Modave, Axel; Remacle, Jean-Francois; Warburton, T.
2016-08-01
We present a time-explicit discontinuous Galerkin (DG) solver for the time-domain acoustic wave equation on hybrid meshes containing vertex-mapped hexahedral, wedge, pyramidal and tetrahedral elements. Discretely energy-stable formulations are presented for both Gauss-Legendre and Gauss-Legendre-Lobatto (Spectral Element) nodal bases for the hexahedron. Stable timestep restrictions for hybrid meshes are derived by bounding the spectral radius of the DG operator using order-dependent constants in trace and Markov inequalities. Computational efficiency is achieved under a combination of element-specific kernels (including new quadrature-free operators for the pyramid), multi-rate timestepping, and acceleration using Graphics Processing Units.
First-line antiretroviral drug discontinuations in children
Fortuin-de Smidt, Melony; de Waal, Reneé; Cohen, Karen; Technau, Karl-Günter; Stinson, Kathryn; Maartens, Gary; Boulle, Andrew; Igumbor, Ehimario U.; Davies, Mary-Ann
2017-01-01
Introduction There are a limited number of paediatric antiretroviral drug options. Characterising the long term safety and durability of different antiretrovirals in children is important to optimise management of HIV infected children and to determine the estimated need for alternative drugs in paediatric regimens. We describe first-line antiretroviral therapy (ART) durability and reasons for discontinuations in children at two South African ART programmes, where lopinavir/ritonavir has been recommended for children <3 years old since 2004, and abacavir replaced stavudine as the preferred nucleoside reverse transcriptase inhibitor in 2010. Methods We included children (<16 years at ART initiation) who initiated ≥3 antiretrovirals between 2004–2014 with ≥1 follow-up visit on ART. We estimated the incidence of first antiretroviral discontinuation using Kaplan-Meier analysis. We determined the reasons for antiretroviral discontinuations using competing risks analysis. We used Cox regression to identify factors associated with treatment-limiting toxicity. Results We included 3579 children with median follow-up duration of 41 months (IQR 14–72). At ART initiation, median age was 44 months (IQR 13–89) and median CD4 percent was 15% (IQR 9–21%). At three and five years on ART, 72% and 26% of children respectively remained on their initial regimen. By five years on ART, the most common reasons for discontinuations were toxicity (32%), treatment failure (18%), treatment simplification (5%), drug interactions (3%), and other or unspecified reasons (18%). The incidences of treatment limiting toxicity were 50.6 (95% CI 46.2–55.4), 1.6 (0.5–4.8), 2.0 (1.2–3.3), and 1.3 (0.6–2.8) per 1000 patient years for stavudine, abacavir, efavirenz and lopinavir/ritonavir respectively. Conclusions While stavudine was associated with a high risk of treatment-limiting toxicity, abacavir, lopinavir/ritonavir and efavirenz were well-tolerated. This supports the World Health
Weak discontinuities in electrically conducting and radiating gases
Rai A.
2002-01-01
Full Text Available The singular surface theory has been used to determine the law of propagation of weak discontinuities and the problem of growth and decay of waves. The effect of radioactive heat transfer has been treated using a differential approximation which is valid over entire optical depth range. The effects of wave geometry and magnetic field with finite electrical conductivity on the global behavior of the wave amplitude have also been studied. The two cases of diverging and converging waves have been discussed separately.
[Continuities and discontinuities of psychopathology from childhood to adulthood].
Karantanos, G
2012-06-01
Important data about possible continuities and discontinuities of psychopathology from childhood to adulthood have been provided by findings from well scheduled prospective longitudinal studies of community-based samples. Findings from clinical populations have contributed as well. This presentation relies on data from selected studies of reference. An effort is made to combine results demonstrating the extent of continuity at a more general level with those indicating continuities or discontinuities concerning disorders commonly presented in clinical practice. These disorders are those included in the internalizing (anxiety and mood disorders) and externalizing (ADHD, oppositional, conduct disorder-antisocial personality disorder) domains of psychopathology. Discontinuities do exist, however findings also suggest considerable longitudinal links between childhood-adolescence and adulthood. Reports from the Dunedin longitudinal study showed that half of those with psychiatric diagnoses at the age of 26 had met criteria for psychiatric disorder by the age of 15, and that figure approached 75% by the age of 18. Homotypic continuity is the most prominent. There are also heterotypic continuities, while homotypic and heterotypic continuities may co-occur. Among common disorders, findings suggest continuity tendencies even for anxiety disorders and for subclinical cases with obsessive and compulsive symptoms as well. Comorbidity between different anxiety disorders (strict homotypic continuity) as well as between them and depression (broad homotypic continuity) is very common. In the externalizing domain, longitudinal links between conduct disorder and antisocial personality disorder, including adverse consequences in psychosocial functioning, have been repeatedly found. Childhood onset subtype of conduct disorder is more prone to this adverse outcome, however all cases with conduct disorder need early recognition and intervention. During the course of conduct disorder
A Level Set Discontinuous Galerkin Method for Free Surface Flows
Grooss, Jesper; Hesthaven, Jan
2006-01-01
We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by embedding and represented by a levelset. We discuss the discretization of the flow equations and the level set equation...... as well a various ways of advancing the equations in time using velocity projection techniques. The efficacy of the method for the representation of the levelset and its reinitialization is discussed and several numerical tests confirm the robustness and versatility of the proposed scheme....
Pupil phase discontinuity measurement: comparison of different wavefront sensing concepts
El Hadi, K.; Sauvage, J.-F.; Dohlen, K.; Fusco, T.; Neichel, B.; Marchis, F.; N'Diaye, M.
2016-07-01
The Laboratoire d'Astrophysique de Marseille is involved in the preparation of the E-ELT instrumentation framework: In particular, an ESO-EELT M1 mirror segment (1.5 m) has been demonstrated and different wavefront sensing (WFS) concepts among which Pyramid, Zernike phase mask sensor (ZELDA), Phase diversity or still NL Curvature) are also investigated. Segmented mirrors are widely used today in diverse domains: fiber coupling, laser beam shaping, microscopy or retina imaging. If, these mirrors offer a solution to realize important monolithic sizes for giant telescopes in astronomy, they also raise the problem of segments cophasing and measurement of phase discontinuities. In this work, we aim to investigate a suitable WFS approach for pupil phase discontinuity measurement. Coupling a segmented PTT mirror (Iris AO) with four different WFS (Shack-Hartmann, Quadriwave Lateral Shearing Interferometer, Pyramid and Zernike Phase Mask), we study their sensitivity to segmented pupil: in particular, segment phasing, stability, saturation, flat, or still the addressing mode are then performed and compared.
Discontinuous finite element method for vector radiative transfer
Wang, Cun-Hai; Yi, Hong-Liang; Tan, He-Ping
2017-03-01
The discontinuous finite element method (DFEM) is applied to solve the vector radiative transfer in participating media. The derivation in a discrete form of the vector radiation governing equations is presented, in which the angular space is discretized by the discrete-ordinates approach with a local refined modification, and the spatial domain is discretized into finite non-overlapped discontinuous elements. The elements in the whole solution domain are connected by modelling the boundary numerical flux between adjacent elements, which makes the DFEM numerically stable for solving radiative transfer equations. Several various problems of vector radiative transfer are tested to verify the performance of the developed DFEM, including vector radiative transfer in a one-dimensional parallel slab containing a Mie/Rayleigh/strong forward scattering medium and a two-dimensional square medium. The fact that DFEM results agree very well with the benchmark solutions in published references shows that the developed DFEM in this paper is accurate and effective for solving vector radiative transfer problems.
Optical strain for monitoring of concrete failure mechanism with discontinuity.
Deb, Debasis; Bhattacharjee, Sudipta
2015-12-10
Finite-element-based digital image correlation (FEM-DIC) is one of the most widely used noncontact techniques in the field of experimental mechanics for measurement of deformation/strain. In this paper, the FEM-DIC method is refined by introducing the concept of multilevel extended digital image correlation (X-DIC), which also can capture deformation across discontinuity planes if they exist in images. Using regular and enhanced displacements at each node, strain tensors are estimated by applying the concept of smooth particle hydrodynamics (SPH). Numerical works are carried out to check the accuracy level of the developed algorithm by considering discrete discontinuity on the surface of a sample. Work is further extended to determine displacements and strains developed at the surface of several cubical concrete samples under uniaxial loading conditions. The tests are conducted until fractures are developed in the post-failure region. Using the concept of cumulative effective strain, a parameter is identified, which can be used as a precursor in the object failure process.
Coupling impedances of small discontinuities: Dependence on beam velocity
Kurennoy, Sergey S.
2006-05-01
The beam coupling impedances of small discontinuities of an accelerator vacuum chamber have been calculated [e.g., Kurennoy, Gluckstern, and Stupakov, Phys. Rev. E 52, 4354 (1995)PLEEE81063-651X10.1103/PhysRevE.52.4354] for ultrarelativistic beams using the Bethe diffraction theory. Here we extend the results to an arbitrary beam velocity. The vacuum chamber is assumed to have an arbitrary, but uniform along the beam path, cross section. The longitudinal and transverse coupling impedances are derived in terms of series over cross-section eigenfunctions, while the discontinuity shape enters via its polarizabilities. Simple explicit formulas for two important particular cases—circular and rectangular chamber cross sections—are presented. The impedance dependence on the beam velocity exhibits some unusual features: for example, the reactive impedance, which dominates in the ultrarelativistic limit, can vanish at a certain beam velocity, or its magnitude can exceed the ultrarelativistic value many times. In addition, we demonstrate that the same technique, the field expansion into a series of cross-section eigenfunctions, is convenient for calculating the space-charge impedance of uniform beam pipes with arbitrary cross section.
Kohn-Sham potential with discontinuity for band gap materials
Kuisma, M.; Ojanen, J.; Enkovaara, J.; Rantala, T. T.
2010-09-01
We model a Kohn-Sham potential with the discontinuity at integer particle numbers starting from the approximation by (GLLB) Gritsenko [Phys. Rev. A 51, 1944 (1995)10.1103/PhysRevA.51.1944]. We evaluate the Kohn-Sham gap and the discontinuity to obtain the quasiparticle gap. This allows us to compare the Kohn-Sham gaps to those obtained by accurate many-body perturbation-theory-based optimized potential methods. In addition, the resulting quasiparticle band gap is compared to experimental gaps. In the GLLB model potential, the exchange-correlation hole is modeled using a generalized gradient approximation (GGA) energy density and the response of the hole-to-density variations is evaluated by using the common-denominator approximation and homogeneous electron-gas-based assumptions. In our modification, we have chosen the PBEsol potential as the GGA to model the exchange hole and add a consistent correlation potential. The method is implemented in the GPAW code, which allows efficient parallelization to study large systems. A fair agreement for Kohn-Sham and the quasiparticle band gaps with semiconductors and other band gap materials is obtained with a potential which is as fast as GGA to calculate.
Scaling of clusters near discontinuous percolation transitions in hyperbolic networks.
Singh, Vijay; Boettcher, Stefan
2014-07-01
We investigate the onset of the discontinuous percolation transition in small-world hyperbolic networks by studying the systems-size scaling of the typical largest cluster approaching the transition, p ↗ p(c). To this end, we determine the average size of the largest cluster 〈s(max)〉 ∼ N(Ψ(p)) in the thermodynamic limit using real-space renormalization of cluster-generating functions for bond and site percolation in several models of hyperbolic networks that provide exact results. We determine that all our models conform to the recently predicted behavior regarding the growth of the largest cluster, which found diverging, albeit subextensive, clusters spanning the system with finite probability well below p(c) and at most quadratic corrections to unity in Ψ(p) for p ↗ p(c). Our study suggests a large universality in the cluster formation on small-world hyperbolic networks and the potential for an alternative mechanism in the cluster formation dynamics at the onset of discontinuous percolation transitions.
Discontinuous Galerkin flood model formulation: Luxury or necessity?
Kesserwani, Georges; Wang, Yueling
2014-08-01
The finite volume Godunov-type flood model formulation is the most comprehensive amongst those currently employed for flood risk modeling. The local Discontinuous Galerkin method constitutes a more complex, rigorous, and extended local Godunov-type formulation. However, the practical merit associated with such an increase in the level of complexity of the formulation is yet to be decided. This work makes the case for a second-order Runge-Kutta Discontinuous Galerkin (RKDG2) formulation and contrasts it with the equivalently accurate finite volume (MUSCL) formulation, both of which solve the Shallow Water Equations (SWE) in two space dimensions. The numerical complexity of both formulations are presented and their capabilities are explored for wide-ranging diagnostic and real-scale tests, incorporating all challenging features relevant to flood inundation modeling. Our findings reveal that the extra complexity associated with the RKDG2 model pays off by providing higher-quality solution behavior on very coarse meshes and improved velocity predictions. The practical implication of this is that improved accuracy for flood modeling simulations will result when terrain data are limited or of a low resolution.
Cockroaches breathe discontinuously to reduce respiratory water loss.
Schimpf, Natalie G; Matthews, Philip G D; Wilson, Robbie S; White, Craig R
2009-09-01
The reasons why many insects breathe discontinuously at rest are poorly understood and hotly debated. Three adaptive hypotheses attempt to explain the significance of these discontinuous gas exchange cycles (DGCs), whether it be to save water, to facilitate gas exchange in underground environments or to limit oxidative damage. Comparative studies favour the water saving hypothesis and mechanistic studies are equivocal but no study has examined the acclimation responses of adult insects chronically exposed to a range of respiratory environments. The present research is the first manipulative study of such chronic exposure to take a strong-inference approach to evaluating the competing hypotheses according to the explicit predictions stemming from them. Adult cockroaches (Nauphoeta cinerea) were chronically exposed to various treatments of different respiratory gas compositions (O(2), CO(2) and humidity) and the DGC responses were interpreted in light of the a priori predictions stemming from the competing hypotheses. Rates of mass loss during respirometry were also measured for animals acclimated to a range of humidity conditions. The results refute the hypotheses of oxidative damage and underground gas exchange, and provide evidence supporting the hypothesis that DGCs serve to reduce respiratory water loss: cockroaches exposed to low humidity conditions exchange respiratory gases for shorter durations during each DGC and showed lower rates of body mass loss during respirometry than cockroaches exposed to high humidity conditions.
Effect of oxytocin discontinuation during the active phase of labor.
Öztürk, Filiz Halıcı; Yılmaz, Saynur Sarıcı; Yalvac, Serdar; Kandemir, Ömer
2015-01-01
To observe the progression of labor when oxytocin use is limited to the onset of the active stage of labor. A randomized, prospective controlled study was performed to address the issue of oxytocin infusion after the onset of active labor in 140 patients. In the study group, infusion of oxytocin was discontinued at the onset of the active phase of labor, which was accepted as a cervical dilatation of 5 cm. In the control group, incremental oxytocin infusion was administered until 5 cm cervical dilatation, and then was maintained at the same level until delivery. The primary outcome variable was duration from the beginning of the active phase to delivery. In the study group, the duration of the active phase of labor was about 30 min longer than in the control group and this difference was significant. The secondary outcomes of the study were maternal-fetal complications of oxytocin and in both groups there were no significant differences. It is not reasonable to discontinue oxytocin infusion at the beginning of active labor. Nevertheless, for an accurate conclusion expanded investigations are needed.
Bow-shock Pulsar Wind Nebulae Passing Through Density Discontinuities
Yoon, Doosoo
2016-01-01
Bow-shock pulsar wind nebulae are a subset of pulsar wind nebulae that form when the pulsar has high velocity due to the natal kick during the supernova explosion. The interaction between the relativistic wind from the fast-moving pulsar and the interstellar medium produces a bow-shock and a trail, which are detectable in H$_{\\alpha}$ emission. Among such bow-shock pulsar wind nebulae, the Guitar Nebula stands out for its peculiar morphology, which consists of a prominent bow-shock head and a series of bubbles further behind. We present a scenario in which multiple bubbles can be produced when the pulsar encounters a series of density discontinuities in the ISM. We tested the scenario using 2-D and 3-D hydrodynamic simulations. The shape of the guitar nebula can be reproduced if the pulsar traversed a region of declining low density. We also show that if a pulsar encounters an inclined density discontinuity, it produces an asymmetric bow-shock head, consistent with observations of the bow-shock of the millise...
Bifurcation in autonomous and nonautonomous differential equations with discontinuities
Akhmet, Marat
2017-01-01
This book is devoted to bifurcation theory for autonomous and nonautonomous differential equations with discontinuities of different types. That is, those with jumps present either in the right-hand-side or in trajectories or in the arguments of solutions of equations. The results obtained in this book can be applied to various fields such as neural networks, brain dynamics, mechanical systems, weather phenomena, population dynamics, etc. Without any doubt, bifurcation theory should be further developed to different types of differential equations. In this sense, the present book will be a leading one in this field. The reader will benefit from the recent results of the theory and will learn in the very concrete way how to apply this theory to differential equations with various types of discontinuity. Moreover, the reader will learn new ways to analyze nonautonomous bifurcation scenarios in these equations. The book will be of a big interest both for beginners and experts in the field. For the former group o...
Discontinuous Transition of a Multistage Independent Cascade Model on Networks
Hasegawa, Takehisa
2012-01-01
We study a multistage independent cascade (MIC) model in complex networks. This model is parameterized by two probabilities: T1 is the probability that a node adopting a fad increases the awareness of a neighboring susceptible node until it abandons the fad, and T2 is the probability that an adopter directly causes a susceptible node to adopt the fad. We formulate a framework of tree approximation for the MIC model on an uncorrelated network with an arbitrary given degree distribution. As an application, we study this model on a random regular network with degree k=6 to show that it has a rich phase diagram including continuous and discontinuous transition lines for the percolation of fads as well as a continuous transition line for the percolation of susceptible nodes. In particular, the percolation transition of fads is discontinuous (continuous) when T1 is larger (smaller) than a certain value. Furthermore, the phase boundaries drastically change by assigning a finite fraction of initial adopters. We discu...
Moho depth and two discontinuities variation in Taiwan from radial teleseismic receiver functions
Ton, C.; Chen, C. H.
2005-12-01
In this study, we use data recorded by the stations of Broadband Array in Taiwan for Seismology (BATS) to investigate the depths of major discontinuities of the crust in Taiwan. From the differential times between direct P wave and converted Ps phase and several multiple phases on radial teleseismic receiver function, we determine the Moho depth and the Vp/Vs ratios at these stations. More importantly, we develop a method which can let us use more seismic phases to examine other discontinuities in the crust. Using the arrival times of some specific phases on radial teleseismic receiver function, except for Moho discontinuity, we found that there are two discontinuities ( denoted by discontinuity 1 and discontinuity 2 ) existing in the crust that beneath some of stations. The Moho depth in Taiwan varies from 22 to 39 km and Vp/Vs ratios varies from 1.64~1.87. The deepest Moho depth in Taiwan locates at the Central Mountain Range (CMR) and consistent with the result obtained from gravity survey. The discontinuity 1 and the discontinuity 2 exist clearly in the CMR, in the southern region and the northeastern region of Taiwan. These two discontinuities both become unapparent in the northern region (volcano region) and in the southeastern region (plate convergent area) of Taiwan. The depth of the discontinuity 1 varies from 4.5 to 11 km and while the depth of the discontinuity 2 varies from 12 to 22 km in our estimation. Based on these results, we imply that the discontinuity 1 and 2 are basement and the Conrad discontinuity respectively.
Kasenda Benjamin
2012-08-01
Full Text Available Abstract Background Randomized controlled trials (RCTs may be discontinued because of apparent harm, benefit, or futility. Other RCTs are discontinued early because of insufficient recruitment. Trial discontinuation has ethical implications, because participants consent on the premise of contributing to new medical knowledge, Research Ethics Committees (RECs spend considerable effort reviewing study protocols, and limited resources for conducting research are wasted. Currently, little is known regarding the frequency and characteristics of discontinued RCTs. Methods/Design Our aims are, first, to determine the prevalence of RCT discontinuation for specific reasons; second, to determine whether the risk of RCT discontinuation for specific reasons differs between investigator- and industry-initiated RCTs; third, to identify risk factors for RCT discontinuation due to insufficient recruitment; fourth, to determine at what stage RCTs are discontinued; and fifth, to examine the publication history of discontinued RCTs. We are currently assembling a multicenter cohort of RCTs based on protocols approved between 2000 and 2002/3 by 6 RECs in Switzerland, Germany, and Canada. We are extracting data on RCT characteristics and planned recruitment for all included protocols. Completion and publication status is determined using information from correspondence between investigators and RECs, publications identified through literature searches, or by contacting the investigators. We will use multivariable regression models to identify risk factors for trial discontinuation due to insufficient recruitment. We aim to include over 1000 RCTs of which an anticipated 150 will have been discontinued due to insufficient recruitment. Discussion Our study will provide insights into the prevalence and characteristics of RCTs that were discontinued. Effective recruitment strategies and the anticipation of problems are key issues in the planning and evaluation of trials
Towards new mathematical tools for obtaining chronologies in discontinuous archives
Donner, Reik V.
2014-05-01
In the last years, a variety of new mathematical approaches has been developed for obtaining reliable chronologies of geological and geomorphological archives based on a limited set of dating horizons. These new approaches work relatively well for continuous archives, but quickly approach their conceptual limits in the presence of discontinuities. Here, I report first steps towards improving existing mathematical algorithms in their performance regarding unknown discontinuities by integrating complementary information based on variations encoded in other archives. The proposed method is based on the following ingredients: (1) a correlation estimator for arbitrarily spaced time series, (2) a maximization criterion for correlations based on a linear rescaling of the unknown time axis, (3) a procedure allowing an automatic evaluation of minimum-cost paths for performing a sophisticated version of "wiggle-matching", and (4) improving the relative chronologies by adding explicit dates via some additional penalty term. To this end, I will mainly focus on the methodological details associated with the first two steps. Here, correlations between the data set under study and the "reference" archive are evaluated for running windows along the records utilizing a recently developed non-parametric correlation estimator based on a Gaussian kernel function. Allowing for an arbitrary rescaling of the time axis around the respective window midpoint, maximum correlations arise when the windows represent the same time intervals and the rescaled time axis corrects for different material accumulation rates. For sufficiently high-resolution records, the proposed approach can be extended to account also for possible non-linear co-variations between the two considered archives or proxies. By identifying sequences of subsequent windows with particularly high correlations, relative chronologies can be obtained. Moreover, gaps in such sequences are indicative of archive discontinuities and
Contribution of strong discontinuities to the power spectrum of the solar wind.
Borovsky, Joseph E
2010-09-10
Eight and a half years of magnetic field measurements (2(22) samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the "inertial subrange" with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this "inertial subrange." Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.
Howland, Robert H
2010-08-01
Abrupt discontinuation of antipsychotic drugs in patients with schizophrenia is associated with earlier, and often more severe, illness episodes than are seen with gradual discontinuation. Antipsychotic drugs can cause various abnormal motor syndromes, but abruptly stopping them has been associated with the seemingly paradoxical development of similar motor syndromes, such as withdrawal dyskinesias, parkinsonian symptoms, dystonias, and neuroleptic malignant syndrome. Dopamine-releasing and dopamine-agonist drugs are used to treat some of the motor syndromes caused by antipsychotic drugs, but their abrupt discontinuation can also be associated with abnormal syndromes. When antipsychotic drugs, lithium, or certain anticonvulsant drugs are used for treatment of bipolar disorder, rapid versus gradual discontinuation is more likely to lead to greater mood instability and manic relapse. If necessary, these medications should be gradually tapered to minimize all types of adverse discontinuation effects. Patients should be educated about the possible adverse effects of abrupt medication discontinuation.
Splitting of the 520-kilometer seismic discontinuity and chemical heterogeneity in the mantle.
Saikia, Ashima; Frost, Daniel J; Rubie, David C
2008-03-14
Seismic studies indicate that beneath some regions the 520-kilometer seismic discontinuity in Earth's mantle splits into two separate discontinuities (at approximately 500 kilometers and approximately 560 kilometers). The discontinuity near 500 kilometers is most likely caused by the (Mg,Fe)2SiO4 beta-to-gamma phase transformation. We show that the formation of CaSiO3 perovskite from garnet can cause the deeper discontinuity, and by determining the temperature dependence for this reaction we demonstrate that regional variations in splitting of the discontinuity arise from variability in the calcium concentration of the mantle rather than from temperature changes. This discontinuity therefore is sensitive to large-scale chemical heterogeneity. Its occurrence and variability yield regional information on the fertility of the mantle or the proportion of recycled oceanic crust.
He, Zhijian
2017-01-01
This paper studies randomized quasi-Monte Carlo (QMC) sampling for discontinuous integrands having singularities along the boundary of the unit cube $[0,1]^d$. Both discontinuities and singularities are extremely common in the pricing and hedging of financial derivatives and have a tremendous impact on the accuracy of QMC. It was previously known that the root mean square error of randomized QMC is only $o(n^{-1/2})$ for discontinuous functions with singularities. We find that under some mild...
Pottegård, Anton; Bjerregaard, B. K.; Kortegaard, L. S.
2015-01-01
Knowledge of patterns of treatment discontinuation in attention-deficit/hyperactivity disorder (ADHD) drug treatment is of importance, for both the clinical practice and the study of long-term treatment outcomes. The purpose of this study was to describe early discontinuation of ADHD drug treatment...... regions, except for adults in the capital region. Overall, early discontinuation was somewhat lower than expected, considering rates of side effects or non-response to ADHD drug treatment....
Signal processing technique for randomly discontinuous spectra HF radar waveforms
张东坡; 刘兴钊
2004-01-01
A major problem with all high frequency (HF) radars is a relatively poor range resolution available due to many interference sources. To avoid the interferences in frequency domain and operate with wideband, the randomly discontinuous spectra (RDS) signal is employed. However, it results in high range sidelobes when matching the reflected echo, which is much more difficult for target detection. A new signal processing technique that is radically different from the conventional technique to lower range sidelobes is introduced. This method is based on suppressing the selfclutter of the radar range ambiguity function (AF) by mismatched filtering. An effective algorithm is adopted to solve the filter coefficients. Simulation results show that the peak sidelobe level can be reduced to -30dB and the achievable system bandwidth is about 400KHz. The technique is adaptable to practical radar systems and applicable for other realtime signal processing.
Cryogenic thermal storage system for discontinuous industrial vacuum processes
Scaringella M.
2012-10-01
Full Text Available Phase Change Materials are proposed for refrigerating systems in discontinuous industrial vacuum processes where temperatures as low as −140 ÷ −100°C are necessary within time-frames representing 10÷20% of total operating time. An application is proposed for cooling systems used in a Physical Vapour Deposition (PVD apparatus. A prototype has been manufactured which couples a cryopump with a reservoir filled with MethylCycloPentane (MCP-C6H12 and a distribution line where nitrogen in the gaseous state is flowing. Preliminary tests show that temperatures of about −120°C are actually achieved within time windows compatible with PVD applications.
Scalable parallel Newton-Krylov solvers for discontinuous Galerkin discretizations
Persson, P.-O.
2008-12-31
We present techniques for implicit solution of discontinuous Galerkin discretizations of the Navier-Stokes equations on parallel computers. While a block-Jacobi method is simple and straight-forward to parallelize, its convergence properties are poor except for simple problems. Therefore, we consider Newton-GMRES methods preconditioned with block-incomplete LU factorizations, with optimized element orderings based on a minimum discarded fill (MDF) approach. We discuss the difficulties with the parallelization of these methods, but also show that with a simple domain decomposition approach, most of the advantages of the block-ILU over the block-Jacobi preconditioner are still retained. The convergence is further improved by incorporating the matrix connectivities into the mesh partitioning process, which aims at minimizing the errors introduced from separating the partitions. We demonstrate the performance of the schemes for realistic two- and three-dimensional flow problems.
Should School Boards Discontinue Support for High School Football?
Margolis, Lewis H; Canty, Greg; Halstead, Mark; Lantos, John D
2017-01-01
A pediatrician is asked by her local school board to help them decide whether to discontinue their high school football program. She reviews the available evidence on the risks of football and finds it hopelessly contradictory. Some scholars claim that football is clearly more dangerous than other sports. Others suggest that the risks of football are comparable to other sports, such as lacrosse, ice hockey, or soccer. She finds very little data on the long-term sequelae of concussions. She sees claims that good coaching and a school culture that prioritizes the health of athletes over winning can reduce morbidity from sports injuries. In this paper, 3 experts also review the evidence about sports risks and discuss what is known and not known about the science and the ethics of high school football. Copyright © 2017 by the American Academy of Pediatrics.
On the propagation of jump discontinuities in relativistic cosmology
Van Elst, H; Schmidt, B G; Elst, Henk van; Ellis, George F R; Schmidt, Bernd G
2000-01-01
A recent dynamical formulation at derivative level $\\ptl^{3}g$ for fluid spacetime geometries $({\\cal M}, {\\bf g}, {\\bf u})$, that employs the concept of evolution systems in first-order symmetric hyperbolic format, implies the existence in the Weyl curvature branch of a set of timelike characteristic 3-surfaces associated with propagation speed $| v | = \\sfrac{1}{2}$ relative to fluid-comoving observers. We show it is the physical role of the constraint equations to prevent realisation of jump discontinuities in the derivatives of the related initial data so that Weyl curvature modes propagating along these 3-surfaces cannot be activated. In addition we introduce a new, illustrative first-order symmetric hyperbolic evolution system at derivative level $\\ptl^{2}g$ for baryotropic perfect fluid cosmological models that are invariant under the transformations of an Abelian $G_{2}$ isometry group.
Simulating Turbulence Using the Astrophysical Discontinuous Galerkin Code TENET
Bauer, Andreas; Springel, Volker; Chandrashekar, Praveen; Pakmor, Rüdiger; Klingenberg, Christian
2016-01-01
In astrophysics, the two main methods traditionally in use for solving the Euler equations of ideal fluid dynamics are smoothed particle hydrodynamics and finite volume discretization on a stationary mesh. However, the goal to efficiently make use of future exascale machines with their ever higher degree of parallel concurrency motivates the search for more efficient and more accurate techniques for computing hydrodynamics. Discontinuous Galerkin (DG) methods represent a promising class of methods in this regard, as they can be straightforwardly extended to arbitrarily high order while requiring only small stencils. Especially for applications involving comparatively smooth problems, higher-order approaches promise significant gains in computational speed for reaching a desired target accuracy. Here, we introduce our new astrophysical DG code TENET designed for applications in cosmology, and discuss our first results for 3D simulations of subsonic turbulence. We show that our new DG implementation provides ac...
A REVISED SOLUTION OF EQUIVALENT PERMEABILITY TENSOR FOR DISCONTINUOUS FRACTURES
HE Ji; CHEN Sheng-hong; SHAHROUR Isam
2012-01-01
The equivalent permeability tensor is essential to the application of the equivalent porous media model in the numerical seepage simulation for fractured rock masses.In this paper,a revised solution of the equivalent permeability tensor is proposed to represent the influence of the fracture connectivity in discontinuous fractures.A correction coefficient is involved to reflect the complex seepage flow type through the rock bridge.This correction coefficient is back analyzed from single-hole packer tests,based on the Artificial Neural Network (ANN) back analysis and the Finite Element Method (FEM) seepage simulation.The limitation of this back analysis algorithm is that the number of single-hole packer tests should be equal or greater than the number of fracture sets,and three is the maximum number of the fracture sets.The proposed solution and the back analysis algorithm are applied in the permeability measurement and the seepage simulation for the Xiaowan arch dam foundation.
NUMERICAL MODELLING OF DISCONTINUOUS ROCK MASS IN THE ELASTIC DOMAIN
Biljana Kovačević-Zelić
1995-12-01
Full Text Available Constitutive relationships of rock materials are an important component of the numerical modelling, it is not possible to find a generally acceptable constitutive law for rock materials, because of their complex nature. In this paper, the applicability of some models within the framework of theory of elasticity are examined. The analyses are carried out using next models: isotropic and transversely isotropic model, and 'equivalent' material approach The parametric study is also made to examine the influence of discontinuities on the parameters of the equivalent materials the comparison of above mentioned models is made through numerical modelling of the direct shear test. The analysis were performed with finite difference code FLAC (the paper is published in Croatian.
Generalized Stefan models accounting for a discontinuous temperature field
Danescu, A.
We construct a class of generalized Stefan models able to account for a discontinuous temperature field across a nonmaterial interface. The resulting theory introduces a constitutive scalar interfacial field, denoted by /lineθ and called the equivalent temperature of the interface. A classical procedure, based on the interfacial dissipation inequality, relates the interfacial energy release to the interfacial mass flux and restricts the equivalent temperature of the interface. We show that previously proposed theories are obtained as particular cases when /lineθ = ⪉θ > or /lineθ = ⪉(1)/(θ )>-1 or, more generally, when /lineθ = ⪉θ r ⪉ 1/θ1-r-1 for 0<= r<= 1. We study in a particular constitutive framework the solidification of an under-cooled liquid and we are able to give a sufficient condition for the existence of travelling wave solutions.
3D unstructured mesh discontinuous finite element hydro
Prasad, M.K.; Kershaw, D.S.; Shaw, M.J. [Lawrence Livermore National Lab., CA (United States)
1995-07-01
The authors present detailed features of the ICF3D hydrodynamics code used for inertial fusion simulations. This code is intended to be a state-of-the-art upgrade of the well-known fluid code, LASNEX. ICF3D employs discontinuous finite elements on a discrete unstructured mesh consisting of a variety of 3D polyhedra including tetrahedra, prisms, and hexahedra. The authors discussed details of how the ROE-averaged second-order convection was applied on the discrete elements, and how the C++ coding interface has helped to simplify implementing the many physics and numerics modules within the code package. The author emphasized the virtues of object-oriented design in large scale projects such as ICF3D.
[Bilateral renal infarction after discontinuation of anticoagulant therapy].
Lavoignet, Charles-Éric; Le Borgne, Pierrick; Ugé, Sarah; Veneziano, Rinaldo; Brunhuber, Claudia; Kam, Claire; Bilbault, Pascal
2016-07-01
Acute renal infarction is an uncommon and often under diagnosed condition mostly because of misleading symptoms. Accurate data regarding clinical presentation, laboratory tests, diagnostic and treatment are lacking. Detection is often delayed or missed because of non-specific clinical presentation. The mechanisms of acute renal infarction are various, mainly embolic or thrombotic. Abdominal CT scan remains the most valuable exam to confirm the diagnosis. Therapeutic guidelines for the treatment of renal embolism have not been well established. The standard treatment strategy includes anticoagulation with or without thrombolysis. Despite the uncertainty regarding management, the renal outcome remains favorable. Some patients do develop some degree of renal insufficiency during the acute episode. We report here the case of a 73-year-old woman with bilateral acute renal infarction after discontinuation of anticoagulant therapy.
Numerical integration of discontinuous functions: moment fitting and smart octree
Hubrich, Simeon; Di Stolfo, Paolo; Kudela, László; Kollmannsberger, Stefan; Rank, Ernst; Schröder, Andreas; Düster, Alexander
2017-07-01
A fast and simple grid generation can be achieved by non-standard discretization methods where the mesh does not conform to the boundary or the internal interfaces of the problem. However, this simplification leads to discontinuous integrands for intersected elements and, therefore, standard quadrature rules do not perform well anymore. Consequently, special methods are required for the numerical integration. To this end, we present two approaches to obtain quadrature rules for arbitrary domains. The first approach is based on an extension of the moment fitting method combined with an optimization strategy for the position and weights of the quadrature points. In the second approach, we apply the smart octree, which generates curved sub-cells for the integration mesh. To demonstrate the performance of the proposed methods, we consider several numerical examples, showing that the methods lead to efficient quadrature rules, resulting in less integration points and in high accuracy.
Perceived discontinuities and continuities in transdisciplinary scientific working groups.
Crowston, Kevin; Specht, Alison; Hoover, Carol; Chudoba, Katherine M; Watson-Manheim, Mary Beth
2015-11-15
We examine the DataONE (Data Observation Network for Earth) project, a transdisciplinary organization tasked with creating a cyberinfrastructure platform to ensure preservation of and access to environmental science and biological science data. Its objective was a difficult one to achieve, requiring innovative solutions. The DataONE project used a working group structure to organize its members. We use organizational discontinuity theory as our lens to understand the factors associated with success in such projects. Based on quantitative and qualitative data collected from DataONE members, we offer recommendations for the use of working groups in transdisciplinary synthesis. Recommendations include welcome diverse opinions and world views, establish shared communication practices, schedule periodic synchronous face-to-face meetings, and ensure the active participation of bridge builders or knowledge brokers such as librarians who know how to ask questions about disciplines not their own. Copyright © 2015 Elsevier B.V. All rights reserved.
Adaptive discontinuous Galerkin methods for non-linear reactive flows
Uzunca, Murat
2016-01-01
The focus of this monograph is the development of space-time adaptive methods to solve the convection/reaction dominated non-stationary semi-linear advection diffusion reaction (ADR) equations with internal/boundary layers in an accurate and efficient way. After introducing the ADR equations and discontinuous Galerkin discretization, robust residual-based a posteriori error estimators in space and time are derived. The elliptic reconstruction technique is then utilized to derive the a posteriori error bounds for the fully discrete system and to obtain optimal orders of convergence. As coupled surface and subsurface flow over large space and time scales is described by (ADR) equation the methods described in this book are of high importance in many areas of Geosciences including oil and gas recovery, groundwater contamination and sustainable use of groundwater resources, storing greenhouse gases or radioactive waste in the subsurface.
Wave propagation in pantographic 2D lattices with internal discontinuities
Madeo, A; Neff, P
2014-01-01
In the present paper we consider a 2D pantographic structure composed by two orthogonal families of Euler beams. Pantographic rectangular 'long' waveguides are considered in which imposed boundary displacements can induce the onset of traveling (possibly non-linear) waves. We performed numerical simulations concerning a set of dynamically interesting cases. The system undergoes large rotations which may involve geometrical non-linearities, possibly opening the path to appealing phenomena such as propagation of solitary waves. Boundary conditions dramatically influence the transmission of the considered waves at discontinuity surfaces. The theoretical study of this kind of objects looks critical, as the concept of pantographic 2D sheets seems to have promising possible applications in a number of fields, e.g. acoustic filters, vascular prostheses and aeronautic/aerospace panels.
Optimal command generation for tracking a class of discontinuous trajectories
Weissenberger, S.
1976-01-01
Commands are found to drive a linear system to optimally track a class of prescribed trajectories, each of which contains a point of discontinuity. The paper focuses on the guidance problem of command generation, to be implemented in a feedforward fashion; the necessary additional control or feedback regulation structure is not studied in detail, but assumed to be provided in applications as a conventional error-feedback regulator. Solutions are found for the infinite-time problem which are optimal with respect to a quadratic performance criterion; suboptimal controls which satisfy a continuity condition are also found. The controls have applications to certain problems in aircraft guidance where command trajectories are piecewise continuous. Several examples are worked out in detail, with comparisons with conventional, nonfeedforward solutions to the problem, and a brief discussion of a simpler, suboptimal solution.
The performance of proper orthogonal decomposition in discontinuous flows
Jing Li
2016-09-01
Full Text Available In this paper, flow reconstruction accuracy and flow prediction capability of discontinuous transonic flow field by means of proper orthogonal decomposition (POD method is studied. Although linear superposition of “high frequency waves” in different POD modes can achieve the reconstruction of the shock wave, the smoothness of the solution near the shock wave cannot be guaranteed. The modal coefficients are interpolated or extrapolated and different modal components are superposed to realize the prediction of the flow field beyond the snapshot sets. Results show that compared with the subsonic flow, the transonic flow with shock wave requires more POD modes to reach a comparative reconstruction accuracy. When a shock wave exists, the interpolation prediction ability is acceptable. However, large errors exist in extrapolation, and increasing the number of POD modes cannot effectively improve the prediction accuracy of the flow field.
Clearance gap flow: simulations by discontinuous Galerkin method and experiments
Prausová Helena
2015-01-01
Full Text Available Compressible viscous fluid flow in a narrow gap formed by two parallel plates in distance of 2 mm is investigated numerically and experimentally. Pneumatic and optical methods were used to obtain distribution of static to stagnation pressure ratio along the channel axis and interferograms including the free outflow behind the channel. Modern developing discontinuous Galerkin finite element method is implemented for numerical simulation of the fluid flow. The goal to make progress in knowledge of compressible viscous fluid flow characteristic phenomena in minichannels is satisfied by finding a suitable approach to this problem. Laminar, turbulent and transitional flow regime is examined and a good agreement of experimental and numerical results is achieved using γ − Reθt transition model.
Clearance gap flow: simulations by discontinuous Galerkin method and experiments
Prausová, Helena; Bublík, Ondřej; Vimmr, Jan; Luxa, Martin; Hála, Jindřich
2015-05-01
Compressible viscous fluid flow in a narrow gap formed by two parallel plates in distance of 2 mm is investigated numerically and experimentally. Pneumatic and optical methods were used to obtain distribution of static to stagnation pressure ratio along the channel axis and interferograms including the free outflow behind the channel. Modern developing discontinuous Galerkin finite element method is implemented for numerical simulation of the fluid flow. The goal to make progress in knowledge of compressible viscous fluid flow characteristic phenomena in minichannels is satisfied by finding a suitable approach to this problem. Laminar, turbulent and transitional flow regime is examined and a good agreement of experimental and numerical results is achieved using γ - Reθt transition model.
Corporate Entrepreneurship in SMEs during the Search for Discontinuous Innovations
van Geenhuizen, Maurits; Middel, Rick; Lassen, Astrid Heidemann
2008-01-01
The present paper illustrates, through three Danish/Dutch case studies, how several of the characteristics connected with SMEs entail significant reasons to make use of corporate entrepreneurship as a search strategy for discontinuous innovation. Characteristic dimensions of corporate...... entrepreneurship are researched, and pro-activity, risk-taking and autonomy are in particular found to be significant elements of the approach applied. The way these dimensions are implemented, counterbalances the resources constraints in terms of human, social and financial capital found in the SME setting....... Competitive aggressiveness is found to be only indirectly influential as a way for the case firms to stay ahead of other firms by knowing what developments are made on shared technologies or part components....
MODE THEORY OF MULTILAYER WAVEGUIDE STRUCTURE WITH DISCONTINUITIES
Zong Weihua; Liang Changhong
2003-01-01
TEn mode (whose electric field is zero in the normal direction of theboundafiesbetween layers) and TMn mode (whose magnetic field is zero in the normal direction of the bound-aries between layers) are defined. Then conditions under which pure TEn (TMn) modes may existin multilayer waveguide structure with discontinuities are presented. E (H) step wavguides, ridgedwavguides, microstrip lines and fin lines all satisfy the conditions, and hold for TEn (TMn) mode.The conventional conclusion that ridged waveguides with inhomogeneous dielectric-slab loading,microstrip lines and fin lines only hold for hybrid modes is revised. Compared with hybrid modes,the number of unknown variations and matching equations is reduced by half for pure TEn (TMn)modes, and the computation cost is decreased dramatically.
Dynamic Discontinuous Control for Active Control of Mechanical Vibrations
Orestes Llanes Santiago
2010-02-01
Full Text Available This article shows the use of the discontinuous control using dynamic sliding modes for the active isolation of vibrations in mechanical systems. This type of control law constitutes a robust feedback control policy due to its insensitivity to external disturbance inputs, certain immunity to model parameter variations, within known bounds, and to the ever present modelling errors. The whole theoretical analysis is applied to a lineal model of two degrees of freedom of the vehicle's suspension where the irregularities of the land represent of direct way the external interferences to the system . To carry out the isolation an electro-hydraulic operator it is used. Simulations are performed which validate the proposed approach.
Discontinuous Galerkin method for predicting heat transfer in hypersonic environments
Ching, Eric; Lv, Yu; Ihme, Matthias
2016-11-01
This study is concerned with predicting surface heat transfer in hypersonic flows using high-order discontinuous Galerkin methods. A robust and accurate shock capturing method designed for steady calculations that uses smooth artificial viscosity for shock stabilization is developed. To eliminate parametric dependence, an optimization method is formulated that results in the least amount of artificial viscosity necessary to sufficiently suppress nonlinear instabilities and achieve steady-state convergence. Performance is evaluated in two canonical hypersonic tests, namely a flow over a circular half-cylinder and flow over a double cone. Results show this methodology to be significantly less sensitive than conventional finite-volume techniques to mesh topology and inviscid flux function. The method is benchmarked against state-of-the-art finite-volume solvers to quantify computational cost and accuracy. Financial support from a Stanford Graduate Fellowship and the NASA Early Career Faculty program are gratefully acknowledged.
CONSTITUTIVE RELATION OF DISCONTINUOUS REINFORCED METAL-MATRIX COMPOSITES
季葆华; 王自强
2001-01-01
A micromechanical model is developed to simulate the mechanical behaviors of discontinuous reinforced composites. The analysis for a representative unit cell is based on the assumption of a periodic array of aligned reinforcements.The minimum energy principle is used to determine the unknown coefficients of the displacement field of the unit cell. The constitutive behavior of composites is studied to obtain the relationship between the main variables of matrix and reinforcements.It is concluded that the flow strength of composites is strongly influenced by volume fraction, aspect ratio of reinforcement, and the strain hardening exponent of matrix.An analytical constitutive relation of composites is obtained. The predicted results are in agreement with the existing experimental and numerical results.
Application of wall-models to discontinuous Galerkin LES
Frère, Ariane; Carton de Wiart, Corentin; Hillewaert, Koen; Chatelain, Philippe; Winckelmans, Grégoire
2017-08-01
Wall-resolved Large-Eddy Simulations (LES) are still limited to moderate Reynolds number flows due to the high computational cost required to capture the inner part of the boundary layer. Wall-modeled LES (WMLES) provide more affordable LES by modeling the near-wall layer. Wall function-based WMLES solve LES equations up to the wall, where the coarse mesh resolution essentially renders the calculation under-resolved. This makes the accuracy of WMLES very sensitive to the behavior of the numerical method. Therefore, best practice rules regarding the use and implementation of WMLES cannot be directly transferred from one methodology to another regardless of the type of discretization approach. Whilst numerous studies present guidelines on the use of WMLES, there is a lack of knowledge for discontinuous finite-element-like high-order methods. Incidentally, these methods are increasingly used on the account of their high accuracy on unstructured meshes and their strong computational efficiency. The present paper proposes best practice guidelines for the use of WMLES in these methods. The study is based on sensitivity analyses of turbulent channel flow simulations by means of a Discontinuous Galerkin approach. It appears that good results can be obtained without the use of a spatial or temporal averaging. The study confirms the importance of the wall function input data location and suggests to take it at the bottom of the second off-wall element. These data being available through the ghost element, the suggested method prevents the loss of computational scalability experienced in unstructured WMLES. The study also highlights the influence of the polynomial degree used in the wall-adjacent element. It should preferably be of even degree as using polynomials of degree two in the first off-wall element provides, surprisingly, better results than using polynomials of degree three.
Movement of trichloroethene in a discontinuous permafrost zone.
Carlson, Andrea E; Barnes, David L
2011-06-01
At a site with discontinuous permafrost in Fairbanks, Alaska, releases of trichloroethene (TCE), an industrial solvent, have caused contamination of the groundwater. The objective of this study was to investigate the relationship between the migration pathway of the TCE groundwater plume and the distribution of the discontinuous permafrost at the site. The TCE plume configuration is substantially different than what regional hydrology trends would predict. Using GIS, we conducted a geostatistical analysis of field data collected during soil-boring installations and groundwater monitoring well sampling. With the analysis results, we constructed maps of the permafrost-table elevation (top of permafrost) and of the groundwater gradients and TCE concentrations from multiyear groundwater sampling events. The plume concentrations and groundwater gradients were overlain on the permafrost map to correlate permafrost locations with groundwater movement and the spatial distribution of TCE moving with groundwater. Correlation of the overlay maps revealed converging and diverging groundwater flow in response to the permafrost-table distribution, the absence of groundwater contamination in areas with a high permafrost-table elevation, and channeling of contaminants and water between areas of permafrost. In addition, we measured groundwater elevations in nested wells to quantify vertical gradients affecting TCE migration. At one set of nested wells down gradient from an area of permafrost we measured an upward vertical gradient indicating recharge of groundwater from the subpermafrost region of the aquifer causing dilution of the plume. The study indicates that the variable distribution of the permafrost is affecting the way groundwater and TCE move through the aquifer. Consequently, changes to the permafrost configuration due to thawing would likely affect both groundwater movement and TCE migration, and areas that were contaminant-free may become susceptible to contamination.
Zhang, Sun, E-mail: szhang@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Key Laboratory of Dark Matter and Space Astronomy, Chinese Academy of Sciences, Nanjing 210008 (China); Joint Center for Particle, Nuclear Physics and Cosmology (J-CPNPC), PMO-NJU, Nanjing 210008 (China)
2014-02-05
In this Letter, we have studied the shock wave and discontinuity propagation for relativistic superfluid with spontaneous U(1) symmetry breaking in the framework of hydrodynamics. General features of shock waves are provided, the propagation of discontinuity and the sound modes of shock waves are also presented. The first sound and the second sound are identified as the propagation of discontinuity, and the results are in agreement with earlier theoretical studies. Moreover, a differential equation, called the growth equation, is obtained to describe the decay and growth of the discontinuity propagating along its normal trajectory. The solution is in an integral form and special cases of diverging waves are also discussed.
Beshir, Semira Abdi; Chee, Kok-Han; Lo, Yoke-Lin
2016-10-01
Background Oral anticoagulant therapy is indicated for the prevention of stroke or other thromboembolic events. Premature discontinuation of oral anticoagulants may increase the risk of thromboembolism resulting in adverse sequelae. There are sparse data on the prevalence and the predictors of dabigatran discontinuation in Malaysian patients with atrial fibrillation. Objectives Determine the reasons and identify associated factors for abrupt discontinuation of dabigatran, assess the switching pattern and the occurrence of thromboembolic events after dabigatran discontinuation. Setting A university-affiliated tertiary hospital in Kuala Lumpur, Malaysia. Methods The clinical and demographic data of a cohort who were initiated with dabigatran between 2010 and 2012 at the University of Malaya Medical Centre were reviewed until the date of death or on 31st December 2013. Those patients who discontinued dabigatran were further followed up until 31st December 2015 to determine the occurrence of any thromboembolic event. Main outcome measure Permanent discontinuation of dabigatran for more than 8 weeks. Results 26 (14 %) of a cohort of 192 patients discontinued dabigatran therapy during a median follow-up period of 20 (range 3-45) months. About one-half of the discontinuation occurred within the first 6 months of dabigatran use. The three most cited reasons for discontinuation are bleeding events (19 %), high out-of-pocket drug payment (19 %) and cardioversion (19 %). Heart failure [adjusted odds ratio 3.699 (95 % confidence interval 1.393-9.574)] or chronic kidney disease [adjusted odds ratio 5.211 (95 % confidence interval 1.068-23.475)] were found to be independent risk factors for abrupt dabigatran discontinuation. Patients who discontinued dabigatran received warfarin (38 %), antiplatelet agents (16 %) or no alternative antithrombotic therapy (46 %). Five of the 26 patients who discontinued dabigatran developed an ischaemic stroke within 3-34 months after
Vanga, Subba R; Satti, Sudhakar R; Williams, James; Weintraub, William; Doorey, Andrew
2015-01-01
Oral anticoagulants (OAC) are the therapy of choice to prevent thromboembolism in patients at risk. Discontinuation of OAC prior to elective medical and surgical procedures may reduce the risk of bleeding, but may expose patients to increased risk of thromboembolism and ischemic stroke. The current public health burden of ischemic strokes associated with OAC discontinuation is unknown. We aimed to study the prevalence OAC discontinuation in patients who presented with acute ischemic stroke as well as the outcomes of these strokes. Retrospective cross-sectional study by intensive chart review of all acute ischemic stroke patients over 6 months in a large tertiary care community hospital. A total of 431 patients with acute ischemic stroke were admitted during study period, of which 11 (2.6%) had OAC discontinuation within 120 days prior to the index admission. Several strokes occurred after relatively brief discontinuations. The patient group with discontinuation was older, had higher comorbidities and also had a clinically significant stroke and resulting higher mortality and morbidity. About 2.6% or 1 in every 38 of all ischemic stokes occurred after OAC discontinuation. Strokes occurring after OAC discontinuation also have higher mortality and morbidity. Our data suggest that any planned discontinuation of OAC, however brief, should be carefully considered.
Ma, Xichao; Xiao, Wen; Pan, Feng
2017-07-01
We present a reconstruction method for samples containing localized refractive index (RI) discontinuities in optical diffraction tomography. Abrupt RI changes induce regional phase perturbations and random spikes, which will be expanded and strengthened by existing tomographic algorithms, resulting in contaminated reconstructions. This method avoids the disturbance by recognition and separation of the discontinuous regions, and recombination of individually reconstructed data. Three-dimensional RI distributions of two fusion spliced optical fibers with different typical discontinuities are demonstrated, showing distinctly detailed structures of the samples as well as the positions and estimated shapes of the discontinuities.
Clopidogrel discontinuation within the first year after coronary drug-eluting stent implantation
Thim, Troels; Johansen, Martin Berg; Chisholm, Gro Egholm
2014-01-01
-eluting stents in Western Denmark for 1 year and obtained data on redeemed clopidogrel prescriptions and major adverse cardiovascular events (MACE, i.e., cardiac death, myocardial infarction, or stent thrombosis) from medical databases. RESULTS: Discontinuation of clopidogrel within the first 3 months after...... associated with smaller, not statistically significant, increases in MACE rates. Among patients who discontinued clopidogrel, MACE rates were highest within the first 2 months after discontinuation. CONCLUSIONS: Discontinuation of clopidogrel was associated with an increased rate of MACE among patients...
Tan, Cheng; Liang, Zhi-Shan
2016-03-01
In this paper, based on the fact that the inductors and capacitors are of fractional order in nature, the four-order mathematical model of the fractional order quadratic Boost converter in type I and type II discontinuous conduction mode (DCM) — DCM is established by using fractional calculus theory. Direct current (DC) analysis is conducted by using the DC equivalent model and the transfer functions are derived from the corresponding alternating current (AC) equivalent model. The DCM-DCM regions of type I and type II are obtained and the relations between the regions and the orders are found. The influence of the orders on the performance of the quadratic Boost converter in DCM-DCM is verified by numerical and circuit simulations. Simulation results demonstrate the correctness of the fractional order model and the efficiency of the proposed theoretical analysis.
Yang, Yunlong; Zhang, Yin; Iwamoto, Hideki
2016-01-01
The impact of discontinuation of anti-VEGF cancer therapy in promoting cancer metastasis is unknown. Here we show discontinuation of anti-VEGF treatment creates a time-window of profound structural changes of liver sinusoidal vasculatures, exhibiting hyper-permeability and enlarged open-pore size...... for uninterrupted and sustained antiangiogenic therapy for treatment of human cancers....
Discontinuities in Schooling and the Socioeconomic Life Cycle. Discussion Papers No. 238-74.
Featherman, David L.; Carter, T. Michael
In a longitudinal study of a 1939-40 birth cohort of Michigan men, the educational, occupational, and earnings costs of discontinuous patterns of school attendance over the life cycle were examined. The intracohort analysis aimed to identify plausible causal antecedents and consequences of discontinuities in schooling in the context of the…
2012-08-07
... respect to discontinuance actions for which initial feasibility studies have been initiated on or after... feasibility study of a USPS-operated facility for possible discontinuance. Any decision to close or... to make a helpful contribution toward the final decision. (5) Initial feasibility study. A...
Reasons for Discontinuing Hashish Use in a Group of Central European Athletes.
Duncan, David F.
1988-01-01
Examined self-reported reasons for discontinuing marijuana use among 61 former marijuana using students at central European sports training facility. Most common reasons given for discontinuing marijuana use were dislike of effects, athletic training regimen, health reasons, and mental/emotional problems. (Author/NB)
Regression Discontinuity in Prospective Evaluations: The Case of the FFVP Evaluation
Klerman, Jacob Alex; Olsho, Lauren E. W.; Bartlett, Susan
2015-01-01
While regression discontinuity has usually been applied retrospectively to secondary data, it is even more attractive when applied prospectively. In a prospective design, data collection can be focused on cases near the discontinuity, thereby improving internal validity and substantially increasing precision. Furthermore, such prospective…
hpGEM -- A software framework for discontinuous Galerkin finite element methods
Pesch, L.; Bell, A.; Sollie, W.E.H.; Ambati, V.R.; Bokhove, O.; Vegt, van der J.J.W.
2007-01-01
hpGEM, a novel framework for the implementation of discontinuous Galerkin finite element methods (FEMs), is described. We present data structures and methods that are common for many (discontinuous) FEMs and show how we have implemented the components as an object-oriented framework. This framework
hpGEM -- A software framework for discontinuous Galerkin finite element methods
Pesch, L.; Bell, A.; Sollie, W.E.H.; Ambati, V.R.; Bokhove, O.; Vegt, van der J.J.W.
2006-01-01
hpGEM, a novel framework for the implementation of discontinuous Galerkin finite element methods, is described. We present structures and methods that are common for many (discontinuous) finite element methods and show how we have implemented the components as an object-oriented framework. This fra
Continuity and Discontinuity in Education: Example of Transition from Preschool to School
Babic, Nada
2017-01-01
This article reconsiders multiple perspectives about continuity and discontinuity of early childhood education. Theoretical starting points, childhood policies and research of continuity and discontinuity exemplified through transition to school, are promising in rethinking and creating productive practices of childhood in different sociocultural…
Bretler, Ditte-Marie; Hansen, Peter Riis; Sørensen, Rikke;
2012-01-01
To assess the risk of adverse cardiovascular events in women who discontinue hormone replacement therapy after myocardial infarction compared with those who continue.......To assess the risk of adverse cardiovascular events in women who discontinue hormone replacement therapy after myocardial infarction compared with those who continue....
Wong, Vivian C.; Steiner, Peter M.; Cook, Thomas D.
2013-01-01
In a traditional regression-discontinuity design (RDD), units are assigned to treatment on the basis of a cutoff score and a continuous assignment variable. The treatment effect is measured at a single cutoff location along the assignment variable. This article introduces the multivariate regression-discontinuity design (MRDD), where multiple…
The risk of acute myocardial infarction after discontinuation of antihypertensive agents
Alharbi, Fawaz F.; Souverein, Patrick C.; De Groot, Mark C.H.; Der Zee, Anke H Maitland-Van; De Boer, Anthonius; Klungel, Olaf H.
2015-01-01
Background: Sudden discontinuation of some antihypertensive agents such as beta-blockers and centrally acting antihypertensive agents are associated with increased risk of acute coronary events. Objectives: The aim of this study was to assess the association between discontinuation of different
5 CFR 530.323 - Setting pay when a special rate is discontinued or decreased.
2010-01-01
... discontinued or decreased. 530.323 Section 530.323 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT... decreased. (a) General. This section applies when a special rate applicable to a position is discontinued or decreased because of— (1) A reduction or termination of the rates of the special rate schedule (or of rates...
The risk of acute myocardial infarction after discontinuation of antihypertensive agents
Alharbi, Fawaz F.; Souverein, Patrick C.; De Groot, Mark C.H.; Der Zee, Anke H Maitland-Van; De Boer, Anthonius; Klungel, Olaf H.
2015-01-01
Background: Sudden discontinuation of some antihypertensive agents such as beta-blockers and centrally acting antihypertensive agents are associated with increased risk of acute coronary events. Objectives: The aim of this study was to assess the association between discontinuation of different anti
Wong, Vivian C.; Steiner, Peter M.; Cook, Thomas D.
2012-01-01
In a traditional regression-discontinuity design (RDD), units are assigned to treatment and comparison conditions solely on the basis of a single cutoff score on a continuous assignment variable. The discontinuity in the functional form of the outcome at the cutoff represents the treatment effect, or the average treatment effect at the cutoff.…
van der Vegt, Jacobus J.W.; van der Ven, H.
1998-01-01
A new discretization method for the three-dimensional Euler equations of gas dynamics is presented, which is based on the discontinuous Galerkin finite element method. Special attention is paid to an efficient implementation of the discontinuous Galerkin method that minimizes the number of flux
Discontinuation of long-term benzodiazepine use : 10-year follow-up
de Gier, N. A. H.; Gorgels, W. J. M. J.; Lucassen, P. L. B. J.; Voshaar, R. Oude; Mulder, J.; Zitman, F.
2011-01-01
Background. Several interventions aiming at discontinuation of long-term benzodiazepine use have been proven effective in the short term. However, data on the persistence of discontinuation are lacking. Objectives. To assess 10-year follow-up status in patients who succeeded in stopping benzodiazepi
Adaptive multiresolution semi-Lagrangian discontinuous Galerkin methods for the Vlasov equations
Besse, N.; Deriaz, E.; Madaule, É.
2017-03-01
We develop adaptive numerical schemes for the Vlasov equation by combining discontinuous Galerkin discretisation, multiresolution analysis and semi-Lagrangian time integration. We implement a tree based structure in order to achieve adaptivity. Both multi-wavelets and discontinuous Galerkin rely on a local polynomial basis. The schemes are tested and validated using Vlasov-Poisson equations for plasma physics and astrophysics.
Van Wijk, Boris L G; Klungel, Olaf H; Heerdink, Eibert R; de Boer, Anthonius
2006-01-01
PURPOSE: Discontinuation with treatment is a major problem in the treatment of hypertension. The objective of our study was to assess the association between non-compliance and discontinuation in patients who started using antihypertensive monotherapy. METHODS: A nested case-control study within a c
41 CFR 101-39.105-1 - Transfers from discontinued or curtailed fleet management systems.
2010-07-01
... discontinued or curtailed fleet management systems. 101-39.105-1 Section 101-39.105-1 Public Contracts and... AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 39-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.1-Establishment, Modification, and Discontinuance of Interagency Fleet Management Systems § 101-39.105-1 Transfers...
A HIGHLY ACCURATE NUMERICAL METHOD FOR FLOWPROBLEMS WITH INTERACTIONS OF DISCONTINUITIES
Xiaonan Wu; Youlan Zhu
2002-01-01
A type of shock fitting method is used to solve some two and three dimensional flowproblems with interactions of various discontinuities. The numerical results show that highaccuracy is achieved for the flow field, especially at the discontinuities. Comparisons withthe Lax-Friedrichs scheme and the ENO scheme confirm the accuracy of the method.
Barth, TIm
2002-01-01
This viewgraph presentation provides information on optimizing the travel distance between two points on a curved surface. The presentation addresses the single source shortest path problem, fast algorithms for estimating the eikonal equation, fast schemes and barrier theorems, and the discontinuous Galerkin method, including hyperbolic causality, finite element method, scalars, and marching the discontinuous Galerkin Eikonal approximation.
S. HEIKKIL(A)
2006-01-01
In this paper we shall study the solvability of discontinuous functional equations, and apply the so-obtained results to discontinuous implicit initial value problems in ordered Banach spaces. The proofs are based on fixed point results in ordered spaces proved recently by the author. A concrete example is solved to demonstrate the obtained results.
76 FR 20819 - Manufacturers Railway Company-Discontinuance Exemption-in St. Louis County, MO
2011-04-13
.... Interstate 55 on the west, in St. Louis, Mo. The lines traverse U.S. Postal Service Zip Code 63118. MRS... practice regarding labor conditions in entire system discontinuances. The United Transportation Union, the...). Because this is a discontinuance proceeding and not an abandonment, a trail use/rail banking condition...
Van Wijk, Boris L G; Klungel, Olaf H; Heerdink, Eibert R; de Boer, Anthonius
PURPOSE: Discontinuation with treatment is a major problem in the treatment of hypertension. The objective of our study was to assess the association between non-compliance and discontinuation in patients who started using antihypertensive monotherapy. METHODS: A nested case-control study within a
A. A. Lubchich
2005-07-01
Full Text Available Characteristics of small amplitude plane waves within the medium separated by the plane discontinuity into two half spaces are analysed. The approximation of the ideal one-fluid magnetohydrodynamics (MHD is used. The discontinuities with the nonzero mass flux across them are mainly examined. These are fast or slow shock waves and rotational discontinuities. The dispersion equation for MHD waves within each of half space is obtained in the reference frame connected with the discontinuity surface. The solution of this equation permits one to determine the wave vectors versus the parameter c_{p}, which is the phase velocity of surface discontinuity oscillations. This value of c_{p} is common for all MHD waves and determined by an incident wave or by spontaneous oscillations of the discontinuity surface. The main purpose of the study is a detailed analysis of the dispersion equation solution. This analysis let us draw the following conclusions. (I For a given c_{p}, ahead or behind a discontinuity at most, one diverging wave can transform to a surface wave damping when moving away from the discontinuity. The surface wave can be a fast one or, in rare cases, a slow, magnetoacoustic one. The entropy and Alfvén waves always remain in a usual homogeneous mode. (II For certain values of c_{p} and parameters of the discontinuity behind the front of the fast shock wave, there can be four slow magnetoacoustic waves, satisfying the dispersion equation, and none of the fast magnetoacoustic waves. In this case, one of the four slow magnetoacoustic waves is incident on the fast shock wave from the side of a compressed medium. It is shown that its existence does not contradict the conditions of the evolutionarity of MHD shock waves. The four slow magnetoacoustic waves, satisfying the dispersion equation, can also exist from either side of a slow shock wave or rotational discontinuity. (III The
A Floating Node Method for the Modelling of Discontinuities Within a Finite Element
Pinho, Silvestre T.; Chen, B. Y.; DeCarvalho, Nelson V.; Baiz, P. M.; Tay, T. E.
2013-01-01
This paper focuses on the accurate numerical representation of complex networks of evolving discontinuities in solids, with particular emphasis on cracks. The limitation of the standard finite element method (FEM) in approximating discontinuous solutions has motivated the development of re-meshing, smeared crack models, the eXtended Finite Element Method (XFEM) and the Phantom Node Method (PNM). We propose a new method which has some similarities to the PNM, but crucially: (i) does not introduce an error on the crack geometry when mapping to natural coordinates; (ii) does not require numerical integration over only part of a domain; (iii) can incorporate weak discontinuities and cohesive cracks more readily; (iv) is ideally suited for the representation of multiple and complex networks of (weak, strong and cohesive) discontinuities; (v) leads to the same solution as a finite element mesh where the discontinuity is represented explicitly; and (vi) is conceptually simpler than the PNM.
A gradient estimate for solutions to parabolic equations with discontinuous coefficients
Jishan Fan
2013-04-01
Full Text Available Li-Vogelius and Li-Nirenberg gave a gradient estimate for solutions of strongly elliptic equations and systems of divergence forms with piecewise smooth coefficients, respectively. The discontinuities of the coefficients are assumed to be given by manifolds of codimension 1, which we called them emph{manifolds of discontinuities}. Their gradient estimate is independent of the distances between manifolds of discontinuities. In this paper, we gave a parabolic version of their results. That is, we gave a gradient estimate for parabolic equations of divergence forms with piecewise smooth coefficients. The coefficients are assumed to be independent of time and their discontinuities are likewise the previous elliptic equations. As an application of this estimate, we also gave a pointwise gradient estimate for the fundamental solution of a parabolic operator with piecewise smooth coefficients. Both gradient estimates are independent of the distances between manifolds of discontinuities.
High Strength Discontinuously Reinforced Aluminum For Rocket Applications
Pandey, A. B.; Shah, S. R.; Shadoan, M.
2003-01-01
This study presents results on the development of a new aluminum alloy with very high strength and ductility. Five compositions of Al-Mg-Sc-Gd-Zr alloy were selected for this purpose. These alloys were also reinforced with 15 volume percent silicon-carbide and boron-carbide particles to produce Discontinuously Reinforced Aluminum (DRA) materials. Matrix alloys and DRA were processed using a powder metallurgy process. The helium gas atomization produced very fine powder with cellular-dentritic microstructure. The microstructure of matrix alloys showed fine Al3Sc based precipitate which provides significant strengthening in these alloys. DRA showed uniform distribution of reinforcement in aluminum matrix. DRA materials were tested at -320 F, 75 F in air and 7S F in gaseous hydrogen environments and matrix alloys were tested at 75 F in air. DRA showed high strengths in the range of 89-111 ksi (614-697 MPa) depending on alloy compositions and test environments. Matrix alloys had a good combination of strength, 84-89 ksi (579-621 MPa) and ductility, 4.5-6.5%. The properties of these materials can further be improved by proper control of processing parameters.
Dynamical properties of a dissipative discontinuous map: A scaling investigation
Aguilar-Sánchez, R. [Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla 72570 (Mexico); Leonel, Edson D. [Departamento de Física, UNESP – Univ. Estadual Paulista, Av. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Méndez-Bermúdez, J.A. [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, Puebla 72570 (Mexico)
2013-12-13
The effects of dissipation on the scaling properties of nonlinear discontinuous maps are investigated by analyzing the behavior of the average squared action 〈I{sup 2}〉 as a function of the n-th iteration of the map as well as the parameters K and γ, controlling nonlinearity and dissipation, respectively. We concentrate our efforts to study the case where the nonlinearity is large; i.e., K≫1. In this regime and for large initial action I{sub 0}≫K, we prove that dissipation produces an exponential decay for the average action 〈I〉. Also, for I{sub 0}≅0, we describe the behavior of 〈I{sup 2}〉 using a scaling function and analytically obtain critical exponents which are used to overlap different curves of 〈I{sup 2}〉 onto a universal plot. We complete our study with the analysis of the scaling properties of the deviation around the average action ω.
FORMULATIONS OF THE THREE-DIMENSIONAL DISCONTINUOUS DEFORMATION ANALYSIS METHOD
LIU Jun; KONG Xianjing; LIN Gao
2004-01-01
This paper extends the original 2D discontinuous deformation analysis (DDA) method proposed by Shi to 3D cases, and presents the formulations of the 3D DDA. The formulations maintain the characteristics of the original 2D DDA approach. Contacts between the blocks are detected by using Common-Plane (C-P) approach and the non-smooth contact, such as of vertex-to-vertex, vertex-to-edge and edge-to-edge types, can be handled easily based on the C-P method. The matrices of equilibrium equations have been given in detail for programming purposes. The C program codes for the 3D DDA are developed. The ability and accuracy of the formulations and the program are verified by the analytical solutions of several dynamic examples. The robustness and versatility of the algorithms presented in this paper are demonstrated with the aid of an example of scattering of densely packed cubes. Finally, implications and future extensions are discussed.
Coupled dipole plasmonics of nanoantennas in discontinuous, complex dielectric environments
Forcherio, Gregory T.; Blake, Phillip; Seeram, Manoj; DeJarnette, Drew; Roper, D. Keith
2015-11-01
Two-dimensional metamaterials support both plasmonic and coupled lattice (Fano) resonant modes that together could enhance optoelectronics. Descriptions for plasmon excitation in Fano resonant lattices in non-vacuum environments typically use idealized, homogeneous matrices due to computational expense and limitations of common approaches. This work described both localized and coupled resonance activity of two-dimensional, square lattices of gold (Au) nanospheres (NS) in discontinuous, complex dielectric media using compact synthesis of discrete and coupled dipole approximations. This multi-scale approach supported attribution of experimentally observed spectral resonance energy and bandwidth to interactions between metal and dielectric substrate(s) supporting the lattices. Effective polarizabilities of single AuNS, either in vacuo or supported by glass and/or indium tin oxide (ITO) substrates, were obtained with discrete dipole approximation (DDA). This showed plasmon energy transport varied with type of substrate: glass increased scattering, while ITO increased absorption and energy confinement. Far-field lattice interactions between AuNS with/without substrates were computed by coupled dipole approximation (CDA) using effective polarizabilities. This showed glass enhanced diffractive features (e.g., coupled lattice resonance), while ITO supported plasmon modes. This compact, multiscale approach to describe metasurfaces in complex environments could accelerate their development and application.
Certification of Discontinuous Composite Material Forms for Aircraft Structures
Arce, Michael Roger
New, high performance chopped, discontinuous, or short fiber composites (DFCs), DFCs, such as HexMC and Lytex, made by compression molding of randomly oriented pre-impregnated unidirectional tape, can be formed into complex geometry while retaining mechanical properties suitable for structural use. These DFCs provide the performance benefits of Continuous Fiber Composites (CFCs) in form factors that were previously unavailable. These materials demonstrate some notably different properties from continuous fiber composites, especially with respect to damage tolerance and failure behavior. These behaviors are not very well understood, and fundamental research efforts are ongoing to better characterize the material and to ease certification for future uses. Despite this, these new DFCs show such promise that they are already in service in the aerospace industry, for instance in the Boeing 787. Unfortunately, the relative novelty of these parts means that they needed to be certified by “point design”, an excess of physical testing, rather than by a mix of physical testing and finite element analysis, which would be the case for CFCs or metals. In this study, one particular approach to characterizing both linear-elastic and failure behaviors are considered. The Stochastic Laminate Analogy, which represents a novel approach to modeling DFCs, and its combination with a Ply Discount scheme. Owing to limited available computational resources, only preliminary results are available, but those results are quite promising and warrant further investigation.
On a Geometric Theory of Generalized Chiral Elasticity with Discontinuities
Suhendro I.
2008-01-01
Full Text Available In this work we develop, in a somewhat extensive manner, a geometric theory of chiral elasticity which in general is endowed with geometric discontinuities (sometimes referred to as defects. By itself, the present theory generalizes both Cosserat and void elasticity theories to a certain extent via geometrization as well as by taking intoaccount the action of the electromagnetic field, i.e., the incorporation of the electromagnetic field into the description of the so-called microspin (chirality also forms the underlying structure of this work. As we know, the description of the electromagnetic field as a unified phenomenon requires four-dimensional space-time rather than three-dimensional space as its background. For this reason we embed the three-dimensional material space in four-dimensional space-time. This way, the electromagnetic spin is coupled to the non-electromagnetic microspin, both being parts of the completemicrospin to be added to the macrospin in the full description of vorticity. In short, our objective is to generalize the existing continuum theories by especially describing microspin phenomena in a fully geometric way.
On a Geometric Theory of Generalized Chiral Elasticity with Discontinuities
Suhendro I.
2008-01-01
Full Text Available In this work we develop, in a somewhat extensive manner, a geometric theory of chiral elasticity which in general is endowed with geometric discontinuities (sometimes re- ferred to as defects . By itself, the present theory generalizes both Cosserat and void elasticity theories to a certain extent via geometrization as well as by taking into ac- count the action of the electromagnetic field, i.e., the incorporation of the electromag- netic field into the description of the so-called microspin ( chirality also forms the un- derlying structure of this work. As we know, the description of the electromagnetic field as a unified phenomenon requires four-dimensional space-time rather than three- dimensional space as its background. For this reason we embed the three-dimensional material space in four-dimensional space-time. This way, the electromagnetic spin is coupled to the non-electromagnetic microspin, both being parts of the complete mi- crospin to be added to the macrospin in the full description of vorticity. In short, our objective is to generalize the existing continuum theories by especially describing mi- crospin phenomena in a fully geometric way.
Three-dimensional shock wave diffraction off a discontinuous edge
Cooppan, S.; Skews, B.
2017-03-01
The interaction of three-dimensional vortex flows was investigated through vortex shedding off a discontinuous edge. Two wedges of 14.5° wedge angle (up and downstream edges) were separated by an offset. The size of the offset (5, 10, and 20 mm) and the Mach number (Mach 1.32, 1.42, and 1.6) were the key parameters investigated. Experimental images were taken and computational simulations were run; a close relation was found between the two. This enabled the three-dimensional effects of the flow to be studied and analysed. It was found, as the offset increased in size, the vortices shed off the up and downstream edges took a longer time to merge and the strength of the interaction was weaker. The vortex topology changed with a larger offset; the downstream vortex was thinner (in terms of cross-sectional diameter) adjacent to the offset, which is an indication of a change in density, than the rest of the vortex along the downstream diffraction edge. This particular feature was more prevalent at lower Mach numbers. The effect of a higher Mach number was to increase the rate of dissipation of the vortices, lengthen the shear layer due to the higher upstream velocity, and make the vortex profile elliptical.
Approximate solution for SPP with discontinuous source term
Adžić Nevenka
2004-01-01
Full Text Available In this paper we shall consider self-adjoint singularly perturbed problem described by the ordinary differential equation of second order with small parameter multiplying the highest derivative and discontinuous source term, and the appropriate boundary conditions, which describes steady state of certain flow problems. The solution displays both boundary layers and an interior layer. The domain decomposition will be performed determining layer subintervals which are adapted to polynomial approximation. The division points for the interior layer are determined by the procedure similar to the one for boundary layers using appropriate resemblance function. The solution out of boundary layer is approximated by the solution of the reduced problem, and the layer solutions is approximated by truncated orthogonal series giving a smooth approximate solution upon the entire interval. The coefficients of the truncated series are evaluated using pseudospectral technique. The rate of convergence is examined and the order-of-magnitude of the error is given, using the principle of inverse monotonicity and the behavior of the pseudospectral approximations. Numerical example is included and it shows the high accuracy of the presented method. .
Momentum balance in the shallow water equations on bottom discontinuities
Valiani, A.; Caleffi, V.
2017-02-01
This work investigates the topical problem of balancing the shallow water equations over bottom steps of different heights. The current approaches in the literature are essentially based on mathematical analysis of the hyperbolic system of balance equations and take into account the relevant progresses in treating the non-conservative form of the governing system in the framework of path-conservative schemes. An important problem under debate is the correct position of the momentum balance closure when the bottom elevation is discontinuous. Cases of technical interest are systematically analysed, consisting of backward-facing steps and forward-facing steps, tackled supercritical and subcritical flows; critical (sonic) conditions are also analysed and discussed. The fundamental concept governing the problem and supported by the present computations is that the energy-conserving approach is the only approach that is consistent with the classical shallow water equations formulated with geometrical source terms and that the momentum balance is properly closed if a proper choice of a conventional depth on the bottom step is performed. The depth on the step is shown to be included between the depths just upstream and just downstream of the step. It is also shown that current choices (as given in the literature) of the depth on (or in front of) the step can lead to unphysical configurations, similar to some energy-increasing solutions.
Regional wave propagation using the discontinuous Galerkin method
S. Wenk
2013-01-01
Full Text Available We present an application of the discontinuous Galerkin (DG method to regional wave propagation. The method makes use of unstructured tetrahedral meshes, combined with a time integration scheme solving the arbitrary high-order derivative (ADER Riemann problem. This ADER-DG method is high-order accurate in space and time, beneficial for reliable simulations of high-frequency wavefields over long propagation distances. Due to the ease with which tetrahedral grids can be adapted to complex geometries, undulating topography of the Earth's surface and interior interfaces can be readily implemented in the computational domain. The ADER-DG method is benchmarked for the accurate radiation of elastic waves excited by an explosive and a shear dislocation source. We compare real data measurements with synthetics of the 2009 L'Aquila event (central Italy. We take advantage of the geometrical flexibility of the approach to generate a European model composed of the 3-D EPcrust model, combined with the depth-dependent ak135 velocity model in the upper mantle. The results confirm the applicability of the ADER-DG method for regional scale earthquake simulations, which provides an alternative to existing methodologies.
Regional wave propagation using the discontinuous Galerkin method
S. Wenk
2012-08-01
Full Text Available We present an application of the discontinuous Galerkin (DG method to regional wave propagation. The method makes use of unstructured tetrahedral meshes, combined with a time integration scheme solving the arbitrary high-order derivative (ADER Riemann problem. The ADER-DG method is high-order accurate in space and time, beneficial for reliable simulations of high-frequency wavefields over long propagation distances. Due to the ease with which tetrahedral grids can be adapted to complex geometries, undulating topography of the Earth's surface and interior interfaces can be readily implemented in the computational domain. The ADER-DG method is benchmarked for the accurate radiation of elastic waves excited by an explosive and a shear dislocation source. We compare real data measurements with synthetics of the 2009 L'Aquila event (central Italy. We take advantage of the geometrical flexibility of the approach to generate a European model composed of the 3-D EPcrust model, combined with the depth-dependent ak135 velocity model in the upper-mantle. The results confirm the applicability of the ADER-DG method for regional scale earthquake simulations, which provides an alternative to existing methodologies.
Emergence of phenotype switching through continuous and discontinuous evolutionary transitions
Patra, Pintu; Klumpp, Stefan
2015-07-01
Bacterial persistence (phenotypic tolerance to antibiotics) provides a prime example of bet-hedging, where normally growing cells generate slow-growing but antibiotic-tolerant persister cells to survive through periods of exposure to antibiotics. The population dynamics of persistence is explained by a phenotype switching mechanism that allows individual cells to switch between these different cellular states with different environmental sensitivities. Here, we perform a theoretical study based on an exact solution for the case of a periodic variation of the environment to address how phenotype switching emerges and under what conditions switching is or is not beneficial for long-time growth. Specifically we report a bifurcation through which a fitness maximum and minimum emerge above a threshold in the duration of exposure to the antibiotic. Only above this threshold, the optimal phenotype switching rates are adjusted to the time scales of the environment, as emphasized by previous theoretical studies, while below the threshold a non-switching population is fitter than a switching one. The bifurcation can be of different type, depending on how the phenotype switching rates are allowed to vary. If the switching rates for both directions of the switch are coupled, the transition is discontinuous and results in evolutionary hysteresis, which we confirm with a stochastic simulation. If the switching rates vary individually, a continuous transition is obtained and no hysteresis is found. We discuss how both scenarios can be linked to changes in the underlying molecular networks.
Organic and organo-mineral colloids in discontinuous permafrost zone
Pokrovsky, Oleg S.; Manasypov, Rinat M.; Loiko, Sergey V.; Shirokova, Liudmila S.
2016-09-01
On-going permafrost thaw in discontinuous permafrost regions produces significant amounts of small permafrost subsidence and depressions, while large lakes are likely to drain into streams and rivers. The intensification of permafrost thaw may alter the size distribution and chemical composition of organo-Fe-Al colloids in lakes and rivers. We used a continuum of surface water bodies, from permafrost subsidence, small depressions and thaw ponds to large lakes and rivers that drain the Western Siberia Lowland (WSL), to assess OC, major and the trace element size distribution between the 20-μm, 5-μm, 1.2-μm, 0.45-μm, 0.22-μm, 0.025-μm and 1-kDa (∼1.4 nm) size fractions. This approach allowed us to distinguish the organic and organo-ferric colloids that were responsible for the transport of trace elements in surface waters and address their evolution during possible physico-chemical and biological processes. Both conventionally dissolved (alkaline earth elements and several micronutrients (Zn, Ba, Mn, and Ni), decreased the degree of their binding to DOM along the landscape continuum, whereas the majority of insoluble TEs (Al, Fe, Co, Cd, Cu, Pb, REEs, Th, and U) remained complexed with DOM in the LMWsoil to rivers will increase.
Properties of Discontinuous Galerkin Algorithms and Implications for Edge Gyrokinetics
Hammett, G. W.; Hakim, A.; Shi, E. L.; Abel, I. G.; Stoltzfus-Dueck, T.
2015-11-01
The continuum gyrokinetic code Gkeyll uses Discontinuous Galerkin (DG) algorithms, which have a lot of flexibility in the choice of basis functions and inner product norm that can be useful in designing algorithms for particular problems. Rather than use regular polynomial basis functions, we consider here Maxwellian-weighted basis functions (which have similarities to Gaussian radial basis functions). The standard Galerkin approach loses particle and energy conservation, but this can be restored with a particular weight for the inner product (this is equivalent to a Petrov-Galerkin method). This allows a full- F code to have some benefits similar to the Gaussian quadrature used in gyrokinetic δf codes to integrate Gaussians times some polynomials exactly. In tests of Gkeyll for electromagnetic fluctuations, we found it is important to use consistent basis functions where the potential is in a higher-order continuity subspace of the space for the vector potential A| |. A regular projection method to this subspace is a non-local operation, while we show a self-adjoint averaging operator that can preserve locality and energy conservation. This does not introduce damping, but like gyro-averaging involves only the reactive part of the dynamics. Supported by the Max-Planck/Princeton Center for Plasma Physics, the SciDAC Center for the Study of Plasma Microturbulence, and DOE Contract DE-AC02-09CH11466.
The price sensitivity of Medicare beneficiaries: a regression discontinuity approach.
Buchmueller, Thomas C; Grazier, Kyle; Hirth, Richard A; Okeke, Edward N
2013-01-01
We use 4 years of data from the retiree health benefits program of the University of Michigan to estimate the effect of price on the health plan choices of Medicare beneficiaries. During the period of our analysis, changes in the University's premium contribution rules led to substantial price changes. A key feature of this 'natural experiment' is that individuals who had retired before a certain date were exempted from having to pay any premium contributions. This 'grandfathering' creates quasi-experimental variation that is ideal for estimating the effect of price. Using regression discontinuity methods, we compare the plan choices of individuals who retired just after the grandfathering cutoff date and were therefore exposed to significant price changes to the choices of a 'control group' of individuals who retired just before that date and therefore did not experience the price changes. The results indicate a statistically significant effect of price, with a $10 increase in monthly premium contributions leading to a 2 to 3 percentage point decrease in a plan's market share. Copyright © 2012 John Wiley & Sons, Ltd.
Multi-slicing strategy for the three-dimensional discontinuity layout optimization (3D DLO).
Zhang, Yiming
2017-03-01
Discontinuity layout optimization (DLO) is a recently presented topology optimization method for determining the critical layout of discontinuities and the associated upper bound limit load for plane two-dimensional and three-dimensional (3D) problems. The modelling process (pre-processing) for DLO includes defining the discontinuities inside a specified domain and building the target function and the global constraint matrix for the optimization solver, which has great influence on the the efficiency of the computation processes and the reliability of the final results. This paper focuses on efficient and reliable pre-processing of the discontinuities within the 3D DLO and presents a multi-slicing strategy, which naturally avoids the overlapping and crossing of different discontinuities. Furthermore, the formulation of the 3D discontinuity considering a shape of an arbitrary convex polygon is introduced, permitting the efficient assembly of the global constraint matrix. The proposed method eliminates unnecessary discontinuities in 3D DLO, making it possible to apply 3D DLO for solving large-scale engineering problems such as those involving landslides. Numerical examples including a footing test, a 3D landslide and a punch indentation are considered, illustrating the effectiveness of the presented method. © 2016 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd.
A global finite-element shallow-water model supporting continuous and discontinuous elements
P. A. Ullrich
2014-08-01
Full Text Available This paper presents a novel nodal finite element method for either continuous and discontinuous elements, as applied to the 2-D shallow-water equations on the cubed-sphere. The cornerstone of this method is the construction of a robust derivative operator which can be applied to compute discrete derivatives even over a discontinuous function space. A key advantage of the robust derivative is that it can be applied to partial differential equations in either conservative or non-conservative form. However, it is also shown that discontinuous penalization is required to recover the correct order of accuracy for discontinuous elements. Two versions with discontinuous elements are examined, using either the g1 and g2 flux correction function for distribution of boundary fluxes and penalty across nodal points. Scalar and vector hyperviscosity operators valid for both continuous and discontinuous elements are also derived for stabilization and removal of grid-scale noise. This method is validated using three standard shallow-water test cases, including geostrophically balanced flow, a mountain-induced Rossby wave train and a barotropic instability. The results show that although the discontinuous basis requires a smaller time step size than that required for continuous elements, the method exhibits better stability and accuracy properties in the absence of hyperviscosity.
Zhang, X.; Burgstaller, R.; Lai, X.; Gehrer, A.; Kefalas, A.; Pang, Y.
2016-11-01
The performance discontinuity of a pump-turbine under pumping mode is harmful to stable operation of units in hydropower station. In this paper, the performance discontinuity phenomenon of the pump-turbine was studied by means of experiment and numerical simulation. In the experiment, characteristics of the pump-turbine with different diffuser vane openings were tested in order to investigate the effect of pumping casing to the performance discontinuity. While other effects such as flow separation and rotating stall are known to have an effect on the discontinuity, the present studied test cases show that prerotation is the dominating effect for the instability, positions of the positive slope of characteristics are almost the same in different diffuser vane opening conditions. The impeller has principal effect to the performance discontinuity. In the numerical simulation, CFD analysis of tested pump-turbine has been done with k-ω and SST turbulence model. It is found that the position of performance curve discontinuity corresponds to flow recirculation at impeller inlet. Flow recirculation at impeller inlet is the cause of the discontinuity of characteristics curve. It is also found that the operating condition of occurrence of flow recirculation at impeller inlet is misestimated with k-ω and SST turbulence model. Furthermore, the original SST model has been modified. We predict the occurrence position of flow recirculation at impeller inlet correctly with the modified SST turbulence model, and it also can improve the prediction accuracy of the pump- turbine performance at the same time.
Serasa, Ailie Sofyiana; Lai, Goh Thian; Rafek, Abdul Ghani; Simon, Norbert; Hussein, Azimah; Ern, Lee Khai; Surip, Noraini; Mohamed, Tuan Rusli
2016-11-01
The significant influence of surface roughness of discontinuity surfaces is a quantity that is fundamental to the understanding of shear strength of geological discontinuities. This is due to reason that the shear strength of geological discontinuities greatly influenced the mechanical behavior of a rock mass especially in stability evaluation of tunnel, foundation, and natural slopes. In evaluating the stability of these structures, the study of peak friction angle (Φpeak) of rough discontinuity surfaces has become more prominent seeing that the shear strength is a pivotal factor causing failures. The measurement of peak friction angle however, requires an extensive series of laboratory tests which are both time and cost demanding. With that in mind, this publication presents an approach in the form of an experimentally determined polynomial equation to estimate peak friction angle of limestone discontinuity surfaces by measuring the Joint Roughness Coefficient (JRC) values from tilt tests, and applying the fore mentioned empirical correlation. A total of 1967 tilt tests and JRC measurements were conducted in the laboratory to determine the peak friction angles of rough limestone discontinuity surfaces. A polynomial equation of ɸpeak = -0.0635JRC2 + 3.95JRC + 25.2 that exhibited 0.99 coefficient of determination (R2) were obtained from the correlation of JRC and peak friction angles. The proposed correlation offers a practical method for estimation of peak friction angles of rough discontinuity surfaces of limestone from measurement of JRC in the field.
Continuous, saturation, and discontinuous tokamak plasma vertical position control systems
Mitrishkin, Yuri V., E-mail: y_mitrishkin@hotmail.com [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow 119991 (Russian Federation); Pavlova, Evgeniia A., E-mail: janerigoler@mail.ru [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow 119991 (Russian Federation); Kuznetsov, Evgenii A., E-mail: ea.kuznetsov@mail.ru [Troitsk Institute for Innovation and Fusion Research, Moscow 142190 (Russian Federation); Gaydamaka, Kirill I., E-mail: k.gaydamaka@gmail.com [V. A. Trapeznikov Institute of Control Sciences of the Russian Academy of Sciences, Moscow 117997 (Russian Federation)
2016-10-15
Highlights: • Robust new linear state feedback control system for tokamak plasma vertical position. • Plasma vertical position relay control system with voltage inverter in sliding mode. • Design of full models of multiphase rectifier and voltage inverter. • First-order unit approximation of full multiphase rectifier model with high accuracy. • Wider range of unstable plant parameters of stable control system with multiphase rectifier. - Abstract: This paper is devoted to the design and comparison of unstable plasma vertical position control systems in the T-15 tokamak with the application of two types of actuators: a multiphase thyristor rectifier and a transistor voltage inverter. An unstable dynamic element obtained by the identification of plasma-physical DINA code was used as the plasma model. The simplest static feedback state space control law was synthesized as a linear combination of signals accessible to physical measurements, namely the plasma vertical displacement, the current, and the voltage in a horizontal field coil, to solve the pole placement problem for a closed-loop system. Only one system distinctive parameter was used to optimize the performance of the feedback system, viz., a multiple real pole. A first-order inertial unit was used as the rectifier model in the feedback. A system with a complete rectifier model was investigated as well. A system with the voltage inverter model and static linear controller was brought into a sliding mode. As this takes place, real time delays were taken into account in the discontinuous voltage inverter model. The comparison of the linear and sliding mode systems showed that the linear system enjoyed an essentially wider range of the plant model parameters where the feedback system was stable.
Neonatal Discontinuation Syndrome in Serotonergic Antidepressant-Exposed Neonates.
Yang, Amy; Ciolino, Jody D; Pinheiro, Emily; Rasmussen-Torvik, Laura J; Sit, Dorothy K Y; Wisner, Katherine L
2017-05-01
To determine whether infants exposed in utero to serotonin reuptake inhibitor (SRI) antidepressants or a DSM-IV-TR-defined mood disorder have significantly more neonatal discontinuation signs compared to an unexposed group of infants at 2-4 weeks after birth. This secondary analysis was derived from 2 observational studies with enrollment from July 2000 to December 2011 in Cleveland, Ohio, and Pittsburgh, Pennsylvania. Mothers (n = 214) belonged to one of 3 groups based on exposure status during pregnancy: (1) Comparison-women who did not take psychotropics during pregnancy and had no major mood disorder; (2) SRI-exposed-women with a mood disorder who were taking an SRI but no benzodiazepines; and (3) Mood Disorder-women with depression or bipolar disorder who did not take psychotropic medications. The infants were examined for signs according to the Finnegan Scale by evaluators blind to maternal exposure status. The rates of sign presence (defined as a score ≥ 2 on the Finnegan Scale) in the SRI, Mood Disorder, and Comparison groups were similar at 34.1%, 35.1%, and 30.4%, respectively. Women in the SRI group had a significantly higher preterm birth rate (24.4%) compared to the other 2 groups (7.4% and 8.9% in the Mood Disorder and Comparison groups, respectively; P = .012). Preterm newborns had a significantly higher sign rate compared to full-term newborns (54% vs 31%, P = .020). We observed a significant relationship between Finnegan signs and preterm birth. The presence of neonatal signs at 2-4 weeks was more closely associated with prematurity than with in utero SRI or mood disorder exposure. ClinicalTrials.gov identifiers: NCT00279370 and NCT00585702.
The Discontinuity Circa 1885 in the Group Sunspot Number
Cliver, E. W.; Ling, A. G.
2016-11-01
On average, the international sunspot number (RI) is 44 % higher than the group sunspot number (RG) from 1885 to the beginning of the RI series in 1700. This is the principal difference between RI and RG. Here we show that this difference is primarily due to an inhomogeneity in the Royal Greenwich Observatory (RGO) record of sunspot groups (1874 - 1976) used to derive observer normalization factors (called k-factors) for RG. Specifically, annual RGO group counts increase relative to those of Wolfer and other long-term observers from 1876 - 1915. A secondary contributing cause is that the k-factors for observers who began observing before 1884 and overlapped with RGO for any years during 1874 - 1883 were not based on direct comparison with RGO but were calculated using one or more intermediary or additional observers. We introduce R_{GC} by rectifying the RGO group counts from 1874 - 1915 and basing k-factors on direct comparison with RGO across the 1885 discontinuity, which brings the RG and RI series into reasonable agreement for the 1841 - 1885 interval (after correcting RI for an inhomogeneity from 1849 - 1867 (to give R_{IC})). Comparison with an independently derived backbone-based reconstruction of RG (R_{BB}) indicates that R_{GC} over-corrects R_{BB} by 4 % on average from 1841 - 1925. Our analysis suggests that the maxima of Cycles 10 (in 1860), 12 (1883/1884), and 13 (1893) in the R_{IC} series are too low by ≈ 10 %.
Bluethmann, Shirley M; Alfano, Catherine M; Clapp, Jonathan D; Luta, George; Small, Brent J; Hurria, Arti; Cohen, Harvey J; Sugarman, Steven; B Muss, Hyman; Isaacs, Claudine; Mandelblatt, Jeanne S
2017-06-26
To investigate the effects of cognitive function on discontinuation of hormonal therapy in breast cancer survivors ages 65+ ("older"). Older breast cancer survivors with invasive, non-metastatic disease, and no reported cognitive difficulties were recruited from 78 Alliance sites between 2004 and 2011. Eligible survivors (n = 1280) completed baseline interviews; follow-up was conducted annually for up to 7 years. Survivors with estrogen-receptor-positive (ER+) cancers who initiated hormonal therapy (n = 990) were included. Self-reported cognitive function was measured using the EORTC-QLQ30 scale; a difference of eight points on the 0-100 scale was considered clinically significant. Based on varying rates of discontinuation over time, discontinuation was evaluated separately for three time periods: early (3-5 years). Cox models for each time period were used to evaluate the effects of cognition immediately preceding discontinuation, controlling for age, chemotherapy, and other covariates. Survivors were 65-91 years old (mean 72.6 years), and 79% had stages 1 or 2A disease. Overall, 43% discontinued hormonal therapy before 5 years. Survivors who reported lower cognitive function in the period before discontinuation had greater hazards of discontinuing therapy at the treatment midpoint (HR 1.22 per 8-point difference, CI 1.09-1.40, p cognition was not related to discontinuation in the other periods. Self-reported cognitive problems were a significant risk factor for discontinuation of hormonal therapy 1-3 years post-initiation. Additional research is needed on the temporality of cognitive effects and hormonal therapy to support survivorship care needs of older survivors.
Upper mantle seismic discontinuities in the area of the Indian Ocean Geoid Low
Reiss, Anne-Sophie; van Driel, Jac; Heyn, Björn; Thomas, Christine
2017-04-01
We are investigating the upper mantle seismic discontinuities at 410 and 660 km depth beneath the southern tip of India, where the Indian Ocean Geoid Low (IOGL) is located. We use PP and SS waves and their precursors, which reflect off the underside of these seismic discontinuities midway between source and receiver, to map the topography of the two discontinuities bounding the mantle transition zone. Our dataset consists of 9604 events with magnitude 5.8 or higher recorded at 57 different arrays distributed around the Indian Ocean. This results in a dense coverage of reflection points across our area of interest. 599 events out of this dataset show a good PP or SS signal. To enhance the signal-to-noise-ratio for better visibility of the weak precursor signals and to identify out-of-plane arrivals we use array seismology methods. We obtain the depth of the discontinuities by measuring the differential travel time between the main phase and the precursor signal, comparing it with theoretical travel times through the 1D reference Earth model ak135 and correcting the measured travel times for crustal and tomographic features. Most of the signals we observe reflect off the 410 km discontinuity, which is caused by the solid-solid phase transition from olivine to wadsleyite. The 660 km discontinuity, which exists due to the phase transformation from ringwoodite to bridgmanite and magnesiowustite, also causes some visible reflections in our dataset. Besides those two discontinuities we also see few reflections both from shallower and deeper structure. The best quality data show a deepened 410 in the centre of the IOGL as well as an overall elevated 660 km discontinuity. The combined observation of the IOGL, its sensitivity kernel and the behaviour of the mantle transition zone seismic discontinuities can be interpreted as a hot upwelling that currently resides in the mantle transition zone.
[Comment on “Seismology in the days of old” by Inge Lehmann] The Lehmann discontinuity
Anderson, D. L.; Bolt, B. A.; Morse, S. A.
Recent reflections by Inge Lehmann on her discovery of the inner core (Eos, January 20, 1987, p. 33; see also Bolt [1987, 1982]) remind us that this outstanding Earth scientist is now in her 100th year. The inner core boundary (ICB) is one of the three great seismic-compositional discontinuities that divide Earth into crust, mantle, core, and inner core. The other two discontinuities are well known by names honoring their discoverers, Andrija Mohorovicic and Beno Gutenberg. In this tradition, it is fitting that the ICB be called the Lehmann Discontinuity in honor of its discoverer.
Increased frequency of first-episode poststroke depression after discontinuation of escitalopram.
Mikami, Katsunaka; Jorge, Ricardo E; Moser, David J; Arndt, Stephan; Jang, Mijin; Solodkin, Ana; Small, Steven L; Fonzetti, Pasquale; Hegel, Mark T; Robinson, Robert G
2011-11-01
The purpose of this study was to compare escitalopram, problem-solving therapy, and placebo to prevent poststroke depression during 6 months after discontinuation of treatment. We examined for depression 33 patients assigned to placebo, 34 to escitalopram, and 41 to problem-solving therapy. After controlling for age, gender, prior mood disorder, and severity of stroke, new-onset major depression and Hamilton Depression scores were significantly higher 6 months after escitalopram was discontinued compared with the problem-solving therapy or placebo groups. Discontinuation of escitalopram may increase poststroke depressive symptoms.
Increased frequency of first episode poststroke depression following discontinuation of escitalopram
Mikami, Katsunaka; Jorge, Ricardo E.; Moser, David J.; Arndt, Stephan; Jang, Mijin; Solodkin, Ana; Small, Steven L.; Fonzetti, Pasquale; Hegel, Mark T.; Robinson, Robert G.
2011-01-01
Background and Purpose To compare escitalopram, problem-solving therapy (PST), and placebo, to prevent poststroke depression during 6 months after discontinuation of treatment. Methods We examined for depression, 33 patients assigned to placebo, 34 to escitalopram, and 41 to PST. Results After controlling for age, gender, prior mood disorder, and severity of stroke, new onset major depression and Hamilton Depression scores were significantly higher 6 months after escitalopram was discontinued, compared to the PST or placebo groups. Conclusions Discontinuation of escitalopram may increase poststroke depressive symptoms. PMID:21868736
Sirenko, Kostyantyn
2014-07-01
Discontinuous Galerkin time-domain method (DGTD) has been used extensively in computational electromagnetics for analyzing transient electromagnetic wave interactions on structures described with linear constitutive relations. DGTD expands unknown fields independently on disconnected mesh elements and uses numerical flux to realize information exchange between fields on different elements (J. S. Hesthaven and T. Warburton, Nodal Discontinuous Galerkin Method, 2008). The numerical flux of choice for \\'linear\\' Maxwell equations is the upwind flux, which mimics accurately the physical behavior of electromagnetic waves on discontinuous boundaries. It is obtained from the analytical solution of the Riemann problem defined on the boundary of two neighboring mesh elements.
Kolmogorov, Dmitry; Sørensen, Niels N.; Shen, Wen Zhong
2013-01-01
An Optimized Schwarz method using Robin boundary conditions for relaxation scheme is presented in the frame of Multigrid method on discontinuous grids. At each iteration the relaxation scheme is performed in two steps: one step with Dirichlet and another step with Robin boundary conditions at inner...... block boundaries. A Robin parameter that depends on grid geometry and grid discontinuity at block interfaces is introduced. The general solution algorithm is based on SIMPLE method and a conservative _nite-volume scheme on block-structured grids with discontinuous interfaces. The multigrid method...
Dias-da-Costa, D.; Alfaiate, J.; Sluys, L.J.; Julio, E.
2009-01-01
In this paper, three different approaches used to model strong discontinuities are studied: a new strong embedded discontinuity technique, designated as the discrete strong embedded discontinuity approach (DSDA), introduced in Dias-da-Costa et al. (Eng Fract Mech 76(9):1176–1201, 2009); the generali
Dias-da-Costa, D.; Alfaiate, J.; Sluys, L.J.; Julio, E.
2009-01-01
In this paper, three different approaches used to model strong discontinuities are studied: a new strong embedded discontinuity technique, designated as the discrete strong embedded discontinuity approach (DSDA), introduced in Dias-da-Costa et al. (Eng Fract Mech 76(9):1176–1201, 2009); the
Toughening mechanisms in discontinuous glass/polypropylene composites
Williams, Eunethia Denise
1997-08-01
There are five energy absorbing mechanisms for discontinuous fiber reinforced composites. These include fiber debonding, fiber pullout/bridging, fiber breakage, matrix cracking and matrix deformation. Because of the typically random orientation of fibers in these systems, it has been difficult to develop an experimental approach to determine which of these contributions dominate the measured in-plane toughness values. To address this issue, a specimen has been developed of one pultruded sheet of polypropylene-glass longitudinally centered in a compression molded polypropylene bar. Experimentally, interface strength was varied from weak to intermediate to strong adhesion through the addition of different sizings and maleic anhydride grafted polypropylene. The pullout contribution was determined through varying fiber length. Matrix contributions were determined by changing the molecular weight of the matrix and by changing the crystal structure from predominantly the alpha form to the beta form. Experiments of Izod testing have shown that impact strength is maximized in specimens with a weak interface at an optimum fiber length corresponding to the fiber length at which pullout predominates. In specimens with an intermediate strength interface, impact strength showed a maximum but was reduced. In specimens with a strong interface, impact strength was the lowest and fairly level. Experiments of tensile testing also showed maximum toughness in specimens with a weak interface with an optimum fiber length where pull out predominates. In specimens with a strong interface, tensile toughness was reduced. Examination of these specimens suggests that the impact strength is maximized by the density via the crystallinity of the resin. The density influences the volume contraction of the matrix around the fibers during cooling. This volume contraction creates a radial stress on the fibers that affects the frictional shear stress against which the fibers are pulled out during
Vertically Discontinuous Seismic Signatures From Continuous Thermochemical Plumes
Harris, A. C.; Kincaid, C.; Savage, B.
2008-12-01
, which appears slow for all compositions in a hot plume. Complex seismic signatures are predicted for mantle upwellings forming from source regions containing oceanic lithosphere, including strong variations in velocity with depth. Strong thermal signatures above 300km may be masked by compositional effects below 300km. Results predict that a vertically continuous upwelling will give a spatially discontinuous seismic result.
Continuity Conditions on Schrodinger Wave Functions at Discontinuities of the Potential.
Branson, David
1979-01-01
Several standard arguments which attempt to show that the wave function and its derivative must be continuous across jump discontinuities of the potential are reviewed and their defects discussed. (Author/HM)
Periodic Orbits in a Second-Order Discontinuous System with an Elliptic Boundary
Li, Liping; Luo, Albert C. J.
2016-12-01
This paper develops the analytical conditions for the onset and disappearance of motion passability and sliding along an elliptic boundary in a second-order discontinuous system. A periodically forced system, described by two different linear subsystems, is considered mainly to demonstrate the methodology. The passable, sliding and grazing conditions of a flow to the elliptic boundary in the discontinuous dynamical system are provided through the analysis of the corresponding vector fields and G-functions. Moreover, by constructing appropriate generic mappings, periodic orbits in such a discontinuous system are predicted analytically. Finally, three different cases are discussed to illustrate the existence of periodic orbits with passable and/or sliding flows. The results obtained in this paper can be applied to the sliding mode control in discontinuous dynamical systems.
A numerical procedure for geochemical compaction in the presence of discontinuous reactions
Agosti, Abramo; Giovanardi, Bianca; Formaggia, Luca; Scotti, Anna
2016-08-01
The process by which rocks are formed from the burial of a fresh sediment involves the coupled effects of mechanical compaction and geochemical reactions. Both of them affect the porosity and permeability of the rock and, in particular, geochemical reactions can significantly alter them, since dissolution and precipitation processes may cause a structural transformation of the solid matrix. Often, the differential problems that arise from the modeling of these chemical reactions may present a discontinuous right hand side, where the discontinuity depends on the solution itself. In this work we have developed a numerical model to simulate this complex multi-physics problem by treating the discontinuous right hand side with a specially tailored event-driven numerical scheme. We show the performance of this strategy in terms of positivity and mass conservation, also in comparison with a more traditional approach that relies on a regularization of the discontinuous terms.
Implementation of the entropy viscosity method with the discontinuous Galerkin method
Zingan, Valentin
2013-01-01
The notion of entropy viscosity method introduced in Guermond and Pasquetti [21] is extended to the discontinuous Galerkin framework for scalar conservation laws and the compressible Euler equations. © 2012 Elsevier B.V.
Bretler, Ditte-Marie; Hansen, P. R.; Abildstrom, S. Z.
2011-01-01
center dot General use of hormone replacement therapy (HRT) dropped drastically after 2002 when pivotal randomized trials showed increased risk of coronary artery disease and other complications with HRT. center dot HRT is not recommended for primary or secondary prevention of coronary heart...... disease and guidelines recommend discontinuation of HRT after myocardial infarction (MI). center dot It is unknown whether women actually discontinue HRT after MI. WHAT THIS STUDY ADDS center dot Women who use HRT when they experience their MI generally continue using HRT. center dot We found a remarkably...... low increase in discontinuation after 2002, in contrast to the general drop in use of HRT. AIM To characterize the pattern of use and discontinuation of postmenopausal hormone replacement therapy (HRT) in women with myocardial infarction (MI) before and after 2002, where the general use of HRT dropped...
Beeftink, Martine M.A.; Van Der Sande, Nicolette G.C.; Bots, Michiel L.; Doevendans, Pieter A.; Blankestijn, Peter J.; Visseren, Frank L.J.; Voskuil, Michiel; Spiering, Wilko
2017-01-01
Successful control of blood pressure relies on identification of secondary causes and contributing factors of hypertension. As antihypertensive medication can interfere with diagnostic investigations, temporary discontinuation of medication is advised. However, there are concerns about the safety of
Discontinuous Galerkin finite element methods for radiative transfer in spherical symmetry
Kitzmann, D; Patzer, A B C
2016-01-01
The discontinuous Galerkin finite element method (DG-FEM) is successfully applied to treat a broad variety of transport problems numerically. In this work, we use the full capacity of the DG-FEM to solve the radiative transfer equation in spherical symmetry. We present a discontinuous Galerkin method to directly solve the spherically-symmetric radiative transfer equation as a two-dimensional problem. The transport equation in spherical atmospheres is more complicated than in the plane-parallel case due to the appearance of an additional derivative with respect to the polar angle. The DG-FEM formalism allows for the exact integration of arbitrarily complex scattering phase functions, independent of the angular mesh resolution. We show that the discontinuous Galerkin method is able to describe accurately the radiative transfer in extended atmospheres and to capture discontinuities or complex scattering behaviour which might be present in the solution of certain radiative transfer tasks and can, therefore, cause...
Predictor-Corrector LU-SGS Discontinuous Galerkin Finite Element Method for Conservation Laws
Ma, Xinrong; Liu, Sanyang; Xie, Gongnan
2015-01-01
Efficient implicit predictor-corrector LU-SGS discontinuous Galerkin (DG) approach for compressible Euler equations on unstructured grids is investigated by adding the error compensation of high-order term...
Yoshida, Kazuki; Radner, Helga; Kavanaugh, Arthur; Sung, Yoon-Kyoung; Bae, Sang-Cheol; Kishimoto, Mitsumasa; Matsui, Kazuo; Okada, Masato; Tohma, Shigeto; Weinblatt, Michael E.; Solomon, Daniel H.
2016-01-01
Many biologic disease-modifying antirheumatic drug (DMARD) discontinuation studies have been conducted, but mainly in trial settings which result in limited generalizability. Registry studies can complement the current literature of biologic DMARD discontinuation by providing more generalizable information. However, registries may need to be combined to increase power and provide a more diverse patient population. This increased power could provide us information about risk and benefits of discontinuing biologic DMARD in typical clinical practice. However, use of multiple registries is not without challenges. In this review, we discuss the challenges to combining data across multiple registries, focusing on biologic discontinuation as an example. Challenges include: 1) generalizability of each registry; 2) new versus prevalent users designs; 3) outcome definitions; 4) different health care systems; 5) different follow up intervals; and 6) data harmonization. The first three apply to each registry, and the last three apply to combining multiple registries. This review describes these challenges, corresponding solutions, and potential future opportunities. PMID:24129133
Property-Property relations: 22 degree and 9 degree discontinuities in the Arabian Sea
Somasundar, K.; Rajendran, A.; DileepKumar, M.
Property-property relations, mostly of conservative chemical parameters, are used in this attempt in tracing various discontinuities in the Arabian Sea and to reveal in situ processes together with potential temperature-salinity plots. Plots...
Finite-time stabilization control for discontinuous time-delayed networks: New switching design.
Zhang, Ling-Ling; Huang, Li-Hong; Cai, Zuo-Wei
2016-03-01
This paper discusses the finite-time stabilization problem for time-varying delayed neural networks (DNNs) with discontinuous activation functions. By using fixed point theory and set-valued analysis, we establish the existence theorem of equilibrium point. In order to stabilize the states of this class of discontinuous DNNs in finite time, we design two different kinds of switching controllers which are described by discontinuous functions. Under the framework of Filippov solutions, several new and effective criteria are derived to realize finite-time stabilization of discontinuous DNNs based on the famous finite-time stability theory. Besides, the upper bounds of the settling time of stabilization are estimated. Numerical examples are finally provided to illustrate the correctness of the proposed design method and theoretical results.
A new method for automatic discontinuity traces sampling on rock mass 3D model
Umili, G.; Ferrero, A.; Einstein, H. H.
2013-02-01
A new automatic method for discontinuity traces mapping and sampling on a rock mass digital model is described in this work. The implemented procedure allows one to automatically identify discontinuity traces on a Digital Surface Model: traces are detected directly as surface breaklines, by means of maximum and minimum principal curvature values of the vertices that constitute the model surface. Color influence and user errors, that usually characterize the trace mapping on images, are eliminated. Also trace sampling procedures based on circular windows and circular scanlines have been implemented: they are used to infer trace data and to calculate values of mean trace length, expected discontinuity diameter and intensity of rock discontinuities. The method is tested on a case study: results obtained applying the automatic procedure on the DSM of a rock face are compared to those obtained performing a manual sampling on the orthophotograph of the same rock face.
Stage, Tore Bjerregaard; Lee, Moa P; Hallas, Jesper;
2016-01-01
The aim of this study was to examine the risk of early discontinuation of metformin as a proxy for intolerance, associated with use of drugs known to inhibit transporters involved in metformin distribution. We analysed all incident users of metformin in Denmark between 2000 and 2012 (n = 132......,221) and in a cohort of US patients (n = 296,903). Risk of early discontinuation of metformin was assessed using adjusted logistic regression for 28 drugs putatively inhibiting metformin transporters and four negative controls. Increased odds ratio of early discontinuation of metformin was only associated with codeine...... drugs were associated with a decreased risk. These findings indicate that codeine use may be associated with risk of early discontinuation of metformin and could be used as a basis for further investigation....
Lecoanet, Daniel; Quataert, Eliot
2012-01-01
We study the effects of anisotropic thermal conduction along magnetic field lines on an accelerated contact discontinuity in a weakly collisional plasma. We first perform a linear stability analysis similar to that used to derive the Rayleigh-Taylor instability (RTI) dispersion relation. We find that anisotropic conduction is only important for compressible modes, as incompressible modes are isothermal. Modes grow faster in the presence of anisotropic conduction, but growth rates do not change by more than a factor of order unity. We next run fully non-linear numerical simulations of a contact discontinuity with anisotropic conduction. The non-linear evolution can be thought of as a superposition of three physical effects: temperature diffusion due to vertical conduction, the RTI, and the heat flux driven buoyancy instability (HBI). In simulations with RTI-stable contact discontinuities, the temperature discontinuity spreads due to vertical heat conduction. This occurs even for initially horizontal magnetic f...
2013-02-06
... 501 Authorization To Manufacture and Distribute Postage Evidencing Systems; Discontinued Indicia... concerning the manufacture and distribution of postage evidencing systems to clarify that effective January 1, 2016, all postage evidencing systems (postage meters and PC Postage products) will be required...
Hydro-mechanical modeling of impermeable discontinuity in rock by extended finite element method
郑安兴; 罗先启
2015-01-01
The extended finite element method(XFEM) is a numerical method for modeling discontinuities within the classical finite element framework. The computation mesh in XFEM is independent of the discontinuities, such that remeshing for moving discontinuities can be overcome. The extended finite element method is presented for hydro-mechanical modeling of impermeable discontinuities in rock. The governing equation of XFEM for hydraulic fracture modeling is derived by the virtual work principle of the fracture problem considering the water pressure on crack surface. The coupling relationship between water pressure gradient on crack surface and fracture opening width is obtained by semi-analytical and semi-numerical method. This method simplifies coupling analysis iteration and improves computational precision. Finally, the efficiency of the proposed method for modeling hydraulic fracture problems is verified by two examples and the advantages of the XFEM for hydraulic fracturing analysis are displayed.
FPGA Based Optimized Discontinuous SVPWM Algorithm for Three Phase VSI in AC Drives
Tole Sutikno
2013-02-01
Full Text Available The discontinuous space vector pulse width modulation (SVPWM has well-known that can reduce switching losses. By simplifying the thermal management issues, the discontinuous SVPWM can potentially reduce the inverter size and cost. However, using the modulation due to different time interval equations for each sector can introduce glitches at the points when the sector is changed. The more main problem, it can increase unwanted harmonic content and current ripple. Consider the decrease in switching losses associated with discontinuous modulation allows the system to utilize a higher switching frequency, this paper present high frequency switching of optimized discontinuous SVPWM based on FPGA to overcome the problems above. The proposed SVPWM has been successfully implemented by using APEX20KE Altera FPGA to drive on a three phase inverter system with 1.5 kW induction machine as load. The results have proved that the method can reduce harmonic content and current ripple without glitches.
A test for diffusional coherency strain hypothesis in the discontinuous precipitation in Mg–Al alloy
K T Kashyap; C Ramachandra; V Bhat; B Chatterji
2000-08-01
Discontinuous precipitation (DP) occurs in many alloy systems under certain conditions. Although solute supersaturation is the chemical driving force for DP, this has to be coupled with another driving force for grain boundary migration. This was identified to be diffusional coherency strain ahead of the moving boundary in the case of diffusion induced grain boundary migration (DIGM) and liquid film migration (LFM). In the present work, the validity of diffusional coherency strain hypothesis is verified in Mg–Al alloy, which exhibits discontinuous precipitation. Samples were tested with an applied stress simultaneously with discontinuous precipitation and it was found that the velocity of the boundaries both parallel and transverse to the stress axis obeys the model for diffusional coherency strain. This work can be used as a conclusive evidence for diffusional coherency strain hypothesis for the occurrence of discontinuous precipitation in Mg–Al alloys.
Cai, Zuowei; Huang, Lihong; Zhang, Lingling
2015-05-01
This paper investigates the problem of exponential synchronization of time-varying delayed neural networks with discontinuous neuron activations. Under the extended Filippov differential inclusion framework, by designing discontinuous state-feedback controller and using some analytic techniques, new testable algebraic criteria are obtained to realize two different kinds of global exponential synchronization of the drive-response system. Moreover, we give the estimated rate of exponential synchronization which depends on the delays and system parameters. The obtained results extend some previous works on synchronization of delayed neural networks not only with continuous activations but also with discontinuous activations. Finally, numerical examples are provided to show the correctness of our analysis via computer simulations. Our method and theoretical results have a leading significance in the design of synchronized neural network circuits involving discontinuous factors and time-varying delays.
Arrest of Avalanche Propagation by Discontinuities on Snow Cover
Frigo, B.; Chiaia, B.
2009-04-01
Considering the spatial variability of the snow cover, the paper analyses, in the framework of Fracture Mechanics, the Mode II fracture propagation on snow cover that leads to large dry slab avalanches. Under the hypothesis of a perfectly brittle phenomenon, avalanche triggering is usually investigated numerically by means of Linear Elastic Fracture Mechanics (McClung, 1979; Chiaia et al., 2008). Since, however, the real phenomenon is intrinsically dynamical, another aspect to investigate is represented by dynamic fracture propagation. In this paper, we model dynamic crack propagation into a dry snow slab, to assess the possibility of crack arrest due to the presence of weak zones distributed along the snow slope. As a consequence of the first triggering mechanism (the Mode II fracture propagation on the weak plane), the secondary Mode I crack propagation in the crown is studied by means of numerical simulations based on Dynamic Elastic Fracture Mechanics and on the theory of crack arresters. By taking into account kinetic energy and using the FEM software FRANC 2D (Wawrzynek and Ingraffea, 1993), several paths of crown fracture propagation and their stability have been investigated. The snowpack is considered as a linear-elastic plate (2D problem), whose physical and mechanical parameters are chosen according to classical literature values. To investigate the possible arrest of crown fracture, we apply the theory of crack arresters, usually adopted for pipelines and perforated steel sheets fracture problems. To study crack arrest, different crack paths are simulated, in discontinuous (equipped with different shapes and geometries of artificial voids) snowpacks. The simulations show the effectiveness of these weak zones, to reduce substantially the crack driving force of the propagating fracture. This means that, increasing spatial variability tends to stabilize the snow slope, eventually splitting a major avalanche event into smaller, independent avalanches. Our
Lee HyunYoung
2010-01-01
Full Text Available We analyze discontinuous Galerkin methods with penalty terms, namely, symmetric interior penalty Galerkin methods, to solve nonlinear Sobolev equations. We construct finite element spaces on which we develop fully discrete approximations using extrapolated Crank-Nicolson method. We adopt an appropriate elliptic-type projection, which leads to optimal error estimates of discontinuous Galerkin approximations in both spatial direction and temporal direction.
A Discontinuous Galerkin Finite Element Method for Hamilton-Jacobi Equations
Hu, Changqing; Shu, Chi-Wang
1998-01-01
In this paper, we present a discontinuous Galerkin finite element method for solving the nonlinear Hamilton-Jacobi equations. This method is based on the Runge-Kutta discontinuous Galerkin finite element method for solving conservation laws. The method has the flexibility of treating complicated geometry by using arbitrary triangulation, can achieve high order accuracy with a local, compact stencil, and are suited for efficient parallel implementation. One and two dimensional numerical examples are given to illustrate the capability of the method.
Continuation versus discontinuation of lithium in recurrent bipolar illness: a naturalistic study.
Biel, Matthew G; Peselow, Eric; Mulcare, Loretta; Case, Brady G; Fieve, Ron
2007-08-01
Lithium's efficacy in prophylaxis of mood episodes in bipolar disorder (BD) is well established in the clinical trial setting, but may be less robust in routine clinical practice. We compared illness recurrence in bipolar patients naturalistically continued on or discontinued from lithium after an extended period of clinical stability on lithium monotherapy, and evaluated other potential risk factors for relapse. We followed 213 patients who were stable for 2 years on lithium monotherapy following resolution of acute symptoms marking their last manic episode. Based upon patient preference and clinical judgment, 159 patients were continued on lithium monotherapy and 54 patients were slowly discontinued. Survival differences between the continued and discontinued groups were assessed using the Kaplan-Meier product limit method, and risk factors for relapse were evaluated in Cox proportional hazards regression. Patients continued on lithium prophylaxis experienced risk of recurrence equivalent to a third of that suffered by discontinued patients during the first year of treatment (0.15 versus 0.45), and significant survival differences persisted throughout follow-up. Median survival time to illness recurrence for patients continued on lithium was 7.33 years [95% confidence interval (CI) 5.67-9.67]; that for patients discontinued from lithium was 1.33 years (95% CI 0.33-2.33). After controlling for all significant covariates, lithium discontinuation was associated with a hazard ratio of 4.85. Inter-episode manic and depressive symptoms conferred increased risk for subsequent recurrence of illness in both groups, while lower lithium levels recorded during the two years of clinical stability preceding study onset were protective. Despite considerable rates of illness recurrence in both groups, those who continued on lithium sustained markedly lower rates of recurrence over a lengthy follow-up period. Lithium discontinuation in BD after successful maintenance monotherapy
无
2000-01-01
The mechanism of discontinuity behavior has important significance in the study of thermal science,such as fire,combustion,explosion and heat transfer.This sort of discontinuity behavior and the catastrophe caused by system nonlinearity may be equivalently classified according to the catastrophe model promulgated by catastrophe theory.Under the conditions of uniform temperature and thermal isolation,the self-ignition behavior of a Semenov System can be viewed as a result of the fold catastrophe of the system.
The discontinuous Galerkin method for the numerical simulation of compressible viscous flow
Česenek Jan
2014-03-01
Full Text Available In this paper we deal with numerical simulation of the compressible viscous flow. The mathematical model of flow is represented by the system of non-stationary compressible Navier-Stokes equations. This system of equations is discretized by the discontinuous Galerkin finite element method in space and in time using piecewise polynomial discontinuous approximations. We present some numerical experiments to demonstrate the applicability of the method using own-developed code.
A Biomimetic Study of Discontinuous-Constraint Metamorphic Mechanism for Gecko-Like Robot
Zhen-dong Dai; Jiu-rong Sun
2007-01-01
Locomotion ability, efficiency and reliability are key targets for a good robot. The linkage mechanism for robot locomotion is a discontinuous-constraint metamorphic mechanism. Here we set up equations to present the discontinuous-constraint, point out that driving and controlling are the key points to improve the performance and efficiency of the linkage mechanism. Inspired by controlling strategy of the motor nervous system in peripheral vertebrae to the locomotion, we draw off motor control and drive strategy.
On the Convergence of Space-Time Discontinuous Galerkin Schemes for Scalar Conservation Laws
May, Georg
2016-01-01
We prove convergence of a class of space-time discontinuous Galerkin schemes for scalar hyperbolic conservation laws. Convergence to the unique entropy solution is shown for all orders of polynomial approximation, provided strictly monotone flux functions and a suitable shock-capturing operator are used. The main improvement, compared to previously published results of similar scope, is that no streamline-diffusion stabilization is used. This is the way discontinuous Galerkin schemes were originally proposed, and are most often used in practice.
Lely Indrawati
2014-01-01
Background: Trends of prevalence contraceptive rates is increasing in the last few years. However, the discontinuation of contraceptives prevalence is still stagnant. Goals: To obtain factors influencing discontinuation of contraceptives in couples of childbearing age 10–49 years. Methods: Population this research are women of childbearing age 10–49 years who are married. Sample in this research are all couples of childbearing age of 10–49 years who had ever used contraception and using contr...
2017-07-01
strength between 190 to 240 MPa and is broadly characterized as a reactive powder concrete (RPC). RPCs have fine aggregates and powders but do not...ER D C/ G SL T R- 17 -1 9 Performance Assessment of Discontinuous Fibers in Fiber-Reinforced Concrete : Current State-of-the-Art G eo te...Discontinuous Fibers in Ultra-High Performance Fiber-Reinforced Concrete : Current State-of-the-Art Charles A. Burchfield Geotechnical and
Mixed time discontinuous space-time finite element method for convection diffusion equations
无
2008-01-01
A mixed time discontinuous space-time finite element scheme for second-order convection diffusion problems is constructed and analyzed. Order of the equation is lowered by the mixed finite element method. The low order equation is discretized with a space-time finite element method, continuous in space but discontinuous in time. Stability, existence, uniqueness and convergence of the approximate solutions are proved. Numerical results are presented to illustrate efficiency of the proposed method.
无
2000-01-01
In this paper,authors discuss the numerical methods of general discontinuous boundary value problems for elliptic complex equations of first order.They first give the well posedness of general discontinuous boundary value problems,reduce the discontinuousboundary value problems to a variation problem,and then find the numerical solutions ofabove problem by the finite element method.Finally authors give some error-estimates of the foregoing numerical solutions.
Seismic imaging of a mid-lithospheric discontinuity beneath Ontong Java Plateau
Tharimena, Saikiran; Rychert, Catherine A.; Harmon, Nicholas
2016-09-01
Ontong Java Plateau (OJP) is a huge, completely submerged volcanic edifice that is hypothesized to have formed during large plume melting events ∼90 and 120 My ago. It is currently resisting subduction into the North Solomon trench. The size and buoyancy of the plateau along with its history of plume melting and current interaction with a subduction zone are all similar to the characteristics and hypothesized mechanisms of continent formation. However, the plateau is remote, and enigmatic, and its proto-continent potential is debated. We use SS precursors to image seismic discontinuity structure beneath Ontong Java Plateau. We image a velocity increase with depth at 28 ± 4 km consistent with the Moho. In addition, we image velocity decreases at 80 ± 5 km and 282 ± 7 km depth. Discontinuities at 60-100 km depth are frequently observed both beneath the oceans and the continents. However, the discontinuity at 282 km is anomalous in comparison to surrounding oceanic regions; in the context of previous results it may suggest a thick viscous root beneath OJP. If such a root exists, then the discontinuity at 80 km bears some similarity to the mid-lithospheric discontinuities (MLDs) observed beneath continents. One possibility is that plume melting events, similar to that which formed OJP, may cause discontinuities in the MLD depth range. Plume-plate interaction could be a mechanism for MLD formation in some continents in the Archean prior to the onset of subduction.
Grundy Paul E
2005-05-01
Full Text Available Abstract Background There are no standard criteria for when to discontinue intravenous antimicrobial therapy (IVAMT in children with febrile neutropenia (FN, but it is now common to discontinue IVAMT and discharge patients with an absolute neutrophil count (ANC ≤ 500 /mm3. The purpose of this study was to evaluate the outcome of a large cohort of children with FN who had IVAMT discontinued with an ANC ≤ 500 /mm3 Methods A retrospective chart review was completed of patients in the Northern Alberta Children's Cancer Program with FN and no apparent clinical source of fever from June 1, 1997 to July 1, 2002. Results Out of a total of 275 patients, 127 (46% had at least one episode of FN, with FN occurring in patients with sarcomas more commonly than in those with leukemia/ lymphoma and least in those with other solid tumors. In 59 of 276 episodes of FN (21% patients had a microbiologically defined infection at admission. Of the 217 remaining episodes, 112 of 199 patients (56% with known neutrophil counts had IVAMT discontinued before their absolute neutrophil count (ANC reached 500 /mm3 at the discretion of the clinician. Fever recurred in only two of these patients after discharge, and there were no bacterial infections diagnosed after parenteral antibiotics were discontinued. Conclusion Even without use of standard criteria for early discharge, clinicians appear to be skilled at selecting children with FN who can safely have IVAMT discontinued with an ANC ≤ 500 /mm3.
Kraisler, Eli; Kronik, Leeor [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel)
2014-05-14
The fundamental gap is a central quantity in the electronic structure of matter. Unfortunately, the fundamental gap is not generally equal to the Kohn-Sham gap of density functional theory (DFT), even in principle. The two gaps differ precisely by the derivative discontinuity, namely, an abrupt change in slope of the exchange-correlation energy as a function of electron number, expected across an integer-electron point. Popular approximate functionals are thought to be devoid of a derivative discontinuity, strongly compromising their performance for prediction of spectroscopic properties. Here we show that, in fact, all exchange-correlation functionals possess a derivative discontinuity, which arises naturally from the application of ensemble considerations within DFT, without any empiricism. This derivative discontinuity can be expressed in closed form using only quantities obtained in the course of a standard DFT calculation of the neutral system. For small, finite systems, addition of this derivative discontinuity indeed results in a greatly improved prediction for the fundamental gap, even when based on the most simple approximate exchange-correlation density functional – the local density approximation (LDA). For solids, the same scheme is exact in principle, but when applied to LDA it results in a vanishing derivative discontinuity correction. This failure is shown to be directly related to the failure of LDA in predicting fundamental gaps from total energy differences in extended systems.
Fitness in animals correlates with proximity to discontinuities in body mass distributions.
Angeler, David G.; Allen, Craig R.; Vila-Gispert, Anna; Almeida, David
2014-01-01
Discontinuous structure in landscapes may cause discontinuous, aggregated species body-mass patterns, reflecting the scales of structure available to animal communities within a landscape. Empirical analyses have shown that the location of species within body mass aggregations, which reflect this scale-specific organization, is non-random with regard to several ecological phenomena, including species extinctions. The propensity of declining species to have body masses proximate to discontinuities suggests that transition zones between scaling regimes ultimately decreases the ecological fitness for some species. We test this proposition using vulnerable and unthreatened fish species in Mediterranean streams with differing levels of human impact. We show that the proximity to discontinuities in body mass aggregations (“distance-to-edge”) of more vs. less fit individuals within vulnerable and unthreatened populations differs. Specifically, regression analysis between the scaled mass index, a proxy of animal fitness, and distance-to-edge reveals negative and positive relationships for vulnerable and unthreatened species, respectively. That is, fitness is higher close to discontinuities in vulnerable populations and toward the center of body mass aggregation groups in unthreatened populations. Our results demonstrate the suitability of the discontinuity framework for scrutinizing non-random patterns of environmental impact in populations. Further exploration of the usefulness of this method across other ecosystems and organism groups is warranted.
The effect of discontinuities on the corrosion behaviour of copper canisters
King, F. [Integrity Corrosion Consulting Ltd, Calgary, AL (Canada)
2004-03-01
Discontinuities may remain in the weld region of copper canisters following the final closure welding and inspection procedures. Although the shell of the copper canister is expected to exhibit excellent corrosion properties in the repository environment, the question remains what impact these discontinuities might have on the long-term performance and service life of the canister. A review of the relevant corrosion literature has been carried out and an expert opinion of the impact of these discontinuities on the canister lifetime has been developed. Since the amount of oxidant in the repository is limited and the maximum wall penetration is expected to be < 2 mm, discontinuities will only be significant if they impact the localised corrosion or stress corrosion cracking (SCC) behaviour of the canister. Not all of the discontinuities will impact the corrosion behaviour of the canister. Only surface-breaking discontinuities and those discontinuities within 2 mm of the surface will affect the corrosion behaviour. Defects located further away from the finished surface will have no impact. The relevant literature on the initiation and propagation of localised corrosion and SCC has been reviewed. Initiation of localised corrosion occurs at the microscopic scale at grain boundaries, and will not be affected by the presence of macroscopic discontinuities. The localised breakdown of a passive Cu{sub 2}O/Cu(OH){sub 2} film at a critical electrochemical potential determines where and when pits initiate, not the presence of pit-shaped surface discontinuities. The factors controlling pit growth and death are well understood. There is evidence for a maximum pit radius for copper in chloride solutions, above which the small anodic: cathodic surface area ratio required for the formation of deep pits cannot be sustained. This maximum pit radius is of the order of 0.1-0.5 mm. Surface discontinuities larger than this size are unlikely to propagate as pits, and pits generated from
Mohorovicic discontinuity depth analysis beneath North Patagonian Massif
Gómez Dacal, M. L.; Tocho, C.; Aragón, E.
2013-05-01
The North Patagonian Massif is a 100000 km2, sub-rectangular plateau that stands out 500 to 700 m higher in altitude than the surrounding topography. The creation of this plateau took place during the Oligocene through a sudden uplift without noticeable internal deformation. This quite different mechanical response between the massif and the surrounding back arc, the short time in which this process took place and a regional negative Bouguer anomaly in the massif area, raise the question about the isostatic compensation state of the previously mentioned massif. In the present work, a comparison between different results about the depth of the Mohorovicic discontinuity beneath the North Patagonian Massif and a later analysis is made. It has the objective to analyze the crustal thickness in the area to contribute in the determination of the isostatic balance and the better understanding of the Cenozoic evolution of the mentioned area. The comparison is made between four models; two of these were created with seismic information (Feng et al., 2006 and Bassin et al., 2000), another model with gravity information (Barzaghi et al., 2011) and the last one with a combination of both techniques (Tassara y Etchaurren, 2011). The latter was the result of the adaptation to the work area of a three-dimensional density model made with some additional information, mainly seismic, that constrain the surfaces. The work of restriction and adaptation of this model, the later analysis and comparison with the other three models and the combination of both seismic models to cover the lack of resolution in some areas, is presented here. According the different models, the crustal thickness of the study zone would be between 36 and 45 Km. and thicker than the surrounding areas. These results talk us about a crust thicker than normal and that could behave as a rigid and independent block. Moreover, it can be observed that there are noticeable differences between gravimetric and seismic
ChunguangXU
1996-01-01
The investigation of Mach reflection formed after the impingement of a weak plane shock wave on a wedge .with shock Mach number Ms near 1,is still an open problem[12].It's difficult for shock tube experiments with interferometer to detect contact discontinuities ,if it is too weak;also difficult to catch with due accuracy the transition condition between Mach reflection and regular reflection.The interest to this phenomenon is continuing,especially for weak shocks because there was systematic discrepancy between simplified three shock theory of von Neumann[8] and shock tube results[15] which was named by G.Birkhoff as “Von Neumann Paradox on three shock theory”[18].In 1972,K.O.Friedrichs called for more computational efforts on this problem.Recently it is known that for weak impinging shocks it's still diffcult to get contact discontinuities and curved mach stem with satisfactory accuracy,Recent numerical computation sometimes even fails to show reflected shock wave[6].These explain why von Neumann paradox of the three shock theory in case of weak discontinuities is still a problem of interesting[9,12,14].In this paper,on one hand,we investigate the numerical methods for Euler's equation for compressible inviscid flow,aiming at improving the computation of contact discontinuities,on the other hand,a methodology is suggested to correctly plot flow data from the massive information in storage.On this basis,all the reflected shock wave.contact discontinuities and the curved Mach stem are determined.We get Mach reflection under the condition when over-simplified shock theory predicts no such configuration[5].
Yee, Helen M. C.; Kotov, D. V.; Wang, Wei; Shu, Chi-Wang
2013-01-01
The goal of this paper is to relate numerical dissipations that are inherited in high order shock-capturing schemes with the onset of wrong propagation speed of discontinuities. For pointwise evaluation of the source term, previous studies indicated that the phenomenon of wrong propagation speed of discontinuities is connected with the smearing of the discontinuity caused by the discretization of the advection term. The smearing introduces a nonequilibrium state into the calculation. Thus as soon as a nonequilibrium value is introduced in this manner, the source term turns on and immediately restores equilibrium, while at the same time shifting the discontinuity to a cell boundary. The present study is to show that the degree of wrong propagation speed of discontinuities is highly dependent on the accuracy of the numerical method. The manner in which the smearing of discontinuities is contained by the numerical method and the overall amount of numerical dissipation being employed play major roles. Moreover, employing finite time steps and grid spacings that are below the standard Courant-Friedrich-Levy (CFL) limit on shockcapturing methods for compressible Euler and Navier-Stokes equations containing stiff reacting source terms and discontinuities reveals surprising counter-intuitive results. Unlike non-reacting flows, for stiff reactions with discontinuities, employing a time step and grid spacing that are below the CFL limit (based on the homogeneous part or non-reacting part of the governing equations) does not guarantee a correct solution of the chosen governing equations. Instead, depending on the numerical method, time step and grid spacing, the numerical simulation may lead to (a) the correct solution (within the truncation error of the scheme), (b) a divergent solution, (c) a wrong propagation speed of discontinuities solution or (d) other spurious solutions that are solutions of the discretized counterparts but are not solutions of the governing equations
de Vries, Liat; Grushka, Yael; Lebenthal, Yael; Shalitin, Shlomit; Phillip, Moshe
2011-08-01
There are few reports on rates and predictors for pump discontinuation in the pediatric population. To study the rate of and predictors for insulin pump discontinuation among pediatric patients with type 1 diabetes. Medical chart review of 530 patients with type 1 diabetes who had started pump therapy between 2000 and 2008 in our center revealed that 11.3% had discontinued pump use after 3 d to 5 yr; of these, 9.1% discontinued pump use at least 3 months after initiation. Relevant data were retrieved from the files of these patients and from those of 100 randomly assigned pump-treated patients. The pump discontinuation group had a significantly higher proportion of female patients (75 vs. 46%, p = 0.001) and patients above 10 yr of age (93.8 vs. 80%, p = 0.03) than the reference group. Comparable findings were noted for age at diagnosis, pubertal stage, anthropometric data and duration of diabetes at pump initiation, rate of severe hypoglycemic and diabetic ketoacidosis episodes. There were no between-group differences in number of daily insulin injections and blood glucose measurements before pump treatment. At pump initiation, HbA(1c) was significantly higher in patients discontinuing pump therapy than in the controls (8.6 ± 1.4 vs. 8.1 ± 1.0, p = 0.02). This difference was maintained at the last follow-up visit recorded. Almost 90% of our cohort maintained pump therapy. Female gender, age older than 10 years in girls and poor metabolic control at pump initiation were associated with higher risk for pump discontinuation - for such patients intensified individual and family support may serve to maximize persistent pump therapy. © 2010 John Wiley & Sons A/S.
Ayres, Lorena Rocha; Baldoni, André de Oliveira; Borges, Anna Paula de Sá; Pereira, Leonardo Régis Leira
2014-02-01
Oral treatment in women with breast cancer has been increasingly used. However, a potentially negative side of oral medication is poor patient adherence and/or discontinuation, which reduces the treatment effectiveness, accelerating progression of the disease and reducing the patient survival rate. To compare the rates of adherence and/or discontinuation and the methodologies used to assess these outcomes. It was conducted an integrative review of original articles published from 2000 to 2012, in which their primary outcome was to quantify medication adherence and/or discontinuation of oral hormonal therapy in patients with hormone receptor positive breast cancer. Original studies were searched in the PubMed/MEDLINE, Scopus, Embase and SciELO databases. The Medical Subject Heading was used to define descriptors. The descriptor "breast neoplasms" was used in all combinations. Each of the descriptors "medication adherence" and "patient compliance" were combined with each of the following descriptors "tamoxifen", "aromatase inhibitors", "selective estrogen receptor modulators", or the terms "letrozole", "anastrozole", and "exemestane". Twenty-four original articles were included. Our study showed a wide range of adherence and discontinuation rates, ranging from 45-95.7 and 12-73 %, respectively. Regarding the methodological development of the selected articles, a high prevalence (87.5 %) of prospective and/or retrospective longitudinal studies was found. In addition, there was a high prevalence of studies using a database (70.8 %). Among some of the studies, it was shown that patient adherence to hormonal therapy gradually reduces, while discontinuation increases during the treatment. It was observed a great diversity among rates of adherence and/or discontinuation of hormonal therapy for breast cancer, which may be due to a lack of methodology standardization. Therefore, adequate and validated methods to ensure reliability of the results and allow comparison in the
Detection of a new sub-lithospheric discontinuity in Central Europe with S-receiver functions
Kind, Rainer; Handy, Mark R.; Yuan, Xiaohui; Meier, Thomas; Kämpf, Horst; Soomro, Riaz
2017-03-01
We used S-receiver functions (i.e. S-to-P converted signals) to study seismic discontinuities in the upper mantle between the Moho and the 410 km discontinuity beneath central Europe. This was done by using c. 49,000 S-receiver functions from c. 700 permanent and temporary broadband stations made available by the open EIDA Archives. Below Phanerozoic Europe we observed expected discontinuities like the Moho, the lithosphere-asthenosphere boundary (LAB), the Lehmann discontinuity and the 410 km discontinuity with an additional overlying low velocity zone. Below the East European Craton (EEC), we observed the Mid-Lithospheric Discontinuity (MLD) at c. 100 km depth as well as the controversial cratonic LAB at c. 200 km depth. At the boundary of the EEC but still below the Phanerozoic surface, we observed downward velocity reductions below the LAB in the following regions: the North German-Polish Plain at about 200 km depth; the Bohemian Massive, north-west dipping from 200 to 300 km depth; the Pannonian Basin, north-east dipping from 150 to 200 km depth underneath the western Carpathians and the EEC. We named this newly observed structure Sub-Lithospheric Discontinuity (SLD). At the northern edge of the Bohemian Massive, we see a sharp vertical step of about 100 km between the SLD below the Bohemian Massive and the North German-Polish Plain. This step follows the surface trace of the Rheic Suture between the continental Saxo-Thuringian and Rheno-Herzynian zones of the Variscan orogen. A preliminary interpretation of these features is that a prong of the cratonic mantle lithosphere penetrated the Phanerozoic asthenosphere during the continental collision at the western and south-western edges of the EEC.
Mahumud RA
2015-01-01
Full Text Available Rashidul Alam Mahumud,1 Md Golam Hossain,2 Abdur Razzaque Sarkar,1 Md Nurul Islam,2 Md Ripter Hossain,2 Aik Saw,3 Jahangir AM Khan1,4 1Health Economics and Financing Research Group, Center for Equity and Health Systems, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh; 2Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh; 3Department of Orthopaedic Surgery, National Orthopaedic Centre of Excellence for Research and Learning, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; 4Adjunct Faculty, Health Economics Unit, Department of Learning, Informatics, Management and Ethics, Karolinska Institutet, Stockholm, Sweden Introduction: Contraceptive discontinuation is a worldwide incident that may be connected with low incentive to avoid pregnancy. Contraceptive discontinuation highly contributes to unplanned pregnancy and unwanted births.Objectives: The objective of this study was to observe the prevalence of discontinuation and switching of contraceptive methods among Bangladeshi married women. In addition, the sociodemographic factors associated with contraceptive discontinuation and switching were assessed.Methods: Secondary cross-sectional data was used in this study. A total of 16,273 married Bangladeshi women of reproductive age (15–49 years were considered in the present study, from the Bangladesh Demographic and Health Survey, 2011. Logistic regression models were used to determine the relationships between key sociodemographic factors and user status.Results: The prevalence of discontinuation and switching of contraceptive method among women were 38.4% and 15.4%, respectively. The logistic regression model demonstrated that women in early reproductive years (25–29 years and 30–34 years significantly more often (odds ratio [OR] =0.84 and 0.71, respectively discontinued use of contraceptives. Significantly higher rates of discontinuation were pronounced among women who
A hyper-spherical adaptive sparse-grid method for high-dimensional discontinuity detection
Zhang, Guannan [ORNL; Webster, Clayton G [ORNL; Gunzburger, Max D [ORNL; Burkardt, John V [ORNL
2014-03-01
This work proposes and analyzes a hyper-spherical adaptive hi- erarchical sparse-grid method for detecting jump discontinuities of functions in high-dimensional spaces is proposed. The method is motivated by the the- oretical and computational inefficiencies of well-known adaptive sparse-grid methods for discontinuity detection. Our novel approach constructs a func- tion representation of the discontinuity hyper-surface of an N-dimensional dis- continuous quantity of interest, by virtue of a hyper-spherical transformation. Then, a sparse-grid approximation of the transformed function is built in the hyper-spherical coordinate system, whose value at each point is estimated by solving a one-dimensional discontinuity detection problem. Due to the smooth- ness of the hyper-surface, the new technique can identify jump discontinuities with significantly reduced computational cost, compared to existing methods. Moreover, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. Rigorous error estimates and complexity anal- yses of the new method are provided as are several numerical examples that illustrate the effectiveness of the approach.
Work related determinants of breastfeeding discontinuation among employed mothers in Malaysia
Darus Azlan
2011-02-01
Full Text Available Abstract Background This cross-sectional study assesses factors that contribute to discontinuing breastfeeding among employed mothers in Malaysia. Methods A structured questionnaire was used in conducting this study involving all government health clinics in Petaling district between July and September 2006. Respondents were Malaysian women with children between the ages of six to twelve months who were formally employed. Factors studied were selected socio-demographic and work-related characteristics. Results From a total of 290 respondents, 51% discontinued breastfeeding. The majority (54% of mothers who discontinued breastfeeding had breastfed their babies for less than three months. Compared to Malay mothers, the risk of breastfeeding discontinuation were higher among Chinese (AOR 3.7, 95% CI: 1.7, 7.8 and Indian mothers (AOR 7.3, 95% CI 1.9, 27.4. Not having adequate breastfeeding facilities at the workplace was also a risk factor for breastfeeding discontinuation (AOR 1.8, 95% CI: 1.05, 3.1. Conclusion It is important that workplaces provide adequate breastfeeding facilities such as a room in which to express breast milk and a refrigerator, and allow mothers flexible time to express breast milk.
Woolley, Stephen B; Fredman, Lisa; Goethe, John W; Lincoln, Alisa K; Heeren, Timothy
2010-12-01
Studies have suggested that discontinuation of treatment in depressed patients is associated with their perceptions about their treatment. We surveyed 403 adults treated for major depressive disorder with a selective serotonin reuptake inhibitor (SSRI) 3 months after onset of treatment to assess their interactions with clinicians, reasons they stopped SSRI treatment, and SSRI side effects (SEs). Bothersome SEs, poorer instruction by physicians about SSRI SEs, and self-reported change in depression, sex, marital status, and employment were significantly (P < 0.05) associated with discontinuation. Logistic regression examined the associations between patients' perceptions during treatment planning and SSRI discontinuation. Seventeen percent of patients felt uninvolved in treatment decisions, 9% disagreed with the diagnosis, and 24% subsequently stopped treatment. Elevated risk of discontinuation was found among patients who felt uninvolved in treatment decisions (unadjusted risk ratio [RR], 2.3; 95% confidence interval [CI], 1.2-4.3) and those who disagreed with the diagnosis (RR, 2.0; CI, 0.9-4.4). Patients who both felt uninvolved and disagreed with the diagnosis were 7-fold as likely to discontinue their SSRI (RR, 7.3; CI, 1.5-36.3) compared with those who felt neither uninvolved nor disagreed. Selective serotonin reuptake inhibitor SEs, specific interactions with clinicians, self-assessed outcomes, and sociodemographics did not explain these associations. To improve adherence to medications, clinicians should consider patients' perceptions about their involvement in treatment decisions and agreement with their diagnosis.
Kim, Min Soo; Lee, Jehyun [Changwon National University, Changwon (Korea, Republic of); Han, Seung Zeon; Ahn, Jee Hyuk [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lim, Sung Hwan [Kangwon National University, Chuncheon (Korea, Republic of); Kim, Kwang Ho [Pusan National University, Pusan (Korea, Republic of); Kim, Sang sik [Gyeongsang National University, Jinju (Korea, Republic of)
2017-02-15
In order to study the effect of microstructural change on the tensile properties of discontinuous precipitated Al-Zn binary alloy, four different Al-Zn alloys(25, 30, 35, 45 wt%Zn) were aged at 160 ℃ for different aging times(0, 5, 15, 30, 60, 120, 360 min) after being solution treated at 400 ℃, and successively drawn at room and cryogenic temperatures(-197 ℃). Discontinuous precipitation was formed during aging in the Al matrix(which contained more than 30 wt%Zn) in Al alloys containing more than 30 wt%Zn. The tensile strength of continuous precipitated Al-35Zn alloy decreased with increasing drawing ratio, however, the tensile strength of discontinuous precipitated Al-35Zn alloy increased with further drawing. The strength and ductility combination, 350 MPa-36%was achieved by drawning discontinuous precipitated Al-Zn alloy at room temperature. The discontinuous precipitated Al-Zn alloy drawn at cryogenic temperature showed a higher value of tensile strength, over 500 MPa, although ductility decreased.
Ruilan Tian
2016-06-01
Full Text Available The coupled system of smooth and discontinuous absorber and beam bridge under moving loads is constructed in order to detect the effectiveness of smooth and discontinuous absorber. It is worth pointing out that the coupled system contains an irrational restoring force which is a barrier for conventional nonlinear techniques. Hence, the harmonic balance method and Fourier expansion are used to obtain the approximate solutions of the system. The first and the second kind of generalized complete elliptic integrals are introduced. Furthermore, using power flow approach, the performance of smooth and discontinuous absorber in vibration reduction is estimated through the input energy, the dissipated energy, and the damping efficiency. It is interesting that only depending on the value of the smoothness parameter, the efficiency parameter of vibration reduction is optimized. Therefore, smooth and discontinuous absorber can adapt itself to effectively reducing the amplitude of the vibration of the beam bridge, which provides an insight to the understanding of the applications of smooth and discontinuous oscillator in engineering and power flow characteristics in nonlinear system.
Nicola Ponara
2012-11-01
Full Text Available Regularized Heaviside and Dirac delta function are used in several fields of computational physics and mechanics. Hence the issue of the quadrature of integrals of discontinuous and singular functions arises. In order to avoid ad-hoc quadrature procedures, regularization of the discontinuous and the singular fields is often carried out. In particular, weight functions of the signed distance with respect to the discontinuity interface are exploited. Tornberg and Engquist (Journal of Scientific Computing, 2003, 19: 527–552 proved that the use of compact support weight function is not suitable because it leads to errors that do not vanish for decreasing mesh size. They proposed the adoption of non-compact support weight functions. In the present contribution, the relationship between the Fourier transform of the weight functions and the accuracy of the regularization procedure is exploited. The proposed regularized approach was implemented in the eXtended Finite Element Method. As a three-dimensional example, we study a slender solid characterized by an inclined interface across which the displacement is discontinuous. The accuracy is evaluated for varying position of the discontinuity interfaces with respect to the underlying mesh. A procedure for the choice of the regularization parameters is proposed.
Yakubu Sani Ibn
2013-06-01
Full Text Available This study aimed at evaluating the incidence of adverse effects leading to treatment discontinuation of antihypertensive drugs within the same therapeutic class. Individual medical records were searched to identify those hypertensive patients who had been commenced on antihypertensive therapy during a 24-month period and who had subsequently for a reason(s discontinued the therapy. The results showed variation in discontinuation rates for drugs within same class, and that might be related to the relative frequency of specific adverse effects. Cough was the reason cited for discontinuation of angiotensin converting enzyme inhibitors, with linosopril appearing to be better tolerated than captopril (39% vs 48% ; peripheral oedema with calcium channel blockers, with amlodipine appearing to be better tolerated than nifedipine (29% vs 38% and bradycardia with beta adrenergic receptor blockers, with propranolol better tolerated than atenolol (0% vs 48%. Diuretics showed the lowest discontinuation rate (3.3% mainly due to hypokalemia, with thiazide better tolerated than frusemide (11% vs 43%. Prescribers should verify their use of antihypertensive drugs to ensure that they prescribe drugs with lower adverse effect rates, in order that patients with hypertension continue using the medication in the long term, thereby reducing the risk of developing cardiovascular complications associated with uncontrolled blood pressure.
Diffractional Imaging of Mantle Transition Zone Discontinuities Using SdS-SS Traveltimes
Guo, Z.; Zhou, Y.
2015-12-01
The mantle transition zone is characterized by two discontinuities at depths of about 410 and 660 km. Mineral physics studies suggest that wavespeed and density jumps across the discontinuities are associated with olivine phase transformations and the depths at which the phase transformations occur are strongly dependent on temperature. Imaging lateral variations of the discontinuity depths is important for constraining thermal structure in the mid mantle. SS precursors (SdS) are waves reflected at the underside of the discontinuities and arrive beforethe SS phase. Their traveltime measurements at teleseismic distances can be used to map the discontinuities at a global scale. In this study, we measure frequency-dependent SS precursors traveltimes using seismograms recorded at GSN stations for earthquakes occurred between 2000 and 2015. The measurements were made using cosine tapers and multitapers and the traveltimes show significant dispersion. We calculate finite-frequency sensitivity kernels for SdS-SS differential measurements based on traveling-wave mode summation, which account for complete wave interactions within the measurement window. We will discuss preliminary results from finite-frequency imaging using SdS-SS dispersion measurements and the effects of 3-D crustal structure and mantle wavespeed structure.
Laura B Ramsey
Full Text Available Osteonecrosis is one of the most common, serious, toxicities resulting from the treatment of acute lymphoblastic leukemia. In recent years, pediatric acute lymphoblastic leukemia clinical trials have used discontinuous rather than continuous dosing of dexamethasone in an effort to reduce the incidence of osteonecrosis. However, it is not known whether discontinuous dosing would compromise antileukemic efficacy of glucocorticoids. Therefore, we tested the efficacy of discontinuous dexamethasone against continuous dexamethasone in murine models bearing human acute lymphoblastic leukemia xenografts (n = 8 patient samples or murine BCR-ABL+ acute lymphoblastic leukemia. Plasma dexamethasone concentrations (7.9 to 212 nM were similar to those achieved in children with acute lymphoblastic leukemia using conventional dosages. The median leukemia-free survival ranged from 16 to 59 days; dexamethasone prolonged survival from a median of 4 to 129 days in all seven dexamethasone-sensitive acute lymphoblastic leukemias. In the majority of cases (7 of 8 xenografts and the murine BCR-ABL model we demonstrated equal efficacy of the two dexamethasone dosing regimens; whereas for one acute lymphoblastic leukemia sample, the discontinuous regimen yielded inferior antileukemic efficacy (log-rank p = 0.002. Our results support the clinical practice of using discontinuous rather than continuous dexamethasone dosing in patients with acute lymphoblastic leukemia.
Reasons for discontinuation of sildenafil citrate after successful restoration of erectile function
HwancheolSon; KwanjinPark; Soo-WoongKim; Jae-SeungPaick
2004-01-01
Aim: To investigate the reasons for discontinuations of sildenafil after the successful restoration of erectile function. Methods: One hundred fifty six patients, whose scores of erectile function domain of the 15-item International Index of Erectile Function (IIEF) increased to 26 or more after sildenafil medication, were included in this study. Six-months after the first sildenafil prescription, compliance to medication and the reason for discontinuity were reviewed by chart or surveyed by telephone. Results: Fifty-four (34.6%) of the 156 successfully treated patients discontinued sildenafil medication. The reasons for discontinuance were shortcomings in the partners' or patients' emotional readiness for the restoration of sexual life after long-term abstinence (37.0%), fear of possible side effects (18.5%), recovery of spontaneous erection (14.8%), postponement of ED treatment because of comorbid disease treatment (11.1%), unwillingness to accept drug-dependent erection (7.4%), high drug cost (3.7%),unacceptability of planned sexual activity (3.7%) and lack of sexual interest (3.7 %). Conclusion: The reasons for discontinuing sildenafil medication were primarily emotional or relationship-oriented, which indicates that simple recovery of a rigid erection is insufficient to restore sexual activity. More education about the effects of drug and the counseling of both partners is recommended to promote the successful recovery of sexual activity.
Peterson, Chris J; Dosch, Jerald J; Carson, Walter P
2014-08-01
The nucleation hypothesis appears to explain widespread patterns of succession in tropical pastures, specifically the tendency for isolated trees to promote woody species recruitment. Still, the nucleation hypothesis has usually been tested explicitly for only short durations and in some cases isolated trees fail to promote woody recruitment. Moreover, at times, nucleation occurs in other key habitat patches. Thus, we propose an extension, the matrix discontinuity hypothesis: woody colonization will occur in focal patches that function to mitigate the herbaceous vegetation effects, thus providing safe sites or regeneration niches. We tested predictions of the classical nucleation hypothesis, the matrix discontinuity hypothesis, and a distance from forest edge hypothesis, in five abandoned pastures in Costa Rica, across the first 11 years of succession. Our findings confirmed the matrix discontinuity hypothesis: specifically, rotting logs and steep slopes significantly enhanced woody colonization. Surprisingly, isolated trees did not consistently significantly enhance recruitment; only larger trees did so. Finally, woody recruitment consistently decreased with distance from forest. Our results as well as results from others suggest that the nucleation hypothesis needs to be broadened beyond its historical focus on isolated trees or patches; the matrix discontinuity hypothesis focuses attention on a suite of key patch types or microsites that promote woody species recruitment. We argue that any habitat discontinuities that ameliorate the inhibition by dense graminoid layers will be foci for recruitment. Such patches could easily be manipulated to speed the transition of pastures to closed canopy forests.
Llanos, Ella María; Jeffrey, Robert G.; Hillis, Richard; Zhang, Xi
2017-08-01
Rocks are naturally fractured, and lack of knowledge of hydraulic fracture growth through the pre-existing discontinuities in rocks has impeded enhancing hydrocarbon extraction. This paper presents experimental results from uniaxial and biaxial tests, combined with numerical and analytical modelling results to develop a criterion for predicting whether a hydraulic fracture will cross a discontinuity, represented at the laboratory by unbonded machined frictional interfaces. The experimental results provide the first evidence for the impact of viscous fluid flow on the orthogonal fracture crossing. The fracture elliptical footprint also reflects the importance of both the applied loading stress and the viscosity in fracture propagation. The hydraulic fractures extend both in the direction of maximum compressive stress and in the direction with discontinuities that are arranged to be normal to the maximum compressive stress. The modelling results of fracture growth across discontinuities are obtained for the locations of slip starting points in initiating fracture crossing. Our analysis, in contrast to previous work on the prediction of frictional crossing, includes the non-singular stresses generated by the finite pressurised hydraulic fracture. Experimental and theoretical outcomes herein suggest that hydraulic fracture growth through an orthogonal discontinuity does not depend primarily on the interface friction coefficient.
Sharpness of upper-mantle discontinuities determined from high-frequency reflections
Benz, H.M.; Vidale, J.E.
1993-01-01
AN understanding of the nature of seismic discontinuities in the Earth's upper mantle is important for understanding mantle processes: in particular, the amplitude and sharpness of these discontinuities are critical for assessing models of upper-mantle phase changes and chemical layering. So far, seismic studies aimed at determining the thickness and lateral variability of upper-mantle discontinuities have yielded equivocal results, particularly for the discontinuity at 410km depth1,2. Here we present short-period (0.8-2.0 s) recordings of upper-mantle precursors to the seismic phase P???P??? (PKPPKP) from two South American earthquakes recorded by the ???700-station short-period array in California. Our results show that the 410- and 660-km discontinuities beneath the Indian Ocean are locally simple and sharp, corresponding to transi-tion zones of 4 km or less. These observations pose problems for mineral physics models3-5, which predict a transitional thickness greater than 6 km for the peridotite to ??-spinel phase transition. In contrast to the results of long-period studies6,7, we observe no short-period arrivals from near 520 km depth. ?? 1993 Nature Publishing Group.
Discontinuity of Gas-dynamic Variables in the Center of the Compression Wave
Pavel Viktorovich Bulat
2014-12-01
Full Text Available The purpose of research-the study of the flow in the center of the centered isentropic compression waves. Gas-dynamic discontinuities cover shocks, shockwaves, interfaces and sliding surfaces and also the center of the centered compression wave one-dimensional and two-dimensional. For a long time there has been no analysis of the shockwave structures arising in the center of compression waves. At the same time, the problem of development of supersonic and hypersonic air inlets demands to consider the process of the stream isentropic compression. This problem is connected (three-dimensional case to the problem of arising inside the streams of hinged shocks as opposite to the usual discontinuities not resulted by interaction of supersonic streams, waves and discontinuities, but like from nowhere. This study sets the problem for study in the terms of the developed theory of the interference of gas-dynamic discontinuities of the area of existing solutions for the structures of possible types. We have obtained the relations describing the parameters in the center of the compression wave. We have considered the neutral polar of neither compression meeting the case when in the center of the compression wave there neither shocks nor depression waves. The analysis of properties of the centered compression wave adds to the theory of stationary gas-dynamic discontinuities. We have specified the borders of the shock structure existence area optimal for development of supersonic diffusers.
Njoku CO
2014-09-01
Full Text Available Background: Contraception has an important role to play in reducing the high rate of maternal morbidity and mortality in developing countries. Objective: The objective is to determine the prevalence rate, methods and reasons for discontinuation of contraceptive methods at UCTH, Calabar. Method: This was a retrospective study of all clients that utilised different forms of contraceptives at UCTH, Calabar from 1st January, 2009 to 31st December, 2013. Results: A total of 5,381 clients used various methods of contraception while 13,492 live births were recorded giving the prevalence rate of 39.9% of total live birth. Common methods were intrauterine contraceptive device (IUCD 1,745(32.8% and injectable contraceptives 1,268(23.8%. Most clients 1,876(35.2% were graduates while 81(1.5% had no formal education. A total of 535(10.1% clients discontinued different family planning method commonly due to desire for pregnancy and side effects. IUCD had the highest discontinuation rate. Conclusion: The study revealed low prevalence rate of contraceptive use which was more among teenagers and illiterate women. The main reasons for discontinuation of different methods were desire for pregnancy, side effects and menopause. Creating more contraceptive awareness, improvement in contraceptive counselling and female education will help to improve contraceptive utilisation rate and reduce discontinuation rate.
Risk factors for discontinuation of insulin pump therapy in pediatric and young adult patients.
Kostev, Karel; Rockel, Timo; Rosenbauer, Joachim; Rathmann, Wolfgang
2014-12-01
Previous studies have shown that only a small number of pediatric and young adult patients discontinue pump therapy, but risk factors for discontinuation are unclear. To identify characteristics of pediatric and young adult patients with pump therapy which are associated with discontinuation of treatment. Retrospective cohort study using a representative nationwide database (LRx; IMS Health) in Germany covering >80% of all prescriptions to members of statutory health insurances in 2008-2011. All patients (age group insulin pumps were identified (2009-2010) and were followed for 12 months. Overall, 2452 new pump users were identified, of whom 177 (7.2%) switched to other forms of insulin therapy within 12 months. In multivariate logistic regression, younger age (pump discontinuation. A non-significant trend was found for male sex (OR, 95% CI: 0.75; 0.52-1.08). Prescriptions of thyroid therapeutics (ATC H03A: OR, 95% CI: 1.79; 1.23-2.61) and antiepileptics (N03: OR, 95% CI: 3.14; 1.49-6.59) were significantly associated with discontinuation of pump therapy. About 93% of pediatric and young adult patients maintained insulin pump therapy within 12 months. Age insulin pump treatment. Copyright © 2014 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.
The use of discontinuities and functional groups to assess relative resilience in complex systems
Allen, C.R.; Gunderson, Lance; Johnson, A.R.
2005-01-01
It is evident when the resilience of a system has been exceeded and the system qualitatively changed. However, it is not clear how to measure resilience in a system prior to the demonstration that the capacity for resilient response has been exceeded. We argue that self-organizing human and natural systems are structured by a relatively small set of processes operating across scales in time and space. These structuring processes should generate a discontinuous distribution of structures and frequencies, where discontinuities mark the transition from one scale to another. Resilience is not driven by the identity of elements of a system, but rather by the functions those elements provide, and their distribution within and across scales. A self-organizing system that is resilient should maintain patterns of function within and across scales despite the turnover of specific elements (for example, species, cities). However, the loss of functions, or a decrease in functional representation at certain scales will decrease system resilience. It follows that some distributions of function should be more resilient than others. We propose that the determination of discontinuities, and the quantification of function both within and across scales, produce relative measures of resilience in ecological and other systems. We describe a set of methods to assess the relative resilience of a system based upon the determination of discontinuities and the quantification of the distribution of functions in relation to those discontinuities. ?? 2005 Springer Science+Business Media, Inc.
Influence of the foreshock on propagation of upstream discontinuities toward the magnetosphere
Urbar, Jaroslav; Nemecek, Zdenek; Safrankova, Jana; Prech, Lubomir; Jelinek, Karel
Interplanetary shocks and other major solar wind discontinuities have been recognized as a very efficient source of geomagnetic disturbances and many studies have been devoted to the interaction of these discontinuities with both characteristic magnetospheric boundaries: the bow shock and magnetopause. However, an influence of the foreshock as a region with param-eters significantly different from those of the undisturbed solar wind was not discussed up to now. Non-stationarity of this region and interactions occurring there requires multi-spacecraft observations with a good spatial and temporal coverage. We use a large set of spacecraft orbiting in the solar wind (SOHO, Wind, ACE) and near the bow shock vicinity (Cluster II, Themis) and investigate what quantity controls the evolution and propagation of solar wind disturbances through the foreshock, bow shock and magnetosheath. Into the study, we included an inclination of the discontinuity normal from the Sun-Earth line that determines the propagation of the discontinuity along the bow shock surface as well as the direction of the motional electric field that can concentrate foreshock energetic particles at the discontinuity plane. These particles excite waves of large amplitudes that can modify not only the disturbance parameters but also mean values of parameters measured in an un-perturbed solar wind.
A Level Set Discontinuous Galerkin Method for Free Surface Flows - and Water-Wave Modeling
Grooss, Jesper
2005-01-01
We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by a level set technique. We describe the discontinuous Galerkin method in general, and its application to the flow equations....... accurately. We present techniques for reinitialization, and outline the strengths and weaknesses of the level set method. Through a few numerical tests, the robustness and versatility of the proposed scheme is confirmed.......We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by a level set technique. We describe the discontinuous Galerkin method in general, and its application to the flow equations....... The deferred correction method is applied on the fluid flow equations and show good results in periodic domains. We describe the design of a level set method for the free surface modeling. The level set utilize the high order accurate discontinuous Galerkin method fully and represent smooth surfaces very...
Modelling the Shear Behaviour of Clean Rock Discontinuities Using Artificial Neural Networks
Dantas Neto, Silvrano Adonias; Indraratna, Buddhima; Oliveira, David Américo Fortuna; de Assis, André Pacheco
2017-07-01
Since the mechanical behaviour of rock masses is influenced by the shear behaviour of their discontinuities, analytical models are being developed to describe the shear behaviour of rock discontinuities. The aim of this paper is to present a model to predict the shear behaviour of clean rock discontinuities developed by using artificial neural networks (ANN), as an alternative to the existing analytical models which sometimes require certain parameters obtained from large-scale laboratory tests which are not always available. Results from direct shear tests on different boundary conditions and types of discontinuities have been used to develop this ANN model, whose input parameters contain the boundary normal stiffness, the initial normal stress, the joint roughness coefficient, the compressive strength of the intact rock, the basic friction angle and the horizontal displacement of a joint. This proposed ANN model fits the experimental data better than some existing analytical models, and it can satisfactorily describe how governing parameters influence the shear behaviour of clean rock discontinuities. This paper also presents a practical application where the proposed ANN model is used to analyse the stability of a rock slope.
R. M. Tikhilov
2016-01-01
Full Text Available Revision hip arthroplasty rate is growing, and pelvic discontinuity rate ranges from 1% to 5% of acetabular component revision reasons. According to AAOS acetabular defects classification, pelvic discontinuity is fourth type defect in which cranial part of hip bone is separated from caudal part at acetabular level. Usually it occurs from bone loss secondary to osteolysis, infection, fracture or aseptic loosening. There are a lot of techniques for pelvis discontinuity treatment. Published results of bulk allografts and antiprotrusion cages have generally been poor. More preferable methods with acceptable rate of good results are cup-cage systems and custom triflange acetabular components(CTAC. CTACs are designed based on preoperative CT scans to build a custom titanium 3D-printed implant to address the patient's specific bone defect and provide secure fixation in the ilium, pubis, and ischium. We faced pelvic discontinuity, in which extensive iliac bone loss was added to caudal hip bone part medial displacement and pelvic ring deformity, in patient with multiple hip surgeries. Preoperative investigation called into question the possibility of using off-the-shelf hip implants, which could restore the biomechanics of the hip and provide reliable primary fixation at the same time. We present case report of the patient with pelvic discontinuity and massive bone loss treatment using a custom triflange component.
Yu, Caixia; Zhao, Jingtao; Wang, Yanfei
2017-02-01
Studying small-scale geologic discontinuities, such as faults, cavities and fractures, plays a vital role in analyzing the inner conditions of reservoirs, as these geologic structures and elements can provide storage spaces and migration pathways for petroleum. However, these geologic discontinuities have weak energy and are easily contaminated with noises, and therefore effectively extracting them from seismic data becomes a challenging problem. In this paper, a method for detecting small-scale discontinuities using dictionary learning and sparse representation is proposed that can dig up high-resolution information by sparse coding. A K-SVD (K-means clustering via Singular Value Decomposition) sparse representation model that contains two stage of iteration procedure: sparse coding and dictionary updating, is suggested for mathematically expressing these seismic small-scale discontinuities. Generally, the orthogonal matching pursuit (OMP) algorithm is employed for sparse coding. However, the method can only update one dictionary atom at one time. In order to improve calculation efficiency, a regularized version of OMP algorithm is presented for simultaneously updating a number of atoms at one time. Two numerical experiments demonstrate the validity of the developed method for clarifying and enhancing small-scale discontinuities. The field example of carbonate reservoirs further demonstrates its effectiveness in revealing masked tiny faults and small-scale cavities.
SpECTRE: A Task-based Discontinuous Galerkin Code for Relativistic Astrophysics
Kidder, Lawrence E; Foucart, Francois; Schnetter, Erik; Teukolsky, Saul A; Bohn, Andy; Deppe, Nils; Diener, Peter; Hébert, François; Lippuner, Jonas; Miller, Jonah; Ott, Christian D; Scheel, Mark A; Vincent, Trevor
2016-01-01
We introduce a new relativistic astrophysics code, SpECTRE, that combines a discontinuous Galerkin method with a task-based parallelism model. SpECTRE's goal is to achieve more accurate solutions for challenging relativistic astrophysics problems such as core-collapse supernovae and binary neutron star mergers. The robustness of the discontinuous Galerkin method allows for the use of high-resolution shock capturing methods in regions where (relativistic) shocks are found, while exploiting high-order accuracy in smooth regions. A task-based parallelism model allows efficient use of the largest supercomputers for problems with a heterogeneous workload over disparate spatial and temporal scales. We argue that the locality and algorithmic structure of discontinuous Galerkin methods will exhibit good scalability within a task-based parallelism framework. We demonstrate the code on a wide variety of challenging benchmark problems in (non)-relativistic (magneto)-hydrodynamics. We demonstrate the code's scalability i...
BEHAVIORAL ASPECTS IN COMMUNITY ORAL HEALTH PROBLEMS: A STUDY ON DENTAL TREATMENT DISCONTINUATION
Felix Aryadi Joelimar
2015-08-01
Full Text Available The low value of F/DMF-T ration on Performed Treatment Index in Indoneisa gives an indication of great problems in dental treatment utilization. Dental treatment utilization is affected by several obstacles, the greatest among which is psychosocial obstacles. In this study the psychosocial obstacles were detected through Intrinsic Obstacles, Obstacles in Transportation, and Obstacles in Dental Clinic related to their effects on their discontinuation of dental treatments at Balkesmas Kiara, Kecamatan Senen, Jakarta Pusat. The discontinuation of dental treatments was mostly affected by Intrinsic Obstacles, through its components as Types of Cases, Dental Anxiety Scale, and Intrinsic Motivation. Generally Obstacles in Transportation had no effects, excpet its components of Travel Time and Tiredness. Obstacles in Dental Clinic had a significant effect on the discontinuation of dental treatments through the unpleasant manner of the druggist, the hot waiting room, and the high expense on drugs.
Interactions between discontinuities for binary mixture separation problem and hodograph method
Elaeva, M S; Yu, Zhukov M
2016-01-01
The Cauchy problem for first-order PDE with the initial data which have a piecewise discontinuities localized in different spatial points is completely solved. The interactions between discontinuities arising after breakup of initial discontinuities are studied with the help of the hodograph method. The solution is constructed in analytical implicit form. To recovery the explicit form of solution we propose the transformation of the PDEs into some ODEs on the level lines (isochrones) of implicit solution. In particular, this method allows us to solve the Goursat problem with initial data on characteristics. The paper describes a specific problem for zone electrophoresis (method of the mixture separation). However, the method proposed allows to solve any system of two first-order quasilinear PDEs for which the second order linear PDE, arising after the hodograph transformation, has the Riemann-Green function in explicit form.
Refinement of a discontinuity-free edge-diffraction model describing focused wave fields.
Sedukhin, Andrey G
2010-03-01
Two equivalent forms of a refined discontinuity-free edge-diffraction model describing the structure of a stationary focused wave field are presented that are valid in the framework of the scalar Debye integral representation for a diffracted rotationally symmetric converging spherical wave of a limited yet not-too-low angular opening. The first form describes the field as the sum of a direct quasi-spherical wave and a plurality of edge quasi-conical waves of different orders, the optimum discontinuity-free angular spectrum functions of all the waves being dependent on the polar angle only. According to the second form, the focused field is fully characterized by only three components--the same quasi-spherical wave and two edge quasi-conical waves of the zero and first order, of which the optimum discontinuity-free angular spectrum functions are dependent on both the polar angle and the polar radius counted from the geometrical focus.
Ranatunga, Vipul; Bednarcyk, Brett A.; Arnold, Steven M.
2010-01-01
A method for performing progressive damage modeling in composite materials and structures based on continuum level interfacial displacement discontinuities is presented. The proposed method enables the exponential evolution of the interfacial compliance, resulting in unloading of the tractions at the interface after delamination or failure occurs. In this paper, the proposed continuum displacement discontinuity model has been used to simulate failure within both isotropic and orthotropic materials efficiently and to explore the possibility of predicting the crack path, therein. Simulation results obtained from Mode-I and Mode-II fracture compare the proposed approach with the cohesive element approach and Virtual Crack Closure Techniques (VCCT) available within the ABAQUS (ABAQUS, Inc.) finite element software. Furthermore, an eccentrically loaded 3-point bend test has been simulated with the displacement discontinuity model, and the resulting crack path prediction has been compared with a prediction based on the extended finite element model (XFEM) approach.
High Order Finite Difference Schemes for the Elastic Wave Equation in Discontinuous Media
Virta, Kristoffer
2013-01-01
Finite difference schemes for the simulation of elastic waves in materi- als with jump discontinuities are presented. The key feature is the highly accurate treatment of interfaces where media discontinuities arise. The schemes are constructed using finite difference operators satisfying a sum- mation - by - parts property together with a penalty technique to impose interface conditions at the material discontinuity. Two types of opera- tors are used, termed fully compatible or compatible. Stability is proved for the first case by bounding the numerical solution by initial data in a suitably constructed semi - norm. Numerical experiments indicate that the schemes using compatible operators are also stable. However, the nu- merical studies suggests that fully compatible operators give identical or better convergence and accuracy properties. The numerical experiments are also constructed to illustrate the usefulness of the proposed method to simulations involving typical interface phenomena in elastic materials...
Hakho HONG
2016-01-01
The zero dissipation limit to the contact discontinuities for one-dimensional com-pressible Navier-Stokes equations was recently proved for ideal polytropic gas (see Huang et al. [15, 22] and Ma [31]), but there is few result for general gases including ideal polytropic gas. We prove that if the solution to the corresponding Euler system of general gas satisfying (1.4) is piecewise constant with a contact discontinuity, then there exist smooth solutions to Navier-Stokes equations which converge to the inviscid solutions at a rate of κ14 as the heat-conductivity coeff cient κtends to zero. The key is to construct a viscous contact wave of general gas suitable to our proof (see Section 2). Notice that we have no need to restrict the strength of the contact discontinuity to be small.
Vismodegib persistence and discontinuation patterns in Greek patients from a real world setting.
Soura, Efthymia; Plaka, Michaela; Chasapi, Vasiliki; Antoniou, Christina; Stratigos, Alexander
2017-10-04
Hedghehog pathway inhibitors have been successfully used for patients with locally advanced basal cell carcinomas. However, these treatments have been associated with various adverse events that may limit patient compliance. In this study, an association of patient and disease characteristics with drug compliance in a real clinical setting was made. 18 patients were included in the study. The average patient age was 78.39 years. The time that patients remained to treatment was, on average, 8.73 months. 72.2% of patients experienced at least one adverse event. At study cut-off, 11 out of 18 patients had discontinued treatment. The most common reason for discontinuation was reported "fatigue" from the treatment due to the type of AEs experienced (37.4%) and patient's choice after complete response achievement (30.8%). Factors that were associated with treatment discontinuation was: number of previous treatments, severity of AEs and patient age. © 2017 Wiley Periodicals, Inc.
A Level Set Discontinuous Galerkin Method for Free Surface Flows - and Water-Wave Modeling
Grooss, Jesper
2005-01-01
We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by a level set technique. We describe the discontinuous Galerkin method in general, and its application to the flow equations....... The deferred correction method is applied on the fluid flow equations and show good results in periodic domains. We describe the design of a level set method for the free surface modeling. The level set utilize the high order accurate discontinuous Galerkin method fully and represent smooth surfaces very...... equations in time are discussed. We investigate theory of di erential algebraic equations, and connect the theory to current methods for solving the unsteady fluid flow equations. We explore the use of a semi-implicit spectral deferred correction method having potential to achieve high temporal order...
Shang, J.; Hencher, S. R.; West, L. J.
2016-11-01
Geological discontinuities have a controlling influence for many rock-engineering projects in terms of strength, deformability and permeability, but their characterisation is often very difficult. Whilst discontinuities are often modelled as lacking any strength, in many rock masses visible rock discontinuities are only incipient and have tensile strength that may approach and can even exceed that of the parent rock. This fact is of high importance for realistic rock mass characterisation but is generally ignored. It is argued that current ISRM and other standards for rock mass characterisation, as well as rock mass classification schemes such as RMR and Q, do not allow adequately for the incipient nature of many rock fractures or their geological variability and need to be revised, at least conceptually. This paper addresses the issue of the tensile strength of incipient discontinuities in rock and presents results from a laboratory test programme to quantify this parameter. Rock samples containing visible, natural incipient discontinuities including joints, bedding, and mineral veins have been tested in direct tension. It has been confirmed that such discontinuities can have high tensile strength, approaching that of the parent rock. Others are, of course, far weaker. The tested geological discontinuities all exhibited brittle failure at axial strain less than 0.5 % under direct tension conditions. Three factors contributing to the tensile strength of incipient rock discontinuities have been investigated and characterised. A distinction is made between sections of discontinuity that are only partially developed, sections of discontinuity that have been locally weathered leaving localised residual rock bridges and sections that have been `healed' through secondary cementation. Tests on bedding surfaces within sandstone showed that tensile strength of adjacent incipient bedding can vary considerably. In this particular series of tests, values of tensile strength
Argemi, X; Albrecht, M; Hansmann, Y; Jaulhac, B; Koebel, C; Schramm, F
2015-10-01
Our aim was to evaluate the criteria required to discontinue airborne precautions for patients presenting with sputum smear-positive pulmonary tuberculosis as the need for sputum smear examinations is still a matter of debate. We conducted a retrospective study in the University Hospitals of Strasbourg (France) from July 2011 to July 2013. Our aim was to describe the results of sputum smear examinations and cultures obtained from treated patients presenting with drug-sensitive pulmonary tuberculosis. We included 97 patients in the study. Nearly half of patients for whom a sputum smear examination was performed had a negative sputum direct examination but a positive culture. According to the literature, those patients are still likely to be contagious. This questions the safety of discontinuing airborne precautions in this situation. We also observed a great disparity in physicians' behaviors. Only half of them waited to get a negative sputum direct examination before discontinuing airborne precautions. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
Duru, Kenneth
2014-12-01
© 2014 Elsevier Inc. In this paper, we develop a stable and systematic procedure for numerical treatment of elastic waves in discontinuous and layered media. We consider both planar and curved interfaces where media parameters are allowed to be discontinuous. The key feature is the highly accurate and provably stable treatment of interfaces where media discontinuities arise. We discretize in space using high order accurate finite difference schemes that satisfy the summation by parts rule. Conditions at layer interfaces are imposed weakly using penalties. By deriving lower bounds of the penalty strength and constructing discrete energy estimates we prove time stability. We present numerical experiments in two space dimensions to illustrate the usefulness of the proposed method for simulations involving typical interface phenomena in elastic materials. The numerical experiments verify high order accuracy and time stability.
Fernandez, Pablo; Roca, Xevi; Peraire, Jaime
2016-01-01
We present a high-order implicit large-eddy simulation (ILES) approach for simulating transitional turbulent flows. The approach consists of an Interior Embedded Discontinuous Galerkin (IEDG) method for the discretization of the compressible Navier-Stokes equations and a parallel preconditioned Newton-GMRES solver for the resulting nonlinear system of equations. The IEDG method arises from the marriage of the Embedded Discontinuous Galerkin (EDG) method and the Hybridizable Discontinuous Galerkin (HDG) method. As such, the IEDG method inherits the advantages of both the EDG method and the HDG method to make itself well-suited for turbulence simulations. We propose a minimal residual Newton algorithm for solving the nonlinear system arising from the IEDG discretization of the Navier-Stokes equations. The preconditioned GMRES algorithm is based on a restricted additive Schwarz (RAS) preconditioner in conjunction with a block incomplete LU factorization at the subdomain level. The proposed approach is applied to...
Simulating diffusion processes in discontinuous media: A numerical scheme with constant time steps
Lejay, Antoine, E-mail: Antoine.Lejay@iecn.u-nancy.fr [Universite de Lorraine, IECN, UMR 7502, Vandoeuvre-les-Nancy, F-54500 (France); CNRS, IECN, UMR 7502, Vandoeuvre-les-Nancy, F-54500 (France); Inria, Villers-les-Nancy, F-54600 (France); IECN, BP 70238, F-54506 Vandoeuvre-les-Nancy Cedex (France); Pichot, Geraldine, E-mail: Geraldine.Pichot@inria.fr [Inria, Rennes - Bretagne Atlantique, Campus de Beaulieu, 35042 Rennes Cedex (France); INRIA, Campus de Beaulieu, 35042 Rennes Cedex (France)
2012-08-30
In this article, we propose new Monte Carlo techniques for moving a diffusive particle in a discontinuous media. In this framework, we characterize the stochastic process that governs the positions of the particle. The key tool is the reduction of the process to a Skew Brownian motion (SBM). In a zone where the coefficients are locally constant on each side of the discontinuity, the new position of the particle after a constant time step is sampled from the exact distribution of the SBM process at the considered time. To do so, we propose two different but equivalent algorithms: a two-steps simulation with a stop at the discontinuity and a one-step direct simulation of the SBM dynamic. Some benchmark tests illustrate their effectiveness.
Multistability of complex-valued neural networks with discontinuous activation functions.
Liang, Jinling; Gong, Weiqiang; Huang, Tingwen
2016-12-01
In this paper, based on the geometrical properties of the discontinuous activation functions and the Brouwer's fixed point theory, the multistability issue is tackled for the complex-valued neural networks with discontinuous activation functions and time-varying delays. To address the network with discontinuous functions, Filippov solution of the system is defined. Through rigorous analysis, several sufficient criteria are obtained to assure the existence of 25(n) equilibrium points. Among them, 9(n) points are locally stable and 16(n)-9(n) equilibrium points are unstable. Furthermore, to enlarge the attraction basins of the 9(n) equilibrium points, some mild conditions are imposed. Finally, one numerical example is provided to illustrate the effectiveness of the obtained results.
Lisitsa, Vadim, E-mail: lisitsavv@ipgg.sbras.ru [Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Tcheverda, Vladimir [Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk (Russian Federation); Kazakh–British Technical University, Alma-Ata (Kazakhstan); Botter, Charlotte [University of Stavanger (Norway)
2016-04-15
We present an algorithm for the numerical simulation of seismic wave propagation in models with a complex near surface part and free surface topography. The approach is based on the combination of finite differences with the discontinuous Galerkin method. The discontinuous Galerkin method can be used on polyhedral meshes; thus, it is easy to handle the complex surfaces in the models. However, this approach is computationally intense in comparison with finite differences. Finite differences are computationally efficient, but in general, they require rectangular grids, leading to the stair-step approximation of the interfaces, which causes strong diffraction of the wavefield. In this research we present a hybrid algorithm where the discontinuous Galerkin method is used in a relatively small upper part of the model and finite differences are applied to the main part of the model.
Dao-qi Yang; Jennifer Zhao
2003-01-01
An iterative algorithm is proposed and analyzed based on a hybridized mixed finite element method for numerically solving two-phase generalized Stefan interface problems withstrongly discontinuous solutions, conormal derivatives, and coefficients. This algorithmiteratively solves small problems for each single phase with good accuracy and exchangeinformation at the interface to advance the iteration until convergence, following the ideaof Schwarz Alternating Methods. Error estimates are derived to show that this algorithmalways converges provided that relaxation parameters are suitably chosen. Numeric experiments with matching and non-matching grids at the interface from different phases areperformed to show the accuracy of the method for capturing discontinuities in the solutionsand coefficients. In contrast to standard numerical methods, the accuracy of our methoddoes not seem to deteriorate as the coefficient discontinuity increases.
Continuation versus discontinuation of oxytocin in the active phase of labour
Bor, Isil Pinar; Ledertoug, Susanne; Boie, Sidsel;
2016-01-01
OBJECTIVE: To investigate whether discontinuation of oxytocin infusion increases the duration of the active phase of labour and reduces maternal and neonatal complications. DESIGN: Randomised controlled trial. SETTING: Department of Obstetrics and Gynaecology, Regional Hospital of Randers, Denmark....... POPULATION: Women with singleton pregnancy in the vertex position undergoing labour induction or augmentation. METHODS: Two hundred women were randomised when cervical dilation was ≤4 cm to either continue or discontinue oxytocin infusion when cervical dilation reached 5 cm. MAIN OUTCOME MEASURES......). The incidence of fetal heart rate abnormalities (51 versus 20%) and uterine hyperstimulation (12 versus 2%) was significantly greater in the continued than the discontinued oxytocin group. The incidence of tachysystole, caesarean deliveries, postpartum haemorrhage, third degree perineal tears and adverse...
Kolmogorov, Dmitry; Sørensen, Niels N.; Shen, Wen Zhong;
2013-01-01
An Optimized Schwarz method using Robin boundary conditions for relaxation scheme is presented in the frame of Multigrid method on discontinuous grids. At each iteration the relaxation scheme is performed in two steps: one step with Dirichlet and another step with Robin boundary conditions at inner...... block boundaries. A Robin parameter that depends on grid geometry and grid discontinuity at block interfaces is introduced. The general solution algorithm is based on SIMPLE method and a conservative _nite-volume scheme on block-structured grids with discontinuous interfaces. The multigrid method...... is used to obtain the solution of pressure-correction equation where an Incomplete Block LU factorization is used as the relaxation scheme. Solution on the coarsest grid is done with an Incomplete Block LU preconditioned Conjugate Gradient method. Results from computations of laminar ows around a circular...
A Prelude Staircase to a Type V Intermittency in Two-Dimensional Discontinuous Maps
WANG Xu-Ming; ZHAO Jin-Gang; HE Da-Ren
2003-01-01
A sequence of periodic attractors has been observed in a two-dimensional discontinuous map, which canbe considered as a model of impact oscillator. The so-called "transfer number", which is defined as the mean numberof transfer from non-impact state to impact state per iteration, is locked onto a lot of rational values to form a curveconsisting of many steps. Our numerical investigation confirms that every step is confined by conditions created by thecollision between the periodic orbit and the discontinuous boundary of the system. After the last collision the systemshows a chaotic motion with intermittent characteristics. Therefore the staircase can be addressed as a "prelude staircaseto type V intermittency". The similar phenomenon has also been observed in a model of electric circuit. These resultsof our study suggest that this kind of staircases is common in two (or even higher) dimensional discontinuous maps.
Liu, Xiaoyang; Yu, Wenwu; Cao, Jinde; Chen, Shun
2015-08-01
This paper is concerned with the sampled-data state estimation and H(∞) filtering for a class of Markovian jump systems with the discontinuous Lyapunov approach. The system measurements are sampled and then transmitted to the estimator and filter in order to estimate the state of the jumped system under consideration. The corresponding error dynamics is represented by a system with two types of delays: one is from the system itself, and the other from the sampling period. As the delay due to sampling is discontinuous, a corresponding discontinuous Lyapunov functional is constructed, and sufficient conditions are established so as to guarantee both the asymptotic mean-square stability and the H(∞) performance for the filtering error systems. The explicit expressions of the desired estimator and filter are further provided. Finally, two simulation examples are given to illustrate the design procedures and performances of the proposed method.
LI Xikui; YAO Dongmei
2004-01-01
A time-discontinuous Galerkin finite element method for dynamic analyses in saturated poro-elasto-plastic medium is proposed. As compared with the existing discontinuous Galerkin finite element methods, the distinct feature of the proposed method is that the continuity of the displacement vector at each discrete time instant is automatically ensured, whereas the discontinuity of the velocity vector at the discrete time levels still remains. The computational cost is then obviously reduced,particularly, for material non-linear problems. Both the implicit and explicit algorithms to solve the derived formulations for material non-linear problems are developed. Numerical results show a good performance of the present method in eliminating spurious numerical oscillations and providing with much more accurate solutions over the traditional Galerkin finite element method using the Newmark algorithm in the time domain.
Nie, Xiaobing; Zheng, Wei Xing
2015-11-01
In this paper, we discuss the coexistence and dynamical behaviors of multiple equilibrium points for recurrent neural networks with a class of discontinuous nonmonotonic piecewise linear activation functions. It is proved that under some conditions, such n -neuron neural networks can have at least 5(n) equilibrium points, 3(n) of which are locally stable and the others are unstable, based on the contraction mapping theorem and the theory of strict diagonal dominance matrix. The investigation shows that the neural networks with the discontinuous activation functions introduced in this paper can have both more total equilibrium points and more locally stable equilibrium points than the ones with continuous Mexican-hat-type activation function or discontinuous two-level activation functions. An illustrative example with computer simulations is presented to verify the theoretical analysis.
Kamal-Bahl, Sachin J; Burke, Thomas; Watson, Douglas; Wentworth, Chuck
2007-02-15
Although several lipid-modifying drug (LMD) treatments and strategies are available to successfully manage patients at risk for cardiovascular events, the benefits of drug treatment can be realized only if these therapies are continued on a long-term basis. Previous observational studies examining rates of discontinuation with LMDs are not generalizable to current clinical practice in the United States. In this study, the discontinuation of newly initiated LMD classes in recent clinical practice was compared in a geographically diverse, commercially insured United States population. Administrative claims from the Ingenix Lab/Rx Database were used to identify patients aged >or=20 years who were newly prescribed statins, extended-release niacin, fibrates, bile acid sequestrants, or ezetimibe from January 1, 2001, to June 30, 2003. An LMD class was considered discontinued if a patient did not receive a prescription from the same LMD class within 180 days of the most recent prescription expiration date. The median time to discontinuation was 8.2 months in the bile acid sequestrant group, followed by 12 months in the extended-release niacin group, 17.4 months in the fibrate group, and 27.5 months in the statin group. By the end of 1 year, the adjusted cumulative incidence of discontinuation was 68.3% in bile acid sequestrant users, 55.4% in extended-release niacin users, 39.9% in fibrate users, 33.0% in ezetimibe users, and 28.9% in statin users (p LMD classes vs statins). In conclusion, despite the changes in lipid treatment paradigms and the importance of long-term lipid therapy, this study found high discontinuation rates of LMD classes in recent United States clinical practice.
Kalder, Matthias; Pantazis, Konstantinos; Dinas, Konstantinos; Albert, Ute-Susann; Heilmaier, Christina; Kostev, Karel
2014-10-01
To evaluate the discontinuation rates of anticholinergics prescribed in patients with urinary incontinence (UI). Data from a Disease Analyzer database including 988 general, 95 urologist, and 203 gynecologic practices were examined. Twenty six thousand eight hundred thirty-four patients were identified as having received a first-time anticholinergic prescription for UI, namely darifenacin, fesoterodine, oxybutynin, propiverine, solifenacin, tolterodine, or trospium, between 2005 and 2012. Covariates studied included demographic data, concomitant diagnoses, and potential drug-induced side effects. The cumulative discontinuation rate of initial treatment was estimated using a Kaplan-Meier analysis. A Cox proportional hazard regression model was used to estimate the relationship between discontinuation and the demographic and clinical variables for up to 36 months. An increasing discontinuation rate was observed in years 1, 2, and 3 (74.8%, 77.6%, 87%). Within 3 years, discontinuation rates were higher for men than for women (87.9%, 86.5%; P=.056; hazard ratio [HR] 1.14, 95% confidence interval [CI] 1.11-1.18; Ppractices and general practices than those treated in urologist practices (HR 1.60; 95% CI 1.52-1.67, PHR 1.24, 95% CI 1.20-1.29, PHR 1.27, 95% CI 1.22-1.33; 61-70 years, HR 1.16, 95% CI 1.11-1.21; 71-80 years, HR 1.14, 95% CI 1.09-1.18, PHR 0.94, 95% CI 0.88-0.99, P=.024 and HR 0.93, 95% CI 0.87-0.98, P=.004, respectively). Patients with UI demonstrate high discontinuation rates for anticholinergics with only slight variations between the various drugs in this category. : III.
Balasubramanian A
2013-11-01
Full Text Available Akhila Balasubramanian,1 M Alan Brookhart,2 Vamshidar Goli1 Cathy W Critchlow1 1Amgen Inc, Thousand Oaks, CA, USA; 2University of North Carolina at Chapel Hill, Chapel Hill, NC, USAObjective: Poor adherence to chronic medications is common and compromises medication effectiveness. We sought to describe longitudinal patterns of osteoporosis medication use.Study design: This was a retrospective observational cohort study using 2005–2009 data from a large, commercially insured population.Methods: Patients were women aged ≥55 years initiating osteoporosis therapy who had a ≥12-month (baseline period with no osteoporosis therapy claims preceding initiation, and ≥24 months follow-up after therapy initiation. Discontinuation was defined as a gap >60 days (varied in sensitivity analyses in prescription claims. Reinitiation was defined as a prescription claim for the same or different osteoporosis therapy following the therapy gap. Discontinuation and reinitiation patterns were described using Kaplan–Meier analysis. Multivariable Cox regression assessed the impact of baseline factors on reinitiation.Results: Of the 92,839 patients, 45%, 58%, and 70% discontinued therapy at 6, 12, and 24 months, respectively, following initiation. Of the discontinuers, 46% reinitiated therapy, with the majority doing so within 6 months of discontinuation. Women were less likely to reinitiate therapy if they were older (P < 0.0001 or were hospitalized during baseline (P = 0.0007. Women who discontinued treatment early (<6 months following initiation were less likely to reinitiate (P < 0.0001 and remained on therapy for shorter periods following reinitiation. Depending on the available observation time, the median time on therapy following reinitiation was 58–193 days. Study findings did not change appreciably in sensitivity analyses.Conclusion: Many patients stop and restart treatment for osteoporosis. A better understanding of determinants of treatment
Beeftink, Martine M A; van der Sande, Nicolette G C; Bots, Michiel L; Doevendans, Pieter A; Blankestijn, Peter J; Visseren, Frank L J; Voskuil, Michiel; Spiering, Wilko
2017-05-01
Successful control of blood pressure relies on identification of secondary causes and contributing factors of hypertension. As antihypertensive medication can interfere with diagnostic investigations, temporary discontinuation of medication is advised. However, there are concerns about the safety of temporary discontinuation of antihypertensive medication in patients with difficult-to-control hypertension. We assessed the occurrence of adverse cardiovascular and cerebrovascular events potentially attributable to temporary discontinuation of antihypertensive medication between February 2010 and March 2016 (n=604) in our Analysis of Complicated Hypertension screening program. A reference group (n=604) was extracted from the SMART study (Second Manifestations of Arterial Disease) cohort (comprising a similar cohort at our hospital in whom medication was not stopped) and individually matched for blood pressure, age, sex, and history of cardiovascular disease. Discontinuation of medication was well tolerated; 62% reported no complaints, 24% had mild discomfort that could be left untreated, and 14% experienced complaints that required prescription of antihypertensive escape medication. Three major adverse events were observed in the Analysis of Complicated Hypertension group between discontinuation of medication and 30 days after restart of medication (event rate=31.2 events per 1000 patient-year). In the reference cohort, 5 cardiovascular events were observed during a similar follow-up period (event rate=51.2 events per 1000 patient-year). In conclusion, discontinuation of antihypertensive medication for the diagnostic evaluation of hypertension does not increase the acute risk of cardiovascular events when performed in a well-controlled setting in specialized hospitals with appropriate protocols for monitoring safety. © 2017 American Heart Association, Inc.
Schmerr, N. C.; Beghein, C.; Kostic, D.; Baldridge, A. M.; West, J. D.; Nittler, L. R.; Bull, A. L.; Montesi, L.; Byrne, P. K.; Hummer, D. R.; Plescia, J. B.; Elkins-Tanton, L. T.; Lekic, V.; Schmidt, B. E.; Elkins, L. J.; Cooper, C. M.; ten Kate, I. L.; Van Hinsbergen, D. J. J.; Parai, R.; Glass, J. B.; Ni, J.; Fuji, N.; McCubbin, F. M.; Michalski, J. R.; Zhao, C.; Arevalo, R. D., Jr.; Koelemeijer, P.; Courtier, A. M.; Dalton, H.; Waszek, L.; Bahamonde, J.; Schmerr, B.; Gilpin, N.; Rosenshein, E.; Mach, K.; Ostrach, L. R.; Caracas, R.; Craddock, R. A.; Moore-Driskell, M. M.; Du Frane, W. L.; Kellogg, L. H.
2015-12-01
Seismic discontinuities within the mantle arise from a wide range of mechanisms, including changes in mineralogy, major element composition, melt content, volatile abundance, anisotropy, or a combination of the above. In particular, the depth and sharpness of upper mantle discontinuities at 410 and 660 km depth are attributed to solid-state phase changes sensitive to both mantle temperature and composition, where regions of thermal heterogeneity produce topography and chemical heterogeneity changes the impedance contrast across the discontinuity. Seismic mapping of this topography and sharpness thus provides constraint on the thermal and compositional state of the mantle. The EarthScope USArray is providing unprecedented access to a wide variety of new regions previously undersampled by the SS precursors. This includes the boundary between the oceanic plate in the western Atlantic Ocean and continental margin of eastern North America. Here we use a seismic array approach to image the depth, sharpness, and topography of the upper mantle discontinuities, as well as other possible upper mantle reflectors beneath this region. This array approach utilizes seismic waves that reflect off the underside of a mantle discontinuity and arrive several hundred seconds prior to the SS seismic phase as precursory energy. In this study, we collected high-quality broadband data SS precursors data from shallow focus (ocean lithosphere to underlying continental lithosphere, as while deeper reflectors are associated with the subduction of the ancient Farallon slab. A comparison of the depth of upper mantle discontinuities to changes in seismic velocity and anisotropy will further quantify the relationship to mantle flow, compositional layering, and phases changes.
Hale, Thomas W; Kendall-Tackett, Kathleen; Cong, Zhen; Votta, Richard; McCurdy, Fred
2010-12-01
This study compared mothers' report of symptoms of discontinuation syndrome in infants exposed to antidepressants both in utero and during lactation to infants who were exposed only during lactation. This is a convenience sample of 930 women breastfeeding women who answered an online questionnaire about antidepressant use while pregnant and breastfeeding. All 930 women had taken antidepressants while breastfeeding, and 527 had also taken antidepressants during pregnancy. There were no participants in the present study who had taken antidepressants only during pregnancy. The questionnaire was posted on the first author's Medications and Breastfeeding Forum. There was no advertising of this study, nor were efforts made to recruit women into this study beyond posting a notice on the website. The questionnaire included a list of symptoms that mothers may have observed in their infants during the newborn period, as well as demographic questions, and questions about antidepressant use during pregnancy and lactation. The majority of women reported that their infants never experienced the symptoms of discontinuation syndrome. Twenty-five percent reported infant irritability. A smaller percentage reported inconsolable crying (17%), low body temperature (14%), and significant problems with eating and sleeping (15%). Logistic regression revealed that mothers who took antidepressants while pregnant and then during breastfeeding were two to eight times more likely to report symptoms of discontinuation syndrome than women who took them only while breastfeeding. Discontinuation symptoms were more likely to occur in infants whose mothers took medications with shorter half-lives. Discontinuation syndrome does occur in a small percentage of infants exposed to antidepressants in utero. Mothers reported a higher frequency of discontinuation syndrome after in utero exposure followed by breastfeeding than when infants were exposed to antidepressants only during lactation.
Duan, Lian; Huang, Lihong; Guo, Zhenyuan
2016-07-01
In this paper, the problems of robust dissipativity and robust exponential dissipativity are discussed for a class of recurrent neural networks with time-varying delay and discontinuous activations. We extend an invariance principle for the study of the dissipativity problem of delay systems to the discontinuous case. Based on the developed theory, some novel criteria for checking the global robust dissipativity and global robust exponential dissipativity of the addressed neural network model are established by constructing appropriate Lyapunov functionals and employing the theory of Filippov systems and matrix inequality techniques. The effectiveness of the theoretical results is shown by two examples with numerical simulations.
Faber-Krahn Inequalities for the Robin-Laplacian: A Free Discontinuity Approach
Bucur, Dorin; Giacomini, Alessandro
2015-11-01
Isoperimetric inequalities for the principal eigenvalues of the Robin-Laplacian are interpreted as free discontinuity problems (of unusual type). We prove a full range of Faber-Krahn inequalities in a nonlinear setting and for non smooth domains, including the open case of the torsional rigidity. The key point of the analysis relies on regularity issues for free discontinuity problems in spaces of functions of bounded variation. As a byproduct, we obtain the best constants for a class of Poincaré inequalities with trace terms in.
Steenholdt, Casper; Molazahi, Akbar; Ainsworth, Mark Andrew
2012-01-01
Abstract Objective. To investigate duration of remission, including risk factors for relapse and response to retreatment with infliximab (IFX), in patients with Crohn's disease (CD) and ulcerative colitis (UC) who had discontinued IFX while in clinical remission. Methods. Observational, single......%) experienced complete clinical remission when retreated with IFX after relapse. Conclusion. While the short-term prognosis seems favorable, the majority of patients who discontinue IFX while in remission relapse over time. The response to retreatment with IFX at relapse seems favorable in this subpopulation....
Ćalasan Martin P.
2013-01-01
Full Text Available This paper presents mechanical characteristics of Switched Reluctance Motor (SRM when it operates in Discontinuous Conduction Mode (DCM or in Continuous Conduction Mode (CCM, i.e. when the current through the phase coils (windings flows discontinuously or continuously. Firstly, in order to maximize the output power of SRM optimization of its control parameters was performed, such that the peak and RMS values of the current do not exceed the predefined values. The optimal control parameters vs. rotation speed, as well as the corresponding characteristics of torque, power and efficiency. It is shown that with CCM the machine torque (power, at high speed, can be increased.
Cuk, S.; Middlebrook, R. D.
1977-01-01
A method for modelling switching converters in the discontinuous conduction mode is developed, whose starting point is the unified state-space representation, and whose end result is a complete linear circuit model which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small signal). While the method is generally applicable to any switching converter operating in the discontinuous conduction mode, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model.
Bolge SC
2015-01-01
Full Text Available Susan C Bolge,1 Amir Goren,2 Neeta Tandon1 1Health Economics and Outcomes Research, Janssen Scientific Affairs, LLC, Horsham, PA, USA; 2Health Outcomes Practice, Kantar Health, New York, NY, USA Objective: To examine reasons why rheumatoid arthritis patients discontinued subcutaneous (SQ anti-tumor necrosis factor (anti-TNF treatment in the past 12 months, so as to help inform successful, uninterrupted therapy.Methods: Data were collected in March and April 2011 using self-reported, internet-based questionnaires. Study inclusion criteria comprised: rheumatoid arthritis diagnosis; discontinuation of SQ anti-TNF medication (adalimumab, certolizumab, etanercept, or golimumab within the past 12 months; aged ≥18 years; United States residency; and consent to participate. Patients reported primary and other reasons for discontinuation of their most recently discontinued anti-TNF.Results: Questionnaires from 250 patients were analyzed; 72.8% were female, 80.8% were white, and median age was 51 years. Patients had discontinued etanercept (n=109, adalimumab (n=98, certolizumab (n=24, or golimumab (n=19 within the past 12 months. When prompted about their primary reason for discontinuation, lack of effectiveness (40.8% was cited most often, followed by injection experience (18.4%. Combining prompted primary and other reasons for discontinuation, 60.8% of patients reported lack of effectiveness, while 40.8% reported injection experience, which included: pain/burning/discomfort after injection (14.4%; pain/burning/discomfort during injection (13.2%; injection reactions such as redness/swelling after injection (12.4%; dislike of self-injection (11.6%; dislike of frequency of injection (10.4%; and fear of injection/needles (6.8%. Conclusion: From the patient perspective, there are unmet needs with regard to the effectiveness and injection experience associated with SQ anti-TNF medications, which may lead to discontinuation. Treatment options with a
A discontinuous Galerkin method for two-dimensional PDE models of Asian options
Hozman, J.; Tichý, T.; Cvejnová, D.
2016-06-01
In our previous research we have focused on the problem of plain vanilla option valuation using discontinuous Galerkin method for numerical PDE solution. Here we extend a simple one-dimensional problem into two-dimensional one and design a scheme for valuation of Asian options, i.e. options with payoff depending on the average of prices collected over prespecified horizon. The algorithm is based on the approach combining the advantages of the finite element methods together with the piecewise polynomial generally discontinuous approximations. Finally, an illustrative example using DAX option market data is provided.
Periodic Orbits for a Discontinuous Vector Field Arising from a Conceptual Model of Glacial Cycles
Walsh, James; Hahn, Jonathan; McGehee, Richard
2015-01-01
Conceptual climate models provide an approach to understanding climate processes through a mathematical analysis of an approximation to reality. Recently, these models have also provided interesting examples of nonsmooth dynamical systems. Here we discuss a conceptual model of glacial cycles consisting of a system of three ordinary differential equations defining a discontinuous vector field. We show that this system has a large periodic orbit crossing the discontinuity boundary. This orbit can be interpreted as an intrinsic cycling of the Earth's climate giving rise to alternating glaciations and deglaciations.
Discontinuous initial value problems for functional differential-algebraic equations of mixed type
d'Albis, H.; Augeraud-Véron, E.; Hupkes, H. J.
We study the well-posedness of initial value problems for nonlinear functional differential-algebraic equations of mixed type. We are interested in solutions to such problems that admit a single jump discontinuity at time zero. We focus specially on the question whether unstable equilibria can be stabilized by appropriately choosing the size of the jump discontinuity. We illustrate our techniques by analytically studying an economic model for the interplay between inflation and interest rates. In particular, we investigate under which circumstances the central bank can prevent runaway inflation by appropriately hiking the interest rate.
On One-Sided Filters for Spectral Fourier Approximations of Discontinuous Functions
1991-03-01
up to the discontinuity from one side. We also use a least square procedure to construct such a filter and test it on several discontinuous functions...thus use a least square procedure, described below, with the objective of obtaining more efficient one-sided filters for a practical range of N...between 8 and 32 (between 16 and 64 grid points for collocation): Least Square Procedure: We make an ansaze { TN ()QykŽ N7 = k (3.1)a k < 0 -k<O where the
Liu, Xiaoyang; Ho, Daniel W C; Cao, Jinde; Xu, Wenying
2016-08-24
This brief investigates the problem of finite-time robust consensus (FTRC) for second-order nonlinear multiagent systems with external disturbances. Based on the global finite-time stability theory of discontinuous homogeneous systems, a novel finite-time convergent discontinuous disturbed observer (DDO) is proposed for the leader-following multiagent systems. The states of the designed DDO are then used to design the control inputs to achieve the FTRC of nonlinear multiagent systems in the presence of bounded disturbances. The simulation results are provided to validate the effectiveness of these theoretical results.
On a problem of reconstruction of a discontinuous function by its Radon transform
Derevtsov, Evgeny Yu.; Maltseva, Svetlana V.; Svetov, Ivan E.; Sultanov, Murat A.
2016-08-01
A problem of reconstruction of a discontinuous function by its Radon transform is considered. One of the approaches to the numerical solution for the problem consists in the next sequential steps: a visualization of a set of breaking points; an identification of this set; a determination of jump values; an elimination of discontinuities. We consider three of listed problems except the problem of jump values. The problems are investigated by mathematical modeling using numerical experiments. The results of simulation are satisfactory and allow to hope for the further development of the approach.
Lanthanides in the study of lithologic discontinuity in soils from the Piracicaba river basin
De Nadai Fernandes, E.A.; Martins Bacchi, F.A. [Sao Paulo Univ., Piracicaba (Brazil). Centro de Energia Nuclear na Agricultura
1998-07-24
This study was designed with the objective of using lanthanides to confirm the occurrence of lithologic discontinuities, formerly highlighted by morphological and mineralogical studies and recognized by field evidence, in three soil profiles from the Piracicaba river basin, Brazil. Comparison of lanthanide concentrations in the horizons and underlying rocks indicated the presence of allochthonous soils. Application of principal component analysis to the measured elements yielded well-defined segregation into groups with cumulative variances higher than 90% for the first two components. Lanthanides were confirmed as versatile indicators to corroborate parent material discontinuities for the soil profiles studied. (orig.) 12 refs.
Safety and Benefit of Discontinuing Statin Therapy in the Setting of Advanced, Life-Limiting Illness
Kutner, Jean S.; Blatchford, Patrick J.; Taylor, Don H.; Ritchie, Christine S.; Bull, Janet H.; Fairclough, Diane L.; Hanson, Laura C.; LeBlanc, Thomas W.; Samsa, Greg P.; Wolf, Steven; Aziz, Noreen M.; Currow, David C.; Ferrell, Betty; Wagner-Johnston, Nina; Zafar, S. Yousuf; Cleary, James F.; Dev, Sandesh; Goode, Patricia S.; Kamal, Arif H.; Kassner, Cordt; Kvale, Elizabeth A.; McCallum, Janelle G.; Ogunseitan, Adeboye B.; Pantilat, Steven Z.; Portenoy, Russell K.; Prince-Paul, Maryjo; Sloan, Jeff A.; Swetz, Keith M.; Von Gunten, Charles F.; Abernethy, Amy P.
2015-01-01
IMPORTANCE For patients with limited prognosis, some medication risks may outweigh the benefits, particularly when benefits take years to accrue; statins are one example. Data are lacking regarding the risks and benefits of discontinuing statin therapy for patients with limited life expectancy. OBJECTIVE To evaluate the safety, clinical, and cost impact of discontinuing statin medications for patients in the palliative care setting. DESIGN, SETTING, AND PARTICIPANTS This was a multicenter, parallel-group, unblinded, pragmatic clinical trial. Eligibility included adults with an estimated life expectancy of between 1 month and 1 year, statin therapy for 3 months or more for primary or secondary prevention of cardiovascular disease, recent deterioration in functional status, and no recent active cardiovascular disease. Participants were randomized to either discontinue or continue statin therapy and were monitored monthly for up to 1 year. The study was conducted from June 3, 2011, to May 2, 2013. All analyses were performed using an intent-to-treat approach. INTERVENTIONS Statin therapy was withdrawn from eligible patients who were randomized to the discontinuation group. Patients in the continuation group continued to receive statins. MAIN OUTCOMES AND MEASURES Outcomes included death within 60 days (primary outcome), survival, cardiovascular events, performance status, quality of life (QOL), symptoms, number of nonstatin medications, and cost savings. RESULTS A total of 381 patients were enrolled; 189 of these were randomized to discontinue statins, and 192 were randomized to continue therapy. Mean (SD) age was 74.1 (11.6) years, 22.0% of the participants were cognitively impaired, and 48.8% had cancer. The proportion of participants in the discontinuation vs continuation groups who died within 60 days was not significantly different (23.8% vs 20.3%; 90% CI, −3.5% to 10.5%; P = .36) and did not meet the noninferiority end point. Total QOL was better for the group
Wu Huaiqin
2009-01-01
Full Text Available This paper considers a new class of additive neural networks where the neuron activations are modelled by discontinuous functions with nonlinear growth. By Leray-Schauder alternative theorem in differential inclusion theory, matrix theory, and generalized Lyapunov approach, a general result is derived which ensures the existence and global asymptotical stability of a unique periodic solution for such neural networks. The obtained results can be applied to neural networks with a broad range of activation functions assuming neither boundedness nor monotonicity, and also show that Forti's conjecture for discontinuous neural networks with nonlinear growth activations is true.
Systems of Quasilinear Parabolic Equations with Discontinuous Coefficients and Continuous Delays
Tan Qi-Jian
2011-01-01
Full Text Available Abstract This paper is concerned with a weakly coupled system of quasilinear parabolic equations where the coefficients are allowed to be discontinuous and the reaction functions may depend on continuous delays. By the method of upper and lower solutions and the associated monotone iterations and by difference ratios method and various estimates, we obtained the existence and uniqueness of the global piecewise classical solutions under certain conditions including mixed quasimonotone property of reaction functions. Applications are given to three 2-species Volterra-Lotka models with discontinuous coefficients and continuous delays.
Duan, Lian; Huang, Lihong; Guo, Zhenyuan
2016-07-01
In this paper, the problems of robust dissipativity and robust exponential dissipativity are discussed for a class of recurrent neural networks with time-varying delay and discontinuous activations. We extend an invariance principle for the study of the dissipativity problem of delay systems to the discontinuous case. Based on the developed theory, some novel criteria for checking the global robust dissipativity and global robust exponential dissipativity of the addressed neural network model are established by constructing appropriate Lyapunov functionals and employing the theory of Filippov systems and matrix inequality techniques. The effectiveness of the theoretical results is shown by two examples with numerical simulations.
Hempert, F.; Hoffmann, M.; Iben, U.; Munz, C.-D.
2016-06-01
In the present investigation, we demonstrate the capabilities of the discontinuous Galerkin spectral element method for high order accuracy computation of gas dynamics. The internal flow field of a natural gas injector for bivalent combustion engines is investigated under its operating conditions. The simulations of the flow field and the aeroacoustic noise emissions were in a good agreement with the experimental data. We tested several shock-capturing techniques for the discontinuous Galerkin scheme. Based on the validated framework, we analyzed the development of the supersonic jets during different opening procedures of a compressed natural gas injector. The results suggest that a more gradual injector opening decreases the noise emission.
Effect of discontinuities in Kohn-Sham-based chemical reactivity theory
Hellgren, M
2012-01-01
We provide a new derivation of a formula for the Fukui function of density-functional chemical reactivity theory which incorporates the discontinuities in the Kohn-Sham reference system. Orbital relaxations are described in terms of the exchange-correlation (XC) kernel, i.e., the derivative of the XC potential with respect to the density and it is shown that in order to correctly measure the reactivity toward a nucleophilic reagent a discontinuity of the XC kernel has to be taken into account. The importance of this finding is illustrated in model molecular systems.
2010-05-12
... Pacific Railroad Company, Mr. William E. Van Trump, AVP Engineering -- Signal/Comm/TCO, 1400 Douglas..., near Chilcoot, California. The modification consists of the discontinuance and removal of...
Ismagilov, Timur Z., E-mail: ismagilov@academ.org
2015-02-01
This paper presents a second order finite volume scheme for numerical solution of Maxwell's equations with discontinuous dielectric permittivity and magnetic permeability on unstructured meshes. The scheme is based on Godunov scheme and employs approaches of Van Leer and Lax–Wendroff to increase the order of approximation. To keep the second order of approximation near dielectric permittivity and magnetic permeability discontinuities a novel technique for gradient calculation and limitation is applied near discontinuities. Results of test computations for problems with linear and curvilinear discontinuities confirm second order of approximation. The scheme was applied to modelling propagation of electromagnetic waves inside photonic crystal waveguides with a bend.
Discontinuous Time Relaxation Method for the Time-Dependent Navier-Stokes Equations
Monika Neda
2010-01-01
is considered. A fully discrete scheme using discontinuous finite elements is proposed and analyzed. Optimal velocity error estimates are derived. The dependence of these estimates with respect to the Reynolds number Re is (ReRe, which is an improvement with respect to the continuous finite element method where the dependence is (ReRe3.
Halpern, Laurence; Japhet, Caroline
2010-01-01
We design and analyze a Schwarz waveform relaxation algorithm for domain decomposition of advection-diffusion-reaction problems with strong heterogeneities. The interfaces are curved, and we use optimized Robin or Ventcell transmission conditions. We analyze the semi-discretization in time with Discontinuous Galerkin as well. We also show two-dimensional numerical results using generalized mortar finite elements in space.
Briel, Matthias; Olu, Kelechi Kalu; von Elm, Erik; Kasenda, Benjamin; Alturki, Reem; Agarwal, Arnav; Bhatnagar, Neera; Schandelmaier, Stefan
2016-12-01
To collect and classify reported reasons for recruitment failure in discontinued randomized controlled trials (RCTs) and to assess reporting quality. We systematically searched MEDLINE and EMBASE (2010-2014) and a previous cohort of RCTs for published RCTs reporting trial discontinuation due to poor recruitment. Teams of two investigators selected eligible RCTs working independently and extracted information using standardized forms. We used an iterative approach to classify reasons for poor recruitment. We included 172 RCTs discontinued due to poor recruitment (including 26 conference abstracts and 63 industry-funded RCTs). Of those, 131 (76%) reported one or more reasons for discontinuation due to poor recruitment. We identified 28 different reasons for recruitment failure; most frequently mentioned were overestimation of prevalence of eligible participants and prejudiced views of recruiters and participants on trial interventions. Few RCTs reported relevant details about the recruitment process such as how eligible participants were identified, the number of patients assessed for eligibility, and who actually recruited participants. Our classification could serve as a checklist to assist investigators in the planning of RCTs. Most reasons for recruitment failure seem preventable with a pilot study that applies the planned informed consent procedure. Copyright © 2016 Elsevier Inc. All rights reserved.
Asymptotically exact Discontinuous Galerkin error estimates for linear symmetric hyperbolic systems
Adjerid, S.; Weinhart, T.
2014-01-01
We present an a posteriori error analysis for the discontinuous Galerkin discretization error of first-order linear symmetric hyperbolic systems of partial differential equations with smooth solutions. We perform a local error analysis by writing the local error as a series and showing that its lead
DISCONTINUOUS GALERKIN FINITE ELEMENT METHOD FOR A FORWARD-BACKWARD HEAT EQUATION
LiHong; WeiXiaoxi
2005-01-01
A space-time finite element method,discontinuous in time but continuous in space, is studied to solve the nonlinear forward-backward heat equation. A linearized technique is introduced in order to obtain the error estimates of the approximate solutions. And the numerical simulations are given.
Shobo, Yetty; Wong, Jen D.; Bell, Angie
2014-01-01
Regression discontinuity (RD), an "as good as randomized," research design is increasingly prominent in education research in recent years; the design gets eligible quasi-experimental designs as close as possible to experimental designs by using a stated threshold on a continuous baseline variable to assign individuals to a…
Carrell, Scott E.; Hoekstra, Mark; West, James E.
2010-01-01
This paper examines the effect of alcohol consumption on student achievement. To do so, we exploit the discontinuity in drinking at age 21 at a college in which the minimum legal drinking age is strictly enforced. We find that drinking causes significant reductions in academic performance, particularly for the highest-performing students. This…
The Implications of Discontinuities for Testing Theories of Turbulence in the Solar Wind
Turner, A J; Gogoberidze, G
2012-01-01
In-situ observations of magnetic field fluctuations in the solar wind show a broad continuum in the power spectral density (PSD) with a power-law range of scaling often identified as an inertial range of magnetohydrodynamic turbulence. However, both turbulence and discontinuities are present in the solar wind on these inertial range of scales. We identify and remove these discontinuities using a method which for the first time does not impose a characteristic scale on the resultant time-series. The PSD of vector field fluctuations obtained from at-a point observations is a tensor that can in principle be anisotropic with scaling exponents that depend on background field and flow direction. This provides a key test of theories of turbulence. We find that the removal of discontinuities from the observed time-series can significantly alter the PSD trace anisotropy. It becomes quasi-isotropic, in that the observed exponent does not vary with the background field angle once the discontinuities are removed. This is...
Stoelhorst, J.W.
2002-01-01
This paper explores the nature of competition under conditions of technological change and asks how firms can manage technological discontinuities. By drawing on the literatures on strategic management and technology dynamics, it is proposed that firms should change the nature of their strategy as a
Lipsey, Mark W.; Weiland, Christina; Yoshikawa, Hirokazu; Wilson, Sandra Jo; Hofer, Kerry G.
2015-01-01
Much of the currently available evidence on the causal effects of public prekindergarten programs on school readiness outcomes comes from studies that use a regression-discontinuity design (RDD) with the age cutoff to enter a program in a given year as the basis for assignment to treatment and control conditions. Because the RDD has high internal…
Gillespie, David; Farewell, Daniel; Brookes-Howell, Lucy; Butler, Christopher C; Coenen, Samuel; Francis, Nick A; Little, Paul; Stuart, Beth; Verheij, Theo; Hood, Kerenza
2017-01-01
Aim To investigate the determinants of adherence to amoxicillin in patients with acute lower respiratory tract infection. Materials and methods Three European data sets were used. Adherence data were collected using self-reported diaries. Candidate determinants included factors relating to patient, condition, therapy, health care system/provider, and the study in which the patient participated. Logistic and Cox regression models were used to investigate the determinants of initiation, implementation, and discontinuation of amoxicillin. Results Although initiation differed across samples, implementation and discontinuation were similar. Determinants of initiation were days waited before consulting, duration of prescription, and being in a country where a doctor-issued sick certificate is required for being off work for <7 days. Implementation was higher for older participants or those with abnormal auscultation. Implementation was lower for those prescribed longer courses of amoxicillin (≥8 days). Time from initiation to discontinuation was longer for longer prescriptions and shorter for those from countries where single-handed practices were widespread. Conclusion Nonadherence to amoxicillin was largely driven by noninitiation. Differing sets of determinants were found for initiation, implementation, and discontinuation. There is a need to further understand the reasons for these determinants, the impact of poor adherence to antibiotics on outcomes, and to develop interventions to improve antibiotic use when prescribed. PMID:28352162
Mandell, Marvin B.
2008-01-01
Both true experiments and regression discontinuity (RD) designs produce unbiased estimates of effects. However, true experiments are, of course, often criticized on equity grounds, whereas RD designs entail sacrifices in terms of statistical precision. In this article, a hybrid of true experiments and RD designs is considered. This hybrid entails…
Gouin, Henri
2008-01-01
The discontinuity of the vorticity is written as a function of the vector T grad s, (where T is the temperature and s the specific entropy). The expression is obtained thanks to potential equations and independently of the mass conservation and the equation of momentum balance.
Women’s attitudes towards discontinuation of female genital mutilation in Egypt
Bjarne Jansson
2010-01-01
Full Text Available BACKGROUND: To examine women’s attitude towards discontinuation of female genital mutilation (FGM in association with their access to information, knowledge of health effects and cultural beliefs concerning FGM in Egypt. METHODS: A cross-sectional study of 9159 women, using data from the household survey in Egypt by Demographic and Health survey 2003. A comprehensive questionnaire covering attitudes towards FGM, demographics, and access to information was used. Chi-square analysis and logistic regression were applied to investigate how demographics, level of education, access to information, knowledge of health consequences and cultural beliefs influence women’s attitudes towards FGM. RESULTS: Among the demographic variables, discontinuation of FGM was independently associated with urban residency and post-secondary education. Moreover, women who were informed by the media, and those who had attended community meetings, church, or mosque where FGM was discussed, as well as women who were aware of the negative health consequences of FGM, were more likely to support discontinuation of FGM. By contrast, women with positive cultural conceptions of FGM were less likely to favour its discontinuation. CONCLUSIONS: Public education and information dissemination aiming to change current cultural notions favouring FGM practice – through community and religious leaders, and radio and television programs – may play an important role in modifying women’s attitudes towards FGM. These findings have some implications for intervention and policy.
Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death
Ostergaard, Kamilla; Pottegård, Anton; Hallas, Jesper
2014-01-01
drugs. Recent statin use was associated with markedly increased risk of death (2.1 (1.7-2.6)), and only marginally with recurrent stroke (1.2 (0.9-1.6)). CONCLUSIONS: Antiplatelet drug discontinuation may be associated with an increased recurrent stroke risk. Our results on death risk indicate that non...