WorldWideScience

Sample records for internal shock model

  1. TIMING SIGNATURES OF THE INTERNAL-SHOCK MODEL FOR BLAZARS

    International Nuclear Information System (INIS)

    Boettcher, M.; Dermer, C. D.

    2010-01-01

    We investigate the spectral and timing signatures of the internal-shock model for blazars. For this purpose, we develop a semi-analytical model for the time-dependent radiative output from internal shocks arising from colliding relativistic shells in a blazar jet. The emission through synchrotron and synchrotron-self Compton radiation as well as Comptonization of an isotropic external radiation field are taken into account. We evaluate the discrete correlation function (DCF) of the model light curves in order to evaluate features of photon-energy-dependent time lags and the quality of the correlation, represented by the peak value of the DCF. The almost completely analytic nature of our approach allows us to study in detail the influence of various model parameters on the resulting spectral and timing features. This paper focuses on a range of parameters in which the γ-ray production is dominated by Comptonization of external radiation, most likely appropriate for γ-ray bright flat-spectrum radio quasars (FSRQs) or low-frequency peaked BL Lac objects (LBLs). In most cases relevant for FSRQs and LBLs, the variability of the optical emission is highly correlated with the X-ray and high-energy (HE: > 100 MeV) γ-ray emission. Our baseline model predicts a lead of the optical variability with respect to the higher-energy bands by 1-2 hr and of the HE γ-rays before the X-rays by about 1 hr. We show that variations of certain parameters may lead to changing signs of inter-band time lags, potentially explaining the lack of persistent trends of time lags in most blazars.

  2. Social Skills Difficulty: Model of Culture Shock for International Graduate Students

    Science.gov (United States)

    Chapdelaine, Raquel Faria; Alexitch, Louise R.

    2004-01-01

    This study expanded and tested Furnham and Bochner's (1982) model of culture shock, employing a sample of 156 male international students in a Canadian university. Path analysis was used to assess the effects of cultural differences, size of co-national group, family status, cross-cultural experience, and social interaction with hosts on culture…

  3. Multi-messenger Light Curves from Gamma-Ray Bursts in the Internal Shock Model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, Columbus, OH 43210 (United States); Heinze, Jonas; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, D-15738 Zeuthen (Germany); Murase, Kohta, E-mail: bustamanteramirez.1@osu.edu, E-mail: walter.winter@desy.de, E-mail: jonas.heinze@desy.de, E-mail: murase@psu.edu [Center for Particle and Gravitational Astrophysics, The Pennsylvania State University, University Park, PA16802 (United States)

    2017-03-01

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma-rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure can be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  4. Multi-messenger light curves from gamma-ray bursts in the internal shock model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Ohio State Univ., Columbus, OH (United States). Center for Cosmology and AstroParticle Physics (CCAPP); Ohio State Univ., Columbus, OH (United States). Dept. of Physics; Murase, Kohta [Pennsylvania State Univ., University Park, PA (United States). Center for Particle and Gravitational Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2016-06-15

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure tend to be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  5. 30th International Symposium on Shock Waves

    CERN Document Server

    Sadot, Oren; Igra, Ozer

    2017-01-01

    These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...

  6. Theoretical Models of Culture Shock and Adaptation in International Students in Higher Education

    Science.gov (United States)

    Zhou, Yuefang; Jindal-Snape, Divya; Topping, Keith; Todman, John

    2008-01-01

    Theoretical concepts of culture shock and adaptation are reviewed, as applied to the pedagogical adaptation of student sojourners in an unfamiliar culture. The historical development of "traditional" theories of culture shock led to the emergence of contemporary theoretical approaches, such as "culture learning", "stress and coping" and "social…

  7. 29th International Symposium on Shock Waves

    CERN Document Server

    Ranjan, Devesh

    2015-01-01

    This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion,  Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interes...

  8. Investing in global shock absorbers | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-02-02

    Feb 2, 2011 ... Canada's funding for the International Monetary Fund's "Exogenous Shocks Facility" is an important contribution to dealing with a problem that warrants greater international attention and more creative solutions.

  9. 28th International Symposium on Shock Waves

    CERN Document Server

    2012-01-01

    The University of Manchester hosted the 28th International Symposium on Shock Waves between 17 and 22 July 2011. The International Symposium on Shock Waves first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW28 focused on the following areas: Blast Waves, Chemically Reacting Flows, Dense Gases and Rarefied Flows, Detonation and Combustion, Diagnostics, Facilities, Flow Visualisation, Hypersonic Flow, Ignition, Impact and Compaction, Multiphase Flow, Nozzle Flow, Numerical Methods, Propulsion, Richtmyer-Meshkov, Shockwave Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shockwave Phenomena and Applications, as well as Medical and Biological Applications. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 28 and individuals interested in these fields.

  10. Culture Shock and the International Student "Offshore"

    Science.gov (United States)

    Pyvis, David; Chapman, Anne

    2005-01-01

    Within the context of higher education, it is the international student who travels to another country to study who is typically identified as the subject at risk of culture shock. This paper attempts to go further by suggesting that international students studying in their home country with an overseas institution may also experience culture…

  11. A study of internal energy relaxation in shocks using molecular dynamics based models

    International Nuclear Information System (INIS)

    Li, Zheng; Parsons, Neal; Levin, Deborah A.

    2015-01-01

    Recent potential energy surfaces (PESs) for the N 2 + N and N 2 + N 2 systems are used in molecular dynamics (MD) to simulate rates of vibrational and rotational relaxations for conditions that occur in hypersonic flows. For both chemical systems, it is found that the rotational relaxation number increases with the translational temperature and decreases as the rotational temperature approaches the translational temperature. The vibrational relaxation number is observed to decrease with translational temperature and approaches the rotational relaxation number in the high temperature region. The rotational and vibrational relaxation numbers are generally larger in the N 2 + N 2 system. MD-quasi-classical trajectory (QCT) with the PESs is also used to calculate the V-T transition cross sections, the collision cross section, and the dissociation cross section for each collision pair. Direct simulation Monte Carlo (DSMC) results for hypersonic flow over a blunt body with the total collision cross section from MD/QCT simulations, Larsen-Borgnakke with new relaxation numbers, and the N 2 dissociation rate from MD/QCT show a profile with a decreased translational temperature and a rotational temperature close to vibrational temperature. The results demonstrate that many of the physical models employed in DSMC should be revised as fundamental potential energy surfaces suitable for high temperature conditions become available

  12. A Prognostic Model for Development of Profound Shock among Children Presenting with Dengue Shock Syndrome.

    Directory of Open Access Journals (Sweden)

    Phung Khanh Lam

    Full Text Available To identify risk factors and develop a prediction model for the development of profound and recurrent shock amongst children presenting with dengue shock syndrome (DSS.We analyzed data from a prospective cohort of children with DSS recruited at the Paediatric Intensive Care Unit of the Hospital for Tropical Disease in Ho Chi Minh City, Vietnam. The primary endpoint was "profound DSS", defined as ≥2 recurrent shock episodes (for subjects presenting in compensated shock, or ≥1 recurrent shock episodes (for subjects presenting initially with decompensated/hypotensive shock, and/or requirement for inotropic support. Recurrent shock was evaluated as a secondary endpoint. Risk factors were pre-defined clinical and laboratory variables collected at the time of presentation with shock. Prognostic model development was based on logistic regression and compared to several alternative approaches.The analysis population included 1207 children of whom 222 (18% progressed to "profound DSS" and 433 (36% had recurrent shock. Independent risk factors for both endpoints included younger age, earlier presentation, higher pulse rate, higher temperature, higher haematocrit and, for females, worse hemodynamic status at presentation. The final prognostic model for "profound DSS" showed acceptable discrimination (AUC=0.69 for internal validation and calibration and is presented as a simple score-chart.Several risk factors for development of profound or recurrent shock among children presenting with DSS were identified. The score-chart derived from the prognostic models should improve triage and management of children presenting with DSS in dengue-endemic areas.

  13. Dynamical Properties of Internal Shocks Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Pe’er, Asaf; Long, Killian [Physics Department, University College Cork, Cork (Ireland); Casella, Piergiorgio [INAF, Osservatorio Astronomico di Roma, Via Frascati 33, I-00078 Monteporzio Catone (Italy)

    2017-09-01

    Internal shocks between propagating plasma shells, originally ejected at different times with different velocities, are believed to play a major role in dissipating the kinetic energy, thereby explaining the observed light curves and spectra in a large range of transient objects. Even if initially the colliding plasmas are cold, following the first collision, the plasma shells are substantially heated, implying that in a scenario of multiple collisions, most collisions take place between plasmas of non-zero temperatures. Here, we calculate the dynamical properties of plasmas resulting from a collision between arbitrarily hot plasma shells, moving at arbitrary speeds. We provide simple analytical expressions valid for both ultrarelativistic and Newtonian velocities for both hot and cold plasmas. We derive the minimum criteria required for the formation of the two-shock wave system, and show that in the relativistic limit, the minimum Lorentz factor is proportional to the square root of the ratio of the initial plasmas enthalpies. We provide basic scaling laws of synchrotron emission from both the forward and reverse-shock waves, and show how these can be used to deduce the properties of the colliding shells. Finally, we discuss the implications of these results in the study of several astronomical transients, such as X-ray binaries, radio-loud quasars, and gamma-ray bursts.

  14. Asymmetric impacts of international energy shocks on macroeconomic activities

    International Nuclear Information System (INIS)

    While limited by its scarcity of natural resources, the impacts of energy price changes on Taiwan's economic activities have been an important issue for social public and government authorities. This study applies the multivariate threshold model to investigate the effects of various international energy price shocks on Taiwan's macroeconomic activity. By separating energy price changes into the so-called decrease and increase regimes, we can realize different impacts of energy price changes and their shocks on economic output. The results confirm that there is an asymmetric threshold effect for the energy-output nexus. The optimal threshold levels are exactly where the oil price change is at 2.48%, the natural gas price change is at 0.66%, and the coal price change is at 0.25%. The impulse response analysis suggests that oil price and natural gas shocks have a delayed negative impact on macroeconomic activities. - Highlights: ► This study applies multivariate threshold model to investigate the effects of various international energy price shocks on Taiwan's macroeconomic activity. ► The results confirm that there is an asymmetric threshold effect for energy-output nexus. ► The optimal threshold levels are exactly found where oil price change is at 2.48%, natural gas price change is at 0.66%, and coal price change is at 0.25%.

  15. Gamma-ray emission from internal shocks in novae

    Science.gov (United States)

    Martin, P.; Dubus, G.; Jean, P.; Tatischeff, V.; Dosne, C.

    2018-04-01

    Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods: We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results: The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to 100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10-5-10-4 M⊙ expands in a homologous way with a maximum velocity of 1000-2000 km s-1, followed within a day by a wind with a velocity problem are degenerate and/or poorly constrained except for the wind velocity, the relatively low values of which result in the majority of best-fit models having gamma-ray spectra

  16. Model for Shock Wave Chaos

    KAUST Repository

    Kasimov, Aslan R.

    2013-03-08

    We propose the following model equation, ut+1/2(u2−uus)x=f(x,us) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x=0 for any t≥0. Here, us(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

  17. International trade with pensions and demographic shock

    NARCIS (Netherlands)

    Fedotenkov, I.; van Groezen, Bas; Meijdam, Lex

    The central question of this paper is how international trade and specialization are affected by different designs of pension schemes and asymmetric demographic changes. In a model with two goods, two countries and two production factors, we find that countries with a relatively large unfunded

  18. 3D model of bow shocks

    Science.gov (United States)

    Gustafsson, M.; Ravkilde, T.; Kristensen, L. E.; Cabrit, S.; Field, D.; Pineau Des Forêts, G.

    2010-04-01

    Context. Shocks produced by outflows from young stars are often observed as bow-shaped structures in which the H2 line strength and morphology are characteristic of the physical and chemical environments and the velocity of the impact. Aims: We present a 3D model of interstellar bow shocks propagating in a homogeneous molecular medium with a uniform magnetic field. The model enables us to estimate the shock conditions in observed flows. As an example, we show how the model can reproduce rovibrational H2 observations of a bow shock in OMC1. Methods: The 3D model is constructed by associating a planar shock with every point on a 3D bow skeleton. The planar shocks are modelled with a highly sophisticated chemical reaction network that is essential for predicting accurate shock widths and line emissions. The shock conditions vary along the bow surface and determine the shock type, the local thickness, and brightness of the bow shell. The motion of the cooling gas parallel to the bow surface is also considered. The bow shock can move at an arbitrary inclination to the magnetic field and to the observer, and we model the projected morphology and radial velocity distribution in the plane-of-sky. Results: The morphology of a bow shock is highly dependent on the orientation of the magnetic field and the inclination of the flow. Bow shocks can appear in many different guises and do not necessarily show a characteristic bow shape. The ratio of the H2 v = 2-1 S(1) line to the v = 1-0 S(1) line is variable across the flow and the spatial offset between the peaks of the lines may be used to estimate the inclination of the flow. The radial velocity comes to a maximum behind the apparent apex of the bow shock when the flow is seen at an inclination different from face-on. Under certain circumstances the radial velocity of an expanding bow shock can show the same signatures as a rotating flow. In this case a velocity gradient perpendicular to the outflow direction is a projection

  19. Oil Shocks through International Transport Costs: Evidence from U.S. Business Cycles

    OpenAIRE

    Hakan Yilmazkuday

    2011-01-01

    The effects of oil shocks on output volatility through international transport costs are investigated in an open-economy DSGE model. Two versions of the model, with and without international transport costs, are structurally estimated for the U.S. economy by a Bayesian approach for moving windows of ten years. For model selection, the posterior odds ratios of the two versions are compared for each ten-year window. The version with international transport costs is selected during periods of hi...

  20. Numerical modeling of shock-sensitivity experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, A.L.; Forest, C.A.; Kershner, J.D.; Mader, C.L.; Pimbley, G.H.

    1981-01-01

    The Forest Fire rate model of shock initiation of heterogeneous explosives has been used to study several experiments commonly performed to measure the sensitivity of explosives to shock and to study initiation by explosive-formed jets. The minimum priming charge test, the gap test, the shotgun test, sympathetic detonation, and jet initiation have been modeled numerically using the Forest Fire rate in the reactive hydrodynamic codes SIN and 2DE.

  1. Reliability assessment of competing risks with generalized mixed shock models

    International Nuclear Information System (INIS)

    Rafiee, Koosha; Feng, Qianmei; Coit, David W.

    2017-01-01

    This paper investigates reliability modeling for systems subject to dependent competing risks considering the impact from a new generalized mixed shock model. Two dependent competing risks are soft failure due to a degradation process, and hard failure due to random shocks. The shock process contains fatal shocks that can cause hard failure instantaneously, and nonfatal shocks that impact the system in three different ways: 1) damaging the unit by immediately increasing the degradation level, 2) speeding up the deterioration by accelerating the degradation rate, and 3) weakening the unit strength by reducing the hard failure threshold. While the first impact from nonfatal shocks comes from each individual shock, the other two impacts are realized when the condition for a new generalized mixed shock model is satisfied. Unlike most existing mixed shock models that consider a combination of two shock patterns, our new generalized mixed shock model includes three classic shock patterns. According to the proposed generalized mixed shock model, the degradation rate and the hard failure threshold can simultaneously shift multiple times, whenever the condition for one of these three shock patterns is satisfied. An example using micro-electro-mechanical systems devices illustrates the effectiveness of the proposed approach with sensitivity analysis. - Highlights: • A rich reliability model for systems subject to dependent failures is proposed. • The degradation rate and the hard failure threshold can shift simultaneously. • The shift is triggered by a new generalized mixed shock model. • The shift can occur multiple times under the generalized mixed shock model.

  2. Modeling Propagation of Shock Waves in Metals

    Science.gov (United States)

    Howard, W. M.; Molitoris, J. D.

    2006-07-01

    We present modeling results for the propagation of strong shock waves in metals. In particular, we use an arbitrary Lagrange Eulerian (ALE3D) code to model the propagation of strong pressure waves (P ˜ 300 to 400 kbars) generated with high explosives in contact with aluminum cylinders. The aluminum cylinders are assumed to be both flat-topped and have large-amplitude curved surfaces. We use 3D Lagrange mechanics. For the aluminum we use a rate-independent Steinberg-Guinan model, where the yield strength and shear modulus depend on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and shear modulus is set to zero. The pressure is represented as a seven-term polynomial as a function of density. For the HMX-based high explosive, we use a JWL, with a program burn model that give the correct detonation velocity and C-J pressure (P ˜ 390 kbars). For the case of the large-amplitude curved surface, we discuss the evolving shock structure in terms of the early shock propagation experiments by Sakharov.

  3. Oil shocks in New Keynesian models: Positive and normative implications

    Science.gov (United States)

    Chang, Jian

    Chapter 1 investigates optimal monetary policy response towards oil shocks in a New Keynesian model. We find that optimal policy, in general, becomes contractionary in response to an adverse oil shock. However, the optimal policy rule and the inflation-output trade-off depend on the specific structure of the model. The benchmark economy consists of a flexible-price energy sector and a sticky-price manufacturing sector where energy is used as an intermediate input. We show that optimal policy is to stabilize the sticky (core) price level. We then show that after incorporating a less oil-dependent sticky-price service sector, the model exhibits a trade-off in stabilizing prices and output gaps in the different sticky-price sectors. It predicts that central bank should not try to stabilize the core price level, and the economy will experience higher inflation and rising output gaps, even if central banks respond optimally. Chapter 2 addresses the observed volatility and persistence of real exchange rates and the terms of trade. It contributes to the literature with a quantitative study on the U.S. and Canada. A two-country New Keynesian model consisting of traded, non-traded, and oil production sectors is proposed to examine the time series properties of the real exchange rate, the terms of trade and the real oil price. We find that after incorporating several realistic features (namely oil price shocks, sector specific labor, non-traded goods, asymmetric pricing decisions of exporters and asymmetric consumer preferences over tradables), the benchmark model broadly matches the volatilities of the relative prices and some business cycle correlations. The model matches the data more closely after adding real demand shocks, suggesting their importance in explaining the relative price movements between the US and Canada. Chapter 3 explores several sources and transmission channels of international relative price movements. In particular, we elaborate on the role of

  4. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016

    NARCIS (Netherlands)

    Rhodes, Andrew; Evans, Laura E.; Alhazzani, Waleed; Levy, Mitchell M.; Antonelli, Massimo; Ferrer, Ricard; Kumar, Anand; Sevransky, Jonathan E.; Sprung, Charles L.; Nunnally, Mark E.; Rochwerg, Bram; Rubenfeld, Gordon D.; Angus, Derek C.; Annane, Djillali; Beale, Richard J.; Bellinghan, Geoffrey J.; Bernard, Gordon R.; Chiche, Jean-Daniel; Coopersmith, Craig; de Backer, Daniel P.; French, Craig J.; Fujishima, Seitaro; Gerlach, Herwig; Hidalgo, Jorge Luis; Hollenberg, Steven M.; Jones, Alan E.; Karnad, Dilip R.; Kleinpell, Ruth M.; Koh, Younsuck; Lisboa, Thiago Costa; Machado, Flavia R.; Marini, John J.; Marshall, John C.; Mazuski, John E.; McIntyre, Lauralyn A.; McLean, Anthony S.; Mehta, Sangeeta; Moreno, Rui P.; Myburgh, John; Navalesi, Paolo; Nishida, Osamu; Osborn, Tiffany M.; Perner, Anders; Plunkett, Colleen M.; Ranieri, Marco; Schorr, Christa A.; Seckel, Maureen A.; Seymour, Christopher W.; Shieh, Lisa; Shukri, Khalid A.; Simpson, Steven Q.; Singer, Mervyn; Thompson, B. Taylor; Townsend, Sean R.; van der Poll, Thomas; Vincent, Jean-Louis; Wiersinga, W. Joost; Zimmerman, Janice L.; Dellinger, R. Phillip

    2017-01-01

    Objective: To provide an update to "Surviving Sepsis Campaign Guidelines for Management of Sepsis and Septic Shock: 2012!' Design: A consensus committee of 55 international experts representing 25 international organizations was convened. Nominal groups were assembled at key international meetings

  5. Comparison of geometrical shock dynamics and kinematic models for shock-wave propagation

    Science.gov (United States)

    Ridoux, J.; Lardjane, N.; Monasse, L.; Coulouvrat, F.

    2018-03-01

    Geometrical shock dynamics (GSD) is a simplified model for nonlinear shock-wave propagation, based on the decomposition of the shock front into elementary ray tubes. Assuming small changes in the ray tube area, and neglecting the effect of the post-shock flow, a simple relation linking the local curvature and velocity of the front, known as the A{-}M rule, is obtained. More recently, a new simplified model, referred to as the kinematic model, was proposed. This model is obtained by combining the three-dimensional Euler equations and the Rankine-Hugoniot relations at the front, which leads to an equation for the normal variation of the shock Mach number at the wave front. In the same way as GSD, the kinematic model is closed by neglecting the post-shock flow effects. Although each model's approach is different, we prove their structural equivalence: the kinematic model can be rewritten under the form of GSD with a specific A{-}M relation. Both models are then compared through a wide variety of examples including experimental data or Eulerian simulation results when available. Attention is drawn to the simple cases of compression ramps and diffraction over convex corners. The analysis is completed by the more complex cases of the diffraction over a cylinder, a sphere, a mound, and a trough.

  6. Shock ignition: modelling and target design robustness

    Energy Technology Data Exchange (ETDEWEB)

    Ribeyre, X; Lafon, M; Schurtz, G; Olazabal-Loume, M; Breil, J; Galera, S; Weber, S, E-mail: ribeyre@celia.u-bordeaux1.f [Centre Lasers Intenses et Applications, Universite Bordeaux 1, CNRS, CEA, Universite Bordeaux 1, 351, cours de la Liberation, 33405 Talence (France)

    2009-12-15

    Shock ignition of a pre-compressed deuterium tritium fuel is considered here. When properly timed, a converging shock launched in the target prior to stagnation time strongly enhances the hot spot pressure. This allows ignition to be reached in a nonisobaric configuration. We show in this work that the igniting mechanism is pressure amplification by shock convergence and shock collision. The shock ignition applied to the HiPER target allows one to study the robustness of this method. It is shown that the spike energy is not a critical parameter and that the spike power delivered on the target depends mainly on the shell implosion velocity. Finally, a family of homothetic targets ignited with a shock wave is studied.

  7. out-of-n systems with shock model

    African Journals Online (AJOL)

    distributed. Sarhan, A.M. and Abouammoh (2000) used the shock model to derive the re- liability function of k-out-of-n systems with nonindependent and nonidentical components. They assumed that a system is subjected to n + m independent types of shocks. Liu et al. (2008) proposed a model to evaluate the reliability ...

  8. Modeling of energy transfer in hypersonic shocks using high fidelity models

    Science.gov (United States)

    Zhu, Tong

    The spectra of high-temperature, chemically reacting hypersonic flows provides the most powerful diagnostic available for testing thermochemically nonequilibrium models in re-entry conditions. Several shock tube experiments have revealed that conventional phenomenological approach can not accurately predict the internal temperature of the gas and also the corresponding radiation. In particular, large rotational nonequilibrium in strong shocks has been observed in several experiments with high peak translational temperatures. The Direct Simulation Monte Carlo (DSMC) method is a particlebased simulation method that is capable of properly simulating flows with large nonequilibrium. In the experiments above, one dimensional shocks are most widely studied but they are challenging to simulate using the DSMC method due to the unsteady nature of the flows and especially for hypersonic flows with chemical reactions taking place. Therefore, efficient approaches for simulating one-dimensional shocks are developed for use in DSMC simulations. Both a shock stabilization technique and a modified DSMC unsteady sampling approach are used in simulating one dimensional, unsteady shocks. In the latter approach, a moving sampling region is used to obtain an accurate profile of the reflected shock in air. The shock number density and temperature profiles are obtained and used to calculate excitation and radiation. The Quasi-Steady-State (QSS) assumption is made in the excitation calculation where both electron impact and heavy particle impact excitation for the NO(A2sum +) and the N+2 (B2sum +u ) states are studied. The calculated NOradiation in the wavelength range o lambda = 235 +/- 7 nm for shock speeds below 7 km/s are in good agreement with the experiment, but, the predicted radiation is lower than the experiment for shock speeds above 7 km/s. In addition, the N+2 radiation in the wavelength range of lambda = 391.4 +/- 0.2 nm are in good agreement with the experimental data for

  9. Shocks Abroad, Pain at Home? Bank-firm Level Evidence on the International Transmission of Financial Shocks

    NARCIS (Netherlands)

    Ongena, S.; Peydro, J.L.; van Horen, N.

    2013-01-01

    Abstract: We study the international transmission of shocks from the banking to the real sector during the global financial crisis. For identification, we use matched bank-firm level data, including many small and medium-sized firms, in Eastern Europe and Central Asia. We find that

  10. Shock metamorphism in the Vredefort Collar: Evidence for internal shock sources

    Science.gov (United States)

    Lilly, P. A.

    1981-11-01

    Shock metamorphic microstructures in the Vredefort collar include planar features, crystallographically controlled cleavage, crystallographically controlled faults, and mosaic extinction. In addition, several recrystallization textures are developed in the quartzites of the collar, and quartz c axis distributions for both primary and recrystallized quartz grains are random. The degree of recrystallization decreases away from the core-collar contact. Two events of shock deformation have been identified in the collar, and using planar feature orientations, shock pressures have been estimated using the technique of Robertson (1975). The first shock (D1) subjected the lowermost Witwatersrand rocks to shock pressures of about 150 kbar and the uppermost beds to pressures of about 60 kbar. Following a period of extensive recrystallization of the quartzites came the second shock event (D2), which was weaker than the first and subjected the lowermost strata in the collar to pressures of between 75 and 100 kbar. The D2 event has been shown to be separated in time from the D1 event. The results are used to show that the shock sources were probably within the earth and that the Vredefort ring structure has formed as a result of endogenous processes rather than hypervelocity meteorite impact.

  11. Effect of continuous hemofiltration on internal environment and survival rate of severe heatstroke dogs with shock

    Directory of Open Access Journals (Sweden)

    Guang-ming CHEN

    2011-08-01

    Full Text Available Objective To explore the effect of continuous hemofiltration(CHF on internal environment and survival rate of severe heatstroke dogs with shock.Methods Sixteen healthy male dogs were randomly divided into heatshock group(HS group,n=8 and continuous hemofiltration group(CHF group,n=8.Severe heatstroke model was established by applying high temperature to whole body,and then the animals were removed from the heating cabin as soon as they presented manifestations of shock.Dogs of HS group were put into an ordinary environment,while dogs of CHF group received CHF treatment.The core temperature(Tc,mean arterial pressure(MAP,blood gas analysis,serum electrolytes and survival rate of dogs in two groups were observed.Results The time from heat exposure to shock was 107.0±28.5min and 111.4±22.2min in HS group and CHF group respectively(t=-0.354,P=0.729.The Tc in CHF group declined to normal level 15 to 30 minitues after CHF treatment,while the Tc in HS group remained at a level higher than that before heat exposure at 90min after shock.The Tc of two groups showed significant difference at each time point after shock(P < 0.01.The MAP of both groups was obviously lowered than that before heatstroke.The MAP of CHF group raised gradually 30 min after treatment,while the MAP of HS group rose very slowly,and it was significantly lower than that of CHF group at each time point after 45min(P < 0.05,P < 0.01.All the dogs in both groups manifested hyperventilation and respiratory alkalosis when shock appeared.After shock,respiratory alkalosis in HS group gradually became metabolic acidosis,with some animals manifested combined metabolic and respiratory acidosis because of respiratory decompensation,while the blood gas levels in CHF group recovered to normal gradually.The blood gas levels of two groups showed significant difference at each time point after shock(P < 0.05,P < 0.01.Hypernatremia,hyperchloraemia and hyperpotassaemia were found in all animals of both

  12. American nursing students experience shock during a short-term international program.

    Science.gov (United States)

    Heuer, L J; Bengiamin, M I

    2001-01-01

    When individuals plan to travel internationally, they frequently assume that they will have an enjoyable and memorable experience. But for some, the effects of culture shock may negatively impact their travels and memories. The purpose of this study was to describe culture shock as reported by student nurses who took part in an international short-term program. A phenomenological approach was utilized to elicit the essence of meaning attached to the experience. Eight student nurses in an upper Midwestern university, participated in this international experience. It was concluded that all of the student nurses experienced culture shock to a varying degree and they had varying perceptions of their experiences.

  13. The Propagation of Shocks Across International Equity Markets : A Microstructure Perspective

    NARCIS (Netherlands)

    D.G.J. Bongaerts (Dion); R. Roll (Richard); D.M. Rösch (Dominik); M.A. van Dijk (Mathijs); D. Yuferova (Darya)

    2014-01-01

    textabstractWe study the high-frequency propagation of shocks across international equity markets. We identify shocks to stock prices, liquidity (quoted and effective spreads), and trading activity (turnover and order imbalance) for 12 equity markets around the world based on non-parametric jump

  14. Detonation Shock Dynamics Modelling with Arbitrary Boundaries

    Science.gov (United States)

    Hodgson, Alexander

    2017-06-01

    The Detonation Shock Dynamics (DSD) model can be used to predict detonation wave propagation in a high explosive (HE). The detonation wave is prescribed a velocity that depends on its curvature. Additionally, the angle between the wave and the HE boundary may not exceed a specified ``boundary angle'', the value of which depends on the HE and its confining material(s). The level-set method is commonly used to drive DSD computation. Boundary conditions are applied to the level-set field at the charge edges to maintain the explosive boundary angle criteria. The position of the boundary must be accurate and continuous across adjacent cells to achieve accurate and robust results. This is mainly an issue for mixed material meshes where the boundary does not coincide with the cell boundaries. For such meshes, a set of volume fractions defines the amount of material in each cell. The boundary is defined implicitly by the volume fractions, and must be reconstructed to an explicit form for use in DSD. This work describes a novel synthesis of the level-set method and simulated annealing, an optimisation method used to reconstruct the boundary. The accuracy and robustness of the resulting DSD calculation are evaluated with a range of test problems.

  15. Models og International Entrepreneurship

    DEFF Research Database (Denmark)

    Rask, Morten; Servais, Per

    2015-01-01

    on International Entrepreneurship, and specifically but not exclusively, International New Ventures (INVs). The three resulting ‘meta-models’ depict the activities and loci of such firms, the motivating factors that give rise to such firms and their growth modalities and strategies. These models reflect the merger...... of entrepreneurship and international business into the field of international entrepreneurship....

  16. Modeling of Particle Acceleration at Multiple Shocks via Diffusive Shock Acceleration: Preliminary Results

    Science.gov (United States)

    Parker, L. Neergaard; Zank, G. P.

    2013-01-01

    Successful forecasting of energetic particle events in space weather models require algorithms for correctly predicting the spectrum of ions accelerated from a background population of charged particles. We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box. We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (E(sub max)) appropriate for quasi-parallel and quasi-perpendicular shocks and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

  17. Models of international entrepreneurship

    DEFF Research Database (Denmark)

    Rask, Morten; Servais, Per

    2012-01-01

    The purpose with this article is to review models used to describe and explain the establishment and development of international new ventures in order to investigate how and why international new ventures are established and developed. This article attempts an integration of extant theory...... on International Entrepreneurship, and specifically but not exclusively, International New Ventures (INVs). The three resulting ‘meta-models’ depict the activities and loci of such firms (Figure 1), the motivating factors that give rise to such firms (Figure 2) and their growth modalities and strategies (Figure 3......). These models reflect the merger of entrepreneurship and international business into the field of international entrepreneurship. Managers in international entrepreneurial firms and students in international business and entrepreneurship can use the models as framework for understanding international...

  18. Thermal shock analysis of functionally graded materials by micromechanical model

    International Nuclear Information System (INIS)

    Ueda, Sei

    2002-01-01

    The transient thermoelastic behavior of the functionally graded plate due to a thermal shock with temperature dependent properties is studied in this paper. The development of a micromechanical model for the functionally graded materials is presented and its application to thermoelastic analysis is discussed for the case of the W-Cu functionally graded material for the International Thermonuclear Experimental Reactor divertor plate. The divertor plate is made of a graded layer bonded between a homogeneous substrate and a homogeneous coating, and it is subjected to a cycle of heating and cooling on the coating surface of the material. The thermal and elastic properties of the material are dependent on the temperature and the position. Numerical calculations are carried out, and the results for the transient temperature and thermal stress distributions are displayed graphically. (author)

  19. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).

    Science.gov (United States)

    Singer, Mervyn; Deutschman, Clifford S; Seymour, Christopher Warren; Shankar-Hari, Manu; Annane, Djillali; Bauer, Michael; Bellomo, Rinaldo; Bernard, Gordon R; Chiche, Jean-Daniel; Coopersmith, Craig M; Hotchkiss, Richard S; Levy, Mitchell M; Marshall, John C; Martin, Greg S; Opal, Steven M; Rubenfeld, Gordon D; van der Poll, Tom; Vincent, Jean-Louis; Angus, Derek C

    2016-02-23

    Definitions of sepsis and septic shock were last revised in 2001. Considerable advances have since been made into the pathobiology (changes in organ function, morphology, cell biology, biochemistry, immunology, and circulation), management, and epidemiology of sepsis, suggesting the need for reexamination. To evaluate and, as needed, update definitions for sepsis and septic shock. A task force (n = 19) with expertise in sepsis pathobiology, clinical trials, and epidemiology was convened by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine. Definitions and clinical criteria were generated through meetings, Delphi processes, analysis of electronic health record databases, and voting, followed by circulation to international professional societies, requesting peer review and endorsement (by 31 societies listed in the Acknowledgment). Limitations of previous definitions included an excessive focus on inflammation, the misleading model that sepsis follows a continuum through severe sepsis to shock, and inadequate specificity and sensitivity of the systemic inflammatory response syndrome (SIRS) criteria. Multiple definitions and terminologies are currently in use for sepsis, septic shock, and organ dysfunction, leading to discrepancies in reported incidence and observed mortality. The task force concluded the term severe sepsis was redundant. Sepsis should be defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. For clinical operationalization, organ dysfunction can be represented by an increase in the Sequential [Sepsis-related] Organ Failure Assessment (SOFA) score of 2 points or more, which is associated with an in-hospital mortality greater than 10%. Septic shock should be defined as a subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone. Patients with septic shock

  20. Models og International Entrepreneurship

    DEFF Research Database (Denmark)

    Rask, Morten; Servais, Per

    2015-01-01

    The purpose with this article is to review models used to describe and explain the establishment and development of international new ventures in order to investigate how and why international new ventures are established and developed. This article attempts an integration of extant theory...... on International Entrepreneurship, and specifically but not exclusively, International New Ventures (INVs). The three resulting ‘meta-models’ depict the activities and loci of such firms, the motivating factors that give rise to such firms and their growth modalities and strategies. These models reflect the merger...... of entrepreneurship and international business into the field of international entrepreneurship....

  1. "Financial-Sector Shocks in a Credit-View Model"

    OpenAIRE

    Burton A. Abrams

    2011-01-01

    A variation of the Bernanke-Blinder credit-view model reveals that holding constant the money supply following various financial-sector shocks, including an autonomous drop in the money multiplier, is insufficient to prevent aggregate demand from decreasing.

  2. Modeling of Shock Propagation and Attenuation in Viscoelastic Components

    Directory of Open Access Journals (Sweden)

    R. Rusovici

    2001-01-01

    Full Text Available Protection from the potentially damaging effects of shock loading is a common design requirement for diverse mechanical structures ranging from shock accelerometers to spacecraft. High damping viscoelastic materials are employed in the design of geometrically complex, impact-absorbent components. Since shock transients are characterized by a broad frequency spectrum, it is imperative to properly model frequency dependence of material behavior over a wide frequency range. The Anelastic Displacement Fields (ADF method is employed herein to model frequency-dependence within a time-domain finite element framework. Axisymmetric, ADF finite elements are developed and then used to model shock propagation and absorption through viscoelastic structures. The model predictions are verified against longitudinal wave propagation experimental data and theory.

  3. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016

    NARCIS (Netherlands)

    Rhodes, Andrew; Evans, Laura E.; Alhazzani, Waleed; Levy, Mitchell M.; Antonelli, Massimo; Ferrer, Ricard; Kumar, Anand; Sevransky, Jonathan E.; Sprung, Charles L.; Nunnally, Mark E.; Rochwerg, Bram; Rubenfeld, Gordon D.; Angus, Derek C.; Annane, Djillali; Beale, Richard J.; Bellinghan, Geoffrey J.; Bernard, Gordon R.; Chiche, Jean-Daniel; Coopersmith, Craig; de Backer, Daniel P.; French, Craig J.; Fujishima, Seitaro; Gerlach, Herwig; Hidalgo, Jorge Luis; Hollenberg, Steven M.; Jones, Alan E.; Karnad, Dilip R.; Kleinpell, Ruth M.; Koh, Younsuk; Lisboa, Thiago Costa; Machado, Flavia R.; Marini, John J.; Marshall, John C.; Mazuski, John E.; McIntyre, Lauralyn A.; McLean, Anthony S.; Mehta, Sangeeta; Moreno, Rui P.; Myburgh, John; Navalesi, Paolo; Nishida, Osamu; Osborn, Tiffany M.; Perner, Anders; Plunkett, Colleen M.; Ranieri, Marco; Schorr, Christa A.; Seckel, Maureen A.; Seymour, Christopher W.; Shieh, Lisa; Shukri, Khalid A.; Simpson, Steven Q.; Singer, Mervyn; Thompson, B. Taylor; Townsend, Sean R.; van der Poll, Thomas; Vincent, Jean-Louis; Wiersinga, W. Joost; Zimmerman, Janice L.; Dellinger, R. Phillip

    2017-01-01

    To provide an update to "Surviving Sepsis Campaign Guidelines for Management of Sepsis and Septic Shock: 2012". A consensus committee of 55 international experts representing 25 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee

  4. On the Consistency of Gamma-Ray Burst Spectral Indices with the Synchrotron Shock Model

    Science.gov (United States)

    Preece, R. D.; Briggs, M. S.; Giblin, T. W.; Mallozzi, R. S.; Pendleton, G. N.; Paciesad, W. S.; Band, D. L.

    2002-01-01

    The current scenario for gamma-ray bursts (GRBs) involves internal shocks for the prompt GRB emission phase and external shocks for the afterglow phase. Assuming optically thin synchrotron emission from isotropically distributed energetic shocked electrons, GRB spectra observed with a low-energy power-law spectral index greater than -2/3 (for positive photon number indices E(exp alpha) indicate a problem with this model. For spectra that do not violate this condition, additional tests of the shock model can be made by comparing the low- and high-energy spectral indices, on the basis of the model's assertion that synchrotron emission from a single power-law distribution of electrons is responsible for both the low-energy and the high-energy power-law portions of the spectra. We find in most cases that the inferred relationship between the two spectral indices of observed GRB spectra is inconsistent with the constraints from the simple optically thin synchrotron shock emission model. In this sense, the prompt burst phase is different from the afterglow phase, and this difference may be related to anisotropic distributions of particles or to their continual acceleration in shocks during the prompt phase.

  5. SME International Business Models

    DEFF Research Database (Denmark)

    Child, John; Hsieh, Linda; Elbanna, Said

    2017-01-01

    This paper addresses two questions through a study of 180 SMEs located in contrasting industry and home country contexts. First, which business models for international markets prevail among SMEs and do they configure into different types? Second, which factors predict the international business...... models that SMEs follow? Three distinct international business models (traditional market-adaptive, technology exploiter, and ambidextrous explorer) are found among the SMEs studied. The likelihood of SMEs adopting one business model rather than another is to a high degree predictable with reference...... to a small set of factors: industry, level of home economy development, and decision-maker international experience....

  6. Shock Acceleration Model for the Toothbrush Radio Relic

    Science.gov (United States)

    Kang, Hyesung; Ryu, Dongsu; Jones, T. W.

    2017-05-01

    Although many of the observed properties of giant radio relics detected in the outskirts of galaxy clusters can be explained by relativistic electrons accelerated at merger-driven shocks, significant puzzles remain. In the case of the so-called Toothbrush relic, the shock Mach number estimated from X-ray observations ({M}{{X}}≈ 1.2{--}1.5) is substantially weaker than that inferred from the radio spectral index ({M}{rad}≈ 2.8). Toward understanding such a discrepancy, we here consider the following diffusive shock acceleration (DSA) models: (1) weak-shock models with {M}{{s}}≲ 2 and a preexisting population of cosmic-ray electrons (CRe) with a flat energy spectrum, and (2) strong-shock models with {M}{{s}}≈ 3 and either shock-generated suprathermal electrons or preexisting fossil CRe. We calculate the synchrotron emission from the accelerated CRe, following the time evolution of the electron DSA, and the subsequent radiative cooling and postshock turbulent acceleration (TA). We find that both models could reproduce reasonably well the observed integrated radio spectrum of the Toothbrush relic, but the observed broad transverse profile requires the stochastic acceleration by downstream turbulence, which we label “turbulent acceleration” or TA to distinguish it from DSA. Moreover, to account for the almost uniform radio spectral index profile along the length of the relic, the weak-shock models require a preshock region over 400 kpc with a uniform population of preexisting CRe with a high cutoff energy (≳ 40 {GeV}). Due to the short cooling time, it is challenging to explain the origin of such energetic electrons. Therefore, we suggest the strong-shock models with low-energy seed CRe (≲ 150 {MeV}) are preferred for the radio observations of this relic.

  7. Uncertainty shocks in a model of effective demand

    OpenAIRE

    Bundick, Brent; Basu, Susanto

    2014-01-01

    Can increased uncertainty about the future cause a contraction in output and its components? An identified uncertainty shock in the data causes significant declines in output, consumption, investment, and hours worked. Standard general-equilibrium models with flexible prices cannot reproduce this comovement. However, uncertainty shocks can easily generate comovement with countercyclical markups through sticky prices. Monetary policy plays a key role in offsetting the negative impact of uncert...

  8. A Conditional Approach to Panel Data Models with Common Shocks

    Directory of Open Access Journals (Sweden)

    Giovanni Forchini

    2016-01-01

    Full Text Available This paper studies the effects of common shocks on the OLS estimators of the slopes’ parameters in linear panel data models. The shocks are assumed to affect both the errors and some of the explanatory variables. In contrast to existing approaches, which rely on using results on martingale difference sequences, our method relies on conditional strong laws of large numbers and conditional central limit theorems for conditionally-heterogeneous random variables.

  9. Numerical investigation of turbulence models for shock separated boundary-layer flows

    Science.gov (United States)

    Viegas, J. R.; Coakley, T. J.

    1977-01-01

    Numerical solutions of the Navier-Stokes equations for shock separated turbulent boundary-layer flows are presented. Several turbulence models are investigated and assessed by their ability to predict the physical phenomena associated with two extensively documented experiments. The experimental flows consist of shock-wave boundary-layer interactions in axisymmetric internal and external geometries at Mach numbers of 1.5 and 7, respectively. Algebraic and one-equation eddy viscosity models are used to describe the Reynolds shear stress. Calculated values of skin friction, wall pressure distribution, kinetic energy of turbulence, and heat transfer are compared with measurements.

  10. Broadband Shock Noise in Internally-Mixed Dual-Stream Jets

    Science.gov (United States)

    Bridges, James E.

    2009-01-01

    Broadband shock noise (BBSN) has been studied in some detail in single-flow jets and recently in dual-stream jets with separate flow exhaust systems. Shock noise is of great concern in these latter cases because of the noise created for the aircraft cabin by the underexpanded nozzle flow at cruise. Another case where shock noise is of concern is in the case of future supersonic aircraft that are expected to have bypass ratios small enough to justify internally mixed exhaust systems, and whose mission will push cycles to the point of imperfectly expanded flows. Dual-stream jets with internally mixed plume have some simplifying aspects relative to the separate flow jets, having a single shock structure given by the common nozzle pressure. This is used to separate the contribution of the turbulent shear layer to the broadband shock noise. Shock structure is held constant while the geometry and strength of the inner and merged shear layers are varying by changing splitter area ratio and core stream temperature. Flow and noise measurements are presented which document the efforts at separating the contribution of the inner shear layer to the broadband shock noise.

  11. Investigation of external and internal shock in the stability of Indonesia’s financial system

    Directory of Open Access Journals (Sweden)

    Maulina Vinus

    2017-07-01

    Full Text Available The objective of this research is to develop a financial system stability index and analyze the internal and external factors that we expect to affect the stability of the Indonesian financial system. We measured the single model of financial system stability index (FSSI from year 2004M03 to2014M09 in Indonesia, and compiled a single quantitative measure based on aggregate internal factors and external factors to capture and predict the shocks of the financial system stability. Stability parameters were composed of composite indicators on different bases. In addition, we developed a comprehensive index component associated with the relevant market conditions, including banking soundness index, financial vulnerability index, and regional economic climate index. Results stated that US economic growth and economic growth of ASEAN countries positively affected financial stability. In addition, current account, exchange rate, inflation, interest rate were shown to negatively affect financial stability. The results of this study imply that internal factors have a strong influence on the financial stability. Therefore, the central bank should give a fast and correct response to the changes of external and internal financial environment, especially for internal factors through monetary policy.

  12. Culture shock and international students on the example of Erasmus program in Prague

    OpenAIRE

    Bezushchenko, Polina

    2017-01-01

    This thesis covers the problem of culture shock that is nowadays becoming more and more popular, since our world is the world of both extensive and intensive integration and globalization. The aim of the work is to analyze how much international students in Prague are affected by culture shock. The first part of the thesis provides the deep information about the concept of culture shock. The second part of the work comprises the survey which was done by the mean of the questionnaire. The resu...

  13. EXPLOMET 90 International Conference on Shock-Wave and High-Strain-Rate Phenomena in Materials

    Science.gov (United States)

    1992-01-10

    Instituto Militar de Engenharia , Rio de Janeiro, BRASIL M. A. Meyers, University of California, San Diego, La Jolla, CA 6. EFFECT OF INTERN?.1.. GAS PRESSURE...Instituto Militar de Engenharia . Rio oe Janeiro, RJ, BRASIL 9. TRANSFORMATION AND STRUCTURAL CHANGES IN METALS UNDER SHOCK AND DYNAMIC LOADING C. Feng...Rios, and A. W. Romero, Instituto Militar de Engenharia , Rio de Janeiro, BRASIL 5. SPALLING OF ALUMINUM AND COPPER TARGETS BY LASER-SHOCKS M_ Boie, and

  14. Shock, release and reshock of PBX 9502: experiments and modeling

    Science.gov (United States)

    Aslam, Tariq; Gustavsen, Richard; Whitworh, Nicholas; Menikoff, Ralph; Tarver, Craig; Handley, Caroline; Bartram, Brian

    2017-06-01

    We examine shock, release and reshock into the tri-amino-tri-nitro-benzene (TATB) based explosive PBX 9502 (95% TATB, 5% Kel-F 800) from both an experimental and modeling point of view. The experiments are performed on the 2-stage light gas gun at Los Alamos National Laboratory and are composed of a multi-layered impactor impinging on PBX 9502 backed by a polymethylmethacrylate window. The objective is to initially shock the PBX 9502 in the 7 GPa range (too weak to start significant reaction), then allow a rarefaction fan to release the material to a lower pressure/temperature state. Following this release, a strong second shock will recompress the PBX. If the rarefaction fan releases the PBX to a very low pressure, the ensuing second shock can increase the entropy and temperature substantially more than in previous double-shock experiments without an intermediate release. Predictions from a variety of reactive burn models (AWSD, CREST, Ignition and Growth, SURF) demonstrate significantly different behaviors and thus the experiments are an excellent validation test of the models, and may suggest improvements for subsequent modeling efforts.

  15. 3D Smoothed Particle Hydrodynamics Models of Betelgeuse's Bow Shock

    Science.gov (United States)

    Mohamed, S.; Mackey, J.; Langer, N.

    2013-05-01

    Betelgeuse, the bright red supergiant (RSG) in Orion, is a runaway star. Its supersonic motion through the interstellar medium has resulted in the formation of a bow shock, a cometary structure pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. We show that the bow shock morphology depends substantially on the growth timescale for Rayleigh-Taylor versus Kelvin-Helmholtz instabilities. We discuss our models in light of the recent Herschel, GALEX and VLA observations. If the mass in the bow shock shell is low (~few × 10-3 M⊙), as seems to be implied by the AKARI and Herschel observations, then Betelgeuse's bow shock is very young and is unlikely to have reached a steady state. The circular, smooth bow shock shell is consistent with this conclusion. We further discuss the implications of our results, in particular, the possibility that Betelgeuse may have only recently entered the RSG phase.

  16. Modeling Internal Radiation Therapy

    NARCIS (Netherlands)

    van den Broek, Egon; Schouten, Theo E.; Pellegrini, M.; Fred, A.; Filipe, J.; Gamboa, H.

    2011-01-01

    A new technique is described to model (internal) radiation therapy. It is founded on morphological processing, in particular distance transforms. Its formal basis is presented as well as its implementation via the Fast Exact Euclidean Distance (FEED) transform. Its use for all variations of internal

  17. Neutrino and cosmic-ray emission from multiple internal shocks in gamma-ray bursts.

    Science.gov (United States)

    Bustamante, Mauricio; Baerwald, Philipp; Murase, Kohta; Winter, Walter

    2015-04-10

    Gamma-ray bursts (GRBs) are short-lived, luminous explosions at cosmological distances, thought to originate from relativistic jets launched at the deaths of massive stars. They are among the prime candidates to produce the observed cosmic rays at the highest energies. Recent neutrino data have, however, started to constrain this possibility in the simplest models with only one emission zone. In the classical theory of GRBs, it is expected that particles are accelerated at mildly relativistic shocks generated by the collisions of material ejected from a central engine. Here we consider neutrino and cosmic-ray emission from multiple emission regions since these internal collisions must occur at very different radii, from below the photosphere all the way out to the circumburst medium, as a consequence of the efficient dissipation of kinetic energy. We demonstrate that the different messengers originate from different collision radii, which means that multi-messenger observations open windows for revealing the evolving GRB outflows.

  18. Multiphase Modeling of Secondary Atomization in a Shock Environment

    Science.gov (United States)

    St. Clair, Jeffrey; McGrath, Thomas; Balachandar, Sivaramakrishnan

    2017-06-01

    Understanding and developing accurate modeling strategies for shock-particulate interaction remains a challenging and important topic, with application to energetic materials development, volcanic eruptions, and safety/risk assessment. This work presents computational modeling of compressible multiphase flows with shock-induced droplet atomization. Droplet size has a strong influence on the interphase momentum and heat transfer. A test case is presented that is sensitive to this, requiring the dynamic modeling of the secondary atomization process occurring when the shock impacts the droplets. An Eulerian-Eulerian computational model that treats all phases as compressible, is hyperbolic and satisfies the 2nd Law of Thermodynamics is applied. Four different breakup models are applied to the test case in which a planar shock wave encounters a cloud of water droplets. The numerical results are compared with both experimental and previously-generated modeling results. The effect of the drag relation used is also investigated. The computed results indicate the necessity of using a droplet breakup model for this application, and the relative accuracy of results obtained with the different droplet breakup and drag models is discussed.

  19. Insoluble glycogen, a metabolizable internal adsorbent, decreases the lethality of endotoxin shock in rats

    Directory of Open Access Journals (Sweden)

    S. Sipka

    1997-01-01

    Full Text Available Insoluble glycogen is an enzymatically modified form of naturally occurring soluble glycogen with a great adsorbing capacity. It can be metabolized by phagocytes to glucose. In this study we used insoluble glycogen intravenously in the experimental endotoxin shock of rats. Wistar male rats were sensitized to endotoxin by Pb acetate. The survival of rats were compared in groups of animals endotoxin shock treated and non-treated with insoluble glycogen. Furthermore, we have determined in vitro the binding capacity of insoluble glycogen for endotoxin, tumour necrosis factor alpha, interleukin-1 and secretable phospholipase A2. Use of 10 mg/kg dose of insoluble glycogen could completely prevent the lethality of shock induced by LD50 quantity of endotoxin in rats. All animals treated survived. Insoluble glycogen is a form of ‘metabolizable internal adsorbents’. It can potentially be used for treatment of septic shock.

  20. "Library shock" - the expectations and realities of library and information literacy skills for international students

    OpenAIRE

    Lahlafi, Alison; Bullingham, Liam

    2012-01-01

    This article seeks to conceptualise the culture shock experienced by international students studying in UK higher education within the context of the Adsetts Learning Centre at Sheffield Hallam University (SHU). The authors also aim to further understanding in this area by discussing the information literacy skills of international students at SHU. The discussion is informed by the results of a conference presentation activity for SHU staff and a short survey of a small group of international...

  1. A two-temperature model for shocked porous explosive

    Science.gov (United States)

    Lambourn, Brian; Handley, Caroline

    2017-01-01

    Mesoscale calculations of hotpots created by a shock wave in a porous explosive show that the hotspots do not cool in times of order at least a microsecond. This suggests that simple models of porosity like the Snowplough model, which assume that a shocked porous explosive jumps to a point on the Hugoniot that is instantaneously in thermodynamic equilibrium, are not correct. A two-temperature model of shocked porous explosive has been developed in which a small fraction of the material, representing the hotspots, has a high temperature, but the bulk of the material is cooler than the temperature calculated by the Snowplough model. In terms of the mean state of the material, it is shown that the two-temperature model only minimally affects the pressure vs. volume and shock velocity vs. particle velocity plot of the Hugoniot, but that the mean state lies slightly off the equation of state surface. The results of the model are compared with two dimensional mesoscale calculations.

  2. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)

    Science.gov (United States)

    Singer, Mervyn; Deutschman, Clifford S.; Seymour, Christopher Warren; Shankar-Hari, Manu; Annane, Djillali; Bauer, Michael; Bellomo, Rinaldo; Bernard, Gordon R.; Chiche, Jean-Daniel; Coopersmith, Craig M.; Hotchkiss, Richard S.; Levy, Mitchell M.; Marshall, John C.; Martin, Greg S.; Opal, Steven M.; Rubenfeld, Gordon D.; van der Poll, Tom; Vincent, Jean-Louis; Angus, Derek C.

    2016-01-01

    IMPORTANCE Definitions of sepsis and septic shock were last revised in 2001. Considerable advances have since been made into the pathobiology (changes in organ function, morphology, cell biology, biochemistry, immunology, and circulation), management, and epidemiology of sepsis, suggesting the need for reexamination. OBJECTIVE To evaluate and, as needed, update definitions for sepsis and septic shock. PROCESS A task force (n = 19) with expertise in sepsis pathobiology, clinical trials, and epidemiology was convened by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine. Definitions and clinical criteria were generated through meetings, Delphi processes, analysis of electronic health record databases, and voting, followed by circulation to international professional societies, requesting peer review and endorsement (by 31 societies listed in the Acknowledgment). KEY FINDINGS FROMEVIDENCE SYNTHESIS Limitations of previous definitions included an excessive focus on inflammation, the misleading model that sepsis follows a continuum through severe sepsis to shock, and inadequate specificity and sensitivity of the systemic inflammatory response syndrome (SIRS) criteria. Multiple definitions and terminologies are currently in use for sepsis, septic shock, and organ dysfunction, leading to discrepancies in reported incidence and observed mortality. The task force concluded the term severe sepsis was redundant. RECOMMENDATIONS Sepsis should be defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. For clinical operationalization, organ dysfunction can be represented by an increase in the Sequential [Sepsis-related] Organ Failure Assessment (SOFA) score of 2 points or more, which is associated with an in-hospital mortality greater than 10%. Septic shock should be defined as a subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a

  3. Electroporation induced by internal defibrillation shock with and without recovery in intact rabbit hearts

    Science.gov (United States)

    Wang, Yves T.; Efimov, Igor R.

    2012-01-01

    Defibrillation shocks from implantable cardioverter defibrillators can be lifesaving but can also damage cardiac tissues via electroporation. This study characterizes the spatial distribution and extent of defibrillation shock-induced electroporation with and without a 45-min postshock period for cell membranes to recover. Langendorff-perfused rabbit hearts (n = 31) with and without a chronic left ventricular (LV) myocardial infarction (MI) were studied. Mean defibrillation threshold (DFT) was determined to be 161.4 ± 17.1 V and 1.65 ± 0.44 J in MI hearts for internally delivered 8-ms monophasic truncated exponential (MTE) shocks during sustained ventricular fibrillation (>20 s, SVF). A single 300-V MTE shock (twice determined DFT voltage) was used to terminate SVF. Shock-induced electroporation was assessed by propidium iodide (PI) uptake. Ventricular PI staining was quantified by fluorescent imaging. Histological analysis was performed using Masson's Trichrome staining. Results showed PI staining concentrated near the shock electrode in all hearts. Without recovery, PI staining was similar between normal and MI groups around the shock electrode and over the whole ventricles. However, MI hearts had greater total PI uptake in anterior (P < 0.01) and posterior (P < 0.01) LV epicardial regions. Postrecovery, PI staining was reduced substantially, but residual staining remained significant with similar spacial distributions. PI staining under SVF was similar to previously studied paced hearts. In conclusion, electroporation was spatially correlated with the active region of the shock electrode. Additional electroporation occurred in the LV epicardium of MI hearts, in the infarct border zone. Recovery of membrane integrity postelectroporation is likely a prolonged process. Short periods of SVF did not affect electroporation injury. PMID:22730387

  4. International students. Culture shock can affect the health of students from abroad.

    Science.gov (United States)

    Hamboyan, H.; Bryan, A. K.

    1995-01-01

    Family physicians and other health care workers who have international students as patients should have a thorough understanding of their circumstances in order to manage their health problems effectively. These students often experience culture shock that could lead to serious psychosocial difficulties and mental health problems. PMID:8829581

  5. International students. Culture shock can affect the health of students from abroad.

    OpenAIRE

    Hamboyan, H.; Bryan, A. K.

    1995-01-01

    Family physicians and other health care workers who have international students as patients should have a thorough understanding of their circumstances in order to manage their health problems effectively. These students often experience culture shock that could lead to serious psychosocial difficulties and mental health problems.

  6. International students. Culture shock can affect the health of students from abroad.

    Science.gov (United States)

    Hamboyan, H; Bryan, A K

    1995-10-01

    Family physicians and other health care workers who have international students as patients should have a thorough understanding of their circumstances in order to manage their health problems effectively. These students often experience culture shock that could lead to serious psychosocial difficulties and mental health problems.

  7. Internal Shock Interactions in Propulsion/Airframe Integrated Three-Dimensional Sidewall Compression Scramjet Inlets

    Science.gov (United States)

    Holland, Scott D.; Perkins, John N.

    1992-01-01

    The advantages and design requirements of propulsion/airframe integration for high Mach number flight have led to extensive study of the three-dimensional sidewall compression scramjet inlet in recent years. Recent research publications have indicated testing over a broad range of Mach number (2 to 18) in a variety of test gases, such as air, helium, and tetrafluoromethane. Multiple experimental techniques have been employed to obtain detailed internal shock interaction data, performance data, and inlet starting limits. Computational fluid dynamics has been effectively used for preliminary parametric studies as well as in parallel with experiments to aid in the explanation of unusual or unexpected flow phenomena. Inlets of this genre afford a relatively simple, generic geometry while producing a highly complex, three-dimensional flow field dominated by shock/shock and shock/boundary layer interactions. While the importance of the viscous effects in high speed inlet interactions is recognized, the present work addresses in a parametric fashion the inviscid effects of leading edge sweep, sidewall compression, and inflow Mach number on the internal shock structure in terms of inlet compression and mass capture. In the process, the source of the of the Mach number invariance with leading edge sweep for a constant sidewall compression class of inlet is identified, and a previously undocumented spillage phenomenon in a constant effective wedge angle class of inlets is discussed.

  8. A multiple shock model for common cause failures using discrete Markov chain

    International Nuclear Information System (INIS)

    Chung, Dae Wook; Kang, Chang Soon

    1992-01-01

    The most widely used models in common cause analysis are (single) shock models such as the BFR, and the MFR. But, single shock model can not treat the individual common cause separately and has some irrational assumptions. Multiple shock model for common cause failures is developed using Markov chain theory. This model treats each common cause shock as separately and sequently occuring event to implicate the change in failure probability distribution due to each common cause shock. The final failure probability distribution is evaluated and compared with that from the BFR model. The results show that multiple shock model which minimizes the assumptions in the BFR model is more realistic and conservative than the BFR model. The further work for application is the estimations of parameters such as common cause shock rate and component failure probability given a shock,p, through the data analysis

  9. Surface Ship Shock Modeling and Simulation: Two-Dimensional Analysis

    Directory of Open Access Journals (Sweden)

    Young S. Shin

    1998-01-01

    Full Text Available The modeling and simulation of the response of a surface ship system to underwater explosion requires an understanding of many different subject areas. These include the process of underwater explosion events, shock wave propagation, explosion gas bubble behavior and bubble-pulse loading, bulk and local cavitation, free surface effect, fluid-structure interaction, and structural dynamics. This paper investigates the effects of fluid-structure interaction and cavitation on the response of a surface ship using USA-NASTRAN-CFA code. First, the one-dimensional Bleich-Sandler model is used to validate the approach, and second, the underwater shock response of a two-dimensional mid-section model of a surface ship is predicted with a surrounding fluid model using a constitutive equation of a bilinear fluid which does not allow transmission of negative pressures.

  10. Modeling the Propagation of Shock Waves in Metals

    Science.gov (United States)

    Howard, W. Michael

    2005-07-01

    We present modeling results for the propagation of strong shock waves in metals. In particular, we use an arbitrary Lagrange Eulerian (ALE3D) code to model the propagation of strong pressure waves (P ˜300 to 400 kbars) generated with high explosives in contact with aluminum cylinders. The aluminum cylinders are assumed to be both flat-topped and have large-amplitude curved surfaces. We use 3D Lagrange mechanics. For the aluminum we use a rate-independent Steinberg-Guinan model, where the yield strength and bulk modulus depends on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and bulk modulus is set to zero. The pressure is represented as a seven-term polynomial as a function of density. For the HMX-based high explosive, we use a JWL, with a program burn model that gives the correct detonation velocity and C-J pressure (P ˜ 390 kbars). For the case of the large-amplitude curved surface, we discuss the evolving shock structure in terms of the early shock propagation experiments by Sakharov. We also discuss the dependence of our results upon our material model for aluminum.

  11. 3D numerical modeling of YSO accretion shocks

    Directory of Open Access Journals (Sweden)

    Matsakos T.

    2014-01-01

    Full Text Available The dynamics of YSO accretion shocks is determined by radiative processes as well as the strength and structure of the magnetic field. A quasi-periodic emission signature is theoretically expected to be observed, but observations do not confirm any such pattern. In this work, we assume a uniform background field, in the regime of optically thin energy losses, and we study the multi-dimensional shock evolution in the presence of perturbations, i.e. clumps in the stream and an acoustic energy flux flowing at the base of the chromosphere. We perform 3D MHD simulations using the PLUTO code, modelling locally the impact of the infalling gas onto the chromosphere. We find that the structure and dynamics of the post-shock region is strongly dependent on the plasma-beta (thermal over magnetic pressure, different values of which may give distinguishable emission signatures, relevant for observations. In particular, a strong magnetic field effectively confines the plasma inside its flux tubes and leads to the formation of quasi-independent fibrils. The fibrils may oscillate out of phase and hence the sum of their contributions in the emission results in a smooth overall profile. On the contrary, a weak magnetic field is not found to have any significant effect on the shocked plasma and the turbulent hot slab that forms is found to retain its periodic signature.

  12. Frontiers in Anisotropic Shock-Wave Modeling

    Science.gov (United States)

    2012-02-01

    Nowadays, some models incorporate a user-defined subroutine within the commercial software (e.g., ABAQUS ) to take into account either a homogenous...I.; Razorenov, S. V.; Baumung, K. Impact Strength Properties of Nickel-Based Refractory Superalloys at Normal and Elevated Temperatures. Int. J

  13. Potential early predictors for outcomes of experimental hemorrhagic shock induced by uncontrolled internal bleeding in rats.

    Directory of Open Access Journals (Sweden)

    Zaid A Abassi

    Full Text Available Uncontrolled hemorrhage, resulting from traumatic injuries, continues to be the leading cause of death in civilian and military environments. Hemorrhagic deaths usually occur within the first 6 hours of admission to hospital; therefore, early prehospital identification of patients who are at risk for developing shock may improve survival. The aims of the current study were: 1. To establish and characterize a unique model of uncontrolled internal hemorrhage induced by massive renal injury (MRI, of different degrees (20-35% unilateral nephrectomy in rats, 2. To identify early biomarkers those best predict the outcome of severe internal hemorrhage. For this purpose, male Sprague Dawley rats were anesthetized and cannulas were inserted into the trachea and carotid artery. After abdominal laparotomy, the lower pole of the kidney was excised. During 120 minutes, hematocrit, pO2, pCO2, base excess, potassium, lactate and glucose were measured from blood samples, and mean arterial pressure (MAP was measured through arterial tracing. After 120 minutes, blood loss was determined. Statistical prediction models of mortality and amount of blood loss were performed. In this model, the lowest blood loss and mortality rate were observed in the group with 20% nephrectomy. Escalation of the extent of nephrectomy to 25% and 30% significantly increased blood loss and mortality rate. Two phases of hemodynamic and biochemical response to MRI were noticed: the primary phase, occurring during the first 15 minutes after injury, and the secondary phase, beginning 30 minutes after the induction of bleeding. A Significant correlation between early blood loss and mean arterial pressure (MAP decrements and survival were noted. Our data also indicate that prediction of outcome was attainable in the very early stages of blood loss, over the first 15 minutes after the injury, and that blood loss and MAP were the strongest predictors of mortality.

  14. Laser shock experiments to investigate and to model various aspects of the response of metals to shock loading

    Directory of Open Access Journals (Sweden)

    Berthe L.

    2011-01-01

    Full Text Available Laser driven shocks allow studying the dynamic behaviour of condensed matter over small spatial (∼μm to mm-order and temporal (∼ps to ns-order scales, at extremely high strain rates (∼107 s−1. They can be used to test the predictive capability of constitutive models over wide ranges of loading pressures and pulse durations. We present experimental results in laser shock-loaded metals (iron, gold, tin, based on various, complementary techniques including time-resolved velocity measurements, transverse shadowgraphy and post-shock analyses of recovered samples. The data are used to investigate several shock wave processes such as yielding and polymorphic transformations, melting, spall fracture and dynamic fragmentation in both solid and melted states. On the basis of comparisons with numerical simulations, the abilities and limitations of several models are briefly discussed.

  15. Assessment of RANS CFD modelling for pressurised thermal shock analysis

    International Nuclear Information System (INIS)

    Sander M Willemsen; Ed MJ Komen; Sander Willemsen

    2005-01-01

    Full text of publication follows: The most severe Pressurised Thermal Shock (PTS) scenario is a cold water Emergency Core Coolant (ECC) injection into the cold leg during a LOCA. The injected ECC water mixes with the hot fluid present in the cold leg and flows towards the downcomer where further mixing takes place. When the cold mixture comes into contact with the Reactor Pressure Vessel (RPV) wall, it may lead to large temperature gradients and consequently to high stresses in the RPV wall. Knowledge of these thermal loads is important for RPV remnant life assessments. The existing thermal-hydraulic system codes currently applied for this purpose are based on one-dimensional approximations and can, therefore, not predict the complex three-dimensional flows occurring during ECC injection. Computational Fluid Dynamics (CFD) can be applied to predict these phenomena, with the ultimate benefit of improved remnant RPV life assessment. The present paper presents an assessment of various Reynolds Averaged Navier Stokes (RANS) CFD approaches for modeling the complex mixing phenomena occurring during ECC injection. This assessment has been performed by comparing the numerical results obtained using advanced turbulence models available in the CFX 5.6 CFD code in combination with a hybrid meshing strategy with experimental results of the Upper Plenum Test Facility (UPTF). The UPTF was a full-scale 'simulation' of the primary system of the four loop 1300 MWe Siemens/KWU Pressurised Water Reactor at Grafenrheinfeld. The test vessel upper plenum internals, downcomer and primary coolant piping were replicas of the reference plant, while other components, such as core, coolant pump and steam generators were replaced by simulators. From the extensive test programme, a single-phase fluid-fluid mixing experiment in the cold leg and downcomer was selected. Prediction of the mixing and stratification is assessed by comparison with the measured temperature profiles at several locations

  16. Swift and Fermi Observations of X-Ray Flares: The Case of Late Internal Shock

    Science.gov (United States)

    Troja, E.; Piro, L.; Vasileiou, V.; Omodei, N.; Burgess, J. M.; Cutini, S.; Connaughton, V.; McEnery, J. E.

    2015-01-01

    Simultaneous Swift and Fermi observations of gamma-ray bursts (GRBs) offer a unique broadband view of their afterglow emission, spanning more than 10 decades in energy. We present the sample of X-ray flares observed by both Swift and Fermi during the first three years of Fermi operations. While bright in the X-ray band, X-ray flares are often undetected at lower (optical), and higher (MeV to GeV) energies. We show that this disfavors synchrotron self-Compton processes as the origin of the observed X-ray emission. We compare the broadband properties of X-ray flares with the standard late internal shock model, and find that in this scenario, X-ray flares can be produced by a late-time relativistic (gamma greater than 50) outflow at radii R approximately 10(exp 13) - 10(exp 14) cm. This conclusion holds only if the variability timescale is significantly shorter than the observed flare duration, and implies that X-ray flares can directly probe the activity of the GRB central engine.

  17. A discussion of nursing students' experiences of culture shock during an international clinical placement and the clinical facilitators' role.

    Science.gov (United States)

    Maginnis, Cathy; Anderson, Judith

    2017-06-01

    This paper examines the meaning and experience of culture shock for nursing students undertaking an international clinical placement (ICP) and the role of the clinical facilitator. Oberg's four stages of adapting to culture shock were aligned to anecdotal conversations with nursing students on an ICP. All four stages were identified in anecdotal conversations with the students. Support by the accompanying clinical facilitator is pivotalin overcoming culture shock and maximising the learning experience. It is essential that students are prepared for the change in cultural norms and are supported by the academic staff to work through the processes required to adapt to culture shock. Planning and preparation prior to departure is essential to assist with managing culture shock with an emphasis on the inclusion of cultural norms and beliefs. The role of the facilitator is crucial to guide and support the students through the culture shock process.

  18. An extended finite element formulation for modeling the response of polycrystalline materials to shock loading

    Science.gov (United States)

    Robbins, Joshua; Voth, Thomas

    2007-06-01

    The eXtended Finite Element Method (X-FEM) is a finite element based discretization technique developed originally to model dynamic crack propagation [1]. Since that time the method has been used for modeling physics ranging from static mesoscale material failure to dendrite growth. Here we adapt the recent advances of Benson et al. [2] and Belytchko et al. [3] to model shock loading of polycrystalline material. Through several demonstration problems we evaluate the method for modeling the shock response of polycrystalline materials at the mesoscale. Specifically, we use the X-FEM to model grain boundaries. This approach allows us to i) eliminate ad-hoc mixture rules for multi-material elements and ii) avoid explicitly meshing grain boundaries. ([1] N. Moes, J. Dolbow, J and T. Belytschko, 1999,``A finite element method for crack growth without remeshing,'' International Journal for Numerical Methods in Engineering, 46, 131-150. [2] E. Vitali, and D. J. Benson, 2006, ``An extended finite element formulation for contact in multi-material arbitrary Lagrangian-Eulerian calculations,'' International Journal for Numerical Methods in Engineering, 67, 1420-1444. [3] J-H Song, P. M. A. Areias and T. Belytschko, 2006, ``A method for dynamic crack and shear band propagation with phantom nodes,'' International Journal for Numerical Methods in Engineering, 67, 868-893.)

  19. Shock Absorbers Multi-Modeling and Suspension Optimization

    Directory of Open Access Journals (Sweden)

    LUPU Ciprian

    2013-05-01

    Full Text Available The standard dampers used by more 90% of vehicles have damping coefficients constant along stroke, so they can’t solve simultaneous all of them, situation solving practically using a relative dampingcoefficient able to made compromise between them. This paper design and simulation testing multi-models of two types of Damp (DSA and VZN. To compare the two types of suspension they are simulated in various road and load conditions. Analysis of simulation results is presente a new VZN shock absorber. This is an invention of the Institute of Mechanics of the Romanian Academy, and patented at European and U.S. [1], [2]. This is Called VZN shock absorber, iscoming from Variable Zeta Necessary acronym, for well moving in all road and load Conditions, Where zeta Represents the relative damping, Which is Adjusted automatically, stepwise, According to the piston positions [3,4,5]. Suspension systems are used in all air and ground transportation to protect that building transportation and cargo transported around against shocks and vibrations induced in the systemfrom the road Modifying damping coefficients (Zeta function piston position, being correlated with vehicle load and road unevenness.

  20. Modeling shock waves in an ideal gas: combining the Burnett approximation and Holian's conjecture.

    Science.gov (United States)

    He, Yi-Guang; Tang, Xiu-Zhang; Pu, Yi-Kang

    2008-07-01

    We model a shock wave in an ideal gas by combining the Burnett approximation and Holian's conjecture. We use the temperature in the direction of shock propagation rather than the average temperature in the Burnett transport coefficients. The shock wave profiles and shock thickness are compared with other theories. The results are found to agree better with the nonequilibrium molecular dynamics (NEMD) and direct simulation Monte Carlo (DSMC) data than the Burnett equations and the modified Navier-Stokes theory.

  1. Turbulence modeling of shock separated boundary-layer flows

    Science.gov (United States)

    Coakley, T. J.; Viegas, J. R.

    1977-01-01

    Computations of transonic and hypersonic shock-separated boundary-layer flows using zero-equation (algebraic), one-equation (kinetic energy), and two-equation (kinetic energy plus length scale) turbulence eddy viscosity models are described and compared with measurements. The computations make use of a new Navier-Stokes computer algorithm that has reduced computing times by one to two orders of magnitude. The algorithm, and how the turbulence models are incorporated into it, are described. Results for the transonic flow show that the unmodified one-equation model is superior to the zero-equation model in skin-friction predictions. For the hypersonic flow, a highly modified one-equation model that accurately predicts surface pressure and heat transfer is described. Preliminary two-equation model results are also presented.

  2. Modeling Three-Dimensional Shock Initiation of PBX 9501 in ALE3D

    Energy Technology Data Exchange (ETDEWEB)

    Leininger, L; Springer, H K; Mace, J; Mas, E

    2008-07-08

    A recent SMIS (Specific Munitions Impact Scenario) experimental series performed at Los Alamos National Laboratory has provided 3-dimensional shock initiation behavior of the HMX-based heterogeneous high explosive, PBX 9501. A series of finite element impact calculations have been performed in the ALE3D [1] hydrodynamic code and compared to the SMIS results to validate and study code predictions. These SMIS tests used a powder gun to shoot scaled NATO standard fragments into a cylinder of PBX 9501, which has a PMMA case and a steel impact cover. This SMIS real-world shot scenario creates a unique test-bed because (1) SMIS tests facilitate the investigation of 3D Shock to Detonation Transition (SDT) within the context of a considerable suite of diagnostics, and (2) many of the fragments arrive at the impact plate off-center and at an angle of impact. A particular goal of these model validation experiments is to demonstrate the predictive capability of the ALE3D implementation of the Tarver-Lee Ignition and Growth reactive flow model [2] within a fully 3-dimensional regime of SDT. The 3-dimensional Arbitrary Lagrange Eulerian (ALE) hydrodynamic model in ALE3D applies the Ignition and Growth (I&G) reactive flow model with PBX 9501 parameters derived from historical 1-dimensional experimental data. The model includes the off-center and angle of impact variations seen in the experiments. Qualitatively, the ALE3D I&G calculations reproduce observed 'Go/No-Go' 3D Shock to Detonation Transition (SDT) reaction in the explosive, as well as the case expansion recorded by a high-speed optical camera. Quantitatively, the calculations show good agreement with the shock time of arrival at internal and external diagnostic pins. This exercise demonstrates the utility of the Ignition and Growth model applied for the response of heterogeneous high explosives in the SDT regime.

  3. Modeling The Shock Initiation of PBX-9501 in ALE3D

    Energy Technology Data Exchange (ETDEWEB)

    Leininger, L; Springer, H K; Mace, J; Mas, E

    2008-07-01

    The SMIS (Specific Munitions Impact Scenario) experimental series performed at Los Alamos National Laboratory has determined the 3-dimensional shock initiation behavior of the HMX-based heterogeneous high explosive, PBX 9501. A series of finite element impact calculations have been performed in the ALE3D [1] hydrodynamic code and compared to the SMIS results to validate the code predictions. The SMIS tests use a powder gun to shoot scaled NATO standard fragments at a cylinder of PBX 9501, which has a PMMA case and a steel impact cover. The SMIS real-world shot scenario creates a unique test-bed because many of the fragments arrive at the impact plate off-center and at an angle of impact. The goal of this model validation experiments is to demonstrate the predictive capability of the Tarver-Lee Ignition and Growth (I&G) reactive flow model [2] in this fully 3-dimensional regime of Shock to Detonation Transition (SDT). The 3-dimensional Arbitrary Lagrange Eulerian hydrodynamic model in ALE3D applies the Ignition and Growth (I&G) reactive flow model with PBX 9501 parameters derived from historical 1-dimensional experimental data. The model includes the off-center and angle of impact variations seen in the experiments. Qualitatively, the ALE3D I&G calculations accurately reproduce the 'Go/No-Go' threshold of the Shock to Detonation Transition (SDT) reaction in the explosive, as well as the case expansion recorded by a high-speed optical camera. Quantitatively, the calculations show good agreement with the shock time of arrival at internal and external diagnostic pins. This exercise demonstrates the utility of the Ignition and Growth model applied in a predictive fashion for the response of heterogeneous high explosives in the SDT regime.

  4. An Improved Shock Model for Bare and Covered Explosives

    Science.gov (United States)

    Scholtes, Gert; Bouma, Richard

    2017-06-01

    TNO developed a toolbox to estimate the probability of a violent event on a ship or other platform, when the munition bunker is hit by e.g. a bullet or fragment from a missile attack. To obtain the proper statistical output, several millions of calculations are needed to obtain a reliable estimate. Because millions of different scenarios have to be calculated, hydrocode calculations cannot be used for this type of application, but a fast and good engineering solutions is needed. At this moment the Haskins and Cook-model is used for this purpose. To obtain a better estimate for covered explosives and munitions, TNO has developed a new model which is a combination of the shock wave model at high pressure, as described by Haskins and Cook, in combination with the expanding shock wave model of Green. This combined model gives a better fit with the experimental values for explosives response calculations, using the same critical energy fluence values for covered as well as for bare explosives. In this paper the theory is explained and results of the calculations for several bare and covered explosives will be presented. To show this, the results will be compared with the experimental values from literature for composition B, Composition B-3 and PBX-9404.

  5. Modeling and evaluation of HE driven shock effects in copper with the MTS model

    International Nuclear Information System (INIS)

    Murphy, M.J.; Lassila, D.F.

    1997-01-01

    Many experimental studies have investigated the effect of shock pressure on the post-shock mechanical properties of OFHC copper. These studies have shown that significant hardening occurs during shock loading due to dislocation processes and twinning. It has been demonstrated that when an appropriate initial value of the Mechanical Threshold Stress (MTS) is specified, the post-shock flow stress of OFE copper is well described by relationships derived independently for unshocked materials. In this study we consider the evolution of the MTS during HE driven shock loading processes and the effect on the subsequent flow stress of the copper. An increased post shock flow stress results in a higher material temperature due to an increase in the plastic work. An increase in temperature leads to thermal softening which reduces the flow stress. These coupled effects will determine if there is melting in a shaped charge jet or a necking instability in an EFP Ww. 'Me critical factor is the evolution path followed combined with the 'current' temperature, plastic strain, and strain rate. Preliminary studies indicate that in simulations of HE driven shock with very high resolution zoning, the MTS saturates because of the rate dependence in the evolution law. On going studies are addressing this and other issues with the goal of developing a version of the MT'S model that treats HE driven, shock loading, temperature, strain, and rate effects apriori

  6. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016.

    Science.gov (United States)

    Rhodes, Andrew; Evans, Laura E; Alhazzani, Waleed; Levy, Mitchell M; Antonelli, Massimo; Ferrer, Ricard; Kumar, Anand; Sevransky, Jonathan E; Sprung, Charles L; Nunnally, Mark E; Rochwerg, Bram; Rubenfeld, Gordon D; Angus, Derek C; Annane, Djillali; Beale, Richard J; Bellinghan, Geoffrey J; Bernard, Gordon R; Chiche, Jean-Daniel; Coopersmith, Craig; De Backer, Daniel P; French, Craig J; Fujishima, Seitaro; Gerlach, Herwig; Hidalgo, Jorge Luis; Hollenberg, Steven M; Jones, Alan E; Karnad, Dilip R; Kleinpell, Ruth M; Koh, Younsuck; Lisboa, Thiago Costa; Machado, Flavia R; Marini, John J; Marshall, John C; Mazuski, John E; McIntyre, Lauralyn A; McLean, Anthony S; Mehta, Sangeeta; Moreno, Rui P; Myburgh, John; Navalesi, Paolo; Nishida, Osamu; Osborn, Tiffany M; Perner, Anders; Plunkett, Colleen M; Ranieri, Marco; Schorr, Christa A; Seckel, Maureen A; Seymour, Christopher W; Shieh, Lisa; Shukri, Khalid A; Simpson, Steven Q; Singer, Mervyn; Thompson, B Taylor; Townsend, Sean R; Van der Poll, Thomas; Vincent, Jean-Louis; Wiersinga, W Joost; Zimmerman, Janice L; Dellinger, R Phillip

    2017-03-01

    To provide an update to "Surviving Sepsis Campaign Guidelines for Management of Sepsis and Septic Shock: 2012." A consensus committee of 55 international experts representing 25 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. A stand-alone meeting was held for all panel members in December 2015. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development. The panel consisted of five sections: hemodynamics, infection, adjunctive therapies, metabolic, and ventilation. Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. Each subgroup generated a list of questions, searched for best available evidence, and then followed the principles of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system to assess the quality of evidence from high to very low, and to formulate recommendations as strong or weak, or best practice statement when applicable. The Surviving Sepsis Guideline panel provided 93 statements on early management and resuscitation of patients with sepsis or septic shock. Overall, 32 were strong recommendations, 39 were weak recommendations, and 18 were best-practice statements. No recommendation was provided for four questions. Substantial agreement exists among a large cohort of international experts regarding many strong recommendations for the best care of patients with sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for these critically ill patients with high mortality.

  7. A SIMPLE EXPERIMENTAL MODEL OF HEAT SHOCK RESPONSE IN RATS

    Directory of Open Access Journals (Sweden)

    Tufi Neder Meyer

    1998-10-01

    Full Text Available Objective: To obtain a simple model for the elicitation of the heat shock response in rats. Design: Laboratory study. Setting: University research laboratories. Sample: Seventy-nine adult male albino rats (weight range 200 g to 570 g. Procedures: Exposure to heat stress by heating animals in a warm bath for 5 min after their rectal temperatures reached 107.60 F (420 C. Liver and lung samples were collected for heat-shock protein 70 (HSP70 detection (Western analysis. Results: Western analysis was positive for HSP70 in the liver and in the lungs of heated animals. There was a temporal correlation between heating and HSP70 detection: it was strongest 1 day after heating and reduced afterwards. No heated animals died. Conclusion: These data show that heating rats in a warm (45o C bath, according to parameters set in this model, elicits efficiently the heat shock response.OBJETIVO: Obter um modelo simples para tentar esclarecer a resposta ao choque térmico em ratos. LOCAL: Laboratório de pesquisa da Universidade. MÉTODO: Amostra: 79 ratos albinos, adultos, entre 200g a 570g. Procedimentos: Exposição ao calor, em banho quente, por 5 minutos, após a temperatura retal chegar a 42 graus centigrados. Biópsias de fígado e pulmão foram obtidas para detectar a proteina 70 (HSP 70, pelo "Western blot". RESULTADOS: As análises foram positivas nos animais aquecidos, com uma correlação entre aquecimento e constatação da HSP 70. Foi mais elevada no primeiro dia e não houve óbitos nos animais aquecidos. CONCLUSÃO: Os ratos aquecidos a 45 graus centígrados respondem eficientemente ao choque térmico.

  8. Hydrodynamic modelling of the shock ignition scheme for inertial confinement fusion

    International Nuclear Information System (INIS)

    Vallet, Alexandra

    2014-01-01

    The shock ignition concept in inertial confinement fusion uses an intense power spike at the end of an assembly laser pulse. The key features of shock ignition are the generation of a high ablation pressure, the shock pressure amplification by at least a factor of a hundred in the cold fuel shell and the shock coupling to the hot-spot. In this thesis, new semi-analytical hydrodynamic models are developed to describe the ignitor shock from its generation up to the moment of fuel ignition. A model is developed to describe a spherical converging shock wave in a pre-heated hot spot. The self-similar solution developed by Guderley is perturbed over the shock Mach number Ms ≥≥1. The first order correction accounts for the effects of the shock strength. An analytical ignition criterion is defined in terms of the shock strength and the hot-spot areal density. The ignition threshold is higher when the initial Mach number of the shock is lower. A minimal shock pressure of 20 Gbar is needed when it enters the hot-spot. The shock dynamics in the imploding shell is then analyzed. The shock is propagating into a non inertial medium with a high radial pressure gradient and an overall pressure increase with time. The collision with a returning shock coming from the assembly phase enhances further the ignitor shock pressure. The analytical theory allows to describe the shock pressure and strength evolution in a typical shock ignition implosion. It is demonstrated that, in the case of the HiPER target design, a generation shock pressure near the ablation zone on the order of 300-400 Mbar is needed. An analysis of experiments on the strong shock generation performed on the OMEGA laser facility is presented. It is shown that a shock pressure close to 300 Mbar near the ablation zone has been reached with an absorbed laser intensity up to 2 * 10 15 W:cm -2 and a laser wavelength of 351 nm. This value is two times higher than the one expected from collisional laser absorption only

  9. Comparison of Hydroxocobalamin Versus Norepinephrine Versus Saline in a Swine Model of Servere Septic Shock

    Science.gov (United States)

    2016-05-20

    Versus Saline in a Swine Model of Severe Septic Shock presented at/published to SURF Conference, San Antonio, TX 20 May 2016 with MDWJ 41-108, and has...PRESENTED: Comparison of hydroxocobalamin versus norepinephrine versus saline in a Swine model of severe septic shock 7. FUNDING RECEIVED FOR THIS...Comparison of hydroxocbalamin versus norepinephrine versus saline in a swine model of severe septic shock . Background: Sepsis is associated with a mortality

  10. Comparison of Hydroxocobalamin Versus Norepinephrine Versus Saline in a Swine Model of Severe Septic Shock

    Science.gov (United States)

    2016-05-18

    Versus Saline in a Swine Model of Severe Septic Shock presented at/published to the Lightning Oral, SAEM Conference, New Orleans, LA 10-13 May 2016 with...PRESENTED: Comparison of hydroxocobalamin versus norepinephrine versus sal ine in a Swine model of severe septic shock 7. FUNDING RECEIVED FOR THIS...saline in a swine model of severe septic shock . Background: Sepsis is associated with a mortality of nearly 30%. Mortality is due, in part, to an

  11. Modeling and Analysis of AGS (1998) Thermal Shock Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Haines, J.R.; Kim, S.H.; Taleyarkhan, R.P.

    1999-11-14

    An overview is provided on modeling and analysis of thermal shock experiments conducted during 1998 with high-energy, short-pulse energy deposition in a mercury filled container in the Alternating Gradient Synchrotron (AGS) facility at Brookhaven National Laboratory (BNL). The simulation framework utilized along with the results of simulations for pressure and strain profiles are presented. While the magnitude of penk strain predictions versus data are in reasonable agreement, the temporal variations were found to differ significantly in selected cases, indicating lack of modeling of certain physical phenomena or due to uncertainties in the experimental data gathering techniques. Key thermal-shock related issues and uncertainties are highlighted. Specific experiments conducted at BNL's AGS facility during 1998 (the subject of this paper) involved high-energy (24 GeV) proton energy deposition in the mercury target over a time frame of - 0.1s. The target consisted of an - 1 m. long cylindrical stainless steel shell with a hemispherical dome at the leading edge. It was filled with mercury at room temperature and pressure. Several optical strain gages were attached to the surface of the steel target. Figure 1 shows a schematic representation of the test vessel along with the main dimensions and positions of three optical strain gages at which meaningful data were obtained. As

  12. Drop Hammer Tests with Three Oleo Strut Models and Three Different Shock Strut Oils at Low Temperatures

    Science.gov (United States)

    Kranz, M

    1954-01-01

    Drop hammer tests with different shock strut models and shock strut oils were performed at temperatures ranging to -40 C. The various shock strut models do not differ essentially regarding their springing and damping properties at low temperatures; however, the influence of the different shock strut oils on the springing properties at low temperatures varies greatly.

  13. Structural model of dodecameric heat-shock protein Hsp21

    DEFF Research Database (Denmark)

    Rutsdottir, Gudrun; Härmark, Johan; Weide, Yoran

    2017-01-01

    Small heat-shock proteins (sHsps) prevent aggregation of thermosensitive client proteins in a first line of defense against cellular stress. The mechanisms by which they perform this function have been hard to define due to limited structural information; currently, there is only one high......-resolution structure of a plant sHsp published, that of the cytosolic Hsp16.9. We took interest in Hsp21, a chloroplast-localized sHsp crucial for plant stress resistance, which has even longer N-terminal arms than Hsp16.9, with a functionally important and conserved methionine-rich motif. To provide a framework...... for investigating structure-function relationships of Hsp21 and understanding these sequence variations, we developed a structural model of Hsp21 based on homology modeling, cryo-EM, cross-linking mass spectrometry, NMR, and small-angle X-ray scattering. Our data suggest a dodecameric arrangement of two trimer...

  14. The Effects of Permanent Technology Shocks on Labour Productivity and Hours in the RBC Model

    OpenAIRE

    Lindé, Jesper

    2005-01-01

    Recent work on the effects of permanent technology shocks argue that the basic RBC model cannot account for a negative correlation between hours worked and labour productivity. In this Paper, I show that this conjecture is not necessarily correct. In the basic RBC model, I find that hours worked fall and labour productivity rises after a positive permanent technology shock once one allows for the possibility that the process for the permanent technology shock is persistent in growth rates. A ...

  15. Nonequilibrium excitation of internal molecular degrees of freedom in the shock layer during hypersonic flight

    Science.gov (United States)

    Doroshenko, V. M.; Kudriavtsev, N. N.; Smetanin, V. V.

    1992-09-01

    A kinetic scheme of processes including the formation and quenching of electronically and vibrationally excited particles is proposed for the shock layer adjacent to the surface of a body flying at hypersonic speed. We present results of a numerical calculations for the stagnation point obtained under the thin viscous shock layer approximation for space shuttle flight conditions. We show that the release of atom recombination energy into the internal molecular degrees of freedom and the finite rate of relaxation reduce the calculated heat flux by 20 percent. Proceedings of the 29th International Conference on the Applications of the Mössbauer Effect (ICAME 2007) held in Kanpur, India, 14-19 October 2007, PART IV/VII 30 2008 11 19 2008 11 18 2008 7 2008 Springer Science+Business Media B.V. 2008 9832 10.1007/s10751-008-9832-4 24 Mössbauer study of [Fe(Dioximato) n L2] mixed coordination compounds 159 165 2008 9 17 2008 11 1

  16. Quantification model of the consequences of monetary policy shocks

    Directory of Open Access Journals (Sweden)

    Coralia Emilia POPA

    2017-11-01

    Full Text Available The monetary analysis based on the BVAR (Bayesian Vector Autoregression model is extremely important in the monetary policy implementation strategy, the information provided is important not only for the Central Bank, but also for the economic agents and the population. Therefore, conducting this analysis at the level of Romania helps to understand better the mechanism by which monetary policy is transmitted in order to achieve the set target, namely inflation targeting, but it also provides us with important information regarding the accession to the euro area. The model we are trying to test helps us understand through the correlations between the interest rate, GDP and the inflation rate how monetary policy responds to shocks. The model follows the methodology presented by Sims and Zha (1998 in the paper "Bayesian Methods for Dynamic Multivariate Models and Using the Bayesian Autoregressive Vector". In the analysis of this model, quarterly data for a minimum of three years, three variables are used to make the results relevant. The data needed to model the model are used in logarithmic form, except for the interest rate, and the outcome is applied to a differentiated premium operator. Of the variables used, the interest rate is the only one that does not allow seasonal adjustment.

  17. Experimental models of sepsis and septic shock: an overview

    Directory of Open Access Journals (Sweden)

    Garrido Alejandra G.

    2004-01-01

    Full Text Available Sepsis remains a major cause of morbidity and mortality in surgical patients and trauma victims, mainly due to sepsis-induced multiple organ dysfunction. In contrast to preclinical studies, most clinical trials of promising new treatment strategies for sepsis have fails to demonstrate efficacy. Although many reasons could account for this discrepancy, the misinterpretation of preclinical data obtained from experimental studies, and especially the use of animal models that do not adequately mimic human sepsis may have been contributing factors. In this review, the benefits and limitations of various animal models of sepsis are discussed to clarify the extend to which findings are relevant to human sepsis, particularly with respect to the subsequent design and execution of clinical trials. Such models include intravascular infusion of endotoxin or live bacteria, bacterial peritonitis, cecal ligation and perforation, soft tissue infection, pneumonia or meningitis models, using different animal species including rats, mice, rabbits, dogs, pigs, sheep and nonhuman primates. Despite several limitations, animal models remain essential in the development of all new therapies for sepsis and septic shock, because they provide fundamental information about the pharmacokinetics, toxicity, and mechanism of drug action that cannot be duplicated by other methods. New therapeutic agents should be studies in infection models, even after the initiation of the septic process. Furthermore, debility conditions need to be reproduced to avoid the exclusive use of healthy animals, which often do not represent the human septic patient.

  18. Material model validation for laser shock peening process simulation

    International Nuclear Information System (INIS)

    Amarchinta, H K; Grandhi, R V; Langer, K; Stargel, D S

    2009-01-01

    Advanced mechanical surface enhancement techniques have been used successfully to increase the fatigue life of metallic components. These techniques impart deep compressive residual stresses into the component to counter potentially damage-inducing tensile stresses generated under service loading. Laser shock peening (LSP) is an advanced mechanical surface enhancement technique used predominantly in the aircraft industry. To reduce costs and make the technique available on a large-scale basis for industrial applications, simulation of the LSP process is required. Accurate simulation of the LSP process is a challenging task, because the process has many parameters such as laser spot size, pressure profile and material model that must be precisely determined. This work focuses on investigating the appropriate material model that could be used in simulation and design. In the LSP process material is subjected to strain rates of 10 6  s −1 , which is very high compared with conventional strain rates. The importance of an accurate material model increases because the material behaves significantly different at such high strain rates. This work investigates the effect of multiple nonlinear material models for representing the elastic–plastic behavior of materials. Elastic perfectly plastic, Johnson–Cook and Zerilli–Armstrong models are used, and the performance of each model is compared with available experimental results

  19. 3D Smoothed Particle Hydrodynamics Models of Betelgeuse's Bow Shock

    OpenAIRE

    Mohamed, Shazrene; Mackey, Jonathan; Langer, Norbert

    2013-01-01

    Betelgeuse, the bright red supergiant (RSG) in Orion, is a runaway star. Its supersonic motion through the interstellar medium has resulted in the formation of a bow shock, a cometary structure pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. We show that the bow shock morphology depends substantially on the growth timescale for Rayleigh-Taylor versus Kelvin-Helmholtz instabilities. We discuss our m...

  20. Positive predictive value of International Classification of Diseases, 10th revision, diagnosis codes for cardiogenic, hypovolemic, and septic shock in the Danish National Patient Registry.

    Science.gov (United States)

    Lauridsen, Marie Dam; Gammelager, Henrik; Schmidt, Morten; Nielsen, Henrik; Christiansen, Christian Fynbo

    2015-03-20

    Large registries are important data sources in epidemiological studies of shock, if these registries are valid. Therefore, we examined the positive predictive value (PPV) of diagnosis codes for shock, the procedure codes for inotropic/vasopressor therapy among patients with a diagnosis of shock, and the combination of a shock diagnosis and a code for inotropic/vasopressor therapy in the Danish National Patient Registry (DNPR). We randomly selected 190 inpatients with an International Classification of Diseases, 10th revision (ICD-10) diagnosis of shock at Aarhus University Hospital from 2005-2012 using the DNPR; 50 patients were diagnosed with cardiogenic shock, 40 patients with hypovolemic shock, and 100 patients with septic shock. We used medical charts as the reference standard and calculated the PPV with 95% confidence intervals (CI) for overall shock and for each type of shock separately. We also examined the PPV for inotropic/vasopressor therapy and the PPV for shock when a concurrent code for inotropic/vasopressor therapy was also registered. The PPV was 86.1% (95% CI: 79.7-91.1) for shock overall, 93.5% (95% CI: 82.1-98.6) for cardiogenic shock, 70.6% (95% CI: 52.5-84.9) for hypovolemic shock, and 69.2% (95% CI: 57.7-79.2) for septic shock. The PPV of use of inotropes/vasopressors among shock patients was 88.9% (95% CI: 79.3-95.1). When both a shock code and a procedure code for inotropic/vasopressor therapy were used, the PPV for shock overall was 93.1% (95% CI: 84.5-97.7). ICD-10 codes for subtypes of shock and simultaneously registered use of inotropes/vasopressors provided PPVs of 96.0% (95% CI: 79.6-99.9) for cardiogenic shock, 69.2% (95% CI: 38.6-90.9) for hypovolemic shock, and 82.4% (95% CI: 65.5-93.2) for septic shock. Overall, we found a moderately high PPV for shock in the DNPR. The PPV was highest for cardiogenic shock but lower for hypovolemic and septic shock. Combination diagnoses of shock with codes for inotropic/vasopressor therapy further

  1. Modelling Near-IR polarization to constrain stellar wind bow shocks

    Science.gov (United States)

    Neilson, Hilding R.; Ignace, R.; Shrestha, M.; Hoffman, J. L.; Mackey, J.

    2013-06-01

    Bow shocks formed from stellar winds are common phenomena observed about massive and intermediate-mass stars such as zeta Oph, Betelgeuse and delta Cep. These bow shocks provide information about the motion of the star, the stellar wind properties and the density of the ISM. Because bow shocks are asymmetric structures, they also present polarized light that is a function of their shape and density. We present a preliminary work modeling dust polarization from a Wilkin (1996) analytic bow shock model and explore how the polarization changes as a function of stellar wind properties.

  2. Extended charge banking model of dual path shocks for implantable cardioverter defibrillators.

    Science.gov (United States)

    Dosdall, Derek J; Sweeney, James D

    2008-08-01

    Single path defibrillation shock methods have been improved through the use of the Charge Banking Model of defibrillation, which predicts the response of the heart to shocks as a simple resistor-capacitor (RC) circuit. While dual path defibrillation configurations have significantly reduced defibrillation thresholds, improvements to dual path defibrillation techniques have been limited to experimental observations without a practical model to aid in improving dual path defibrillation techniques. The Charge Banking Model has been extended into a new Extended Charge Banking Model of defibrillation that represents small sections of the heart as separate RC circuits, uses a weighting factor based on published defibrillation shock field gradient measures, and implements a critical mass criteria to predict the relative efficacy of single and dual path defibrillation shocks. The new model reproduced the results from several published experimental protocols that demonstrated the relative efficacy of dual path defibrillation shocks. The model predicts that time between phases or pulses of dual path defibrillation shock configurations should be minimized to maximize shock efficacy. Through this approach the Extended Charge Banking Model predictions may be used to improve dual path and multi-pulse defibrillation techniques, which have been shown experimentally to lower defibrillation thresholds substantially. The new model may be a useful tool to help in further improving dual path and multiple pulse defibrillation techniques by predicting optimal pulse durations and shock timing parameters.

  3. Evaluation of turbulence models for three primary types of shock-separated boundary layers

    Science.gov (United States)

    Coakley, T. J.; Viegas, J. R.; Horstman, C. C.

    1977-01-01

    Zero-equation (algebraic), one-equation (kinetic energy), and two-equation (kinetic energy plus length scale) turbulence eddy viscosity models were used in computing three basic types of shock-separated boundary-layer flows. The three basic types of shock boundary-layer interaction discussed are: (1) a normal shock wave at transonic speeds, (2) a compression corner shock at supersonic speeds, and (3) an incident oblique shock at hypersonic speeds. The models tested are simple, unmodified models used extensively for incompressible, unseparated flows. A comparison of computed and measured results for the compressible, separated flows described herein indicates that model performance is dependent on flow configuration with no distinct superiority of one model over the other for all three flow configurations.

  4. Heat flux and shock shape measurements on an Aeroassist Flight Experiment model in a high enthalpy free piston shock tunnel

    Science.gov (United States)

    Gai, S. L.; Mudford, N. R.; Hackett, C.

    1992-01-01

    This paper describes measurements of heat flux and shock shapes made on a 2.08 percent scale model of the proposed Aeroassist Flight Experiment model in a high enthalpy free piston shock tunnel T3 at the Australian National University in Canberra, Australia. The enthalpy and Reynolds number range covered were 7.5 MJ/kg to 20 MJ/kg and 150,000 to 270,000 per meter respectively. The test Mach number varied between 7.5 and 8. Two test gases, air and nitrogen, were used and the model angle of attack varied from -10 deg to +10 deg to the free stream. The results are discussed and compared to the Mach 10 cold hypersonic air data as obtained in the Langley 31 inch Mach 10 Facility as well as the perfect gas CFD calculations of NASA LaRC.

  5. Comparison Between Surf and Multi-Shock Forest Fire High Explosive Burn Models

    Energy Technology Data Exchange (ETDEWEB)

    Greenfield, Nicholas Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-18

    PAGOSA1 has several different burn models used to model high explosive detonation. Two of these, Multi-Shock Forest Fire and Surf, are capable of modeling shock initiation. Accurately calculating shock initiation of a high explosive is important because it is a mechanism for detonation in many accident scenarios (i.e. fragment impact). Comparing the models to pop-plot data give confidence that the models are accurately calculating detonation or lack thereof. To compare the performance of these models, pop-plots2 were created from simulations where one two cm block of PBX 9502 collides with another block of PBX 9502.

  6. An In Silico Model of Endotoxic Shock Mediators (Briefing Charts)

    Science.gov (United States)

    2012-03-12

    organ dysfunction Arachidonic acid metabolism Thromboxanes (TX) Prostaglandins (PG) Leukotrienes (LT) Distribution A. Approved for public release...Increased plasma TXB2 in humans suffering from severe septic shock • Endotoxemia and sepsis: Blood PAF levels are elevated Distribution A. Approved...mediators are capable of modifying the course of endotoxic shock • Lipoxygenase (LOX) inhibitors protect mice and rats from lethal endotoxemia

  7. Dynamics of a Pipeline under the Action of Internal Shock Pressure

    Science.gov (United States)

    Il'gamov, M. A.

    2017-11-01

    The static and dynamic bending of a pipeline in the vertical plane under the action of its own weight is considered with regard to the interaction of the internal pressure with the curvature of the axial line and the axisymmetric deformation. The pressure consists of a constant and timevarying parts and is assumed to be uniformly distributed over the entire span between the supports. The pipeline reaction to the stepwise increase in the pressure is analyzed in the case where it is possible to determine the exact solution of the problem. The initial stage of bending determined by the smallness of elastic forces as compared to the inertial forces is introduced into the consideration. At this stage, the solution is sought in the form of power series and the law of pressure variation can be arbitrary. This solution provides initial conditions for determining the further process. The duration of the inertial stage is compared with the times of sharp changes of the pressure and the shock waves in fluids. The structure parameters are determined in the case where the shock pressure is accepted only by the inertial forces in the pipeline.

  8. Shock-induced electrical activity in polymeric solids. A mechanically induced bond scission model

    International Nuclear Information System (INIS)

    Graham, R.A.

    1979-01-01

    When polymeric solids are subjected to high-pressure shock loading, two anomalous electrical phenomena, shock-induced conduction and shock-induced polarization, are observed. The present paper proposes a model of mechanically induced bond scission within the shock front to account for the effects. An experimental study of shock-induced polarization in poly(pyromellitimide) (Vespel SP-1) is reported for shock compressions from 17 to 23% (pressures from 2.5 to 5.4 GPa). Poly(pyromellitimide) is found to be a strong generator of such polarization and the polarization is found to reflect an irreversible or highly hysteretic process. The present measurements are combined with prior measurements to establish a correlation between monomer structure and strength of shock-induced polarization; feeble signals are observed in the simpler monomer repeat units of poly(tetrafluoroethylene) and polyethylene while the strongest signals are observed in more complex monomers of poly(methyl methacrylate) and poly(pyromellitimide). It is also noted that there is an apparent correlation between shock-induced conduction and shock-induced polarization. Such shock-induced electrical activity is also found to be well correlated with the propensity for mechanical bond scission observed in experiments carried out in conventional mechanochemical studies. The bond scission model can account for characteristics observed for electrical activity in shock-loaded polymers and their correlation to monomer structure. Localization of elastic energy within the monomer repeat unit or along the main chain leads to the different propensities for bond scission and resulting shock-induced electrical activity

  9. Theoretical models of interstellar shocks. I - Radiative transfer and UV precursors

    Science.gov (United States)

    Shull, J. M.; Mckee, C. F.

    1979-01-01

    Theoretical models of interstellar radiative shocks are constructed, with special attention to the transfer of ionizing radiation. These models are 'self-consistent' in the sense that the emergent ionizing radiation (the UV precursor) is coupled with the ionization state of H, He, and the metals in the preshock gas. For shock velocities of at least 110 km/s the shocks generate sufficient UV radiation for complete preionization of H and He, the latter to He(+). At lower velocities the preionization can be much smaller, with important consequences for the cooling function, the shock structure, and the emission. For models with shock velocities of 40 to 130 km/s the intensities of the strongest emission lines in the UV, optical, and infrared are tabulated, as well as postshock column densities of metal ions potentially observable by UV absorption spectroscopy. Possible applications to supernova remnants and high-velocity interstellar gas are assessed.

  10. The collision of a strong shock with a gas cloud: a model for Cassiopeia A

    International Nuclear Information System (INIS)

    Sgro, A.G.

    1975-01-01

    The result of the collision of the shock with the cloud is a shock traveling around the cloud, a shock transmitted into the cloud, and a shock reflected from the cloud. By equating the cooling time of the posttransmitted shock gas to the time required for the transmitted shock to travel the length of the cloud, a critical cloud density n/subc/ /sup prime/ is defined. For clouds with density greater than n/subc/ /sup prime/, the posttransmitted shock gas cools rapidly and then emits the lines of the lower ionization stages of its constituent elements. The structure of such and its expected appearance to an observer are discussed and compared with the quasi-stationary condensations of Cas A. Conversely, clouds with density less than n/subc//sup prime/ remain hot for several thousand years, and are sources of X-radiation whose temperatures are much less than that of the intercloud gas. After the transmitted shock passes, the cloud pressure is greater than the pressure in the surrounding gas, causing the cloud to expand and the emission to decrease from its value just after the collision. A model in which the soft X-radiation of Cas A is due to a collection of such clouds is discussed. The faint emission patches to the north of Cas A are interpreted as preshocked clouds which will probably become quasi-stationary condensations after being hit by the shock

  11. Topics in Computational Modeling of Shock and Wave Propagation

    National Research Council Canada - National Science Library

    Gazonas, George A; Main, Joseph A; Laverty, Rich; Su, Dan; Santare, Michael H; Raghupathy, R; Molinari, J. F; Zhou, F

    2006-01-01

    This report contains reprints of four papers that focus on various aspects of shock and wave propagation in cellular, viscoelastic, microcracked, and fragmented media that appear in the Proceedings...

  12. International Students from Melbourne Describing Their Cross-Cultural Transitions Experiences: Culture Shock, Social Interaction, and Friendship Development

    Science.gov (United States)

    Belford, Nish

    2017-01-01

    Drawing from a study that explored how international students experience cross-cultural transitions after living and studying in Melbourne for a few years, this paper, in particular, examines the participants' experiences with culture shock, social interaction, and friendship development. The findings include narratives of their personal stories…

  13. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012.

    Science.gov (United States)

    Dellinger, R P; Levy, Mitchell M; Rhodes, Andrew; Annane, Djillali; Gerlach, Herwig; Opal, Steven M; Sevransky, Jonathan E; Sprung, Charles L; Douglas, Ivor S; Jaeschke, Roman; Osborn, Tiffany M; Nunnally, Mark E; Townsend, Sean R; Reinhart, Konrad; Kleinpell, Ruth M; Angus, Derek C; Deutschman, Clifford S; Machado, Flavia R; Rubenfeld, Gordon D; Webb, Steven; Beale, Richard J; Vincent, Jean-Louis; Moreno, Rui

    2013-02-01

    To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008. A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Recommendations were classified into three groups: (1) those directly targeting severe sepsis; (2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and (3) pediatric considerations. Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 h after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 h of the recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B

  14. Surviving sepsis campaign: international guidelines for management of severe sepsis and septic shock: 2012.

    Science.gov (United States)

    Dellinger, R Phillip; Levy, Mitchell M; Rhodes, Andrew; Annane, Djillali; Gerlach, Herwig; Opal, Steven M; Sevransky, Jonathan E; Sprung, Charles L; Douglas, Ivor S; Jaeschke, Roman; Osborn, Tiffany M; Nunnally, Mark E; Townsend, Sean R; Reinhart, Konrad; Kleinpell, Ruth M; Angus, Derek C; Deutschman, Clifford S; Machado, Flavia R; Rubenfeld, Gordon D; Webb, Steven A; Beale, Richard J; Vincent, Jean-Louis; Moreno, Rui

    2013-02-01

    To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008. A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Some recommendations were ungraded (UG). Recommendations were classified into three groups: 1) those directly targeting severe sepsis; 2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and 3) pediatric considerations. Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 hrs after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 hr of recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de

  15. Combustion, detonation, shock waves. Proceedings of the Zel'dovich memorial - International conference on combustion. Volume 1

    International Nuclear Information System (INIS)

    Merzhanov, A.G.; Frolov, S.M.

    1995-01-01

    This book contains lectures by the experts in various fields of modern research in combustion, detonation and shock waves, presented at the Zel'dovich memorial - International conference on combustion dedicated to the 80-th birthday of academician Ya.B. Zel'dovich. There are eight chapters discussing the state-of-the-art in combustion kinetics, ignition and steady-state flame propagation, diffusion and heterogeneous combustion, turbulent combustion, unsteady combustion, detonation, combustion and detonation analogies, intense shock waves and extreme states of matter [ru

  16. The isolated perfused kidney of the pig: new model to evaluate shock wave-induced lesions.

    Science.gov (United States)

    Köhrmann, K U; Back, W; Bensemann, J; Florian, J; Weber, A; Kahmann, F; Rassweiler, J; Alken, P

    1994-04-01

    Little is known about the mechanisms and determining factors of shock wave-induced kidney trauma. After classification of the renal lesion in a canine model, we attempted to establish an ex vivo model using the isolated kidney of the pig perfused by Tyrode's solution under physiologic conditions. After shock wave application on the Modulith SL 20, vessel lesions were evaluated by microangiography to determine the size and frequency of dye extravasation in the different areas of the organ. Variation of the focus localization caused different patterns of lesions that characterized the pathway of the shock wave. In particular, constant petechial extravasation in the cortex was observed. The generator voltage correlated with the diameter and the frequency of the lesion area. The number of shock waves primarily affected the incidence of vessel rupture in the regions adjacent to the focal zone. Light microscopy revealed dose-dependent necrosis of tubular cells up to gap-like parenchymal defects. Even after application of the minimal shock wave doses, electron microscopy demonstrated vacuolization of tubular cells in the shock wave focus. Traumatic junctions between capillaries and the tubulur system can explain clinically observed macrohematuria without renal hematomas. With this model, it was possible to evaluate localization and dose dependence of shock wave-induced kidney trauma with high sensitivity and reproducibility. Further advantages of the model were easy availability and the fact that studies on living animals were not necessary. Therefore, standardization and comparison of different lithotripters becomes possible.

  17. Internal density waves of shock type induced by chemoconvection in miscible reacting liquids

    Science.gov (United States)

    Bratsun, D. A.

    2017-10-01

    A theoretical explanation of the phenomenon of spontaneous emergence of density waves experimentally observed recently in bilayered systems of miscible liquids placed in a narrow vertical gap of the Hele-Shaw cell in the gravitational field is provided. Upper and lower layers represent aqueous solutions of acids and bases, respectively, whose contact leads to the beginning of a neutralization reaction. The process is accompanied by a strong dependence of the reagent's diffusion coefficients on their concentrations, giving rise to the generation of local density pockets, in which convection develops. The cavities collapse under certain conditions, causing a density jump, which moves faster than typical perturbations in a medium and takes the form of a shock wave. A mathematical model of the phenomenon is proposed, which can be formally reduced to equations of motion of a compressible gas under certain assumptions. Numerical calculations are given and compared with the experimental data.

  18. The influence of oil price shocks on china’s macro-economy: A perspective of international trade

    Directory of Open Access Journals (Sweden)

    Dengke Chen

    2015-09-01

    Full Text Available This paper is aimed at investigating and understanding the relationship between China’s macro-economy and oil price from a new perspective—the international trade perspective. We find strong evidence to suggest that the increase of China’s price level, resulting from oil price shocks, is statistically less than that of its main trade partners’. This helps us to understand the confused empirical results estimated within the SVAR framework. More specifically, SVAR results suggest that China’s output level is positively correlated with the oil price. Positive correlation between China’s output and oil price shocks presumably results from the drop in China’s relative price induced by oil price shocks, which is inclined to stimulate China’s goods and service exports.

  19. An empirical model of the Earth's bow shock based on an artificial neural network

    Science.gov (United States)

    Pallocchia, Giuseppe; Ambrosino, Danila; Trenchi, Lorenzo

    2014-05-01

    All of the past empirical models of the Earth's bow shock shape were obtained by best-fitting some given surfaces to sets of observed crossings. However, the issue of bow shock modeling can be addressed by means of artificial neural networks (ANN) as well. In this regard, here it is presented a perceptron, a simple feedforward network, which computes the bow shock distance along a given direction using the two angular coordinates of that direction, the bow shock predicted distance RF79 (provided by Formisano's model (F79)) and the upstream alfvénic Mach number Ma. After a brief description of the ANN architecture and training method, we discuss the results of the statistical comparison, performed over a test set of 1140 IMP8 crossings, between the prediction accuracies of ANN and F79 models.

  20. Turbulence Models: Shock Boundary Layer Interaction at M=2.05

    Data.gov (United States)

    National Aeronautics and Space Administration — Exp: Shock Boundary Layer Interaction at M=2.05. This web page provides data from experiments that may be useful for the validation of turbulence models. This...

  1. Hydrodynamic modeling and simulations of shock ignition thresholds

    Directory of Open Access Journals (Sweden)

    Lafon M.

    2013-11-01

    Full Text Available The Shock Ignition (SI scheme [1] offers to reduce the laser requirements by relaxing the implosion phase to sub-ignition velocities and later adding an intense laser spike. Depending on laser energy, target characteristics and implosion velocity, high gains are expected [2,3]. Relevant intensities for scaled targets imploded in the velocity range from 150 to 400 km/s are defined at ignition thresholds. A range of moderate implosion velocities is specified to match safe implosions. These conditions for target design are then inferred for relevant NIF and LMJ shock-ignited targets.

  2. Improved Reactive Flow Modeling of the LX-17 Double Shock Experiments

    Science.gov (United States)

    Rehagen, Thomas J.; Vitello, Peter

    2017-06-01

    Over driven double shock experiments provide a measurement of the properties of the reaction product states of the insensitive high explosive LX-17 (92.5% TATB and 7.5% Kel-F by weight). These experiments used two flyer materials mounted on the end of a projectile to send an initial shock through the LX-17, followed by a second shock of a higher magnitude into the detonation products. In the experiments, the explosive was initially driven by the flyer plate to pressures above the Chapman-Jouguet state. The particle velocity history was recorded by Photonic Doppler Velocimetry (PDV) probes pointing at an aluminum foil coated LiF window. The PDV data shows a sharp initial shock and decay, followed by a rounded second shock. Here, the experimental results are compared to 2D and 3D Cheetah reactive flow modeling. Our default Cheetah reactive flow model fails to accurately reproduce the decay of the first shock or the curvature or strength of the second shock. A new model is proposed in which the carbon condensate produced in the reaction zone is controlled by a kinetic rate. This allows the carbon condensate to be initially out of chemical equilibrium with the product gas. This new model reproduces the initial detonation peak and decay, and matches the curvature of the second shock, however, it still over-predicts the strength of the second shock. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  3. Generalized Sagdeev potential theory for shock waves modeling

    Science.gov (United States)

    Akbari-Moghanjoughi, M.

    2017-05-01

    In this paper, we develop an innovative approach to study the shock wave propagation using the Sagdeev potential method. We also present an analytical solution for Korteweg de Vries Burgers (KdVB) and modified KdVB equation families with a generalized form of the nonlinearity term which agrees well with the numerical one. The novelty of the current approach is that it is based on a simple analogy of the particle in a classical potential with the variable particle energy providing one with a deeper physical insight into the problem and can easily be extended to more complex physical situations. We find that the current method well describes both monotonic and oscillatory natures of the dispersive-diffusive shock structures in different viscous fluid configurations. It is particularly important that all essential parameters of the shock structure can be deduced directly from the Sagdeev potential in small and large potential approximation regimes. Using the new method, we find that supercnoidal waves can decay into either compressive or rarefactive shock waves depending on the initial wave amplitude. Current investigation provides a general platform to study a wide range of phenomena related to nonlinear wave damping and interactions in diverse fluids including plasmas.

  4. The Role of Uncoupling Protein 2 During Myocardial Dysfunction in a Canine Model of Endotoxin Shock.

    Science.gov (United States)

    Wang, Xiaoting; Liu, Dawei; Chai, Wenzhao; Long, Yun; Su, Longxiang; Yang, Rongli

    2015-03-01

    To explore the role of uncoupling protein 2 (UCP2) during myocardial dysfunction in a canine model of endotoxin shock, 26 mongrel canines were randomly divided into the following four groups: A (control group; n = 6), B2 (shock after 2 h; n = 7), B4 (shock after 4 h; n = 7), and B6 (shock after 6 h; n = 6). Escherichia coli endotoxin was injected into the canines via the central vein, and hemodynamics were monitored. Energy metabolism, UCP2 mRNA and protein expression, and UCP2 localization were analyzed, and the correlation between energy metabolism changes, and UCP2 expression was determined. After the canine endotoxin shock model was successfully established, the expression of UCP2 mRNA and protein was found to increase, with later time points showing significant increases (P shock (P shock, and UCP2 may play an important role in this process. The negative correlation between UCP2 expression and energy metabolism requires further study, as the results might contribute to the treatment of sepsis with heart failure.

  5. Using numerical models of bow shocks to investigate the circumstellar medium of massive stars

    International Nuclear Information System (INIS)

    Van Marle, A J; Decin, L; Cox, N L J; Meliani, Z

    2015-01-01

    Many massive stars travel through the interstellar medium at supersonic speeds. As a result they form bow shocks at the interface between the stellar wind. We use numerical hydrodynamics to reproduce such bow shocks numerically, creating models that can be compared to observations. In this paper we discuss the influence of two physical phenomena, interstellar magnetic fields and the presence of interstellar dust grains on the observable shape of the bow shocks of massive stars. We find that the interstellar magnetic field, though too weak to restrict the general shape of the bow shock, reduces the size of the instabilities that would otherwise be observed in the bow shock of a red supergiant. The interstellar dust grains, due to their inertia can penetrate deep into the bow shock structure of a main sequence O-supergiant, crossing over from the ISM into the stellar wind. Therefore, the dust distribution may not always reflect the morphology of the gas. This is an important consideration for infrared observations, which are dominated by dust emission. Our models clearly show, that the bow shocks of massive stars are useful diagnostic tools that can used to investigate the properties of both the stellar wind as well as the interstellar medium

  6. Development of solar wind shock models with tensor plasma pressure for data analysis. Final technical report, 1 Aug 1970--31 Dec 1975

    International Nuclear Information System (INIS)

    Abraham-shrauner, B.

    1975-01-01

    The development of solar wind shock models with tensor plasma pressure and the comparison of some of the shock models with the satellite data from Pioneer 6 through Pioneer 9 are reported. Theoretically, difficulties were found in non-turbulent fluid shock models for tensor pressure plasmas. For microscopic shock theories nonlinear growth caused by plasma instabilities was frequently not clearly demonstrated to lead to the formation of a shock. As a result no clear choice for a shock model for the bow shock or interplanetary tensor pressure shocks emerged

  7. Effects of low ambient temperature on hemodynamics and oxygen dynamics in a porcine hemorrhagic shock model

    Directory of Open Access Journals (Sweden)

    Xue-feng ZHANG

    2013-02-01

    Full Text Available Objective  To investigate the effects of low ambient temperature on hemodynamics and oxygen dynamics in a porcine hemorrhagic shock model. Methods  Thirty-two healthy adult Bama miniature pigs were randomly divided into four groups (8 each: control (group C, shock under room temperature (22℃, group R, shock under low ambient temperature (–10℃, group L and shock under normal body temperature (keep pulmonary arterial temperature ranged from 38.5 to 39.5℃, group N. The hemorrhagic shock model was reproduced by venous bleeding (40% of total blood volume, and the core temperature (pulmonary arterial temperature and rectal temperature, heart rate (HR, mean arterial pressure (MAP, pulmonary arterial pressure (PAP, pulmonary arterial wedge pressure (PAWP, central venous pressure (CVP, cardiac output (CO, hemoglobin (Hb, saturation of mixed venous blood (SvO2 and blood gas analysis were recorded before reproduction of shock and at different time points after hemorrhagic shock. The whole body oxygen delivery index (DO2I, oxygen uptake index (VO2I, and oxygen extraction ratio (O2ER were calculated. Results  Four pigs died in group N during the experiment, meanwhile, no pig died in other groups. The core temperature in group C, R and L decreased significantly compared with group N (P<0.05, and the core temperature in group L was significantly lower than that in groups C and R from 120 minutes after shock. No difference was found in hemodynamics, oxygen dynamics and prognosis between group R and group L. The HR and VO2I in group N were significantly higher than those in group L and group R, while there was no difference in other indices between the 3 groups. Conclusion  The hemodynamics and oxygen dynamics indices don't worsen in hemorrhagic shock pigs under low ambient temperature, possibly resulting from induced hypothermia caused by anesthesia.

  8. Mortality Prediction Model of Septic Shock Patients Based on Routinely Recorded Data

    Directory of Open Access Journals (Sweden)

    Marta Carrara

    2015-01-01

    Full Text Available We studied the problem of mortality prediction in two datasets, the first composed of 23 septic shock patients and the second composed of 73 septic subjects selected from the public database MIMIC-II. For each patient we derived hemodynamic variables, laboratory results, and clinical information of the first 48 hours after shock onset and we performed univariate and multivariate analyses to predict mortality in the following 7 days. The results show interesting features that individually identify significant differences between survivors and nonsurvivors and features which gain importance only when considered together with the others in a multivariate regression model. This preliminary study on two small septic shock populations represents a novel contribution towards new personalized models for an integration of multiparameter patient information to improve critical care management of shock patients.

  9. Synchronisation under shocks: The Lévy Kuramoto model

    Science.gov (United States)

    Roberts, Dale; Kalloniatis, Alexander C.

    2018-04-01

    We study the Kuramoto model of identical oscillators on Erdős-Rényi (ER) and Barabasi-Alberts (BA) scale free networks examining the dynamics when perturbed by a Lévy noise. Lévy noise exhibits heavier tails than Gaussian while allowing for their tempering in a controlled manner. This allows us to understand how 'shocks' influence individual oscillator and collective system behaviour of a paradigmatic complex system. Skewed α-stable Lévy noise, equivalent to fractional diffusion perturbations, are considered, but overlaid by exponential tempering of rate λ. In an earlier paper we found that synchrony takes a variety of forms for identical Kuramoto oscillators subject to stable Lévy noise, not seen for the Gaussian case, and changing with α: a noise-induced drift, a smooth α dependence of the point of cross-over of synchronisation point of ER and BA networks, and a severe loss of synchronisation at low values of α. In the presence of tempering we observe both analytically and numerically a dramatic change to the α behaviour where synchronisation is sustained over a larger range of values of the 'noise strength' σ, improved compared to the α > 1 tempered cases. Analytically we study the system close to the phase synchronised fixed point and solve the tempered fractional Fokker-Planck equation. There we observe that densities show stronger support in the basin of attraction at low α for fixed coupling, σ and tempering λ. We then perform numerical simulations for networks of size N = 1000 and average degree d ¯ = 10. There, we compute the order parameter r as a function of σ for fixed α and λ and observe values of r ≈ 1 over larger ranges of σ for α < 1 and λ ≠ 0. In addition we observe drift of both positive and negative slopes for different α and λ when native frequencies are equal, and confirm a sustainment of synchronisation down to low values of α. We propose a mechanism for this in terms of the basic shape of the tempered stable L

  10. Business Cycle Effects of Credit and Technology Shocks in a DSGE Model with Firm Defaults

    OpenAIRE

    Pesaran, Hashem; Xu, TengTeng

    2011-01-01

    This paper proposes a theoretical framework to analyze the impacts of credit and technology shocks on business cycle dynamics, where firms rely on banks and households for capital financing. Firms are identical ex ante but differ ex post due to different realizations of firm specific technology shocks, possibly leading to default by some firms. The paper advances a new modelling approach for the analysis of financial intermediation and firm defaults that takes account of the financial implica...

  11. Mathematical Modeling of the Heat-Shock Response in HeLa Cells

    Science.gov (United States)

    2015-07-01

    concentration as a representative of damage because free misfolded proteins are known to play a critical cytotoxic role in the response to hyperthermia...heat-shock protein dynamics in the long-term heat-shock response. In addition, our model was able to consis- tently predict the extent of damage produced...mech- anism to mitigate the cytotoxic effects of damaged or mis- folded proteins . In addition to heat stress, a variety of other physiological

  12. International Students from Melbourne Describing Their Cross-Cultural Transitions Experiences: Culture Shock, Social Interaction, and Friendship Development

    OpenAIRE

    Belford, Nish

    2017-01-01

    Drawing from a study that explored how international students experience cross-cultural transitions after living and studying in Melbourne for a few years, this paper, in particular, examines the participants' experiences with culture shock, social interaction, and friendship development. The findings include narratives of their personal stories and perspectives on social engagement and friendship ties with a particular focus on variables including cultural similarity, inter...

  13. Could a multi-PeV neutrino event have as origin the internal shocks inside the GRB progenitor star?

    Science.gov (United States)

    Fraija, N.

    2016-03-01

    The IceCube Collaboration initially reported the detection of 37 extraterrestrial neutrinos in the TeV-PeV energy range. The reconstructed neutrino events were obtained during three consecutive years of data taking, from 2010 to 2013. Although these events have been discussed to have an extragalactic origin, they have not been correlated to any known source. Recently, the IceCube Collaboration reported a neutrino-induced muon event with energy of 2.6 ± 0.3 PeV which corresponds to the highest event ever detected. Neither the reconstructed direction of this event (J2000.0), detected on June 11 2014 at R.A. = 110 ° . 34, Dec. = 11 ° . 48 matches with any familiar source. Long gamma-ray bursts (lGRBs) are usually associated with the core collapse of massive stars leading relativistic-collimated jets inside stars with high-energy neutrino production. These neutrinos have been linked to the 37 events previously detected by IceCube experiment. In this work, we explore the conditions and values of parameters so that the highest neutrino recently detected could be generated by proton-photon and proton-hadron interactions at internal shocks inside lGRB progenitor star and then detected in IceCube experiment. Considering that internal shocks take place in a relativistic collimated jet, whose (half) opening angle is θ0 ∼ 0.1, we found that lGRBs with total luminosity L ≲1048 erg/s and internal shocks on the surface of progenitors such as Wolf-Rayet (WR) and blue super giant (BSG) stars favor this multi-PeV neutrino production, although this neutrino could be associated with L ∼1050.5 (∼1050) erg/s provided that the internal shocks occur at ∼109 (∼1010.2) cm for a WR (BSG).

  14. Astrophysical radiative shocks: From modeling to laboratory experiments

    Czech Academy of Sciences Publication Activity Database

    Gonzales, N.; Stehlé, C.; Audit, E.; Busquet, M.; Rus, Bedřich; Thais, F.; Acef, O.; Barroso, P.; Bar-Shalom, A.; Bauduin, D.; Kozlová, Michaela; Lery, T.; Madouri, A.; Mocek, Tomáš; Polan, Jiří

    2006-01-01

    Roč. 24, - (2006), s. 535-540 ISSN 0263-0346 EU Projects: European Commission(XE) 506350 - LASERLAB-EUROPE; European Commission(XE) 5592 - JETSET Grant - others:CNRS(FR) PNPS Institutional research plan: CEZ:AV0Z10100523 Keywords : laboratory astrophysics * laser plasmas * radiative shock waves * radiative transfer Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.958, year: 2006

  15. Shock-darkening in ordinary chondrites: impact modelling

    Czech Academy of Sciences Publication Activity Database

    Moreau, J.; Kohout, Tomáš; Wünnemann, K.

    2016-01-01

    Roč. 88, Special volume (2016), s. 285-285 ISSN 0367-5211. [Nordic Geological Winter Meeting /32./. 13.01.2016-15.01.2016, Helsinki] Institutional support: RVO:67985831 Keywords : impact, shock * reflectance spectra * chondrite * meteorite * Chelyabinsk Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics http://www.geologinenseura.fi/bulletin/Special_Volume_1_2016/BGSF-NGWM2016_Abstract_Volume.pdf

  16. The Terrestrial Bow Shock: A Comparison of New Data from the IBEX Mission to Existing Models

    Science.gov (United States)

    Hart, S. T.; Janzen, P. H.; Reisenfeld, D. B.

    2017-12-01

    For over 50 years, models predicting the position and shape of the bow shock have been empirically produced and examined. Accurate bow shock models provide deeper understanding of the interaction between Earth's magnetosphere and the solar wind. To date, most bow shock studies have incorporated bow shock crossings within 35 RE of the Earth, or in the distant tail region (about 200 RE downstream of the Earth). Since late December 2008, the Interstellar Boundary Explorer (IBEX) has orbited earth nearly 400 times to date, collecting the position of over 600 bow shock and magnetopause crossings between 15 and 50 RE, making the IBEX data set unique for the study of the magnetosheath structure between 35 and 50 RE. With crossings determined from IBEX-Hi data, and the use of the OMNI-2 dataset to provide corresponding upstream solar wind conditions and IMF data, we will test how well the leading published bow shock models (e.g. Merka et al. 2005, Jerab et al. 2005) match the shape of these boundaries in this unexplored region.

  17. Finite element modelling of radial shock wave therapy for chronic plantar fasciitis.

    Science.gov (United States)

    Alkhamaali, Zaied K; Crocombe, Andrew D; Solan, Matthew C; Cirovic, Srdjan

    2016-01-01

    Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression-rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot.

  18. Reynolds stress turbulence model applied to two-phase pressurized thermal shocks in nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Mérigoux, Nicolas, E-mail: nicolas.merigoux@edf.fr; Laviéville, Jérôme; Mimouni, Stéphane; Guingo, Mathieu; Baudry, Cyril

    2016-04-01

    Highlights: • NEPTUNE-CFD is used to model two-phase PTS. • k-ε model did produce some satisfactory results but also highlights some weaknesses. • A more advanced turbulence model has been developed, validated and applied for PTS. • Coupled with LIM, the first results confirmed the increased accuracy of the approach. - Abstract: Nuclear power plants are subjected to a variety of ageing mechanisms and, at the same time, exposed to potential pressurized thermal shock (PTS) – characterized by a rapid cooling of the internal Reactor Pressure Vessel (RPV) surface. In this context, NEPTUNE-CFD is used to model two-phase PTS and give an assessment on the structural integrity of the RPV. The first available choice was to use standard first order turbulence model (k-ε) to model high-Reynolds number flows encountered in Pressurized Water Reactor (PWR) primary circuits. In a first attempt, the use of k-ε model did produce some satisfactory results in terms of condensation rate and temperature field distribution on integral experiments, but also highlights some weaknesses in the way to model highly anisotropic turbulence. One way to improve the turbulence prediction – and consequently the temperature field distribution – is to opt for more advanced Reynolds Stress turbulence Model. After various verification and validation steps on separated effects cases – co-current air/steam-water stratified flows in rectangular channels, water jet impingements on water pool free surfaces – this Reynolds Stress turbulence Model (R{sub ij}-ε SSG) has been applied for the first time to thermal free surface flows under industrial conditions on COSI and TOPFLOW-PTS experiments. Coupled with the Large Interface Model, the first results confirmed the adequacy and increased accuracy of the approach in an industrial context.

  19. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)

    NARCIS (Netherlands)

    Singer, Mervyn; Deutschman, Clifford S.; Seymour, Christopher Warren; Shankar-Hari, Manu; Annane, Djillali; Bauer, Michael; Bellomo, Rinaldo; Bernard, Gordon R.; Chiche, Jean-Daniel; Coopersmith, Craig M.; Hotchkiss, Richard S.; Levy, Mitchell M.; Marshall, John C.; Martin, Greg S.; Opal, Steven M.; Rubenfeld, Gordon D.; van der Poll, Tom; Vincent, Jean-Louis; Angus, Derek C.

    2016-01-01

    IMPORTANCE Definitions of sepsis and septic shock were last revised in 2001. Considerable advances have since been made into the pathobiology (changes in organ function, morphology, cell biology, biochemistry, immunology, and circulation), management, and epidemiology of sepsis, suggesting the need

  20. Well-posed Euler model of shock-induced two-phase flow in bubbly liquid

    Science.gov (United States)

    Tukhvatullina, R. R.; Frolov, S. M.

    2018-03-01

    A well-posed mathematical model of non-isothermal two-phase two-velocity flow of bubbly liquid is proposed. The model is based on the two-phase Euler equations with the introduction of an additional pressure at the gas bubble surface, which ensures the well-posedness of the Cauchy problem for a system of governing equations with homogeneous initial conditions, and the Rayleigh-Plesset equation for radial pulsations of gas bubbles. The applicability conditions of the model are formulated. The model is validated by comparing one-dimensional calculations of shock wave propagation in liquids with gas bubbles with a gas volume fraction of 0.005-0.3 with experimental data. The model is shown to provide satisfactory results for the shock propagation velocity, pressure profiles, and the shock-induced motion of the bubbly liquid column.

  1. Solvency ii. partial internal model

    OpenAIRE

    Baltrėnas, Rokas

    2016-01-01

    Solvency II. Partial Internal Model Solvency is one of the most important characteristics of the insurance company. Sufficient solvency ratio ensures long–term performance of the company and the necessary protection of policyholders. The new solvency assessment framework (Solvency II) came into force across the EU on 1 January 2016. It is based on a variety of risk evaluation modules, so it better reflects the real state of the company’s solvency. Under the Solvency II insurance company’s sol...

  2. Do oil shocks predict economic policy uncertainty?

    Science.gov (United States)

    Rehman, Mobeen Ur

    2018-05-01

    Oil price fluctuations have influential role in global economic policies for developed as well as emerging countries. I investigate the role of international oil prices disintegrated into structural (i) oil supply shock, (ii) aggregate demand shock and (iii) oil market specific demand shocks, based on the work of Kilian (2009) using structural VAR framework on economic policies uncertainty of sampled markets. Economic policy uncertainty, due to its non-linear behavior is modeled in a regime switching framework with disintegrated structural oil shocks. Our results highlight that Indian, Spain and Japanese economic policy uncertainty responds to the global oil price shocks, however aggregate demand shocks fail to induce any change. Oil specific demand shocks are significant only for China and India in high volatility state.

  3. Modeling the internal combustion engine

    Science.gov (United States)

    Zeleznik, F. J.; Mcbride, B. J.

    1985-01-01

    A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics.

  4. A Discontinuous Galerkin Method for Two-Dimensional Shock Wave Modeling

    Directory of Open Access Journals (Sweden)

    W. Lai

    2011-01-01

    Full Text Available A numerical scheme based on discontinuous Galerkin method is proposed for the two-dimensional shallow water flows. The scheme is applied to model flows with shock waves. The form of shallow water equations that can eliminate numerical imbalance between flux term and source term and simplify computation is adopted here. The HLL approximate Riemann solver is employed to calculate the mass and momentum flux. A slope limiting procedure that is suitable for incompressible two-dimensional flows is presented. A simple method is adapted for flow over initially dry bed. A new formulation is introduced for modeling the net pressure force and gravity terms in discontinuous Galerkin method. To validate the scheme, numerical tests are performed to model steady and unsteady shock waves. Applications include circular dam break with shock, shock waves in channel contraction, and dam break in channel with 45∘ bend. Numerical results show that the scheme is accurate and efficient to model two-dimensional shallow water flows with shock waves.

  5. Thermodynamic parameters for mixtures of quartz under shock wave loading in views of the equilibrium model

    International Nuclear Information System (INIS)

    Maevskii, K. K.; Kinelovskii, S. A.

    2015-01-01

    The numerical results of modeling of shock wave loading of mixtures with the SiO 2 component are presented. The TEC (thermodynamic equilibrium component) model is employed to describe the behavior of solid and porous multicomponent mixtures and alloys under shock wave loading. State equations of a Mie–Grüneisen type are used to describe the behavior of condensed phases, taking into account the temperature dependence of the Grüneisen coefficient, gas in pores is one of the components of the environment. The model is based on the assumption that all components of the mixture under shock-wave loading are in thermodynamic equilibrium. The calculation results are compared with the experimental data derived by various authors. The behavior of the mixture containing components with a phase transition under high dynamic loads is described

  6. Evidence on a Real Business Cycle Model with Neutral and Investment-Specific Technology Shocks using Bayesian Model Averaging

    NARCIS (Netherlands)

    R.W. Strachan (Rodney); H.K. van Dijk (Herman)

    2010-01-01

    textabstractThe empirical support for a real business cycle model with two technology shocks is evaluated using a Bayesian model averaging procedure. This procedure makes use of a finite mixture of many models within the class of vector autoregressive (VAR) processes. The linear VAR model is

  7. A multiple-scales model of the shock-cell structure of imperfectly expanded supersonic jets

    Science.gov (United States)

    Tam, C. K. W.; Jackson, J. A.; Seiner, J. M.

    1985-01-01

    The present investigation is concerned with the development of an analytical model of the quasi-periodic shock-cell structure of an imperfectly expanded supersonic jet. The investigation represents a part of a program to develop a mathematical theory of broadband shock-associated noise of supersonic jets. Tam and Tanna (1982) have suggested that this type of noise is generated by the weak interaction between the quasi-periodic shock cells and the downstream-propagating large turbulence structures in the mixing layer of the jet. In the model developed in this paper, the effect of turbulence in the mixing layer of the jet is simulated by the addition of turbulent eddy-viscosity terms to the momentum equation. Attention is given to the mean-flow profile and the numerical solution, and a comparison of the numerical results with experimental data.

  8. Chemical kinetics modeling of the influence of molecular structure on shock tube ignition delay

    International Nuclear Information System (INIS)

    Westbrook, C.K.; Pitz, W.J.

    1985-07-01

    The current capabilities of kinetic modeling of hydrocarbon oxidation in shock waves are discussed. The influence of molecular size and structure on ignition delay times are stressed. The n-paraffin fuels from CH 4 to n-C 5 H 12 are examined under shock tube conditions, as well as the branched chain fuel isobutane, and the computed results are compared with available experimental data. The modeling results show that it is important in the reaction mechanism to distinguish between abstraction of primary, secondary and tertiary H atom sites from the fuel molecule. This is due to the fact that both the rates and the product distributions of the subsequent alkyl radical decomposition reactions depend on which H atoms were abstracted. Applications of the reaction mechanisms to shock tube problems and to other practical problems such as engine knock are discussed

  9. [Adherence to international guidelines on early management in severe sepsis and septic shock].

    Science.gov (United States)

    Quintero, Ricardo Andrés; Martínez, Carlos Arturo; Gamba, Juan Diego; Ortiz, Isadora; Jaimes, Fabián

    2012-09-01

    Complete adherence to early goal-directed therapy has shown a significant reduction in 28-day mortality rate, whereas partial adherence has not shown beneficial effect. The effect of adherence to 6 hour sepsis bundle treatment was evaluated on patients with severe sepsis and septic shock. A prospective cohort study was conducted during a six-month period. The patients were limited to those 16 years or older and included admissions to intensive care units, special care units or emergency departments with severe sepsis or septic shock. The adherence to the 6-hour sepsis bundle was evaluated through 8 interventions as follows: (1) serum lactate measure,( 2) early antibiotic administration, (3) blood culture samples, (4) infusion of intravenous fluids, (5) vasopressor use, (6) central venous catheter, (7) central venous pressure >8 mm Hg, and (8) central venous oxygen saturation >70%. Seven hundred and twenty three patients were screened; 16% (n=116) met the inclusion criteria; 92.2% (n=107) met the criteria for severe sepsis and 37.9% (44) for septic shock; 62.9% (n=73) were subdiagnosed. Complete adherence to the 8 interventions of 6-hour sepsis bundle was 0%; 6 to 7 (19%, n=22), 3 to 5 (67.2%, n=78), and 0 to 2 (98.3%, n=114). Adherence to 6-hour sepsis bundle treatment for severe sepsis and septic shock was not done for the full 8 interventions and only partial accomplishment of the first 4 interventions.

  10. A minimal titration model of the mammalian dynamical heat shock response

    Science.gov (United States)

    Sivéry, Aude; Courtade, Emmanuel; Thommen, Quentin

    2016-12-01

    Environmental stress, such as oxidative or heat stress, induces the activation of the heat shock response (HSR) and leads to an increase in the heat shock proteins (HSPs) level. These HSPs act as molecular chaperones to maintain cellular proteostasis. Controlled by highly intricate regulatory mechanisms, having stress-induced activation and feedback regulations with multiple partners, the HSR is still incompletely understood. In this context, we propose a minimal molecular model for the gene regulatory network of the HSR that reproduces quantitatively different heat shock experiments both on heat shock factor 1 (HSF1) and HSPs activities. This model, which is based on chemical kinetics laws, is kept with a low dimensionality without altering the biological interpretation of the model dynamics. This simplistic model highlights the titration of HSF1 by chaperones as the guiding line of the network. Moreover, by a steady states analysis of the network, three different temperature stress regimes appear: normal, acute, and chronic, where normal stress corresponds to pseudo thermal adaption. The protein triage that governs the fate of damaged proteins or the different stress regimes are consequences of the titration mechanism. The simplicity of the present model is of interest in order to study detailed modelling of cross regulation between the HSR and other major genetic networks like the cell cycle or the circadian clock.

  11. Health care delivery through a different lens: the lived experience of culture shock while participating in an international educational program.

    Science.gov (United States)

    Egenes, Karen J

    2012-10-01

    An international educational experience can enhance the curriculum of an undergraduate program in nursing and can promote student development. However, many students who participate in international programs experience the debilitating effects of symptoms that comprise a phenomenon that is sometimes labeled culture shock. The progress of American nursing students through the stages of adaptation to a different culture is examined through journal entries the students recorded while they were in England for a short-term experience in community health nursing. The benefits of participation in an international program are discussed. Also included are guidelines for faculty to help them recognize the symptoms described and to implement appropriate interventions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Shock-to-detonation transition of RDX and NTO based composite high explosives: experiments and modeling

    Science.gov (United States)

    Baudin, Gerard; Roudot, Marie; Genetier, Marc

    2013-06-01

    Composite HMX and NTO based high explosives (HE) are widely used in ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside HE. Comparing to a pressed HE, a composite HE is not porous and the hot-spots are mainly located at the grain - binder interface leading to a different behavior during shock-to-detonation transition. An investigation of how shock-to-detonation transition occurs inside composite HE containing RDX and NTO is proposed in this lecture. Two composite HE have been studied. The first one is HMX - HTPB 82:18. The second one is HMX - NTO - HTPB 12:72:16. These HE have been submitted to plane sustained shock waves at different pressure levels using a laboratory powder gun. Pressure signals are measured using manganin gauges inserted at several distances inside HE. The corresponding run-distances to detonation are determined using wedge test experiments where the plate impact is performed using a powder gun. Both HE exhibit a single detonation buildup curve in the distance - time diagram of shock-to-detonation transition. This feature seems a common shock-to-detonation behavior for composite HE without porosity. This behavior is also confirmed for a RDX - HTPB 85:15 based composite HE. Such a behavior is exploited to determine the heterogeneous reaction rate versus the shock pressure using a method based on the Cauchy-Riemann problem inversion. The reaction rate laws obtained allow to compute both run-distance to detonation and pressure signals.

  13. Use of high-dose nandrolone aggravates septic shock in a mouse model

    Directory of Open Access Journals (Sweden)

    Che Lin

    2011-06-01

    Full Text Available Nandrolone, an anabolic-androgenic steroid, is widely misused by athletes who wish to rapidly increase muscle mass and performance. An increasing number of reports have indicated that nandrolone may affect and modulate the immune system. This study aimed to investigate the effects of nandrolone on septic shock-caused immune responses and the cellular mechanism of action using a sepsis murine model. Before septic shock induction, BALB/c mice were given a high dose of nandrolone or peanut oil only. After septic shock induction, mice were sacrificed at different time points. Their blood and tissue specimens were analyzed. It was found that the high-dose nandrolone group had significantly increased mortality compared with the control group (p<0.001. The serum malondialdehyde level was significantly increased in the high-dose group compared with the control group. Animals administered a high dose of nandrolone had significantly increased hepatic tumor necrosis factor-α or splenic interferon-γ at 0 and 6 hours. In lung tissue, insulin-like growth factor-1, insulin-like growth factor binding proteins (IGFBPs and insulin-like growth factor-1 receptor, and IGFBP1 and IGFBP2 mRNA expression were increased in the high-dose nandrolone group at 6 hours. Nandrolone abuse may hasten the death of patients with septic shock and may aggravate septic shock in mice.

  14. Atomic Scale Modeling of Laser Shock induced Spallation of FCC Metals

    Science.gov (United States)

    Galitskiy, Sergey; Ivanov, Dmitry; Dongare, Avinash

    2017-06-01

    An atomistic-continuum approach combining the molecular dynamics (MD) simulations with a two temperature model (TTM) was used to simulate the laser induced shock loading and spall failure in FCC metals. The combined TTM-MD approach incorporates the laser energy absorption, fast electron heat conduction, and the electron-phonon non-equilibrium interaction, as well as the shock wave propagation, plastic deformation, and failure processes (spallation) in metals at atomic scales. The simulations are carried out for systems corresponding to dimensions of up to 500 nm in the loading direction for various Cu and Al microstructures and laser loading conditions (intensity and pulse durations). The front end of the metal that absorbs the laser energy is observed to undergo melting and a shock wave is generated that travels towards the rear surface. The shock wave reaches the rear surface, reflects, and interacts with the its tail to create a high triaxial tensile stress region and initiates spall failure (void nucleation). The predicted values of spall strength and wave velocities of shock waves compare very well with experimentally reported values at these dimensions and laser loading conditions. The effect of microstructure and the defect evolution in the system on the predicted spall failure behavior will be presented.

  15. Modeling shock waves in an ideal gas: Going beyond the Navier-Stokes level

    International Nuclear Information System (INIS)

    Holian, B.L.; Patterson, C.W.; Mareschal, M.; Salomons, E.

    1993-01-01

    We model a shock wave in an ideal gas by solving a modified version of the compressible Navier-Stokes equations of hydrodynamics, where, following an earlier conjecture by Holian [Phys. Rev. A 37, 2562 (1988)], we use the temperature in the direction of shock propagation T xx , rather than the average temperature T=(T xx +T yy +T zz )/3, in the evaluation of the linear transport coefficients. The results are found to agree much better with the molecular-dynamics simulations of Salomons and Mareschal [Phys. Rev. Lett. 69, 269 (1992)] than standard Navier-Stokes theory

  16. Laser Beam Propagation Through Inhomogeneous Media with Shock-Like Profiles: Modeling and Computing

    Science.gov (United States)

    Adamovsky, Grigory; Ida, Nathan

    1997-01-01

    Wave propagation in inhomogeneous media has been studied for such diverse applications as propagation of radiowaves in atmosphere, light propagation through thin films and in inhomogeneous waveguides, flow visualization, and others. In recent years an increased interest has been developed in wave propagation through shocks in supersonic flows. Results of experiments conducted in the past few years has shown such interesting phenomena as a laser beam splitting and spreading. The paper describes a model constructed to propagate a laser beam through shock-like inhomogeneous media. Numerical techniques are presented to compute the beam through such media. The results of computation are presented, discussed, and compared with experimental data.

  17. A Critical Assessment of Burn Models Available for Implementation into a Computer Code to Model Shock Initiation of Heterogeneous Explosives

    Science.gov (United States)

    1989-07-01

    includes a dependence on the shock strength has been described by Damamme and Missonier [391 and is known as the Krakatoa model. It has the form dA...is a function which depends on the shock strength, and Am and ’a are constants. K(P) = pn (27) and H(A) = (Q - A) [2n (1 - 2/3 (28) 17 The Krakatoa ...with the model. Both the DAGMAR and Krakatoa models are also inappropriate, as neither addresses the problem of particle size effects. The multiphase

  18. The Sandia MEMS Passive Shock Sensor : FY08 testing for functionality, model validation, and technology readiness.

    Energy Technology Data Exchange (ETDEWEB)

    Walraven, Jeremy Allen; Blecke, Jill; Baker, Michael Sean; Clemens, Rebecca C.; Mitchell, John Anthony; Brake, Matthew Robert; Epp, David S.; Wittwer, Jonathan W.

    2008-10-01

    This report summarizes the functional, model validation, and technology readiness testing of the Sandia MEMS Passive Shock Sensor in FY08. Functional testing of a large number of revision 4 parts showed robust and consistent performance. Model validation testing helped tune the models to match data well and identified several areas for future investigation related to high frequency sensitivity and thermal effects. Finally, technology readiness testing demonstrated the integrated elements of the sensor under realistic environments.

  19. Nonrelativistic Perpendicular Shocks Modeling Young Supernova Remnants: Nonstationary Dynamics and Particle Acceleration at Forward and Reverse Shocks

    Science.gov (United States)

    Wieland, Volkmar; Pohl, Martin; Niemiec, Jacek; Rafighi, Iman; Nishikawa, Ken-Ichi

    2016-03-01

    For parameters that are applicable to the conditions at young supernova remnants, we present results of two-dimensional, three-vector (2D3V) particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at a 45^\\circ angle to the simulation plane to approximate three-dimensional (3D) physics. We developed an improved clean setup that uses the collision of two plasma slabs with different densities and velocities, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations due to shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales produced by the gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but is commensurate with {\\boldsymbol{E}}× {\\boldsymbol{B}} drift. We observe a stable supra-thermal tail in the ion spectra, but no electron acceleration because the amplitude of the Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other two-dimensional (2D) simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but the pre-acceleration efficacy might be reduced with respect to the 2D results once 3D effects are fully accounted for. Other microphysical factors may also play a part in limiting the amplitude of the Buneman waves or preventing the return of electrons to the foot region.

  20. Essays in the Application of Linear and Non-linear Bayesian VAR Models to the Macroeconomic Impacts of Energy Price Shocks

    Science.gov (United States)

    Nguyen, Bao H.

    This thesis is a collection of five self contained empirical macroeconomic papers on the asymmetric effects of energy price shocks on various economies. Chapter 1 formally determines the number of regime changes in the US natural gas market by employing a MS-VAR model. Estimated using Bayesian methods, three regimes are identified for the period 1980 - 2016, namely, before the Decontrol Act, after the Decontrol Act and the Recession. The results show that the natural gas market tends to be much more sensitive to market fundamental shocks occurring in a Recession regime than in the other regimes. Augmenting the model by incorporating the price of crude oil, the results reveal that the impacts of oil price shocks on natural gas prices are relatively small. Chapter 2 provides new empirical evidence on the asymmetric reactions of the U.S. natural gas market and the U.S. economy to its market fundamental shocks in different phases of the business cycle. To this end, we employ a ST-VAR model to capture the asymmetric responses depending on economic conditions. Our results indicate that in contrast to the prediction made by a linear VAR model, the STVAR model provides a plausible explanation to the behavior of the U.S. natural gas market, which asymmetrically reacts in bad times and good times. Chapter 3 examines the relationship between China's economic growth and global oil market fluctuations between 1992Q1 and 2015Q3. We find that: (1) the time varying parameter VAR with stochastic volatility provides a better fit as compared to it's constant counterparts; (2) the impacts of intertemporal global oil price shocks on China's output are often small and temporary in nature; (3) oil supply and specific oil demand shocks generally produce negative movements in China's GDP growth whilst oil demand shocks tend to have positive effects; (4) domestic output shocks have no significant impact on price or quantity movements within the global oil market. Chapter 4 examines the

  1. A Shock-Refracted Acoustic Wave Model for the Prediction of Screech Amplitude in Supersonic Jets

    Science.gov (United States)

    Kandula, Max

    2007-01-01

    A physical model is proposed for the estimation of the screech amplitude in underexpanded supersonic jets. The model is based on the hypothesis that the interaction of a plane acoustic wave with stationary shock waves provides amplification of the transmitted acoustic wave upon traversing the shock. Powell's discrete source model for screech incorporating a stationary array of acoustic monopoles is extended to accommodate variable source strength. The proposed model reveals that the acoustic sources are of increasing strength with downstream distance. It is shown that the screech amplitude increases with the fuiiy expanded jet Mach number. Comparisons of predicted screech amplitude with available test data show satisfactory agreement. The effect of variable source strength on directivity of the fundamental (first harmonic, lowest frequency mode) and the second harmonic (overtone) is found to be unimportant with regard to the principal lobe (main or major lobe) of considerable relative strength, and is appreciable only in the secondary or minor lobes (of relatively weaker strength

  2. Stochastic modeling for reliability shocks, burn-in and heterogeneous populations

    CERN Document Server

    Finkelstein, Maxim

    2013-01-01

    Focusing on shocks modeling, burn-in and heterogeneous populations, Stochastic Modeling for Reliability naturally combines these three topics in the unified stochastic framework and presents numerous practical examples that illustrate recent theoretical findings of the authors.  The populations of manufactured items in industry are usually heterogeneous. However, the conventional reliability analysis is performed under the implicit assumption of homogeneity, which can result in distortion of the corresponding reliability indices and various misconceptions. Stochastic Modeling for Reliability fills this gap and presents the basics and further developments of reliability theory for heterogeneous populations. Specifically, the authors consider burn-in as a method of elimination of ‘weak’ items from heterogeneous populations. The real life objects are operating in a changing environment. One of the ways to model an impact of this environment is via the external shocks occurring in accordance with some stocha...

  3. THE INTERNAL CONTROL MODELS IN ROMANIA

    Directory of Open Access Journals (Sweden)

    TEODORESCU CRISTIAN DRAGOȘ

    2015-06-01

    Full Text Available Internal control is indissolubly linked to business and accounting. Throughout history, domestic and international trade has grown exponentially, which has led to an increasing complexity of internal control, to new methods and techniques to control the business. The literature has presented the first models of internal control in the Sumerian period (3600 - 3200 BC, and the emergence and development of internal control in Egypt, Persia, Greek and Roman Empire, in the Middle Ages till modern times. The purpose of this article is to present the models of internal control in Romania, starting from the principles of the classical model of internal control (COSO model. For a better understanding of the implication of internal control in terms of public and private sector, I have structured the article in the following parts: (a the definition of internal control in the literature; (b the presentation of the COSO model; (c internal control and internal audit in public institutions; (d internal control issues in accounting regulations on the individual and consolidated annual financial statements; (e internal / managerial control; (f conclusions.

  4. A Novel Porcine Model of Septic Shock Induced by Acute Respiratory Distress Syndrome due to Methicillin-resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Shuo Wang

    2017-01-01

    Conclusions: In the present study, we developed a novel porcine model of septic shock induced by ARDS due to severe MRSA pneumonia with characteristic hyperdynamic and hypodynamic phases in 24 h, which mimicked the hemodynamic changing of septic shock in human.

  5. Fresh Frozen Plasma Modulates Brain Gene Expression in a Swine Model of Traumatic Brain Injury and Shock

    DEFF Research Database (Denmark)

    Sillesen, Martin; Bambakidis, Ted; Dekker, Simone E

    2017-01-01

    BACKGROUND: Resuscitation with fresh frozen plasma (FFP) decreases brain lesion size and swelling in a swine model of traumatic brain injury and hemorrhagic shock. We hypothesized that brain gene expression profiles after traumatic brain injury and hemorrhagic shock would be modulated by FFP resu...

  6. Developing a New Definition and Assessing New Clinical Criteria for Septic Shock For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)

    NARCIS (Netherlands)

    Shankar-Hari, Manu; Phillips, Gary S.; Levy, Mitchell L.; Seymour, Christopher W.; Liu, Vincent X.; Deutschman, Clifford S.; Angus, Derek C.; Rubenfeld, Gordon D.; Singer, Mervyn; Angus, Derek; Annane, Djilalli; Bauer, Michael; Bellomo, Rinaldo; Bernard, Gordon; Chiche, Jean-Daniel; Coopersmith, Craig; Deutschman, Cliff; Hotchkiss, Richard; Levy, Mitchell; Marshall, John; Martin, Greg; Opal, Steve; Rubenfeld, Gordon; Seymour, Christopher; van der Poll, Tom; Vincent, Jean-Louis

    2016-01-01

    IMPORTANCE Septic shock currently refers to a state of acute circulatory failure associated with infection. Emerging biological insights and reported variation in epidemiology challenge the validity of this definition. OBJECTIVE To develop a new definition and clinical criteria for identifying

  7. Modeling of plastic localization in aluminum and Al–Cu alloys under shock loading

    International Nuclear Information System (INIS)

    Krasnikov, V.S.; Mayer, A.E.

    2014-01-01

    This paper focuses on the modeling of plastic deformation localization in pure aluminum and aluminum–copper alloys during the propagation of a plane shock wave. Modeling is carried out with the use of continual dislocation plasticity model in 2-D geometry. It is shown that the formation of localization bands occurs at an angle of 45° to the direction of propagation of the shock front. Effective initiators for plastic localization in pure aluminum are the perturbations of the initial dislocation density, in the alloys – perturbations of the dislocation density and the concentration of copper atoms. Perturbations of temperature field in a range of tens of kelvins are not so effective for plastic localization. In the alloy plastic localization intensity decreases with an increase of strain rate due to the thermally activated nature of the dislocation motion

  8. A System Shock Approach to Modelling Clandestine Network Disruption

    National Research Council Canada - National Science Library

    Dipper, Tamlan

    2004-01-01

    .... This model took as its focus the disruption of successful terrorist operations. In doing so it drew upon operational art, group behavioural studies, and psychological research into problem solving...

  9. Oscillations in a Growth Model with Capital, Technology and Environment with Exogenous Shocks

    Directory of Open Access Journals (Sweden)

    Wei-Bin Zhang

    2015-07-01

    Full Text Available This paper generalizes the dynamic growth model with wealth accumulation, technological change and environmental change by Zhang (2012 by making all the parameters as time-dependent parameters. The model treats physical capital accumulation, knowledge creation and utilization, and environmental change as endogenous variables. It synthesizes the basic ideas of the neoclassical growth theory, Arrow’s learning-by-doing model and the traditional dynamic models of environmental change within a comprehensive framework. The behavior of the household is described with an alternative approach to household behavior. We simulated the model to demonstrate existence of equilibrium points, motion of the dynamic system, and oscillations due to different exogenous shocks.

  10. Effective Acceleration Model for the Arrival Time of Interplanetary Shocks driven by Coronal Mass Ejections

    Science.gov (United States)

    Paouris, Evangelos; Mavromichalaki, Helen

    2017-12-01

    In a previous work (Paouris and Mavromichalaki in Solar Phys. 292, 30, 2017), we presented a total of 266 interplanetary coronal mass ejections (ICMEs) with as much information as possible. We developed a new empirical model for estimating the acceleration of these events in the interplanetary medium from this analysis. In this work, we present a new approach on the effective acceleration model (EAM) for predicting the arrival time of the shock that preceds a CME, using data of a total of 214 ICMEs. For the first time, the projection effects of the linear speed of CMEs are taken into account in this empirical model, which significantly improves the prediction of the arrival time of the shock. In particular, the mean value of the time difference between the observed time of the shock and the predicted time was equal to +3.03 hours with a mean absolute error (MAE) of 18.58 hours and a root mean squared error (RMSE) of 22.47 hours. After the improvement of this model, the mean value of the time difference is decreased to -0.28 hours with an MAE of 17.65 hours and an RMSE of 21.55 hours. This improved version was applied to a set of three recent Earth-directed CMEs reported in May, June, and July of 2017, and we compare our results with the values predicted by other related models.

  11. The Prevalence and Significance of Overt Disseminated Intravascular Coagulation in Patients with Septic Shock in the Emergency Department According to the Third International Consensus Definition

    Directory of Open Access Journals (Sweden)

    Byuk Sung Ko

    2016-11-01

    Full Text Available Background The prevalence and prognostic value of overt disseminated intravascular coagulation (DIC in patients with septic shock presenting to emergency departments (EDs is poorly understood, particularly following the release of a new definition of septic shock. The purpose of this study was to investigate the prevalence and prognostic value of DIC in septic shock. Methods We performed retrospective review of 391 consecutive patients with septic shock admitting to the ED of tertiary care, university-affiliated hospital during a 16-month. Septic shock was defined as fluid-unresponsive hypotension requiring vasopressor to maintain a mean arterial pressure of 65 mmHg or greater, and serum lactate level ≥ 2 mmol/L. Overt DIC was defined as an International Society on Thrombosis and Hemostasis (ISTH score ≥ 5 points. The primary endpoint was 28-day mortality. Results Of 391 patients with septic shock, 290 were included in the present study. The mean age was 65.6 years, the 28-day mortality rate was 26.9%, and the prevalence of overt DIC was 17.6% (n = 51 according to the ISTH score. The median DIC score was higher in non-survivors than in survivors (5.0 vs. 2.0, p = 0.001. Significant higher risk of mortality was observed in overt DIC patients compared to those without (28.2% vs. 13.7%, p = 0.005. Multivariable logistic regression analysis identified DIC to be independently associated with 28-day mortality (odds ratio, 2.689 [95% confidence interval, 1.390-5.201]. Conclusions Using the ISTH criteria of DIC, overt DIC in septic shock was found to be common among patients admitting to the ED and to be associated with higher mortality when it is accompanied with septic shock. Efforts are required to identify presence of overt DIC during the initial treatment of septic shock in patients presenting the the ED.

  12. Mesoscale modelling of shock initiation in HMX-based explosives

    Energy Technology Data Exchange (ETDEWEB)

    Swift, D. C. (Damian C.); Mulford, R. N. R. (Robert N. R.); Winter, R. E. (Ron E.); Taylor, P. (Peter); Salisbury, D. A. (Darren A.); Harris, E. J. (Ernie J.)

    2002-01-01

    Motivation: predictive capability Want to predict initiation, detonics and performance given: {sm_bullet} Variations in composition {sm_bullet} Variations in morphology {sm_bullet}Different loading conditions Previous work on PBX and ANFO: need physically-based model rather than just mechanical calibrations

  13. Bursts and shocks in a continuum shell model

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Bohr, Tomas; Jensen, M.H.

    1998-01-01

    We study a burst event, i.e., the evolution of an initial condition having support only in a finite interval of k-space, in the continuum shell model due to Parisi. We show that the continuum equation without forcing or dissipation can be explicitly written in characteristic form and that the right...

  14. Modeling Blood Filtration in the Treatment of Septic Shock

    Science.gov (United States)

    Foster, Glenn; Hubler, Alfred

    2007-03-01

    Sepsis, the overreaction of the inflammation and coagulation responses to infection, is the leading cause of death in non-coronary intensive care unit patients in the US. Anti-mediator drugs have been generally ineffective, but by considering the network of cytokine interactions, we illustrate how filtering the cytokines in the blood leads to a reduced response. We further illustrate by applying an appropriate filter to existing immune response models as well as discuss both practical and optimal filter parameters.

  15. Business Cycle Models with Embodied Technological Change and Poisson Shocks

    OpenAIRE

    Schlegel, Christoph

    2004-01-01

    The first part analyzes an Endogenous Business Cycle model with embodied technological change. Households take an optimal decision about their spending for consumption and financing of R&D. The probability of a technology invention occurring is an increasing function of aggregate R&D expenditure in the whole economy. New technologies bring higher productivity, but rather than applying to the whole capital stock, they require a new vintage of capital, which first has to be accu...

  16. Determination of Parameters of Steinberg-Guinan Constitutive Model with Shock Wave Experiments

    Science.gov (United States)

    Peng, Jianxiang; Hu, Changming; Li, Yinglei; Zhang, Lin; Jing, Fuqian

    Steinberg-Guinan constitutive model is widely used in impact engineering simulations. Shock wave profile measurements of Al, Cu, and W under shock pressures ranging from 4 GPa to 200 GPa were analyzed, and shear modulus G and yield strength Y of these materials were obtained by using the high-pressure sonic velocities and rate independent Lagrange analysis results. Then values of derivatives of G and Y with respect to pressure or temperature at the reference state of these three metals were determined. By analyzing the pressure and temperature dependence of shear modulus and yield strength, we conclude that the relations of Steinberg-Guinan constitutive model, Y/G=constant, are approximately correct on Hugoniot state for these materials. So this is a probable approach to solve the difficulty of measurement of Y under high-pressure and high-temperature directly.

  17. Melting under shock compression

    International Nuclear Information System (INIS)

    Bennett, B.I.

    1980-10-01

    A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

  18. Recent results of full-spatial scale modeling of fast ignition and shock ignition

    Science.gov (United States)

    Tonge, J.; May, J.; Mori, W. B.; Fiuza, F.; Marti, M.; Fonseca, R. A.; Davies, J. R.; Silva, L. O.

    2010-11-01

    We show recent results of full-spatial scale modeling of fast ignition and shock ignition, from both full-PIC and the recently developed hybrid-PIC capability of OSIRIS 2.0. Our results show full-scale modeling of fast ignition over full density and time scales, where laser absorption, electron beam divergence, and energy deposition in the compressed core will be addressed in a self-consistent manner. Full-PIC and hybrid-PIC simulations of isolated targets will be presented, illustrating the importance of this type of modeling in order to accurately infer the beam divergence and transport properties. We will also demonstrate the possibility of performing full-scale simulations of shock ignition with the new hybrid-PIC capability, using compressed target profiles from hydrodynamic simulations, and studying the self-consistent laser absorption, electron transport, and energy deposition that can lead to the generation of the shock required for ignition. Work supported by DOE under DE-FC02-04-ER54789 and DE-FG52-09NA29552, and NSF under NSF-Phy-0904039, FCT (Portugal), and the HiPER project. Simulations performed on Hoffman at UCLA, Thresher at SDSC, and Intrepid at ANL supported by Incite grant FastIgnitionPIC.

  19. The Figure 8 Model of International Relations

    National Research Council Canada - National Science Library

    Sibayan, Jerome T

    2008-01-01

    .... The Figure 8 Model is presented first in a Cartesian format and then in geometrical form. This model is an intuitive idea based on a particular reading of history rather than a new international relations theory...

  20. On the Magnitude and Orientation of Stress during Shock Metamorphism: Understanding Peak Ring Formation by Combining Observations and Models.

    Science.gov (United States)

    Rae, A.; Poelchau, M.; Collins, G. S.; Timms, N.; Cavosie, A. J.; Lofi, J.; Salge, T.; Riller, U. P.; Ferrière, L.; Grieve, R. A. F.; Osinski, G.; Morgan, J. V.; Expedition 364 Science Party, I. I.

    2017-12-01

    . Our results quantitatively describe the deviatoric stress conditions of rocks in shock, which are consistent with observations of shock deformation. Our integrated analysis provides further support for the dynamic collapse model of peak-ring formation, and places dynamic constraints on the conditions of peak-ring formation.

  1. Global Effects of Transmitted Shock Wave Propagation Through the Earth's Inner Magnetosphere: First Results from 3-D Hybrid Kinetic Modeling

    Science.gov (United States)

    Lipatov, A. S.; Sibeck, D. G.

    2016-01-01

    We use a new hybrid kinetic model to simulate the response of ring current, outer radiation belt, and plasmaspheric particle populations to impulsive interplanetary shocks. Since particle distributions attending the interplanetary shock waves and in the ring current and radiation belts are non-Maxwellian, waveparticle interactions play a crucial role in energy transport within the inner magnetosphere. Finite gyroradius effects become important in mass loading the shock waves with the background plasma in the presence of higher energy ring current and radiation belt ions and electrons. Initial results show that shocks cause strong deformations in the global structure of the ring current, radiation belt, and plasmasphere. The ion velocity distribution functions at the shock front, in the ring current, and in the radiation belt help us determine energy transport through the Earth's inner magnetosphere.

  2. Ion heating and energy partition at the heliospheric termination shock: hybrid simulations and analytical model

    Energy Technology Data Exchange (ETDEWEB)

    Gary, S Peter [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Wu, Pin [BOSTON UNIV.; Schwadron, N A [BOSTON UNIV.; Lee, M [UNIV OF NEW HAMPSHIRE

    2009-01-01

    The Los Alamos hybrid simulation code is used to examine heating and the partition of dissipation energy at the perpendicular heliospheric termination shock in the presence of pickup ions. The simulations are one-dimensional in space but three-dimensional in field and velocity components, and are carried out for a range of values of pickup ion relative density. Results from the simulations show that because the solar wind ions are relatively cold upstream, the temperature of these ions is raised by a relatively larger factor than the temperature of the pickup ions. An analytic model for energy partition is developed on the basis of the Rankine-Hugoniot relations and a polytropic energy equation. The polytropic index {gamma} used in the Rankine-Hugoniot relations is varied to improve agreement between the model and the simulations concerning the fraction of downstream heating in the pickup ions as well as the compression ratio at the shock. When the pickup ion density is less than 20%, the polytropic index is about 5/3, whereas for pickup ion densities greater than 20%, the polytropic index tends toward 2.2, suggesting a fundamental change in the character of the shock, as seen in the simulations, when the pickup ion density is large. The model and the simulations both indicate for the upstream parameters chosen for Voyager 2 conditions that the pickup ion density is about 25% and the pickup ions gain the larger share (approximately 90%) of the downstream thermal pressure, consistent with Voyager 2 observations near the shock.

  3. Modeling Hot-Spot Contributions in Shocked High Explosives at the Mesoscale

    Energy Technology Data Exchange (ETDEWEB)

    Harrier, Danielle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-12

    When looking at performance of high explosives, the defects within the explosive become very important. Plastic bonded explosives, or PBXs, contain voids of air and bonder between the particles of explosive material that aid in the ignition of the explosive. These voids collapse in high pressure shock conditions, which leads to the formation of hot spots. Hot spots are localized high temperature and high pressure regions that cause significant changes in the way the explosive material detonates. Previously hot spots have been overlooked with modeling, but now scientists are realizing their importance and new modeling systems that can accurately model hot spots are underway.

  4. Modeling of skin cooling, blood flow, and optical properties in wounds created by electrical shock

    Science.gov (United States)

    Nguyen, Thu T. A.; Shupp, Jeffrey W.; Moffatt, Lauren T.; Jordan, Marion H.; Jeng, James C.; Ramella-Roman, Jessica C.

    2012-02-01

    High voltage electrical injuries may lead to irreversible tissue damage or even death. Research on tissue injury following high voltage shock is needed and may yield stage-appropriate therapy to reduce amputation rate. One of the mechanisms by which electricity damages tissue is through Joule heating, with subsequent protein denaturation. Previous studies have shown that blood flow had a significant effect on the cooling rate of heated subcutaneous tissue. To assess the thermal damage in tissue, this study focused on monitoring changes of temperature and optical properties of skin next to high voltage wounds. The burns were created between left fore limb and right hind limb extremities of adult male Sprague-Dawley rats by a 1000VDC delivery shock system. A thermal camera was utilized to record temperature variation during the exposure. The experimental results were then validated using a thermal-electric finite element model (FEM).

  5. Optimal Design and Model Validation for Combustion Experiments in a Shock Tube

    KAUST Repository

    Long, Quan

    2014-01-06

    We develop a Bayesian framework for the optimal experimental design of the shock tube experiments which are being carried out at the KAUST Clean Combustion Center. The unknown parameters are the pre-exponential parameters and the activation energies in the reaction rate functions. The control parameters are the initial hydrogen concentration and the temperature. First, we build a polynomial based surrogate model for the observable related to the reactions in the shock tube. Second, we use a novel MAP based approach to estimate the expected information gain in the proposed experiments and select the best experimental set-ups corresponding to the optimal expected information gains. Third, we use the synthetic data to carry out virtual validation of our methodology.

  6. Explosively Generated Plasmas: Measurement and Models of Shock Generation and Material Interactions

    Science.gov (United States)

    Emery, Samuel; Elert, Mark; Giannuzzi, Paul; Le, Ryan; McCarthy, Daniel; Schweigert, Igor

    2017-06-01

    Explosively generated plasmas (EGPs) are created by the focusing of a shock produced from an explosive driver via a conical waveguide. In the waveguide, the gases from the explosive along with the trapped air are accelerated and compressed (via Mach stemming) to such extent that plasma is produced. These EGPs have been measured in controlled experiments to achieve temperatures on the order of 1 eV and velocities as high as 25 km/s. We have conducted a combined modeling and measurement effort to increase the understanding for design purposes of the shock generation of EGPs and the interaction of EGP with explosive materials. Such efforts have led to improved measures of pressure and temperature, spatial structure of the plasma, and the decomposition/deflagration behavior of RDX upon exposure to an EGP. Funding provided by the Environmental Security Technology Certification Program (ESTCP) Munitions Response program area.

  7. Shock Initiation Experiments with Ignition and Growth Modeling on the HMX-Based Explosive LX-14

    Science.gov (United States)

    Vandersall, Kevin S.; Dehaven, Martin R.; Strickland, Shawn L.; Tarver, Craig M.; Springer, H. Keo; Cowan, Matt R.

    2017-06-01

    Shock initiation experiments on the HMX-based explosive LX-14 were performed to obtain in-situ pressure gauge data, characterize the run-distance-to-detonation behavior, and provide a basis for Ignition and Growth reactive flow modeling. A 101 mm diameter gas gun was utilized to initiate the explosive charges with manganin piezoresistive pressure gauge packages placed between sample disks pressed to different densities ( 1.57 or 1.83 g/cm3 that corresponds to 85 or 99% of theoretical maximum density (TMD), respectively). The shock sensitivity was found to increase with decreasing density as expected. Ignition and Growth model parameters were derived that yielded reasonable agreement with the experimental data at both initial densities. The shock sensitivity at the tested densities will be compared to prior work published on other HMX-based formulations. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work was funded in part by the Joint DoD-DOE Munitions Program.

  8. Cardiopulmonary Arrest and Resuscitation in Severe Sepsis and Septic Shock: A Research Model.

    Science.gov (United States)

    Chalkias, Athanasios; Spyropoulos, Vaios; Koutsovasilis, Anastasios; Papalois, Apostolos; Kouskouni, Evaggelia; Xanthos, Theodoros

    2015-03-01

    Cardiopulmonary resuscitation in patients with severe sepsis and septic shock is challenging and usually unsuccessful. The aim of the present study is to describe our swine model of cardiac arrest and resuscitation in severe sepsis and septic shock. In this prospective randomized animal study, 10 healthy female Landrace-Large White pigs with an average weight of 20 ± 1 kg (aged 19 - 21 weeks) were the study subjects. Septicemia was induced by an intravenous infusion of a bolus of 20-mL bacterial suspension in 2 min, followed by a continuous infusion during the rest of the experiment. After septic shock was confirmed, the animals were left untreated until cardiac arrest occurred. All animals developed pulseless electrical activity between the fifth and sixth hours of septicemia, whereas five (50%) of 10 animals were successfully resuscitated. Coronary perfusion pressure was statistically significantly different between surviving and nonsurviving animals. We found a statistically significant correlation between mean arterial pressure and unsuccessful resuscitation (P = 0.046), whereas there was no difference in end-tidal carbon dioxide (23.05 ± 1.73 vs. 23.56 ± 1.70; P = 0.735) between animals with return of spontaneous circulation and nonsurviving animals. During the 45-min postresuscitation monitoring, we noted a significant decrease in hemodynamic parameters, although oxygenation indices and lactate clearance were constantly increased (P = 0.001). This successful basic swine model was for the first time developed and may prove extremely useful in future studies on the periarrest period in severe sepsis and septic shock.

  9. The Effect of Nondeterministic Parameters on Shock-Associated Noise Prediction Modeling

    Science.gov (United States)

    Dahl, Milo D.; Khavaran, Abbas

    2010-01-01

    Engineering applications for aircraft noise prediction contain models for physical phenomenon that enable solutions to be computed quickly. These models contain parameters that have an uncertainty not accounted for in the solution. To include uncertainty in the solution, nondeterministic computational methods are applied. Using prediction models for supersonic jet broadband shock-associated noise, fixed model parameters are replaced by probability distributions to illustrate one of these methods. The results show the impact of using nondeterministic parameters both on estimating the model output uncertainty and on the model spectral level prediction. In addition, a global sensitivity analysis is used to determine the influence of the model parameters on the output, and to identify the parameters with the least influence on model output.

  10. Shock Waves

    CERN Document Server

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  11. The physiology of blood loss and shock: New insights from a human laboratory model of hemorrhage.

    Science.gov (United States)

    Schiller, Alicia M; Howard, Jeffrey T; Convertino, Victor A

    2017-04-01

    The ability to quickly diagnose hemorrhagic shock is critical for favorable patient outcomes. Therefore, it is important to understand the time course and involvement of the various physiological mechanisms that are active during volume loss and that have the ability to stave off hemodynamic collapse. This review provides new insights about the physiology that underlies blood loss and shock in humans through the development of a simulated model of hemorrhage using lower body negative pressure. In this review, we present controlled experimental results through utilization of the lower body negative pressure human hemorrhage model that provide novel insights on the integration of physiological mechanisms critical to the compensation for volume loss. We provide data obtained from more than 250 human experiments to classify human subjects into two distinct groups: those who have a high tolerance and can compensate well for reduced central blood volume (e.g. hemorrhage) and those with low tolerance with poor capacity to compensate.We include the conceptual introduction of arterial pressure and cerebral blood flow oscillations, reflex-mediated autonomic and neuroendocrine responses, and respiration that function to protect adequate tissue oxygenation through adjustments in cardiac output and peripheral vascular resistance. Finally, unique time course data are presented that describe mechanistic events associated with the rapid onset of hemodynamic failure (i.e. decompensatory shock). Impact Statement Hemorrhage is the leading cause of death in both civilian and military trauma. The work submitted in this review is important because it advances the understanding of mechanisms that contribute to the total integrated physiological compensations for inadequate tissue oxygenation (i.e. shock) that arise from hemorrhage. Unlike an animal model, we introduce the utilization of lower body negative pressure as a noninvasive model that allows for the study of progressive

  12. Analysis of a Shock-Associated Noise Prediction Model Using Measured Jet Far-Field Noise Data

    Science.gov (United States)

    Dahl, Milo D.; Sharpe, Jacob A.

    2014-01-01

    A code for predicting supersonic jet broadband shock-associated noise was assessed using a database containing noise measurements of a jet issuing from a convergent nozzle. The jet was operated at 24 conditions covering six fully expanded Mach numbers with four total temperature ratios. To enable comparisons of the predicted shock-associated noise component spectra with data, the measured total jet noise spectra were separated into mixing noise and shock-associated noise component spectra. Comparisons between predicted and measured shock-associated noise component spectra were used to identify deficiencies in the prediction model. Proposed revisions to the model, based on a study of the overall sound pressure levels for the shock-associated noise component of the measured data, a sensitivity analysis of the model parameters with emphasis on the definition of the convection velocity parameter, and a least-squares fit of the predicted to the measured shock-associated noise component spectra, resulted in a new definition for the source strength spectrum in the model. An error analysis showed that the average error in the predicted spectra was reduced by as much as 3.5 dB for the revised model relative to the average error for the original model.

  13. Modeling of the plasma generated in a rarefied hypersonic shock layer

    International Nuclear Information System (INIS)

    Farbar, Erin D.; Boyd, Iain D.

    2010-01-01

    In this study, a rigorous numerical model is developed to simulate the plasma generated in a rarefied, hypersonic shock layer. The model uses the direct simulation Monte Carlo (DSMC) method to treat the particle collisions and the particle-in-cell (PIC) method to simulate the plasma dynamics in a self-consistent manner. The model is applied to compute the flow along the stagnation streamline in front of a blunt body reentering the Earth's atmosphere at very high velocity. Results from the rigorous DSMC-PIC model are compared directly to the standard DSMC modeling approach that uses the ambipolar diffusion approximation to simulate the plasma dynamics. It is demonstrated that the self-consistent computation of the plasma dynamics using the rigorous DSMC-PIC model captures many physical phenomena not accurately predicted by the standard modeling approach. These computations represent the first assessment of the validity of the ambipolar diffusion approximation when predicting the rarefied plasma generated in a hypersonic shock layer.

  14. Vulnerability to shocks in the global seafood trade network

    Science.gov (United States)

    Gephart, Jessica A.; Rovenskaya, Elena; Dieckmann, Ulf; Pace, Michael L.; Brännström, Åke

    2016-03-01

    Trade can allow countries to overcome local or regional losses (shocks) to their food supply, but reliance on international food trade also exposes countries to risks from external perturbations. Countries that are nutritionally or economically dependent on international trade of a commodity may be adversely affected by such shocks. While exposure to shocks has been studied in financial markets, communication networks, and some infrastructure systems, it has received less attention in food-trade networks. Here, we develop a forward shock-propagation model to quantify how trade flows are redistributed under a range of shock scenarios and assess the food-security outcomes by comparing changes in national fish supplies to indices of each country’s nutritional fish dependency. Shock propagation and distribution among regions are modeled on a network of historical bilateral seafood trade data from UN Comtrade using 205 reporting territories grouped into 18 regions. In our model exposure to shocks increases with total imports and the number of import partners. We find that Central and West Africa are the most vulnerable to shocks, with their vulnerability increasing when a willingness-to-pay proxy is included. These findings suggest that countries can reduce their overall vulnerability to shocks by reducing reliance on imports and diversifying food sources. As international seafood trade grows, identifying these types of potential risks and vulnerabilities is important to build a more resilient food system.

  15. The Initial Stage of the International Sojourn: Excitement or Culture Shock?

    Science.gov (United States)

    Brown, Lorraine; Holloway, Immy

    2008-01-01

    This paper presents findings from an ethnographic study of the adjustment journey of international postgraduate students at a university in the South of England, which involved interviews and participant observation over a 12-month academic year. It was discovered that the initial stage of the sojourn was not characterised by feelings of…

  16. Shock and rarefaction waves in a hyperbolic model of incompressible materials

    Directory of Open Access Journals (Sweden)

    Tommaso Ruggeri

    2013-01-01

    Full Text Available The aim of the present paper is to investigate shock and rarefaction waves in a hyperbolic model of incompressible materials. To this aim, we use the so-called extended quasi-thermal-incompressible (EQTI model, recently proposed by Gouin & Ruggeri (H. Gouin, T. Ruggeri, Internat. J. Non-Linear Mech. 47 688–693 (2012. In particular, we use as constitutive equation a variant of the well-known Bousinnesq approximation in which the specific volume depends not only on the temperature but also on the pressure. The limit case of ideal incompressibility, namely when the thermal expansion coefficient and the compressibility factor vanish, is also considered.

  17. A numerical calculation of outward propagation of solar disturbances. [solar atmospheric model with shock wave propagation

    Science.gov (United States)

    Wu, S. T.

    1974-01-01

    The responses of the solar atmosphere due to an outward propagation shock are examined by employing the Lax-Wendroff method to solve the set of nonlinear partial differential equations in the model of the solar atmosphere. It is found that this theoretical model can be used to explain the solar phenomena of surge and spray. A criterion to discriminate the surge and spray is established and detailed information concerning the density, velocity, and temperature distribution with respect to the height and time is presented. The complete computer program is also included.

  18. Growth models with internal competition

    International Nuclear Information System (INIS)

    Ausloos, M.; Vandewalle, N.

    1996-01-01

    Combined statistical physics and computation modelling give new instruments for the study of non-equilibrium systems. We briefly review generalized Eden and Diffusion-Limited Aggregation models as applied to spreading phenomena. We indicate the occurrence of non-universal behaviors. (author)

  19. Confinement effects in shock/turbulent-boundary-layer interaction through wall-modeled LES

    Science.gov (United States)

    Bermejo-Moreno, Ivan; Campo, Laura; Larsson, Johan; Bodart, Julien; Helmer, David; Eaton, John

    2016-11-01

    Wall-modeled large-eddy simulations (WMLES) are used to investigate three-dimensional effects imposed by lateral confinement on the interaction of oblique shock waves impinging on turbulent boundary layers (TBLs) developed along the walls of a nearly-square duct. A constant Mach number, M = 2 . 05 , of the incoming air stream is considered, with a Reynolds number based on the incoming turbulent boundary layer momentum thickness Reθ 14 , 000 . The strength of the impinging shock is varied by increasing the height of a compression wedge located at a constant streamwise location that spans the top wall of the duct at a 20° angle. Simulation results are first validated with particle image velocimetry (PIV) experimental data obtained at several vertical planes. Emphasis is placed on the study of the instantaneous and time-averaged structure of the flow for the stronger-interaction case, which shows mean flow reversal. By performing additional spanwise-periodic simulations, it is found that the structure and location of the shock system and separation bubble are significantly modified by the lateral confinement. Low-frequency unsteadiness and downstream evolution of corner flows are also investigated. Financial support from the United States Department of Energy under the PSAAP program is gratefully acknowledged.

  20. A History of constitutive modeling via molecular dynamics: Shock waves in fluids and gases

    Directory of Open Access Journals (Sweden)

    Holian B.L.

    2011-01-01

    Full Text Available From its inception in the mid-Fifties, the method of molecular-dynamics (MD computer simulations has been used to probe the foundations of statistical mechanics, first for equilibrium equation-of-state averages, and then for transport properties from equilibrium fluctuations. Traditional statistical mechanical theoreticians were shocked to see that this new-fangled computational physics approach was feasible, even with incredibly tiny samples (on the order of a hundred atoms. When direct measurement of transport coefficients by non-equilibrium molecular dynamics (NEMD was proposed in the early Seventies, even greater resistance was encountered from the traditionalists – though evidence for convergence with the equilibrium fluctuation method gradually accumulated. In the late Seventies and early Eighties, shock-wave simulations by NEMD made it possible to test directly the principal continuum constitutive theory for fluids, namely, Navier-Stokes viscous flow and Fourier’s Law of heat conduction. To everyone’s surprise – and the consternation of many – NEMD, once again, demonstrated that continuum theory applies at embarrassingly small (atomistic time and length scales. We pursue this early line of work into the modern era, showing how NEMD shock-wave simulations can still provide surprising insights and improvements upon our understanding of constitutive modeling.

  1. International Symposia on Scale Modeling

    CERN Document Server

    Ito, Akihiko; Nakamura, Yuji; Kuwana, Kazunori

    2015-01-01

    This volume thoroughly covers scale modeling and serves as the definitive source of information on scale modeling as a powerful simplifying and clarifying tool used by scientists and engineers across many disciplines. The book elucidates techniques used when it would be too expensive, or too difficult, to test a system of interest in the field. Topics addressed in the current edition include scale modeling to study weather systems, diffusion of pollution in air or water, chemical process in 3-D turbulent flow, multiphase combustion, flame propagation, biological systems, behavior of materials at nano- and micro-scales, and many more. This is an ideal book for students, both graduate and undergraduate, as well as engineers and scientists interested in the latest developments in scale modeling. This book also: Enables readers to evaluate essential and salient aspects of profoundly complex systems, mechanisms, and phenomena at scale Offers engineers and designers a new point of view, liberating creative and inno...

  2. On the effects of world stock market and oil price shocks on food prices: An empirical investigation based on TVP-VAR models with stochastic volatility

    International Nuclear Information System (INIS)

    Jebabli, Ikram; Arouri, Mohamed; Teulon, Frédéric

    2014-01-01

    Transmission of price shocks from one market to another one has long been investigated in the economic literature. However, studies have namely dealt with the relationship between financial and energy markets. With the recent changes in market conditions, investors, policy-makers and interest groups are giving special attention to food market. This paper aims at analyzing shock transmission between international food, energy and financial markets and to provide some insights into the volatility behavior during the past years and discuss its implications for portfolio management. To do this, we present a new time varying parameter VAR (TVP-VAR) model with stochastic volatility approach which provides extreme flexibility with a parsimonious specification. We resort also to a generalized vector autoregressive framework in which forecast-error variance decompositions are invariant to the variable ordering for the assessment of total and directional volatility spillovers. Our main findings suggest that volatility spillovers increase considerably during crisis and, namely after mid-2008, when stock markets become net transmitter of volatility shocks while crude oil becomes a net receiver. Shocks to crude oil or MSCI markets have immediate and short-term impacts on food markets which are emphasized during the financial crisis period. Moreover, we show that augmenting a diversified portfolio of food commodities with crude oil or stocks significantly increases its risk-adjusted performance. - Highlights: • We study shock transmission between food, energy and financial markets. • We use a new time-varying parameter VAR model with stochastic volatility. • There is volatility spillover from oil and stock markets to food. • Volatility spillovers increase considerably during crisis, namely after mid-2008. • Augmenting a portfolio of foods with oil or stocks increases its performance

  3. International Universities: Misunderstandings and Emerging Models?

    Science.gov (United States)

    Knight, Jane

    2015-01-01

    Internationalization has transformed higher education institutions and systems but there is much confusion as to what an international, binational, transnational, cosmopolitan, multinational, or global university actually means. There is no standardized model for an international university, nor should there be, but a deeper understanding of…

  4. Modeling Shocks Detected by Voyager 1 in the Local Interstellar Medium

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T. K.; Pogorelov, N. V. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Burlaga, L. F. [NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 (United States)

    2017-07-10

    The magnetometer (MAG) on Voyager 1 ( V1 ) has been sampling the interstellar magnetic field (ISMF) since 2012 August. The V1 MAG observations have shown draped ISMF in the very local interstellar medium disturbed occasionally by significant enhancements in magnetic field strength. Using a three-dimensional, data-driven, multi-fluid model, we investigated these magnetic field enhancements beyond the heliopause that are supposedly associated with solar transients. To introduce time-dependent effects at the inner boundary at 1 au, we used daily averages of the solar wind parameters from the OMNI data set. The model ISMF strength, direction, and proton number density are compared with V1 data beyond the heliopause. The model reproduced the large-scale fluctuations between 2012.652 and 2016.652, including major events around 2012.9 and 2014.6. The model also predicts shocks arriving at V1 around 2017.395 and 2019.502. Another model driven by OMNI data with interplanetary coronal mass ejections (ICMEs) removed at the inner boundary suggests that ICMEs may play a significant role in the propagation of shocks into the interstellar medium.

  5. Do structural oil-market shocks affect stock prices?

    International Nuclear Information System (INIS)

    Apergis, Nicholas; Miller, Stephen M.

    2009-01-01

    This paper investigates how explicit structural shocks that characterize the endogenous character of oil price changes affect stock-market returns in a sample of eight countries - Australia, Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States. For each country, the analysis proceeds in two steps. First, modifying the procedure of Kilian [Not All Oil Price Shocks are Alike: Disentangling Demand and Supply Shocks in the Crude Oil Market. American Economic Review.], we employ a vector error-correction or vector autoregressive model to decompose oil-price changes into three components: oil-supply shocks, global aggregate-demand shocks, and global oil-demand shocks. The last component relates to specific idiosyncratic features of the oil market, such as changes in the precautionary demand concerning the uncertainty about the availability of future oil supplies. Second, recovering the oil-supply shocks, global aggregate-demand shocks, and global oil-demand shocks from the first analysis, we then employ a vector autoregressive model to determine the effects of these structural shocks on the stock market returns in our sample of eight countries. We find that international stock market returns do not respond in a large way to oil market shocks. That is, the significant effects that exist prove small in magnitude. (author)

  6. Combustion modeling in internal combustion engines

    Science.gov (United States)

    Zeleznik, F. J.

    1976-01-01

    The fundamental assumptions of the Blizard and Keck combustion model for internal combustion engines are examined and a generalization of that model is derived. The most significant feature of the model is that it permits the occurrence of unburned hydrocarbons in the thermodynamic-kinetic modeling of exhaust gases. The general formulas are evaluated in two specific cases that are likely to be significant in the applications of the model.

  7. A Novel Fluoroscopy-free, Resuscitative Endovascular Aortic Balloon Occlusion System in a Model of Hemorrhagic Shock

    Science.gov (United States)

    2013-07-01

    A novel fluoroscopy -free, resuscitative endovascular aortic balloon occlusion system in a model of hemorrhagic shock Daniel J. Scott, MD, Jonathan L...hemorrhagic shock. However, emergent use of REBOA is limited by existing technology, which requires large sheath arterial access and fluoroscopy - guided...balloon positioning. The objectives of this study were to describe a new, fluoroscopy -free REBOA system and to compare its efficacy to existing technology

  8. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, SShao-sheng R.; Allen, Christopher S.

    2009-01-01

    Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was

  9. Diaplectic quartz glass and SiO2 melt experimentally generated at only 5 GPa shock pressure in porous sandstone: Laboratory observations and meso-scale numerical modeling

    Science.gov (United States)

    Kowitz, A.; Güldemeister, N.; Reimold, W. U.; Schmitt, R. T.; Wünnemann, K.

    2013-12-01

    A combination of shock recovery experiments and numerical modeling of shock deformation in the low pressure range from 2.5 to 17.5 GPa in dry, porous Seeberger sandstone provides new, significant insights with respect to the heterogeneous nature of shock distribution in such important, upper crustal material, for which to date no pressure-calibrated scheme for shock metamorphism exists. We found that pores are already completely closed at 2.5 GPa shock pressure. Whole quartz grains or parts of them are transformed to diaplectic quartz glass and/or SiO2 melt starting already at 5 GPa, whereas these effects are not observed below shock pressures of 30-35 and ˜45 GPa, respectively, in shock experiments with quartz single crystals. The appearance of diaplectic glass or melt is not restricted to the zone directly below the impacted surface but is related to the occurrence of pores in a much broader zone. The combined amount of these phases increases distinctly with increasing shock pressure from 0.03 vol.% at 5 GPa to ˜80 vol.% at 17.5 GPa. In accordance with a previous shock classification for silica phases in naturally shocked Coconino sandstone from Meteor Crater that was based on varied slopes of the Coconino sandstone Hugoniot curve, our observations allow us to construct a shock pressure classification for porous sandstone consistent with shock stages 1b-4 of the progressive shock metamorphism classification of Kieffer (1971).

  10. A mesoscopic reaction rate model for shock initiation of multi-component PBX explosives.

    Science.gov (United States)

    Liu, Y R; Duan, Z P; Zhang, Z Y; Ou, Z C; Huang, F L

    2016-11-05

    The primary goal of this research is to develop a three-term mesoscopic reaction rate model that consists of a hot-spot ignition, a low-pressure slow burning and a high-pressure fast reaction terms for shock initiation of multi-component Plastic Bonded Explosives (PBX). Thereinto, based on the DZK hot-spot model for a single-component PBX explosive, the hot-spot ignition term as well as its reaction rate is obtained through a "mixing rule" of the explosive components; new expressions for both the low-pressure slow burning term and the high-pressure fast reaction term are also obtained by establishing the relationships between the reaction rate of the multi-component PBX explosive and that of its explosive components, based on the low-pressure slow burning term and the high-pressure fast reaction term of a mesoscopic reaction rate model. Furthermore, for verification, the new reaction rate model is incorporated into the DYNA2D code to simulate numerically the shock initiation process of the PBXC03 and the PBXC10 multi-component PBX explosives, and the numerical results of the pressure histories at different Lagrange locations in explosive are found to be in good agreements with previous experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Time-dependent simulation of oblique MHD cosmic-ray shocks using the two-fluid model

    Science.gov (United States)

    Frank, Adam; Jones, T. W.; Ryu, Dongsu

    1995-01-01

    Using a new, second-order accurate numerical method we present dynamical simulations of oblique MHD cosmic-ray (CR)-modified plane shock evolution. Most of the calculations are done with a two-fluid model for diffusive shock acceleration, but we provide also comparisons between a typical shock computed that way against calculations carried out using the more complete, momentum-dependent, diffusion-advection equation. We also illustrate a test showing that these simulations evolve to dynamical equilibria consistent with previously published steady state analytic calculations for such shocks. In order to improve understanding of the dynamical role of magnetic fields in shocks modified by CR pressure we have explored for time asymptotic states the parameter space of upstream fast mode Mach number, M(sub f), and plasma beta. We compile the results into maps of dynamical steady state CR acceleration efficiency, epsilon(sub c). We have run simulations using constant, and nonisotropic, obliquity (and hence spatially) dependent forms of the diffusion coefficient kappa. Comparison of the results shows that while the final steady states achieved are the same in each case, the history of CR-MHD shocks can be strongly modified by variations in kappa and, therefore, in the acceleration timescale. Also, the coupling of CR and MHD in low beta, oblique shocks substantially influences the transient density spike that forms in strongly CR-modified shocks. We find that inside the density spike a MHD slow mode wave can be generated that eventually steepens into a shock. A strong layer develops within the density spike, driven by MHD stresses. We conjecture that currents in the shear layer could, in nonplanar flows, results in enhanced particle accretion through drift acceleration.

  12. Phenylmethimazole inhibits production of proinflammatory mediators and is protective in an experimental model of endotoxic shock*.

    Science.gov (United States)

    Benavides, Uruguaysito; Gonzalez-Murguiondo, Mariana; Harii, Norikazu; Lewis, Christopher J; Schwartz, Anthony L; Giuliani, Cesidio; Napolitano, Giorgio; Dagia, Nilesh M; Malgor, Ramiro; McCall, Kelly D; Kohn, Leonard D

    2012-03-01

    One form of sepsis, or endotoxic shock, is a hyperactivated systemic response caused by excessive expression of proinflammatory mediators, which results from Gram-negative bacterial lipopolysaccharide-stimulated Toll-like receptor-4 signaling. This lipopolysaccharide signaling is known to consist of a MyD88-dependent nuclear factor-κB-mediated pathway that results in production of proinflammatory mediators (tumor necrosis factor-α, interleukin-6, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, inducible nitric oxide synthase, cyclooxygenase-2) and a MyD88-independent interferon regulatory factor-mediated pathway that regulates production of Type 1 interferon-inducible proteins (interferon γ-induced protein-10, monocyte chemotactic protein-1). In prior studies, phenylmethimazole markedly decreased virally induced Toll-like receptor-3 expression and signaling and significantly suppressed murine colitis in an experimental model wherein lipopolysaccharide is known to play an important role. In this study, we probed the hypothesis that phenylmethimazole inhibits lipopolysaccharide-mediated Toll-like receptor-4 signaling and is efficacious in attenuating inflammatory changes and improving survival in an in vivo murine model of endotoxic shock. Experimental animal model. University laboratory. Male C57BL/6J mice weighing 18-22 g. Phenylmethimazole (1 mg/kg) was administered intraperitoneally to mice before a lethal lipopolysaccharide challenge (25 mg/kg). RAW264.7 mouse macrophage cells were pretreated with phenylmethimazole followed by lipopolysaccharide stimulation. : Macroscopic observations revealed that phenylmethimazole was significantly protective in controlling clinical manifestations of endotoxic shock and death under conditions wherein flunixin of meglumine and prednisolone were marginally effective. A combination of enzyme-linked immunosorbent assay, Northern blot, reverse transcriptase-polymerase chain reaction, immunohistochemistry

  13. Analytical model of internally coupled ears

    DEFF Research Database (Denmark)

    Vossen, Christine; Christensen-Dalsgaard, Jakob; Leo van Hemmen, J

    2010-01-01

    differences in the tympanic membrane vibrations. Both cues show strong directionality. The work presented herein sets out the derivation of a three dimensional analytical model of internally coupled ears that allows for calculation of a complete vibration profile of the membranes. The analytical model...... additionally provides the opportunity to incorporate the effect of the asymmetrically attached columella, which leads to the activation of higher membrane vibration modes. Incorporating this effect, the analytical model can explain measurements taken from the tympanic membrane of a living lizard, for example......, data demonstrating an asymmetrical spatial pattern of membrane vibration. As the analytical calculations show, the internally coupled ears increase the directional response, appearing in large directional internal amplitude differences (iAD) and in large internal time differences (iTD). Numerical...

  14. Geometrical shock dynamics for magnetohydrodynamic fast shocks

    KAUST Repository

    Mostert, W.

    2016-12-12

    We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

  15. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Sozer, Emre; Moini-Yekta, Shayan

    2016-01-01

    NASA and Industry are performing vehicle studies of configurations with low sonic boom pressure signatures. The computational analyses of modern configuration designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty in the aft signatures with often greater boundary layer effects and nozzle jet pressures. Wind tunnel testing at significantly lower Reynolds numbers than in flight and without inlet and nozzle jet pressures make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel from Mach 1.6 to 2.0 will be used to assess the effects of shocks from components passing through nozzle jet plumes on the sonic boom pressure signature and provide datasets for comparison with CFD codes. A large number of high-fidelity numerical simulations of wind tunnel test models with a variety of shock generators that simulate horizontal tails and aft decks have been studied to provide suitable models for sonic boom pressure measurements using a minimally intrusive pressure rail in the wind tunnel. The computational results are presented and the evolution of candidate wind tunnel models is summarized and discussed in this paper.

  16. Detailed ADM-based Modeling of Shock Retreat and X-ray Emission of τ Sco

    Science.gov (United States)

    Fletcher, C. L.; Petit, V.; Cohen, D. H.; Townsend, R. H.; Wade, G. A.

    2018-01-01

    Leveraging the improvement of spectropolarimeters over the past few decades, surveys have found that about 10% of OB-type stars host strong (˜ kG) and mostly dipolar surface magnetic fields. One B-type star, τ Sco, has a more complex surface magnetic field than the general population of OB stars. Interestingly, its X-ray luminosity is an order of magnitude higher than predicted from analytical models of magnetized winds. Previous studies of τ Sco's magnetosphere have predicted that the region of closed field loops should be located close to the stellar surface. However, the lack of X-ray variability and the location of the shock-heated plasma measured from forbidden-to-intercombination X-ray line ratios suggest that the hot plasma, and hence the closed magnetic loops, extend considerably farther from the stellar surface, implying a significantly lower mass loss rate than initially assumed. We present an adaptation of the Analytic Dynamical Magnetosphere model, describing the magnetic confinement of the stellar wind, for an arbitrary field loop configuration. This model is used to predict the shock-heated plasma temperatures for individual field loops, which are then compared to high resolution grating spectra from the Chandra X-ray Observatory. This comparison shows that larger closed magnetic loops are needed.

  17. Shock Melting of Permafrost on Mars: Water Ice Multiphase Equation of State for Numerical Modeling and Its Testing

    Science.gov (United States)

    Ivanov, B. A.

    2005-01-01

    The presence of water/ice/brine in upper layers of Martian crust affects many processes of impact cratering. Modeling of these effects promises better understanding of Martian cratering records. We present here the new ANEOS-based multiphase equation of state for water/ice constructed for usage in hydrocodes and first numerical experiments on permafrost shock melting. Preliminary results show that due to multiple shock compression of ice inclusions in rocks the entropy jump in shocked ice is smaller than in pure ice for the same shock pressure. Hence previous estimates of ice melting during impact cratering on Mars should be re-evaluated. Additional information is included in the original extended abstract.

  18. BIOMOVS: an international model validation study

    International Nuclear Information System (INIS)

    Haegg, C.; Johansson, G.

    1988-01-01

    BIOMOVS (BIOspheric MOdel Validation Study) is an international study where models used for describing the distribution of radioactive and nonradioactive trace substances in terrestrial and aquatic environments are compared and tested. The main objectives of the study are to compare and test the accuracy of predictions between such models, explain differences in these predictions, recommend priorities for future research concerning the improvement of the accuracy of model predictions and act as a forum for the exchange of ideas, experience and information. (author)

  19. BIOMOVS: An international model validation study

    International Nuclear Information System (INIS)

    Haegg, C.; Johansson, G.

    1987-01-01

    BIOMOVS (BIOspheric MOdel Validation Study) is an international study where models used for describing the distribution of radioactive and nonradioactive trace substances in terrestrial and aquatic environments are compared and tested. The main objectives of the study are to compare and test the accuracy of predictions between such models, explain differences in these predictions, recommend priorities for future research concerning the improvement of the accuracy of model predictions and act as a forum for the exchange of ideas, experience and information. (orig.)

  20. Use of artificial intelligence to identify cardiovascular compromise in a model of hemorrhagic shock.

    Science.gov (United States)

    Glass, Todd F; Knapp, Jason; Amburn, Philip; Clay, Bruce A; Kabrisky, Matt; Rogers, Steven K; Garcia, Victor F

    2004-02-01

    To determine whether a prototype artificial intelligence system can identify volume of hemorrhage in a porcine model of controlled hemorrhagic shock. Prospective in vivo animal model of hemorrhagic shock. Research foundation animal surgical suite; computer laboratories of collaborating industry partner. Nineteen, juvenile, 25- to 35-kg, male and female swine. Anesthetized animals were instrumented for arterial and systemic venous pressure monitoring and blood sampling, and a splenectomy was performed. Following a 1-hr stabilization period, animals were hemorrhaged in aliquots to 10, 20, 30, 35, 40, 45, and 50% of total blood volume with a 10-min recovery between each aliquot. Data were downloaded directly from a commercial monitoring system into a proprietary PC-based software package for analysis. Arterial and venous blood gas values, glucose, and cardiac output were collected at specified intervals. Electrocardiogram, electroencephalogram, mixed venous oxygen saturation, temperature (core and blood), mean arterial pressure, pulmonary artery pressure, central venous pressure, pulse oximetry, and end-tidal CO(2) were continuously monitored and downloaded. Seventeen of 19 animals (89%) died as a direct result of hemorrhage. Stored data streams were analyzed by the prototype artificial intelligence system. For this project, the artificial intelligence system identified and compared three electrocardiographic features (R-R interval, QRS amplitude, and R-S interval) from each of nine unknown samples of the QRS complex. We found that the artificial intelligence system, trained on only three electrocardiographic features, identified hemorrhage volume with an average accuracy of 91% (95% confidence interval, 84-96%). These experiments demonstrate that an artificial intelligence system, based solely on the analysis of QRS amplitude, R-R interval, and R-S interval of an electrocardiogram, is able to accurately identify hemorrhage volume in a porcine model of lethal

  1. Method for detecting neutrinos from internal shocks in GRB fireballs with AMANDA

    CERN Document Server

    Stamatikos, M

    2004-01-01

    Neutrino-based astronomy provides a new window on the most energetic processes in the universe. The discovery of high-energy (E >or= 10 /sup 14/ eV) muonic neutrinos (v/sub mu /) from gamma-ray bursts (GRBs) would confirm hadronic acceleration in the relativistic GRB- wind, validate the phenomenology of the canonical fireball model and possibly reveal an acceleration mechanism for the highest energy cosmic rays (CRs). The Antarctic Muon and Neutrino Detector Array (AMANDA) is the world's largest operational neutrino telescope with a PeV muon effective area (averaged over zenith angle) ~ 50,000 m/sup 2 /. AMANDA uses the natural ice at the geographic South Pole as a Cherenkov medium and has been successfully calibrated on the signal of atmospheric neutrinos (v/sub atm/). Contrary to previous diffuse searches, we describe an analysis based upon confronting AMANDA observations of individual GRBs, adequately modeled by fireball phenomenology, with the predictions of the canonical fireball model. The expected neut...

  2. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet Flows with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Moini-Yekta, Shayan; Morr, Donald E.; Durston, Donald A.

    2016-01-01

    NASA and the U.S. aerospace industry are performing studies of supersonic aircraft concepts with low sonic boom pressure signatures. The computational analyses of modern aircraft designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty remains in the aft signatures due to boundary layer and nozzle exhaust jet effects. Wind tunnel testing without inlet and nozzle exhaust jet effects at lower Reynolds numbers than in-flight make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel is planned for February 2016 to address the nozzle jet effects on sonic boom. The experiment will provide pressure signatures of test articles that replicate waveforms from aircraft wings, tails, and aft fuselage (deck) components after passing through cold nozzle jet plumes. The data will provide a variety of nozzle plume and shock interactions for comparison with computational results. A large number of high-fidelity numerical simulations of a variety of shock generators were evaluated to define a reduced collection of suitable test models. The computational results of the candidate wind tunnel test models as they evolved are summarized, and pre-test computations of the final designs are provided.

  3. High temperature shock tube experiments and kinetic modeling study of diisopropyl ketone ignition and pyrolysis

    KAUST Repository

    Barari, Ghazal

    2017-03-10

    Diisopropyl ketone (DIPK) is a promising biofuel candidate, which is produced using endophytic fungal conversion. In this work, a high temperature detailed combustion kinetic model for DIPK was developed using the reaction class approach. DIPK ignition and pyrolysis experiments were performed using the UCF shock tube. The shock tube oxidation experiments were conducted between 1093K and 1630K for different reactant compositions, equivalence ratios (φ=0.5–2.0), and pressures (1–6atm). In addition, methane concentration time-histories were measured during 2% DIPK pyrolysis in argon using cw laser absorption near 3400nm at temperatures between 1300 and 1400K near 1atm. To the best of our knowledge, current ignition delay times (above 1050K) and methane time histories are the first such experiments performed in DIPK at high temperatures. Present data were used as validation targets for the new kinetic model and simulation results showed fair agreement compared to the experiments. The reaction rates corresponding to the main consumption pathways of DIPK were found to have high sensitivity in controlling the reactivity, so these were adjusted to attain better agreement between the simulation and experimental data. A correlation was developed based on the experimental data to predict the ignition delay times using the temperature, pressure, fuel concentration and oxygen concentration.

  4. The small heat shock proteins from Acidithiobacillus ferrooxidans: gene expression, phylogenetic analysis, and structural modeling

    Directory of Open Access Journals (Sweden)

    Ribeiro Daniela A

    2011-12-01

    Full Text Available Abstract Background Acidithiobacillus ferrooxidans is an acidophilic, chemolithoautotrophic bacterium that has been successfully used in metal bioleaching. In this study, an analysis of the A. ferrooxidans ATCC 23270 genome revealed the presence of three sHSP genes, Afe_1009, Afe_1437 and Afe_2172, that encode proteins from the HSP20 family, a class of intracellular multimers that is especially important in extremophile microorganisms. Results The expression of the sHSP genes was investigated in A. ferrooxidans cells submitted to a heat shock at 40°C for 15, 30 and 60 minutes. After 60 minutes, the gene on locus Afe_1437 was about 20-fold more highly expressed than the gene on locus Afe_2172. Bioinformatic and phylogenetic analyses showed that the sHSPs from A. ferrooxidans are possible non-paralogous proteins, and are regulated by the σ32 factor, a common transcription factor of heat shock proteins. Structural studies using homology molecular modeling indicated that the proteins encoded by Afe_1009 and Afe_1437 have a conserved α-crystallin domain and share similar structural features with the sHSP from Methanococcus jannaschii, suggesting that their biological assembly involves 24 molecules and resembles a hollow spherical shell. Conclusion We conclude that the sHSPs encoded by the Afe_1437 and Afe_1009 genes are more likely to act as molecular chaperones in the A. ferrooxidans heat shock response. In addition, the three sHSPs from A. ferrooxidans are not recent paralogs, and the Afe_1437 and Afe_1009 genes could be inherited horizontally by A. ferrooxidans.

  5. The endogenous grid method for discrete-continuous dynamic choice models with (or without) taste shocks

    DEFF Research Database (Denmark)

    Iskhakov, Fedor; Jørgensen, Thomas H.; Rust, John

    2017-01-01

    We present a fast and accurate computational method for solving and estimating a class of dynamic programming models with discrete and continuous choice variables. The solution method we develop for structural estimation extends the endogenous grid-point method (EGM) to discrete-continuous (DC...... taste shocks that are typically interpreted as “unobserved state variables” in structural econometric applications, or serve as “random noise” to smooth out kinks in the value functions in numerical applications. We present Monte Carlo experiments that demonstrate the reliability and efficiency......) problems. Discrete choices can lead to kinks in the value functions and discontinuities in the optimal policy rules, greatly complicating the solution of the model. We show how these problems are ameliorated in the presence of additive choice-specific independent and identically distributed extreme value...

  6. Intification and modelling of flight characteristics for self-build shock flyer type UAV

    Science.gov (United States)

    Rashid., Z. A.; Dardin, A. S. F. Syed.; Azid, A. A.; Ahmad, K. A.

    2018-02-01

    The development of an autonomous Unmanned Aerial Vehicle (UAV) requires a fundamentals studies of the UAV's flight characteristic. The aim of this study is to identify and model the flight characteristic of a conventional fixed-wing type UAV. Subsequence to this, the mode of flight of the UAV can be investigated. One technique to identify the characteristic of a UAV is a flight test where it required specific maneuvering to be executed while measuring the attitude sensor. In this study, a simple shock flyer type UAV was used as the aircraft. The result shows that the modeled flight characteristic has a significant relation with actual values but the fitting value is rather small. It is suggested that the future study is conducted with an improvement of the physical UAV, data filtering and better system identification methods.

  7. Experimental models of acute infection and Toll-like receptor driven septic shock.

    Science.gov (United States)

    Ferstl, Ruth; Spiller, Stephan; Fichte, Sylvia; Dreher, Stefan; Kirschning, Carsten J

    2009-01-01

    Mainly Gram-negative and Gram-positive bacterial infections, but also other infections such as with fungal or viral pathogens, can cause the life-threatening clinical condition of septic shock. Transgression of the host immune response from a local level limited to the pathogen's place of entry to the systemic level is recognised as a major mode of action leading to sepsis. This view has been established upon demonstration of the capacity of specific pathogen-associated molecular patterns (PAMPs) to elicit symptoms of septic shock upon systemic administration. Immune stimulatory PAMPs are agonists of soluble, cytoplasmic, as well as/or cell membrane-anchored and/or -spanning pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs). However, reflection of pathogen-host crosstalk triggering sepsis pathogenesis upon an infection by a host response to challenge with an isolated PAMP is incomplete. Therefore, an experimental model more reflective of pathogen-host interaction requires experimental host confrontation with a specific pathogen in its viable form resulting in a collective stimulation of a variety of specific PRRs. This chapter describes methods to analyse innate pathogen sensing by the host on both a cellular and systemic level.

  8. Reorganization of pathological control functions of memory-A neural model for tissue healing by shock waves

    Science.gov (United States)

    Wess, Othmar

    2005-04-01

    Since 1980 shock waves have proven effective in the field of extracorporeal lithotripsy. More than 10 years ago shock waves were successfully applied for various indications such as chronic pain, non-unions and, recently, for angina pectoris. These fields do not profit from the disintegration power but from stimulating and healing effects of shock waves. Increased metabolism and neo-vascularization are reported after shock wave application. According to C. J. Wang, a biological cascade is initiated, starting with a stimulating effect of physical energy resulting in increased circulation and metabolism. Pathological memory of neural control patterns is considered the reason for different pathologies characterized by insufficient metabolism. This paper presents a neural model for reorganization of pathological reflex patterns. The model acts on associative memory functions of the brain based on modification of synaptic junctions. Accordingly, pathological memory effects of the autonomous nervous system are reorganized by repeated application of shock waves followed by development of normal reflex patterns. Physiologic control of muscle and vascular tone is followed by increased metabolism and tissue repair. The memory model may explain hyper-stimulation effects in pain therapy.

  9. Administration of colistin sulfate in endotoxic model at slow and sustained fashion may reverse shock without causing nephrotoxicity in its optimal concentration.

    Science.gov (United States)

    Haque, Anwarul; Ishii, Yoshikazu; Akasaka, Yoshikiyo; Matsumoto, Tetsuya; Tateda, Kazuhiro

    2017-12-01

    Despite of proven LPS neutralizing activity, intravenous polymyxin use was waned due to experience of associated nephrotoxicity. But, increasing resistance to all available antibiotics has necessitated their resurgence and the prodrug of colistin sulfate (CS), known as colistin-methanesulfonate (CMS), is increasingly used as the only therapeutic option in many infections. Currently available CMS employ very different dose definitions and thus because of complex pharmacokinetics/pharmacodynamics information and short half-life, this drug use remains confusing. We aimed to expose CS in endotoxic shock models by micro-osmotic pump and evaluated its effectiveness. We used micro-osmotic pumps to deliver either sterile saline or CS at different dosages ranging from 0.25mg/day to 7mg/day for consecutive 3days in LPS (8mg/kg body weight) induced endotoxic mice and observed their outcome twice daily for a week to determine the survival rate. Serum pro-inflammatory cytokine levels and apoptosis in renal tissues in these models were evaluated. We showed endotoxic shock was reversed and all mice survived with a CS administration at a dosage of 2mg/day for 3 days, in comparison to survival rate with saline administration (p≤0.0001) in endotoxic models. CS infusion in shock models using micro-osmotic pump ameliorated rising of serum TNF-α, IL-12p70 and IL-6 levels. Nephrotoxicity was evident only with a higher dosage, but not with a lower dosage which was optimum to control endotoxic shock in models. These results highlighted that an optimal dosage of CS effectively improved outcome in endotoxic shock models without causing nephrotoxicity when administered at a slow and sustained manner. And a higher CS dosage administration was nephrotoxic and fatal. Thus this study bought an opportunity to consider future investigations with CS administration in murine Gram-negative bacterial infections in a novel way. Copyright © 2017 International Society for Chemotherapy of Infection

  10. Generalized continuous linear model of international trade

    Directory of Open Access Journals (Sweden)

    Kostenko Elena

    2014-01-01

    Full Text Available The probability-based approach to the linear model of international trade based on the theory of Markov processes with continuous time is analysed. A generalized continuous model of international trade is built, in which the transition of the system from state to state is described by linear differential equations. The methodology of how to obtain the intensity matrices, which are differential in nature, is shown, and the same is done for their corresponding transition matrices for processes of purchasing and selling. In the process of the creation of the continuous model, functions and operations of matrices were used in addition to the Laplace transform, which gave the analytical form of the transition matrices, and therefore the expressions for the state vectors of the system. The obtained expressions simplify analysis and calculations in comparison to other methods. The values of the continuous transition matrices include in themselves the results of discrete model of international trade at moments in time proportional to the time step. The continuous model improves the quality of planning and the effectiveness of control of international trade agreements.

  11. Arrival times of Flare/Halo CME associated shocks at the Earth: comparison of the predictions of three numerical models with these observations

    Directory of Open Access Journals (Sweden)

    S. M. P. McKenna-Lawlor

    2002-07-01

    Full Text Available The arrival times at L1 of eleven travelling shocks associated both with X-ray flaring and with halo CMEs recorded aboard SOHO/LASCO have been considered. Close to the Sun the velocities of these events were estimated using either Type II radio records or CME speeds. Close to the Earth the shocks were detected in the data of various solar wind plasma, interplanetary magnetic field (IMF and energetic particle experiments aboard SOHO, ACE, WIND, INTERBALL-1 and IMP-8. The real-time shock arrival predictions of three numerical models, namely the Shock Time of Arrival Model (STOA, the Interplanetary Shock Propagation Model (ISPM and the Hakamada-Akasofu-Fry Solar Wind Model (HAFv.2 were tested against these observations. This is the first time that energetic protons (tens of keV to a few MeV have been used to complement plasma and IMF data in validating shock propagation models. The models were all generally successful in predicting shock arrivals. STOA provided the smallest values of the "predicted minus measured" arrival times and displayed a typical predictive precision better than about 8 h. The ratio of the calculated standard deviation of the transit times to Earth to the standard deviation of the measurements was estimated for each model (treating interacting events as composite shocks and these ratios turned out to be 0.60, 1.15 and 1.02 for STOA, ISPM and HAFv.2, respectively. If an event in the sample for which the shock velocity was not well known is omitted from consideration, these ratios become 0.36, 0.76 and 0.81, respectively. Larger statistical samples should now be tested. The ratio of the in situ shock velocity and the "Sun to L1" transit velocity (Vsh /Vtr was in the range of 0.7–0.9 for individual, non-interacting, shock events. HAFv.2 uniquely provided information on those changes in the COBpoint (the moving Connection point on the shock along the IMF to the OBserver which directly influenced energetic particle rise times

  12. Efficacy of Methylene Blue in an Experimental Model of Calcium Channel Blocker Induced Shock

    Science.gov (United States)

    Jang, David H.; Donovan, Sean; Nelson, Lewis S.; Bania, Theodore C.; Hoffman, Robert S.; Chu, Jason

    2014-01-01

    BACKGROUND Calcium channel blocker poisonings account for a substantial number of reported deaths from cardiovascular drugs. While supportive care is the mainstay of treatment, experimental therapies such as high dose insulin-euglycemia and lipid emulsion have been studied in animal models and used in humans. In the most severe cases even aggressive care is inadequate and deaths occur. In both experimental models and clinical cases of vasodilatory shock, methylene blue improves hemodynamic measures. Methylene blue acts as both a nitric oxide scavenger and inhibits guanylate cyclase that is responsible for the production of cGMP. Excessive cGMP production is associated with refractory vasodilatory shock in sepsis and anaphylaxis. The aim of this study was to determine the efficacy of methylene blue in an animal model of amlodipine-induced shock. METHODS Sprague-Dawley rats were anesthetized, ventilated and instrumented for continuous blood pressure and heart rate monitoring. The dose of amlodipine that produced death within 60 minutes was 17 mg/kg/hour (LD50). Rats were divided into 2 groups: amlodipine followed by methylene blue or amlodipine followed by normal saline (NS) with 15 rats in each group. Rats received methylene blue at 2 mg/kg over 5 mins or an equivalent amount of NS in three intervals from the start of the protocol: Minute 5, 30, and 60. The animals were observed for a total of 2 hours after the start of the protocol. Mortality risk and survival time were analyzed using Fisher’s exact test and Kaplan Meier survival analysis with the log rank test. RESULTS Overall, 1/15 (7%) rats in the saline-treated group survived to 120 minutes compared with 5/15 (33%) rats in the methylene blue-treated group (difference −26%, 95% CI –54%, 0.3%). The median survival time for the NS group was 42 min (95% CI, 28.1,55.9) and the methylene blue group was 109 min (95% CI, 93.9,124.1). Heart rate and MAP differences between groups were analyzed until 60 minutes

  13. Analysis and modelling of septic shock microarray data using Singular Value Decomposition.

    Science.gov (United States)

    Allanki, Srinivas; Dixit, Madhulika; Thangaraj, Paul; Sinha, Nandan Kumar

    2017-06-01

    Being a high throughput technique, enormous amounts of microarray data has been generated and there arises a need for more efficient techniques of analysis, in terms of speed and accuracy. Finding the differentially expressed genes based on just fold change and p-value might not extract all the vital biological signals that occur at a lower gene expression level. Besides this, numerous mathematical models have been generated to predict the clinical outcome from microarray data, while very few, if not none, aim at predicting the vital genes that are important in a disease progression. Such models help a basic researcher narrow down and concentrate on a promising set of genes which leads to the discovery of gene-based therapies. In this article, as a first objective, we have used the lesser known and used Singular Value Decomposition (SVD) technique to build a microarray data analysis tool that works with gene expression patterns and intrinsic structure of the data in an unsupervised manner. We have re-analysed a microarray data over the clinical course of Septic shock from Cazalis et al. (2014) and have shown that our proposed analysis provides additional information compared to the conventional method. As a second objective, we developed a novel mathematical model that predicts a set of vital genes in the disease progression that works by generating samples in the continuum between health and disease, using a simple normal-distribution-based random number generator. We also verify that most of the predicted genes are indeed related to septic shock. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Mixed butanols addition to gasoline surrogates: Shock tube ignition delay time measurements and chemical kinetic modeling

    KAUST Repository

    AlRamadan, Abdullah S.

    2015-10-01

    The demand for fuels with high anti-knock quality has historically been rising, and will continue to increase with the development of downsized and turbocharged spark-ignition engines. Butanol isomers, such as 2-butanol and tert-butanol, have high octane ratings (RON of 105 and 107, respectively), and thus mixed butanols (68.8% by volume of 2-butanol and 31.2% by volume of tert-butanol) can be added to the conventional petroleum-derived gasoline fuels to improve octane performance. In the present work, the effect of mixed butanols addition to gasoline surrogates has been investigated in a high-pressure shock tube facility. The ignition delay times of mixed butanols stoichiometric mixtures were measured at 20 and 40bar over a temperature range of 800-1200K. Next, 10vol% and 20vol% of mixed butanols (MB) were blended with two different toluene/n-heptane/iso-octane (TPRF) fuel blends having octane ratings of RON 90/MON 81.7 and RON 84.6/MON 79.3. These MB/TPRF mixtures were investigated in the shock tube conditions similar to those mentioned above. A chemical kinetic model was developed to simulate the low- and high-temperature oxidation of mixed butanols and MB/TPRF blends. The proposed model is in good agreement with the experimental data with some deviations at low temperatures. The effect of mixed butanols addition to TPRFs is marginal when examining the ignition delay times at high temperatures. However, when extended to lower temperatures (T < 850K), the model shows that the mixed butanols addition to TPRFs causes the ignition delay times to increase and hence behaves like an octane booster at engine-like conditions. © 2015 The Combustion Institute.

  15. International Planetary Data Alliance (IPDA) Information Model

    Science.gov (United States)

    Hughes, John Steven; Beebe, R.; Guinness, E.; Heather, D.; Huang, M.; Kasaba, Y.; Osuna, P.; Rye, E.; Savorskiy, V.

    2007-01-01

    This document is the third deliverable of the International Planetary Data Alliance (IPDA) Archive Data Standards Requirements Identification project. The goal of the project is to identify a subset of the standards currently in use by NASAs Planetary Data System (PDS) that are appropriate for internationalization. As shown in the highlighted sections of Figure 1, the focus of this project is the Information Model component of the Data Architecture Standards, namely the object models, a data dictionary, and a set of data formats.

  16. Double shock experiments and reactive flow modeling on LX-17 to understand the reacted equation of state

    International Nuclear Information System (INIS)

    Vandersall, Kevin S; Garcia, Frank; Fried, Laurence E; Tarver, Craig M

    2014-01-01

    Experimental data from measurements of the reacted state of an energetic material are desired to incorporate reacted states in modeling by computer codes. In a case such as LX-17 (92.5% TATB and 7.5% Kel-F by weight), where the time dependent kinetics of reaction is still not fully understood and the reacted state may evolve over time, this information becomes even more vital. Experiments were performed to measure the reacted state of LX-17 using a double shock method involving the use of two flyer materials (with known properties) mounted on the projectile that send an initial shock through the material close to or above the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. By measuring the parameters of the first and second shock waves, information on the reacted state can be obtained. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments.

  17. Assessment of Computational Fluid Dynamics (CFD) Models for Shock Boundary-Layer Interaction

    Science.gov (United States)

    DeBonis, James R.; Oberkampf, William L.; Wolf, Richard T.; Orkwis, Paul D.; Turner, Mark G.; Babinsky, Holger

    2011-01-01

    A workshop on the computational fluid dynamics (CFD) prediction of shock boundary-layer interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses.

  18. Cissampelos sympodialis Eichl. (Menispermaceae inhibits anaphylactic shock reaction in murine allergic model

    Directory of Open Access Journals (Sweden)

    C.R. Bezerra-Santos

    Full Text Available The murine model of OVA-induced immediate allergic reaction was used to evaluate the effectiveness of intraperitoneal sub-acute treatment with the leaf hydroalcoholic extract of Cissampelos sympodialis (AFL in the anaphylactic shock reaction, IgE production and the background proliferative response. BALB/c mice treated with AFL ranging from 200 to 400 mg/kg/day for 5 days before and during OVA-sensitization strongly reduced the animal death and promoted reduction in total and OVA-specific serum IgE level. Spleen cells from AFL-treated sensitized animals showed a decreased proliferative background response when compared with non-sensitized animals. These results demonstrated that sub-acute intraperitoneal treatment with Cissampelos sympodialis extract has an anti-allergic effect.

  19. Modelling of thermal shock experiments of carbon based materials in JUDITH

    Science.gov (United States)

    Ogorodnikova, O. V.; Pestchanyi, S.; Koza, Y.; Linke, J.

    2005-03-01

    The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

  20. Modelling of thermal shock experiments of carbon based materials in JUDITH

    International Nuclear Information System (INIS)

    Ogorodnikova, O.V.; Pestchanyi, S.; Koza, Y.; Linke, J.

    2005-01-01

    The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments

  1. The Outsider's Syndrome Model: an inquiry into the psychodynamics of culture shock experience

    OpenAIRE

    Med HAFSI

    1992-01-01

    This paper explores the nature, or the psychodynamics of culture shock experience. The term culture shock, as far as I know, was first introduced by Oberg (1960), when studying the adjustment process of anthropologists to different cultures during their field research. For a longtime a subject for anthropology, thep henomenon of culture shock was studied as one of the phenomena observed during the course of adjustment to a new culture (Berry,1985). Recently, as can be shown by the large numbe...

  2. Shock tube and modeling study of 2,7-dimethyloctane pyrolysis and oxidation

    KAUST Repository

    Li, Sijie

    2015-05-01

    High molecular weight iso-paraffinic molecules are found in conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels, yet fundamental combustion studies on this class of compounds are lacking. In the present work, ignition delay time measurements in 2,7-dimethyloctane/air were carried out behind reflected shock waves using conventional and constrained reaction volume (CRV) methods. The ignition delay time measurements covered the temperature range 666-1216K, pressure range 12-27atm, and equivalence ratio of 0.5 and 1. The ignition delay time temperatures span the low-, intermediate- and high-temperature regimes for 2,7-dimethyloctane (2,7-DMO) oxidation. Clear evidence of negative temperature coefficient behavior was observed near 800K. Fuel time-history measurements were also carried out in pyrolysis experiments in mixtures of 2000ppm 2,7-DMO/argon at pressures near 16 and 35atm, and in the temperature range of 1126-1455K. Based on the fuel removal rates, the overall 2,7-DMO decomposition rate constant can be represented with k =4.47×105 exp(-23.4[kcal/mol]/RT) [1/s]. Ethylene time-history measurements in pyrolysis experiments at 16atm are also provided. The current shock tube dataset was simulated using a novel chemical kinetic model for 2,7-DMO. The reaction mechanism includes comprehensive low- and high-temperature reaction classes with rate constants assigned using established rules. Comparisons between the simulated and experimental data show simulations reproduce the qualitative trends across the entire range of conditions tested. However, the present kinetic modeling simulations cannot quantitatively reproduce a number of experimental data points, and these are analyzed herein.

  3. Boltzmann rovibrational collisional coarse-grained model for internal energy excitation and dissociation in hypersonic flows.

    Science.gov (United States)

    Munafò, A; Panesi, M; Magin, T E

    2014-02-01

    A Boltzmann rovibrational collisional coarse-grained model is proposed to reduce a detailed kinetic mechanism database developed at NASA Ames Research Center for internal energy transfer and dissociation in N(2)-N interactions. The coarse-grained model is constructed by lumping the rovibrational energy levels of the N(2) molecule into energy bins. The population of the levels within each bin is assumed to follow a Boltzmann distribution at the local translational temperature. Excitation and dissociation rate coefficients for the energy bins are obtained by averaging the elementary rate coefficients. The energy bins are treated as separate species, thus allowing for non-Boltzmann distributions of their populations. The proposed coarse-grained model is applied to the study of nonequilibrium flows behind normal shock waves and within converging-diverging nozzles. In both cases, the flow is assumed inviscid and steady. Computational results are compared with those obtained by direct solution of the master equation for the rovibrational collisional model and a more conventional multitemperature model. It is found that the proposed coarse-grained model is able to accurately resolve the nonequilibrium dynamics of internal energy excitation and dissociation-recombination processes with only 20 energy bins. Furthermore, the proposed coarse-grained model provides a superior description of the nonequilibrium phenomena occurring in shock heated and nozzle flows when compared with the conventional multitemperature models.

  4. Models and phantoms for internal dose assessment

    International Nuclear Information System (INIS)

    Giussani, Augusto

    2015-01-01

    Radiation doses delivered by incorporated radionuclides cannot be directly measured, and they are assessed by means of biokinetic and dosimetric models and computational phantoms. For emitters of short-range radiation like alpha-particles or Auger electrons, the doses at organ levels, as they are usually defined in internal dosimetry, are no longer relevant. Modelling the inter- and intra-cellular radiation transport and the local patterns of deposition at molecular or cellular levels are the challenging tasks of micro- and nano-dosimetry. With time, the physiological and anatomical realism of the models and phantoms have increased. However, not always the information is available that would be required to characterise the greater complexity of the recent models. Uncertainty studies in internal dose assessment provide here a valuable contribution for testing the significance of the new dose estimates and of the discrepancies from the previous values. Some of the challenges, limitations and future perspectives of the use of models and phantoms in internal dosimetry are discussed in the present manuscript. (authors)

  5. International Space Station Model Correlation Analysis

    Science.gov (United States)

    Laible, Michael R.; Fitzpatrick, Kristin; Hodge, Jennifer; Grygier, Michael

    2018-01-01

    This paper summarizes the on-orbit structural dynamic data and the related modal analysis, model validation and correlation performed for the International Space Station (ISS) configuration ISS Stage ULF7, 2015 Dedicated Thruster Firing (DTF). The objective of this analysis is to validate and correlate the analytical models used to calculate the ISS internal dynamic loads and compare the 2015 DTF with previous tests. During the ISS configurations under consideration, on-orbit dynamic measurements were collected using the three main ISS instrumentation systems; Internal Wireless Instrumentation System (IWIS), External Wireless Instrumentation System (EWIS) and the Structural Dynamic Measurement System (SDMS). The measurements were recorded during several nominal on-orbit DTF tests on August 18, 2015. Experimental modal analyses were performed on the measured data to extract modal parameters including frequency, damping, and mode shape information. Correlation and comparisons between test and analytical frequencies and mode shapes were performed to assess the accuracy of the analytical models for the configurations under consideration. These mode shapes were also compared to earlier tests. Based on the frequency comparisons, the accuracy of the mathematical models is assessed and model refinement recommendations are given. In particular, results of the first fundamental mode will be discussed, nonlinear results will be shown, and accelerometer placement will be assessed.

  6. Mesoscale Modeling of Shock Wave Propagation and Dynamic Failure in Metallic Systems

    Science.gov (United States)

    Dongare, Avinash

    2013-03-01

    The response of materials under conditions of thermomechanical extremes is very complex and involves damage creation and propagation, phase transformation, heat generation and transfer, etc. A principal challenge in predictive modeling of failure behavior is presented by the gap between the atomistic description of micromechanisms of the relevant processes and the macoscale response in continuum simulations/experiments. This difficulty can be approached through the development of a robust mesoscopic computational model that retains the relevant physics and is capable of representing the material behavior at time- and length-scales intermediate between the atomistic or continuum levels. Mesoscale models typically reduce a group of atoms by a mesoparticle system with much smaller number of collective degrees of freedom, and hence are often difficult to apply for problems such as heat transfer, phase transformation, and dissipation of mechanical energy during wave propagation. To achieve this goal, a novel mesoscopic model is being developed based on the idea of coarse-graining with the energetics defined for the particles based on interatomic potentials used in molecular dynamics (MD) simulations. The coarse-grained molecular dynamics simulations (CGMD) allows larger size systems and improved time-steps for simulations and thus able to extend the capabilities of MD simulations to model materials behavior at mesoscales. The successful application of the CGMD method is demonstrated by prediction of the phase-transformation, heat generation and wave-propagation behavior under the conditions of shock loading, as would be predicted using MD simulations.

  7. Terminal-shock and restart control of a Mach 2.5, axisymmetric, mixed compression inlet with 40 percent internal contraction. [wind tunnel tests

    Science.gov (United States)

    Baumbick, R. J.

    1974-01-01

    Results of experimental tests conducted on a supersonic, mixed-compression, axisymmetric inlet are presented. The inlet is designed for operation at Mach 2.5 with a turbofan engine (TF-30). The inlet was coupled to either a choked orifice plate or a long duct which had a variable-area choked exit plug. Closed-loop frequency responses of selected diffuser static pressures used in the terminal-shock control system are presented. Results are shown for Mach 2.5 conditions with the inlet coupled to either the choked orifice plate or the long duct. Inlet unstart-restart traces are also presented. High-response inlet bypass doors were used to generate an internal disturbance and also to achieve terminal-shock control.

  8. Neural correlates of internal-model loading.

    Science.gov (United States)

    Bursztyn, Lulu L C D; Ganesh, G; Imamizu, Hiroshi; Kawato, Mitsuo; Flanagan, J Randall

    2006-12-19

    Skilled object manipulation requires knowledge, or internal models, of object dynamics relating applied force to motion , and our ability to handle myriad objects indicates that the brain maintains multiple models . Recent behavioral studies have shown that once learned, an internal model of an object with novel dynamics can be rapidly recruited and derecruited as the object is grasped and released . We used event-related fMRI to investigate neural activity linked to grasping an object with recently learned dynamics in preparation for moving it after a delay. Subjects also performed two control tasks in which they either moved without the object in hand or applied isometric forces to the object. In all trials, subjects received a cue indicating which task to perform in response to a go signal delivered 5-10 s later. We examined BOLD responses during the interval between the cue and go and assessed the conjunction of the two contrasts formed by comparing the primary task to each control. The analysis revealed significant activity in the ipsilateral cerebellum and the contralateral and supplementary motor areas. We propose that these regions are involved in internal-model recruitment in preparation for movement execution.

  9. Disequilibrium macro model and catastrophe theory: the case of an oil shock

    Energy Technology Data Exchange (ETDEWEB)

    German, I.

    1983-01-01

    This study builds a simple disequilibrium macromodel of a small open economy that imports oil from an exogenous unit. The model is motivated by very slow adjustment of prices and wages to disequilibrium. Output on the other hand adjusts to its final level instantaneously. A rationing scheme is specified that explicitly takes into account the spillover effects and differentiates between notional, effective, and actual quantities. In a Solow-Stiglitz (1968) setting, a dynamic model is developed in which the dynamic forces depend on the economic environment specified by the Malinvandian regimes: Classical Unemployment, Keynesian Unemployment, Repressed Inflation, and the Walrasian Equilibrium. Given that dynamic system, the author seeks to identify the stationary points of the system (quasi-equilibria) and to find their stability properties. To the disequilibrium model an oil shock is introduced and its effects on employment, real output, real wage, and the stationary points of the system are investigated. A one-time increase (decrease) in the real price of oil and a continuous increase (decrease) in the real price of oil are considered. The path the economy takes and, in particular, the continuous and discontinuous behavior of the quasi-equilibria are investigated. Finally, the model government policy is incorporated and different policy alternatives are studied.

  10. A Novel Porcine Model of Septic Shock Induced by Acute Respiratory Distress Syndrome due to Methicillin-resistantStaphylococcus aureus.

    Science.gov (United States)

    Wang, Shuo; Wang, Jun-Yu; Wang, Tao; Hang, Chen-Chen; Shao, Rui; Li, Chun-Sheng

    2017-05-20

    Sepsis is one of the main causes of mortality in critically ill patients following progression to septic shock. To investigate the pathophysiologic changes of sepsis, we developed a novel porcine model of septic shock induced by acute respiratory distress syndrome (ARDS) due to methicillin-resistant Staphylococcus aureus(MRSA) pneumonia. Twenty-six male Landraces (Lvyuanweiye, Beijing, China) weighing 30 ± 2 kg were divided into four groups: sham group (SH; n = 5); cotton smoke inhalation group (SM; n = 6); MRSA pneumonia group (MR; n = 6); and septic shock group with cotton smoke inhalation + MRSA pneumonia (SS; n = 9). Extensive hemodynamics, oxygen dynamics, and lung function were monitored for 24 h following the injury or until death. Tissues were collected, and histopathology evaluations were carried out. Blood cultures from 6 of 9 animals in the SS group were positive for MRSA. Two hours following the injury, decreased mean arterial blood pressure (60-70 mmHg) and cardiac index (septic shock were only observed in the SS group but not significant in the other groups. The PO2/FiO2in the SM and SS groups decreased to 300 and 100, respectively. In the SS group, extravascular lung water index increased to 20 ml/kg, whereas thoracopulmonary compliance decreased to 10 ml/H2O after injury. Deterioration of pulmonary function in the SS group was more serious than the SM and MR groups. Severe lung injury in the SS group was confirmed by the histopathology evaluations. The lung injury confirmed by high-resolution thin-section computed tomography and histopathology in the SS group was more serious than those of other groups. In the present study, we developed a novel porcine model of septic shock induced by ARDS due to severe MRSA pneumonia with characteristic hyperdynamic and hypodynamic phases in 24 h, which mimicked the hemodynamic changing of septic shock in human.

  11. CME Flux Rope and Shock Identifications and Locations: Comparison of White Light Data, Graduated Cylindrical Shell Model, and MHD Simulations

    Science.gov (United States)

    Schmidt, J. M.; Cairns, Iver H.; Xie, Hong; St. Cyr, O. C.; Gopalswamy, N.

    2016-01-01

    Coronal mass ejections (CMEs) are major transient phenomena in the solar corona that are observed with ground-based and spacecraft-based coronagraphs in white light or with in situ measurements by spacecraft. CMEs transport mass and momentum and often drive shocks. In order to derive the CME and shock trajectories with high precision, we apply the graduated cylindrical shell (GCS) model to fit a flux rope to the CME directed toward STEREO A after about 19:00 UT on 29 November 2013 and check the quality of the heliocentric distance-time evaluations by carrying out a three-dimensional magnetohydrodynamic (MHD) simulation of the same CME with the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. Heliocentric distances of the CME and shock leading edges are determined from the simulated white light images and magnetic field strength data. We find very good agreement between the predicted and observed heliocentric distances, showing that the GCS model and the BATS-R-US simulation approach work very well and are consistent. In order to assess the validity of CME and shock identification criteria in coronagraph images, we also compute synthetic white light images of the CME and shock. We find that the outer edge of a cloud-like illuminated area in the observed and predicted images in fact coincides with the leading edge of the CME flux rope and that the outer edge of a faint illuminated band in front of the CME leading edge coincides with the CME-driven shock front.

  12. Modeling Protein Aggregation and the Heat Shock Response in ALS iPSC-Derived Motor Neurons.

    Science.gov (United States)

    Seminary, Emily R; Sison, Samantha L; Ebert, Allison D

    2018-01-01

    Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder caused by the selective loss of the upper and lower motor neurons. Only 10% of all cases are caused by a mutation in one of the two dozen different identified genes, while the remaining 90% are likely caused by a combination of as yet unidentified genetic and environmental factors. Mutations in C9orf72, SOD1 , or TDP-43 are the most common causes of familial ALS, together responsible for at least 60% of these cases. Remarkably, despite the large degree of heterogeneity, all cases of ALS have protein aggregates in the brain and spinal cord that are immunopositive for SOD1, TDP-43, OPTN, and/or p62. These inclusions are normally prevented and cleared by heat shock proteins (Hsps), suggesting that ALS motor neurons have an impaired ability to induce the heat shock response (HSR). Accordingly, there is evidence of decreased induction of Hsps in ALS mouse models and in human post-mortem samples compared to unaffected controls. However, the role of Hsps in protein accumulation in human motor neurons has not been fully elucidated. Here, we generated motor neuron cultures from human induced pluripotent stem cell (iPSC) lines carrying mutations in SOD1, TDP-43 , or C9orf72 . In this study, we provide evidence that despite a lack of overt motor neuron loss, there is an accumulation of insoluble, aggregation-prone proteins in iPSC-derived motor neuron cultures but that content and levels vary with genetic background. Additionally, although iPSC-derived motor neurons are generally capable of inducing the HSR when exposed to a heat stress, protein aggregation itself is not sufficient to induce the HSR or stress granule formation. We therefore conclude that ALS iPSC-derived motor neurons recapitulate key early pathological features of the disease and fail to endogenously upregulate the HSR in response to increased protein burden.

  13. Laser-shocked energetic materials for laboratory-scale characterization and model validation

    Science.gov (United States)

    Gottfried, Jennifer

    The development of laboratory-scale methods for characterizing the properties of energetic materials, i.e., using only milligram quantities of material, is essential for the development of new types of explosives and propellants for use in military applications. Laser-based excitation methods for initiating or exciting the energetic material offer several advantages for investigating the response of energetic materials to various stimuli: 1) very small quantities of material can be studied prior to scale-up synthesis, 2) no detonation of bulk energetic material is required, eliminating the need for expensive safety precautions, and 3) extensive diagnostics can be incorporated into the experimental setup to provide as much information as possible per shot. In this presentation, progress in our laboratory developing three laser-based methods for characterizing energetic materials will be discussed. Direct excitation of a sample residue using a focused nanosecond laser pulse enables estimation of the performance of the energetic material based on the measured shock wave velocity with a technique called laser-induced air shock from energetic materials (LASEM); recent LASEM results on novel energetic materials will be presented. Impact ignition of energetic materials has also been investigated using laser-driven flyer plates. High-speed schlieren imaging of the flyer plate launch has demonstrated that late-time emission from the impacted energetic material is caused by the reaction of particles ejected off the sample surface with the flyer plate launch products. Finally, the role of a rapid temperature jump (1014 K/s) in the initiation of the explosive cyclotrimethylenetrinitramine (RDX) has been investigated by indirect ultrafast laser heating. Although the temperature jump was insufficient to decompose the RDX, it did induce a temporary electronic excitation of the heated explosive molecules. These results are being used to validate multiscale models in order to

  14. The Air Quality Model Evaluation International Initiative ...

    Science.gov (United States)

    This presentation provides an overview of the Air Quality Model Evaluation International Initiative (AQMEII). It contains a synopsis of the three phases of AQMEII, including objectives, logistics, and timelines. It also provides a number of examples of analyses conducted through AQMEII with a particular focus on past and future analyses of deposition. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

  15. Primary Blast Injury Criteria for Animal/Human TBI Models using Field Validated Shock Tubes

    Science.gov (United States)

    2017-09-01

    Assistance with exposure of animals , shock wave experimentation , Western blot Name: Stephanie Iring Project Role: Laboratory technician (biochemistry...Contribution to Project: Assistance with shock wave experimentation , exposure of animals , biochemistry work, data analysis, manuscript preparation Name... experimentation , exposure of animals , biochemistry work, data analysis, manuscript preparation Name: Debanjan Haldar Project Role: Undergraduate

  16. An International Model for Antibiotics Regulation.

    Science.gov (United States)

    Aguirre, Emilie

    We face a global antibiotics resistance crisis. Antibiotic drugs are rapidly losing their effectiveness, potentially propelling us toward a post-antibiotic world. The largest use of antibiotics in the world is in food-producing animals. Food producers administer these drugs in routine, low doses—the types of doses that are incidentally the most conducive to breeding antibiotic resistance. In general, individual countries have been too slow to act in regulating misuse and overuse of antibiotics in foodproducing animals. This problem will only worsen with the significant projected growth in meat consumption and production expected in emerging economies in the near future. Although individual countries regulating antibiotics can have important effects, one country alone cannot insulate itself entirely from the effects of antibiotic resistance, nor can one country solve the crisis for itself or for the world. The global nature of the food system and the urgency of the problem require immediate global solutions. Adapting a democratic experimentalist approach at the international level can help achieve this goal. Using an international democratic experimentalist framework in conjunction with the World Organization for Animal Health (OIE) would provide for increased systematized data collection and lead to heightened, scientifically informed OIE standards, enforceable by the World Trade Organization (WTO), which could have a significant impact on the reduction of subtherapeutic use of antibiotics internationally. International democratic experimentalism addresses the global intricacy, time sensitivity, context- and culture-specificity, and knowledgeintensiveness of this problem. By encouraging more countries to experiment to solve this problem, the democratic experimentalist model would help develop a larger database of solutions to enable more meaningful cross-country comparisons across a wider range of contexts. This approach maintains democratic governance and

  17. Proceedings of the International Symposium on Shock Tubes and Waves (13th), Niagara Falls, July 6-9, 1981.

    Science.gov (United States)

    1981-07-01

    orifice dian - eters. Omparison of diaphragm kinetic energy and strain energy of deforma- tion during yield at the rate of pressure rise experienced in the...Department of Physical Sciences, Kingsborougho \\Community College of CUNY , Brooklyn, NY, USA An ultra-clean 2 in I.D. single pulse shock tube coupled to

  18. AN EQUILIBRIUM AGGREGATE DEMAND AND SUPPLY MODEL TO EXAMINE THE DYNAMIC EFFECT OF OIL PRICE SHOCKS ON OUTPUT AND INFLATION IN IRAN AS AN OIL EXPORTING COUNTRY

    Directory of Open Access Journals (Sweden)

    Sajjad Barkordari

    2017-09-01

    Full Text Available Iran is an oil exporting country in Middle East. The high share of the oil revenues in Iran is a serious economic problem. Due to the high dependency of Iran’s economy on oil revenues, oil price shocks have a determinant impact on macroeconomic variables. In this paper, we analyze the dynamic effects of oil price shocks and the aggregate supply and aggregate demand shocks on macroeconomic fluctuations in Iran. According to macroeconomic theory and aggregate demand and supply model in equilibrium, a structural vector autoregressive (VAR model is applied to identify different structural shocks and further assess the relative contributions of different shocks on macroeconomic fluctuations, using a decomposition approach. The results show that oil price shocks have significant and positive effects on both output and inflation. Aggregate supply and aggregate demand shocks are the main causes of fluctuation in output and inflation, and moreover, the effect of aggregate supply shocks on output is permanent in the Iranian economy. On the base of this study results, we suggest the Iranian government should accelerate the economic reforms such as the finance system of state owned enterprises, the tax system, the cash subsidy distribution system, the allocation system of the government budget in national and provincial level, the financial and banking system, and so on. The suggested reforms aim to decrease in the share of oil revenues in the economy and protect the Iranian economy in the face of any exogenous and endogenous shocks.

  19. Efficacy of methylene blue in an experimental model of calcium channel blocker-induced shock.

    Science.gov (United States)

    Jang, David H; Donovan, Sean; Nelson, Lewis S; Bania, Theodore C; Hoffman, Robert S; Chu, Jason

    2015-04-01

    Calcium channel blocker poisonings account for a substantial number of reported deaths from cardiovascular drugs. Although supportive care is the mainstay of treatment, experimental therapies such as high-dose insulin-euglycemia and lipid emulsion have been studied in animal models and used in humans. In the most severe cases, even aggressive care is inadequate and deaths occur. In both experimental models and clinical cases of vasodilatory shock, methylene blue improves hemodynamic measures. It acts as a nitric oxide scavenger and inhibits guanylate cyclase that is responsible for the production of cyclic guanosine monophosphate (cGMP). Excessive cGMP production is associated with refractory vasodilatory shock in sepsis and anaphylaxis. The aim of this study is to determine the efficacy of methylene blue in an animal model of amlodipine-induced shock. Sprague-Dawley rats were anesthetized, ventilated, and instrumented for continuous blood pressure and pulse rate monitoring. The dose of amlodipine that produced death within 60 minutes was 17 mg/kg per hour (LD50). Rats were divided into 2 groups: amlodipine followed by methylene blue or amlodipine followed by normal saline solution, with 15 rats in each group. Rats received methylene blue at 2 mg/kg during 5 minutes or an equivalent amount of normal saline solution in 3 intervals from the start of the protocol: minutes 5, 30, and 60. The animals were observed for a total of 2 hours after the start of the protocol. Mortality risk and survival time were analyzed with Fisher's exact test and Kaplan-Meier survival analysis with the log rank test. Overall, 1 of 15 rats (7%) in the saline solution-treated group survived to 120 minutes compared with 5 of 15 (33%) in the methylene blue-treated group (difference -26%; 95% confidence interval [CI] -54% to 0.3%). The median survival time for the normal saline solution group was 42 minutes (95% CI 28.1 to 55.9 minutes); for the methylene blue group, 109 minutes (95% CI 93.9 to

  20. Determining the Cardiovascular Effect of Partial versus Complete REBOA in a Porcine (Sus scrofa) Model of Hemorrhagic Shock.

    Science.gov (United States)

    2018-03-09

    the Cardiovascular Effect of Partial versus Complete REBOA in a Porcine (Sus scrofa) Model of Hemorrhagic Shock. PRINCIPAL INVESTIGATOR (PI...or sentience been identified as potential study/training models in this protocol? No. REDUCTION: Since the last IACUC approval, have any methods...questions regarding applicability of REBOA in different positions for different therapeutic goals . This will, in turn, help to guide the practice of

  1. Simulation of shock-induced bubble collapse using a four-equation model

    Science.gov (United States)

    Goncalves, E.; Hoarau, Y.; Zeidan, D.

    2018-02-01

    This paper presents a numerical study of the interaction between a planar incident shock wave with a cylindrical gas bubble. Simulations are performed using an inviscid compressible one-fluid solver based upon three conservation laws for the mixture variables, namely mass, momentum, and total energy along with a supplementary transport equation for the volume fraction of the gas phase. The study focuses on the maximum pressure generated by the bubble collapse. The influence of the strength of the incident shock is investigated. A law for the maximum pressure function of the Mach number of the incident shock is proposed.

  2. Shock tubes and waves; Proceedings of the Sixteenth International Symposium, Rheinisch-Westfaelische Technische Hochschule, Aachen, Federal Republic of Germany, July 26-31, 1987

    Science.gov (United States)

    Groenig, Hans

    Topics discussed in this volume include shock wave structure, propagation, and interaction; shocks in condensed matter, dusty gases, and multiphase media; chemical processes and related combustion and detonation phenomena; shock wave reflection, diffraction, and focusing; computational fluid dynamic code development and shock wave application; blast and detonation waves; advanced shock tube technology and measuring technique; and shock wave applications. Papers are presented on dust explosions, the dynamics of shock waves in certain dense gases, studies of condensation kinetics behind incident shock waves, the autoignition mechanism of n-butane behind a reflected shock wave, and a numerical simulation of the focusing process of reflected shock waves. Attention is also given to the equilibrium shock tube flow of real gases, blast waves generated by planar detonations, modern diagnostic methods for high-speed flows, and interaction between induced waves and electric discharge in a very high repetition rate excimer laser.

  3. Stochastic model theory of broadband shock associated noise from supersonic jets

    Science.gov (United States)

    Tam, C. K. W.

    1987-01-01

    A method based on the work of Tam and Tanna (1982) for calculating the near field noise spectrum and the spatial distribution of broadband shock associated noise from supersonic jets is proposed. Multiple-scales expansion is used to decompose the quasi-periodic shock cells into time-independent waveguide modes of the jet flow, and the interaction of the instability waves with each of the waveguide modes is shown to generate unsteady disturbances which become part of the broadband shock associated noise when radiated to the far field. The observed broadband shock associated noise is composed of a superposition of the various distinct spectra of the different waveguide modes, and the multispectra can be easily identified in many of the existing far and near field noise measurements.

  4. Turbulence Models: Data from Other Experiments: Shock Wave / Turbulent Boundary Layer Flows at High Mach Numbers

    Data.gov (United States)

    National Aeronautics and Space Administration — Shock Wave / Turbulent Boundary Layer Flows at High Mach Numbers. This web page provides data from experiments that may be useful for the validation of turbulence...

  5. Ship Shock Trial Modeling and Simulation of USS WINSTON S. CHURCHHILL (DDG 81)

    National Research Council Canada - National Science Library

    Schneider, Nathan

    2003-01-01

    ... in a severe shock environment. While these tests are extremely important in determining the vulnerabilities of a surface ship they require an extensive amount of preparation manhours, and money...

  6. Circulatory Shock. Volume 34. Number 1. May 1991. International Conference on Shock (2nd), Meeting of European Shock Society (5th), Annual Meeting of the Shock Society (USA) (14th), Vienna Shock Form (3rd) Held in Vienna, Austria on 2-6 June 1991

    Science.gov (United States)

    1991-06-06

    common medical therapies, one group received also glutathion tOSH ) 1200 mg/day. The trial lasted 15 days and the treated group showed a marked reduction in...coil SEPTIC SHOCK. E. Fischer, M.A. Marano, K. Van Zee, A.E. Hayes, C. Rock , A.A. Hudson, R.C. Thompson, S.F. Lowry, L.L. Moldawer (spons. H. Redl...at Greenspring 4301 W. Markham Baltimore, MD 21215 Little Rock , AR 72205 186 Membership Directory Connell, Reid S. Cunningham, Paul Dept. of Anatomy

  7. A Recipe for implementing the Arrhenius-Shock-Temperature State Sensitive WSD (AWSD) model, with parameters for PBX 9502

    Energy Technology Data Exchange (ETDEWEB)

    Aslam, Tariq Dennis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-03

    A reactive ow model for the tri-amino-tri-nitro-benzene (TATB) based plastic bonded explosive PBX 9502 is presented. This newly devised model is based primarily on the shock temperature of the material, along with local pressure, and accurately models a broader range of detonation and initiation scenarios. The equation of state for the reactants and products, as well as the thermodynamic closure of pressure and temperature equilibration are carried over from the Wescott-Stewart-Davis (WSD) model7,8. Thus, modifying an existing WSD model in a hydrocode should be rather straightforward.

  8. Mortality Prediction Model of Septic Shock Patients Based on Routinely Recorded Data

    OpenAIRE

    Carrara, Marta; Baselli, Giuseppe; Ferrario, Manuela

    2015-01-01

    We studied the problem of mortality prediction in two datasets, the first composed of 23 septic shock patients and the second composed of 73 septic subjects selected from the public database MIMIC-II. For each patient we derived hemodynamic variables, laboratory results, and clinical information of the first 48 hours after shock onset and we performed univariate and multivariate analyses to predict mortality in the following 7 days. The results show interesting features that individually iden...

  9. First-principles modeling of laser-matter interaction and plasma dynamics in nanosecond pulsed laser shock processing

    Science.gov (United States)

    Zhang, Zhongyang; Nian, Qiong; Doumanidis, Charalabos C.; Liao, Yiliang

    2018-02-01

    Nanosecond pulsed laser shock processing (LSP) techniques, including laser shock peening, laser peen forming, and laser shock imprinting, have been employed for widespread industrial applications. In these processes, the main beneficial characteristic is the laser-induced shockwave with a high pressure (in the order of GPa), which leads to the plastic deformation with an ultrahigh strain rate (105-106/s) on the surface of target materials. Although LSP processes have been extensively studied by experiments, few efforts have been put on elucidating underlying process mechanisms through developing a physics-based process model. In particular, development of a first-principles model is critical for process optimization and novel process design. This work aims at introducing such a theoretical model for a fundamental understanding of process mechanisms in LSP. Emphasis is placed on the laser-matter interaction and plasma dynamics. This model is found to offer capabilities in predicting key parameters including electron and ion temperatures, plasma state variables (temperature, density, and pressure), and the propagation of the laser shockwave. The modeling results were validated by experimental data.

  10. Heat Shock Response Associated with Hepatocarcinogenesis in a Murine Model of Hereditary Tyrosinemia Type I

    Energy Technology Data Exchange (ETDEWEB)

    Angileri, Francesca; Morrow, Geneviève; Roy, Vincent; Orejuela, Diana; Tanguay, Robert M., E-mail: robert.tanguay@ibis.ulaval.ca [Laboratory of Cell and Developmental Genetics, Department of Molecular Biology, Medical Biochemistry and Pathology, Institut de Biologie Intégrative et des Systèmes (IBIS) and PROTEO, 1030 avenue de la médecine, Université Laval, Québec G1V 0A6 (Canada)

    2014-04-23

    Hereditary Tyrosinemia type 1 (HT1) is a metabolic liver disease caused by genetic defects of fumarylacetoacetate hydrolase (FAH), an enzyme necessary to complete the breakdown of tyrosine. The severe hepatic dysfunction caused by the lack of this enzyme is prevented by the therapeutic use of NTBC (2-[2-nitro-4-(trifluoromethyl)benzoyl]cyclohexane-1,3-dione). However despite the treatment, chronic hepatopathy and development of hepatocellular carcinoma (HCC) are still observed in some HT1 patients. Growing evidence show the important role of heat shock proteins (HSPs) in many cellular processes and their involvement in pathological diseases including cancer. Their survival-promoting effect by modulation of the apoptotic machinery is often correlated with poor prognosis and resistance to therapy in a number of cancers. Here, we sought to gain insight into the pathophysiological mechanisms associated with liver dysfunction and tumor development in a murine model of HT1. Differential gene expression patterns in livers of mice under HT1 stress, induced by drug retrieval, have shown deregulation of stress and cell death resistance genes. Among them, genes coding for HSPB and HSPA members, and for anti-apoptotic BCL-2 related mitochondrial proteins were associated with the hepatocarcinogenetic process. Our data highlight the variation of stress pathways related to HT1 hepatocarcinogenesis suggesting the role of HSPs in rendering tyrosinemia-affected liver susceptible to the development of HCC.

  11. HSF1-dependent and -independent regulation of the mammalian in vivo heat shock response and its impairment in Huntington's disease mouse models.

    Science.gov (United States)

    Neueder, Andreas; Gipson, Theresa A; Batterton, Sophie; Lazell, Hayley J; Farshim, Pamela P; Paganetti, Paolo; Housman, David E; Bates, Gillian P

    2017-10-02

    The heat shock response (HSR) is a mechanism to cope with proteotoxic stress by inducing the expression of molecular chaperones and other heat shock response genes. The HSR is evolutionarily well conserved and has been widely studied in bacteria, cell lines and lower eukaryotic model organisms. However, mechanistic insights into the HSR in higher eukaryotes, in particular in mammals, are limited. We have developed an in vivo heat shock protocol to analyze the HSR in mice and dissected heat shock factor 1 (HSF1)-dependent and -independent pathways. Whilst the induction of proteostasis-related genes was dependent on HSF1, the regulation of circadian function related genes, indicating that the circadian clock oscillators have been reset, was independent of its presence. Furthermore, we demonstrate that the in vivo HSR is impaired in mouse models of Huntington's disease but we were unable to corroborate the general repression of transcription that follows a heat shock in lower eukaryotes.

  12. Shock Waves in Gas Dynamics

    Directory of Open Access Journals (Sweden)

    Abdolrahman Razani

    2007-11-01

    Full Text Available Shock wave theory was studied in literature by many authors. This article presents a survey with references about various topics related to shock waves: Hyperbolic conservation laws, Well-posedness theory, Compactness theory, Shock and reaction-diffusion wave, The CJ and ZND theory, Existence of detonation in Majda's model, Premixed laminar flame, Multidimensional gas flows, Multidimensional Riemann problem.

  13. Response of subassembly model with internals

    International Nuclear Information System (INIS)

    Kennedy, J.M.; Belytschko, T.

    1977-01-01

    Analytical tools have been developed and validated by controlled sets of experiments to understand the response of an accident and/or single subassembly in an LMFBR reasonably well. They have been subjected to a variety of loadings and boundary environments. Some large subassembly cluster experiments have been performed, however little analytical work has accompanied them because of the lack of suitable analytical tools. Reported are analytical approaches to: (1) development of more sophisiticated models for the subassembly internals, that is, the fuel pins and coolant; (2) development of models for representing three dimensional effects in subassemblies adjacent to the accident subassembly. These analytical developments will provide feasible capabilities for doing economical three-dimensional analysis not previously available

  14. Continuum dislocation-density based models for the dynamic shock response of single-crystal and polycrystalline materials

    Science.gov (United States)

    Luscher, Darby

    2017-06-01

    The dynamic thermomechanical responses of polycrystalline materials under shock loading are often dominated by the interaction of defects and interfaces. For example, polymer-bonded explosives (PBX) can initiate under weak shock impacts whose energy, if distributed homogeneously throughout the material, translates to temperature increases that are insufficient to drive the rapid chemistry observed. In such cases, heterogeneous thermomechanical interactions at the mesoscale (i.e. between single-crystal and macroscale) lead to the formation of localized hot spots. Within metals, a prescribed deformation associated with a shock wave may be accommodated by crystallographic slip, provided a sufficient population of mobile dislocations is available. However, if the deformation rate is large enough, there may be an insufficient number of freely mobile dislocations. In these cases, additional dislocations may be nucleated, or alternate mechanisms (e.g. twinning, damage) activated in order to accommodate the deformation. Direct numerical simulation at the mesoscale offers insight into these physical processes that can be invaluable to the development of macroscale constitutive theories, if the mesoscale models adequately represent the anisotropic nonlinear thermomechanical response of individual crystals and their interfaces. This talk will briefly outline a continuum mesoscale modeling framework founded upon local and nonlocal variations of dislocation-density based crystal plasticity theory. The nonlocal theory couples continuum dislocation transport with the local theory. In the latter, dislocation transport is modeled by enforcing dislocation conservation at a slip-system level through the solution of advection-diffusion equations. The configuration of geometrically necessary dislocation density gives rise to a back-stress that inhibits or accentuates the flow of dislocations. Development of the local theory and application to modeling the explosive molecular crystal

  15. Quantitative understanding of Forbush decrease drivers based on shock-only and CME-only models using global signature of February 14, 1978 event

    International Nuclear Information System (INIS)

    Raghav, Anil; Lotekar, Ajay; Bhaskar, Ankush; Vichare, Geeta; Yadav, Virendra

    2014-01-01

    We have studied the Forbush decrease (FD) event that occurred on February 14, 1978 using 43 neutron monitor observatories to understand the global signature of FD. We have studied rigidity dependence of shock amplitude and total FD amplitude. We have found almost the same power law index for both shock phase amplitude and total FD amplitude. Local time variation of shock phase amplitude and maximum depression time of FD have been investigated which indicate possible effect of shock/CME orientation. We have analyzed rigidity dependence of time constants of two phase recovery. Time constants of slow component of recovery phase show rigidity dependence and imply possible effect of diffusion. Solar wind speed was observed to be well correlated with slow component of FD recovery phase. This indicates solar wind speed as possible driver of recovery phase. To investigate the contribution of interplanetary drivers, shock and CME in FD, we have used shock-only and CME-only models. We have applied these models separately to shock phase and main phase amplitudes respectively. This confirms presently accepted physical scenario that the first step of FD is due to propagating shock barrier and second step is due to flux rope of CME/magnetic cloud

  16. A Novel mouse model of enhanced proteostasis: Full-length human heat shock factor 1 transgenic mice

    International Nuclear Information System (INIS)

    Pierce, Anson; Wei, Rochelle; Halade, Dipti; Yoo, Si-Eun; Ran, Qitao; Richardson, Arlan

    2010-01-01

    Research highlights: → Development of mouse overexpressing native human HSF1 in all tissues including CNS. → HSF1 overexpression enhances heat shock response at whole-animal and cellular level. → HSF1 overexpression protects from polyglutamine toxicity and favors aggresomes. → HSF1 overexpression enhances proteostasis at the whole-animal and cellular level. -- Abstract: The heat shock response (HSR) is controlled by the master transcriptional regulator heat shock factor 1 (HSF1). HSF1 maintains proteostasis and resistance to stress through production of heat shock proteins (HSPs). No transgenic model exists that overexpresses HSF1 in tissues of the central nervous system (CNS). We generated a transgenic mouse overexpressing full-length non-mutant HSF1 and observed a 2-4-fold increase in HSF1 mRNA and protein expression in all tissues studied of HSF1 transgenic (HSF1 +/0 ) mice compared to wild type (WT) littermates, including several regions of the CNS. Basal expression of HSP70 and 90 showed only mild tissue-specific changes; however, in response to forced exercise, the skeletal muscle HSR was more elevated in HSF1 +/0 mice compared to WT littermates and in fibroblasts following heat shock, as indicated by levels of inducible HSP70 mRNA and protein. HSF1 +/0 cells elicited a significantly more robust HSR in response to expression of the 82 repeat polyglutamine-YFP fusion construct (Q82YFP) and maintained proteasome-dependent processing of Q82YFP compared to WT fibroblasts. Overexpression of HSF1 was associated with fewer, but larger Q82YFP aggregates resembling aggresomes in HSF1 +/0 cells, and increased viability. Therefore, our data demonstrate that tissues and cells from mice overexpressing full-length non-mutant HSF1 exhibit enhanced proteostasis.

  17. International evidence on crude oil price dynamics. Applications of ARIMA-GARCH models

    International Nuclear Information System (INIS)

    Mohammadi, Hassan; Su, Lixian

    2010-01-01

    We examine the usefulness of several ARIMA-GARCH models for modeling and forecasting the conditional mean and volatility of weekly crude oil spot prices in eleven international markets over the 1/2/1997-10/3/2009 period. In particular, we investigate the out-of-sample forecasting performance of four volatility models - GARCH, EGARCH and APARCH and FIGARCH over January 2009 to October 2009. Forecasting results are somewhat mixed, but in most cases, the APARCH model outperforms the others. Also, conditional standard deviation captures the volatility in oil returns better than the traditional conditional variance. Finally, shocks to conditional volatility dissipate at an exponential rate, which is consistent with the covariance-stationary GARCH models than the slow hyperbolic rate implied by the FIGARCH alternative. (author)

  18. Splenectomy Versus Sham Splenectomy in a Swine Model of Controlled Hemorrhagic Shock.

    Science.gov (United States)

    Boysen, Søren R; Caulkett, Nigel A; Brookfield, Caroline E; Warren, Amy; Pang, Jessica M

    2016-10-01

    Splenectomy is controversial in acute hemorrhagic shock models. To compare splenectomized (SP) versus sham-splenectomized (SSP) swine during acute controlled hemorrhage. Twenty-six male Landrace White swine (mean body weight ± standard deviation, 33.8 ± 2.9 kg) were used. Ethics approval was obtained. Landrace swine underwent splenectomy (n = 13) or sham-splenectomy (n = 13), were bled to mean arterial blood pressure (MAP) of 40 mm Hg, which was held for 60 min, given 125 mL IV RescueFlow, held for a further 60 min, given whole blood, and held for a final 60 min. Tissue oxygen saturation, thromboelastography, oncotic pressure, urine volume and specific gravity, complete blood count, serum chemistry, body temperature, hematocrit, total solids, arterial and mixed venous blood gas, bispectral index, SAP, MAP, DAP, cardiac index, total blood volume (TBV) removed and returned, rate of hemorrhage and transfusion, spleen weight, heart rate (HR), arterial pH, lactate, PaO2, PaCO2, respiratory rate, cranial mesenteric and renal artery blood flow were recorded. Groups were compared using two-way ANOVA with post hoc Bonferroni (P splenectomy for the duration of the experiment (P splenectomy (P Splenectomy likely accounts for the transient increase in hematocrit and the higher HR in SP swine prior to hemorrhage, and the differences in TBV removed between the two groups during hemorrhage. With a fixed end point model using a moderate rate of acute hemorrhage and an MAP of 40 mm Hg, splenectomy is not necessary and may confound results.

  19. Establishing an International Soil Modelling Consortium

    Science.gov (United States)

    Vereecken, Harry; Schnepf, Andrea; Vanderborght, Jan

    2015-04-01

    -change-feedback processes, bridge basic soil science research and management, and facilitate the communication between science and society . To meet these challenges an international community effort is required, similar to initiatives in systems biology, hydrology, and climate and crop research. We therefore propose to establish an international soil modelling consortium with the aims of 1) bringing together leading experts in modelling soil processes within all major soil disciplines, 2) addressing major scientific gaps in describing key processes and their long term impacts with respect to the different functions and ecosystem services provided by soil, 3) intercomparing soil model performance based on standardized and harmonized data sets, 4) identifying interactions with other relevant platforms related to common data formats, protocols and ontologies, 5) developing new approaches to inverse modelling, calibration, and validation of soil models, 6) integrating soil modelling expertise and state of the art knowledge on soil processes in climate, land surface, ecological, crop and contaminant models, and 7) linking process models with new observation, measurement and data evaluation technologies for mapping and characterizing soil properties across scales. Our consortium will bring together modelers and experimental soil scientists at the forefront of new technologies and approaches to characterize soils. By addressing these aims, the consortium will contribute to improve the role of soil modeling as a knowledge dissemination instrument in addressing key global issues and stimulate the development of translational research activities. This presentation will provide a compelling case for this much-needed effort, with a focus on tangible benefits to the scientific and food security communities.

  20. Role of pseudo-turbulent stresses in shocked particle clouds and construction of surrogate models for closure

    Science.gov (United States)

    Sen, O.; Gaul, N. J.; Davis, S.; Choi, K. K.; Jacobs, G.; Udaykumar, H. S.

    2018-02-01

    Macroscale models of shock-particle interactions require closure terms for unresolved solid-fluid momentum and energy transfer. These comprise the effects of mean as well as fluctuating fluid-phase velocity fields in the particle cloud. Mean drag and Reynolds stress equivalent terms (also known as pseudo-turbulent terms) appear in the macroscale equations. Closure laws for the pseudo-turbulent terms are constructed in this work from ensembles of high-fidelity mesoscale simulations. The computations are performed over a wide range of Mach numbers (M) and particle volume fractions (φ ) and are used to explicitly compute the pseudo-turbulent stresses from the Favre average of the velocity fluctuations in the flow field. The computed stresses are then used as inputs to a Modified Bayesian Kriging method to generate surrogate models. The surrogates can be used as closure models for the pseudo-turbulent terms in macroscale computations of shock-particle interactions. It is found that the kinetic energy associated with the velocity fluctuations is comparable to that of the mean flow—especially for increasing M and φ . This work is a first attempt to quantify and evaluate the effect of velocity fluctuations for problems of shock-particle interactions.

  1. Hemorrhagic Shock-induced Endothelial Cell Activation in a Spontaneous Breathing and a Mechanical Ventilation Hemorrhagic Shock Model Is Induced by a Proinflammatory Response and Not by Hypoxia

    NARCIS (Netherlands)

    van Meurs, Matijs; Wulfert, Francis M.; Jongman, Rianne M.; Schipper, Martin; Houwertjes, Martin C.; Vaneker, Michiel; Scheffer, Gert Jan; Teppema, Luc J.; Aarts, Leon P. H. J.; Heeringa, Peter; Zijlstra, Jan G.; Molema, Grietje

    Introduction: The interaction between neutrophils and activated endothelium is essential for the development of multiple organ dysfunction in patients with hemorrhagic shock (HS). Mechanical ventilation frequently is used in patients with HS. The authors sought to investigate the consequences of

  2. Hemorrhagic shock-induced endothelial cell activation in a spontaneous breathing and a mechanical ventilation hemorrhagic shock model is induced by a proinflammatory response and not by hypoxia

    NARCIS (Netherlands)

    Meurs, M. van; Wulfert, F.M.; Jongman, R.M.; Schipper, M.; Houwertjes, M.C.; Vaneker, M.; Scheffer, G.J.; Teppema, L.J.; Aarts, L.P.; Heeringa, P.; Zijlstra, J.G.; Molema, G.

    2011-01-01

    INTRODUCTION: The interaction between neutrophils and activated endothelium is essential for the development of multiple organ dysfunction in patients with hemorrhagic shock (HS). Mechanical ventilation frequently is used in patients with HS. The authors sought to investigate the consequences of

  3. Two-phase pressurized thermal shock investigations using a 3D two-fluid modeling of stratified flow with condensation

    International Nuclear Information System (INIS)

    Yao, W.; Coste, P.; Bestion, D.; Boucker, M.

    2003-01-01

    In this paper, a local 3D two-fluid model for a turbulent stratified flow with/without condensation, which can be used to predict two-phase pressurized thermal shock, is presented. A modified turbulent K- model is proposed with turbulence production induced by interfacial friction. A model of interfacial friction based on a interfacial sublayer concept and three interfacial heat transfer models, namely, a model based on the small eddies controlled surface renewal concept (HDM, Hughes and Duffey, 1991), a model based on the asymptotic behavior of the Eddy Viscosity (EVM), and a model based on the Interfacial Sublayer concept (ISM) are implemented into a preliminary version of the NEPTUNE code based on the 3D module of the CATHARE code. As a first step to apply the above models to predict the two-phase thermal shock, the models are evaluated by comparison of calculated profiles with several experiments: a turbulent air-water stratified flow without interfacial heat transfer; a turbulent steam-water stratified flow with condensation; turbulence induced by the impact of a water jet in a water pool. The prediction results agree well with the experimental data. In addition, the comparison of three interfacial heat transfer models shows that EVM and ISM gave better prediction results while HDM highly overestimated the interfacial heat transfers compared to the experimental data of a steam water stratified flow

  4. Modeling internal ballistics of gas combustion guns.

    Science.gov (United States)

    Schorge, Volker; Grossjohann, Rico; Schönekess, Holger C; Herbst, Jörg; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

    2016-05-01

    Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur.

  5. CMAQ Involvement in Air Quality Model Evaluation International Initiative

    Science.gov (United States)

    Description of Air Quality Model Evaluation International Initiative (AQMEII). Different chemical transport models are applied by different groups over North America and Europe and evaluated against observations.

  6. Modern Gravity Models of Internal Migration. The Case of Romania

    Directory of Open Access Journals (Sweden)

    Daniela BUNEA

    2012-04-01

    Full Text Available Internal migration, although less investigated than international migration, is a key mechanism for adjustment to regional economic shocks, especially when other tools prove useless. But this process has very complex factors of determination which can be economic, social, demographic, environmental, etc. Based on previous international studies, in the case of Romania the robust variables proved to be the population size, the per capita gross domestic product, the road density, an amenity index and the crime rate from a static perspective, and the previous migration, the population size and the amenity index from a dynamic perspective. The techniques I have employed in making this study are the Least Square Dummy Variables (LSDV, or the fixed effects method and the Generalized Method of Moments (GMM, or the dynamic method both applied to panel data.

  7. Finnish exchange students' culture shock

    OpenAIRE

    Pekkala, Karoliina

    2015-01-01

    This bachelor’s thesis is written about culture shock experienced by the exchange students from Finland. It is commissioned by an international students exchange organisation located in Finland. The aim of the research was to find out how much the host country affects the culture shock and to identify aspects that affect the adaptation of the students. The goal is to provide the future exchange students with advise on coping with culture shock. Theoretical framework consists of defining w...

  8. ZMOTTO- MODELING THE INTERNAL COMBUSTION ENGINE

    Science.gov (United States)

    Zeleznik, F. J.

    1994-01-01

    The ZMOTTO program was developed to model mathematically a spark-ignited internal combustion engine. ZMOTTO is a large, general purpose program whose calculations can be established at five levels of sophistication. These five models range from an ideal cycle requiring only thermodynamic properties, to a very complex representation demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. ZMOTTO is a flexible and computationally economical program based on a system of ordinary differential equations for cylinder-averaged properties. The calculations assume that heat transfer is expressed in terms of a heat transfer coefficient and that the cylinder average of kinetic plus potential energies remains constant. During combustion, the pressures of burned and unburned gases are assumed equal and their heat transfer areas are assumed proportional to their respective mass fractions. Even the simplest ZMOTTO model provides for residual gas effects, spark advance, exhaust gas recirculation, supercharging, and throttling. In the more complex models, 1) finite rate chemistry replaces equilibrium chemistry in descriptions of both the flame and the burned gases, 2) poppet valve formulas represent fluid flow instead of a zero pressure drop flow, and 3) flame propagation is modeled by mass burning equations instead of as an instantaneous process. Input to ZMOTTO is determined by the model chosen. Thermodynamic data is required for all models. Transport properties and chemical kinetics data are required only as the model complexity grows. Other input includes engine geometry, working fluid composition, operating characteristics, and intake/exhaust data. ZMOTTO accommodates a broad spectrum of reactants. The program will calculate many Otto cycle performance parameters for a number of consecutive cycles (a cycle being an interval of 720 crankangle degrees). A typical case will have a number of initial ideal cycles and progress through levels

  9. On the high-temperature combustion of n-butanol: Shock tube data and an improved kinetic model

    KAUST Repository

    Vasu, Subith S.

    2013-11-21

    The combustion of n-butanol has received significant interest in recent years, because of its potential use in transportation applications. Researchers have extensively studied its combustion chemistry, using both experimental and theoretical methods; however, additional work is needed under specific conditions to improve our understanding of n-butanol combustion. In this study, we report new OH time-history data during the high-temperature oxidation of n-butanol behind reflected shock waves over the temperature range of 1300-1550 K and at pressures near 2 atm. These data were obtained at Stanford University, using narrow-line-width ring dye laser absorption of the R1(5) line of OH near 306.7 nm. Measured OH time histories were modeled using comprehensive n-butanol literature mechanisms. It was found that n-butanol unimolecular decomposition rate constants commonly used in chemical kinetic models, as well as those determined from theoretical studies, are unable to predict the data presented herein. Therefore, an improved high-temperature mechanism is presented here, which incorporates recently reported rate constants measured in a single pulse shock tube [C. M. Rosado-Reyes and W. Tsang, J. Phys. Chem. A 2012, 116, 9825-9831]. Discussions are presented on the validity of the proposed mechanism against other literature shock tube experiments. © 2013 American Chemical Society.

  10. A model of the factors affecting international postgraduate students’ pursuit of degrees: A case study

    Directory of Open Access Journals (Sweden)

    Desmond Wesley Govender

    2016-03-01

    Full Text Available The aim of this paper is to present a model of the factors affecting international students’ pursuit of their academic degrees in tertiary institutions. This was achieved by identifying factors that commonly affect international postgraduate students. This was a questionnaire based case study with a sample of 24 post-graduate international students from one university in KwaZulu-Natal. Questionnaires were analysed using SPSS (version 21.0 and WarpPLS (4.0. WarpPLS (4.0 was used to draw up a statistically based model regarding the factors affecting international students in pursuit of their academic degrees. Results from the model show that financial stress, accommodation challenges, cultural shock, loneliness/homesick, communication skills and evaluation of their (previous university experience affect students in their pursuit of their academic degrees in higher education. These findings could be used by students themselves to make them aware of possible challenges that lie ahead as well as by staff in international student offices at higher education institutions.

  11. sGC(alpha)1(beta)1 attenuates cardiac dysfunction and mortality in murine inflammatory shock models.

    Science.gov (United States)

    Buys, Emmanuel S; Cauwels, Anje; Raher, Michael J; Passeri, Jonathan J; Hobai, Ion; Cawley, Sharon M; Rauwerdink, Kristen M; Thibault, Helene; Sips, Patrick Y; Thoonen, Robrecht; Scherrer-Crosbie, Marielle; Ichinose, Fumito; Brouckaert, Peter; Bloch, Kenneth D

    2009-08-01

    Altered cGMP signaling has been implicated in myocardial depression, morbidity, and mortality associated with sepsis. Previous studies, using inhibitors of soluble guanylate cyclase (sGC), suggested that cGMP generated by sGC contributed to the cardiac dysfunction and mortality associated with sepsis. We used sGC(alpha)(1)-deficient (sGC(alpha)(1)(-/-)) mice to unequivocally determine the role of sGC(alpha)(1)beta(1) in the development of cardiac dysfunction and death associated with two models of inflammatory shock: endotoxin- and TNF-induced shock. At baseline, echocardiographic assessment and invasive hemodynamic measurements of left ventricular (LV) dimensions and function did not differ between wild-type (WT) mice and sGC(alpha)(1)(-/-) mice on the C57BL/6 background (sGC(alpha)(1)(-/-B6) mice). At 14 h after endotoxin challenge, cardiac dysfunction was more pronounced in sGC(alpha)(1)(-/-B6) than WT mice, as assessed using echocardiographic and hemodynamic indexes of LV function. Similarly, Ca(2+) handling and cell shortening were impaired to a greater extent in cardiomyocytes isolated from sGC(alpha)(1)(-/-B6) than WT mice after endotoxin challenge. Importantly, morbidity and mortality associated with inflammatory shock induced by endotoxin or TNF were increased in sGC(alpha)(1)(-/-B6) compared with WT mice. Together, these findings suggest that cGMP generated by sGC(alpha)(1)beta(1) protects against cardiac dysfunction and mortality in murine inflammatory shock models.

  12. Simple wealth distribution model causing inequality-induced crisis without external shocks

    Science.gov (United States)

    Benisty, Henri

    2017-05-01

    We address the issue of the dynamics of wealth accumulation and economic crisis triggered by extreme inequality, attempting to stick to most possibly intrinsic assumptions. Our general framework is that of pure or modified multiplicative processes, basically geometric Brownian motions. In contrast with the usual approach of injecting into such stochastic agent models either specific, idiosyncratic internal nonlinear interaction patterns or macroscopic disruptive features, we propose a dynamic inequality model where the attainment of a sizable fraction of the total wealth by very few agents induces a crisis regime with strong intermittency, the explicit coupling between the richest and the rest being a mere normalization mechanism, hence with minimal extrinsic assumptions. The model thus harnesses the recognized lack of ergodicity of geometric Brownian motions. It also provides a statistical intuition to the consequences of Thomas Piketty's recent "r >g " (return rate > growth rate) paradigmatic analysis of very-long-term wealth trends. We suggest that the "water-divide" of wealth flow may define effective classes, making an objective entry point to calibrate the model. Consistently, we check that a tax mechanism associated to a few percent relative bias on elementary daily transactions is able to slow or stop the build-up of large wealth. When extreme fluctuations are tamed down to a stationary regime with sizable but steadier inequalities, it should still offer opportunities to study the dynamics of crisis and the inner effective classes induced through external or internal factors.

  13. Arrival times of Flare/Halo CME associated shocks at the Earth: comparison of the predictions of three numerical models with these observations

    Directory of Open Access Journals (Sweden)

    S. M. P. McKenna-Lawlor

    Full Text Available The arrival times at L1 of eleven travelling shocks associated both with X-ray flaring and with halo CMEs recorded aboard SOHO/LASCO have been considered. Close to the Sun the velocities of these events were estimated using either Type II radio records or CME speeds. Close to the Earth the shocks were detected in the data of various solar wind plasma, interplanetary magnetic field (IMF and energetic particle experiments aboard SOHO, ACE, WIND, INTERBALL-1 and IMP-8. The real-time shock arrival predictions of three numerical models, namely the Shock Time of Arrival Model (STOA, the Interplanetary Shock Propagation Model (ISPM and the Hakamada-Akasofu-Fry Solar Wind Model (HAFv.2 were tested against these observations. This is the first time that energetic protons (tens of keV to a few MeV have been used to complement plasma and IMF data in validating shock propagation models. The models were all generally successful in predicting shock arrivals. STOA provided the smallest values of the "predicted minus measured" arrival times and displayed a typical predictive precision better than about 8 h. The ratio of the calculated standard deviation of the transit times to Earth to the standard deviation of the measurements was estimated for each model (treating interacting events as composite shocks and these ratios turned out to be 0.60, 1.15 and 1.02 for STOA, ISPM and HAFv.2, respectively. If an event in the sample for which the shock velocity was not well known is omitted from consideration, these ratios become 0.36, 0.76 and 0.81, respectively. Larger statistical samples should now be tested. The ratio of the in situ shock velocity and the "Sun to L1" transit velocity (Vsh /Vtr was in the range of 0.7–0.9 for individual, non-interacting, shock events. HAFv.2 uniquely provided information on those changes in the COBpoint (the moving Connection point on the shock along the IMF to the OBserver which directly influenced energetic

  14. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  15. Monitoring Microcirculatory Blood Flow with a New Sublingual Tonometer in a Porcine Model of Hemorrhagic Shock

    Directory of Open Access Journals (Sweden)

    Péter Palágyi

    2015-01-01

    Full Text Available Tissue capnometry may be suitable for the indirect evaluation of regional hypoperfusion. We tested the performance of a new sublingual capillary tonometer in experimental hemorrhage. Thirty-six anesthetized, ventilated mini pigs were divided into sham-operated (n=9 and shock groups (n=27. Hemorrhagic shock was induced by reducing mean arterial pressure (MAP to 40 mmHg for 60 min, after which fluid resuscitation started aiming to increase MAP to 75% of the baseline value (60–180 min. Sublingual carbon-dioxide partial pressure was measured by tonometry, using a specially coiled silicone rubber tube. Mucosal red blood cell velocity (RBCV and capillary perfusion rate (CPR were assessed by orthogonal polarization spectral (OPS imaging. In the 60 min shock phase a significant drop in cardiac index was accompanied by reduction in sublingual RBCV and CPR and significant increase in the sublingual mucosal-to-arterial PCO2 gap (PSLCO2 gap, which significantly improved during the 120 min resuscitation phase. There was significant correlation between PSLCO2 gap and sublingual RBCV (r=-0.65, p<0.0001, CPR (r=-0.64, p<0.0001, central venous oxygen saturation (r=-0.50, p<0.0001, and central venous-to-arterial PCO2 difference (r=0.62, p<0.0001. This new sublingual tonometer may be an appropriate tool for the indirect evaluation of circulatory changes in shock.

  16. Catastrophe modelling: deriving the 1-in-200 year mortality shock for ...

    African Journals Online (AJOL)

    This paper investigates catastrophe risk for South African life insurers by considering the additional deaths that could arise from a 1-in-200 year mortality shock. Existing South African academic research on catastrophic risk has mostly focused on property losses and the resulting impact on property insurance companies.

  17. The Significance of Splenectomy in Experimental Swine Models of Controlled Hemorrhagic Shock

    Science.gov (United States)

    2013-11-01

    Antonio, TX REFERENCES 1. Lehman E, Amole C. The function of the spleen in the retardation of shock from hemorrhage. Surgery . 1938;4:44 50. 2. Horton...stressful circum stances.4Because it requires laparotomy ,organ manipulation, vascular control and spleen removal, prehemorrhagic splenectomy consti tutes a

  18. Shocks in coupled socio-ecological systems: what are they and how can we model them?

    NARCIS (Netherlands)

    Filatova, Tatiana; Polhill, Gary; Seppelt, R.; Voinov, A.A.; Lange, S.; Bankamp, D.

    2012-01-01

    Coupled socio-ecological systems (SES) are complex systems characterized by self-organization, non-linearities, interactions among heterogeneous elements within each subsystem, and feedbacks across scales and among subsystems. When such a system experiences a shock or a crisis, the consequences are

  19. Testing and analysis of internal hardwood log defect prediction models

    Science.gov (United States)

    R. Edward. Thomas

    2011-01-01

    The severity and location of internal defects determine the quality and value of lumber sawn from hardwood logs. Models have been developed to predict the size and position of internal defects based on external defect indicator measurements. These models were shown to predict approximately 80% of all internal knots based on external knot indicators. However, the size...

  20. Shock Dynamics in Stellar Outbursts. I. Shock Formation

    Energy Technology Data Exchange (ETDEWEB)

    Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

    2017-05-20

    Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

  1. Toward An Internal Gravity Wave Spectrum In Global Ocean Models

    Science.gov (United States)

    2015-05-14

    Toward an internal gravity wave spectrum in global ocean models Malte Müller1,2, Brian K. Arbic3, James G. Richman4, Jay F. Shriver4, Eric L. Kunze5...fields and tides are beginning to display realistic internal gravity wave spectra, especially as model resolution increases. This paper examines...able to simulate the internal gravity wave spectrum and the extent to which nonlinear internal wave-wave interactions contribute to the simulated

  2. International Nuclear Model personal computer (PCINM): Model documentation

    International Nuclear Information System (INIS)

    1992-08-01

    The International Nuclear Model (INM) was developed to assist the Energy Information Administration (EIA), U.S. Department of Energy (DOE) in producing worldwide projections of electricity generation, fuel cycle requirements, capacities, and spent fuel discharges from commercial nuclear reactors. The original INM was developed, maintained, and operated on a mainframe computer system. In spring 1992, a streamlined version of INM was created for use on a microcomputer utilizing CLIPPER and PCSAS software. This new version is known as PCINM. This documentation is based on the new PCINM version. This document is designed to satisfy the requirements of several categories of users of the PCINM system including technical analysts, theoretical modelers, and industry observers. This document assumes the reader is familiar with the nuclear fuel cycle and each of its components. This model documentation contains four chapters and seven appendices. Chapter Two presents the model overview containing the PCINM structure and process flow, the areas for which projections are made, and input data and output reports. Chapter Three presents the model technical specifications showing all model equations, algorithms, and units of measure. Chapter Four presents an overview of all parameters, variables, and assumptions used in PCINM. The appendices present the following detailed information: variable and parameter listings, variable and equation cross reference tables, source code listings, file layouts, sample report outputs, and model run procedures. 2 figs

  3. Heart Rate Variability Analysis in an Experimental Model of Hemorrhagic Shock and Resuscitation in Pigs.

    Directory of Open Access Journals (Sweden)

    Edgard Salomão

    Full Text Available The analysis of heart rate variability (HRV has been shown as a promising non-invasive technique for assessing the cardiac autonomic modulation in trauma. The aim of this study was to evaluate HRV during hemorrhagic shock and fluid resuscitation, comparing to traditional hemodynamic and metabolic parameters.Twenty anesthetized and mechanically ventilated pigs were submitted to hemorrhagic shock (60% of estimated blood volume and evaluated for 60 minutes without fluid replacement. Surviving animals were treated with Ringer solution and evaluated for an additional period of 180 minutes. HRV metrics (time and frequency domain as well as hemodynamic and metabolic parameters were evaluated in survivors and non-survivors animals.Seven of the 20 animals died during hemorrhage and initial fluid resuscitation. All animals presented an increase in time-domain HRV measures during haemorrhage and fluid resuscitation restored baseline values. Although not significantly, normalized low-frequency and LF/HF ratio decreased during early stages of haemorrhage, recovering baseline values later during hemorrhagic shock, and increased after fluid resuscitation. Non-surviving animals presented significantly lower mean arterial pressure (43±7 vs 57±9 mmHg, P<0.05 and cardiac index (1.7±0.2 vs 2.6±0.5 L/min/m2, P<0.05, and higher levels of plasma lactate (7.2±2.4 vs 3.7±1.4 mmol/L, P<0.05, base excess (-6.8±3.3 vs -2.3±2.8 mmol/L, P<0.05 and potassium (5.3±0.6 vs 4.2±0.3 mmol/L, P<0.05 at 30 minutes after hemorrhagic shock compared with surviving animals.The HRV increased early during hemorrhage but none of the evaluated HRV metrics was able to discriminate survivors from non-survivors during hemorrhagic shock. Moreover, metabolic and hemodynamic variables were more reliable to reflect hemorrhagic shock severity than HRV metrics.

  4. Nitric oxide and liver microcirculation during autoregulation and haemorrhagic shock in rabbit model.

    Science.gov (United States)

    Lhuillier, F; Robert, M-O; Crova, P; Goudable, J; Arnal, F; Cespuglio, R; Annat, G; Viale, J-P

    2006-08-01

    Direct evidence of nitric oxide (NO) involvement in the regulation of hepatic microcirculation is not yet available under physiological conditions nor in haemorrhagic shock. A laser Doppler flowmetry was used to measure liver perfusion index and a specific NO-sensitive electrode was inserted into liver parenchyma of anaesthetized rabbits. Hepatic autoregulation during moderate hypovolaemia {mean arterial pressure at 50 mm Hg without liver perfusion alteration; blood withdrawal 17.7 (4.2) ml [mean (SD)]} or haemorrhagic shock [mean arterial pressure at 20 mm Hg associated with liver perfusion impairment and lactic acidosis; blood withdrawal 56.0 (6.8) ml] were investigated over 60 min and were followed by a rapid infusion of the shed blood. Involvement of NO synthases was evaluated using a non-specific inhibitor, NAPNA (Nomega-nitro-L-arginine P-nitro-anilide). In the autoregulation group, a decrease [30.0 (4.0) mm Hg] of mean arterial pressure did not alter liver perfusion index, whereas the liver NO concentration increased and reached a plateau [125 (10)%; compared with baseline; P<0.05]. This NO concentration was reduced to zero by the administration of NO synthase inhibitor. Haemorrhagic shock led to a rapid decrease in liver perfusion index [60 (7)%; compared with baseline; P<0.05] before an immediate and continuous increase in NO concentration [250 (50)%; compared with baseline; P<0.05]. Infusion of NO inhibitor before haemorrhagic shock reduced the NO concentration to zero and hepatic perfusion by 60 (8)% (P<0.05) of the baseline. Mean arterial pressure increased simultaneously. In these animals, during haemorrhage, a continuous increase in NO concentration still occurred and liver perfusion slightly increased. In all groups but NAPNA+haemorrhagic shock, blood replacement induced recovery of baseline values. NO plays a physiological role in the liver microcirculation during autoregulation. Its production is enzyme-dependent. Conversely, haemorrhagic shock

  5. A Model Program for International Commerce Education.

    Science.gov (United States)

    Funston, Richard

    To address the economy's growing reliance on international business, San Diego State University has recently introduced a program in international commerce. The program was developed by packaging coursework in three existing areas: business administration, language training, and area studies. Although still in its infancy, the international…

  6. SHOCK WAVE IN IONOSPHERE DURING EARTHQUAKE

    Directory of Open Access Journals (Sweden)

    V.V. Kuznetsov

    2016-11-01

    Full Text Available Fundamentally new model of the shock wave (SW generation in atmosphere and ionosphere during earthquake is proposed. The model proceeds from the idea of cooperative shock water crystallization in a cloud

  7. Primary Blast Injury Criteria for Animal/Human TBI Models using Field Validated Shock Tubes

    Science.gov (United States)

    2016-09-01

    exposure to shock wave. We used experimental measures to probe the response of the body to blast loading via implantation of intracranial pressure (ICP...Representative pressure profiles measured by incident ( loading ), intracranial and carotid artery sensors (response) implanted in a rat exposed to 130 kPa...if these changes can be used as convenient markers of injury which can be used in the field and inform affected personnel immediately upon the

  8. demystifying the shock of shocking

    African Journals Online (AJOL)

    demystifying the shock of shocking. Beyra Rossouw, MB ChB, MMed. (Paed), DTM, MSc (Sports Medicine),. Certificate Critical Care (Paed). Senior Registrar Paediatric Cardiology, Western. Cape Paediatric Cardiac Services, Red Cross. War Memorial Children's Hospital, University of. Cape Town, and Tygerberg Children's ...

  9. Nosography of systemic inflammatory response syndrome, sepsis, severe sepsis, septic shock, and multiple organ dysfunction syndrome in internal medicine patients

    Directory of Open Access Journals (Sweden)

    Silvia Spoto

    2015-09-01

    Full Text Available Sepsis is defined by the presence of at least two systemic inflammatory response syndrome criteria associated with an infection microbiologically or clinically evidenced. In Italy sepsis is responsible for 80,000 hospital admissions per year and, in the last decades, severe sepsis and septic shock cases are increasing, in correlation with the increased prevalence of multi-drugresistant microbial strains. The predominant etiologic agents are Gram-positive and Gram-negative bacteria, but sepsis caused by fungi is increasing. The host response with both inflammatory and anti-inflammatory processes is responsible for organic failures, which complicate the syndrome, and for the susceptibility to secondary infections. The impairment of one or more organs or systems may be the onset clinical presentation. The organ dysfunctions complicating sepsis involve mainly cardiorespiratory system, kidneys, hemostatis and central nervous system. Fever or hypothermia, tachycardia, tachypnea, leukocytosis or leukopenia, elevated blood levels of lactate and procalcitonin, hypotension are diagnostically sensitive findings for sepsis. Definitive diagnosis requires isolation of the pathogen from blood sample or from the focus of infection. Therapeutic success against sepsis depends on the appropriate use of antibiotics, on the treatment of hemodynamic and respiratory disorder and on general supportive care. In some cases the use of activated protein C is to take in consideration.

  10. The international radioactive transportation regulations: A model for national regulations

    International Nuclear Information System (INIS)

    Pope, R.B.; Rawl, R.R.

    1990-06-01

    The International Atomic Energy Agency's (IAEA) Regulations for the Safe Transport of Radioactive Material, Safety Series No. 6 (herein after denoted as the ''International Regulations'') serve as the model for the regulations for individual countries and international modal organizations controlling the packaging and transportation of radioactive materials. The purpose of this paper is to outline the background and history of the International Regulations, the general principles behind the requirements of the International Regulations, the structure and general contents of the latest edition of the International Regulations, and the roles of various international bodies in the development and implementation of the International Regulations and the current status of regulatory and supportive document development at both the international and domestic level. This review will provide a basis for users and potential users to better understand the source and application of the International Regulations. 1 tab

  11. Chemically modified tetracycline prevents the development of septic shock and acute respiratory distress syndrome in a clinically applicable porcine model.

    Science.gov (United States)

    Steinberg, Jay; Halter, Jeffrey; Schiller, Henry; Gatto, Louis; Carney, David; Lee, Hsi-Ming; Golub, Lorne; Nieman, Gary

    2005-10-01

    Sepsis causes more than with 215,000 deaths per year in the United States alone. Death can be caused by multiple system organ failure, with the lung, in the form of the acute respiratory distress syndrome (ARDS), often being the first organ to fail. We developed a chronic porcine model of septic shock and ARDS and hypothesized that blocking the proteases neutrophil elastase (NE) and matrix metalloproteinases (MMP-2 and MMP-9) with the modified tetracycline, COL-3, would significantly improve morbidity in this model. Pigs were anesthetized and instrumented for hemodynamic monitoring and were then randomized to one of three groups: control (n = 3), laparotomy only; superior mesenteric artery occlusion (SMA) + fecal blood clot (FC; n = 7), with intraperitoneal placement of a FC; and SMA + FC + COL (n = 5), ingestion of COL-3 12 h before injury. Animals emerged from anesthesia and were monitored and treated with fluids and antibiotics in an animal intensive care unit continuously for 48 h. Serum and bronchoalveolar lavage fluid (BALF) were sampled and bacterial cultures, MMP-2, MMP-9, NE, and multiple cytokine concentrations were measured. Pigs were reanesthetized and placed on a ventilator when significant lung impairment occurred (PaO2/FiO2 < 250). At necropsy, lung water and histology were assessed. All animals in the SMA + FC group developed septic shock evidenced by a significant fall in arterial blood pressure that was not responsive to fluids. Lung injury typical of ARDS (i.e., a fall in lung compliance and PaO2/FiO2 ratio and a significant increase in lung water) developed in this group. Additionally, there was a significant increase in plasma IL-1 and IL-6 and in BALF IL-6, IL-8, IL-10, NE, and protein concentration in the SMA + FC group. COL-3 treatment prevented septic shock and ARDS and significantly decreased cytokine levels in plasma and BALF. COL-3 treatment also significantly reduced NE activity (P < 0.05) and reduced MMP-2 and MMP-9 activity in BALF by

  12. SME International Business Models: The Role of Context and Experience

    DEFF Research Database (Denmark)

    Child, John; Hsieh, Linda; Elbanna, Said

    2017-01-01

    This paper addresses two questions through a study of 180 SMEs located in contrasting industry and home country contexts. First, which business models for international markets prevail among SMEs and do they configure into different types? Second, which factors predict the international business...... models that SMEs follow? Three distinct international business models (traditional market-adaptive, technology exploiter, and ambidextrous explorer) are found among the SMEs studied. The likelihood of SMEs adopting one business model rather than another is to a high degree predictable with reference...... to a small set of factors: industry, level of home economy development, and decision-maker international experience....

  13. The structure of steady shock waves in porous metals

    Science.gov (United States)

    Czarnota, Christophe; Molinari, Alain; Mercier, Sébastien

    2017-10-01

    The paper aims at developing an understanding of steady shock wave propagation in a ductile metallic material containing voids. Porosity is assumed to be less than 0.3 and voids are not connected (foams are not considered). As the shock wave is traveling in the porous medium, the voids are facing a rapid collapse. During this dynamic compaction process, material particles are subjected to very high acceleration in the vicinity of voids, thus generating acceleration forces at the microscale that influence the overall response of the porous material. Analyzing how stationary shocks are influenced by these micro-inertia effects is the main goal of this work. The focus is essentially on the shock structure, ignoring oscillatory motion of pores prevailing at the tail of the shock wave. Following the constitutive framework developed by Molinari and Ravichandran (2004) for the analysis of steady shock waves in dense metals, an analytical approach of steady state propagation of plastic shocks in porous metals is proposed. The initial void size appears as a characteristic internal length that scales the overall dynamic response, thereby contributing to the structuring of the shock front. This key feature is not captured by standard damage models where the porosity stands for the single damage parameter with no contribution of the void size. The results obtained in this work provide a new insight in the fundamental understanding of shock waves in porous media. In particular, a new scaling law relating the shock width to the initial void radius is obtained when micro-inertia effects are significant.

  14. Numerical prediction of shock induced oscillations over a 2D airfoil: Influence of turbulence modelling and test section walls

    International Nuclear Information System (INIS)

    Thiery, Mylene; Coustols, Eric

    2006-01-01

    The present study deals with recent numerical results from on-going research conducted at ONERA/DMAE regarding the prediction of transonic flows, for which shock wave/boundary layer interaction is important. When this interaction is strong enough (M ≥ 1.3), shock induced oscillations (SIO) appear at the suction side of the airfoil and lead to the formation of unsteady separated areas. The main issue is then to perform unsteady computations applying appropriate turbulence modelling and relevant boundary conditions with respect to the test case. Computations were performed with the ONERA elsA software and the URANS-type approach, closure relationships being achieved from transport-equation models. Applications are provided for the OAT15A airfoil data base, well documented for unsteady CFD validation (mean and r.m.s. pressure, phase-averaged LDA data, ...). In this paper, the capabilities of turbulence models are evaluated with two 2D URANS strategies, under free-stream or confined conditions. The latter takes into account the adaptive upper and lower wind-tunnel walls. A complete 3D URANS simulation was then performed to demonstrate the real impact of all lateral wind-tunnel walls on such a flow

  15. From qualitative data to quantitative models: analysis of the phage shock protein stress response in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Jovanovic Goran

    2011-05-01

    Full Text Available Abstract Background Bacteria have evolved a rich set of mechanisms for sensing and adapting to adverse conditions in their environment. These are crucial for their survival, which requires them to react to extracellular stresses such as heat shock, ethanol treatment or phage infection. Here we focus on studying the phage shock protein (Psp stress response in Escherichia coli induced by a phage infection or other damage to the bacterial membrane. This system has not yet been theoretically modelled or analysed in silico. Results We develop a model of the Psp response system, and illustrate how such models can be constructed and analyzed in light of available sparse and qualitative information in order to generate novel biological hypotheses about their dynamical behaviour. We analyze this model using tools from Petri-net theory and study its dynamical range that is consistent with currently available knowledge by conditioning model parameters on the available data in an approximate Bayesian computation (ABC framework. Within this ABC approach we analyze stochastic and deterministic dynamics. This analysis allows us to identify different types of behaviour and these mechanistic insights can in turn be used to design new, more detailed and time-resolved experiments. Conclusions We have developed the first mechanistic model of the Psp response in E. coli. This model allows us to predict the possible qualitative stochastic and deterministic dynamic behaviours of key molecular players in the stress response. Our inferential approach can be applied to stress response and signalling systems more generally: in the ABC framework we can condition mathematical models on qualitative data in order to delimit e.g. parameter ranges or the qualitative system dynamics in light of available end-point or qualitative information.

  16. Cardiogenic shock

    Science.gov (United States)

    ... occur during or after a heart attack (myocardial infarction). These complications include: A large section of heart ... high blood pressure, high cholesterol and triglycerides, or tobacco use Alternative Names Shock - cardiogenic Images Heart, section ...

  17. Shock absorber

    International Nuclear Information System (INIS)

    Housman, J.J.

    1978-01-01

    A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

  18. Dynamic fragmentation of laser shock-melted tin: experiment and modelling

    Energy Technology Data Exchange (ETDEWEB)

    De Resseguier, T. [CNRS ENSMA, Lab Combust and Deton, F-86961 Futuroscope (France); Signor, L.; Dragon, A. [CNRS ENSMA, Mecan and Phys Mat Lab, F-86961 Futuroscope (France); Signor, L.; Roy, G. [CEA Valduc, 21 - Is-sur-Tille (France)

    2010-07-01

    Dynamic fragmentation of shock-loaded metals is an issue of considerable importance for both basic science and a variety of technological applications, such as pyrotechnics or inertial confinement fusion, the latter involving high energy laser irradiation of thin metallic shells. Whereas spall fracture in solid materials has been extensively studied for many years, little data can be found yet about the evolution of this phenomenon after partial or full melting on compression or on release. Here, we present an investigation of dynamic fragmentation in laser shock-melted tin, from the 'micro-spall' process (ejection of a cloud of fine droplets) occurring upon reflection of the compressive pulse from the target free surface, to the late rupture observed in the un-spalled melted layer (leading to the formation of larger spherical fragments). Experimental results consist of time-resolved velocity measurements and post-shock observations of recovered targets and fragments. They provide original information regarding the loss of tensile strength associated with melting, the cavitation mechanism likely to occur in the melted metal, the sizes of the subsequent fragments and their ejection velocities. A theoretical description based on an energetic approach adapted to the case of a liquid metal is implemented as a failure criterion in a one-dimensional hydro-code including a multi-phase equation of state for tin. The resulting predictions of the micro-spall process are compared with experimental data. In particular, the use of a new experimental technique to quantify the fragment size distributions leads to a much better agreement with theory than previously reported. Finally, a complementary approach focused on cavitation is proposed to evaluate the role of this phenomenon in the fragmentation of the melted metal. (authors)

  19. Accuracy Analysis of DSMC Chemistry Models Applied to a Normal Shock Wave

    Science.gov (United States)

    2012-06-20

    to note that even though a two-dimensional setup is used instead of a one-dimensional solution with exact Rankine-Hugoniot conditions for M=9.3, the...mode temperatures after the shock for a plateau at a value of about 4,400 K, which agrees with the Rankine-Hugoniot solutions for a variable specific...used, with underpopulated low (except for the ground state) and overpopulated high vibrational levels. The main reason for such a non-equilibrium is

  20. An Approximate Analytical Model of Shock Waves from Underground Nuclear Explosions

    Science.gov (United States)

    1990-12-01

    of the official yields. 14, SUBJECT TERMS 15 NUMBER OF PAGES iilr’sh41old JI Vs B/lIT1 rt t , lirodvinam it methiods, ’-hock waves, 74 1111(1 rl ~I...shock wave methods, to appear in Explosion Source Pheno neiolgy, S. R. Taylor, P. G. Richards, and H. J. Patton , eds., American Geophysical Union...Fig. A6 62 DISTR I TON ,1 1ST Proo. ’i ifl as Ahrcns Dr. T.J. BennettSe-inotogical Lab, 252-21 S-CUBF.D Division of Geological & Planetary Sciences A

  1. Hemorrhagic shock-induced endothelial cell activation in a spontaneous breathing and a mechanical ventilation hemorrhagic shock model is induced by a proinflammatory response and not by hypoxia.

    Science.gov (United States)

    van Meurs, Matijs; Wulfert, Francis M; Jongman, Rianne M; Schipper, Martin; Houwertjes, Martin C; Vaneker, Michiel; Scheffer, Gert Jan; Teppema, Luc J; Aarts, Leon P H J; Heeringa, Peter; Zijlstra, Jan G; Molema, Grietje

    2011-09-01

    The interaction between neutrophils and activated endothelium is essential for the development of multiple organ dysfunction in patients with hemorrhagic shock (HS). Mechanical ventilation frequently is used in patients with HS. The authors sought to investigate the consequences of mechanical ventilation of mice subjected to HS on microvascular endothelial activation in the lung and kidney. Anesthetized wild type C57BL/6 male mice were subjected to controlled hemorrhage; subgroups of mice were mechanically ventilated during the HS insult. To study the effect of acute hypoxia on the mice, the animals were housed in hypoxic cages. Gene expression levels was assessed by quantitative real-time polymerase chain reaction. Protein expression was assessed by immunohistochemistry and enzyme-linked immunosorbent assay. Ninety minutes after the shock induction, a vascular bed-specific, heterogeneous proinflammatory endothelial activation represented by E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 expression was seen in kidney and lung. No differences in adhesion molecules between the spontaneously breathing and mechanically ventilated mice were found. Concentrations of the proinflammatory cytokines chemokine (C-X-C motif) ligand 1 (11.0-fold) and interleukin-6 (21.7-fold) were increased after 90 min of HS. Two hours of 6% oxygen did not induce the expression of E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 in the kidneys and the lung. Hemorrhagic shock leads to an early and reversible proinflammatory endothelial activation in kidney and lung. HS-induced endothelial activation is not changed by mechanical ventilation during the shock phase. Hypoxia alone does not lead to endothelial activation. The observed proinflammatory endothelial activation is mostly ischemia- or reperfusion-dependent and not related to hypoxia.

  2. A prediction model for two-dimensional pressure distribution from underwater shock wave focusing by an ellipsoidal reflector.

    Science.gov (United States)

    Liu, Lei; Guo, Rui; Chen, Liang; Cao, Yu; Yang, Yongliang; Zhao, Bobo

    2016-12-01

    Underwater shock wave focusing by ellipsoidal reflector is an important method for medical treatment, detection, and acoustic warfare. However, its pressure field is difficult to predict due to complicated physics. In this study, the pressure by focusing is modeled based on theories of shock wave propagation, nonlinear reflection, and nonlinear focusing, and the calculation domain is determined by approximate equations of wave fronts and lines. The pressure field during the whole process is described by combining direct and focusing pressures in the time and space domains. On this basis, the focusing behavior is simulated, and obtained pressure profiles are compared with experimental results, and the influence of reflector length on focusing performance is also discussed. The results indicate that although there are some rough assumptions, this model can simulate the underwater focusing in some detail and does a good job of predicting the pressure distribution, especially for the positive peak pressure, with an error below 10%; as the reflector length increases, the dynamic focus tends to move linearly forward to the other geometric focus, and the pressure gain increases continuously but the growth rate decreases.

  3. Enhancing the Action Research Capacity of the International Model ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    The International Model Forest Network (IMFN) dates from a commitment made by Canada at the UNCED (United Nations Conference on Environment and Development) Rio Conference in 1992 to create an international network of working models of sustainable forest management that are based on local-level ...

  4. The linkage between oil price shocks and economic growth with inflation in the presence of technological advances: a CGE model

    International Nuclear Information System (INIS)

    Doroodian, K.; Boyd, R.

    2003-01-01

    This study examines whether oil price shocks are inflationary in the US. We increase the price of oil in the year 2000 in a manner consistent with the oil price shock of 1973-74 and let the economy experience a Hicksian technological change. Then using a dynamic computable general equilibrium (CGE) model, we conduct our analyses under two separate cases: (1) regular economic growth, and (2) low economic growth. We also run three technological scenarios: (1) no technology change, (2) technological advances in the manufacturing and refining sectors, and (3) technological advances in the manufacturing, refining, chemical, and service sectors. The effects of these changes are analyzed over the next 20 years until the year 2020. Our results suggest that while a shock of the magnitude experienced in the 1970s will have a fairly severe effect on such things as gasoline and refinery prices, the aggregate price changes will be largely dissipated over time at the aggregate level. Furthermore, the aggregate level of prices (CPI and PPI) will fall over time as the level of technological advances rise under both growth scenarios. There are several reasons why we would obtain such results. First of all, the structure of the US economy has changed remarkably since the early 1970s. Rather than being a manufacturing based economy, the US is largely a service based economy today and hence it is more protected from raw materials shortages. Second, the economy has had a steady history of strong growth and the faster an economy grows the quicker disruptions to that economy are dissipated. Finally, our economy is experiencing rapid technological advances in information systems which have served to reduce costs and maintain output in a wide number of economic sectors.(author)

  5. The linkage between oil price shocks and economic growth with inflation in the presence of technological advances: a CGE model

    International Nuclear Information System (INIS)

    Doroodian, K.; Boyd, Roy

    2003-01-01

    This study examines whether oil price shocks are inflationary in the US. We increase the price of oil in the year 2000 in a manner consistent with the oil price shock of 1973-74 and let the economy experience a Hicksian technological change. Then using a dynamic computable general equilibrium (CGE) model, we conduct our analyses under two separate cases: (1) regular economic growth, and (2) low economic growth. We also run three technological scenarios: (1) no technology change, (2) technological advances in the manufacturing and refining sectors, and (3) technological advances in the manufacturing, refining, chemical, and service sectors. The effects of these changes are analyzed over the next 20 years until the year 2020. Our results suggest that while a shock of the magnitude experienced in the 1970s will have a fairly severe effect on such things as gasoline and refinery prices, the aggregate price changes will be largely dissipated over time at the aggregate level. Furthermore, the aggregate level of prices (CPI and PPI) will fall over time as the level of technological advances rise under both growth scenarios. There are several reasons why we would obtain such results. First of all, the structure of the US economy has changed remarkably since the early 1970s. Rather than being a manufacturing based economy, the US is largely a service based economy today and hence it is more protected form raw materials shortages. Second, the economy has had a steady history of strong growth and the faster an economy grows the quicker disruptions to that economy are dissipated. Finally, our economy is experiencing rapid technological advances in information systems which have served to reduce costs and maintain output in a wide number of economic sectors

  6. Identification and modeling of internal waves

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.; Sadhuram, Y.; Rao, M.M.M.; SujithKumar, S.; Maneesha, K.; Sandhya, K.S.; Prakash, S.S.; Chandramouli, P.; Murthy, K.S.R.

    ) and Bhimili (17°35.486’N, 83°42.322’E) at sonic depth 100 m during different seasons using time series CTD (hourly), current meter and indigenously developed thermister chain (at an interval of 2 minutes) to study the Internal Wave (IW) characteristics. Sound...

  7. THE EFFECTS OF FENOLDOPAM ON RENAL FUNCTION AND METABOLISM IN AN OVINE MODEL OF SEPTIC SHOCK.

    Science.gov (United States)

    Post, Emiel Hendrik; Su, Fuhong; Taccone, Fabio Silvio; Hosokawa, Koji; Herpain, Antoine; Creteur, Jacques; Vincent, Jean-Louis; De Backer, Daniel

    2016-04-01

    The importance of renal perfusion and metabolism in septic acute kidney injury (AKI) remains unclear. Prophylactic administration of the dopaminergic agent, fenoldopam, has been suggested to reduce the occurrence of AKI, but its effects in septic shock are poorly defined. Sepsis was induced in 15 adult female sheep by injecting autologous feces into the abdominal cavity. Two hours later, the animals were randomized to one of three groups: low-dose fenoldopam (1.0 μg/kg/min, n = 5), high-dose fenoldopam (5.0 μg/kg/min, n = 5), or placebo (control, n = 5). A perivascular flow probe was placed around the renal artery and a catheter in the renal vein for measurement of renal blood flow index (RBFI) and oxygen consumption (VO2renI). Metabolism in the renal cortex was evaluated using microdialysis. Serum creatinine was measured 6-hourly and the sublingual microcirculation assessed using sidestream dark-field videomicroscopy. High-dose fenoldopam was associated with a lower RBFI at 18 h (P = 0.032) than in the control group, but VO2renI was maintained by a higher oxygen extraction (P septic shock, fenoldopam did not improve renal blood flow, worsened microcirculatory alterations, and induced metabolic changes that were indicative of increased glycolysis.

  8. The Synchrotron Shock Model Confronts a "Line of Death" in the BATSE Gamma-Ray Burst Data

    Science.gov (United States)

    Preece, Robert D.; Briggs, Michael S.; Mallozzi, Robert S.; Pendleton, Geoffrey N.; Paciesas, W. S.; Band, David L.

    1998-01-01

    The synchrotron shock model (SSM) for gamma-ray burst emission makes a testable prediction: that the observed low-energy power-law photon number spectral index cannot exceed -2/3 (where the photon model is defined with a positive index: $dN/dE \\propto E{alpha}$). We have collected time-resolved spectral fit parameters for over 100 bright bursts observed by the Burst And Transient Source Experiment on board the {\\it Compton Gamma Ray Observatory}. Using this database, we find 23 bursts in which the spectral index limit of the SSM is violated, We discuss elements of the analysis methodology that affect the robustness of this result, as well as some of the escape hatches left for the SSM by theory.

  9. Cathelicidin peptide sheep myeloid antimicrobial peptide-29 prevents endotoxin-induced mortality in rat models of septic shock.

    Science.gov (United States)

    Giacometti, Andrea; Cirioni, Oscar; Ghiselli, Roberto; Mocchegiani, Federico; D'Amato, Giuseppina; Circo, Raffaella; Orlando, Fiorenza; Skerlavaj, Barbara; Silvestri, Carmela; Saba, Vittorio; Zanetti, Margherita; Scalise, Giorgio

    2004-01-15

    The present study was designed to investigate the antiendotoxin activity and therapeutic efficacy of sheep myeloid antimicrobial peptide (SMAP)-29, a cathelicidin-derived peptide. The in vitro ability of SMAP-29 to bind LPS from Escherichia coli 0111:B4 was determined using a sensitive limulus chromogenic assay. Two rat models of septic shock were performed: (1) rats were injected intraperitoneally with 1 mg E. coli 0111:B4 LPS and (2) intraabdominal sepsis was induced via cecal ligation and single puncture. All animals were randomized to receive parenterally isotonic sodium chloride solution, 1 mg/kg SMAP-29, 1 mg/kg polymyxin B or 20 mg/kg imipenem. The main outcome measures were: abdominal exudate and plasma bacterial growth, plasma endotoxin and tumor necrosis factor-alpha concentrations, and lethality. The in vitro study showed that SMAP-29 completely inhibited the LPS procoagulant activity at approximately 10 microM peptide concentration. The in vivo experiments showed that all compounds reduced the lethality when compared with control animals. SMAP-29 achieved a substantial decrease in endotoxin and tumor necrosis factor-alpha plasma concentrations when compared with imipenem and saline treatment and exhibited a slightly lower antimicrobial activity than imipenem. No statistically significant differences were noted between SMAP-29 and polymyxin B. SMAP-29, because of its double antiendotoxin and antimicrobial activities, could be an interesting compound for septic shock treatment.

  10. Computational Model for Internal Relative Humidity Distributions in Concrete

    Directory of Open Access Journals (Sweden)

    Wondwosen Ali

    2014-01-01

    Full Text Available A computational model is developed for predicting nonuniform internal relative humidity distribution in concrete. Internal relative humidity distribution is known to have a direct effect on the nonuniform drying shrinkage strains. These nonuniform drying shrinkage strains result in the buildup of internal stresses, which may lead to cracking of concrete. This may be particularly true at early ages of concrete since the concrete is relatively weak while the difference in internal relative humidity is probably high. The results obtained from this model can be used by structural and construction engineers to predict critical drying shrinkage stresses induced due to differential internal humidity distribution. The model uses finite elment-finite difference numerical methods. The finite element is used to space discretization while the finite difference is used to obtain transient solutions of the model. The numerical formulations are then programmed in Matlab. The numerical results were compared with experimental results found in the literature and demonstrated very good agreement.

  11. Anti-inflammatory effect of a Nuphar lutea partially purified leaf extract in murine models of septic shock.

    Science.gov (United States)

    Ozer, J; Levi, T; Golan-Goldhirsh, A; Gopas, J

    2015-02-23

    Various plant organs of Nuphar lutea (L.) SM. (Nymphaeaceae) are used in traditional medicine for the treatment of arthritis, fever, aches, pains and inflammation. The main purpose of this study was to determine the anti-inflammatory effect of Nuphar lutea leaf extract (NUP) in two septic shock models: (1) Survival of mice challenged with a lethal dose of LPS, determination of pro-inflammatory and anti-inflammatory cytokines in serum, as well as in peritoneal macrophages in cell culture. (2) The effect of NUP in a murine model of fecal-induced peritonitis. NUP pre-treatment partially protected mice in two models of acute septic shock. We concluded that NUP is anti-inflammatory by inhibiting the NF-κB pathway, modulating cytokine production and ERK phosphorylation. A significant average survival rate (60%) of LPS lethally-challenged mice was achieved by pre-treatment with NUP. In addition, NUP pre-treatment reduced nuclear NF-κB translocation in peritoneal macrophages. The production of pro-inflammatory cytokines, TNF-α, IL-6 and IL-12, in the sera of LPS-treated mice or in the supernatants of peritoneal macrophages stimulated with LPS for 2-6 h was also decreased by NUP. Pre-treatment with NUP caused a significant increase in the anti-inflammatory cytokine IL-10. The NUP pre-treatment reduced and delayed mortality in mice with fecal-induced peritonitis. Our studies also revealed that NUP pre-treatment induced a dose-dependent phosphorylation of ERK in peritoneal macrophages. Since most of the reports about the anti-inflammatory effect of Nuphar lutea refer to rhizome and root powder and extracts, it is important to clarify the effectiveness of leaf extract as a source for such activity. NUP pre-treatment partially protected mice in two models of acute septic shock. We concluded that NUP is anti-inflammatory by inhibiting the NF-κB pathway, modulating cytokine production and ERK phosphorylation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  12. A stock-flow consistent input-output model with applications to energy price shocks, interest rates, and heat emissions

    Science.gov (United States)

    Berg, Matthew; Hartley, Brian; Richters, Oliver

    2015-01-01

    By synthesizing stock-flow consistent models, input-output models, and aspects of ecological macroeconomics, a method is developed to simultaneously model monetary flows through the financial system, flows of produced goods and services through the real economy, and flows of physical materials through the natural environment. This paper highlights the linkages between the physical environment and the economic system by emphasizing the role of the energy industry. A conceptual model is developed in general form with an arbitrary number of sectors, while emphasizing connections with the agent-based, econophysics, and complexity economics literature. First, we use the model to challenge claims that 0% interest rates are a necessary condition for a stationary economy and conduct a stability analysis within the parameter space of interest rates and consumption parameters of an economy in stock-flow equilibrium. Second, we analyze the role of energy price shocks in contributing to recessions, incorporating several propagation and amplification mechanisms. Third, implied heat emissions from energy conversion and the effect of anthropogenic heat flux on climate change are considered in light of a minimal single-layer atmosphere climate model, although the model is only implicitly, not explicitly, linked to the economic model.

  13. Spectral fitting, shock layer modeling, and production of nitrogen oxides and excited nitrogen

    Science.gov (United States)

    Blackwell, H. E.

    1991-01-01

    An analysis was made of N2 emission from 8.72 MJ/kg shock layer at 2.54, 1.91, and 1.27 cm positions and vibrational state distributions, temperatures, and relative electronic state populations was obtained from data sets. Other recorded arc jet N2 and air spectral data were reviewed and NO emission characteristics were studied. A review of operational procedures of the DSMC code was made. Information on other appropriate codes and modifications, including ionization, were made as well as a determination of the applicability of codes reviewed to task requirement. A review was also made of computational procedures used in CFD codes of Li and other codes on JSC computers. An analysis was made of problems associated with integration of specific chemical kinetics applicable to task into CFD codes.

  14. Study Design of the Microcirculatory Shock Occurrence in Acutely Ill Patients (microSOAP: an International Multicenter Observational Study of Sublingual Microcirculatory Alterations in Intensive Care Patients

    Directory of Open Access Journals (Sweden)

    Namkje A. R. Vellinga

    2012-01-01

    Full Text Available Objective. Sublingual microcirculatory alterations are associated with an adverse prognosis in several critical illness subgroups. Up to now, single-center studies have reported on sublingual microcirculatory alterations in ICU patient subgroups, but an extensive evaluation of the prevalence of these alterations is lacking. We present the study design of an international multicenter observational study to investigate the prevalence of microcirculatory alterations in critically ill: the Microcirculatory Shock Occurrence in Acutely ill Patients (microSOAP. Methods. 36 ICU’s worldwide have participated in this study aiming for inclusion of over 500 evaluable patients. To enable communication and data collection, a website, an Open Clinica 3.0 database, and image uploading software have been designed. A one-session assessment of the sublingual microcirculation using Sidestream Dark Field imaging and data collection on patient characteristics has been performed in every ICU patient >18 years, regardless of underlying disease. Statistical analysis will provide insight in the prevalence and severity of sublingual alterations, its relation to systemic hemodynamic variables, disease, therapy, and outcome. Conclusion. This study will be the largest microcirculation study ever performed. It is expected that this study will also establish a basis for future studies related to the microcirculation in critically ill.

  15. Study Design of the Microcirculatory Shock Occurrence in Acutely Ill Patients (microSOAP): an International Multicenter Observational Study of Sublingual Microcirculatory Alterations in Intensive Care Patients

    Science.gov (United States)

    Vellinga, Namkje A. R.; Boerma, E. Christiaan; Koopmans, Matty; Donati, Abele; Dubin, Arnaldo; Shapiro, Nathan I.; Pearse, Rupert M.; Bakker, Jan; Ince, Can

    2012-01-01

    Objective. Sublingual microcirculatory alterations are associated with an adverse prognosis in several critical illness subgroups. Up to now, single-center studies have reported on sublingual microcirculatory alterations in ICU patient subgroups, but an extensive evaluation of the prevalence of these alterations is lacking. We present the study design of an international multicenter observational study to investigate the prevalence of microcirculatory alterations in critically ill: the Microcirculatory Shock Occurrence in Acutely ill Patients (microSOAP). Methods. 36 ICU's worldwide have participated in this study aiming for inclusion of over 500 evaluable patients. To enable communication and data collection, a website, an Open Clinica 3.0 database, and image uploading software have been designed. A one-session assessment of the sublingual microcirculation using Sidestream Dark Field imaging and data collection on patient characteristics has been performed in every ICU patient >18 years, regardless of underlying disease. Statistical analysis will provide insight in the prevalence and severity of sublingual alterations, its relation to systemic hemodynamic variables, disease, therapy, and outcome. Conclusion. This study will be the largest microcirculation study ever performed. It is expected that this study will also establish a basis for future studies related to the microcirculation in critically ill. PMID:22666566

  16. Effects of Oil Price Shocks on the Ghanaian Economy

    Directory of Open Access Journals (Sweden)

    Dennis Nchor

    2016-01-01

    Full Text Available The economy of Ghana is highly vulnerable to fluctuations in the international price of crude oil. This is due to the fact that oil as a commodity plays a central role in the economic activities of the nation. The objective of this paper is to investigate the dynamic relationship between oil price shocks and macroeconomic variables in the Ghanaian economy. This is achieved through the use of Vector Autoregressive (VAR and Vector Error Correction (VECM models. The variables considered in the study include: real oil price, real government expenditure, real industry value added, real imports, inflation and the real effective exchange rate. The study points out the asymmetric effects of oil price shocks; for instance, positive as well as negative oil price shocks on the macroeconomic variables used. The empirical findings of this study suggest that both linear and nonlinear oil price shocks have adverse impact on macroeconomic variables in Ghana. Positive oil price shocks are stronger than negative shocks with respect to government expenditure, inflation and the real effective exchange rate. Industry value added and imports have stronger responses to negative oil price shocks. Positive oil price shocks account for about 30% of fluctuations in government expenditure, 5% of imports, 6% of industry value added, 17% of inflation and 2% of the real effective exchange rate in the long run. Negative oil price shocks account for about 8% of fluctuations in government spending, 20% of imports, 8% of inflation and 2% of the real effective exchange rate in the long run. The data was obtained from the United States Energy Information Administration and the World Bank’s World Development Indicators.

  17. Multilevel models in international business research

    NARCIS (Netherlands)

    Peterson, M.F.; Arregle, J-L.; Martin, Xavier

    2012-01-01

    Multiple-level (or mixed linear) modeling (MLM) can simultaneously test hypotheses at several levels of analysis (usually two or three), or control for confounding effects at one level while testing hypotheses at others. Advances in multi-level modeling allow increased precision in quantitative

  18. Scientists' internal models of the greenhouse effect

    Science.gov (United States)

    Libarkin, J. C.; Miller, H.; Thomas, S. R.

    2013-12-01

    A prior study utilized exploratory factor analysis to identify models underlying drawings of the greenhouse effect made by entering university freshmen. This analysis identified four archetype models of the greenhouse effect that appear within the college enrolling population. The current study collected drawings made by 144 geoscientists, from undergraduate geoscience majors through professionals. These participants scored highly on a standardized assessment of climate change understanding and expressed confidence in their understanding; many also indicated that they teach climate change in their courses. Although geoscientists held slightly more sophisticated greenhouse effect models than entering freshmen, very few held complete, explanatory models. As with freshmen, many scientists (44%) depict greenhouse gases in a layer in the atmosphere; 52% of participants depicted this or another layer as a physical barrier to escaping energy. In addition, 32% of participants indicated that incoming light from the Sun remains unchanged at Earth's surface, in alignment with a common model held by students. Finally, 3-20% of scientists depicted physical greenhouses, ozone, or holes in the atmosphere, all of which correspond to non-explanatory models commonly seen within students and represented in popular literature. For many scientists, incomplete models of the greenhouse effect are clearly enough to allow for reasoning about climate change. These data suggest that: 1) better representations about interdisciplinary concepts, such as the greenhouse effect, are needed for both scientist and public understanding; and 2) the scientific community needs to carefully consider how much understanding of a model is needed before necessary reasoning can occur.

  19. Modelling and controlling infectious diseases | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    The research. The research team is exploring the potential of mathematical modelling to inform a new generation of tools and approaches to control disease spread. Drawing on research and surveillance data from China's National Center for AIDS/STD Control and Prevention, the team is creating disease models, focusing ...

  20. Traumatic brain injury and hemorrhagic shock: evaluation of different resuscitation strategies in a large animal model of combined insults.

    Science.gov (United States)

    Jin, Guang; DeMoya, Marc A; Duggan, Michael; Knightly, Thomas; Mejaddam, Ali Y; Hwabejire, John; Lu, Jennifer; Smith, William Michael; Kasotakis, Georgios; Velmahos, George C; Socrate, Simona; Alam, Hasan B

    2012-07-01

    Traumatic brain injury (TBI) and hemorrhagic shock (HS) are the leading causes of trauma-related mortality and morbidity. Combination of TBI and HS (TBI + HS) is highly lethal, and the optimal resuscitation strategy for this combined insult remains unclear. A critical limitation is the lack of suitable large animal models to test different treatment strategies. We have developed a clinically relevant large animal model of TBI + HS, which was used to evaluate the impact of different treatments on brain lesion size and associated edema. Yorkshire swine (42-50 kg) were instrumented to measure hemodynamic parameters and intracranial pressure. A computer-controlled cortical impact device was used to create a TBI through a 20-mm craniotomy: 15-mm cylindrical tip impactor at 4 m/s velocity, 100-ms dwell time, and 12-mm penetration depth. Volume-controlled hemorrhage was started (40% blood volume) concurrent with the TBI. After 2 h of shock, animals were randomized to one of three resuscitation groups (n = 5/group): (a) normal saline (NS); (b) 6% hetastarch, Hextend (Hex); and (c) fresh frozen plasma (FFP). Volumes of Hex and FFP matched the shed blood, whereas NS was three times the volume. After 6 h of postresuscitation monitoring, brains were sectioned into 5-mm slices and stained with TTC (2,3,5-triphenyltetrazolium chloride) to quantify the lesion size and brain swelling. Combination of 40% blood loss with cortical impact and a period of shock (2 h) resulted in a highly reproducible brain injury. Total fluid requirements were lower in the Hex and FFP groups. Lesion size and brain swelling in the FFP group (2,160 ± 202.63 mm and 22% ± 1.0%, respectively) were significantly smaller than those in the NS group (3,285 ± 130.8 mm3 and 37% ± 1.6%, respectively) (P < 0.05). Hex treatment decreased the swelling (29% ± 1.6%) without reducing the lesion size. Early administration of FFP reduces the size of brain lesion and associated swelling in a large animal model of TBI

  1. International Business Models Developed Through Brokerage Knowledge and Value Creation

    DEFF Research Database (Denmark)

    Petersen, Nicolaj Hannesbo; Rasmussen, Erik Stavnsager

    This paper highlights theoretically and empirically international business model decisions in networks with knowledge sharing and value creation. The paper expands the conceptual in-ternational business model framework for technology-oriented companies to include the focal firm’s network role...... and strategic fit in a global embeddedness. The brokerage role in the in-ternationalization of a network is discussed from both a theoretical and empirical point of view. From a business model and social network analysis perspective, this paper will show how firms and network grow internationally through two...

  2. Kinetics of the Thermal Decomposition of Tetramethylsilane behind the Reflected Shock Waves in a Single Pulse Shock Tube (SPST) and Modeling Study

    Science.gov (United States)

    Parandaman, A.; Sudhakar, G.; Rajakumar, B.

    Thermal reactions of Tetramethylsilane (TMS) diluted in argon were studied behind the reflected shock waves in a single-pulse shock tube (SPST) over the temperature range of 1085-1221 K and pressures varied between 10.6 and 22.8 atm. The stable products resulting from the decomposition of TMS were identified and quantified using gas chromatography and also verified with Fourier Transform Infrared (FTIR) spectrometer. The major reaction products are methane (CH4) and ethylene (C2H4). The minor reaction products are ethane (C2H6) and propylene (C3H6). The initiation of mechanism in the decomposition of TMS takes plays via the Si-C bond scission by ejecting the methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The measured temperature dependent rate coefficient for the total decomposition of TMS was to be ktotal = 1.66 ×1015 exp (-64.46/RT) s-1 and for the formation of CH4 reaction channel was to be k = 2.20 × 1014 exp (-60.15/RT) s-1, where the activation energies are given in kcal mol-1. A kinetic scheme containing 17 species and 28 elementary reactions was used for the simulation using chemical kinetic simulator over the temperature range of 1085-1221 K. The agreement between the experimental and simulated results was satisfactory.

  3. The impact of oil-market shocks on stock returns in major oil-exporting countries: A Markov-switching approach

    OpenAIRE

    Basher, Syed Abul; Haug, Alfred A.; Sadorsky, Perry

    2017-01-01

    The impact that oil shocks have on stock prices in oil exporting countries has implications for both domestic and international investors. We derive the shocks driving oil prices from a fully-identified structural model of the oil market. We study their nonlinear relationship with stock market returns in major oil-exporting countries in a multi-factor Markov-switching framework. Flow oil-demand shocks have a statistically significant impact on stock returns in Canada, Norway, Russia, Kuwait, ...

  4. A model for international border management systems.

    Energy Technology Data Exchange (ETDEWEB)

    Duggan, Ruth Ann

    2008-09-01

    To effectively manage the security or control of its borders, a country must understand its border management activities as a system. Using its systems engineering and security foundations as a Department of Energy National Security Laboratory, Sandia National Laboratories has developed such an approach to modeling and analyzing border management systems. This paper describes the basic model and its elements developed under Laboratory Directed Research and Development project 08-684.

  5. Discrete approximations of detonation flows with structured detonation reaction zones by discontinuous front models: A program burn algorithm based on detonation shock dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bdzil, J.B. [Los Alamos National Lab., NM (United States); Jackson, T.L. [Univ. of Illinois, Urbana, IL (United States). Center for Simulation of Advanced Rockets; Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States). Theoretical and Applied Mechanics

    1999-02-02

    In the design of explosive systems the generic problem that one must consider is the propagation of a well-developed detonation wave sweeping through an explosive charge with a complex shape. At a given instant of time the lead detonation shock is a surface that occupies a region of the explosive and has a dimension that is characteristic of the explosive device, typically on the scale of meters. The detonation shock is powered by a detonation reaction zone, sitting immediately behind the shock, which is on the scale of 1 millimeter or less. Thus, the ratio of the reaction zone thickness to the device dimension is of the order of 1/1,000 or less. This scale disparity can lead to great difficulties in computing three-dimensional detonation dynamics. An attack on the dilemma for the computation of detonation systems has lead to the invention of sub-scale models for a propagating detonation front that they refer to herein as program burn models. The program burn model seeks not to resolve the fine scale of the reaction zone in the sense of a DNS simulation. The goal of a program burn simulation is to resolve the hydrodynamics in the inert product gases on a grid much coarser than that required to resolve a physical reaction zone. The authors first show that traditional program burn algorithms for detonation hydrocodes used for explosive design are inconsistent and yield incorrect shock dynamic behavior. To overcome these inconsistencies, they are developing a new class of program burn models based on detonation shock dynamic (DSD) theory. It is hoped that this new class will yield a consistent and robust algorithm which reflects the correct shock dynamic behavior.

  6. Toxic shock syndrome

    Science.gov (United States)

    Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

  7. Validation of an internal hardwood log defect prediction model

    Science.gov (United States)

    R. Edward. Thomas

    2011-01-01

    The type, size, and location of internal defects dictate the grade and value of lumber sawn from hardwood logs. However, acquiring internal defect knowledge with x-ray/computed-tomography or magnetic-resonance imaging technology can be expensive both in time and cost. An alternative approach uses prediction models based on correlations among external defect indicators...

  8. A New Conceptual Model for Understanding International Students' College Needs

    Science.gov (United States)

    Alfattal, Eyad

    2016-01-01

    This study concerns the theory and practice of international marketing in higher education with the purpose of exploring a conceptual model for understanding international students' needs in the context of a four-year college in the United States. A transcendental phenomenological design was employed to investigate the essence of international…

  9. Evaluation of internal noise methods for Hotelling observer models

    International Nuclear Information System (INIS)

    Zhang Yani; Pham, Binh T.; Eckstein, Miguel P.

    2007-01-01

    The inclusion of internal noise in model observers is a common method to allow for quantitative comparisons between human and model observer performance in visual detection tasks. In this article, we studied two different strategies for inserting internal noise into Hotelling model observers. In the first strategy, internal noise was added to the output of individual channels: (a) Independent nonuniform channel noise, (b) independent uniform channel noise. In the second strategy, internal noise was added to the decision variable arising from the combination of channel responses. The standard deviation of the zero mean internal noise was either constant or proportional to: (a) the decision variable's standard deviation due to the external noise, (b) the decision variable's variance caused by the external noise, (c) the decision variable magnitude on a trial to trial basis. We tested three model observers: square window Hotelling observer (HO), channelized Hotelling observer (CHO), and Laguerre-Gauss Hotelling observer (LGHO) using a four alternative forced choice (4AFC) signal known exactly but variable task with a simulated signal embedded in real x-ray coronary angiogram backgrounds. The results showed that the internal noise method that led to the best prediction of human performance differed across the studied model observers. The CHO model best predicted human observer performance with the channel internal noise. The HO and LGHO best predicted human observer performance with the decision variable internal noise. The present results might guide researchers with the choice of methods to include internal noise into Hotelling model observers when evaluating and optimizing medical image quality

  10. Stock assessment model outputs for ICCAT (International) managed species

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Includes outputs from the various models run in the evaluation of stock status for species managed by the International Commission for the Conservation of Atlantic...

  11. A Reaction Zone Enthalpy Balance Model to Simulate Shock-to-Detonation Transition and Unsteady Detonation Wave Propagation

    Science.gov (United States)

    Froger, A.

    2004-07-01

    The standard models in use to simulate the reactive detonation wave propagation are not accurate in computing the transient evolutions because they focus on the shock front, not on the reaction zone where the coupling of thermodynamic and mechanic effects occurs. The model we propose is based on a new thermodynamic description of the constituents in the reaction zone, and on the use of the enthalpy balance of the chemical reaction as the energetic parameter instead of the heat of reaction. The enthalpy balance of the reaction results from the enthalpies of formation of all the chemical species involved in the reaction and is, therefore, a physical constant. The model is based on four basic assumptions: -1) the reaction zone is anevolving intimate mixture of non-reacted material and detonation products, -2) the energy released by thereaction is inherent to the detonation products alone, -3) the two constituents have the same pressure but different temperatures, -4) the specific energy released is not a constant but is related to the enthalpy balance and depends on the thermodynamic state. The model only needs the physical properties of the materials (equations of state of the constituents, chemical reaction and initiation delay), not the CJ state nor any other sub-model. When coupled with the Euler equations this thermodynamic description of the reaction zone permits us to simulate the transient evolution of an emerging detonation for any geometry (2D or 3D) or confinement structure.

  12. Los Alamos Radiation Hydrocode Models of Asteroid Mitigation by an Internal Explosion

    Science.gov (United States)

    Weaver, Robert; Plesko, C.; Dearholdt, W.

    2010-10-01

    Mitigation of a potentially hazardous object (PHO) by a conventional or nuclear subsurface burst is considered. This intervention methodology has been popularized in media presentations and is considered as one possible method of impact-hazard mitigation. We present RAGE radiation hydrocode models of the shock-generated disruption of PHOs by subsurface nuclear bursts and deflection from shallow buried bursts using scenario-specific models from authentic RADAR shape models. We will show 2D and 3D models for the disruption by a large energy source at the center and near the edge (mitigation) of such PHO models (1-10 Mton TNT equivalent), specifically for asteroid 25143 Itokawa. Parametric studies will be done on: the value of the source energy (from 1 Mton to 10 Mton), the parameters in the Steinberg-Guinan strength model used and the internal composition of the object from uniform composition to a "rubble pile” distribution. Specifically we are interested in assessing the optimum depth of burial and energy required to essentially disrupt and/or move the PHO and therefore mitigate the hazard. Recollection will be considered.

  13. PBA regulates neurogenesis and cognition dysfunction after repeated electroconvulsive shock in a rat model.

    Science.gov (United States)

    Yao, Zhao-Hui; Kang, Xiang; Yang, Liu; Niu, Yi; Lu, Ye; Nie, Li

    2015-12-15

    Electroconvulsive therapy (ECT) was widely used to treat the refractory depression. But ECT led to the cognitive deficits plaguing the depression patients. The underlying mechanisms of the cognitive deficits remain elusive. Repeated electroconvulsive shock (rECS) was used to simulate ECT and explore the mechanisms of ECT during the animal studies. Previous studies showed rECS could lead to neurogenesis and cognitive impairment. But it was well known that neurogenesis could improve the cognition. So these suggested that the mechanism of the cognitive deficit after rECS was very complex. In present study, we explored the probable mechanisms of the cognitive deficit after rECS from neurogenesis aspect. We found the cognitive deficit was reversible and neurogenesis could bring a long-term beneficial effect on cognition. Astrogliosis and NR1 down-regulation probably participated in the reversible cognitive deficits after rECS. Phenylbutyric acid (PBA), generally as an agent to investigate the roles of histone acetylation, could prevent the reversible cognitive dysfunction, but PBA could diminish the long-term effect of enhanced cognition by rECS. These suggested that ECT could possibly bring the long-term beneficial cognitive effect by regulating neurogenesis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. Oscillating nonlinear acoustic shock waves

    DEFF Research Database (Denmark)

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....

  15. Double Shock Experiments Performed at -55°C on LX-17 with Reactive Flow Modeling to Understand the Reacted Equation of State

    Science.gov (United States)

    Dehaven, Martin R.; Vandersall, Kevin S.; Strickland, Shawn L.; Fried, Laurence E.; Tarver, Craig M.

    2017-06-01

    Experiments were performed at -55°C to measure the reacted state of LX-17 (92.5% TATB and 7.5% Kel-F by weight) using a double shock technique using two flyer materials (with known properties) mounted on a projectile that send an initial shock through the material close to the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. Information on the reacted state is obtained by measuring the relative timing and magnitude of the first and second shock waves. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include a comparison to prior work at ambient temperature, the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Modeling the international competitiveness of Botswana's coal

    Science.gov (United States)

    Fichani, Khaulani

    Botswana has vast proven deposits of steam coal, which for a long time it has wanted to develop but without much success. The main objectives of this study are: (1) to analyze the time schedule of coal exports likely to be forthcoming from Botswana and the land routes for these exports; (2) to determine the competitiveness of Botswana's coal in the world steam coal markets and (3) to make recommendations on the appropriate policy for the exploitation of this coal. To accomplish these objectives, we construct a model of the seaborne steam coal trade consisting of exporters and importers with a substantial share in this trade. We econometrically estimate the long run marginal cost functions for net exporters and employ these to construct a spatial and dynamic model of the world steam coal trade with elastic supply and inelastic demand. This model is applied to simulate Botswana's competitiveness in this trade over the period 1995 to 2010 from a 1990 base year with a decision criterion that minimizes the sum of discounted capital costs of mine development, variable supply costs, rail and maritime transportation costs. Finally, we employ the model to forecast the likely optimal size of mine, timing of production capacity and choice of export port for Botswana's coal for the years 2005 and 2010. The base year for the forecast is 2000. The simulation results indicate that Botswana's coal would have been competitive in the steam coal markets of Western Europe and Asia. The forecast results indicate that Botswana's coal would also be competitive in these markets in the future. These results are least sensitive to changes in rail transportation and variable supply costs but are sensitive to capital costs for mine development.

  17. PROCESS OF GLOBAL SHOCKS TRANSMISSION TO DOMESTIC FOOD PRICE LEVEL: CASE OF BANGLADESH

    Directory of Open Access Journals (Sweden)

    Fakir Azmal Huda

    2014-04-01

    Full Text Available The world experienced in dramatic price surge of food commodities since mid of 2007 to 2008. It was claimed that the crisis were being mainly for backdrop of global shocks in food and energy price. But how the shocks come to domestic market from external sources is a researchable phenomenon. Surprisingly few attempts have been made to systematically analysis of shock transmission from international to domestic market. The study analyzed the effect of global commodity market factors and domestic exchange rate development on domestic food price in Bangladesh. A bi-variants co-integration approach was applied for the analysis of shock transmission. Finally an error correction model was developed. The overall magnitudes of the pass through suggest that only 46 per cent of the total world shock pass-through in domestic economy.

  18. Self-organized Criticality Model for Ocean Internal Waves

    International Nuclear Information System (INIS)

    Wang Gang; Hou Yijun; Lin Min; Qiao Fangli

    2009-01-01

    In this paper, we present a simple spring-block model for ocean internal waves based on the self-organized criticality (SOC). The oscillations of the water blocks in the model display power-law behavior with an exponent of -2 in the frequency domain, which is similar to the current and sea water temperature spectra in the actual ocean and the universal Garrett and Munk deep ocean internal wave model [Geophysical Fluid Dynamics 2 (1972) 225; J. Geophys. Res. 80 (1975) 291]. The influence of the ratio of the driving force to the spring coefficient to SOC behaviors in the model is also discussed. (general)

  19. The Effect of Infrarenal Aortic Balloon Occlusion on Weaning from Supraceliac Aortic Balloon Occlusion in a Porcine Model (Sus scrofa) of Hemorrhagic Shock

    Science.gov (United States)

    2017-06-15

    all animals , and continued for six hours. Half of the animals were randomly assigned to Zone-3 REBOA for an additional 45 minutes following Zone-1...concentration or resuscitation requirements.Conclusion: In an animal model of hemorrhagic shock and Zone-1 REBOA, subsequent Zone-3 aortic occlusion did not add

  20. Early treatment with lyophilized plasma protects the brain in a large animal model of combined traumatic brain injury and hemorrhagic shock

    DEFF Research Database (Denmark)

    Imam, Ayesha M; Jin, Guang; Sillesen, Martin

    2013-01-01

    Combination of traumatic brain injury (TBI) and hemorrhagic shock (HS) can result in significant morbidity and mortality. We have previously shown that early administration of fresh frozen plasma (FFP) in a large animal model of TBI and HS reduces the size of the brain lesion as well...

  1. demystifying the shock of shocking

    African Journals Online (AJOL)

    aimed at depolarising a myocardium that is not generating a co-ordinated, perfusing rhythm. Organised QRS complexes cannot be identified and the electrical current is delivered without synchronising with the patient's native rhythm. DC shock should not be delayed once a shockable rhythm is recognised. The longer the ...

  2. Modeling and assessing international climate financing

    Science.gov (United States)

    Wu, Jing; Tang, Lichun; Mohamed, Rayman; Zhu, Qianting; Wang, Zheng

    2016-06-01

    Climate financing is a key issue in current negotiations on climate protection. This study establishes a climate financing model based on a mechanism in which donor countries set up funds for climate financing and recipient countries use the funds exclusively for carbon emission reduction. The burden-sharing principles are based on GDP, historical emissions, and consumptionbased emissions. Using this model, we develop and analyze a series of scenario simulations, including a financing program negotiated at the Cancun Climate Change Conference (2010) and several subsequent programs. Results show that sustained climate financing can help to combat global climate change. However, the Cancun Agreements are projected to result in a reduction of only 0.01°C in global warming by 2100 compared to the scenario without climate financing. Longer-term climate financing programs should be established to achieve more significant benefits. Our model and simulations also show that climate financing has economic benefits for developing countries. Developed countries will suffer a slight GDP loss in the early stages of climate financing, but the longterm economic growth and the eventual benefits of climate mitigation will compensate for this slight loss. Different burden-sharing principles have very similar effects on global temperature change and economic growth of recipient countries, but they do result in differences in GDP changes for Japan and the FSU. The GDP-based principle results in a larger share of financial burden for Japan, while the historical emissions-based principle results in a larger share of financial burden for the FSU. A larger burden share leads to a greater GDP loss.

  3. Simulation-Based Internal Models for Safer Robots

    Directory of Open Access Journals (Sweden)

    Christian Blum

    2018-01-01

    Full Text Available In this paper, we explore the potential of mobile robots with simulation-based internal models for safety in highly dynamic environments. We propose a robot with a simulation of itself, other dynamic actors and its environment, inside itself. Operating in real time, this simulation-based internal model is able to look ahead and predict the consequences of both the robot’s own actions and those of the other dynamic actors in its vicinity. Hence, the robot continuously modifies its own actions in order to actively maintain its own safety while also achieving its goal. Inspired by the problem of how mobile robots could move quickly and safely through crowds of moving humans, we present experimental results which compare the performance of our internal simulation-based controller with a purely reactive approach as a proof-of-concept study for the practical use of simulation-based internal models.

  4. The International Reference Ionosphere 2012 – a model of international collaboration☆

    Directory of Open Access Journals (Sweden)

    Bilitza Dieter

    2014-02-01

    Full Text Available The International Reference Ionosphere (IRI project was established jointly by the Committee on Space Research (COSPAR and the International Union of Radio Science (URSI in the late sixties with the goal to develop an international standard for the specification of plasma parameters in the Earth’s ionosphere. COSPAR needed such a specification for the evaluation of environmental effects on spacecraft and experiments in space, and URSI for radiowave propagation studies and applications. At the request of COSPAR and URSI, IRI was developed as a data-based model to avoid the uncertainty of theory-based models which are only as good as the evolving theoretical understanding. Being based on most of the available and reliable observations of the ionospheric plasma from the ground and from space, IRI describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 km to 2000 km. A working group of about 50 international ionospheric experts is in charge of developing and improving the IRI model. Over time as new data became available and new modeling techniques emerged, steadily improved editions of the IRI model have been published. This paper gives a brief history of the IRI project and describes the latest version of the model, IRI-2012. It also briefly discusses efforts to develop a real-time IRI model. The IRI homepage is at http://IRImodel.org.

  5. International Shock Congress (1st) and Annual Society Meeting (10th) Held in Montreal, Canada on 7-11 June 1987

    Science.gov (United States)

    1987-10-01

    Studlo per la Fisiopatologia dello Shock, CNR, 1-00168 Rome, Italy and iMIEMSS and Departments of Surgery and Pathology, University of MD, Baltimore, MD...increases PDH kinase activity and inactivates PDH. This factor appears similar to the kinase activator protein described for starvation and diabetes -induced...Centro Studio Fisiopatologia Shock CNR, Catholic University, I-001b Rome, Italy. An extensive work was performed in order to develop a method for

  6. Oblique MHD cosmic-ray modified shocks: Two-fluid numerical simulations

    Science.gov (United States)

    Frank, Adam; Jones, T. W.; Ryu, Dongsu

    1991-01-01

    We present the first results of time dependent, two-fluid, cosmic-ray (CR) modified, MHD shock simulations. The calculations were carried out with a new numerical code for 1-D ideal MHD. By coupling this code with the CR energy transport equation we can simulate the time-dependent evolution of MHD shocks including the acceleration of the CR and their feedback on the shock structures. We report tests of the combined numerical method including comparisons with analytical steady state results published earlier by Webb, as well as internal consistency checks for more general MHD CR shock structures after they appear to have converged to dynamical steady states. We also present results from an initial time dependent simulation which extend the parameter space domain of previous analytical models. These new results support Webb's suggestion that equilibrium oblique shocks are less effective than parallel shocks in the acceleration of CR. However, for realistic models of anisotropic CR diffusion, oblique shocks may achieve dynamical equilibrium on shorter timescale than parallel shocks.

  7. Supernova shock breakout from a red supergiant.

    Science.gov (United States)

    Schawinski, Kevin; Justham, Stephen; Wolf, Christian; Podsiadlowski, Philipp; Sullivan, Mark; Steenbrugge, Katrien C; Bell, Tony; Röser, Hermann-Josef; Walker, Emma S; Astier, Pierre; Balam, Dave; Balland, Christophe; Carlberg, Ray; Conley, Alex; Fouchez, Dominique; Guy, Julien; Hardin, Delphine; Hook, Isobel; Howell, D Andrew; Pain, Reynald; Perrett, Kathy; Pritchet, Chris; Regnault, Nicolas; Yi, Sukyoung K

    2008-07-11

    Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic "core-collapse" supernova. Such events are usually only detected at least a few days after the star has exploded. Observations of the supernova SNLS-04D2dc with the Galaxy Evolution Explorer space telescope reveal a radiative precursor from the supernova shock before the shock reached the surface of the star and show the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve confirm that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a way to probe the physics of core-collapse supernovae and the internal structures of their progenitor stars.

  8. Cardiogenic Shock.

    Science.gov (United States)

    Moskovitz, Joshua B; Levy, Zachary D; Slesinger, Todd L

    2015-08-01

    Cardiogenic shock is the leading cause of morbidity and mortality in patients presenting with acute coronary syndrome. Although early reperfusion strategies are essential to the management of these critically ill patients, additional treatment plans are often needed to stabilize and treat the patient before reperfusion may be possible. This article discusses pharmacologic and surgical interventions, their indications and contraindications, management strategies, and treatment algorithms. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Traffic Jam and Shock Formation in Stochastic Traffic-Flow Model of a Two-Lane Roadway

    Science.gov (United States)

    Nagatani, Takashi

    1994-01-01

    We present a stochastic cellular automaton (CA) model to simulate the traffic jam induced by a car accident in the traffic flow of a two-lane roadway. The CA model is an extended version of the one-dimensional asymmetric exclusion model to take into account the stochastic exchange of cars between the first and second lanes. We study the traffic flow of the system when the translation invariance is broken by the insertion of a blockage which is induced by a car accident on the first lane. Using the computer simulation, it is found that the dynamical jamming transions occur successively from the phase 1, through the phase 2, to the phase 3 with increasing the density of cars. The phase 1 is characterized by the property such that no cars exist in the first lane and the cars on the second lane move with the maximal velocity. The phase 2 is characterized by the shock formation (a discontinuity of density) and the maximal current. In the phase 3, the discontinuity disappears and the traffic flow is not affected by the car accident.

  10. Quasilinear simulations of interplanetary shocks and Earth's bow shock

    Science.gov (United States)

    Afanasiev, Alexandr; Battarbee, Markus; Ganse, Urs; Vainio, Rami; Palmroth, Minna; Pfau-Kempf, Yann; Hoilijoki, Sanni; von Alfthan, Sebastian

    2016-04-01

    We have developed a new self-consistent Monte Carlo simulation model for particle acceleration in shocks. The model includes a prescribed large-scale magnetic field and plasma density, temperature and velocity profiles and a self-consistently computed incompressible ULF foreshock under the quasilinear approximation. Unlike previous analytical treatments, our model is time dependent and takes full account of the anisotropic particle distributions and scattering in the wave-particle interaction process. We apply the model to the problem of particle acceleration at traveling interplanetary (IP) shocks and Earth's bow shock and compare the results with hybrid-Vlasov simulations and spacecraft observations. A qualitative agreement in terms of spectral shape of the magnetic fluctuations and the polarization of the unstable mode is found between the models and the observations. We will quantify the differences of the models and explore the region of validity of the quasilinear approach in terms of shock parameters. We will also compare the modeled IP shocks and the bow shock, identifying the similarities and differences in the spectrum of accelerated particles and waves in these scenarios. The work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA). The Academy of Finland is thanked for financial support. We acknowledge the computational resources provided by CSC - IT Centre for Science Ltd., Espoo.

  11. Gamma-Ray Burst Spectral Indices: Evidence for Deceleration of Synchrotron Shocks

    Science.gov (United States)

    Preece, R. D.; Briggs, M. S.; Giblin, T.; Mallozzi, R. S.; Pendleton, G. N.; Paciesas, W. S.; Band, D. L.

    2000-01-01

    The current scenario for gamma-ray bursts (GRBs) involves internal shocks for the prompt GRB emission phase and external shocks for the afterglow phase. Assuming synchrotron emission from energetic shocked electrons. GRB spectra observed with a low-energy power-law spectral index greater than -2/3 (for positive photon number indices E(sup alpha) indicate a problem with this model. The remaining spectra can test the synchrotron shock model prediction that the emission from a single distribution of electrons, cooling rapidly, is responsible for both the low-energy and high-energy power-low portions of the spectra. We find that the inferred relationship between the two spectral indices of observed GRB spectra is inconsistent with the constraints from the model, posing another problem for the synchrotron shock emission model. To overcome this problem, we describe a model where the average of -1, rather than the value of -3/2 predicted for cooling electrons. Situations where this might arise have been discussed in other contexts, and involve deceleration of the internal shocks during the GRB phase.

  12. An extended gravity model with substitution applied to international trade

    NARCIS (Netherlands)

    Bikker, J.A.

    The traditional gravity model has been applied many times to international trade flows, especially in order to analyze trade creation and trade diversion. However, there are two fundamental objections to the model: it cannot describe substitutions between flows and it lacks a cogent theoretical

  13. Reserves and Trade Jointly Determine Exposure to Food Supply Shocks

    Science.gov (United States)

    Marchand, Philippe; Carr, Joel A.; Dell'Angelo, Jampel; Fader, Marianela; Gephart, Jessica A.; Kummu, Matti; Magliocca, Nicholas; Porkka, Miina; Puma, Michael J.; Zak, Ratajczak

    2016-01-01

    While a growing proportion of global food consumption is obtained through international trade, there is an ongoing debate on whether this increased reliance on trade benefits or hinders food security, and specifically, the ability of global food systems to absorb shocks due to local or regional losses of production. This paper introduces a model that simulates the short-term response to a food supply shock originating in a single country, which is partly absorbed through decreases in domestic reserves and consumption, and partly transmitted through the adjustment of trade flows. By applying the model to publicly-available data for the cereals commodity group over a 17 year period, we find that differential outcomes of supply shocks simulated through this time period are driven not only by the intensification of trade, but as importantly by changes in the distribution of reserves. Our analysis also identifies countries where trade dependency may accentuate the risk of food shortages from foreign production shocks; such risk could be reduced by increasing domestic reserves or importing food from a diversity of suppliers that possess their own reserves. This simulation-based model provides a framework to study the short-term, nonlinear and out-of-equilibrium response of trade networks to supply shocks, and could be applied to specific scenarios of environmental or economic perturbations.

  14. Hexavalent Chromium Removal from Model Water and Car Shock Absorber Factory Effluent by Nanofiltration and Reverse Osmosis Membrane

    Directory of Open Access Journals (Sweden)

    Amine Mnif

    2017-01-01

    Full Text Available Nanofiltration and reverse osmosis are investigated as a possible alternative to the conventional methods of Cr(VI removal from model water and industrial effluent. The influences of feed concentration, water recovery, pH, and the coexisting anions were studied. The results have shown that retention rates of hexavalent chromium can reach 99.7% using nanofiltration membrane (NF-HL and vary from 85 to 99.9% using reverse osmosis membrane (RO-SG depending upon the composition of the solution and operating conditions. This work was also extended to investigate the separation of Cr(VI from car shock absorber factory effluent. The use of these membranes is very promising for Cr(VI water treatment and desalting industry effluent. Spiegler-Kedem model was applied to experimental results in the aim to determine phenomenological parameters, the reflection coefficient of the membrane (σ, and the solute permeability coefficient (Ps. The convective and diffusive parts of the mass transfer were quantified with predominance of the diffusive contribution.

  15. Perpendicular relativistic shocks in magnetized pair plasma

    Science.gov (United States)

    Plotnikov, Illya; Grassi, Anna; Grech, Mickael

    2018-04-01

    Perpendicular relativistic (γ0 = 10) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive Shock Acceleration is observed only in weakly magnetized shocks, while a dominant contribution of Shock Drift Acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of AGN jets and in the termination shocks of Pulsar Wind Nebulae.

  16. How Non-Gaussian Shocks Affect Risk Premia in Non-Linear DSGE Models

    DEFF Research Database (Denmark)

    Andreasen, Martin Møller

    premia in a wide class of DSGE models. To quantify these effects, we then set up a standard New Keynesian DSGE model where total factor productivity includes rare disasters, stochastic volatility, and GARCH. We …find that rare disasters increase the mean level of the 10-year nominal term premium, whereas...

  17. Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

    Science.gov (United States)

    Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

    2015-03-01

    The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

  18. A GDP-driven model for the binary and weighted structure of the International Trade Network

    Science.gov (United States)

    Almog, Assaf; Squartini, Tiziano; Garlaschelli, Diego

    2015-01-01

    Recent events such as the global financial crisis have renewed the interest in the topic of economic networks. One of the main channels of shock propagation among countries is the International Trade Network (ITN). Two important models for the ITN structure, the classical gravity model of trade (more popular among economists) and the fitness model (more popular among networks scientists), are both limited to the characterization of only one representation of the ITN. The gravity model satisfactorily predicts the volume of trade between connected countries, but cannot reproduce the missing links (i.e. the topology). On the other hand, the fitness model can successfully replicate the topology of the ITN, but cannot predict the volumes. This paper tries to make an important step forward in the unification of those two frameworks, by proposing a new gross domestic product (GDP) driven model which can simultaneously reproduce the binary and the weighted properties of the ITN. Specifically, we adopt a maximum-entropy approach where both the degree and the strength of each node are preserved. We then identify strong nonlinear relationships between the GDP and the parameters of the model. This ultimately results in a weighted generalization of the fitness model of trade, where the GDP plays the role of a ‘macroeconomic fitness’ shaping the binary and the weighted structure of the ITN simultaneously. Our model mathematically explains an important asymmetry in the role of binary and weighted network properties, namely the fact that binary properties can be inferred without the knowledge of weighted ones, while the opposite is not true.

  19. Structure and internal consistency of a shoulder model.

    Science.gov (United States)

    Högfors, C; Karlsson, D; Peterson, B

    1995-07-01

    A three-dimensional biomechanical model of the shoulder is developed for force predictions in 46 shoulder structures. The model is directed towards the analysis of static working situations where the load is low or moderate. Arbitrary static arm postures in the natural shoulder range may be considered, as well as different kinds of external loads including different force and moment directions. The model can predict internal forces for the shoulder muscles, for the glenohumeral, the acromioclavicular and the sternoclavicular joint as well as for the coracohumeral ligament. A solution to the statistically indeterminate force system is obtained by minimising an objective function. The default function chosen for this is the sum of the squared muscle stresses, but other objective functions may be used as well. The structure of the model is described and its ingredients discussed. The internal consistency of the model, its structural stability and the compatibility of the elements that go into it, is investigated.

  20. Awara (Astrocaryum vulgare M.) pulp oil: chemical characterization, and anti-inflammatory properties in a mice model of endotoxic shock and a rat model of pulmonary inflammation.

    Science.gov (United States)

    Bony, Emilie; Boudard, Frédéric; Brat, Pierre; Dussossoy, Emilie; Portet, Karine; Poucheret, Patrick; Giaimis, Jean; Michel, Alain

    2012-01-01

    Awara (Astrocaryum vulgare M.) is a palm fruit mainly used in nutrition. We analysed the pulp oil for fatty acid, tocopherol, carotenoid, and phytosterol and we evaluated whether this oil may attenuate inflammation in vivo. In an endotoxic shock model, awara pulp oil treatment decreased pro-inflammatory cytokines and increased anti-inflammatory cytokines. In a pulmonary inflammation model, awara pulp oil treatment reduced eosinophil and lymphocyte numbers recovered into the broncho-alveolar lavages. These results suggest that awara pulp oil administration can efficiently counteract an acute and chronic inflammatory response in vivo that is probably mediated by fatty acids and minor compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Glutamine reduces myocardial cell apoptosis in a rat model of sepsis by promoting expression of heat shock protein 90.

    Science.gov (United States)

    Li, Wanxia; Tao, Shaoyu; Wu, Qinghua; Wu, Tao; Tao, Ran; Fan, Jun

    2017-12-01

    Myocardial cell injury and cardiac myocyte apoptosis are associated with sepsis. Glutamine (Gln) has been reported to repair myocardial cell injury. The aim of this study was to explore the role of Gln on cardiac myocytes in a cecal ligation and puncture (CLP) model of sepsis in Wistar rats. Following induction of sepsis in a CLP rat model, viral encoding heat shock protein 90 (Hsp90) gene and Hsp90dsDNA were designed to express and knockdown Hsp90, respectively. Rat cardiac tissues were examined histologically, and apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling staining. The expression of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein, Hsp90, p53 upregulated modulator of apoptosis, and p53 was measured by western blotting and real-time polymerase chain reaction. Caspase-3, caspase-8, and caspase-9 were detected by enzyme-linked immunosorbent assay. Rat cardiac myocyte damage induced by CLP was reduced by Gln treatment and Hsp90 overexpression, and these changes were reversed by Hsp90 knockdown. Bcl-2 expression, Bcl-2-associated X protein, p53, p53 upregulated modulator of apoptosis, caspase-8, caspase-9, and caspase-3 activities were significantly upregulated in the CLP model, which were reduced by Gln treatment and Hsp90 overexpression. Gln reduced apoptosis of cardiac myocytes in a rat model of sepsis, by promoting Hsp90 expression. Further studies are needed to determine the possible therapeutic action of Gln in sepsis in human tissue. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Do sector-specific shocks explain aggregate fluctuations?

    DEFF Research Database (Denmark)

    Busato, Francesco; Girardi, Alessandro; Argentiero, Amedeo

    This paper estimates a reduced form multi-sector real business cycle model that allows for sectorspecificand cross-sector shocks of two different types: technology shocks and non-technology shocks.Long run restrictions identify the different kinds of shocks. There are four main findings.(i) Secto...

  3. Initial conditions of radiative shock experiments

    International Nuclear Information System (INIS)

    Kuranz, C. C.; Drake, R. P.; Krauland, C. M.; Marion, D. C.; Grosskopf, M. J.; Rutter, E.; Torralva, B.; Holloway, J. P.; Bingham, D.; Goh, J.; Boehly, T. R.; Sorce, A. T.

    2013-01-01

    We performed experiments at the Omega Laser Facility to characterize the initial, laser-driven state of a radiative shock experiment. These experiments aimed to measure the shock breakout time from a thin, laser-irradiated Be disk. The data are then used to inform a range of valid model parameters, such as electron flux limiter and polytropic γ, used when simulating radiative shock experiments using radiation hydrodynamics codes. The characterization experiment and the radiative shock experiment use a laser irradiance of ∼7 × 10 14 W cm −2 to launch a shock in the Be disk. A velocity interferometer and a streaked optical pyrometer were used to infer the amount of time for the shock to move through the Be disk. The experimental results were compared with simulation results from the Hyades code, which can be used to model the initial conditions of a radiative shock system using the CRASH code

  4. Global assemblages and structural models of International Relations

    DEFF Research Database (Denmark)

    Corry, Olaf

    2014-01-01

    Rather than consigning assemblages to the micro-politics of international relations, the chapter argues that assemblages can also be seen to play a role in the ‘grand’ structures of international relations. Structural IR theory normally only considers how subjects are ordered – hierarchically......, anarchically, in core-periphery relations or in terms of networks. However, not only subjects but also assemblages – the bringing together of previously unconnected elements into novel constellations – play a critical role in structuring international relations. More specifically, one sub......-category of assemblages – those constructed as malleable and governable which I call ‘governance-objects’ – is central to structure in international relations. The chapter begins with standard definitions of what structures are – patterns of interaction between elements – and briefly covers the range of models currently...

  5. Internal noise-sustained circadian rhythms in a Drosophila model.

    Science.gov (United States)

    Li, Qianshu; Lang, Xiufeng

    2008-03-15

    Circadian rhythmic processes, mainly regulated by gene expression at the molecular level, have inherent stochasticity. Their robustness or resistance to internal noise has been extensively investigated by most of the previous studies. This work focuses on the constructive roles of internal noise in a reduced Drosophila model, which incorporates negative and positive feedback loops, each with a time delay. It is shown that internal noise sustains reliable oscillations with periods close to 24 h in a region of parameter space, where the deterministic kinetics would evolve to a stable steady state. The amplitudes of noise-sustained oscillations are significantly affected by the variation of internal noise level, and the best performance of the oscillations could be found at an optimal noise intensity, indicating the occurrence of intrinsic coherence resonance. In the oscillatory region of the deterministic model, the coherence of noisy circadian oscillations is suppressed by internal noise, while the period remains nearly constant over a large range of noise intensity, demonstrating robustness of the Drosophila model for circadian rhythms to intrinsic noise. In addition, the effects of time delay in the positive feedback on the oscillations are also investigated. It is found that the time delay could efficiently tune the performance of the noise-sustained oscillations. These results might aid understanding of the exploitation of intracellular noise in biochemical and genetic regulatory systems.

  6. Shock Prevention

    Science.gov (United States)

    1978-01-01

    The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical shock in the home or in industrial facilities. Shocks due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.

  7. Shocks in the Early Universe.

    Science.gov (United States)

    Pen, Ue-Li; Turok, Neil

    2016-09-23

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

  8. Bayesian inference in a discrete shock model using confounded common cause data

    International Nuclear Information System (INIS)

    Kvam, Paul H.; Martz, Harry F.

    1995-01-01

    We consider redundant systems of identical components for which reliability is assessed statistically using only demand-based failures and successes. Direct assessment of system reliability can lead to gross errors in estimation if there exist external events in the working environment that cause two or more components in the system to fail in the same demand period which have not been included in the reliability model. We develop a simple Bayesian model for estimating component reliability and the corresponding probability of common cause failure in operating systems for which the data is confounded; that is, the common cause failures cannot be distinguished from multiple independent component failures in the narrative event descriptions

  9. INTERFERENCE OF COUNTERPROPAGATING SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-03-01

    Full Text Available The subject of study. We examined the interaction of counterpropagating shock waves. The necessity of counterpropagating shock waves studying occurs at designing of high Mach number modern internal compression air intakes, Ramjets with subsonic and supersonic combustion, in asymmetrical supersonic nozzles and in some other cases. In a sense, this problem is a generalization of the case of an oblique shock reflection from the wall or from the plane of symmetry. With the renewed vigor, the interest to this problem emerged at the end of the 90s. This was due to the start of the programs for flight study at hypersonic speeds. The first experiments performed with air intakes, which realized the interaction of counterpropagating shock waves have shown that the change in flow velocity is accompanied by abrupt alteration of shock-wave structure, the occurrence of nonstationary and oscillatory phenomena. With an increase of flow velocity these phenomena undesirable for aircraft structure became more marked. The reason is that there are two fundamentally different modes of interaction of counterpropagating shock waves: a four-wave regular and a five-wave irregular. The transition from one mode to another can be nonstationary abrupt or gradual, it can also be accompanied by hysteresis. Main results. Criteria for the transition from regular reflection of counterpropagating shock waves to irregular are described: the criterion of von Neumann and the stationary Mach configuration criterion. We described areas in which the transition from one reflection type to another is possible only in abrupt way, as well as areas of possible gradual transition. Intensity dependences of the reflected shock waves from the intensity of interacting counterpropagating shocks were given. Qualitative pictures of shock-wave structures arising from the interaction of counterpropagating shock waves were shown. Calculation results of the intensity of outgoing gas

  10. Characterization of shocked beryllium

    Directory of Open Access Journals (Sweden)

    Papin P.A.

    2012-08-01

    Full Text Available While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity models, the Preston-Tonks-Wallace (PTW and Mechanical Threshold Stress (MTS models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional “arrested” drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

  11. Urn model for products’ shares in international trade

    Science.gov (United States)

    Barbier, Matthieu; Lee, D.-S.

    2017-12-01

    International trade fluxes evolve as countries revise their portfolios of trade products towards economic development. Accordingly products’ shares in international trade vary with time, reflecting the transfer of capital between distinct industrial sectors. Here we analyze the share of hundreds of product categories in world trade for four decades and find a scaling law obeyed by the annual variation of product share, which informs us of how capital flows and interacts over the product space. A model of stochastic transfer of capital between products based on the observed scaling relation is proposed and shown to reproduce exactly the empirical share distribution. The model allows analytic solutions as well as numerical simulations, which predict a pseudo-condensation of capital onto few product categories and when it will occur. At the individual level, our model finds certain products unpredictable, the excess or deficient growth of which with respect to the model prediction is shown to be correlated with the nature of goods.

  12. Model tracking dual stochastic controller design under irregular internal noises

    International Nuclear Information System (INIS)

    Lee, Jong Bok; Heo, Hoon; Cho, Yun Hyun; Ji, Tae Young

    2006-01-01

    Although many methods about the control of irregular external noise have been introduced and implemented, it is still necessary to design a controller that will be more effective and efficient methods to exclude for various noises. Accumulation of errors due to model tracking, internal noises (thermal noise, shot noise and l/f noise) that come from elements such as resistor, diode and transistor etc. in the circuit system and numerical errors due to digital process often destabilize the system and reduce the system performance. New stochastic controller is adopted to remove those noises using conventional controller simultaneously. Design method of a model tracking dual controller is proposed to improve the stability of system while removing external and internal noises. In the study, design process of the model tracking dual stochastic controller is introduced that improves system performance and guarantees robustness under irregular internal noises which can be created internally. The model tracking dual stochastic controller utilizing F-P-K stochastic control technique developed earlier is implemented to reveal its performance via simulation

  13. Trade and compliance cost model in the international supply chain

    NARCIS (Netherlands)

    Arsyida, Tuty; van Delft, Selma; Rukanova, B.D.; Tan, Y.

    2017-01-01

    Trade costs for international supply chain are huge, even in the absence of formal barriers. It is necessary for all the stakeholders, both private and public organizations, to support an effective and efficient border compliance process. Very little trade cost model research has been done at the

  14. Soluble Boltzmann equations for internal state and Maxwell models

    NARCIS (Netherlands)

    Futcher, E.; Hoare, M.R.; Hendriks, E.M.; Ernst, M.H.

    We consider a class of scalar nonlinear Boltzmann equations describing the evolution of a microcanonical ensemble in which sub-systems exchange internal energy ‘randomly’ in binary interactions. In the continuous variable version these models can equally be interpreted as Boltzmann equations for

  15. Desirable role in an international duopoly model with tariffs

    Science.gov (United States)

    Ferreira, Fernanda A.; Ferreira, Flávio

    2012-09-01

    In this paper, we study an international market model in which the home government imposes a tariff on the imported goods. The model has two stages. In the first stage, the home government chooses an import tariff to maximize a function that cares about the home firm's profit and the total revenue. Then, the firms engage in a Cournot or in a Stackelberg competition. We compare the results obtained in the three different ways of moving on the decision make of the firms.

  16. International Jobs and Economic Development Impacts (I-JEDI) Model

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    International Jobs and Economic Development Impacts (I-JEDI) is a freely available economic model that estimates gross economic impacts from wind, solar, biomass, and geothermal energy projects. Building on a similar model for the United States, I-JEDI was developed by the National Renewable Energy Laboratory under the U.S. government's Enhancing Capacity for Low Emission Development Strategies (EC-LEDS) program to support partner countries in assessing economic impacts of LEDS actions in the energy sector.

  17. Exploring the Efficacy and Limitations of Shock-cooling Models: New Analysis of Type II Supernovae Observed by the Kepler Mission

    Science.gov (United States)

    Rubin, Adam; Gal-Yam, Avishay

    2017-10-01

    Modern transient surveys have begun discovering and following supernovae (SNe) shortly after first light—providing systematic measurements of the rise of Type II SNe. We explore how analytic models of early shock-cooling emission from core-collapse SNe can constrain the progenitor’s radius, explosion velocity, and local host extinction. We simulate synthetic photometry in several realistic observing scenarios; assuming the models describe the typical explosions well, we find that ultraviolet observations can constrain the progenitor’s radius to a statistical uncertainty of ±10%-15%, with a systematic uncertainty of ±20%. With these observations the local host extinction (A V ) can be constrained to a factor of two and the shock velocity to ±5% with a systematic uncertainty of ±10%. We also reanalyze the SN light curves presented by Garnavich et al. (2016) and find that KSN 2011a can be fit by a blue supergiant model with a progenitor radius of {R}sred supergiant model with a progenitor radius of {R}s={111}-21({stat)-1({sys})}+89({stat)+49({sys})} {R}⊙ . Our results do not agree with those of Garnavich et al. Moreover, we re-evaluate their claims and find that there is no statistically significant evidence for a shock-breakout flare in the light curve of KSN 2011d.

  18. The internal propagation of fusion flame with the strong shock of a laser driven plasma block for advanced nuclear fuel ignition

    International Nuclear Information System (INIS)

    Malekynia, B.; Razavipour, S. S.

    2013-01-01

    An accelerated skin layer may be used to ignite solid state fuels. Detailed analyses were clarified by solving the hydrodynamic equations for nonlinear force driven plasma block ignition. In this paper, the complementary mechanisms are included for the advanced fuel ignition: external factors such as lasers, compression, shock waves, and sparks. The other category is created within the plasma fusion as reheating of an alpha particle, the Bremsstrahlung absorption, expansion, conduction, and shock waves generated by explosions. With the new condition for the control of shock waves, the spherical deuterium-tritium fuel density should be increased to 75 times that of the solid state. The threshold ignition energy flux density for advanced fuel ignition may be obtained using temperature equations, including the ones for the density profile obtained through the continuity equation and the expansion velocity for the r ≠ 0 layers. These thresholds are significantly reduced in comparison with the ignition thresholds at x = 0 for solid advanced fuels. The quantum correction for the collision frequency is applied in the case of the delay in ion heating. Under the shock wave condition, the spherical proton-boron and proton-lithium fuel densities should be increased to densities 120 and 180 times that of the solid state. These plasma compressions are achieved through a longer duration laser pulse or X-ray. (physics of gases, plasmas, and electric discharges)

  19. BANK CAPITAL AND MACROECONOMIC SHOCKS: A PRINCIPAL COMPONENTS ANALYSIS AND VECTOR ERROR CORRECTION MODEL

    Directory of Open Access Journals (Sweden)

    Christian NZENGUE PEGNET

    2011-07-01

    Full Text Available The recent financial turmoil has clearly highlighted the potential role of financial factors on amplification of macroeconomic developments and stressed the importance of analyzing the relationship between banks’ balance sheets and economic activity. This paper assesses the impact of the bank capital channel in the transmission of schocks in Europe on the basis of bank's balance sheet data. The empirical analysis is carried out through a Principal Component Analysis and in a Vector Error Correction Model.

  20. Why are Housing Prices so Volatile? Income Shocks in a Stochastic Heterogeneous-Agents Model

    OpenAIRE

    Fracois Ortalo-Magne; Sven Rady

    2000-01-01

    Building on a stochastic life-cycle model with credit constraints and heterogeneous agents and dwellings, this paper clarifies the contribution of income fluctuations to housing price volatility. First, housing prices are shown to depend on the current income of young households. Empirical evidence from the UK and the US shows that this income variable is more volatile than aggregate income. Data also suggest that the income of young households affects housing prices independently of aggregat...

  1. The Influence of Pickup Protons, from Interstellar Neutral Hydrogen, on the Propagation of Interplanetary Shocks from the Halloween 2003 Solar Events to ACE and Ulysses: A 3-D MHD Modeling Study

    Science.gov (United States)

    Detman, T. R.; Intriligator, D. S.; Dryer, M.; Sun, W.; Deehr, C. S.; Intriligator, J.

    2012-01-01

    We describe our 3-D, time ]dependent, MHD solar wind model that we recently modified to include the physics of pickup protons from interstellar neutral hydrogen. The model has a time-dependent lower boundary condition, at 0.1 AU, that is driven by source surface map files through an empirical interface module. We describe the empirical interface and its parameter tuning to maximize model agreement with background (quiet) solar wind observations at ACE. We then give results of a simulation study of the famous Halloween 2003 series of solar events. We began with shock inputs from the Fearless Forecast real ]time shock arrival prediction study, and then we iteratively adjusted input shock speeds to obtain agreement between observed and simulated shock arrival times at ACE. We then extended the model grid to 5.5 AU and compared those simulation results with Ulysses observations at 5.2 AU. Next we undertook the more difficult tuning of shock speeds and locations to get matching shock arrival times at both ACE and Ulysses. Then we ran this last case again with neutral hydrogen density set to zero, to identify the effect of pickup ions. We show that the speed of interplanetary shocks propagating from the Sun to Ulysses is reduced by the effects of pickup protons. We plan to make further improvements to the model as we continue our benchmarking process to 10 AU, comparing our results with Cassini observations, and eventually on to 100 AU, comparing our results with Voyager 1 and 2 observations.

  2. INTERNAL REGULATIONS OF INTERNATIONAL COMPANIES OPERATING IN POLAND AND TRADITIONAL FAMILY MODEL

    Directory of Open Access Journals (Sweden)

    Chojara-Sobiecka Małgorzata

    2017-12-01

    Full Text Available Most of the big companies have the internal regulations about human resources management. The bylaws in question are usually created in the reality of a particular legal system. When a company expands abroad, it starts operating in a different legal system than its own. As a result, the bylaws are not always compatible neither with laws nor the legal culture of the state of a new market. The paper touches upon the problem of the cohesion of internal regulations of some of the international companies operating in Poland with the traditional family model established in Polish law analyzing three areas such as: supporting parenting, family business, and preference for non-heterosexual persons. The conclusions are that some of the internal regulations are not coherent with Polish law, and some of the bylaws regarding, e.g., daycare or flexible working hours, can be adapted to Polish legal system. It (unclear what “it” is referring to would benefit traditional model of the family. The paper contains also the excursus about some legis-lative phenomenon regarding the reception of state law regulations issues by private companies and pos-tulates that the Polish legislator shall be open to new ideas in this matter and search for the well-tried regulations.

  3. Strain measurements during pressurized thermal shock experiment

    International Nuclear Information System (INIS)

    Tarso Vida Gomes, P. de; Julio Ricardo Barreto Cruz; Tanius Rodrigues Mansur; Denis Henrique Bianchi Scaldaferri; Miguel Mattar Neto

    2005-01-01

    For the life extension of nuclear power plants, the residual life of most of their components must be evaluated along all their operating time. Concerning the reactor pressure vessel, the pressurized thermal shock (PTS) is a very important event to be considered. For better understanding the effects of this kind of event, tests are made. The approach described here consisted of building a simplified in-scale physical model of the reactor pressure vessel, submitting it to the actual operating temperature and pressure conditions and provoking a thermal shock by means of cold water flow in its external surface. To conduct such test, the Nuclear Technology Development Center (CDTN) has been conducting several studies related to PTS and has also built a laboratory that has made possible the simulation of the PTS loading conditions. Several cracks were produced in the external surface of the reactor pressure vessel model. Strain gages were fixed by means of electrical discharge welding over the cracks regions in both external and internal surfaces. The temperature was monitored in 10 points across the vessel wall. The internal pressure was manually controlled and monitored using a pressure transducer. Two PTS experiments were conducted and this paper presents the strain measurement procedures applied to the reactor pressure vessel model, during the PTS, using strain gages experimental methodology. (authors)

  4. The Shock Wave in the ionosphere during an Earthquake

    Directory of Open Access Journals (Sweden)

    Kuznetsov Vladimir

    2016-01-01

    Full Text Available Fundamentally new model of the shock wave (SW generation in atmosphere and ionosphere during earthquake is proposed. The model proceeds from the idea of cooperative shock water crystallization in a cloud.

  5. Culture Shock in the Library: Implications for Information Literacy Instruction

    Science.gov (United States)

    Gilton, Donna Louise

    2005-01-01

    A tremendous amount has been written on culture shock experienced by people who leave their own cultures for another. This essay defines and describes culture shock and clash in general, discusses the literature related to different aspects of culture shock as it relates to international students, describes other related library literature,…

  6. Type II Supernova Energetics and Comparison of Light Curves to Shock-Cooling Models

    Science.gov (United States)

    Rubin, Adam; Gal-Yam, Avishay; Cia, Annalisa De; Horesh, Assaf; Khazov, Danny; Ofek, Eran O.; Kulkarni, S. R.; Arcavi, Iair; Manulis, Ilan; Cenko, S. Bradley

    2016-01-01

    During the first few days after explosion, Type II supernovae (SNe) are dominated by relatively simple physics. Theoretical predictions regarding early-time SN light curves in the ultraviolet (UV) and optical bands are thus quite robust. We present, for the first time, a sample of 57 R-band SN II light curves that are well-monitored during their rise, with greater than 5 detections during the first 10 days after discovery, and a well-constrained time of explosion to within 13 days. We show that the energy per unit mass (E/M) can be deduced to roughly a factor of five by comparing early-time optical data to the 2011 model of Rabinak Waxman, while the progenitor radius cannot be determined based on R-band data alone. We find that SN II explosion energies span a range of EM = (0.2-20) x 10(exp 51) erg/(10 M stellar mass), and have a mean energy per unit mass of E/ M = 0.85 x 10(exp 51) erg(10 stellar mass), corrected for Malmquist bias. Assuming a small spread in progenitor masses, this indicates a large intrinsic diversity in explosion energy. Moreover, E/M is positively correlated with the amount of Ni-56 produced in the explosion, as predicted by some recent models of core-collapse SNe. We further present several empirical correlations. The peak magnitude is correlated with the decline rate (Delta m(sub15), the decline rate is weakly correlated with the rise time, and the rise time is not significantly correlated with the peak magnitude. Faster declining SNe are more luminous and have longer rise times. This limits the possible power sources for such events.

  7. Preface: International Reference Ionosphere - Progress in Ionospheric Modelling

    Science.gov (United States)

    Bilitza Dieter; Reinisch, Bodo

    2010-01-01

    The international reference ionosphere (lRI) is the internationally recommended empirical model for the specification of ionospheric parameters supported by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) and recognized by the International Standardization Organization (ISO). IRI is being continually improved by a team of international experts as new data become available and better models are being developed. This issue chronicles the latest phase of model updates as reported during two IRI-related meetings. The first was a special session during the Scientific Assembly of the Committee of Space Research (COSPAR) in Montreal, Canada in July 2008 and the second was an IRI Task Force Activity at the US Air Force Academy in Colorado Springs in May 2009. This work led to several improvements and additions of the model which will be included in the next version, IRI-201O. The issue is divided into three sections focusing on the improvements made in the topside ionosphere, the F-peak, and the lower ionosphere, respectively. This issue would not have been possible without the reviewing efforts of many individuals. Each paper was reviewed by two referees. We thankfully acknowledge the contribution to this issue made by the following reviewers: Jacob Adeniyi, David Altadill, Eduardo Araujo, Feza Arikan, Dieter Bilitza, Jilijana Cander, Bela Fejer, Tamara Gulyaeva, Manuel Hermindez-Pajares, Ivan Kutiev, John MacDougal, Leo McNamara, Bruno Nava, Olivier Obrou, Elijah Oyeyemi, Vadym Paznukhov, Bodo Reinisch, John Retterer, Phil Richards, Gary Sales, J.H. Sastri, Ludger Scherliess, Iwona Stanislavska, Stamir Stankov, Shin-Yi Su, Manlian Zhang, Y ongliang Zhang, and Irina Zakharenkova. We are grateful to Peggy Ann Shea for her final review and guidance as the editor-in-chief for special issues of Advances in Space Research. We thank the authors for their timely submission and their quick response to the reviewer comments and humbly

  8. The International Reference Ionosphere 2012 – a model of international collaboration

    Czech Academy of Sciences Publication Activity Database

    Bilitza, D.; Altadill, D.; Zhang, Y.; Mertens, Ch.; Truhlík, Vladimír; Richards, P.; McKinnell, L.- A.; Reinisch, B.

    2014-01-01

    Roč. 4, 20 February (2014), A07/1-A07/12 ISSN 2115-7251 R&D Projects: GA MŠk(CZ) LH11123 Institutional support: RVO:68378289 Keywords : International Reference Ionosphere * empirical models * plasma parameters * real - time IRI Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.558, year: 2014 http://www.swsc-journal.org/articles/swsc/abs/2014/01/swsc130043/swsc130043.html

  9. A comprehensive gaze stabilization controller based on cerebellar internal models

    DEFF Research Database (Denmark)

    Vannucci, Lorenzo; Falotico, Egidio; Tolu, Silvia

    2017-01-01

    based on the coordination of VCR and VOR and OKR. The model, inspired by neuroscientific cerebellar theories, is provided with learning and adaptation capabilities based on internal models. We present the results for the gaze stabilization model on three sets of experiments conducted on the SABIAN robot...... and on the iCub simulator, validating the robustness of the proposed control method. The first set of experiments focused on the controller response to a set of disturbance frequencies along the vertical plane. The second shows the performances of the system under three-dimensional disturbances. The last set...

  10. A conflict model for the international hazardous waste disposal dispute

    International Nuclear Information System (INIS)

    Hu Kaixian; Hipel, Keith W.; Fang, Liping

    2009-01-01

    A multi-stage conflict model is developed to analyze international hazardous waste disposal disputes. More specifically, the ongoing toxic waste conflicts are divided into two stages consisting of the dumping prevention and dispute resolution stages. The modeling and analyses, based on the methodology of graph model for conflict resolution (GMCR), are used in both stages in order to grasp the structure and implications of a given conflict from a strategic viewpoint. Furthermore, a specific case study is investigated for the Ivory Coast hazardous waste conflict. In addition to the stability analysis, sensitivity and attitude analyses are conducted to capture various strategic features of this type of complicated dispute.

  11. International Conference on Computational Intelligence, Cyber Security, and Computational Models

    CERN Document Server

    Ramasamy, Vijayalakshmi; Sheen, Shina; Veeramani, C; Bonato, Anthony; Batten, Lynn

    2016-01-01

    This book aims at promoting high-quality research by researchers and practitioners from academia and industry at the International Conference on Computational Intelligence, Cyber Security, and Computational Models ICC3 2015 organized by PSG College of Technology, Coimbatore, India during December 17 – 19, 2015. This book enriches with innovations in broad areas of research like computational modeling, computational intelligence and cyber security. These emerging inter disciplinary research areas have helped to solve multifaceted problems and gained lot of attention in recent years. This encompasses theory and applications, to provide design, analysis and modeling of the aforementioned key areas.

  12. Shock loads induced on metal structures by LHC proton beams: modelling of thermo-mechanical effects

    CERN Document Server

    Peroni, L; Dallocchio, A; Bertarelli, A

    2011-01-01

    In this work, the numerical simulations of the LHC high energy particle beam impact against a metal structure are performed using the commercial FEM code LS-DYNA. The evaluation of thermal loads on the hit material is performed using a statistical code, called FLUKA, based on the Monte-Carlo method, which returns an energy map on a particular geometry (taking into account all the particles in the cascade generated by the interaction between the proton beam and the target). The FLUKA results are then used as input for thermo-structural studies. The first step of this work is the validation of the numerical procedure on a simple geometry for two different materials (copper and tungsten) and constitutive material models. In particular, the high energy particle impact is examined on a facially irradiated cylindrical bar: the beam hits the component directly on the centre of the basis. Then the final step is the study of the impact on a real structure with an energy beam of 5 TeV (the next target in the energy val...

  13. Shock-induced deformation twinning in tantalum

    International Nuclear Information System (INIS)

    Murr, L.E.; Niou, C.S.; Pappu, S.; Kennedy, C.; Meyers, M.A.; Chen, Y.J.

    1997-01-01

    Shock-wave deformation of tantalum to a pressure of 45 GPa and duration of 1.8 micros generates profuse twinning. The post-shock mechanical response is significantly affected, with shock hardening exceeding the expected hardening due to the transient shock strain ε s = (4/3)ln(V/V 0 ); this enhanced hardening, and other alterations in response, are attributed to the barriers presented to plastic deformation by the deformation twins. A constitutive model is proposed that predicts the threshold shock stress for mechanical twinning; it is based on the application of the Swegle-Grady relationship between shock stress and strain rate to constitute equations describing the critical stress for slip and twinning. This constitutive model incorporates grain-size effects and predicts a threshold twinning stress that is a function of temperature and grain size; predictions of the model are in qualitative agreement with experimental results

  14. A systematic comparison of two-equation Reynolds-averaged Navier-Stokes turbulence models applied to shock-cloud interactions

    Science.gov (United States)

    Goodson, Matthew D.; Heitsch, Fabian; Eklund, Karl; Williams, Virginia A.

    2017-07-01

    Turbulence models attempt to account for unresolved dynamics and diffusion in hydrodynamical simulations. We develop a common framework for two-equation Reynolds-averaged Navier-Stokes turbulence models, and we implement six models in the athena code. We verify each implementation with the standard subsonic mixing layer, although the level of agreement depends on the definition of the mixing layer width. We then test the validity of each model into the supersonic regime, showing that compressibility corrections can improve agreement with experiment. For models with buoyancy effects, we also verify our implementation via the growth of the Rayleigh-Taylor instability in a stratified medium. The models are then applied to the ubiquitous astrophysical shock-cloud interaction in three dimensions. We focus on the mixing of shock and cloud material, comparing results from turbulence models to high-resolution simulations (up to 200 cells per cloud radius) and ensemble-averaged simulations. We find that the turbulence models lead to increased spreading and mixing of the cloud, although no two models predict the same result. Increased mixing is also observed in inviscid simulations at resolutions greater than 100 cells per radius, which suggests that the turbulent mixing begins to be resolved.

  15. Mathematical and numerical study of nonlinear hyperbolic equations: model coupling and nonclassical shocks

    International Nuclear Information System (INIS)

    Boutin, B.

    2009-11-01

    This thesis concerns the mathematical and numerical study of nonlinear hyperbolic partial differential equations. A first part deals with an emergent problematic: the coupling of hyperbolic equations. The pursued applications are linked with the mathematical coupling of computing platforms, dedicated to an adaptative simulation of multi-scale phenomena. We propose and analyze a new coupling formalism based on extended PDE systems avoiding the geometric treatment of the interfaces. In addition, it allows to formulate the problem in a multidimensional setting, with possible covering of the coupled models. This formalism allows in particular to equip the coupling procedure with viscous regularization mechanisms, useful in the selection of natural discontinuous solutions. We analyze existence and uniqueness in the framework of a parabolic regularization a la Dafermos. Existence of a solution holds true under very general conditions but failure of uniqueness may naturally arise as soon as resonance occurs at the interfaces. Next, we highlight that our extended PDE framework gives rise to another regularization strategy based on thick interfaces. In this setting, we prove existence and uniqueness of the solutions of the Cauchy problem for initial data in L ∞ . The main tool consists in the derivation of a flexible and robust finite volume method for general triangulation which is analyzed in the setting of entropy measure-valued solutions by DiPerna. The second part is devoted to the definition of a finite volume scheme for the computing of nonclassical solutions of a scalar conservation law based on a kinetic relation. This scheme offers the feature to be stricto sensu conservative, in opposition to a Glimm approach that is only statistically conservative. The validity of our approach is illustrated through numerical examples. (author)

  16. Internal variability in a regional climate model over West Africa

    Energy Technology Data Exchange (ETDEWEB)

    Vanvyve, Emilie; Ypersele, Jean-Pascal van [Universite catholique de Louvain, Institut d' astronomie et de geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Hall, Nicholas [Laboratoire d' Etudes en Geophysique et Oceanographie Spatiales/Centre National d' Etudes Spatiales, Toulouse Cedex 9 (France); Messager, Christophe [University of Leeds, Institute for Atmospheric Science, Environment, School of Earth and Environment, Leeds (United Kingdom); Leroux, Stephanie [Universite Joseph Fourier, Laboratoire d' etude des Transferts en Hydrologie et Environnement, BP53, Grenoble Cedex 9 (France)

    2008-02-15

    Sensitivity studies with regional climate models are often performed on the basis of a few simulations for which the difference is analysed and the statistical significance is often taken for granted. In this study we present some simple measures of the confidence limits for these types of experiments by analysing the internal variability of a regional climate model run over West Africa. Two 1-year long simulations, differing only in their initial conditions, are compared. The difference between the two runs gives a measure of the internal variability of the model and an indication of which timescales are reliable for analysis. The results are analysed for a range of timescales and spatial scales, and quantitative measures of the confidence limits for regional model simulations are diagnosed for a selection of study areas for rainfall, low level temperature and wind. As the averaging period or spatial scale is increased, the signal due to internal variability gets smaller and confidence in the simulations increases. This occurs more rapidly for variations in precipitation, which appear essentially random, than for dynamical variables, which show some organisation on larger scales. (orig.)

  17. Non-equilibrium effects of diatomic and polyatomic gases on the shock-vortex interaction based on the second-order constitutive model of the Boltzmann-Curtiss equation

    Science.gov (United States)

    Singh, S.; Karchani, A.; Myong, R. S.

    2018-01-01

    The rotational mode of molecules plays a critical role in the behavior of diatomic and polyatomic gases away from equilibrium. In order to investigate the essence of the non-equilibrium effects, the shock-vortex interaction problem was investigated by employing an explicit modal discontinuous Galerkin method. In particular, the first- and second-order constitutive models for diatomic and polyatomic gases derived rigorously from the Boltzmann-Curtiss kinetic equation were solved in conjunction with the physical conservation laws. As compared with a monatomic gas, the non-equilibrium effects result in a substantial change in flow fields in both macroscale and microscale shock-vortex interactions. Specifically, the computational results showed three major effects of diatomic and polyatomic gases on the shock-vortex interaction: (i) the generation of the third sound waves and additional reflected shock waves with strong and enlarged expansion, (ii) the dominance of viscous vorticity generation, and (iii) an increase in enstrophy with increasing bulk viscosity, related to the rotational mode of gas molecules. Moreover, it was shown that there is a significant discrepancy in flow fields between the microscale and macroscale shock-vortex interactions in diatomic and polyatomic gases. The quadrupolar acoustic wave source structures, which are typically observed in macroscale shock-vortex interactions, were not found in any microscale shock-vortex interactions. The physics of the shock-vortex interaction was also investigated in detail to examine vortex deformation and evolution dynamics over an incident shock wave. A comparative study of first- and second-order constitutive models was also conducted for the enstrophy and dissipation rate. Finally, the study was extended to the shock-vortex pair interaction case to examine the effects of pair interaction on vortex deformation and evolution dynamics.

  18. Full-field initialized decadal predictions with the MPI earth system model: an initial shock in the North Atlantic

    Science.gov (United States)

    Kröger, Jürgen; Pohlmann, Holger; Sienz, Frank; Marotzke, Jochem; Baehr, Johanna; Köhl, Armin; Modali, Kameswarrao; Polkova, Iuliia; Stammer, Detlef; Vamborg, Freja S. E.; Müller, Wolfgang A.

    2017-12-01

    Our decadal climate prediction system, which is based on the Max-Planck-Institute Earth System Model, is initialized from a coupled assimilation run that utilizes nudging to selected state parameters from reanalyses. We apply full-field nudging in the atmosphere and either full-field or anomaly nudging in the ocean. Full fields from two different ocean reanalyses are considered. This comparison of initialization strategies focuses on the North Atlantic Subpolar Gyre (SPG) region, where the transition from anomaly to full-field nudging reveals large differences in prediction skill for sea surface temperature and ocean heat content (OHC). We show that nudging of temperature and salinity in the ocean modifies OHC and also induces changes in mass and heat transports associated with the ocean flow. In the SPG region, the assimilated OHC signal resembles well OHC from observations, regardless of using full fields or anomalies. The resulting ocean transport, on the other hand, reveals considerable differences between full-field and anomaly nudging. In all assimilation runs, ocean heat transport together with net heat exchange at the surface does not correspond to OHC tendencies, the SPG heat budget is not closed. Discrepancies in the budget in the cases of full-field nudging exceed those in the case of anomaly nudging by a factor of 2-3. The nudging-induced changes in ocean transport continue to be present in the free running hindcasts for up to 5 years, a clear expression of memory in our coupled system. In hindcast mode, on annual to inter-annual scales, ocean heat transport is the dominant driver of SPG OHC. Thus, we ascribe a significant reduction in OHC prediction skill when using full-field instead of anomaly initialization to an initialization shock resulting from the poor initialization of the ocean flow.

  19. A novel small heat shock protein of Haliotis discus hannai: characterization, structure modeling, and expression profiles under environmental stresses.

    Science.gov (United States)

    Sun, Bo-Guang; Hu, Yong-Hua

    2016-07-01

    Small heat shock proteins (sHsps) are a class of chaperones with low molecular weight, feathered by a C-terminal α-crystallin domain (ACD). They participate in reestablishing the stability of partially denatured proteins and therefore contribute to cellular homeostasis. In this work, we identified a sHsp homolog (designated as sHsp19) from Haliotis discus hannai, an economically important farmed mollusk in East Asia. sHsp19 possesses a sHsp hallmark domain, which exhibits the typical fold of ACD as revealed by a three-dimensional model constructed through an iterative threading assembly refinement method. The amino acid sequence sHsp19 shares low identities with any other known sHsps, with percentages below 35 %. Besides, sHsp19 shows relatively distant phylogenetic relationships with sHsps of various mollusks, including two other identified sHsps of abalone subspecies. qRT-PCR analysis indicated that the expression of sHsp19 occurred in multiple tissues. Upon exposure to thermal, oxidative, and multiple toxic metal stresses, the level of sHsp19 mRNA was rapidly elevated in a persistent fashion, with the maximum increase up to 170.58-, 405.84-, and 361.96-fold, respectively. These results indicate sHsp is a novel sHsp that possesses the distinguishing structural feature of sHsps but has remote homologies with known sHsps. It is likely to be important in stress adaptation of abalone and may be applied as a bioindicator for monitoring pollution or detrimental changes of environment in abalone culture.

  20. Propofol prevents electroconvulsive-shock-induced memory impairment through regulation of hippocampal synaptic plasticity in a rat model of depression

    Directory of Open Access Journals (Sweden)

    Luo J

    2014-09-01

    Full Text Available Jie Luo, Su Min, Ke Wei, Jun Cao, Bin Wang, Ping Li, Jun Dong, Yuanyuan Liu Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China Background: Although a rapid and efficient psychiatric treatment, electroconvulsive therapy (ECT induces memory impairment. Modified ECT requires anesthesia for safety purposes. Although traditionally found to exert amnesic effects in general anesthesia, which is an inherent part of modified ECT, some anesthetics have been found to protect against ECT-induced cognitive impairment. However, the mechanisms remain unclear. We investigated the effects of propofol (2,6-diisopropylphenol on memory in depressed rats undergoing electroconvulsive shock (ECS, the analog of ECT in animals, under anesthesia as well as its mechanisms.Methods: Chronic unpredictable mild stresses were adopted to reproduce depression in a rodent model. Rats underwent ECS (or sham ECS with anesthesia with propofol or normal saline. Behavior was assessed in sucrose preference, open field and Morris water maze tests. Hippocampal long-term potentiation (LTP was measured using electrophysiological techniques. PSD-95, CREB, and p-CREB protein expression was assayed with western blotting.Results: Depression induced memory damage, and downregulated LTP, PSD-95, CREB, and p-CREB; these effects were exacerbated in depressed rats by ECS; propofol did not reverse the depression-induced changes, but when administered in modified ECS, propofol improved memory and reversed the downregulation of LTP and the proteins. Conclusion: These findings suggest that propofol prevents ECS-induced memory impairment, and modified ECS under anesthesia with propofol improves memory in depressed rats, possibly by reversing the excessive changes in hippocampal synaptic plasticity. These observations provide a novel insight into potential targets for optimizing the clinical use of ECT for psychiatric

  1. A model of strategic marketing alliances for hospices: vertical, internal, osmotic alliances and the complete model.

    Science.gov (United States)

    Starnes, B J; Self, D R

    1999-01-01

    This article develops two previous research efforts. William J. Winston (1994, 1995) has proposed a set of strategies by which health care organizations can benefit from forging strategic alliances. Raadt and Self (1997) have proposed a classification model of alliances including horizontal, vertical, internal, and osmotic. In the second of two articles, this paper presents a model of vertical, internal, and osmotic alliances. Advantages and disadvantages of each are discussed. Finally, the complete alliance system model is presented.

  2. Environmental indicators and international models for making decision

    International Nuclear Information System (INIS)

    Polanco, Camilo

    2006-01-01

    The last international features proposed by the Organization for Economic Cooperation Development (OECD) and United Nations (UN) are analyzed in the use of the environmental indicators, in typology, selection criteria, and models, for organizing the information for management, environmental performance, and decision making. The advantages and disadvantages of each model are analyzed, as well as their environmental index characteristics. The analyzed models are Pressure - State - Response (PSR) and its conceptual developments: Driving Force - State Response (DSR), Driving Force - Pressure - State - Impact - Response (DPSIR), Model- Flow-Quality (MFQ), Pressure - State - Impact - Effect - Response (PSIER), and, finally, Pressure-State - Impact - Effect - Response - Management (PSIERM). The use of one or another model will depend on the quality of the available information, as well as on the proposed objectives

  3. Modelling and Internal Fuzzy Model Power Control of a Francis Water Turbine

    Directory of Open Access Journals (Sweden)

    Klemen Nagode

    2014-02-01

    Full Text Available This paper presents dynamic modelling of a Francis turbine with a surge tank and the control of a hydro power plant (HPP. Non-linear and linear models include technical parameters and show high similarity to measurement data. Turbine power control with an internal model control (IMC is proposed, based on a turbine fuzzy model. Considering appropriate control responses in the entire area of turbine power, the model parameters of the process are determined from a fuzzy model, which are further included in the internal model controller. The results are compared to a proportional-integral (PI controller tuned with an integral absolute error (IAE objective function, and show an improved response of internal model control.

  4. Collisionless electrostatic shocks

    DEFF Research Database (Denmark)

    Andersen, H.K.; Andersen, S.A.; Jensen, Vagn Orla

    1970-01-01

    An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth......An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth...

  5. Comparison of extracorporeal shock wave lithotripsy running models between outsourcing cooperation and rental cooperation conducted in Taiwan.

    Science.gov (United States)

    Liu, Chih-Kuang; Ko, Ming-Chung; Chen, Shiou-Sheng; Lee, Wen-Kai; Shia, Ben-Chang; Chiang, Han-Sun

    2015-02-01

    We conducted a retrospective study to compare the cost and effectiveness between two different running models for extracorporeal shock wave lithotripsy (SWL), including the outsourcing cooperation model (OC) and the rental cooperation model (RC). Between January 1999 and December 2005, we implemented OC for the SWL, and from January 2006 to October 2011, RC was utilized. With OC, the cooperative company provided a machine and shared a variable payment with the hospital, according to treatment sessions. With RC, the cooperative company provided a machine and received a fixed rent from the hospital. We calculated the cost of each treatment session, and evaluated the break-even point to estimate the lowest number of treatment sessions to make the balance between revenue and cost every month. Effectiveness parameters, including the stone-free rate, the retreatment rate, the rate of additional procedures and complications, were evaluated. Compared with OC there were significantly less treatment sessions for RC every month (42.6±7.8 vs. 36.8±6.5, p=0.01). The cost of each treatment session was significantly higher for OC than for RC (751.6±20.0 USD vs. 684.7±16.7 USD, p=0.01). The break-even point for the hospital was 27.5 treatment sessions/month for OC, when the hospital obtained 40% of the payment, and it could be reduced if the hospital got a greater percentage. The break-even point for the hospital was 27.3 treatment sessions/month for RC. No significant differences were noticed for the stone-free rate, the retreatment rate, the rate of additional procedures and complications. Our study revealed that RC had a lower cost for every treatment session, and fewer treatment sessions of SWL/month than OC. The study might provide a managerial implication for healthcare organization managers, when they face a situation of high price equipment investment. Copyright © 2012. Published by Elsevier B.V.

  6. Wind Magnetic Clouds for the Period 2013 - 2015: Model Fitting, Types, Associated Shock Waves, and Comparisons to Other Periods

    Science.gov (United States)

    Lepping, R. P.; Wu, C.-C.; Berdichevsky, D. B.; Szabo, A.

    2018-04-01

    We give the results of parameter fitting of the magnetic clouds (MCs) observed by the Wind spacecraft for the three-year period 2013 to the end of 2015 (called the "Present" period) using the MC model of Lepping, Jones, and Burlaga ( J. Geophys. Res. 95, 11957, 1990). The Present period is almost coincident with the solar maximum of the sunspot number, which has a broad peak starting in about 2012 and extending to almost 2015. There were 49 MCs identified in the Present period. The modeling gives MC quantities such as size, axial attitude, field handedness, axial magnetic-field strength, center time, and closest-approach vector. Derived quantities are also estimated, such as axial magnetic flux, axial current density, and total axial current. Quality estimates are assigned representing excellent, fair/good, and poor. We provide error estimates on the specific fit parameters for the individual MCs, where the poor cases are excluded. Model-fitting results that are based on the Present period are compared to the results of the full Wind mission from 1995 to the end of 2015 (Long-term period), and compared to the results of two other recent studies that encompassed the periods 2007 - 2009 and 2010 - 2012, inclusive. We see that during the Present period, the MCs are, on average, slightly slower, slightly weaker in axial magnetic field (by 8.7%), and larger in diameter (by 6.5%) than those in the Long-term period. However, in most respects, the MCs in the Present period are significantly closer in characteristics to those of the Long-term period than to those of the two recent three-year periods. However, the rate of occurrence of MCs for the Long-term period is 10.3 year^{-1}, whereas this rate for the Present period is 16.3 year^{-1}, similar to that of the period 2010 - 2012. Hence, the MC occurrence rate has increased appreciably in the last six years. MC Type (N-S, S-N, All N, All S, etc.) is assigned to each MC; there is an inordinately large percentage of All S

  7. Radioactive waste management. International projects on biosphere modelling

    International Nuclear Information System (INIS)

    Carboneras, P.; Cancio, D.

    1993-01-01

    The paper presents a general overview and discussion on the state of art concerning the biospheric transfer and accumulation of contaminants. A special emphasis is given to the progress achieved in the field of radioactive contaminants and particularly to those implied in radioactive waste disposal. The objectives and advances of the international projects BIOMOVS and VAMP on validation of model predictions are also described. (Author)

  8. Internal Catchment Data for Improved Model Diagnosis and Calibration

    Science.gov (United States)

    Goodrich, D. C.; Srinivasan, M.; McMillan, H.; Duncan, M.; Yatheendradas, S.; Wagener, T.; Clark, M.; Martinez, G.; Gupta, H.; Jackson, B.; Schmidt, J.; Woods, R.

    2008-12-01

    There have been numerous calls for the need to incorporate internal catchment observations for improving distributed catchment models. Recent results from a synthetic study by van Werkhoven et al., (GRL, 2008) imply that the relative worth of internal catchment observations for providing information to improve downstream predictions is limited to a time-varying zone, or cone of influence - that is, different observing points have explanatory power for different parts of the catchment at different times. In their study the spatial extent of this cone of influence is significantly influenced by a number of factors; primarily spatiotemporal precipitation patterns; but also initial conditions and inherent observational and model uncertainties. To explore this concept further two intensively instrumented experimental catchments, near end members of the hydro-climatic spectrum, with extensive internal observations were selected. The first is the 50 square kilometer Mahurangi Experimental Catchment located on the north island of New Zealand with mean annual rainfall and runoff of approximately 1700, and 870 mm, respectively. The second is the 148 square kilometer Walnut Gulch Experimental Watershed located in southeast Arizona, USA with respective mean annual rainfall and runoff of 325, and 2 mm. Data analysis and stepwise, spatially-explicit model calibration was conducted in each of these watersheds. Results from these analyses, in the context of the worth of internal runoff observations will be presented. van Werkhoven, K., T. Wagener, P. Reed, and Y. Tang (2008), Rainfall characteristics define the value of streamflow observations for distributed watershed model identification, Geophys. Res. Lett., 35, L11403, doi:10.1029/2008GL034162.

  9. International Digital Elevation Model Service (IDEMS): A Revived IAG Service

    Science.gov (United States)

    Kelly, K. M.; Hirt, C., , Dr; Kuhn, M.; Barzaghi, R.

    2017-12-01

    A newly developed International Digital Elevation Model Service (IDEMS) is now available under the umbrella of the International Gravity Field Service of the International Association of Geodesy. Hosted and operated by Environmental Systems Research Institute (Esri) (http://www.esri.com/), the new IDEMS website is available at: https://idems.maps.arcgis.com/home/index.html. IDEMS provides a focus for distribution of data and information about various digital elevation models, including spherical-harmonic models of Earth's global topography and lunar and planetary DEM. Related datasets, such as representation of inland water within DEMs, and relevant software which are available in the public domain are also provided. Currently, IDEMS serves as repository of links to providers of global terrain and bathymetry, terrain related Earth models and datasets such as digital elevation data services managed and maintained by Esri (Terrain and TopoBathy), Bedmap2-Ice thickness and subglacial topographic model of Antarctica and Ice, Cloud, and Land Elevation ICESat/GLAS Data, as well as planetary terrain data provided by PDS Geosciences Node at Washington University, St. Louis. These services provide online access to a collection of multi-resolution and multi-source elevation and bathymetry data, including metadata and source information. In addition to IDEMS current holdings of terrestrial and planetary DEMs, some topography related products IDEMS may include in future are: dynamic ocean topography, 3D crustal density models, Earth's dynamic topography, etc. IDEMS may also consider terrain related products such as quality assessments, global terrain corrections, global height anomaly-to-geoid height corrections and other geodesy-relevant studies and products. IDEMS encourages contributions to the site from the geodetic community in any of the product types listed above. Please contact the authors if you would like to contribute or recommend content you think appropriate for

  10. Entropy Generation Across Earth's Bow Shock

    Science.gov (United States)

    Parks, George K.; McCarthy, Michael; Fu, Suiyan; Lee E. s; Cao, Jinbin; Goldstein, Melvyn L.; Canu, Patrick; Dandouras, Iannis S.; Reme, Henri; Fazakerley, Andrew; hide

    2011-01-01

    Earth's bow shock is a transition layer that causes an irreversible change in the state of plasma that is stationary in time. Theories predict entropy increases across the bow shock but entropy has never been directly measured. Cluster and Double Star plasma experiments measure 3D plasma distributions upstream and downstream of the bow shock that allow calculation of Boltzmann's entropy function H and his famous H-theorem, dH/dt O. We present the first direct measurements of entropy density changes across Earth's bow shock. We will show that this entropy generation may be part of the processes that produce the non-thermal plasma distributions is consistent with a kinetic entropy flux model derived from the collisionless Boltzmann equation, giving strong support that solar wind's total entropy across the bow shock remains unchanged. As far as we know, our results are not explained by any existing shock models and should be of interests to theorists.

  11. Equation of state for potassium in shock waves at high pressures

    Science.gov (United States)

    Khishchenko, K. V.

    2018-01-01

    A simple caloric equation-of-state model, which relates the pressure with density and internal energy, is applied for potassium in the bcc-solid and liquid phases. Thermodynamic characteristics along the principal Hugoniot are calculated for the metal and compared with available data from shock-wave experiments at high pressures.

  12. Four-Stroke, Internal Combustion Engine Performance Modeling

    Science.gov (United States)

    Wagner, Richard C.

    In this thesis, two models of four-stroke, internal combustion engines are created and compared. The first model predicts the intake and exhaust processes using isentropic flow equations augmented by discharge coefficients. The second model predicts the intake and exhaust processes using a compressible, time-accurate, Quasi-One-Dimensional (Q1D) approach. Both models employ the same heat release and reduced-order modeling of the cylinder charge. Both include friction and cylinder loss models so that the predicted performance values can be compared to measurements. The results indicate that the isentropic-based model neglects important fluid mechanics and returns inaccurate results. The Q1D flow model, combined with the reduced-order model of the cylinder charge, is able to capture the dominant intake and exhaust fluid mechanics and produces results that compare well with measurement. Fluid friction, convective heat transfer, piston ring and skirt friction and temperature-varying specific heats in the working fluids are all shown to be significant factors in engine performance predictions. Charge blowby is shown to play a lesser role.

  13. On Parametric Sensitivity of Reynolds-Averaged Navier-Stokes SST Turbulence Model: 2D Hypersonic Shock-Wave Boundary Layer Interactions

    Science.gov (United States)

    Brown, James L.

    2014-01-01

    Examined is sensitivity of separation extent, wall pressure and heating to variation of primary input flow parameters, such as Mach and Reynolds numbers and shock strength, for 2D and Axisymmetric Hypersonic Shock Wave Turbulent Boundary Layer interactions obtained by Navier-Stokes methods using the SST turbulence model. Baseline parametric sensitivity response is provided in part by comparison with vetted experiments, and in part through updated correlations based on free interaction theory concepts. A recent database compilation of hypersonic 2D shock-wave/turbulent boundary layer experiments extensively used in a prior related uncertainty analysis provides the foundation for this updated correlation approach, as well as for more conventional validation. The primary CFD method for this work is DPLR, one of NASA's real-gas aerothermodynamic production RANS codes. Comparisons are also made with CFL3D, one of NASA's mature perfect-gas RANS codes. Deficiencies in predicted separation response of RANS/SST solutions to parametric variations of test conditions are summarized, along with recommendations as to future turbulence approach.

  14. Mercury's Internal Magnetic Field: Modeling Core Fields with Smooth Inversions

    Science.gov (United States)

    Uno, H.; Johnson, C. L.; Anderson, B. J.; Korth, H.; Purucker, M. E.; Solomon, S. C.

    2008-12-01

    MESSENGER's second flyby (M2) of Mercury on 6 October 2008 will provide significantly improved geographical sampling of the planet's internal magnetic field over previous measurements. Latitudinal coverage and spacecraft altitudes will be similar to those during MESSENGER's first encounter (M1), but the spacecraft trajectory will be displaced by about 180° in longitude, yielding the first magnetic measurements in the western hemisphere. We investigate spatial structure in Mercury's internal magnetic field by applying methods from inverse theory to construct low-degree-and-order spherical harmonic models. External fields predicted by a parameterized magnetospheric model are subtracted from the vector field observations. The approach takes into account noise contributions from long-wavelength uncertainties in the external field models, unexplained short-wavelength features, and spacecraft attitude errors. We investigate the effect of different regularization (smoothness) constraints on our inversions. Analyses of data from M1 and the two Mariner 10 flybys that penetrated the magnetosphere yield a preferred spherical harmonic solution to degree and order eight with the centered, axial dipole term g10 dominating. The model shows structure at low and mid-latitude regions near the flybys. Terms predicted by an analytical model for long- wavelength crustal fields - namely g10, g30 and g32 - are present, but their relative amplitudes are not consistent with such a field. We conclude that structure in our models is dominated by core, rather than by crustal, fields. We also investigate, through simulations, field morphologies that are recoverable while the spacecraft is in orbit about Mercury, under the assumption that the long-wavelength contributions from external sources can be accurately modeled and removed. Although the elliptical orbit of MESSENGER will impede the recovery of southern hemisphere structure, we obtain excellent recovery of the dipole field and of

  15. Particle Acceleration in Two Converging Shocks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin; Wang, Na; Shan, Hao [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011 (China); Giacalone, Joe [Lunar and Planetary Laboratory, University of Arizona, Tucson AZ 85721 (United States); Yan, Yihua [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing 100012 (China); Ding, Mingde, E-mail: wangxin@xao.ac.cn [Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education, Nanjing 210093 (China)

    2017-06-20

    Observations by spacecraft such as ACE , STEREO , and others show that there are proton spectral “breaks” with energy E {sub br} at 1–10 MeV in some large CME-driven shocks. Generally, a single shock with the diffusive acceleration mechanism would not predict the “broken” energy spectrum. The present paper focuses on two converging shocks to identify this energy spectral feature. In this case, the converging shocks comprise one forward CME-driven shock on 2006 December 13 and another backward Earth bow shock. We simulate the detailed particle acceleration processes in the region of the converging shocks using the Monte Carlo method. As a result, we not only obtain an extended energy spectrum with an energy “tail” up to a few 10 MeV higher than that in previous single shock model, but also we find an energy spectral “break” occurring on ∼5.5 MeV. The predicted energy spectral shape is consistent with observations from multiple spacecraft. The spectral “break,” then, in this case is caused by the interaction between the CME shock and Earth’s bow shock, and otherwise would not be present if Earth were not in the path of the CME.

  16. Intense Shock Waves and Strongly Coupled Plasmas

    Science.gov (United States)

    Fortov, Vladimir

    2005-07-01

    The report presents the recent results of experimental investigations of equations of state, compositions, thermodynamical and transport properties, electrical conductivity and opacity of strongly coupled plasmas generated by intense shock and rarefaction waves. The experimental methods for generation of high energy densities in matter, drivers for shock waves and fast diagnostic tools are discussed. Application of intense shock waves to solid and porous targets generates nonideal plasmas in megabar-gigabar pressure range. Compression of plasma by a series of reverberating shock waves allows us to decrease irreversible heating effects. To increase the irreversibility effects and to generate high temperature plasma states the experiments on shock compression of porous samples (fine metal powder, aerogels) were performed. The adiabatic expansion of matter initially compressed by intense shocks up to megabars allows investigating the intermediate region between the solid and vapor phase of nonideal plasmas, including the metal-insulator transition phase and the high temperature saturation curve with critical points of metals. The shock-wave-induced non-equilibrium phenomena at fast melting, spallation and adiabatic condensation are analyzed in the framework of the interspinodal decomposition model. The spall strength of single and polycrystal metals at extremely fast deformation produced by fast shock waves is discussed. The ``pressure ionization'' phenomena in hydrogen, helium, argon, xenon, krypton, neon, iodine, silica, sulfur, fullerenes, and some metals are analyzed on the base of multiple shock compression experiments. For some simple metals (Li, Na, Ca) the effect of ``dielectrization'' as a result of multiple shock compression are discussed.

  17. International energy market dynamics: a modelling approach. Tome 2

    International Nuclear Information System (INIS)

    Nachet, S.

    1996-01-01

    This work is an attempt to model international energy market and reproduce the behaviour of both energy demand and supply. Energy demand was represented using sector versus source approach. For developing countries, existing link between economic and energy sectors were analysed. Energy supply is exogenous for energy sources other than oil and natural gas. For hydrocarbons, exploration-production process was modelled and produced figures as production yield, exploration effort index, ect. The model build is econometric and is solved using a software that was constructed for this purpose. We explore the energy market future using three scenarios and obtain projections by 2010 for energy demand per source and oil and natural gas supply per region. Economic variables are used to produce different indicators as energy intensity, energy per capita, etc. (author). 378 refs., 26 figs., 35 tabs., 11 appends

  18. International energy market dynamics: a modelling approach. Tome 1

    International Nuclear Information System (INIS)

    Nachet, S.

    1996-01-01

    This work is an attempt to model international energy market and reproduce the behaviour of both energy demand and supply. Energy demand was represented using sector versus source approach. For developing countries, existing link between economic and energy sectors were analysed. Energy supply is exogenous for energy sources other than oil and natural gas. For hydrocarbons, exploration-production process was modelled and produced figures as production yield, exploration effort index, etc. The model built is econometric and is solved using a software that was constructed for this purpose. We explore the energy market future using three scenarios and obtain projections by 2010 for energy demand per source and oil natural gas supply per region. Economic variables are used to produce different indicators as energy intensity, energy per capita, etc. (author). 378 refs., 26 figs., 35 tabs., 11 appends

  19. Observing and modeling nonlinear dynamics in an internal combustion engine

    International Nuclear Information System (INIS)

    Daw, C.S.; Kennel, M.B.; Finney, C.E.; Connolly, F.T.

    1998-01-01

    We propose a low-dimensional, physically motivated, nonlinear map as a model for cyclic combustion variation in spark-ignited internal combustion engines. A key feature is the interaction between stochastic, small-scale fluctuations in engine parameters and nonlinear deterministic coupling between successive engine cycles. Residual cylinder gas from each cycle alters the in-cylinder fuel-air ratio and thus the combustion efficiency in succeeding cycles. The model close-quote s simplicity allows rapid simulation of thousands of engine cycles, permitting statistical studies of cyclic-variation patterns and providing physical insight into this technologically important phenomenon. Using symbol statistics to characterize the noisy dynamics, we find good quantitative matches between our model and experimental time-series measurements. copyright 1998 The American Physical Society

  20. Macroeconomic impacts of oil price shocks in Asian economies

    International Nuclear Information System (INIS)

    Cunado, Juncal; Jo, Soojin; Perez de Gracia, Fernando

    2015-01-01

    This paper analyzes the macroeconomic impact of structural oil shocks in four of the top oil-consuming Asian economies, using a VAR model. We identify three different structural oil shocks via sign restrictions: an oil supply shock, an oil demand shock driven by global economic activity and an oil-specific demand shock. The main results suggest that economic activity and prices respond very differently to oil price shocks depending on their types. In particular, an oil supply shock has a limited impact, while a demand shock driven by global economic activity has a significant positive effect in all four Asian countries examined. Our finding also includes that policy tools such as interest rates and exchange rates help mitigating the effects of supply shocks in Japan and Korea; however, they can be more actively used in response to demands shocks. - Highlights: • We analyze the effects of three structural oil price shocks on Asian economies. • Supply shocks have limited impact on the economic activity of Asian economies examined. • Demand shocks due to economic activity boosts GDP of all economies. • CPIs in India and Indonesia were only marginally affected by oil price shocks. • Monetary and exchange rate tools help mitigating supply shocks in Korea and Japan.

  1. Shock heating of the solar wind plasma

    Science.gov (United States)

    Whang, Y. C.; Liu, Shaoliang; Burlaga, L. F.

    1990-01-01

    The role played by shocks in heating solar-wind plasma is investigated using data on 413 shocks which were identified from the plasma and magnetic-field data collected between 1973 and 1982 by Pioneer and Voyager spacecraft. It is found that the average shock strength increased with the heliocentric distance outside 1 AU, reaching a maximum near 5 AU, after which the shock strength decreased with the distance; the entropy of the solar wind protons also reached a maximum at 5 AU. An MHD simulation model in which shock heating is the only heating mechanism available was used to calculate the entropy changes for the November 1977 event. The calculated entropy agreed well with the value calculated from observational data, suggesting that shocks are chiefly responsible for heating solar wind plasma between 1 and 15 AU.

  2. Inappropriate shocks in the subcutaneous ICD

    DEFF Research Database (Denmark)

    Olde Nordkamp, Louise R A; Brouwer, Tom F; Barr, Craig

    2015-01-01

    shocks have been reported. METHODS: We analyzed the incidence, predictors and management of inappropriate shocks in the EFFORTLESS S-ICD Registry, which collects S-ICD implantation information and follow-up data from clinical centers in Europe and New Zealand. RESULTS: During a follow-up of 21 ± 13...... months, 48 out of 581 S-ICD patients (71% male, age 49 ± 18 years) experienced 101 inappropriate shocks (8.3%). The most common cause was cardiac signal oversensing (73%), such as T-wave oversensing. Eighteen shocks (18%) were due to supraventricular tachycardias (SVT), of which 15 occurred in the shock......-only zone. Cox-proportional hazard modeling using time-dependent covariates demonstrated that patients with a history of atrial fibrillation (HR 2.4) and patients with hypertrophic cardiomyopathy (HR 4.6) had an increased risk for inappropriate shocks, while programming the primary vector for sensing (from...

  3. Dynamics of desalination shocks in microstructures

    Science.gov (United States)

    Mani, Ali; Bazant, Martin

    2010-11-01

    We describe a nonlinear regime of ion transport that results from coupled conduction effects of electric double layers (surface conduction) in electrokinetic systems. Mani, Zangle, and Santiago (Langmuir, 25, 3898--3916) recently showed that sharp concentration gradients can be formed and propagate away from a microchannel/nanochannel junction, analogous to shock waves in gases. Propagation of these shocks in microchannels leaves behind a region with orders of magnitude lower salt concentration acting to desalinate the bulk electrolyte. In this talk we describe the basic dynamics of desalination shocks and present the mathematical theory of shock existence and propagation in complex microstructures. We predict that desalination shocks accelerate and sharpen in narrowing structures and decelerate and weaken, even disappear, in widening channels. We will also discuss mathematical models for propagation of desalination shocks in porous media.

  4. Measurement and reactive burn modeling of the shock to detonation transition for the HMX based explosive LX-14

    Science.gov (United States)

    Jones, J. D.; Ma, Xia; Clements, B. E.; Gibson, L. L.; Gustavsen, R. L.

    2017-06-01

    Gas-gun driven plate-impact techniques were used to study the shock to detonation transition in LX-14 (95.5 weight % HMX, 4.5 weight % estane binder). The transition was recorded using embedded electromagnetic particle velocity gauges. Initial shock pressures, P, ranged from 2.5 to 8 GPa and the resulting distances to detonation, xD, were in the range 1.9 to 14 mm. Numerical simulations using the SURF reactive burn scheme coupled with a linear US -up / Mie-Grueneisen equation of state for the reactant and a JWL equation of state for the products, match the experimental data well. Comparison of simulation with experiment as well as the ``best fit'' parameter set for the simulations is presented.

  5. The Shock and Vibration Bulletin. Part 2. Model Test and Analysis, Testing Techniques, Machinery Dynamics, Isolation and Damping, Structural Dynamics

    Science.gov (United States)

    1986-08-01

    jBfr 5? JOR JS T SIONAL/lBRATIONjerF^EAR-RANCHED PROPULSION.gVSTEMS j... 117 / H.F. Tavares, Cepstrum Engenharia Ltda., Rio de Janeiro, Brazil and V...GAUGE" FOR STRUCTURAL ASSESSMENT T. Krauthammer, Department ot Civil and Mineral Engineering, University of Minnesota, Minneapolis, MN ACTIVE ONE...ACCEPTANCE TEST SPECIFICATIONS FOR BLAST-RESISTANT WINDOWS G.E. Meyers, Naval Civil Engineering Laboratory, Port Hueneme, CA Shock Testin» and

  6. Seismic velocity models for an internally asymmetric Mars

    Science.gov (United States)

    Franck, S.; Kowalle, G.

    1994-01-01

    The well-known dichotomy in topography, surface age, and crustal structure between the northern lowlands and the southern uplands of Mars has been explained by both endogenic and exogenic processes. According to the used model this asymmetry might be a result of a certain mechanism of core formation influencing the following planetary evolution. Therefore it has been assumed that the present internal structure of Mars is characterized by different velocity-depth distributions of the mantle for the northern and southern hemisphere, respectively. For both regions significant differences in travel times of seismic waves were calculated. These results may be important for the future seismic exploration of Mars.

  7. International Family Migration and the Dual-Earner Model

    DEFF Research Database (Denmark)

    Munk, Martin D.; Nikolka, Till; Poutvaara, Panu

    2018-01-01

    Gender differences in labor force participation are exceptionally small in Nordic countries. We investigate how couples emigrating from Denmark self-select and sort into different destinations and whether couples pursue the dual-earner model, in which both partners work, when abroad. Female labor...... force participation is slightly lower among couples that later emigrate, and drops considerably after migration outside the Nordic countries. Pre-migration differences between couples subsequently migrating to different destinations are small. Our survey reveals that couple migration is usually driven...... by the male’s job opportunities. The results suggest that increasing international migration may reduce women’s career investments....

  8. Scaling for Shock Response of Equipment in Different Submarines

    Directory of Open Access Journals (Sweden)

    G.J. O’Hara

    1993-01-01

    Full Text Available This article presents scaling rules developed to predict the response of submarine equipment subjected to underwater chemical explosions. The computer was used as a surrogate for shock tests. A simplified model of a hull section was used to contain frame-mounted single degree of freedom equipment. A general scaling rule has been developed to handle the spread in the shock response attributable to the charge weight, equipment weight, and equipment frequency, where the shock response is the absolute maximum acceleration of the equipment mass as a function of the shock factor for a given charge weight. The article also examines those cases where a new hull is derived from an original hull by the linear scaling law. The solution of the shock response is well known when the internal equipment has also been linearly scaled. A new general scaling rule is developed for those cases when the equipment is not linearly scaled, that is, the equipment and charge weight used with the original hull remains unchanged when installed in the linearly scaled hull or a completely different equipment and charge weight are used with the new hull. It is emphasized that the test sections were short and devoid of typical equipment present in a real compartment. The results, nevertheless, provide trends and ratios in shock design values, not necessarily absolute design numbers. The approach taken in developing these scaling rules could be useful for enhancing field data that may exist for a given class of boat to allow greater usage of these data for different equipment subject to a variety of charge weights, attack geometries, and other boats.

  9. Three-Dimensional Navier-Stokes Simulations with Two-Equation Turbulence Models of Intersecting Shock-Waves/Turbulent Boundary Layer at Mach 8.3

    Science.gov (United States)

    Bardina, J. E.; Coakley, T. J.

    1994-01-01

    An investigation of the numerical simulation with two-equation turbulence models of a three-dimensional hypersonic intersecting (SWTBL) shock-wave/turbulent boundary layer interaction flow is presented. The flows are solved with an efficient implicit upwind flux-difference split Reynolds-averaged Navier-Stokes code. Numerical results are compared with experimental data for a flow at Mach 8.28 and Reynolds number 5.3x10(exp 6) with crossing shock-waves and expansion fans generated by two lateral 15 fins located on top of a cold-wall plate. This experiment belongs to the hypersonic database for modeling validation. Simulations show the development of two primary counter-rotating cross-flow vortices and secondary turbulent structures under the main vortices and in each corner singularity inside the turbulent boundary layer. A significant loss of total pressure is produced by the complex interaction between the main vortices and the uplifted jet stream of the boundary layer. The overall agreement between computational and experimental data is generally good. The turbulence modeling corrections show improvements in the predictions of surface heat transfer distribution and an increase in the strength of the cross-flow vortices. Accurate predictions of the outflow flowfield is found to require accurate modeling of the laminar/turbulent boundary layers on the fin walls.

  10. Remarks on stability of magneto-elastic shocks

    Directory of Open Access Journals (Sweden)

    Włodzimierz Domański

    2015-12-01

    Full Text Available The problem of stability of plane shock waves for a model of perfect magnetoelasticityis investigated. Important mathematical properties, like loss of strict hyperbolicityand loss of genuine nonlinearity, and their consequences for the stability ofmagneto-elastic shocks are discussed. It is shown that some of these shocks do not satisfyclassical Lax stability conditions. Both compressible and incompressible models ofmagneto-elasticity are discussed.[b]Keywords[/b]: perfect magneto-elasticity, shock waves, stability conditions

  11. Acceleration mechanisms flares, magnetic reconnection and shock waves

    International Nuclear Information System (INIS)

    Colgate, S.A.

    1979-01-01

    Several mechanisms are briefly discussed for the acceleration of particles in the astrophysical environment. Included are hydrodynamic acceleration, spherically convergent shocks, shock and a density gradient, coherent electromagnetic acceleration, the flux tube origin, symmetries and instabilities, reconnection, galactic flares, intergalactic acceleration, stochastic acceleration, and astrophysical shocks. It is noted that the supernova shock wave models still depend critically on the presupernova star structure and the assumption of highly compact presupernova models for type I supernovae. 37 references

  12. A preventive maintenance policy based on dependent two-stage deterioration and external shocks

    International Nuclear Information System (INIS)

    Yang, Li; Ma, Xiaobing; Peng, Rui; Zhai, Qingqing; Zhao, Yu

    2017-01-01

    This paper proposes a preventive maintenance policy for a single-unit system whose failure has two competing and dependent causes, i.e., internal deterioration and sudden shocks. The internal failure process is divided into two stages, i.e. normal and defective. Shocks arrive according to a non-homogeneous Poisson process (NHPP), leading to the failure of the system immediately. The occurrence rate of a shock is affected by the state of the system. Both an age-based replacement and finite number of periodic inspections are schemed simultaneously to deal with the competing failures. The objective of this study is to determine the optimal preventive replacement interval, inspection interval and number of inspections such that the expected cost per unit time is minimized. A case study on oil pipeline maintenance is presented to illustrate the maintenance policy. - Highlights: • A maintenance model based on two-stage deterioration and sudden shocks is developed. • The impact of internal system state on external shock process is studied. • A new preventive maintenance strategy combining age-based replacements and periodic inspections is proposed. • Postponed replacement of a defective system is provided by restricting the number of inspections.

  13. Synergistic effects of fresh frozen plasma and valproic acid treatment in a combined model of traumatic brain injury and hemorrhagic shock

    DEFF Research Database (Denmark)

    Imam, Ayesha M; Jin, Guang; Duggan, Michael

    2013-01-01

    Traumatic brain injury (TBI) and hemorrhagic shock (HS) are major causes of trauma-related deaths and are especially lethal as a combined insult. Previously, we showed that early administration of fresh frozen plasma (FFP) decreased the size of the brain lesion and associated swelling in a swine...... model of combined TBI+HS. We have also shown separately that addition of valproic acid (VPA) to the resuscitation protocol attenuates inflammatory markers in the brain as well as the degree of TBI. The current study was performed to determine whether a combined FFP+VPA treatment strategy would exert...

  14. Modelling interacting molecular motors with an internal degree of freedom

    Science.gov (United States)

    Pinkoviezky, Itai; Gov, Nir S.

    2013-02-01

    The mechanisms underlying the collective motion of molecular motors in living cells are not yet fully understood. One such open puzzle is the observed pulses of backward-moving myosin-X in the filopodia structure. Motivated by this phenomenon we introduce two generalizations of the ‘total asymmetric exclusion process’ (TASEP) that might be relevant to the formation of such pulses. The first is adding a nearest-neighbours attractive interaction between motors, while the second is adding an internal degree of freedom corresponding to a processive and immobile form of the motors. Switching between the two states occurs stochastically, without a conservation law. Both models show strong deviations from the mean field behaviour and lack particle-hole symmetry. We use approximations borrowed from the research on vehicular traffic models to calculate the current and jam size distribution in a system with periodic boundary conditions and introduce a novel modification to one of these approximation schemes.

  15. Modelling interacting molecular motors with an internal degree of freedom

    International Nuclear Information System (INIS)

    Pinkoviezky, Itai; Gov, Nir S

    2013-01-01

    The mechanisms underlying the collective motion of molecular motors in living cells are not yet fully understood. One such open puzzle is the observed pulses of backward-moving myosin-X in the filopodia structure. Motivated by this phenomenon we introduce two generalizations of the ‘total asymmetric exclusion process’ (TASEP) that might be relevant to the formation of such pulses. The first is adding a nearest-neighbours attractive interaction between motors, while the second is adding an internal degree of freedom corresponding to a processive and immobile form of the motors. Switching between the two states occurs stochastically, without a conservation law. Both models show strong deviations from the mean field behaviour and lack particle–hole symmetry. We use approximations borrowed from the research on vehicular traffic models to calculate the current and jam size distribution in a system with periodic boundary conditions and introduce a novel modification to one of these approximation schemes. (paper)

  16. Dialogues on cancer survivorship: a new model of international cooperation.

    Science.gov (United States)

    Stein, Kevin; Mattioli, Vittorio

    2013-06-01

    The authors describe the rationale and background of the present supplement to Cancer intended to stimulate a dialogue among researchers from Europe and North America regarding important issues faced by cancer survivors. Through jointly written articles addressing various aspects of cancer survivorship, each manuscript reports on the similarities, disparities, and problems viewed from the point of view of each author's respective continent. The supplement is meant to create a springboard for increased collaboration and aid in the development of a shared care model to improve the quality of cancer care, both during and after the completion of primary treatment. We hope that this effort may represent a new model of international cooperation, which is fruitful not only for the field of scientific research but also for identifying and sharing new approaches to the care and management of cancer survivorship issues, ultimately bringing improvements to quality of life of the growing population of cancer survivors. Copyright © 2013 American Cancer Society.

  17. Models and Rules of Evaluation in International Accounting

    Directory of Open Access Journals (Sweden)

    Niculae Feleaga

    2006-04-01

    Full Text Available The accounting procedures cannot be analyzed without a previous evaluation. Value is in general a very subjective issue, usually the result of a monetary evaluation made to a specific asset, group of assets or entities, or to some rendered services. Within the economic sciences, value comes from its very own deep history. In accounting, the concept of value had a late and fragile start. The term of value must not be misinterpreted as being the same thing with cost, even though value is frequently measured through costs. At the origin of the international accounting standards lays the framework for preparing, presenting and disclosing the financial statements. The framework stays as a reference matrix, as a standard of standards, as a constitution of financial accounting. According to the international framework, the financial statements use different evaluation basis: the hystorical cost, the current cost, the realisable (settlement value, the present value (the present value of cash flows. Choosing the evaluation basis and the capital maintenance concept will eventually determine the accounting evaluation model used in preparing the financial statements of a company. The multitude of accounting evaluation models differentiate themselves one from another through various relevance and reliable degrees of accounting information and therefore, accountants (the prepares of financial statements must try to equilibrate these two main qualitative characteristics of financial information.

  18. Models and Rules of Evaluation in International Accounting

    Directory of Open Access Journals (Sweden)

    Liliana Feleaga

    2006-06-01

    Full Text Available The accounting procedures cannot be analyzed without a previous evaluation. Value is in general a very subjective issue, usually the result of a monetary evaluation made to a specific asset, group of assets or entities, or to some rendered services. Within the economic sciences, value comes from its very own deep history. In accounting, the concept of value had a late and fragile start. The term of value must not be misinterpreted as being the same thing with cost, even though value is frequently measured through costs. At the origin of the international accounting standards lays the framework for preparing, presenting and disclosing the financial statements. The framework stays as a reference matrix, as a standard of standards, as a constitution of financial accounting. According to the international framework, the financial statements use different evaluation basis: the hystorical cost, the current cost, the realisable (settlement value, the present value (the present value of cash flows. Choosing the evaluation basis and the capital maintenance concept will eventually determine the accounting evaluation model used in preparing the financial statements of a company. The multitude of accounting evaluation models differentiate themselves one from another through various relevance and reliable degrees of accounting information and therefore, accountants (the prepares of financial statements must try to equilibrate these two main qualitative characteristics of financial information.

  19. Toxic Shock Syndrome

    Science.gov (United States)

    ... may also be caused by toxins produced by group A streptococcus (strep) bacteria. Toxic shock syndrome has been associated ... syndrome. The syndrome can also be caused by group A streptococcus (strep) bacteria. Risk factors Toxic shock syndrome can ...

  20. Biomass shock pretreatment

    Science.gov (United States)

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  1. Simulations of Turbulent Flows with Strong Shocks and Density Variations

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Xiaolin

    2012-12-13

    In this report, we present the research efforts made by our group at UCLA in the SciDAC project Simulations of turbulent flows with strong shocks and density variations. We use shock-fitting methodologies as an alternative to shock-capturing schemes for the problems where a well defined shock is present. In past five years, we have focused on development of high-order shock-fitting Navier-Stokes solvers for perfect gas flow and thermochemical non-equilibrium flow and simulation of shock-turbulence interaction physics for very strong shocks. Such simulation has not been possible before because the limitation of conventional shock capturing methods. The limitation of shock Mach number is removed by using our high-order shock-fitting scheme. With the help of DOE and TeraGrid/XSEDE super computing resources, we have obtained new results which show new trends of turbulence statistics behind the shock which were not known before. Moreover, we are also developing tools to consider multi-species non-equilibrium flows. The main results are in three areas: (1) development of high-order shock-fitting scheme for perfect gas flow, (2) Direct Numerical Simulation (DNS) of interaction of realistic turbulence with moderate to very strong shocks using super computing resources, and (3) development and implementation of models for computation of mutli-species non-quilibrium flows with shock-fitting codes.

  2. Converging shocks in elastic-plastic solids.

    Science.gov (United States)

    Ortega, A López; Lombardini, M; Hill, D J

    2011-11-01

    We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e=e(s)(I(1))+e(h)(ρ,ς), where e(s) accounts for shear through the first invariant of the Cauchy-Green tensor, and e(h) represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., e(h)=e(h)(ρ), with a power-law dependence e(h) is proportional to ρ(α), shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M is proportional to [log(1/R)](α), independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M is proportional to R(-(s-1)) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part e(h) is that of an ideal gas, is also tested, recovering the strong-shock limit M is proportional to R(-(s-1)/n(γ)) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ-1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the

  3. Robots with Internal Models: A Route to Self-Aware and Hence Safer Robots

    Science.gov (United States)

    Winfield, Alan F. T.

    The following sections are included: * Introduction * Internal Models and Self-Awareness * Internal Model-Based Architecture for Robot Safety * The Internal Model * The Consequence Evaluator * The Object Tracker-Localizer * Towards an Ethical Robot * Challenges and Open Questions * Discussion: The Way Forward * Summary and Conclusions

  4. Shock processing of interstellar grains

    International Nuclear Information System (INIS)

    Seab, C.G.; Shull, J.M.

    1986-01-01

    Shock processing plays an important role in the life of a typical interstellar grain. Shocks of 100 km/s-l or greater can destroy about 50% of the grain material under appropriate preshock conditions of density and magnetic field. The destruction occurs by grain-grain collisions and nonthermal sputtering for steady state radiative shocks and by thermal sputtering for fast adiabatic shocks. The evaluation of the lifetime of grains against shock destruction depends on models of the interstellar medium (ISM) structure and on supernova remnants (SNR) evolution. Results from various authors give lifetimes between 10 to the 8th and 10 to the 9th power years, compared to typical injection times for new grains of a few times 10 to the 9th power years. These numbers require that a major portion of the interstellar silicon bearing grain material must be formed by grain growth in the ISM. At the same time, the presence of isotopic anomalies in some meteorites implies that at least some grains must survive from their formation in SNRs or red giant winds through incorporation into the solar system

  5. Protective effect of chlorpromazine on endotoxin toxicity and TNF production in glucocorticoid-sensitive and glucocorticoid-resistant models of endotoxic shock

    Science.gov (United States)

    1991-01-01

    The present study was designed to define the potential of chlorpromazine (CPZ) as a protective agent against lipopolysaccharide (LPS) toxicity in comparison with glucocorticoids, and to obtain initial correlations with its effects on the levels of tumor necrosis factor (TNF), a pivotal mediator of endotoxic shock. It was found that CPZ protects mice, normal or adrenalectomized, and guinea pigs against lethality of LPS, and inhibited TNF serum levels, like dexamethasone (DEX), a well-known inhibitor of TNF synthesis. CPZ protected against LPS lethality when administered 30 minutes (min) before, simultaneously, or up to 10 min after LPS and was ineffective when given 30 min after LPS, paralleling the inhibitory effect on TNF production. In another experimental model, where mice were sensitized to LPS toxicity by actinomycin D, CPZ significantly inhibited LPS lethality and hepatotoxicity, whereas under these conditions DEX was inactive. These experiments indicate that CPZ has a protective action in both glucocorticoid-sensitive and -resistant models of endotoxic shock. PMID:2033366

  6. Model for the broadband Crab nebula spectrum with injection of a log-parabola electron distribution at the wind termination shock

    Science.gov (United States)

    Fraschetti, F.; Pohl, M.

    2017-10-01

    We develop a model of the steady-state spectrum of the Crab nebula encompassing both the radio/soft X-ray and the GeV/multi-TeV observations. By solving the transport equation for TeV electrons injected at the wind termination shock as a log-parabola momentum distribution and evolved via energy losses, we determine analytically the resulting photon differential energy spectrum. We find an impressive agreement with the observations in the synchrotron region. The predicted synchrotron self-Compton accommodates the previously unsolved origin of the broad 200 GeV peak that matches the Fermi/LAT data beyond 1 GeV with the MAGIC data. A natural interpretation of the deviation from power-law of the photon spectrum customarily fit with empirical broken power-laws is provided. This model can be applied to the radio-to- multi-TeV spectra of a variety of astrophysical outflows, including pulsar wind nebulae and supernova remnants. We also show that MeV-range energetic particle distribution at interplanetary shocks typically fit with broken-power laws or Band function can be accurately reproduced by log-parabolas.

  7. Effects of aminoguanidine, a potent nitric oxide synthase inhibitor, on myocardial and organ structure in a rat model of hemorrhagic shock

    Directory of Open Access Journals (Sweden)

    Mona M Soliman

    2014-01-01

    Full Text Available Background: Nitric oxide (NO has been shown to increase following hemorrhagic shock (HS. Peroxynitrite is produced by the reaction of NO with reactive oxygen species, leads to nitrosative stress mediated organ injury. We examined the protective effects of a potent inhibitor of NO synthase, aminoguanidine (AG, on myocardial and multiple organ structure in a rat model of HS. Materials and Methods: Male Sprague Dawley rats (300-350 g were assigned to 3 experimental groups (n = 6 per group: (1 Normotensive rats (N, (2 HS rats and (3 HS rats treated with AG (HS-AG. Rats were hemorrhaged over 60 min to reach a mean arterial blood pressure of 40 mmHg. Rats were treated with 1 ml of 60 mg/kg AG intra-arterially after 60 min HS. Resuscitation was performed in vivo by the reinfusion of the shed blood for 30 min to restore normo-tension. Biopsy samples were taken for light and electron microscopy. Results: Histological examination of hemorrhagic shocked untreated rats revealed structural damage. Less histological damage was observed in multiple organs in AG-treated rats. AG-treatment decreased the number of inflammatory cells and mitochondrial swollen in myocardial cells. Conclusion: AG treatment reduced microscopic damage and injury in multiple organs in a HS model in rats.

  8. Shock waves in helium at low temperatures

    International Nuclear Information System (INIS)

    Liepmann, H.W.; Torczynski, J.R.

    1986-01-01

    Results are reported from studies of the properties of low temperature He-4 using shock waves as a probe. Ideal shock tube theory is used to show that sonic speeds of Mach 40 are attainable in He at 300 K. Viscosity reductions at lower temperatures minimize boundary layer effects at the side walls. A two-fluid model is described to account for the phase transition which He undergoes at temperatures below 2.2 K, after which the quantum fluid (He II) and the normal compressed superfluid (He I) coexist. Analytic models are provided for pressure-induced shocks in He I and temperature-induced shock waves (called second sound) which appear in He II. The vapor-fluid interface of He I is capable of reflecting second and gasdynamic sound shocks, which can therefore be used as probes for studying phase transitions between He I and He II. 17 references

  9. Neurons compute internal models of the physical laws of motion.

    Science.gov (United States)

    Angelaki, Dora E; Shaikh, Aasef G; Green, Andrea M; Dickman, J David

    2004-07-29

    A critical step in self-motion perception and spatial awareness is the integration of motion cues from multiple sensory organs that individually do not provide an accurate representation of the physical world. One of the best-studied sensory ambiguities is found in visual processing, and arises because of the inherent uncertainty in detecting the motion direction of an untextured contour moving within a small aperture. A similar sensory ambiguity arises in identifying the actual motion associated with linear accelerations sensed by the otolith organs in the inner ear. These internal linear accelerometers respond identically during translational motion (for example, running forward) and gravitational accelerations experienced as we reorient the head relative to gravity (that is, head tilt). Using new stimulus combinations, we identify here cerebellar and brainstem motion-sensitive neurons that compute a solution to the inertial motion detection problem. We show that the firing rates of these populations of neurons reflect the computations necessary to construct an internal model representation of the physical equations of motion.

  10. The International Trade Network: weighted network analysis and modelling

    International Nuclear Information System (INIS)

    Bhattacharya, K; Mukherjee, G; Manna, S S; Saramäki, J; Kaski, K

    2008-01-01

    Tools of the theory of critical phenomena, namely the scaling analysis and universality, are argued to be applicable to large complex web-like network structures. Using a detailed analysis of the real data of the International Trade Network we argue that the scaled link weight distribution has an approximate log-normal distribution which remains robust over a period of 53 years. Another universal feature is observed in the power-law growth of the trade strength with gross domestic product, the exponent being similar for all countries. Using the 'rich-club' coefficient measure of the weighted networks it has been shown that the size of the rich-club controlling half of the world's trade is actually shrinking. While the gravity law is known to describe well the social interactions in the static networks of population migration, international trade, etc, here for the first time we studied a non-conservative dynamical model based on the gravity law which excellently reproduced many empirical features of the ITN

  11. Temperature measurements of shock-compressed deuterium

    International Nuclear Information System (INIS)

    Holmes, N.C.; Ross, M.; Nellis, W.J.

    1994-11-01

    The authors measured the temperatures of single and double-shocked D 2 and H 2 up to 85 GPa (0.85 Mbar) and 5,200 K. While single shock temperatures, at pressures to 23 GPa, agree well with previous models, the double shock temperatures are as much as 40% lower than predicted. This is believed to be caused by molecular dissociation, and a new model of the hydrogen EOS at extreme conditions has been developed which correctly predicts their observations. These data and model have important implications for programs which use condensed-phase hydrogen in implosion systems

  12. Measurements on a shock wave generated by a solar flare

    International Nuclear Information System (INIS)

    Maxwell, A.; Dryer, M.

    1982-01-01

    Having reviewed data obtained on a high-velocity shock generated by a solar flare on 18 August 1979, 1400 UT and commented on some previously deduced velocities for the shock, a model, based on current computer programs to account for the overall characteristics of the shock as it propagated through the corona and the interplanetary plasma, is presented. (U.K.)

  13. School Shock: A Psychodynamic View of Learning Disability.

    Science.gov (United States)

    Zitani, E. Alfredo

    Learning disability is seen to be a dissociative disorder (school shock) similar to shell shock in wartime. The shell shock model is explained to focus diagnosis and treatment of learning disabilities around the dynamics of the predisposing unconscious conflict, the dynamics in the environment, the mechanism which allows these two conditions to…

  14. Reverse Shock Emission in Gamma-Ray Bursts Revisited

    Directory of Open Access Journals (Sweden)

    He Gao

    2015-01-01

    reverse shock which have been confirmed by observations. Investigations of the nature of the reverse shock emission can provide valuable insights into the intrinsic properties of the GRB ejecta. Here we briefly review the standard and the extended models of the reverse shock emission, discussing the connection between the theory and observations, including the implications of the latest observational advances.

  15. Bugbuster: Survivability of Living Bacteria Upon Shock Compression

    Science.gov (United States)

    Willis, M. J.; Ahrens, T. J.; Bertani, L. E.; Nash, C. Z.

    2003-12-01

    Survivability of bacteria during impact events has implications both for the transport of life between planets and development of organisms on Hadean Earth and other planets during the period of heavy bombardment which ended 3.5 Gyr before the present [1]. We envision that life existed within internal rock surfaces immersed in the early ocean. We performed shock recovery experiments on live E. coli bacteria to determine survival rate vs. shock pressure. Samples of 2x107 cells were suspended in ˜10-5 l of a buffer solution (TE: a 10:1 solution of Tris and EDTA), sealed into stainless steel chambers that are impacted by 1.5 mm thick flyer plates at 670-760 m s-1 using a 20 mm gun. Recovered liquid was mixed with a nutrient broth (LB: growth medium containing tryptone, yeast extract and NaCl) and spread on a Petrie dish containing agar (a polysaccharide growth medium extracted from marine algae Rhodophyceae). Recovered samples were cultured for ˜16 hours at 37° C. In addition, sample bacteria studied under an optical microscope with DAPI fluorescent stain to verify presence of bacteria in shock recovered samples. Initial and reverberated shock pressures in H2O varied from 0.2 to 2.0 and 2.4 to 14.9 GPa respectively. We modeled the bacteria cell walls with stilbene, ρ 0=1.16 g cm-3, US=2.866+1.588uP and the cell interiors as water. Upon initial loading the net strain imposed on E. coli that just caused non-survival for 10-6 s duration stress was 2.8. If this strain is characteristic of that tolerable by E. coli, we predict that shock stresses of 25 MPa, 25 kPa and 25 Pa are sustainable upon shock loading by 0.1 ms, 0.1 s and 100 s shock duration pulses. Such shock durations are induced by 2.5 m, 2.5 km and 2,500 km diameter silicate impactors. References: [1] Maher K.A. & Stevenson D.J., Nature, 331, pp.612-614, 1988

  16. DOE International Collaboration; Seismic Modeling and Simulation Capability Project

    Energy Technology Data Exchange (ETDEWEB)

    Leininger, Lara D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Settgast, Randolph R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2010-10-12

    The following report describes the development and exercise of a new capability at LLNL to model complete, non-linear, seismic events in 3-dimensions with a fully-coupled soil structure interaction response. This work is specifically suited to nuclear reactor design because this design space is exempt from the Seismic Design requirements of International Building Code (IBC) and the American Society of Civil Engineers (ASCE) [4,2]. Both IBC and ASCE-7 exempt nuclear reactors because they are considered “structures that require special consideration” and their design is governed only by “other regulations”. In the case of nuclear reactors, the regulations are from both the Nuclear Regulatory Commission (NRC) [10] and ASCE 43 [3]. This current framework of design guidance, coupled to this new and evolving capability to provide high fidelity design solutions as presented in this report, enables the growing field of Performance-Based Design (PBD) for nuclear reactors subjected to earthquake ground motions.

  17. Development of an International School Nurse Asthma Care Coordination Model.

    Science.gov (United States)

    Garwick, Ann W; Svavarsdóttir, Erla Kolbrun; Seppelt, Ann M; Looman, Wendy S; Anderson, Lori S; Örlygsdóttir, Brynja

    2015-03-01

    To identify and compare how school nurses in Reykjavik, Iceland and St. Paul, Minnesota coordinated care for youth with asthma (ages 10-18) and to develop an asthma school nurse care coordination model. Little is known about how school nurses coordinate care for youth with asthma in different countries. A qualitative descriptive study design using focus group data. Six focus groups with 32 school nurses were conducted in Reykjavik (n = 17) and St. Paul (n = 15) using the same protocol between September 2008 and January 2009. Descriptive content analytic and constant comparison strategies were used to categorize and compare how school nurses coordinated care, which resulted in the development of an International School Nurse Asthma Care Coordination Model. Participants in both countries spontaneously described a similar asthma care coordination process that involved information gathering, assessing risk for asthma episodes, prioritizing healthcare needs and anticipating and planning for student needs at the individual and school levels. This process informed how they individualized symptom management, case management and/or asthma education. School nurses played a pivotal part in collaborating with families, school and healthcare professionals to ensure quality care for youth with asthma. Results indicate a high level of complexity in school nurses' approaches to asthma care coordination that were responsive to the diverse and changing needs of students in school settings. The conceptual model derived provides a framework for investigators to use in examining the asthma care coordination process of school nurses in other geographic locations. © 2014 John Wiley & Sons Ltd.

  18. Quantitative Risk Modeling of Fire on the International Space Station

    Science.gov (United States)

    Castillo, Theresa; Haught, Megan

    2014-01-01

    The International Space Station (ISS) Program has worked to prevent fire events and to mitigate their impacts should they occur. Hardware is designed to reduce sources of ignition, oxygen systems are designed to control leaking, flammable materials are prevented from flying to ISS whenever possible, the crew is trained in fire response, and fire response equipment improvements are sought out and funded. Fire prevention and mitigation are a top ISS Program priority - however, programmatic resources are limited; thus, risk trades are made to ensure an adequate level of safety is maintained onboard the ISS. In support of these risk trades, the ISS Probabilistic Risk Assessment (PRA) team has modeled the likelihood of fire occurring in the ISS pressurized cabin, a phenomenological event that has never before been probabilistically modeled in a microgravity environment. This paper will discuss the genesis of the ISS PRA fire model, its enhancement in collaboration with fire experts, and the results which have informed ISS programmatic decisions and will continue to be used throughout the life of the program.

  19. Internal modelling under Risk-Based Capital (RBC) framework

    Science.gov (United States)

    Ling, Ang Siew; Hin, Pooi Ah

    2015-12-01

    Very often the methods for the internal modelling under the Risk-Based Capital framework make use of the data which are in the form of run-off triangle. The present research will instead extract from a group of n customers, the historical data for the sum insured si of the i-th customer together with the amount paid yij and the amount aij reported but not yet paid in the j-th development year for j = 1, 2, 3, 4, 5, 6. We model the future value (yij+1, aij+1) to be dependent on the present year value (yij, aij) and the sum insured si via a conditional distribution which is derived from a multivariate power-normal mixture distribution. For a group of given customers with different original purchase dates, the distribution of the aggregate claims liabilities may be obtained from the proposed model. The prediction interval based on the distribution for the aggregate claim liabilities is found to have good ability of covering the observed aggregate claim liabilities.

  20. Septic shock in chronic dialysis patients: clinical characteristics, antimicrobial therapy and mortality.

    Science.gov (United States)

    Clark, Edward; Kumar, Anand; Langote, Amit; Lapinsky, Stephen; Dodek, Peter; Kramer, Andreas; Wood, Gordon; Bagshaw, Sean M; Wood, Ken; Gurka, Dave; Sood, Manish M

    2016-02-01

    To describe the clinical characteristics and in-hospital mortality of chronic dialysis-dependent end-stage kidney disease patients with septic shock in comparison to septic shock patients not receiving chronic dialysis. Using an international, multicenter database, we conducted a retrospective analysis of data collected from 10,414 patients admitted to the intensive care unit (ICU) with septic shock from 1989 to 2013, of which 800 (7.7 %) were chronic dialysis patients. Data on demographic characteristics, sites of infection, microbial pathogens, antimicrobial usage patterns, and in-hospital mortality were aggregated and compared for chronic dialysis and non-dialysis patients. Multivariate time-varying Cox models with and without propensity score matching were constructed to determine the association between dialysis and in-hospital death. Septic shock secondary to central venous catheter infection, peritonitis, ischemic bowel, and cellulitis was more frequent in chronic dialysis patients. The isolation of resistant organisms (10.7 vs. 7.1 %; p = 0.005) and delays in receiving antimicrobials (6.0 vs. 5.0 h) were more common in chronic dialysis patients than in non-dialysis patients. Delayed appropriate antimicrobial therapy was associated with an increased risk of death in chronic dialysis patients (p septic shock differ from those of similar non-dialysis patients. However, there was no significant difference in mortality between the chronic dialysis and non-dialysis patients with septic shock enrolled in this analysis.

  1. Electrostatic and magnetic instabilities in the transition layer of a collisionless weakly relativistic pair shock

    Science.gov (United States)

    Dieckmann, M. E.; Bret, A.

    2018-01-01

    Energetic electromagnetic emissions by astrophysical jets like those that are launched during the collapse of a massive star and trigger gamma-ray bursts are partially attributed to relativistic internal shocks. The shocks are mediated in the collisionless plasma of such jets by the filamentation instability of counterstreaming particle beams. The filamentation instability grows fastest only if the beams move at a relativistic relative speed. We model here with a particle-in-cell simulation, the collision of two cold pair clouds at the speed c/2 (c: speed of light). We demonstrate that the two-stream instability outgrows the filamentation instability for this speed and is thus responsible for the shock formation. The incomplete thermalization of the upstream plasma by its quasi-electrostatic waves allows other instabilities to grow. A shock transition layer forms, in which a filamentation instability modulates the plasma far upstream of the shock. The inflowing upstream plasma is progressively heated by a two-stream instability closer to the shock and compressed to the expected downstream density by the Weibel instability. The strong magnetic field due to the latter is confined to a layer 10 electron skin depths wide.

  2. Deionization shocks in flat and thin microchannels

    Science.gov (United States)

    Alizadeh, Shima; Andersen, Mathias B.; Mani, Ali

    2013-11-01

    We have investigated dynamics of deionization shocks in flat and thin microchannel using two different approaches: (1) extension of Mani and Bazant's simple model [PRE 2011] to two-dimensions, and (2) development of a height-averaged model from tabulated solutions of the Poisson-Boltzmann equation. The latter model is more accurate since it captures both thin and overlapped double-layer regimes as well as diffusion-osmotic flows. Both models describe ion transport and deionization shock dynamics in two dimensional space corresponding to the transverse flat dimensions. We compare prediction of these models for shock profile, speed and dynamical response, as well as onset conditions for hydrodynamic instability of deionization shocks. The outcome of this study has applications in deionization processes in lab-on-a-chip systems as well as porous microstructures.

  3. On the Need to Establish an International Soil Modeling Consortium

    Science.gov (United States)

    Vereecken, H.; Vanderborght, J.; Schnepf, A.

    2014-12-01

    Soil is one of the most critical life-supporting compartments of the Biosphere. Soil provides numerous ecosystem services such as a habitat for biodiversity, water and nutrients, as well as producing food, feed, fiber and energy. To feed the rapidly growing world population in 2050, agricultural food production must be doubled using the same land resources footprint. At the same time, soil resources are threatened due to improper management and climate change. Despite the many important functions of soil, many fundamental knowledge gaps remain, regarding the role of soil biota and biodiversity on ecosystem services, the structure and dynamics of soil communities, the interplay between hydrologic and biotic processes, the quantification of soil biogeochemical processes and soil structural processes, the resilience and recovery of soils from stress, as well as the prediction of soil development and the evolution of soils in the landscape, to name a few. Soil models have long played an important role in quantifying and predicting soil processes and related ecosystem services. However, a new generation of soil models based on a whole systems approach comprising all physical, mechanical, chemical and biological processes is now required to address these critical knowledge gaps and thus contribute to the preservation of ecosystem services, improve our understanding of climate-change-feedback processes, bridge basic soil science research and management, and facilitate the communication between science and society. To meet these challenges an international community effort is required, similar to initiatives in systems biology, hydrology, and climate and crop research. Our consortium will bring together modelers and experimental soil scientists at the forefront of new technologies and approaches to characterize soils. By addressing these aims, the consortium will contribute to improve the role of soil modeling as a knowledge dissemination instrument in addressing key

  4. Adiabatic, Shock, and Plastic Work Heating of Solids and the Cylinder Test

    National Research Council Canada - National Science Library

    Ruden, E

    2000-01-01

    Solids subjected to high pressures, shocks, and/or deformation experience an increase in internal energy density and temperature due to adiabatic compression, shock heating, and plastic work heating, respectively...

  5. Treatment with a histone deacetylase inhibitor, valproic acid, is associated with increased platelet activation in a large animal model of traumatic brain injury and hemorrhagic shock

    DEFF Research Database (Denmark)

    Dekker, Simone E; Sillesen, Martin; Bambakidis, Ted

    2014-01-01

    BACKGROUND: We have previously shown that resuscitation with fresh frozen plasma (FFP) in a large animal model of traumatic brain injury (TBI) and hemorrhagic shock (HS) decreases the size of the brain lesion, and that addition of a histone deacetylase inhibitor, valproic acid (VPA), provides...... synergistic benefits. In this study, we hypothesized that VPA administration would be associated with a conservation of platelet function as measured by increased platelet activation after resuscitation. MATERIALS AND METHODS: Ten swine (42-50 kg) were subjected to TBI and HS (40% blood loss). Animals were...... with the FFP group (5.22 ± 2.00 pg/mL versus 7.99 ± 1.13 pg/mL; P = 0.03). CONCLUSIONS: In this clinically relevant large animal model of combined TBI + HS, the addition of VPA to FFP resuscitation results in an early upregulation of platelet activation in the circulation and the brain. The previously observed...

  6. Challenging the Forward Shock Model with the 80 Ms Follow up of the X-ray Afterglow of Gamma-Ray Burst 130427A

    Directory of Open Access Journals (Sweden)

    Massimiliano De Pasquale

    2017-01-01

    Full Text Available GRB 130427A was the most luminous gamma-ray burst detected in the last 30 years. With an isotropic energy output of 8.5 × 10 53 erg and redshift of 0.34, it combined very high energetics with a relative proximity to Earth in an unprecedented way. Sensitive X-ray observatories such as XMM-Newton and Chandra have detected the afterglow of this event for a record-breaking baseline longer than 80 million seconds. The light curve displays a simple power-law over more than three decades in time. In this presentation, we explore the consequences of this result for a few models put forward so far to interpret GRB 130427A, and more in general the implication of this outcome in the context of the standard forward shock model.

  7. The effect of intracellular delivery of catalase and antisense oligonucleotides to NF-kappaB using albumin microcapsules in the endotoxic shock model.

    Science.gov (United States)

    Siwale, Rodney C; Oettinger, Carl W; Addo, Richard; Siddig, Aladin; D'Souza, Martin J

    2009-11-01

    Microencapsulated (MC) catalase has been shown to inhibit H(2)O(2) and tumor necrosis factor (TNF) in vitro after endotoxin stimulation. It is the purpose of this study to determine whether MC catalase improves pro-inflammatory cytokine inhibition and mortality in an endotoxic shock model in vivo. We also examined whether MC catalase and antisense oligonucleotides (ASO) to nuclear factor kappaB (NF-kappaB) together improved survival by inhibiting pro-inflammatory cytokines using different mechanisms. Albumin microcapsules containing catalase and ASO to NF-kappaB were prepared 2-7 microm in size by using a Büchi spray dryer. Progressively increasing doses of MC catalase, MC ASO to NF-kappaB, and the combination were given to rats before the administration of Escherichia coli endotoxin. Results demonstrated 60% survival in rats given 15 mg/kg MC catalase, 70% survival with 20 mg/kg MC ASO NF-kappaB, and 80% survival with the combination. TNF was inhibited by 53% in the MC catalase group 4 h after endotoxin administration, 43% in the ASO NF-kappaB group, and 78% in the combination group compared to controls. In conclusion, this study demonstrates the effectiveness of MC intracellular delivery of the naturally occurring antioxidant catalase in improving animal survival. The addition of ASO to NF-kappaB improved both cytokine inhibition and animal survival in endotoxic shock.

  8. Next-generation models for Canadian collaboration in international ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Through this project, the Canadian Council for International Cooperation (CCIC), in partnership with the Canadian Association for the Study of International Development, will identify and promote new ways for Canadian practitioners, academics, and public policymakers to work together in international development.

  9. Structure of Energetic Particle Mediated Shocks Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Mostafavi, P.; Zank, G. P. [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Webb, G. M. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2017-05-20

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  10. Structure of Energetic Particle Mediated Shocks Revisited

    Science.gov (United States)

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2017-05-01

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1. We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  11. Matrix stochastic analysis of the maintainability of a machine under shocks

    International Nuclear Information System (INIS)

    Montoro-Cazorla, Delia; Pérez-Ocón, Rafael

    2014-01-01

    We study the maintenance of a machine operating under environmental conditions producing shocks affecting the lifetime of the machine. The shocks cause different types of damage depending on their strength and eventually the total failure. The maintenance of the machine is performed by repairs and replacement. The interarrival times of shocks are dependent. We introduce a multidimensional stochastic model for simulating the evolution of the lifetime of the machine. This model implies the application of the matrix-analytic methods, that are being used in stochastic modelling with interesting results. Under this methodology, the availability, the reliability, and the rates of occurrence of the different types of failures and of the replacements are calculated, obtaining mathematically tractable expressions. The results are applied to a numerical example. - Highlights: • A machine under random environmental conditions producing shocks and wear is studied under matrix-analytic methods. • There is dependence in the interarrival times of shocks. • Different types of failure producing damage in the internal and external structure of the machine are considered. • Maintenance is performed by repair and replacement. • Explicit expressions for the main reliability performance measures are given

  12. Shock-induced devolatilization of calcite

    Science.gov (United States)

    Boslough, M. B.; Ahrens, T. J.; Vizgirda, J.; Becker, R. H.; Epstein, S.

    1982-01-01

    Experimental measurements of the release adiabats by Vizgirda (1981) indicate that substantial vaporization takes place upon release from shock pressures of 37 GPa for calcite and 14 GPa for aragonite. The present investigation includes the first controlled partial vaporization experiments on calcite. The experiments were conducted to test the predictions of the release adiabat experiments. The quantities of the gaseous species produced from shocked calcite and their carbon and oxygen isotopic compositions were determined, and the shock-induced effect on the Mn(2+) electron spin resonance spectrum in the shock-recovered calcite was observed. On the basis of the obtained results, it is concluded that shock stresses at the 17-18 GPa level give rise to volatilization of 0.03-0.3 (mole) percent of calcite to CO2 and CO. The devolatilization of calcite occurs at low pressure at significantly lower entropy densities than predicted on the basis of thermodynamic continuum models.

  13. HLA-DR polymorphisms influence in vivo responses to staphylococcal toxic shock syndrome toxin-1 in a transgenic mouse model.

    Science.gov (United States)

    Krogman, A; Tilahun, A; David, C S; Chowdhary, V R; Alexander, M P; Rajagopalan, G

    2017-01-01

    Toxic shock syndrome toxin-1 (TSST-1) is a potent superantigen produced by Staphylococcus aureus. In addition to menstrual and nonmenstrual toxic shock syndromes, TSST-1 is also implicated in the immunopathogenesis of pneumonia, infective endocarditis, neonatal exanthematous disease, and atopic dermatitis among others. Superantigens first bind to major histocompatibility complex (MHC) class II molecules and then activate a large proportion of T cells by cross-linking their T cell receptor. As binding to MHC class II molecules is a critical step in the robust activation of the immune system by TSST-1 and other superantigens, polymorphic variations between different HLA-DR alleles could potentially influence the magnitude of immune activation and immunopathology caused by TSST-1. As TSST-1 is highly toxic to humans and given that multiple variations of alleles of HLA-DR and HLA-DQ are expressed in each individual, it is difficult to determine how HLA-DR polymorphisms quantitatively and qualitatively impact immune activation caused by TSST-1 in humans. However, such investigations can be conducted on transgenic mice lacking all endogenous MHC class II molecules and expressing specific HLA class II alleles. Therefore, transgenic mice expressing different HLA-DRB1 alleles (HLA-DRB1*15:01, HLA-DRB1*15:02, HLA-DRB1*03:01, HLA-DRB1*04:01), and sharing HLA-A1*01:01 chain, were systemically challenged with purified TSST-1 and multiple immune parameters were assessed. Among the HLA-DR alleles, mice expressing HLA-DRB1*15:01 allele elicited a significantly higher serum cytokine/chemokine response; greater splenic T cell expansion and most severe organ pathology. Our study highlights the potential utility of human leukocyte antigen (HLA) transgenic mice in understanding the impact of HLA polymorphisms on the outcomes of diseases caused by TSST-1 and other superantigens. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. On the Accurate Determination of Shock Wave Time-Pressure Profile in the Experimental Models of Blast-Induced Neurotrauma

    Directory of Open Access Journals (Sweden)

    Maciej Skotak

    2018-02-01

    Full Text Available Measurement issues leading to the acquisition of artifact-free shock wave pressure-time profiles are discussed. We address the importance of in-house sensor calibration and data acquisition sampling rate. Sensor calibration takes into account possible differences between calibration methodology in a manufacturing facility, and those used in the specific laboratory. We found in-house calibration factors of brand new sensors differ by less than 10% from their manufacturer supplied data. Larger differences were noticeable for sensors that have been used for hundreds of experiments and were as high as 30% for sensors close to the end of their useful lifetime. These observations were despite the fact that typical overpressures in our experiments do not exceed 50 psi for sensors that are rated at 1,000 psi maximum pressure. We demonstrate that sampling rate of 1,000 kHz is necessary to capture the correct rise time values, but there were no statistically significant differences between peak overpressure and impulse values for low-intensity shock waves (Mach number <2 at lower rates. We discuss two sources of experimental errors originating from mechanical vibration and electromagnetic interference on the quality of a waveform recorded using state-of-the-art high-frequency pressure sensors. The implementation of preventive measures, pressure acquisition artifacts, and data interpretation with examples, are provided in this paper that will help the community at large to avoid these mistakes. In order to facilitate inter-laboratory data comparison, common reporting standards should be developed by the blast TBI research community. We noticed the majority of published literature on the subject limits reporting to peak overpressure; with much less attention directed toward other important parameters, i.e., duration, impulse, and dynamic pressure. These parameters should be included as a mandatory requirement in publications so the results can be properly

  15. Relativistic simulations of long-lived reverse shocks in stratified ejecta: the origin of flares in GRB afterglows

    Science.gov (United States)

    Lamberts, A.; Daigne, F.

    2018-02-01

    The X-ray light curves of the early afterglow phase from gamma-ray bursts (GRBs) present a puzzling variability, including flares. The origin of these flares is still debated, and often associated with a late activity of the central engine. We discuss an alternative scenario where the central engine remains short-lived and flares are produced by the propagation of a long-lived reverse shock in a stratified ejecta. Here we focus on the hydrodynamics of the shock interactions. We perform one-dimensional ultrarelativistic hydrodynamic simulations with different initial internal structure in the GRB ejecta. We use them to extract bolometric light curves and compare with a previous study based on a simplified ballistic model. We find a good agreement between both approaches, with similar slopes and variability in the light curves, but identify several weaknesses in the ballistic model: the density is underestimated in the shocked regions, and more importantly, late shock reflections are not captured. With accurate dynamics provided by our hydrodynamic simulations, we confirm that internal shocks in the ejecta lead to the formation of dense shells. The interaction of the long-lived reverse shock with a dense shell then produces a fast and intense increase of the dissipated power. Assuming that the emission is due to the synchrotron radiation from shock-accelerated electrons, and that the external forward shock is radiatively inefficient, we find that this results in a bright flare in the X-ray light curve, with arrival times, shapes, and duration in agreement with the observed properties of X-ray flares in GRB afterglows.

  16. Grain Destruction in a Supernova Remnant Shock Wave

    Science.gov (United States)

    Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi

    2014-01-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV (lambda)1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the shock is too high compared to the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- shock medium limit our ability to test dust destruction models in detail.

  17. BOP Crises and External Shocks

    OpenAIRE

    Kitano, Shigeto

    2003-01-01

    This is a theoretical study of BOP crises in emerging markets in East Asia and LatinAmerica in the l990s. These BOP crises tend to be preceded by the current account deterioration, the real exchange rate appreciation, and inflationary pressures. The paper develops a model of BOP crises preceded by these macroeconomic phenomena. The model shows that an external shock (a decrease in the world nominal interest rate) leads to this type of BOP crises.

  18. Vibration analysis on compact car shock absorber

    Science.gov (United States)

    Tan, W. H.; Cheah, J. X.; Lam, C. K.; Lim, E. A.; Chuah, H. G.; Khor, C. Y.

    2017-10-01

    Shock absorber is a part of the suspension system which provides comfort experience while driving. Resonance, a phenomenon where forced frequency is coinciding with the natural frequency has significant effect on the shock absorber itself. Thus, in this study, natural frequencies of the shock absorber in a 2 degree-of-freedom system were investigated using Wolfram Mathematica 11, CATIA, and ANSYS. Both theoretical and simulation study how will the resonance affect the car shock absorber. The parametric study on the performance of shock absorber also had been conducted. It is found that the failure tends to occur on coil sprung of the shock absorber before the body of the shock absorber is fail. From mathematical modelling, it can also be seen that higher vibration level occurred on un-sprung mass compare to spring mass. This is due to the weight of sprung mass which could stabilize as compared with the weight of un-sprung mass. Besides that, two natural frequencies had been obtained which are 1.0 Hz and 9.1 Hz for sprung mass and un-sprung mass respectively where the acceleration is recorded as maximum. In conclusion, ANSYS can be used to validate with theoretical results with complete model in order to match with mathematical modelling.

  19. Shock propagation in a heterogeneous medium

    International Nuclear Information System (INIS)

    Elbaz, D.

    2011-01-01

    In the frame of the inertial confinement fusion in direct drive, the use of foams as ablator allows the reduction of hydrodynamic instabilities created on the target by the direct laser irradiation. The foam is made up of carbon (CH) fibers impregnated of cryogenic deuterium-tritium (DT). In the past, studies have been carried out considering this foam to be a homogeneous medium. Yet, the foam presents heterogeneous features. We study the effects of this heterogeneity on the shock velocity when the laser irradiates the target. Thanks to experimental and numerical studies, we show that the shock propagates faster in the heterogeneous medium than in the homogeneous one with the same averaged density. This velocity gap depends on the presence rate of the CH fibers in the foam, the density ratio, the adiabatic coefficient and the foam geometry. We model the foam by different ways, more and more complex. The shock velocity modification is due to the baroclinicity which, during the interaction between the shock front and the interface, creates a vorticity deposition, responsible for the shock acceleration. Accordingly, an interface, which is plane and perpendicular to the front shock, maximizes the vorticity deposition and increases the velocity gaps between heterogeneous and homogeneous media. We found a correlation between the kinetic energy behind the shock front and the velocities relative difference. We compared our results with two analytical models. However, the system is not closed, so we can't for the moment develop a predictive model. (author) [fr

  20. Shock waves & explosions

    CERN Document Server

    Sachdev, PL

    2004-01-01

    Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...