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Sample records for huxley work allowing

  1. Brave new world revisited revisited: Huxley's evolving view of behaviorism

    OpenAIRE

    Newman, Bobby

    1992-01-01

    Aldous Huxley's Brave New World has served as a popular and powerful source of antibehavioral sentiment. Several of Huxley's works are examined in order to ascertain his true thoughts regarding behaviorism. Early in his career Huxley failed to appreciate aspects of behavioral theory (e.g., an appreciation of heredity) or the good ends to which it could be employed. Huxley's later works portrayed behaviorism in a much more positive light, and he believed that behavioral science, along with spi...

  2. A review of the diversity and evolution of photonic structures in butterflies, incorporating the work of John Huxley (The Natural History Museum, London from 1961 to 1990).

    Science.gov (United States)

    Ingram, A L; Parker, A R

    2008-07-27

    The photonic structures of butterfly wings are among the most anatomically diverse of all those in nature, giving rise to an unrivalled display of structural colours. These have recently become the focus of research by workers in a variety of disciplines, stimulated by their potential applications to technology ('biomimetics'). This interest, together with the discovery of unpublished electron micrographs taken by the late Dr John Huxley (Natural History Museum, London), prompted this review of butterfly photonics in general. The current work provides a synopsis of the literature to date, covering the diversity and evolution of these optical structures and incorporating Huxley's work, which represents an important biomimetic and evolutionary database on its own. This review deals with butterfly photonic devices according to the parts of the butterfly scales on which they occur. In this way, the information is ripe for evolutionary study.

  3. [R. Goldschmidt and J. Huxley: creative parallelisms].

    Science.gov (United States)

    Golubovskiĭ, M D; Gall, Ia M

    2003-01-01

    The comparative analysis of scientific heritage of Richard Goldschmidt and Julian Huxley shows convincingly the resemblance of these two scientists' views over the core problems of evolutionary theory, genetics and development biology. They both contributed to developing a triad "genetics--development--evolution". The problem of a relative growth of animals was the central point in both Goldschmidt's and Huxley's works. Huxley developed a formula of the allometric growth (law of constant differential growth) while Goldschmidt was the first to draw up the broad interpretation of the consequences of that phenomenon. Both scientists belonged to initiators of development genetics and used the "non-morganian" genetics in their efforts of solving problems of macroevolution. Goldschmidt tended toward an idea of an important role of macromutation in the process of macroevolution, though Huxley adhered to more moderate views. But at the same time the concept of preadaptive mutations proposed by Huxley was close to Goldschmidt's idea of macromutants. It is shown that both scientists analyzed profoundly the changes in early stages of embryogenesis in respect to macroevolution. It is not likely to be reasonable to oppose firmly Goldschmidt's saltationism to the evolutionary synthesis of Huxley. They developed the larger biological problems in a similar way, and undoubtedly their works in the field helped to enrich the development of the views over genetics and evolution. The open-minded analysis of Goldschmidt's and Huxley's concepts leads to creating modern and up-to-date views over the theory of evolution where seemingly incompatible things go together rather well and supplement each other. Evo-Devo rediscovered Goldshmidt's Biology and Huxley's Synthesis.

  4. Brave new world revisited revisited: Huxley's evolving view of behaviorism.

    Science.gov (United States)

    Newman, B

    1992-01-01

    Aldous Huxley's Brave New World has served as a popular and powerful source of antibehavioral sentiment. Several of Huxley's works are examined in order to ascertain his true thoughts regarding behaviorism. Early in his career Huxley failed to appreciate aspects of behavioral theory (e.g., an appreciation of heredity) or the good ends to which it could be employed. Huxley's later works portrayed behaviorism in a much more positive light, and he believed that behavioral science, along with spiritual enlightenment, might help save humanity from the Brave New World he predicted.

  5. 38 CFR 21.9670 - Work-study allowance.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Work-study allowance. 21... rate of pursuit of at least 75 percent may receive a work-study allowance in accordance with the...) VOCATIONAL REHABILITATION AND EDUCATION Post-9/11 GI Bill Payments-Educational Assistance § 21.9670...

  6. Aldous Huxley: a beginner's guide

    OpenAIRE

    O'Hara, Kieron

    2012-01-01

    Author of Brave New World and The Doors of Perception, and inventor of the term 'psychedelic', Aldous Huxley was a global trend-setter ahead of his time. Charting his transformation from society satirist to Californian guru-mystic, Aldous Huxley: A Beginner's Guide shows how his ideas evolved and why his writing is still vitally relevant today - from detailing the lures of consumerism to exploring individual responsibility in a globalised world. With biographical notes on Huxley's extraordina...

  7. Evolution and Education: Lessons from Thomas Huxley

    Science.gov (United States)

    Lyons, Sherrie Lynne

    2010-01-01

    Thomas Huxley more than anyone else was responsible for disseminating Darwin's theory in the western world and maintained that investigating the history of life should be regarded as a purely scientific question free of theological speculation. The content and rhetorical strategy of Huxley's defense of evolution is analyzed. Huxley argued that the…

  8. Dartington: A Principal Source of Inspiration behind Aldous Huxley's "Island".

    Science.gov (United States)

    Parsons, David

    1987-01-01

    Describes Dartington Hall School in Devon, England, which between the 1920s and 1970s implemented an educational system combining traditional Hindu religious philosophy and ideals of living and Western scientific knowledge and work experience. Considers ways Dartington educationally and socially resembled Aldous Huxley's utopia in…

  9. 46 CFR 52.01-55 - Increase in maximum allowable working pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Increase in maximum allowable working pressure. 52.01-55... POWER BOILERS General Requirements § 52.01-55 Increase in maximum allowable working pressure. (a) When the maximum allowable working pressure of a boiler has been established, an increase in the pressure...

  10. 76 FR 67558 - Proposed Information Collection (Application for Work-Study Allowance) Activity: Comment Request

    Science.gov (United States)

    2011-11-01

    ... AFFAIRS Proposed Information Collection (Application for Work-Study Allowance) Activity: Comment Request... comments for information needed to determine a claimant's eligibility for work-study benefits. DATES.... Application for Work-Study Allowance, VA Form 22-8691. b. Student Work-Study Agreement (Advance Payment),...

  11. 77 FR 2351 - Agency Information Collection (Application for Work-Study Allowance): Activity Under OMB Review

    Science.gov (United States)

    2012-01-17

    ... AFFAIRS Agency Information Collection (Application for Work-Study Allowance): Activity Under OMB Review... INFORMATION: Titles a. Application for Work-Study Allowance, VA Form 22-8691. b. Student Work-Study Agreement (Advance Payment), VA Form 22-8692. c. Extended Student Work-Study Agreement, VA Form 22-8692a. d....

  12. EXPONENTIAL TIME DIFFERENCING FOR HODGKIN-HUXLEY-LIKE ODES.

    Science.gov (United States)

    Börgers, Christoph; Nectow, Alexander R

    2013-01-01

    Several authors have proposed the use of exponential time differencing (ETD) for Hodgkin-Huxley-like partial and ordinary differential equations (PDEs and ODEs). For Hodgkin-Huxley-like PDEs, ETD is attractive because it can deal effectively with the stiffness issues that diffusion gives rise to. However, large neuronal networks are often simulated assuming "space-clamped" neurons, i.e., using the Hodgkin-Huxley ODEs, in which there are no diffusion terms. Our goal is to clarify whether ETD is a good idea even in that case. We present a numerical comparison of first- and second-order ETD with standard explicit time-stepping schemes (Euler's method, the midpoint method, and the classical fourth-order Runge-Kutta method). We find that in the standard schemes, the stable computation of the very rapid rising phase of the action potential often forces time steps of a small fraction of a millisecond. This can result in an expensive calculation yielding greater overall accuracy than needed. Although it is tempting at first to try to address this issue with adaptive or fully implicit time-stepping, we argue that neither is effective here. The main advantage of ETD for Hodgkin-Huxley-like systems of ODEs is that it allows underresolution of the rising phase of the action potential without causing instability, using time steps on the order of one millisecond. When high quantitative accuracy is not necessary and perhaps, because of modeling inaccuracies, not even useful, ETD allows much faster simulations than standard explicit time-stepping schemes. The second-order ETD scheme is found to be substantially more accurate than the first-order one even for large values of Δt.

  13. Population Encoding With Hodgkin-Huxley Neurons.

    Science.gov (United States)

    Lazar, Aurel A

    2010-02-01

    The recovery of (weak) stimuli encoded with a population of Hodgkin-Huxley neurons is investigated. In the absence of a stimulus, the Hodgkin-Huxley neurons are assumed to be tonically spiking. The methodology employed calls for 1) finding an input-output (I/O) equivalent description of the Hodgkin-Huxley neuron and 2) devising a recovery algorithm for stimuli encoded with the I/O equivalent neuron(s). A Hodgkin-Huxley neuron with multiplicative coupling is I/O equivalent with an Integrate-and-Fire neuron with a variable threshold sequence. For bandlimited stimuli a perfect recovery of the stimulus can be achieved provided that a Nyquist-type rate condition is satisfied. A Hodgkin-Huxley neuron with additive coupling and deterministic conductances is first-order I/O equivalent with a Project-Integrate-and-Fire neuron that integrates a projection of the stimulus on the phase response curve. The stimulus recovery is formulated as a spline interpolation problem in the space of finite length bounded energy signals. A Hodgkin-Huxley neuron with additive coupling and stochastic conductances is shown to be first-order I/O equivalent with a Project-Integrate-and-Fire neuron with random thresholds. For stimuli modeled as elements of Sobolev spaces the reconstruction algorithm minimizes a regularized quadratic optimality criterion. Finally, all previous recovery results of stimuli encoded with Hodgkin-Huxley neurons with multiplicative and additive coupling, and deterministic and stochastic conductances are extended to stimuli encoded with a population of Hodgkin-Huxley neurons.

  14. [Thomas H.Huxley--the naval doctor who became Darwin's bulldog].

    Science.gov (United States)

    Hauge, A

    2000-12-10

    Thomas H. Huxley (1825-1895) was an English physician and biologist who had a deep impact on the Victorian age. More than any other at his time he introduced scientifically based values. As a member of London's school board he brought science into the curriculum, encouraging school-children to ask questions and to make their own observations. Huxley came from a lower middle class family with little money. By sheer determination and hard work he managed to get a medical education at Charing Cross Hospital Medical School. He then obtained a posting on H.M.S. Rattlesnake, which gave him a chance to explore the southern seas and to study marine species. The results were published by the Royal Society of which Huxley became a member at the age of 26, and later its president. After several years of uncertainty he secured a position at the Royal School of Mines, which he transformed into the Imperial College of Science. He was a prolific scientist with wide interests, doing valuable work in paleontology, taxonomy and ethnology. Huxley wrote numerous essays on philosophy and scientific subjects. He coined the word agnostic to explain his attitude to Christian dogma. His style was clear and direct, and his essays still read very well. However, Huxley is now mostly, perhaps unfairly, remembered for his defence of Darwin's theory of evolution. In his book Evidence as to man's place in nature, Huxley, in contrast to Darwin, deals with the evolution of humans, mainly based on comparative anatomy. Huxley advocated a firmly held belief that scientific truths will have a liberating effect on the minds of men. His lectures on scientific subjects attracted large audiences of people who had not had the benefit of a higher education.

  15. On nonclassical symmetries of generalized Huxley equations

    CERN Document Server

    Ivanova, Nataliya M

    2010-01-01

    Nonclassical symmetries of a class of generalized Huxley equations of form $u_t=u_{xx}+k(x)u^2(1-u)$ are found. More precisely, for the class under consideration we completely classify reduction operators with $\\tau=1$ and give a wide number of examples of equations admitting reduction operators with $\\tau=0$.

  16. Unidirectional synchronization of Hodgkin-Huxley neurons

    Energy Technology Data Exchange (ETDEWEB)

    Cornejo-Perez, Octavio [Division de Matematicas Aplicadas y Sistemas, Computacionales, IPICYT, Apdo. Postal 3-74 Tangamanga, 78231 San Luis Potosi (Mexico)]. E-mail: octavio@ipicyt.edu.mx; Femat, Ricardo [Division de Matematicas Aplicadas y Sistemas, Computacionales, IPICYT, Apdo. Postal 3-74 Tangamanga, 78231 San Luis Potosi (Mexico)]. E-mail: rfemat@ipicyt.edu.mx

    2005-07-01

    Synchronization dynamics of two noiseless Hodgkin-Huxley (HH) neurons under the action of feedback control is studied. The spiking patterns of the action potentials evoked by periodic external modulations attain synchronization states under the feedback action. Numerical simulations for the synchronization dynamics of regular-irregular desynchronized spiking sequences are displayed. The results are discussed in context of generalized synchronization. It is also shown that the HH neurons can be synchronized in face of unmeasured states.

  17. The what and where of adding channel noise to the Hodgkin-Huxley equations.

    Science.gov (United States)

    Goldwyn, Joshua H; Shea-Brown, Eric

    2011-11-01

    Conductance-based equations for electrically active cells form one of the most widely studied mathematical frameworks in computational biology. This framework, as expressed through a set of differential equations by Hodgkin and Huxley, synthesizes the impact of ionic currents on a cell's voltage--and the highly nonlinear impact of that voltage back on the currents themselves--into the rapid push and pull of the action potential. Later studies confirmed that these cellular dynamics are orchestrated by individual ion channels, whose conformational changes regulate the conductance of each ionic current. Thus, kinetic equations familiar from physical chemistry are the natural setting for describing conductances; for small-to-moderate numbers of channels, these will predict fluctuations in conductances and stochasticity in the resulting action potentials. At first glance, the kinetic equations provide a far more complex (and higher-dimensional) description than the original Hodgkin-Huxley equations or their counterparts. This has prompted more than a decade of efforts to capture channel fluctuations with noise terms added to the equations of Hodgkin-Huxley type. Many of these approaches, while intuitively appealing, produce quantitative errors when compared to kinetic equations; others, as only very recently demonstrated, are both accurate and relatively simple. We review what works, what doesn't, and why, seeking to build a bridge to well-established results for the deterministic equations of Hodgkin-Huxley type as well as to more modern models of ion channel dynamics. As such, we hope that this review will speed emerging studies of how channel noise modulates electrophysiological dynamics and function. We supply user-friendly MATLAB simulation code of these stochastic versions of the Hodgkin-Huxley equations on the ModelDB website (accession number 138950) and http://www.amath.washington.edu/~etsb/tutorials.html.

  18. Correlations in background activity control persistent state stability and allow execution of working memory tasks

    Directory of Open Access Journals (Sweden)

    Mario eDipoppa

    2013-10-01

    Full Text Available Working memory (WM is tightly capacity limited, it requires selective information gating, active information maintenance, and rapid active updating. Hence performing a WM task needs rapid and controlled transitions between neural persistent activity and the resting state. We propose that changes in spike-time correlations in neural activity provides a mechanism for the required working memory operations. As a proof of principle, we implement sustained activity and working memory in a recurrently-coupled spiking network with neurons receiving excitatory random background activity where background correlations are induced by a common noise source. We first characterize how the level of background correlations controls the stability of the persistent state. With sufficiently high correlations, the sustained state becomes practically unstable, so it cannot be initiated by a transient stimulus. We exploit this in a working memory model implementing the delay match to sample task by modulating flexibly in time the correlation level at different phases of the task. The modulation sets the network in different working regimes: more prompt to gate in a signal or clear the memory. The findings presented in this manuscript can form the basis for a new paradigm about how correlations are flexibly controlled by the cortical circuits to execute WM operations.

  19. Heuristics for the Hodgkin-Huxley system.

    Science.gov (United States)

    Hoppensteadt, Frank

    2013-09-01

    Hodgkin and Huxley (HH) discovered that voltages control ionic currents in nerve membranes. This led them to describe electrical activity in a neuronal membrane patch in terms of an electronic circuit whose characteristics were determined using empirical data. Due to the complexity of this model, a variety of heuristics, including relaxation oscillator circuits and integrate-and-fire models, have been used to investigate activity in neurons, and these simpler models have been successful in suggesting experiments and explaining observations. Connections between most of the simpler models had not been made clear until recently. Shown here are connections between these heuristics and the full HH model. In particular, we study a new model (Type III circuit): It includes the van der Pol-based models; it can be approximated by a simple integrate-and-fire model; and it creates voltages and currents that correspond, respectively, to the h and V components of the HH system.

  20. Singularly perturbed Burger-Huxley equation: Analytical solution ...

    African Journals Online (AJOL)

    user

    Keywords: Burger-Huxley equation, iteration method, analytical solution, ... dynamics, chemical kinetics and mathematical biology (Albowitz and Clarkson, ... numbers, Navier-Stokes flows with large Reynolds numbers, chemical reactor theory, ...

  1. Whistles, bells, and cogs in machines: Thomas Huxley and epiphenomenalism.

    Science.gov (United States)

    Greenwood, John

    2010-01-01

    In this paper I try to shed some historical light upon the doctrine of epiphenomenalism, by focusing on the version of epiphenomenalism championed by Thomas Huxley, which is often treated as a classic statement of the doctrine. I argue that it is doubtful if Huxley held any form of metaphysical epiphenomenalism, and that he held a more limited form of empirical epiphenomenalism with respect to consciousness but not with respect to mentality per se. Contrary to what is conventionally supposed, Huxley's empirical epiphenomenalism with respect to consciousness was not simply based upon the demonstration of the neurophysiological basis of conscious mentality, or derived from the extension of mechanistic and reflexive principles of explanation to encompass all forms of animal and human behavior, but was based upon the demonstration of purposive and coordinated animal and human behavior in the absence of consciousness. Given Huxley's own treatment of mentality, his characterization of animals and humans as "conscious automata" was not well chosen.

  2. The Hodgkin-Huxley heritage: from channels to circuits.

    Science.gov (United States)

    Catterall, William A; Raman, Indira M; Robinson, Hugh P C; Sejnowski, Terrence J; Paulsen, Ole

    2012-10-10

    The Hodgkin-Huxley studies of the action potential, published 60 years ago, are a central pillar of modern neuroscience research, ranging from molecular investigations of the structural basis of ion channel function to the computational implications at circuit level. In this Symposium Review, we aim to demonstrate the ongoing impact of Hodgkin's and Huxley's ideas. The Hodgkin-Huxley model established a framework in which to describe the structural and functional properties of ion channels, including the mechanisms of ion permeation, selectivity, and gating. At a cellular level, the model is used to understand the conditions that control both the rate and timing of action potentials, essential for neural encoding of information. Finally, the Hodgkin-Huxley formalism is central to computational neuroscience to understand both neuronal integration and circuit level information processing, and how these mechanisms might have evolved to minimize energy cost.

  3. Remembrance of Hugh E. Huxley, a founder of our field.

    Science.gov (United States)

    Pollard, Thomas D; Goldman, Yale E

    2013-09-01

    Hugh E. Huxley (1924-2013) carried out structural studies by X-ray fiber diffraction and electron microscopy that established how muscle contracts. Huxley's sliding filament mechanism with an ATPase motor protein taking steps along an actin filament, established the paradigm not only for muscle contraction but also for other motile systems using actin and unconventional myosins, microtubules and dynein and microtubules and kinesin.

  4. Science, Sexuality, and the Novels of Huxley and Houellebecq

    OpenAIRE

    2003-01-01

    In her article "Science, Sexuality, and the Novels of Huxley and Houellebecq," Angela C. Holzer begins with an introduction to recent discourse about contemporary culture by Francis Fukuyama, notably in his book Our Posthuman Future (2001). Next, Holzer introduces twentieth-century literary representations of genetic engineering. Focusing on Huxley's Brave New World (1932) and on Houellebecq's Les Particules élémentaires (1998), Holzer discusses differences in "utopian" literature when linked...

  5. SAn Analysis f the theme of “Fard”by Aldous Leonard Huxley

    Institute of Scientific and Technical Information of China (English)

    野长虹

    2014-01-01

    奥德斯�李納�赫胥黎是英格兰作家,著名的赫胥黎家族最杰出的成员之一。赫胥黎是一个人文主义者,和平主义者及讽刺作家。他的文章“胭脂”入选了现代大学英语阅读(4)。此文展示了资产阶级对工人阶级的极度剥削,揭露了资产阶级的丑恶灵魂。本论文旨在分析文章题目揭示的深层次主题。%Leonard Huxley was an English writer and a prominent member of the Huxley family.Huxley was a humanist,pacifist and satirist.His article “Fard”has been elected into the Contemporary College English Reading Book IV.It shows the facts of bourG geoisie’s fierce exploitation to the working class and their ugly souls.This thesis aims at analyzing the deeper theme of the article shown by the title.

  6. Correlations in background activity control persistent state stability and allow execution of working memory tasks.

    Science.gov (United States)

    Dipoppa, Mario; Gutkin, Boris S

    2013-01-01

    Working memory (WM) requires selective information gating, active information maintenance, and rapid active updating. Hence performing a WM task needs rapid and controlled transitions between neural persistent activity and the resting state. We propose that changes in correlations in neural activity provides a mechanism for the required WM operations. As a proof of principle, we implement sustained activity and WM in recurrently coupled spiking networks with neurons receiving excitatory random background activity where background correlations are induced by a common noise source. We first characterize how the level of background correlations controls the stability of the persistent state. With sufficiently high correlations, the sustained state becomes practically unstable, so it cannot be initiated by a transient stimulus. We exploit this in WM models implementing the delay match to sample task by modulating flexibly in time the correlation level at different phases of the task. The modulation sets the network in different working regimes: more prompt to gate in a signal or clear the memory. We examine how the correlations affect the ability of the network to perform the task when distractors are present. We show that in a winner-take-all version of the model, where two populations cross-inhibit, correlations make the distractor blocking robust. In a version of the mode where no cross inhibition is present, we show that appropriate modulation of correlation levels is sufficient to also block the distractor access while leaving the relevant memory trace in tact. The findings presented in this manuscript can form the basis for a new paradigm about how correlations are flexibly controlled by the cortical circuits to execute WM operations.

  7. Old flying ice-rock body in space allows a glance at its inner working.

    Science.gov (United States)

    Bieler, A. M.

    2015-12-01

    I am studying old, cold bodies of rock and ice flying through space, usually far, far away from the Sun. They are even behind the last of the big 8 balls we call our home worlds. (There were 9 balls a few yearsago, but then one of the balls was not considered a ball anymore by some people and he/she had to leave the group.)Because they are so far away from the Sun, they remain dark and very cold for the most part of their life.That is why even most of the very nervous stuff sticks on them ever since. With stuff I mean the little things that the Sun, the big 8 balls, we humans and everything else that is flying around the Sun ismade of. The nervous ones quickly change into something wind like andcan get lost. But the cold on the ice-rock bodies slows this down andthey stick around. This makes those ice-rock bodies interesting tostudy, they did not change too much since they were made.I study news sent back from a computer controlled box flying around oneof those rock-ice things that is now closer to the Sun. When thespace between such a body and the Sun gets smaller, it warms up andsome of the ice changes into wind like things. We find out how muchof what stuff is flying away from that body and at what time.Then I and my friends put those numbers into a big ass computer to findout more on how those rock-ice bodies work. Where does the wind comefrom? Do they all come from the same place or only some? Is it really the Sun's fault? How many cups of ice change into wind each day? Many questions.

  8. Teaching and learning the Hodgkin-Huxley model based on software developed in NEURON's programming language hoc.

    Science.gov (United States)

    Hernández, Oscar E; Zurek, Eduardo E

    2013-05-15

    We present a software tool called SENB, which allows the geometric and biophysical neuronal properties in a simple computational model of a Hodgkin-Huxley (HH) axon to be changed. The aim of this work is to develop a didactic and easy-to-use computational tool in the NEURON simulation environment, which allows graphical visualization of both the passive and active conduction parameters and the geometric characteristics of a cylindrical axon with HH properties. The SENB software offers several advantages for teaching and learning electrophysiology. First, SENB offers ease and flexibility in determining the number of stimuli. Second, SENB allows immediate and simultaneous visualization, in the same window and time frame, of the evolution of the electrophysiological variables. Third, SENB calculates parameters such as time and space constants, stimuli frequency, cellular area and volume, sodium and potassium equilibrium potentials, and propagation velocity of the action potentials. Furthermore, it allows the user to see all this information immediately in the main window. Finally, with just one click SENB can save an image of the main window as evidence. The SENB software is didactic and versatile, and can be used to improve and facilitate the teaching and learning of the underlying mechanisms in the electrical activity of an axon using the biophysical properties of the squid giant axon.

  9. Spike neural models (part I: The Hodgkin-Huxley model

    Directory of Open Access Journals (Sweden)

    Johnson, Melissa G.

    2017-05-01

    Full Text Available Artificial neural networks, or ANNs, have grown a lot since their inception back in the 1940s. But no matter the changes, one of the most important components of neural networks is still the node, which represents the neuron. Within spiking neural networks, the node is especially important because it contains the functions and properties of neurons that are necessary for their network. One important aspect of neurons is the ionic flow which produces action potentials, or spikes. Forces of diffusion and electrostatic pressure work together with the physical properties of the cell to move ions around changing the cell membrane potential which ultimately produces the action potential. This tutorial reviews the Hodkgin-Huxley model and shows how it simulates the ionic flow of the giant squid axon via four differential equations. The model is implemented in Matlab using Euler's Method to approximate the differential equations. By using Euler's method, an extra parameter is created, the time step. This new parameter needs to be carefully considered or the results of the node may be impaired.

  10. Comparison of the validity of Hill and Huxley muscle-tendon complex models using experimental data obtained from rat m. soleus in situ.

    Science.gov (United States)

    Lemaire, Koen K; Baan, Guus C; Jaspers, Richard T; van Soest, A J Knoek

    2016-04-01

    The relationship between mechanical and metabolic behaviour in the widely used Hill muscle-tendon complex (MTC) model is not straightforward, whereas this is an integral part of the Huxley model. In this study, we assessed to what extent Huxley- and Hill-type MTC models yield adequate predictions of mechanical muscle behaviour during stretch-shortening cycles (SSCs). In fully anaesthetized male Wistar rats (N=3), m. soleus was dissected completely free, except for the insertion. Cuff electrodes were placed over the n. ischiadicus. The distal end of the tendon was connected to a servo motor, via a force transducer. The setup allowed for full control over muscle stimulation and length, while force was measured. Quick-release and isovelocity contractions (part 1), and SSCs (part 2) were imposed. Simulations of part 2 were made with both a Hill and a Huxley MTC model, using parameter values determined from part 1. Modifications to the classic two-state Huxley model were made to incorporate series elasticity, activation dynamics, and active and passive force-length relationships. Results were similar for all rats. Fitting of the free parameters to the data of part 1 was near perfect (R(2)>0.97). During SSCs, predicted peak force and force during relaxation deviated from the experimental data for both models. Overall, both models yielded similarly adequate predictions of the experimental data. We conclude that Huxley and Hill MTC models are equally valid with respect to mechanical behaviour.

  11. Synchronization of a coupled Hodgkin-Huxley neurons via high order sliding-mode feedback

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Lopez, R. [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana, Av. San Pablo No. 180, Reynosa-Tamaulipas, 02200 Azcapotzalco, Mexico, D.F. (Mexico)], E-mail: raguilar@correo.azc.uam.mx; Martinez-Guerra, R. [Departamento de Control Automatico, CINVESTAV-IPN, Apartado Postal 14-740, Mexico, D.F. C.P. 07360 (Mexico)], E-mail: rguerra@ctrl.cinvestav.mx

    2008-07-15

    This work deals with the synchronizations of two both coupled Hodgkin-Huxley (H-H) neurons, where the master neuron posses inner noise and the slave neuron is considered in a resting state, (without inner noise) and an exciting state (with inner noise). The synchronization procedure is done via a feedback control, considering a class of high order sliding-mode controller which provides chattering reduction and finite time synchronization convergence, with a satisfactory performance. Theoretical analysis is done in order to show the closed-loop stability of the proposed controller and the calculated finite time for convergence. The main results are illustrated via numerical experiments.

  12. Huxley College of Environmental Studies, Western Washington University.

    Science.gov (United States)

    Miles, John C.

    1987-01-01

    Describes the programs of Huxley College (Washington) which were designed to provide an environmental studies thread through all of its academic endeavors. Addresses the development of the curriculum of both the undergraduate and graduate levels. Discusses its research focal points and its prospects for the future. (TW)

  13. Statistical mechanics of the Huxley-Simmons model.

    Science.gov (United States)

    Caruel, M; Truskinovsky, L

    2016-06-01

    The chemomechanical model of Huxley and Simmons (HS) [A. F. Huxley and R. M. Simmons, Nature 233, 533 (1971)NATUAS0028-083610.1038/233533a0] provides a paradigmatic description of mechanically induced collective conformational changes relevant in a variety of biological contexts, from muscles power stroke and hair cell gating to integrin binding and hairpin unzipping. We develop a statistical mechanical perspective on the HS model by exploiting a formal analogy with a paramagnetic Ising model. We first study the equilibrium HS model with a finite number of elements and compute explicitly its mechanical and thermal properties. To model kinetics, we derive a master equation and solve it for several loading protocols. The developed formalism is applicable to a broad range of allosteric systems with mean-field interactions.

  14. Statistical mechanics of the Huxley-Simmons model

    CERN Document Server

    Caruel, M

    2016-01-01

    The chemomechanical model of Huxley and Simmons (HS) [A. F. Huxley and R. M. Simmons, Nature 233, 533 (1971)] provides a paradigmatic description of mechanically induced collective conformational changes relevant in a variety of biological contexts, from muscles power-stroke and hair cell gating to integrin binding and hairpin unzipping. We develop a statistical mechanical perspective on the HS model by exploiting a formal analogy with a paramagnetic Ising model. We first study the equilibrium HS model with a finite number of elements and compute explicitly its mechanical and thermal properties. To model kinetics, we derive a master equation and solve it for several loading protocols. The developed formalism is applicable to a broad range of allosteric systems with mean-field interactions.

  15. Statistical mechanics of the Huxley-Simmons model

    Science.gov (United States)

    Caruel, M.; Truskinovsky, L.

    2016-06-01

    The chemomechanical model of Huxley and Simmons (HS) [A. F. Huxley and R. M. Simmons, Nature 233, 533 (1971), 10.1038/233533a0] provides a paradigmatic description of mechanically induced collective conformational changes relevant in a variety of biological contexts, from muscles power stroke and hair cell gating to integrin binding and hairpin unzipping. We develop a statistical mechanical perspective on the HS model by exploiting a formal analogy with a paramagnetic Ising model. We first study the equilibrium HS model with a finite number of elements and compute explicitly its mechanical and thermal properties. To model kinetics, we derive a master equation and solve it for several loading protocols. The developed formalism is applicable to a broad range of allosteric systems with mean-field interactions.

  16. An efficient method for solving fractional Hodgkin–Huxley model

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, A.M., E-mail: abdelhameed_nagy@yahoo.com [Department of Mathematics, Faculty of Science, Benha University, 13518 Benha (Egypt); Sweilam, N.H., E-mail: n_sweilam@yahoo.com [Department of Mathematics, Faculty of Science, Cairo University, 12613 Giza (Egypt)

    2014-06-13

    In this paper, we present an accurate numerical method for solving fractional Hodgkin–Huxley model. A non-standard finite difference method (NSFDM) is implemented to study the dynamic behaviors of the proposed model. The Grünwald–Letinkov definition is used to approximate the fractional derivatives. Numerical results are presented graphically reveal that NSFDM is easy to implement, effective and convenient for solving the proposed model. - Highlights: • An accurate numerical method for solving fractional Hodgkin–Huxley model is given. • Non-standard finite difference method (NSFDM) is implemented to the proposed model. • NSFDM can solve differential equations involving derivatives of non-integer order. • NDFDM is very powerful and efficient technique for solving the proposed model.

  17. Parameter estimation of the Huxley cross-bridge muscle model in humans.

    Science.gov (United States)

    Vardy, Alistair N; de Vlugt, Erwin; van der Helm, Frans C T

    2012-01-01

    The Huxley model has the potential to provide more accurate muscle dynamics while affording a physiological interpretation at cross-bridge level. By perturbing the wrist at different velocities and initial force levels, reliable Huxley model parameters were estimated in humans in vivo using a Huxley muscle-tendon complex. We conclude that these estimates may be used to investigate and monitor changes in microscopic elements of muscle functioning from experiments at joint level.

  18. Chiral Solutions to Generalized Burgers and Burgers-Huxley Equations

    CERN Document Server

    Bazeia, D

    1998-01-01

    We investigate generalizations of the Burgers and Burgers-Huxley equations. The investigations we offer focus attention mainly on presenting explict analytical solutions by means of relating these generalized equations to relativistic 1+1 dimensional systems of scalar fields where topological solutions are known to play a role. Emphasis is given on chiral solutions, that is, on the possibility of finding solutions that travel with velocities determined in terms of the parameters that identify the generalized equation, with a definite sign.

  19. An efficient method for solving fractional Hodgkin-Huxley model

    Science.gov (United States)

    Nagy, A. M.; Sweilam, N. H.

    2014-06-01

    In this paper, we present an accurate numerical method for solving fractional Hodgkin-Huxley model. A non-standard finite difference method (NSFDM) is implemented to study the dynamic behaviors of the proposed model. The Grünwald-Letinkov definition is used to approximate the fractional derivatives. Numerical results are presented graphically reveal that NSFDM is easy to implement, effective and convenient for solving the proposed model.

  20. Action potential initiation in the hodgkin-huxley model.

    Directory of Open Access Journals (Sweden)

    Lucy J Colwell

    2009-01-01

    Full Text Available A recent paper of B. Naundorf et al. described an intriguing negative correlation between variability of the onset potential at which an action potential occurs (the onset span and the rapidity of action potential initiation (the onset rapidity. This correlation was demonstrated in numerical simulations of the Hodgkin-Huxley model. Due to this antagonism, it is argued that Hodgkin-Huxley-type models are unable to explain action potential initiation observed in cortical neurons in vivo or in vitro. Here we apply a method from theoretical physics to derive an analytical characterization of this problem. We analytically compute the probability distribution of onset potentials and analytically derive the inverse relationship between onset span and onset rapidity. We find that the relationship between onset span and onset rapidity depends on the level of synaptic background activity. Hence we are able to elucidate the regions of parameter space for which the Hodgkin-Huxley model is able to accurately describe the behavior of this system.

  1. Correlation between Dermatology Life Quality Index (DLQI) scores and Work Limitations Questionnaire (WLQ) allows the calculation of percent work productivity loss in patients with psoriasis.

    Science.gov (United States)

    Schmitt, Jochen; Küster, Denise

    2015-07-01

    Data on indirect costs are vital for cost-effectiveness studies from a societal perspective. In contrast to quality of life, information on productivity loss is rarely collected in psoriasis trials. We aimed to identify a model to deduce indirect costs (presenteeism and absenteeism) of psoriasis from the Dermatologic Life Quality Index (DLQI) of affected patients to facilitate health economic evaluations for psoriasis. We undertook a cross-sectional mapping study including 201 patients with physician-diagnosed psoriasis and investigated the relationship between quality of life (DLQI) and productivity loss (Work Limitations Questionnaire, WLQ--using the "output demands" subscale) using linear bootstrap regression analysis to set up an equation model allowing the calculation of percent work productivity loss per DLQI unit increase. DLQI and WLQ scores were significantly correlated (r = 0.47; p work productivity loss due to psoriasis can be estimated from DLQI scores using the equations, Y = 0.545 × DLQI score + 1.654 for presenteeism (%) and Y = 0.560 × DLQI score + 0.536 for absenteeism (%).

  2. Strange Nonchaotic Oscillations in The Quasiperiodically Forced Hodgkin-Huxley Neuron

    CERN Document Server

    Lim, Woochang; 10.1088/1751-8113/42/26/265103

    2011-01-01

    We numerically study dynamical behaviors of the quasiperiodically forced Hodgkin-Huxley neuron and compare the dynamical responses with those for the case of periodic stimulus. In the periodically forced case, a transition from a periodic to a chaotic oscillation was found to occur via period doublings in previous numerical and experimental works. We investigate the effect of the quasiperiodic forcing on this period-doubling route to chaotic oscillation. In contrast to the case of periodic forcing, new type of strange nonchaotic (SN) oscillating states (that are geometrically strange but have no positive Lyapunov exponents) are found to exist between the regular and chaotic oscillating states as intermediate ones. Their strange fractal geometry leads to aperiodic "complex" spikings. Various dynamical routes to SN oscillations are identified, as in the quasiperiodically forced logistic map. These SN spikings are expected to be observed in experiments of the quasiperiodically forced squid giant axon.

  3. Spike trains in Hodgkin-Huxley model and ISIs of acupuncture manipulations

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jiang [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China)], E-mail: jiangwang@tju.edu.cn; Si Wenjie; Che Yanqiu; Fei Xiangyang [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China)

    2008-05-15

    The Hodgkin-Huxley equations (HH) are parameterized by a number of parameters and shows a variety of qualitatively different behaviors depending on the parameter values. Under stimulation of an external periodic voltage, the ISIs (interspike intervals) of a HH model are investigated in this work, while the frequency of the voltage is taken as the controlling parameter. As well-known, the science of acupuncture and moxibustion is an important component of Traditional Chinese Medicine with a long history. Although there are a number of different acupuncture manipulations, the method for distinguishing them is rarely investigated. With the idea of ISI, we study the electrical signal time series at the spinal dorsal horn produced by three different acupuncture manipulations in Zusanli point and present an effective way to distinguish them.

  4. Strange nonchaotic oscillations in the quasiperiodically forced Hodgkin-Huxley neuron

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Woochang; Kim, Sang-Yoon [Department of Physics, Kangwon National University, Chunchon, Kangwon-Do 200-701 (Korea, Republic of)], E-mail: wclim@kangwon.ac.kr, E-mail: sykim@kangwon.ac.kr

    2009-07-03

    We numerically study dynamical behaviors of the quasiperiodically forced Hodgkin-Huxley neuron and compare the dynamical responses with those for the case of periodic stimulus. In the periodically forced case, a transition from a periodic to a chaotic oscillation was found to occur via period doublings in previous numerical and experimental works. We investigate the effect of the quasiperiodic forcing on this period-doubling route to chaotic oscillation. In contrast to the case of periodic forcing, a new type of strange nonchaotic (SN) oscillating states (that are geometrically strange but have no positive Lyapunov exponents) is found to exist between the regular and chaotic oscillating states as intermediate ones. Their strange fractal geometry leads to aperiodic 'complex' spikings. Various dynamical routes to SN oscillations are identified, as in the quasiperiodically forced logistic map. These SN spikings are expected to be observed in experiments of the quasiperiodically forced squid giant axon.

  5. 朱利安·赫胥黎%Julian Huxley

    Institute of Scientific and Technical Information of China (English)

    焦玉洁

    2011-01-01

    @@ 朱利安·赫胥黎(Julian Huxley),1887年6月生于英国伦敦市,1975年2月去世,是英网著名的动物学家、哲学家、教育家和作家.他曾担任联合国教育科学文化组织第一届总干事,也是世界自然基金会(WWF)创始成员之一.作为生物学家,他提倡自然选择,是现代综合进化论领军人物.

  6. Application of the (′/)-expansion method for the Burgers, Burgers–Huxley and modified Burgers–KdV equations

    Indian Academy of Sciences (India)

    H Kheiri; M R Moghaddam; V Vafaei

    2011-06-01

    In this work, we present travelling wave solutions for the Burgers, Burgers–Huxley and modified Burgers–KdV equations. The (′/)-expansion method is used to determine travelling wave solutions of these sets of equations. The travelling wave solutions are expressed by the hyperbolic functions, the trigonometric functions and the rational functions. It is shown that the proposed method is direct, effective and can be used for many other nonlinear evolution equations in mathematical physics.

  7. Energy and information in Hodgkin-Huxley neurons

    CERN Document Server

    Moujahid, A; Torrealdea, F J

    2015-01-01

    The generation of spikes by neurons is energetically a costly process and the evaluation of the metabolic energy required to maintain the signalling activity of neurons a challenge of practical interest. Neuron models are frequently used to represent the dynamics of real neurons but hardly ever to evaluate the electrochemical energy required to maintain that dynamics. This paper discusses the interpretation of a Hodgkin-Huxley circuit as an energy model for real biological neurons and uses it to evaluate the consumption of metabolic energy in the transmission of information between neurons coupled by electrical synapses, i.e. gap junctions. We show that for a single postsynaptic neuron maximum energy efficiency, measured in bits of mutual information per ATP molecule consumed, requires maximum energy consumption. On the contrary, for groups of parallel postsynaptic neurons we determine values of the synaptic conductance at which the energy efficiency of the transmission presents clear maxima at relatively ver...

  8. Hodgkin-Huxley neurons with defective and blocked ion channels

    Science.gov (United States)

    Pang, James Christopher S.; Bantang, Johnrob Y.

    2015-03-01

    We utilize the original Hodgkin-Huxley (HH) model to consider the effects of defective ion channels to the temporal response of neurons. Statistics of firing rate and inter-spike interval (ISI) reveal that production of action potentials (APs) in neurons is not sensitive to changes in membrane conductance for sodium and potassium ions, as well as to the reversal potential for sodium ions, as long as the relevant parameters do not exceed 13% from their normal levels. We also found that blockage of a critical fraction of either sodium or potassium channels (dependent on constant input current) respectively limits the firing activity or increases spontaneous spiking activity of neurons. Our model may be used to guide experiment designs related to ion channel control drug development.

  9. Spontaneous spiking in an autaptic Hodgkin-Huxley set up

    CERN Document Server

    Li, Yunyun; Hanggi, Peter; Schimansky-Geier, Lutz

    2010-01-01

    The effect of intrinsic channel noise is investigated for the dynamic response of a neuronal cell with a delayed feedback loop. The loop is based on the so-called autapse phenomenon in which dendrites establish not only connections to neighboring cells but as well to its own axon. The biophysical modeling is achieved in terms of a stochastic Hodgkin-Huxley model containing such a built in delayed feedback. The fluctuations stem from intrinsic channel noise, being caused by the stochastic nature of the gating dynamics of ion channels. The influence of the delayed stimulus is systematically analyzed with respect to the coupling parameter and the delay time in terms of the interspike interval histograms and the average interspike interval. The delayed feedback manifests itself in the occurrence of bursting and a rich multimodal interspike interval distribution, exhibiting a delay-induced reduction of the spontaneous spiking activity at characteristic frequencies. Moreover, a specific frequency-locking mechanism ...

  10. Edge detection based on Hodgkin-Huxley neuron model simulation.

    Science.gov (United States)

    Yedjour, Hayat; Meftah, Boudjelal; Lézoray, Olivier; Benyettou, Abdelkader

    2017-04-03

    In this paper, we propose a spiking neural network model for edge detection in images. The proposed model is biologically inspired by the mechanisms employed by natural vision systems, more specifically by the biologically fulfilled function of simple cells of the human primary visual cortex that are selective for orientation. Several aspects are studied in this model according to three characteristics: feedforward spiking neural structure; conductance-based model of the Hodgkin-Huxley neuron and Gabor receptive fields structure. A visualized map is generated using the firing rate of neurons representing the orientation map of the visual cortex area. We have simulated the proposed model on different images. Successful computer simulation results are obtained. For comparison, we have chosen five methods for edge detection. We finally evaluate and compare the performances of our model toward contour detection using a public dataset of natural images with associated contour ground truths. Experimental results show the ability and high performance of the proposed network model.

  11. Hodgkin-Huxley revisited: reparametrization and identifiability analysis of the classic action potential model with approximate Bayesian methods.

    Science.gov (United States)

    Daly, Aidan C; Gavaghan, David J; Holmes, Chris; Cooper, Jonathan

    2015-12-01

    As cardiac cell models become increasingly complex, a correspondingly complex 'genealogy' of inherited parameter values has also emerged. The result has been the loss of a direct link between model parameters and experimental data, limiting both reproducibility and the ability to re-fit to new data. We examine the ability of approximate Bayesian computation (ABC) to infer parameter distributions in the seminal action potential model of Hodgkin and Huxley, for which an immediate and documented connection to experimental results exists. The ability of ABC to produce tight posteriors around the reported values for the gating rates of sodium and potassium ion channels validates the precision of this early work, while the highly variable posteriors around certain voltage dependency parameters suggests that voltage clamp experiments alone are insufficient to constrain the full model. Despite this, Hodgkin and Huxley's estimates are shown to be competitive with those produced by ABC, and the variable behaviour of posterior parametrized models under complex voltage protocols suggests that with additional data the model could be fully constrained. This work will provide the starting point for a full identifiability analysis of commonly used cardiac models, as well as a template for informative, data-driven parametrization of newly proposed models.

  12. New multi-soliton solutions for generalized Burgers-Huxley equation

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2013-01-01

    Full Text Available The double exp-function method is used to obtain a two-soliton solution of the generalized Burgers-Huxley equation. The wave has two different velocities and two different frequencies.

  13. Hugh E. Huxley: cambiando el paradigma de la contracción muscular, desde dentro. [Hugh E. Huxley: changing from inside the paradigm of muscle contraction].

    OpenAIRE

    Adolfo Araci

    2014-01-01

    Desde un punto de vista físico se puede entender la fibra muscular como un motor, es decir, un sistema capaz de transformar la energía química en energía mecánica, que se utiliza para realizar un trabajo. Por lo tanto, para entender cómo ocurre dicho proceso de transformación es necesario conocer la ultraestructura de la fibra muscular. Esta es, sin duda, la principal aportación al acervo científico del recientemente fallecido Hugh Emor Huxley (1924-2013). Huxley se graduó en Física en el Chr...

  14. Hugh E. Huxley: cambiando el paradigma de la contracción muscular, desde dentro. [Hugh E. Huxley: changing from inside the paradigm of muscle contraction].

    OpenAIRE

    Adolfo Araci

    2014-01-01

    Desde un punto de vista físico se puede entender la fibra muscular como un motor, es decir, un sistema capaz de transformar la energía química en energía mecánica, que se utiliza para realizar un trabajo. Por lo tanto, para entender cómo ocurre dicho proceso de transformación es necesario conocer la ultraestructura de la fibra muscular. Esta es, sin duda, la principal aportación al acervo científico del recientemente fallecido Hugh Emor Huxley (1924-2013). Huxley se graduó en Física en el Chr...

  15. CHILD ALLOWANCE

    CERN Multimedia

    Human Resources Division

    2001-01-01

    HR Division wishes to clarify to members of the personnel that the allowance for a dependent child continues to be paid during all training courses ('stages'), apprenticeships, 'contrats de qualification', sandwich courses or other courses of similar nature. Any payment received for these training courses, including apprenticeships, is however deducted from the amount reimbursable as school fees. HR Division would also like to draw the attention of members of the personnel to the fact that any contract of employment will lead to the suppression of the child allowance and of the right to reimbursement of school fees.

  16. Modelling spatiotemporal olfactory data in two steps: from binary to Hodgkin-Huxley neurones.

    Science.gov (United States)

    Quenet, Brigitte; Dubois, Rémi; Sirapian, Sevan; Dreyfus, Gérard; Horn, David

    2002-01-01

    Network models of synchronously updated McCulloch-Pitts neurones exhibit complex spatiotemporal patterns that are similar to activities of biological neurones in phase with a periodic local field potential, such as those observed experimentally by Wehr and Laurent (1996, Nature 384, 162-166) in the locust olfactory pathway. Modelling biological neural nets with networks of simple formal units makes the dynamics of the model analytically tractable. It is thus possible to determine the constraints that must be satisfied by its connection matrix in order to make its neurones exhibit a given sequence of activity (see, for instance, Quenet et al., 2001, Neurocomputing 38-40, 831-836). In the present paper, we address the following question: how can one construct a formal network of Hodgkin-Huxley (HH) type neurones that reproduces experimentally observed neuronal codes? A two-step strategy is suggested in the present paper: first, a simple network of binary units is designed, whose activity reproduces the binary experimental codes; second, this model is used as a guide to design a network of more realistic formal HH neurones. We show that such a strategy is indeed fruitful: it allowed us to design a model that reproduces the Wehr-Laurent olfactory codes, and to investigate the robustness of these codes to synaptic noise.

  17. Spontaneous spiking in an autaptic Hodgkin-Huxley setup

    Science.gov (United States)

    Li, Yunyun; Schmid, Gerhard; Hänggi, Peter; Schimansky-Geier, Lutz

    2010-12-01

    The effect of intrinsic channel noise is investigated for the dynamic response of a neuronal cell with a delayed feedback loop. The loop is based on the so-called autapse phenomenon in which dendrites establish connections not only to neighboring cells but also to its own axon. The biophysical modeling is achieved in terms of a stochastic Hodgkin-Huxley model containing such a built in delayed feedback. The fluctuations stem from intrinsic channel noise, being caused by the stochastic nature of the gating dynamics of ion channels. The influence of the delayed stimulus is systematically analyzed with respect to the coupling parameter and the delay time in terms of the interspike interval histograms and the average interspike interval. The delayed feedback manifests itself in the occurrence of bursting and a rich multimodal interspike interval distribution, exhibiting a delay-induced reduction in the spontaneous spiking activity at characteristic frequencies. Moreover, a specific frequency-locking mechanism is detected for the mean interspike interval.

  18. The ISI distribution of the stochastic Hodgkin-Huxley neuron.

    Science.gov (United States)

    Rowat, Peter F; Greenwood, Priscilla E

    2014-01-01

    The simulation of ion-channel noise has an important role in computational neuroscience. In recent years several approximate methods of carrying out this simulation have been published, based on stochastic differential equations, and all giving slightly different results. The obvious, and essential, question is: which method is the most accurate and which is most computationally efficient? Here we make a contribution to the answer. We compare interspike interval histograms from simulated data using four different approximate stochastic differential equation (SDE) models of the stochastic Hodgkin-Huxley neuron, as well as the exact Markov chain model simulated by the Gillespie algorithm. One of the recent SDE models is the same as the Kurtz approximation first published in 1978. All the models considered give similar ISI histograms over a wide range of deterministic and stochastic input. Three features of these histograms are an initial peak, followed by one or more bumps, and then an exponential tail. We explore how these features depend on deterministic input and on level of channel noise, and explain the results using the stochastic dynamics of the model. We conclude with a rough ranking of the four SDE models with respect to the similarity of their ISI histograms to the histogram of the exact Markov chain model.

  19. Effect of channel block on the collective spiking activity of coupled stochastic Hodgkin-Huxley neurons

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Toxins, such as tetraethylammonium (TEA) and tetrodotoxin (TTX), can make potassium or sodium ion channels poisoned, respectively, and hence reduce the number of working ion channels and lead to the diminishment of conductance. In this paper, we have studied by numerical simulations the effects of sodium and potassium ion channel poisoning on the collective spiking activity of an array of coupled stochastic Hodgkin-Huxley (HH) neurons. It is found for a given number of neurons sodium or potas- sium ion channel block can either enhance or reduce the collective spiking regularity, depending on the membrane patch size. For a given smaller or larger patch size, potassium and sodium ion channel block can reduce or enhance the collective spiking regularity, but they have different patch size ranges for the transformation. This result shows that sodium or potassium ion channel block might have dif- ferent effects on the collective spiking activity in coupled HH neurons from the effects for a single neuron, which represents the interplay among the diminishment of maximal conductance and the in- crease of channel noise strength due to the channel blocks, as well as the bi-directional coupling be- tween the neurons.

  20. Response of autaptic Hodgkin-Huxley neuron with noise to subthreshold sinusoidal signals

    Science.gov (United States)

    Wang, Hengtong; Chen, Yong

    2016-11-01

    In this work, we investigated the response of a stochastic Hodgkin-Huxley (HH) neuron with an autapse to subthreshold sinusoidal signals. It is found that the autapse not only adjusts the stochastic responses, but also improves the detection of subthreshold signals. In the case of weak noise, the autapse facilitates the response of neuron to the subthreshold sinusoidal signals with a small parameter region in tdelay- ω space. The increased noise intensity enlarges this parameter region and increases the corresponding response frequency in such range. As the autaptic intensity increases, however, this parameter region shrunks. We also observed that there is an optimal range of the delay time of autapse, within which the stochastic HH neuron fires action potentials with high frequency. The corresponding response spike train for the optimal delay time is nearly a regular sequence with the interspike intervals approximated to the delay time. The current results reveal a novel resonance phenomenon facilitated by autapse, named autaptic delay-induced coherence resonance.

  1. Chimera states in a Hodgkin-Huxley model of thermally sensitive neurons

    Science.gov (United States)

    Glaze, Tera A.; Lewis, Scott; Bahar, Sonya

    2016-08-01

    Chimera states occur when identically coupled groups of nonlinear oscillators exhibit radically different dynamics, with one group exhibiting synchronized oscillations and the other desynchronized behavior. This dynamical phenomenon has recently been studied in computational models and demonstrated experimentally in mechanical, optical, and chemical systems. The theoretical basis of these states is currently under active investigation. Chimera behavior is of particular relevance in the context of neural synchronization, given the phenomenon of unihemispheric sleep and the recent observation of asymmetric sleep in human patients with sleep apnea. The similarity of neural chimera states to neural "bump" states, which have been suggested as a model for working memory and visual orientation tuning in the cortex, adds to their interest as objects of study. Chimera states have been demonstrated in the FitzHugh-Nagumo model of excitable cells and in the Hindmarsh-Rose neural model. Here, we demonstrate chimera states and chimera-like behaviors in a Hodgkin-Huxley-type model of thermally sensitive neurons both in a system with Abrams-Strogatz (mean field) coupling and in a system with Kuramoto (distance-dependent) coupling. We map the regions of parameter space for which chimera behavior occurs in each of the two coupling schemes.

  2. Delay-induced coherence bi-resonance-like behavior in stochastic Hodgkin-Huxley neuron networks

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper,we study how information transmission delays affect the spiking behavior of electrically coupled stochastic Hodgkin-Huxley (HH) neurons on Newman-Watts networks.It is found that the spiking behavior becomes the most regular at an optimal time delay,indicating the occurrence of delay-induced coherence resonance-like (CR-like) behavior.Interestingly,there are different CR-like types,depending on the membrane patch size of the neuron.For a smaller patch size,only single CR-like behavior occurs;while for a larger patch size,coherence bi-resonance-like (CBR) behavior appears.These findings show that the delay-induced CR-like behavior is closely related to the channel noise strength,and the coupled neurons may exhibit different spiking behaviors under the interplay of the channel noise and time delay.Therefore,the channel noise should be taken into account in the study of time delay-related spiking activity in stochastic HH neurons.This work provides new insight into the role of channel noise and information transmission delays in realistic neural systems.

  3. Effect of channel block on the collective spiking activity of coupled stochastic Hodgkin-Huxley neurons

    Institute of Scientific and Technical Information of China (English)

    GONG YuBing; XU Bo; MA XiaoGuang; HAN JiQu

    2008-01-01

    Toxins, such as tetraethylammonium (TEA) and tetrodotoxin (TTX), can make potassium or sodium ion channels poisoned, respectively, and hence reduce the number of working ion channels and lead to the diminishment of conductance. In this paper, we have studied by numerical simulations the effects of sodium and potassium ion channel poisoning on the collective spiking activity of an array of coupled stochastic Hodgkin-Huxley (HH) neurons. It is found for a given number of neurons sodium or potas-sium ion channel block can either enhance or reduce the collective spiking regularity, depending on the membrane patch size. For a given smaller or larger patch size, potassium and sodium ion channel block can reduce or enhance the collective spiking regularity, but they have different patch size ranges for the transformation. This result shows that sodium or potassium ion channel block might have dif-ferent effects on the collective spiking activity in coupled HH neurons from the effects for a single neuron, which represents the interplay among the diminishment of maximal conductance and the in-crease of channel noise strength due to the channel blocks, as well as the bi-directional coupling be-tween the neurons.

  4. Thomas Huxley and the rat placenta in the early debates on evolution.

    Science.gov (United States)

    Pijnenborg, R; Vercruysse, L

    2004-01-01

    The 19th century debates on mammalian classification in the light of the new evolutionary thinking led to controversies between Thomas Huxley and Richard Owen concerning the value of the placenta as a representative key organ. As a main point in his argument, Huxley provided a detailed description of a sectioned rat placenta, highlighting the importance of decidualization of the uterus as an argument supporting an evolutionary relationship between rodents, insectivores and primates, an idea hotly contested by Owen. In addition, he illustrated and correctly interpreted the maternal blood supply from uterus to placenta in striking detail. During the succeeding decades the key role of trophoblast in placenta formation was discovered, and the decidua became neglected in later comparative studies. Nevertheless, at the present time trophoblast-decidual interaction is regarded as an extremely important feature of placental development in both primates and rodents, and Huxley can therefore rightfully be considered as an early pioneer in placental research.

  5. Challenging normative orthodoxies in depression: Huxley's Utopia or Dante's Inferno?

    Science.gov (United States)

    Cutcliffe, John R; Lakeman, Richard

    2010-04-01

    Although there appears to be a widespread consensus that depression is a ubiquitous human experience, definitions of depression, its prevalence, and how mental health services respond to it have changed significantly over time, particularly during recent decades. Epistemological limitations notwithstanding, it is now estimated that approximately 121 million people experience depression. At the same time, it should be acknowledged that the last two decades have seen the widespread acceptance of depression as a chemical imbalance and a massive corresponding increase in the prescription of antidepressants, most notably of selective serotonin reuptake inhibitors (SSRIs). However, questions have been raised about the effectiveness and iatrogenic side effects of antidepressants; related questions have also been asked about whose interests are served by the marketing and sales of these drugs. Accordingly, this article attempts to problematize the normative orthodoxy concerning depression and creates a "space" in which an alternative can be articulated and enacted. In so doing, the article finds that the search for a world where the automatic response to depression is a pharmacological intervention not only ignores the use of alternative efficacious treatment options but may also inhibit the persons' chance to explore the meaning of their experience and thus prevent people from individual growth and personal development. Interestingly, in worlds analogous to this pharmacologically induced depression-free state, such as utopias like that in Huxley's Brave New World, no "properly conditioned citizen" is depressed or suicidal. Yet, in the same Brave New World, no one is free to suffer, to be different, or crucially, to be independent. Copyright 2010 Elsevier Inc. All rights reserved.

  6. Principal Dynamic Mode Analysis of the Hodgkin–Huxley Equations

    Science.gov (United States)

    Eikenberry, Steffen E.; Marmarelis, Vasilis Z.

    2015-01-01

    We develop an autoregressive model framework based on the concept of Principal Dynamic Modes (PDMs) for the process of action potential (AP) generation in the excitable neuronal membrane described by the Hodgkin–Huxley (H–H) equations. The model's exogenous input is injected current, and whenever the membrane potential output exceeds a specified threshold, it is fed back as a second input. The PDMs are estimated from the previously developed Nonlinear Autoregressive Volterra (NARV) model, and represent an efficient functional basis for Volterra kernel expansion. The PDM-based model admits a modular representation, consisting of the forward and feedback PDM bases as linear filterbanks for the exogenous and autoregressive inputs, respectively, whose outputs are then fed to a static nonlinearity composed of polynomials operating on the PDM outputs and cross-terms of pair-products of PDM outputs. A two-step procedure for model reduction is performed: first, influential subsets of the forward and feedback PDM bases are identified and selected as the reduced PDM bases. Second, the terms of the static nonlinearity are pruned. The first step reduces model complexity from a total of 65 coefficients to 27, while the second further reduces the model coefficients to only eight. It is demonstrated that the performance cost of model reduction in terms of out-of-sample prediction accuracy is minimal. Unlike the full model, the eight coefficient pruned model can be easily visualized to reveal the essential system components, and thus the data-derived PDM model can yield insight into the underlying system structure and function. PMID:25630480

  7. Principal dynamic mode analysis of the Hodgkin-Huxley equations.

    Science.gov (United States)

    Eikenberry, Steffen E; Marmarelis, Vasilis Z

    2015-03-01

    We develop an autoregressive model framework based on the concept of Principal Dynamic Modes (PDMs) for the process of action potential (AP) generation in the excitable neuronal membrane described by the Hodgkin-Huxley (H-H) equations. The model's exogenous input is injected current, and whenever the membrane potential output exceeds a specified threshold, it is fed back as a second input. The PDMs are estimated from the previously developed Nonlinear Autoregressive Volterra (NARV) model, and represent an efficient functional basis for Volterra kernel expansion. The PDM-based model admits a modular representation, consisting of the forward and feedback PDM bases as linear filterbanks for the exogenous and autoregressive inputs, respectively, whose outputs are then fed to a static nonlinearity composed of polynomials operating on the PDM outputs and cross-terms of pair-products of PDM outputs. A two-step procedure for model reduction is performed: first, influential subsets of the forward and feedback PDM bases are identified and selected as the reduced PDM bases. Second, the terms of the static nonlinearity are pruned. The first step reduces model complexity from a total of 65 coefficients to 27, while the second further reduces the model coefficients to only eight. It is demonstrated that the performance cost of model reduction in terms of out-of-sample prediction accuracy is minimal. Unlike the full model, the eight coefficient pruned model can be easily visualized to reveal the essential system components, and thus the data-derived PDM model can yield insight into the underlying system structure and function.

  8. Stimulus-dependent refractoriness in the Frankenhaeuser-Huxley model.

    Science.gov (United States)

    Morse, R P; Allingham, D; Stocks, N G

    2015-10-07

    Phenomenological neural models, such as the leaky integrate-and-fire model, normally have a fixed refractory time-course that is independent of the stimulus. The recovery of threshold following an action potential is typically based on physiological experiments that use a two-pulse paradigm in which the first pulse is suprathreshold and causes excitation and the second pulse is used to determine the threshold at various intervals following the first. In such experiments, the nerve is completely unstimulated between the two pulses. This contrasts the receptor stimuli in normal physiological systems and the electrical stimuli used by cochlear implants and other neural prostheses. A numerical study of the Frankenhaeuser-Huxley conductance-based model of nerve fibre was therefore undertaken to investigate the effect of stimulation on refractoriness. We found that the application of a depolarizing stimulus during the later part of what is classically regarded as the absolute refractory period could effectively prolong the absolute refractory period, while leaving the refractory time-constants and other refractory parameters largely unaffected. Indeed, long depolarizing pulses, which would have been suprathreshold if presented to a resting nerve fibre, appeared to block excitation indefinitely. Stimulation during what is classically regarded as the absolute refractory period can therefore greatly affect the temporal response of a nerve. We conclude that the classical definition of absolute refractory period should be refined to include only the initial period following an action potential when an ongoing stimulus would not affect threshold; this period was found to be about half as long as the classical absolute refractory period. We further conclude that the stimulus-dependent nature of the relative refractory period must be considered when developing a phenomenological nerve model for complex stimuli.

  9. Stochastic differential equation models for ion channel noise in Hodgkin-Huxley neurons.

    Science.gov (United States)

    Goldwyn, Joshua H; Imennov, Nikita S; Famulare, Michael; Shea-Brown, Eric

    2011-04-01

    The random transitions of ion channels between conducting and nonconducting states generate a source of internal fluctuations in a neuron, known as channel noise. The standard method for modeling the states of ion channels nonlinearly couples continuous-time Markov chains to a differential equation for voltage. Beginning with the work of R. F. Fox and Y.-N. Lu [Phys. Rev. E 49, 3421 (1994)], there have been attempts to generate simpler models that use stochastic differential equation (SDEs) to approximate the stochastic spiking activity produced by Markov chain models. Recent numerical investigations, however, have raised doubts that SDE models can capture the stochastic dynamics of Markov chain models.We analyze three SDE models that have been proposed as approximations to the Markov chain model: one that describes the states of the ion channels and two that describe the states of the ion channel subunits. We show that the former channel-based approach can capture the distribution of channel noise and its effects on spiking in a Hodgkin-Huxley neuron model to a degree not previously demonstrated, but the latter two subunit-based approaches cannot. Our analysis provides intuitive and mathematical explanations for why this is the case. The temporal correlation in the channel noise is determined by the combinatorics of bundling subunits into channels, but the subunit-based approaches do not correctly account for this structure. Our study confirms and elucidates the findings of previous numerical investigations of subunit-based SDE models. Moreover, it presents evidence that Markov chain models of the nonlinear, stochastic dynamics of neural membranes can be accurately approximated by SDEs. This finding opens a door to future modeling work using SDE techniques to further illuminate the effects of ion channel fluctuations on electrically active cells.

  10. The "History" of Victorian Scientific Naturalism: Huxley, Spencer and the "End" of natural history.

    Science.gov (United States)

    Lightman, Bernard

    2016-08-01

    As part of their defence of evolutionary theory, T. H. Huxley and Herbert Spencer argued that natural history was no longer a legitimate scientific discipline. They outlined a secularized concept of life from biology to argue for the validity of naturalism. Despite their support for naturalism, they offered two different responses to the decline of natural history. Whereas Huxley emphasized the creation of a biological discipline, and all that that entailed, Spencer was more concerned with constructing an entire intellectual system based on the idea of evolution. In effect, Spencer wanted to create a new scientific worldview based on evolutionary theory. This had consequences for their understanding of human history, especially of how science had evolved through the ages. It affected their conceptions of human agency, contingency, and directionality in history. Examining Huxley's and Spencer's responses to the "end" of natural history reveals some of the deep divisions within scientific naturalism and the inherent problems of naturalism in general. Whereas Huxley chose to separate the natural and the historical, Spencer opted to fuse them into a single system.

  11. Tunicates: exploring the sea shores and roaming the open ocean. A tribute to Thomas Huxley.

    Science.gov (United States)

    Lemaire, Patrick; Piette, Jacques

    2015-06-01

    This review is a tribute to the remarkable contributions of Thomas Huxley to the biology of tunicates, the likely sister group of vertebrates. In 1851, the great biologist and philosopher published two landmark papers on pelagic tunicates in the Philosophical Transactions of the Royal Society. They were dedicated to the description of the adult anatomy and life cycle of thaliaceans and appendicularians, the pelagic relatives of ascidians. In the first part of this review, we discuss the novel anatomical observations and evolutionary hypotheses made by Huxley, which would have a lasting influence on tunicate biology. We also briefly comment on the more philosophical reflections of Huxley on individuality. In the second part, we stress the originality and relevance of past and future studies of tunicates in the resolution of major biological issues. In particular, we focus on the complex relationship between genotype and phenotype and the phenomenon of developmental system drift. We propose that more than 150 years after Huxley's papers, tunicate embryos are still worth studying in their own right, independently of their evolutionary proximity to vertebrates, as they provide original and crucial insights into the process of animal evolution. Tunicates are still at the forefront of biological research.

  12. A Collocation Method for Numerical Solution of the Generalized Burgers-Huxley Equation

    Directory of Open Access Journals (Sweden)

    Mohammad ZAREBNIA

    2014-08-01

    Full Text Available In this paper, we use a collocation method to solve the Burgers-Huxley equation. To achieve this aim, we use mesh free technique based on sinc functions. The stability analysis is discussed. Some numerical examples are provided to illustrate the accuracy and fluency of the method.

  13. Resonant Activation in a Stochastic Hodgkin-Huxley Model: Interplay between noise and suprathreshold driving effect

    DEFF Research Database (Denmark)

    Pankratova, Evgeniya; Polovinkin, A.V.; Mosekilde, Erik

    2005-01-01

    The paper considers an excitable Hodgkin-Huxley system subjected to a strong periodic forcing in the presence of random noise. The influence of the forcing frequency on the response of the system is examined in the realm of suprathreshold amplitudes. Our results confirm that the presence of noise...

  14. Wilberforce, Huxley and the Use of History in Teaching about Evolution.

    Science.gov (United States)

    Gauld, Colin

    1992-01-01

    Author asserts that many historical anecdotes used in science instruction have little basis in reality. The purpose of this paper is to provide a critique of the way in which the "Wilberforce and Huxley debate at Oxford" anecdote is employed in the teaching of evolution and to suggest a more positive role for this incident in science…

  15. On non-linear dynamics and an optimal control synthesis of the action potential of membranes (ideal and non-ideal cases) of the Hodgkin-Huxley (HH) mathematical model

    Energy Technology Data Exchange (ETDEWEB)

    Chavarette, Fabio Roberto [Department of Mechanical Design, State University of Campinas, 13083-970 Campinas, SP (Brazil); State University of Sao Paulo at Rio Claro, C.P. 178, 13500-230 Rio Claro, SP (Brazil); Balthazar, Jose Manoel [Department of Mechanical Design, State University of Campinas, 13083-970 Campinas, SP (Brazil); State University of Sao Paulo at Rio Claro, C.P. 178, 13500-230 Rio Claro, SP (Brazil)], E-mail: jmbaltha@rc.unesp.br; Rafikov, Marat [Universidade Regional do Noroeste do Estado do Rio Grande do Sul 98700-000, C.P. 560, Ijui, RS (Brazil); Hermini, Helder Anibal [Department of Mechanical Design, State University of Campinas, 13083-970 Campinas, SP (Brazil)

    2009-02-28

    In this paper, we have studied the plasmatic membrane behavior using an electric circuit developed by Hodgkin and Huxley in 1952 and have dealt with the variation of the amount of time related to the potassium and sodium conductances in the squid axon. They developed differential equations for the propagation of electric signals; the dynamics of the Hodgkin-Huxley model have been extensively studied both from the view point of its their biological implications and as a test bed for numerical methods, which can be applied to more complex models. Recently, an irregular chaotic movement of the action potential of the membrane was observed for a number of techniques of control with the objective to stabilize the variation of this potential. This paper analyzes the non-linear dynamics of the Hodgkin-Huxley mathematical model, and we present some modifications in the governing equations of the system in order to make it a non-ideal one (taking into account that the energy source has a limited power supply). We also developed an optimal linear control design for the action potential of membranes. Here, we discuss the conditions that allow the use of control linear feedback for this kind of non-linear system.

  16. Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo

    Directory of Open Access Journals (Sweden)

    Ruhschulte Hainer

    2008-07-01

    Full Text Available Abstract Background The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible. Methods The myograph presented in our study has two newly developed technical units, i.e. a. a counterforce unit which can load the muscle with an adjustable, but constant force and b. a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions. Results The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant – uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions. Conclusion With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed.

  17. Pregnancy as protest in interwar British women's writing: an antecedent alternative to Aldous Huxley's Brave New World.

    Science.gov (United States)

    Bigman, Fran

    2016-12-01

    Accounts that take Aldous Huxley's Brave New World (1932) as representative of interwar reproductive dystopia fail to recognise that the novel expresses both an interest and an anxiety about the possibility of new reproductive technologies to transform sex, gender, and the family that were widely shared by writers in different genres and perhaps expressed best by those likely to be most affected: women. This article explores three earlier works-Charlotte Haldane's Man's World (1926), Vera Brittain's Halcyon, or the Future of Monogamy (1929), and Naomi Mitchison's Comments on Birth Control (1930)-in which pregnancy, instead of figuring as illness or debility, becomes a form of resistance to the status quo. These works engage with biomedicine, however, rather than abjuring it. Through a reading of these works, this article argues that the intersection of medical humanities and science fiction (SF) can enrich both: medical humanities can push SF to go beyond the canon, and SF can challenge any characterisation of literature in the medical humanities as purely fantastical by demonstrating how it responds to the hopes and anxieties of a particular time. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  18. Comparison of Spectral and Differential Quadrature Methods for Solving the Burger-Huxley Equation

    Directory of Open Access Journals (Sweden)

    Jalal Izadian

    2013-06-01

    Full Text Available In this paper, the Burger-Huxley equation is solved by two methods: Spectral method and Differential Quadrature Method (DQM. The Chebyshev-Gauss-Lobatto point distribution is utilized in spectral method. The integrity and computational accuracy of the spectral method in solving some test problems are demonstrated through various case studies. The results show that spectral method is more accurate than DQM.

  19. Development of Galerkin Method for Solving the Generalized Burger's-Huxley Equation

    Directory of Open Access Journals (Sweden)

    M. El-Kady

    2013-01-01

    Full Text Available Numerical treatments for the generalized Burger's—Huxley GBH equation are presented. The treatments are based on cardinal Chebyshev and Legendre basis functions with Galerkin method. Gauss quadrature formula and El-gendi method are used to convert the problem into a system of ordinary differential equations. The numerical results are compared with the literatures to show efficiency of the proposed methods.

  20. Thomas Henry Huxley (1825-1895) puts us in our place.

    Science.gov (United States)

    Weiss, Kenneth M

    2004-05-15

    Thomas Huxley was one of the 19th century's most active defenders of Darwin's idea that life has evolved through natural processes. An anatomist and paleontologist, he extended his energies to science and education policy, the democratization of science, and the broad societal implications of evolution. Since his time the fossil record has greatly improved and the genetic 'revolution' has occurred, deepening our understanding of primate and human evolution in ways that would please Huxley: improved systematics relies heavily on genetic data, and molecular technologies are opening our understanding of the genetic basis of complex traits of traditional anthropological interest-but in ways that are thoroughly dependent on the fact of evolution. A more unified biological synthesis is forming that unites genes, developmental process, structure, and inheritance. But the tempo and mode of evolution remain unresolved. Huxley was one of many who have had trouble accepting Darwin's gradual natural selection as the central evolutionary mechanism, and views spanning the antipodes of gradualism and saltation find advocates even in our genetic era.

  1. Extending the conditions of application of an inversion of the Hodgkin-Huxley gating model.

    Science.gov (United States)

    Raba, Ashley E; Cordeiro, Jonathan M; Antzelevitch, Charles; Beaumont, Jacques

    2013-05-01

    We present an inversion of the Hodgkin-Huxley formalism to estimate initial conditions and model parameters, including functions of voltage, from the solutions of the underlying ordinary differential equation (ODE) subjected to multiple voltage step stimulations. As such, the procedure constitutes a means to estimate the parameters including functions of voltage of an Hodgkin-Huxley formalism from experimental data.The basic idea was developed in a previous communication (SIAM J. Appl. Math. 64:1264-1274, 2009). The inversion in question applies to currents exhibiting activation and inactivation, but the version, as published previously, cannot estimate the unknowns for channels that rapidly inactivate just after a brief opening. In such cases, the amplitude of the current, in a given voltage range, is too small to be detectable by the instrumentation using previously applied experimental protocols. This is, for example, the case for the sodium channels in a number of excitable tissue for potential in the vicinity of the cell resting potential. The current communication extends the inversion procedure in a manner to overcome this limitation.Furthermore, within the inversion framework, we can determine whether the data at the basis of the estimation sufficiently constrains the estimation problem, i.e., whether it is complete. We exploit this element of our method to document a set of stimulation protocols that constitute a complete data set for the purpose of inverting the Hodgkin-Huxley formalism.

  2. Effects of information transmission delay and channel blocking on synchronization in scale-free Hodgkin-Huxley neuronal networks

    Science.gov (United States)

    Wang, Qing-Yun; Zheng, Yan-Hong

    2011-12-01

    In this paper, we investigate the evolution of spatiotemporal patterns and synchronization transitions in dependence on the information transmission delay and ion channel blocking in scale-free neuronal networks. As the underlying model of neuronal dynamics, we use the Hodgkin-Huxley equations incorporating channel blocking and intrinsic noise. It is shown that delays play a significant yet subtle role in shaping the dynamics of neuronal networks. In particular, regions of irregular and regular propagating excitatory fronts related to the synchronization transitions appear intermittently as the delay increases. Moreover, the fraction of working sodium and potassium ion channels can also have a significant impact on the spatiotemporal dynamics of neuronal networks. As the fraction of blocked sodium channels increases, the frequency of excitatory events decreases, which in turn manifests as an increase in the neuronal synchrony that, however, is dysfunctional due to the virtual absence of large-amplitude excitations. Expectedly, we also show that larger coupling strengths improve synchronization irrespective of the information transmission delay and channel blocking. The presented results are also robust against the variation of the network size, thus providing insights that could facilitate understanding of the joint impact of ion channel blocking and information transmission delay on the spatiotemporal dynamics of neuronal networks.

  3. Effects of information transmission delay and channel blocking on synchronization in scale-free Hodgkin-Huxley neuronal networks

    Institute of Scientific and Technical Information of China (English)

    Qing-Yun Wang; Yan-Hong Zheng

    2011-01-01

    In this paper,we investigate the evolution of spatiotemporal patterns and synchronization transitions in dependence on the information transmission delay and ion channel blocking in scale-free neuronal networks.As the underlying model of neuronal dynamics,we use the HodgkinHuxley equations incorporating channel blocking and intrinsic noise.It is shown that delays play a significant yet subtle role in shaping the dynamics of neuronal networks.In particular,regions of irregular and regular propagating excitatory fronts related to the synchronization transitions appear intermittently as the delay increases.Moreover,the fraction of working sodium and potassium ion channels can also have a significant impact on the spatiotemporal dynamics of neuronal networks.As the fraction of blocked sodium channels increases,the frequency of excitatory events decreases,which in turn manifests as an increase in the neuronal synchrony that,however,is dysfunctional due to the virtual absence of large-amplitude excitations.Expectedly,we also show that larger coupling strengths improve synchronization irrespective of the information transmission delay and channel blocking.The presented results are also robust against the variation of the network size,thus providing insights that could facilitate understanding of the joint impact of ion channel blocking and information transmission delay on the spatiotemporal dynamics of neuronal networks.

  4. 一类广义 Burgers-Huxley 方程的解与其分支%Solutions and Its Bifurcation for a Generalized Burgers-Huxley Equation

    Institute of Scientific and Technical Information of China (English)

    王勤龙; 邓习军

    2010-01-01

    运用平面动力系统分支理论和可积性判定方法,研究了一类广义 Burgers-Huxley 方程,首先通过新的算法计算奇点量,解决了其可积性问题,然后进行平衡点类型分析,并讨论了在不同的参数条件下的相图与分支类型,利用 Maple 软件绘出分支相图,最后讨论了各种行波解的存在性及方程的精确解.

  5. Rival Visions: J.J. Rousseau and T.H. Huxley on the Nature (or Nurture) of Inequality and What It Means for Education

    Science.gov (United States)

    Currie-Knight, Kevin

    2011-01-01

    Jean-Jacques Rousseau (1712-1778) and Thomas Huxley (1852-1895) had different, but substantial, effects on the history of education. Rousseau's educational theories supplied the intellectual foundation for pedagogical progressivism. Huxley's educational writings helped to enlarge the scope of the British curriculum to include such things as…

  6. “Providing a Roof That Allows One to Dream of a Better Life”: A Case Study of Working with Families in Extreme Poverty

    Directory of Open Access Journals (Sweden)

    Maria Tsekoura

    2015-04-01

    Full Text Available This paper presents a case study of a youth organisation working with families in extreme poverty and lack of adequate housing in Chile and Mexico. It initially describes the considerable structural changes that relate to the emergence of the organisation, and then discusses how across context case study research that draws from the interpretivist interactionist tradition was employed. In the main body it presents interventions that aim to provide families with temporary accommodation, social support, education, micro-credit opportunities, and legal support. The paper aims to contribute to a discussion concerning wider insights to be gained from context-specific approaches in working with families. The article highlights the need for policy and practice that approaches families as complex, dynamic and context specific entities that are re-configured through their networks and interpersonal interactions, and are subject to particular plays of power relations. Furthermore, it argues for practice that fosters family agency that is based on recognition of strengths, emotional and cognitive aspects of decision making as well as nurturing of hope.

  7. Channel noise effects on first spike latency of a stochastic Hodgkin-Huxley neuron

    Science.gov (United States)

    Maisel, Brenton; Lindenberg, Katja

    2017-02-01

    While it is widely accepted that information is encoded in neurons via action potentials or spikes, it is far less understood what specific features of spiking contain encoded information. Experimental evidence has suggested that the timing of the first spike may be an energy-efficient coding mechanism that contains more neural information than subsequent spikes. Therefore, the biophysical features of neurons that underlie response latency are of considerable interest. Here we examine the effects of channel noise on the first spike latency of a Hodgkin-Huxley neuron receiving random input from many other neurons. Because the principal feature of a Hodgkin-Huxley neuron is the stochastic opening and closing of channels, the fluctuations in the number of open channels lead to fluctuations in the membrane voltage and modify the timing of the first spike. Our results show that when a neuron has a larger number of channels, (i) the occurrence of the first spike is delayed and (ii) the variation in the first spike timing is greater. We also show that the mean, median, and interquartile range of first spike latency can be accurately predicted from a simple linear regression by knowing only the number of channels in the neuron and the rate at which presynaptic neurons fire, but the standard deviation (i.e., neuronal jitter) cannot be predicted using only this information. We then compare our results to another commonly used stochastic Hodgkin-Huxley model and show that the more commonly used model overstates the first spike latency but can predict the standard deviation of first spike latencies accurately. We end by suggesting a more suitable definition for the neuronal jitter based upon our simulations and comparison of the two models.

  8. The neuron physiology and Hodgkin-Huxley and FitzHugh-Nagumo models

    OpenAIRE

    2007-01-01

    Resumo: Apresentaremos neste trabalho descrições detalhadas da modelagem e conceitos fisiológicos associados aos modelos de Hodgkin-Huxley e Fitzhugh-Nagumo, para em seguida compararmos suas características. Tentaremos justificar a opção pelo modelo de Fitzhugh-Nagumo como objeto de estudo viável pra interações entre neurônios, e em seguida introduziremos um tipo de interação na qual o comportamento do sistema para dois neurônios apresenta fenômenos de comportamento irregular. Para isso, most...

  9. Thermal impact on spiking properties in Hodgkin-Huxley neuron with synaptic stimulus

    Indian Academy of Sciences (India)

    Shenbing Kuang; Jiafu Wang; Ting Zeng; Aiyin Cao

    2008-01-01

    The effect of environmental temperature on neuronal spiking behaviors is investigated by numerically simulating the temperature dependence of spiking threshold of the Hodgkin-Huxley neuron subject to synaptic stimulus. We find that the spiking threshold exhibits a global minimum in a specific temperature range where spike initiation needs weakest synaptic strength, which form the engineering perspective indicates the occurrence of optimal use of synaptic transmission in the nervous system. We further explore the biophysical origin of this phenomenon associated with ion channel gating kinetics and also discuss its possible biological relevance in information processing in neuronal systems.

  10. Non-Gaussian Colored Noise Optimized Spatial Coherence of a Hodgkin—Huxley Neuronal Network

    Science.gov (United States)

    Sun, Xiao-Juan; Lu, Qi-Shao

    2014-02-01

    We numerically study how non-Gaussian colored noise affects the spatial coherence of a Hodgkin—Huxley neuronal network. From the simulation results, we find that there exists some intermediate noise intensities, correlation time of the colored noise, and the deviation from Gaussian colored noise, for which an ordered pattern with a characteristic spatial frequency of the system comes forth in a resonant manner. Namely, under certain conditions, spatial coherence of the studied neuronal network can be optimized by the non-Gaussian colored noise, which indicates the occurrence of spatial coherence resonance.

  11. Unidirectional synchronization of Hodgkin-Huxley neurons exposed to ELF electric field

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jiang [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)], E-mail: jiangwang@tju.edu.cn; Che Yanqiu; Zhou Sisi; Deng Bin [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

    2009-02-15

    In this paper, a hybrid control strategy, H{sub {infinity}} variable universe adaptive fuzzy control, is derived and applied to synchronize two Hodgkin-Huxley (HH) neurons exposed to external electric field. Firstly, the modified model of HH neuron exposed to extremely low frequency (ELF) external electric field is established and its periodic and chaotic dynamics in response to sinusoidal electric field stimulation are described. And then the statement of the problem for unidirectional synchronization of two HH neurons is given. Finally H{sub {infinity}} variable universe adaptive fuzzy control is designed to synchronize the HH systems and the simulation results demonstrate the effectiveness of the proposed control method.

  12. Responses of Hodgkin-Huxley Neuronal Systems to Spike-Train Inputs

    Institute of Scientific and Technical Information of China (English)

    CHANG Wen-Li; WANG Sheng-Jun; WANG Ying-Hai

    2007-01-01

    We investigate responses of the Hodgkin-Huxley globally neuronal systems to periodic spike-train inputs. The firing activities of the neuronal networks show different rhythmic patterns for different parameters. These rhythmic patterns can be used to explain cycles of firing in real brain. These activity patterns, average activity and coherence measure are affected by two quantities such as the percentage of excitatory couplings and stimulus intensity, in which the percentage of excitatory couplings is more important than stimulus intensity since the transition phenomenon of average activity comes about.

  13. Soliton-like solutions to the generalized Burgers-Huxley equation with variable coefficients

    Science.gov (United States)

    Triki, Houria; Wazwaz, Abdul-Majid

    2013-12-01

    In this paper, we consider the generalized Burgers-Huxley equation with arbitrary power of nonlinearity and timedependent coefficients. We analyze the traveling wave problem and explicitly find new soliton-like solutions for this extended equation by using the ansatz of Zhao et al. [X. Zhao, D. Tang, L. Wang, Phys. Lett. A 346 (2005) 288-291]. We also employ the solitary wave ansatz method to derive the exact bright and dark soliton solutions for the considered evolution equation. The physical parameters in the soliton solutions are obtained as function of the time-dependent model coefficients. The conditions of existence of solitons are presented. As a result, rich exact travelling wave solutions, which contain new soliton-like solutions, bell-shaped solitons and kink-shaped solitons for the generalized Burgers-Huxley equation with time-dependent coefficients, are obtained. The methods employed here can also be used to solve a large class of nonlinear evolution equations with variable coefficients.

  14. Spiking sychronization regulated by noise in three types of Hodgkin-Huxley neuronal networks

    Institute of Scientific and Technical Information of China (English)

    Zhang Zheng-Zhen; Zeng Shang-You; Tang Wen-Yan; Hu Jin-Lin; Zeng Shao-Wen; Ning Wei-Lian; Qiu Yi; Wu Hui-Si

    2012-01-01

    In this paper,we study spiking synchronization in three different types of Hodgkin-Huxley neuronal networks,which are the small-world,regular,and random neuronal networks. All the neurons are subjected to subthreshold stimulus and external noise. It is found that in each of all the neuronal networks there is an optimal strength of noise to induce the maximal spiking synchronization.We further demonstrate that in each of the neuronal networks there is a range of synaptic conductance to induce the effect that an optimal strength of noise maximizes the spiking synchronization.Only when the magnitude of the synaptic conductance is moderate,will the effect be considerable.However,if the synaptic conductance is small or large,the effect vanishes.As the connections between neurons increase,the synaptic conductance to maximize the effect decreases.Therefore,we show quantitatively that the noise-induced maximal synchronization in the Hodgkin-Huxley neuronal network is a general effect,regardless of the specific type of neuronal network.

  15. The influence of ion concentrations on the dynamic behavior of the Hodgkin-Huxley model-based cortical network.

    Science.gov (United States)

    Tagluk, M Emin; Tekin, Ramazan

    2014-08-01

    Action potentials (APs) in the form of very short pulses arise when the cell is excited by any internal or external stimulus exceeding the critical threshold of the membrane. During AP generation, the membrane potential completes its natural cycle through typical phases that can be formatted by ion channels, gates and ion concentrations, as well as the synaptic excitation rate. On the basis of the Hodgkin-Huxley cell model, a cortical network consistent with the real anatomic structure is realized with randomly interrelated small population of neurons to simulate a cerebral cortex segment. Using this model, we investigated the effects of Na(+) and K(+) ion concentrations on the outcome of this network in terms of regularity, phase locking, and synchronization. The results suggested that Na(+) concentration does slightly affect the amplitude but not considerably affects the other parameters specified by depolarization and repolarization. K(+) concentration significantly influences the form, regularity, and synchrony of the network-generated APs. No previous study dealing directly with the effects of both Na(+) and K(+) ion concentrations on regularity and synchronization of the simulated cortical network-generated APs, allowing for the comparison of results obtained using our methods, was encountered in the literature. The results, however, were consistent with those obtained through studies concerning resonance and synchronization from another perspective and with the information revealed through physiological and pharmacological experiments concerning changing ion concentrations or blocking ion channels. Our results demonstrated that the regularity and reliability of brain functions have a strong relationship with cellular ion concentrations, and suggested the management of the dynamic behavior of the cellular network with ion concentrations.

  16. Hugh E. Huxley: cambiando el paradigma de la contracción muscular, desde dentro. [Hugh E. Huxley: changing from inside the paradigm of muscle contraction].

    Directory of Open Access Journals (Sweden)

    Adolfo Araci

    2014-04-01

    Full Text Available Desde un punto de vista físico se puede entender la fibra muscular como un motor, es decir, un sistema capaz de transformar la energía química en energía mecánica, que se utiliza para realizar un trabajo. Por lo tanto, para entender cómo ocurre dicho proceso de transformación es necesario conocer la ultraestructura de la fibra muscular. Esta es, sin duda, la principal aportación al acervo científico del recientemente fallecido Hugh Emor Huxley (1924-2013. Huxley se graduó en Física en el Christ’s College de Cambdrige, tras ver interrumpidos temporalmente sus estudios por su dedicación como operario de radar de la Royal Air Force entre 1943 y 1947, durante la Segunda Guerra Mundial (Pollard y Goldman, 2013; Spudich, 2013. Tras su graduación se incorporó como el primer estudiante de doctorado a una unidad de nueva creación del Medical Research Council, el “Laboratorio de Biología Molecular”, dirigida por Max Perutz y John Kendrew, siendo este último el director de sus tesis doctoral, que fue defendida en 1952 (Spudich, 2013. El uso de la técnicas de difracción de rayos X, que permitían el estudio en niveles de resolución inalcanzables con las técnicas microscópicas del momento, y su aplicación a la descripción de la ultraestructura muscular, fueron el objeto de su tesis doctoral, para el desarrollo de la cual diseñó y construyó sus propios instrumentos. El esclarecimiento de los aspectos estructurales implicados en la contracción muscular se convirtió desde entonces en la pregunta central de su biografía científica.

  17. Work.

    Science.gov (United States)

    Haines, Annette M.

    2003-01-01

    Draws upon Maria Montessori's writings to examine work as a universal human tendency throughout life. Discusses the work of adaptation of the infant, work of "psycho-muscular organism" for the preschooler, work of the imagination for the elementary child, community work of the adolescent, and work of the adult. Asserts that…

  18. Homoclinic bifurcation in a Hodgkin-Huxley model of thermally sensitive neurons

    Energy Technology Data Exchange (ETDEWEB)

    Feudel, Ulrike [Department of Physics, University of Potsdam, Potsdam 14415, (Germany); Neiman, Alexander [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Pei, Xing [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Wojtenek, Winfried [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Braun, Hans [Institute of Physiology, University of Marburg, Marburg 35037, (Germany); Huber, Martin [Institute of Physiology, University of Marburg, Marburg 35037, (Germany); Moss, Frank [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States)

    2000-03-01

    We study global bifurcations of the chaotic attractor in a modified Hodgkin-Huxley model of thermally sensitive neurons. The control parameter for this model is the temperature. The chaotic behavior is realized over a wide range of temperatures and is visualized using interspike intervals. We observe an abrupt increase of the interspike intervals in a certain temperature region. We identify this as a homoclinic bifurcation of a saddle-focus fixed point which is embedded in the chaotic attractors. The transition is accompanied by intermittency, which obeys a universal scaling law for the average length of trajectory segments exhibiting only short interspike intervals with the distance from the onset of intermittency. We also present experimental results of interspike interval measurements taken from the crayfish caudal photoreceptor, which qualitatively demonstrate the same bifurcation structure. (c) 2000 American Institute of Physics.

  19. A correspondence between the models of Hodgkin-Huxley and FitzHugh-Nagumo revisited

    Science.gov (United States)

    Postnikov, Eugene B.; Titkova, Olga V.

    2016-11-01

    We present the discussion on the possibility to scale the classical dimensionless FitzHugh-Nagumo model of neuronal self-sustained oscillations to the range of variables corresponding to the results, which are provided by the biophysically relevant reduced two-dimensional Hodgkin-Huxley equations (the Rinzel model). It is shown that there exists a relatively simple choice of affine transformation, which results in time-dependent solutions, which reproduce with a high accuracy the time course of the recovery variable and the sharp onsets (intervals of fast motions on a phase trajectories) of the voltage spikes. As for the latter, the reasons for unavoidable difference are discussed as well as a necessity of taking into account applied current values during such a scaling procedure.

  20. Identifying generalized Fitzhugh-Nagumo equation from a numerical solution of Hodgkin-Huxley model

    Directory of Open Access Journals (Sweden)

    Nikola V. Georgiev

    2003-01-01

    Full Text Available An analytic time series in the form of numerical solution (in an appropriate finite time interval of the Hodgkin-Huxley current clamped (HHCC system of four differential equations, well known in the neurophysiology as an exact empirical model of excitation of a giant axon of Loligo, is presented. Then we search for a second-order differential equation of generalized Fitzhugh-Nagumo (GFN type, having as a solution the given single component (action potential of the numerical solution. The given time series is used as a basis for reconstructing orders, powers, and coefficients of the polynomial right-hand sides of GFN equation approximately governing the process of action potential. For this purpose, a new geometrical method for determining phase space dimension of the unknown dynamical system (GFN equation and a specific modification of least squares method for identifying unknown coefficients are developed and applied.

  1. Temperature Effects on Information Capacity and Energy Efficiency of Hodgkin-Huxley Neuron

    CERN Document Server

    Wang, Long-Fei; Liu, Xiao-Zhi; Song, Ya-lei; Yu, Lian-Chun

    2015-01-01

    Recent experimental and theoretical studies show that energy efficiency, which measures the amount of information processed by a neuron with per unit of energy consumption, plays an important role in the evolution of neural systems. Here, we calculated the information rates and energy efficiencies of the Hodgkin-Huxley (HH) neuron model at different temperatures in a noisy environment. We found that both the information rate and energy efficiency are maximized by certain temperatures. Though the information rate and energy efficiency cannot be maximized simultaneously, the neuron holds a high information processing capacity at the temperature corresponding to maximal energy efficiency. Our results support the idea that the energy efficiency is a selective pressure that influences the evolution of nervous systems.

  2. In-phase and anti-phase synchronization in noisy Hodgkin-Huxley neurons

    CERN Document Server

    Schmid, Gerhard; Hanggi, Peter

    2013-01-01

    We numerically investigate the influence of intrinsic channel noise on the dynamical response of delay-coupling in neuronal systems. The stochastic dynamics of the spiking is modeled within a stochastic modification of the standard Hodgkin-Huxley model wherein the delay-coupling accounts for the finite propagation time of an action potential along the neuronal axon. We quantify this delay-coupling of the Pyragas-type in terms of the difference between corresponding presynaptic and postsynaptic membrane potentials. In case of a single neuron we analyze the spiking activity in presence of an autaptic feedback loop. With vanishing channel noise the interspike interval increases with increasing delay time. For an elementary neuronal network consisting of two coupled neurons we detect characteristic stochastic synchronization patterns which exhibit multiple phase-flip bifurcations: The phase-flip bifurcations occur in form of alternate transitions from an in-phase spiking activity towards an anti-phase spiking act...

  3. Emergent Central Pattern Generator Behavior in Gap-Junction-Coupled Hodgkin-Huxley Style Neuron Model

    Directory of Open Access Journals (Sweden)

    Kyle G. Horn

    2012-01-01

    Full Text Available Most models of central pattern generators (CPGs involve two distinct nuclei mutually inhibiting one another via synapses. Here, we present a single-nucleus model of biologically realistic Hodgkin-Huxley neurons with random gap junction coupling. Despite no explicit division of neurons into two groups, we observe a spontaneous division of neurons into two distinct firing groups. In addition, we also demonstrate this phenomenon in a simplified version of the model, highlighting the importance of afterhyperpolarization currents ( to CPGs utilizing gap junction coupling. The properties of these CPGs also appear sensitive to gap junction conductance, probability of gap junction coupling between cells, topology of gap junction coupling, and, to a lesser extent, input current into our simulated nucleus.

  4. Dynamic range in small-world networks of Hodgkin-Huxley neurons with chemical synapses

    Science.gov (United States)

    Batista, C. A. S.; Viana, R. L.; Lopes, S. R.; Batista, A. M.

    2014-09-01

    According to Stevens' law the relationship between stimulus and response is a power-law within an interval called the dynamic range. The dynamic range of sensory organs is found to be larger than that of a single neuron, suggesting that the network structure plays a key role in the behavior of both the scaling exponent and the dynamic range of neuron assemblies. In order to verify computationally the relationships between stimulus and response for spiking neurons, we investigate small-world networks of neurons described by the Hodgkin-Huxley equations connected by chemical synapses. We found that the dynamic range increases with the network size, suggesting that the enhancement of the dynamic range observed in sensory organs, with respect to single neurons, is an emergent property of complex network dynamics.

  5. Rhythmic Oscillations of Excitatory Bursting Hodkin-Huxley Neuronal Network with Synaptic Learning.

    Science.gov (United States)

    Shi, Qi; Han, Fang; Wang, Zhijie; Li, Caiyun

    2016-01-01

    Rhythmic oscillations of neuronal network are actually kind of synchronous behaviors, which play an important role in neural systems. In this paper, the properties of excitement degree and oscillation frequency of excitatory bursting Hodkin-Huxley neuronal network which incorporates a synaptic learning rule are studied. The effects of coupling strength, synaptic learning rate, and other parameters of chemical synapses, such as synaptic delay and decay time constant, are explored, respectively. It is found that the increase of the coupling strength can weaken the extent of excitement, whereas increasing the synaptic learning rate makes the network more excited in a certain range; along with the increasing of the delay time and the decay time constant, the excitement degree increases at the beginning, then decreases, and keeps stable. It is also found that, along with the increase of the synaptic learning rate, the coupling strength, the delay time, and the decay time constant, the oscillation frequency of the network decreases monotonically.

  6. Temperature Effects on Information Capacity and Energy Efficiency of Hodgkin-Huxley Neuron

    Science.gov (United States)

    Wang, Long-Fei; Jia, Fei; Liu, Xiao-Zhi; Song, Ya-Lei; Yu, Lian-Chun

    2015-10-01

    Recent experimental and theoretical studies show that energy efficiency, which measures the amount of information processed by a neuron with per unit of energy consumption, plays an important role in the evolution of neural systems. Here, we calculated the information rates and energy efficiencies of the Hodgkin-Huxley (HH) neuron model at different temperatures in a noisy environment. We found that both the information rate and energy efficiency are maximized by certain temperatures. Though the information rate and energy efficiency cannot be maximized simultaneously, the neuron holds a high information processing capacity at the temperature corresponding to maximal energy efficiency. Our results support the idea that the energy efficiency is a selective pressure that influences the evolution of nervous systems.

  7. Delay-enhanced coherence of spiral waves in noisy Hodgkin-Huxley neuronal networks

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qingyun [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China) and School of Statistics and Mathematics, Inner Mongolia Finance and Economics College, Huhhot 010051 (China)], E-mail: nmqingyun@163.com; Perc, Matjaz [Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroska cesta 160, SI-2000 Maribor (Slovenia); Duan Zhisheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China); Chen Guanrong [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China); Department of Electronic Engineering, City University of Hong Kong, Hong Kong (China)

    2008-08-25

    We study the spatial dynamics of spiral waves in noisy Hodgkin-Huxley neuronal ensembles evoked by different information transmission delays and network topologies. In classical settings of coherence resonance the intensity of noise is fine-tuned so as to optimize the system's response. Here, we keep the noise intensity constant, and instead, vary the length of information transmission delay amongst coupled neurons. We show that there exists an intermediate transmission delay by which the spiral waves are optimally ordered, hence indicating the existence of delay-enhanced coherence of spatial dynamics in the examined system. Additionally, we examine the robustness of this phenomenon as the diffusive interaction topology changes towards the small-world type, and discover that shortcut links amongst distant neurons hinder the emergence of coherent spiral waves irrespective of transmission delay length. Presented results thus provide insights that could facilitate the understanding of information transmission delay on realistic neuronal networks.

  8. Synchronization control of Hodgkin-Huxley neurons exposed to ELF electric field

    Energy Technology Data Exchange (ETDEWEB)

    Che Yanqiu [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China); Wang Jiang [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)], E-mail: jiangwang@tju.edu.cn; Zhou Sisi; Deng Bin [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

    2009-05-30

    This paper presents an adaptive neural network H{sub {infinity}} control for unidirectional synchronization of modified Hodgkin-Huxley (HH) neurons exposed to extremely low frequency (ELF) electric field. The proposed modified HH neurons exhibit periodic and chaotic dynamics in response to sinusoidal electric field stimulation. Based on the Lyapunov stability theory, we derive the updated laws of neural network for approximating the nonlinear uncertain functions of the error dynamical system. The H{sub {infinity}} design technique makes the controller robust to unmodeled dynamics, disturbances and approximate errors. The proposed controller not only ensures closed-loop stability, but also guarantees an H{sub {infinity}} performance for the synchronization error system. The states of the controlled slave system exponentially synchronize with that of the master one after control. The simulation results demonstrate the validity of the proposed method.

  9. Autaptic activity-induced synchronization transitions in Newman-Watts network of Hodgkin-Huxley neurons

    Science.gov (United States)

    Wu, Yanan; Gong, Yubing; Wang, Qi

    2015-04-01

    In this paper, we numerically study the effect of autapse on the synchronization of Newman-Watts small-world Hodgkin-Huxley neuron network. It is found that the neurons exhibit synchronization transitions as autaptic self-feedback delay is varied, and the phenomenon becomes strongest when autaptic self-feedback strength is optimal. This phenomenon also changes with the change of coupling strength and network randomness and become strongest when they are optimal. There are similar synchronization transitions for electrical and chemical autapse, but the synchronization transitions for chemical autapse occur more frequently and are stronger than those for electrical synapse. The underlying mechanisms are briefly discussed in quality. These results show that autaptic activity plays a subtle role in the synchronization of the neuronal network. These findings may find potential implications of autapse for the information processing and transmission in neural systems.

  10. Dynamic Behavior of Artificial Hodgkin-Huxley Neuron Model Subject to Additive Noise.

    Science.gov (United States)

    Kang, Qi; Huang, BingYao; Zhou, MengChu

    2016-09-01

    Motivated by neuroscience discoveries during the last few years, many studies consider pulse-coupled neural networks with spike-timing as an essential component in information processing by the brain. There also exists some technical challenges while simulating the networks of artificial spiking neurons. The existing studies use a Hodgkin-Huxley (H-H) model to describe spiking dynamics and neuro-computational properties of each neuron. But they fail to address the effect of specific non-Gaussian noise on an artificial H-H neuron system. This paper aims to analyze how an artificial H-H neuron responds to add different types of noise using an electrical current and subunit noise model. The spiking and bursting behavior of this neuron is also investigated through numerical simulations. In addition, through statistic analysis, the intensity of different kinds of noise distributions is discussed to obtain their relationship with the mean firing rate, interspike intervals, and stochastic resonance.

  11. Environmental Impacts on Spiking Properties in Hodgkin-Huxley Neuron with Direct Current Stimulus

    Institute of Scientific and Technical Information of China (English)

    YUAN Chang-Qing; ZHAO Tong-Jun; ZHAN Yong; ZHANG Su-Hua; LIU Hui; ZHANG Yu-Hong

    2009-01-01

    Based on the well accepted Hodgkin-Huxley neuron model, the neuronal intrinsic excitability is studied when the neuron is subject to varying environmental temperatures, the typical impact for its regulating ways. With computer simulation, it is found that altering environmental temperature can improve or inhibit the neuronal intrinsic excitability so as to influence the neuronal spiking properties. The impacts from environmental factors can be understood that ,the neuronal spiking threshold is essentially influenced by the fluctuations in the environ-ment. With the environmental temperature varying, burst spiking is realized for the neuronal membrane voltage because of the environment-dependent spiking threshold. This burst induced by changes in spiking threshold is different from that excited by input currents or other stimulus.

  12. Studies of phase return map and symbolic dynamics in a periodically driven Hodgkin—Huxley neuron

    Science.gov (United States)

    Ding, Jiong; Zhang, Hong; Tong, Qin-Ye; Chen, Zhuo

    2014-02-01

    How neuronal spike trains encode external information is a hot topic in neurodynamics studies. In this paper, we investigate the dynamical states of the Hodgkin—Huxley neuron under periodic forcing. Depending on the parameters of the stimulus, the neuron exhibits periodic, quasiperiodic and chaotic spike trains. In order to analyze these spike trains quantitatively, we use the phase return map to describe the dynamical behavior on a one-dimensional (1D) map. According to the monotonicity or discontinuous point of the 1D map, the spike trains are transformed into symbolic sequences by implementing a coarse-grained algorithm — symbolic dynamics. Based on the ordering rules of symbolic dynamics, the parameters of the external stimulus can be measured in high resolution with finite length symbolic sequences. A reasonable explanation for why the nervous system can discriminate or cognize the small change of the external signals in a short time is also presented.

  13. Noise-induced synchronization in a lattice Hodgkin-Huxley neural network

    Science.gov (United States)

    Pang, James Christopher S.; Monterola, Christopher P.; Bantang, Johnrob Y.

    2014-01-01

    We examine how the synchronization of the series of action potentials (APs) of realistic neurons interconnected in a lattice is influenced by variations of both the direction and magnitude of neuron-neuron connectivity in a noisy environment. We first demonstrate the existence of an optimal noise level that brings about the highest average number of APs per unit time, for a single Hodgkin-Huxley neuron. We then show that synchronization, as a collective response of interconnected neurons forming an N×N lattice, is optimal at different noise strengths σc=σc(p), depending on the degree of random-link malfunction parameterized by flipping direction probability p. Thus, even without the scale-free structure of neuronal networks, proper combinations of both randomness in reconnection (flipping) and noisy environment can be beneficial to the collective functioning of neurons.

  14. Langevin approach with rescaled noise for stochastic channel dynamics in Hodgkin-Huxley neurons

    Science.gov (United States)

    Huang, Yan-Dong; Xiang, Li; Shuai, Jian-Wei

    2015-12-01

    The Langevin approach has been applied to model the random open and closing dynamics of ion channels. It has long been known that the gate-based Langevin approach is not sufficiently accurate to reproduce the statistics of stochastic channel dynamics in Hodgkin-Huxley neurons. Here, we introduce a modified gate-based Langevin approach with rescaled noise strength to simulate stochastic channel dynamics. The rescaled independent gate and identical gate Langevin approaches improve the statistical results for the mean membrane voltage, inter-spike interval, and spike amplitude. Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 11125419), the National Natural Science Foundation of China (Grant No. 10925525), and the Funds for the Leading Talents of Fujian Province, China.

  15. In-phase and anti-phase synchronization in noisy Hodgkin-Huxley neurons.

    Science.gov (United States)

    Ao, Xue; Hänggi, Peter; Schmid, Gerhard

    2013-09-01

    We numerically investigate the influence of intrinsic channel noise on the dynamical response of delay-coupling in neuronal systems. The stochastic dynamics of the spiking is modeled within a stochastic modification of the standard Hodgkin-Huxley model wherein the delay-coupling accounts for the finite propagation time of an action potential along the neuronal axon. We quantify this delay-coupling of the Pyragas-type in terms of the difference between corresponding presynaptic and postsynaptic membrane potentials. For an elementary neuronal network consisting of two coupled neurons we detect characteristic stochastic synchronization patterns which exhibit multiple phase-flip bifurcations: The phase-flip bifurcations occur in form of alternate transitions from an in-phase spiking activity towards an anti-phase spiking activity. Interestingly, these phase-flips remain robust for strong channel noise and in turn cause a striking stabilization of the spiking frequency.

  16. A new domain decomposition algorithm for generalized Burger's-Huxley equation based on Chebyshev polynomials and preconditioning

    Energy Technology Data Exchange (ETDEWEB)

    Javidi, M. [Department of Mathematics, Iran University of Science and Technology, Narmak, Tehran 16844 (Iran, Islamic Republic of)], E-mail: mo_javidi@yahoo.com; Golbabai, A. [Department of Mathematics, Iran University of Science and Technology, Narmak, Tehran 16844 (Iran, Islamic Republic of)], E-mail: golbabai@iust.ac.ir

    2009-01-30

    In this study, we use the spectral collocation method using Chebyshev polynomials for spatial derivatives and fourth order Runge-Kutta method for time integration to solve the generalized Burger's-Huxley equation (GBHE). To reduce round-off error in spectral collocation (pseudospectral) method we use preconditioning. Firstly, theory of application of Chebyshev spectral collocation method with preconditioning (CSCMP) and domain decomposition on the generalized Burger's-Huxley equation presented. This method yields a system of ordinary differential algebric equations (DAEs). Secondly, we use fourth order Runge-Kutta formula for the numerical integration of the system of DAEs. The numerical results obtained by this way have been compared with the exact solution to show the efficiency of the method.

  17. Schizophrenia, evolution and the borders of biology: on Huxley et al.'s 1964 paper in Nature.

    Science.gov (United States)

    De Bont, Raf

    2010-06-01

    In October 1964, Julian Huxley, Ernst Mayr, Humphrey Osmond and Abram Hoffer co-published a controversial paper in Nature, in which they tried to explain the persistence of schizophrenia from an evolutionary perspective. This article will elucidate how the reputed authors composed this paper to make it a strong argument for biological psychiatry. Through a close reading of their correspondence, it will furthermore clarify the elements which remained unspoken in the paper, but which were elementary in its genesis. The first was the dominance of psychoanalytical theory in (American) psychiatry--a dominance which the authors wanted to break. The second was the ongoing discussion on the boundaries of biological determinism and the desirability of a new kind of eugenics. As such, the Huxley et al. paper can be used to study the central issues of psychiatry in a pivotal era of its history.

  18. Travelling solitary wave solutions for the generalized Burgers-Huxley equation with nonlinear terms of any order

    Institute of Scientific and Technical Information of China (English)

    Deng Xi-Jun; Yan Zi-Zong; Han Li-Bo

    2009-01-01

    In this paper,the travelling wave solutions for the generalized Burgers-Huxley equation with nonlinear terms of any order are studied.By using the first integral method,which is based on the divisor theorem,some exact explicit travelling solitary wave solutions for the above equation are obtained.As a result,some minor errors and some known results in the previousl literature are clarified and improved.

  19. Existential concerns and narrative techniques in the novels of Ford Madox Ford, Virginia Wools and Aldous Huxley

    Directory of Open Access Journals (Sweden)

    Radojka Verčko

    2005-12-01

    Full Text Available The article addresses the issue of the close relationship between the nexistential concem and the narrative techniques used by English writers Ford Madox Ford, Virginia Woolf and Aldous Huxley to present the general human condition. The selected authors had introduced narrative techniques that influenced the entire development of the modern  novel and that are stili highly  relevant and widely used in the contemporary novel, including the Slovene modern novel.

  20. Neural Energy Supply-Consumption Properties Based on Hodgkin-Huxley Model

    Science.gov (United States)

    2017-01-01

    Electrical activity is the foundation of the neural system. Coding theories that describe neural electrical activity by the roles of action potential timing or frequency have been thoroughly studied. However, an alternative method to study coding questions is the energy method, which is more global and economical. In this study, we clearly defined and calculated neural energy supply and consumption based on the Hodgkin-Huxley model, during firing action potentials and subthreshold activities using ion-counting and power-integral model. Furthermore, we analyzed energy properties of each ion channel and found that, under the two circumstances, power synchronization of ion channels and energy utilization ratio have significant differences. This is particularly true of the energy utilization ratio, which can rise to above 100% during subthreshold activity, revealing an overdraft property of energy use. These findings demonstrate the distinct status of the energy properties during neuronal firings and subthreshold activities. Meanwhile, after introducing a synapse energy model, this research can be generalized to energy calculation of a neural network. This is potentially important for understanding the relationship between dynamical network activities and cognitive behaviors. PMID:28316842

  1. Neural Energy Supply-Consumption Properties Based on Hodgkin-Huxley Model

    Directory of Open Access Journals (Sweden)

    Yihong Wang

    2017-01-01

    Full Text Available Electrical activity is the foundation of the neural system. Coding theories that describe neural electrical activity by the roles of action potential timing or frequency have been thoroughly studied. However, an alternative method to study coding questions is the energy method, which is more global and economical. In this study, we clearly defined and calculated neural energy supply and consumption based on the Hodgkin-Huxley model, during firing action potentials and subthreshold activities using ion-counting and power-integral model. Furthermore, we analyzed energy properties of each ion channel and found that, under the two circumstances, power synchronization of ion channels and energy utilization ratio have significant differences. This is particularly true of the energy utilization ratio, which can rise to above 100% during subthreshold activity, revealing an overdraft property of energy use. These findings demonstrate the distinct status of the energy properties during neuronal firings and subthreshold activities. Meanwhile, after introducing a synapse energy model, this research can be generalized to energy calculation of a neural network. This is potentially important for understanding the relationship between dynamical network activities and cognitive behaviors.

  2. Biophysical synaptic dynamics in an analog VLSI network of Hodgkin-Huxley neurons.

    Science.gov (United States)

    Yu, Theodore; Cauwenberghs, Gert

    2009-01-01

    We study synaptic dynamics in a biophysical network of four coupled spiking neurons implemented in an analog VLSI silicon microchip. The four neurons implement a generalized Hodgkin-Huxley model with individually configurable rate-based kinetics of opening and closing of Na+ and K+ ion channels. The twelve synapses implement a rate-based first-order kinetic model of neurotransmitter and receptor dynamics, accounting for NMDA and non-NMDA type chemical synapses. The implemented models on the chip are fully configurable by 384 parameters accounting for conductances, reversal potentials, and pre/post-synaptic voltage-dependence of the channel kinetics. We describe the models and present experimental results from the chip characterizing single neuron dynamics, single synapse dynamics, and multi-neuron network dynamics showing phase-locking behavior as a function of synaptic coupling strength. The 3mm x 3mm microchip consumes 1.29 mW power making it promising for applications including neuromorphic modeling and neural prostheses.

  3. Bistability and resonance in the periodically stimulated Hodgkin-Huxley model with noise

    CERN Document Server

    Borkowski, L S

    2010-01-01

    We describe general characteristics of the Hodgkin-Huxley neuron's response to a periodic train of short current pulses with Gaussian noise. The deterministic neuron is bistable for antiresonant frequencies. When the stimuli arrive at the resonant frequency the firing rate is a continuous function of the current amplitude $I_0$ and scales as $(I_0-I_{th})^{1/2}$, where $I_{th}$ is an approximate threshold. Intervals of continuous irregular response alternate with integer mode-locked regions with bistable excitation edge. There is an even-all multimodal transition between the 2:1 and 3:1 states in the vicinity of the main resonance, which is analogous to the odd-all transition discovered earlier in the high-frequency regime. For $I_0

  4. Theoretical analysis of transcranial magneto-acoustical stimulation with Hodgkin–Huxley neuron model

    Directory of Open Access Journals (Sweden)

    Yi eYuan

    2016-04-01

    Full Text Available Transcranial magneto-acoustical stimulation (TMAS is a novel stimulation technology in which an ultrasonic wave within a magnetostatic field generates an electric current in an area of interest in the brain to modulate neuronal activities. As a key part of the neural network, neurons transmit information in the nervous system. However, the effect of TMAS on the neuronal firing rhythm remains unknown. To address this problem, we investigated the stimulatory mechanism of TMAS on neurons with a Hodgkin-Huxley neuron model. The simulation results indicate that the magnetostatic field intensity and ultrasonic power can affect the amplitude and interspike interval of neuronal action potential under continuous wave ultrasound. The simulation results also show that the ultrasonic power, duty cycle and repetition frequency can alter the firing rhythm of neural action potential under pulsed ultrasound. This study can help to reveal and explain the biological mechanism of TMAS and to provide a theoretical basis for TMAS in the treatment or rehabilitation of neuropsychiatric disorders.

  5. Response of the Hodgkin-Huxley neuron to a periodic sequence of biphasic pulses

    CERN Document Server

    Borkowski, L S

    2013-01-01

    We study the response of the Hodgkin-Huxley neuron stimulated periodically by biphasic rectangular current pulses. The optimal response for charge-balanced input is obtained for cathodic-first pulses with an inter-phase gap (IPG) approximately equal 5 ms. For short pulses the topology of the global bifurcation diagram in the period-amplitude plane is approximately invariant with respect to the pulse polarity and shape details. If stimuli are delivered at neuron's resonant frequencies the firing rate is a continuous function of pulse amplitude. At nonresonant frequencies the quiescent state and the firing state coexist over a range of amplitude values and the transition to excitability is a discontinuous one. There is a multimodal odd-all transition between the 2:1 and 3:1 locked-in states. A strong antiresonant effect is found between the states 3:1 and 4:1, where the modes (2+3n):1, $n=0,1,2,...$, are entirely absent. At high frequencies the excitation threshold is a nonmonotonic function of the stimulus and...

  6. Response of a Hodgkin-Huxley neuron to a high-frequency input

    CERN Document Server

    Borkowski, L S

    2010-01-01

    We study the response of a Hodgkin-Huxley neuron stimulated by a periodic sequence of conductance pulses arriving through the synapse in the high frequency regime. In addition to the usual excitation threshold there is a smooth crossover from the firing to the silent regime for increasing pulse amplitude $g_{syn}$. The amplitude of the voltage spikes decreases approximately linearly with $g_{syn}$. In some regions of parameter space the response is irregular, probably chaotic. In the chaotic regime between the mode-locked regions 3:1 and 2:1 near the lower excitation threshold the output interspike interval histogram (ISIH) undergoes a sharp transition. If the driving period is below the critical value, $T_i T^*$ even multiples of $T_i$ also appear in the histogram, starting from the largest values. Near $T^*$ the ISIH scales logarithmically on both sides of the transition. The coefficient of variation of ISIH has a cusp singularity at $T^*$. The average response period has a maximum slightly above $T^*$. Ne...

  7. Neural Energy Supply-Consumption Properties Based on Hodgkin-Huxley Model.

    Science.gov (United States)

    Wang, Yihong; Wang, Rubin; Xu, Xuying

    2017-01-01

    Electrical activity is the foundation of the neural system. Coding theories that describe neural electrical activity by the roles of action potential timing or frequency have been thoroughly studied. However, an alternative method to study coding questions is the energy method, which is more global and economical. In this study, we clearly defined and calculated neural energy supply and consumption based on the Hodgkin-Huxley model, during firing action potentials and subthreshold activities using ion-counting and power-integral model. Furthermore, we analyzed energy properties of each ion channel and found that, under the two circumstances, power synchronization of ion channels and energy utilization ratio have significant differences. This is particularly true of the energy utilization ratio, which can rise to above 100% during subthreshold activity, revealing an overdraft property of energy use. These findings demonstrate the distinct status of the energy properties during neuronal firings and subthreshold activities. Meanwhile, after introducing a synapse energy model, this research can be generalized to energy calculation of a neural network. This is potentially important for understanding the relationship between dynamical network activities and cognitive behaviors.

  8. Theoretical Analysis of Transcranial Magneto-Acoustical Stimulation with Hodgkin-Huxley Neuron Model.

    Science.gov (United States)

    Yuan, Yi; Chen, Yudong; Li, Xiaoli

    2016-01-01

    Transcranial magneto-acoustical stimulation (TMAS) is a novel stimulation technology in which an ultrasonic wave within a magnetostatic field generates an electric current in an area of interest in the brain to modulate neuronal activities. As a key part of the neural network, neurons transmit information in the nervous system. However, the effect of TMAS on the neuronal firing pattern remains unknown. To address this problem, we investigated the stimulatory mechanism of TMAS on neurons, by using a Hodgkin-Huxley neuron model. The simulation results indicated that the magnetostatic field intensity and ultrasonic power affect the amplitude and interspike interval of neuronal action potential under a continuous wave ultrasound. The simulation results also showed that the ultrasonic power, duty cycle and repetition frequency can alter the firing pattern of neural action potential under pulsed wave ultrasound. This study may help to reveal and explain the biological mechanism of TMAS and to provide a theoretical basis for TMAS in the treatment or rehabilitation of neuropsychiatric disorders.

  9. FPGA implementation of a biological neural network based on the Hodgkin-Huxley neuron model.

    Science.gov (United States)

    Yaghini Bonabi, Safa; Asgharian, Hassan; Safari, Saeed; Nili Ahmadabadi, Majid

    2014-01-01

    A set of techniques for efficient implementation of Hodgkin-Huxley-based (H-H) model of a neural network on FPGA (Field Programmable Gate Array) is presented. The central implementation challenge is H-H model complexity that puts limits on the network size and on the execution speed. However, basics of the original model cannot be compromised when effect of synaptic specifications on the network behavior is the subject of study. To solve the problem, we used computational techniques such as CORDIC (Coordinate Rotation Digital Computer) algorithm and step-by-step integration in the implementation of arithmetic circuits. In addition, we employed different techniques such as sharing resources to preserve the details of model as well as increasing the network size in addition to keeping the network execution speed close to real time while having high precision. Implementation of a two mini-columns network with 120/30 excitatory/inhibitory neurons is provided to investigate the characteristic of our method in practice. The implementation techniques provide an opportunity to construct large FPGA-based network models to investigate the effect of different neurophysiological mechanisms, like voltage-gated channels and synaptic activities, on the behavior of a neural network in an appropriate execution time. Additional to inherent properties of FPGA, like parallelism and re-configurability, our approach makes the FPGA-based system a proper candidate for study on neural control of cognitive robots and systems as well.

  10. Strange nonchaotic spiking in the quasiperiodically-forced Hodgkin-Huxley neuron

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Woochang; Kim, Sangyoon [Kangwon National University, Chunchon (Korea, Republic of)

    2010-06-15

    We study the transition from a silent state to a spiking state by varying the dc stimulus in the quasiperiodically-forced Hodgkin-Huxley neuron. For this quasiperiodically-forced case, a new type of strange nonchaotic (SN) spiking state is found to appear between the silent state and the chaotic spiking state as intermediate one. Using a rational approximation to the quasiperiodic forcing, we investigate the mechanism for the appearance of such an SN spiking state. We thus find that a smooth torus (corresponding to the silent state) is transformed into an SN spiking attractor via a phase-dependent saddle-node bifurcation. This is in contrast to the periodically-forced case where the silent state transforms directly to a chaotic spiking state. SN spiking states are characterized in terms of the interspike interval, so they are found to be aperiodic complex ones, as in the case of chaotic spiking states. Hence, aperiodic complex spikings may result from two dynamically different states with strange geometry (one is chaotic and the other one is nonchaotic).

  11. Quantification of degeneracy in Hodgkin-Huxley neurons on Newman-Watts small world network.

    Science.gov (United States)

    Man, Menghua; Zhang, Ya; Ma, Guilei; Friston, Karl; Liu, Shanghe

    2016-08-07

    Degeneracy is a fundamental source of biological robustness, complexity and evolvability in many biological systems. However, degeneracy is often confused with redundancy. Furthermore, the quantification of degeneracy has not been addressed for realistic neuronal networks. The objective of this paper is to characterize degeneracy in neuronal network models via quantitative mathematic measures. Firstly, we establish Hodgkin-Huxley neuronal networks with Newman-Watts small world network architectures. Secondly, in order to calculate the degeneracy, redundancy and complexity in the ensuing networks, we use information entropy to quantify the information a neuronal response carries about the stimulus - and mutual information to measure the contribution of each subset of the neuronal network. Finally, we analyze the interdependency of degeneracy, redundancy and complexity - and how these three measures depend upon network architectures. Our results suggest that degeneracy can be applied to any neuronal network as a formal measure, and degeneracy is distinct from redundancy. Qualitatively degeneracy and complexity are more highly correlated over different network architectures, in comparison to redundancy. Quantitatively, the relationship between both degeneracy and redundancy depends on network coupling strength: both degeneracy and redundancy increase with complexity for small coupling strengths; however, as coupling strength increases, redundancy decreases with complexity (in contrast to degeneracy, which is relatively invariant). These results suggest that the degeneracy is a general topologic characteristic of neuronal networks, which could be applied quantitatively in neuroscience and connectomics.

  12. Bifurcation analysis of delay-induced patterns in a ring of Hodgkin-Huxley neurons.

    Science.gov (United States)

    Kantner, Markus; Yanchuk, Serhiy

    2013-09-28

    Rings of delay-coupled neurons possess a striking capability to produce various stable spiking patterns. In order to reveal the mechanisms of their appearance, we present a bifurcation analysis of the Hodgkin-Huxley (HH) system with delayed feedback as well as a closed loop of HH neurons. We consider mainly the effects of external currents and communication delays. It is shown that typically periodic patterns of different spatial form (wavenumber) appear via Hopf bifurcations as the external current or time delay changes. The Hopf bifurcations are shown to occur in relatively narrow regions of the external current values, which are independent of the delays. Additional patterns, which have the same wavenumbers as the existing ones, appear via saddle-node bifurcations of limit cycles. The obtained bifurcation diagrams are evidence for the important role of communication delays for the emergence of multiple coexistent spiking patterns. The effects of a short-cut, which destroys the rotational symmetry of the ring, are also briefly discussed.

  13. Channel-noise-induced critical slowing in the subthreshold Hodgkin-Huxley neuron

    Science.gov (United States)

    Bukoski, Alex; Steyn-Ross, D. A.; Steyn-Ross, Moira L.

    2015-03-01

    The dynamics of a spiking neuron approaching threshold is investigated in the framework of Markov-chain models describing the random state-transitions of the underlying ion-channel proteins. We characterize subthreshold channel-noise-induced transmembrane potential fluctuations in both type-I (integrator) and type-II (resonator) parametrizations of the classic conductance-based Hodgkin-Huxley equations. As each neuron approaches spiking threshold from below, numerical simulations of stochastic trajectories demonstrate pronounced growth in amplitude simultaneous with decay in frequency of membrane voltage fluctuations induced by ion-channel state transitions. To explore this progression of fluctuation statistics, we approximate the exact Markov treatment with a 12-variable channel-based stochastic differential equation (SDE) and its Ornstein-Uhlenbeck (OU) linearization and show excellent agreement between Markov and SDE numerical simulations. Predictions of the OU theory with respect to membrane potential fluctuation variance, autocorrelation, correlation time, and spectral density are also in agreement and illustrate the close connection between the eigenvalue structure of the associated deterministic bifurcations and the observed behavior of the noisy Markov traces on close approach to threshold for both integrator and resonator point-neuron varieties.

  14. Enhancement of spike coherence by the departure from Gaussian noise in a Hodgkin-Huxley neuron

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Experimental study has shown that non-Gaussian noise exists in sensory systems like neurons.The departure from Gaussian behavior is a characteristic parameter of non-Gaussian noise.In this paper,we have numerically studied the effect of a particular kind of non-Gaussian colored noise(NGN),especially its departure q from Gaussian noise(q = 1),on the spiking activity in a deterministic Hodgkin-Huxley(HH) neuron driven by sub-threshold periodic stimulus.Simulation results show that the departure q can affect the spiking activity induced by noise intensity D.For smaller q values,the minimum in the variation coefficient(CV) as a function of noise intensity(D) becomes smaller,showing that D-induced stochastic resonance(SR) becomes strengthened.Meanwhile,depending on the value of D,q can either enhance or reduce the spiking regularity.Interestingly,CV changes non-monotonously with varying q and passes through a minimum at an intermediate q,representing the presence of "departure-induced SR".This result shows that appropriate departures of the NGN can enhance the spike coherence in the HH neuron.Since the departure of the NGN determines the probability distribution and hence may denote the type of the noise,"departure-induced SR" shows that different types of noise can enhance the spike coherence,and hence may improve the timing precision of sub-threshold signal encoding in the HH neuron.

  15. Effect of autaptic activity on the response of a Hodgkin-Huxley neuron

    Science.gov (United States)

    Wang, Hengtong; Wang, Longfei; Chen, Yueling; Chen, Yong

    2014-09-01

    An autapse is a special synapse that connects a neuron to itself. In this study, we investigated the effect of an autapse on the responses of a Hodgkin-Huxley neuron to different forms of external stimuli. When the neuron was subjected to a DC stimulus, the firing frequencies and the interspike interval distributions of the output spike trains showed periodic behaviors as the autaptic delay time increased. When the input was a synaptic pulse-like train with random interspike intervals, we observed low-pass and band-pass filtering behaviors. Moreover, the region over which the output ISIs are distributed and the mean firing frequency display periodic behaviors with increasing autaptic delay time. When specific autaptic parameters were chosen, most of the input ISIs could be filtered, and the response spike trains were nearly regular, even with a highly random input. The background mechanism of these observed dynamics has been analyzed based on the phase response curve method. We also found that the information entropy of the output spike train could be modified by the autapse. These results also suggest that the autapse can serve as a regulator of information response in the nervous system.

  16. A study of quantum mechanical probabilities in the classical Hodgkin-Huxley model.

    Science.gov (United States)

    Moradi, N; Scholkmann, F; Salari, V

    2015-03-01

    The Hodgkin-Huxley (HH) model is a powerful model to explain different aspects of spike generation in excitable cells. However, the HH model was proposed in 1952 when the real structure of the ion channel was unknown. It is now common knowledge that in many ion-channel proteins the flow of ions through the pore is governed by a gate, comprising a so-called "selectivity filter" inside the ion channel, which can be controlled by electrical interactions. The selectivity filter (SF) is believed to be responsible for the selection and fast conduction of particular ions across the membrane of an excitable cell. Other (generally larger) parts of the molecule such as the pore-domain gate control the access of ions to the channel protein. In fact, two types of gates are considered here for ion channels: the "external gate", which is the voltage sensitive gate, and the "internal gate" which is the selectivity filter gate (SFG). Some quantum effects are expected in the SFG due to its small dimensions, which may play an important role in the operation of an ion channel. Here, we examine parameters in a generalized model of HH to see whether any parameter affects the spike generation. Our results indicate that the previously suggested semi-quantum-classical equation proposed by Bernroider and Summhammer (BS) agrees strongly with the HH equation under different conditions and may even provide a better explanation in some cases. We conclude that the BS model can refine the classical HH model substantially.

  17. Stochastic resonance on Newman-Watts networks of Hodgkin-Huxley neurons with local periodic driving

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, Mahmut [Zonguldak Karaelmas University, Engineering Faculty, Department of Electrical and Electronics Engineering, 67100 Zonguldak (Turkey)], E-mail: mahmutozer2002@yahoo.com; Perc, Matjaz [University of Maribor, Faculty of Natural Sciences and Mathematics, Department of Physics, Koroska cesta 160, SI-2000 Maribor (Slovenia); Uzuntarla, Muhammet [Zonguldak Karaelmas University, Engineering Faculty, Department of Electrical and Electronics Engineering, 67100 Zonguldak (Turkey)

    2009-03-02

    We study the phenomenon of stochastic resonance on Newman-Watts small-world networks consisting of biophysically realistic Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise via voltage-gated ion channels embedded in neuronal membranes. Importantly thereby, the subthreshold periodic driving is introduced to a single neuron of the network, thus acting as a pacemaker trying to impose its rhythm on the whole ensemble. We show that there exists an optimal intensity of intrinsic ion channel noise by which the outreach of the pacemaker extends optimally across the whole network. This stochastic resonance phenomenon can be further amplified via fine-tuning of the small-world network structure, and depends significantly also on the coupling strength among neurons and the driving frequency of the pacemaker. In particular, we demonstrate that the noise-induced transmission of weak localized rhythmic activity peaks when the pacemaker frequency matches the intrinsic frequency of subthreshold oscillations. The implications of our findings for weak signal detection and information propagation across neural networks are discussed.

  18. Pseudo-Lyapunov exponents and predictability of Hodgkin-Huxley neuronal network dynamics.

    Science.gov (United States)

    Sun, Yi; Zhou, Douglas; Rangan, Aaditya V; Cai, David

    2010-04-01

    We present a numerical analysis of the dynamics of all-to-all coupled Hodgkin-Huxley (HH) neuronal networks with Poisson spike inputs. It is important to point out that, since the dynamical vector of the system contains discontinuous variables, we propose a so-called pseudo-Lyapunov exponent adapted from the classical definition using only continuous dynamical variables, and apply it in our numerical investigation. The numerical results of the largest Lyapunov exponent using this new definition are consistent with the dynamical regimes of the network. Three typical dynamical regimes-asynchronous, chaotic and synchronous, are found as the synaptic coupling strength increases from weak to strong. We use the pseudo-Lyapunov exponent and the power spectrum analysis of voltage traces to characterize the types of the network behavior. In the nonchaotic (asynchronous or synchronous) dynamical regimes, i.e., the weak or strong coupling limits, the pseudo-Lyapunov exponent is negative and there is a good numerical convergence of the solution in the trajectory-wise sense by using our numerical methods. Consequently, in these regimes the evolution of neuronal networks is reliable. For the chaotic dynamical regime with an intermediate strong coupling, the pseudo-Lyapunov exponent is positive, and there is no numerical convergence of the solution and only statistical quantifications of the numerical results are reliable. Finally, we present numerical evidence that the value of pseudo-Lyapunov exponent coincides with that of the standard Lyapunov exponent for systems we have been able to examine.

  19. Power-Law Dynamics of Membrane Conductances Increase Spiking Diversity in a Hodgkin-Huxley Model.

    Science.gov (United States)

    Teka, Wondimu; Stockton, David; Santamaria, Fidel

    2016-03-01

    We studied the effects of non-Markovian power-law voltage dependent conductances on the generation of action potentials and spiking patterns in a Hodgkin-Huxley model. To implement slow-adapting power-law dynamics of the gating variables of the potassium, n, and sodium, m and h, conductances we used fractional derivatives of order η≤1. The fractional derivatives were used to solve the kinetic equations of each gate. We systematically classified the properties of each gate as a function of η. We then tested if the full model could generate action potentials with the different power-law behaving gates. Finally, we studied the patterns of action potential that emerged in each case. Our results show the model produces a wide range of action potential shapes and spiking patterns in response to constant current stimulation as a function of η. In comparison with the classical model, the action potential shapes for power-law behaving potassium conductance (n gate) showed a longer peak and shallow hyperpolarization; for power-law activation of the sodium conductance (m gate), the action potentials had a sharp rise time; and for power-law inactivation of the sodium conductance (h gate) the spikes had wider peak that for low values of η replicated pituitary- and cardiac-type action potentials. With all physiological parameters fixed a wide range of spiking patterns emerged as a function of the value of the constant input current and η, such as square wave bursting, mixed mode oscillations, and pseudo-plateau potentials. Our analyses show that the intrinsic memory trace of the fractional derivative provides a negative feedback mechanism between the voltage trace and the activity of the power-law behaving gate variable. As a consequence, power-law behaving conductances result in an increase in the number of spiking patterns a neuron can generate and, we propose, expand the computational capacity of the neuron.

  20. Comparison between Hodgkin-Huxley and Markov formulations of cardiac ion channels.

    Science.gov (United States)

    Carbonell-Pascual, Beatriz; Godoy, Eduardo; Ferrer, Ana; Romero, Lucia; Ferrero, Jose M

    2016-06-21

    When simulating the macroscopic current flowing through cardiac ion channels, two mathematical formalisms can be adopted: the Hodgkin-Huxley model (HHM) formulation, which describes openings and closings of channel 'gates', or the Markov model (MM) formulation, based on channel 'state' transitions. The latter was first used in 1995 to simulate the effects of mutations in ionic currents and, since then, its use has been extended to wild-type channels also. While the MMs better describe the actual behavior of ion channels, they are mathematically more complex than HHMs in terms of parameter estimation and identifiability and are computationally much more demanding, which can dramatically increase computational time in large-scale (e.g. whole heart) simulations. We hypothesize that a HHM formulation obtained from classical patch-clamp protocols in wild-type and mutant ion channels can be used to correctly simulate cardiac action potentials and their static and dynamic properties. To validate our hypothesis, we selected two pivotal cardiac ionic currents (the rapid delayed rectifier K(+) current, IKr, and the inward Na(+) current, INa) and formulated HHMs for both wild-type and mutant channels (LQT2-linked T474I mutation for IKr and LQT3-linked ΔKPQ mutation for INa). Action potentials were then simulated using the MM and HHM versions of the currents, and the action potential waveforms, biomarkers and action potential duration rate dependence properties were compared in control conditions and in the presence of physiological variability. While small differences between ionic currents were found between the two models (correlation coefficient ρ>0.92), the simulations yielded almost identical action potentials (ρ>0.99), suggesting that HHMs may also be valid to simulate the effects of mutations affecting IKr and INa on the action potential.

  1. Power-Law Dynamics of Membrane Conductances Increase Spiking Diversity in a Hodgkin-Huxley Model.

    Directory of Open Access Journals (Sweden)

    Wondimu Teka

    2016-03-01

    Full Text Available We studied the effects of non-Markovian power-law voltage dependent conductances on the generation of action potentials and spiking patterns in a Hodgkin-Huxley model. To implement slow-adapting power-law dynamics of the gating variables of the potassium, n, and sodium, m and h, conductances we used fractional derivatives of order η≤1. The fractional derivatives were used to solve the kinetic equations of each gate. We systematically classified the properties of each gate as a function of η. We then tested if the full model could generate action potentials with the different power-law behaving gates. Finally, we studied the patterns of action potential that emerged in each case. Our results show the model produces a wide range of action potential shapes and spiking patterns in response to constant current stimulation as a function of η. In comparison with the classical model, the action potential shapes for power-law behaving potassium conductance (n gate showed a longer peak and shallow hyperpolarization; for power-law activation of the sodium conductance (m gate, the action potentials had a sharp rise time; and for power-law inactivation of the sodium conductance (h gate the spikes had wider peak that for low values of η replicated pituitary- and cardiac-type action potentials. With all physiological parameters fixed a wide range of spiking patterns emerged as a function of the value of the constant input current and η, such as square wave bursting, mixed mode oscillations, and pseudo-plateau potentials. Our analyses show that the intrinsic memory trace of the fractional derivative provides a negative feedback mechanism between the voltage trace and the activity of the power-law behaving gate variable. As a consequence, power-law behaving conductances result in an increase in the number of spiking patterns a neuron can generate and, we propose, expand the computational capacity of the neuron.

  2. Teaching and learning the Hodgkin-Huxley model based on software developed in NEURON's programming language hoc

    National Research Council Canada - National Science Library

    Hernández, Oscar E; Zurek, Eduardo E

    2013-01-01

    .... The aim of this work is to develop a didactic and easy-to-use computational tool in the NEURON simulation environment, which allows graphical visualization of both the passive and active conduction...

  3. Energy consumption in Hodgkin–Huxley type fast spiking neuron model exposed to an external electric field

    Directory of Open Access Journals (Sweden)

    K. Usha

    2016-09-01

    Full Text Available This paper evaluates the change in metabolic energy required to maintain the signalling activity of neurons in the presence of an external electric field. We have analysed the Hodgkin–Huxley type conductance based fast spiking neuron model as electrical circuit by changing the frequency and amplitude of the applied electric field. The study has shown that, the presence of electric field increases the membrane potential, electrical energy supply and metabolic energy consumption. As the amplitude of applied electric field increases by keeping a constant frequency, the membrane potential increases and consequently the electrical energy supply and metabolic energy consumption increases. On increasing the frequency of the applied field, the peak value of membrane potential after depolarization gradually decreases as a result electrical energy supply decreases which results in a lower rate of hydrolysis of ATP molecules.

  4. Effect of gating currents of ion channels on the collective spiking activity of coupled Hodgkin-Huxley neurons

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the coupled stochastic Hodgkin-Huxley neurons, we numerically studied the effect of gating currents of ion channels, as well as coupling and the number of neurons, on the collective spiking rate and regularity in the coupled system. It was found, for a given coupling strength and with a relatively large number of neurons, when gating currents are applied, the collective spiking regularity decreases; meanwhile, the collective spiking rate increases, indicating that gating currents can aggravate the de-synchronization of the spikings of all neurons. However, gating currents caused hardly any effect in the spiking of any individual neuron of the coupled system. This result, different from the reduction of the spiking rate by gating currents in a single neuron, provides a new insight into the effect of gating cur-rents on the global information processing and signal transduction in real neural systems.

  5. Derivation of Hodgkin-Huxley equations for a Na+ channel from a master equation for coupled activation and inactivation

    CERN Document Server

    Vaccaro, S R

    2016-01-01

    The Na+ current in nerve and muscle membranes may be described in terms of the activation variable m(t) and the inactivation variable h(t), which are dependent on the transitions of S4 sensors in each of the ion channel domains DI to DIV. The time-dependence of the Na+ current and the rate equations satisfied by m(t) and h(t) may be derived from the solution to a master equation which describes the coupling between two activation sensors regulating the Na+ channel conductance and a two stage inactivation process. The voltage dependence of the rate functions for inactivation and recovery from inactivation are consistent with the empirically determined Hodgkin-Huxley expressions, and exhibit saturation for both depolarized and hyperpolarized clamp potentials.

  6. Effects of the spike timing-dependent plasticity on the synchronisation in a random Hodgkin-Huxley neuronal network

    Science.gov (United States)

    Borges, R. R.; Borges, F. S.; Lameu, E. L.; Batista, A. M.; Iarosz, K. C.; Caldas, I. L.; Viana, R. L.; Sanjuán, M. A. F.

    2016-05-01

    In this paper, we study the effects of spike timing-dependent plasticity on synchronisation in a network of Hodgkin-Huxley neurons. Neuron plasticity is a flexible property of a neuron and its network to change temporarily or permanently their biochemical, physiological, and morphological characteristics, in order to adapt to the environment. Regarding the plasticity, we consider Hebbian rules, specifically for spike timing-dependent plasticity (STDP), and with regard to network, we consider that the connections are randomly distributed. We analyse the synchronisation and desynchronisation according to an input level and probability of connections. Moreover, we verify that the transition for synchronisation depends on the neuronal network architecture, and the external perturbation level.

  7. Effect of gating currents of ion channels on the collective spiking activity of coupled Hodξkin-Huxley neurons

    Institute of Scientific and Technical Information of China (English)

    GONG YuBing; XIE YanHang; XU Bo; MA XiaoGuang

    2009-01-01

    Based on the coupled stochastic Hodgkin-Huxley neurons, we numerically studied the effect of gating currents of ion channels, as well as coupling and the number of neurons, on the collective spiking rate and regularity in the coupled system, it was found, for a given coupling strength and with a relatively large number of neurons, when gating currents are applied, the collective spiking regularity decreases; meanwhile, the collective spiking rate increases, indicating that gating currents can aggravate the de-synchronization of the spikings of all neurons. However, gating currents caused hardly any effect in the spiking of any individual neuron of the coupled system. This result, different from the reduction of the spiking rate by gating currents in a single neuron, provides a new insight into the effect of gating cur-rents on the global information processing and signal transduction in real neural systems.

  8. Phase-locking and chaos in a silent Hodgkin-Huxley neuron exposed to sinusoidal electric field

    Energy Technology Data Exchange (ETDEWEB)

    Che Yanqiu [School of Electrical Engineering and Automation, Tianjin University, 300072 (China); Wang Jiang [School of Electrical Engineering and Automation, Tianjin University, 300072 (China)], E-mail: jiangwang@tju.edu.cn; Si Wenjie; Fei Xiangyang [School of Electrical Engineering and Automation, Tianjin University, 300072 (China)

    2009-01-15

    Neuronal firing patterns are related to the information processing in neural system. This paper investigates the response characteristics of a silent Hodgkin-Huxley neuron to the stimulation of externally-applied sinusoidal electric field. The neuron exhibits both p:q phase-locked (i.e. a periodic oscillation defined as p action potentials generated by q cycle stimulations) and chaotic behaviors, depending on the values of stimulus frequencies and amplitudes. In one-parameter space, a rich bifurcation structure including period-adding without chaos and phase-locking alternated with chaos suggests frequency discrimination of the neuronal firing patterns. Furthermore, by mapping out Arnold tongues, we partition the amplitude-frequency parameter space in terms of the qualitative behaviors of the neuron. Thus the neuron's information (firing patterns) encodes the stimulus information (amplitude and frequency), and vice versa.

  9. Effect of Autaptic Activity on Intrinsic Coherence Resonance in Newman-Watts Networks of Stochastic Hodgkin-Huxley Neurons

    Science.gov (United States)

    Wang, Qi; Gong, Yubing

    2016-06-01

    In this paper, we study the effect of autaptic activity on intrinsic coherence resonance (CR) induced by channel noise in Newman-Watts (NW) networks of stochastic Hodgkin-Huxley (HH) neurons. It is found that autaptic strength and autaptic delay have a big effect on the intrinsic CR. As autaptic strength increases, there is optimal autaptic strength by which the intrinsic CR is most highly enhanced. Autaptic delay can enhance, reduce, or destroy the intrinsic CR, depending on the delay length. Moreover, there are optimal coupling strength and network randomness by which autaptic activity can most highly enhance the intrinsic CR. These results show that autaptic activity has different effects on the intrinsic CR in the neuronal networks, and it can most highly enhance the intrinsic CR at optimal coupling strength and network randomness. These findings could find potential implications of channel noise and autaptic activity for the information processing and transmission in neural systems.

  10. Optimization of Intrinsic Stochastic Resonance in Adaptive Newman-Watts Network of Channel Blocked Hodgkin-Huxley Neurons

    Science.gov (United States)

    Wang, Qi; Gong, Yubing; Wu, Yanan

    2014-08-01

    In this paper, we study stochastic resonance (SR) induced by channel noise in adaptive weighted Newman-Watts networks of Hodgkin-Huxley neurons with channel blocking (CB). It is found that the intrinsic SR is dependent on adaptive coupling and is strongly enhanced when the changing rate of adaptive coupling is optimal, and this phenomenon is independent of sodium and potassium CB levels. As CB increases, the channel noise for SR decreases, but the strength of intrinsic SR nearly does not change in the presence of adaptive coupling, which is different from the case for fixed coupling. These results show that intrinsic SR can be enhanced and optimized by adaptive coupling, and CB's effect on the intrinsic SR can be reduced by adaptive coupling. This implies that adaptive coupling could more efficiently improve the time precision of information processing in neural systems.

  11. Two new species of South American freshwater crayfish genus Parastacus Huxley, 1879 (Crustacea: Decapoda: Parastacidae).

    Science.gov (United States)

    Ribeiro, Felipe Bezerra; Buckup, Ludwig; Gomes, Kelly Martinez; Araujo, Paula Beatriz

    2016-08-30

    Two new species of Parastacus Huxley, 1879 are described from material collected in the state of Rio Grande do Sul, southern Brazil: Parastacus fluviatilis sp. nov. from highland streams and Parastacus caeruleodactylus sp. nov. from wetlands. Parastacus fluviatilis sp. nov. is distinguished mainly by large chelipeds with dense setae cover on the cutting edge of fingers, telson subtriangular with two lateral blunt spines and strongly concave ventral surface of lateral process of thoracic sternites 6 and 7. Parastacus caeruleodactylus sp. nov. is distinguished mainly by blue cheliped fingers and a large gap between them, reduced abdomen, dorsal and ventral margins of dactylus, propodus and carpus of second pair of pereiopods with tufts of long setae and mid-dorsal carina of exopod of uropods unarmed. According to IUCN Red List criteria both species are considered endangered. Habitat characterization and a method for defining the shape of second abdominal pleura are also provided.

  12. A new species of Parastacus Huxley, 1879 (Crustacea, Decapoda, Parastacidae from a swamp forest in southern Brazil

    Directory of Open Access Journals (Sweden)

    Felipe Bezerra Ribeiro

    Full Text Available Abstract In this contribution we describe a new species of burrowing crayfish of the genus Parastacus Huxley, 1879 from a swamp forest in southern Brazil and determine its conservation status. The distinction of the new species is based on morphology and the mitochondrial DNA marker 16S rRNA. The extinction risk was assessed according to the sub-criterion B1 of IUCN that estimates the Extent of Occurrence (EOO. Parastacus tuerkayi sp. nov. is morphologically distinguishable from all species of Parastacus by having three lines of verrucous tubercles on the dorsomesial margin of the cheliped propodus and a suborbital angle exceeding 90°. The EOO comprises 647,674 km², and the species is classified as “endangered”. Phylogenetic relationships indicate the distinct position of this new species in relation to the already described species.

  13. 40 CFR 35.2025 - Allowance and advance of allowance.

    Science.gov (United States)

    2010-07-01

    ... facilities planning and design of the project and Step 7 agreements will include an allowance for facility planning in accordance with appendix B of this subpart. (b) Advance of allowance to potential grant... grant applicants for facilities planning and project design. (2) The State may request that the right to...

  14. Derivation of Hodgkin-Huxley equations for a Na+ channel from a master equation for coupled activation and inactivation

    Science.gov (United States)

    Vaccaro, S. R.

    2016-11-01

    The Na+ current in nerve and muscle membranes may be described in terms of the activation variable m (t ) and the inactivation variable h (t ) , which are dependent on the transitions of S4 sensors of each of the Na+ channel domains DI to DIV. The time-dependence of the Na+ current and the rate equations satisfied by m (t ) and h (t ) may be derived from the solution to a master equation that describes the coupling between two or three activation sensors regulating the Na+ channel conductance and a two-stage inactivation process. If the inactivation rate from the closed or open states increases as the S4 sensors activate, a more general form of the Hodgkin-Huxley expression for the open-state probability may be derived where m (t ) is dependent on both activation and inactivation processes. The voltage dependence of the rate functions for inactivation and recovery from inactivation are consistent with the empirically determined expressions and exhibit saturation for both depolarized and hyperpolarized clamp potentials.

  15. Numerical simulations of piecewise deterministic Markov processes with an application to the stochastic Hodgkin-Huxley model

    Science.gov (United States)

    Ding, Shaojie; Qian, Min; Qian, Hong; Zhang, Xuejuan

    2016-12-01

    The stochastic Hodgkin-Huxley model is one of the best-known examples of piecewise deterministic Markov processes (PDMPs), in which the electrical potential across a cell membrane, V(t), is coupled with a mesoscopic Markov jump process representing the stochastic opening and closing of ion channels embedded in the membrane. The rates of the channel kinetics, in turn, are voltage-dependent. Due to this interdependence, an accurate and efficient sampling of the time evolution of the hybrid stochastic systems has been challenging. The current exact simulation methods require solving a voltage-dependent hitting time problem for multiple path-dependent intensity functions with random thresholds. This paper proposes a simulation algorithm that approximates an alternative representation of the exact solution by fitting the log-survival function of the inter-jump dwell time, H(t), with a piecewise linear one. The latter uses interpolation points that are chosen according to the time evolution of the H(t), as the numerical solution to the coupled ordinary differential equations of V(t) and H(t). This computational method can be applied to all PDMPs. Pathwise convergence of the approximated sample trajectories to the exact solution is proven, and error estimates are provided. Comparison with a previous algorithm that is based on piecewise constant approximation is also presented.

  16. Stochastic resonance, coherence resonance, and spike timing reliability of Hodgkin-Huxley neurons with ion-channel noise

    Science.gov (United States)

    Yu, Haitao; Galán, Roberto F.; Wang, Jiang; Cao, Yibin; Liu, Jing

    2017-04-01

    The random transitions of ion channels between open and closed states are a major source of noise in neurons. In this study, we investigate the stochastic dynamics of a single Hodgkin-Huxley (HH) neuron with realistic, physiological channel noise, which depends on the channel number and the voltage potential of the membrane. Without external input, the stochastic HH model can generate spontaneous spikes induced by ion-channel noise, and the variability of inter-spike intervals attains a minimum for an optimal membrane area, a phenomenon known as coherence resonance. When a subthreshold periodic input current is added, the neuron can optimally detect the input frequency for an intermediate membrane area, corresponding to the phenomenon of stochastic resonance. We also investigate spike timing reliability of neuronal responses to repeated presentations of the same stimulus with different realizations of channel noise. We show that, with increasing membrane area, the reliability of neuronal response decreases for subthreshold periodic inputs, and attains a minimum for suprathreshold inputs. Furthermore, Arnold tongues of high reliability arise in a two-dimensional plot of frequency and amplitude of the sinusoidal input current, resulting from the resonance effect of spike timing reliability.

  17. Optimal time scales of input fluctuations for spiking coherence and reliability in stochastic Hodgkin-Huxley neurons

    Science.gov (United States)

    Guo, Xinmeng; Wang, Jiang; Liu, Jing; Yu, Haitao; Galán, Roberto F.; Cao, Yibin; Deng, Bin

    2017-02-01

    Channel noise, which is generated by the random transitions of ion channels between open and closed states, is distinguished from external sources of physiological variability such as spontaneous synaptic release and stimulus fluctuations. This inherent stochasticity in ion-channel current can lead to variability of the timing of spikes occurring both spontaneously and in response to stimuli. In this paper, we investigate how intrinsic channel noise affects the response of stochastic Hodgkin-Huxley (HH) neuron to external fluctuating inputs with different amplitudes and correlation time. It is found that there is an optimal correlation time of input fluctuations for the maximal spiking coherence, where the input current has a fluctuating rate approximately matching the inherent oscillation of stochastic HH model and plays a dominating role in the timing of spike firing. We also show that the reliability of spike timing in the model is very sensitive to the properties of the current input. An optimal time scale of input fluctuations exists to induce the most reliable firing. The channel-noise-induced unreliability can be mostly overridden by injecting a fluctuating current with an appropriate correlation time. The spiking coherence and reliability can also be regulated by the size of channel stochasticity. As the membrane area (or total channel number) of the neuron increases, the spiking coherence decreases but the spiking reliability increases.

  18. Effects of channel noise on synchronization transitions in delayed scale-free network of stochastic Hodgkin-Huxley neurons

    Institute of Scientific and Technical Information of China (English)

    王宝英; 龚玉兵

    2015-01-01

    We numerically study the effect of the channel noise on the spiking synchronization of a scale-free Hodgkin–Huxley neuron network with time delays. It is found that the time delay can induce synchronization transitions at an intermediate and proper channel noise intensity, and the synchronization transitions become strongest when the channel noise intensity is optimal. The neurons can also exhibit synchronization transitions as the channel noise intensity is varied, and this phenomenon is enhanced at around the time delays that can induce the synchronization transitions. It is also found that the synchronization transitions induced by the channel noise are dependent on the coupling strength and the network average degree, and there is an optimal coupling strength or network average degree with which the synchronization transitions become strongest. These results show that by inducing synchronization transitions, the channel noise has a big regulation effect on the synchronization of the neuronal network. These findings could find potential implications for the information transmission in neural systems.

  19. 一类Hodgkin-Huxley模型的分支研究%Bifurcation Analysis of a Hodgkin-Huxley-Type Model

    Institute of Scientific and Technical Information of China (English)

    李敏; 刘宣亮; 刘深泉

    2013-01-01

    This paper consider the Hodgkin-Huxley model in muscels, by using the bifurcation theory of differential equations and mumerical simulation, we discuss the one-parameter and two-parameter bifurcations of the model. The Bogdanov-Takens bifurcation are also discussed. We obtain the saddle-node bifurcation curve, the Hopf bifurcation curve and the Homoclinic bifurcation curve near the Bogdanov-Takens point.%考虑一类描述肌细胞膜电位变化的Hodgkin-Huxley模型的分支问题.利用常微分方程的分支理论,结合数值模拟结果,对模型的单参数分支与双参数分支进行了讨论.分析了Bogdanov-Takens分支,得到了相应的鞍结点分支曲线, Hopf分支曲线与同宿分支曲线.

  20. Effects of channel noise on synchronization transitions in delayed scale-free network of stochastic Hodgkin-Huxley neurons

    Science.gov (United States)

    Wang, Bao-Ying; Gong, Yu-Bing

    2015-11-01

    We numerically study the effect of the channel noise on the spiking synchronization of a scale-free Hodgkin-Huxley neuron network with time delays. It is found that the time delay can induce synchronization transitions at an intermediate and proper channel noise intensity, and the synchronization transitions become strongest when the channel noise intensity is optimal. The neurons can also exhibit synchronization transitions as the channel noise intensity is varied, and this phenomenon is enhanced at around the time delays that can induce the synchronization transitions. It is also found that the synchronization transitions induced by the channel noise are dependent on the coupling strength and the network average degree, and there is an optimal coupling strength or network average degree with which the synchronization transitions become strongest. These results show that by inducing synchronization transitions, the channel noise has a big regulation effect on the synchronization of the neuronal network. These findings could find potential implications for the information transmission in neural systems. Project supported by the Natural Science Foundation of Shandong Province of China (Grant No. ZR2012AM013).

  1. Optimal size of stochastic Hodgkin-Huxley neuronal systems for maximal energy efficiency in coding pulse signals

    Science.gov (United States)

    Yu, Lianchun; Liu, Liwei

    2014-03-01

    The generation and conduction of action potentials (APs) represents a fundamental means of communication in the nervous system and is a metabolically expensive process. In this paper, we investigate the energy efficiency of neural systems in transferring pulse signals with APs. By analytically solving a bistable neuron model that mimics the AP generation with a particle crossing the barrier of a double well, we find the optimal number of ion channels that maximizes the energy efficiency of a neuron. We also investigate the energy efficiency of a neuron population in which the input pulse signals are represented with synchronized spikes and read out with a downstream coincidence detector neuron. We find an optimal number of neurons in neuron population, as well as the number of ion channels in each neuron that maximizes the energy efficiency. The energy efficiency also depends on the characters of the input signals, e.g., the pulse strength and the interpulse intervals. These results are confirmed by computer simulation of the stochastic Hodgkin-Huxley model with a detailed description of the ion channel random gating. We argue that the tradeoff between signal transmission reliability and energy cost may influence the size of the neural systems when energy use is constrained.

  2. Derivation of Hodgkin-Huxley equations for a Na^{+} channel from a master equation for coupled activation and inactivation.

    Science.gov (United States)

    Vaccaro, S R

    2016-11-01

    The Na^{+} current in nerve and muscle membranes may be described in terms of the activation variable m(t) and the inactivation variable h(t), which are dependent on the transitions of S4 sensors of each of the Na^{+} channel domains DI to DIV. The time-dependence of the Na^{+} current and the rate equations satisfied by m(t) and h(t) may be derived from the solution to a master equation that describes the coupling between two or three activation sensors regulating the Na^{+} channel conductance and a two-stage inactivation process. If the inactivation rate from the closed or open states increases as the S4 sensors activate, a more general form of the Hodgkin-Huxley expression for the open-state probability may be derived where m(t) is dependent on both activation and inactivation processes. The voltage dependence of the rate functions for inactivation and recovery from inactivation are consistent with the empirically determined expressions and exhibit saturation for both depolarized and hyperpolarized clamp potentials.

  3. Numerical simulations of piecewise deterministic Markov processes with an application to the stochastic Hodgkin-Huxley model.

    Science.gov (United States)

    Ding, Shaojie; Qian, Min; Qian, Hong; Zhang, Xuejuan

    2016-12-28

    The stochastic Hodgkin-Huxley model is one of the best-known examples of piecewise deterministic Markov processes (PDMPs), in which the electrical potential across a cell membrane, V(t), is coupled with a mesoscopic Markov jump process representing the stochastic opening and closing of ion channels embedded in the membrane. The rates of the channel kinetics, in turn, are voltage-dependent. Due to this interdependence, an accurate and efficient sampling of the time evolution of the hybrid stochastic systems has been challenging. The current exact simulation methods require solving a voltage-dependent hitting time problem for multiple path-dependent intensity functions with random thresholds. This paper proposes a simulation algorithm that approximates an alternative representation of the exact solution by fitting the log-survival function of the inter-jump dwell time, H(t), with a piecewise linear one. The latter uses interpolation points that are chosen according to the time evolution of the H(t), as the numerical solution to the coupled ordinary differential equations of V(t) and H(t). This computational method can be applied to all PDMPs. Pathwise convergence of the approximated sample trajectories to the exact solution is proven, and error estimates are provided. Comparison with a previous algorithm that is based on piecewise constant approximation is also presented.

  4. Collective temporal coherence for subthreshold signal encoding on a stochastic small-world Hodgkin-Huxley neuronal network

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, Mahmut [Zonguldak Karaelmas University, Engineering Faculty, Department of Electrical and Electronics Engineering, 67100 Zonguldak (Turkey); Laboratory of Neurophysics and Physiology, UMR 8119 CNRS, Universite Paris Descartes, 45 rue des Saint-Peres, 75006 Paris (France)], E-mail: mahmutozer2002@yahoo.com; Uzuntarla, Muhammet [Zonguldak Karaelmas University, Engineering Faculty, Department of Electrical and Electronics Engineering, 67100 Zonguldak (Turkey); Kayikcioglu, Temel [Karadeniz Technical University, Department of Electrical and Electronics Engineering, Trabzon (Turkey); Graham, Lyle J. [Laboratory of Neurophysics and Physiology, UMR 8119 CNRS, Universite Paris Descartes, 45 rue des Saint-Peres, 75006 Paris (France)

    2008-10-20

    We study the collective temporal coherence of a small-world network of coupled stochastic Hodgkin-Huxley neurons. Previous reports have shown that network coherence in response to a subthreshold periodic stimulus, thus subthreshold signal encoding, is maximal for a specific range of the fraction of randomly added shortcuts relative to all possible shortcuts, p, added to an initially locally connected network. We investigated this behavior further as a function of channel noise, stimulus frequency and coupling strength. We show that temporal coherence peaks when the frequency of the external stimulus matches that of the intrinsic subthreshold oscillations. We also find that large values of the channel noise, corresponding to small cell sizes, increases coherence for optimal values of the stimulus frequency and the topology parameter p. For smaller values of the channel noise, thus larger cell sizes, network coherence becomes insensitive to these parameters. Finally, the degree of coupling between neurons in the network modulates the sensitivity of coherence to topology, such that for stronger coupling the peak coherence is achieved with fewer added short cuts.

  5. 38 CFR 21.4145 - Work-study allowance.

    Science.gov (United States)

    2010-07-01

    ... place where his or her services are to be performed; (3) Motivation of the veteran, reservist, or... the Fair Labor Standards Act of 1938 (29 U.S.C. 206(a)) times the number of hours the veteran...

  6. Mean-field description and propagation of chaos in networks of Hodgkin-Huxley and FitzHugh-Nagumo neurons.

    Science.gov (United States)

    Baladron, Javier; Fasoli, Diego; Faugeras, Olivier; Touboul, Jonathan

    2012-05-31

    We derive the mean-field equations arising as the limit of a network of interacting spiking neurons, as the number of neurons goes to infinity. The neurons belong to a fixed number of populations and are represented either by the Hodgkin-Huxley model or by one of its simplified version, the FitzHugh-Nagumo model. The synapses between neurons are either electrical or chemical. The network is assumed to be fully connected. The maximum conductances vary randomly. Under the condition that all neurons' initial conditions are drawn independently from the same law that depends only on the population they belong to, we prove that a propagation of chaos phenomenon takes place, namely that in the mean-field limit, any finite number of neurons become independent and, within each population, have the same probability distribution. This probability distribution is a solution of a set of implicit equations, either nonlinear stochastic differential equations resembling the McKean-Vlasov equations or non-local partial differential equations resembling the McKean-Vlasov-Fokker-Planck equations. We prove the well-posedness of the McKean-Vlasov equations, i.e. the existence and uniqueness of a solution. We also show the results of some numerical experiments that indicate that the mean-field equations are a good representation of the mean activity of a finite size network, even for modest sizes. These experiments also indicate that the McKean-Vlasov-Fokker-Planck equations may be a good way to understand the mean-field dynamics through, e.g. a bifurcation analysis.Mathematics Subject Classification (2000): 60F99, 60B10, 92B20, 82C32, 82C80, 35Q80.

  7. Voltage dependence of Hodgkin-Huxley rate functions for a multistage K^{+} channel voltage sensor within a membrane.

    Science.gov (United States)

    Vaccaro, S R

    2014-11-01

    The activation of a K^{+} channel sensor in two sequential stages during a voltage clamp may be described as the translocation of a Brownian particle in an energy landscape with two large barriers between states. A solution of the Smoluchowski equation for a square-well approximation to the potential function of the S4 voltage sensor satisfies a master equation and has two frequencies that may be determined from the forward and backward rate functions. When the higher-frequency terms have small amplitude, the solution reduces to the relaxation of a rate equation, where the derived two-state rate functions are dependent on the relative magnitude of the forward rates (α and γ) and the backward rates (β and δ) for each stage. In particular, the voltage dependence of the Hodgkin-Huxley rate functions for a K^{+} channel may be derived by assuming that the rate functions of the first stage are large relative to those of the second stage-α≫γ and β≫δ. For a Shaker IR K^{+} channel, the first forward and backward transitions are rate limiting (αchannel and a noninactivating Na^{+} ion channel is determined by the master equation for K^{+} channel activation and the ionic current equation when the Na^{+} channel activation time is small, and if β≪δ and α≪γ, the system may exhibit a small amplitude oscillation between spikes, or mixed-mode oscillation, in which the slow closed state modulates the K^{+} ion channel conductance in the membrane.

  8. Voltage dependence of Hodgkin-Huxley rate functions for a multistage K+ channel voltage sensor within a membrane

    Science.gov (United States)

    Vaccaro, S. R.

    2014-11-01

    The activation of a K+channel sensor in two sequential stages during a voltage clamp may be described as the translocation of a Brownian particle in an energy landscape with two large barriers between states. A solution of the Smoluchowski equation for a square-well approximation to the potential function of the S4 voltage sensor satisfies a master equation and has two frequencies that may be determined from the forward and backward rate functions. When the higher-frequency terms have small amplitude, the solution reduces to the relaxation of a rate equation, where the derived two-state rate functions are dependent on the relative magnitude of the forward rates (α and γ ) and the backward rates (β and δ ) for each stage. In particular, the voltage dependence of the Hodgkin-Huxley rate functions for a K+channel may be derived by assuming that the rate functions of the first stage are large relative to those of the second stage—α ≫γ and β ≫δ . For a Shaker IR K+ channel, the first forward and backward transitions are rate limiting (α <γ and δ ≪β ), and for an activation process with either two or three stages, the derived two-state rate functions also have a voltage dependence that is of a similar form to that determined for the squid axon. The potential variation generated by the interaction between a two-stage K+ ion channel and a noninactivating Na+ ion channel is determined by the master equation for K+channel activation and the ionic current equation when the Na+channel activation time is small, and if β ≪δ and α ≪γ , the system may exhibit a small amplitude oscillation between spikes, or mixed-mode oscillation, in which the slow closed state modulates the K+ ion channel conductance in the membrane.

  9. A library of analog operators based on the hodgkin-huxley formalism for the design of tunable, real-time, silicon neurons.

    Science.gov (United States)

    Saïghi, S; Bornat, Y; Tomas, J; Le Masson, G; Renaud, S

    2011-02-01

    In this paper, we present a library of analog operators used for the analog real-time computation of the Hodgkin-Huxley formalism. These operators make it possible to design a silicon (Si) neuron that is dynamically tunable, and that reproduces different kinds of neurons. We used an original method in neuromorphic engineering to characterize this Si neuron. In electrophysiology, this method is well known as the "voltage-clamp" technique. We also compare the features of an application-specific integrated circuit built with this library with results obtained from software simulations. We then present the complex behavior of neural membrane voltages and the potential applications of this Si neuron.

  10. Solitary wave and periodic wave solutions for Burgers, Fisher, Huxley and combined forms of these equations by the (′/)-expansion method

    Indian Academy of Sciences (India)

    Jalil Manafian; Mehrdad Lakestani

    2015-07-01

    An application of the (′/)-expansion method to search for exact solutions of nonlinear partial differential equations is analysed. This method is used for Burgers, Fisher, Huxley equations and combined forms of these equations. The (′/)-expansion method was used to construct periodic wave and solitary wave solutions of nonlinear evolution equations. This method is developed for searching exact travelling wave solutions of nonlinear partial differential equations. It is shown that the (′/)-expansion method, with the help of symbolic computation, provides a straightforward and powerful mathematical tool for solving nonlinear partial differential equations.

  11. A Phase-Locking Analysis of Neuronal Firing Rhythms with Transcranial Magneto-Acoustical Stimulation Based on the Hodgkin-Huxley Neuron Model.

    Science.gov (United States)

    Yuan, Yi; Pang, Na; Chen, Yudong; Wang, Yi; Li, Xiaoli

    2017-01-01

    Transcranial magneto-acoustical stimulation (TMAS) uses ultrasonic waves and a static magnetic field to generate electric current in nerve tissues for the purpose of modulating neuronal activities. It has the advantage of high spatial resolution and penetration depth. Neuronal firing rhythms carry and transmit nerve information in neural systems. In this study, we investigated the phase-locking characteristics of neuronal firing rhythms with TMAS based on the Hodgkin-Huxley neuron model. The simulation results indicate that the modulation frequency of ultrasound can affect the phase-locking behaviors. The results of this study may help us to explain the potential firing mechanism of TMAS.

  12. Entre a civilização e a selvajaria : os estereótipos do nativo americano e o selvagem de Brave New World de Aldous Huxley

    OpenAIRE

    Rebelo, Maria Raquel de Gouveia Durão Pina

    1999-01-01

    A presente dissertação apresenta, num primeiro momento, um estudo dos estereótipos do Ameríndio - nomeadamente o Bom-Selvagem e o canibal feroz e amoral -, formados pela mente branca europeia e americana numa atitude de contraponto entre culturas. Este estudo, baseado em textos representativos de várias épocas, serve de base à deconstrucção satírica que aldous Huxley faz desses estereótipos e à subversão das categorias discursivas oposicionais nas quais eles assentam e que levaram à distinção...

  13. Canards existence in FitzHugh-Nagumo and Hodgkin-Huxley neuronal models

    OpenAIRE

    Ginoux, Jean-Marc

    2015-01-01

    In a previous paper we have proposed a new method for proving the existence of "canard solutions" for three and four-dimensional singularly perturbed systems with only one fast variable. The aim of this work is to extend this method to the case of four-dimensional singularly perturbed systems with two slow and two fast variables. This method enables to state a unique generic condition for the existence of "canard solutions" for such four-dimensional singularly perturbed systems which is based...

  14. Canards Existence in FitzHugh-Nagumo and Hodgkin-Huxley Neuronal Models

    OpenAIRE

    Jean-Marc Ginoux; Jaume Llibre

    2015-01-01

    In a previous paper we have proposed a new method for proving the existence of “canard solutions” for three- and four-dimensional singularly perturbed systems with only one fast variable which improves the methods used until now. The aim of this work is to extend this method to the case of four-dimensional singularly perturbed systems with two slow and two fast variables. This method enables stating a unique generic condition for the existence of “canard solutions” for such four-dimensional s...

  15. 广义Burgers—Huxley方程解的数值模拟%The numerical simulation of the solutions for the generalized Burgers-Huxley equation

    Institute of Scientific and Technical Information of China (English)

    刘玉华; 张金良; 李留涛

    2012-01-01

    广义Burgers—Huxley方程是一个非常重要的模型,在流体力学、化学反应、生物工程、自动控制等领域有着广泛的应用.借助于有限差分、对角隐式Runge—Kutta-NystrSm(DIRKN),对广义Burgers·Huxley方程的精确解进行了数值模拟,由模拟的图形及误差可以看出本文的方法是有效的,但是若方程的非线性较强时,数值结果的误差相对较大.%The generalized Burgers-Huxley equation is an important model, it has wide applications in fluid mechanics, chemical reaction, bioengineering, automatic control, etc. In this paper, the exact solutions of the generalized Burgers-Huxley equation are numerically simulated using the finite difference method and diagonal implicit Runge-Kutta-Nystrom method. From the simulation figures and errors, the method used in this paper is efficient, if the nonlinearity is strong, the error becomes bigger.

  16. Vietnam recommended dietary allowances 2007.

    Science.gov (United States)

    Khan, Nguyen Cong; Hoan, Pham Van

    2008-01-01

    It has been well acknowledged that Vietnam is undergoing a nutrition transition. With a rapid change in the country's reform and economic growth, food supply at the macronutrient level has improved. Changes of the Vietnamese diet include significantly more foods of animal origin, and an increase of fat/oils, and ripe fruits. Consequently, nutritional problems in Vietnam now include not only malnutrition but also overweight/obesity, metabolic syndrome and other chronic diseases related to nutrition and lifestyles. The recognition of these shifts, which is also associated with morbidity and mortality, was a major factor in the need to review and update the Recommended Dietary Allowances (RDA) for the Vietnamese population. This revised RDA established an important science-based tool for evaluation of nutrition adequacy, for teaching, and for scientific communications within Vietnam. It is expected that the 2007 Vietnam RDA and its conversion to food-based dietary guidelines will facilitate education to the public, as well as the policy implementation of programs for prevention of non-communicable chronic diseases and addressing the double burden of both under and over nutrition.

  17. Stochastic sensitivity analysis of noise-induced suppression of firing and giant variability of spiking in a Hodgkin-Huxley neuron model

    Science.gov (United States)

    Bashkirtseva, Irina; Neiman, Alexander B.; Ryashko, Lev

    2015-05-01

    We study the stochastic dynamics of a Hodgkin-Huxley neuron model in a regime of coexistent stable equilibrium and a limit cycle. In this regime, noise may suppress periodic firing by switching the neuron randomly to a quiescent state. We show that at a critical value of the injected current, the mean firing rate depends weakly on noise intensity, while the neuron exhibits giant variability of the interspike intervals and spike count. To reveal the dynamical origin of this noise-induced effect, we develop the stochastic sensitivity analysis and use the Mahalanobis metric for this four-dimensional stochastic dynamical system. We show that the critical point of giant variability corresponds to the matching of the Mahalanobis distances from attractors (stable equilibrium and limit cycle) to a three-dimensional surface separating their basins of attraction.

  18. Stochastic sensitivity analysis of noise-induced suppression of firing and giant variability of spiking in a Hodgkin-Huxley neuron model.

    Science.gov (United States)

    Bashkirtseva, Irina; Neiman, Alexander B; Ryashko, Lev

    2015-05-01

    We study the stochastic dynamics of a Hodgkin-Huxley neuron model in a regime of coexistent stable equilibrium and a limit cycle. In this regime, noise may suppress periodic firing by switching the neuron randomly to a quiescent state. We show that at a critical value of the injected current, the mean firing rate depends weakly on noise intensity, while the neuron exhibits giant variability of the interspike intervals and spike count. To reveal the dynamical origin of this noise-induced effect, we develop the stochastic sensitivity analysis and use the Mahalanobis metric for this four-dimensional stochastic dynamical system. We show that the critical point of giant variability corresponds to the matching of the Mahalanobis distances from attractors (stable equilibrium and limit cycle) to a three-dimensional surface separating their basins of attraction.

  19. 40 CFR 35.940-5 - Disputes concerning allowable costs.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Disputes concerning allowable costs. 35... FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE Grants for Construction of Treatment Works-Clean Water Act § 35.940-5 Disputes concerning allowable costs. The grantee should seek to resolve any questions...

  20. 46 CFR 154.421 - Allowable stress.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.421 Section 154.421 Shipping COAST... § 154.421 Allowable stress. The allowable stress for the integral tank structure must meet the American Bureau of Shipping's allowable stress for the vessel's hull published in “Rules for Building and Classing...

  1. 46 CFR 154.440 - Allowable stress.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.440 Section 154.440 Shipping COAST... Tank Type A § 154.440 Allowable stress. (a) The allowable stresses for an independent tank type A must... Commandant (CG-522). (b) A greater allowable stress than required in paragraph (a)(1) of this section may be...

  2. Clean Air Markets - Allowances Query Wizard

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Allowances Query Wizard is part of a suite of Clean Air Markets-related tools that are accessible at http://camddataandmaps.epa.gov/gdm/index.cfm. The Allowances...

  3. Allowance Holdings and Transfers Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Allowance Holdings and Transfers Data Inventory contains measured data on holdings and transactions of allowances under the NOx Budget Trading Program (NBP), a...

  4. 46 CFR 154.428 - Allowable stress.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable stresses...

  5. 46 CFR 154.447 - Allowable stress.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for stress...

  6. Effect of Spike-Timing-Dependent Plasticity on Intrinsic Coherence Resonance in Newman-Watts Stochastic Hodgkin-Huxley Neuronal Networks

    Science.gov (United States)

    Xie, Huijuan; Gong, Yubing; Wang, Qi

    2016-07-01

    In this paper, we numerically study the effect of spike-timing-dependent plasticity (STDP) on coherence resonance (CR) induced by channel noise in adaptive Newman-Watts stochastic Hodgkin-Huxley neuron networks. It is found that STDP can either enhance or suppress the intrinsic CR when the adjusting rate of STDP decreases or increases. STDP can alter the effects of network randomness and network size on the intrinsic CR. Under STDP, for electrical coupling there are optimal network randomness and network size by which the intrinsic CR becomes strongest, however, for chemical coupling the intrinsic CR is always enhanced as network randomness or network size increases, which are different from the results for fixed coupling. These results show that the intrinsic CR of the neuronal networks can be either enhanced or suppressed by STDP, and there are optimal network randomness and network size by which the intrinsic CR becomes strongest. These findings could provide a new insight into the role of STDP for the information processing and transmission in neural systems.

  7. 基于HH模型的心肌细胞电模型%Electric Model of the Myocardial Cell Based on Hodgkin-Huxley Model

    Institute of Scientific and Technical Information of China (English)

    张莹; 李智

    2012-01-01

    A modeling and simulation methods of electrophysiological model of myocardial cells were proposed. Based on the Hodg- kin-Huxley model, equivalent circuit model of the rat's single cardiac muscle cell was built. Using fourth-order Rouge-Kutta algorithm, internal and external cardiac membrane ionic current and potential difference changes has been researched and analyzed. Making use of C Language, the program of the cardiac cell membrane was realized like equivalent circuit model, and the computer's simulation through Mat-lab software platform was realized. As a result, it obtained the result of simulation experience of electrophysiological model of cardiac muscle cell under every different kinds of stimulation.%提出了一种心肌细胞电生理模型的建模仿真方法.通过借助Hodgkin-Huxley模型对单个心肌细胞建立细胞膜的等效电路模型,利用四阶Rouge-Kutta算法,研究并分析了心肌细胞膜内外离子电流及电位差变化.然后用C语言完成了对细胞膜等效电路模型的编程,利用Matlab软件平台进行了计算机仿真,得到了心肌细胞电生理学模型在不同刺激下的仿真实验结果.

  8. Iterative learning control of synchronization of Hodgkin-Huxley neurons%Hodgkin-Huxley神经元同步的迭代学习控制

    Institute of Scientific and Technical Information of China (English)

    邓斌; 王晓军; 王江; 李会艳

    2014-01-01

    由于神经元模型和参数具有不确定性,加大了许多控制算法的应用难度,而迭代学习控制不需要精确的数学模型,因此适合神经元网络同步的控制.针对Hodgkin-Huxley(HH)神经元的同步控制问题,提出了基于PI型迭代学习控制算法.对四种不同情况下主从神经元同步控制进行仿真,结果表明,施加控制后从神经元能够迅速跟踪主神经元的动力学行为.研究结果证实了该控制算法的可行性和有效性.

  9. Enhancement of temporal coherence via time-periodic coupling strength in a scale-free network of stochastic Hodgkin-Huxley neurons

    Science.gov (United States)

    Yilmaz, Ergin; Baysal, Veli; Ozer, Mahmut

    2015-08-01

    We investigate the effects of time-periodic coupling strength on the temporal coherence or firing regularity of a scale-free network consisting of stochastic Hodgkin-Huxley (H-H) neurons. The temporal coherence exhibits a resonance-like behavior depending on the cell size or the channel noise intensity. The best temporal coherence requires an optimal channel noise intensity, and this coherence can be significantly increased by time-periodic coupling strength when its frequency matches the integer multiples of the intrinsic subthreshold oscillation frequency of H-H neuron. Particularly, we find the multiple-coherence resonance depending on frequency of time-periodic coupling strength at the optimal noise intensity. We also obtain a resonance-like dependence of temporal coherence on the amplitude of time-periodic coupling strength. Additionally, we investigate the effects of average degree on the temporal coherence and find that the temporal coherence exhibits a resonance-like behavior with respect to the network average degree, indicating that the best regularity requires an optimal average degree.

  10. Traveling-wave solutions of a modified Hodgkin-Huxley type neural model via Novel analytical results for nonlinear transmission lines with arbitrary I(V characteristics

    Directory of Open Access Journals (Sweden)

    Valentino Anthony Simpao

    2000-01-01

    Full Text Available Herein an enhanced Hodgkin-Huxley (H-H type model of neuron dynamics is solved analytically via formal methods. Our model is a variant of an earlier one by M.A. Mahrous and H.Y. Alkahby [1]. Their modified model is realized by a hyperbolic quasi-linear diffusion operator with time-delay parameters; this compared to the original H-H model with standard parabolic quasi-linear diffusion operator and no time-delay parameters. Besides these features, the present model also incorporates terms describing signal dissipation into the background substrate (e.g., conductance to ground, making it more experimentally amenable. The solutions which results via the present scheme are of traveling-wave profile, which agree qualitatively with those observed in actual electro-physiological measurements made on the neural systems originally studied by H-H These results confirm the physiological soundness of the enhanced model and of the preliminary assumptions which motivated the present solution strategy; the comparison of the present results with actual electro-physiological data displays shall appear in later publications.

  11. 45 CFR 74.27 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Allowable costs. 74.27 Section 74.27 Public..., AND COMMERCIAL ORGANIZATIONS Post-Award Requirements Financial and Program Management § 74.27 Allowable costs. (a) For each kind of recipient, there is a particular set of Federal principles...

  12. 28 CFR 100.11 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Allowable costs. 100.11 Section 100.11 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) COST RECOVERY REGULATIONS, COMMUNICATIONS ASSISTANCE FOR LAW ENFORCEMENT ACT OF 1994 § 100.11 Allowable costs. (a) Costs that are eligible...

  13. 20 CFR 633.303 - Allowable costs.

    Science.gov (United States)

    2010-04-01

    ... occupation trained for and at not less than the wage specified in the agreement. (g) Travel costs. (1) The... to the overall administrative cost ceiling. (i) Allowances and reimbursements for board and advisory... grantee per quarter. (2) Allowances and loss of wages. Any individual or family member who is a member of...

  14. 75 FR 4098 - Utility Allowance Adjustments

    Science.gov (United States)

    2010-01-26

    ... URBAN DEVELOPMENT Utility Allowance Adjustments AGENCY: Office of the Chief Information Officer, HUD... are required to advise the Secretary of the need for and request of a new utility allowance for... whether the information will have practical utility; (2) Evaluate the accuracy of the agency's estimate...

  15. 44 CFR 13.22 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... uniform cost accounting standards that comply with cost principles acceptable to the Federal agency. ... STATE AND LOCAL GOVERNMENTS Post-Award Requirements Financial Administration § 13.22 Allowable costs. (a... increment above allowable costs) to the grantee or subgrantee. (b) Applicable cost principles. For each...

  16. 32 CFR 33.22 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... accounting standards that comply with cost principles acceptable to the Federal agency. ... Post-Award Requirements Financial Administration § 33.22 Allowable costs. (a) Limitation on use of... allowable costs) to the grantee or subgrantee. (b) Applicable cost principles. For each kind of...

  17. 36 CFR 1207.22 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... uniform cost accounting standards that comply with cost principles acceptable to the Federal agency. ... GOVERNMENTS Post-Award Requirements Financial Administration § 1207.22 Allowable costs. (a) Limitation on use... increment above allowable costs) to the grantee or subgrantee. (b) Applicable cost principles. For each...

  18. 34 CFR 74.27 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... Procedures or uniform cost accounting standards that comply with cost principles acceptable to ED. (b) The... OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Financial... principles for determining allowable costs. Allowability of costs are determined in accordance with the...

  19. 5 CFR 180.104 - Allowable claims.

    Science.gov (United States)

    2010-01-01

    ... mobile homes may be allowed only in cases of collision, theft, or vandalism. (5) Money. Claims for money... claimant's supervisor. (4) Mobile homes. Claims may be allowed for damage to or loss of mobile homes and their contents under the provisions of § 180.104(c)(2). Claims for structural damage to mobile...

  20. 38 CFR 49.27 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Financial and Program Management § 49.27 Allowable...-Profit Organizations.” The allowability of costs incurred by institutions of higher education...

  1. 20 CFR 435.27 - Allowable costs.

    Science.gov (United States)

    2010-04-01

    ... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT ORGANIZATIONS, AND COMMERCIAL ORGANIZATIONS Post-Award Requirements Financial and Program Management § 435.27 Allowable costs. For each kind... Organizations.” (c) Allowability of costs incurred by institutions of higher education is determined...

  2. 28 CFR 70.27 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... AND AGREEMENTS (INCLUDING SUBAWARDS) WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Financial and Program Management § 70.27 Allowable costs. (a... Organizations.” The allowability of costs incurred by institutions of higher education is determined...

  3. 15 CFR 14.27 - Allowable costs.

    Science.gov (United States)

    2010-01-01

    ... GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT, AND COMMERCIAL ORGANIZATIONS Post-Award Requirements Financial and Program Management § 14.27 Allowable costs. For each kind of... Organizations.” The allowability of costs incurred by institutions of higher education is determined...

  4. 24 CFR 17.43 - Allowable claims.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Allowable claims. 17.43 Section 17.43 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development..., superior authority. (6) Clothing and accessories. Claims may be allowed for damage to, or loss of, clothing...

  5. 29 CFR 1470.22 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... to that circular 48 CFR part 31. Contract Cost Principles and Procedures, or uniform cost accounting... grantee or subgrantee. (b) Applicable cost principles. For each kind of organization, there is a set of Federal principles for determining allowable costs. Allowable costs will be determined in accordance...

  6. 45 CFR 2541.220 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... accounting standards that comply with cost principles acceptable to the Federal agency. ... the grantee or subgrantee. (b) Applicable cost principles. For each kind of organization, there is a set of Federal principles for determining allowable costs. Allowable costs will be determined...

  7. Keynes, family allowances and Keynesian economic policy

    OpenAIRE

    Pressman, Steven

    2014-01-01

    This paper provides a short history of family allowances and documents the fact that Keynes supported family allowances as early as the 1920s, continuing through the 1930s and early 1940s. Keynes saw this policy as a way to help households raise their children and also as a way to increase consumption without reducing business investment. The paper goes on to argue that a policy of family allowances is consistent with Keynesian economics. Finally, the paper uses the Luxembourg Income Study to...

  8. A self-organizing state-space-model approach for parameter estimation in hodgkin-huxley-type models of single neurons.

    Science.gov (United States)

    Vavoulis, Dimitrios V; Straub, Volko A; Aston, John A D; Feng, Jianfeng

    2012-01-01

    Traditional approaches to the problem of parameter estimation in biophysical models of neurons and neural networks usually adopt a global search algorithm (for example, an evolutionary algorithm), often in combination with a local search method (such as gradient descent) in order to minimize the value of a cost function, which measures the discrepancy between various features of the available experimental data and model output. In this study, we approach the problem of parameter estimation in conductance-based models of single neurons from a different perspective. By adopting a hidden-dynamical-systems formalism, we expressed parameter estimation as an inference problem in these systems, which can then be tackled using a range of well-established statistical inference methods. The particular method we used was Kitagawa's self-organizing state-space model, which was applied on a number of Hodgkin-Huxley-type models using simulated or actual electrophysiological data. We showed that the algorithm can be used to estimate a large number of parameters, including maximal conductances, reversal potentials, kinetics of ionic currents, measurement and intrinsic noise, based on low-dimensional experimental data and sufficiently informative priors in the form of pre-defined constraints imposed on model parameters. The algorithm remained operational even when very noisy experimental data were used. Importantly, by combining the self-organizing state-space model with an adaptive sampling algorithm akin to the Covariance Matrix Adaptation Evolution Strategy, we achieved a significant reduction in the variance of parameter estimates. The algorithm did not require the explicit formulation of a cost function and it was straightforward to apply on compartmental models and multiple data sets. Overall, the proposed methodology is particularly suitable for resolving high-dimensional inference problems based on noisy electrophysiological data and, therefore, a potentially useful tool in

  9. 赫胥黎与达尔文主义及生态伦理学的创新%Huxley and His Innovation of Darwinism and Ecological Ethics

    Institute of Scientific and Technical Information of China (English)

    何毓德; 郎补俄

    2012-01-01

    赫胥黎对生物进化论作出划时代创新。他汲取古希腊赫拉克利特的直观辩证法,使康德宇宙整体发展观推陈出新。从人类发生学和人猿比较解剖学新视角,重新确定了人在生物界中的位置,使达尔文的人猿同祖论,从"假说"深化为科学的结论。他看到人类社会和生物进化的差别,纠正了社会达尔文主义的错误。他把猿与具有"至善伦理"的人和生物进化相统一,赋予人类保护生态系统义不容辞的社会责任。他由此成为生态伦理学说的开拓者。%Huxley made epoch-making innovations of biological evolution. He absorbed the visual dia- lectics of Heraclitus of ancient Greece and developed new ideas out of Kant's whole development view of the universe. He redefined the position of man in the biological world from the new perspective of the origin of human species and the comparative anatomy of human species and apes, and therefore turned Darwin's theory of human and ape evolving from the same origin from hypothesis to scientific conclusion. He perceived the evolution differences between human society and biological creatures, and corrected the mistakes of social Darwinism. He integrated apes, man who has ethics and biological evolution, granting human beings the social responsibility of protecting ecological systems. Thus he became a pioneer of ecological ethics.

  10. Impact of Bounded Noise and Rewiring on the Formation and Instability of Spiral Waves in a Small-World Network of Hodgkin-Huxley Neurons.

    Science.gov (United States)

    Yao, Yuangen; Deng, Haiyou; Ma, Chengzhang; Yi, Ming; Ma, Jun

    2017-01-01

    Spiral waves are observed in the chemical, physical and biological systems, and the emergence of spiral waves in cardiac tissue is linked to some diseases such as heart ventricular fibrillation and epilepsy; thus it has importance in theoretical studies and potential medical applications. Noise is inevitable in neuronal systems and can change the electrical activities of neuron in different ways. Many previous theoretical studies about the impacts of noise on spiral waves focus an unbounded Gaussian noise and even colored noise. In this paper, the impacts of bounded noise and rewiring of network on the formation and instability of spiral waves are discussed in small-world (SW) network of Hodgkin-Huxley (HH) neurons through numerical simulations, and possible statistical analysis will be carried out. Firstly, we present SW network of HH neurons subjected to bounded noise. Then, it is numerically demonstrated that bounded noise with proper intensity σ, amplitude A, or frequency f can facilitate the formation of spiral waves when rewiring probability p is below certain thresholds. In other words, bounded noise-induced resonant behavior can occur in the SW network of neurons. In addition, rewiring probability p always impairs spiral waves, while spiral waves are confirmed to be robust for small p, thus shortcut-induced phase transition of spiral wave with the increase of p is induced. Furthermore, statistical factors of synchronization are calculated to discern the phase transition of spatial pattern, and it is confirmed that larger factor of synchronization is approached with increasing of rewiring probability p, and the stability of spiral wave is destroyed.

  11. Impact of Bounded Noise and Rewiring on the Formation and Instability of Spiral Waves in a Small-World Network of Hodgkin-Huxley Neurons

    Science.gov (United States)

    Yao, Yuangen; Deng, Haiyou; Ma, Chengzhang; Yi, Ming

    2017-01-01

    Spiral waves are observed in the chemical, physical and biological systems, and the emergence of spiral waves in cardiac tissue is linked to some diseases such as heart ventricular fibrillation and epilepsy; thus it has importance in theoretical studies and potential medical applications. Noise is inevitable in neuronal systems and can change the electrical activities of neuron in different ways. Many previous theoretical studies about the impacts of noise on spiral waves focus an unbounded Gaussian noise and even colored noise. In this paper, the impacts of bounded noise and rewiring of network on the formation and instability of spiral waves are discussed in small-world (SW) network of Hodgkin-Huxley (HH) neurons through numerical simulations, and possible statistical analysis will be carried out. Firstly, we present SW network of HH neurons subjected to bounded noise. Then, it is numerically demonstrated that bounded noise with proper intensity σ, amplitude A, or frequency f can facilitate the formation of spiral waves when rewiring probability p is below certain thresholds. In other words, bounded noise-induced resonant behavior can occur in the SW network of neurons. In addition, rewiring probability p always impairs spiral waves, while spiral waves are confirmed to be robust for small p, thus shortcut-induced phase transition of spiral wave with the increase of p is induced. Furthermore, statistical factors of synchronization are calculated to discern the phase transition of spatial pattern, and it is confirmed that larger factor of synchronization is approached with increasing of rewiring probability p, and the stability of spiral wave is destroyed. PMID:28129401

  12. The Space-Clamped Hodgkin-Huxley System with Random Synaptic Input: Inhibition of Spiking by Weak Noise and Analysis with Moment Equations.

    Science.gov (United States)

    Tuckwell, Henry C; Ditlevsen, Susanne

    2016-10-01

    We consider a classical space-clamped Hodgkin-Huxley model neuron stimulated by synaptic excitation and inhibition with conductances represented by Ornstein-Uhlenbeck processes. Using numerical solutions of the stochastic model system obtained by an Euler method, it is found that with excitation only, there is a critical value of the steady-state excitatory conductance for repetitive spiking without noise, and for values of the conductance near the critical value, small noise has a powerfully inhibitory effect. For a given level of inhibition, there is also a critical value of the steady-state excitatory conductance for repetitive firing, and it is demonstrated that noise in either the excitatory or inhibitory processes or both can powerfully inhibit spiking. Furthermore, near the critical value, inverse stochastic resonance was observed when noise was present only in the inhibitory input process. The system of deterministic differential equations for the approximate first- and second-order moments of the model is derived. They are solved using Runge-Kutta methods, and the solutions are compared with the results obtained by simulation for various sets of parameters, including some with conductances obtained by experiment on pyramidal cells of rat prefrontal cortex. The mean and variance obtained from simulation are in good agreement when there is spiking induced by strong stimulation and relatively small noise or when the voltage is fluctuating at subthreshold levels. In the occasional spike mode sometimes exhibited by spinal motoneurons and cortical pyramidal cells, the assumptions underlying the moment equation approach are not satisfied. The simulation results show that noisy synaptic input of either an excitatory or inhibitory character or both may lead to the suppression of firing in neurons operating near a critical point and this has possible implications for cortical networks. Although suppression of firing is corroborated for the system of moment equations

  13. Sign Patterns That Allow the Given Matrix

    Institute of Scientific and Technical Information of China (English)

    邵燕灵; 孙良

    2003-01-01

    Let P be a property referring to a real matrix. For a sign pattern A, if there exists a real matrix B in the qualitative class of A such that B has property P, then we say A allows P. Three cases that A allows an M-matrix, an inverse M-matrix and a P0-matrix are considered. The complete characterizations are obtained.

  14. Regulatory treatment of allowances and compliance costs

    Energy Technology Data Exchange (ETDEWEB)

    Rose, K. [National Regulatory Research Institute, Columbus, OH (United States)

    1993-07-01

    The Clean Air Act Amendments of 1990 (CAAA) established a national emission allowance trading system, a market-based form of environmental regulation designed to reduce and limit sulfur dioxide emissions. However, the allowance trading system is being applied primarily to an economically regulated electric utility industry. The combining of the new form of environmental regulation and economic regulation of electric utilities has raised a number of questions including what the role should be of the federal and state utility regulating commissions and how those actions will affect the decision making process of the utilities and the allowance market. There are several dimensions to the regulatory problems that commissions face. Allowances and utility compliance expenditures have implications for least-cost/IPR (integrated resource planning), prudence review procedures, holding company and multistate utility regulation and ratemaking treatment. The focus of this paper is on the ratemaking treatment. The following topics are covered: ratemaking treatment of allowances and compliance costs; Traditional cost-recovery mechanisms; limitations to the traditional approach; traditional approach and the allowance trading market; market-based cost recovery mechanisms; methods of determining the benchmark; determining the split between ratepayers and the utility; other regulatory approaches; limitations of incentive mechanisms.

  15. Paid work and unpaid work

    DEFF Research Database (Denmark)

    Bonke, Jens

    Time-use information is preferably obtained from diaries, as this method is considered more reliable than information from questionnaires. The diary-technique seems to be unique in catching the rhythm of every day life and thereby the structuring of work and leisure during a well......-questions are asked about the time spent on paid work and unpaid/household work. The advantage of the latter technique is that it can easily be integrated into surveys. Thus the American National Survey of Families and Households (NSFH) already contains two waves, and a new wave for 2001-2002, which allows...

  16. Quantum theory allows for absolute maximal contextuality

    Science.gov (United States)

    Amaral, Barbara; Cunha, Marcelo Terra; Cabello, Adán

    2015-12-01

    Contextuality is a fundamental feature of quantum theory and a necessary resource for quantum computation and communication. It is therefore important to investigate how large contextuality can be in quantum theory. Linear contextuality witnesses can be expressed as a sum S of n probabilities, and the independence number α and the Tsirelson-like number ϑ of the corresponding exclusivity graph are, respectively, the maximum of S for noncontextual theories and for the theory under consideration. A theory allows for absolute maximal contextuality if it has scenarios in which ϑ /α approaches n . Here we show that quantum theory allows for absolute maximal contextuality despite what is suggested by the examination of the quantum violations of Bell and noncontextuality inequalities considered in the past. Our proof is not constructive and does not single out explicit scenarios. Nevertheless, we identify scenarios in which quantum theory allows for almost-absolute-maximal contextuality.

  17. 45 CFR 34.4 - Allowable claims.

    Science.gov (United States)

    2010-10-01

    ... government-owned or operated parking lot or garage incident to employment. This subsection does not include... amount allowed is the value of the vehicle at the time of loss as determined by the National Automobile.... Damage or loss of personal property, including baggage and household items, while being transported by...

  18. 45 CFR 2543.27 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... Welfare Regulations Relating to Public Welfare (Continued) CORPORATION FOR NATIONAL AND COMMUNITY SERVICE GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT... Organizations.” The allowability of costs incurred by institutions of higher education is determined in...

  19. 34 CFR 80.22 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... CFR part 31. Contract Cost Principles and Procedures, or uniform cost accounting standards that comply... COOPERATIVE AGREEMENTS TO STATE AND LOCAL GOVERNMENTS Post-Award Requirements Financial Administration § 80.22... kind of organization, there is a set of Federal principles for determining allowable costs. For...

  20. 13 CFR 143.22 - Allowable costs.

    Science.gov (United States)

    2010-01-01

    ... to that circular 48 CFR part 31. Contract Cost Principles and Procedures, or uniform cost accounting... Financial Administration § 143.22 Allowable costs. (a) Limitation on use of funds. Grant funds may be used... grantee or subgrantee. (b) Applicable cost principles. For each kind of organization, there is a set...

  1. 38 CFR 43.22 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... accounting standards that comply with cost principles acceptable to the Federal agency. ... Requirements Financial Administration § 43.22 Allowable costs. (a) Limitation on use of funds. Grant funds may... the grantee or subgrantee. (b) Applicable cost principles. For each kind of organization, there is...

  2. 22 CFR 135.22 - Allowable costs.

    Science.gov (United States)

    2010-04-01

    ... Procedures, or uniform cost accounting standards that comply with cost principles acceptable to the Federal... AGREEMENTS TO STATE AND LOCAL GOVERNMENTS Post-Award Requirements Financial Administration § 135.22 Allowable... principles. For each kind of organization, there is a set of Federal principles for determining...

  3. 40 CFR 31.22 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... accounting standards that comply with cost principles acceptable to the Federal agency. ... Requirements Financial Administration § 31.22 Allowable costs. (a) Limitation on use of funds. Grant funds may... the grantee or sub-grantee. (b) Applicable cost principles. For each kind of organization, there is...

  4. 45 CFR 92.22 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... to that circular 48 CFR Part 31. Contract Cost Principles and Procedures, or uniform cost accounting... Financial Administration § 92.22 Allowable costs. (a) Limitation on use of funds. Grant funds may be used... grantee or subgrantee. (b) Applicable cost principles. For each kind of organization, there is a set...

  5. 7 CFR 550.25 - Allowable costs.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture (Continued) AGRICULTURAL RESEARCH SERVICE, DEPARTMENT OF... Financial Management § 550.25 Allowable costs. For each kind of Cooperator, there is a set of Federal... Acquisition Regulation (FAR) at 48 CFR part 31. Program Management ...

  6. 22 CFR 145.27 - Allowable costs.

    Science.gov (United States)

    2010-04-01

    ... Relations DEPARTMENT OF STATE CIVIL RIGHTS GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Financial and Program Management § 145...-Profit Organizations.” The allowability of costs incurred by institutions of higher education...

  7. 22 CFR 518.27 - Allowable costs.

    Science.gov (United States)

    2010-04-01

    ... INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Financial and Program Management § 518.27 Allowable costs. For each kind of recipient, there is a set of... by institutions of higher education is determined in accordance with the provisions of OMB Circular...

  8. 36 CFR 1210.27 - Allowable costs.

    Science.gov (United States)

    2010-07-01

    ... RULES UNIFORM ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Financial and Program Management § 1210.27 Allowable costs. For each kind of recipient, there is a set of Federal principles...

  9. Making It Personal: Per Capita Carbon Allowances

    DEFF Research Database (Denmark)

    Fawcett, Tina; Hvelplund, Frede; Meyer, Niels I

    2009-01-01

    The Chapter highligts the importance of introducing new, efficient schemes for mitigation of global warming. One such scheme is Personal Carbon Allowances (PCA), whereby individuals are allotted a tradable ration of CO2 emission per year.This chapter reviews the fundamentals of PCA and analyzes its...

  10. Judicial Deference Allows European Consensus to Emerge

    DEFF Research Database (Denmark)

    Dothan, Shai

    2017-01-01

    conceived as competing doctrines: the more there is of one, the less there is of another. This paper suggests a novel rationale for the emerging consensus doctrine: the doctrine can allow the ECHR to make good policies by drawing on the independent decision-making of many similar countries. In light of that...

  11. 77 FR 34218 - Clothing Allowance; Correction

    Science.gov (United States)

    2012-06-11

    ... construed to impose a restriction that VA did not intend. This document corrects that error. DATES: This... Service, Veterans Benefits Administration, Department of Veterans Affairs, 810 Vermont Avenue NW... medication would be eligible for a clothing allowance for each such appliance or medication if each...

  12. 49 CFR 266.11 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... Management Circular 74-4; and costs of projects eligible under § 266.7 of this part. All allowable costs shall be authorized by a fully executed grant agreement. A State may incur costs prior to the execution... need to incur costs prior to the execution of a grant agreement, has authorized the costs in writing...

  13. 33 CFR 136.211 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.211 Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.211...

  14. 33 CFR 136.205 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.205 Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.205...

  15. 33 CFR 136.241 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.241 Section 136.241 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.241...

  16. 33 CFR 136.223 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.223 Section 136.223 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.223...

  17. 33 CFR 136.217 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.217 Section 136.217 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.217...

  18. 33 CFR 136.235 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.235 Section 136.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.235...

  19. 33 CFR 136.229 - Compensation allowable.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.229 Section 136.229 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.229...

  20. 50 CFR 80.15 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ...) FINANCIAL ASSISTANCE-WILDLIFE SPORT FISH RESTORATION PROGRAM ADMINISTRATIVE REQUIREMENTS, PITTMAN-ROBERTSON WILDLIFE RESTORATION AND DINGELL-JOHNSON SPORT FISH RESTORATION ACTS § 80.15 Allowable costs. (a) What are... designed to include purposes other than those eligible under either the Dingell-Johnson Sport Fish...

  1. 43 CFR 12.62 - Allowable costs.

    Science.gov (United States)

    2010-10-01

    ... Public Lands: Interior Office of the Secretary of the Interior ADMINISTRATIVE AND AUDIT REQUIREMENTS AND COST PRINCIPLES FOR ASSISTANCE PROGRAMS Uniform Administrative Requirements for Grants and Cooperative... increment above allowable costs) to the grantee or subgrantee. (b) Applicable cost principles. For each...

  2. Realization of allowable qeneralized quantum gates

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The most general duality gates were introduced by Long,Liu and Wang and named allowable generalized quantum gates (AGQGs,for short).By definition,an allowable generalized quantum gate has the form of U=YfkjsckUK,where Uk’s are unitary operators on a Hilbert space H and the coefficients ck’s are complex numbers with |Yfijo ck\\ ∧ 1 an d 1ck| <1 for all k=0,1,...,d-1.In this paper,we prove that an AGQG U=YfkZo ck∧k is realizable,i.e.there are two d by d unitary matrices W and V such that ck=W0kVk0 (0

  3. Making It Personal: Per Capita Carbon Allowances

    DEFF Research Database (Denmark)

    Fawcett, Tina; Hvelplund, Frede; Meyer, Niels I

    2009-01-01

    The Chapter highligts the importance of introducing new, efficient schemes for mitigation of global warming. One such scheme is Personal Carbon Allowances (PCA), whereby individuals are allotted a tradable ration of CO2 emission per year.This chapter reviews the fundamentals of PCA and analyzes its...... merits and problems. The United Kingdom and Denmark have been chosen as case studies because the energy situation and the institutional setup are quite different between the two countries....

  4. What parents say about the allowance: Function of the allowance for parents of different economic incomes

    Directory of Open Access Journals (Sweden)

    Irani Lauer Lellis

    2012-06-01

    Full Text Available The practice of giving allowance is used by several parents in different parts of the world and can contribute to the economic education of children. This study aimed to investigate the purposes of the allowance with 32 parents of varying incomes. We used the focus group technique and Alceste software to analyze the data. The results involved two classes related to the process of using the allowance. These classes have covered aspects of the role of socialization and education allowance, serving as an instrument of reward, but sometimes encouraging bad habits in children. The justification of the fathers concerning the amount of money to be given to the children and when to stop giving allowance were also highlighted.   Keywords: allowance; economic socialization; parenting practices.

  5. 76 FR 16629 - Federal Travel Regulation (FTR); Relocation Allowances-Relocation Income Tax Allowance (RITA) Tables

    Science.gov (United States)

    2011-03-24

    ... http://www.gsa.gov/relocationpolicy . Dated: March 21, 2011. Janet Dobbs, Director, Office of Travel... ADMINISTRATION Federal Travel Regulation (FTR); Relocation Allowances-- Relocation Income Tax Allowance (RITA... effective March 24, 2011. FOR FURTHER INFORMATION CONTACT: Mr. Ed Davis, Office of Governmentwide Policy...

  6. 76 FR 32340 - Federal Travel Regulation; Temporary Duty (TDY) Travel Allowances (Taxes); Relocation Allowances...

    Science.gov (United States)

    2011-06-06

    ... Duty (TDY) Travel Allowances (Taxes); Relocation Allowances (Taxes) AGENCY: Office of Governmentwide... extended temporary duty (TDY) benefits to correct errors and to align that process with the proposed... incurred by employees as a result of relocation and to reimburse ``all'' of the taxes imposed on any...

  7. Assessing allowable take of migratory birds

    Science.gov (United States)

    Runge, M.C.; Sauer, J.R.; Avery, M.L.; Blackwell, B.F.; Koneff, M.D.

    2009-01-01

    Legal removal of migratory birds from the wild occurs for several reasons, including subsistence, sport harvest, damage control, and the pet trade. We argue that harvest theory provides the basis for assessing the impact of authorized take, advance a simplified rendering of harvest theory known as potential biological removal as a useful starting point for assessing take, and demonstrate this approach with a case study of depredation control of black vultures (Coragyps atratus) in Virginia, USA. Based on data from the North American Breeding Bird Survey and other sources, we estimated that the black vulture population in Virginia was 91,190 (95% credible interval = 44,520?212,100) in 2006. Using a simple population model and available estimates of life-history parameters, we estimated the intrinsic rate of growth (rmax) to be in the range 7?14%, with 10.6% a plausible point estimate. For a take program to seek an equilibrium population size on the conservative side of the yield curve, the rate of take needs to be less than that which achieves a maximum sustained yield (0.5 x rmax). Based on the point estimate for rmax and using the lower 60% credible interval for population size to account for uncertainty, these conditions would be met if the take of black vultures in Virginia in 2006 was <3,533 birds. Based on regular monitoring data, allowable harvest should be adjusted annually to reflect changes in population size. To initiate discussion about how this assessment framework could be related to the laws and regulations that govern authorization of such take, we suggest that the Migratory Bird Treaty Act requires only that take of native migratory birds be sustainable in the long-term, that is, sustained harvest rate should be

  8. The Synchronization and Associative Memory of Hodgkin-Huxley Neural Network with Randomly Distributed Time Delays%随机延时Hodgkin-Huxley神经网络的同步与联想记忆

    Institute of Scientific and Technical Information of China (English)

    李冰; 彭建华; 刘延柱

    2005-01-01

    基于神经系统微观生理结构,给出具有空间分布随机延时的神经元间耦合,而这种随机延时描述峰电位从突触前神经元到突触后神经元在轴突上传播所需要的时间.记忆由时空发放的神经元集群表达.通过加入并改变噪声的强度,研究了噪声对Hodgkin-Huxley(HH)神经元网络系统联想记忆的作用,在噪声涨落的作用下,系统取得了对不完整输入的记忆恢复,得到与熟知的随机共振完全一致的结果.

  9. 外电场下Hodgkin-Huxley模型的分岔分析%Analysis of hopf bifurcation in the hodgkin-Huxley model exposed to external DC electric field

    Institute of Scientific and Technical Information of China (English)

    于凯; 赵辉; 王红君; 岳有军

    2009-01-01

    本文以Hodgkin-Huxley(HH)为基础,分析外电场对神经细胞的作用机制,建立了极低电场下改进的HH模型.我们通过高维系统Hopf分岔存在性的代数判据,计算了(外部刺激电流)和(外部直流电场引起的跨膜电压)的单参数空间的Hopf分岔集,并给出了系统产生稳定周期解的参数区域,这将有助于从理论上揭示和解释电场致病的生物机理,为预防和治疗此类疾病提供理论依据.

  10. Does "grief work" work?

    NARCIS (Netherlands)

    Stroebe, M; Stroebe, W

    1991-01-01

    This article challenges the long-standing belief in the necessity of "grief work" for adjustment to bereavement. Evidence is offered from a prospective study of 30 widows and 30 widowers that indicates that grief work is not always as essential for adjustment to bereavement as theorists and clinicia

  11. Radiative data for allowed transitions in Ni XXV

    Energy Technology Data Exchange (ETDEWEB)

    Tully, John A [Departement Cassiopee, Observatoire de la Cote d' Azur, BP 4229, 06304 Nice Cedex 4 (France); Chidichimo, Marita C [Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2004-02-14

    Using Hibbert's configuration interaction program CIV3, which allows for relativistic effects by means of the Breit-Pauli approximation, we have computed radiative data for the 272 optically allowed transitions between levels i = 2l{sub 1} 2l{sub 2} S'L'J' and j = 2l{sub 3} n{sub 4}l{sub 4} SLJ with n{sub 4} = 2, 3, 4 in Be-like Ni XXV. Oscillator strengths f, transition probabilities A, line wavelengths {lambda} and energies E{sub ij} in cm{sup -1} are tabulated. We make detailed comparisons with related work done by other authors during the period 1977 to 2000.

  12. Allowing for heterogeneity in monetary subjective well-being valuations.

    Science.gov (United States)

    Mentzakis, Emmanouil

    2011-03-01

    Recent research on 'happiness' regression equations has shown how monetary values can be put on the well-being effects of many life events (like health problems, marriage or the death of a spouse). Potentially, such work has practical implications for policy-makers and the courts. However, this article argues that we need to be careful in such work to use the appropriate statistical method. It goes beyond previous research and allows for heterogeneity in the subjective well-being scales. Using less restrictive models than the current literature, the article argues that standard linear or ordered response models seem consistently to overstate valuations. With data from the UK, it provides new monetary estimates of the well-being consequences of a number of health problems, social capital indicators, marital status changes and social relationships.

  13. Funding child rearing: child allowance and parental leave.

    Science.gov (United States)

    Walker, J R

    1996-01-01

    This article proposes two financing plans to address what the author identifies as the two primary concerns in the child care field: (1) a child allowance for poor and near-poor households to address the child care problems of low-income families, and (2) a program of voluntary parental leave, available to all parents at child birth or adoption, to ensure the adequacy of infant care. The child allowance plan would cover the first three children in families up to 175% of the poverty level (more than 22 million children) at an annual cost of $45 billion. The author suggests that the allowance could be financed by redirecting funds from existing income support (for example, Aid to Families with Dependent Children), tax credit, and tax deduction programs. Financing the parental leave program would require new revenues, generated by an employee-paid increase in payroll tax totaling 3.5%. Each employee's contributions would create a parental leave account (PLA). Families could use the funds in these accounts to cover the cost of a one-year leave from work after the birth or adoption of a child. If families did not have enough dollars in their accounts to cover the cost of the leave, the federal government would extend a low-interest loan to them, which they would have to pay back. The amount individuals receive through Social Security would be adjusted upward or downward according to the balances in their parental leave accounts at retirement. The author suggests that both proposals would help parents balance work and family obligations and protect parental freedom of choice over the care and upbringing of their children.

  14. 40 CFR 73.21 - Phase II repowering allowances.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Phase II repowering allowances. 73.21... (CONTINUED) SULFUR DIOXIDE ALLOWANCE SYSTEM Allowance Allocations § 73.21 Phase II repowering allowances. (a) Repowering allowances. In addition to allowances allocated under § 73.10(b), the Administrator will...

  15. Progress Report on Alloy 617 Time Dependent Allowables

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Julie Knibloe [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-06-01

    Time dependent allowable stresses are required in the ASME Boiler and Pressure Vessel Code for design of components in the temperature range where time dependent deformation (i.e., creep) is expected to become significant. There are time dependent allowable stresses in Section IID of the Code for use in the non-nuclear construction codes, however, there are additional criteria that must be considered in developing time dependent allowables for nuclear components. These criteria are specified in Section III NH. St is defined as the lesser of three quantities: 100% of the average stress required to obtain a total (elastic, plastic, primary and secondary creep) strain of 1%; 67% of the minimum stress to cause rupture; and 80% of the minimum stress to cause the initiation of tertiary creep. The values are reported for a range of temperatures and for time increments up to 100,000 hours. These values are determined from uniaxial creep tests, which involve the elevated temperature application of a constant load which is relatively small, resulting in deformation over a long time period prior to rupture. The stress which is the minimum resulting from these criteria is the time dependent allowable stress St. In this report data from a large number of creep and creep-rupture tests on Alloy 617 are analyzed using the ASME Section III NH criteria. Data which are used in the analysis are from the ongoing DOE sponsored high temperature materials program, form Korea Atomic Energy Institute through the Generation IV VHTR Materials Program and historical data from previous HTR research and vendor data generated in developing the alloy. It is found that the tertiary creep criterion determines St at highest temperatures, while the stress to cause 1% total strain controls at low temperatures. The ASME Section III Working Group on Allowable Stress Criteria has recommended that the uncertainties associated with determining the onset of tertiary creep and the lack of significant

  16. 45 CFR 2522.245 - How are living allowances disbursed?

    Science.gov (United States)

    2010-10-01

    ..., Requirements, and Benefits § 2522.245 How are living allowances disbursed? A living allowance is not a wage and programs may not pay living allowances on an hourly basis. Programs must distribute the living allowance at... 45 Public Welfare 4 2010-10-01 2010-10-01 false How are living allowances disbursed? 2522.245...

  17. 49 CFR 230.24 - Maximum allowable stress.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

  18. Refugees’ rights to work

    Directory of Open Access Journals (Sweden)

    Emily E Arnold-Fernández

    2013-09-01

    Full Text Available Host economies benefit when refugees work. Nations seeking economic growth and political stability should allow refugees to access employment and to enjoy employment-related rights.

  19. 7 CFR 3560.202 - Establishing rents and utility allowances.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Establishing rents and utility allowances. 3560.202... Establishing rents and utility allowances. (a) General. Rents and utility allowances for rental units in Agency... Agency. (b) Agency approval. All rents and utility allowances set by borrowers are subject to...

  20. Neural population with lateral inhibition of cortical columns based on the Hodgkin-Huxley model%基于Hodgkin-Huxley模型的皮层柱侧抑制神经元群

    Institute of Scientific and Technical Information of China (English)

    杜红伟; 王从庆

    2007-01-01

    HH(Hodgkin-Huxley)神经细胞模型一般被用于研究单个神经细胞的行为和特性,很少被用于构造人工神经系统.考虑神经细胞具有抑制性联结和兴奋性联结,将HH模型进行发展,提出了基于HH模型的神经元群,模拟大脑皮层柱的生理结构及侧抑制特性.分别将皮层柱内及皮层柱间的侧抑制机制应用于神经元群编码、解码,进行位置跟踪;改变解码策略,实现"胜者为王"功能.仿真实验表明了该神经元群模型的有效性,侧抑制特性的应用大大提高了位置跟踪精度、"胜者为王"效果.

  1. 27 CFR 20.24 - Allowance of claims.

    Science.gov (United States)

    2010-04-01

    ... OF THE TREASURY LIQUORS DISTRIBUTION AND USE OF DENATURED ALCOHOL AND RUM Administrative Provisions Authorities § 20.24 Allowance of claims. The appropriate TTB officer is authorized to allow claims for...

  2. 27 CFR 22.23 - Allowance of claims.

    Science.gov (United States)

    2010-04-01

    ... OF THE TREASURY LIQUORS DISTRIBUTION AND USE OF TAX-FREE ALCOHOL Administrative Provisions Authorities § 22.23 Allowance of claims. The appropriate TTB officer is authorized to allow claims for...

  3. Mobility Work

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind; Bossen, Claus

    2005-01-01

    We posit the concept of Mobility Work to describe efforts of moving about people and things as part of accomplishing tasks. Mobility work can be seen as a spatial parallel to the concept of articulation work proposed by the sociologist Anselm Strauss. Articulation work describes efforts...... of coordination necessary in cooperative work, but focuses, we argue, mainly on the temporal aspects of cooperative work. As a supplement, the concept of mobility work focuses on the spatial aspects of cooperative work. Whereas actors seek to diminish the amount of articulation work needed in collaboration...... by constructing Standard Operation Procedures (SOPs), actors minimise mobility work by constructing Standard Operation Configurations (SOCs). We apply the concept of mobility work to the ethnography of hospital work, and argue that mobility arises because of the need to get access to people, places, knowledge and...

  4. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3) Slurp gun;...

  5. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3)...

  6. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3) Slurp gun;...

  7. 14 CFR 151.125 - Allowable advance planning costs.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Allowable advance planning costs. 151.125... (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Rules and Procedures for Advance Planning and Engineering Proposals § 151.125 Allowable advance planning costs. (a) The United States' share of the allowable costs of...

  8. 24 CFR 891.785 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... Handicapped Families and Individuals-Section 162 Assistance § 891.785 Adjustment of utility allowances. In... adjustment of utility allowances provided in § 891.440 apply....

  9. 24 CFR 891.440 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... Project Management § 891.440 Adjustment of utility allowances. This section shall apply to projects funded... submit an analysis of any utility allowances applicable. Such data as changes in utility rates and...

  10. 24 CFR 886.326 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... utility allowances. When the owner requests HUD approval of an adjustment in Contract Rents under § 886.312, an analysis of the project's Utility Allowances must be included. Such data as changes in...

  11. 24 CFR 880.610 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... Management § 880.610 Adjustment of utility allowances. In connection with annual and special adjustments of contract rents, the owner must submit an analysis of the project's Utility Allowances. Such data as...

  12. 24 CFR 886.126 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... utility allowances. When the owner requests HUD approval of adjustment in Contract Rents under § 886.112, an analysis of the project's Utility Allowances must be included. Such data as changes in...

  13. 24 CFR 884.220 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... Adjustment of utility allowances. In connection with annual and special adjustments of contract rents, the owner must submit an analysis of the project's Utility Allowances. Such data as changes in utility...

  14. 45 CFR 1801.43 - Allowance for books.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Allowance for books. 1801.43 Section 1801.43... HARRY S. TRUMAN SCHOLARSHIP PROGRAM Payments to Finalists and Scholars § 1801.43 Allowance for books. The cost allowance for a Scholar's books is $1000 per year, or such higher amount published on...

  15. 42 CFR 50.504 - Allowable cost of drugs.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Allowable cost of drugs. 50.504 Section 50.504... APPLICABILITY Maximum Allowable Cost for Drugs § 50.504 Allowable cost of drugs. (a) The maximum amount which may be expended from program funds for the acquisition of any drug shall be the lowest of (1)...

  16. 20 CFR 606.2 - Total credits allowable.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Total credits allowable. 606.2 Section 606.2 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TAX CREDITS UNDER THE... credits allowable. The total credits allowed to an employer subject to the tax imposed by section 3301 of...

  17. 46 CFR 154.412 - Cargo tank corrosion allowance.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo tank corrosion allowance. 154.412 Section 154.412... Containment Systems § 154.412 Cargo tank corrosion allowance. A cargo tank must be designed with a corrosion...) carries a cargo that corrodes the tank material. Note: Corrosion allowance for independent tank type C...

  18. 46 CFR 54.25-5 - Corrosion allowance.

    Science.gov (United States)

    2010-10-01

    ... Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-5 Corrosion allowance. The corrosion allowance must be as required in 46 CFR 54.01-35. ... 46 Shipping 2 2010-10-01 2010-10-01 false Corrosion allowance. 54.25-5 Section 54.25-5...

  19. 32 CFR 842.35 - Depreciation and maximum allowances.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Depreciation and maximum allowances. 842.35... LITIGATION ADMINISTRATIVE CLAIMS Personnel Claims (31 U.S.C. 3701, 3721) § 842.35 Depreciation and maximum allowances. The military services have jointly established the “Allowance List-Depreciation Guide”...

  20. Factors affecting the carbon allowance market in the US

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Seok; Koo, Won W. [Center for Agricultural Policy and Trade Studies, Department of Agribusiness and Applied Economics, North Dakota State University, Dept 7610, P.O. Box 6050, Fargo, ND 58103-6050 (United States)

    2010-04-15

    The US carbon allowance market has different characteristic and price determination process from the EU ETS market, since emitting installations voluntarily participate in emission trading scheme. This paper examines factors affecting the US carbon allowance market. An autoregressive distributed lag model is used to examine the short- and long-run relationships between the US carbon allowance market and its determinant factors. In the long-run, the price of coal is a main factor in the determination of carbon allowance trading. In the short-run, on the other hand, the changes in crude oil and natural gas prices as well as coal price have significant effects on carbon allowance market. (author)

  1. Flexible working motivates all staff.

    Science.gov (United States)

    2001-04-01

    A recent survey has demolished the myth that work-life balance is only of interest to women with children. The survey, commissioned by Lloyds TSB on behalf of the Employers for Work Life Balance organisation, shows that young workers and men are equally interested in flexible working arrangements that allow them to pursue interests outside of work.

  2. Radical reconciliation: The TRC should have allowed Zacchaeus to testify?

    Directory of Open Access Journals (Sweden)

    Tshepo Lephakga

    2016-02-01

    Full Text Available This article seeks to point out that, the inclusion of a theological term – that is ‘reconciliation’ (at the request of F.W. de Klerk on behalf of the National Party to what was supposed to be the ‘Truth Commission’ (Boesak & DeYoung 2012; Stevens Franchi & Swart 2006 – was for the purpose of taming the work of this commission and using reconciliation to merely reach some political accommodation which did not address the critical questions of justice, equality, and dignity which are prominent in the biblical understanding of reconciliation (Boesak 2008; Boesak & DeYoung 2012:1; Lephakga 2015; Terreblanche 2002. However, it is important to point out that, the problem was not the theological word – that is ‘reconciliation’– but the understanding and interpretation of it in South Africa. This is because previously in South Africa the Bible was made a servant to ideology (Lephakga 2012, 2013; Moodie 1975; Serfontein 1982 and thus domesticated for the purposes of subjection and control (Boesak & DeYoung 2012. As such, this article contends that, the call for the inclusion of ‘reconciliation’ within the ‘truth commission’ was not to allow reconciliation to confront the country with the demands of the gospel but to blunt the process of radical change (Boesak & DeYoung 2012. Therefore, this article will point out that the shortcomings of the South African Truth and Reconciliation Commission (TRC need to be understood against the following events which occurred between the period 1989 to 1995: (1 the fall of the Soviet Union (Cronin 1994:2–6; (2 the National Party’s (NP and South African business sector’s interest in negotiations with the African National Congress (ANC (Cronin 1994:2–6; Mkhondo 1993:3–43; Terreblanche 2002:51–124; (3 the elite compromise (Terreblanche 2002:51–124; and the sudden passing of the Promotion of National Unity and Reconciliation Act, no 34 of 1995 (TRC, Vol. 1998. This paper will use

  3. Tram works (TCMC)

    CERN Multimedia

    GS Department

    2011-01-01

    In order to allow the final switchover of traffic, as part of the on-going Tram works (TCMC), please note that the traffic lights at Entrance B will be out of service from 7 to 14 February. In order to ensure traffic safety and allow CERN employees to exit the site, a temporary roundabout will be installed during this week. Department of General Infrastructure Services (GS) GS-SE Group

  4. 29 CFR 778.600 - Veterans' subsistence allow- ances.

    Science.gov (United States)

    2010-07-01

    ... OF GENERAL POLICY OR INTERPRETATION NOT DIRECTLY RELATED TO REGULATIONS OVERTIME COMPENSATION... subsistence allowances provided by Public Law 346 for payment to veterans are not paid as compensation...

  5. Mobility Work

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind; Bossen, Claus

    2005-01-01

    by constructing Standard Operation Procedures (SOPs), actors minimise mobility work by constructing Standard Operation Configurations (SOCs). We apply the concept of mobility work to the ethnography of hospital work, and argue that mobility arises because of the need to get access to people, places, knowledge and....../or resources. To accomplish their work, actors have to make the right configuration of these four aspects emerge....

  6. Developmental Work

    DEFF Research Database (Denmark)

    Møller, Niels; Hvid, Helge; Kristensen, Tage Søndergaard

    2003-01-01

    Human Deveoplment and Working Life - Work for Welfare explores whether the development of human resources at company level can improve individuals' quality of life, companies' possibilities of development, and welfare and democracy in society. Chapter two discuss the concept "developmental work...

  7. Developmental Work

    DEFF Research Database (Denmark)

    Møller, Niels; Hvid, Helge; Kristensen, Tage Søndergaard;

    2003-01-01

    Human Deveoplment and Working Life - Work for Welfare explores whether the development of human resources at company level can improve individuals' quality of life, companies' possibilities of development, and welfare and democracy in society. Chapter two discuss the concept "developmental work...

  8. 20 CFR 362.10 - Principal types of claims allowable.

    Science.gov (United States)

    2010-04-01

    ... which the loss or damage occurred: (1) In a common or natural disaster; (2) When the property was... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Principal types of claims allowable. 362.10... PROCEDURES EMPLOYEES' PERSONAL PROPERTY CLAIMS § 362.10 Principal types of claims allowable. (a) In...

  9. 24 CFR 882.510 - Adjustment of utility allowance.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowance... Moderate Rehabilitation-Program Development and Operation § 882.510 Adjustment of utility allowance. The PHA must determine, at least annually, whether an adjustment is required in the Utility...

  10. 24 CFR 891.645 - Adjustment of utility allowances.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Adjustment of utility allowances... Handicapped-Section 8 Assistance § 891.645 Adjustment of utility allowances. In connection with adjustments of contract rents as provided in § 891.640(a), the requirements for the adjustment of utility...

  11. 24 CFR 982.517 - Utility allowance schedule.

    Science.gov (United States)

    2010-04-01

    ... reasonable accommodation in accordance with 24 CFR part 8 to make the program accessible to and usable by the... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Utility allowance schedule. 982.517... Payment § 982.517 Utility allowance schedule. (a) Maintaining schedule. (1) The PHA must maintain...

  12. 77 FR 66938 - Utility Allowances Submetering; Hearing Cancellation

    Science.gov (United States)

    2012-11-08

    ... Federal Register on August 7, 2012 (77 FR 46987) announced that a public hearing was scheduled for... Internal Revenue Service 26 CFR Part 1 RIN 1545-BI91 Utility Allowances Submetering; Hearing Cancellation... 42 of the Internal Revenue Code; relating to the utility allowance regulations. DATES: The...

  13. 40 CFR 86.1725-01 - Allowable maintenance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Allowable maintenance. 86.1725-01... Trucks § 86.1725-01 Allowable maintenance. This section includes text that specifies requirements that... are subject to the applicable Otto-cycle or diesel engine maintenance requirements of §...

  14. 49 CFR 174.86 - Maximum allowable operating speed.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Maximum allowable operating speed. 174.86 Section... operating speed. (a) For molten metals and molten glass shipped in packagings other than those prescribed in § 173.247 of this subchapter, the maximum allowable operating speed may not exceed 24 km/hour (15...

  15. 42 CFR 489.31 - Allowable charges: Blood.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Allowable charges: Blood. 489.31 Section 489.31... Allowable charges: Blood. (a) Limitations on charges. (1) A provider may charge the beneficiary (or other person on his or her behalf) only for the first three pints of blood or units of packed red...

  16. 48 CFR 1352.216-70 - Estimated and allowable costs.

    Science.gov (United States)

    2010-10-01

    ... Estimated and allowable costs. As prescribed in 48 CFR 1316.307(a), insert the following clause: Estimated and Allowable Costs (APR 2010) (a) Estimated Costs. The estimated cost of this contract is... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Estimated and...

  17. 26 CFR 31.3402(m)-1 - Withholding allowances.

    Science.gov (United States)

    2010-04-01

    ... individuals. (i) Except as provided in subdivision (ii) of this subparagraph, a husband and wife shall... of their combined wages and allowable items. The withholding allowances to which a husband and wife are entitled may be claimed by the husband, by the wife, or they may be allocated between...

  18. 9 CFR 51.32 - Claims not allowed.

    Science.gov (United States)

    2010-01-01

    ... COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF BRUCELLOSIS Indemnity for Sheep, Goats, and Horses § 51.32 Claims not allowed. Claims for indemnity for goats, sheep, and horses destroyed because of brucellosis will not be allowed if any of the following...

  19. 46 CFR 64.15 - Allowable stress; framework.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Allowable stress; framework. 64.15 Section 64.15... AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.15 Allowable stress; framework. The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material...

  20. 30 CFR 33.33 - Allowable limits of dust concentration.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Allowable limits of dust concentration. 33.33... MINES Test Requirements § 33.33 Allowable limits of dust concentration. (a) The concentration of dust determined by the control sample shall be subtracted from the average concentration of dust determined by the...

  1. Final Report-- A Novel Storage Method for Concentrating Solar Power Plants Allowing Storage at High Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Jeffrey F.

    2014-09-29

    The main objective of the proposed work was the development and testing of a storage method that has the potential to fundamentally change the solar thermal industry. The development of a mathematical model that describes the phenomena involved in the heat storage and recovery was also a main objective of this work. Therefore, the goal was to prepare a design package allowing reliable scale-up and optimization of design.

  2. Work Coordination Engine

    Science.gov (United States)

    Zendejas, Silvino; Bui, Tung; Bui, Bach; Malhotra, Shantanu; Chen, Fannie; Kim, Rachel; Allen, Christopher; Luong, Ivy; Chang, George; Sadaqathulla, Syed

    2009-01-01

    The Work Coordination Engine (WCE) is a Java application integrated into the Service Management Database (SMDB), which coordinates the dispatching and monitoring of a work order system. WCE de-queues work orders from SMDB and orchestrates the dispatching of work to a registered set of software worker applications distributed over a set of local, or remote, heterogeneous computing systems. WCE monitors the execution of work orders once dispatched, and accepts the results of the work order by storing to the SMDB persistent store. The software leverages the use of a relational database, Java Messaging System (JMS), and Web Services using Simple Object Access Protocol (SOAP) technologies to implement an efficient work-order dispatching mechanism capable of coordinating the work of multiple computer servers on various platforms working concurrently on different, or similar, types of data or algorithmic processing. Existing (legacy) applications can be wrapped with a proxy object so that no changes to the application are needed to make them available for integration into the work order system as "workers." WCE automatically reschedules work orders that fail to be executed by one server to a different server if available. From initiation to completion, the system manages the execution state of work orders and workers via a well-defined set of events, states, and actions. It allows for configurable work-order execution timeouts by work-order type. This innovation eliminates a current processing bottleneck by providing a highly scalable, distributed work-order system used to quickly generate products needed by the Deep Space Network (DSN) to support space flight operations. WCE is driven by asynchronous messages delivered via JMS indicating the availability of new work or workers. It runs completely unattended in support of the lights-out operations concept in the DSN.

  3. School Social Work Worldwide.

    Science.gov (United States)

    Huxtable, Marion, Ed.; Blyth, Eric, Ed.

    This book, with sequentially arranged chapters, allow practitioners, educators, and students to follow the expansion of school social work practice around the world. Leaders in the field from 12 countries provide eye-opening perspectives and interventions, selected for their range and application. Additionally, the book looks ahead to policy and…

  4. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ..., Johnston Atoll and Palmyra Atoll. (d) Existing FEP fisheries shall follow the allowable gear and methods... decision on the permissibility of this gear type will be made by the Regional Administrator...

  5. 45 CFR 1386.25 - Allowable litigation costs.

    Science.gov (United States)

    2010-10-01

    ..., DEVELOPMENTAL DISABILITIES PROGRAM FORMULA GRANT PROGRAMS State System for Protection and Advocacy of the Rights... be used to pay the otherwise allowable costs incurred by a Protection and Advocacy System in...

  6. 30 CFR 206.157 - Determination of transportation allowances.

    Science.gov (United States)

    2010-07-01

    ... a series of outgoing pipelines; (5) Gas Research Institute (GRI) fees. The GRI conducts research... industry and gas customers. GRI fees are allowable provided such fees are mandatory in FERC-approved...

  7. 7 CFR 52.782 - Allowances for quality factors.

    Science.gov (United States)

    2010-01-01

    ... PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Canned Red Tart Pitted Cherries 1 Allowances... average 1 per 30 ozs 4 or more in any sample unit Sample average 1 per 20 ozs. Defects: 100 cherries...

  8. Case work

    DEFF Research Database (Denmark)

    Shaw, Ian Frank

    2016-01-01

    Answers to the question just what is the ?case? partly defined the fields of sociology and social work in early 20th century Chicago. Drawing on the archives of the University of Chicago, I describe and appraise the way the ?case? figured in social work at Chicago and elsewhere. I ask...... the corresponding question of sociology. Finally, I briefly consider why not much came of social work and sociology ploughing similar territory in ways that served for a time to hallmark their identities. This analysis opens up ways of rethinking how social work and sociological research are distinctive...

  9. Paper works

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    2017-01-01

    of their land and natural resources, but also of labor and territorial sovereignty. This case shows how an Andean campesino community counters such movements by a wide repertoire of legal and social actions that works simultaneously in legal and extra-legal domains. Paper works mediate claims to territorial...

  10. Works Councils

    DEFF Research Database (Denmark)

    Knudsen, Herman Lyhne; Markey, Ray

    2002-01-01

    The article outlines the operation of works councils in Europe and in the context of disscussing their viability in Austalia.......The article outlines the operation of works councils in Europe and in the context of disscussing their viability in Austalia....

  11. Sedentary work

    DEFF Research Database (Denmark)

    Eriksen, Dorte; Rosthøj, Susanne; Burr, Hermann

    2015-01-01

    OBJECTIVE: The aim of this study is to investigate the association between five-year changes in occupational sitting and body mass index (BMI) in working adults. METHODS: We analyzed data from The Danish Work Environment Cohort Study (2005 and 2010, n=3.482). Data on occupational sitting, weight...

  12. ACCOUNTING FOR GREENHOUSE GASES EMISSIONS ALLOWANCES IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Marius Deac

    2013-02-01

    Full Text Available The present paper tries to analyze the accounting challenges that the implementation of EU Emissions Trading Scheme has risen. On 2 December 2004, IASB has issued an interpretation regarding the accounting of the GHG emissions allowances (IFRIC 3 „Emission Rights”. This interpretation should have been effective for annual periods beginning after 1 March 2005, the first year of the EU Emission Trading Scheme implementation. Less than a year after it was issued, IFRIC has withdrawn IFRIC 3. In December 2007, IASB has started a new project in order to provide guidance on accounting for carbon allowances called Emissions Trading Schemes Project. In the absence of an accounting standard regarding the accounting of these emissions allowances a diversity of accounting practices have been identified. Nowadays, there are three main accounting practices for the recognition of the emissions allowances and the GHG emissions liabilities: IFRIC 3 approach, the government grants approach and the net liability or off balance sheet approach. The accounting treatment of greenhouse gas emissions allowances by Romanian companies resembles the net liability or off balance sheet approach. Finance Ministry Order no. 1118/2012 states that GHG emission certificates should be recognized as fixed assets (if the entity is expecting a profit in the long term or in the category of short term investments (if the entity is expecting a profit in the short term. The accounting of the greenhouse gas emissions allowances described above is applicable mainly to traders of such certificates and not for the installations in the scope of the EU ETS directive, which should recognize GHG emissions off balance sheet, at their nominal value (nil if received for free. The shortfall or excess of allowances will be recognized in the profit or loss as they are bought or sold by the entity (the accounting treatment imposed by Finance Ministry Order no. 3055/2009.

  13. On the Methods for Calculating Annual Allowable Cut

    Directory of Open Access Journals (Sweden)

    V. А. Sokolov

    2014-10-01

    Full Text Available Crisis in supplying regions and the country related to available forest resources and low profitability of forest sector, as a whole, is an indicator of failure of the existing model of forest management and forest use organization in Russia at the present time. Many Russian regions, which are traditionally considered as forest industrial territories, face the challenge of lack of economically accessible forests. The forests are decreasing against a background of under exploitation of the annual allowable cut. This situation occurs in Siberia as well. In many cases, using calculated allowable cut will result in unsustainable harvest levels and a future decrease of accessible forest resources. Thus, the statement that «a volume of wood resource utilization is determined by allowable cut represented the scientifically grounded norm of sustainable forest use» is considered as no more than the declarative proposition. Modeling the normal forest, and using a formula of allowable cut calculation estimated for some decades based on the modeling, is totally unreliable and unreal. The long-term forecast should use analog methods, but it will hardly be sufficiently accurate and adequate to set norms. In order to estimate ecological and economic accessibility of forest resources, an algorithm was made, and a method and model were developed. This model is based on GIS-database and makes it possible to estimate accessibility of forest resources and to map it as well. The conclusion on necessity to determine annual allowable cut in two varieties was drawn following the procedures for calculating annual allowable cut. The first variety is silvicultural (according the currently used methods and the other one is economically accessible allowable cut, which could provide economic effective use of tradable mature wood, taking in to account ecological and economic accessibility of forest resources.

  14. Work Stress

    OpenAIRE

    Roeters, Anne

    2014-01-01

    Most of us agree that stress is a growing problem within organizations. We hear about the postal workers who had killed fellow employees and supervisors, and then hear that a major cause of tension is at work. Friends tell us that they are stressed due to increased workload and he has to work overtime because the company is restructured. We read the polls that employees complain about the stress in trying to balance family life with the work. Stress is a dynamic condition in which an individu...

  15. Effect of Forging Allowance Value on the Power Consumption of Machining Process

    Directory of Open Access Journals (Sweden)

    L. D. Mal'kova

    2015-01-01

    Full Text Available The paper aim is to develop and study possible energy-efficiency measures for machined forgings drawing on analysis of the impact of the allowance for machining and its scatter.The most sophisticated option to take into consideration the effect of the cut depth is the work-piece machining in which the forging allowance value results from the blank production.Research of power consumption was conducted for turning the cylindrical surface of 144 mm length and  1,5 33 0,5   diameter on forgings of the work-pieces "screw of steering control" made from steel 60PP. A radial dimension allowance at said cylindrical surface at six points of the five sections was sized to assess the allowance value dispersion. The size of the sample measurements at the control points was n = 600. Statistic processing has shown normal law of distribution and sample homogeneity.To analyze the results of experiments was calculated a range of allowances for this workpiece. Calculated minimum and maximum allowance per one side for rough lathing were, respectively, 0.905 mm and 1.905mm. It was found that 77% points under control lie in calculated range of allowance values. And there are no points out of the range on lesser side that proves a lack of rejects; but there are points out of the range on the bigger side, that will require additional costs for machining the specified surface, including the cost of electricity.There were three power consumption calculations based on factory- recommended duty: for processing the entire sample of forgings with an average allowance, for machining forgings allowances of which are within the recommended design range of allowance, and for processing the entire sample of forgings with a minimum value of allowance.It was found that elimination of allowance values which are outside the recommended range enables to reduce the power consumption, at least, by 6%, and the overall power consumption for processing the measured forgings

  16. Does "Social Work Abstracts" Work?

    Science.gov (United States)

    Holden, Gary; Barker, Kathleen; Covert-Vail, Lucinda; Rosenberg, Gary; Cohen, Stephanie A.

    2008-01-01

    Objective: The current study seeks to provide estimates of the adequacy of journal coverage in the Social Work Abstracts (SWA) database. Method: A total of 23 journals listed in the Journal Citation Reports social work category during the 1997 to 2005 period were selected for study. Issue-level coverage estimates were obtained for SWA and…

  17. Does "Social Work Abstracts" Work?

    Science.gov (United States)

    Holden, Gary; Barker, Kathleen; Covert-Vail, Lucinda; Rosenberg, Gary; Cohen, Stephanie A.

    2008-01-01

    Objective: The current study seeks to provide estimates of the adequacy of journal coverage in the Social Work Abstracts (SWA) database. Method: A total of 23 journals listed in the Journal Citation Reports social work category during the 1997 to 2005 period were selected for study. Issue-level coverage estimates were obtained for SWA and…

  18. Allowing for crystalline structure effects in Geant4

    Science.gov (United States)

    Bagli, Enrico; Asai, Makoto; Dotti, Andrea; Pandola, Luciano; Verderi, Marc

    2017-07-01

    In recent years, the Geant4 toolkit for the Monte Carlo simulation of radiation with matter has seen large growth in its divers user community. A fundamental aspect of a successful physics experiment is the availability of a reliable and precise simulation code. Geant4 currently does not allow for the simulation of particle interactions with anything other than amorphous matter. To overcome this limitation, the GECO (GEant4 Crystal Objects) project developed a general framework for managing solid-state structures in the Geant4 kernel and validate it against experimental data. Accounting for detailed geometrical structures allows, for example, simulation of diffraction from crystal planes or the channeling of charged particle.

  19. The economics of allowing more U.S. oil drilling

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Robert [University of Manchester (United Kingdom); Smith School University of Oxford (United Kingdom); Georgetown Center for Business and Public Policy (United States); Passell, Peter [Milken Institute (United States)

    2010-05-15

    This paper examines the likely impact of developing U.S. energy resources on oil prices. In addition, we examine the benefits and costs of allowing drilling in the Arctic National Wildlife Refuge and the areas of the Outer Continental Shelf that were until recently closed to drilling. We find that allowing oil drilling in ANWR and the off-limits OCS would be likely to have a very modest impact on oil prices - on the order of 1%. However, a benefit-cost analysis of developing ANWR and off-limits OCS suggests that the benefits are likely to exceed the costs. (author)

  20. CITA works

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette; Tamke, Martin; Ayres, Phil;

    2015-01-01

    CITA works documents over 40 projects, events and research collaborations conducted between 2005 and 2014 by the Centre for Information Technology and Architecture (CITA). Through individual project descriptions accompanied by photographic documentation and design drawings, CITA works provides...... readers with insights into our design-led practice-based architectural research which queries how computation challenges the way we think, design and build architecture. With essays by Professor Mette Ramsgaard Thomsen (Head of CITA), and Dr. Jane Burry (Head of the Spatial Information Architecture...... Laboratory, RMIT) the work is contextualised within the field of digital architectural design practice. These essays also identify the emerging questions and maturing methods that continue to inform CITA’s research within this territory. CITA works marks the first 10 years of our research effort...

  1. Video Allows Young Scientists New Ways to Be Seen

    Science.gov (United States)

    Park, John C.

    2009-01-01

    Science is frequently a visual endeavor, dependent on direct or indirect observations. Teachers have long employed motion pictures in the science classroom to allow students to make indirect observations, but the capabilities of digital video offer opportunities to engage students in active science learning. Not only can watching a digital video…

  2. 44 CFR 11.74 - Claims not allowed.

    Science.gov (United States)

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Claims not allowed. 11.74 Section 11.74 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF..., checks, promissory notes, stock certificates, bonds, bills of lading, warehouse receipts, baggage...

  3. 30 CFR 206.159 - Determination of processing allowances.

    Science.gov (United States)

    2010-07-01

    ... depreciation, the lessee may elect to use either a straight-line depreciation method based on the life of..., including operating and maintenance expenses, overhead, and either depreciation and a return on..., including royalties, are not allowable expenses. (iv) A lessee may use either depreciation or a return...

  4. 20 CFR 322.7 - Dismissal, coordination, and separation allowances.

    Science.gov (United States)

    2010-04-01

    ... UNEMPLOYMENT INSURANCE ACT REMUNERATION § 322.7 Dismissal, coordination, and separation allowances. (a... relationship and remains subject to call. Such pay is remuneration with respect to each day in the month or... employee who voluntarily or involuntarily terminates his or her employment relationship is not...

  5. 20 CFR 429.203 - When is a claim allowable?

    Science.gov (United States)

    2010-04-01

    ... paragraph (a) of this section and the other provisions of this subpart, any claim you make for damage to, or... excluded under this subpart: (1) Property damage in quarters or other authorized places. Claims are allowable for damage to, or loss of, property arising from fire, flood, hurricane, other natural...

  6. 30 CFR 206.261 - Transportation allowances-general.

    Science.gov (United States)

    2010-07-01

    ... quantity of clean coal output and the rejected waste material. The transportation allowance shall be... MANAGEMENT PRODUCT VALUATION Federal Coal § 206.261 Transportation allowances—general. (a) For ad valorem... the coal from a Federal lease to a sales point which is remote from both the lease and mine; or...

  7. 30 CFR 206.460 - Transportation allowances-general.

    Science.gov (United States)

    2010-07-01

    ... quantity of clean coal output and the rejected waste material. The transportation allowance shall be... MANAGEMENT PRODUCT VALUATION Indian Coal § 206.460 Transportation allowances—general. (a) For ad valorem... the coal from an Indian lease to a sales point which is remote from both the lease and mine; or...

  8. Conditions allowing the formation of biogenic amines in cheese

    NARCIS (Netherlands)

    Joosten, H.M.L.J.

    1988-01-01

    A study was undertaken to reveal the conditions that allow the formation of biogenic amines in cheese.

    The starters most commonly used in the Dutch cheese industry do not have decarboxylative properties. Only if the milk or curd is contaminated with non-starter bacteria, amine

  9. Conditions allowing the formation of biogenic amines in cheese.

    NARCIS (Netherlands)

    Joosten, H.M.L.J.

    1988-01-01

    A study was undertaken to reveal the conditions that allow the formation of biogenic amines in cheese.The starters most commonly used in the Dutch cheese industry do not have decarboxylative properties. Only if the milk or curd is contaminated with non-starter bacteria, amine formation may be observ

  10. Blackboard allows students to take quizzes on the go.

    Science.gov (United States)

    Neville, Michael W

    2003-01-01

    New Web-based technologies offer innovative opportunities in nursing courses. Blackboard is one such program that allows faculty to interact with students in new ways. Experimentally, this software's online quizzes were substituted for traditional in-class quizzes in a master's level advanced pharmacology course. The author discusses concerns, benefits, and pitfalls of the online assessment features of Blackboard.

  11. Disability and Supported Employment: Impact on Employment, Income, and Allowances

    Science.gov (United States)

    Germundsson, Per; Gustafsson, Johanna; Lind, Martin; Danermark, Berth

    2012-01-01

    In this article, we examine supported employment and its impact on the level of employment, disposable income, and sum of allowances, targeting a group of individuals with disabilities. We have particularly focused on individuals with psychiatric disabilities. Supported employment is a vocational rehabilitation service with an empowerment approach…

  12. Mitigation of Global Warming with Focus on Personal Carbon Allowances

    DEFF Research Database (Denmark)

    Meyer, Niels I

    2008-01-01

    The mitigation of global warming requires new efficient systems and methods. The paper presents a new proposal called personal carbon allowances with caps on the CO2 emission from household heating and electricity and on emission from transport in private cars and in personal air flights. Results...

  13. 34 CFR 390.41 - What are allowable costs?

    Science.gov (United States)

    2010-07-01

    ... conduct of the seminar, institute, workshop or other short course for which the grant support has been... AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION REHABILITATION SHORT-TERM TRAINING What... costs established in EDGAR §§ 75.530-75.562, the following items are allowable under short-term...

  14. 48 CFR 752.7028 - Differential and allowances.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Differential and allowances. 752.7028 Section 752.7028 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL... compensation to an employee in a foreign area where civil insurrection, civil war, terrorism or...

  15. 41 CFR 101-27.503 - Allowable credit.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Allowable credit. 101-27.503 Section 101-27.503 Public Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 27-INVENTORY MANAGEMENT 27.5...

  16. 38 CFR 21.332 - Payments of subsistence allowance.

    Science.gov (United States)

    2010-07-01

    ... payment only: (1) At the beginning of an ordinary school year; or (2) At the beginning of any other....C. 3680(g)) (g) Payments for courses which are repeated. VA may pay subsistence allowance to a veteran who repeats a course under conditions described in § 21.132. (Authority: 38 U.S.C. 3680(a))...

  17. 40 CFR 18.8 - Stipends, Allowances, and Benefits.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Stipends, Allowances, and Benefits. 18.8 Section 18.8 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL ENVIRONMENTAL... continental United States, the payment of expenses of preparing the remains for burial and transporting...

  18. 9 CFR 50.22 - Claims not allowed.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Claims not allowed. 50.22 Section 50.22 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF...

  19. 30 CFR 206.262 - Determination of transportation allowances.

    Science.gov (United States)

    2010-07-01

    ... REVENUE MANAGEMENT PRODUCT VALUATION Federal Coal § 206.262 Determination of transportation allowances. (a... transporting the coal under that contract, subject to monitoring, review, audit, and possible future adjustment... are generally those for depreciable fixed assets (including costs of delivery and installation...

  20. Can preapproval jump-start the allowance market

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, D.J.; Goffman, J.

    1992-06-01

    With compliance deadlines approaching in three years, utility, environmental and financial planners and their regulators are in the process of grappling with the requirements imposed, and opportunities created, by the acid rain program established under Title 4 of the Clean Air Act amendments of 1990. The novel element of the program - emissions or allowance trading through a nationwide allowance market - presents great challenges for utilities and their regulators. Perhaps the foremost challenge is establishing the allowance market. If state utility commissions subject utilities' compliance strategies to traditional after-the-fact prudence reviews, as tradition would impel them to do, the attendant regulatory risks are likely to push utilities toward more conservative compliance schemes that underuse allowance trading (as the exchange at the head of this article demonstrates). If that happens, the market will fail to develop, and its full potential for environmental benefit at least cost will go unrealized. This, in turn, is likely to strengthen the case for non-market regulatory mechanisms - a vicious circle. In this paper, the authors suggest a way out of this.

  1. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Outer Burial Receptacle... (CONTINUED) NATIONAL CEMETERIES OF THE DEPARTMENT OF VETERANS AFFAIRS § 38.629 Outer Burial Receptacle Allowance. (a) Definitions—Outer burial receptacle. For purposes of this section, an outer burial...

  2. Mitigation of Global Warming with Focus on Personal Carbon Allowances

    DEFF Research Database (Denmark)

    Meyer, Niels I

    2008-01-01

    The mitigation of global warming requires new efficient systems and methods. The paper presents a new proposal called personal carbon allowances with caps on the CO2 emission from household heating and electricity and on emission from transport in private cars and in personal air flights. Results...

  3. 32 CFR 584.7 - Basic allowance for quarters.

    Science.gov (United States)

    2010-07-01

    ... CUSTODY, AND PATERNITY § 584.7 Basic allowance for quarters. (a) Eligibility. (1) Soldiers entitled to...-dependents rate each month in support of their families. (See DODPM, part 3.) This is so even if a divorce... spouse or stepchildren after the divorce. BAQ at the “with dependents” rate is not authorized when...

  4. 40 CFR 14.11 - Principal types of allowable claims.

    Science.gov (United States)

    2010-07-01

    ... of delivery of the household goods or within a reasonable time after discovery, any award by EPA will... employee to possess under the circumstances at the time of the loss or damage. In evaluating whether a... damages to household goods may be allowed where: (i) The loss or damages occurred while the goods were...

  5. Supporting clinician educators to achieve “work-work balance”

    Directory of Open Access Journals (Sweden)

    Jerry M Maniate

    2016-10-01

    Full Text Available Clinician Educators (CE have numerous responsibilities in different professional domains, including clinical, education, research, and administration. Many CEs face tensions trying to manage these often competing professional responsibilities and achieve “work-work balance.” Rich discussions of techniques for work-work balance amongst CEs at a medical education conference inspired the authors to gather, analyze, and summarize these techniques to share with others. In this paper we present the CE’s “Four Ps”; these are practice points that support both the aspiring and established CE to help improve their performance and productivity as CEs, and allow them to approach work-work balance.

  6. 40 CFR 35.940-3 - Costs allowable, if approved.

    Science.gov (United States)

    2010-07-01

    ... of compost residues which result from wastewater treatment, if EPA has approved a program for use of the compost. (d) Acquisition of an operable portion of a treatment works. This type of acquisition...

  7. Working Collaboratively

    DEFF Research Database (Denmark)

    Holder, Anna; Lovett, George

    2009-01-01

    Working collaboratively is arguably an essential skill in architectural practice as the complexity of contemporary projects involves multiple agents in the conception, construction and use of architecture. This has been emphasised by recent government rhetoric. Mass collaboration has been...... identified as a transformative global force of the last decade, most notably in knowledge and information publishing, communication and creation. This paper presents a structured conversation on changing understandings of collaboration, and the realities of collaborative methodology in architectural work....... Ideas of the platforms and structures necessary to support ‘creative’ collaborations are advanced and tested, and a vocabulary of key terms is developed. The conversation extends to reflect on the role of the architecture profession in supporting or enabling collaboration in architectural works....

  8. Studies with spike initiators - Linearization by noise allows continuous signal modulation in neural networks

    Science.gov (United States)

    Yu, Xiaolong; Lewis, Edwin R.

    1989-01-01

    It is shown that noise can be an important element in the translation of neuronal generator potentials (summed inputs) to neuronal spike trains (outputs), creating or expanding a range of amplitudes over which the spike rate is proportional to the generator potential amplitude. Noise converts the basically nonlinear operation of a spike initiator into a nearly linear modulation process. This linearization effect of noise is examined in a simple intuitive model of a static threshold and in a more realistic computer simulation of spike initiator based on the Hodgkin-Huxley (HH) model. The results are qualitatively similar; in each case larger noise amplitude results in a larger range of nearly linear modulation. The computer simulation of the HH model with noise shows linear and nonlinear features that were earlier observed in spike data obtained from the VIIIth nerve of the bullfrog. This suggests that these features can be explained in terms of spike initiator properties, and it also suggests that the HH model may be useful for representing basic spike initiator properties in vertebrates.

  9. Aspects of quantum work.

    Science.gov (United States)

    Talkner, Peter; Hänggi, Peter

    2016-02-01

    Various approaches of defining and determining work performed on a quantum system are compared. Any operational definition of work, however, must allow for two facts: first, that work characterizes a process rather than an instantaneous state of a system and, second, that quantum systems are sensitive to the interactions with a measurement apparatus. We compare different measurement scenarios on the basis of the resulting postmeasurement states and the according probabilities for finding a particular work value. In particular, we analyze a recently proposed work meter for the case of a Gaussian pointer state and compare it with the results obtained by two projective and, alternatively, two Gaussian measurements. In the limit of a strong effective measurement strength the work distribution of projective two energy measurements can be recovered. In the opposite limit the average of work becomes independent of any measurement. Yet the fluctuations about this value diverge. The performance of the work meter is illustrated by the example of a spin in a suddenly changing magnetic field.

  10. Just do it: action-dependent learning allows sensory prediction.

    Directory of Open Access Journals (Sweden)

    Itai Novick

    Full Text Available Sensory-motor learning is commonly considered as a mapping process, whereby sensory information is transformed into the motor commands that drive actions. However, this directional mapping, from inputs to outputs, is part of a loop; sensory stimuli cause actions and vice versa. Here, we explore whether actions affect the understanding of the sensory input that they cause. Using a visuo-motor task in humans, we demonstrate two types of learning-related behavioral effects. Stimulus-dependent effects reflect stimulus-response learning, while action-dependent effects reflect a distinct learning component, allowing the brain to predict the forthcoming sensory outcome of actions. Together, the stimulus-dependent and the action-dependent learning components allow the brain to construct a complete internal representation of the sensory-motor loop.

  11. 17 CFR 240.17i-7 - Calculations of allowable capital and risk allowances or alternative capital assessment.

    Science.gov (United States)

    2010-04-01

    ... factor. Each Value at Risk model shall meet the applicable qualitative and quantitative requirements set... historical data to support a Value at Risk model, the measure obtained by computing the allowance for market... investment bank holding company or member of the affiliate group can demand payment after any payment is...

  12. Moral dilemma: to kill or allow to die?

    Science.gov (United States)

    Cole, J J

    1989-01-01

    The thesis of this paper is that while allowing a person to die with care can be morally justified in particular cases, the option of mercy killing can never be morally defended. There is a significant moral difference between these two concepts. Furthermore, the wedge argument, the medical fallibility argument, and the medical care and trust argument provide cogent and convincing reasons for maintaining a legal distinction between mercy killing and letting a person die.

  13. FINAL REMINDER: Extension/suppression of allowance for dependent child

    CERN Multimedia

    Human Resources Department

    2005-01-01

    Members of the personnel with dependent children aged 18 or above (or reaching 18 during the 2005/2006 school year) who have not yet provided a SCHOOL CERTIFICATE must do so as soon as possible. If we have not received this certificate by 2 December 2005 at the latest, the child allowance will be withdrawn retroactively as from 1 September 2005. Human Resources Department Tel. 72862

  14. Mass spectrometry allows direct identification of proteins in large genomes

    DEFF Research Database (Denmark)

    Küster, B; Mortensen, Peter V.; Andersen, Jens S.

    2001-01-01

    Proteome projects seek to provide systematic functional analysis of the genes uncovered by genome sequencing initiatives. Mass spectrometric protein identification is a key requirement in these studies but to date, database searching tools rely on the availability of protein sequences derived fro...... genome and allows identification, mapping, cloning and assistance in gene prediction of any protein for which minimal mass spectrometric information can be obtained. Several novel proteins from Arabidopsis thaliana and human have been discovered in this way....

  15. Scientific substantination of maximum allowable concentration of fluopicolide in water

    Directory of Open Access Journals (Sweden)

    Pelo I.М.

    2014-03-01

    Full Text Available In order to substantiate fluopicolide maximum allowable concentration in the water of water reservoirs the research was carried out. Methods of study: laboratory hygienic experiment using organoleptic and sanitary-chemical, sanitary-toxicological, sanitary-microbiological and mathematical methods. The results of fluopicolide influence on organoleptic properties of water, sanitary regimen of reservoirs for household purposes were given and its subthreshold concentration in water by sanitary and toxicological hazard index was calculated. The threshold concentration of the substance by the main hazard criteria was established, the maximum allowable concentration in water was substantiated. The studies led to the following conclusions: fluopicolide threshold concentration in water by organoleptic hazard index (limiting criterion – the smell – 0.15 mg/dm3, general sanitary hazard index (limiting criteria – impact on the number of saprophytic microflora, biochemical oxygen demand and nitrification – 0.015 mg/dm3, the maximum noneffective concentration – 0.14 mg/dm3, the maximum allowable concentration - 0.015 mg/dm3.

  16. Allowed and forbidden transitions in artificial hydrogen and helium atoms.

    Science.gov (United States)

    Fujisawa, Toshimasa; Austing, David Guy; Tokura, Yasuhiro; Hirayama, Yoshiro; Tarucha, Seigo

    2002-09-19

    The strength of radiative transitions in atoms is governed by selection rules that depend on the occupation of atomic orbitals with electrons. Experiments have shown similar electron occupation of the quantized energy levels in semiconductor quantum dots--often described as artificial atoms. But unlike real atoms, the confinement potential of quantum dots is anisotropic, and the electrons can easily couple with phonons of the material. Here we report electrical pump-and-probe experiments that probe the allowed and 'forbidden' transitions between energy levels under phonon emission in quantum dots with one or two electrons (artificial hydrogen and helium atoms). The forbidden transitions are in fact allowed by higher-order processes where electrons flip their spin. We find that the relaxation time is about 200 micro s for forbidden transitions, 4 to 5 orders of magnitude longer than for allowed transitions. This indicates that the spin degree of freedom is well separated from the orbital degree of freedom, and that the total spin in the quantum dots is an excellent quantum number. This is an encouraging result for potential applications of quantum dots as basic entities for spin-based quantum information storage.

  17. Work sampling

    OpenAIRE

    Salas Bacalla, julio; FII-UNMSM

    2014-01-01

    Work sampling is a method of indirect measurement, which means instantaneous observations, to determine the amount of uptime or downtime in a production process El muestreo de trabajo es un método de medición indirecto, que mediante observaciones instantaneas, permite determinar la cantidad de tiempo en actividad o inactividad en un proceso productivo

  18. Hard work

    NARCIS (Netherlands)

    Myra Keizer; Saskia Keuzenkamp

    2011-01-01

    Original title: Moeilijk werken More than one in ten women say they are not available for the labour market because of health complaints. That is almost twice as many as the figure for men. Migrant women, in particular, often cite health as a reason for not being able to work. Are there

  19. Demolition work

    CERN Document Server

    2004-01-01

    Because of demolition work inside Bldg. 251, two containers will be placed on the route Démocrite. For security reasons, the part of this road in front of barrack 553 will be closed to circulation from 5 to 12 November. Thank you, in advance for your understanding. PH-SMI

  20. Road works

    CERN Multimedia

    GS Department

    2010-01-01

    From Monday 11 October until Friday 29 October 2010, the flow of traffic will be disrupted by road works at the roundabout in front of Restaurant No. 2; The number of spaces available in the car park in front of Rest. No. 2 will be reduced. Thank you for your understanding during this period. GS/SEM Group

  1. Wetlands Work

    Science.gov (United States)

    Messina, Linda; Blanchard, Pamela Borne

    2004-01-01

    This article describes how a biology teacher's search for a cross-curricular project in science, math, history, and environmental science, that would help her students connect what they were learning in the classroom to their everyday life, resulted in an ongoing stewardship project. Working together with the Louisiana Sea Grant College Program…

  2. Wetlands Work

    Science.gov (United States)

    Messina, Linda; Blanchard, Pamela Borne

    2004-01-01

    This article describes how a biology teacher's search for a cross-curricular project in science, math, history, and environmental science, that would help her students connect what they were learning in the classroom to their everyday life, resulted in an ongoing stewardship project. Working together with the Louisiana Sea Grant College Program…

  3. Working Parents

    Science.gov (United States)

    ... on your time and energy. For example, the family can work together to clean up the kitchen after dinner; with everyone's help it will get done much quicker and free up some time for you in the evening. Do the same on the ... build family cohesiveness while finishing the job faster, thus leaving ...

  4. Construction work

    CERN Multimedia

    2004-01-01

    Construction work on building 179 will start on the 16th February 2004 and continue until November 2004. The road between buildings 179 and 158 will temporarily become a one way street from Route Democrite towards building 7. The parking places between buildings 179 and 7 will become obsolete. The ISOLDE collaboration would like to apologize for any inconveniences.

  5. Work and minor work contracts

    CERN Document Server

    1999-01-01

    The Work and Minor Work contracts are all of the result-oriented type. The work is specified by CERN and the contractor is given full responsibility for its performance. The contracts are thus very similar to supply contracts. The re-tendering of the existing contracts is almost complete, except for some building maintenance contracts. A new cycle of re-tendering for some activities will be launched in the next twelve months. The total estimated expenditure in the year 2000 for the contracts referred to in this document is 27 750 000 Swiss francs at 1999 prices. The Finance Committee is invited: - to approve the proposed expenditure for the extension of contracts for which the estimated amount for the year 2000 exceeds 750 000 Swiss francs, namely those under references 1, 2, 3, 5, 7, 8, 9 and 23, highlighted in Table I; - to take note that all Work and Minor Work contracts have been tendered since 1 January 1994, except the small contracts shown under references 12 and 16 in Table I; - to take note that the ...

  6. 75 FR 78940 - Sales-Based Royalties and Vendor Allowances

    Science.gov (United States)

    2010-12-17

    ... agreement provides A with the right to use L's intellectual property, a trademark. The licensing agreement.... Royalties are the costs associated with the right to use intellectual property such as copyrighted works or... property produced or property acquired for resale (sales- based royalties). This document also...

  7. RESUMING WORK

    CERN Multimedia

    Service Médical

    2000-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: - if the medical absence has been for 21 calendar days or longer, - if absent more than 48 hours due to professional accident. It is incumbent upon the member of the personnel himself/herself to contact the Medical Service 73186, without awaiting its summons.

  8. Works notice

    CERN Multimedia

    GS Department

    2009-01-01

    We would like to inform you that renovation work on the road lighting equipment will take place on the Meyrin site between 19 October and 18 December 2009. During this period, traffic will be disrupted on the Schrödinger, Perrin and Siegbahn roads, ie from Building 274 to Building 188. We request that you comply with the road signs and thank you for your understanding. GS-SEM Group

  9. RESUMING WORK

    CERN Multimedia

    Medical Service

    2001-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: if the medical absence has been for 21 calendar days or longer, if absent more than 48 hours due to professional accident. It is incumbent upon the member of the personnel himself/herself to contact the Medical Service 73186, without awaiting its summons.

  10. RESUMING WORK

    CERN Multimedia

    Medical Service

    2002-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: if the medical absence has been for 21 calendar days or longer, if absent more than 48 hours due to professional accident. It is incumbent upon the member of the personnel himself/herself to contact the Medical Service 73186, without awaiting its summons. Medical Service

  11. RESUMING WORK

    CERN Multimedia

    Service Médical

    2000-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: if the medical absence has been for 21 calendar days or longer, if absent more than 48 hours due to professional accident. It is incumbent upon the member of the personnel himself/herself to contact the Medical Service 73186, without awaiting its summons.

  12. RESUMING WORK

    CERN Multimedia

    Medical Service

    2002-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: if the medical absence has been for 21 calendar days or longer, if absent more than 48 hours due to professional accident. It is incumbent upon the member of the personnel himself/herself to contact the Medical Service 73186, without awaiting its summons. Medical Service

  13. Dutch Energy Investment Allowance (EIA). Energy List for 2013; Energie-investeringsaftrek (EIA). Energielijst 2013

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-01-15

    The Energy Investment Allowance (EIA) is a tax system by means of which the Dutch government supports companies with investments in energy-saving equipment and renewable energy. This brochure explains the assets eligible for EIA and how the scheme works [Dutch] De Energie-investeringsaftrek (EIA) is een fiscale regeling waarmee de overheid ondersteuning biedt voor bedrijven bij investeringen in energiebesparende bedrijfsmiddelen en duurzame energie. In deze brochure wordt uitgelegd welke bedrijfsmiddelen in aanmerking komen voor EIA en hoe de regeling werkt.

  14. Allowable levels of take for the trade in Nearctic songbirds

    Science.gov (United States)

    Johnson, Fred A.; Walters, Matthew A.H.; Boomer, G. Scott

    2012-01-01

    The take of Nearctic songbirds for the caged-bird trade is an important cultural and economic activity in Mexico, but its sustainability has been questioned. We relied on the theta-logistic population model to explore options for setting allowable levels of take for 11 species of passerines that were subject to legal take in Mexico in 2010. Because estimates of population size necessary for making periodic adjustments to levels of take are not routinely available, we examined the conditions under which a constant level of take might contribute to population depletion (i.e., a population below its level of maximum net productivity). The chance of depleting a population is highest when levels of take are based on population sizes that happen to be much lower or higher than the level of maximum net productivity, when environmental variation is relatively high and serially correlated, and when the interval between estimation of population size is relatively long (≥5 years). To estimate demographic rates of songbirds involved in the Mexican trade we relied on published information and allometric relationships to develop probability distributions for key rates, and then sampled from those distributions to characterize the uncertainty in potential levels of take. Estimates of the intrinsic rate of growth (r) were highly variable, but median estimates were consistent with those expected for relatively short-lived, highly fecund species. Allowing for the possibility of nonlinear density dependence generally resulted in allowable levels of take that were lower than would have been the case under an assumption of linearity. Levels of take authorized by the Mexican government in 2010 for the 11 species we examined were small in comparison to relatively conservative allowable levels of take (i.e., those intended to achieve 50% of maximum sustainable yield). However, the actual levels of take in Mexico are unknown and almost certainly exceed the authorized take. Also, the take

  15. Analysis of electric vehicle's trip cost allowing late arrival

    Science.gov (United States)

    Leng, Jun-Qiang; Liu, Wei-Yi; Zhao, Lin

    2017-05-01

    In this paper, we use a car-following model to study each electric vehicle's trip cost and the total trip cost allowing late arrival. The numerical result show that the electricity cost has great effects on each commuter's trip cost and the total trip costs and that these effects are dependent on each commuter's time headway at the origin, but the electricity cost has no prominent impacts on the minimum value of total trip cost under each commuter's different time headway at the origin.

  16. Allowable carbon emissions for medium-to-high mitigation scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Tachiiri, Kaoru; Hargreaves, Julia C.; Annan, James D.; Kawamiya, Michio [Research Inst. for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, (Japan)], e-mail: tachiiri@jamstec.go.jp; Huntingford, Chris [Centre for Ecology and Hydrology, Wallingford (United Kingdom)

    2013-11-15

    Using an ensemble of simulations with an intermediate complexity climate model and in a probabilistic framework, we estimate future ranges of carbon dioxide (CO{sub 2}) emissions in order to follow three medium-high mitigation concentration pathways: RCP2.6, RCP4.5 and SCP4.5 to 2.6. Uncertainty is first estimated by allowing modelled equilibrium climate sensitivity, aerosol forcing and intrinsic physical and biogeochemical processes to vary within widely accepted ranges. Results are then constrained by comparison against contemporary measurements. For both constrained and unconstrained projections, our calculated allowable emissions are close to the standard (harmonised) emission scenarios associated with these pathways. For RCP4.5, which is the most moderate scenario considered in terms of required emission abatement, then after year 2100 very low net emissions are needed to maintain prescribed year 2100 CO{sub 2} concentrations. As expected, RCP2.6 and SCP4.5 to 2.6 require more strict emission reductions. The implication of this is that direct sequestration of carbon dioxide is likely to be required for RCP4.5 or higher mitigation scenarios, to offset any minimum emissions for society to function (the 'emissions floor'). Despite large uncertainties in the physical and biogeochemical processes, constraints from model-observational comparisons support a high degree of confidence in predicting the allowable emissions consistent with a particular concentration pathway. In contrast the uncertainty in the resulting temperature range remains large. For many parameter sets, and especially for RCP2.6, the land will turn into a carbon source within the twenty first century, but the ocean will remain as a carbon sink. For land carbon storage and our modelling framework, major reductions are seen in northern high latitudes and the Amazon basin even after atmospheric CO{sub 2} is stabilised, while for ocean carbon uptake, the tropical ocean regions will be a

  17. Bends in nanotubes allow electric spin control and coupling

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Marcus, Charles Masamed

    2010-01-01

    We investigate combined effects of spin-orbit coupling and magnetic field in carbon nanotubes containing one or more bends along their length. We show how bends can be used to provide electrical control of confined spins, while spins confined in straight segments remain insensitive to electric...... fields. Device geometries that allow general rotation of single spins are presented and analyzed. In addition, capacitive coupling along bends provides coherent spin-spin interaction, including between otherwise disconnected nanotubes, completing a universal set of one- and two-qubit gates....

  18. Paid work and unpaid work

    DEFF Research Database (Denmark)

    Bonke, Jens

    Time-use information is preferably obtained from diaries, as this method is considered more reliable than information from questionnaires. The diary-technique seems to be unique in catching the rhythm of every day life and thereby the structuring of work and leisure during a well-defined and memo...

  19. Finding All Allowed Edges in a Bipartite Graph

    CERN Document Server

    Tassa, Tamir

    2011-01-01

    We consider the problem of finding all allowed edges in a bipartite graph $G=(V,E)$, i.e., all edges that are included in some maximum matching. We show that given any maximum matching in the graph, it is possible to perform this computation in linear time $O(n+m)$ (where $n=|V|$ and $m=|E|$). Hence, the time complexity of finding all allowed edges reduces to that of finding a single maximum matching, which is $O(n^{1/2}m)$ [Hopcroft and Karp 1973], or $O((n/\\log n)^{1/2}m)$ for dense graphs with $m=\\Theta(n^2)$ [Alt et al. 1991]. This time complexity improves upon that of the best known algorithms for the problem, which is $O(nm)$ ([Costa 1994] for bipartite graphs, and [Carvalho and Cheriyan 2005] for general graphs). Other algorithms for solving that problem are randomized algorithms due to [Rabin and Vazirani 1989] and [Cheriyan 1997], the runtime of which is $\\tilde{O}(n^{2.376})$. Our algorithm, apart from being deterministic, improves upon that time complexity for bipartite graphs when $m=O(n^r)$ and $...

  20. Maximum Allowable Dynamic Load of Mobile Manipulators with Stability Consideration

    Directory of Open Access Journals (Sweden)

    Heidary H. R.

    2015-09-01

    Full Text Available High payload to mass ratio is one of the advantages of mobile robot manipulators. In this paper, a general formula for finding the maximum allowable dynamic load (MADL of wheeled mobile robot is presented. Mobile manipulators operating in field environments will be required to manipulate large loads, and to perform such tasks on uneven terrain, which may cause the system to reach dangerous tip-over instability. Therefore, the method is expanded for finding the MADL of mobile manipulators with stability consideration. Moment-Height Stability (MHS criterion is used as an index for the system stability. Full dynamic model of wheeled mobile base and mounted manipulator is considered with respect to the dynamic of non-holonomic constraint. Then, a method for determination of the maximum allowable loads is described, subject to actuator constraints and by imposing the stability limitation as a new constraint. The actuator torque constraint is applied by using a speed-torque characteristics curve of a typical DC motor. In order to verify the effectiveness of the presented algorithm, several simulation studies considering a two-link planar manipulator, mounted on a mobile base are presented and the results are discussed.

  1. [The right to human reproduction. Should surrogate maternity be allowed?].

    Science.gov (United States)

    Corral García, Eduardo

    2013-01-01

    Is addressed in this work if you can accept that in Spain a reproductive rights through the use of assisted reproductive techniques, especially when the client is a single woman and when the baby has undergone a substitution pregnancy or surrogacy, regardless of those who have come to this possibility, which still continues to be considered without any efficacy in the rules governing the matter.

  2. RESUMING WORK

    CERN Multimedia

    2003-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: - if the medical absence has been for 21 calendar days or longer - if absent more than 48 hours due to professional accident It is incumbent upon the member of the personnel himself/herself to contact the Medical Service Tel. 73186, without awaiting its summons. The purpose of this exam is not to check on the absenteeism, but to support the professional reinsertion. Medical Service

  3. RESUMING WORK

    CERN Multimedia

    2003-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: - if the medical absence has been for 21 calendar days or longer - if absent more than 48 hours due to professional accident It is incumbent upon the member of the personnel himself/herself to contact the Medical Service tel. 73186, without awaiting its summons. The purpose of this exam is not to check on the absenteeism, but to support the professional reinsertion. Medical Service

  4. RESUMING WORK

    CERN Multimedia

    2004-01-01

    In application of the Staff Rules and Regulations, every member of the CERN personnel is required to undergo a medical examination on resuming work after sick leave: • if the medical absence has been for 21 calendar days or longer • if absent more than 48 hours due to professional accident It is incumbent upon the member of the personnel himself/herself to contact the Medical Service tel. 73186, without awaiting its summons. The purpose of this exam is not to check on the absenteeism, but to support the professional reinsertion. Medical Service

  5. Evaluation of Reports Required by the Statutes for Distribution of Monetary Donations and Allowances

    Directory of Open Access Journals (Sweden)

    Harun Tugcu

    2007-12-01

    Full Text Available Physicians have to write reports in accordance with the relevant laws, statutes and regulations when requested by the administrations for distribution of monetary donations and allowances. The Statutes for Distribution of Monetary Donations and Allowances show the conditions requiring monetary support, the people who need monetary donations and the types of making monetary donations in cases of disabilities and injuries. We retrospectively reviewed the reports written in accordance with the Statutes for Distribution of Monetary Donations and Allowances in the Department of Forensic Medicine of Gulhane Military Medical Academy between 1st January 2005 and 31st December 2006. There were 87 reports written in accordance with the Statutes for Distribution of Monetary Donations and Allowances. The mean age of the cases was 25.93 ±5.8 years (20-43 years. The most frequent condition requiring monetary support was gun shot wounds (42.6%. The most frequent location of the wounds was the head (31% and there was an increase in the duration of work leave caused by disabilities (p<0.05. The aim of this study was to determine problems which physicians face when they write reports required by the Statutes for Distribution of Monetary Donations and Allowances and to underline the points concerning writing those reports based on the relevant laws. [TAF Prev Med Bull. 2007; 6(6: 475-478

  6. Evaluation of Reports Required by the Statutes for Distribution of Monetary Donations and Allowances

    Directory of Open Access Journals (Sweden)

    Harun Tugcu

    2007-12-01

    Full Text Available Physicians have to write reports in accordance with the relevant laws, statutes and regulations when requested by the administrations for distribution of monetary donations and allowances. The Statutes for Distribution of Monetary Donations and Allowances show the conditions requiring monetary support, the people who need monetary donations and the types of making monetary donations in cases of disabilities and injuries. We retrospectively reviewed the reports written in accordance with the Statutes for Distribution of Monetary Donations and Allowances in the Department of Forensic Medicine of Gulhane Military Medical Academy between 1st January 2005 and 31st December 2006. There were 87 reports written in accordance with the Statutes for Distribution of Monetary Donations and Allowances. The mean age of the cases was 25.93 ±5.8 years (20-43 years. The most frequent condition requiring monetary support was gun shot wounds (42.6%. The most frequent location of the wounds was the head (31% and there was an increase in the duration of work leave caused by disabilities (p<0.05. The aim of this study was to determine problems which physicians face when they write reports required by the Statutes for Distribution of Monetary Donations and Allowances and to underline the points concerning writing those reports based on the relevant laws. [TAF Prev Med Bull 2007; 6(6.000: 475-478

  7. Defoliation patterns and tillering dynamics in Italian ryegrass under different herbage allowances

    Directory of Open Access Journals (Sweden)

    Larissa Arnhold Graminho

    2014-09-01

    Full Text Available This work was carried out in order to generate information on the tillering process and to contribute for the understanding of the defoliation process on Italian ryegrass (Lolium multiflorum Lam. grazed by lambs under different herbage allowances: 6, 8 and12 kg  of dry matter  per100 kg of animal live weight  per day. The grazing method was intermittent. The experimental design was completely randomized following a repeated measure arrangement, with three treatments and two area replications. The intensity of defoliation is greater at 6 and 9% herbage allowances. The defoliation interval is higher at 12% herbage allowance, intermediate at 9% and lower at 6%. The rates of tiller emergence, survival and death, stability index the tiller population are similar for the different herbage allowances and differ according to the phenological stage of ryegrass. Structural changes caused by canopy management with low herbage allowance and/or due to the advance in developmental stage of ryegrass alter defoliation strategies, with more intense and frequent grazing.

  8. Utility regulators and the market for emission allowances

    Energy Technology Data Exchange (ETDEWEB)

    Bohi, D.R.

    1993-07-01

    When it comes to emission trading under the Clean Air Act, a major concern of most people in the electric utilities industry is the effect of this new form of environmental regulation on the industry and the way it is regulated. This paper focuses on a different concern: the effect of the industry and the way it is regulated on the emission trading program. Emission trading must prove to be successful in lowering the cost of reducing sulfur dioxide emissions if this approach to environmental regulation is to be regarded as a viable substitute for traditional command-and-control regulation. In addition, whether or not utilities will buy and sell allowances as intended depends on the actions of the public utility regulators. This paper covers both setting the cost recovery rules and the incentive to sell and the capital gain.

  9. Super-allowed Fermi beta-decay revisited

    CERN Document Server

    Wilkinson, D H

    2002-01-01

    Analysis of J suppi=0 sup +->0 sup + super-allowed Fermi transitions is limited with respect to the precision of its outcome in terms of the Fermi coupling constant neither by the accuracy of the experimental input data nor by the confidence with which the radiative corrections can be applied but rather by knowledge of the nuclear mismatch: the subversion of isospin symmetry along the multiplets. Theoretical estimates of this mismatch differ considerably from to their direct nuclide-by-nuclide application results in an apparent clear violation of the hypothesis of conservation of the vector current and evident inconsistency with unitary of the Cabibbo-Kobayashi-Maskawa matrix. This paper pursues and elaborates the earlier suggestion that, in these unsatisfactory circumstances, the best procedure is to look to the experimental data themselves to determine and eliminate the mismatch by appropriate extrapolation to Z approx 0 where the mismatch falls away. This is done: (i) without any prior correction for misma...

  10. Chromosome duplication in Brachiaria (A. Rich. Stapf allows intraspecific crosses

    Directory of Open Access Journals (Sweden)

    Carine Simioni

    2009-01-01

    Full Text Available Brachiaria decumbens cv. Basilisk is the single most important forage grass used for pastures in the tropics.Breeding to produce improved cultivars has been impossible until now due to the lack of compatible sexual ecotypes. Thispaper reports the success of somatic chromosome duplication of sexually reproducing diploid plants of B. decumbens and ofa diploid hybrid between B. decumbens and B. brizantha, which should allow intraspecific crosses with natural apomictictetraploid accessions of either species. Polyploidization was induced in explants cultured in vitro on a medium supplementedwith colchicine at 0.01% for 48 hours, transferred to the same medium without colchicine until shoot regeneration occurred.Five sexual tetraploid plants (3.9% of plants recovered were obtained. Crosses with apomictic cultivars recovered 14 seeds.The novel sexual tetraploids generated were unique and represented a major breakthrough in breeding B. decumbens toobtain superior hybrids.

  11. Short peptides allowing preferential detection of Candida albicans hyphae.

    Science.gov (United States)

    Kaba, Hani E J; Pölderl, Antonia; Bilitewski, Ursula

    2015-09-01

    Whereas the detection of pathogens via recognition of surface structures by specific antibodies and various types of antibody mimics is frequently described, the applicability of short linear peptides as sensor molecules or diagnostic tools is less well-known. We selected peptides which were previously reported to bind to recombinant S. cerevisiae cells, expressing members of the C. albicans Agglutinin-Like-Sequence (ALS) cell wall protein family. We slightly modified amino acid sequences to evaluate peptide sequence properties influencing binding to C. albicans cells. Among the selected peptides, decamer peptides with an "AP"-N-terminus were superior to shorter peptides. The new decamer peptide FBP4 stained viable C. albicans cells more efficiently in their mature hyphal form than in their yeast form. Moreover, it allowed distinction of C. albicans from other related Candida spp. and could thus be the basis for the development of a useful tool for the diagnosis of invasive candidiasis.

  12. Work with Apple's Rhapsody Operating System which Allows Simultaneous UNIX Program Development, UNIX Program Execution, and PC Application Execution

    CERN Document Server

    Summers, D; Cremaldi, L M; Sanders, D; Summers, Don; Riley, Chris; Cremaldi, Lucien; Sanders, David

    2001-01-01

    Over the past decade, UNIX workstations have provided a very powerful program development environment. However, workstations are more expensive than PCs and Macintoshes and require a system manager for day-to-day tasks such as disk backup, adding users, and setting up print queues. Native commercial software for system maintenance and "PC applications" has been lacking under UNIX. Apple's new Rhapsody operating system puts the current MacOS on a NeXT UNIX foundation and adds an enhanced NeXTSTEP object oriented development environment called Yellow Box. Rhapsody simultaneously runs UNIX and commercial Macintosh applications such as word processing or spreadsheets. Thus a UNIX detector Monte Carlo can run for days in the background at the same time as a commercial word processing program. And commercial programs such as Dantz Retrospect are being made available to make disk backup easy under Rhapsody. Apple has announced that in 1999 they intend to be running Rhapsody, or MacOS X as it will be called in the co...

  13. Carbon nanohorns allow acceleration of osteoblast differentiation via macrophage activation

    Science.gov (United States)

    Hirata, Eri; Miyako, Eijiro; Hanagata, Nobutaka; Ushijima, Natsumi; Sakaguchi, Norihito; Russier, Julie; Yudasaka, Masako; Iijima, Sumio; Bianco, Alberto; Yokoyama, Atsuro

    2016-07-01

    Carbon nanohorns (CNHs), formed by a rolled graphene structure and terminating in a cone, are promising nanomaterials for the development of a variety of biological applications. Here we demonstrate that alkaline phosphatase activity is dramatically increased by coculture of human monocyte derived macrophages (hMDMs) and human mesenchymal stem cells (hMSCs) in the presence of CNHs. CNHs were mainly localized in the lysosome of macrophages more than in hMSCs during coculturing. At the same time, the amount of Oncostatin M (OSM) in the supernatant was also increased during incubation with CNHs. Oncostatin M (OSM) from activated macrophage has been reported to induce osteoblast differentiation and matrix mineralization through STAT3. These results suggest that the macrophages engulfed CNHs and accelerated the differentiation of mesenchymal stem cells into the osteoblast via OSM release. We expect that the proof-of-concept on the osteoblast differentiation capacity by CNHs will allow future studies focused on CNHs as ideal therapeutic materials for bone regeneration.Carbon nanohorns (CNHs), formed by a rolled graphene structure and terminating in a cone, are promising nanomaterials for the development of a variety of biological applications. Here we demonstrate that alkaline phosphatase activity is dramatically increased by coculture of human monocyte derived macrophages (hMDMs) and human mesenchymal stem cells (hMSCs) in the presence of CNHs. CNHs were mainly localized in the lysosome of macrophages more than in hMSCs during coculturing. At the same time, the amount of Oncostatin M (OSM) in the supernatant was also increased during incubation with CNHs. Oncostatin M (OSM) from activated macrophage has been reported to induce osteoblast differentiation and matrix mineralization through STAT3. These results suggest that the macrophages engulfed CNHs and accelerated the differentiation of mesenchymal stem cells into the osteoblast via OSM release. We expect that the

  14. Spatial capture-recapture models allowing Markovian transience or dispersal

    Science.gov (United States)

    Royle, J. Andrew; Fuller, Angela K.; Sutherland, Chris

    2016-01-01

    Spatial capture–recapture (SCR) models are a relatively recent development in quantitative ecology, and they are becoming widely used to model density in studies of animal populations using camera traps, DNA sampling and other methods which produce spatially explicit individual encounter information. One of the core assumptions of SCR models is that individuals possess home ranges that are spatially stationary during the sampling period. For many species, this assumption is unlikely to be met and, even for species that are typically territorial, individuals may disperse or exhibit transience at some life stages. In this paper we first conduct a simulation study to evaluate the robustness of estimators of density under ordinary SCR models when dispersal or transience is present in the population. Then, using both simulated and real data, we demonstrate that such models can easily be described in the BUGS language providing a practical framework for their analysis, which allows us to evaluate movement dynamics of species using capture–recapture data. We find that while estimators of density are extremely robust, even to pathological levels of movement (e.g., complete transience), the estimator of the spatial scale parameter of the encounter probability model is confounded with the dispersal/transience scale parameter. Thus, use of ordinary SCR models to make inferences about density is feasible, but interpretation of SCR model parameters in relation to movement should be avoided. Instead, when movement dynamics are of interest, such dynamics should be parameterized explicitly in the model.

  15. Photochemical Microscale Electrophoresis Allows Fast Quantification of Biomolecule Binding.

    Science.gov (United States)

    Möller, Friederike M; Kieß, Michael; Braun, Dieter

    2016-04-27

    Intricate spatiotemporal patterns emerge when chemical reactions couple to physical transport. We induce electrophoretic transport by a confined photochemical reaction and use it to infer the binding strength of a second, biomolecular binding reaction under physiological conditions. To this end, we use the photoactive compound 2-nitrobenzaldehyde, which releases a proton upon 375 nm irradiation. The charged photoproducts locally perturb electroneutrality due to differential diffusion, giving rise to an electric potential Φ in the 100 μV range on the micrometer scale. Electrophoresis of biomolecules in this field is counterbalanced by back-diffusion within seconds. The biomolecule concentration is measured by fluorescence and settles proportionally to exp(-μ/D Φ). Typically, binding alters either the diffusion coefficient D or the electrophoretic mobility μ. Hence, the local biomolecule fluorescence directly reflects the binding state. A fit to the law of mass action reveals the dissociation constant of the binding reaction. We apply this approach to quantify the binding of the aptamer TBA15 to its protein target human-α-thrombin and to probe the hybridization of DNA. Dissociation constants in the nanomolar regime were determined and match both results in literature and in control experiments using microscale thermophoresis. As our approach is all-optical, isothermal and requires only nanoliter volumes at nanomolar concentrations, it will allow for the fast screening of biomolecule binding in low volume multiwell formats.

  16. Credit financing for deteriorating imperfect quality items with allowable shortages

    Directory of Open Access Journals (Sweden)

    Aditi Khanna

    2016-01-01

    Full Text Available The outset of new technologies, systems and applications in manufacturing sector has no doubt lighten up our workload, yet the chance causes of variation in production system cannot be eliminated completely. Every produced/ordered lot may have some fraction of defectives which may vary from process to process. In addition the situation is more susceptible when the items are deteriorating in nature. However, the defective items can be secluded from the good quality lot through a careful inspection process. Thus, a screening process is obligatory in today’s technology driven industry which has the customer satisfaction as its only motto. Moreover, in order to survive in the current global markets, credit financing has been proven a very influential promotional tool to attract new customers and a good inducement policy for the retailers. Keeping this scenario in mind, the present paper investigates an inventory model for a retailer dealing with imperfect quality deteriorating items under permissible delay in payments. Shortages are allowed and fully backlogged. This model jointly optimizes the order quantity and shortages by maximizing the expected total profit. A mathematical model is developed to depict this scenario. Results have been validated with the help of numerical example. Comprehensive sensitivity analysis has also been presented.

  17. Quasi-Newton Method for Optimal Blank Allowance Balancing

    Institute of Scientific and Technical Information of China (English)

    CHEN Manyi

    2006-01-01

    A balancing technique for casting or forging parts to be machined is presented in this paper. It allows an optimal part setup to make sure that no shortage of material (undercut) will occur during machining. Particularly in the heavy part industry, where the resulting casting size and shape may deviate from expectations, the balancing process discovers whether or not the design model is totally enclosed in the actual part to be machined. The alignment is an iterative process involving nonlinear constrained optimization, which forces data points to lie outside the nominal model under a specific order of priority. Newton methods for non-linear numerical minimization are rarely applied to this problem because of the high cost of computing. In this paper, Newton methods are applied to the balancing of blank part. The aforesaid algorithm is demonstrated in term of a marine propeller blade, and result shows that The Newton methods are more efficient and accurate than those implemented in past research and have distinct advantages compared to the registration methods widely used today.

  18. Structural determinants allowing endolysosomal sorting and degradation of endosomal GTPases.

    Science.gov (United States)

    Valero, Ruth A; Oeste, Clara L; Stamatakis, Konstantinos; Ramos, Irene; Herrera, Mónica; Boya, Patricia; Pérez-Sala, Dolores

    2010-09-01

    Rapid control of protein degradation is usually achieved through the ubiquitin-proteasome pathway. We recently found that the short-lived GTPase RhoB is degraded in lysosomes. Moreover, the fusion of the RhoB C-terminal sequence CINCCKVL, containing the isoprenylation and palmitoylation sites, to other proteins directs their sorting into multivesicular bodies (MVBs) and rapid lysosomal degradation. Here, we show that this process is highly specific for RhoB. Alteration of late endosome lipid dynamics produced the accumulation of RhoB, but not of other endosomal GTPases, including Rab5, Rab7, Rab9 or Rab11, into enlarged MVB. Other isoprenylated and bipalmitoylated GTPases, such as H-Ras, Rap2A, Rap2B and TC10, were not accumulated into MVB and were stable. Remarkably, although TC10, which is highly homologous to RhoB, was stable, a sequence derived from its C-terminus (CINCCLIT) elicited MVB sorting and degradation of a green fluorescent protein (GFP)-chimeric protein. This led us to identify a cluster of basic amino acids (KKH) in the TC10 hypervariable region, constituting a secondary signal potentially involved in electrostatic interactions with membrane lipids. Mutation of this cluster allowed TC10 MVB sorting and degradation, whereas inserting it into RhoB hypervariable region rescued this protein from its lysosomal degradation pathway. These findings define a highly specific structural module for entering the MVB pathway and rapid lysosomal degradation.

  19. Extreme alien light allows survival of terrestrial bacteria

    Science.gov (United States)

    Johnson, Neil; Zhao, Guannan; Caycedo, Felipe; Manrique, Pedro; Qi, Hong; Rodriguez, Ferney; Quiroga, Luis

    2013-07-01

    Photosynthetic organisms provide a crucial coupling between the Sun's energy and metabolic processes supporting life on Earth. Searches for extraterrestrial life focus on seeking planets with similar incident light intensities and environments. However the impact of abnormal photon arrival times has not been considered. Here we present the counterintuitive result that broad classes of extreme alien light could support terrestrial bacterial life whereas sources more similar to our Sun might not. Our detailed microscopic model uses state-of-the-art empirical inputs including Atomic Force Microscopy (AFM) images. It predicts a highly nonlinear survivability for the basic lifeform Rsp. Photometricum whereby toxic photon feeds get converted into a benign metabolic energy supply by an interplay between the membrane's spatial structure and temporal excitation processes. More generally, our work suggests a new handle for manipulating terrestrial photosynthesis using currently-available extreme value statistics photon sources.

  20. A highly precise and portable genome engineering method allows comparison of mutational effects across bacterial species.

    Science.gov (United States)

    Nyerges, Ákos; Csörgő, Bálint; Nagy, István; Bálint, Balázs; Bihari, Péter; Lázár, Viktória; Apjok, Gábor; Umenhoffer, Kinga; Bogos, Balázs; Pósfai, György; Pál, Csaba

    2016-03-01

    Currently available tools for multiplex bacterial genome engineering are optimized for a few laboratory model strains, demand extensive prior modification of the host strain, and lead to the accumulation of numerous off-target modifications. Building on prior development of multiplex automated genome engineering (MAGE), our work addresses these problems in a single framework. Using a dominant-negative mutant protein of the methyl-directed mismatch repair (MMR) system, we achieved a transient suppression of DNA repair in Escherichia coli, which is necessary for efficient oligonucleotide integration. By integrating all necessary components into a broad-host vector, we developed a new workflow we term pORTMAGE. It allows efficient modification of multiple loci, without any observable off-target mutagenesis and prior modification of the host genome. Because of the conserved nature of the bacterial MMR system, pORTMAGE simultaneously allows genome editing and mutant library generation in other biotechnologically and clinically relevant bacterial species. Finally, we applied pORTMAGE to study a set of antibiotic resistance-conferring mutations in Salmonella enterica and E. coli. Despite over 100 million y of divergence between the two species, mutational effects remained generally conserved. In sum, a single transformation of a pORTMAGE plasmid allows bacterial species of interest to become an efficient host for genome engineering. These advances pave the way toward biotechnological and therapeutic applications. Finally, pORTMAGE allows systematic comparison of mutational effects and epistasis across a wide range of bacterial species.

  1. Role Resources and Work-Family Enrichment: The Role of Work Engagement

    Science.gov (United States)

    Siu, Oi-ling; Lu, Jia-fang; Brough, Paula; Lu, Chang-qin; Bakker, Arnold B.; Kalliath, Thomas; O'Driscoll, Michael; Phillips, David R.; Chen, Wei-qing; Lo, Danny; Sit, Cindy; Shi, Kan

    2010-01-01

    This article proposes a theoretical model of work-family enrichment and tests the mediating role of work engagement. The inclusion of work engagement extends prior research on work-family interface, and allows for examination of the effects of role resources (job resources, family support) on work-family enrichment. A two-wave survey was conducted…

  2. Reminder: extension/suppression of allowance for dependent children aged 20 to 25

    CERN Document Server

    2013-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2013/2014 school year), for whom an allowance for dependent children is currently paid, are invited to provide the Education Fees service with a SCHOOL CERTIFICATE.   Unless we receive, by October 31, 2013 at the latest, a school certificate or similar written proof (contract of work placement, sandwich course or apprenticeship) covering your child / children for the school year 2013/2014, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance at the appropriate date and retroactively if necessary.   Education fees service HR/CB-B Mailbox C20000 schoolfees.service@cern.ch Tel.: 72862 / 71421

  3. Reminder - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2011-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2011/2012 school year), for whom an allowance for dependent children is currently paid, are invited to provide the Education Fees Service with a: SCHOOL CERTIFICATE Unless we receive, by 31 October 2011 at the latest, a school certificate or similar written proof (contract of work placement, sandwich courses or apprenticeship) covering your child / children for the school year 2011/2012, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance at the appropriate date and retroactively if necessary. Education Fees Service Mailbox C20000 schoolfees.service@cern.ch Tel. 72862 / 71421

  4. REMINDER - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2010-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2010/2011 school year), for whom an allowance for dependent children is currently paid, are invited to provide the Education Fees Service with a: SCHOOL CERTIFICATE Unless we receive, by 31 October 2010 at the latest, a school certificate or similar written proof (work placement contract, evidence of sandwich courses or apprenticeship) covering your child / children for the school year 2010/2011, we will be obliged to stop payment of the allowance for dependent children as well as membership of the health insurance scheme at the appropriate date, retroactively if necessary. Education Fees Service HR/SPS-SER Tel. 72862 / 71421

  5. REMINDER - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2010-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2010/2011 school year), for whom an allowance for dependent children is currently paid, are invited to provide the Education fees service with a: SCHOOL CERTIFICATE Unless we receive, by October 31, 2010 at the latest, a school certificate or similar written proof (contract of work placement, sandwich courses or apprenticeship) covering your child / children for the school year 2010/2011, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance at the appropriate date and retroactively if necessary. Education fees service HR/SPS-SER Tel. 72862 / 71421

  6. REMINDER: Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    2012-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2012/2013 school year), for whom an allowance for dependent children is currently paid, are invited to provide the Education fees service with a   SCHOOL CERTIFICATE.   Unless we receive, by October 31, 2012 at the latest, a school certificate or similar written proof (contract of work placement, sandwich courses or apprenticeship) covering your child / children for the school year 2012/2013, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance at the appropriate date and retroactively if necessary.   Education fees service HR/CB-B Mailbox C20000 schoolfees.service@cern.ch Tel. 72862 / 71421

  7. Reminder - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2009-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2009/2010 school year), for whom a dependent child’s allowance is currently paid, are invited to provide the Education Fees service with a: SCHOOL CERTIFICATE Unless we receive, by October 31, 2009 at the latest, a school certificate or similar written proof (contract of work placement, sandwich course or apprenticeship) covering your child / children for the 2009/2010 school year, we will be obliged to stop payment of the dependent child’s allowance as well as membership of the health insurance scheme at the appropriate date, retroactively if necessary. Education Fees service (33-1-017) HR Department - Tel. 72862

  8. Final reminder - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2007-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2007/2008 school year), for whom an allowance for dependent children is paid, must provide the School fees service as soon as possible with a: SCHOOL CERTIFICATE Unless we receive, by November 30, 2007 at the latest, a school certificate or similar written proof (contract of work placement, sandwich courses or apprenticeship) covering your child / children for the school year 2007/2008, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance retroactively as of July 1, 2007. School fees service (33-1-017) HR/SPS-SER Tel. 72862

  9. REMINDER - extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2008-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2008/2009 school year), for whom an allowance for dependent children is paid, must provide the School fees service with a: SCHOOL CERTIFICATE Unless we receive, by 31 October 2008 at the latest, a school certificate or similar written proof (contract of work placement, sandwich courses or apprenticeship) covering your child / children for the school year 2008/2009, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance retroactively as of 1 July 2008. School fees service (33-1-017) HR/SPS-SER Tel. 72862

  10. Final reminder - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2007-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2007/2008 school year), for whom an allowance for dependent children is paid, must provide the School Fees service as soon as possible with a: SCHOOL CERTIFICATE Unless we receive, by November 30, 2007 at the latest, a school certificate or similar written proof (contract of work placement, sandwich courses or apprenticeship) covering your child / children for the school year 2007/2008, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance scheme retroactively as of 1 July 2007. School Fees service (33-1-017) HR/SPS-SER Tel. 72862

  11. REMINDER - Extension/suppression of allowance for dependent children aged 20 to 25

    CERN Multimedia

    HR Department

    2008-01-01

    Members of the personnel with dependent children aged 20 to 25 (or reaching 20 during the 2008/2009 school year), for whom an allowance for dependent children is paid, must provide the School Fees service with a: SCHOOL CERTIFICATE Unless we receive, by 31 October, 2008 at the latest, a school certificate or similar written proof (contract of work placement, sandwich course or apprenticeship) covering your child / children for the school year 2008/2009, we will be obliged to stop payment of the allowance for dependent children as well as affiliation to the health insurance scheme retroactively as of1st July 2008. School fees service (33-1-017) HR/SPS-SER Tel. 72862

  12. Investigation on the presence of sulphites in fresh meat preparations: estimation of an allowable maximum limit.

    Science.gov (United States)

    Iammarino, Marco; Di Taranto, Aurelia; Muscarella, Marilena

    2012-02-01

    Sulphiting agents are commonly used food additives. They are not allowed in fresh meat preparations. In this work, 2250 fresh meat samples were analysed to establish the maximum concentration of sulphites that can be considered as "natural" and therefore be admitted in fresh meat preparations. The analyses were carried out by an optimised Monier-Williams Method and the positive samples confirmed by ion chromatography. Sulphite concentrations higher than the screening method LOQ (10.0 mg · kg(-1)) were found in 100 samples. Concentrations higher than 76.6 mg · kg(-1), attributable to sulphiting agent addition, were registered in 40 samples. Concentrations lower than 41.3 mg · kg(-1) were registered in 60 samples. Taking into account the distribution of sulphite concentrations obtained, it is plausible to estimate a maximum allowable limit of 40.0 mg · kg(-1) (expressed as SO(2)). Below this value the samples can be considered as "compliant".

  13. Method to Determine Maximum Allowable Sinterable Silver Interconnect Size

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, A. A.; Modugno, M. C.; Waters, S. B.; DeVoto, D. J.; Paret, P. P.

    2016-05-01

    The use of sintered-silver for large-area interconnection is attractive for some large-area bonding applications in power electronics such as the bonding of metal-clad, electrically-insulating substrates to heat sinks. Arrays of different pad sizes and pad shapes have been considered for such large area bonding; however, rather than arbitrarily choosing their size, it is desirable to use the largest size possible where the onset of interconnect delamination does not occur. If that is achieved, then sintered-silver's high thermal and electrical conductivities can be fully taken advantage of. Toward achieving this, a simple and inexpensive proof test is described to identify the largest achievable interconnect size with sinterable silver. The method's objective is to purposely initiate failure or delamination. Copper and invar (a ferrous-nickel alloy whose coefficient of thermal expansion (CTE) is similar to that of silicon or silicon carbide) disks were used in this study and sinterable silver was used to bond them. As a consequence of the method's execution, delamination occurred in some samples during cooling from the 250 degrees C sintering temperature to room temperature and bonding temperature and from thermal cycling in others. These occurrences and their interpretations highlight the method's utility, and the herein described results are used to speculate how sintered-silver bonding will work with other material combinations.

  14. Estimating net survival: the importance of allowing for informative censoring.

    Science.gov (United States)

    Danieli, Coraline; Remontet, Laurent; Bossard, Nadine; Roche, Laurent; Belot, Aurélien

    2012-04-13

    Net survival, the one that would be observed if cancer were the only cause of death, is the most appropriate indicator to compare cancer mortality between areas or countries. Several parametric and non-parametric methods have been developed to estimate net survival, particularly when the cause of death is unknown. These methods are based either on the relative survival ratio or on the additive excess hazard model, the latter using the general population mortality hazard to estimate the excess mortality hazard (the hazard related to net survival). The present work used simulations to compare estimator abilities to estimate net survival in different settings such as the presence/absence of an age effect on the excess mortality hazard or on the potential time of follow-up, knowing that this covariate has an effect on the general population mortality hazard too. It showed that when age affected the excess mortality hazard, most estimators, including specific survival, were biased. Only two estimators were appropriate to estimate net survival. The first is based on a multivariable excess hazard model that includes age as covariate. The second is non-parametric and is based on the inverse probability weighting. These estimators take differently into account the informative censoring induced by the expected mortality process. The former offers great flexibility whereas the latter requires neither the assumption of a specific distribution nor a model-building strategy. Because of its simplicity and availability in commonly used software, the nonparametric estimator should be considered by cancer registries for population-based studies.

  15. A novel integrated renewable energy system modelling approach, allowing fast FPGA controller prototyping

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Ruiz, Alberto Parera; Cirstea, Marcian

    2008-01-01

    The paper describes a new holistic approach to the modeling of integrated renewable energy systems. The method is using the DK5 modeling/design environment from Celoxica and is based on the new Handel-C programming language. The goal of the work carried out was to achieve a combined model...... of a photovoltaic energy system and a wind power system, which would allow an optimized holistic digital control system design, followed by rapid prototyping of the controller into a single Field Programmable Gate Array (FPGA). Initially, the system was simulated using Matlab / Simulink, to create a reference...

  16. Work team

    Directory of Open Access Journals (Sweden)

    RBE Editorial

    2016-06-01

    Full Text Available Work Team 2016 (Jan-Jul1. Editorial TeamChief-editorsBayardo Bapstista Torres, Instituto de Química (USP, BrasilEduardo Galembeck, Depto. Bioquímica, Instituto de Biologia, Universidade de Campinas (Unicamp, Brasil Co-editorsGabriel Gerber Hornink, Depto. Bioquímica, Instituto de Ciências Biomédicas, Universidade - Federal de Alfenas (Unifal-MG, BrasilVera Maria Treis Trindade, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul (UFRGS, Brasil Editorial BoardAdriana Cassina, Department of Biochemistry, Facultad de Medicina, Universidad de la República, UruguayAngel Herráez, Departamento de Bioquímica y Biología molecular, Universidad de Alcalá de Henares, Madrid, SpainAndré Amaral Gonçalves Bianco, Universidade Federal de São Paulo (Unifesp, BrasilDenise Vaz de Macedo, Depto. Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas (Unicamp, BrasilEneida de Paula, Depto. Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas (Unicamp, BrasilJose Antonio Martinez Oyanedel, Universidad de Concepción, ChileJosep Maria Fernández Novell, Department of Molecular Biology & Biochemistry, Universitat de Barcelona, SpainLeila Maria Beltramini, Instituto de Física de São Carlos, Universidade Estadual de São Paulo (USP, BrasilManuel João da Costa, Escola de Ciências da Saúde, Universidade do Minho, PortugalMaria Lucia Bianconi, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro (UFRJ, BrasilMaría Noel Alvarez, Department of Biochemistry, Facultad de Medicina, Universidad de la República, UruguayMiguel Ángel Medina Torres, Department of Molecular Biology & Biochemistry Faculty of Sciences University of Málaga, SpainNelma Regina Segnini Bossolan, Instituto de Física de São Carlos, Universidade de São Paulo (USP, BrasilPaulo De Avila Junior, Centro de Ciências Naturais e Humanas (CCNH Universidade Federal do ABC (UFABC

  17. Allowing for model error in strong constraint 4D-Var

    Science.gov (United States)

    Howes, Katherine; Lawless, Amos; Fowler, Alison

    2016-04-01

    Four dimensional variational data assimilation (4D-Var) can be used to obtain the best estimate of the initial conditions of an environmental forecasting model, namely the analysis. In practice, when the forecasting model contains errors, the analysis from the 4D-Var algorithm will be degraded to allow for errors later in the forecast window. This work focusses on improving the analysis at the initial time by allowing for the fact that the model contains error, within the context of strong constraint 4D-Var. The 4D-Var method developed acknowledges the presence of random error in the model at each time step by replacing the observation error covariance matrix with an error covariance matrix that includes both observation error and model error statistics. It is shown that this new matrix represents the correct error statistics of the innovations in the presence of model error. A method for estimating this matrix using innovation statistics, without requiring prior knowledge of the model error statistics, is presented. The method is demonstrated numerically using a non-linear chaotic system with erroneous parameter values. We show that that the new method works to reduce the analysis error covariance when compared with a standard strong constraint 4D-Var scheme. We discuss the fact that an improved analysis will not necessarily provide a better forecast.

  18. ILDG Middleware Working Group Status Report

    Energy Technology Data Exchange (ETDEWEB)

    B. Joo; W. Watson

    2004-09-01

    We report on the status of the ILDG Middleware Working Group. The Middleware Working Group was formed with the aim of designing standard middleware to allow the interoperation of the data grids of ILDG member collaborations. Details of the working group are given. In this contribution we outline the role of middleware in the ILDG, present our proposed middleware architecture and discuss our current status and future work within the working group.

  19. Tinbergen's work: Change and continuity

    NARCIS (Netherlands)

    J. Kol (Jacob); P. de Wolff

    1993-01-01

    textabstractThis article provides an overview of Tinbergen's economic writings, comprising well over 900 publications. Six broad areas have been distinguished to allow for the classification and discussion of Tinbergen's economic work. These six areas embody the change in Tinbergen's areas of

  20. Tinbergen's work: Change and continuity

    NARCIS (Netherlands)

    J. Kol (Jacob); P. de Wolff

    1993-01-01

    textabstractThis article provides an overview of Tinbergen's economic writings, comprising well over 900 publications. Six broad areas have been distinguished to allow for the classification and discussion of Tinbergen's economic work. These six areas embody the change in Tinbergen's areas of intere

  1. 30 CFR 56.18020 - Working alone.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Working alone. 56.18020 Section 56.18020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Working alone. No employee shall be assigned, or allowed, or be required to perform work alone in any...

  2. 30 CFR 57.18020 - Working alone.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Working alone. 57.18020 Section 57.18020... Surface Only § 57.18020 Working alone. No employee shall be assigned, or allowed, or be required to perform work alone in any area where hazardous conditions exist that would endanger his safety unless...

  3. 30 CFR 57.18025 - Working alone.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Working alone. 57.18025 Section 57.18025... Underground Only § 57.18025 Working alone. No employee shall be assigned, or allowed, or be required to perform work alone in any area where hazardous conditions exist that would endanger his safety unless...

  4. Comics – a Method that Allows Boys Deeper Experience of Children’s Literature

    Directory of Open Access Journals (Sweden)

    Maja Kerneza

    2014-06-01

    Full Text Available In the acquisition of reading skills girls are more successful than boys. As a method of interpretation comics could allow boys a deeper perception, understanding and evaluation of youth literary texts, and help them to express their literary perception experience. The main research method is case study with a number of linguistic motivations used. After getting acquainted with the comics, the students applied new knowledge to detect textual information embedded in stage directions, and expanded their literary worlds by converting texts into comic form. The research is based on qualitative research methods of literary didactic research. Boys’ deficits were successfully compensated – in some cases they were even more successful than girls, and the mehod of work also suited girls.

  5. EU Emission Allowances and the stock market Evidence from the electricity industry

    Energy Technology Data Exchange (ETDEWEB)

    Oberndorfer, Ulrich [Centre for European Economic Research (ZEW) P.O. Box 103443 68034 Mannheim (Germany)

    2009-02-15

    This paper constitutes - to our best knowledge - the first econometric analysis on stock market effects of the EU Emission Trading Scheme (EU ETS). Our results suggest that EU Emission Allowance (EUA) price developments matter to the stock performance of electricity firms: EUA price changes and stock returns of the most important European electricity corporations are shown to be positively related. This effect does not work asymmetrically, so that stock markets do not seem to react differently to EUA appreciations in comparison to depreciations. The carbon market effect is shown to be both time- and country-specific: It is particularly strong for the period of EUA market shock in early 2006, and differs with respect to the countries where the electricity corporations analysed are headquartered. Stock market reactions to EUA volatility could not be shown. (author)

  6. A robust and scalable microfluidic metering method that allows protein crystal growth by free interface diffusion

    Science.gov (United States)

    Hansen, Carl L.; Skordalakes, Emmanuel; Berger, James M.; Quake, Stephen R.

    2002-12-01

    Producing robust and scalable fluid metering in a microfluidic device is a challenging problem. We developed a scheme for metering fluids on the picoliter scale that is scalable to highly integrated parallel architectures and is independent of the properties of the working fluid. We demonstrated the power of this method by fabricating and testing a microfluidic chip for rapid screening of protein crystallization conditions, a major hurdle in structural biology efforts. The chip has 480 active valves and performs 144 parallel reactions, each of which uses only 10 nl of protein sample. The properties of microfluidic mixing allow an efficient kinetic trajectory for crystallization, and the microfluidic device outperforms conventional techniques by detecting more crystallization conditions while using 2 orders of magnitude less protein sample. We demonstrate that diffraction-quality crystals may be grown and harvested from such nanoliter-volume reactions.

  7. A New Item Response Theory Model for Open-Ended Online Homework with Multiple Allowed Attempts

    CERN Document Server

    Gönülateş, Emre

    2015-01-01

    Item Response Theory (IRT) was originally developed in traditional exam settings, and it has been shown that the model does not readily transfer to formative assessment in the form of online homework. We investigate if this is mostly due to learner traits that do not become apparent in exam settings, namely random guessing due to lack of diligence or dedication, and copying work from other students or resources. Both of these traits mask the true ability of the learner, which is the only trait considered in most mainstream unidimensional IRT models. We find that indeed the introduction of these traits allows to better assess the true ability of the learners, as well as to better gauge the quality of assessment items. Correspondence of the model traits to self-reported behavior is investigated and confirmed. We find that of these two traits, copying answers has a larger influence on initial homework attempts than random guessing.

  8. A robust and scalable microfluidic metering method that allows protein crystal growth by free interface diffusion

    Science.gov (United States)

    Hansen, Carl L.; Skordalakes, Emmanuel; Berger, James M.; Quake, Stephen R.

    2002-01-01

    Producing robust and scalable fluid metering in a microfluidic device is a challenging problem. We developed a scheme for metering fluids on the picoliter scale that is scalable to highly integrated parallel architectures and is independent of the properties of the working fluid. We demonstrated the power of this method by fabricating and testing a microfluidic chip for rapid screening of protein crystallization conditions, a major hurdle in structural biology efforts. The chip has 480 active valves and performs 144 parallel reactions, each of which uses only 10 nl of protein sample. The properties of microfluidic mixing allow an efficient kinetic trajectory for crystallization, and the microfluidic device outperforms conventional techniques by detecting more crystallization conditions while using 2 orders of magnitude less protein sample. We demonstrate that diffraction-quality crystals may be grown and harvested from such nanoliter-volume reactions. PMID:12486223

  9. The Extension Of Torque Scheduler Allowing The Use Of Planning And Optimization In Grids

    Directory of Open Access Journals (Sweden)

    Vaclav Chlumsky

    2012-01-01

    Full Text Available In this work we present a major extension of the open source TORQUE Resource Manager system. We have replaced a naive scheduler provided in the TORQUE distribution with complex scheduling system that allows to plan job execution ahead and predict the behavior of the system. It is based on the application of job schedule, which represents the jobs’ execution plan. Such a functionality is very useful as the plan can be used by the users to see when and where their jobs will be executed. Moreover, created plans can be easily evaluated in order to identify possible inefficiencies. Then, repair actions can be taken immediately and the inefficiencies can be fixed, producing better schedules with respect to considered criteria.

  10. A Study on the Allowable Safety Factor of Cut-Slopes for Nuclear Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Soo; Yee, Eric [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2015-10-15

    In this study, the issues of allowable safety factor design criteria for cut-slopes in nuclear facilities is derived through case analysis, a proposed construction work slope design criteria that provides relatively detailed conditions can be applied in case of the dry season and some unclear parts of slope design criteria be modified in case of the rainy season. This safety factor can be further subdivided into two; normal and earthquake factors, a factor of 1.5 is applied for normal conditions and a factor of 1.2 is applied for seismic conditions. This safety factor takes into consideration the effect of ground water and rainfall conditions. However, no criteria for the case of cut-slope in nuclear facilities and its response to seismic conditions is clearly defined, this can cause uncertainty in design. Therefore, this paper investigates the allowable safety factor for cut-slopes in nuclear facilities, reviews conditions of both local and international cut-slope models and finally suggests an alternative method of analysis. It is expected that the new design criteria adequately ensures the stability of the cut-slope to reflect clear conditions for both the supervising and design engineers.

  11. 77 FR 71741 - Guides for Advertising Allowances and Other Merchandising Payments and Services

    Science.gov (United States)

    2012-12-04

    ... CFR Part 240 Guides for Advertising Allowances and Other Merchandising Payments and Services AGENCY... Guides for Advertising Allowances and Other Merchandising Payments and Services (``the Fred Meyer Guides... make advertising and promotional allowances or services available to all competing customers...

  12. Risk-Based Allowed Outage Time and Surveillance Test Interval Extensions for Angra 1

    Directory of Open Access Journals (Sweden)

    Sonia M. Orlando Gibelli

    2012-01-01

    Full Text Available In this work, Probabilistic Safety Assessment (PSA is used to evaluate Allowed Outage Times (AOT and Surveillance Test Intervals (STI extensions for three Angra 1 nuclear power plant safety systems. The interest in such an analysis lies on the fact that PSA comprises a risk-based tool for safety evaluation and has been increasingly applied to support both the regulatory and the operational decision-making processes. Regarding Angra 1, among other applications, PSA is meant to be an additional method that can be used by the utility to justify Technical Specification relaxation to the Brazilian regulatory body. The risk measure used in this work is the Core Damage Frequency, obtained from the Angra 1 Level 1 PSA study. AOT and STI extensions are evaluated for the Safety Injection, Service Water and Auxiliary Feedwater Systems using the SAPHIRE code. In order to compensate for the risk increase caused by the extensions, compensatory measures as (1 test of redundant train prior to entering maintenance and (2 staggered test strategy are proposed. Results have shown that the proposed AOT extensions are acceptable for two of the systems with the implementation of compensatory measures whereas STI extensions are acceptable for all three systems.

  13. Working Together: Google Apps Goes to School

    Science.gov (United States)

    Oishi, Lindsay

    2007-01-01

    Online collaboration and project-management tools allow people to work together without being in the same place at the same time. However, that is not all, Google Docs & Spreadsheets, for example, allows the creation of documents and spreadsheets just like in Microsoft Word and Excel, but with more collaborative capacity. Google Calendar lets…

  14. Balancing Machine Work, Comfort Work, and Sentimental Work

    DEFF Research Database (Denmark)

    Pedersen, Maria Ie; Hansen, Magnus; Hertzum, Morten

    2011-01-01

    and attention. We investigate ambulance care in three of Denmark’s five healthcare regions, which staff ambulances with emergency medical technicians, paramedics, and physicians. Using the concept of illness trajectory we analyse how the ambulance crews balance machine work, which involves continuously...... work, but also that this has negative consequences. Equipment for use in ambulances should aim at supporting the ambulance crews in competently and dynamically balancing the different types of work and should, consequently, avoid binding the crew’s attention for unbroken periods of time....... monitoring the equipment, comfort work, which is actions taken to relieve the pain or discomfort of the patient, and sentimental work, which is care for the patient’s physical and mental well-being, often verbal in nature. The analysis shows that comfort and sentimental work often takes priority over machine...

  15. 41 CFR 302-5.2 - What is the purpose of the househunting trip expenses allowance?

    Science.gov (United States)

    2010-07-01

    ... the househunting trip expenses allowance? 302-5.2 Section 302-5.2 Public Contracts and Property...) ALLOWANCES FOR SUBSISTENCE AND TRANSPORTATION EXPENSES 5-ALLOWANCE FOR HOUSEHUNTING TRIP EXPENSES Employee's Allowance For Househunting Trip Expenses § 302-5.2 What is the purpose of the househunting trip expenses...

  16. 41 CFR 302-5.100 - How should we administer the househunting trip expenses allowance?

    Science.gov (United States)

    2010-07-01

    ... the househunting trip expenses allowance? 302-5.100 Section 302-5.100 Public Contracts and Property...) ALLOWANCES FOR SUBSISTENCE AND TRANSPORTATION EXPENSES 5-ALLOWANCE FOR HOUSEHUNTING TRIP EXPENSES Agency Responsibilities § 302-5.100 How should we administer the househunting trip expenses allowance? You should...

  17. 41 CFR 302-5.4 - Who is not eligible for a househunting trip expenses allowance?

    Science.gov (United States)

    2010-07-01

    ... a househunting trip expenses allowance? 302-5.4 Section 302-5.4 Public Contracts and Property...) ALLOWANCES FOR SUBSISTENCE AND TRANSPORTATION EXPENSES 5-ALLOWANCE FOR HOUSEHUNTING TRIP EXPENSES Employee's Allowance For Househunting Trip Expenses § 302-5.4 Who is not eligible for a househunting trip expenses...

  18. 41 CFR 302-5.3 - Am I eligible for a househunting trip expenses allowance?

    Science.gov (United States)

    2010-07-01

    ... househunting trip expenses allowance? 302-5.3 Section 302-5.3 Public Contracts and Property Management Federal... SUBSISTENCE AND TRANSPORTATION EXPENSES 5-ALLOWANCE FOR HOUSEHUNTING TRIP EXPENSES Employee's Allowance For Househunting Trip Expenses § 302-5.3 Am I eligible for a househunting trip expenses allowance? You are eligible...

  19. 26 CFR 1.167(a)-10 - When depreciation deduction is allowable.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 2 2010-04-01 2010-04-01 false When depreciation deduction is allowable. 1.167... Corporations § 1.167(a)-10 When depreciation deduction is allowable. (a) A taxpayer should deduct the proper depreciation allowance each year and may not increase his depreciation allowances in later years by reason...

  20. Returning to Work

    Science.gov (United States)

    ... when work tasks can be upgraded to full duty. What can a person returning to work do? ... to-work program that includes transitional work for employees is an important component of a company's healthy ...

  1. Meaningful work, work engagement and organisational commitment

    Directory of Open Access Journals (Sweden)

    Madelyn Geldenhuys

    2014-02-01

    Full Text Available Orientation: Meaningful work can yield benefits for organisations and lead to positive work outcomes such as satisfied, engaged and committed employees, individual and organisational fulfilment, productivity, retention and loyalty.Research purpose: The aim of the study was to investigate the relationships amongst psychological meaningfulness, work engagement and organisational commitment and to test for a possible mediation effect of work engagement on the relationship between psychological meaningfulness and organisational commitment.Motivation for the study: Managers have to rethink ways of improving productivity and performance at work, due to the diverse, and in some instances escalating, needs of employees (e.g. financial support to uphold their interest in and enjoyment of working.Research approach, design and method: A quantitative approach was employed to gather the data for the study, utilising a cross-sectional survey design. The sample (n = 415 consisted of working employees from various companies and positions in Gauteng, South Africa.Main findings: The results confirmed a positive relationship between psychological meaningfulness, work engagement and organisational commitment. Further, psychological meaningfulness predicts work engagement, whilst psychological meaningfulness and work engagement predict organisational commitment.Practical/managerial implications: Employers identifying their employees’ commitment patterns and mapping out strategies for enhancing those that are relevant to organisational goals will yield positive work outcomes (e.g. employees who are creative, seek growth or challenges for themselves.Contribution/value-add: This study contributes to the literature through highlighting the impact that meaningful work has on sustaining employee commitment to the organisation.

  2. New ways of working and work engagement

    NARCIS (Netherlands)

    Baudewijns, C.; Gerards, R.; de Grip, A.

    2015-01-01

    This article investigates whether New Ways of Working (NWW) are related to employee work engagement in the Netherlands. We test our hypotheses using a sample of 656 employees from 14 industry sectors and 12 occupational fields. Our study reveals that three facets of NWW positively affect work

  3. [Investigating work, age, health and work participation in the ageing work force in Germany].

    Science.gov (United States)

    Ebener, M; Hasselhorn, H M

    2015-04-01

    Working life in Germany is changing. The work force is ageing and the number of people available to the labour market will - from now on - shrink considerably. Prospectively, people will have to work longer; but still today, most people leave employment long before reaching official retirement age. What are the reasons for this? In this report, a conceptual framework and the German lidA Cohort Study are presented. The "lidA conceptual framework on work, age, health and work participation" visualises determinants of employment (11 "domains") in higher working age, e. g., "work", "health", "social status" and "life style". The framework reveals 4 key characteristics of withdrawal from work: leaving working life is the result of an interplay of different domains (complexity); (early) retirement is a process with in part early determinants in the life course (processual character); retirement has a strong individual component (individuality); retirement is embedded in a strong structural frame (structure). On the basis of this framework, the "lidA Cohort Study on work, age, health and work participation" (www.lida-studie.de) investigates long-term effects of work on health and work participation in the ageing work force in Germany. It is the only large study in Germany operationalising the concept of employability in a broad interdisciplinary approach. Employees subject to social security and born in 1959 or in 1965 will be interviewed (CAPI) every 3 years (N[wave 1]=6 585, N[wave 2]=4 244) and their data will be linked (where consented) with social security data covering employment history and with health insurance data. The study design ("Schaie's most efficient design") allows for a tri-factor model that isolates the impact of age, cohort and time. In 2014, the second wave was completed. In the coming years lidA will analyse the association of work, health and work participation, and identify age as well as generation differences. lidA will investigate the

  4. Nontraditional work schedules for pharmacists.

    Science.gov (United States)

    Mahaney, Lynnae; Sanborn, Michael; Alexander, Emily

    2008-11-15

    Nontraditional work schedules for pharmacists at three institutions are described. The demand for pharmacists and health care in general continues to increase, yet significant material changes are occurring in the pharmacy work force. These changing demographics, coupled with historical vacancy rates and turnover trends for pharmacy staff, require an increased emphasis on workplace changes that can improve staff recruitment and retention. At William S. Middleton Memorial Veterans Affairs Hospital in Madison, Wisconsin, creative pharmacist work schedules and roles are now mainstays to the recruitment and retention of staff. The major challenge that such scheduling presents is the 8 hours needed to prepare a six-week schedule. Baylor Medical Center at Grapevine in Dallas, Texas, has a total of 45 pharmacy employees, and slightly less than half of the 24.5 full-time-equivalent staff work full-time, with most preferring to work one, two, or three days per week. As long as the coverage needs of the facility are met, Envision Telepharmacy in Alpine, Texas, allows almost any scheduling arrangement preferred by individual pharmacists or the pharmacist group covering the facility. Staffing involves a great variety of shift lengths and intervals, with shifts ranging from 2 to 10 hours. Pharmacy leaders must be increasingly aware of opportunities to provide staff with unique scheduling and operational enhancements that can provide for a better work-life balance. Compressed workweeks, job-sharing, and team scheduling were the most common types of alternative work schedules implemented at three different institutions.

  5. Thermodynamic work from operational principles

    Science.gov (United States)

    Gallego, R.; Eisert, J.; Wilming, H.

    2016-10-01

    In recent years we have witnessed a concentrated effort to make sense of thermodynamics for small-scale systems. One of the main difficulties is to capture a suitable notion of work that models realistically the purpose of quantum machines, in an analogous way to the role played, for macroscopic machines, by the energy stored in the idealisation of a lifted weight. Despite several attempts to resolve this issue by putting forward specific models, these are far from realistically capturing the transitions that a quantum machine is expected to perform. In this work, we adopt a novel strategy by considering arbitrary kinds of systems that one can attach to a quantum thermal machine and defining work quantifiers. These are functions that measure the value of a transition and generalise the concept of work beyond those models familiar from phenomenological thermodynamics. We do so by imposing simple operational axioms that any reasonable work quantifier must fulfil and by deriving from them stringent mathematical condition with a clear physical interpretation. Our approach allows us to derive much of the structure of the theory of thermodynamics without taking the definition of work as a primitive. We can derive, for any work quantifier, a quantitative second law in the sense of bounding the work that can be performed using some non-equilibrium resource by the work that is needed to create it. We also discuss in detail the role of reversibility and correlations in connection with the second law. Furthermore, we recover the usual identification of work with energy in degrees of freedom with vanishing entropy as a particular case of our formalism. Our mathematical results can be formulated abstractly and are general enough to carry over to other resource theories than quantum thermodynamics.

  6. Frequency tuning allows flow direction control in microfluidic networks with passive features.

    Science.gov (United States)

    Jain, Rahil; Lutz, Barry

    2017-05-02

    Frequency tuning has emerged as an attractive alternative to conventional pumping techniques in microfluidics. Oscillating (AC) flow driven through a passive valve can be rectified to create steady (DC) flow, and tuning the excitation frequency to the characteristic (resonance) frequency of the underlying microfluidic network allows control of flow magnitude using simple hardware, such as an on-chip piezo buzzer. In this paper, we report that frequency tuning can also be used to control the direction (forward or backward) of the rectified DC flow in a single device. Initially, we observed that certain devices provided DC flow in the "forward" direction expected from previous work with a similar valve geometry, and the maximum DC flow occurred at the same frequency as a prominent peak in the AC flow magnitude, as expected. However, devices of a slightly different geometry provided the DC flow in the opposite direction and at a frequency well below the peak AC flow. Using an equivalent electrical circuit model, we found that the "forward" DC flow occurred at the series resonance frequency (with large AC flow peak), while the "backward" DC flow occurred at a less obvious parallel resonance (a valley in AC flow magnitude). We also observed that the DC flow occurred only when there was a measurable differential in the AC flow magnitude across the valve, and the DC flow direction was from the channel with large AC flow magnitude to that with small AC flow magnitude. Using these observations and the AC flow predictions from the equivalent circuit model, we designed a device with an AC flowrate frequency profile that was expected to allow the DC flow in opposite directions at two distinct frequencies. The fabricated device showed the expected flow reversal at the expected frequencies. This approach expands the flow control toolkit to include both magnitude and direction control in frequency-tuned microfluidic pumps. The work also raises interesting questions about the

  7. PeakWorks

    Energy Technology Data Exchange (ETDEWEB)

    2016-11-30

    The PeakWorks software is designed to assist in the quantitative analysis of atom probe tomography (APT) generated mass spectra. Specifically, through an interactive user interface, mass peaks can be identified automatically (defined by a threshold) and/or identified manually. The software then provides a means to assign specific elemental isotopes (including more than one) to each peak. The software also provides a means for the user to choose background subtraction of each peak based on background fitting functions, the choice of which is left to the users discretion. Peak ranging (the mass range over which peaks are integrated) is also automated allowing the user to chose a quantitative range (e.g. full-widthhalf- maximum). The software then integrates all identified peaks, providing a background-subtracted composition, which also includes the deconvolution of peaks (i.e. those peaks that happen to have overlapping isotopic masses). The software is also able to output a 'range file' that can be used in other software packages, such as within IVAS. A range file lists the peak identities, the mass range of each identified peak, and a color code for the peak. The software is also able to generate 'dummy' peak ranges within an outputted range file that can be used within IVAS to provide a means for background subtracted proximity histogram analysis.

  8. Playing the Fertility Game at Work

    DEFF Research Database (Denmark)

    Ciliberto, Federico; Miller, Amalia Rebecca; Nielsen, Helena Skyt

    2016-01-01

    We study workplace peer effects in fertility decisions using a game theory model of strategic interactions among coworkers that allows for multiple equilibria. Using register-based data on fertile-aged women working in medium sized establishments in Denmark, we uncover negative average peer effects....... Allowing for heterogeneous effects by worker type, we find that positive effects dominate across worker types defined by age or education. Negative effects dominate within age groups and among low-education types. Policy simulations show that these estimated effects make the distribution of where women...... work an important consideration, beyond simply if they work, in predicting population fertility....

  9. Knowledge work and work-related stress

    DEFF Research Database (Denmark)

    Ipsen, Christine

    2006-01-01

    Work-related stress is an increasing problem in Europe. Earlier studies have stated that knowledge-work comprises working conditions which reflect a good psychosocial environment. Recent Danish studies, however, point at stress being an increasing problem in knowledge-intensive companies...... as good and stimulating, but has on the other hand sides to it which can cause frustration and stress. The implication of organisational characteristics of the knowledge-intensive companies studied is a transfer of the responsibility for ones own working-life. Consequently, issues are dealt...... with informally, individu-ally and incidentally. It is only when problems exist that enhanced support is offered in order to help an employee to cope or recover. As most workplace initiatives work at this tertiary level, the sources of work-related and organiza-tional stress are not reduced or eliminated...

  10. Knowledge work and work-related stress

    OpenAIRE

    Ipsen, Christine

    2006-01-01

    Work-related stress is an increasing problem in Europe. Earlier studies have stated that knowledge-work comprises working conditions which reflect a good psychosocial environment. Recent Danish studies, however, point at stress being an increasing problem in knowledge-intensive companies. These companies employ highly educated and com-petent people who apply their personal knowledge to generate new knowledge in close relationship with both custom-ers and colleagues. The employees are self-man...

  11. Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology

    Directory of Open Access Journals (Sweden)

    Jan Anderl

    2012-11-01

    Full Text Available Phallotoxins inhibit the dynamics of microfilaments in cells and lead to apoptosis. Due to poor cellular uptake these effects cannot be studied in live cells, even at millimolar toxin concentrations, nor can phalloidin be used for the elimination of tumor cells. Uptake is greatly enhanced by conjugation of phallotoxins to either lipophilic or polycationic moieties, such as oleic acid, polylysine, or Tat-peptide. These conjugates were lethally toxic for cells, e.g., mouse fibroblasts or Jurkat leukemia cells, in the micromolar range. Uptake into cells starts with the attachment of the toxin conjugates to the plasma membrane, followed by endocytosis and, in most cases, cleavage of the toxin from the carrier. Interestingly, the internalization rate of phalloidin into cells was also significantly increased by the fluorescent moiety tetramethylrhodaminyl, as well as by high molecular weight methoxy-polyethyleneglycol, two compounds unknown so far for their uptake-mediating activity. Conjugation to carriers as investigated in this work will allow the use of phallotoxins in experimental cell biology and possibly in tumor therapy. The findings obtained with phallotoxins could be applied also to the family of amatoxins, where α-amanitin, for example, when conjugated to oleic acid was more than 100-fold more toxic for cells than the native toxin. This suggests the possibility of a more general use of the moieties examined here to enhance the uptake of hydrophilic peptides, or drugs, into live cells.

  12. A new type of remote sensors which allow directly forming certain statistical estimates of images

    Science.gov (United States)

    Podlaskin, Boris; Guk, Elena; Karpenko, Andrey

    2010-10-01

    A new approach to the problems of statistical and structural pattern recognition, a signal processing and image analysis techniques has been considered. These problems are extremely important for tasks being solved by airborne and space borne remote sensing systems. Development of new remote sensors for image and signal processing is inherently connected with a possibility of statistical processing of images. Fundamentally new optoelectronic sensors "Multiscan" have been suggested in the present paper. Such sensors make it possible to form directly certain statistical estimates, which describe completely enough the different types of images. The sensors under discussion perform the Lebesgue-Stieltjes signal integration rather than the Cauchy-Riemann one. That permits to create integral functionals for determining statistical features of images. The use of the integral functionals for image processing provides a good agreement of obtained statistical estimates with required image information features. The Multiscan remote sensors allows to create a set of integral moments of an input image right up to high-order integral moments, to form a quantile representation of an input image, which provides a count number limited texture, to form a median, which provides a localisation of a low-contrast horizon line in fog, localisation of water flow boundary etc. This work presents both the description of the design concept of the new remote sensor and mathematical apparatus providing the possibility to create input image statistical features and integral functionals.

  13. Defining allowable physical property variations for high accurate measurements on polymer parts

    Science.gov (United States)

    Mohammadi, A.; Sonne, M. R.; Madruga, D. G.; De Chiffre, L.; Hattel, J. H.

    2016-06-01

    Measurement conditions and material properties have a significant impact on the dimensions of a part, especially for polymers parts. Temperature variation causes part deformations that increase the uncertainty of the measurement process. Current industrial tolerances of a few micrometres demand high accurate measurements in non-controlled ambient. Most of polymer parts are manufactured by injection moulding and their inspection is carried out after stabilization, around 200 hours. The overall goal of this work is to reach ±5μm in uncertainty measurements a polymer products which is a challenge in today`s production and metrology environments. The residual deformations in polymer products at room temperature after injection molding are important when micrometer accuracy needs to be achieved. Numerical modelling can give a valuable insight to what is happening in the polymer during cooling down after injection molding. In order to obtain accurate simulations, accurate inputs to the model are crucial. In reality however, the material and physical properties will have some variations. Although these variations may be small, they can act as a source of uncertainty for the measurement. In this paper, we investigated how big the variation in material and physical properties are allowed in order to reach the 5 μm target on the uncertainty.

  14. CRAB the CMS Tool to Allow Data Analysis in a distributed Environment

    CERN Document Server

    Fanzago, Federica; Codispoti, Giuseppe; Corvo, Marco; Fanfani, Alessandra; Farina, Fabio; Kavka, Carlos; Lacaprara, Stefano; Spiga, Daniele; Vaandering, Eric

    2008-01-01

    The CMS collaboration is developing a tool to allow physicists to access and analyze data stored in geographically distributed sites, simplifying the data discovery and hiding details related analysis job creation, execution and monitoring in the Grid environment. With this presentation we would like to show the progress of our work and some statistics about its usage. The CMS experiment will produce few PBytes of data each year to distribute and store in many computing centres spread in the countries participating to the CMS collaboration and made available for analysis to world-wide distributed physicists.CMS will use a distributed architecture based on Grid infrastructure to analyze data stored at remote sites, to assure data access only to authorized users and to ensure remote resources availability.Data analysis in a distributed environment is a task that assume to know which data are available, where data are stored and how to access them.To simplify analysis job creation and management the CMS collabor...

  15. Terahertz time domain spectroscopy allows contactless monitoring of grapevine water status

    Directory of Open Access Journals (Sweden)

    Luis Gonzaga Santesteban

    2015-06-01

    Full Text Available Agriculture is the sector with the greatest water consumption, since food production is frequently based on crop irrigation. Proper irrigation management requires reliable information on plant water status, but all the plant-based methods to determine it suffer from several inconveniences, mainly caused by the necessity of destructive sampling or of alteration of the plant organ due to contact installation. The aim of this work is to test if THz time domain reflectance measurements made on the grapevine trunk allows contactless monitoring of plant status. The experiments were performed on a potted 14-years old plant, using a general purpose THz emitter receiver head.Trunk THz time-domain reflection signal proved to be very sensitive to changes in plant water availability, as its pattern follows the trend of soil water content and trunk growth variations. Therefore, it could be used to contactless monitor plant water status. Apart from that, THz reflection signal was observed to respond to light conditions which, according to a specifically designed girdling experiment, was caused by changes in the phloem. This latter results opens a promising field of research for contactless monitoring of phloem activity.

  16. 76 FR 1504 - Pipeline Safety: Establishing Maximum Allowable Operating Pressure or Maximum Operating Pressure...

    Science.gov (United States)

    2011-01-10

    ...: Establishing Maximum Allowable Operating Pressure or Maximum Operating Pressure Using Record Evidence, and... facilities of their responsibilities, under Federal integrity management (IM) regulations, to perform... system, especially when calculating Maximum Allowable Operating Pressure (MAOP) or Maximum Operating...

  17. 77 FR 25721 - Small Entity Compliance Guide: Bottled Water: Quality Standard: Establishing an Allowable Level...

    Science.gov (United States)

    2012-05-01

    ... HUMAN SERVICES Food and Drug Administration Small Entity Compliance Guide: Bottled Water: Quality... availability of a guidance for industry entitled ``Bottled Water: Quality Standard: Establishing an Allowable... its bottled water standard of quality regulations by establishing an allowable level for...

  18. How the Heart Works

    Science.gov (United States)

    ... Works Explore How the Heart Works What Is... Anatomy Contraction Circulation Electrical System Heart Disease Related Topics Arrhythmia Congenital Heart Defects Coronary Heart Disease Heart Valve Disease How the Lungs Work Send a link to NHLBI to someone ...

  19. Work and Non-Work: Institutional Perspectives.

    Science.gov (United States)

    Dubin, Robert

    What impact do the institutions of society have on work? To answer this question a distinction was drawn between two models of social institutions, contrasting their characteristics and pointing out the implication of each model for an understanding of work and the production institution. It was concluded that the "multi-equal" model of social…

  20. Riding Third: Social Work in Ambulance Work

    Science.gov (United States)

    Campbell, Hilary; Rasmussen, Brian

    2012-01-01

    This research explored the possible role of social work alongside emergency ambulance services. An ethnographic study included semistructured interviews and direct observations collected over 300 hours while riding in ambulances in an urban setting. The data suggest that social work could play a role by providing needed psychosocial care during…

  1. Work organisation, technology and working conditions

    NARCIS (Netherlands)

    Dhondt, S.; Kraan, K.; Sloten, G. van

    2002-01-01

    The personal computer, computer networks and the Internet have brought the Union into the Information Age. These technological changes have inevitably led to changes in the work environment and the quality of working conditions. For the third time, the European Foundation for the Improvement of Livi

  2. Constant attention to work on work safety

    Energy Technology Data Exchange (ETDEWEB)

    Gurando, R.V.

    1982-01-01

    In order to improve responsibility of the workers for strict observance of the standards, rules and instruction for work safety, the Karlov NKGRE has introduced a number of indicators under socialist competition: lack of injuries, accidents, complications, fulfillment of organizational-technical measures of a comprehensive plan and collective contract, preventive maintenance schedule and instructions of the agencies of inspection and public inspectors. The organization of prevention of production injury is based on the principle ''for each object constant attention to work safety and supervisory monitoring.'' Monitoring of the condition of accident prevention is done by 69 public inspectors under the control of the commission of work safety made of 9 people. The work of the commission is done according to quarterly and annual plans. The commission reveals shortcomings, introduces specific suggestions, for example regarding reconstruction of the ventilation of the sharpener, the mechanism of pipe feed to the pipe cutting machine, etc. One of the main tasks of the commission is to participate in the rapid control of the condition of work safety at the work sites. For achievements in work to create good working and living conditions, the collective of the Karlov NKGRE was awarded certificates of the AUCCTU, the Ukrainian SSR Ministry of Geology and the USSR Ministry of Geology, as well as group and republic committees of the trade unions.

  3. Riding Third: Social Work in Ambulance Work

    Science.gov (United States)

    Campbell, Hilary; Rasmussen, Brian

    2012-01-01

    This research explored the possible role of social work alongside emergency ambulance services. An ethnographic study included semistructured interviews and direct observations collected over 300 hours while riding in ambulances in an urban setting. The data suggest that social work could play a role by providing needed psychosocial care during…

  4. 47 CFR 65.700 - Determining the maximum allowable rate of return.

    Science.gov (United States)

    2010-10-01

    ... CARRIER SERVICES (CONTINUED) INTERSTATE RATE OF RETURN PRESCRIPTION PROCEDURES AND METHODOLOGIES Maximum Allowable Rates of Return § 65.700 Determining the maximum allowable rate of return. (a) The maximum allowable rate of return for any exchange carrier's earnings on any access service category shall...

  5. 36 CFR 1280.24 - Is smoking allowed on NARA property?

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Is smoking allowed on NARA property? 1280.24 Section 1280.24 Parks, Forests, and Public Property NATIONAL ARCHIVES AND RECORDS...? Prohibited Activities § 1280.24 Is smoking allowed on NARA property? Smoking is not allowed inside any...

  6. Immediate weight-bearing after osteosynthesis of proximal tibial fractures may be allowed

    DEFF Research Database (Denmark)

    Haak, Karl Tobias; Palm, Henrik; Holck, Kim;

    2012-01-01

    Immediate weight-bearing following osteosynthesis of proximal tibial fractures is traditionally not allowed due to fear of articular fracture collapse. Anatomically shaped locking plates with sub-articular screws could improve stability and allow greater loading forces. The purpose of this study...... was to investigate if immediate weight-bearing can be allowed following locking plate osteosynthesis of proximal tibial fractures....

  7. 40 CFR Appendix B to Subpart I of... - Allowance for Facilities Planning and Design

    Science.gov (United States)

    2010-07-01

    ... allowance under § 35.2025 for facilities planning and design. The Step 2+3, Step 3 and Step 7 grant... reimburse the grantee for costs actually incurred for facilities planning or design. Rather, the allowance... for Facilities Planning and Design Building cost Allowance as a percentage of building cost* $100,000...

  8. Struggling at work

    DEFF Research Database (Denmark)

    Hjarsbech, Pernille U; Nielsen, Maj Britt D.; Andersen, Malene Friis

    2015-01-01

    who were in an on-going process that we conceptualised as struggling at work. Informants struggled with the negative experiences of work that led to emotional, cognitive and somatic symptoms. Relationships with supervisors and colleagues, work load and work pressure and their self-image as a good...... with problems at work. Methods: From a survey study on work and mental health in Denmark, we invited participants for in-depth interviews. Using grounded theory, we conducted 13 semi structured interviews with employees, at work, experiencing depressive symptoms. Findings: Work was pivotal for the informants...

  9. Toward a Grid Work flow Formal Composition

    Energy Technology Data Exchange (ETDEWEB)

    Hlaoui, Y. B.; BenAyed, L. J.

    2007-07-01

    This paper exposes a new approach for the composition of grid work flow models. This approach proposes an abstract syntax for the UML Activity Diagrams (UML-AD) and a formal foundation for grid work flow composition in form of a work flow algebra based on UML-AD. This composition fulfils the need for collaborative model development particularly the specification and the reduction of the complexity of grid work flow model verification. This complexity has arisen with the increase in scale of grid work flow applications such as science and e-business applications since large amounts of computational resources are required and multiple parties could be involved in the development process and in the use of grid work flows. Furthermore, the proposed algebra allows the definition of work flow views which are useful to limit the access to predefined users in order to ensure the security of grid work flow applications. (Author)

  10. Desert Pathfinder at Work

    Science.gov (United States)

    2005-09-01

    The Atacama Pathfinder Experiment (APEX) project celebrates the inauguration of its outstanding 12-m telescope, located on the 5100m high Chajnantor plateau in the Atacama Desert (Chile). The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, passed successfully its Science Verification phase in July, and since then is performing regular science observations. This new front-line facility provides access to the "Cold Universe" with unprecedented sensitivity and image quality. After months of careful efforts to set up the telescope to work at the best possible technical level, those involved in the project are looking with satisfaction at the fruit of their labour: APEX is not only fully operational, it has already provided important scientific results. "The superb sensitivity of our detectors together with the excellence of the site allow fantastic observations that would not be possible with any other telescope in the world," said Karl Menten, Director of the group for Millimeter and Sub-Millimeter Astronomy at the Max-Planck-Institute for Radio Astronomy (MPIfR) and Principal Investigator of the APEX project. ESO PR Photo 30/05 ESO PR Photo 30/05 Sub-Millimetre Image of a Stellar Cradle [Preview - JPEG: 400 x 627 pix - 200k] [Normal - JPEG: 800 x 1254 pix - 503k] [Full Res - JPEG: 1539 x 2413 pix - 1.3M] Caption: ESO PR Photo 30/05 is an image of the giant molecular cloud G327 taken with APEX. More than 5000 spectra were taken in the J=3-2 line of the carbon monoxide molecule (CO), one of the best tracers of molecular clouds, in which star formation takes place. The bright peak in the north of the cloud is an evolved star forming region, where the gas is heated by a cluster of new stars. The most interesting region in the image is totally inconspicuous in CO: the G327 hot core, as seen in methanol contours. It is a truly exceptional source, and is one of the richest sources of emission from complex organic molecules in the

  11. Patterns of work injuries

    DEFF Research Database (Denmark)

    Lander, Flemming; Nielsen, Kent Jacob; Rasmussen, Kurt;

    2014-01-01

    To compare work injuries treated in an emergency department (ED) and injuries reported to the Danish Working Environment Authority (DWEA).......To compare work injuries treated in an emergency department (ED) and injuries reported to the Danish Working Environment Authority (DWEA)....

  12. New ways to work.

    Science.gov (United States)

    2003-06-01

    Flexible working, work-life balance, family friendliness; all are now familiar terms in today's NHS, and employers, managers and leaders are expected to be forging ahead in improving the working lives for all staff. If you are looking for new ideas to help tackle the challenge, you should try the New Ways to Work website.

  13. CTOs at work

    CERN Document Server

    Donaldson, Scott; Donaldson, Gary

    2012-01-01

    Scott Donaldson, Stanley Siegel and Gary Donaldson interview many of the world's most influential chief technology officers in CTOs at Work, offering a brand-new companion volume to the highly acclaimed elite At Work books including Coders at Work, CIOS at Work and Venture Capitalists at Work. As the words "at work" suggest, the authors focus on how their interviewees tackle the day-to-day work of the CTO while revealing much more: how they got there, how they manage and allocate projects, and how they interact with business units and ensure that their companies take advantage of technologies,

  14. Working-time autonomy as a management practice

    OpenAIRE

    Beckmann, Michael

    2016-01-01

    Allowing workers to control their work hours (working-time autonomy) is a controversial policy for worker empowerment, with concerns that range from increased shirking to excessive intensification of work. Empirical evidence, however, supports neither view. Recent studies find that working-time autonomy improves individual and firm performance without promoting overload or exhaustion from work. However, if working-time autonomy is incorporated into a system of family-friendly workplace practi...

  15. On a local mass dimension one Fermi field of spin one-half and the theoretical crevice that allows it

    CERN Document Server

    Ahluwalia, Dharam Vir

    2013-01-01

    Since the 1928 seminal work of Dirac, and its subsequent development by Weinberg, a view is held that there is a unique Fermi field of spin one-half. It is endowed with mass dimension three-half. Combined, these characteristics profoundly affect the phenomenology of the high energy physics, astrophysics, and cosmology. We here present a counter example by providing a local, mass dimension one, Fermi field of spin one-half. The theory, inter alia, thus allows dimensionless quartic self interaction for the new fermions, and its only other dimensionless coupling is quadratic in the new fermions and in the standard-model scalar field. For these reasons, the immediate application of the new theory resides in the dark-matter sector of physical reality. The lowest-mass associated new particle may leave its unique signature at the Large Hadron Collider. We discuss in detail the theoretical crevice that allows the existence of the new quantum field.

  16. Mediation analysis allowing for exposure-mediator interactions and causal interpretation: theoretical assumptions and implementation with SAS and SPSS macros.

    Science.gov (United States)

    Valeri, Linda; Vanderweele, Tyler J

    2013-06-01

    Mediation analysis is a useful and widely employed approach to studies in the field of psychology and in the social and biomedical sciences. The contributions of this article are several-fold. First we seek to bring the developments in mediation analysis for nonlinear models within the counterfactual framework to the psychology audience in an accessible format and compare the sorts of inferences about mediation that are possible in the presence of exposure-mediator interaction when using a counterfactual versus the standard statistical approach. Second, the work by VanderWeele and Vansteelandt (2009, 2010) is extended here to allow for dichotomous mediators and count outcomes. Third, we provide SAS and SPSS macros to implement all of these mediation analysis techniques automatically, and we compare the types of inferences about mediation that are allowed by a variety of software macros.

  17. Direct Chromatin PCR (DC-PCR): Hypotonic Conditions Allow Differentiation of Chromatin States during Thermal Cycling

    Science.gov (United States)

    Vatolin, Sergei; Khan, Shahper N.; Reu, Frederic J.

    2012-01-01

    Current methods to study chromatin configuration are not well suited for high throughput drug screening since they require large cell numbers and multiple experimental steps that include centrifugation for isolation of nuclei or DNA. Here we show that site specific chromatin analysis can be achieved in one step by simply performing direct chromatin PCR (DC-PCR) on cells. The basic underlying observation was that standard hypotonic PCR buffers prevent global cellular chromatin solubilization during thermal cycling while more loosely organized chromatin can be amplified. Despite repeated heating to >90°C, 41 of 61 tested 5′ sequences of silenced genes (CDKN2A, PU.1, IRF4, FOSB, CD34) were not amplifiable while 47 could be amplified from expressing cells. Two gene regions (IRF4, FOSB) even required pre-heating of cells in isotonic media to allow this differentiation; otherwise none of 19 assayed sequences yielded PCR products. Cells with baseline expression or epigenetic reactivation gave similar DC-PCR results. Silencing during differentiation of CD34 positive cord blood cells closed respective chromatin while treatment of myeloma cells with an IRF4 transcriptional inhibitor opened a site to DC-PCR that was occupied by RNA polymerase II and NFκB as determined by ChIP. Translation into real-time PCR can not be achieved with commercial real-time PCR buffers which potently open chromatin, but even with simple ethidium bromide addition to standard PCR mastermix we were able to identify hits in small molecules screens that suppressed IRF4 expression or reactivated CDKN2A in myeloma cells using densitometry or visual inspection of PCR plates under UV light. While need in drug development inspired this work, application to genome-wide analysis appears feasible using phi29 for selective amplification of open cellular chromatin followed by library construction from supernatants since such supernatants yielded similar results as gene specific DC-PCR. PMID:22984542

  18. Direct chromatin PCR (DC-PCR: hypotonic conditions allow differentiation of chromatin states during thermal cycling.

    Directory of Open Access Journals (Sweden)

    Sergei Vatolin

    Full Text Available Current methods to study chromatin configuration are not well suited for high throughput drug screening since they require large cell numbers and multiple experimental steps that include centrifugation for isolation of nuclei or DNA. Here we show that site specific chromatin analysis can be achieved in one step by simply performing direct chromatin PCR (DC-PCR on cells. The basic underlying observation was that standard hypotonic PCR buffers prevent global cellular chromatin solubilization during thermal cycling while more loosely organized chromatin can be amplified. Despite repeated heating to >90 °C, 41 of 61 tested 5' sequences of silenced genes (CDKN2A, PU.1, IRF4, FOSB, CD34 were not amplifiable while 47 could be amplified from expressing cells. Two gene regions (IRF4, FOSB even required pre-heating of cells in isotonic media to allow this differentiation; otherwise none of 19 assayed sequences yielded PCR products. Cells with baseline expression or epigenetic reactivation gave similar DC-PCR results. Silencing during differentiation of CD34 positive cord blood cells closed respective chromatin while treatment of myeloma cells with an IRF4 transcriptional inhibitor opened a site to DC-PCR that was occupied by RNA polymerase II and NFκB as determined by ChIP. Translation into real-time PCR can not be achieved with commercial real-time PCR buffers which potently open chromatin, but even with simple ethidium bromide addition to standard PCR mastermix we were able to identify hits in small molecules screens that suppressed IRF4 expression or reactivated CDKN2A in myeloma cells using densitometry or visual inspection of PCR plates under UV light. While need in drug development inspired this work, application to genome-wide analysis appears feasible using phi29 for selective amplification of open cellular chromatin followed by library construction from supernatants since such supernatants yielded similar results as gene specific DC-PCR.

  19. The Maximum Free Magnetic Energy Allowed in a Solar Active Region

    Science.gov (United States)

    Moore, Ronald L.; Falconer, David A.

    2009-01-01

    Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are (sup L) WL(sub SG), a gauge of the total free energy in an active region's magnetic field, and sup L(sub theta), a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 R(sub Sun) central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size (sup L) (sub theta) of the active region, (2) in (Log (sup L)WL(sub SG), Log(sup L) theta) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: =- theta/A approximately equal to 300 G, where theta is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is 1, and (2) any one CME/flare eruption releases no more than a small fraction (less than 10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division and NSF's Division of Atmospheric Sciences.

  20. The Ambiguity of Work

    DEFF Research Database (Denmark)

    Humle, Didde Maria

    2014-01-01

    drawing on the results of an ethnographic case study of a consultancy house; more specifically, it comprises an exploration of the narrative identity work of consultants as they perform work practice stories of self, work, and the organization negotiating why the work they do is both challenging...... contributes by showing that some of the elements perceived to make the work meaningful and rewarding are the same ones also described as potentially demanding and challenging. Furthermore, the article contributes by arguing that studying work practice stories as (ante)narrative identity work provides a rich......This article contributes to the current debate among organizational and work-life researchers on the double-sided nature of knowledge work, which offers great freedom and satisfaction on the one hand and the potential to be overly demanding and stressful on the other. This contribution involves...

  1. Experimental comparison of impact of auction format on carbon allowance market

    DEFF Research Database (Denmark)

    Cong, Ronggang; Wei, Yi-Ming

    2012-01-01

    Carbon allowances auctions are a good way to achieve the carbon allowance allocations under international agreements to address global climate change. Based on an economic experiment, this paper compares three possible carbon allowance auction formats (uniform price auction, discriminatory price...... two formats; (2) when there are relatively fewer bidders and there are obvious communications between them, explicit collusions are observed under English clock auction. In this case, discriminatory price auction helps prevent collusion to some extents; (3) in the banking scenario, more speculations...

  2. Predicting Sustainable Work Behavior

    DEFF Research Database (Denmark)

    Hald, Kim Sundtoft

    2013-01-01

    Sustainable work behavior is an important issue for operations managers – it has implications for most outcomes of OM. This research explores the antecedents of sustainable work behavior. It revisits and extends the sociotechnical model developed by Brown et al. (2000) on predicting safe behavior....... Employee characteristics and general attitudes towards safety and work condition are included in the extended model. A survey was handed out to 654 employees in Chinese factories. This research contributes by demonstrating how employee- characteristics and general attitudes towards safety and work...... condition influence their sustainable work behavior. A new definition of sustainable work behavior is proposed....

  3. LSTM with Working Memory

    OpenAIRE

    Pulver, Andrew; Lyu, Siwei

    2016-01-01

    LSTM is arguably the most successful RNN architecture for many tasks that involve sequential information. In the past few years there have been several proposed improvements to LSTM. We propose an improvement to LSTM which allows communication between memory cells in different blocks and allows an LSTM layer to carry out internal computation within its memory.

  4. Practical Work in Chemistry: Chemistry Students' Perceptions of Working Independently in a Less Organised Environment

    Science.gov (United States)

    Lyall, Robert James

    2010-01-01

    A study of chemistry students in an organic practical class, where they were required to work on their own, found considerable benefits in allowing them to work independently in a less organised environment. Although apprehensive at first, they soon gained a self-belief in their own abilities and were able to complete the course with minimal input…

  5. Flow Control Technology

    Science.gov (United States)

    2010-07-01

    downstream of the propeller system. Figure 16 and Figure 17 show the ADV used by Huxley and Hartman [5] as well as a flow diagram for their...Max 17° Figure 23: Power Coefficient of Asymmetric Test Trials vs. Sinusoid pitch schedule. The aim of the work by Huxley and Hartman [5] was...Fagley, Ph.D. candidate, worked with Cadets Thiago Huxley and Christopher Hartman on a feedback controlled cycloidal wave energy converter in

  6. Working during cancer treatment

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000834.htm Working during cancer treatment To use the sharing features on this page, ... JavaScript. Many people continue to work throughout their cancer treatment. Cancer, or the side effects of treatment, may ...

  7. Current Work Politics

    DEFF Research Database (Denmark)

    Hasle, Peter; Hvid, Helge

    2003-01-01

    A presentation of the development of the Danish work politics during the last decade, discussed in an international context.......A presentation of the development of the Danish work politics during the last decade, discussed in an international context....

  8. How the Ear Works

    Science.gov (United States)

    ... Find an ENT Doctor Near You How the Ear Works How the Ear Works Patient Health Information News media interested in ... public relations staff at newsroom@entnet.org . The ear has three main parts: the outer ear (including ...

  9. NCPC Commemorative Works Catalog

    Data.gov (United States)

    National Capital Planning Commission — The CWC is a complete list of Washington DC's commemorative works on federal land. Each record includes a work's title, location, a short description of its purpose,...

  10. Group Work Publication-1991.

    Science.gov (United States)

    Zimpfer, David G.

    1992-01-01

    Lists 21 new publications in group work, of which 9 are reviewed. Those discussed include publications on group counseling and psychotherapy, structured groups, support groups, psychodrama, and social group work. (Author/NB)

  11. Dynamics of auditory working memory

    Directory of Open Access Journals (Sweden)

    Jochen eKaiser

    2015-05-01

    Full Text Available Working memory denotes the ability to retain stimuli in mind that are no longer physically present and to perform mental operations on them. Electro- and magnetoencephalography allow investigating the short-term maintenance of acoustic stimuli at a high temporal resolution. Studies investigating working memory for non-spatial and spatial auditory information have suggested differential roles of regions along the putative auditory ventral and dorsal streams, respectively, in the processing of the different sound properties. Analyses of event-related potentials have shown sustained, memory load-dependent deflections over the retention periods. The topography of these waves suggested an involvement of modality-specific sensory storage regions. Spectral analysis has yielded information about the temporal dynamics of auditory working memory processing of individual stimuli, showing activation peaks during the delay phase whose timing was related to task performance. Coherence at different frequencies was enhanced between frontal and sensory cortex. In summary, auditory working memory seems to rely on the dynamic interplay between frontal executive systems and sensory representation regions.

  12. The recognition of work

    OpenAIRE

    Nierling, Linda

    2007-01-01

    The following article argues that recognition structures in work relations differ significantly in the sphere of paid work in contrast to unpaid work in private spheres. According to the systematic approach on recognition of Axel Honneth three different levels of recognition are identified: the interpersonal recognition, organisational recognition and societal recognition. Based on this framework it can be stated that recognition structures in the sphere of paid work and in private spheres di...

  13. Work-related stress

    OpenAIRE

    Houtman, I.L.D.

    2005-01-01

    Changes in the content and organisation of work in recent decades have resulted in an intensification of work, which is commonly regarded as a cause of stress. This report presents trends in the risks and consequences of work-related stress, and identifies how these can be prevented. The focus iswithin the European Working Conditions Observatory (EWCO) network of seven European countries in its initial phase: Denmark, Finland, France, Germany, the Netherlands, Spain and Sweden. In many countr...

  14. Working with Working Families. ERIC Digest.

    Science.gov (United States)

    King, Margaret

    This ERIC Digest offers tips for understanding the needs, concerns, and feelings of employed parents, and discusses ways child caregivers can involve working parents in their children's lives while the children are enrolled in child care facilities. Competition with the caregiver, guilt over leaving children in the care of others, and little time…

  15. Work Redesign that Works for Teachers

    Science.gov (United States)

    Mayrowetz, David; Smylie, Mark A.

    2004-01-01

    Over the past two decades, scholars and practitioners in a variety of industries have considered work redesign among a constellation of strategies to promote employee recruitment and retention, development, motivation, and performance. Although educational policymakers in the middle to late 1990s shifted their attention to standards, systemic…

  16. 34 CFR 363.51 - What are the allowable administrative costs?

    Science.gov (United States)

    2010-07-01

    ... administrative costs? (a) Administrative costs—general. Expenditures are allowable for the following administrative costs: (1) Administration of the State plan supplement for this program. (2) Planning program... 34 Education 2 2010-07-01 2010-07-01 false What are the allowable administrative costs?...

  17. The Effects of Replacing Income Tax Deductions for Children with Children's Allowances: A Microsimulation.

    Science.gov (United States)

    Meyer, Daniel R.; And Others

    1991-01-01

    Argues that a children's allowance could be instituted in this country that would decrease poverty and welfare participation while not costing the federal government any additional resources. Discusses microsimulation model that shows effects of three levels of children's allowances on government revenues, family incomes, welfare use, and labor…

  18. When less is more: a simple Western blotting amendment allowing data acquisition on human single fibers

    DEFF Research Database (Denmark)

    Jensen, Thomas Elbenhardt; Richter, Erik A

    2011-01-01

    This editorial discusses a simple western blotting-amendment allowing rapid data-acquisition on single fibers obtained from freeze-dried human skeletal muscle biopsies.......This editorial discusses a simple western blotting-amendment allowing rapid data-acquisition on single fibers obtained from freeze-dried human skeletal muscle biopsies....

  19. 20 CFR 645.220 - What activities are allowable under this part?

    Science.gov (United States)

    2010-04-01

    ...) Occupational skills training; (3) English as a second language training; and (4) Mentoring. (f) Job retention... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What activities are allowable under this part....220 What activities are allowable under this part? Entities operating WtW projects may use WtW funds...

  20. 19 CFR 151.23 - Allowance for moisture in raw sugar.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Allowance for moisture in raw sugar. 151.23...; DEPARTMENT OF THE TREASURY (CONTINUED) EXAMINATION, SAMPLING, AND TESTING OF MERCHANDISE Sugars, Sirups, and Molasses § 151.23 Allowance for moisture in raw sugar. Inasmuch as the absorption of sea water or moisture...