An LDA (Laser-Doppler Anemometry) investigation of three-dimensional normal shock wave boundary-layer interactions

NASA Technical Reports Server (NTRS)

Chriss, R. M.; Hingst, W. R.; Strazisar, A. J.; Keith, T. G., Jr.

1989-01-01

Nonintrusive measurements were made of a normal shock wave/boundary layer interaction. Two dimensional measurements were made throughout the interaction region while 3-D measurements were made in the vicinity of the shock wave. The measurements were made in the corner of the test section of a continuous supersonic wind tunnel in which a normal shock wave had been stabilized. Laser Doppler Anemometry, surface pressure measurement and flow visualization techniques were employed for two freestream Mach number test cases: 1.6 and 1.3. The former contained separated flow regions and a system of shock waves. The latter was found to be far less complicated. The results define the flow field structure in detail for each case.

Formation of gyrotropic and non gyrotropic field-aligned beams in the Earth's quasi-perpendicular Ion Foreshock: Full-particle 2D simulation results

NASA Astrophysics Data System (ADS)

Savoini, P.; Lembege, B.

2013-12-01

The ion foreshock located upstream of the Earth's bow shock is populated with ions reflected back by the shock front with an high energy gain. In-situ spacecraft measurements have clearly established the existence of two distinct populations in the foreshock upstream of quasi-perpendicular shock region (i.e. for 45° ≤ ΘBn≤ 90°, where ΘBn is the angle between the shock normal and the upstream magnetostatic field): (i) field-aligned (';FAB') ion beams characterized by a gyrotropic distribution, and (ii) gyro-phase bunched (';GPB') ions characterized by a NON gyrotropic distribution, which exhibits a non-vanishing perpendicular bulk velocity. The purpose of the present work is to identify the possible sources of the different backstreaming ions and is based on the use of 2D PIC simulations of a curved shock, where full curvature effects, time of flight effects and both electrons and ions dynamics are fully described by a self consistent approach. Our analysis evidences that the two populations mentionned above may have different origins identified both in terms of interaction time and distance of penetration within the shock front. In particular, ours simulations evidence that "GPB" and ';FAB' populations are characterized by a short (Δinter= 1 to 2 tci) and much larger (Δinter= 1 to 10 tci) interaction time respectively, where τci is the ion upstream gyroperiod. In addition, a deeper statistical analysis of ion trajectories evidences that: (i) both populations can be discriminated in terms of injection angle into the shock front (i.e. defined between the local normal to the shock front and the gyration velocity vector at the time ions reach the front). Such a behavior explains how reflected ions can be splitted in the observed two populations "FAB" and "GPB". (ii) ion trajectories strongly differ between the "FAB" and "GPB" populations at the shock front. In particular, ';FAB' ions suffer multi-bounces whereas ';GPB '; ions make only one bounce. Such differences can explain why the ';FAB' population loses their gyro-phase coherency and become gyrotropic which is not the case for the "GPB". As evidenced by these simulations the origin of both populations can be associated directly to their interaction with the shock front itself and do not require any upstream instability which can be another source for such backstreaming ions.

[Clinical study on the postburn change in the hypothalamus-pituitary-adrenal hormones in severely burned patients].

PubMed

Li, Hong-mian; Liang, Zi-qian; Luo, Zuo-jie

2003-06-01

To investigate the postburn dynamic changes in the hypothalamus-pituitary-adrenal hormones in severely burned patients. Fifty burn patients were enrolled in the study. The plasma contents of total GC (cortisol), ACTH and aldosterone (ALDO) and urinary contents of 17-OHO and 17-KS were determined with radio-immunological assay (RIA) method after burn injury to compare with the normal values which were well established clinically. The postburn plasma and urinary contents of the above indices were increased evidently with two peak values in shock and infectious stages, whilst the majority of he indices were lower than the normal values after 6 postburn weeks (PBWs). The values of these hormones were the lowest in dying patients. On the other hand, the values approached normal levels in those patients whose burn wounds were healing. Increases of the plasma and urinary levels of hypothalamus-pituitary -adrenal hormones in severely burned patients were constantly seen. Burn shock and infection seemed to be the two major factors in inducing postburn stress reaction in burn victims. Abrupt decrease of the hormone levels in plasma and or urine indicated adrenal failure predicting a poor prognosis of the burn patients.

Interplanetary fast shocks and associated drivers observed through the 23rd solar minimum by Wind over its first 2.5 years

NASA Astrophysics Data System (ADS)

Berdichevsky, Daniel B.; Szabo, Adam; Lepping, Ronald P.; Viñas, Adolfo F.; Mariani, Franco

2000-12-01

A list of the interplanetary shocks observed by Wind from its launch (in Nov 1994) to May 1997 is presented. The magnetohydrodynamic nature of the shocks is investigated, and the associated shock parameters and their uncertainties are accurately computed using two techniques. These are: 1) a combination of the ``preaveraged'' magnetic-coplanarity, velocity-coplanarity, and the Abraham-Schrauner-mixed methods, and 2) the Viñas and Scudder [1986] technique for solving the nonlinear least squares Rankine-Hugoniot equations. Within acceptable limits these two techniques generally gave the same results, with some exceptions. The reasons for the exceptions are discussed. The mean strength and rate of occurrence of the shocks appear to correlate with the solar cycle. Both showed a decrease in 1996 coincident with the time of the lowest ultraviolet solar radiance, indicative of solar minimum and the beginning of solar cycle 23. Eighteen shocks appeared to be associated with corotating interaction regions (CIRs). The shock normal distribution showed a mean direction peaking in the ecliptic plane and with a longitude of ~200° (GSE coordinates). Another 16 shocks were determined to be driven by solar transients, including magnetic clouds. These had a broader distribution of normal directions than those of the CIR cases with a mean direction close to the Sun-Earth line. Eight shocks of unknown origin had normal orientations far off the ecliptic plane. No shock propagated with longitude φn>=220+/-10°, i.e. against the average Parker spiral direction. Examination of the obliquity angle θBn (i.e., between the shock normal and the upstream interplanetary magnetic field) for the full set of shocks revealed that about 58% were quasi-perpendicular, and about 32% of the shocks oblique, and the rest quasi-parallel. Small uncertainty in the estimated angle θBn was obtained for about 10 shocks with magnetosonic Mach numbers between 1 and 2.

Shock-wave studies of anomalous compressibility of glassy carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molodets, A. M., E-mail: molodets@icp.ac.ru; Golyshev, A. A.; Savinykh, A. S.

2016-02-15

The physico-mechanical properties of amorphous glassy carbon are investigated under shock compression up to 10 GPa. Experiments are carried out on the continuous recording of the mass velocity of compression pulses propagating in glassy carbon samples with initial densities of 1.502(5) g/cm{sup 3} and 1.55(2) g/cm{sup 3}. It is shown that, in both cases, a compression wave in glassy carbon contains a leading precursor with amplitude of 0.135(5) GPa. It is established that, in the range of pressures up to 2 GPa, a shock discontinuity in glassy carbon is transformed into a broadened compression wave, and shock waves are formedmore » in the release wave, which generally means the anomalous compressibility of the material in both the compression and release waves. It is shown that, at pressure higher than 3 GPa, anomalous behavior turns into normal behavior, accompanied by the formation of a shock compression wave. In the investigated area of pressure, possible structural changes in glassy carbon under shock compression have a reversible character. A physico-mechanical model of glassy carbon is proposed that involves the equation of state and a constitutive relation for Poisson’s ratio and allows the numerical simulation of physico-mechanical and thermophysical properties of glassy carbon of different densities in the region of its anomalous compressibility.« less

Quasi One-Dimensional Unsteady Modeling of External Compression Supersonic Inlets

NASA Technical Reports Server (NTRS)

Kopasakis, George; Connolly, Joseph W.; Kratz, Jonathan

2012-01-01

The AeroServoElasticity task under the NASA Supersonics Project is developing dynamic models of the propulsion system and the vehicle in order to conduct research for integrated vehicle dynamic performance. As part of this effort, a nonlinear quasi 1-dimensional model of an axisymmetric external compression supersonic inlet is being developed. The model utilizes compressible flow computational fluid dynamics to model the internal inlet segment as well as the external inlet portion between the cowl lip and normal shock, and compressible flow relations with flow propagation delay to model the oblique shocks upstream of the normal shock. The external compression portion between the cowl-lip and the normal shock is also modeled with leaking fluxes crossing the sonic boundary, with a moving CFD domain at the normal shock boundary. This model has been verified in steady state against tunnel inlet test data and it s a first attempt towards developing a more comprehensive model for inlet dynamics.

A surge of light at the birth of a supernova.

PubMed

Bersten, M C; Folatelli, G; García, F; Van Dyk, S D; Benvenuto, O G; Orellana, M; Buso, V; Sánchez, J L; Tanaka, M; Maeda, K; Filippenko, A V; Zheng, W; Brink, T G; Cenko, S B; de Jaeger, T; Kumar, S; Moriya, T J; Nomoto, K; Perley, D A; Shivvers, I; Smith, N

2018-02-21

It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.

A surge of light at the birth of a supernova

NASA Astrophysics Data System (ADS)

Bersten, M. C.; Folatelli, G.; García, F.; van Dyk, S. D.; Benvenuto, O. G.; Orellana, M.; Buso, V.; Sánchez, J. L.; Tanaka, M.; Maeda, K.; Filippenko, A. V.; Zheng, W.; Brink, T. G.; Cenko, S. B.; de Jaeger, T.; Kumar, S.; Moriya, T. J.; Nomoto, K.; Perley, D. A.; Shivvers, I.; Smith, N.

2018-02-01

It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.

Synthesis of 19-substituted geldanamycins with altered conformations and their binding to heat shock protein Hsp90

PubMed Central

Kitson, Russell R. A.; Chang, Chuan-Hsin; Xiong, Rui; Williams, Huw E. L.; Davis, Adrienne L.; Lewis, William; Dehn, Donna L.; Siegel, David; Roe, S. Mark; Prodromou, Chrisostomos; Ross, David; Moody, Christopher J.

2013-01-01

The benzoquinone ansamycin geldanamycin and its derivatives are inhibitors of heat shock protein Hsp90, an emerging target for novel therapeutic agents both in cancer and in neurodegeneration. However, toxicity of these compounds to normal cells has been ascribed to reaction with thiol nucleophiles at the quinone 19-position. We reasoned that blocking this position would ameliorate toxicity, and that it might also enforce a favourable conformational switch of the trans-amide group into the cis-form required for protein binding. We report here an efficient synthesis of such 19-substituted compounds and realization of our hypotheses. Protein crystallography established that the new compounds bind to Hsp90 with, as expected, a cis-amide conformation. Studies on Hsp90 inhibition in cells demonstrated the molecular signature of Hsp90 inhibitors: decreases in client proteins with compensatory increases in other heat shock proteins in both human breast cancer and dopaminergic neural cells, demonstrating their potential for use in the therapy of cancer or neurodegenerative diseases. PMID:23511419

Dynamic calibration of fast-response probes in low-pressure shock tubes

NASA Astrophysics Data System (ADS)

Persico, G.; Gaetani, P.; Guardone, A.

2005-09-01

Shock tube flows resulting from the incomplete burst of the diaphragm are investigated in connection with the dynamic calibration of fast-response pressure probes. As a result of the partial opening of the diaphragm, pressure disturbances are observed past the shock wave and the measured total pressure profile deviates from the envisaged step signal required by the calibration process. Pressure oscillations are generated as the initially normal shock wave diffracts from the diaphragm's orifice and reflects on the shock tube walls, with the lowest local frequency roughly equal to the ratio of the sound speed in the perturbed region to the shock tube diameter. The energy integral of the perturbations decreases with increasing distance from the diaphragm, as the diffracted leading shock and downwind reflections coalesce into a single normal shock. A procedure is proposed to calibrate fast-response pressure probes downwind of a partially opened shock tube diaphragm.

Computation of Thermally Perfect Properties of Oblique Shock Waves

NASA Technical Reports Server (NTRS)

Tatum, Kenneth E.

1996-01-01

A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon a value of cp expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135, and with a state-of-the-art computational fluid dynamics code. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use, and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

Molecular cloud formation in high-shear, magnetized colliding flows

NASA Astrophysics Data System (ADS)

Fogerty, E.; Frank, A.; Heitsch, F.; Carroll-Nellenback, J.; Haig, C.; Adams, M.

2016-08-01

The colliding flows (CF) model is a well-supported mechanism for generating molecular clouds. However, to-date most CF simulations have focused on the formation of clouds in the normal-shock layer between head-on colliding flows. We performed simulations of magnetized colliding flows that instead meet at an oblique-shock layer. Oblique shocks generate shear in the post-shock environment, and this shear creates inhospitable environments for star formation. As the degree of shear increases (I.e. the obliquity of the shock increases), we find that it takes longer for sink particles to form, they form in lower numbers, and they tend to be less massive. With regard to magnetic fields, we find that even a weak field stalls gravitational collapse within forming clouds. Additionally, an initially oblique collision interface tends to reorient over time in the presence of a magnetic field, so that it becomes normal to the oncoming flows. This was demonstrated by our most oblique shock interface, which became fully normal by the end of the simulation.

Giotto magnetic field observations at the outbound quasi-parallel bow shock of Comet Halley

NASA Technical Reports Server (NTRS)

Neubauer, F. M.; Glassmeier, K. H.; Acuna, M. H.; Mariani, F.; Musmann, G.

1990-01-01

The investigation of the outbound bow shock of Comet Halley using Giotto magnetometer data leads to the following results: the shock is characterized by strong magnetic turbulence associated with an increasing background magnetic field and a change in direction by 60 deg as one goes inward. In HSE-coordinates, the observed normal turned out to be (0.544, - 0.801, 0.249). The thickness of the quasi-parallel shock was 120,000 km. The shock is shown to be a new type of shock transition called a 'draping shock'. In a draping shock with high beta in the transonic transition region, the transonic region is characterized by strong directional variations of the magnetic field. The magnetic turbulence ahead of the shock is characterized by k-vectors parallel or antiparallel to the average field (and, therefore, also to the normal of the quasi-parallel shock) and almost isotropic magnetic turbulence in the shock transition region. A model of the draping shock is proposed which also includes a hypothetical subshock in which the supersonic-subsonic transition is accomplished.

Numerical solutions of Navier-Stokes equations for compressible turbulent two/three dimensional flows in terminal shock region of an inlet/diffuser

NASA Technical Reports Server (NTRS)

Liu, N. S.; Shamroth, S. J.; Mcdonald, H.

1983-01-01

The multidimensional ensemble averaged compressible time dependent Navier Stokes equations in conjunction with mixing length turbulence model and shock capturing technique were used to study the terminal shock type of flows in various flight regimes occurring in a diffuser/inlet model. The numerical scheme for solving the governing equations is based on a linearized block implicit approach and the following high Reynolds number calculations were carried out: (1) 2 D, steady, subsonic; (2) 2 D, steady, transonic with normal shock; (3) 2 D, steady, supersonic with terminal shock; (4) 2 D, transient process of shock development and (5) 3 D, steady, transonic with normal shock. The numerical results obtained for the 2 D and 3 D transonic shocked flows were compared with corresponding experimental data; the calculated wall static pressure distributions agree well with the measured data.

Table and charts of equilibrium normal shock and shock tube properties for pure argon with velocities to 18 km/sec

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1976-01-01

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure argon. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular-weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 2 to 18 km/sec for a range of initial pressure of 5 N/sq m to 500 kN/sq m. Working charts illustrating shock tube performance with argon test gas and heated helium and hydrogen driver gases are also presented.

Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

NASA Technical Reports Server (NTRS)

Wilson, L. B., III

2012-01-01

We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves.

Normal- and oblique-shock flow parameters in equilibrium air including attached-shock solutions for surfaces at angles of attack, sweep, and dihedral

NASA Technical Reports Server (NTRS)

Hunt, J. L.; Souders, S. W.

1975-01-01

Normal- and oblique-shock flow parameters for air in thermochemical equilibrium are tabulated as a function of shock angle for altitudes ranging from 15.24 km to 91.44 km in increments of 7.62 km at selected hypersonic speeds. Post-shock parameters tabulated include flow-deflection angle, velocity, Mach number, compressibility factor, isentropic exponent, viscosity, Reynolds number, entropy difference, and static pressure, temperature, density, and enthalpy ratios across the shock. A procedure is presented for obtaining oblique-shock flow properties in equilibrium air on surfaces at various angles of attack, sweep, and dihedral by use of the two-dimensional tabulations. Plots of the flow parameters against flow-deflection angle are presented at altitudes of 30.48, 60.96, and 91.44 km for various stream velocities.

Shock Boundary Layer Interaction Flow Control with Micro Vortex Generators

DTIC Science & Technology

2011-05-01

Pitot rake ( p̄02p01 ) u = time-averaged streamwise velocity ufs = time-averaged freestream streamwise velocity u∗ = √ τw ρw = wall-shear velocity w...upstream of the normal shock-wave 2 = station 2, at the Pitot rake location I. Introduction With the exception of the scramjet, all current air-breathing...to this.7 1 shock holder near-normal shock μVGs 123 143 14 hole Pitot rake 6o x vg variable φ cylinder mounted on the centre-line 380 M ∞ =1.4

Low-energy ion acceleration at quasi-perpendicular shocks: Transverse diffusion

NASA Technical Reports Server (NTRS)

Giacalone, J.; Jokipii, J. R.

1995-01-01

The problem of ion injection and acceleration at quasi perpendicular shocks has been the subject of some debate over the past two decades. It is widely known that these shocks efficiently accelerate particles that are well in the high-energy tail of the distribution. However, the issue of injection, or the acceleration of low-energy ions, has yet to reach a consensus. The fundamental issue is whether there is enough diffusion normal to the magnetic field for the particles to remain near the shock. Since transverse diffusion is a physical process that is not well understood in space plasmas, this is an important, and difficult issue to address. In this report, we will investigate the ion injection problem by performing test particle orbit integrations using synthesized turbulent fields. These fields are fully three-dimensional so that transverse diffusion is possible (cross-field diffusion is not possible in geometries where the electromagnetic fields are less than three dimensional). The synthesized fields are produced by superimposing a three-dimensional wave field on a background field. For completeness, we will compare the results from this model with the more well-established theories, such as the diffusive approximation and scatter-free shock drift acceleration. We will also compare these results with other numerical simulation techniques such as the well known hybrid simulation, and other test-particle calculations in which the shock fields are specified to have less than three dimensions. We will also discuss some recent relevant observations and how these compare with our results.

Interplanetary Fast Shocks and Associated Drivers Observed through the Twenty-Third Solar Minimum by WIND Over its First 2.5 Years

NASA Technical Reports Server (NTRS)

Mariani, F.; Berdichevsky, D.; Szabo, A.; Lepping, R. P.; Vinas, A. F.

1999-01-01

A list of the interplanetary (IP) shocks observed by WIND from its launch (in November 1994) to May 1997 is presented. Forty two shocks were identified. The magnetohydrodynamic nature of the shocks is investigated, and the associated shock parameters and their uncertainties are accurately computed using a practical scheme which combines two techniques. These techniques are a combination of the "pre-averaged" magnetic-coplanarity, velocity-coplanarity, and the Abraham-Schrauner-mixed methods, on the one hand, and the Vinas and Scudder [1986] technique for solving the non-linear least-squares Rankine-Hugoniot shock equations, on the other. Within acceptable limits these two techniques generally gave the same results, with some exceptions. The reasons for the exceptions are discussed. It is found that the mean strength and rate of occurrence of the shocks appears to correlated with the solar cycle. Both showed a decrease in 1996 coincident with the time of the lowest ultraviolet solar radiance, indicative of solar minimum and start of solar cycle 23, which began around June 1996. Eighteen shocks appeared to be associated with corotating interaction regions (CIRs). The distribution of their shock normals showed a mean direction peaking in the ecliptic plane and with a longitude (phi(sub n)) in that plane between perpendicular to the Parker spiral and radial from the Sun. When grouped according to the sense of the direction of propagation of the shocks the mean azimuthal (longitude) angle in GSE coordinates was approximately 194 deg for the fast-forward and approximately 20 deg for the fast-reverse shocks. Another 16 shocks were determined to be driven by solar transients, including magnetic clouds. These shocks had a broader distribution of normal directions than those of the CIR cases with a mean direction close to the Sun-Earth line. Eight shocks of unknown origin had normal orientation well off the ecliptic plane. No shock propagated with longitude phi(sub n) >= 220 +/- 10 deg, this would suggest strong hindrance to the propagation of shocks contra a rather tightly winding Parker spiral. Examination of the obliquity angle theta(sub Bn) (that between the shock normal and the upstream interplanetary magnetic field) for the full set of shocks revealed that about 58% was quasi-perpendicular, and some were very nearly perpendicular. About 32% of the shocks were oblique, and the rest (only 10%) were quasi-parallel, with one on Dec. 9, 1996 that showed field pulsations. Small uncertainty in the estimated angle theta(sub Bn) was obtained for about 10 shocks with magnetosonic Mach numbers between 1 and 2, hopefully significantly contributing to studies researching particle acceleration mechanisms at IP shocks, and to investigations where accurate values of theta(sub Bn) are crucial.

Table and charts of equilibrium normal-shock and shock-tube properties for pure carbon dioxide with velocities from 1 to 16 km/sec

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1976-01-01

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure CO2. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 1 to 16 km/sec for a range of initial pressure of 5 N/sq m to 500 kN/sq m. The present results are applicable to shock tube flows and to freeflight conditions for a blunt body at high velocities. Working charts illustrating idealized shock tube performance with CO2 test gas and heated helium and hydrogen driver gases are also presented.

[Lethal anaphylactic shock model induced by human mixed serum in guinea pigs].

PubMed

Ren, Guang-Mu; Bai, Ji-Wei; Gao, Cai-Rong

2005-08-01

To establish an anaphylactic shock model induced by human mixed serum in guinea pigs. Eighteen guinea pigs were divided into two groups: sensitized and control, The sensitized group were immunized intracutaneously with human mixed serum and then induced by endocardiac injection after 3 weeks. Symptoms of anaphylactic shock appeared in the sensitized group. The level of serum IgE were increased in the sensitized group significantly. An animal model of anaphylactic shock wer established successfully. It provide a tool for both forensic study and anaphylactic shock therapy.

Emissivity measurements of shocked tin using a multi-wavelength integrating sphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seifter, A; Holtkamp, D B; Iverson, A J

Pyrometric measurements of radiance to determine temperature have been performed on shock physics experiments for decades. However, multi-wavelength pyrometry schemes sometimes fail to provide credible temperatures in experiments, which incur unknown changes in sample emissivity, because an emissivity change also affects the spectral radiance. Hence, for shock physics experiments using pyrometry to measure temperatures, it is essential to determine the dynamic sample emissivity. The most robust way to determine the normal spectral emissivity is to measure the spectral normal-hemispherical reflectance using an integrating sphere. In this paper we describe a multi-wavelength (1.6–5.0 μm) integrating sphere system that utilizes a “reversed”more » scheme, which we use for shock physics experiments. The sample to be shocked is illuminated uniformly by scattering broadband light from inside a sphere onto the sample. A portion of the light reflected from the sample is detected at a point 12° from normal to the sample surface. For this experiment, we used the system to measure emissivity of shocked tin at four wavelengths for shock stress values between 17 and 33 GPa. The results indicate a large increase in effective emissivity upon shock release from tin when the shock is above 24–25 GPa, a shock stress that partially melts the sample. We also recorded an IR image of one of the shocked samples through the integrating sphere, and the emissivity inferred from the image agreed well with the integrating-sphere, pyrometer-detector data. Here, we discuss experimental data, uncertainties, and a data analysis process. We also describe unique emissivity-measurement problems arising from shock experiments and methods to overcome such problems.« less

Modeling normal shock velocity curvature relations for heterogeneous explosives

NASA Astrophysics Data System (ADS)

Yoo, Sunhee; Crochet, Michael; Pemberton, Steven

2017-01-01

The theory of Detonation Shock Dynamics (DSD) is, in part, an asymptotic method to model a functional form of the relation between the shock normal, its time rate and shock curvature κ. In addition, the shock polar analysis provides a relation between shock angle θ and the detonation velocity Dn that is dependent on the equations of state (EOS) of two adjacent materials. For the axial detonation of an explosive material confined by a cylinder, the shock angle is defined as the angle between the shock normal and the normal to the cylinder liner, located at the intersection of the shock front and cylinder inner wall. Therefore, given an ideal explosive such as PBX-9501 with two functional models determined, a unique, smooth detonation front shape ψ can be determined that approximates the steady state detonation shock front of the explosive. However, experimental measurements of the Dn(κ) relation for heterogeneous explosives such as PBXN-111 [D. K. Kennedy, 2000] are challenging due to the non-smoothness and asymmetry usually observed in the experimental streak records of explosion fronts. Out of many possibilities the asymmetric character may be attributed to the heterogeneity of the explosives; here, material heterogeneity refers to compositions with multiple components and having a grain morphology that can be modeled statistically. Therefore in extending the formulation of DSD to modern novel explosives, we pose two questions: (1) is there any simple hydrodynamic model that can simulate such an asymmetric shock evolution, and (2) what statistics can be derived for the asymmetry using simulations with defined structural heterogeneity in the unreacted explosive? Saenz, Taylor and Stewart [1] studied constitutive models for derivation of the Dn(κ) relation for porous homogeneous explosives and carried out simulations in a spherical coordinate frame. In this paper we extend their model to account for heterogeneity and present shock evolutions in heterogeneous explosives using 2-D hydrodynamic simulations with some statistical examination. As an initial work, we assume that the heterogeneity comes from the local density variation or porosity only.

Tables and charts of equilibrium normal shock and shock tube solutions for pure CO2 with velocities to 16 km/second

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1974-01-01

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure CO2, representative of Mars and Venus atmospheres. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, isentropic exponent, velocity and species mole fractions. Incident (moving) shock velocities are varied from 1 to 16 km/sec for a range of initial pressure of 5 Newtons per square meter to 500 kilo Newtons per square meter. The present results are applicable to shock tube flows, and to free-flight conditions for a blunt body at high velocities. Working charts illustrating idealized shock-tube performance with CO2 test gas and heated helium and hydrogen driver gases are also presented.

Injection of thermal and suprathermal seed particles into coronal shocks of varying obliquity

NASA Astrophysics Data System (ADS)

Battarbee, M.; Vainio, R.; Laitinen, T.; Hietala, H.

2013-10-01

Context. Diffusive shock acceleration in the solar corona can accelerate solar energetic particles to very high energies. Acceleration efficiency is increased by entrapment through self-generated waves, which is highly dependent on the amount of accelerated particles. This, in turn, is determined by the efficiency of particle injection into the acceleration process. Aims: We present an analysis of the injection efficiency at coronal shocks of varying obliquity. We assessed injection through reflection and downstream scattering, including the effect of a cross-shock potential. Both quasi-thermal and suprathermal seed populations were analysed. We present results on the effect of cross-field diffusion downstream of the shock on the injection efficiency. Methods: Using analytical methods, we present applicable injection speed thresholds that were compared with both semi-analytical flux integration and Monte Carlo simulations, which do not resort to binary thresholds. Shock-normal angle θBn and shock-normal velocity Vs were varied to assess the injection efficiency with respect to these parameters. Results: We present evidence of a significant bias of thermal seed particle injection at small shock-normal angles. We show that downstream isotropisation methods affect the θBn-dependence of this result. We show a non-negligible effect caused by the cross-shock potential, and that the effect of downstream cross-field diffusion is highly dependent on boundary definitions. Conclusions: Our results show that for Monte Carlo simulations of coronal shock acceleration a full distribution function assessment with downstream isotropisation through scatterings is necessary to realistically model particle injection. Based on our results, seed particle injection at quasi-parallel coronal shocks can result in significant acceleration efficiency, especially when combined with varying field-line geometry. Appendices are available in electronic form at http://www.aanda.org

On numerical instabilities of Godunov-type schemes for strong shocks

NASA Astrophysics Data System (ADS)

Xie, Wenjia; Li, Wei; Li, Hua; Tian, Zhengyu; Pan, Sha

2017-12-01

It is well known that low diffusion Riemann solvers with minimal smearing on contact and shear waves are vulnerable to shock instability problems, including the carbuncle phenomenon. In the present study, we concentrate on exploring where the instability grows out and how the dissipation inherent in Riemann solvers affects the unstable behaviors. With the help of numerical experiments and a linearized analysis method, it has been found that the shock instability is strongly related to the unstable modes of intermediate states inside the shock structure. The consistency of mass flux across the normal shock is needed for a Riemann solver to capture strong shocks stably. The famous carbuncle phenomenon is interpreted as the consequence of the inconsistency of mass flux across the normal shock for a low diffusion Riemann solver. Based on the results of numerical experiments and the linearized analysis, a robust Godunov-type scheme with a simple cure for the shock instability is suggested. With only the dissipation corresponding to shear waves introduced in the vicinity of strong shocks, the instability problem is circumvented. Numerical results of several carefully chosen strong shock wave problems are investigated to demonstrate the robustness of the proposed scheme.

Two-Fluid Description of Collisionless Perpendicular Shocks

NASA Astrophysics Data System (ADS)

Gomez, D. O.; Morales, L. F.; Dmitruk, P.; Bertucci, C.

2017-12-01

Collisionless shocks are ubiquitous in space physics and astrophysics, such as the bow shocks formed by the solar wind in front of planets, the termination shock at the heliospheric boundary or the supernova shock fronts expanding in the interstellar plasma. Although the one-fluid magnetohydrodynamic framework provides a reasonable description of the large scale structures of the upstream and downstream plasmas, it falls short of providing an adequate description of the internal structure of the shock. A more comprehensive description of the inner and outer features of collisionless shocks would require the use of kinetic theory. Nonetheless, in the present work we show that a complete two-fluid framework (considering the role of both ions and electrons in the dynamics) can properly capture some of the features observed in real shocks. For the specific case of perpendicular shocks, i.e. cases in which the magnetic field is perpendicular to the shock normal, we integrate the one-dimensional two-fluid MHD equations numerically, to describe the generation of shocks and their spatial structure along the shock normal. Starting from finite amplitude fast-magnetosonic waves, our simulations show the generation of a stationary fast-magnetosonic shock. More importantly, we show that the ramp thickness is of the order of a few electron inertial lengths. The parallel and perpendicular components of the self-consistent electric field are derived, and their role in accelerating particles is discussed.

An experimental investigation of compressible three-dimensional boundary layer flow in annular diffusers

NASA Technical Reports Server (NTRS)

Om, Deepak; Childs, Morris E.

1987-01-01

An experimental study is described in which detailed wall pressure measurements have been obtained for compressible three-dimensional unseparated boundary layer flow in annular diffusers with and without normal shock waves. Detailed mean flow-field data were also obtained for the diffuser flow without a shock wave. Two diffuser flows with shock waves were investigated. In one case, the normal shock existed over the complete annulus whereas in the second case, the shock existed over a part of the annulus. The data obtained can be used to validate computational codes for predicting such flow fields. The details of the flow field without the shock wave show flow reversal in the circumferential direction on both inner and outer surfaces. However, there is a lag in the flow reversal between the inner nad the outer surfaces. This is an interesting feature of this flow and should be a good test for the computational codes.

Transit Time and Normal Orientation of ICME-driven Shocks

NASA Astrophysics Data System (ADS)

Case, A. W.; Spence, H.; Owens, M.; Riley, P.; Linker, J.; Odstrcil, D.

2006-12-01

Interplanetary Coronal Mass Ejections (ICMEs) can drive shocks that accelerate particles to great energies. It is important to understand the acceleration, transport, and spectra of these particles in order to quantify this fundamental physical process operating throughout the cosmos. This understanding also helps to better protect astronauts and spacecraft in upcoming missions. We show that the ambient solar wind is crucial in determining characteristics of ICME-driven shocks, which in turn affect energetic particle production. We use a coupled 3-D MHD code of the corona and heliosphere to simulate ICME propagation from 30 solar radii to 1AU. ICMEs of different velocities are injected into a realistic solar wind to determine how the initial speed affects the shape and deceleration of the ICME-driven shock. We use shock transit time and shock normal orientation to quantify these dependencies. We also inject identical ICMEs into different ambient solar winds to quantify the effective drag force on an ICME.

Entropy considerations applied to shock unsteadiness in hypersonic inlets

NASA Astrophysics Data System (ADS)

Bussey, Gillian Mary Harding

The stability of curved or rectangular shocks in hypersonic inlets in response to flow perturbations can be determined analytically from the principle of minimum entropy. Unsteady shock wave motion can have a significant effect on the flow in a hypersonic inlet or combustor. According to the principle of minimum entropy, a stable thermodynamic state is one with the lowest entropy gain. A model based on piston theory and its limits has been developed for applying the principle of minimum entropy to quasi-steady flow. Relations are derived for analyzing the time-averaged entropy gain flux across a shock for quasi-steady perturbations in atmospheric conditions and angle as a perturbation in entropy gain flux from the steady state. Initial results from sweeping a wedge at Mach 10 through several degrees in AEDC's Tunnel 9 indicates the bow shock becomes unsteady near the predicted normal Mach number. Several curved shocks of varying curvature are compared to a straight shock with the same mean normal Mach number, pressure ratio, or temperature ratio. The present work provides analysis and guidelines for designing an inlet robust to off- design flight or perturbations in flow conditions an inlet is likely to face. It also suggests that inlets with curved shocks are less robust to off-design flight than those with straight shocks such as rectangular inlets. Relations for evaluating entropy perturbations for highly unsteady flow across a shock and limits on their use were also developed. The normal Mach number at which a shock could be stable to high frequency upstream perturbations increases as the speed of the shock motion increases and slightly decreases as the perturbation size increases. The present work advances the principle of minimum entropy theory by providing additional validity for using the theory for time-varying flows and applying it to shocks, specifically those in inlets. While this analytic tool is applied in the present work for evaluating the stability of shocks in hypersonic inlets, it can be used for an arbitrary application with a shock.

Targeting Heat Shock Proteins in Cancer: A Promising Therapeutic Approach.

PubMed

Chatterjee, Suman; Burns, Timothy F

2017-09-15

Heat shock proteins (HSPs) are a large family of chaperones that are involved in protein folding and maturation of a variety of "client" proteins protecting them from degradation, oxidative stress, hypoxia, and thermal stress. Hence, they are significant regulators of cellular proliferation, differentiation and strongly implicated in the molecular orchestration of cancer development and progression as many of their clients are well established oncoproteins in multiple tumor types. Interestingly, tumor cells are more HSP chaperonage-dependent than normal cells for proliferation and survival because the oncoproteins in cancer cells are often misfolded and require augmented chaperonage activity for correction. This led to the development of several inhibitors of HSP90 and other HSPs that have shown promise both preclinically and clinically in the treatment of cancer. In this article, we comprehensively review the roles of some of the important HSPs in cancer, and how targeting them could be efficacious, especially when traditional cancer therapies fail.

Early initiation of low-dose hydrocortisone treatment for septic shock in adults: A randomized clinical trial.

PubMed

Lv, Qing-Quan; Gu, Xiao-Hua; Chen, Qi-Hong; Yu, Jiang-Quan; Zheng, Rui-Qiang

2017-12-01

Physiologic dose hydrocortisone is part of the suggested adjuvant therapies for patients with septic shock. However, the association between the corticosteroid therapy and mortality in patients with septic shock is still not clear. Some authors considered that the mortality is related to the time frame between development of septic shock and start of low dose hydrocortisone. Thus we designed a placebo-controlled, randomized clinical trial to assess the importance of early initiation of low dose hydrocortisone for the final outcome. A total of 118 patients with septic shock were recruited in the study. All eligible patients were randomized to receive hydrocortisone (n=58) or normal saline (n=60). The study medication (hydrocortisone and normal saline) was initiated simultaneously with vasopressors. The primary end-point was 28-day mortality. The secondary end-points were the reversal of shock, in-hospital mortality and the duration of ICU and hospital stay. The proportion of patients with reversal of shock was similar in the two groups (P=0.602); There were no significant differences in 28-day or hospital all-cause mortality; length of stay in the ICU or hospital between patients treated with hydrocortisone or normal saline. The early initiation of low-dose of hydrocortisone did not decrease the risk of mortality, and the length of stay in the ICU or hospital in adults with septic shock. www.clinicaltrials.govNCT02580240. Copyright © 2017 Elsevier Inc. All rights reserved.

Digital-computer normal shock position and restart control of a Mach 2.5 axisymmetric mixed-compression inlet

NASA Technical Reports Server (NTRS)

Neiner, G. H.; Cole, G. L.; Arpasi, D. J.

1972-01-01

Digital computer control of a mixed-compression inlet is discussed. The inlet was terminated with a choked orifice at the compressor face station to dynamically simulate a turbojet engine. Inlet diffuser exit airflow disturbances were used. A digital version of a previously tested analog control system was used for both normal shock and restart control. Digital computer algorithms were derived using z-transform and finite difference methods. Using a sample rate of 1000 samples per second, the digital normal shock and restart controls essentially duplicated the inlet analog computer control results. At a sample rate of 100 samples per second, the control system performed adequately but was less stable.

Observations of Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

NASA Technical Reports Server (NTRS)

Wilson, L. B., III; Koval, A.; Szabo, Adam; Breneman, A.; Cattell, C. A.; Goetz, K.; Kellogg, P. J.; Kersten, K.; Kasper, J. C.; Maruca, B. A.;

Real Gas Scale Effects on Hypersonic Laminar Boundary-Layer Parameters Including Effects of Entropy-Layer Swallowing

DTIC Science & Technology

1975-12-01

crossed the essentially normal portion of the bow shock is swallowed by the boundary layer. The flow along the edge of the boundary layer on the aft...portions hf the body will then have passed through an oblique part of the bow shock and will be in a different state than had it passed through a normal...determination of the local edge flow conditions may be improvedby taking into con- sideration the inclination of the bow shock where the local flow stream- line

System for determining position of normal shock in supersonic flow

NASA Technical Reports Server (NTRS)

Iverson, Jr., Donald G. (Inventor); Daiber, Troy D. (Inventor)

1991-01-01

Light from a plurality of light emitting diodes is transmitted through optical cables (12) to a lens system. The lenses (56, 58) expand and collimate the light and project it in a sheet (16) across the supersonic inlet of an aircraft power plant perpendicular to incoming airflow. A normal shock bends a portion of the sheet of light (16). A linear array of a multiplicity of optical fiber ends collects discrete samples of light. The samples are processed and compared to a predetermined profile to determine the shock location.

ENU mutagenesis screening for dominant behavioral mutations based on normal control data obtained in home-cage activity, open-field, and passive avoidance tests.

PubMed

Wada, Yumiko; Furuse, Tamio; Yamada, Ikuko; Masuya, Hiroshi; Kushida, Tomoko; Shibukawa, Yoko; Nakai, Yuji; Kobayashi, Kimio; Kaneda, Hideki; Gondo, Yoichi; Noda, Tetsuo; Shiroishi, Toshihiko; Wakana, Shigeharu

2010-01-01

To establish the cutoff values for screening ENU-induced behavioral mutations, normal variations in mouse behavioral data were examined in home-cage activity (HA), open-field (OF), and passive-avoidance (PA) tests. We defined the normal range as one that included more than 95% of the normal control values. The cutoffs were defined to identify outliers yielding values that deviated from the normal by less than 5% for C57BL/6J, DBA/2J, DBF(1), and N(2) (DXDB) progenies. Cutoff values for G1-phenodeviant (DBF(1)) identification were defined based on values over +/- 3.0 SD from the mean of DBF(1) for all parameters assessed in the HA and OF tests. For the PA test, the cutoff values were defined based on whether the mice met the learning criterion during the 2nd (at a shock intensity of 0.3 mA) or the 3rd (at a shock intensity of 0.15 mA) retention test. For several parameters, the lower outliers were undetectable as the calculated cutoffs were negative values. Based on the cutoff criteria, we identified 275 behavioral phenodeviants among 2,646 G1 progeny. Of these, 64 were crossed with wild-type DBA/2J individuals, and the phenotype transmission was examined in the G2 progeny using the cutoffs defined for N(2) mice. In the G2 mice, we identified 15 novel dominant mutants exhibiting behavioral abnormalities, including hyperactivity in the HA or OF tests, hypoactivity in the OF test, and PA deficits. Genetic and detailed behavioral analysis of these ENU-induced mutants will provide novel insights into the molecular mechanisms underlying behavior.

Investigation of charge weight and shock factor effect on non-linear transient structural response of rectangular plates subjected to underwater explosion (UNDEX) shock loading

NASA Astrophysics Data System (ADS)

Demir, Ozgur; Sahin, Abdurrahman; Yilmaz, Tamer

2012-09-01

Underwater explosion induced shock loads are capable of causing considerable structural damage. Investigations of the underwater explosion (UNDEX) effects on structures have seen continuous developments because of security risks. Most of the earlier experimental investigations were performed by military since the World War I. Subsequently; Cole [1] established mathematical relations for modeling underwater explosion shock loading, which were the outcome of many experimental investigations This study predicts and establishes the transient responses of a panel structure to underwater explosion shock loads using non-linear finite element code Ls-Dyna. Accordingly, in this study a new MATLAB code has been developed for predicting shock loading profile for different weight of explosive and different shock factors. Numerical analysis was performed for various test conditions and results are compared with Ramajeyathilagam's experimental study [8].

On the role of covarying functions in stimulus class formation and transfer of function.

PubMed Central

Markham, Rebecca G; Markham, Michael R

2002-01-01

This experiment investigated whether directly trained covarying functions are necessary for stimulus class formation and transfer of function in humans. Initial class training was designed to establish two respondent-based stimulus classes by pairing two visual stimuli with shock and two other visual stimuli with no shock. Next, two operant discrimination functions were trained to one stimulus of each putative class. The no-shock group received the same training and testing in all phases, except no stimuli were ever paired with shock. The data indicated that skin conductance response conditioning did not occur for the shock groups or for the no-shock group. Tests showed transfer of the established discriminative functions, however, only for the shock groups, indicating the formation of two stimulus classes only for those participants who received respondent class training. The results suggest that transfer of function does not depend on first covarying the stimulus class functions. PMID:12507017

Effect of shock pressure on the structure and superconducting properties of Y-Ba-Cu-O in explosively fabricated bulk metal-matrix composites

NASA Technical Reports Server (NTRS)

Murr, L. E.; Niou, C. S.; Pradhan-Advani, M.

1991-01-01

While it is now well established that copper-oxide-based power, or virtually any other ceramic superconductor powder, can be consolidated and encapsulated within a metal matrix by explosive consolidation, the erratic superconductivity following fabrication has posed a major problem for bulk applications. The nature of this behavior was found to arise from microstructural damage created in the shock wave front, and the residual degradation in superconductivity was demonstrated to be directly related to the peak shock pressure. The explosively fabricated or shock loaded YBa2Cu3Ox examples exhibit drastically altered rho (or R) - T curves. The deterioration in superconductivity is even more noticeable in the measurement of ac magnetic susceptibility and flux exclusion or shielding fraction which is also reduced in proportion to increasing peak shock pressure. The high frequency surface resistance (in the GHz range) is also correspondingly compromised in explosively fabricated, bulk metal-matrix composites based on YBa2Cu3O7. Transmission electron microscopy (including lattice imaging techniques) is being applied in an effort to elucidate the fundamental (microstructural) nature of the shock-induced degradation of superconductivity and normal state conductivity. One focus of TEM observations has assumed that oxygen displaced from b-chains rather than oxygen-vacancy disorder in the basal plane of oxygen deficient YBa2Cu3Ox may be a prime mechanism. Shock-wave displaced oxygen may also be locked into new positions or interstitial clusters or chemically bound to displaced metal (possibly copper) atoms to form precipitates, or such displacements may cause the equivalent of local lattice cell changes as a result of stoichiometric changes. While the shock-induced suppression of T(sub c) is not desirable in the explosive fabrication of bulk metal-matrix superconductors, it may be turned into an advantage if the atomic-scale distortion can be understood and controlled as local flux pinning sites.

Origin of energetic ions observed in the terrestrial ion foreshock : 2D full-particle simulations

NASA Astrophysics Data System (ADS)

Savoini, Philippe; Lembege, bertrand

2016-04-01

Collisionless shocks are well-known structures in astrophysical environments which dissipate bulk flow kinetic energy and accelerate large fraction of particle. Spacecrafts have firmly established the existence of the so-called terrestrial foreshock region magnetically connected to the shock and filled by two distinct populations in the quasi-perpendicular shock region (i.e. for 45r{ } ≤ quad θ Bn quad ≤ 90r{ }, where θ Bn is the angle between the shock normal and the upstream magnetic field) : (i) the field-aligned ion beams or `` FAB '' characterized by a gyrotropic distributionsout{,} and (ii) the gyro-phase bunched ions or `` GPB '' characterized by a NON gyrotropic distribution. The present work is based on the use of two dimensional PIC simulation of a curved shock and associated foreshock region where full curvature effects, time of flight effects and both electrons and ions dynamics are fully described by a self consistent approach. Our previous analysis (Savoini et Lembège, 2015) has evidenced that these two types of backstreaming populations can originate from the shock front itself without invoking any local diffusion by ion beam instabilities. Present results are focussed on individual ion trajectories and evidence that "FAB" population is injected into the foreshock mainly along the shock front whereas the "GPB" population penetrates more deeply the shock front. Such differences explain why the "FAB" population loses their gyro-phase coherency and become gyrotropic which is not the case for the "GPB". The impact of these different injection features on the energy gain for each ion population will be presented in détails. Savoini, P. and B. Lembège (2015), `` Production of nongyrotropic and gyrotropic backstreaming ion distributions in the quasi-perpendicular ion foreshock région '', J. Geophys. Res., 120, pp 7154-7171, doi = 10.1002/2015JA021018.

Effect of shock pressure on the structure and superconducting properties of Y-Ba-Cu-O in explosively fabricated bulk metal-matrix composites

NASA Technical Reports Server (NTRS)

Murr, L. E.; Niou, C. S.; Pradhan, M.; Schoenlein, L. H.

1990-01-01

While it is now well established that copper-oxide-based powder, or virtually any other ceramic superconductor powder, can be consolidated and encapsulated within a metal matrix by explosive consolidation, the erratic superconductivity following fabrication has posed a major problem for bulk applications. The nature of this behavior was found to arise from microstructural damage created in the shock wave front, and the residual degradation in superconductivity was demonstrated to be directly related to the peak shock pressure. The explosively fabricated or shock loaded YBa2Cu3Ox examples exhibit drastically altered rho (or R) - T curves. The deterioration in superconductivity is even more noticeable in the measurement of ac magnetic susceptibility and flux exclusion or shielding fraction which is also reduced in proportion to increasing peak shock pressure. The high-frequency surface resistance (in the GHz range) is also correspondingly compromised in explosively fabricated, bulk metal-matrix composites based on YBa2Cu3O7. Transmission electron microscopy (including lattice imaging techniques) is being applied in an effort to elucidate the fundamental (microstructural) nature of the shock-induced degradation of superconductivity and normal state conductivity. One focus of TEM observations has assumed that oxygen displaced from b-chains rather than oxygen-vacancy disorder in the basal plane of oxygen deficient YBa2Cu3Ox may be a prime mechanism. Shock-wave displaced oxygen may also be locked into new positions or interstitial clusters or chemically bound to displaced metal (possibly copper) atoms to form precipitates, or such displacements may cause the equivalent of local lattice cell changes as a result of stoichiometric changes. While the shock-induced suppression of T(sub c) is not desirable in the explosive fabrication of bulk metal-matrix superconductors, it may be turned into an advantage if the atomic-scale distortion can be understood and controlled as local flux pinning sites.

Shock-Wave Boundary Layer Interactions

DTIC Science & Technology

1986-02-01

Security Classification of Document UNCLASSIFIED 6. Title TURBULENT SHOCK-WAVE/BOUNDARY-LAYER INTERACTION 7. Presented at 8. Author(s)/Editor(s...contrary effects. The above demonstration puts an emphasis on inertia forces in the sense that the "fullness" for the Incoming boundary-layer profile is...expression "quasi-normal" means that in most transonic streams, the shocks are strong oblique shock, in the sense of the strong solution of the oblique shock

Tangential blowing for control of strong normal shock - Boundary layer interactions on inlet ramps

NASA Technical Reports Server (NTRS)

Schwendemann, M. F.; Sanders, B. W.

1982-01-01

The use of tangential blowing from a row of holes in an aft facing step is found to provide good control of the ramp boundary layer, normal shock interaction on a fixed geometry inlet over a wide range of inlet mass flow ratios. Ramp Mach numbers of 1.36 and 1.96 are investigated. The blowing geometry is found to have a significant effect on system performance at the highest Mach number. The use of high-temperature air in the blowing system, however, has only a slight effect on performance. The required blowing rates are significantly high for the most severe test conditions. In addition, the required blowing coefficient is found to be proportional to the normal shock pressure rise.

Effects of Shock and Turbulence Properties on Electron Acceleration

NASA Astrophysics Data System (ADS)

Qin, G.; Kong, F.-J.; Zhang, L.-H.

2018-06-01

Using test particle simulations, we study electron acceleration at collisionless shocks with a two-component model turbulent magnetic field with slab component including dissipation range. We investigate the importance of the shock-normal angle θ Bn, magnetic turbulence level {(b/{B}0)}2, and shock thickness on the acceleration efficiency of electrons. It is shown that at perpendicular shocks the electron acceleration efficiency is enhanced with the decrease of {(b/{B}0)}2, and at {(b/{B}0)}2=0.01 the acceleration becomes significant due to a strong drift electric field with long time particles staying near the shock front for shock drift acceleration (SDA). In addition, at parallel shocks the electron acceleration efficiency is increasing with the increase of {(b/{B}0)}2, and at {(b/{B}0)}2=10.0 the acceleration is very strong due to sufficient pitch-angle scattering for first-order Fermi acceleration, as well as due to the large local component of the magnetic field perpendicular to the shock-normal angle for SDA. On the other hand, the high perpendicular shock acceleration with {(b/{B}0)}2=0.01 is stronger than the high parallel shock acceleration with {(b/{B}0)}2=10.0, the reason might be the assumption that SDA is more efficient than first-order Fermi acceleration. Furthermore, for oblique shocks, the acceleration efficiency is small no matter whether the turbulence level is low or high. Moreover, for the effect of shock thickness on electron acceleration at perpendicular shocks, we show that there exists the bendover thickness, L diff,b. The acceleration efficiency does not noticeably change if the shock thickness is much smaller than L diff,b. However, if the shock thickness is much larger than L diff,b, the acceleration efficiency starts to drop abruptly.

Tables and charts of equilibrium normal shock and shock-tube solutions for helium-hydrogen mixtures with velocities to 70 km/sec

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1974-01-01

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves into helium-hydrogen mixtures representative of proposed outer planet atmospheres. The volumetric compositions of these mixtures are 0.35He-0.65H2, 0.20He-0.80H2, and 0.05He-0.95H2. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular-weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 4 to 70 km/sec for a range of initial pressure of 5 N/sq m to 100 kN/sq m. The present results are applicable to shock-tube flows and to free-flight conditions for a blunt body at high velocities. A working chart illustrating idealized shock-tube performance with a 0.20He-0.80H2 test gas and heated helium driver gas is also presented.

The interplanetary shock of September 24, 1998: Arrival at Earth

NASA Astrophysics Data System (ADS)

Russell, C. T.; Wang, Y. L.; Raeder, J.; Tokar, R. L.; Smith, C. W.; Ogilvie, K. W.; Lazarus, A. J.; Lepping, R. P.; Szabo, A.; Kawano, H.; Mukai, T.; Savin, S.; Yermolaev, Y. I.; Zhou, X.-Y.; Tsurutani, B. T.

2000-11-01

At close to 2345 UT on September 24, 1998, the magnetosphere was suddenly compressed by the passage of an interplanetary shock. In order to properly interpret the magnetospheric events triggered by the arrival of this shock, we calculate the orientation of the shock, its velocity, and its estimated time of arrival at the nose of the magnetosphere. Our best fit shock normal has an orientation of (-0.981 -0.157 -0.112) in solar ecliptic coordinates, a speed of 769 km/s, and an arrival time of 2344:19 at the magnetopause at 10 RE. Since measurements of the solar wind and interplanetary magnetic field are available from multiple spacecraft, we can compare several different techniques of shock-normal determination. Of the single spacecraft techniques the magnetic coplanarity solution is most accurate and the mixed mode solution is of lesser accuracy. Uncertainty in the timing and location of the IMP 8 spacecraft limits the accuracy of solutions using the time of arrival at the position of IMP 8.

14 CFR 27.475 - Tires and shock absorbers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 27.475 Section 27.475 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock...

WHEN SHOCK WAVES COLLIDE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartigan, P.; Liao, A. S.; Foster, J.

2016-06-01

Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. The experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

When shock waves collide

DOE PAGES

Martinez, D.; Hartigan, P.; Frank, A.; ...

2016-06-01

Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

Validation of MCDS by comparison of predicted with experimental velocity distribution functions in rarefied normal shocks

NASA Technical Reports Server (NTRS)

Pham-Van-diep, Gerald C.; Erwin, Daniel A.

1989-01-01

Velocity distribution functions in normal shock waves in argon and helium are calculated using Monte Carlo direct simulation. These are compared with experimental results for argon at M = 7.18 and for helium at M = 1.59 and 20. For both argon and helium, the variable-hard-sphere (VHS) model is used for the elastic scattering cross section, with the velocity dependence derived from a viscosity-temperature power-law relationship in the way normally used by Bird (1976).

Shock wave absorber having a deformable liner

DOEpatents

Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

1983-08-26

This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

Table and charts of equilibrium normal-shock properties for hydrogen-helium mixtures with velocities to 70 km/sec. Volume 1: 0.95 H2-0.05 He (by volume)

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1976-01-01

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves into hydrogen-helium mixtures representative of postulated outer planet atmospheres. These results are presented in four volumes and the volmetric compositions of the mixtures are 0.95H2-0.05He in Volume 1, 0.90H2-0.10He in Volume 2, 0.85H2-0.15He in Volume 3, and 0.75H2-0.25He in Volume 4. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular-weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 4 to 70 km/sec for a range of initial pressure of 5 N/sq m to 100 kN/sq m. Results are applicable to shock-tube flows and for determining flow conditions behind the normal portion of the bow shock about a blunt body at high velocities in postulated outer planet atmospheres. The document is a revised version of the original edition of NASA SP-3085 published in 1974.

Studies on shock interactions with moving cylinders using immersed boundary method

NASA Astrophysics Data System (ADS)

Luo, Kun; Luo, Yujuan; Jin, Tai; Fan, Jianren

2017-06-01

The process of shock interaction with a rigid cylinder is studied using a compressible immersed boundary method combined with a high-order weighted essentially nonoscillatory scheme. Movement of the cylinder is coupled to the flow field. First, the accuracy of the numerical scheme is validated. Then the influences of the incident shock Mach number and the cylinder diameter are discussed. The results are compared with those from cases with stationary cylinders. It is found that variation of either the incident shock Mach number or the cylinder diameter can cause different schlieren images. At a given dimensionless time, the trajectory of the upper triple point varies nonmonotonically with the incident shock Mach number while the primary reflected shock gets closer to the cylinder with increasing incident shock Mach number. For any moving case with a given incident shock Mach number and cylinder diameter, the trajectory of the upper triple point, the time evolution of the normalized vertical distance from the highest point of the primary reflected shock to the centerline of the cylinder, and the time evolution of the normalized shock detachment distance can all be predicted by linear correlation. As for the time evolution of the force exerted on the cylinder, the peak of the moving cylinder appears earlier than the stationary one in dimensionless time, with much lower value. Correlations to predict the occurrence of the peak drag and its value under different shock Mach numbers and cylinder diameters are proposed. The resulting cylinder movement is also briefly discussed.

HEAT SHOCK FACTOR 1-MEDIATED THERMOTOLERANCE PREVENTS CELL DEATH AND RESULTS IN G2/M CELL CYCLE ARREST

EPA Science Inventory

Mammalian cells respond to stress by activating heat shock transcription factors (e.g., HSF1) that regulate increased synthesis of heat shock proteins (HSPs). HSPs mediate protection from deleterious effects of stress by preventing permanent disruption of normal cellular mitosis...

14 CFR 27.475 - Tires and shock absorbers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section 27.475 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed...

Partial Spreading of a Laser Beam into a Light Sheet by Shock Waves and Its Use as a Shock Detection Technique

NASA Technical Reports Server (NTRS)

Panda, J.

1994-01-01

It is observed that when a laser beam is allowed to fall on a shock surface at a grazing incidence, a small part of the beam spreads out in a thin, diverging sheet of light normal to the surface, and both upstream and downstream of the shock. The phenomenon is visualized by observing a cross section of the light sheet on a screen placed normal to the laser path after it touches a shock. The light sheet disappears when the beam is moved to any other locations where there is no shock or the beam pierces the shock surface, i.e., at a non-grazing incidence. The spread angle of the light sheet is considerably higher than the angle by which the beam may bend as it passes through the shock, which produces a small difference of refractive index. Various details indicate that the spread light is a result of diffraction of a small part of the laser beam by the shock whose thickness is nearly the same as that of the laser wavelength. Shocks formed in underexpanded free jets of fully expanded Mach numbers 1.4 to 1.8 are used for this experiment. The above optical phenomenon is used as the basis of a novel shock detection technique which depends on sensing the spread light using a photomultiplier tube (PMT). The locations of the shock surfaces in the underexpanded supersonic jet, obtained using this technique, match with those inferred from the Schlieren photographs and velocity measurements. Moreover, if the shock oscillates, a periodic PMT signal is obtained which provides information about the frequency and amplitude of shock motion.

A Statistical Approach to Establishing Subsystem Environmental Test Specifications

NASA Technical Reports Server (NTRS)

Keegan, W. B.

1974-01-01

Results are presented of a research task to evaluate structural responses at various subsystem mounting locations during spacecraft level test exposures to the environments of mechanical shock, acoustic noise, and random vibration. This statistical evaluation is presented in the form of recommended subsystem test specifications for these three environments as normalized to a reference set of spacecraft test levels and are thus suitable for extrapolation to a set of different spacecraft test levels. The recommendations are dependent upon a subsystem's mounting location in a spacecraft, and information is presented on how to determine this mounting zone for a given subsystem.

Numerical Simulation Of Shock Response To Wall Changes In High Speed Intakes

NASA Astrophysics Data System (ADS)

Fincham, J.; Taylor, N. V.

2011-05-01

Hypersonic flight presents a number of challenges to the designer, one of which is the intake behaviour. Minimising drag requires careful positioning of the intake shock structure, while accurate understanding of the dynamic behaviour is required to allow minimisation of margins. In this paper, a two shock external compression intake derived from the Reaction Engines Limited SABRE engine is examined using inviscid axisymmetric CFD analysis to determine the response of the normal shockwave to axial motion of the intake centrebody. An approximately linear relationship between centrebody position and both the normal shock position and additive drag in steady flow is demonstrated. Initial results from an unsteady analysis are also given, which show complex behaviours may be triggered by rapid motion of the centrebody in response to control input.

Collisionless dissipation processes in quasi-parallel shocks. [in solar wind

NASA Technical Reports Server (NTRS)

Quest, K. B.; Forslund, D. W.; Brackbill, J. U.; Lee, K.

1983-01-01

The evolution of collisionless, quasi-parallel shocks (the angle between the shock normal and the upstream magnetic field being less than 45 deg) is examined using two dimensional particle simulations. Reflected ions upstream from the shock are observed with average guiding center velocity and gyrational energy which agree well with the prediction of simple specular reflection. Strong ion heating through the shock ramp is apparently caused by large amplitude whistler turbulence. A flux of suprathermal electrons is also the magnetic field direction. Much stronger ion heating occurs in the shock than electron heating. The relevance of this work to the earth's bow shock is discussed.

On magnetic field amplification and particle acceleration near non-relativistic collisionless shocks: Particles in MHD Cells simulations

NASA Astrophysics Data System (ADS)

Casse, F.; van Marle, A. J.; Marcowith, A.

2018-01-01

We present simulations of magnetized astrophysical shocks taking into account the interplay between the thermal plasma of the shock and supra-thermal particles. Such interaction is depicted by combining a grid-based magneto-hydrodynamics description of the thermal fluid with particle-in-cell techniques devoted to the dynamics of supra-thermal particles. This approach, which incorporates the use of adaptive mesh refinement features, is potentially a key to simulate astrophysical systems on spatial scales that are beyond the reach of pure particle-in-cell simulations. We consider non-relativistic super-Alfénic shocks with various magnetic field obliquity. We recover all the features from previous studies when the magnetic field is parallel to the normal to the shock. In contrast with previous particle-in-cell and hybrid simulations, we find that particle acceleration and magnetic field amplification also occur when the magnetic field is oblique to the normal to the shock but on larger timescales than in the parallel case. We show that in our oblique shock simulations the streaming of supra-thermal particles induces a corrugation of the shock front. Such oscillations of both the shock front and the magnetic field then locally helps the particles to enter the upstream region and to initiate a non-resonant streaming instability and finally to induce diffuse particle acceleration.

Seismicity parameters preceding moderate to major earthquakes

NASA Astrophysics Data System (ADS)

von Seggern, David; Alexander, Shelton S.; Baag, Chang-Eob

1981-10-01

Seismic events reported in the bulletins of the two large arrays, LASA and NORSAR, were merged with those from the NEIS bulletin for the period 1970-1977. Using a lower cutoff of mb = 5.8, 510 `main shocks' within the P range of LASA or NORSAR were selected for this period; and various seismicity trends prior to them were investigated. A search for definite foreshocks, based on a significantly short time delay to the main shock, revealed that the true rate of foreshock occurrence was less than 20%. Foreshocks are almost exclusively associated with shallow (h < 100 km) main shocks. To establish common features, a method of averaging seismicity from many regions was used to suppress the randomness of the seismic behavior of each region. This averaging shows that the seismicity level around the main shock increases somewhat for 10 days before main shocks; this feature peaks in the last 3-4 hours prior to the main shocks. The averaging also reveals that the mean magnitude of events near the main shock increases prior to main shocks but only by a few hundredths of a magnitude unit. Again by averaging, the seismicity about main shocks is shown to tend with time toward the main shock as its origin time is approached, but the average effect is small (˜10% change). By expanding or contracting each region's time scale before averaging to relate to the magnitude of the main shock, these features are enhanced. Using a new variable to track the departures from both spatial and temporal randomness, the Poisson-like behavior of deeper seismicity (>100 km) was demonstrated. For shallow events (<100 km) this variable reveals numerous instances of clustering and spatial-temporal seismic gaps, with little tendency toward a uniformity of behavior prior to main shocks. A statistical test of the validity of seismic precursors was performed for approximately 90 main shock regions which had sufficient seismicity. Using a five-variable vector (interevent time, interevent distance, magnitude, epicentral distance to main shock, and depth difference relative to main shock) for each event in a `precursory' time window of 500 days before the main shock and for each event in a `normal' time window of 500 days before that, the null hypothesis of equal vector means between the two groups was tested. At 90% confidence level, less than 30% of the main shock regions were thus found to exhibit precursory seismicity changes. Appendices are available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document J81-007; $1.00. Payment must accompany order.

Asymmetries in the location of the Venus and Mars bow shock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, T.L.; Schwingenschuh, K.; Russell, C.T.

1991-02-01

An examination of observations of the position of the terminator bow shock at Venus and Mars shows that the terminator bow shock varies with the angle between the local bow shock normal and the upstream magnetic field, {theta}{sub BN}. The part of the shock on the quasi-parallel side is closer to the planet than the part on the quasi-perpendicular side, a result which had been sggested by an earlier computer simulation by Thomas and Winske (1990). This bow shock asymmetry is observed to be larger at Mars than at Venus.

Facilitating nutrient aquisition of black walnut and other hardwoods at plantation establishment

Treesearch

Douglass F. Jacobs; John R. Seifert

2004-01-01

Bareroot hardwood seedlings typically undergo transplant shock immediately following planting before root systems are established. Fertilization at planting may act to minimize transplant shock by reducing nutrient stresses. However, previous work with fertilization of hardwoods at planting has generally relied on fertilizers with nutrient forms immediately available....

Roles of heat shock factors in gametogenesis and development.

PubMed

Abane, Ryma; Mezger, Valérie

2010-10-01

Heat shock factors form a family of transcription factors (four in mammals), which were named according to the first discovery of their activation by heat shock. As a result of the universality and robustness of their response to heat shock, the stress-dependent activation of heat shock factor became a ‘paradigm’: by binding to conserved DNA sequences (heat shock elements), heat shock factors trigger the expression of genes encoding heat shock proteins that function as molecular chaperones, contributing to establish a cytoprotective state to various proteotoxic stress and in several pathological conditions. Besides their roles in the stress response, heat shock factors perform crucial roles during gametogenesis and development in physiological conditions. First, during these process, in stress conditions, they are either proactive for survival or, conversely, for apoptotic process, allowing elimination or, inversely, protection of certain cell populations in a way that prevents the formation of damaged gametes and secure future reproductive success. Second, heat shock factors display subtle interplay in a tissue- and stage-specific manner, in regulating very specific sets of heat shock genes, but also many other genes encoding growth factors or involved in cytoskeletal dynamics. Third, they act not only by their classical transcription factor activities, but are necessary for the establishment of chromatin structure and, likely, genome stability. Finally, in contrast to the heat shock gene paradigm, heat shock elements bound by heat shock factors in developmental process turn out to be extremely dispersed in the genome, which is susceptible to lead to the future definition of ‘developmental heat shock element’.

Feedforward somatosensory inhibition is normal in cervical dystonia.

PubMed

Ferrè, Elisa R; Ganos, Christos; Bhatia, Kailash P; Haggard, Patrick

2015-03-01

Insufficient cortical inhibition is a key pathophysiological finding in dystonia. Subliminal sensory stimuli were reported to transiently inhibit somatosensory processing. Here we investigated whether such subliminal feedforward inhibition is reduced in patients with cervical dystonia. Sixteen cervical dystonia patients and 16 matched healthy controls performed a somatosensory detection task. We measured the drop in sensitivity to detect a threshold-level digital nerve shock when it was preceded by a subliminal conditioning shock, compared to when it was not. Subliminal conditioning shocks reduced sensitivity to threshold stimuli to a similar extent in both patients and controls, suggesting that somatosensory subliminal feedforward inhibition is normal in cervical dystonia. Somatosensory feedforward inhibition was normal in this group of cervical dystonia patients. Our results qualify previous concepts of a general dystonic deficit in sensorimotor inhibitory processing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Targeting Heat Shock Proteins in Cancer: A Promising Therapeutic Approach

PubMed Central

Burns, Timothy F.

2017-01-01

Heat shock proteins (HSPs) are a large family of chaperones that are involved in protein folding and maturation of a variety of “client” proteins protecting them from degradation, oxidative stress, hypoxia, and thermal stress. Hence, they are significant regulators of cellular proliferation, differentiation and strongly implicated in the molecular orchestration of cancer development and progression as many of their clients are well established oncoproteins in multiple tumor types. Interestingly, tumor cells are more HSP chaperonage-dependent than normal cells for proliferation and survival because the oncoproteins in cancer cells are often misfolded and require augmented chaperonage activity for correction. This led to the development of several inhibitors of HSP90 and other HSPs that have shown promise both preclinically and clinically in the treatment of cancer. In this article, we comprehensively review the roles of some of the important HSPs in cancer, and how targeting them could be efficacious, especially when traditional cancer therapies fail. PMID:28914774

Shocks in the solar wind between 1 and 8.5 AU: Voyager 1 observations

NASA Technical Reports Server (NTRS)

Gazis, P. R.

1984-01-01

A survey was made of all interplanetary shocks detected by the plasma science experiment aboard the Voyager 1 spacecraft between 1.2 and 8.5 AU. Shock normals and shock velocities are determined. The variation of shock frequency and various shock parameters with heliocentric distance is discussed. The results indicate that beyond 1.2 AU, the vast majority of shocks were associated with interaction regions between high and low speed streams; of 95 events, only 1 was clearly associated with a transient event. Forward shocks were more numerous and seemed to form closer to the sun than reverse shocks. Forward shocks were stronger than reverse shocks. The energy balance of three shocks is examined. A close agreement is found between the measured and the predicted pressure ratios across these shocks. The contribution of shocks to the global energy balance is discussed. Shocks are found to have a significant effect in heating the solar wind.

Inappropriate ICD discharges due to "triple counting" during normal sinus rhythm.

PubMed

Khan, Ejaz; Voudouris, Apostolos; Shorofsky, Stephen R; Peters, Robert W

2006-11-01

To describe the clinical course of a patient with multiple ICD shocks in the setting of advanced renal failure and hyperkalemia. The patient was brought to the Electrophysiology Laboratory where the ICD was interrogated. The patient was found to be hyperkalemic (serum potassium 7.6 mg/dl). Analysis of stored intracardiac electrograms from the ICD revealed "triple counting" (twice during his QRS complex and once during the T wave) and multiple inappropriate shocks. Correction of his electrolyte abnormality normalized his electrogram and no further ICD activations were observed. Electrolyte abnormalities can distort the intracardiac electrogram in patients with ICD's and these changes can lead to multiple inappropriate shocks.

Investigation of Inlet Control Parameters for an External-internal-compression Inlet from Mach 2.1 to 3.0

NASA Technical Reports Server (NTRS)

Anderson, B. H.; Bowditch, D. N.

1958-01-01

Investigation of the control parameters of an external-internal compression inlet indicates that the cowl-lip shock provides a signal to position the spike and to start the inlet over a Mach number range from 2.1 to 3.0. Use of a single fixed probe position to control the spike over the range of conditions resulted in a 3.7-count loss in total-pressure recovery at Mach 3.0 and 0 deg angle of attack. Three separate shock-sensing-probe positions were required to set the spike for peak recovery from Mach 2.1 to 3.0 and angles of attack from 0 deg to 6 deg. When the inlet was unstarted, an erroneous signal was obtained from the normal-shock control through most of the starting cycle that prevented the inlet from starting. Therefore, it was necessary to over-ride the normal-shock control signal and not allow the control to position the terminal shock until the spike was positioned.

Steady normal shock wave solution tables of parahydrogen for total temperatures from 30 K to 290 K and for total pressure from 1 ATM to 10 ATM

NASA Technical Reports Server (NTRS)

Haut, R. C.; Adcock, J. B.

1976-01-01

The steady normal shock wave solutions of parahydrogen at various total pressures and total temperatures were numerically determined by iterating the upstream Mach number and by using a modified interval halving technique. The results obtained are compared with the ideal diatomic gas values and are presented in tabulated form.

Table and Charts of Equilibrium Normal-shock Properties for Pure Hydrogen with Velocities to 70 km/sec. Revised.

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1976-01-01

Errors found in the original edition are corrected. Refinement was made in procedures for solving the conservation relations for an incident (moving), standing, and reflected normal shock, as well as in computational methods for determining thermochemical-equilibrium hydrogen properties. A six-species hydrogen model replaces the original four-species model, and the heat of formation and spectroscopic constants used in this six-species model are listed in appendix A. In appendix B, comparisons are made between a number of methods for determining equilibrium thermodynamic properties for hydrogen for several values of pressure and temperatures to 50000 K. A comparison is also performed between the present method and a second method for determining thermodynamic properties and flow velocity behind an incident shock into pure hydrogen and behind a reflected shock.

Numerical Simulation of Shock Interaction with Deformable Particles Using a Constrained Interface Reinitialization Scheme

NASA Astrophysics Data System (ADS)

Jackson, Thomas L.; Sridharan, Prashanth; Zhang, Ju; Balachandar, S.

2015-11-01

In this work we present axisymmetric numerical simulations of shock propagating in nitromethane over an aluminum particle for post-shock pressures up to 10 GPa. The numerical method is a finite-volume based solver on a Cartesian grid, which allows for multi-material interfaces and shocks. To preserve particle mass and volume, a novel constraint reinitialization scheme is introduced. We compute the unsteady drag coefficient as a function of post-shock pressure, and show that when normalized by post-shock conditions, the maximum drag coefficient decreases with increasing post-shock pressure. Using this information, we also present a simplified point-particle force model that can be used for mesoscale simulations.

Transmission of singularities through a shock wave and the sound generation

NASA Technical Reports Server (NTRS)

Ting, L.

1974-01-01

The interaction of a plane shock wave of finite strength with a vortex line, point vortex, doublet or quadrupole of weak strength is studied. Based upon the physical condition that a free vortex line cannot support a pressure difference, rules are established which define the change of the linear intensity of the segment of the vortex line after its passage through the shock. The rules for point vortex, doublet, and quadrupole are then established as limiting cases. These rules can be useful for the construction of the solution of the entire flow field and for its physical interpretation. However, the solution can be obtained directly by the technique developed for shock diffraction problems. Explicit solutions and the associated sound generation are obtained for the passage of a point vortex through the shock wave.

Nature of the wiggle instability of galactic spiral shocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Woong-Tae; Kim, Yonghwi; Kim, Jeong-Gyu, E-mail: wkim@astro.snu.ac.kr, E-mail: kimyh@astro.snu.ac.kr, E-mail: jgkim@astro.snu.ac.kr

Gas in disk galaxies interacts nonlinearly with an underlying stellar spiral potential to form galactic spiral shocks. While numerical simulations typically show that spiral shocks are unstable to wiggle instability (WI) even in the absence of magnetic fields and self-gravity, its physical nature has remained uncertain. To clarify the mechanism behind the WI, we conduct a normal-mode linear stability analysis and nonlinear simulations assuming that the disk is isothermal and infinitesimally thin. We find that the WI is physical, originating from the generation of potential vorticity at a deformed shock front, rather than Kelvin-Helmholtz instabilities as previously thought. Since gasmore » in galaxy rotation periodically passes through the shocks multiple times, the potential vorticity can accumulate successively, setting up a normal mode that grows exponentially with time. Eigenfunctions of the WI decay exponentially downstream from the shock front. Both shock compression of acoustic waves and a discontinuity of shear across the shock stabilize the WI. The wavelength and growth time of the WI depend on the arm strength quite sensitively. When the stellar-arm forcing is moderate at 5%, the wavelength of the most unstable mode is about 0.07 times the arm-to-arm spacing, with the growth rate comparable to the orbital angular frequency, which is found to be in good agreement with the results of numerical simulations.« less

On magnetic field amplification and particle acceleration near non-relativistic astrophysical shocks: particles in MHD cells simulations

NASA Astrophysics Data System (ADS)

van Marle, Allard Jan; Casse, Fabien; Marcowith, Alexandre

2018-01-01

We present simulations of magnetized astrophysical shocks taking into account the interplay between the thermal plasma of the shock and suprathermal particles. Such interaction is depicted by combining a grid-based magnetohydrodynamics description of the thermal fluid with particle in cell techniques devoted to the dynamics of suprathermal particles. This approach, which incorporates the use of adaptive mesh refinement features, is potentially a key to simulate astrophysical systems on spatial scales that are beyond the reach of pure particle-in-cell simulations. We consider in this study non-relativistic shocks with various Alfvénic Mach numbers and magnetic field obliquity. We recover all the features of both magnetic field amplification and particle acceleration from previous studies when the magnetic field is parallel to the normal to the shock. In contrast with previous particle-in-cell-hybrid simulations, we find that particle acceleration and magnetic field amplification also occur when the magnetic field is oblique to the normal to the shock but on larger time-scales than in the parallel case. We show that in our simulations, the suprathermal particles are experiencing acceleration thanks to a pre-heating process of the particle similar to a shock drift acceleration leading to the corrugation of the shock front. Such oscillations of the shock front and the magnetic field locally help the particles to enter the upstream region and to initiate a non-resonant streaming instability and finally to induce diffuse particle acceleration.

Prediction of Shock Arrival Times from CME and Flare Data

NASA Technical Reports Server (NTRS)

Nunez, Marlon; Nieves-Chinchilla, Teresa; Pulkkinen, Antti

2016-01-01

This paper presents the Shock ARrival Model (SARM) for predicting shock arrival times for distances from 0.72 AU to 8.7 AU by using coronal mass ejections (CME) and flare data. SARM is an aerodynamic drag model described by a differential equation that has been calibrated with a dataset of 120 shocks observed from 1997 to 2010 by minimizing the mean absolute error (MAE), normalized to 1 AU. SARM should be used with CME data (radial, earthward or plane-of-sky speeds), and flare data (peak flux, duration, and location). In the case of 1 AU, the MAE and the median of absolute errors were 7.0 h and 5.0 h respectively, using the available CMEflare data. The best results for 1 AU (an MAE of 5.8 h) were obtained using both CME data, either radial or cone-model-estimated speeds, and flare data. For the prediction of shock arrivals at distances from 0.72 AU to 8.7 AU, the normalized MAE and the median were 7.1 h and 5.1 h respectively, using the available CMEflare data. SARM was also calibrated to be used with CME data alone or flare data alone, obtaining normalized MAE errors of 8.9 h and 8.6 h respectively for all shock events. The model verification was carried out with an additional dataset of 20 shocks observed from 2010 to 2012 with radial CME speeds to compare SARM with the empirical ESA model [Gopalswamy et al., 2005a] and the numerical MHD-based ENLIL model [Odstrcil et al., 2004]. The results show that the ENLIL's MAE was lower than the SARM's MAE, which was lower than the ESA's MAE. The SARM's best results were obtained when both flare and true CME speeds were used.

Consolidation of Bimetallic Nanosized Particles and Formation of Nanocomposites Depending on Conditions of Shock Wave Compaction

NASA Astrophysics Data System (ADS)

Vorozhtsov, S. A.; Kudryashova, O. B.; Lerner, M. I.; Vorozhtsov, A. B.; Khrustalyov, A. P.; Pervikov, A. V.

2017-11-01

The authors consider and evaluate the physical parameters and regularities of the process of consolidation of Fe-Cu, Cu-Nb, Ag-Ni, Fe-Pb nanoparticles when creating composite materials by means of shock wave compaction. As a result of theoretical consideration of explosive compaction process, researchers established and discussed the physical process conditions, established a number of threshold pressure values corresponding to different target indicators of the state of the compact. The time of shock wave impact on powders for powder consolidation was estimated.

Predictive Analytical Model for Isolator Shock-Train Location in a Mach 2.2 Direct-Connect Supersonic Combustion Tunnel

NASA Astrophysics Data System (ADS)

Lingren, Joe; Vanstone, Leon; Hashemi, Kelley; Gogineni, Sivaram; Donbar, Jeffrey; Akella, Maruthi; Clemens, Noel

2016-11-01

This study develops an analytical model for predicting the leading shock of a shock-train in the constant area isolator section in a Mach 2.2 direct-connect scramjet simulation tunnel. The effective geometry of the isolator is assumed to be a weakly converging duct owing to boundary-layer growth. For some given pressure rise across the isolator, quasi-1D equations relating to isentropic or normal shock flows can be used to predict the normal shock location in the isolator. The surface pressure distribution through the isolator was measured during experiments and both the actual and predicted locations can be calculated. Three methods of finding the shock-train location are examined, one based on the measured pressure rise, one using a non-physics-based control model, and one using the physics-based analytical model. It is shown that the analytical model performs better than the non-physics-based model in all cases. The analytic model is less accurate than the pressure threshold method but requires significantly less information to compute. In contrast to other methods for predicting shock-train location, this method is relatively accurate and requires as little as a single pressure measurement. This makes this method potentially useful for unstart control applications.

Shock wave absorber having apertured plate

DOEpatents

Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

1983-08-26

The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

Transportation Shock and Vibration Literature Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maheras, Steven J.; Lahti, Erik A.; Ross, Steven B.

2013-06-06

This report fulfills the M4 milestone M4FT-13OR08220112, "Report Documenting Experimental Activities." The purpose of this report is to document the results of a literature review conducted of studies related to the vibration and shock associated with the normal conditions of transport for rail shipments of used nuclear fuel from commercial light-water reactors. As discussed in Adkins (2013), the objective of this report is to determine if adequate data exist that would enable the impacts of the shock and vibration associated with the normal conditions of transport on commercial light-water reactor used nuclear fuel shipped in current generation rail transportation casksmore » to be realistically modeled.« less

Shock wave absorber having apertured plate

DOEpatents

Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

1985-01-01

The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

Emergence of power-law scalings in shock-driven mixing transition

NASA Astrophysics Data System (ADS)

Vorobieff, Peter; Wayne, Patrick; Olmstead, Dell; Simons, Dylan; Truman, C. Randall; Kumar, Sanjay

2016-11-01

We present an experimental study of transition to turbulence due to shock-driven instability evolving on an initially cylindrical, diffuse density interface between air and a mixture of sulfur hexafluoride (SF6) and acetone. The plane of the shock is at an initial angle θ with the axis of the heavy-gas cylinder. We present the cases of planar normal (θ = 0) and oblique (θ =20°) shock interaction with the initial conditions. Flow is visualized in two perpendicular planes with planar laser-induced fluorescence (PLIF) triggered in acetone with a pulsed ultraviolet laser. Statistics of the flow are characterized in terms of the second-order structure function of the PLIF intensity. As instabilities in the flow evolve, the structure functions begin to develop power-law scalings, at late times manifesting over a range of scales spanning more than two orders of magnitude. We discuss the effects of the initial conditions on the emergence of these scalings, comparing the fully three-dimensional case (oblique shock interaction) with the quasi-two-dimensional case (planar normal shock interaction). We also discuss the flow anisotropy apparent in statistical differences in data from the two visualization planes. This work is funded by NNSA Grant DE-NA0002913.

Experimental Investigation of Normal Shock Boundary-Layer Interaction with Hybrid Flow Control

NASA Technical Reports Server (NTRS)

Vyas, Manan A.; Hirt, Stefanie M.; Anderson, Bernhard H.

2012-01-01

Hybrid flow control, a combination of micro-ramps and micro-jets, was experimentally investigated in the 15x15 cm Supersonic Wind Tunnel (SWT) at the NASA Glenn Research Center. Full factorial, a design of experiments (DOE) method, was used to develop a test matrix with variables such as inter-ramp spacing, ramp height and chord length, and micro-jet injection flow ratio. A total of 17 configurations were tested with various parameters to meet the DOE criteria. In addition to boundary-layer measurements, oil flow visualization was used to qualitatively understand shock induced flow separation characteristics. The flow visualization showed the normal shock location, size of the separation, path of the downstream moving counter-rotating vortices, and corner flow effects. The results show that hybrid flow control demonstrates promise in reducing the size of shock boundary-layer interactions and resulting flow separation by means of energizing the boundary layer.

Comparative analysis of angiogenic gene expression in normal and impaired wound healing in diabetic mice: effects of extracorporeal shock wave therapy.

PubMed

Zins, Stephen R; Amare, Mihret F; Tadaki, Douglas K; Elster, Eric A; Davis, Thomas A

2010-12-01

Impaired wound healing is a persistent clinical problem which has been treated with mixed results. Studies aimed at elucidating the mechanism of impaired wound healing have focused on small cohorts of genes which leave an incomplete picture of the wound healing process. We aimed to investigate impaired wound healing via a comprehensive panel of angiogenic/inflammation-related genes and wound closure kinetics with and without the application of extracorporeal shock wave therapy (ESWT), which has been demonstrated to improve wound healing. Full-thickness skin from the dorsal surface of "normal" (BALB/c) and "impaired" (db (+)/db (+)) mice was excised, and wound margin tissue was harvested 2, 7, and 10 days post injury. A separate, but identical wound model was established over 40 days in order to measure wound closure kinetics. Over time, the normal non-ESWT treated wounds exhibited varying patterns of elevated expression of 25-30 genes, whereas wounds with impaired healing displayed prolonged elevated expression of only a few genes (CXCL2, CXCL5, CSF3, MMP9, TGF-α). In response to ESWT, gene expression was augmented in both types of wounds, especially in the expression of PECAM-1; however, ESWT had no effect on wound closure in either model. In addition, multiple doses of ESWT exacerbated the delayed wound healing, and actually caused the wounds to initially increase in size. These data provide a more complete picture of impaired wound healing, and a way to evaluate various promising treatments.

The resolved layer of a collisionless, high beta, supercritical, quasi-perpendicular shock wave. II - Dissipative fluid electrodynamics

NASA Technical Reports Server (NTRS)

Scudder, J. D.; Aggson, T. L.; Mangeney, A.; Lacombe, C.; Harvey, C. C.

1986-01-01

Using the results of Scudder et al. (1986) on the bow shock wave observed by ISEE satellites, a quantitative description is presented of the electrodynamics of ion and electron fluids, and phase-standing wave interaction which manifests itself as a supercritical MHD shock. The cross-shock electrical profile was determined in both the normal incidence frame and in the deHoffman-Teller frame by two different methods, and the results were compared with dc electric field measurements.

Evaluation of Euler fluxes by a high-order CFD scheme: shock instability

NASA Astrophysics Data System (ADS)

Tu, Guohua; Zhao, Xiaohui; Mao, Meiliang; Chen, Jianqiang; Deng, Xiaogang; Liu, Huayong

2014-05-01

The construction of Euler fluxes is an important step in shock-capturing/upwind schemes. It is well known that unsuitable fluxes are responsible for many shock anomalies, such as the carbuncle phenomenon. Three kinds of flux vector splittings (FVSs) as well as three kinds of flux difference splittings (FDSs) are evaluated for the shock instability by a fifth-order weighted compact nonlinear scheme. The three FVSs are Steger-Warming splitting, van Leer splitting and kinetic flux vector splitting (KFVS). The three FDSs are Roe's splitting, advection upstream splitting method (AUSM) type splitting and Harten-Lax-van Leer (HLL) type splitting. Numerical results indicate that FVSs and high dissipative FDSs undergo a relative lower risk on the shock instability than that of low dissipative FDSs. However, none of the fluxes evaluated in the present study can entirely avoid the shock instability. Generally, the shock instability may be caused by any of the following factors: low dissipation, high Mach number, unsuitable grid distribution, large grid aspect ratio, and the relative shock-internal flow state (or position) between upstream and downstream shock waves. It comes out that the most important factor is the relative shock-internal state. If the shock-internal state is closer to the downstream state, the computation is at higher susceptibility to the shock instability. Wall-normal grid distribution has a greater influence on the shock instability than wall-azimuthal grid distribution because wall-normal grids directly impact on the shock-internal position. High shock intensity poses a high risk on the shock instability, but its influence is not as much as the shock-internal state. Large grid aspect ratio is also a source of the shock instability. Some results of a second-order scheme and a first-order scheme are also given. The comparison between the high-order scheme and the two low-order schemes indicates that high-order schemes are at a higher risk of the shock instability. Adding an entropy fix is very helpful in suppressing the shock instability for the two low-order schemes. When the high-order scheme is used, the entropy fix still works well for Roe's flux, but its effect on the Steger-Warming flux is trivial and not much clear.

Unusually Deep Bonin Earthquake (M7.9) of May 30, 2015 Suggests that Stagnant Slab Transforms into Penetration Stage

NASA Astrophysics Data System (ADS)

Obayashi, M.; Fukao, Y.; Yoshimitsu, J.

2015-12-01

A great shock occurred at an unusual depth of 678 km far away from the well-defined Wadati-Benioff zone of the Izu-Bonin arc (Fig.1). To the north of this region the slab is stagnant above the 660 km discontinuity and to the south it penetrates the discontinuity (Fig.2). Thus, the slab in this region can be viewed as in a transitional state from the stagnant to penetrating slab. Here, the steeply dipping part of the slab bends sharply to horizontal and the great shock happened at the lowest corner of this bending. The CMT indicates a pure normal faulting with the trench-normal near horizontal tensional axis and the near vertical compressional axis (Fig.1). We suggest that this mechanism reflects a transitional state of slab deformation from the bending-dominant mode to the penetration-dominant mode. The mechanism is consistent with either of these two two modes. We show that the mechanism is also consistent with the resultant stress field generated by many deep shocks occurring along the Wadati-Benioff zone. The calculated stress field changes rapidly along a trench-normal profile at a depth of 680 km and becomes similar to that generated by the great shock at points near the hypocenter (Fig.3). Thus, the stress field due to the Wadati-Benioff zone earthquakes works to enhance the occurrence of deep shocks of the type of the 2015 great shock, which represents slab deformation associated with the transition from stagnant to penetrating slab.

Analytical scalings of the linear Richtmyer-Meshkov instability when a shock is reflected.

PubMed

Campos, F Cobos; Wouchuk, J G

2016-05-01

When a planar shock hits a corrugated contact surface between two fluids, hydrodynamic perturbations are generated in both fluids that result in asymptotic normal and tangential velocity perturbations in the linear stage, the so called Richtmyer-Meshkov instability. In this work, explicit and exact analytical expansions of the asymptotic normal velocity (δv_{i}^{∞}) are presented for the general case in which a shock is reflected back. The expansions are derived from the conservation equations and take into account the whole perturbation history between the transmitted and reflected fronts. The important physical limits of weak and strong shocks and the high/low preshock density ratio at the contact surface are shown. An approximate expression for the normal velocity, valid even for high compression regimes, is given. A comparison with recent experimental data is done. The contact surface ripple growth is studied during the linear phase showing good agreement between theory and experiments done in a wide range of incident shock Mach numbers and preshock density ratios, for the cases in which the initial ripple amplitude is small enough. In particular, it is shown that in the linear asymptotic phase, the contact surface ripple (ψ_{i}) grows as ψ_{∞}+δv_{i}^{∞}t, where ψ_{∞} is an asymptotic ordinate different from the postshock ripple amplitude at t=0+. This work is a continuation of the calculations of F. Cobos Campos and J. G. Wouchuk, [Phys. Rev. E 90, 053007 (2014)PLEEE81539-375510.1103/PhysRevE.90.053007] for a single shock moving into one fluid.

Modeling of ion acceleration through drift and diffusion at interplanetary shocks

NASA Technical Reports Server (NTRS)

Decker, R. B.; Vlahos, L.

1986-01-01

A test particle simulation designed to model ion acceleration through drift and diffusion at interplanetary shocks is described. The technique consists of integrating along exact particle orbits in a system where the angle between the shock normal and mean upstream magnetic field, the level of magnetic fluctuations, and the energy of injected particles can assume a range of values. The technique makes it possible to study time-dependent shock acceleration under conditions not amenable to analytical techniques. To illustrate the capability of the numerical model, proton acceleration was considered under conditions appropriate for interplanetary shocks at 1 AU, including large-amplitude transverse magnetic fluctuations derived from power spectra of both ambient and shock-associated MHD waves.

Shock drift acceleration in the presence of waves

NASA Technical Reports Server (NTRS)

Decker, R. B.; Vlahos, L.

1985-01-01

Attention is given to the initial results of a model designed to study the modification of the scatter-free, shock drift acceleration of energetic test particles by wave activity in the vicinity of a quasi-perpendicular, fast-mode MHD shock. It is emphasized that the concept of magnetic moment conservation is a valid approximation only in the perpendicular and nearly perpendicular regimes, when the angle theta-Bn between the shock normal and the upstream magnetic field vector is in the range from 70 deg to 90 deg. The present investigation is concerned with one step in a program which is being developed to combine the shock drift and diffusive processes at a shock of arbitrary theta-Bn.

Shock loading predictions from application of indicial theory to shock-turbulence interactions

NASA Technical Reports Server (NTRS)

Keefe, Laurence R.; Nixon, David

1991-01-01

A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating shock wave from knowledge of the oncoming turbulent boundary layer is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the shock wave, which are then used to obtain the shock frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal shock is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the shock position and velocity spectra, along with the shock passage frequency distribution. The low frequency portion of the shock spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.

Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

DOE PAGES

Ali, S. J.; Bolme, C. A.; Collins, G. W.; ...

2015-04-16

Here, a normal-incidence visible and near-infrared shock wave optical reflectivity diagnostic was constructed to investigate changes in the optical properties of materials under dynamic laser compression. Documenting wavelength- and time-dependent changes in the optical properties of laser-shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved, but we succeeded in doing so by broadening a series of time delayed 800-nm pulses from an ultrafast Ti:sapphire laser to generate high-intensity broadband light at nanosecond time scales. This diagnostic was demonstrated over the wavelength range 450–1150 nm with up to 16 time displaced spectramore » during a single shock experiment. Simultaneous off-normal incidence velocity interferometry (velocity interferometer system for any reflector) characterized the sample under laser-compression and also provided an independent reflectivity measurement at 532 nm wavelength. The shock-driven semiconductor-to-metallic transition in germanium was documented by the way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm.« less

The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giacalone, J.

We investigate the physics of charged-particle acceleration at spherical shocks moving into a uniform plasma containing a turbulent magnetic field with a uniform mean. This has applications to particle acceleration at astrophysical shocks, most notably, to supernovae blast waves. We numerically integrate the equations of motion of a large number of test protons moving under the influence of electric and magnetic fields determined from a kinematically defined plasma flow associated with a radially propagating blast wave. Distribution functions are determined from the positions and velocities of the protons. The unshocked plasma contains a magnetic field with a uniform mean andmore » an irregular component having a Kolmogorov-like power spectrum. The field inside the blast wave is determined from Maxwell’s equations. The angle between the average magnetic field and unit normal to the shock varies with position along its surface. It is quasi-perpendicular to the unit normal near the sphere’s equator, and quasi-parallel to it near the poles. We find that the highest intensities of particles, accelerated by the shock, are at the poles of the blast wave. The particles “collect” at the poles as they approximately adhere to magnetic field lines that move poleward from their initial encounter with the shock at the equator, as the shock expands. The field lines at the poles have been connected to the shock the longest. We also find that the highest-energy protons are initially accelerated near the equator or near the quasi-perpendicular portion of the shock, where the acceleration is more rapid.« less

Normal velocity freeze-out of the Richtmyer-Meshkov instability when a rarefaction is reflected

NASA Astrophysics Data System (ADS)

Wouchuk, J. G.; Sano, T.

2015-02-01

The Richtmyer-Meshkov instability (RMI) develops when a shock front hits a rippled contact surface separating two different fluids. After the incident shock refraction, a transmitted shock is always formed and another shock or a rarefaction is reflected back. The pressure-entropy-vorticity fields generated by the rippled wave fronts are responsible for the generation of hydrodynamic perturbations in both fluids. In linear theory, the contact surface ripple reaches an asymptotic normal velocity which is dependent on the incident shock Mach number, fluids density ratio, and compressibilities. It was speculated in the past about the possibility of getting a zero value for the asymptotic normal velocity, a phenomenon that was called "freeze-out" [G. Fraley, Phys. Fluids 29, 376 (1986), 10.1063/1.865722; K. Mikaelian, Phys. Fluids 6, 356 (1994), 10.1063/1.868091, A. L. Velikovich et al., Phys. Plasmas 8, 592 (2001), 10.1063/1.1335829]. In a previous paper, freeze-out was studied for the case when a shock is reflected at the contact surface [J. G. Wouchuk and K. Nishihara, Phys. Rev. E 70, 026305 (2004), 10.1103/PhysRevE.70.026305]. In this work the freeze-out of the RMI is studied for the case in which a rarefaction is reflected back. Two different regimes are found: nearly equal preshock densities at the interface at any shock intensity, and very large density difference for strong shocks. The contour curves that relate shock Mach number and preshock density ratio are obtained in both regimes for fluids with equal and different compressibilities. An analysis of the temporal evolution of different cases of freeze-out is shown. It is seen that the freeze-out is the result of the interaction between the unstable interface and the rippled wave fronts. As a general and qualitative criterion to look for freeze-out situations, it is seen that a necessary condition for freeze-out is the same orientation for the tangential velocities generated at each side of the contact surface at t =0 + . A comparison with the results of previous works is also shown.

Inhibition of intraluminal pancreatic enzymes with nafamostat mesilate improves clinical outcomes after hemorrhagic shock in swine.

PubMed

Kim, Hubert D; Malinoski, Darren J; Borazjani, Boris; Patel, Madhukar S; Chen, Joseph; Slone, Johnathan; Nguyen, Xuan-Mai T; Steward, Earl; Schmid-Schonbein, Geert W; Hoyt, David B

2010-05-01

Recent studies suggest that intraluminal pancreatic enzymes play a major role in the initiation of the inflammatory cascade by the gut after hemorrhagic shock. Previous animal models have shown that the inhibition of enteral pancreatic enzymes with a serine protease inhibitor, nafamostat mesilate (NM), decreases leukocyte activation and transfusion requirements after hemorrhagic shock. The objective of this study was to determine whether enteroclysis with NM would improve the clinical outcomes in swine after hemorrhagic shock and intestinal hypoperfusion. Thirty-three male Yucatan minipigs weighing 25 kg to 30 kg underwent a controlled hemorrhage of 25 mL/kg with mesenteric clamp for further gut ischemia. Animals were allocated to three groups: (1) shock only (n = 15), (2) shock + enteroclysis with 100 mL/kg GoLYTELY (GL) as a carrier (n = 11), and (3) shock + enteroclysis with GL + 0.37 mmol/L NM (GL+NM, n = 7). Animals were resuscitated, recovered from anesthesia, observed for 3 days, and graded on a daily 4-point clinical scoring system. A score of 0 indicated a moribund state or early death, and a score of 4 indicated normal behavior. Pigs treated with GL + NM had significantly higher mean postoperative recovery scores (3.8 +/- 0.4, essentially normal behavior with no early deaths) compared with animals within the shock only and shock + GL groups (2.1 +/- 1 with one early death and 2.2 +/- 1.2 with two early deaths, respectively, analysis of variance p < 0.003). The inhibition of intraluminal pancreatic enzymes using enteroclysis with the serine protease inhibitor, NM, after hemorrhagic shock significantly improves the clinical outcome.

The properties and causes of rippling in quasi-perpendicular collisionless shock fronts

NASA Astrophysics Data System (ADS)

Lowe, R. E.; Burgess, D.

2003-03-01

The overall structure of quasi-perpendicular, high Mach number collisionless shocks is controlled to a large extent by ion reflection at the shock ramp. Departure from a strictly one-dimensional structure is indicated by simulation results showing that the surface of such shocks is rippled, with variations in the density and all field components. We present a detailed analysis of these shock ripples, using results from a two-dimensional hybrid (particle ions, electron fluid) simulation. The process that generates the ripples is poorly understood, because the large gradients at the shock ramp make it difficult to identify instabilities. Our analysis reveals new features of the shock ripples, which suggest the presence of a surface wave mode dominating the shock normal magnetic field component of the ripples, as well as whistler waves excited by reflected ions.

A CORONAL HOLE'S EFFECTS ON CORONAL MASS EJECTION SHOCK MORPHOLOGY IN THE INNER HELIOSPHERE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, B. E.; Wu, C.-C.; Howard, R. A.

2012-08-10

We use STEREO imagery to study the morphology of a shock driven by a fast coronal mass ejection (CME) launched from the Sun on 2011 March 7. The source region of the CME is located just to the east of a coronal hole. The CME ejecta is deflected away from the hole, in contrast with the shock, which readily expands into the fast outflow from the coronal hole. The result is a CME with ejecta not well centered within the shock surrounding it. The shock shape inferred from the imaging is compared with in situ data at 1 AU, wheremore » the shock is observed near Earth by the Wind spacecraft, and at STEREO-A. Shock normals computed from the in situ data are consistent with the shock morphology inferred from imaging.« less

Whistler Waves Associated with Weak Interplanetary Shocks

NASA Technical Reports Server (NTRS)

Velez, J. C. Ramirez; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Kajdic, P.; Jian,, L. K.; Luhmann, J. G.

2012-01-01

We analyze the properties of 98 weak interplanetary shocks measured by the dual STEREO spacecraft over approximately 3 years during the past solar minimum. We study the occurrence of whistler waves associated with these shocks, which on average are high beta shocks (0.2 < Beta < 10). We have compared the waves properties upstream and downstream of the shocks. In the upstream region the waves are mainly circularly polarized, and in most of the cases (approx. 75%) they propagate almost parallel to the ambient magnetic field (<30 deg.). In contrast, the propagation angle with respect to the shock normal varies in a broad range of values (20 deg. to 90 deg.), suggesting that they are not phase standing. We find that the whistler waves can extend up to 100,000 km in the upstream region but in most cases (88%) are contained in a distance within 30,000 km from the shock. This corresponds to a larger region with upstream whistlers associated with IP shocks than previously reported in the literature. The maximum amplitudes of the waves are observed next to the shock interface, and they decrease as the distance to the shock increases. In most cases the wave propagation direction becomes more aligned with the magnetic field as the distance to the shock increases. These two facts suggest that most of the waves in the upstream region are Landau damping as they move away from the shock. From the analysis we also conclude that it is likely that the generation mechanism of the upstream whistler waves is taking place at the shock interface. In the downstream region, the waves are irregularly polarized, and the fluctuations are very compressive; that is, the compressive component of the wave clearly dominates over the transverse one. The majority of waves in the downstream region (95%) propagate at oblique angles with respect to the ambient magnetic field (>60 deg.). The wave propagation with respect to the shock-normal direction has no preferred direction and varies similarly to the upstream case. It is possible that downstream fluctuations are generated by ion relaxation as suggested in previous hybrid simulation shocks.

Fatal toxic shock syndrome from an intrauterine device.

PubMed

Klug, Cameron D; Keay, C Ryan; Ginde, Adit A

2009-11-01

Toxic shock syndrome is a rare toxin-mediated condition that can rapidly produce multiorgan failure and severe shock. Toxic shock syndrome has been previously recognized in various clinical situations relating to surgery, nasal packing, abscesses, burns, and most notably menstrual-related cases. This case report describes a previously healthy 33-year-old woman presenting to the emergency department with complaints of nausea, vomiting, and diarrhea; vital signs at triage were normal. Within hours, she developed shock and cardiopulmonary arrest. The patient met all 6 of the Centers for Disease Control and Prevention diagnostic criteria for toxic shock syndrome, and her intrauterine device grew out Staphylococcus aureus. To our knowledge, this is the first reported case in the medical literature of fatal toxic shock syndrome related to an intrauterine device.

Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. II - Wall shear stress

NASA Technical Reports Server (NTRS)

Liou, M. S.; Adamson, T. C., Jr.

1980-01-01

Asymptotic methods are used to calculate the shear stress at the wall for the interaction between a normal shock wave and a turbulent boundary layer on a flat plate. A mixing length model is used for the eddy viscosity. The shock wave is taken to be strong enough that the sonic line is deep in the boundary layer and the upstream influence is thus very small. It is shown that unlike the result found for laminar flow an asymptotic criterion for separation is not found; however, conditions for incipient separation are computed numerically using the derived solution for the shear stress at the wall. Results are compared with available experimental measurements.

Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel

DTIC Science & Technology

2007-12-11

and behind the normal 5 Figure 2.1: Diagram of noise radiated from boundary layer transition on the nozzle wall shock of several pitot probes and a...are lower than those measured with the 0.067 in.-dia. pitot probe because the pressure fluctuations in the subsonic region behind the normal shock are...in.-dia. pitot probe before repolishing nozzle . . . . . . . . . . . . . . . . . . 16 2.10 Freestream noise level in the PQFLT measured with 1 in

Study of relation between Pc 3 micropulsations and magnetosheath fluctuations, and multisatellite investigation of earth's bow shock

NASA Technical Reports Server (NTRS)

Greenstadt, E. W.

1975-01-01

The validity is investigated of a suggested model according to which Pc 3 and/or Pc 4 micropulsations are excited by magnetosheath field (and plasma) fluctuations arising in the quasi-parallel structure of the subsolar bow shock. The influence of solar wind plasma parameters on local shock structure and on the configuration of the entire bow shock system is included. Simultaneous data from two or more spacecraft and from multiple diagnostics is used to evaluate the geometrical factor, field-to-shock normal angle, or its B-X equivalent, and the principal plasma parameters. Results are presented and discussed.

Comparative Analysis of Angiogenic Gene Expression in Normal and Impaired Wound Healing in Diabetic Mice: Effects of Extracorporeal Shock Wave Therapy

DTIC Science & Technology

2010-01-01

vivo. Circulation 110(19): 3055-3061 19. Stojadinovic A, Elster EA, Anam K et al (2008) Angiogenic response to extracorporeal shock wave treatment in...healing in diabetic mice: effects of extracorporeal shock wave therapy Stephen R. Zins • Mihret F. A mare • Douglas K. Tadaki • Eric. A. Elster... extracorporeal shock wave therapy (ESWT), which has been demonstrated to improve wound healing. Full-thick- ness skin from the dorsal surface of "nonnal" (BALB

Anomalous elastic response of silicon to uniaxial shock compression on nanosecond time scales.

PubMed

Loveridge-Smith, A; Allen, A; Belak, J; Boehly, T; Hauer, A; Holian, B; Kalantar, D; Kyrala, G; Lee, R W; Lomdahl, P; Meyers, M A; Paisley, D; Pollaine, S; Remington, B; Swift, D C; Weber, S; Wark, J S

2001-03-12

We have used x-ray diffraction with subnanosecond temporal resolution to measure the lattice parameters of orthogonal planes in shock compressed single crystals of silicon (Si) and copper (Cu). Despite uniaxial compression along the (400) direction of Si reducing the lattice spacing by nearly 11%, no observable changes occur in planes with normals orthogonal to the shock propagation direction. In contrast, shocked Cu shows prompt hydrostaticlike compression. These results are consistent with simple estimates of plastic strain rates based on dislocation velocity data.

An alternatively spliced heat shock transcription factor, OsHSFA2dI, functions in the heat stress-induced unfolded protein response in rice.

PubMed

Cheng, Q; Zhou, Y; Liu, Z; Zhang, L; Song, G; Guo, Z; Wang, W; Qu, X; Zhu, Y; Yang, D

2015-03-01

As sessile organisms, plants have evolved a wide range of defence pathways to cope with environmental stress such as heat shock. However, the molecular mechanism of these defence pathways remains unclear in rice. In this study, we found that OsHSFA2d, a heat shock transcriptional factor, encodes two main splice variant proteins, OsHSFA2dI and OsHSFA2dII in rice. Under normal conditions, OsHSFA2dII is the dominant but transcriptionally inactive spliced form. However, when the plant suffers heat stress, OsHSFA2d is alternatively spliced into a transcriptionally active form, OsHSFA2dI, which participates in the heat stress response (HSR). Further study found that this alternative splicing was induced by heat shock rather than photoperiod. We found that OsHSFA2dI is localised to the nucleus, whereas OsHSFA2dII is localised to the nucleus and cytoplasm. Moreover, expression of the unfolded protein response (UNFOLDED PROTEIN RESPONSE) sensors, OsIRE1, OsbZIP39/OsbZIP60 and the UNFOLDED PROTEIN RESPONSE marker OsBiP1, was up-regulated. Interestingly, OsbZIP50 was also alternatively spliced under heat stress, indicating that UNFOLDED PROTEIN RESPONSE signalling pathways were activated by heat stress to re-establish cellular protein homeostasis. We further demonstrated that OsHSFA2dI participated in the unfolded protein response by regulating expression of OsBiP1. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Extracorporeal shock wave therapy in treatment of delayed bone-tendon healing.

PubMed

Wang, Lin; Qin, Ling; Lu, Hong-bin; Cheung, Wing-hoi; Yang, Hu; Wong, Wan-nar; Chan, Kai-ming; Leung, Kwok-sui

2008-02-01

Extracorporeal shock wave therapy is indicated for treatment of chronic injuries of soft tissues and delayed fracture healing and nonunion. No investigation has been conducted to study the effect of shock wave on delayed healing at the bone-tendon junction. Shock wave promotes osteogenesis, regeneration of fibrocartilage zone, and remodeling of healing tissue in delayed healing of bone-tendon junction surgical repair. Controlled laboratory study. Twenty-eight mature rabbits were used for establishing a delayed healing model at the patella-patellar tendon complex after partial patellectomy and then divided into control and shock wave groups. In the shock wave group, a single shock wave treatment was given at week 6 postoperatively to the patella-patellar tendon healing complex. Seven samples were harvested at week 8 and 7 samples at week 12 for radiologic, densitometric, histologic, and mechanical evaluations. Radiographic measurements showed 293.4% and 185.8% more new bone formation at the patella-patellar tendon healing junction in the shock wave group at weeks 8 and 12, respectively. Significantly better bone mineral status was found in the week 12 shock wave group. Histologically, the shock wave group showed more advanced remodeling in terms of better alignment of collagen fibers and thicker and more mature regenerated fibrocartilage zone at both weeks 8 and 12. Mechanical testing showed 167.7% and 145.1% higher tensile load and strength in the shock wave group at week 8 and week 12, respectively, compared with controls. Extracorporeal shock wave promotes osteogenesis, regeneration of fibrocartilage zone, and remodeling in the delayed bone-to-tendon healing junction in rabbits. These results provide a foundation for future clinical studies toward establishment of clinical indication for treatment of delayed bone-to-tendon junction healing.

Osmolality urine - series (image)

MedlinePlus

Greater-than-normal measurements may indicate: Addison's disease (rare) Congestive heart failure Shock Syndrome of inappropriate ADH secretion Lower-than-normal measurements may indicate: Aldosteronism (very rare) Diabetes insipidus (rare) ...

Ion Movements in Shock in Relation to Survival and Its Modifications

DTIC Science & Technology

1985-01-01

from normal to irreversibly injured are initiated and modified by primary and/or secondary effects of ion redistributions taking place between the...reactions to injury by the shock state has become possible. However, spcclflc aspects concerning effects at the cellular and subcellular levels need...to be further clarified. Therefore, the aim of this study was to characterize the cellular and subcellular effects of hemorrhagic and bacteremic shock

Data reduction and analysis of ISEE magnetometer experiment

NASA Technical Reports Server (NTRS)

Russell, C. T.

1982-01-01

The ISEE-1 and -2 magnetometer data was reduced. The up and downstream turbulence associated with interplanetary shocks were studied, including methods of determining shock normals, and the similarities and differences in laminar and quasi-laminar shock structure. The associated up and downstream turbulence was emphasized. The distributions of flux transfer events, field aligned currents in the near tail, and substorm dynamics in the magnetotail were also investigated.

Optical techniques for determination of normal shock position in supersonic flows for aerospace applications

NASA Technical Reports Server (NTRS)

Adamovsky, Grigory; Eustace, John G.

1990-01-01

Techniques for the quantitative determination of shock position in supersonic flows using direct and indirect methods is presented. A description of an experimental setup is also presented, different configurations of shock position sensing systems are explained, and some experimental results are given. All of the methods discussed are analyzed to determine the ease of technology transfer from the laboratory to in-flight operation.

Investigation of Heat Transfer to a Flat Plate in a Shock Tube.

DTIC Science & Technology

1987-12-01

2 Objectives and Scope . . . . . .. .. .. .... 5 11. Theory ............... ....... 7 Shock Tube Principles........... 7 Boundary Layer Theory ...in *excess of theory , but the rounded edge flat plate exhibited data which matched or was less than what theory predicted for each Mach number tested...normal shock advancing along an infinite flat plate. For x< Ugt there is a region of interaction between the downstream influence of the leading edge

Effects of shock strength on shock turbulence interaction

NASA Technical Reports Server (NTRS)

Lee, Sangsan

1993-01-01

Direct numerical simulation (DNS) and linear analysis (LIA) of isotropic turbulence interacting with a shock wave are performed for several upstream shock normal Mach numbers (M(sub 1)). Turbulence kinetic energy (TKE) is amplified across the shock wave, but this amplification tends to saturate beyond M(sub 1) = 3.0. TKE amplification and Reynolds stress anisotropy obtained in DNS are consistent with LIA predictions. Rapid evolution of TKE immediate downstream of the shock wave persists for all shock strengths and is attributed to the transfer between kinetic and potential modes of turbulence energy through acoustic fluctuations. Changes in energy spectra and various length scales across the shock wave are predicted by LIA, which is consistent with DNS results. Most turbulence length scales decrease across the shock. Dissipation length scale (rho-bar q(exp 3) / epsilon), however, increases slightly for shock waves with M(sub 1) less than 1.65. Fluctuations in thermodynamic variables behind the shock wave stay nearly isentropic for M(sub 1) less than 1.2 and deviate significantly from isentropy for the stronger shock waves due to large entropy fluctuation generated through the interaction.

Inferring Pre-shock Acoustic Field From Post-shock Pitot Pressure Measurement

NASA Astrophysics Data System (ADS)

Wang, Jian-Xun; Zhang, Chao; Duan, Lian; Xiao, Heng; Virginia Tech Team; Missouri Univ of Sci; Tech Team

2017-11-01

Linear interaction analysis (LIA) and iterative ensemble Kalman method are used to convert post-shock Pitot pressure fluctuations to static pressure fluctuations in front of the shock. The LIA is used as the forward model for the transfer function associated with a homogeneous field of acoustic waves passing through a nominally normal shock wave. The iterative ensemble Kalman method is then employed to infer the spectrum of upstream acoustic waves based on the post-shock Pitot pressure measured at a single point. Several test cases with synthetic and real measurement data are used to demonstrate the merits of the proposed inference scheme. The study provides the basis for measuring tunnel freestream noise with intrusive probes in noisy supersonic wind tunnels.

Shock-jump conditions in a general medium: weak-solution approach

NASA Astrophysics Data System (ADS)

Forbes, L. K.; Krzysik, O. A.

2017-05-01

General conservation laws are considered, and the concept of a weak solution is extended to the case of an equation involving three space variables and time. Four-dimensional vector calculus is used to develop general jump conditions at a shock wave in the material. To illustrate the use of this result, jump conditions at a shock in unsteady three-dimensional compressible gas flow are presented. It is then proved rigorously that these reduce to the commonly assumed conditions in coordinates normal and tangential to the shock face. A similar calculation is also outlined for an unsteady three-dimensional shock in magnetohydrodynamics, and in a chemically reactive fluid. The technique is available for determining shock-jump conditions in quite general continuous media.

Shock analysis - Three useful new relations. [collisionless hydromagnetic shocks in space plasmas

NASA Technical Reports Server (NTRS)

Smith, Edward J.; Burton, Marcia E.

1988-01-01

The behavior of collisionless hydromagnetic shocks in interplanetary space is considered analytically, with a focus on relations, implicit in the governing Rankine-Hugoniot equations, involving the magnetic field (B) and the plasma velocity (V). A moving reference frame aligned with the shock is employed, and expressions are derived which make it possible (1) to determine the speed of a shock of arbitrary orientation from upstream and downstream measurements of B and V; (2) to characterize the change in flow direction as the plasma crosses the shock in terms of the plasma beta, the Mach number, and the angle between the upstream field and the shock normal; and (3) to infer the third component of the upstream-downstream velocity jump from B and two-dimensional V measurements. These expressions are applied to ISEE-3 data on an interplanetary shock on April 5, 1979, and the results are presented in tables.

Simulation of ideal-gas flow by nitrogen and other selected gases at cryogenic temperatures. [transonic flow in cryogenic wind tunnels

NASA Technical Reports Server (NTRS)

Hall, R. M.; Adcock, J. B.

1981-01-01

The real gas behavior of nitrogen, the gas normally used in transonic cryogenic tunnels, is reported for the following flow processes: isentropic expansion, normal shocks, boundary layers, and interactions between shock waves and boundary layers. The only difference in predicted pressure ratio between nitrogen and an ideal gas which may limit the minimum operating temperature of transonic cryogenic wind tunnels occur at total pressures approaching 9 atm and total temperatures 10 K below the corresponding saturation temperature. These pressure differences approach 1 percent for both isentropic expansions and normal shocks. Alternative cryogenic test gases were also analyzed. Differences between air and an ideal diatomic gas are similar in magnitude to those for nitrogen and should present no difficulty. However, differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. It is concluded that helium and cryogenic hydrogen would not approximate the compressible flow of an ideal diatomic gas.

Perforated peptic ulcer in southeastern Taiwan.

PubMed

Li, Chin-Hsien; Chang, Wen-Hsiung; Shih, Shou-Chuan; Lin, Shee-Chan; Bair, Ming-Jong

2010-09-01

No studies focus on the population with perforated peptic ulcer in southeastern Taiwan. The present study aimed to assess the differences between the different races and the risk factors related to mortality and morbidity in postoperative patients in southeastern Taiwan. The medical records of 237 patients were reviewed retrospectively. The following factors were analyzed: patient profiles, coexisting illnesses, diagnostic method, fever, preoperative shock, clinical data at emergency room, delay operation, site of perforation, operative method, positive ascites culture, species of microbes in ascites culture, postoperative complications, death and the length of hospital stay. Aborigines were significantly different from non-aborigines in the ratio of female cases and in the habits of alcohol drinking and betel nut chewing. There were also four significantly different variables between them: fever, hemoglobin value, site of perforation and operative method. Total postoperative complication rate was 41.3% and 39 patients (16.6%) died. In multivariate analysis, age > or = 65 years, lipase > upper normal limit and preoperative shock were independent predictors of mortality. Significant risk factors associated with morbidity were NSAIDs use, creatinine > 1.5 mg/dL and preoperative shock. Aborigines were different from non-aborigines in several categories. In southeastern Taiwan, NSAIDs use, creatinine > 1.5 mg/dL and preoperative shock were independent risk factors of morbidity, and age > or = 65 years, lipase > upper normal limit and preoperative shock were independent risk factors of mortality in postoperative perforated peptic ulcer. Lipase > upper normal limit is needed for further research on the influence on mortality.

Spectroscopic study of shock-induced decomposition in ammonium perchlorate single crystals.

PubMed

Gruzdkov, Y A; Winey, J M; Gupta, Y M

2008-05-01

Time-resolved Raman scattering measurements were performed on ammonium perchlorate (AP) single crystals under stepwise shock loading. For particular temperature and pressure conditions, the intensity of the Raman spectra in shocked AP decayed exponentially with time. This decay is attributed to shock-induced chemical decomposition in AP. A series of shock experiments, reaching peak stresses from 10-18 GPa, demonstrated that higher stresses inhibit decomposition while higher temperatures promote it. No orientation dependence was found when AP crystals were shocked normal to the (210) and (001) crystallographic planes. VISAR (velocity interferometer system for any reflector) particle velocity measurements and time-resolved optical extinction measurements carried out to verify these observations are consistent with the Raman data. The combined kinetic and spectroscopic results are consistent with a proton-transfer reaction as the first decomposition step in shocked AP.

The quasiperpendicular environment of large magnetic pulses in Earth's quasiparallel foreshock - ISEE 1 and 2 observations

NASA Technical Reports Server (NTRS)

Greenstadt, E. W.; Moses, S. L.; Coroniti, F. V.; Farris, M. H.; Russell, C. T.

1993-01-01

ULF waves in Earth's foreshock cause the instantaneous angle theta-B(n) between the upstream magnetic field and the shock normal to deviate from its average value. Close to the quasi-parallel (Q-parallel) shock, the transverse components of the waves become so large that the orientation of the field to the normal becomes quasi-perpendicular (Q-perpendicular) during applicable phases of each wave cycle. Large upstream pulses of B were observed completely enclosed in excursions of Theta-B(n) into the Q-perpendicular range. A recent numerical simulation included Theta-B(n) among the parameters examined in Q-parallel runs, and described a similar coincidence as intrinsic to a stage in development of the reformation process of such shocks. Thus, the natural environment of the Q-perpendicular section of Earth's bow shock seems to include an identifiable class of enlarged magnetic pulses for which local Q-perpendicular geometry is a necessary association.

Observations on the normal reflection of gaseous detonations

NASA Astrophysics Data System (ADS)

Damazo, J.; Shepherd, J. E.

2017-09-01

Experimental results are presented examining the behavior of the shock wave created when a gaseous detonation wave normally impinges upon a planar wall. Gaseous detonations are created in a 7.67-m-long, 280-mm-internal-diameter detonation tube instrumented with a test section of rectangular cross section enabling visualization of the region at the tube-end farthest from the point of detonation initiation. Dynamic pressure measurements and high-speed schlieren photography in the region of detonation reflection are used to examine the characteristics of the inbound detonation wave and outbound reflected shock wave. Data from a range of detonable fuel/oxidizer/diluent/initial pressure combinations are presented to examine the effect of cell-size and detonation regularity on detonation reflection. The reflected shock does not bifurcate in any case examined and instead remains nominally planar when interacting with the boundary layer that is created behind the incident wave. The trajectory of the reflected shock wave is examined in detail, and the wave speed is found to rapidly change close to the end-wall, an effect we attribute to the interaction of the reflected shock with the reaction zone behind the incident detonation wave. Far from the end-wall, the reflected shock wave speed is in reasonable agreement with the ideal model of reflection which neglects the presence of a finite-length reaction zone. The net far-field effect of the reaction zone is to displace the reflected shock trajectory from the predictions of the ideal model, explaining the apparent disagreement of the ideal reflection model with experimental reflected shock observations of previous studies.

Defibrillation depends on conductivity fluctuations and the degree of disorganization in reentry patterns.

PubMed

Plank, Gernot; Leon, L Joshua; Kimber, Shane; Vigmond, Edward J

2005-02-01

Defibrillation depends on conductivity and disorganization. Cardiac fibrillation is the deterioration of the heart's normally well-organized activity into one or more meandering spiral waves, which subsequently break up into many meandering wave fronts. Delivery of an electric shock (defibrillation) is the only effective way of restoring the normal rhythm. This study focuses on examining whether higher degrees of disorganization requires higher shock strengths to defibrillate and whether microscopic conductivity fluctuations favor shock success. We developed a three-dimensional computer bidomain model of a block of cardiac tissue with straight fibers immersed in a conductive bath. The membrane behavior was described by the Courtemanche human atrial action potential model incorporating electroporation and an acetylcholine- (ACh) dependent potassium current. Intracellular conductivities were varied stochastically around nominal values with variations of up to 50%. A single rotor reentry was initiated and, by adjusting the spatial ACh variation, the level of organization could be controlled. The single rotor could be stabilized or spiral wave breakup could be provoked leading to fibrillatory-like activity. For each level of organization, multiple shock timings and strengths were applied to compute the probability of shock success as a function of shock strength. Our results suggest that the level of the small-scale conductivity fluctuations is a very important factor in defibrillation. A higher variation significantly lowers the required shock strength. Further, we demonstrated that success also heavily depends on the level of organization of the fibrillatory episode. In general, higher levels of disorganization require higher shock strengths to defibrillate.

Earth's Bow Shock: Elapsed-Time Observations by Two Closely Spaced Satellites.

PubMed

Greenstadt, E W; Green, I M; Colburn, D S

1968-11-22

Coordinated observations of the earth's bow shock were made as Vela 3A and Explorer 33 passed within 6 earth radii of each other. Elapsed time measurements of shock motion give directly determined velocities in the range 1 to 10 kilometers per second and establish the existence of two regions, one of large amplitude magnetic "shock" oscillations and another of smaller, sunward, upstream oscillations. Each region is as thick as 1 earth radius, or more.

Expansion shock waves in regularized shallow-water theory

NASA Astrophysics Data System (ADS)

El, Gennady A.; Hoefer, Mark A.; Shearer, Michael

2016-05-01

We identify a new type of shock wave by constructing a stationary expansion shock solution of a class of regularized shallow-water equations that include the Benjamin-Bona-Mahony and Boussinesq equations. An expansion shock exhibits divergent characteristics, thereby contravening the classical Lax entropy condition. The persistence of the expansion shock in initial value problems is analysed and justified using matched asymptotic expansions and numerical simulations. The expansion shock's existence is traced to the presence of a non-local dispersive term in the governing equation. We establish the algebraic decay of the shock as it is gradually eroded by a simple wave on either side. More generally, we observe a robustness of the expansion shock in the presence of weak dissipation and in simulations of asymmetric initial conditions where a train of solitary waves is shed from one side of the shock.

IRREVERSIBLE HEMORRHAGIC SHOCK IN GERMFREE RATS

PubMed Central

Zweifach, B. W.; Gordon, H. A.; Wagner, M.; Reyniers, J. A.

1958-01-01

Evidence has been provided that a state of irreversible hemorrhagic shock can be induced in a bacteria-free environment in rats reared under germfree conditions. The response to bleeding, the duration of the hypotensive episode and the pathological changes were the same in the germfree and in normal stock rats. The findings are interpreted as evidence opposed to the concept that bacteria or bacterial products are implicated, as primary factors, in the pathogenicity of shock. PMID:13513911

The impact of body mass index on the wearable cardioverter defibrillator shock efficacy and patient wear time.

PubMed

Wan, Chingping; Szymkiewicz, Steven J; Klein, Helmut U

2017-04-01

The impact of body mass index (BMI) on the shock efficacy and patient adherence among patients using a wearable cardioverter defibrillator (WCD) is unknown. Patients prescribed the WCD between January 1, 2008 and June 1, 2013, who experienced at least one episode of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and who received appropriate WCD therapy, were identified within a registry maintained by the manufacturer for regulatory, reimbursement, and administrative purposes. The registry contained patients' Body Mass Index (BMI) which was categorized as normal (18.0

Computing Normal Shock-Isotropic Turbulence Interaction With Tetrahedral Meshes and the Space-Time CESE Method

NASA Astrophysics Data System (ADS)

Venkatachari, Balaji Shankar; Chang, Chau-Lyan

2016-11-01

The focus of this study is scale-resolving simulations of the canonical normal shock- isotropic turbulence interaction using unstructured tetrahedral meshes and the space-time conservation element solution element (CESE) method. Despite decades of development in unstructured mesh methods and its potential benefits of ease of mesh generation around complex geometries and mesh adaptation, direct numerical or large-eddy simulations of turbulent flows are predominantly carried out using structured hexahedral meshes. This is due to the lack of consistent multi-dimensional numerical formulations in conventional schemes for unstructured meshes that can resolve multiple physical scales and flow discontinuities simultaneously. The CESE method - due to its Riemann-solver-free shock capturing capabilities, non-dissipative baseline schemes, and flux conservation in time as well as space - has the potential to accurately simulate turbulent flows using tetrahedral meshes. As part of the study, various regimes of the shock-turbulence interaction (wrinkled and broken shock regimes) will be investigated along with a study on how adaptive refinement of tetrahedral meshes benefits this problem. The research funding for this paper has been provided by Revolutionary Computational Aerosciences (RCA) subproject under the NASA Transformative Aeronautics Concepts Program (TACP).

Noncoplanar component of the magnetic field at low Mach number shocks

NASA Technical Reports Server (NTRS)

Friedman, M. A.; Russell, C. T.; Gosling, J. T.; Thomsen, M. F.

1990-01-01

The component of the magnetic field that deviates from the plane defined by the shock normal and the upstream magnetic field is examined for low Mach number bow shocks. The integrated value of this noncoplanar component is compared to the predictions of Jones and Ellison (1987). A test of this relationship was first reported by Gosling et al. (1988) who found good agreement only at the two low Mach number shocks that were included in their study. Analysis of a more extensive collection of low Mach number shocks confirms the Jones and Ellison relationship at very low Mach numbers as well as its deterioration for higher Mach numbers. However, there also is an indication that the relationship may break down for shocks that are nearly perpendicular.

Hydrogen-Helium shock Radiation tests for Saturn Entry Probes

NASA Technical Reports Server (NTRS)

Cruden, Brett A.

2016-01-01

This paper describes the measurement of shock layer radiation in Hydrogen/Helium mixtures representative of that encountered by probes entering the Saturn atmosphere. Normal shock waves are measured in Hydrogen-Helium mixtures (89:11% by volume) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 km/s. Radiance is quantified from the Vacuum Ultraviolet through Near Infrared. An induction time of several centimeters is observed where electron density and radiance remain well below equilibrium. Radiance is observed in front of the shock layer, the characteristics of which match the expected diffusion length of Hydrogen.

Control of shock-wave boundary-layer interactions by bleed in supersonic mixed compression inlets

NASA Technical Reports Server (NTRS)

Fukuda, M. K.; Reshotko, E.; Hingst, W. R.

1975-01-01

An experimental investigation has been conducted to determine the effect of bleed region geometry and bleed rate on shock wave-boundary layer interactions in an axisymmetric, mixed-compression inlet at a Mach number of 2.5. The full realizable reduction in transformed form factor is obtained by bleeding off about half the incident boundary layer mass flow. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise. Slanted holes are more effective than normal holes. Two different bleed hole sizes were tested without detectable difference in performance.

Circumstellar X-ray Emission from SN1978K

NASA Astrophysics Data System (ADS)

Schlegel, Eric M.; Colbert, E.; Petre, R.

1995-02-01

We present the X-ray light curve in the 0.2 2.4 keV band based on fiveROSAT observations of SN1978K in NGC 1313. The X-ray emission is believed to arise from the interaction of the reverse shock and the expanding debris from the supernova. The reverse shock becomes established after the outgoing shock runs into circumstellar matter.

Measuring the Shock Stage of Asteroid Regolith Grains by Electron Back-Scattered Diffraction

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Martinez, James; Sitzman, Scott; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Terada, Yasuko; Yagi, Naoto; Komatsu, Mutsumi; Ozawa, Hikaru;

Distribution of escaping ions produced by non-specular reflection at the stationary quasi-perpendicular shock front

NASA Astrophysics Data System (ADS)

Gedalin, M.; Liverts, M.; Balikhin, M. A.

2008-05-01

Field-aligned and gyrophase bunched ion beams are observed in the foreshock of the Earth bow shock. One of the mechanisms proposed for their production is non-specular reflection at the shock front. We study the distributions which are formed at the stationary quasi-perpendicular shock front within the same process which is responsible for the generation of reflected ions and transmitted gyrating ions. The test particle motion analysis in a model shock allows one to identify the parameters which control the efficiency of the process and the features of the escaping ion distribution. These parameters are: the angle between the shock normal and the upstream magnetic field, the ratio of the ion thermal velocity to the flow velocity upstream, and the cross-shock potential. A typical distribution of escaping ions exhibits a bimodal pitch angle distribution (in the plasma rest frame).

The variety of MHD shock waves interactions in the solar wind flow

NASA Technical Reports Server (NTRS)

Grib, S. A.

1995-01-01

Different types of nonlinear shock wave interactions in some regions of the solar wind flow are considered. It is shown, that the solar flare or nonflare CME fast shock wave may disappear as the result of the collision with the rotational discontinuity. By the way the appearance of the slow shock waves as the consequence of the collision with other directional discontinuity namely tangential is indicated. Thus the nonlinear oblique and normal MHD shock waves interactions with different solar wind discontinuities (tangential, rotational, contact, shock and plasmoidal) both in the free flow and close to the gradient regions like the terrestrial magnetopause and the heliopause are described. The change of the plasma pressure across the solar wind fast shock waves is also evaluated. The sketch of the classification of the MHD discontinuities interactions, connected with the solar wind evolution is given.

Diffraction of a shock wave by a compression corner; regular and single Mach reflection

NASA Technical Reports Server (NTRS)

Vijayashankar, V. S.; Kutler, P.; Anderson, D.

1976-01-01

The two dimensional, time dependent Euler equations which govern the flow field resulting from the injection of a planar shock with a compression corner are solved with initial conditions that result in either regular reflection or single Mach reflection of the incident planar shock. The Euler equations which are hyperbolic are transformed to include the self similarity of the problem. A normalization procedure is employed to align the reflected shock and the Mach stem as computational boundaries to implement the shock fitting procedure. A special floating fitting scheme is developed in conjunction with the method of characteristics to fit the slip surface. The reflected shock, the Mach stem, and the slip surface are all treated as harp discontinuities, thus, resulting in a more accurate description of the inviscid flow field. The resulting numerical solutions are compared with available experimental data and existing first-order, shock-capturing numerical solutions.

Expansion shock waves in regularized shallow-water theory

PubMed Central

El, Gennady A.; Shearer, Michael

2016-01-01

We identify a new type of shock wave by constructing a stationary expansion shock solution of a class of regularized shallow-water equations that include the Benjamin–Bona–Mahony and Boussinesq equations. An expansion shock exhibits divergent characteristics, thereby contravening the classical Lax entropy condition. The persistence of the expansion shock in initial value problems is analysed and justified using matched asymptotic expansions and numerical simulations. The expansion shock's existence is traced to the presence of a non-local dispersive term in the governing equation. We establish the algebraic decay of the shock as it is gradually eroded by a simple wave on either side. More generally, we observe a robustness of the expansion shock in the presence of weak dissipation and in simulations of asymmetric initial conditions where a train of solitary waves is shed from one side of the shock. PMID:27279780

Radiation Modeling in Shock-Tubes and Entry Flows

DTIC Science & Technology

2009-09-01

the MSRO surface , the local spherical coordinate system with a normal n is entered. Radiation Modeling in Shock-Tubes and Entry Flows 10 - 30 RTO...for each simulated photon group. Radiation Modeling in Shock-Tubes and Entry Flows 10 - 52 RTO-EN-AVT-162 There are two algorithms. In the first...Tubes and Entry Flows RTO-EN-AVT-162 10 - 57 all surfaces of the spatial finite-difference mesh should be calculated. This is illustrated in Figure

Coagulopathy and shock on admission is associated with mortality for children with traumatic injuries at combat support hospitals.

PubMed

Patregnani, Jason T; Borgman, Matthew A; Maegele, Marc; Wade, Charles E; Blackbourne, Lorne H; Spinella, Philip C

2012-05-01

In adults, early traumatic coagulopathy and shock are both common and independently associated with mortality. There are little data regarding both the incidence and association of early coagulopathy and shock on outcomes in pediatric patients with traumatic injuries. Our objective was to determine whether coagulopathy and shock on admission are independently associated with mortality in children with traumatic injuries. A retrospective review of the Joint Theater Trauma Registry from U.S. combat support hospitals in Iraq and Afghanistan from 2002 to 2009 was performed. Coagulopathy was defined as an international normalized ratio of ≥1.5 and shock as a base deficit of ≥6. Laboratory values were measured on admission. Primary outcome was inhospital mortality. Univariate analyses were performed on all admission variables followed by reverse stepwise multivariate logistic regression to determine independent associations. Combat support hospitals in Iraq and Afghanistan. Patients <18 yrs of age with Injury Severity Score, international normalized ratio, base deficit, and inhospital mortality were included. Of 1998 in the cohort, 744 (37%) had a complete set of data for analysis. None. The incidence of early coagulopathy and shock were 27% and 38.3% and associated with mortality of 22% and 16.8%, respectively. After multivariate logistic regression, early coagulopathy had an odds ratio of 2.2 (95% confidence interval 1.1-4.5) and early shock had an odds ratio of 3.0 (95% confidence interval 1.2-7.5) for mortality. Patients with coagulopathy and shock had an odds ratio of 3.8 (95% confidence interval 2.0-7.4) for mortality. In children with traumatic injuries treated at combat support hospitals, coagulopathy and shock on admission are common and independently associated with a high incidence of inhospital mortality. Future studies are needed to determine whether more rapid and accurate methods of measuring coagulopathy and shock as well as if early goal-directed treatment of these states can improve outcomes in children.

Molecular architecture of the hsp70 promoter after deletion of the TATA box or the upstream regulation region.

PubMed Central

Weber, J A; Taxman, D J; Lu, Q; Gilmour, D S

1997-01-01

GAGA factor, TFIID, and paused polymerase are present on the hsp70 promoter in Drosophila melanogaster prior to transcriptional activation. In order to investigate the interplay between these components, mutant constructs were analyzed after they had been transformed into flies on P elements. One construct lacked the TATA box and the other lacked the upstream regulatory region where GAGA factor binds. Transcription of each mutant during heat shock was at least 50-fold less than that of a normal promoter construct. Before and after heat shock, both mutant promoters were found to adopt a DNase I hypersensitive state that included the region downstream from the transcription start site. High-resolution analysis of the DNase I cutting pattern identified proteins that could be contributing to the hypersensitivity. GAGA factor footprints were clearly evident in the upstream region of the TATA deletion construct, and a partial footprint possibly caused by TFIID was evident on the TATA box of the upstream deletion construct. Permanganate treatment of intact salivary glands was used to further characterize each promoter construct. Paused polymerase and TFIID were readily detected on the normal promoter construct, whereas both deletions exhibited reduced levels of each of these factors. Hence both the TATA box and the upstream region are required to efficiently recruit TFIID and a paused polymerase to the promoter prior to transcriptional activation. In contrast, GAGA factor appears to be capable of binding and establishing a DNase I hypersensitive region in the absence of TFIID and polymerase. Interestingly, purified GAGA factor was found to bind near the transcription start site, and the strength of this interaction was increased by the presence of the upstream region. GAGA factor alone might be capable of establishing an open chromatin structure that encompasses the upstream regulatory region as well as the core promoter region, thus facilitating the binding of TFIID. PMID:9199313

Heat shock protein 70 in the rat nasal cavity: localisation and response to hyperthermia.

PubMed

Simpson, Sharon A; Alexander, David J; Reed, Celia J

2004-06-01

Heat shock proteins (HSPs) are a group of proteins that are rapidly induced in response to physiological stress, including hyperthermia and exposure to toxicants. Thus they may provide a useful index of toxicity in in vitro systems for screening for toxicity. We have recently developed a rat nasal explant system for investigating upper respiratory tract toxicity, and the aims of this study were to localise HSP70 within the rat nasal cavity and to characterise its response to hyperthermia. Constitutively, HSP70 was found to be predominantly localised to the sustentacular cells, basal cells and Bowman's glands of the olfactory epithelium (OE), with the most intense immunohistochemical staining at levels 3 and 4 of the posterior of the rat nasal cavity. Ethmoturbinates (ETs) and liver slices were exposed to heat shock (37 degrees and 43 degrees C, respectively) for 45 min and then returned to normal culture temperatures (31 degrees and 37 degrees C, respectively) for 24 h. In ETs, HSP72 was maximally induced 4-fold at 4 h after heat shock, and levels then returned to those of control tissue. ATP concentrations were markedly decreased up to 4 h after heat shock and then returned to control levels. In contrast, HSP72 levels in liver slices increased and ATP levels decreased steadily throughout the 24 h culture period. ETs were also able to withstand a 45-min heat shock at 43 degrees C, that is 12 degrees C above normal culture temperature. Incubation of ETs with cycloheximide prior to heat shock reduced the ability of the OE to recover from heat shock at 37 degrees C. Thus the OE of the rat nasal cavity expresses HSP72, and this protein appears to play an important role in the ability of the tissue to withstand hyperthermia.

Expression of the Caulobacter heat shock gene dnaK is developmentally controlled during growth at normal temperatures.

PubMed Central

Gomes, S L; Gober, J W; Shapiro, L

1990-01-01

Caulobacter crescentus has a single dnaK gene that is highly homologous to the hsp70 family of heat shock genes. Analysis of the cloned and sequenced dnaK gene has shown that the deduced amino acid sequence could encode a protein of 67.6 kilodaltons that is 68% identical to the DnaK protein of Escherichia coli and 49% identical to the Drosophila and human hsp70 protein family. A partial open reading frame 165 base pairs 3' to the end of dnaK encodes a peptide of 190 amino acids that is 59% identical to DnaJ of E. coli. Northern blot analysis revealed a single 4.0-kilobase mRNA homologous to the cloned fragment. Since the dnaK coding region is 1.89 kilobases, dnaK and dnaJ may be transcribed as a polycistronic message. S1 mapping and primer extension experiments showed that transcription initiated at two sites 5' to the dnaK coding sequence. A single start site of transcription was identified during heat shock at 42 degrees C, and the predicted promoter sequence conformed to the consensus heat shock promoters of E. coli. At normal growth temperature (30 degrees C), a different start site was identified 3' to the heat shock start site that conformed to the E. coli sigma 70 promoter consensus sequence. S1 protection assays and analysis of expression of the dnaK gene fused to the lux transcription reporter gene showed that expression of dnaK is temporally controlled under normal physiological conditions and that transcription occurs just before the initiation of DNA replication. Thus, in both human cells (I. K. L. Milarski and R. I. Morimoto, Proc. Natl. Acad. Sci. USA 83:9517-9521, 1986) and in a simple bacterium, the transcription of a hsp70 gene is temporally controlled as a function of the cell cycle under normal growth conditions. Images PMID:2345134

Normal shock wave reflection on porous compressible material

NASA Astrophysics Data System (ADS)

Gvozdeva, L. G.; Faresov, Iu. M.; Brossard, J.; Charpentier, N.

The present experimental investigation of the interaction of plane shock waves in air and a rigid wall coated with flat layers of expanded polymers was conducted in a standard shock tube and a diaphragm with an initial test section pressure of 100,000 Pa. The Mach number of the incident shock wave was varied from 1.1 to 2.7; the peak pressures measured on the wall behind polyurethane at various incident wave Mach numbers are compared with calculated values, with the ideal model of propagation, and with the reflection of shock waves in a porous material that is understood as a homogeneous mixture. The effect of elasticity and permeability of the porous material structure on the rigid wall's pressure pulse parameters is qualitatively studied.

Real-air data reduction procedures based on flow parameters measured in the test section of supersonic and hypersonic facilities

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1972-01-01

Data-reduction procedures for determining free stream and post-normal shock kinetic and thermodynamic quantities are derived. These procedures are applicable to imperfect real air flows in thermochemical equilibrium for temperatures to 15 000 K and a range of pressures from 0.25 N/sq m to 1 GN/sq m. Although derived primarily to meet the immediate needs of the 6-inch expansion tube, these procedures are applicable to any supersonic or hypersonic test facility where combinations of three of the following flow parameters are measured in the test section: (1) Stagnation pressure behind normal shock; (2) freestream static pressure; (3) stagnation point heat transfer rate; (4) free stream velocity; (5) stagnation density behind normal shock; and (6) free stream density. Limitations of the nine procedures and uncertainties in calculated flow quantities corresponding to uncertainties in measured input data are discussed. A listing of the computer program is presented, along with a description of the inputs required and a sample of the data printout.

A second-order shock-expansion method applicable to bodies of revolution near zero lift

NASA Technical Reports Server (NTRS)

1957-01-01

A second-order shock-expansion method applicable to bodies of revolution is developed by the use of the predictions of the generalized shock-expansion method in combination with characteristics theory. Equations defining the zero-lift pressure distributions and the normal-force and pitching-moment derivatives are derived. Comparisons with experimental results show that the method is applicable at values of the similarity parameter, the ratio of free-stream Mach number to nose fineness ratio, from about 0.4 to 2.

An Experimental Study of Nonstationary Instabilities of Planar Shock Waves in Ionizing Argon

DTIC Science & Technology

1980-08-01

Distribution is unlimited. A. D. BLOSS Technioal Information Ottoer AN EPERIMeNTAL STUDY OF NONSTATIONARY INSTABILTIES OF PLANAR SHOCK WAVES IN IONIZIG...UTIAS hypervelocity shock tube are performed with the aid of a 23-cm dia aperture Mach-Zehnder interferometer. Details of the design and operation of...and the Q-switching, and normally is designed to be 900 us for optimal single-exposure photos. A different value of t = 500 us was used for some of the

A comparison of shock-cloud and wind-cloud interactions: effect of increased cloud density contrast on cloud evolution

NASA Astrophysics Data System (ADS)

Goldsmith, K. J. A.; Pittard, J. M.

2018-05-01

The similarities, or otherwise, of a shock or wind interacting with a cloud of density contrast χ = 10 were explored in a previous paper. Here, we investigate such interactions with clouds of higher density contrast. We compare the adiabatic hydrodynamic interaction of a Mach 10 shock with a spherical cloud of χ = 103 with that of a cloud embedded in a wind with identical parameters to the post-shock flow. We find that initially there are only minor morphological differences between the shock-cloud and wind-cloud interactions, compared to when χ = 10. However, once the transmitted shock exits the cloud, the development of a turbulent wake and fragmentation of the cloud differs between the two simulations. On increasing the wind Mach number, we note the development of a thin, smooth tail of cloud material, which is then disrupted by the fragmentation of the cloud core and subsequent `mass-loading' of the flow. We find that the normalized cloud mixing time (tmix) is shorter at higher χ. However, a strong Mach number dependence on tmix and the normalized cloud drag time, t_{drag}^' }, is not observed. Mach-number-dependent values of tmix and t_{drag}^' } from comparable shock-cloud interactions converge towards the Mach-number-independent time-scales of the wind-cloud simulations. We find that high χ clouds can be accelerated up to 80-90 per cent of the wind velocity and travel large distances before being significantly mixed. However, complete mixing is not achieved in our simulations and at late times the flow remains perturbed.

On the Unsteadiness of a Transitional Shock Wave-Boundary Layer Interaction Using Fast-Response Pressure-Sensitive Paint

NASA Astrophysics Data System (ADS)

Lash, E. Lara; Schmisseur, John

2017-11-01

Pressure-sensitive paint has been used to evaluate the unsteady dynamics of transitional and turbulent shock wave-boundary layer interactions generated by a vertical cylinder on a flat plate in a Mach 2 freestream. The resulting shock structure consists of an inviscid bow shock that bifurcates into a separation shock and trailing shock. The primary features of interest are the separation shock and an upstream influence shock that is intermittently present in transitional boundary layer interactions, but not observed in turbulent interactions. The power spectral densities, frequency peaks, and normalized wall pressures are analyzed as the incoming boundary layer state changes from transitional to fully turbulent, comparing both centerline and outboard regions of the interaction. The present study compares the scales and frequencies of the dynamics of the separation shock structure in different boundary layer regimes. Synchronized high-speed Schlieren imaging provides quantitative statistical analyses as well as qualitative comparisons to the fast-response pressure sensitive paint measurements. Materials based on research supported by the U.S. Office of Naval Research under Award Number N00014-15-1-2269.

One-dimensional flows of an imperfect diatomic gas

NASA Technical Reports Server (NTRS)

1959-01-01

With the assumptions that Berthelot's equation of state accounts for molecular size and intermolecular force effects, and that changes in the vibrational heat capacities are given by a Planck term, expressions are developed for analyzing one-dimensional flows of a diatomic gas. The special cases of flow through normal and oblique shocks in free air at sea level are investigated. It is found that up to a Mach number 10 pressure ratio across a normal shock differs by less than 6 percent from its ideal gas value; whereas at Mach numbers above 4 the temperature rise is considerable below and hence the density rise is well above that predicted assuming ideal gas behavior. It is further shown that only the caloric imperfection in air has an appreciable effect on the pressures developed in the shock process considered. The effects of gaseous imperfections on oblique shock-flows are studied from the standpoint of their influence on the life and pressure drag of a flat plate operating at Mach numbers of 10 and 20. The influence is found to be small. (author)

A rotationally biased upwind difference scheme for the Euler equations

NASA Technical Reports Server (NTRS)

Davis, S. F.

1983-01-01

The upwind difference schemes of Godunov, Osher, Roe and van Leer are able to resolve one dimensional steady shocks for the Euler equations within one or two mesh intervals. Unfortunately, this resolution is lost in two dimensions when the shock crosses the computing grid at an oblique angle. To correct this problem, a numerical scheme was developed which automatically locates the angle at which a shock might be expected to cross the computing grid and then constructs separate finite difference formulas for the flux components normal and tangential to this direction. Numerical results which illustrate the ability of this method to resolve steady oblique shocks are presented.

Nonholonomic Hamiltonian Method for Meso-macroscale Simulations of Reacting Shocks

NASA Astrophysics Data System (ADS)

Fahrenthold, Eric; Lee, Sangyup

2015-06-01

The seamless integration of macroscale, mesoscale, and molecular scale models of reacting shock physics has been hindered by dramatic differences in the model formulation techniques normally used at different scales. In recent research the authors have developed the first unified discrete Hamiltonian approach to multiscale simulation of reacting shock physics. Unlike previous work, the formulation employs reacting themomechanical Hamiltonian formulations at all scales, including the continuum. Unlike previous work, the formulation employs a nonholonomic modeling approach to systematically couple the models developed at all scales. Example applications of the method show meso-macroscale shock to detonation simulations in nitromethane and RDX. Research supported by the Defense Threat Reduction Agency.

Some new results on shock chemistry in IC 443

NASA Technical Reports Server (NTRS)

Denoyer, L. K.; Frerking, M. A.

1981-01-01

New observations have been made of CO, CO-13, SiO, SO, H2CO, HCO(+), N2H(+), CS, OCS, HCN, and OH in the shocked clouds of IC 443. It is found that at position IC 443 B, (1) the shocked CO is optically thin; (2) the HCO(+)/CO abundance ratio is 4-9 x 10 to the -4 th, representing a tenfold enhancement over that of normal interstellar clouds; (3) there is no enhancement of SO or SIO, as occurs in Orion KL; and (4) there is optically thin preshock OH, confirming a hundredfold enhancement of the OH/CO ratio in the shock.

A probabilistic method to establish the reliability of carbon-carbon rocket motor nozzles. Volume 3: Stress and reliability analysis of layered composite cylinders under thermal shock

NASA Astrophysics Data System (ADS)

Heller, R. A.; Thangjitham, S.; Wang, X.

1992-04-01

The state of stress in a cylindrical structure consisting of multiple layers of carbon-carbon composite and subjected to thermal and pressure shock are analyzed using an elasticity approach. The reliability of the structure based on the weakest link concept and the Weibull distribution is also calculated. Coupled thermo-elasticity is first assumed and is shown to be unnecessary for the material considered. The effects of external and internal thermal shock as well as a superimposed pressure shock are examined. It is shown that for the geometry chosen, the structure may fail when exposed to thermal shock alone while a superimposed pressure shock can mitigate the probability of failure.

Application of the Bootstrap Statistical Method in Deriving Vibroacoustic Specifications

NASA Technical Reports Server (NTRS)

Hughes, William O.; Paez, Thomas L.

2006-01-01

This paper discusses the Bootstrap Method for specification of vibroacoustic test specifications. Vibroacoustic test specifications are necessary to properly accept or qualify a spacecraft and its components for the expected acoustic, random vibration and shock environments seen on an expendable launch vehicle. Traditionally, NASA and the U.S. Air Force have employed methods of Normal Tolerance Limits to derive these test levels based upon the amount of data available, and the probability and confidence levels desired. The Normal Tolerance Limit method contains inherent assumptions about the distribution of the data. The Bootstrap is a distribution-free statistical subsampling method which uses the measured data themselves to establish estimates of statistical measures of random sources. This is achieved through the computation of large numbers of Bootstrap replicates of a data measure of interest and the use of these replicates to derive test levels consistent with the probability and confidence desired. The comparison of the results of these two methods is illustrated via an example utilizing actual spacecraft vibroacoustic data.

Optical Flow for Flight and Wind Tunnel Background Oriented Schlieren Imaging

NASA Technical Reports Server (NTRS)

Smith, Nathanial T.; Heineck, James T.; Schairer, Edward T.

2017-01-01

Background oriented Schlieren images have historically been generated by calculating the observed pixel displacement between a wind-on and wind-o image pair using normalized cross-correlation. This work uses optical flow to solve the displacement fields which generate the Schlieren images. A well established method used in the computer vision community, optical flow is the apparent motion in an image sequence due to brightness changes. The regularization method of Horn and Schunck is used to create Schlieren images using two data sets: a supersonic jet plume shock interaction from the NASA Ames Unitary Plan Wind Tunnel, and a transonic flight test of a T-38 aircraft using a naturally occurring background, performed in conjunction with NASA Ames and Armstrong Research Centers. Results are presented and contrasted with those using normalized cross-correlation. The optical flow Schlieren images are found to provided significantly more detail. We apply the method to historical data sets to demonstrate the broad applicability and limitations of the technique.

Impact and collisional processes in the solar system

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.; Gazis, C.; Pepin, R.; Becker, R.; Cronin, R.; Tyburczy, J.; Tingle, T.; Duffy, T.; Rowan, L.

1991-01-01

As impact cratered terrains have been successively recognized on certain planets and planetary satellites, it has become clear that impact processes are important to the understanding of the accretion and evolution of all solid planets. The noble gases in the normalized atmospheric inventories of the planets and the normalized gas content of meteorites are grossly similar, but demonstrate differences from each other which are not understood. In order to study shock devolatilization of the candidate carrier phases which are principally thought to be carbonaceous or hydrocarbons in planetesimals, experiments were conducted on noble gase implantation in various carbons: carbon black, activated charcoal, graphite, and carbon glass. These were candidate starting materials for impact devolatilization experiments. Initial experiments were conducted on vitreous amorphous carbon samples which were synthesized under vapor saturated conditions using argon as the pressurizing medium. An amino acid and surface analysis by laser ionization analyses were performed on three samples of shocked Murchison meteorite. A first study was completed in which a series of shock loading experiments on a porous limestone and on a non-porous gabbro in one and three dimensions were performed. Also a series of recovery experiments were conducted in which shocked molten basalt a 1700 C is encapsulated in molybdenum containers and shock recovered from up to 6 GPa pressures.

Pathway to a Phenocopy: Heat Stress Effects in Early Embryogenesis

PubMed Central

Crews, Sarah M.; McCleery, W. Tyler; Hutson, M. Shane

2015-01-01

Background Heat shocks applied at the onset of gastrulation in early Drosophila embryos frequently lead to phenocopies of U-shaped mutants – having characteristic failures in the late morphogenetic processes of germband retraction and dorsal closure. The pathway from non-specific heat stress to phenocopied abnormalities is unknown. Results Drosophila embryos subjected to 30-min, 38-°C heat shocks at gastrulation appear to recover and restart morphogenesis. Post-heat-shock development appears normal, albeit slower, until a large fraction of embryos develop amnioserosa holes (diameters > 100 μm). These holes are positively correlated with terminal U-shaped phenocopies. They initiate between amnioserosa cells and open over tens of minutes by evading normal wound healing responses. They are not caused by tissue-wide increases in mechanical stress or decreases in cell-cell adhesion, but instead appear to initiate from isolated apoptosis of amnioserosa cells. Conclusions The pathway from heat shock to U-shaped phenocopies involves the opening of one or more large holes in the amnioserosa that compromise its structural integrity and lead to failures in morphogenetic processes that rely on amnioserosa-generated tensile forces. The proposed mechanism by which heat shock leads to hole initiation and expansion is heterochonicity – i.e., disruption of morphogenetic coordination between embryonic and extra-embryonic cell types. PMID:26498920

A minimal titration model of the mammalian dynamical heat shock response

NASA Astrophysics Data System (ADS)

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.

Numerical and experimental investigation of VG flow control for a low-boom inlet

NASA Astrophysics Data System (ADS)

Rybalko, Michael

The application of vortex generators (VGs) for shock/boundary layer interaction flow control in a novel external compression, axisymmetric, low-boom concept inlet was studied using numerical and experimental methods. The low-boom inlet design features a zero-angle cowl and relaxed isentropic compression centerbody spike, resulting in defocused oblique shocks and a weak terminating normal shock. This allows reduced external gas dynamic waves at high mass flow rates but suffers from flow separation near the throat and a large hub-side boundary layer at the Aerodynamic Interface Plane (AIP), which marks the inflow to the jet engine turbo-machinery. Supersonic VGs were investigated to reduce the shock-induced flow separation near the throat while subsonic VGs were investigated to reduce boundary layer radial distortion at the AIP. To guide large-scale inlet experiments, Reynolds-Averaged Navier-Stokes (RANS) simulations using three-dimensional, structured, chimera (overset) grids and the WIND-US code were conducted. Flow control cases included conventional and novel types of vortex generators at positions both upstream of the terminating normal shock (supersonic VGs) and downstream (subsonic VGs). The performance parameters included incompressible axisymmetric shape factor, post-shock separation area, inlet pressure recovery, and mass flow ratio. The design of experiments (DOE) methodology was used to select device size and location, analyze the resulting data, and determine the optimal choice of device geometry. Based on the above studies, a test matrix of supersonic and subsonic VGs was adapted for a large-scale inlet test to be conducted at the 8'x6' supersonic wind tunnel at NASA Glenn Research Center (GRC). Comparisons of RANS simulations with data from the Fall 2010 8'x6' inlet test showed that predicted VG performance trends and case rankings for both supersonic and subsonic devices were consistent with experimental results. For example, experimental surface oil flow visualization revealed a significant post-shock separation bubble with flow recirculation for the baseline (no VG) case that was substantially broken up in the micro-ramp VG case, consistent with simulations. Furthermore, the predicted subsonic VG performance with respect to a reduction in radial distortion (quantified in terms of axisymmetric incompressible shape factor) was found to be consistent with boundary layer rake measurements. To investigate the unsteady turbulent flow features associated with the shock-induced flow separation and the hub-side boundary layer, a detached eddy simulation (DES) approach using the WIND-US code was employed to model the baseline inlet flow field. This approach yielded improved agreement with experimental data for time-averaged diffuser stagnation pressure profiles and allowed insight into the pressure fluctuations and turbulent kinetic energy distributions which may be present at the AIP. In addition, streamwise shock position statistics were obtained and compared with experimental Schlieren results. The predicted shock oscillations were much weaker than those seen experimentally (by a factor of four), which indicates that the mechanism for the experimental shock oscillations was not captured. In addition, the novel supersonic vortex generator geometries were investigated experimentally (prior to the large-scale inlet 8'x6' wind tunnel tests) in an inlet-relevant flow field containing a Mach 1.4 normal shock wave followed by a subsonic diffuser. A parametric study of device height and distance upstream of the normal shock was undertaken for split-ramp and ramped-vane geometries. Flow field diagnostics included high-speed Schlieren, oil flow visualization, and Pitot-static pressure measurements. Parameters including flow separation, pressure recovery, centerline incompressible boundary layer shape factor, and shock stability were analyzed and compared to the baseline uncontrolled case. While all vortex generators tested eliminated centerline flow separation, the presence of VGs also increased the significant three-dimensionality of the flow via increased side-wall interaction. The stronger streamwise vorticity generated by ramped-vanes also yielded improved pressure recovery and fuller boundary layer velocity profiles within the subsonic diffuser. (Abstract shortened by UMI.)

Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. I - Pressure distribution

NASA Technical Reports Server (NTRS)

Messiter, A. F.

1980-01-01

Asymptotic solutions are derived for the pressure distribution in the interaction of a weak normal shock wave with a turbulent boundary layer. The undisturbed boundary layer is characterized by the law of the wall and the law of the wake for compressible flow. In the limiting case considered, for 'high' transonic speeds, the sonic line is very close to the wall. Comparisons with experiment are shown, with corrections included for the effect of longitudinal wall curvature and for the boundary-layer displacement effect in a circular pipe.

Kinetic Properties of an Interplanetary Shock Propagating inside a Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Liu, Mingzhe; Liu, Ying D.; Yang, Zhongwei; Wilson, L. B., III; Hu, Huidong

2018-05-01

We investigate the kinetic properties of a typical fast-mode shock inside an interplanetary coronal mass ejection (ICME) observed on 1998 August 6 at 1 au, including particle distributions and wave analysis with the in situ measurements from Wind. Key results are obtained concerning the shock and the shock–ICME interaction at kinetic scales: (1) gyrating ions, which may provide energy dissipation at the shock in addition to wave-particle interactions, are observed around the shock ramp; (2) despite the enhanced proton temperature anisotropy of the shocked plasma, the low plasma β inside the ICME constrains the shocked plasma under the thresholds of the ion cyclotron and mirror-mode instabilities; (3) whistler heat flux instabilities, which can pitch-angle scatter halo electrons through a cyclotron resonance, are observed around the shock, and can explain the disappearance of bi-directional electrons (BDEs) inside the ICME together with normal betatron acceleration; (4) whistler waves near the shock are likely associated with the whistler heat flux instabilities excited at the shock ramp, which is consistent with the result that the waves may originate from the shock ramp; (5) the whistlers share a similar characteristic with the shocklet whistlers observed by Wilson et al., providing possible evidence that the shock is decaying because of the strong magnetic field inside the ICME.

Modeling the response of normal and ischemic cardiac tissue to electrical stimulation

NASA Astrophysics Data System (ADS)

Kandel, Sunil Mani

Heart disease, the leading cause of death worldwide, is often caused by ventricular fibrillation. A common treatment for this lethal arrhythmia is defibrillation: a strong electrical shock that resets the heart to its normal rhythm. To design better defibrillators, we need a better understanding of both fibrillation and defibrillation. Fundamental mysteries remain regarding the mechanism of how the heart responds to a shock, particularly anodal shocks and the resultant hyperpolarization. Virtual anodes play critical roles in defibrillation, and one cannot build better defibrillators until these mechanisms are understood. We are using mathematical modeling to numerically simulate observed phenomena, and are exploring fundamental mechanisms responsible for the heart's electrical behavior. Such simulations clarify mechanisms and identify key parameters. We investigate how systolic tissue responds to an anodal shock and how refractory tissue reacts to hyperpolarization by studying the dip in the anodal strength-interval curve. This dip is due to electrotonic interaction between regions of depolarization and hyperpolarization following a shock. The dominance of the electrotonic mechanism over calcium interactions implies the importance of the spatial distribution of virtual electrodes. We also investigate the response of localized ischemic tissue to an anodal shock by modeling a regional elevation of extracellular potassium concentration. This heterogeneity leads to action potential instability, 2:1 conduction block (alternans), and reflection-like reentry at the boarder of the normal and ischemic regions. This kind of reflection (reentry) occurs due to the delay between proximal and distal segments to re-excite the proximal segment. Our numerical simulations are based on the bidomain model, the state-of-the-art mathematical description of how cardiac tissue responds to shocks. The dynamic LuoRudy model describes the active properties of the membrane. To model ischemia, the Luo-Rudy model is modified by adding ischemic-related ion currents and concentrations to mimic conditions during the initial phase of ischemia. The stimulus is applied through a unipolar electrode that induces a complicated spatial distribution of transmembrane potential, including adjacent regions of depolarization and hyperpolarization. This research is significant because it uncovers basic properties of excitation that are fundamental for understanding cardiac pacing and defibrillation.

Small heat shock proteins are necessary for heart migration and laterality determination in zebrafish

PubMed Central

Lahvic, Jamie L.; Ji, Yongchang; Marin, Paloma; Zuflacht, Jonah P.; Springel, Mark W.; Wosen, Jonathan E.; Davis, Leigh; Hutson, Lara D.; Amack, Jeffrey D.; Marvin, Martha J.

2013-01-01

Small heat shock proteins (sHsps) regulate cellular functions not only under stress, but also during normal development, when they are expressed in organ-specific patterns. Here we demonstrate that two small heat shock proteins expressed in embryonic zebrafish heart, hspb7 and hspb12, have roles in the development of left-right asymmetry. In zebrafish, laterality is determined by the motility of cilia in Kupffer’s vesicle (KV), where hspb7 is expressed; knockdown of hspb7 causes laterality defects by disrupting the motility of these cilia. In embryos with reduced hspb7, the axonemes of KV cilia have a 9+0 structure, while control embyros have a predominately 9+2 structure. Reduction of either hspb7 or hspb12 alters the expression pattern of genes that propagate the signals that establish left-right asymmetry: the nodal-related gene southpaw (spaw) in the lateral plate mesoderm, and its downstream targets pitx2, lefty1 and lefty2. Partial depletion of hspb7 causes concordant heart, brain and visceral laterality defects, indicating that loss of KV cilia motility leads causes coordinated but randomized laterality. Reducing hspb12 leads to similar alterations in the expression of downstream laterality genes, but at a lower penetrance. Simultaneous reduction of hspb7 and hspb12 randomizes heart, brain and visceral laterality, suggesting that these two genes have partially redundant functions in the establishment of left-right asymmetry. In addition, both hspb7 and hspb12 are expressed in the precardiac mesoderm and in the yolk syncytial layer, which supports the migration and fusion of mesodermal cardiac precursors. In embryos in which the reduction of hspb7 or hspb12 was limited to the yolk, migration defects predominated, suggesting that the yolk expression of these genes rather than heart expression is responsible for the migration defects. PMID:24140541

Weak incident shock interactions with Mach 8 laminar boundary layers. [of flat plate

NASA Technical Reports Server (NTRS)

Kaufman, L. G., II; Johnson, C. B.

1974-01-01

Weak shock-wave interactions with boundary layers on a flat plate were investigated experimentally in Mach 8 variable-density tunnel for plate-length Reynolds numbers. The undisturbed boundary layers were laminar over the entire plate length. Pressure and heat-transfer distributions were obtained for wedge-generated incident shock waves that resulted in pressure rises ranging from 1.36 to 4.46 (both nonseparated and separated boundary-layer flows). The resulting heat-transfer amplifications ranged from 1.45 to 14. The distributions followed established trends for nonseparated flows, for incipient separation, and for laminar free-interaction pressure rises. The experimental results corroborated established trends for the extent of the pressure rise and for certain peak heat-transfer correlations.

Transparency of the strong shock-compressed diamond for 532 nm laser light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Zhiyu; Department of Engineering Physics, Tsinghua University, Beijing 100084; Zhao, Yang

2016-04-15

An optical reflectivity and transmissivity model for the shock-compressed diamond is established and used to calculate the optical reflectivity and transmissivity of the diamond under different shock compressions. The simulated results indicate that the reflection occurs at the shock front and does not depend on the thickness of the compressed diamond, but the transmissivity decreases with the thickness. The simulated reflectivity is consistent with the experimental results in the literature, which validates the model. It is shown that the diamond keeps transparent when the shock pressure is lower than 2.00 Mbar, and becomes opaque but does not reflect the probemore » laser as the shock pressure increases from 2.00 Mbar to 4.60 Mbar and reflects the probe laser markedly when the shock pressure is higher than 4.60 Mbar.« less

Axial magnetic field and toroidally streaming fast ions in the dense plasma focus are natural consequences of conservation laws in the curved axisymmetric geometry of the current sheath. II. Towards a first principles theory

NASA Astrophysics Data System (ADS)

Auluck, S. K. H.

2017-11-01

This paper continues earlier discussion [S. K. H. Auluck, Phys. Plasmas 21, 102515 (2014)] concerning the formulation of conservation laws of mass, momentum, and energy in a local curvilinear coordinate system in the dense plasma focus. This formulation makes use of the revised Gratton-Vargas snowplow model [S. K. H. Auluck, Phys. Plasmas 20, 112501 (2013)], which provides an analytically defined imaginary surface in three dimensions which resembles the experimentally determined shape of the plasma. Unit vectors along the local tangent to this surface, along the azimuth, and along the local normal define a right-handed orthogonal local curvilinear coordinate system. The simplifying assumption that physical quantities have significant variation only along the normal enables writing laws of conservation of mass, momentum, and energy in the form of effectively one-dimensional hyperbolic conservation law equations using expressions for various differential operators derived for this coordinate system. This formulation demonstrates the highly non-trivial result that the axial magnetic field and toroidally streaming fast ions, experimentally observed by multiple prestigious laboratories, are natural consequences of conservation of mass, momentum, and energy in the curved geometry of the dense plasma focus current sheath. The present paper continues the discussion in the context of a 3-region shock structure similar to the one experimentally observed: an unperturbed region followed by a hydrodynamic shock containing some current followed by a magnetic piston. Rankine-Hugoniot conditions are derived, and expressions are obtained for the specific volumes and pressures using the mass-flux between the hydrodynamic shock and the magnetic piston and current fraction in the hydrodynamic shock as unknown parameters. For the special case of a magnetic piston that remains continuously in contact with the fluid being pushed, the theory gives closed form algebraic results for the fraction of current flowing in the hydrodynamic shock, specific volume, pressure, and fluid velocity of the hydrodynamic shock region, the tangential, normal, and azimuthal components of velocity in the magnetized plasma, the density of the magnetized plasma, the normal and tangential components of the magnetic field, and the tangential, normal, and azimuthal components of the electric field. This explains the occurrence of azimuthally streaming high energy deuterons experimentally observed by Frascati and Stuttgart. The expression derived for the azimuthal component of vector potential can serve as the basis for a proposed experimental test of the theory.

Investigating the ability of solar coronal shocks to accelerate solar energetic particles

NASA Astrophysics Data System (ADS)

Kwon, R. Y.; Vourlidas, A.

2017-12-01

We estimate the density compression ratio of shocks associated with coronal mass ejections (CMEs) and investigate whether they can accelerate solar energetic particles (SEPs). Using remote-sensing, multi-viewpoint coronagraphic observations, we have developed a method to extract the sheath electron density profiles along the shock normal and estimate the density compression ratio. Our method uses the ellipsoid model to derive the 3D geometry of the sheaths, including the line-of-sight (LOS) depth. The sheath density profiles along the shock normal are modeled with double-Gaussian functions, and the modeled densities are integrated along the LOSs to be compared with the observed brightness in STEREO COR2-Ahead. The upstream densities are derived from either the pB-inversion of the brightness in a pre-event image or an empirical model. We analyze two fast halo CMEs observed on 2011 March 7 and 2014 February 25 that are associated with SEP events detected by multiple spacecraft located over a broad range of heliolongitudes. We find that the density compression peaks around the CME nose and decreases at larger position angles. Interestingly, we find that the supercritical region extends over a large area of the shock and lasts longer (several tens of minutes) than past reports. This finding implies that CME shocks may be capable of accelerating energetic particles in the corona over extended spatial and temporal scales and may, therefore, be responsible for the wide longitudinal distribution of these particles in the inner heliosphere.

Hepatic Shock Differential Diagnosis and Risk Factors: A Review Article.

PubMed

Soleimanpour, Hassan; Safari, Saeid; Rahmani, Farzad; Nejabatian, Arezu; Alavian, Seyed Moayed

2015-10-01

Liver as an important organ has a vital role in physiological processes in the body. Different causes can disrupt normal function of liver. Factors such as hypo-perfusion, hypoxemia, infections and some others can cause hepatic injury and hepatic shock. Published research resources from 2002 to May 2015 in some databases (PubMed, Scopus, Index Copernicus, DOAJ, EBSCO-CINAHL, Science direct, Cochrane library and Google scholar and Iranian search database like SID and Iranmedex) were investigated for the present study. Different causes can lead to hepatic shock. Most of these causes can be prevented by early resuscitation and treatment of underlying factors. Hepatic shock is detected in ill patients, especially those with hemodynamic disorders. It can be prevented by early treatment of underlying disease. There is no definite treatment for hepatic shock and should be managed conservatively. Hepatic shock in patients can increase the mortality rate.

Hepatic Shock Differential Diagnosis and Risk Factors: A Review Article

PubMed Central

Soleimanpour, Hassan; Safari, Saeid; Rahmani, Farzad; Nejabatian, Arezu; Alavian, Seyed Moayed

2015-01-01

Context: Liver as an important organ has a vital role in physiological processes in the body. Different causes can disrupt normal function of liver. Factors such as hypo-perfusion, hypoxemia, infections and some others can cause hepatic injury and hepatic shock. Evidence Acquisition: Published research resources from 2002 to May 2015 in some databases (PubMed, Scopus, Index Copernicus, DOAJ, EBSCO-CINAHL, Science direct, Cochrane library and Google scholar and Iranian search database like SID and Iranmedex) were investigated for the present study. Results: Different causes can lead to hepatic shock. Most of these causes can be prevented by early resuscitation and treatment of underlying factors. Conclusions: Hepatic shock is detected in ill patients, especially those with hemodynamic disorders. It can be prevented by early treatment of underlying disease. There is no definite treatment for hepatic shock and should be managed conservatively. Hepatic shock in patients can increase the mortality rate. PMID:26587034

Density-transition scale at quasiperpendicular collisionless shocks.

PubMed

Bale, S D; Mozer, F S; Horbury, T S

2003-12-31

Measurements of a spacecraft floating potential, on the four Cluster spacecraft, are used as a proxy for electron plasma density to study, for the first time, the macroscopic density transition scale at 98 crossings of the quasiperpendicular terrestrial bow shock. A timing analysis gives shock speeds and normals; the shock speed is used to convert the temporal measurement to a spatial one. A hyperbolic tangent function is fitted to each density transition, which captures the main shock transition, but not overshoot or undershoot nor foot features. We find that, at a low Mach number M, the density transition is consistent with both ion inertial scales c/omega(pi) and convected gyroradii v(sh,n)/Omega(ci,2), while at M>/=4-5 only the convected gyroradius is the preferred scale for the shock density transition and takes the value L approximately 0.4v(sh,n)/Omega(ci,2).

Steady flow on to a conveyor belt - Causal viscosity and shear shocks

NASA Technical Reports Server (NTRS)

Syer, D.; Narayan, Ramesh

1993-01-01

Some hydrodynamical consequences of the adoption of a causal theory of viscosity are explored. Causality is introduced into the theory by letting the coefficient of viscosity go to zero as the flow velocity approaches a designated propagation speed for viscous signals. Consideration is given to a model of viscosity which has a finite propagation speed of shear information, and it is shown that it produces two kinds of shear shock. A 'pure shear shock' corresponds to a transition from a superviscous to a subviscous state with no discontinuity in the velocity. A 'mixed shear shock' has a shear transition occurring at the same location as a normal adiabatic or radiative shock. A generalized version of the Rankine-Hugoniot conditions for mixed shear shocks is derived, and self-consistent numerical solutions to a model 2D problem in which an axisymmetric radially infalling stream encounters a spinning star are presented.

Whistler mode waves observed by MGF search coil magnetometer -Polarization and wave normal features of upstream waves near the bow-shock

NASA Astrophysics Data System (ADS)

Hayashi, K.; Matsui, H.; Kawano, H.; Yamamoto, T.; Kokubun, S.

1994-12-01

Whistler mode waves observed in the upstream region very close to the bow-shock is focused from the initial survey for magnetic fed data in a frequency range between 1Hz and 50Hz observed by the search coil magnetometer on board the Geotail satellite. Based on the three component wave form data polarization and wave-normal characteristics of foreshock waves is first shown as dynamic spectra for the whole Fourier components of the 50 Hz band width. Intense whistler mode waves generated in the foot region of the bow-shock are found strongly controlled in the observed polarization dependent on the angle between directions of the wave propagation and the solar wind flow but not very dependent on frequency. Our simple scheme to derive the ware characteristics which is effective to survey large amount of data continuously growing is also introduced.

Shock absorption ability of laminate mouth guards in two different malocclusions using fiber Bragg grating (FBG) sensor.

PubMed

Bhalla, Ashish; Grewal, Navneet; Tiwari, Umesh; Mishra, Vandana; Mehla, Nahar Singh; Raviprakash, Suryanarain; Kapur, Pawan

2013-06-01

The majority of orofacial injuries affect the upper jaw, with the maxillary incisors being most prone to injury, often accounting for as many as 80% of all cases. Children with malocclusion in the anterior segment of the maxilla are more prone to traumatic injuries than those exhibiting normal occlusion, because most often the damaging force impacts directly against the maxillary anterior teeth. Hence, because of the difference of dissipation of the impact force because of the presence or absence of malocclusion, the mouthguard's shock absorption capacity would be influenced by certain factors. In the present study, a unique in vitro experiment utilizing fiber Bragg Grating (FBG) as distributed strain sensors was carried out to evaluate the shock absorption ability of laminate customized mouthguards in two different malocclusions compared with normal occlusion. The impact was produced using a customized pendulum device with three interchangeable impact objects on typhodont models with two different malocclusions and normal occlusion from different heights. Response of gratings was monitored using an optical spectrum analyzer. Strain induced because each impact was determined from the Bragg's wavelength shifts for each grating. For every model, 12 impact strikes were measured using three different impact objects on the two specified sites by releasing the object from two different heights. The laminated mouthguards showed significant variation in shock absorption ability when different malocclusions were compared. Hence, modifications in the original design of the laminated mouthguards should be considered for athletic competitors with malocclusion to provide adequate protection against impact. FBG sensor has shown the unique advantage of high sensitivity to strain measurement and can be used in further studies. The height of the impact is an important variable in determining the shock absorption ability of mouthguards. © 2012 John Wiley & Sons A/S.

Measurement of the potential drop across the earth's collisionless bow shock

NASA Technical Reports Server (NTRS)

Formisano, V.

1982-01-01

The normal component of the dc electric field measured on ISEE-1 ordinarily exhibits an enhancement of a few mV/m over both upstream and downstream values at the earth's bow shock. Using the measured relative velocity between the shock and the spacecraft (from the ISEE-1/2 time delay in the magnetometer data), it is possible to transform the observed E enhancement to a potential drop (delta phi). For a subcritical shock the potential drop is found to be very close to the measured change of particle kinetic energy (delta phi, approximately 280 V on day 330, 1977), whereas for a supercritical shock the potential drop is only a fraction of the measured change of kinetic energy (delta phi, approximately 140 V on day 324, 1977).

Head-on collision of normal shock waves with rigid porous materials

NASA Astrophysics Data System (ADS)

Levy, A.; Ben-Dor, G.; Skews, B. W.; Sorek, S.

1993-08-01

The head-on collision of a planar shock wave with a rigid porous material has been investigated experimentally in a 75 mm × 75 mm shock tube. The experimental study indicated that unlike the reflection from a flexible porous material (e.g., polyurethane foam) where the transmitted compression waves do not converge to a sharp shock wave, in the case of a rigid porous material (e.g., alumina) the transmitted compression waves do converge to a sharp shock wave, which decays as it propagates along the porous material. In addition to this major difference, many other differences were observed. They are outlined in the following sections. Based on these observations a suggestion modifying the phenomenology of the reflection/interaction process in the case a porous material with large permeability is proposed.

Transient hot-film sensor response in a shock tube

NASA Technical Reports Server (NTRS)

Roberts, A. S., Jr.; Ortgies, K. R.; Gartenberg, E.

1989-01-01

Shock tube experiments were performed to determine the response of a hot-film sensor, mounted flush on the side wall of a shock tube, to unsteady flow behind a normal shock wave. The present experiments attempt to isolate the response of the anemometer due only to the change in convective heat transfer at the hot-film surface. The experiments, performed at low supersonic shock speeds in air, are described along with the data acquisition procedure. The change in convective heat transfer is deduced from the data and the results are compared with those from transient boundary layer theory and another set of experimental results. Finally, a transient local heat transfer coefficient is formulated for use as the forcing function in a hot-film sensor instrument model simulation.

A Theory and Experiments for Detecting Shock Locations

NASA Technical Reports Server (NTRS)

Hariharan, S. I.; Johnson, D. K.; Adamovsky, G.

1994-01-01

In this paper we present a simplified one-dimensional theory for predicting locations of normal shocks in a converging diverging nozzle. The theory assumes that the flow is quasi one-dimensional and the flow is accelerated in the throat area. Optical aspects of the model consider propagation of electromagnetic fields transverse to the shock front. The theory consists of an inverse problem in which from the measured intensity it reconstructs an index of refraction profile for the shock. From this profile and the Dale-Gladstone relation, the density in the flow field is determined, thus determining the shock location. Experiments show agreement with the theory. In particular the location is determined within 10 percent of accuracy. Both the theoretical as well as the experimental results are presented to validate the procedures in this work.

Magnetic field studies of the solar wind interaction with venus from the galileo flyby.

PubMed

Kivelson, M G; Kennel, C F; McPherron, R L; Russell, C T; Southwood, D J; Walker, R J; Hammond, C M; Khurana, K K; Strangeway, R J; Coleman, P J

1991-09-27

During the 10 February 1990 flyby of Venus, the Galileo spacecraft skimmed the downstream flank of the planetary bow shock. This provided an opportunity to examine both the global and the local structure of the shock in an interval during which conditions in the solar wind plasma were quite steady. The data show that the cross section of the shock in planes transverse to the flow is smaller in directions aligned with the projection of the interplanetary magnetic field than in directions not so aligned. Ultralow-frequency waves were present in the unshocked solar wind, and their amplitude peaked when the spacecraft was downstream of the foreshock. At large distances down the tail, the Mach number of the flow normal to the shock is low, thus providing the opportunity to study repeated crossings of the collisionless shock in an interesting parameter regime. Some of the shock crossings reveal structure that comes close to the theoretically predicted form of intermediate shocks, whose existence in collisionless plasmas has not been confirmed.

Thermotolerant desert lizards characteristically differ in terms of heat-shock system regulation.

PubMed

Zatsepina, O G; Ulmasov, K A; Beresten, S F; Molodtsov, V B; Rybtsov, S A; Evgen'ev, M B

2000-03-01

We compare the properties and activation of heat-shock transcription factor (HSF1) and the synthesis of a major family of heat-shock proteins (HSP70) in lizard species inhabiting ecological niches with strikingly different thermal parameters. Under normal non-heat-shock conditions, all desert-dwelling lizard species studied so far differ from a northern, non-desert species (Lacerta vivipara) in the electrophoretic mobility and content of proteins constitutively bound to the regulatory heat-shock elements in the heat-shock gene promoter. Under these conditions, levels of activated HSF1 and of both HSP70 mRNA and protein are higher in the desert species than in the non-desert species. Upon heat shock, HSF1 aggregates in all species studied, although in desert species HSF1 subsequently disaggregates more rapidly. Cells of the northern species have a lower thermal threshold for HSP expression than those of the desert species, which correlates with the relatively low constitutive level of HSPs and high basal content of HSF1 in their cells.

The adiabatic energy change of plasma electrons and the frame dependence of the cross-shock potential at collisionless magnetosonic shock waves

NASA Technical Reports Server (NTRS)

Goodrich, C. C.; Scudder, J. D.

1984-01-01

The adiabatic energy gain of electrons in the stationary electric and magnetic field structure of collisionless shock waves was examined analytically in reference to conditions of the earth's bow shock. The study was performed to characterize the behavior of electrons interacting with the cross-shock potential. A normal incidence frame (NIF) was adopted in order to calculate the reversible energy change across a time stationary shock, and comparisons were made with predictions made by the de Hoffman-Teller (HT) model (1950). The electron energy gain, about 20-50 eV, is demonstrated to be consistent with a 200-500 eV potential jump in the bow shock quasi-perpendicular geometry. The electrons lose energy working against the solar wind motional electric field. The reversible energy process is close to that modeled by HT, which predicts that the motional electric field vanishes and the electron energy gain from the electric potential is equated to the ion energy loss to the potential.

Shock Radiation Tests for Saturn and Uranus Entry Probes

NASA Technical Reports Server (NTRS)

Cruden, Brett A.; Bogdanoff, David W.

2014-01-01

This paper describes a test series in the Electric Arc Shock Tube at NASA Ames Research Center with the objective of quantifying shock-layer radiative heating magnitudes for future probe entries into Saturn and Uranus atmospheres. Normal shock waves are measured in Hydrogen/Helium mixtures (89:11 by mole) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 km/s. No shock layer radiation is detected below 25 km/s, a finding consistent with predictions for Uranus entries. Between 25-30 km/s, radiance is quantified from the Vacuum Ultraviolet through Near Infrared, with focus on the Lyman-alpha and Balmer series lines of Hydrogen. Shock profiles are analyzed for electron number density and electronic state distribution. The shocks do not equilibrate over several cm, and distributions are demonstrated to be non-Boltzmann. Radiation data are compared to simulations of Decadal survey entries for Saturn and shown to be significantly lower than predicted with the Boltzmann radiation model.

Magnetic field studies of the solar wind interaction with Venus from the Galileo flyby

NASA Technical Reports Server (NTRS)

Kivelson, M. G.; Kennel, C. F.; Mcpherron, R. L.; Russell, C. T.; Southwood, D. J.; Walker, R. J.; Hammond, C. M.; Khurana, K. K.; Strangeway, R. J.; Coleman, P. J.

1991-01-01

During the February 10, 1990 flyby of Venus, the Galileo spacecraft skimmed the downnstream flank of the planetary bow shock. This provided an opportunity to examine both the global and the local structure of the shock in an interval during which conditions in the solar wind plasma were quite steady. The data show that the cross section of the shock in planes transverse to the flow is smaller in directions aligned with the projection of the interplanetary magnetic field than in directions not so aligned. Ultralow-frequency waves were present in the unshocked solar wind, and their amplitude peaked when the spacecraft was downstream of the foreshock. At large distances down the tail, the Mach number of the flow normal to the shock is low, thus providing the opportunity to study repeated crossings of the collisionless shock in an interesting parameter regime. Some of the shock crossings reveal structure that comes close to the theoretically predicted form of intermediate shocks, whose existence in collisionless plasmas has not been confirmed.

Schistosoma mansoni miracidia transformed by particle bombardment infect Biomphalaria glabrata snails and develop into transgenic sporocysts.

PubMed

Heyers, Oliver; Walduck, Anna K; Brindley, Paul J; Bleiss, Wilfrid; Lucius, Richard; Dorbic, Tomislav; Wittig, Burghardt; Kalinna, Bernd H

2003-10-01

Miracidia (and adults) of Schistosoma mansoni which had been subjected to particle bombardment with a plasmid DNA encoding enhanced green fluorescent protein (EGFP) under control of the S. mansoni heat shock protein 70 (HSP70) promoter and termination elements were shown to express the reporter gene. Bombarded miracidia were able to penetrate and establish in Biomphalaria glabrata the intermediate host snail. Gold particles could be detected in the germ balls of parasites in paraffin-sections of snail tissue. The bombarded miracidia were able to develop normally and to transform into mother sporocysts. Reporter gene activity could be determined at 10 days post-infection by RT-PCR in snail tissues, but not by microscopy or Western blot which probably reflected sub-optimal expression levels of constructs. Our findings indicated that it is feasible to return transgenic miracidia to the life cycle, a crucial step for the establishment of a transgenesis system for schistosomes.

A Retrospective Evaluation of Echocardiograms to Establish Normative Inferior Vena Cava and Aortic Measurements for Children Younger Than 6 Years.

PubMed

Stenson, Erin K; Punn, Rajesh; Ramsi, Musaab; Kache, Saraswati

2018-02-26

The ability to plot the inferior vena cava (IVC) size on a normal curve for pediatric patients may prove beneficial. First, in patients with normal cardiac anatomy who present in shock, assessing IVC size may be valuable for evaluating the degree of dehydration. Second, in children with heart disease, understanding how a child's IVC size compares to normal could be particularly beneficial for patients with right heart disease. We sought to create normal curves for the IVC and aorta in children younger than 6 years. Data were gathered from 347 echocardiograms of healthy children younger than 6 years in a retrospective study at a quaternary care children's hospital. From the subcostal long- and short-axis images, maximum diameters in the transverse and longitudinal views were obtained for both the IVC and the aorta. Both IVC and aortic dimensions increased in a linear fashion and had excellent correlations with the body surface area, body mass, and height (IVC, r = 0.78-0.81; P < .0001; aorta, r = 0.82-0.86; P < .0001). In children younger than 6 years, the IVC and aorta increase linearly as the children grow. Such normal curves will be beneficial for assessing a pediatric patient's hydration status or right heart function in patients with congenital heart disease. © 2018 by the American Institute of Ultrasound in Medicine.

Shock-wave structure based on the Navier-Stokes-Fourier equations.

PubMed

Uribe, F J; Velasco, R M

2018-04-01

We use the Navier-Stokes-Fourier constitutive equations to study plane shock waves in dilute gases. It is shown that the experimental information on the normalized density profiles can be fit by using the so-called soft sphere model, in which the viscosity and thermal conductivity are proportional to a power of the temperature.

Shock-wave structure based on the Navier-Stokes-Fourier equations

NASA Astrophysics Data System (ADS)

Uribe, F. J.; Velasco, R. M.

2018-04-01

We use the Navier-Stokes-Fourier constitutive equations to study plane shock waves in dilute gases. It is shown that the experimental information on the normalized density profiles can be fit by using the so-called soft sphere model, in which the viscosity and thermal conductivity are proportional to a power of the temperature.

Neonatal Odor-Shock Conditioning Alters the Neural Network Involved in Odor Fear Learning at Adulthood

ERIC Educational Resources Information Center

Sevelinges, Yannick; Sullivan, Regina M.; Messaoudi, Belkacem; Mouly, Anne-Marie

2008-01-01

Adult learning and memory functions are strongly dependent on neonatal experiences. We recently showed that neonatal odor-shock learning attenuates later life odor fear conditioning and amygdala activity. In the present work we investigated whether changes observed in adults can also be observed in other structures normally involved, namely…

Intra-Amygdala Muscimol Injections Impair Freezing and Place Avoidance in Aversive Contextual Conditioning

ERIC Educational Resources Information Center

Holahan, Matthew R.; White, Norman M.

2004-01-01

Rats were trained by shocking them in a closed compartment. When subsequently tested in the same closed compartment with no shock, normal rats showed an increased tendency to freeze. They also showed an increased tendency to actively avoid the compartment when given access to an adjacent neutral compartment for the first time. Amygdala…

Plasma first resuscitation reduces lactate acidosis, enhances redox homeostasis, amino acid and purine catabolism in a rat model of profound hemorrhagic shock

PubMed Central

D’Alessandro, Angelo; Moore, Hunter B; Moore, Ernest E; Wither, Matthew J.; Nemkov, Travis; Morton, Alexander P; Gonzalez, Eduardo; Chapman, Michael P; Fragoso, Miguel; Slaughter, Anne; Sauaia, Angela; Silliman, Christopher C; Hansen, Kirk C; Banerjee, Anirban

2016-01-01

The use of aggressive crystalloid resuscitation to treat hypoxemia, hypovolemia and nutrient deprivation promoted by massive blood loss may lead to the development of the blood vicious cycle of acidosis, hypothermia, and coagulopathy and, utterly, death. Metabolic acidosis is one of the many metabolic derangements triggered by severe trauma/hemorrhagic shock, also including enhanced proteolysis, lipid mobilization, as well as traumatic diabetes. Appreciation of the metabolic benefit of plasma first resuscitation is an important concept. Plasma resuscitation has been shown to correct hyperfibrinolysis secondary to severe hemorrhage better than normal saline. Here we hypothesize that plasma first resuscitation corrects metabolic derangements promoted by severe hemorrhage better than resuscitation with normal saline. Ultra-high-performance liquid chromatography-mass spectrometry-based metabolomics analyses were performed to screen plasma metabolic profiles upon shock and resuscitation with either platelet-free plasma or normal saline in a rat model of severe hemorrhage. Of the 251 metabolites that were monitored, 101 were significantly different in plasma vs normal saline resuscitated rats. Plasma resuscitation corrected lactate acidosis by promoting glutamine/amino acid catabolism and purine salvage reactions. Plasma first resuscitation may benefit critically injured trauma patients by relieving the lactate burden and promoting other non-clinically measured metabolic changes. In the light of our results, we propose that plasma resuscitation may promote fueling of mitochondrial metabolism, through the enhancement of glutaminolysis/amino acid catabolism and purine salvage reactions. The treatment of trauma patients in hemorrhagic shock with plasma first resuscitation is likely not only to improve coagulation, but also to promote substrate-specific metabolic corrections. PMID:26863033

Extracorporeal shock waves enhance normal fibroblast proliferation in vitro and activate mRNA expression for TGF-beta1 and for collagen types I and III.

PubMed

Berta, Laura; Fazzari, Annamaria; Ficco, Anna Maria; Enrica, Patrizia Maurici; Catalano, Maria Graziella; Frairia, Roberto

2009-10-01

Extracorporeal shock waves (ESWs) are used to good effect in the treatment of soft tissue injuries, but the underlying mechanisms are still unknown. We therefore determined the effects of ESWs on normal fibroblasts in vitro, in order to assess treatment-induced cell response. A normal human fibroblast cell line (NHDF-12519) was treated with ESWs generated by a piezoelectric device (Piezoson 100; Richard Wolfe) using different protocols of impulses (300, 1,000, or 2,000 shots) and energy (0.11 or 0.22 mJ/mm(2)). Untreated controls and treated cells were cultivated for 12 days following a single shock-wave treatment. Viability, growth rate, and expression of mRNA for TGFbeta-1 and collagen types I and III were evaluated at days 3, 6, 9, and 12. 1 hour after shock-wave treatment, cell viability showed a decrease related mainly to impulse numbers applied. Fibroblasts treated with energy of 0.22 mJ/mm(2) subsequently showed an increase in proliferation from day 6 to day 9 that was higher than in untreated controls, without interference with the normal cell kinetic profile. mRNA expression was also higher in treated fibroblasts than in untreated controls for TGFbeta-1 on day 6 and day 9, for collagen type I on day 6, and for collagen type III on day 9. These in vitro data confirm that the main factors involved in the repair process of connective tissues are activated by ESWs. The study gives the rationale for, and may provide schedules for, ESW treatment of tendonopathies.

MMS Observations and Hybrid Simulations of Surface Ripples at a Marginally Quasi-Parallel Shock

NASA Astrophysics Data System (ADS)

Gingell, Imogen; Schwartz, Steven J.; Burgess, David; Johlander, Andreas; Russell, Christopher T.; Burch, James L.; Ergun, Robert E.; Fuselier, Stephen; Gershman, Daniel J.; Giles, Barbara L.; Goodrich, Katherine A.; Khotyaintsev, Yuri V.; Lavraud, Benoit; Lindqvist, Per-Arne; Strangeway, Robert J.; Trattner, Karlheinz; Torbert, Roy B.; Wei, Hanying; Wilder, Frederick

2017-11-01

Simulations and observations of collisionless shocks have shown that deviations of the nominal local shock normal orientation, that is, surface waves or ripples, are expected to propagate in the ramp and overshoot of quasi-perpendicular shocks. Here we identify signatures of a surface ripple propagating during a crossing of Earth's marginally quasi-parallel (θBn˜45∘) or quasi-parallel bow shock on 27 November 2015 06:01:44 UTC by the Magnetospheric Multiscale (MMS) mission and determine the ripple's properties using multispacecraft methods. Using two-dimensional hybrid simulations, we confirm that surface ripples are a feature of marginally quasi-parallel and quasi-parallel shocks under the observed solar wind conditions. In addition, since these marginally quasi-parallel and quasi-parallel shocks are expected to undergo a cyclic reformation of the shock front, we discuss the impact of multiple sources of nonstationarity on shock structure. Importantly, ripples are shown to be transient phenomena, developing faster than an ion gyroperiod and only during the period of the reformation cycle when a newly developed shock ramp is unaffected by turbulence in the foot. We conclude that the change in properties of the ripple observed by MMS is consistent with the reformation of the shock front over a time scale of an ion gyroperiod.

Hugoniot and refractive indices of bromoform under shock compression

NASA Astrophysics Data System (ADS)

Liu, Q. C.; Zeng, X. L.; Zhou, X. M.; Luo, S. N.

2018-01-01

We investigate physical properties of bromoform (liquid CHBr3) including compressibility and refractive index under dynamic extreme conditions of shock compression. Planar shock experiments are conducted along with high-speed laser interferometry. Our experiments and previous results establish a linear shock velocity-particle velocity relation for particle velocities below 1.77 km/s, as well as the Hugoniot and isentropic compression curves up to ˜21 GPa. Shock-state refractive indices of CHBr3 up to 2.3 GPa or ˜26% compression, as a function of density, can be described with a linear relation and follows the Gladstone-Dale relation. The velocity corrections for laser interferometry measurements at 1550 nm are also obtained.

Shock Radiation Tests for Saturn and Uranus Entry Probes

NASA Technical Reports Server (NTRS)

Cruden, Brett A.; Bogdanoff, David W.

2017-01-01

This paper describes a test series in the Electric Arc Shock Tube at NASA Ames Research Center with the objective of quantifying shock-layer radiative heating magnitudes for future probe entries into Saturn and Uranus atmospheres. Normal shock waves are measured in Hydrogen-Helium mixtures (89:11 by volume) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 kms. No shock layer radiation is detected within measurement limits below 25 kms, a finding consistent with predictions for Uranus entries. Between 25-30 kms, radiance is quantified from the Vacuum Ultraviolet through Near Infrared, with focus on the Lyman-a and Balmer series lines of Hydrogen. Shock profiles are analyzed for electron number density and electronic state distribution. The shocks do not equilibrate over several cm, and in many cases the state distributions are non-Boltzmann. Radiation data are compared to simulations of Decadal Survey entries for Saturn and shown to be as much as 8x lower than predicted with the Boltzmann radiation model. Radiance is observed in front of the shock layer, the characteristics of which match the expected diffusion length.

Shock-driven transition to turbulence: Emergence of power-law scaling

DOE PAGES

Olmstead, D.; Wayne, P.; Simons, D.; ...

2017-05-25

Here, we consider two cases of interaction between a planar shock and a cylindrical density interface. In the first case (planar normal shock), the axis of the gas cylinder is parallel to the shock front and baroclinic vorticity deposited by the shock is predominantly two dimensional (directed along the axis of the cylinder). In the second case, the cylinder is tilted, resulting in an oblique shock interaction and a fully-three-dimensional shock-induced vorticity field. Furthermore, the statistical properties of the flow for both cases are analyzed based on images from two orthogonal visualization planes, using structure functions of the intensity mapsmore » of fluorescent tracer premixed with heavy gas. And at later times, these structure functions exhibit power-law-like behavior over a considerable range of scales. Manifestation of this behavior is remarkably consistent in terms of dimensionless time τ defined based on Richtmyer's linear theory within the range of Mach numbers from 1.1 to 2.0 and the range of gas cylinder tilt angles with respect to the plane of the shock front (0–30°).« less

A bulk viscosity approach for shock capturing on unstructured grids

NASA Astrophysics Data System (ADS)

Shoeybi, Mohammad; Larsson, Nils Johan; Ham, Frank; Moin, Parviz

2008-11-01

The bulk viscosity approach for shock capturing (Cook and Cabot, JCP, 2005) augments the bulk part of the viscous stress tensor. The intention is to capture shock waves without dissipating turbulent structures. The present work extends and modifies this method for unstructured grids. We propose a method that properly scales the bulk viscosity with the grid spacing normal to the shock for unstructured grid for which the shock is not necessarily aligned with the grid. The magnitude of the strain rate tensor used in the original formulation is replaced with the dilatation, which appears to be more appropriate in the vortical turbulent flow regions (Mani et al., 2008). The original form of the model is found to have an impact on dilatational motions away form the shock wave, which is eliminated by a proposed localization of the bulk viscosity. Finally, to allow for grid adaptation around shock waves, an explicit/implicit time advancement scheme has been developed that adaptively identifies the stiff regions. The full method has been verified with several test cases, including 2D shock-vorticity entropy interaction, homogenous isotropic turbulence, and turbulent flow over a cylinder.

Used fuel rail shock and vibration testing options analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Steven B.; Best, Ralph E.; Klymyshyn, Nicholas A.

2014-09-25

The objective of the rail shock and vibration tests is to complete the framework needed to quantify loads of fuel assembly components that are necessary to guide materials research and establish a technical basis for review organizations such as the U.S. Nuclear Regulatory Commission (NRC). A significant body of experimental and numerical modeling data exists to quantify loads and failure limits applicable to normal conditions of transport (NCT) rail transport, but the data are based on assumptions that can only be verified through experimental testing. The test options presented in this report represent possible paths for acquiring the data thatmore » are needed to confirm the assumptions of previous work, validate modeling methods that will be needed for evaluating transported fuel on a case-by-case basis, and inform material test campaigns on the anticipated range of fuel loading. The ultimate goal of this testing is to close all of the existing knowledge gaps related to the loading of used fuel under NCT conditions and inform the experiments and analysis program on specific endpoints for their research. The options include tests that would use an actual railcar, surrogate assemblies, and real or simulated rail transportation casks. The railcar carrying the cradle, cask, and surrogate fuel assembly payload would be moved in a train operating over rail track modified or selected to impart shock and vibration forces that occur during normal rail transportation. Computer modeling would be used to help design surrogates that may be needed for a rail cask, a cask’s internal basket, and a transport cradle. The objective of the design of surrogate components would be to provide a test platform that effectively simulates responses to rail shock and vibration loads that would be exhibited by state-of-the-art rail cask, basket, and/or cradle structures. The computer models would also be used to help determine the placement of instrumentation (accelerometers and strain gauges) on the surrogate fuel assemblies, cask and cradle structures, and the railcar so that forces and deflections that would result in the greatest potential for damage to high burnup and long-cooled UNF can be determined. For purposes of this report we consider testing on controlled track when we have control of the track and speed to facilitate modeling.« less

Revisiting Shock Initiation Modeling of Homogeneous Explosives

NASA Astrophysics Data System (ADS)

Partom, Yehuda

2013-04-01

Shock initiation of homogeneous explosives has been a subject of research since the 1960s, with neat and sensitized nitromethane as the main materials for experiments. A shock initiation model of homogeneous explosives was established in the early 1960s. It involves a thermal explosion event at the shock entrance boundary, which develops into a superdetonation that overtakes the initial shock. In recent years, Sheffield and his group, using accurate experimental tools, were able to observe details of buildup of the superdetonation. There are many papers on modeling shock initiation of heterogeneous explosives, but there are only a few papers on modeling shock initiation of homogeneous explosives. In this article, bulk reaction reactive flow equations are used to model homogeneous shock initiation in an attempt to reproduce experimental data of Sheffield and his group. It was possible to reproduce the main features of the shock initiation process, including thermal explosion, superdetonation, input shock overtake, overdriven detonation after overtake, and the beginning of decay toward Chapman-Jouget (CJ) detonation. The time to overtake (TTO) as function of input pressure was also calculated and compared to the experimental TTO.

Plasmapheresis in severe septic shock with disseminated intravascular coagulation.

PubMed

Zilow, E P; Selle, B; Zilow, G

1994-01-01

An 18-year-old female with CNS relapse of acute lymphoblastic leukemia after previous complete remission of the disease underwent chemotherapy. Due to the therapy she suffered from profound suppression of bone marrow with consecutive thrombocytopenia and leukopenia. Despite prophylactic treatment, severe septicemia occurred with septic shock, hemolysis and disseminated intravascular coagulation (DIC). As the clinical course became uncontrollable by means of conventional therapy, including broad-spectrum antibiotics, substitution of fresh frozen plasma, antithrombin III and heparin therapy, plasma exchange was used as a rescue therapy. This method succeeded in effective replacement of clotting factors and normalization of coagulation, in removal of fibrinogen degradation products and probably of toxins and shock mediators. The patient recovered from shock.

Modeling shock responses of plastic bonded explosives using material point method

NASA Astrophysics Data System (ADS)

Shang, Hailin; Zhao, Feng; Fu, Hua

2017-01-01

Shock responses of plastic bonded explosives are modeled using material point method as implemented in the Uintah Computational Framework. Two-dimensional simulation model was established based on the micrograph of PBX9501. Shock loading for the explosive was performed by a piston moving at a constant velocity. Unreactive simulation results indicate that under shock loading serious plastic strain appears on the boundary of HMX grains. Simultaneously, the plastic strain energy transforms to thermal energy, causing the temperature to rise rapidly on grain boundary areas. The influence of shock strength on the responses of explosive was also investigated by increasing the piston velocity. And the results show that with increasing shock strength, the distribution of plastic strain and temperature does not have significant changes, but their values increase obviously. Namely, the higher the shock strength is, the higher the temperature rise will be.

Chemical Enhancements in Shock-Accelerated Particles: Ab initio Simulations.

PubMed

Caprioli, Damiano; Yi, Dennis T; Spitkovsky, Anatoly

2017-10-27

We study the thermalization, injection, and acceleration of ions with different mass/charge ratios, A/Z, in nonrelativistic collisionless shocks via hybrid (kinetic ions-fluid electrons) simulations. In general, ions thermalize to a postshock temperature proportional to A. When diffusive shock acceleration is efficient, ions develop a nonthermal tail whose extent scales with Z and whose normalization is enhanced as (A/Z)^{2} so that incompletely ionized heavy ions are preferentially accelerated. We discuss how these findings can explain observed heavy-ion enhancements in Galactic cosmic rays.

Existence and Stability of Viscoelastic Shock Profiles

NASA Astrophysics Data System (ADS)

Barker, Blake; Lewicka, Marta; Zumbrun, Kevin

2011-05-01

We investigate existence and stability of viscoelastic shock profiles for a class of planar models including the incompressible shear case studied by Antman and Malek-Madani. We establish that the resulting equations fall into the class of symmetrizable hyperbolic-parabolic systems, hence spectral stability implies linearized and nonlinear stability with sharp rates of decay. The new contributions are treatment of the compressible case, formulation of a rigorous nonlinear stability theory, including verification of stability of small-amplitude Lax shocks, and the systematic incorporation in our investigations of numerical Evans function computations determining stability of large-amplitude and nonclassical type shock profiles.

Shock-Strength Determination With Seeded and Seedless Laser Methods

NASA Technical Reports Server (NTRS)

Herring, G. C.; Meyers, James F.

2008-01-01

Two nonintrusive laser diagnostics were independently used to demonstrate the measurement of time-averaged and spatially-resolved pressure change across a twodimensional (2-D) shock wave. The first method is Doppler global velocimetry (DGV) which uses water seeding and generates 2-D maps of 3-orthogonal components of velocity. A DGV-measured change in flow direction behind an oblique shock provides an indirect determination of pressure jump across the shock, when used with the known incoming Mach number and ideal shock relations (or Prandtl-Meyer flow equations for an expansion fan). This approach was demonstrated at Mach 2 on 2-D shocks and expansions generated from a flat plate at angles-of-attack approx. equals -2.4deg and +0.6deg, respectively. This technique also works for temperature jump (as well as pressure) and for normal shocks (as well as oblique). The second method, laser-induced thermal acoustics (LITA), is a seedless approach that was used to generate 1-D spatial profiles of streamwise Mach number, sound speed, pressure, and temperature across the same shock waves. Excellent agreement was obtained between the DGV and LITA methods, suggesting that either technique is viable for noninvasive shock-strength measurements.

Impact of Shock Front Rippling and Self-reformation on the Electron Dynamics at Low-Mach-number Shocks

NASA Astrophysics Data System (ADS)

Yang, Zhongwei; Lu, Quanming; Liu, Ying D.; Wang, Rui

2018-04-01

Electron dynamics at low-Mach-number collisionless shocks are investigated by using two-dimensional electromagnetic particle-in-cell simulations with various shock normal angles. We found: (1) The reflected ions and incident electrons at the shock front provide an effective mechanism for the quasi-electrostatic wave generation due to the charge-separation. A fraction of incident electrons can be effectively trapped and accelerated at the leading edge of the shock foot. (2) At quasi-perpendicular shocks, the electron trapping and reflection is nonuniform due to the shock rippling along the shock surface and is more likely to take place at some locations accompanied by intense reflected ion-beams. The electron trapping process has a periodical evolution over time due to the shock front self-reformation, which is controlled by ion dynamics. Thus, this is a cross-scale coupling phenomenon. (3) At quasi-parallel shocks, reflected ions can travel far back upstream. Consequently, quasi-electrostatic waves can be excited in the shock transition and the foreshock region. The electron trajectory analysis shows these waves can trap electrons at the foot region and reflect a fraction of them far back upstream. Simulation runs in this paper indicate that the micro-turbulence at the shock foot can provide a possible scenario for producing the reflected electron beam, which is a basic condition for the type II radio burst emission at low-Mach-number interplanetary shocks driven by Coronal Mass Ejections (CMEs).

Monte Carlo simulations of particle acceleration at oblique shocks

NASA Technical Reports Server (NTRS)

Baring, Matthew G.; Ellison, Donald C.; Jones, Frank C.

1994-01-01

The Fermi shock acceleration mechanism may be responsible for the production of high-energy cosmic rays in a wide variety of environments. Modeling of this phenomenon has largely focused on plane-parallel shocks, and one of the most promising techniques for its study is the Monte Carlo simulation of particle transport in shocked fluid flows. One of the principal problems in shock acceleration theory is the mechanism and efficiency of injection of particles from the thermal gas into the accelerated population. The Monte Carlo technique is ideally suited to addressing the injection problem directly, and previous applications of it to the quasi-parallel Earth bow shock led to very successful modeling of proton and heavy ion spectra, as well as other observed quantities. Recently this technique has been extended to oblique shock geometries, in which the upstream magnetic field makes a significant angle Theta(sub B1) to the shock normal. Spectral resutls from test particle Monte Carlo simulations of cosmic-ray acceleration at oblique, nonrelativistic shocks are presented. The results show that low Mach number shocks have injection efficiencies that are relatively insensitive to (though not independent of) the shock obliquity, but that there is a dramatic drop in efficiency for shocks of Mach number 30 or more as the obliquity increases above 15 deg. Cosmic-ray distributions just upstream of the shock reveal prominent bumps at energies below the thermal peak; these disappear far upstream but might be observable features close to astrophysical shocks.

Measurements of the Shock Release Of Quartz and Paralyene-N

NASA Astrophysics Data System (ADS)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2017-06-01

The shock and release properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies single shock or multiple shock conditions. The challenge with measuring release properties is unlike shocks which have a single interface from which to measure the properties, the release establishes gradients in the sample. The streaked x-ray imaging capability of the NIKE laser allow the interface between quartz and CH to be measured during the release, giving measurements of the interface velocity and CH density. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography Work supported by DOE/NNSA.

Velocity lag of solid particles in oscillating gases and in gases passing through normal shock waves

NASA Technical Reports Server (NTRS)

Maxwell, B. R.; Seasholtz, R. G.

1974-01-01

The velocity lag of micrometer size spherical particles is theoretically determined for gas particle mixtures passing through a stationary normal shock wave and also for particles embedded in an oscillating gas flow. The particle sizes and densities chosen are those considered important for laser Doppler velocimeter applications. The governing equations for each flow system are formulated. The deviation from Stokes flow caused by inertial, compressibility, and rarefaction effects is accounted for in both flow systems by use of an empirical drag coefficient. Graphical results are presented which characterize particle tracking as a function of system parameters.

A Study of Normal Shock-Wave Turbulent Boundary-Layer Interactions at Mach Numbers of 1.3, 1.4 and 1.5.

DTIC Science & Technology

1982-10-01

Veigas 13used a third technique which was to hold the normal shock wave steady in a supersonic tube by the adjustment of a conical choke downstream of...the equilibrium functioii E (equation (3) as tie eqoi ihri:’ fl -it I lows of East, Sawyer and Nash 2 8 . Although the maximum values of ti wakce :, i...f.. ..l.. .. .. ..t.. fl iC!alaCC CCCCCCCCt t CCCCCifllt CCCCCCCCit C C--- ---- -- C A CCC5C tCC C NC C - f CC1S $ C C A * E~ - - C 2

Atmospheric effects on inlets for supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Cole, G. L.

1977-01-01

Mixed-compression inlet dynamic behavior in the vicinity of unstart, was simulated and analyzed to investigate time response of an inlet's normal shock to independent disturbances in ambient temperature and pressure and relative velocity (longitudinal gust), with and without inlet controls active. The results indicate that atmospheric disturbances may be more important than internal disturbances in setting inlet controls requirements because they are usually not anticipated and because normal shock response to rapid atmospheric disturbances is not attenuated by the inlet, as it is for engine induced disturbances. However, before inlet control requirements can be fully assessed, more statistics on extreme atmospheric disturbances are needed.

Real-gas effects associated with one-dimensional transonic flow of cryogenic nitrogen

NASA Technical Reports Server (NTRS)

Adcock, J. B.

1976-01-01

Real gas solutions for one-dimensional isentropic and normal-shock flows of nitrogen were obtained for a wide range of temperatures and pressures. These calculations are compared to ideal gas solutions and are presented in tables. For temperatures (300 K and below) and pressures (1 to 10 atm) that cover those anticipated for transonic cryogenic tunnels, the solutions are analyzed to obtain indications of the magnitude of inviscid flow simulation errors. For these ranges, the maximum deviation of the various isentropic and normal shock parameters from the ideal values is about 1 percent or less, and for most wind tunnel investigations this deviation would be insignificant.

The 2016-2017 Central Italy Seismic Sequence: Source Complexity Inferred from Rupture Models.

NASA Astrophysics Data System (ADS)

Scognamiglio, L.; Tinti, E.; Casarotti, E.; Pucci, S.; Villani, F.; Cocco, M.; Magnoni, F.; Michelini, A.

2017-12-01

The Apennines have been struck by several seismic sequences in recent years, showing evidence of the activation of multiple segments of normal fault systems in a variable and, relatively short, time span, as in the case of the 1980 Irpinia earthquake (three shocks in 40 s), the 1997 Umbria-Marche sequence (four main shocks in 18 days) and the 2009 L'Aquila earthquake having three segments activated within a few weeks. The 2016-2017 central Apennines seismic sequence begin on August 24th with a MW 6.0 earthquake, which strike the region between Amatrice and Accumoli causing 299 fatalities. This earthquake ruptures a nearly 20 km long normal fault and shows a quite heterogeneous slip distribution. On October 26th, another main shock (MW 5.9) occurs near Visso extending the activated seismogenic area toward the NW. It is a double event rupturing contiguous patches on the fault segment of the normal fault system. Four days after the second main shock, on October 30th, a third earthquake (MW 6.5) occurs near Norcia, roughly midway between Accumoli and Visso. In this work we have inverted strong motion waveforms and GPS data to retrieve the source model of the MW 6.5 event with the aim of interpreting the rupture process in the framework of this complex sequence of moderate magnitude earthquakes. We noted that some preliminary attempts to model the slip distribution of the October 30th main shock using a single fault plane oriented along the Apennines did not provide convincing fits to the observed waveforms. In addition, the deformation pattern inferred from satellite observations suggested the activation of a multi-fault structure, that is coherent to the complexity and the extension of the geological surface deformation. We investigated the role of multi-fault ruptures and we found that this event revealed an extraordinary complexity of the rupture geometry and evolution: the coseismic rupture propagated almost simultaneously on a normal fault and on a blind fault, possibly inherited from compressional tectonics. These earthquakes raise serious concerns on our understanding of fault segmentation and seismicity evolution during sequences of normal faulting earthquakes. Finally, the retrieved rupture history has important implications on seismic hazard assessment and on the maximum expected magnitude in a given tectonic area.

Micro-Ramps for External Compression Low-Boom Inlets

NASA Technical Reports Server (NTRS)

Rybalko, Michael; Loth, Eric; Chima, Rodrick V.; Hirt, Stefanie M.; DeBonis, James R.

2010-01-01

The application of vortex generators for flow control in an external compression, axisymmetric, low-boom concept inlet was investigated using RANS simulations with three-dimensional (3-D), structured, chimera (overset) grids and the WIND-US code. The low-boom inlet design is based on previous scale model 1- by 1-ft wind tunnel tests and features a zero-angle cowl and relaxed isentropic compression centerbody spike, resulting in defocused oblique shocks and a weak terminating normal shock. Validation of the methodology was first performed for micro-ramps in supersonic flow on a flat plate with and without oblique shocks. For the inlet configuration, simulations with several types of vortex generators were conducted for positions both upstream and downstream of the terminating normal shock. The performance parameters included incompressible axisymmetric shape factor, separation area, inlet pressure recovery, and massflow ratio. The design of experiments (DOE) methodology was used to select device size and location, analyze the resulting data, and determine the optimal choice of device geometry. The optimum upstream configuration was found to substantially reduce the post-shock separation area but did not significantly impact recovery at the aerodynamic interface plane (AIP). Downstream device placement allowed for fuller boundary layer velocity profiles and reduced distortion. This resulted in an improved pressure recovery and massflow ratio at the AIP compared to the baseline solid-wall configuration.

Structure of velocity distributions in shock waves in granular gases with extension to molecular gases.

PubMed

Vilquin, A; Boudet, J F; Kellay, H

2016-08-01

Velocity distributions in normal shock waves obtained in dilute granular flows are studied. These distributions cannot be described by a simple functional shape and are believed to be bimodal. Our results show that these distributions are not strictly bimodal but a trimodal distribution is shown to be sufficient. The usual Mott-Smith bimodal description of these distributions, developed for molecular gases, and based on the coexistence of two subpopulations (a supersonic and a subsonic population) in the shock front, can be modified by adding a third subpopulation. Our experiments show that this additional population results from collisions between the supersonic and subsonic subpopulations. We propose a simple approach incorporating the role of this third intermediate population to model the measured probability distributions and apply it to granular shocks as well as shocks in molecular gases.

Atypical Particle Heating at a Supercritical Interplanetary Shock

NASA Technical Reports Server (NTRS)

Wilson, Lynn B., III

2010-01-01

We present the first observations at an interplanetary shock of large amplitude (> 100 mV/m pk-pk) solitary waves and large amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

Numerical solutions of several reflected shock-wave flow fields with nonequilibrium chemical reactions

NASA Technical Reports Server (NTRS)

Hanson, R. K.; Presley, L. L.; Williams, E. V.

1972-01-01

The method of characteristics for a chemically reacting gas is used in the construction of the time-dependent, one-dimensional flow field resulting from the normal reflection of an incident shock wave at the end wall of a shock tube. Nonequilibrium chemical reactions are allowed behind both the incident and reflected shock waves. All the solutions are evaluated for oxygen, but the results are generally representative of any inviscid, nonconducting, and nonradiating diatomic gas. The solutions clearly show that: (1) both the incident- and reflected-shock chemical relaxation times are important in governing the time to attain steady state thermodynamic properties; and (2) adjacent to the end wall, an excess-entropy layer develops wherein the steady state values of all the thermodynamic variables except pressure differ significantly from their corresponding Rankine-Hugoniot equilibrium values.

The Effect on Non-Normal Distributions on the Integrated Moving Average Model of Time-Series Analysis.

ERIC Educational Resources Information Center

Doerann-George, Judith

The Integrated Moving Average (IMA) model of time series, and the analysis of intervention effects based on it, assume random shocks which are normally distributed. To determine the robustness of the analysis to violations of this assumption, empirical sampling methods were employed. Samples were generated from three populations; normal,…

CFD application to supersonic/hypersonic inlet airframe integration. [computational fluid dynamics (CFD)

NASA Technical Reports Server (NTRS)

Benson, Thomas J.

1988-01-01

Supersonic external compression inlets are introduced, and the computational fluid dynamics (CFD) codes and tests needed to study flow associated with these inlets are outlined. Normal shock wave turbulent boundary layer interaction is discussed. Boundary layer control is considered. Glancing sidewall shock interaction is treated. The CFD validation of hypersonic inlet configurations is explained. Scramjet inlet modules are shown.

Inverse Bremsstrahlung in Shocked Astrophysical Plasmas

NASA Technical Reports Server (NTRS)

Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

2000-01-01

There has recently been interest in the role of inverse bremsstrahlung, the emission of photons by fast suprathermal ions in collisions with ambient electrons possessing relatively low velocities, in tenuous plasmas in various astrophysical contexts. This follows a long hiatus in the application of suprathermal ion bremsstrahlung to astrophysical models since the early 1970s. The potential importance of inverse bremsstrahlung relative to normal bremsstrahlung, i.e. where ions are at rest, hinges upon the underlying velocity distributions of the interacting species. In this paper, we identify the conditions under which the inverse bremsstrahlung emissivity is significant relative to that for normal bremsstrahlung in shocked astrophysical plasmas. We determine that, since both observational and theoretical evidence favors electron temperatures almost comparable to, and certainly not very deficient relative to proton temperatures in shocked plasmas, these environments generally render inverse bremsstrahlung at best a minor contributor to the overall emission. Hence inverse bremsstrahlung can be safely neglected in most models invoking shock acceleration in discrete sources such as supernova remnants. However, on scales approximately > 100 pc distant from these sources, Coulomb collisional losses can deplete the cosmic ray electrons, rendering inverse bremsstrahlung, and perhaps bremsstrahlung from knock-on electrons, possibly detectable.

Can shock waves on helicopter rotors generate noise? - A study of the quadrupole source

NASA Technical Reports Server (NTRS)

Farassat, F.; Tadghighi, H.

1990-01-01

An analysis has previously established that local shock surfaces attached to helicopter rotor blades moving at high subsonic speeds are potent noise generators; in pursuit of this insight, a novel formulation is presented for the prediction of the noise of a deformable shock, whose area changes as a function of the azimuthal position of the blade. The derivation of this formulation has its basis in a mapping of the moving shock to a time-independent region. In virtue of this mapping, the implementation of the main result on a computer becomes straightforward enough for incorporation into the available rotor-noise prediction code. A problem illustrating the importance of rotor shocks in the generation of high-intensity noise is presented.

Absolute Hugoniot measurements from a spherically convergent shock using x-ray radiography

NASA Astrophysics Data System (ADS)

Swift, Damian C.; Kritcher, Andrea L.; Hawreliak, James A.; Lazicki, Amy; MacPhee, Andrew; Bachmann, Benjamin; Döppner, Tilo; Nilsen, Joseph; Collins, Gilbert W.; Glenzer, Siegfried; Rothman, Stephen D.; Kraus, Dominik; Falcone, Roger W.

2018-05-01

The canonical high pressure equation of state measurement is to induce a shock wave in the sample material and measure two mechanical properties of the shocked material or shock wave. For accurate measurements, the experiment is normally designed to generate a planar shock which is as steady as possible in space and time, and a single state is measured. A converging shock strengthens as it propagates, so a range of shock pressures is induced in a single experiment. However, equation of state measurements must then account for spatial and temporal gradients. We have used x-ray radiography of spherically converging shocks to determine states along the shock Hugoniot. The radius-time history of the shock, and thus its speed, was measured by radiographing the position of the shock front as a function of time using an x-ray streak camera. The density profile of the shock was then inferred from the x-ray transmission at each instant of time. Simultaneous measurement of the density at the shock front and the shock speed determines an absolute mechanical Hugoniot state. The density profile was reconstructed using the known, unshocked density which strongly constrains the density jump at the shock front. The radiographic configuration and streak camera behavior were treated in detail to reduce systematic errors. Measurements were performed on the Omega and National Ignition Facility lasers, using a hohlraum to induce a spatially uniform drive over the outside of a solid, spherical sample and a laser-heated thermal plasma as an x-ray source for radiography. Absolute shock Hugoniot measurements were demonstrated for carbon-containing samples of different composition and initial density, up to temperatures at which K-shell ionization reduced the opacity behind the shock. Here we present the experimental method using measurements of polystyrene as an example.

Rail Shock and Vibration Pre-Test Modeling of a Used Nuclear Fuel Assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Steven B.; Klymyshyn, Nicholas A.; Jensen, Philip J.

The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Fuel Cycle Technology, has established the Used Fuel Disposition Campaign (UFDC) to conduct the research and development activities related to storage, transportation, and disposal of used nuclear fuel (UNF) and high-level radioactive waste (HLW). The mission of the UFDC is to identify alternatives and conduct scientific research and technology development to enable storage, transportation and disposal of used nuclear fuel and HLW generated by existing and future nuclear fuel cycles. The Storage and Transportation staff within the UFDC is responsible for addressing issues regarding the long-term or extendedmore » storage (ES) of UNF and its subsequent transportation. Available information is not sufficient to determine the ability of ES UNF, including high-burnup fuel, to withstand shock and vibration forces that could occur when the UNF is shipped by rail from nuclear power plant sites to a storage or disposal facility. There are three major gaps in the available information – 1) the forces that UNF assemblies would be subjected to when transported by rail, 2) the mechanical characteristics of fuel rod cladding, which is an essential structure for controlling the geometry of the UNF, a safety related feature, and 3) modeling methodologies to evaluate multiple possible degradation or damage mechanisms over the UNF lifetime. In order to address the first gap, options for tests to determine the physical response of surrogate UNF assemblies subjected to shock and vibration forces that are expected to be experienced during normal conditions of transportation (NCT) by rail must be identified and evaluated. The objective of the rail shock and vibration tests is to obtain data that will help researchers understand the mechanical loads that ES UNF assemblies would be subjected to under normal conditions of transportation and to fortify the computer modeling that will be necessary to evaluate the impact those loads may have on the integrity of the UNF assembly. The shock and vibration testing along with computer modeling is a vital part of research to achieve closure of a gap in information related to the ability of ES UNF to maintain its safety function when subjected to NCT. In support of this effort, preliminary structural dynamics modeling is presented herein. The modeling investigates the rigidity of a hypothetical cask and cradle structure by comparing it to a monolithic concrete mass. The concrete mass represents a practical option for achieving the necessary cask and cradle mass on a flatbed railcar, but this comparative modeling study investigates whether or not the dynamic loads transmitted through a monolithic concrete configuration are adequately representative of a realistic cask and cradle system. This modeling highlights the need for rail testing by reporting the phenomenon of structural transmissibility. As shown herein, this structural transmissibility can cause an amplification of shock and vibration loads through the structure, which could potentially lead to accelerated mechanical degradation of UNF under NCT.« less

Pancreatic Digestive Enzyme Blockade in the Intestine Increases Survival After Experimental Shock

PubMed Central

DeLano, Frank A.; Hoyt, David B.; Schmid-Schönbein, Geert W.

2015-01-01

Shock, sepsis, and multiorgan failure are associated with inflammation, morbidity, and high mortality. The underlying pathophysiological mechanism is unknown, but evidence suggests that pancreatic enzymes in the intestinal lumen autodigest the intestine and generate systemic inflammation. Blocking these enzymes in the intestine reduces inflammation and multiorgan dysfunction. We investigated whether enzymatic blockade also reduces mortality after shock. Three rat shock models were used here: hemorrhagic shock, peritonitis shock induced by placement of cecal material into the peritoneum, and endotoxin shock. One hour after initiation of hemorrhagic, peritonitis, or endotoxin shock, animals were administered one of three different pancreatic enzyme inhibitors—6-amidino-2-naphtyl p-guanidinobenzoate di-methanesulfate, tranexamic acid, or aprotinin—into the lumen of the small intestine. In all forms of shock, blockade of digestive proteases with protease inhibitor attenuated entry of digestive enzymes into the wall of the intestine and subsequent autodigestion and morphological damage to the intestine, lung, and heart. Animals treated with protease inhibitors also survived in larger numbers than untreated controls over a period of 12 weeks. Surviving animals recovered completely and returned to normal weight within 14 days after shock. The results suggest that the active and concentrated digestive enzymes in the lumen of the intestine play a central role in shock and multi-organ failure, which can be treated with protease inhibitors that are currently available for use in the clinic. PMID:23345609

Wind-tunnel based definition of the AFE aerothermodynamic environment. [Aeroassist Flight Experiment

NASA Technical Reports Server (NTRS)

Miller, Charles G.; Wells, W. L.

1992-01-01

The Aeroassist Flight Experiment (AFE), scheduled to be performed in 1994, will serve as a precursor for aeroassisted space transfer vehicles (ASTV's) and is representative of entry concepts being considered for missions to Mars. Rationale for the AFE is reviewed briefly as are the various experiments carried aboard the vehicle. The approach used to determine hypersonic aerodynamic and aerothermodynamic characteristics over a wide range of simulation parameters in ground-based facilities is presented. Facilities, instrumentation and test procedures employed in the establishment of the data base are discussed. Measurements illustrating the effects of hypersonic simulation parameters, particularly normal-shock density ratio (an important parameter for hypersonic blunt bodies), and attitude on aerodynamic and aerothermodynamic characteristics are presented, and predictions from computational fluid dynamic (CFD) computer codes are compared with measurement.

Computational Analysis of the Effect of Porosity on Shock Cell Strength at Cruise

NASA Technical Reports Server (NTRS)

Massey, Steven J.; Elmiligui, Alaa A.; Pao, S. Paul; Abdol-Hamid, Khaled S.; Hunter, Craig A.

2006-01-01

A computational flow field analysis is presented of the effect of core cowl porosity on shock cell strength for a modern separate flow nozzle at cruise conditions. The goal of this study was to identify the primary physical mechanisms by which the application of porosity can reduce shock cell strength and hence the broadband shock associated noise. The flow is simulated by solving the asymptotically steady, compressible, Reynoldsaveraged Navier-Stokes equations on a structured grid using an implicit, up-wind, flux-difference splitting finite volume scheme. The standard two-equation k - epsilon turbulence model with a linear stress representation is used with the addition of a eddy viscosity dependence on total temperature gradient normalized by local turbulence length scale. Specific issues addressed in this study were the optimal area required to weaken a shock impinging on the core cowl surface and the optimal level of porosity and placement of porous areas for reduction of the overall shock cell strength downstream. Two configurations of porosity were found to reduce downstream shock strength by approximately 50%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olmstead, D.; Wayne, P.; Simons, D.

Here, we consider two cases of interaction between a planar shock and a cylindrical density interface. In the first case (planar normal shock), the axis of the gas cylinder is parallel to the shock front and baroclinic vorticity deposited by the shock is predominantly two dimensional (directed along the axis of the cylinder). In the second case, the cylinder is tilted, resulting in an oblique shock interaction and a fully-three-dimensional shock-induced vorticity field. Furthermore, the statistical properties of the flow for both cases are analyzed based on images from two orthogonal visualization planes, using structure functions of the intensity mapsmore » of fluorescent tracer premixed with heavy gas. And at later times, these structure functions exhibit power-law-like behavior over a considerable range of scales. Manifestation of this behavior is remarkably consistent in terms of dimensionless time τ defined based on Richtmyer's linear theory within the range of Mach numbers from 1.1 to 2.0 and the range of gas cylinder tilt angles with respect to the plane of the shock front (0–30°).« less

Shock shapes on blunt bodies in hypersonic-hypervelocity helium, air, and CO2 flows, and calibration results in Langley 6-inch expansion tube

NASA Technical Reports Server (NTRS)

Miller, C. G., III

1975-01-01

Shock shape results for flat-faced cylinders, spheres, and spherically blunted cones in various test gases, along with preliminary results from a calibration study performed in the Langley 6-inch expansion tube are presented. Free-stream velocities from 5 to 7 km/sec are generated at hypersonic conditions with helium, air, and CO2, resulting in normal shock density ratios from 4 to 19. Ideal-gas shock shape predictions, in which an effective ratio of specific heats is used as input, are compared with the measured results. The effect of model diameter is examined to provide insight to the thermochemical state of the flow in the shock layer. The regime for which equilibrium exists in the shock layer for the present air and CO2 test conditions is defined. Test core flow quality, test repeatability, and comparison of measured and predicted expansion-tube flow quantities are discussed.

Mechanical analysis of a heat-shock induced developmental defect

NASA Astrophysics Data System (ADS)

Crews, Sarah M.; McCleery, W. Tyler; Hutson, M. Shane

2014-03-01

Embryonic development in Drosophila is a complex process involving coordinated movements of mechanically interacting tissues. Perturbing this system with a transient heat shock can result in a number of developmental defects. In particular, a heat shock applied during the earliest morphogenetic movements of gastrulation can lead to apparent recovery, but then subsequent morphogenetic failure 5-6 hours later during germ band retraction. The process of germ band retraction requires an intact amnioserosa - a single layered extra-embryonic epithelial tissue - and heat shock at gastrulation can induce the later opening of holes in the amnioserosa. These holes are highly correlated with failures of germ band retraction. These holes could be caused by a combination of mechanical weakness in the amnioserosa or local increases in mechanical stress. Here, we assess the role of mechanical stress using confocal imaging to compare cell and tissue morphology in the amnioserosa of normal and heat-shocked embryos and laser hole drilling to map the stress field around the times and locations at which heat-shock induced holes open.

Dissociative Functions in the Normal Mourning Process.

ERIC Educational Resources Information Center

Kauffman, Jeffrey

1994-01-01

Sees dissociative functions in mourning process as occurring in conjunction with integrative trends. Considers initial shock reaction in mourning as model of normal dissociation in mourning process. Dissociation is understood to be related to traumatic significance of death in human consciousness. Discerns four psychological categories of…

Interplanetary Circumstances of Quasi-Perpendicular Interplanetary Shocks in 1996-2005

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Cane, H. V.

2010-01-01

The angle (theta(sub Bn)) between the normal to an interplanetary shock front and the upstream magnetic field direction, though often thought of as a property "of the shock," is also determined by the configuration of the magnetic field immediately upstream of the shock. We investigate the interplanetary circumstances of 105 near-Earth quasi-perpendicular shocks during 1996-2005 identified by theta(sub Bn) greater than or equal to 80 degrees and/or by evidence of shock drift particle acceleration. Around 87% of these shocks were driven by interplanetary coronal mass ejections (ICMEs); the remainder were probably the forward shocks of corotating interaction regions. For around half of the shocks, the upstream field was approximately perpendicular to the radial direction, either east-west or west-east or highly inclined to the ecliptic. Such field directions will give quasi-perpendicular configurations for radially propagating shocks. Around 30% of the shocks were propagating through, or closely followed, ICMEs at the time of observation. Another quarter were propagating through the heliospheric plasma sheet (HPS), and a further quarter occurred in slow solar wind that did not have characteristics of the HPS. Around 11% were observed in high-speed streams, and 7% in the sheaths following other shocks. The fraction of shocks found in high-speed streams is around a third of that expected based on the fraction of the time when such streams were observed at Earth. Quasi-perpendicular shocks are found traveling through ICMEs around 2-3 times more frequently than expected. In addition, shocks propagating through ICMEs are more likely to have larger values of theta(sub Bn) than shocks outside ICMEs.

MMS observations and hybrid simulations of rippled and reforming quasi-parallel shocks

NASA Astrophysics Data System (ADS)

Gingell, I.; Schwartz, S. J.; Burgess, D.; Johlander, A.; Russell, C. T.; Burch, J. L.; Ergun, R.; Fuselier, S. A.; Gershman, D. J.; Giles, B. L.; Goodrich, K.; Khotyaintsev, Y. V.; Lavraud, B.; Lindqvist, P. A.; Strangeway, R. J.; Trattner, K. J.; Torbert, R. B.; Wilder, F. D.

2017-12-01

Surface ripples, i.e. deviations in the nominal local shock orientation, are expected to propagate in the ramp and overshoot of collisionless shocks. These ripples have typically been associated with observations and simulations of quasi-perpendicular shocks. We present observations of a crossing of Earth's marginally quasi-parallel (θBn ˜ 45°) bow shock by the MMS spacecraft on 2015-11-27 06:01:44 UTC, for which we identify signatures consistent with a propagating surface ripple. In order to demonstrate the differences between ripples at quasi-perpendicular and quasi-parallel shocks, we also present two-dimensional hybrid simulations over a range of shock normal angles θBn under the observed solar wind conditions. We show that in the quasi-parallel cases surface ripples are transient phenomena modulated by the cyclic reformation of the shock front. These ripples develop faster than an ion gyroperiod and only during the period of the reformation cycle when a newly developed shock ramp is unaffected by turbulence in the foot. We conclude that the change of properties of the surface ripple observed by MMS while crossing Earth's quasi-parallel bow shock are consistent with the influence of cyclic reformation on shock structure. Given that both surface ripples and cyclic reformation are expected to affect the acceleration of electrons within the shock, the interaction of these phenomena and any other sources of shock non-stationary are important for models of particle acceleration. We therefore discuss signatures of electron heating and acceleration in several rippled shocks observed by MMS.

Identification of Several Mutations in ATP2C1 in Lebanese Families: Insight into the Pathogenesis of Hailey-Hailey Disease

PubMed Central

Btadini, Waed; Abou Hassan, Ossama K.; Saadeh, Dana; Abbas, Ossama; Ballout, Farah; Kibbi, Abdul-Ghani; Dbaibo, Ghassan; Darwiche, Nadine; Nemer, Georges; Kurban, Mazen

2015-01-01

Background Hailey-Hailey disease (HHD) is an inherited blistering dermatosis characterized by recurrent erosions and erythematous plaques that generally manifest in intertriginous areas. Genetically, HHD is an autosomal dominant disease, resulting from heterozygous mutations in ATP2C1, which encodes a Ca2+/Mn2+ATPase. In this study, we aimed at identifying and analyzing mutations in five patients from unrelated families diagnosed with HHD and study the underlying molecular pathogenesis. Objectives To genetically study Lebanese families with HHD, and the underlying molecular pathogenesis of the disease. Methods We performed DNA sequencing for the coding sequence and exon-intron boundaries of ATP2C1. Heat shock experiments were done on several cell types. This was followed by real-time and western blotting for ATP2C1, caspase 3, and PARP proteins to examine any possible role of apoptosis in HHD. This was followed by TUNEL staining to confirm the western blotting results. We then performed heat shock experiments on neonatal rat primary cardiomyocytes. Results Four mutations were detected, three of which were novel and one recurrent mutation in two families. In order for HHD to manifest, it requires both the genetic alteration and the environmental stress, therefore we performed heat shock experiments on fibroblasts (HH and normal) and HaCaT cells, mimicking the environmental factor seen in HHD. It was found that stress stimuli, represented here as temperature stress, leads to an increase in the mRNA and protein levels of ATP2C1 in heat-shocked cells as compared to non-heat shocked ones. However, the increase in ATP2C1 and heat shock protein hsp90 is significantly lower in HH fibroblasts in comparison to normal fibroblasts and HaCaT cells. We did not find a role for apoptosis in the pathogenesis of HHD. A similar approach (heat shock experiments) done on rat cardiomyocytes, led to a significant variation in ATP2C1 transcript and protein levels. Conclusion This is the first genetic report of HHD from Lebanon in which we identified three novel mutations in ATP2C1 and shed light on the molecular mechanisms and pathogenesis of HHD by linking stress signals like heat shock to the observed phenotypes. This link was also found in cultured cardiomyocytes suggesting thus a yet uncharacterized cardiac phenotype in HHD patients masked by its in-expressivity in normal health conditions. PMID:25658765

Hydrogen gas inhalation inhibits progression to the "irreversible" stage of shock after severe hemorrhage in rats.

PubMed

Matsuoka, Tadashi; Suzuki, Masaru; Sano, Motoaki; Hayashida, Kei; Tamura, Tomoyoshi; Homma, Koichiro; Fukuda, Keiichi; Sasaki, Junichi

2017-09-01

Mortality of hemorrhagic shock primarily depends on whether or not the patients can endure the loss of circulating volume until radical treatment is applied. We investigated whether hydrogen (H2) gas inhalation would influence the tolerance to hemorrhagic shock and improve survival. Hemorrhagic shock was achieved by withdrawing blood until the mean arterial blood pressure reached 30-35 mm Hg. After 60 minutes of shock, the rats were resuscitated with a volume of normal saline equal to four times the volume of shed blood. The rats were assigned to either the H2 gas (1.3% H2, 26% O2, 72.7% N2)-treated group or the control gas (26% O2, 74% N2)-treated group. Inhalation of the specified gas mixture began at the initiation of blood withdrawal and continued for 2 hours after fluid resuscitation. The survival rate at 6 hours after fluid resuscitation was 80% in H2 gas-treated rats and 30% in control gas-treated rats (p < 0.05). The volume of blood that was removed through a catheter to induce shock was significantly larger in the H2 gas-treated rats than in the control rats. Despite losing more blood, the increase in serum potassium levels was suppressed in the H2 gas-treated rats after 60 minutes of shock. Fluid resuscitation completely restored blood pressure in the H2 gas-treated rats, whereas it failed to fully restore the blood pressure in the control gas-treated rats. At 2 hours after fluid resuscitation, blood pressure remained in the normal range and metabolic acidosis was well compensated in the H2 gas-treated rats, whereas we observed decreased blood pressure and uncompensated metabolic acidosis and hyperkalemia in the surviving control gas-treated rats. H2 gas inhalation delays the progression to irreversible shock. Clinically, H2 gas inhalation is expected to stabilize the subject until curative treatment can be performed, thereby increasing the probability of survival after hemorrhagic shock.

IL-6-Mediated Activation of Stat3α Prevents Trauma/Hemorrhagic Shock-Induced Liver Inflammation

PubMed Central

Moran, Ana; Thacker, Stephen A.; Arikan, Ayse Akcan; Mastrangelo, Mary-Ann A.; Wu, Yong; Yu, Bi; Tweardy, David J.

2011-01-01

Trauma complicated by hemorrhagic shock (T/HS) is the leading cause of morbidity and mortality in the United States for individuals under the age of 44 years. Initial survivors are susceptible to developing multiple organ failure (MOF), which is thought to be caused, at least in part, by excessive or maladaptive activation of inflammatory pathways. We previously demonstrated in rodents that T/HS results in liver injury that can be prevented by IL-6 administration at the start of resuscitation; however, the contribution of the severity of HS to the extent of liver injury, whether or not resuscitation is required, and the mechanism(s) for the IL-6 protective effect have not been reported. In the experiments described here, we demonstrated that the extent of liver inflammation induced by T/HS depends on the duration of hypotension and requires resuscitation. We established that IL-6 administration at the start of resuscitation is capable of completely reversing liver inflammation and is associated with increased Stat3 activation. Global assessment of the livers showed that the main effect of IL-6 was to normalize the T/HS-induced inflammation transcriptome. Pharmacological inhibition of Stat3 activity within the liver blocked the ability of IL-6 to prevent liver inflammation and to normalize the T/HS-induced liver inflammation transcriptome. Genetic deletion of a Stat3β, a naturally occurring, dominant-negative isoform of the Stat3, attenuated T/HS-induced liver inflammation, confirming a role for Stat3, especially Stat3α, in preventing T/HS-mediated liver inflammation. Thus, T/HS-induced liver inflammation depends on the duration of hypotension and requires resuscitation; IL-6 administration at the start of resuscitation reverses T/HS-induced liver inflammation, through activation of Stat3α, which normalized the T/HS-induced liver inflammation transcriptome. PMID:21738667

Investigations on GSK-3β/NF-kB signaling in stress and stress adaptive behavior in electric foot shock subjected mice.

PubMed

Bali, Anjana; Jaggi, Amteshwar Singh

2016-04-01

The present study was designed to explore the role of GSK-3β and NF-kB signaling in electric foot shock-induced stress and stress adaptation. Mice were subjected to foot shocks of 0.5mA intensity and 1s duration of 1h to produce acute stress. Animals were exposed to the same stressor for 5 days to induce stress adaptation. The behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. The serum corticosterone levels were assessed as a marker of the HPA axis. The levels of total GSK-3β, p-GSK-3β-S9 and p-NF-kB were determined in the hippocampus, frontal cortex and amygdala. Acute electric foot shock stress produced behavioral and biochemical changes; decreased the levels of p-GSK-3β-S9, produced no change in total GSK-3β levels and increased p-NF-kB levels in the brain. However, repeated exposure of foot shock stress restored the behavioral and biochemical changes along with normalization of p-GSK-3β-S9 and p-NF-kB levels. Administration of AR-A01, a selective GSK-3β inhibitor, or diethyldithiocarbamic acid (DDTC), a selective NF-kB inhibitor, diminished acute stress-induced behavioral and biochemical changes. Furthermore, AR-A014418 normalized acute stress-induced alterations in p-GSK-3β-S9 and p-NF-kB levels, however, DDTC selectively restored NF-kB levels without any change in p-GSK-3β-S9 levels. It probably suggests that NF-kB is a downstream mediator of the GSK-3 signaling cascade. It may conclude that acute stress associated decrease in p-GSK-3β-S9 and increase in p-NF-kB levels in the brain contribute in the development of behavioral and biochemical alterations and normalization of GSK-3β/NF-kB signaling may contribute in stress adaptive behavior in response to repeated electric foot shock-subjected mice. Copyright © 2016 Elsevier B.V. All rights reserved.

Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

NASA Technical Reports Server (NTRS)

Carlson, Leland A.

1994-01-01

The primary accomplishments of the project were as follows: (1) From an overall standpoint, the primary accomplishment of this research was the development of a complete gasdynamic-radiatively coupled nonequilibrium viscous shock layer solution method for axisymmetric blunt bodies. This method can be used for rapid engineering modeling of nonequilibrium re-entry flowfields over a wide range of conditions. (2) Another significant accomplishment was the development of an air radiation model that included local thermodynamic nonequilibrium (LTNE) phenomena. (3) As part of this research, three electron-electronic energy models were developed. The first was a quasi-equilibrium electron (QEE) model which determined an effective free electron temperature and assumed that the electronic states were in equilibrium with the free electrons. The second was a quasi-equilibrium electron-electronic (QEEE) model which computed an effective electron-electronic temperature. The third model was a full electron-electronic (FEE) differential equation model which included convective, collisional, viscous, conductive, vibrational coupling, and chemical effects on electron-electronic energy. (4) Since vibration-dissociation coupling phenomena as well as vibrational thermal nonequilibrium phenomena are important in the nonequilibrium zone behind a shock front, a vibrational energy and vibration-dissociation coupling model was developed and included in the flowfield model. This model was a modified coupled vibrational dissociation vibrational (MCVDV) model and also included electron-vibrational coupling. (5) Another accomplishment of the project was the usage of the developed models to investigate radiative heating. (6) A multi-component diffusion model which properly models the multi-component nature of diffusion in complex gas mixtures such as air, was developed and incorporated into the blunt body model. (7) A model was developed to predict the magnitude and characteristics of the shock wave precursor ahead of vehicles entering the Earth's atmosphere. (8) Since considerable data exists for radiating nonequilibrium flow behind normal shock waves, a normal shock wave version of the blunt body code was developed. (9) By comparing predictions from the models and codes with available normal shock data and the flight data of Fire II, it is believed that the developed flowfield and nonequilibrium radiation models have been essentially validated for engineering applications.

Preliminary Investigation on the Effects of Shockwaves on Water Samples Using a Portable Semi-Automatic Shocktube

NASA Astrophysics Data System (ADS)

Wessley, G. Jims John

2017-10-01

The propagation of shock waves through any media results in an instantaneous increase in pressure and temperature behind the shockwave. The scope of utilizing this sudden rise in pressure and temperature in new industrial, biological and commercial areas has been explored and the opportunities are tremendous. This paper presents the design and testing of a portable semi-automatic shock tube on water samples mixed with salt. The preliminary analysis shows encouraging results as the salinity of water samples were reduced up to 5% when bombarded with 250 shocks generated using a pressure ratio of 2. 5. Paper used for normal printing is used as the diaphragm to generate the shocks. The impact of shocks of much higher intensity obtained using different diaphragms will lead to more reduction in the salinity of the sea water, thus leading to production of potable water from saline water, which is the need of the hour.

Large-Amplitude Electrostatic Waves Observed at a Supercritical Interplanetary Shock

NASA Technical Reports Server (NTRS)

Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.

2010-01-01

We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

Planar Reflection of Detonations Waves

NASA Astrophysics Data System (ADS)

Damazo, Jason; Shepherd, Joseph

2012-11-01

An experimental study examining normally reflected gaseous detonation waves is undertaken so that the physics of reflected detonations may be understood. Focused schlieren visualization is used to describe the boundary layer development behind the incident detonation wave and the nature of the reflected shock wave. Reflected shock wave bifurcation-which has received extensive study as it pertains to shock tube performance-is predicted by classical bifurcation theory, but is not observed in the present study for undiluted hydrogen-oxygen and ethylene-oxygen detonation waves. Pressure and thermocouple gauges are installed in the floor of the detonation tube so as to examine both the wall pressure and heat flux. From the pressure results, we observe an inconsistency between the measured reflected shock speed and the measured reflected shock strength with one dimensional flow predictions confirming earlier experiments performed in our laboratory. This research is sponsored by the DHS through the University of Rhode Island, Center of Excellence for Explosives Detection.

Quantitative evaluation of the mechanical strength of titanium/composite bonding using laser-generated shock waves

NASA Astrophysics Data System (ADS)

Ducousso, M.; Bardy, S.; Rouchausse, Y.; Bergara, T.; Jenson, F.; Berthe, L.; Videau, L.; Cuvillier, N.

2018-03-01

Intense acoustic shock waves were applied to evaluate the mechanical strength of structural epoxy bonds between a TA6V4 titanium alloy and a 3D woven carbon/epoxy composite material. Two bond types with different mechanical strengths were obtained from two different adhesive reticulations, at 50% and 90% of conversion, resulting in longitudinal static strengths of 10 and 39 MPa and transverse strengths of 15 and 35 MPa, respectively. The GPa shock waves were generated using ns-scale intense laser pulses and reaction principles to a confined plasma expansion. Simulations taking into account the laser-matter interaction, plasma relaxation, and non-linear shock wave propagation were conducted to aid interpretation of the experiments. Good correlations were obtained between the experiments and the simulation and between different measurement methods of the mechanical strength (normalized tests vs laser-generated shock waves). Such results open the door toward certification of structural bonding.

The "Visual Shock" of Francis Bacon: an essay in neuroesthetics.

PubMed

Zeki, Semir; Ishizu, Tomohiro

2013-01-01

In this paper we discuss the work of Francis Bacon in the context of his declared aim of giving a "visual shock."We explore what this means in terms of brain activity and what insights into the brain's visual perceptive system his work gives. We do so especially with reference to the representation of faces and bodies in the human visual brain. We discuss the evidence that shows that both these categories of stimuli have a very privileged status in visual perception, compared to the perception of other stimuli, including man-made artifacts such as houses, chairs, and cars. We show that viewing stimuli that depart significantly from a normal representation of faces and bodies entails a significant difference in the pattern of brain activation. We argue that Bacon succeeded in delivering his "visual shock" because he subverted the normal neural representation of faces and bodies, without at the same time subverting the representation of man-made artifacts.

Transplant shock of northern red oak seedlings following simulated drought as influenced by root morphology

Treesearch

Douglass F. Jacobs; Francis Salifu; Anthony Davis

2005-01-01

Transplant shock, implicated by depressed seedling physiological response associated with moisture or nutrient stress immediately following planting, limits early plantation establishment. We investigated the impacts of simulated drought and transplant root volume on predawn leaf xylem water potential, photosynthetic assimilation rates, stomatal conductance, and growth...

Formation of Accelerated Backstreaming Particles within the Quasi-perpendicular Ion Terrestrial Foreshock: 2D Full-Particle and Test-particles simulations

NASA Astrophysics Data System (ADS)

Savoini, P.; Lembege, B.

2016-12-01

Backstreaming ion populations are observed upstream of the Terrestrial bow shock and form the ion foreshock. Two distinct populations have been firmly identified by spacecrafts within the quasi-perpendicular shock region (i.e. for 45° ≤ ΘBn ≤ 90°, where ΘBn is the angle between the shock normal and the upstream magnetostatic field): so called (i) field-aligned ion beams (« FAB ») characterized by a gyrotropic distribution, and (ii) gyro-phase bunched ions («GPB »), characterized by a NON gyrotropic distribution.The origin of these backstreaming ions is still an important unresolved question which can be partially analyzed with the help of 2D PIC simulation of a curved shock, where full curvature effects, time of flight effects and both electrons and ions dynamics are fully included by a self consistent approach. Our previous analysis (Savoini et Lembege, 2015) has evidenced that these two populations can be generated directly by the macroscopic fields at the shock front itself. Present results based on ion trajectories analysis confirm: (i) the importance of the interaction time ΔTinter spent by ions within the shock front. "GPB" population is characterized by a very short interaction time (ΔTinter = 1 to 2 tci) in comparison to the "FAB" population (ΔTinter = 2 tci to 10 tci), where tci is the upstream ion gyroperiod. (ii) the key role of the injection angle (i.e. defined between the normal of the shock front and the gyration velocity at the time incoming ions hit the shock front) which strongly differs between FAB and GPB ions. (iii) that "FAB" ions drift along the shock front and « scan » a large ΘBn range (up to 20°) which explains the loss of their initial gyro-phase, before being re-injected into the upstream region. Moreover, our test-particule simulations evidence the importance of the shock wave profile for both the « FAB » and « GPB » populations. Such results show that the reflection process is not continuous in time and in space, but strongly depends of the local shock front profile met by incoming ions at their hitting time. The same simulations also emphasize the slight decrease of backstreaming ions density when the electric field space charge effect present within the shock front is artificially canceled. A comparison between self-consistent and test-particles results will be presented in more details.

Research on shock wave characteristics in the isolator of central strut rocket-based combined cycle engine under Ma5.5

NASA Astrophysics Data System (ADS)

Wei, Xianggeng; Xue, Rui; Qin, Fei; Hu, Chunbo; He, Guoqiang

2017-11-01

A numerical calculation of shock wave characteristics in the isolator of central strut rocket-based combined cycle (RBCC) engine fueled by kerosene was carried out in this paper. A 3D numerical model was established by the DES method. The kerosene chemical kinetic model used the 9-component and 12-step simplified mechanism model. Effects of fuel equivalence ratio, inflow total temperature and central strut rocket on-off on shock wave characteristics were studied under Ma5.5. Results demonstrated that with the increase of equivalence ratio, the leading shock wave moves toward upstream, accompanied with higher possibility of the inlet unstart. However, the leading shock wave moves toward downstream as the inflow total temperature rises. After the central strut rocket is closed, the leading shock wave moves toward downstream, which can reduce risks of the inlet unstart. State of the shear layer formed by the strut rocket jet flow and inflow can influence the shock train structure significantly.

An Atypical Case of Eosinophilic Gastroenteritis Presenting as Hypovolemic Shock.

PubMed

Martillo, Miguel; Abed, Jean; Herman, Michael; Abed, Elie; Shi, Wenjing; Munot, Khushboo; Mankal, Pavan Kumar; Gurunathan, Rajan; Ionescu, Gabriel; Kotler, Donald P

2015-01-01

Eosinophilic gastroenteritis is an uncommon condition characterized by focal or diffuse infiltration of eosinophils in the gastrointestinal tract in the absence of secondary causes. The pathogenesis of this condition is not well understood and its clinical presentation depends on the segment and layer of the gastrointestinal tract affected. The definition of eosinophilic gastroenteritis may be difficult, as the normal ranges of eosinophil numbers in normal and abnormal gastric and intestinal mucosa are not standardized. We present the case of a 59-year-old male who came to the hospital with hypovolemic shock and lethargy secondary to severe diarrhea. Laboratory analysis was significant for peripheral eosinophilia, and pathology from both the duodenum and colon showed marked eosinophilic infiltration.

The acceleration of particles at propagating interplanetary shocks

NASA Astrophysics Data System (ADS)

Prinsloo, P. L.; Strauss, R. D. T.

2017-12-01

Enhancements of charged energetic particles are often observed at Earth following the eruption of coronal mass ejections (CMEs) on the Sun. These enhancements are thought to arise from the acceleration of those particles at interplanetary shocks forming ahead of CMEs, propagating into the heliosphere. In this study, we model the acceleration of these energetic particles by solving a set of stochastic differential equations formulated to describe their transport and including the effects of diffusive shock acceleration. The study focuses on how acceleration at halo-CME-driven shocks alter the energy spectra of non-thermal particles, while illustrating how this acceleration process depends on various shock and transport parameters. We finally attempt to establish the relative contributions of different seed populations of energetic particles in the inner heliosphere to observed intensities during selected acceleration events.

Structural Changes in Alloys of the Al-Cu-Mg System Under Ion Bombardment and Shock-Wave Loading

NASA Astrophysics Data System (ADS)

Ovchinnikov, V. V.; Gushchina, N. V.; Romanov, I. Yu.; Kaigorodova, L. I.; Grigor'ev, A. N.; Pavlenko, A. V.; Plokhoi, V. V.

2017-02-01

To confirm the hypothesis on the shock-wave nature of long-range effects upon corpuscular irradiation of condensed media presumably caused by emission and propagation of post-cascade shock waves, comparative experiments on ion beam modification and mechanical shock-wave loading of specimens of VD1 and D16 alloys of the Al-Cu-Mg system are performed. Direct analogy between the processes of microstructural change of cold-deformed VD1 and D16 alloys under mechanical shock loading and irradiation by beams of accelerated Ar+ ions (E = 20-40 keV) with low fluences (1015-1016 cm-2) is established. This demonstrates the important role of the dynamic long-range effects that have not yet been considered in classical radiation physics of solids.

Integrative analysis of the heat shock response in Aspergillus fumigatus

PubMed Central

2010-01-01

Background Aspergillus fumigatus is a thermotolerant human-pathogenic mold and the most common cause of invasive aspergillosis (IA) in immunocompromised patients. Its predominance is based on several factors most of which are still unknown. The thermotolerance of A. fumigatus is one of the traits which have been assigned to pathogenicity. It allows the fungus to grow at temperatures up to and above that of a fevered human host. To elucidate the mechanisms of heat resistance, we analyzed the change of the A. fumigatus proteome during a temperature shift from 30°C to 48°C by 2D-fluorescence difference gel electrophoresis (DIGE). To improve 2D gel image analysis results, protein spot quantitation was optimized by missing value imputation and normalization. Differentially regulated proteins were compared to previously published transcriptome data of A. fumigatus. The study was augmented by bioinformatical analysis of transcription factor binding sites (TFBSs) in the promoter region of genes whose corresponding proteins were differentially regulated upon heat shock. Results 91 differentially regulated protein spots, representing 64 different proteins, were identified by mass spectrometry (MS). They showed a continuous up-, down- or an oscillating regulation. Many of the identified proteins were involved in protein folding (chaperones), oxidative stress response, signal transduction, transcription, translation, carbohydrate and nitrogen metabolism. A correlation between alteration of transcript levels and corresponding proteins was detected for half of the differentially regulated proteins. Interestingly, some previously undescribed putative targets for the heat shock regulator Hsf1 were identified. This provides evidence for Hsf1-dependent regulation of mannitol biosynthesis, translation, cytoskeletal dynamics and cell division in A. fumigatus. Furthermore, computational analysis of promoters revealed putative binding sites for an AP-2alpha-like transcription factor upstream of some heat shock induced genes. Until now, this factor has only been found in vertebrates. Conclusions Our newly established DIGE data analysis workflow yields improved data quality and is widely applicable for other DIGE datasets. Our findings suggest that the heat shock response in A. fumigatus differs from already well-studied yeasts and other filamentous fungi. PMID:20074381

Automated Detection and Analysis of Interplanetary Shocks Running Real-Time on the Web

NASA Astrophysics Data System (ADS)

Vorotnikov, V.; Smith, C. W.; Hu, Q.; Szabo, A.; Skoug, R. M.; Cohen, C. M.; Davis, A. J.

2008-05-01

The ACE real-time data stream provides web-based now-casting capabilities for solar wind conditions upstream of Earth. We have built a fully automated code that finds and analyzes interplanetary shocks as they occur and posts their solutions on the Web for possible real-time application to space weather nowcasting. Shock analysis algorithms based on the Rankine-Hugoniot jump conditions exist and are in wide-spread use today for the interactive analysis of interplanetary shocks yielding parameters such as shock speed and propagation direction and shock strength in the form of compression ratios. At a previous meeting we reported on efforts to develop a fully automated code that used ACE Level-2 (science quality) data to prove the applicability and correctness of the code and the associated shock-finder. We have since adapted the code to run ACE RTSW data provided by NOAA. This data lacks the full 3-dimensional velocity vector for the solar wind and contains only a single component wind speed. We show that by assuming the wind velocity to be radial strong shock solutions remain essentially unchanged and the analysis performs as well as it would if 3-D velocity components were available. This is due, at least in part, to the fact that strong shocks tend to have nearly radial shock normals and it is the strong shocks that are most effective in space weather applications. Strong shocks are the only shocks that concern us in this application. The code is now running on the Web and the results are available to all.

Early Health Shocks, Intra-household Resource Allocation and Child Outcomes*

PubMed Central

Yi, Junjian; Heckman, James J.; Zhang, Junsen; Conti, Gabriella

2016-01-01

An open question in the literature is whether families compensate or reinforce the impact of child health shocks. Discussions usually focus on one dimension of child investment. This paper examines multiple dimensions using household survey data on Chinese child twins whose average age is 11. We find that, compared with a twin sibling who did not suffer from negative early health shocks at ages 0–3, the other twin sibling who did suffer negative health shocks received RMB 305 more in terms of health investments, but received RMB 182 less in terms of educational investments in the 12 months prior to the survey. In terms of financial transfers over all dimensions of investment, the family acts as a net equalizer in response to early health shocks for children. We estimate a human capital production function and establish that, for this sample, early health shocks negatively affect child human capital, including health, education, and socioemotional skills. Compensating investments in health as measured by BMI reduce the adverse effects of health shocks by 50%, but exacerbate the adverse impact of shocks on educational attainment by 30%. PMID:27019517

Hypersonic lateral and directional stability characteristics of aeroassist flight experiment configuration in air and CF4

NASA Technical Reports Server (NTRS)

Micol, John R.; Wells, William L.

1993-01-01

Hypersonic lateral and directional stability characteristics measured on a 60 deg half-angle elliptical cone, which was raked at an angle of 73 deg from the cone centerline and with an ellipsoid nose (ellipticity equal to 2.0 in the symmetry plane), are presented for angles of attack from -10 to 10 deg. The high normal-shock density ratio of a real gas was simulated by tests at a Mach number of 6 in air and CF4 (density ratio equal to 5.25 and 12.0, respectively). Tests were conducted in air at Mach 6 and 10 and in CF4 at Mach 6 to examine the effects of Mach number, Reynolds number, and normal-shock density ratio. Changes in Mach number from 6 to 10 in air or in Reynolds number by a factor of 4 at Mach 6 had a negligible effect on lateral and directional stability characteristics. Variations in normal-shock density ratio had a measurable effect on lateral and directional aerodynamic coefficients, but no significant effect on lateral and directional stability characteristics. Tests in air and CF4 indicated that the configuration was laterally and directionally stable through the test range of angle of attack.

Superthermal (0.5- 100 keV) Electrons near the ICME-driven shocks

NASA Astrophysics Data System (ADS)

Yang, L.; Wang, L.; Li, G.; Tao, J.; He, J.; Tu, C.

2016-12-01

We present a survey of the 0.5 - 100 keV electrons associated with ICME-driven shocks at 1 AU, using the WIND/3DP electron measurements from 1995 to 2014. We select 66 good ICME-driven shocks, and use the "Rankine-Hugoniot" shock fitting technique to obtain the shock normal, shock velocity Vs, shock compression ratio r and magnetosonic Mach number Ms. We average the electron data in the 1-hour interval immediately after the shock front to obtain the sheath electron fluxes and in the 4-hour quiet-time interval before the shock to obtain the pre-event electron fluxes. Then we subtract the pre-event electron fluxes from the sheath electron fluxes to obtain the enhanced electron fluxes at the shock. We find that the enhanced electron fluxes are positively correlated with Vs and Ms, and generally fit well to a double power-law spectrum, J E-β. At 0.5 - 2 keV, the fitted spectral index β1 ranges from 2.1 to 5.9, negatively correlated with r and Ms. At 2 - 100 keV, the fitted index β2 is smaller than β1, with values ( 1.9 to 3.4) similar to the spectral indexes of quiet-time superhalo electrons in the solar wind. β2 shows no obvious correlation with r and Ms. Neither of β1 or β2 is in agreement with the diffusive shock theoretical predication. These results suggest that electron acceleration by interplanetary shocks may be more significant at a few keVs and the interplanetary shock acceleration can contribute to the production of solar wind superhalo electrons. However, a revision of the diffusive shock acceleration theory would be needed for the electron acceleration.

Chromosome behavior of heat shock induced triploid in Fenneropenaeus chinensis

NASA Astrophysics Data System (ADS)

Zhang, Xiaojun; Li, Fuhua; Xiang, Jianhai

2003-09-01

Triploidy was induced in Chinese shrimp Fenneropenaeus chinensis by 30±0.5°C heat shock treatment (initiated at 20 min after fertilization) for 10 min to inhibit the release of PB2 at 18.0°C. The highest triploid rate obtained was 84.5% in nauplius stage. The effect of heat shock treatment on meiosis and cleavage of eggs was investigated in this work aimed to establish efficient procedures for triploid induction and to gain understanding of the mechanism of triploid production. Three pronuclei that could be observed in the treated eggs under fluorescence microscope developed into triploid embryos. Some abnormal chromosome behavior was observed in heat shocked eggs.

The Curious Events Leading to the Theory of Shock Waves

NASA Technical Reports Server (NTRS)

Salas, Manuel D.

2006-01-01

We review the history of the development of the modern theory of shock waves. Several attempts at an early-theory quickly collapsed for lack of foundations in mathematics and thermodynamics. It is not until the works of Rankine and later Hugoniot that a full theory is established. Rankine is the first to show that within the shock a non-adiabatic process must occur. Hugoniot showed that in the absence of viscosity and heat conduction conservation of energy implies conservation of entropy in smooth regions and a jump in entropy across a shock. Even after the theory is fully developed, old notions continue to pervade the literature well into the early part of the 20th Century.

Lonar Lake, India: An impact Crater in basalt

USGS Publications Warehouse

Fredriksson, K.; Dube, A.; Milton, D.J.; Balasundaram, M.S.

1973-01-01

Discovery of shock-metamorphosed material establishes the impact origin of Lonar Crater. Coarse breccia with shatter coning and microbreccia with moderately shocked fragments containing maskelynite were found in drill holes through the crater floor. Trenches on the rim yield strongly shocked fragments in which plagioclase has melted and vesiculated, and bombs and spherules of homogeneous rock melt. As the only known terrestrial impact crater in basalt, Lonar Crater provides unique opportunities for comparison with lunar craters. In particular, microbreccias and glass spherules from Lonar Crater have close analogs among the Apollo specimens.

Role of echocardiography/Doppler in cardiogenic shock: silent mitral regurgitation.

PubMed

Goldman, A P; Glover, M U; Mick, W; Pupello, D F; Hiro, S P; Lopez-Cuenca, E; Maniscalco, B S

1991-08-01

Two cases of cardiogenic shock and pulmonary edema due to acute, severe, silent mitral regurgitation are discussed. The mechanism for the mitral regurgitation was papillary muscle rupture in the setting of acute myocardial infarction. Echocardiography established the presence, severity, and cause of the mitral regurgitation and the associated hyperdynamic left ventricular function in the setting of cardiogenic shock. Transesophageal echocardiography is excellent for assessing the mitral valve in critically ill patients in whom transthoracic echocardiography may be inadequate or misleading. This allowed for emergency mitral valve replacement without prolonged attempts at medical stabilization.

Strengthening of surface layer of material by wave deformation multi-contact loading

NASA Astrophysics Data System (ADS)

Kirichek, A. V.; Barinov, S. V.; Aborkin, A. V.; Yashin, A. V.; Zaicev, A. A.

2018-03-01

It has been experimentally established that the possibility of multi-contact shock systems can transmit large total energy of the impact pulse to the deformation center. Thus, an increase in the number of instruments in a shock system from two to four, with the constant energy of the shock pulse, made it possible to increase the depth and the degree of hardening in the surface layer. The performance of multi-contact impact systems can be increased by 50% without degrading the hardening parameters by increasing the distance between the tools.

On the role of vasopressin and angiotensin in the development of irreversible haemorrhagic shock

PubMed Central

Errington, M. L.; e Silva, M. Rocha

1974-01-01

1. Long-lasting haemorrhagic hypotension (4·5 hr at 35 mmHg) leading to irreversible haemorrhagic shock, has been studied in normal dogs, in dogs treated with a bradykinin potentiating nonapeptide (BPP9a), which blocks the conversion of angiotensin I to angiotensin II, and in dogs with experimental chronic diabetes insipidus (DI dogs). BPP9a was given by I.V. injection before the start of bleeding (BPP pre-treated group), 45 min after blood pressure had reached 35 mmHg (BPP early treated group) or 2 hr after blood pressure had reached 35 mmHg (BPP late-treated group). After retransfusion of blood all dogs were allowed to recover and observed for a further period of 3 days. 2. Untreated control dogs developed haemorrhagic shock with tachycardia, low cardiac output, low total peripheral conductance and low stroke volume. All died within 24 hr of retransfusion, with pathological lesions typical of irreversible haemorrhagic shock. 3. BPP pre-treated dogs developed haemorrhagic shock with bradycardia (during early shock), high cardiac output, high peripheral vascular conductance and high stroke volume when compared with the untreated controls. All pre-treated animals survived the 3 day observation period. They were then killed and on post-mortem showed no signs of irreversible haemorrhagic shock. 4. BPP early-treated animals behaved like controls before BPP, but like pre-treated animals after the drug. Only one out of eight died within the 3 day observation period. 5. BPP late-treated dogs behaved like controls before BPP. They responded to the drug with a rise in cardiac output, peripheral vascular conductance and stroke volume, and with a fall in heart rate. These responses were, however, short-lived. Four out of these eight animals died within the 3 day observation period, with lesions of irreversible haemorrhagic shock. 6. DI dogs developed haemorrhagic shock with tachycardia (like controls), but with high cardiac output and peripheral vascular conductance (like BPP pre-treated dogs). The stroke volume of DI dogs was intermediate between those of controls and pre-treated groups. All six dogs survived the 3 day observation period. 7. BPP9a had no measurable effect on the course of endotoxic shock. 8. It is suggested that the normally severe vasoconstriction of the mesenteric vascular bed, which is thought to be responsible for irreversible haemorrhagic shock, is absent or attenuated in the absence of vasopressin or angiotensin. The consequences of this on the development of irreversibility are discussed. PMID:4373570

Phenotypic plasticity in the range-margin population of the lycaenid butterfly Zizeeria maha

PubMed Central

2010-01-01

Background Many butterfly species have been experiencing the northward range expansion and physiological adaptation, probably due to climate warming. Here, we document an extraordinary field case of a species of lycaenid butterfly, Zizeeria maha, for which plastic phenotypes of wing color-patterns were revealed at the population level in the course of range expansion. Furthermore, we examined whether this outbreak of phenotypic changes was able to be reproduced in a laboratory. Results In the recently expanded northern range margins of this species, more than 10% of the Z. maha population exhibited characteristic color-pattern modifications on the ventral wings for three years. We physiologically reproduced similar phenotypes by an artificial cold-shock treatment of a normal southern population, and furthermore, we genetically reproduced a similar phenotype after selective breeding of a normal population for ten generations, demonstrating that the cold-shock-induced phenotype was heritable and partially assimilated genetically in the breeding line. Similar genetic process might have occurred in the previous and recent range-margin populations as well. Relatively minor modifications expressed in the tenth generation of the breeding line together with other data suggest a role of founder effect in this field case. Conclusions Our results support the notion that the outbreak of the modified phenotypes in the recent range-margin population was primed by the revelation of plastic phenotypes in response to temperature stress and by the subsequent genetic process in the previous range-margin population, followed by migration and temporal establishment of genetically unstable founders in the recent range margins. This case presents not only an evolutionary role of phenotypic plasticity in the field but also a novel evolutionary aspect of range expansion at the species level. PMID:20718993

Computations of Axisymmetric Flows in Hypersonic Shock Tubes

NASA Technical Reports Server (NTRS)

Sharma, Surendra P.; Wilson, Gregory J.

1995-01-01

A time-accurate two-dimensional fluid code is used to compute test times in shock tubes operated at supersonic speeds. Unlike previous studies, this investigation resolves the finer temporal details of the shock-tube flow by making use of modern supercomputers and state-of-the-art computational fluid dynamic solution techniques. The code, besides solving the time-dependent fluid equations, also accounts for the finite rate chemistry in the hypersonic environment. The flowfield solutions are used to estimate relevant shock-tube parameters for laminar flow, such as test times, and to predict density and velocity profiles. Boundary-layer parameters such as bar-delta(sub u), bar-delta(sup *), and bar-tau(sub w), and test time parameters such as bar-tau and particle time of flight t(sub f), are computed and compared with those evaluated by using Mirels' correlations. This article then discusses in detail the effects of flow nonuniformities on particle time-of-flight behind the normal shock and, consequently, on the interpretation of shock-tube data. This article concludes that for accurate interpretation of shock-tube data, a detailed analysis of flowfield parameters, using a computer code such as used in this study, must be performed.

Detailed Study of Moderately Swept Impinging Oblique Shock/Boundary-Layer Interaction in Mach 2.3 Flow

NASA Astrophysics Data System (ADS)

Threadgill, James; Doerhmann, Adam; Little, Jesse

2017-11-01

A detailed experimental investigation of an impinging oblique Shock/Boundary Layer Interaction (SBLI) with 30° sweep in Mach 2.3 flow has been conducted. Despite its non-dimensional form, this canonical SBLI configuration has attracted little attention and remains poorly understood. Using a 12 .5° shock generator mounted in the freestream over a turbulent boundary layer, the interaction has been characterized with oil flow visualization, fast-response pressure transducers, and particle image velocimetry. Velocity vectors are used to extract the 3D interaction structure. These data are compared to wall pressure measurements and surface skin-friction streamlines. A local collapse of data normal to separation indicates a swept equivalence to Free Interaction Theory, albeit at a lower angle of sweep than imposed by the shock generator. Conditions at reattachment align with the imposed shock. Low-frequency shock motion near separation is observed, analogous to unswept SBLIs, with significant correlations that indicate spanwise traveling ripples in the shock foot. However, the magnitude of wall-pressure unsteadiness in this location is lower and shifted to higher frequencies than observed in equivalent unswept SBLI counterparts. Supported by the Air Force Office of Scientific Research (FA9550-15-1-0430).

Urgent care in gynaecology: resuscitation and management of sepsis and acute blood loss.

PubMed

Fischerova, Daniela

2009-10-01

Sepsis and/or acute blood loss can be encoutered as an emergency condition in gynaecology, especially in women with ectopic pregnancy/miscarriage, acute pelvic inflammatory disease (PID)/tuboovarian abscesses, post-puerperal sepsis/haemorrhage and even in postoperative scenarios. If underestimated or suboptimally treated, both can lead to an inadequate tissue perfusion (defined as shock) and the development of multi-organ failure. Morbidity and mortality after development of one of the shock syndromes (septic or haemorrhagic) correlates directly with the duration and severity of the malperfusion. The patient's prognosis depends on a prompt diagnosis of the presence of shock and immediate resuscitation to predefined physiological end-points, often before the cause of the shock has been identified. In septic shock, hypotension is primarily treated with fluid administration and eventually vasopressors, if required, in order to improve the circulation. Timely administration of antibiotics, control of infectious foci, appropriate use of corticoids and recombinant human activated protein C, tight glucose control, prophylaxis of deep vein thrombosis and stress ulcer prevention complete the therapy of septic shock. In haemorrhagic shock, the treatment primarily involves controlling haemorrhage, reversal of possible coagulopathy and administration of sufficient volumes of fluids and blood products to restore normal tissue perfusion.

Anisotropic shock jump conditions: Theory and observations

NASA Technical Reports Server (NTRS)

Chao, J. K.; Zhang, X. X.; Song, P.

1995-01-01

The MHD Rankine-Hugoniot (RH) relations for shock waves in a collisionless plasma with bi-Maxwellian distribution functions are considered. While by introducing the pressure anisotropy parameter xi in the RH relations, the number of unknowns -- B, V, n, p and xi (a total of 9) -- becomes one more than the total number of the conservation equations, it is possible to use the observed quantities on both sides of the shock to study the anisotropy changes across the shock. A simple relation for the anisotropy change across the shock is derived as a function of the ratio of magnetic fields m(= B'/B), the shock normal angle theta(sub Bn) and the plasma beta and beta' (primes are downstream values). Since m and theta(sub Bn) can be determined accurately in observation, the reliability of the anisotropy change deduced is mostly dependent on the accuracy of the measurements beta and beta'. We have applied the results to six low-beta quasi-perpendicular (Q perpendicular) laminar bow shock crossings with temperature anisotropy measured in the magnetosheath. In the six test cases, it is found that the predicted pressure anisotropies agree well with those observed in the magnetosheath.

AOTV bow shock location

NASA Technical Reports Server (NTRS)

Desautel, D.

1985-01-01

Hypersonic bow-shock location and geometry are of central importance to the aerodynamics and aerothermodynamics of aeroassisted orbital transfer vehicles (AOTVs), but they are difficult to predict for a given vehicle configuration. This paper reports experimental measurements of shock standoff distance for the 70 deg cone AOTV configuration in shock-tunnel-test flows at Mach numbers of 3.8 to 7.9 and for angles of attack from 0 deg to 20 deg. The controlling parameter for hypersonic bow-shock standoff distance (for a given forebody shape) is the mean normal-shock density ratio. Values for this parameter in the tests reported are in the same range as those of the drag-brake AOTV perigee regime. Results for standoff distance are compared with those previously reported in the literature for this AOTV configuration. It is concluded that the AOTV shock standoff distance for the conical configuration, based on frustrum (base) radius, is equivalent to that of a sphere with a radius about 35 percent greater than that of the cone; the distance is, therefore, much less than reported in previous studies. Some reasons for the discrepancies between the present and previous are advanced. The smaller standoff distance determined here implies there will be less radiative heat transfer than was previously expected.

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

NASA Astrophysics Data System (ADS)

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.

Shock progression and survival after use of a condom uterine balloon tamponade package in women with uncontrolled postpartum hemorrhage.

PubMed

Burke, Thomas F; Danso-Bamfo, Sandra; Guha, Moytrayee; Oguttu, Monica; Tarimo, Vincent; Nelson, Brett D

2017-10-01

To examine the outcomes of women in advanced shock from uncontrolled postpartum hemorrhage (PPH) who underwent placement of an Every Second Matters for Mothers and Babies Uterine Balloon Tamponade (ESM-UBT) device. In a prospective case series, data were collected for women who received an ESM-UBT device at healthcare facilities in Kenya, Senegal, Sierra Leone, and Tanzania between September 1, 2012, and September 30, 2016. Shock class was assigned on the basis of recorded blood pressures and mental status at the time of UBT placement. Data for 306 women with uncontrolled PPH from uterine atony across 117 facilities were analyzed. Normal vital signs or class I/II shock were reported for 166 (54.2%). In this group, one death occurred and was attributed to PPH (survival rate 99.4%). There were no cases of shock progression. One hundred and eleven (36.3%) were in class III shock and 29 (9.5%) in class IV shock; the respective survival rates were 97.3% (n=108) and 86.2% (n=25). The ESM-UBT device arrests hemorrhage, prevents shock progression, and is associated with high survival rates among women with uncontrolled PPH from uterine atony. © 2017 International Federation of Gynecology and Obstetrics.

Observation of Dispersive Shock Waves, Solitons, and Their Interactions in Viscous Fluid Conduits.

PubMed

Maiden, Michelle D; Lowman, Nicholas K; Anderson, Dalton V; Schubert, Marika E; Hoefer, Mark A

2016-04-29

Dispersive shock waves and solitons are fundamental nonlinear excitations in dispersive media, but dispersive shock wave studies to date have been severely constrained. Here, we report on a novel dispersive hydrodynamic test bed: the effectively frictionless dynamics of interfacial waves between two high viscosity contrast, miscible, low Reynolds number Stokes fluids. This scenario is realized by injecting from below a lighter, viscous fluid into a column filled with high viscosity fluid. The injected fluid forms a deformable pipe whose diameter is proportional to the injection rate, enabling precise control over the generation of symmetric interfacial waves. Buoyancy drives nonlinear interfacial self-steepening, while normal stresses give rise to the dispersion of interfacial waves. Extremely slow mass diffusion and mass conservation imply that the interfacial waves are effectively dissipationless. This enables high fidelity observations of large amplitude dispersive shock waves in this spatially extended system, found to agree quantitatively with a nonlinear wave averaging theory. Furthermore, several highly coherent phenomena are investigated including dispersive shock wave backflow, the refraction or absorption of solitons by dispersive shock waves, and the multiphase merging of two dispersive shock waves. The complex, coherent, nonlinear mixing of dispersive shock waves and solitons observed here are universal features of dissipationless, dispersive hydrodynamic flows.

On the peculiar shapes of some pulsar bow-shock nebulae

NASA Astrophysics Data System (ADS)

Bandiera, Rino

Pulsar bow-shock nebulae are pulsar-wind nebulae formed by the direct interaction of pulsar relativistic winds with the interstellar medium. The bow-shock morphology, well outlined in Hα for some objects, is an effect of the supersonic pulsar motion with respect to the ambient medium. However, in a considerable fraction of cases (e.g. the nebulae associated to PSR B2224+65, PSR B0740-28, PSR J2124-3358) clear deviations from the classical bow shock shape are observed. Such deviations are usually interpreted as due to ambient density gradients and/or to pulsar-wind anisotropies. Here I present a different interpretation, aiming at explaining deviations from the standard morphology as signs of the peculiar physical conditions present in these objects. Using dimensional arguments, I show that, unlike normal pulsar-wind nebulae, in pulsar bow-shock nebulae the mean free path of the highest-energy particles may be comparable with the bow-shock head. I then investigate whether this may affect the shape of the bow-shock; for instance, whether a conical bow shock (like that observed in the "Guitar", the nebula associated to PSR B2224+65) does really imply an ambient density gradient. Finally, I discuss some other possible signatures of these high-energy, long mean-free-path particles.

Evolution of the shock front and turbulence structures in the shock/turbulence interaction

NASA Technical Reports Server (NTRS)

Kevlahan, N.; Mahesh, K.; Lee, S.

1992-01-01

The interaction of a weak shock front with isotropic turbulence has been investigated using Direct Numerical Simulation (DNS). Two problems were considered: the ability of the field equation (the equation for a propagating surface) to model the shock; and a quantitative study of the evolution of turbulence structure using the database generated by Lee et al. Field equation model predictions for front shape have been compared with DNS results; good agreement is found for shock wave interaction with 2D turbulence and for a single steady vorticity wave. In the interaction of 3D isotropic turbulence with a normal shock, strong alignment of vorticity with the intermediate eigenvector of the rate of strain tensor (S(sup *)(sub ij) = S(sub ij) - (1/3)(delta(sub ij))(S(sub kk))) is seen to develop upstream of the shock and to be further amplified on passage through the shock. Vorticity tends to align at 90 deg to the largest eigenvector, but there is no preferred alignment with the smallest eigenvector. Upstream of the shock, the alignments continue to develop even after the velocity derivative skewness saturates. There is a significant tendency, which increases with time throughout the computational domain, for velocity to align with vorticity. The alignment between velocity and vorticity is strongest in eddy regions and weakest in convergence regions.

Calculation of hypersonic shock structure using flux-split algorithms

NASA Technical Reports Server (NTRS)

Eppard, W. M.; Grossman, B.

1991-01-01

There exists an altitude regime in the atmosphere that is within the continuum domain, but wherein the conventional Navier-Stokes equations cease to be accurate. The altitude limits for this so called continuum transition regime depend on vehicle size and speed. Within this regime the thickness of the bow shock wave is no longer negligible when compared to the shock stand-off distance and the peak radiation intensity occurs within the shock wave structure itself. For this reason it is no longer valid to treat the shock wave as a discontinuous jump and it becomes necessary to compute through the shock wave itself. To accurately calculate hypersonic flowfields, the governing equations must be capable of yielding realistic profiles of flow variables throughout the structure of a hypersonic shock wave. The conventional form of the Navier-Stokes equations is restricted to flows with only small departures from translational equilibrium; it is for this reason they do not provide the capability to accurately predict hypersonic shock structure. Calculations in the continuum transition regime, therefore, require the use of governing equations other than Navier-Stokes. Several alternatives to Navier-Stokes are discussed; first for the case of a monatomic gas and then for the case of a diatomic gas where rotational energy must be included. Results are presented for normal shock calculations with argon and nitrogen.

The interaction of turbulence with parallel and perpendicular shocks

NASA Astrophysics Data System (ADS)

Adhikari, L.; Zank, G. P.; Hunana, P.; Hu, Q.

2016-11-01

Interplanetary shocks exist in most astrophysical flows, and modify the properties of the background flow. We apply the Zank et al 2012 six coupled turbulence transport model equations to study the interaction of turbulence with parallel and perpendicular shock waves in the solar wind. We model the 1D structure of a stationary perpendicular or parallel shock wave using a hyperbolic tangent function and the Rankine-Hugoniot conditions. A reduced turbulence transport model (the 4-equation model) is applied to parallel and perpendicular shock waves, and solved using a 4th- order Runge Kutta method. We compare the model results with ACE spacecraft observations. We identify one quasi-parallel and one quasi-perpendicular event in the ACE spacecraft data sets, and compute various turbulent observed values such as the fluctuating magnetic and kinetic energy, the energy in forward and backward propagating modes, the total turbulent energy in the upstream and downstream of the shock. We also calculate the error associated with each turbulent observed value, and fit the observed values by a least square method and use a Fourier series fitting function. We find that the theoretical results are in reasonable agreement with observations. The energy in turbulent fluctuations is enhanced and the correlation length is approximately constant at the shock. Similarly, the normalized cross helicity increases across a perpendicular shock, and decreases across a parallel shock.

Thermographic Phosphor Measurements of Shock-Shock Interactions on a Swept Cylinder

NASA Technical Reports Server (NTRS)

Jones, Michelle L.; Berry, Scott A.

2013-01-01

The effects of fin leading-edge radius and sweep angle on peak heating rates due to shock-shock interactions were investigated in the NASA Langley Research Center 20-inch Mach 6 Air Tunnel. The fin model leading edges, which represent cylindrical leading edges or struts on hypersonic vehicles, were varied from 0.25 inches to 0.75 inches in radius. A 9deg wedge generated a planar oblique shock at 16.7deg to the flow that intersected the fin bow shock, producing a shock-shock interaction that impinged on the fin leading edge. The fin angle of attack was varied from 0deg (normal to the free-stream) to 15deg and 25deg swept forward. Global temperature data was obtained from the surface of the fused silica fins using phosphor thermography. Metal oil flow models with the same geometries as the fused silica models were used to visualize the streamline patterns for each angle of attack. High-speed zoom-schlieren videos were recorded to show the features and temporal unsteadiness of the shock-shock interactions. The temperature data were analyzed using one-dimensional semi-infinite as well as one- and two-dimensional finite-volume methods to determine the proper heat transfer analysis approach to minimize errors from lateral heat conduction due to the presence of strong surface temperature gradients induced by the shock interactions. The general trends in the leading-edge heat transfer behavior were similar for the three shock-shock interactions, respectively, between the test articles with varying leading-edge radius. The dimensional peak heat transfer coefficient augmentation increased with decreasing leading-edge radius. The dimensional peak heat transfer output from the two-dimensional code was about 20% higher than the value from a standard, semi-infinite onedimensional method.

Experimental Investigation of Shock-Shock Interactions Over a 2-D Wedge at M=6

NASA Technical Reports Server (NTRS)

Jones, Michelle L.

2013-01-01

The effects of fin-leading-edge radius and sweep angle on peak heating rates due to shock-shock interactions were investigated in the NASA Langley Research Center 20-inch Mach 6 Air Tunnel. The fin model leading edges, which represent cylindrical leading edges or struts on hypersonic vehicles, were varied from 0.25 inches to 0.75 inches in radius. A 9deg wedge generated a planar oblique shock at 16.7deg to the flow that intersected the fin bow shock, producing a shock-shock interaction that impinged on the fin leading edge. The fin angle of attack was varied from 0deg (normal to the free-stream) to 15deg and 25deg swept forward. Global temperature data was obtained from the surface of the fused silica fins through phosphor thermography. Metal oil flow models with the same geometries as the fused silica models were used to visualize the streamline patterns for each angle of attack. High-speed zoom-schlieren videos were recorded to show the features and temporal unsteadiness of the shock-shock interactions. The temperature data were analyzed using one-dimensional semi-infinite as well as one- and two-dimensional finite-volume methods to determine the proper heat transfer analysis approach to minimize errors from lateral heat conduction due to the presence of strong surface temperature gradients induced by the shock interactions. The general trends in the leading-edge heat transfer behavior were similar for the three shock-shock interactions, respectively, between the test articles with varying leading-edge radius. The dimensional peak heat transfer coefficient augmentation increased with decreasing leading-edge radius. The dimensional peak heat transfer output from the two-dimensional code was about 20% higher than the value from a standard, semi-infinite one-dimensional method.

Shock interaction with deformable particles using a constrained interface reinitialization scheme

NASA Astrophysics Data System (ADS)

Sridharan, P.; Jackson, T. L.; Zhang, J.; Balachandar, S.; Thakur, S.

2016-02-01

In this paper, we present axisymmetric numerical simulations of shock propagation in nitromethane over an aluminum particle for post-shock pressures up to 10 GPa. We use the Mie-Gruneisen equation of state to describe both the medium and the particle. The numerical method is a finite-volume based solver on a Cartesian grid, that allows for multi-material interfaces and shocks, and uses a novel constrained reinitialization scheme to precisely preserve particle mass and volume. We compute the unsteady inviscid drag coefficient as a function of time, and show that when normalized by post-shock conditions, the maximum drag coefficient decreases with increasing post-shock pressure. We also compute the mass-averaged particle pressure and show that the observed oscillations inside the particle are on the particle-acoustic time scale. Finally, we present simplified point-particle models that can be used for macroscale simulations. In the Appendix, we extend the isothermal or isentropic assumption concerning the point-force models to non-ideal equations of state, thus justifying their use for the current problem.

An Atypical Case of Eosinophilic Gastroenteritis Presenting as Hypovolemic Shock

PubMed Central

Martillo, Miguel; Abed, Jean; Herman, Michael; Abed, Elie; Shi, Wenjing; Munot, Khushboo; Mankal, Pavan Kumar; Gurunathan, Rajan; Ionescu, Gabriel; Kotler, Donald P.

2015-01-01

Eosinophilic gastroenteritis is an uncommon condition characterized by focal or diffuse infiltration of eosinophils in the gastrointestinal tract in the absence of secondary causes. The pathogenesis of this condition is not well understood and its clinical presentation depends on the segment and layer of the gastrointestinal tract affected. The definition of eosinophilic gastroenteritis may be difficult, as the normal ranges of eosinophil numbers in normal and abnormal gastric and intestinal mucosa are not standardized. We present the case of a 59-year-old male who came to the hospital with hypovolemic shock and lethargy secondary to severe diarrhea. Laboratory analysis was significant for peripheral eosinophilia, and pathology from both the duodenum and colon showed marked eosinophilic infiltration. PMID:26078733

Effects of laser polarization on electrostatic shock ion acceleration in near-critical plasmas

NASA Astrophysics Data System (ADS)

Kim, Young-Kuk; Kang, Teyoun; Hur, Min Sup

2016-10-01

Collisionless electrostatic shock ion acceleration has become a major regime of laser-driven ion acceleration owing to generation of quasi-monoenergetic ion beams from moderate parametric conditions of lasers and plasmas in comparison with target-normal-sheath-acceleration or radiation pressure acceleration. In order to construct the shock, plasma heating is an essential condition for satisfying Mach number condition 1.5

Experimental Hypersonic Aerodynamic Characteristics of the 2001 Mars Surveyor Precision Lander with Flap

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; OConnell, Tod F.; Cheatwood, F. McNeil; Prabhu, Ramadas K.; Alter, Stephen J.

2002-01-01

Aerodynamic wind-tunnel screening tests were conducted on a 0.029 scale model of a proposed Mars Surveyor 2001 Precision Lander (70 deg half angle spherically blunted cone with a conical afterbody). The primary experimental objective was to determine the effectiveness of a single flap to trim the vehicle at incidence during a lifting hypersonic planetary entry. The laminar force and moment data, presented in the form of coefficients, and shock patterns from schlieren photography were obtained in the NASA Langley Aerothermodynamic Laboratory for post-normal shock Reynolds numbers (based on forebody diameter) ranging from 2,637 to 92,350, angles of attack ranging from 0 tip to 23 degrees at 0 and 2 degree sideslip, and normal-shock density ratios of 5 and 12. Based upon the proposed entry trajectory of the 2001 Lander, the blunt body heavy gas tests in CF, simulate a Mach number of approximately 12 based upon a normal shock density ratio of 12 in flight at Mars. The results from this experimental study suggest that when traditional means of providing aerodynamic trim for this class of planetary entry vehicle are not possible (e.g. offset c.g.), a single flap can provide similar aerodynamic performance. An assessment of blunt body aerodynamic effects attributed to a real gas were obtained by synergistic testing in Mach 6 ideal-air at a comparable Reynolds number. From an aerodynamic perspective, an appropriately sized flap was found to provide sufficient trim capability at the desired L/D for precision landing. Inviscid hypersonic flow computations using an unstructured grid were made to provide a quick assessment of the Lander aerodynamics. Navier-Stokes computational predictions were found to be in very good agreement with experimental measurement.

Molecular Dynamics Simulations of Shock Wave Propagation across the Nitromethane Crystal-Melt Interface

NASA Astrophysics Data System (ADS)

Jiang, Shan; Sewell, Thomas D.; Thompson, Donald L.

2015-06-01

We are interested in understanding the fundamental processes that occur during propagation of shock waves across the crystal-melt interface in molecular substances. We have carried out molecular dynamics simulations of shock passage from the nitromethane (100)-oriented crystal into the melt and vice versa using the fully flexible, non-reactive Sorescu, Rice, and Thompson force field. A stable interface was established for a temperature near the melting point by using a combination of isobaric-isothermal (NPT) and isochoric-isothermal (NVT) simulations. The equilibrium bulk and interfacial regions were characterized using spatial-temporal distributions of molecular number density, kinetic and potential energy, and C-N bond orientations. Those same properties were calculated as functions of time during shock propagation. As expected, the local temperatures (intermolecular, intramolecular, and total) and stress states differed significantly between the liquid and crystal regions and depending on the direction of shock propagation. Substantial differences in the spatial distribution of shock-induced defect structures in the crystalline region were observed depending on the direction of shock propagation. Research supported by the U.S. Army Research Office.

Control of quasi-monoenergetic electron beams from laser-plasma accelerators by adjusting shock density profile

NASA Astrophysics Data System (ADS)

Tsai, Hai-En; Swanson, Kelly K.; Lehe, Remi; Barber, Sam K.; Isono, Fumika; Otero, Jorge G.; Liu, Xinyao; Mao, Hann-Shin; Steinke, Sven; Tilborg, Jeroen Van; Geddes, Cameron G. R.; Leemans, Wim

2017-10-01

High-level control of a laser-plasma accelerator (LPA) using a shock injector was demonstrated by systematically varying the shock injector profile, including the shock angle, up-ramp width and shock position. Particle-in-cell (PIC) simulation explored how variations in the shock profile impacted the injection process and confirmed results obtained through acceleration experiments. These results establish that, by adjusting shock position, up-ramp, and angle, beam energy, energy spread, and pointing can be controlled. As a result, e-beam were highly tunable from 25 to 300 MeV with <8% energy spread, 1.5 mrad divergence and <1 mrad pointing fluctuation. This highly controllable LPA represents an ideal and compact beam source for the ongoing MeV Thomson photon experiments. Set-up and initial experimental design on a newly constructed one hundred TW laser system will be presented. This work is supported by the US DOE under Contract No. DE-AC02-05CH11231, and by the US DOE National Nuclear Security Administration, Defense Nuclear Nonproliferation R&D (NA22).

Free-piston driver performance characterisation using experimental shock speeds through helium

NASA Astrophysics Data System (ADS)

Gildfind, D. E.; James, C. M.; Morgan, R. G.

2015-03-01

Tuned free-piston driver operation involves configuring the driver to produce a relatively steady blast of driver gas over the critical time scales of the experiment. For the purposes of flow condition development and parametric studies, it is useful to establish some average working values of the driver pressure and temperature for a given driver operating condition. However, in practise, these averaged values need to produce sufficiently accurate estimates of performance. In this study, two tuned driver conditions in the X2 expansion tube have been used to generate shock waves through a helium test gas. The measured shock speeds have then been used to calculate the effective driver gas pressure and temperature after diaphragm rupture. Since the driver gas is typically helium, or a mixture of helium and argon, and the test gas is also helium, ideal gas assumptions can be made without significant loss of accuracy. The technique is applicable to tuned free-piston drivers with a simple area change, as well as those using orifice plates. It is shown that this technique can be quickly used to establish average working driver gas properties which produce very good estimates of actual driven shock speed, across a wide range of operating conditions. The use of orifice plates to control piston dynamics at high driver gas sound speeds is also discussed in the paper, and a simple technique for calculating the restriction required to modify an established safe condition for use with lighter gases, such as pure helium, is presented.

Extracorporeal cytokine elimination as rescue therapy in refractory septic shock: a prospective single-center study.

PubMed

Friesecke, Sigrun; Stecher, Stephanie-Susanne; Gross, Stefan; Felix, Stephan B; Nierhaus, Axel

2017-09-01

Sepsis is the most common cause of death in medical intensive care units (ICU). If sepsis progresses to refractory septic shock, mortality may reach 90-100% despite optimum current therapy. Extracorporeal cytokine adsorption in addition to regular therapy was studied prospectively in refractory septic shock patients on a medical ICU. Refractory shock was defined as increasing vasopressor dose required to maintain mean arterial blood pressure above 65 mmHg or increasing lactate levels despite protocol-guided shock therapy for 6 h. We analysed noradrenaline requirements after 6 and 12 h (primary endpoint), lactate clearance after 6 and 12 h, SOFA-scores in the first days and achievement of shock reversal (i.e., normalization of lactate concentrations and sustained discontinuation of vasopressors; secondary endpoints). Twenty consecutive patients with refractory septic shock were included; CytoSorb ® treatment was started after 7.8 ± 3.7 h of shock therapy. Following the initiation of adsorption therapy, noradrenaline dose could be significantly reduced after 6 (-0.4 µg/kg/min; p = 0.03) and 12 h (-0.6 µg/kg/min; p = 0.001). Lactate clearance improved significantly. SOFA-scores on day 0, 1 and 2 remained unchanged. Shock reversal was achieved in 13 (65%) patients; 28-day survival was 45%. In severe septic shock unresponsive to standard treatment, haemodynamic stabilization was achieved using cytokine adsorption therapy, resulting in shock reversal in two-thirds of these patients. The study was registered in the German Register for Clinical Trials (DRKS) No. 00005149.

Clinical characteristics, sepsis interventions and outcomes in the obese patients with septic shock: an international multicenter cohort study

PubMed Central

2013-01-01

Introduction Data are sparse as to whether obesity influences the risk of death in critically ill patients with septic shock. We sought to examine the possible impact of obesity, as assessed by body mass index (BMI), on hospital mortality in septic shock patients. Methods We performed a nested cohort study within a retrospective database of patients with septic shock conducted in 28 medical centers in Canada, United States and Saudi Arabia between 1996 and 2008. Patients were classified according to the World Health Organization criteria for BMI. Multivariate logistic regression analysis was performed to evaluate the association between obesity and hospital mortality. Results Of the 8,670 patients with septic shock, 2,882 (33.2%) had height and weight data recorded at ICU admission and constituted the study group. Obese patients were more likely to have skin and soft tissue infections and less likely to have pneumonia with predominantly Gram-positive microorganisms. Crystalloid and colloid resuscitation fluids in the first six hours were given at significantly lower volumes per kg in the obese and very obese patients compared to underweight and normal weight patients (for crystalloids: 55.0 ± 40.1 ml/kg for underweight, 43.2 ± 33.4 for normal BMI, 37.1 ± 30.8 for obese and 27.7 ± 22.0 for very obese). Antimicrobial doses per kg were also different among BMI groups. Crude analysis showed that obese and very obese patients had lower hospital mortality compared to normal weight patients (odds ratio (OR) 0.80, 95% confidence interval (CI) 0.66 to 0.97 for obese and OR 0.61, 95% CI 0.44 to 0.85 for very obese patients). After adjusting for baseline characteristics and sepsis interventions, the association became non-significant (OR 0.80, 95% CI 0.62 to 1.02 for obese and OR 0.69, 95% CI 0.45 to 1.04 for very obese). Conclusions The obesity paradox (lower mortality in the obese) documented in other populations is also observed in septic shock. This may be related in part to differences in patient characteristics. However, the true paradox may lie in the variations in the sepsis interventions, such as the administration of resuscitation fluids and antimicrobial therapy. Considering the obesity epidemic and its impact on critical care, further studies are warranted to examine whether a weight-based approach to common therapeutic interventions in septic shock influences outcome. PMID:23594407

Identification of a small heat-shock protein associated with a ras-mediated signaling pathway in ectomycorrhizal symbiosis

Treesearch

Shiv Hiremath; Kirsten Lehtoma; Gopi K. Podila

2009-01-01

Initiation, development, and establishment of a functional ectomycorrhiza involve a series of biochemical events mediated by a number of genes from the fungus as well as the host plant. We have identified a heat shock protein gene from Laccaria bicolor (Lbhsp) that appears to play a role in these events. The size and...

MMS Observation of Inverse Energy Dispersion in Shock Drift Acceleration Ions

NASA Astrophysics Data System (ADS)

Lee, S. H.; Sibeck, D. G.; Hwang, K. J.; Wang, Y.; Silveira, M. D.; Mauk, B.; Cohen, I. J.; Chu, C. S.; Mason, G. M.; Gold, R. E.; Burch, J. L.; Giles, B. L.; Torbert, R. B.; Russell, C. T.; Wei, H.

2016-12-01

The Energetic Particle Detector (EPD) on the Magnetospheric Multiscale (MMS) spacecraft observed bursts of energetic ions (50 keV-1000 keV) both in the foreshock and in the magnetosheath near the bow shock on December 6, 2015. Three species (protons, helium, and oxygen) exhibit inverse energy dispersions. Angular distributions for all three species indicate acceleration at the perpendicular bow shock. Acceleration that energizes the seed solar population by a factor of 2 and 4 is required for the protons and helium ions, respectively. The energy of the ions increases with θBn (the angle between the IMF and the local shock normal) since the induced electric field that energizes the charged particles increases as θBn increases towards 90°. We compare events upstream and downstream from the bow shock. We compare the MMS observations with those of the solar wind seed populations by the Ultra Low Energy Isotope Spectrometer (ULEIS) instrument on the Advanced Composition Explorer (ACE) mission and by the WIND 3-D Plamsa and Energetic Particle Experiment.

Evidence for specularly reflected ions upstream from the quasi-parallel bow shock

NASA Technical Reports Server (NTRS)

Gosling, J. T.; Thomsen, M. F.; Bame, S. J.; Feldman, W. C.; Paschmann, G.; Sckopke, N.

1982-01-01

Ion velocity distributions in the form of bunches of gyrating particles traveling along helical paths have been observed moving sunward immediately upstream from quasi-parallel parts of the earth's bow shock using Los Alamos/Garching instruments on ISEE-1 and -2. These distributions have characteristics which indicate that they are produced by the nearly specular reflection at the shock of a portion of the incident solar wind ions. In particular, the guiding center motion and the gyrospeeds of the gyrating ions are quantitatively consistent with simple geometrical considerations for specular reflection. These considerations reveal that specularly reflected ions can escape upstream when the angle between the upstream magnetic field and the local shock normal is less than 45 deg but not when the angle is greater than 45 deg. These upstream gyrating ions are an important signature of one of the processes by which solar wind streaming energy is dissipated into other forms of energy at the shock.

Multi-shock Shield Performance at 16.5 MJ for Catalogued Debris

NASA Technical Reports Server (NTRS)

Miller, J. E.; Christiansen, E. L.; Davis, B. A.

2014-01-01

While orbital debris of ten centimeters or more are tracked and catalogued, the difficulty of finding and accurately accounting for forces acting on the objects near the ten centimeter threshold results in both uncertainty of their presence and location. These challenges result in difficult decisions for operators balancing potential costly operational approaches with system loss risk. In this paper, numerical simulations and an experiment using the multi-shock shield system is described for a cylindrical projectile composed of Nylon, aluminum and void that is approximately 8 cm in diameter and 10 cm in length weighing 670 g impacting the multi-shock shield normal to the surface with approximately 16.5 MJ of kinetic energy. The multi-shock shield system has been optimized to facilitate the fragmentation, spread and deceleration of the projectile remnants using hydrodynamic simulations of the impact event. The characteristics and function of each of the layers of the multi-shock system will be discussed along with considerations for deployment and improvement.

[Effects of the escharectomy during burn shock stage on expression of glucose translator-4 mRNA in skeletal muscle and adipose tissue].

PubMed

Shuai, Xiu-rong; Liu, Tong-fa; Guo, Zhen-rong; Yu, Shun-xian; He, Peng-fei; Yuan, Wen-zhou; Li, Feng; He, Li-xin

2004-04-07

To investigate the effect of the escharectomy during burn shock stage on expression of glucose translator-4 (GLUT4) mRNA in skeletal muscle and adipose tissue. 30% TBSA scalded rats were employed. Escharectomy were conducted at 8 h, 24 h, 168 h after burns respectively. Insulin, glucagon, cortisol and glucose levels in serum were analyzed. RT-PCR were employed to analyze GLUT4 mRNA expression in skeletal muscle and adipose tissue. Glucagon, cortisol and glucose levels in serum were declined in groups which escharectomy were conducted during burn shock stage. GLUT4 mRNA expression in both skeletal muscle and adipose tissue were downregulated after burns and escharectomy conducted during burn shock stage made it restored to near normal. GLUT4 mRNA expression will declined after major burns in skeletal muscle and adipose tissue. Escharectomy during shock stage could make it upregulated, which will be helpful to improve glucose metabolism and hypermetabolism after major burns.

Mechanism analysis of Magnetohydrodynamic heat shield system and optimization of externally applied magnetic field

NASA Astrophysics Data System (ADS)

Li, Kai; Liu, Jun; Liu, Weiqiang

2017-04-01

As a novel thermal protection technique for hypersonic vehicles, Magnetohydrodynamic (MHD) heat shield system has been proved to be of great intrinsic value in the hypersonic field. In order to analyze the thermal protection mechanisms of such a system, a physical model is constructed for analyzing the effect of the Lorentz force components in the counter and normal directions. With a series of numerical simulations, the dominating Lorentz force components are analyzed for the MHD heat flux mitigation in different regions of a typical reentry vehicle. Then, a novel magnetic field with variable included angle between magnetic induction line and streamline is designed, which significantly improves the performance of MHD thermal protection in the stagnation and shoulder areas. After that, the relationships between MHD shock control and MHD thermal protection are investigated, based on which the magnetic field above is secondarily optimized obtaining better performances of both shock control and thermal protection. Results show that the MHD thermal protection is mainly determined by the Lorentz force's effect on the boundary layer. From the stagnation to the shoulder region, the flow deceleration effect of the counter-flow component is weakened while the flow deflection effect of the normal component is enhanced. Moreover, there is no obviously positive correlation between the MHD shock control and thermal protection. But once a good Lorentz force's effect on the boundary layer is guaranteed, the thermal protection performance can be further improved with an enlarged shock stand-off distance by strengthening the counter-flow Lorentz force right after shock.

Significance of heel pad confinement for the shock absorption at heel strike.

PubMed

Jørgensen, U; Ekstrand, J

1988-12-01

Shock absorption (SA) is a simple way to reduce the body load and can be used in the prevention and treatment of injuries. The heel pad is the most important shock absorber in the shoe heel complex. The purpose of this study was to investigate whether the SA at heel strike can be increased by heel support in people and shoes with high or low SA. The impact forces at heel strike were measured on an AMTI (R) force platform. Fourteen legs were tested in seven persons (nine with normal and five with low heel pad SA) in gait analysis and in human drop tests. The tests were performed barefooted, and in a soccer and a running shoe (selected by shoe drop test), with and without the distal 2 cm of the heel counter. The heel pad confinement produced by the heel counter (the heel counter effect) increased the SA in both shoe types significantly in both impact situations. The mean increase in SA was 8.8% (range 5.8%-15.5%). The heel counter effect was in all situations significantly higher in persons with low heel pad shock absorbency (LHPSA) than in those with normal heel pads. The barefoot impact peak force per kg body weight was significantly higher (6% mean) on the side with LHPSA. The running shoe provided the significantly greatest SA compared with the soccer shoe. It is concluded that the shock absorbency at heel strike can be increased significantly by heel support, with highest effect in persons with LHPSA, both in shoes with high and low SA.(ABSTRACT TRUNCATED AT 250 WORDS)

Self-sustained oscillations of a shock wave interacting with a boundary layer on a supercritical airfoil

NASA Technical Reports Server (NTRS)

Ventres, C. S.; Howe, M. S.

1984-01-01

A theory is proposed of the self-sustaining oscillations of a weak shock on an airfoi in steady, transonic flow. The interaction of the shock with the boundary layer on the airfoil produces displacement thickness fluctuations which convect downstream and generate sound by interaction with the trailing edge. A feedback loop is established when this sound impinges on the shock wave, resulting in the production of further fluctuations in the displacement thickness. The details are worked out for an idealized mean boundary layer velocity profile, but strong support for the basic hypotheses of the theory is provided by a comparison with recent experiments involving the generation of acoustic 'tone bursts' by a supercritical airfoil section.

Self-sustained oscillations of a shock wave interacting with a boundary layer on a supercritical airfoil

NASA Technical Reports Server (NTRS)

Ventres, C. S.; Howe, M. S.

1983-01-01

A theory is proposed of the self-sustaining oscillations of a weak shock on an airfoil in steady, transonic flow. The interaction of the shock with the boundary layer on the airfoil produces displacement thickness fluctuations which convect downstream and generate sound by interaction with the trailing edge. A feedback loop is established when this sound impinges on the shock wave, resulting in the production of further fluctuations in the displacement thickness. The details are worked out for an idealized mean boundary layer velocity profile, but strong support for the basic hypotheses of the theory is provided by a comparison with recent experiments involving the generation of acoustic "tone bursts' by a supercritical airfoil section.

Development Status of Low-Shock Payload Separation Mechanism for H-IIA Launch Vehicle

NASA Astrophysics Data System (ADS)

Terashima, Keita; Kamita, Toru; Horie, Youichi; Kobayashi, Masakazu; Onikura, Hiroki

2013-09-01

This paper presents the design, analysis and test results of the low-shock payload separation mechanism for the H-IIA launch vehicle. The mechanism is based on a simple and reliable four-bar linkage, which makes the release speed of the marman clamp band tension lower than the current system.The adequacy of the principle for low-shock mechanism was evaluated by some simulations and results of fundamental tests. Then, we established the reliability design model of this mechanism, and the adequacy of this model was evaluated by elemental tests.Finally, we conducted the system separation tests using the payload adapter to which the mechanism was assembled, to confirm that the actual separation shock level satisfied our target.

Afterbody Heating Characteristics of a Proposed Mars Sample Return Orbiter

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; Heiner, Nicholas C.; Olguin, Daniella M.; Cheatwood, F. McNeil; Gnoffo, Peter A.

2001-01-01

Aeroheating wind-tunnel tests were conducted on a 0.028 scale model of an orbiter concept considered for a possible Mars sample return mission. The primary experimental objectives were to characterize hypersonic near wake closure and determine if shear layer impingement would occur on the proposed orbiter afterbody at incidence angles necessary for a Martian aerocapture maneuver. Global heat transfer mappings, surface streamline patterns, and shock shapes were obtained in the NASA Langley 20-inch Mach 6 Air and CF4 Tunnels for post-normal shock Reynolds numbers (based on forebody diameter) ranging from 1,400 to 415,000, angles of attack ranging from -5 to 10 degrees at 0, 3, and 6 deg sideslip, and normal-shock density, ratios of 5 and 12. Laminar, transitional, and turbulent shear layer impingement on the cylindrical afterbody was inferred from the measurements and resulted in a localized heating maximum that ranged from 40 to 75% of the reference forebody stagnation point heating. Comparison of laminar heating prediction to experimental measurement along the orbiter afterbody highlight grid alignment challenges associated with numerical simulation of three-dimensional separated wake flows.

One-Dimensional Scanning Approach to Shock Sensing

NASA Technical Reports Server (NTRS)

Tokars, Roger; Adamovsky, Girgory; Floyd, Bertram

2009-01-01

Measurement tools for high speed air flow are sought both in industry and academia. Particular interest is shown in air flows that exhibit aerodynamic shocks. Shocks are accompanied by sudden changes in density, pressure, and temperature. Optical detection and characterization of such shocks can be difficult because the medium is normally transparent air. A variety of techniques to analyze these flows are available, but they often require large windows and optical components as in the case of Schlieren measurements and/or large operating powers which precludes their use for in-flight monitoring and applications. The one-dimensional scanning approach in this work is a compact low power technique that can be used to non-intrusively detect shocks. The shock is detected by analyzing the optical pattern generated by a small diameter laser beam as it passes through the shock. The optical properties of a shock result in diffraction and spreading of the beam as well as interference fringes. To investigate the feasibility of this technique a shock is simulated by a 426 m diameter optical fiber. Analysis of results revealed a direct correlation between the optical fiber or shock location and the beam s diffraction pattern. A plot of the width of the diffraction pattern vs. optical fiber location reveals that the width of the diffraction pattern was maximized when the laser beam is directed at the center of the optical fiber. This work indicates that the one-dimensional scanning approach may be able to determine the location of an actual shock. Near and far field effects associated with a small diameter laser beam striking an optical fiber used as a simulated shock are investigated allowing a proper one-dimensional scanning beam technique.

Global Aeroheating Measurements of Shock-Shock Interactions on a Swept Cylinder

NASA Technical Reports Server (NTRS)

Mason, Michelle L.; Berry, Scott A.

2015-01-01

The effects of fin leading-edge radius and sweep angle on peak heating rates due to shock-shock interactions were investigated in the NASA Langley Research Center 20-Inch Mach 6 Air Tunnel. The cylindrical leading-edge fin models, with radii varied from 0.25 to 0.75 inches, represent wings or struts on hypersonic vehicles. A 9deg wedge generated a planar oblique shock at 16.7deg. to the flow that intersected the fin bow shock, producing a shock-shock interaction that impinged on the fin leading edge. The fin sweep angle was varied from 0deg (normal to the free-stream) to 15deg and 25deg swept forward. These cases were chosen to explore three characterized shock-shock interaction types. Global temperature data were obtained from the surface of the fused silica fins using phosphor thermography. Metal oil flow models with the same geometries as the fused silica models were used to visualize the streamline patterns for each angle of attack. High-speed zoom-schlieren videos were recorded to show the features and any temporal unsteadiness of the shock-shock interactions. The temperature data were analyzed using a one-dimensional semi-infinite method, as well as one- and two-dimensional finite-volume methods. These results were compared to determine the proper heat transfer analysis approach to minimize errors from lateral heat conduction due to the presence of strong surface temperature gradients induced by the shock interactions. The general trends in the leading-edge heat transfer behavior were similar for each explored shock-shock interaction type regardless of the leading-edge radius. However, the dimensional peak heat transfer coefficient augmentation increased with decreasing leading-edge radius. The dimensional peak heat transfer output from the two-dimensional code was about 20% higher than the value from a standard, semi-infinite one-dimensional method.

An Approach Toward Synthesis of Bridgmanite in Dynamic Compression Experiments

NASA Astrophysics Data System (ADS)

Reppart, J. J.

2015-12-01

Bridgmanite occurs in heavily shocked meteorites and provides a useful constraint on pressure-temperature conditions during shock-metamorphism. Its occurrence also provides constraints on the shock release path. Shock-release and shock duration are important parameters in estimating the size of impactors that generate the observed shock metamorphic record. Thus, it is timely to examine if bridgmanite can be synthesized in dynamic compression experiments with the goal of establishing a correlation between shock duration and grainsize. Up to now only one high pressure polymorph of an Mg-silicate has been synthesized AND recovered in a shock experiment (wadsleyite). Therefore, it is not given that shock synthesis of bridgmanite is possible. This project started recently, so we present an outline of shock experiment designs and potentially results from the first experiments. FUNDING ACKNOWLEDGMENT UNLV HiPSEC: This research was sponsored (or sponsored in part) by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement #DE-NA0001982. HPCAT: "[Portions of this work were]/[This work was] performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357."

Adaptive magnetorheological seat suspension for shock mitigation

NASA Astrophysics Data System (ADS)

Singh, Harinder J.; Wereley, Norman M.

2013-04-01

An adaptive magnetorheological seat suspension (AMSS) was analyzed for optimal protection of occupants from shock loads caused by the impact of a helicopter with the ground. The AMSS system consists of an adaptive linear stroke magnetorheological shock absorber (MRSA) integrated into the seat structure of a helicopter. The MRSA provides a large controllability yield force to accommodate a wide spectrum for shock mitigation. A multiple degrees-of-freedom nonlinear biodynamic model for a 50th percentile male occupant was integrated with the dynamics of MRSA and the governing equations of motion were investigated theoretically. The load-stroke profile of MRSA was optimized with the goal of minimizing the potential for injuries. The MRSA yield force and the shock absorber stroke limitations were the most crucial parameters for improved biodynamic response mitigation. An assessment of injuries based on established injury criteria for different body parts was carried out.

Deformation behavior and spall fracture of the Hadfield steel under shock-wave loading

NASA Astrophysics Data System (ADS)

Gnyusov, S. F.; Rotshtein, V. P.; Polevin, S. D.; Kitsanov, S. A.

2011-03-01

Comparative studies of regularities in plastic deformation and fracture of the Hadfield polycrystalline steel upon quasi-static tension, impact failure, and shock-wave loading with rear spall are performed. The SINUS-7 accelerator was used as a shock-wave generator. The electron beam parameters of the accelerator were the following: maximum electron energy was 1.35 MeV, pulse duration at half-maximum was 45 ns, maximum energy density on a target was 3.4·1010 W/cm2, shock-wave amplitude was ~20 GPa, and strain rate was ~106 s-1. It is established that the failure mechanism changes from ductile transgranular to mixed ductile-brittle intergranular one when going from quasi-static tensile and Charpy impact tests to shock-wave loading. It is demonstrated that a reason for the intergranular spallation is the strain localization near the grain boundaries containing a carbide interlayer.

The size effects upon shock plastic compression of nanocrystals

NASA Astrophysics Data System (ADS)

Malygin, G. A.; Klyavin, O. V.

2017-10-01

For the first time a theoretical analysis of scale effects upon the shock plastic compression of nanocrystals is implemented in the context of a dislocation kinetic approach based on the equations and relationships of dislocation kinetics. The yield point of crystals τy is established as a quantitative function of their cross-section size D and the rate of shock deformation as τy ɛ2/3 D. This dependence is valid in the case of elastic stress relaxation on account of emission of dislocations from single-pole Frank-Read sources near the crystal surface.

Deviatoric response of the aluminium alloy, 5083

NASA Astrophysics Data System (ADS)

Appleby-Thomas, Gareth; Hazell, Paul; Millett, Jeremy; Bourne, Neil

2009-06-01

Aluminium alloys such as 5083 are established light weight armour materials. As such, the shock response of these materials is of great importance. The shear strength of a material under shock loading provides an insight into its ballistic performance. In this investigation embedded manganin stress gauges have been employed to measure both the longitudinal and lateral components of stress during plate impact experiments over a range of impact stresses. In turn, these results were used to determine the shear strength and to investigate the time dependence of lateral stress behind the shock front to give an indication of material response.

Deviatoric Response of AN Armour-Grade Aluminium Alloy

NASA Astrophysics Data System (ADS)

Appleby-Thomas, G. J.; Hazell, P. J.; Millett, J.; Bourne, N. K.

2009-12-01

Aluminium alloys such as 5083 H32 are established light-weight armour materials. As such, the shock response of these materials is of great importance. The shear strength of a material under shock loading provides an insight into its ballistic performance. In this investigation embedded manganin stress gauges have been employed to measure both the longitudinal and lateral components of stress during plate-impact experiments over a range of impact stresses. In turn, these results were used to determine the shear strength and to investigate the time dependence of lateral stress behind the shock front to give an indication of material response.

Energetic storm particle events in the outer heliosphere

NASA Technical Reports Server (NTRS)

Mcdonald, F.; Trainor, J.; Mihalov, J.; Wolfe, J.; Webber, W.

1981-01-01

The evolution of energetic particle events with increasing heliocentric distance is studied through events of Pioneers 10 and 11. Beyond 12 AU the events become the dominant type of solar particle event at 1 AU, and the combined effects of adiabatic cooling and volume expansion rule out the possibility that the particles represent the confinement of the original particle population behind the shock. It is not established whether the particles originate from the solar wind by injection via post-shock enhancements or are energetic solar particles further energized by the shock, although their very long lifetime favors the solar wind origin.

Multiple Launch Rocket System (MLRS) Fuze.

DTIC Science & Technology

1982-06-18

8217This is to be expected, since the probes are near the axis of symmetry 08 (where the bow shock wave is most nearly normal) and, being Pitot probes ...that simulated altitudes from 15.2 Km to 21 Km. The fuze ogive was instrumented with both static and pitot pressure probes , from which the pressure data...insights into the flow. Because the bow shock wave is curved, the static-pressure on the-- .urface should decrease from avalue__ of the stagnation pressure

Comparisons of Normal Saline and Lactated Ringer’s Resuscitation on Hemodynamics, Metabolic Responses, and Coagulation in Pigs after Severe Hemorrhagic Shock

DTIC Science & Technology

2013-12-11

vasodilator effects and the risks of metabolic acidosis and hyperkalemia . Keywords: Hemorrhagic shock, Oxygen metabolism, Coagulation, Pre-hospital...www.sjtrem.com/content/21/1/86 of hyperchloremic acidosis from NS resuscitation [37]. Consistent with our current results, clinically significant hyperkalemia ...risks of meta- bolic acidosis and hyperkalemia . Currently, military first responders have NS, LR and Hextend available [20]. How- ever, the results from

The Shock and Vibration Digest. Volume 12, Number 10,

DTIC Science & Technology

1980-10-01

according to the various behavior stress limits of the ASME code. 80-2289 Tranmition of an Oscillating Incompressible Flow in a Pipe or in a Boundary...a Normal Shock Wave Contained limits are also presented, in an Aerodynamic Inlet ( Pulsation d’un Choc Droit en Aerodynamique Interne) A. Agnes, E...Department of Defense applauded this effort and called for lAG operations that are strongly oriented toward user needs. This is very encouraging, but

The heat shock response and major heat shock proteins of Tritrichomonas mobilensis and Tritrichomonas augusta.

PubMed

Bozner, P

1996-02-01

The responses to heat shock in Tritrichomonas mobilensis, a squirrel monkey parasite and Tritrichomonas augusta, an amphibian trichomonad, were evaluated by means of metabolic labeling with [35S]methionine. Electrophoretically separated trichomonad proteins synthesized at different temperatures were visualized by autoradiography and the label incorporation quantitated by a trichloroacetic acid precipitation procedure. A considerable difference in thermotolerance between the two species was found as the protein synthesis reached a maximum at 41 C in T. mobilensis and 37 C in T. augusta. The latter tolerated temperature increases 13 C above normal cultivation temperatures as compared to only 4 C thermotolerance range above normal in T. mobilensis. Major heat shock proteins (Hsps) were expressed in both T. mobilensis (with apparent Mr 94, 72, and 58 kDa) and T. augusta (Mr 94, 70, and 56 kDa) as revealed by autoradiography. Western blot analysis with polyclonal antibody against DnaK of Escherichia coli showed the presence of antigenic Hsp70 homologs in both trichomonads. Similarly, a polyclonal antibody against Hsp60 with broad interspecies cross-reactivity detected Hsp60 homologs in both T. mobilensis and T. augusta. The anti-DnaK antibody cross-reacted with a T. mobilensis protein localized in Golgi apparatus as demonstrated by immunoelectron microscopy. Immunocytochemistry on trichomonad frozen sections revealed the presence of the Hsp60 homolog in light-microscopic granules corresponding to hydrogenosomes.

Heat shock protein 70 from a thermotolerant Diptera species provides higher thermoresistance to Drosophila larvae than correspondent endogenous gene.

PubMed

Shilova, V Y; Zatsepina, O G; Garbuz, D G; Funikov, S Y; Zelentsova, E S; Schostak, N G; Kulikov, A M; Evgen'ev, M B

2018-02-01

Heat shock proteins (Hsp70s) from two Diptera species that drastically differ in their heat shock response and longevity were investigated. Drosophila melanogaster is characterized by the absence of Hsp70 and other hsps under normal conditions and the dramatic induction of hsp synthesis after temperature elevation. The other Diptera species examined belongs to the Stratiomyidae family (Stratiomys singularior) and exhibits high levels of inducible Hsp70 under normal conditions coupled with a thermotolerant phenotype and much longer lifespan. To evaluate the impact of hsp70 genes on thermotolerance and longevity, we made use of a D. melanogaster strain that lacks all hsp70 genes. We introduced single copies of either S. singularior or D. melanogaster hsp70 into this strain and monitored the obtained transgenic flies in terms of thermotolerance and longevity. We developed transgenic strains containing the S. singularior hsp70 gene under control of a D. melanogaster hsp70 promoter. Although these adult flies did synthesize the corresponding mRNA after heat shock, they were not superior to the flies containing a single copy of D. melanogaster hsp70 in thermotolerance and longevity. By contrast, Stratiomyidae Hsp70 provided significantly higher thermotolerance at the larval stage in comparison with endogenous Hsp70. © 2017 The Royal Entomological Society.

Experimental exploration of underexpanded supersonic jets

NASA Astrophysics Data System (ADS)

André, Benoît; Castelain, Thomas; Bailly, Christophe

2014-01-01

Two underexpanded free jets at fully expanded Mach numbers = 1.15 and 1.50 are studied. Schlieren visualizations as well as measurements of static pressure, Pitot pressure and velocity are performed. All these experimental techniques are associated to obtain an accurate picture of the jet flow development. In particular, expansion, compression and neutral zones have been identified in each shock cell. Particle lag is considered by integrating the equation of motion for particles in a fluid flow and it is found that the laser Doppler velocimetry is suitable for investigating shock-containing jets. Even downstream of the normal shock arising in the = 1.50 jet, the measured gradual velocity decrease is shown to be relevant.

Complex flow morphologies in shock-accelerated gaseous flows

NASA Astrophysics Data System (ADS)

Kumar, S.; Vorobieff, P.; Orlicz, G.; Palekar, A.; Tomkins, C.; Goodenough, C.; Marr-Lyon, M.; Prestridge, K. P.; Benjamin, R. F.

2007-11-01

A Mach 1.2 planar shock wave impulsively and simultaneously accelerates a row of three heavy gas (SF 6) cylinders surrounded by a lighter gas (air), producing pairs of vortex columns. The heavy gas cylinders (nozzle diameter D) are initially equidistant in the spanwise direction (center to center spacing S), with S/D=1.5. The interaction of the vortex columns is investigated with planar laser-induced fluorescence (PLIF) in the plane normal to the axes of the cylinders. Several distinct post-shock morphologies are observed, apparently due to rather small variations of the initial conditions. We report the variation of the streamwise and spanwise growth rates of the integral scales for these flow morphologies.

Mapping the magnetosheath field between the magnetopause and the bow shock - Implications for magnetospheric particle leakage

NASA Technical Reports Server (NTRS)

Luhmann, J. G.; Walker, R. J.; Russell, C. T.; Spreiter, J. R.; Stahara, S. S.; Williams, D. J.

1984-01-01

An approximate picture of the volumes occupied by particles that originate in the vicinity of the magnetopause is obtained by mapping magnetosheath magnetic field lines which drape over the magnetopause through the bow shock. Subsets of these field lines that connect to potential sites of magnetic merging on the magnetopause are also traced in the event that the particle leakage occurs preferentially where normal components of the field are present across that boundary. The results of this modeling exercise suggest that energetic magnetospheric particles which are not scattered by magnetosheath magnetic fluctuations are likely to exit the magnetosheath in the region of the quasi-parallel shock.

[The evolution of heat shock genes and expression patterns of heat shock proteins in the species from temperature contrasting habitats].

PubMed

Garbuz, D G; Evgen’ev, M B

2017-01-01

Heat shock genes are the most evolutionarily ancient among the systems responsible for adaptation of organisms to a harsh environment. The encoded proteins (heat shock proteins, Hsps) represent the most important factors of adaptation to adverse environmental conditions. They serve as molecular chaperones, providing protein folding and preventing aggregation of damaged cellular proteins. Structural analysis of the heat shock genes in individuals from both phylogenetically close and very distant taxa made it possible to reveal the basic trends of the heat shock gene organization in the context of adaptation to extreme conditions. Using different model objects and nonmodel species from natural populations, it was demonstrated that modulation of the Hsps expression during adaptation to different environmental conditions could be achieved by changing the number and structural organization of heat shock genes in the genome, as well as the structure of their promoters. It was demonstrated that thermotolerant species were usually characterized by elevated levels of Hsps under normal temperature or by the increase in the synthesis of these proteins in response to heat shock. Analysis of the heat shock genes in phylogenetically distant organisms is of great interest because, on one hand, it contributes to the understanding of the molecular mechanisms of evolution of adaptogenes and, on the other hand, sheds the light on the role of different Hsps families in the development of thermotolerance and the resistance to other stress factors.

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak

2005-07-01

Explosives formulations with Reduced- Sensitivity RDX showed reduced shock sensitivity using NOL Large Scale Gap Test, compared with similar formulations using normal RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light to the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. SIRDX, a form of Reduced- Sensitivity RDX, was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transformed IR (FTIR). The pressure dependence of the Raman mode frequencies of SIRDX was determined and compared with that of normal RDX. The behavior of SIRDX near the pressure at which normal RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph will be presented. Implications to the reduction in sensitivity will be discussed.

Shocked Quartz Aggregates of the Cretaceous-Tertiary Boundary at Colorado, USA

NASA Astrophysics Data System (ADS)

Miura, Y.; Okamoto, M.; Iancu, O. G.

1993-07-01

Shock-metamorphosed quartz (i.e., shocked quartz) at the Cretaceous-Tertiary boundary (K/T) at Colorado [1,2] reveals the following mineralogical data by X-ray diffractometry and high-resolution electron micrograph with energy- dispersive spectrometry. 1. Shocked quartz is not normal (perfect crystalline) quartz mineral but various quartz aggregates that show relatively low X-ray intensity (i.e., imperfect crystalline) and shock lamellae with crystalline quartz and amorphous glass [3]. 2. Analytical electron micrographs indicate that crystalline quartz silica with spotty dislocation features is included in dendritic amorphous glasses of potassium (K) feldspar composition. Various compositions of glassy materials are found in shocked quartz aggregates as matrix or alternate shock lamellae, which is important to estimate the target rock of impact. The composition of glassy matrix is dendritic K-feldspar in the K/T boundary at Clear Creak North (CCN), Colorado, whereas that in the Barringer Crater is quartz-rich composition from the target rock of sandstone (or some mixture with iron meteorite), and that in artificial impact rock [3] is dendritic silica composition. It is found in this study that shocked quartz aggregates from the CCN K/T boundary samples are supplied from quartz and K-feldspar-bearing target rock at impact event (Table 1). Table 1, which appears here in the hard copy, shows the compositions, texture, and origin of shocked quartz aggregates. References: [1] Alvarez L. W. et al. (1980) Science, 208, 1095-1107. [2] Izett G. (1989) GSA Spec. Pap. 249, 1-194. [3] Miura Y. (1991) Shock Waves, 1, 35-41, Springer-Verlag.

Dexamethasone Injection

MedlinePlus

... severe allergic reactions. It is used in the management of certain types of edema (fluid retention and ... needed for normal body functioning) and in the management of certain types of shock. Dexamethasone injection is ...

Shock response of nanoporous Cu--A molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Zhao, Fengpeng

2015-06-01

Shock response of porous materials can be of crucial significance for shock physics and bears many practical applications in materials synthesis and engineering. Molecular dynamics simulations are carried out to investigate shock response of nanoporous metal materials, including elastic-plastic deformation, Hugoniot states, shock-induced melting, partial or complete void collapse, hotspot formation, nanojetting, and vaporization. A model nanoporous Cu with cylindrical voids and a high porosity under shocking is established to investigate such physical properties as velocity, temperature, density, stress and von Mises stress at different stages of compression and release. The elastic-plastic and overtaking shocks are observed at different shock strengths. A modified power-law P- α model is proposed to describe the Hugoniot states. The Grüneisen equation of state is validated. Shock-induced melting shows no clear signs of bulk premelting or superheating. Void collapse via plastic flow nucleated from voids, and the exact processes are shock strength dependent. With increasing shock strengths, void collapse transits from the ``geometrical'' mode (collapse of a void is dominated by crystallography and void geometry and can be different from that of one another) to ``hydrodynamic'' mode (collapse of a void is similar to one another). The collapse may be achieved predominantly by plastic flows along the {111} slip planes, by way of alternating compression and tension zones, by means of transverse flows, via forward and transverse flows, or through forward nano-jetting. The internal jetting induces pronounced shock front roughening, leading to internal hotspot formation and sizable high speed jets on atomically flat free surfaces. P. O. Box 919-401, Mianyang, 621900, Sichuan, PRC.

Analysis of the interaction of a weak normal shock wave with a turbulent boundary layer

NASA Technical Reports Server (NTRS)

Melnik, R. E.; Grossman, B.

1974-01-01

The method of matched asymptotic expansions is used to analyze the interaction of a normal shock wave with an unseparated turbulent boundary layer on a flat surface at transonic speeds. The theory leads to a three-layer description of the interaction in the double limit of Reynolds number approaching infinity and Mach number approaching unity. The interaction involves an outer, inviscid rotational layer, a constant shear-stress wall layer, and a blending region between them. The pressure distribution is obtained from a numerical solution of the outer-layer equations by a mixed-flow relaxation procedure. An analytic solution for the skin friction is determined from the inner-layer equations. The significance of the mathematical model is discussed with reference to existing experimental data.

Estimates of thermochemical relaxation lengths behind normal shock waves relevant to manned lunar and Mars return missions, the aeroassist flight experiment, and Mars entry

NASA Technical Reports Server (NTRS)

Howe, John T.

1991-01-01

Thermochemical relaxation distances behind the strong normal shock waves associated with vehicles that enter the Earth atmosphere upon returning from a manned lunar or Mars mission are estimated. The relaxation distances for a Mars entry are estimated as well, in order to highlight the extent of the relaxation phenomena early in currently envisioned space exploration studies. The thermochemical relaxation length for the Aeroassist Flight Experiment is also considered. These estimates provide an indication as to whether finite relaxation needs to be considered in subsequent detailed analyses. For the Mars entry, relaxation phenomena that are fully coupled to the flow field equations are used. The relaxation-distance estimates can be scaled to flight conditions other than those discussed.

Liquid phase evaporation on the normal shock wave in moist air transonic flows in nozzles

NASA Astrophysics Data System (ADS)

Dykas, Sławomir; Szymański, Artur; Majkut, Mirosław

2017-06-01

This paper presents a numerical analysis of the atmospheric air transonic flow through de Laval nozzles. By nature, atmospheric air always contains a certain amount of water vapor. The calculations were made using a Laval nozzle with a high expansion rate and a convergent-divergent (CD) "half-nozzle", referred to as a transonic diffuser, with a much slower expansion rate. The calculations were performed using an in-house CFD code. The computational model made it possible to simulate the formation of the liquid phase due to spontaneous condensation of water vapor contained in moist air. The transonic flow calculations also take account of the presence of a normal shock wave in the nozzle supersonic part to analyze the effect of the liquid phase evaporation.

Analysis of differential protein expression in normal and neoplastic human breast epithelial cell lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, K.; Chubb, C.; Huberman, E.

High resolution two dimensional get electrophoresis (2DE) and database analysis was used to establish protein expression patterns for cultured normal human mammary epithelial cells and thirteen breast cancer cell lines. The Human Breast Epithelial Cell database contains the 2DE protein patterns, including relative protein abundances, for each cell line, plus a composite pattern that contains all the common and specifically expressed proteins from all the cell lines. Significant differences in protein expression, both qualitative and quantitative, were observed not only between normal cells and tumor cells, but also among the tumor cell lines. Eight percent of the consistently detected proteinsmore » were found in significantly (P < 0.001) variable levels among the cell lines. Using a combination of immunostaining, comigration with purified protein, subcellular fractionation, and amino-terminal protein sequencing, we identified a subset of the differentially expressed proteins. These identified proteins include the cytoskeletal proteins actin, tubulin, vimentin, and cytokeratins. The cell lines can be classified into four distinct groups based on their intermediate filament protein profile. We also identified heat shock proteins; hsp27, hsp60, and hsp70 varied in abundance and in some cases in the relative phosphorylation levels among the cell lines. Finally, we identified IMP dehydrogenase in each of the cell lines, and found the levels of this enzyme in the tumor cell lines elevated 2- to 20-fold relative to the levels in normal cells.« less

Septic shock sera containing circulating histones induce dendritic cell-regulated necrosis in fatal septic shock patients.

PubMed

Raffray, Loic; Douchet, Isabelle; Augusto, Jean-Francois; Youssef, Jihad; Contin-Bordes, Cecile; Richez, Christophe; Duffau, Pierre; Truchetet, Marie-Elise; Moreau, Jean-Francois; Cazanave, Charles; Leroux, Lionel; Mourrissoux, Gaelle; Camou, Fabrice; Clouzeau, Benjamin; Jeannin, Pascale; Delneste, Yves; Gabinski, Claude; Guisset, Olivier; Lazaro, Estibaliz; Blanco, Patrick

2015-04-01

Innate immune system alterations, including dendritic cell loss, have been reproducibly observed in patients with septic shock and correlated to adverse outcomes or nosocomial infections. The goal of this study is to better understand the mechanisms behind this observation in order to better assess septic shock pathogenesis. Prospective, controlled experimental study. Research laboratory at an academic medical center. The study enrolled 71 patients, 49 with septic shock and 22 with cardiogenic shock. Seventeen healthy controls served as reference. In vitro monocyte-derived dendritic cells were generated from healthy volunteers. Sera were assessed for their ability to promote in vitro dendritic cell death through flow cytometry detection in each group of patients. The percentage of apoptotic or necrotic dendritic cells was evaluated by annexin-V and propidium iodide staining. We observed that only patients with septic shock and not patients with pure cardiogenic shock were characterized by a rapid and profound loss of circulating dendritic cells. In vitro analysis revealed that sera from patients with septic shock induced higher dendritic cell death compared to normal sera or cardiogenic shock (p<0.005). Sera from surviving patients induced dendritic cell death through a caspase-dependent apoptotic pathway, whereas sera from nonsurviving patients induced dendritic cell-regulated necrosis. Dendritic cell necrosis was not due to necroptosis but was dependent of the presence of circulating histone. The toxicity of histones toward dendritic cell could be prevented by recombinant human activated protein C. Finally, we observed a direct correlation between the levels of circulating histones in patients and the ability of the sera to promote dendritic cell-regulated necrosis. The study demonstrates a differential mechanism of dendritic cell death in patients with septic shock that is dependent on the severity of the disease.

Laser Light Scattering by Shock Waves

NASA Technical Reports Server (NTRS)

Panda, J.; Adamovsky, G.

1995-01-01

Scattering of coherent light as it propagates parallel to a shock wave, formed in front of a bluff cylindrical body placed in a supersonic stream, is studied experimentally and numerically. Two incident optical fields are considered. First, a large diameter collimated beam is allowed to pass through the shock containing flow. The light intensity distribution in the resultant shadowgraph image, measured by a low light CCD camera, shows well-defined fringes upstream and downstream of the shadow cast by the shock. In the second situation, a narrow laser beam is brought to a grazing incidence on the shock and the scattered light, which appears as a diverging sheet from the point of interaction, is visualized and measured on a screen placed normal to the laser path. Experiments are conducted on shocks formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the shock shadows in a shadowgraph image become independent of M and P(sub 0) when plotted against the jump in the refractive index, (Delta)n, created across the shock. The total scattered light measured from the narrow laser beam and shock interaction also follows the same trend. In the numerical part of the study, the shock is assumed to be a 'phase object', which introduces phase difference between the upstream and downstream propagating parts of the light disturbances. For a given shape and (Delta)n of the bow shock the phase and amplitude modulations are first calculated by ray tracing. The wave front is then propagated to the screen using the Fresnet diffraction equation. The calculated intensity distribution, for both of the incident optical fields, shows good agreement with the experimental data.

Testing continuum descriptions of low-Mach-number shock structures

NASA Technical Reports Server (NTRS)

Pham-Van-diep, Gerald C.; Erwin, Daniel A.; Muntz, E. P.

1991-01-01

Numerical experiments have been performed on normal shock waves with Monte Carlo Direct Simulations (MCDS's) to investigate the validity of continuum theories at very low Mach numbers. Results from the Navier-Stokes and the Burnett equations are compared to MCDS's for both hard-sphere and Maxwell gases. It is found that the maximum-slope shock thicknesses are described equally well (within the MCDS computational scatter) by either of the continuum formulations for Mach numbers smaller than about 1.2. For Mach numbers greater that 1.2, the Burnett predictions are more accurate than the Navier-Stokes results. Temperature-density profile separations are best described by the Burnett equations for Mach numbers greater than about 1.3. At lower Mach numbers the MCDS scatter is too great to differentiate between the two continuum theories. For all Mach numbers above one, the shock shapes are more accurately described by the Burnett equations.

[Bacterial toxic shock as a complication of calculous pyelonephritis].

PubMed

Lopatkin, N A; Rumiantsev, V B; Ianenko, E K

1994-01-01

The causes of bacteriotoxic shock were examined in 33 patients (11 lethal outcomes). It has arisen as a complication of treatment given to 7830 patients for urolithiasis. Aggravation of chronic pyelonephritis, occlusion of the urinary tracts, urogenital mucosal and parenchymal injuries, low resistance to infection contribute to microbacteria and their toxins entering blood with resultant bacteriotoxic shock. Transcutaneous operative interventions, therapeutic and diagnostic procedures also produce high risk of blood infection with gram-negative microflora, especially in violation of asepsis and antisepsis rules. As shown by microflora tests, the dominating bacteria consisted of opportunistic agents which had acquired the resistance to antibacterial drugs. In view of rapid progression of bacteriotoxic shock therapeutic efforts should be concentrated on fast normalization of hemodynamics, recovery of urine passage, introduction of sorption detoxication, prevention of DIC syndrome. The schemes of combined antibiotic treatment adjusted to the kind of infectious agent are suggested.

Developmentally regulated expression of APG-1, a member of heat shock protein 110 family in murine male germ cells.

PubMed

Kaneko, Y; Kimura, T; Nishiyama, H; Noda, Y; Fujita, J

1997-04-07

Apg-1 encodes a heat shock protein belonging to the heat shock protein 110 family, and is inducible by a 32 degrees C to 39 degrees C heat shock. Northern blot analysis of the testis from immature and adult mice, and of the purified germ cells revealed the quantitative change of the apg-1 transcripts during germ cell development. By in situ hybridization histochemistry the expressions of the apg-1 transcripts were detected in germ cells at specific stages of development including spermatocytes and spermatids. Although heat-induction of the apg-1 transcripts was observed in W/Wv mutant testis lacking germ cells, it was not detected in wild-type testis nor in the purified germ cells. Thus, the apg-1 expression is not heat-regulated but developmentally regulated in germ cells, suggesting that APG-1 plays a role in normal development of germ cells.

Convective response of a wall-mounted hot-film sensor in a shock tube

NASA Technical Reports Server (NTRS)

Roberts, A. Sidney, Jr.; Ortgies, Kelly R.; Gartenberg, Ehud; Carraway, Debra L.

1991-01-01

Shock tube experiments were performed in order to determine the response of a single hot-film element of a sensor array to transiently induced flow behind weak normal shock waves. The experiments attempt to isolate the response due only to the change in convective heat transfer at the hot-film surface mounted on the wall of the shock tube. The experiments are described, the results being correlated with transient boundary layer theory and compared with an independent set of experimental results. One of the findings indicates that the change in the air properties (temperature and pressure) precedes the air mass transport, causing an ambiguity in the sensor response to the development of the velocity boundary layer. Also, a transient, local heat transfer coefficient is formulated to be used as a forcing function in an hot-film instrument model and simulation which remains under investigation.

High strain rate deformation and fracture of the magnesium alloy Ma2-1 under shock wave loading

NASA Astrophysics Data System (ADS)

Garkushin, G. V.; Kanel', G. I.; Razorenov, S. V.

2012-05-01

This paper presents the results of measurements of the dynamic elastic limit and spall strength under shock wave loading of specimens of the magnesium alloy Ma2-1 with a thickness ranging from 0.25 to 10 mm at normal and elevated (to 550°C) temperatures. From the results of measurements of the decay of the elastic precursor of a shock compression wave, it has been found that the plastic strain rate behind the front of the elastic precursor decreases from 2 × 105 s-1 at a distance of 0.25 mm to 103 s-1 at a distance of 10 mm. The plastic strain rate in a shock wave is one order of magnitude higher than that in the elastic precursor at the same value of the shear stress. The spall strength of the alloy decreases as the solidus temperature is approached.

Nonthermal ions and associated magnetic field behavior at a quasi-parallel earth's bow shock

NASA Technical Reports Server (NTRS)

Wilkinson, W. P.; Pardaens, A. K.; Schwartz, S. J.; Burgess, D.; Luehr, H.; Kessel, R. L.; Dunlop, M.; Farrugia, C. J.

1993-01-01

Attention is given to ion and magnetic field measurements at the earth's bow shock from the AMPTE-UKS and -IRM spacecraft, which were examined in high time resolution during a 45-min interval when the field remained closely aligned with the model bow shock normal. Dense ion beams were detected almost exclusively in the midst of short-duration periods of turbulent magnetic field wave activity. Many examples of propagation at large elevation angles relative to the ecliptic plane, which is inconsistent with reflection in the standard model shock configuration, were discovered. The associated waves are elliptically polarized and are preferentially left-handed in the observer's frame of reference, but are less confined to the maximum variance plane than other previously studied foreshock waves. The association of the wave activity with the ion beams suggests that the former may be triggered by an ion-driven instability, and possible candidates are discussed.

The effects of micro-vortex generators on normal shock wave/boundary layer interactions

NASA Astrophysics Data System (ADS)

Herges, Thomas G.

Shock wave/boundary-layer interactions (SWBLIs) are complex flow phenomena that are important in the design and performance of internal supersonic and transonic flow fields such as engine inlets. This investigation was undertaken to study the effects of passive flow control devices on normal shock wave/boundary layer interactions in an effort to gain insight into the physics that govern these complex interactions. The work concentrates on analyzing the effects of vortex generators (VGs) as a flow control method by contributing a greater understanding of the flowfield generated by these devices and characterizing their effects on the SWBLI. The vortex generators are utilized with the goal of improving boundary layer health (i.e., reducing/increasing the boundary-layer incompressible shape factor/skin friction coefficient) through a SWBLI, increasing pressure recovery, and reducing flow distortion at the aerodynamic interface plane while adding minimal drag to the system. The investigation encompasses experiments in both small-scale and large-scale inlet testing, allowing multiple test beds for improving the characterization and understanding of vortex generators. Small-scale facility experiments implemented instantaneous schlieren photography, surface oil-flow visualization, pressure-sensitive paint, and particle image velocimetry to characterize the effects of an array of microramps on a normal shock wave/boundary-layer interaction. These diagnostics measured the time-averaged and instantaneous flow organization in the vicinity of the microramps and SWBLI. The results reveal that a microramp produces a complex vortex structure in its wake with two primary counter-rotating vortices surrounded by a train of Kelvin- Helmholtz (K-H) vortices. A streamwise velocity deficit is observed in the region of the primary vortices in addition to an induced upwash/downwash which persists through the normal shock with reduced strength. The microramp flow control also increased the spanwise-averaged skin-friction coefficient and reduced the spanwise-averaged incompressible shape factor, thereby improving the health of the boundary layer. The velocity in the near-wall region appears to be the best indicator of microramp effectiveness at controlling SWBLIs. Continued analysis of additional micro-vortex generator designs in the small-scale facility revealed reduced separation within a subsonic diffuser downstream of the normal shock wave/boundary layer interaction. The resulting attached flow within the diffuser from the micro-vortex generator control devices reduces shock wave position and pressure RMS fluctuations within the diffuser along with increased pressure recovery through the shock and at the entrance of the diffuser. The largest effect was observed by the micro-vortex generators that produce the strongest streamwise vortices. High-speed pressure measurements also indicated that the vortex generators shift the energy of the pressure fluctuations to higher frequencies. Implementation of micro-vortex generators into a large-scale, supersonic, axisymmetric, relaxed-compression inlet have been investigated with the use of a unique and novel flow-visualization measurement system designed and successfully used for the analysis of both upstream micro-VGs (MVGs) and downstream VGs utilizing surface oil-flow visualization and pressure-sensitive paint measurements. The inlet centerbody and downstream diffuser vortex-generator regions were imaged during wind-tunnel testing internally through the inlet cowl with the diagnostic system attached to the cowl. Surface-flow visualization revealed separated regions along the inlet centerbody for large mass-flow rates without vortex generators. Upstream vortex generators did reduce separation in the subsonic diffuser, and a unique perspective of the flowfield produced by the downstream vortex generators was obtained. In addition, pressure distributions on the inlet centerbody and vortex generators were measured with pressure-sensitive paint. At low mass-flow ratios the onset of buzz occurs in the large-scale low-boom inlet. Inlet buzz and how it is affected by vortex generators was characterized using shock tracking through high-speed schlieren imaging and pressure fluctuation measurements. The analysis revealed a dominant low frequency oscillation at 21.0 Hz for the single-stream inlet, corresponding with the duration of one buzz cycle. Pressure oscillations prior to the onset of buzz were not detected, leaving the location where the shock wave triggers large separation on the compression spike as the best indicator for the onset of buzz. The driving mechanism for a buzz cycle has been confirmed as the rate of depressurization and repressurization of the inlet as the buzz cycle fluctuates between an effectively unstarted (blocked) inlet and supercritical operation (choked flow), respectively. High-frequency shock position oscillations/pulsations (spike buzz) were also observed throughout portions of the inlet buzz cycle. The primary effect of the VGs was to trigger buzz at a higher mass-flow ratio.

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

NASA Astrophysics Data System (ADS)

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.

Study on miss distance based on projectile shock wave sensor

NASA Astrophysics Data System (ADS)

Gu, Guohua; Cheng, Gang; Zhang, Chenjun; Zhou, Lei

2017-05-01

The paper establishes miss distance models based on physical characteristic of shock-wave. The aerodynamic theory shows that the shock-wave of flying super-sonic projectile is generated for the projectile compressing and expending its ambient atmosphere. It advances getting miss distance according to interval of the first sensors, which first catches shock-wave, to solve the problem such as noise filtering on severe background, and signals of amplifier vibration dynamic disposal and electromagnetism compatibility, in order to improves the precision and reliability of gathering wave N signals. For the first time, it can identify the kinds of pills and firing units automatically, measure miss distance and azimuth when pills are firing. Application shows that the tactics and technique index is advanced all of the world.

ATF1 Modulates the Heat Shock Response by Regulating the Stress-Inducible Heat Shock Factor 1 Transcription Complex

PubMed Central

Takii, Ryosuke; Fujimoto, Mitsuaki; Tan, Ke; Takaki, Eiichi; Hayashida, Naoki; Nakato, Ryuichiro; Shirahige, Katsuhiko

2014-01-01

The heat shock response is an evolutionally conserved adaptive response to high temperatures that controls proteostasis capacity and is regulated mainly by an ancient heat shock factor (HSF). However, the regulation of target genes by the stress-inducible HSF1 transcription complex has not yet been examined in detail in mammalian cells. In the present study, we demonstrated that HSF1 interacted with members of the ATF1/CREB family involved in metabolic homeostasis and recruited them on the HSP70 promoter in response to heat shock. The HSF1 transcription complex, including the chromatin-remodeling factor BRG1 and lysine acetyltransferases p300 and CREB-binding protein (CBP), was formed in a manner that was dependent on the phosphorylation of ATF1. ATF1-BRG1 promoted the establishment of an active chromatin state and HSP70 expression during heat shock, whereas ATF1-p300/CBP accelerated the shutdown of HSF1 DNA-binding activity during recovery from acute stress, possibly through the acetylation of HSF1. Furthermore, ATF1 markedly affected the resistance to heat shock. These results revealed the unanticipated complexity of the primitive heat shock response mechanism, which is connected to metabolic adaptation. PMID:25312646

Efficiency assessment of shock wave therapy in patients with pelvic pain employing harmonic analysis of penile bioimpedance.

PubMed

Khodyreva, L A; Dudareva, A A; Mudraya, I S; Markosyan, T G; Revenko, S V; Kumachev, K V; Logvinov, L A

2013-06-01

In searching for novel objective methods to diagnosticate pelvic pain and assess efficiency of analgesic therapy, 37 male patients were examined prior to and after the course of extracorporeal shock wave therapy (5-10 sessions) with the waves directed to projections of prostate and/or crura and shaft of the penis. The repetition rate of mechanical pulses was 3-5 Hz. The range of energy pulse density was 0.09-0.45 mJ/mm(2). The overall number of pulses in a session was 1500-3000 in any treated zone with total energy smaller than 60 J. The applicator was relocated every other series of 300-500 pulses. Effect of the shock wave therapy was assessed according to subjective symptomatic scales: International Prostate Symptom Score, International Index of Erectile Function, Quality of Life, and nociceptive Visual Analog Scale. The objective assessment of shock wave therapy was performed with harmonic analysis of penile bioimpedance variability, which quantitatively evaluated the low-frequency rhythmic and asynchronous activities at rest as well as the total pulsatile activity of the penis. The magnitude of spectrum components of bioimpedance variations was assessed with a novel parameter, the effective impedance. The spectral parameters were measured in 16 patients prior to and after the treatment course. The corresponding control values were measured in the group of healthy patients. Prior to the shock wave therapy course, all spectrum parameters of penile bioimpedance significantly differed from the control (p<0.05). After this course, low-frequency rhythmic and the total pulsatile activity decreased to normal, while asynchronous activity remained significantly different from the normal. The novel objective physiological criteria of pelvic pain diagnostics and efficiency of its treatment reflecting the regional features of circulation and neural activity corresponded to the clinical symptom scaling prior to and after the shock wave course, and on the whole, these criteria corroborated improvement of the patient state after this therapy.

Glyburide, a K(+)(ATP)channel blocker, improves hypotension and survival in anaphylactic shock induced in Wistar rats sensitized to ovalbumin.

PubMed

Dhanasekaran, Subramanian; Nemmar, Abderrahim; Aburawi, Elhadi H; Kazzam, Elsadig E; Abdulle, Abdishakur; Bellou, Moufida; Bellou, Abdelouahab

2013-11-15

Allergens can induce anaphylactic shock and death due to serve hypotension. Potassium channel blockers (K(+)(ATP)) such as glyburide (GLY) induce vasoconstriction. The effect of (K(+)(ATP)) channel blockers on anaphylactic shock is poorly understood. Objective of the study was to test the hypothesis that GLY reduces hypotension induced in anaphylactic shock and increases survival. Rats were grouped into: G1-N=Naïve; G2-SC=Sensitized-Control; G3-SG=Sensitized-GLY (glyburide 40 mg/kg); G4-SE=Sensitized-EPI (epinephrine 10 mg/kg). G2 to G4 groups were sensitized with ovalbumin (OVA) and shock was induced by i.v. injection of OVA. Treatments were administered intravenously 5 min later. Mean arterial pressure (MAP), heart rate (HR), and mean survival time (MST) were measured for 60 min following OVA injection and treatments administration. At the end of the experiment, blood withdrawal was performed to measure plasma levels of histamine, leukotriene B(4) (LTB(4)), prostaglandin E(2) (PGE(2)) and prostaglandin F(2) (PGF(2)). Additionally blood gas (paO2, paCO2, SaO2) and electrolytes (Na(+), K(+) and Ca (++)) were measured. MAP was normal in G1-N; severe hypotension, negative inotropic and short MST were observed in G2-SC; normalization of MAP, with lesser negative inotropism and increased MST were observed in G3-SG; full recovery was observed in G4-SE. Histamine level was significantly higher in G2-SC; reduced in G3-SG and G4-SE. PGE(2) increased in G3-SG; PGF(2) increased in G2-SC and G3-SG. Na(+) and Ca (++) concentration decreased in sensitized rats but reversed in treated groups, without change in K(+) concentration. In conclusion, our data suggest that administration of GLY reduced hypotension and increases survival time in rat anaphylactic shock.

Heating a plasma by a broadband stream of fast electrons: Fast ignition, shock ignition, and Gbar shock wave applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gus’kov, S. Yu., E-mail: guskov@sci.lebedev.ru; Nicolai, Ph.; Ribeyre, X.

2015-09-15

An exact analytic solution is found for the steady-state distribution function of fast electrons with an arbitrary initial spectrum irradiating a planar low-Z plasma with an arbitrary density distribution. The solution is applied to study the heating of a material by fast electrons of different spectra such as a monoenergetic spectrum, a step-like distribution in a given energy range, and a Maxwellian spectrum, which is inherent in laser-produced fast electrons. The heating of shock- and fast-ignited precompressed inertial confinement fusion (ICF) targets as well as the heating of a target designed to generate a Gbar shock wave for equation ofmore » state (EOS) experiments by laser-produced fast electrons with a Maxwellian spectrum is investigated. A relation is established between the energies of two groups of Maxwellian fast electrons, which are responsible for generation of a shock wave and heating the upstream material (preheating). The minimum energy of the fast and shock igniting beams as well as of the beam for a Gbar shock wave generation increases with the spectral width of the electron distribution.« less

Measurements of Amplified Magnetic Field and Cosmic-Ray Content in Supernova Remnants

NASA Astrophysics Data System (ADS)

Uchiyama, Yasunobu

Supernova explosions drive collisionless shocks in the interstellar (or circumstellar) medium. Such shocks are mediated by plasma waves, resulting in the shock transition on a scale much smaller than the collisional mean free path. Galactic cosmic rays are widely considered to be accelerated at collisionless shocks in supernova remnants via diffusive shock acceleration. New high-energy data coming from the X-ray and gamma-ray satellites and from imaging air Cerenkov telescopes are making possible to study physics of particle acceleration at supernova shocks, such as magnetic field amplification which is considered to be realized as part of shock acceleration process and the energy content of cosmic-ray particles in the supernova shell. In particular, GeV observations with the Fermi Gamma-ray Space Telescope offer the prime means to establish the origin of the gamma-rays, and to measure the cosmic-ray content. Moreover they provide a new opportunity to learn about how particle acceleration responds to environ-mental effects. I will present recent observational results from the Chandra and Suzaku X-ray satellites and new results from the LAT onboard Fermi, and discuss their implications to the origin of galactic cosmic rays.

Impact of shock waves on the conductive properties and structure of MgB2 tapes

NASA Astrophysics Data System (ADS)

Mikhailov, Boris P.; Mikhailova, Alexandra B.; Borovitskaya, Irina V.; Nikulin, Valerii Ya.; Peregudova, Elena N.; Polukhin, Sergei N.; Silin, Pavel V.

2017-10-01

This article presents data on shock waves effect on the structure and the critical current of superconducting MgB2 tapes. To generate shock waves, a plasma focus installation (PF) was used. The conductive characteristics of the superconducting tapes dependence on the intensity of the impact and the number of shock pulses were studied. A distinct pattern of change in critical currents in transversal and longitudinal magnetic fields in the range of 2-9 T is studied at a temperature of 4.2 K. The microstructure of the superconducting tape and chemical composition of its layer are studied in the original state and after the shock wave effect. Changes were found in a microstructure of layers of MgB2 (granulation, subdivision of grains and consolidation), which arose due to the shock-wave impact (SWI), are found. The possibility of increasing the critical current of tapes on 50-80 A in a transversal magnetic field of 2-3 T by means of SWI has been established. In a parallel magnetic field, the impact of the shock effect was essential in magnetic fields lower than 4 T.

Pseudo-shock waves and their interactions in high-speed intakes

NASA Astrophysics Data System (ADS)

Gnani, F.; Zare-Behtash, H.; Kontis, K.

2016-04-01

In an air-breathing engine the flow deceleration from supersonic to subsonic conditions takes places inside the isolator through a gradual compression consisting of a series of shock waves. The wave system, referred to as a pseudo-shock wave or shock train, establishes the combustion chamber entrance conditions, and therefore influences the performance of the entire propulsion system. The characteristics of the pseudo-shock depend on a number of variables which make this flow phenomenon particularly challenging to be analysed. Difficulties in experimentally obtaining accurate flow quantities at high speeds and discrepancies of numerical approaches with measured data have been readily reported. Understanding the flow physics in the presence of the interaction of numerous shock waves with the boundary layer in internal flows is essential to developing methods and control strategies. To counteract the negative effects of shock wave/boundary layer interactions, which are responsible for the engine unstart process, multiple flow control methodologies have been proposed. Improved analytical models, advanced experimental methodologies and numerical simulations have allowed a more in-depth analysis of the flow physics. The present paper aims to bring together the main results, on the shock train structure and its associated phenomena inside isolators, studied using the aforementioned tools. Several promising flow control techniques that have more recently been applied to manipulate the shock wave/boundary layer interaction are also examined in this review.

The 60 kDa heat shock proteins in the hyperthermophilic archaeon Sulfolobus shibatae.

PubMed

Kagawa, H K; Osipiuk, J; Maltsev, N; Overbeek, R; Quaite-Randall, E; Joachimiak, A; Trent, J D

1995-11-10

One of the most abundant proteins in the hyperthermophilic archaeon Sulfolobus shibatae is the 59 kDa heat shock protein (TF55) that is believed to form a homo-oligomeric double ring complex structurally similar to the bacterial chaperonins. We discovered a second protein subunit in the S. shibatae ring complex (referred to as alpha) that is stoichiometric with TF55 (renamed beta). The gene and flanking regions of alpha were cloned and sequenced and its inferred amino acid sequence has 54.4% identity and 74.4% similarity to beta. Transcription start sites for both alpha and beta were mapped and three potential transcription regulatory regions were identified. Northern analyses of cultures shifted from normal growth temperatures (70 to 75 degrees C) to heat shock temperatures (85 to 90 degrees C) indicated that the levels of alpha and beta mRNAs increased during heat shock, but at all temperatures their relative proportions remained constant. Monitoring protein synthesis by autoradiography of total proteins from cultures pulse labeled with L(-)[35S]methionine at normal and heat shock temperatures indicated significant increases in alpha and beta synthesis during heat shock. Under extreme heat shock conditions (> or = 90 degrees C) alpha and beta appeared to be the only two proteins synthesized. The purified alpha and beta subunits combined to form high molecular mass complexes with similar mobilities on native polyacrylamide gels to the complexes isolated directly from cells. Equal proportions of the two subunits gave the greatest yield of the complex, which we refer to as a "rosettasome". It is argued that the rosettasome consists of two homo-oligomeric rings; one of alpha and the other of beta. Polyclonal antibodies against alpha and beta from S. shibatae cross-reacted with proteins of similar molecular mass in 10 out of the 17 archaeal species tested, suggesting that the two rosettasome proteins are highly conserved among the archaea. The archaeal sequences were aligned with bacterial and eukaryotic chaperonins to generate a phylogenetic tree. The tree reveals the close relationship between the archaeal rosettasomes and the eukaryotic TCP1 protein family and the distant relationship to the bacterial GroEL/HSP60 proteins.

Inappropriate Implantable Cardioverter-Defibrillator Shock from QRS Double Counting in the Setting of Hyperkalemia.

PubMed

Dadlani, Akash; Dukes, Jonathan W; Badhwar, Nitish

2016-03-01

This case shows the complexity of arrhythmia management in patients with implantable cardioverter-defibrillators (ICDs) who present with hyperkalemia. In order to prevent inappropriate ICD shock, consideration should be given to the suspension of ICD therapies while intensive care treatment of extreme electrolyte derangements is being pursued. Patients in these setting should be closely monitored until their electrocardiograms have normalized, after which the device can safely be reactivated. Copyright © 2016 Elsevier Inc. All rights reserved.

49 CFR 173.199 - Category B infectious substances.

Code of Federal Regulations, 2012 CFR

2012-10-01

... maximum temperatures, changes in humidity and pressure, and shocks, loadings and vibrations normally... containing body parts, organs, or whole bodies, for shipment by aircraft, the outer packaging may not contain...

49 CFR 173.199 - Category B infectious substances.

Code of Federal Regulations, 2013 CFR

2013-10-01

... maximum temperatures, changes in humidity and pressure, and shocks, loadings and vibrations normally... containing body parts, organs, or whole bodies, for shipment by aircraft, the outer packaging may not contain...

49 CFR 173.199 - Category B infectious substances.

Code of Federal Regulations, 2014 CFR

2014-10-01

... maximum temperatures, changes in humidity and pressure, and shocks, loadings and vibrations normally... containing body parts, organs, or whole bodies, for shipment by aircraft, the outer packaging may not contain...

21 CFR 870.5310 - Automated external defibrillator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... shock of a maximum of 360 joules of energy used for defibrillating (restoring normal heart rhythm) the atria or ventricles of the heart. An AED analyzes the patient's electrocardiogram, interprets the...

21 CFR 870.5310 - Automated external defibrillator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... shock of a maximum of 360 joules of energy used for defibrillating (restoring normal heart rhythm) the atria or ventricles of the heart. An AED analyzes the patient's electrocardiogram, interprets the...

21 CFR 870.5310 - Automated external defibrillator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... shock of a maximum of 360 joules of energy used for defibrillating (restoring normal heart rhythm) the atria or ventricles of the heart. An AED analyzes the patient's electrocardiogram, interprets the...

21 CFR 870.5310 - Automated external defibrillator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... shock of a maximum of 360 joules of energy used for defibrillating (restoring normal heart rhythm) the atria or ventricles of the heart. An AED analyzes the patient's electrocardiogram, interprets the...

21 CFR 870.5310 - Automated external defibrillator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... shock of a maximum of 360 joules of energy used for defibrillating (restoring normal heart rhythm) the atria or ventricles of the heart. An AED analyzes the patient's electrocardiogram, interprets the...

Breast infection

MedlinePlus

Breast infections are usually caused by common bacteria ( Staphylococcus aureus ) found on normal skin. The bacteria enter through ... 2017:chap 8. Que Y-A, Moreillon P. Staphylococcus aureus (including staphylococcal toxic shock syndrome). In: Bennett JE, ...

Autodigestion: Proteolytic Degradation and Multiple Organ Failure in Shock

PubMed Central

Altshuler, Angelina E.; Kistler, Erik B.; Schmid-Schönbein, Geert W.

2015-01-01

There is currently no effective treatment for multiorgan failure following shock other than alleviation supportive care. A better understanding of the pathogenesis of these sequelae to shock is required. The intestine plays a central role in multiorgan failure. It was previously suggested that bacteria and their toxins are responsible for the organ failure seen in circulatory shock, but clinical trials in septic patients have not confirmed this hypothesis. Instead, we review here evidence that the digestive enzymes, synthesized in the pancreas and discharged into the small intestine as requirement for normal digestion, may play a role in multi-organ failure. These powerful enzymes are non-specific, highly concentrated and fully activated in the lumen of the intestine. During normal digestion they are compartmentalized in the lumen of the intestine by the mucosal epithelial barrier. However, if this barrier becomes permeable, e.g. in an ischemic state, the digestive enzymes escape into the wall of the intestine. They digest tissues in the mucosa and generate small molecular weight cytotoxic fragments such as unbound free fatty acids. Digestive enzymes may also escape into the systemic circulation and activate other degrading proteases. These proteases have the ability to clip the ectodomain of surface receptors and compromise their function; for example cleaving the insulin receptor causing insulin resistance. The combination of digestive enzymes and cytotoxic fragments leaking into the central circulation causes cell and organ dysfunction, and ultimately may lead to complete organ failure and death. We summarize current evidence suggesting that enteral blockade of digestive enzymes inside the lumen of the intestine may serve to reduce acute cell and organ damage and improve survival in experimental shock. PMID:26717111

High speed observation of fragment impact initiation of nitromethane charges

NASA Astrophysics Data System (ADS)

Cook, M. D.; Haskins, P. J.; Briggs, R. I.; Cheese, P.; Stennett, C.; Fellows, J.

2000-04-01

Ultra high-speed digital photography has been used to record the onset and build-up of reaction in nitromethane charges that have been impacted by steel fragments. The nitromethane charges were housed in PMMA cylinders and back-lit using conventional flash bulbs. Flat plates of aluminum were glued to one end of the cylinder and PMMA plates to the other. The completed charge was positioned to allow normal impact of the projectiles through the aluminum barrier plate. The events were filmed using an Imacon 468, ultra high-speed digital image system, capable of framing at up to 100 million pictures per second. Using this system it was possible to record detailed photographic information concerning the onset and growth of reaction due to shock initiation of the nitromethane charges. The results obtained to date are consistent with the established concepts for initiation of homogeneous and heterogeneous materials.

Model of Energy Spectrum Parameters of Ground Level Enhancement Events in Solar Cycle 23

NASA Astrophysics Data System (ADS)

Wu, S.-S.; Qin, G.

2018-01-01

Mewaldt et al. (2012) fitted the observations of the ground level enhancement (GLE) events during solar cycle 23 to the double power law equation to obtain the four spectral parameters, the normalization constant C, low-energy power law slope γ1, high-energy power law slope γ2, and break energy E0. There are 16 GLEs from which we select 13 for study by excluding some events with complicated situation. We analyze the four parameters with conditions of the corresponding solar events. According to solar event conditions, we divide the GLEs into two groups, one with strong acceleration by interplanetary shocks and another one without strong acceleration. By fitting the four parameters with solar event conditions we obtain models of the parameters for the two groups of GLEs separately. Therefore, we establish a model of energy spectrum of solar cycle 23 GLEs, which may be used in prediction in the future.

Development of Laser-induced Grating Spectroscopy for Underwater Temperature Measurement in Shock Wave Focusing Regions

NASA Technical Reports Server (NTRS)

Gojani, Ardian B.; Danehy, Paul M.; Alderfer, David W.; Saito, Tsutomu; Takayama, Kazuyoshi

2003-01-01

In Extracorporeal Shock Wave Lithotripsy (ESWL) underwater shock wave focusing generates high pressures at very short duration of time inside human body. However, it is not yet clear how high temperatures are enhanced at the spot where a shock wave is focused. The estimation of such dynamic temperature enhancements is critical for the evaluation of tissue damages upon shock loading. For this purpose in the Interdisciplinary Shock Wave Research Center a technique is developed which employs laser induced thermal acoustics or Laser Induced Grating Spectroscopy. Unlike most of gasdynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm3 and 400 ns, respectively. Preliminary experiments in still water demonstrated that this method detected sound speed and hence temperature in water ranging 283 K to 333 K with errors of 0.5%. These results may be used to empirically establish the equation of states of water, gelatin or agar cells which will work as alternatives of human tissues.

Etude theorique et experimentale de la correlation entre la resistance aux chocs thermiques et aux chocs mecaniques des materiaux refractaires utilises dans les fours de traitement de l'aluminium

NASA Astrophysics Data System (ADS)

Sebbani, Mohamed Jamal Eddine

2001-07-01

This work is a theoretical and experimental study of the correlation between the resistance to thermal shock and mechanical shock of refractory materials. The study of thermal shock showed that the Bahr and Hasselman approaches are alike and that they can be combined into a single, more general approach. This generalisation allowed the division of the theoretical models into two groups: the Hasselman model and the Harmuth model. However, neither of these approaches can predict the behaviour of all refractory materials submitted to thermal shock. Therefore, the generalisation of the Hasselman approach is more appropriate for more dense materials while the Hartmuth approach is more appropriate for less dense materials. The influence of porosity on the energy of rupture helped to explain the behaviour of the less dense material. The absence of generalisation in this case allows those parameters that could be correlated with thermal shock resistance to be dependent on the type of refractory. The study of mechanical shock provided a better understanding of this mechanism. The work performed showed, theoretically and experimentally, that the resistance of the refractory materials could be correlated with the parameter s20 Egwof n-22 . This new parameter helped to explain the statistical correlation between the resistance to mechanical impact and the soxRst parameter established in earlier work. The sintering influence, which makes the refractories more resistant to this type of demand, notably by reducing the "n" coefficient, was shown. This part of the study allowed the establishment of equivalence between thermal fatigue and fatigue by mechanical impact. An evaluation of the correlation between the two mechanisms demonstrated, theoretically and experimentally, that the mechanical and thermal demands could only be exceptionally correlated. In the case of thermal shock, which are imposed deformation demands, it is the shorter cracks which are the most dangerous. However, in the case of mechanical shock, which is constraint imposed, it is the longer cracks that are the most harmful. (Abstract shortened by UMI.)

Quantification of heat shock protein mRNA expression in warm and cold anoxic turtles (Trachemys scripta) using an external RNA control for normalization.

PubMed

Stecyk, Jonathan A W; Couturier, Christine S; Fagernes, Cathrine E; Ellefsen, Stian; Nilsson, Göran E

2012-03-01

The mRNA expression of heat-shock protein 90 (HSP90) and heat-shock cognate 70 (HSC70) was examined in cardiac chambers and telencephalon of warm- (21°C) and cold-acclimated (5°C) turtles (Trachemys scripta) exposed to normoxia, prolonged anoxia or anoxia followed by reoxygenation. Additionally, the suitability of total RNA as well as mRNA from β-actin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and cyclophilin A (PPIA) for normalizing gene expression data was assessed, as compared to the use of an external RNA control. Measurements of HSP90 and HSC70 mRNA expression revealed that anoxia and reoxygenation have tissue- and gene-specific effects. By and large, the alterations support previous investigations on HSP protein abundance in the anoxic turtle heart and brain, as well as the hypothesized roles of HSP90 and HSC70 during stress and non-stress conditions. However, more prominent was a substantially increased HSP90 and HSC70 mRNA expression in the cardiac chambers with cold acclimation. The finding provides support for the notion that cold temperature induces a number of adaptations in tissues of anoxia-tolerant vertebrates that precondition them for winter anoxia. β-actin, GAPDH and PPIA mRNA expression and total RNA also varied with oxygenation state and acclimation temperature in a tissue- and gene-specific manner, as well as among tissue types, thus disqualifying them as suitable for real-time RT-PCR normalization. Thus, the present data highlights the advantages of normalizing real-time RT-PCR data to an external RNA control, an approach that also allows inter-tissue and potentially inter-species comparisons of target gene expression. Copyright © 2011 Elsevier Inc. All rights reserved.

Arthritis in hip (image)

MedlinePlus

Cartilage normally protects the joint, allowing for smooth movement. Cartilage also absorbs shock when pressure is placed on ... like when walking. Arthritis involves the breakdown of cartilage. Without the usual amount of cartilage, the bones ...

Dynamic Electromechanical Characterization of the Ferroelectric Ceramic PZT 95/5

NASA Astrophysics Data System (ADS)

Setchell, R. E.; Chhabildas, L. C.; Furnish, M. D.; Montgomery, S. T.; Holman, G. T.

1997-07-01

Shock-induced depoling of the ferroelectric ceramic PZT 95/5 has been utilized in a number of pulsed power applications. The dynamic behavior of the poled ceramic is complex, with nonlinear coupling between mechanical and electrical variables. Recent efforts to improve numerical simulations of this process have been limited by the scarcity of relevant experimental studies within the last twenty years. Consequently, we have initiated an extensive experimental study of the dynamic electromechanical behavior of this material. Samples of the poled ceramic are shocked to axial stresses from 0.5 to 5 GPa in planar impact experiments and observed with laser interferometry (VISAR) to obtain transmitted wave profiles. Current generation due to shock-induced depoling is observed using different external loads to vary electric field strengths within the samples. Experimental configurations either have the remanent polarization parallel to the direction of shock motion (axially poled) or perpendicular (normally poled). Initial experiments on unpoled samples utilized PVDF stress gauges as well as VISAR, and extended prior data on shock loading and release behavior. (Supported by the U. S. Department of Energy under contract DE-AC04-94AL85000). abstract.

Internal structure of shock waves in disparate mass mixtures

NASA Technical Reports Server (NTRS)

Chung, Chan-Hong; De Witt, Kenneth J.; Jeng, Duen-Ren; Penko, Paul F.

1992-01-01

The detailed flow structure of a normal shock wave for a gas mixture is investigated using the direct-simulation Monte Carlo method. A variable diameter hard-sphere (VDHS) model is employed to investigate the effect of different viscosity temperature exponents (VTE) for each species in a gas mixture. Special attention is paid to the irregular behavior in the density profiles which was previously observed in a helium-xenon experiment. It is shown that the VTE can have substantial effects in the prediction of the structure of shock waves. The variable hard-sphere model of Bird shows good agreement, but with some limitations, with the experimental data if a common VTE is chosen properly for each case. The VDHS model shows better agreement with the experimental data without adjusting the VTE. The irregular behavior of the light-gas component in shock waves of disparate mass mixtures is observed not only in the density profile, but also in the parallel temperature profile. The strength of the shock wave, the type of molecular interactions, and the mole fraction of heavy species have substantial effects on the existence and structure of the irregularities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hottiger, T.; Schmutz, P.; Wiemken, A.

Heat shock resulted in rapid accumulation of large amounts of trehalose in Saccharomyces cerevisiae. In cultures growing exponentially on glucose, the trehalose content of the cells increased from 0.01 to 1 g/g of protein within 1 h after the incubation temperature was shifted from 27 to 40/sup 0/C. When the temperature was readjusted to 27/sup 0/C, the accumulated trehalose was rapidly degraded. In parallel, the activity of the trehalose-phosphate synthase, the key enzyme of trehalose biosynthesis, increased about six fold during the heat shock and declined to normal level after readjustment of the temperature. Surprisingly, the activity of neutral trehalase,more » the key enzyme of trehalose degradation, also increased about threefold during the heat shock and remained almost constant during recovery of the cells at 27/sup 0/C. In pulse-labeling experiments with (/sup 14/C) glucose, trehalose was found to be turned over rapidly in heat-shocked cells, indicating that both anabolic and catabolic enzymes of trehalose metabolism were active in vivo. Possible functions of the heat-induced accumulation of trehalose and its rapid turnover in an apparently futile cycle during heat shock are discussed.« less

New findings for the equilibrated enstatite chondrite Grein 002

NASA Astrophysics Data System (ADS)

Patzer, Andrea; Schlüter, Jochen; Schultz, Ludolf; Tarkian, M.; Hill, Dolores H.; Boynton, William V.

2004-09-01

We report new petrographic and chemical data for the equilibrated EL chondrite Grein 002, including the occurrence of osbornite, metallic copper, abundant taenite, and abundant diopside. As inferred from low Si concentrations in kamacite, the presence of ferroan alabandite, textural deformation, chemical equilibration of mafic silicates, and a subsolar noble gas component, we concur with Grein 002's previous classification as an EL4-5 chondrite. Furthermore, the existence of pockets consisting of relatively coarse, euhedral enstatite crystals protruding large patches of Fe-Ni alloys suggests to us that this EL4-5 chondrite has been locally melted. We suspect impact induced shock to have triggered the formation of the melt pockets. Mineralogical evidence indicates that the localized melting of metal and adjacent enstatite must have happened relatively late in the meteorite's history. The deformation of chondrules, equilibration of mafic silicates, and generation of normal zoning in Fe, Zn-sulfides took place during thermal alteration before the melting event. Following parent body metamorphism, daubreelite was exsolved from troilite in response to a period of slow cooling at subsolidus temperatures. Exsolution of schreibersite from the coarse metal patches probably occurred during a similar period of slow cooling subsequent to the event that induced the formation of the melt pockets. Overall shock features other than localized melting correspond to stage S2 and were likely established by the final impact that excavated the Grein 002 meteoroid.

Shock Wave Technology and Application: An Update☆

PubMed Central

Rassweiler, Jens J.; Knoll, Thomas; Köhrmann, Kai-Uwe; McAteer, James A.; Lingeman, James E.; Cleveland, Robin O.; Bailey, Michael R.; Chaussy, Christian

2012-01-01

Context The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems. Objective To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies. Evidence acquisition We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy. Evidence synthesis Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60–80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures. Conclusions New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL. PMID:21354696

Scramjet mixing establishment times for a pulse facility

NASA Technical Reports Server (NTRS)

Rogers, R. Clayton; Weidner, Elizabeth H.

1991-01-01

A numerical simulation of the temporally developing flow through a generic scramjet combustor duct is presented for stagnation conditions typical of flight at Mach 13 as produced by a shock tunnel pulse facility. The particular focus is to examine the start up transients and to determine the time required for certain flow parameters to become established. The calculations were made with a Navier-Stokes solver SPARK with temporally relaxing inflow conditions derived from operation of the T4 shock tunnel at the University of Queensland in Australia. Calculations at nominal steady inflow conditions were made for comparison. The generic combustor geometry includes the injection of hydrogen fuel from the base of a centrally located strut. In both cases, the flow was assumed laminar and fuel combustion was not included. The establishment process is presented for viscous parameters in the boundary layer and for parameters related to the fuel mixing.

The role of distinct parameters of interplanetary shocks in their propagation into and within the Earth's dayside magnetosphere, and their impact on magnetospheric particle populations

NASA Astrophysics Data System (ADS)

Colpitts, C. A.; Cattell, C. A.

2016-12-01

Interplanetary (IP) shocks are abrupt changes in the solar wind velocity and/or magnetic field. When an IP shock impacts the Earth's magnetosphere, it can trigger a number of responses including geomagnetic storms and substorms that affect radiation to satellites and aircraft, and ground currents that disrupt the power grid. There are a wide variety of IP shocks, and they interact with the magnetosphere in different ways depending on their orientation, speed and other factors. The distinct individual characteristics of IP shocks can have a dramatic effect on their impact on the near-earth environment. While some research has been done on the impact of shock parameters on their geo-effectiveness, these studies primarily utilized ground magnetometer derived indices such as Dst, AE and SME or signals at geosynchronous satellites. The current unprecedented satellite coverage of the magnetosphere, particularly on the dayside, presents an opportunity to directly measure how different shocks propagate into and within the magnetosphere, and how they affect the various particle populations therein. Initial case studies reveal that smaller shocks can have unexpected impacts in the dayside magnetosphere, including unusual particle and electric field signatures, depending on shock parameters. We have recently compiled a database of sudden impulses from 2012-2016, and the location of satellites in the dayside magnetosphere at the impulse times. We are currently combining and comparing this with existing databases compiled at UNH, Harvard and others, as well as solar wind data from ACE, Wind and other solar wind monitors, to generate a complete and accurate list of IP shocks, cataloguing parameters such as the type of shock (CME, CIR etc.), strength (Mach number, solar wind velocity etc.) and shock normal angle. We are investigating the magnetospheric response to these shocks using GOES, ARTEMIS and Cluster data, augmented with RBSP and MMS data where available, to determine what effect the various shock parameters have on their propagation through and impact on the magnetosphere. We will present several case studies from our database that show how different parameters affect how shocks propagate in the dayside and how they affect the particles therein.

Design and Implementation of a Dual-Mass MEMS Gyroscope with High Shock Resistance

PubMed Central

Huang, Libin; Li, Hongsheng

2018-01-01

This paper presents the design and implementation of a dual-mass MEMS gyroscope with high shock resistance by improving the in-phase frequency of the gyroscope and by using a two-stage elastic stopper mechanism and proposes a Simulink shock model of the gyroscope equipped with the two-stage stopper mechanism, which is a very efficient method to evaluate the shock resistance of the gyroscope. The structural design takes into account both the mechanical sensitivity and the shock resistance. The design of the primary structure and the analysis of the stopper mechanism are first introduced. Based on the expression of the restoring force of the stopper beam, the analytical shock response model of the gyroscope is obtained. By this model, the shock response of the gyroscope is theoretically analyzed, and the appropriate structural parameters are obtained. Then, the correctness of the model is verified by finite element (FE) analysis, where the contact collision analysis is introduced in detail. The simulation results show that the application of the two-stage elastic stopper mechanism can effectively improve the shock resistance by more than 1900 g and 1500 g in the x- and y-directions, respectively. Finally, experimental verifications are carried out by using a machete hammer on the micro-gyroscope prototype fabricated by the deep dry silicon on glass (DDSOG) technology. The results show that the shock resistance of the prototype along the x-, y- and z-axes all exceed 10,000 g. Moreover, the output of the gyroscope can return to normal in about 2 s. PMID:29601510

Ultrafast dynamics of self-assembled monolayers under shock compression: effects of molecular and substrate structure.

PubMed

Lagutchev, Alexei S; Patterson, James E; Huang, Wentao; Dlott, Dana D

2005-03-24

Laser-driven approximately 1 GPa shock waves are used to dynamically compress self-assembled monolayers (SAMs) consisting of octadecanethiol (ODT) on Au and Ag, and pentanedecanethiol (PDT) and benzyl mercaptan (BMT) on Au. The SAM response to <4 ps shock loading and approximately 25 ps shock unloading is monitored by vibrational sum-frequency generation spectroscopy (SFG), which is sensitive to the instantaneous tilt angle of the SAM terminal group relative to the surface normal. Arrival of the shock front causes SFG signal loss in all SAMs with a material time constant <3.5 ps. Thermal desorption and shock recovery experiments show that SAMs remain adsorbed on the substrate, so signal loss is attributed to shock tilting of the methyl or phenyl groups to angles near 90 degrees. When the shock unloads, PDT/Au returns elastically to its native structure whereas ODT/Au does not. ODT evidences a complicated viscoelastic response that arises from at least two conformers, one that remains kinetically trapped in a large-tilt-angle conformation for times >250 ps and one that relaxes in approximately 30 ps to a nearly upright conformation. Although the shock responses of PDT/Au, ODT/Ag, and BMT/Au are primarily elastic, a small portion of the molecules, 10-20%, evidence viscoelastic response, either becoming kinetically trapped in large-tilt states or by relaxing in approximately 30 ps back to the native structure. The implications of the observed large-amplitude monolayer dynamics for lubrication under extreme conditions of high strain rates are discussed briefly.

Design and Implementation of a Dual-Mass MEMS Gyroscope with High Shock Resistance.

PubMed

Gao, Yang; Huang, Libin; Ding, Xukai; Li, Hongsheng

2018-03-30

This paper presents the design and implementation of a dual-mass MEMS gyroscope with high shock resistance by improving the in-phase frequency of the gyroscope and by using a two-stage elastic stopper mechanism and proposes a Simulink shock model of the gyroscope equipped with the two-stage stopper mechanism, which is a very efficient method to evaluate the shock resistance of the gyroscope. The structural design takes into account both the mechanical sensitivity and the shock resistance. The design of the primary structure and the analysis of the stopper mechanism are first introduced. Based on the expression of the restoring force of the stopper beam, the analytical shock response model of the gyroscope is obtained. By this model, the shock response of the gyroscope is theoretically analyzed, and the appropriate structural parameters are obtained. Then, the correctness of the model is verified by finite element (FE) analysis, where the contact collision analysis is introduced in detail. The simulation results show that the application of the two-stage elastic stopper mechanism can effectively improve the shock resistance by more than 1900 g and 1500 g in the x - and y -directions, respectively. Finally, experimental verifications are carried out by using a machete hammer on the micro-gyroscope prototype fabricated by the deep dry silicon on glass (DDSOG) technology. The results show that the shock resistance of the prototype along the x -, y - and z -axes all exceed 10,000 g. Moreover, the output of the gyroscope can return to normal in about 2 s.

Proper Heat Shock Pretreatment Reduces Acute Liver Injury Induced by Carbon Tetrachloride and Accelerates Liver Repair in Mice

PubMed Central

Li, San-Qiang; Wang, Dong-Mei; Shu, You-Ju; Wan, Xue-Dong; Xu, Zheng-Shun; Li, En-Zhong

2013-01-01

Whether proper heat shock preconditioning can reduce liver injury and accelerate liver repair after acute liver injury is worth study. So mice received heat shock preconditioning at 40°C for 10 minutes (min), 20 min or 30 min and recovered at room temperature for 8 hours (h) under normal feeding conditions. Then acute liver injury was induced in the heat shock-pretreated mice and unheated control mice by intraperitoneal (i.p.) injection of carbon tetrachloride (CCl4). Hematoxylin and eosin (H&E) staining, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and the expression levels of heat shock protein 70 (HSP70), cytochrome P450 1A2 (CYP1A2) and proliferating cell nuclear antigen (PCNA) were detected in the unheated control mice and heat shock-pretreated mice after CCl4 administration. Our results showed that heat shock preconditioning at 40°C for 20 min remarkably improved the mice’s survival rate (P<0.05), lowered the levels of serum AST and ALT (P<0.05), induced HSP70 (P<0.01), CYP1A2 (P<0.01) and PCNA (P<0.05) expression, effectively reduced liver injury (P<0.05) and accelerated the liver repair (P<0.05) compared with heat shock preconditioning at 40°C for 10 min or 30 min in the mice after acute liver injury induced by CCl4 when compared with the control mice. Our results may be helpful in further investigation of heat shock pretreatment as a potential clinical approach to target liver injury PMID:24526809

Dynamic structure of confined shocks undergoing sudden expansion

NASA Astrophysics Data System (ADS)

Abate, G.; Shyy, W.

2002-01-01

The gas dynamic phenomenon associated with a normal shock wave within a tube undergoing a sudden area expansion consists of highly transient flow and diffraction that give rise to turbulent, compressible, vortical flows. These interactions can occur at time scales typically ranging from micro- to milliseconds. In this article, we review recent experimental and numerical results to highlight the flow phenomena and main physical mechanisms associated with this geometry. The topics addressed include time-accurate shock and vortex locations, flowfield evolution and structure, wall-shock Mach number, two- vs. three-dimensional sudden expansions, and the effect of viscous dissipation on planar shock-front expansions. Between axisymmetric and planar geometries, the flow structure evolves very similarly early on in the sudden expansion process (i.e., within the first two shock tube diameters). Both numerical and experimental studies confirm that the trajectory of the vortex formed at the expansion corner is convected into the flowfield faster in the axisymmetric case than the planar case. The lateral propagation of the vortices correlates very well between axisymmetric and planar geometries. In regard to the rate of dissipation of turbulent kinetic energy (TKE) for a two-dimensional planar shock undergoing a sudden expansion within a confined chamber, calculations show that the solenoidal dissipation is confined to the region of high strain rates arising from the expansion corner. Furthermore, the dilatational dissipation is concentrated mainly at the curvature of the incident, reflected, and barrel shock fronts. The multiple physical mechanisms identified, including shock-strain rate interaction, baroclinic effect, vorticity generation, and different aspects of viscous dissipation, have produced individual and collective flow structures observed experimentally.

Heat shock increases oxidative stress to modulate growth and physico-chemical attributes in diverse maize cultivars

NASA Astrophysics Data System (ADS)

Hussain, Iqbal; Ashraf, Muhammad Arslan; Rasheed, Rizwan; Iqbal, Muhammad; Ibrahim, Muhammad; Ashraf, Shamila

2016-10-01

The present investigation was conducted to appraise the physiochemical adjustments in contrasting maize cultivars, namely, PakAfgoi (tolerant) and EV-5098 (sensitive) subjected to heat shock. Seven-day-old seedlings were exposed to heat shock for different time intervals (1, 3, 6, 24, 48 and 72 h) and data for various physiochemical attributes determined to appraise time course changes in maize. After 72 h of heat shock, the plants were grown under normal conditions for 5 d and data for different growth attributes and photosynthetic pigments recorded. Exposure to heat shock reduced growth and photosynthetic pigments in maize cultivars. The plants exposed to heat shock for up to 3 h recovered growth and photosynthetic pigments when stress was relieved. A time course rise in the relative membrane permeability, hydrogen peroxide (H2O2) and malondialdehyde contents was recorded particularly in the EV-5098 indicating that heat shock-induced oxidative stress. Activities of different enzymatic antioxidants greatly altered due to heat shock. For instance, an increase in superoxide dismutase activity was recorded in both maize cultivars. The activity of ascorbate peroxidase was greater in Pak-Afgoi. However, the peroxidase and catalase activities were higher in plants of EV-5098. Heat shock caused a significant rise in the proline and decline in the total free amino acids. Overall, the performance of Pak-Afgoi was better in terms of having lesser oxidative damage and greater cellular levels of proline. The results suggested that oxidative stress indicators (relative membrane permeability, H2O2 and malondialdehyde) and proline can be used as markers for heat shock tolerant plants.

[Assistenza cardiocircolatoria. (Cardio-circulatory care)].

PubMed

Cogo, P E

2010-06-01

Mortality in pediatric cardiovascular failure is markedly improved with the advent of neonatal and pediatric intensive care and with the implementation of treatment guidelines. In 2002 the American College of Critical Care Medicine Clinical Practice Parameters for Hemodynamic Support of Pediatric and Neonatal Shock reported mortality rates of 0%-5% in previously healthy and 10% in chronically ill children with septic shock associated with implementation of "best clinical practices". Early recognition of shock is the key to successful resuscitation in critically ill children. Often, shock results in or co-exists with myo-cardial dysfunction or acute lung injury. Recognition and appropriate management of these insults is crucial for successful outcomes. Resuscitation should be directed to restoration of tissue perfusion and normalization of cardiac and respiratory function. The underlying cause of shock should also be addressed urgently. The physiological response of individual children to shock resuscitation varies and is often unpredictable. Therefore, repeated assessments of vital parameters are needed for taking appropriate decisions. Global indices of tissue oxygen delivery help in targeting therapies more accurately. Isotonic fluids form the cornerstone of treatment and the amount required for resuscitation is based on etiologies and therapeutic response. After resuscitation has been initiated, targeted history and clinical evaluation must be performed to ascertain the cause of shock and management of co-morbidities should be implemented simultaneously. While the management of shock can be protocol based, the treatment needs to be individualized depending on the suspected etiology and therapeutic response particularly for children who suffer from congenital heart disease.

Self-regulation of 70-kilodalton heat shock proteins in Saccharomyces cerevisiae.

PubMed Central

Stone, D E; Craig, E A

1990-01-01

To determine whether the 70-kilodalton heat shock proteins of Saccharomyces cerevisiae play a role in regulating their own synthesis, we studied the effect of overexpressing the SSA1 protein on the activity of the SSA1 5'-regulatory region. The constitutive level of Ssa1p was increased by fusing the SSA1 structural gene to the GAL1 promoter. A reporter vector consisting of an SSA1-lacZ translational fusion was used to assess SSA1 promoter activity. In a strain producing approximately 10-fold the normal heat shock level of Ssa1p, induction of beta-galactosidase activity by heat shock was almost entirely blocked. Expression of a transcriptional fusion vector in which the CYC1 upstream activating sequence of a CYC1-lacZ chimera was replaced by a sequence containing a heat shock upstream activating sequence (heat shock element 2) from the 5'-regulatory region of SSA1 was inhibited by excess Ssa1p. The repression of an SSA1 upstream activating sequence by the SSA1 protein indicates that SSA1 self-regulation is at least partially mediated at the transcriptional level. The expression of another transcriptional fusion vector, containing heat shock element 2 and a lesser amount of flanking sequence, is not inhibited when Ssa1p is overexpressed. This suggests the existence of an element, proximal to or overlapping heat shock element 2, that confers sensitivity to the SSA1 protein. Images PMID:2181281

Stable Reference Gene Selection for RT-qPCR Analysis in Nonviruliferous and Viruliferous Frankliniella occidentalis.

PubMed

Yang, Chunxiao; Li, Hui; Pan, Huipeng; Ma, Yabin; Zhang, Deyong; Liu, Yong; Zhang, Zhanhong; Zheng, Changying; Chu, Dong

2015-01-01

Reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) is a reliable technique for measuring and evaluating gene expression during variable biological processes. To facilitate gene expression studies, normalization of genes of interest relative to stable reference genes is crucial. The western flower thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), the main vector of tomato spotted wilt virus (TSWV), is a destructive invasive species. In this study, the expression profiles of 11 candidate reference genes from nonviruliferous and viruliferous F. occidentalis were investigated. Five distinct algorithms, geNorm, NormFinder, BestKeeper, the ΔCt method, and RefFinder, were used to determine the performance of these genes. geNorm, NormFinder, BestKeeper, and RefFinder identified heat shock protein 70 (HSP70), heat shock protein 60 (HSP60), elongation factor 1 α, and ribosomal protein l32 (RPL32) as the most stable reference genes, and the ΔCt method identified HSP60, HSP70, RPL32, and heat shock protein 90 as the most stable reference genes. Additionally, two reference genes were sufficient for reliable normalization in nonviruliferous and viruliferous F. occidentalis. This work provides a foundation for investigating the molecular mechanisms of TSWV and F. occidentalis interactions.

Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases

NASA Technical Reports Server (NTRS)

Hall, R. M.

1980-01-01

The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

Shock Transmission and Fatigue in Human Running.

PubMed

Verbitsky, Oleg; Mizrahi, Joseph; Voloshin, Arkady; Treiger, July; Isakov, Eli

1998-08-01

The goal of this research was to analyze the effects of fatigue on the shock waves generated by foot strike. Twenty-two subjects were instrumented with an externally attached, lightweight accelerometer placed over the tibial tuberosity. The subjects ran on a treadmill for 30 min at a speed near their anaerobic threshold. Fatigue was established when the end-tidal CO 2 pressure decreased. The results indicated that approximately half of the subjects reached the fatigue state toward the end of the test. Whenever fatigue occurred, the peak acceleration was found to increase. It was thus concluded that there is a clear association between fatigue and increased heel strike-induced shock waves. These results have a significant implication for the etiology of running injuries, since shock wave attenuation has been previously reported to play an important role in preventing such injuries.

An experimental study of fluctuating pressure loads beneath swept shock/boundary-layer interactions

NASA Technical Reports Server (NTRS)

Settles, Gary S.

1991-01-01

A database is established on the fluctuating pressure loads produced on aerodynamic surfaces beneath 3-D shock wave/boundary layer interactions. Such loads constitute a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary layer on a flat plate is subjected to interactions with swept planar shock waves generated by sharp fins. Fin angles from 5 to 25 deg at freestream Mach numbers between 2.5 and 4 produce a variety of interaction strengths from weak to very strong. Miniature Kulite pressure transducers mounted in the flat plate were used to measure interaction-induced wall pressure fluctuations. These data will be correlated with proposed new optical data on the fluctuations of the interaction structure, especially that of the lambda-shock system and its associated high-speed jet impingement.

Properties and Radial Trends of Coronal Mass Ejecta and Their Associated Shocks Observed by Ulysses in the Ecliptic Plane. Appendix 2; Repr. from Journal of Geophysical Research, v. 105, 2000 p 12,617-12,626

NASA Technical Reports Server (NTRS)

Riley, Pete; Gosling, J. T.; McComas, D. J.; Forsyth, R. J.

2001-01-01

In this paper, magnetic and plasma measurements are used to analyze 17 interplanetary coronal mass ejections (CMEs) identified by Ulysses during its in-ecliptic passage to Jupiter. We focus on the expansion characteristics of these CMEs (as inferred from the time rate of change of the velocity profiles through the CMEs) and the properties of 14 forward shocks unambiguously associated with these CMEs. We highlight radial trends from 1 to 5.4 AU. Our results indicate that the CMEs are generally expanding at all heliocentric distances. With regard to the shocks preceding these ejecta, we note the following: (1) There is a clear tendency for the shock speed (in the upstream frame of reference) to decrease with increasing heliocentric distance as the CMEs transfer momentum to the ambient solar wind and slow down; (2) 86% of the shock fronts are oriented in the ecliptic plane such that their normals point westward (i.e., in the direction of planetary motion about the Sun), (3) 86% of the shocks are propagating toward the heliographic equator; and (4) no clear trend was found in the strength of the shocks versus heliocentric distance. These results are interpreted using simple dynamical arguments and are supported by fluid and magnetohydrodynamic (MHD) simulations.

The effect of cosmic-ray acceleration on supernova blast wave dynamics

NASA Astrophysics Data System (ADS)

Pais, M.; Pfrommer, C.; Ehlert, K.; Pakmor, R.

2018-05-01

Non-relativistic shocks accelerate ions to highly relativistic energies provided that the orientation of the magnetic field is closely aligned with the shock normal (quasi-parallel shock configuration). In contrast, quasi-perpendicular shocks do not efficiently accelerate ions. We model this obliquity-dependent acceleration process in a spherically expanding blast wave setup with the moving-mesh code AREPO for different magnetic field morphologies, ranging from homogeneous to turbulent configurations. A Sedov-Taylor explosion in a homogeneous magnetic field generates an oblate ellipsoidal shock surface due to the slower propagating blast wave in the direction of the magnetic field. This is because of the efficient cosmic ray (CR) production in the quasi-parallel polar cap regions, which softens the equation of state and increases the compressibility of the post-shock gas. We find that the solution remains self-similar because the ellipticity of the propagating blast wave stays constant in time. This enables us to derive an effective ratio of specific heats for a composite of thermal gas and CRs as a function of the maximum acceleration efficiency. We finally discuss the behavior of supernova remnants expanding into a turbulent magnetic field with varying coherence lengths. For a maximum CR acceleration efficiency of about 15 per cent at quasi-parallel shocks (as suggested by kinetic plasma simulations), we find an average efficiency of about 5 per cent, independent of the assumed magnetic coherence length.

Measurement and Analysis of the Extreme Physical Shock Environment Experienced by Crane-Mounted Radiation Detection Systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyd, M; Erchinger, J; Marianno, C

Potentially, radiation detectors at ports of entry could be mounted on container gantry crane spreaders to monitor cargo containers entering and leaving the country. These detectors would have to withstand the extreme physical environment experienced by these spreaders during normal operations. Physical shock data from the gable ends of a spreader were recorded during the loading and unloading of a cargo ship with two Lansmont SAVER 9X30 units (with padding) and two PCB Piezotronics model 340A50 accelerometers (hard mounted). Physical shocks in the form of rapid acceleration were observed in all accelerometer units with values ranging from 0.20 g’s tomore » 199.99 g’s. The majority of the shocks for all the Lansmont and PCB accelerometers were below 50 g’s. The Lansmont recorded mean shocks of 21.83 ± 13.62 g’s and 24.78 ± 11.49 g’s while the PCB accelerometers experienced mean shocks of 34.39 ± 25.51 g’s and 41.77 ± 22.68 g’s for the landside and waterside units, respectively. Encased detector units with external padding should be designed to withstand at least 200 g’s of acceleration without padding and typical shocks of 30 g’s with padding for mounting on a spreader.« less

A maximum contraction and substantial quantities of tritium can be obtained from tetraethylammonium-treated [3H]-noradrenaline preloaded, rat vas deferens in response to a single electrical shock.

PubMed Central

Wakade, A. R.

1980-01-01

1 In the normal and phenoxybenzamine-treated vasa deferentia of the rat the overflow of tritium after preloading with [3H]-noradrenaline increased with the increase in frequency of transmural stimulation. Phenozybenzamine enhanced overflow by 5 to 7 fold. 2 After tetraethylammonium (TEA, 10 mM), fractional tritium overflow at 5 Hz increased from a control value of 2.8 to 53 X 10(-4), and at 0.5 Hz it reached 154 X 10(-4). Enhancement of overflow was inversely related to the frequency of stimulation. 3 Contractor responses of the vas deferens induced by transmural stimulation were markedly potentiated, both in amplitude and duration, by 10 mM TEA. The contraction developed in the presence of 10 mM TEA at 0.5 Hz was comparable to that obtained at 10 Hz in normal Krebs solution. 4 In the presence of 5 mM TEA, contractions of the vas deferens caused by exogenous noradrenaline were potentiated about 5 fold. 5 The overflow and contractor response induced by 45 mM K were enhanced about 5 fold in 10 mM TEA-Krebs solution. Facilitation of K-induced overflow by TEA was reduced over 50% by tetrodotoxin (TTX, 1 microM). 6 Delivery of a single shock (1.0 ms duration) to 10 mM TEA-treated vas deferens resulted in a 63% increase in tritium overflow over background overflow. The fractional overflow amounted to almost 720 X 10(-4) after a single shock, as compared to 154 X 10(-4) obtained at 0.5 Hz. 7 The vas deferens treated with 10 mM TEA and stimulated by a single shock developed a contraction which was greater in amplitude and duration than that seen in normal tissue at 10 Hz. 8 Five second serial samples collected from superfused 10 mM TEA-treated vas deferens contained maximum quantities of radioactivity in the first 5 s after a single shock. In subsequent samples, radioactivity gradually declined, and reached prestimulation level after about 25 s. 9 The fractional overflow caused by stimulation at 0.1 Hz in 10 mM TEA-treated tissue progressively increased as external Ca was gradually raised from 0.83 to 10 mM. 10 The mechanism of action of TEA in enhancing the overflow of sympathetic transmitter, particularly in response to a single shock, is discussed in relation to Ca. PMID:7052336

Pressure resistance of cold-shocked Escherichia coli O157:H7 in ground beef, beef gravy and peptone water.

PubMed

Baccus-Taylor, G S H; Falloon, O C; Henry, N

2015-06-01

(i) To study the effects of cold shock on Escherichia coli O157:H7 cells. (ii) To determine if cold-shocked E. coli O157:H7 cells at stationary and exponential phases are more pressure-resistant than their non-cold-shocked counterparts. (iii) To investigate the baro-protective role of growth media (0·1% peptone water, beef gravy and ground beef). Quantitative estimates of lethality and sublethal injury were made using the differential plating method. There were no significant differences (P > 0·05) in the number of cells killed; cold-shocked or non-cold-shocked. Cells grown in ground beef (stationary and exponential phases) experienced lowest death compared with peptone water and beef gravy. Cold-shock treatment increased the sublethal injury to cells cultured in peptone water (stationary and exponential phases) and ground beef (exponential phase), but decreased the sublethal injury to cells in beef gravy (stationary phase). Cold shock did not confer greater resistance to stationary or exponential phase cells pressurized in peptone water, beef gravy or ground beef. Ground beef had the greatest baro-protective effect. Real food systems should be used in establishing food safety parameters for high-pressure treatments; micro-organisms are less resistant in model food systems, the use of which may underestimate the organisms' resistance. © 2015 The Society for Applied Microbiology.

Experimental and numerical investigation of reactive shock-accelerated flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonazza, Riccardo

2016-12-20

The main goal of this program was to establish a qualitative and quantitative connection, based on the appropriate dimensionless parameters and scaling laws, between shock-induced distortion of astrophysical plasma density clumps and their earthbound analog in a shock tube. These objectives were pursued by carrying out laboratory experiments and numerical simulations to study the evolution of two gas bubbles accelerated by planar shock waves and compare the results to available astrophysical observations. The experiments were carried out in an vertical, downward-firing shock tube, 9.2 m long, with square internal cross section (25×25 cm 2). Specific goals were to quantify themore » effect of the shock strength (Mach number, M) and the density contrast between the bubble gas and its surroundings (usually quantified by the Atwood number, i.e. the dimensionless density difference between the two gases) upon some of the most important flow features (e.g. macroscopic properties; turbulence and mixing rates). The computational component of the work performed through this program was aimed at (a) studying the physics of multi-phase compressible flows in the context of astrophysics plasmas and (b) providing a computational connection between laboratory experiments and the astrophysical application of shock-bubble interactions. Throughout the study, we used the FLASH4.2 code to run hydrodynamical and magnetohydrodynamical simulations of shock bubble interactions on an adaptive mesh.« less

Strength properties and structure of a submicrocrystalline Al-Mg-Mn alloy under shock compression

NASA Astrophysics Data System (ADS)

Petrova, A. N.; Brodova, I. G.; Razorenov, S. V.

2017-06-01

The results of studying the strength of a submicrocrystalline aluminum A5083 alloy (chemical composition was 4.4Mg-0.6Mn-0.11Si-0.23Fe-0.03Cr-0.02Cu-0.06Ti wt % and Al base) under shockwave compression are presented. The submicrocrystalline structure of the alloy was produced in the process of dynamic channel-angular pressing at a strain rate of 104 s-1. The average size of crystallites in the alloy was 180-460 nm. Hugoniot elastic limit σHEL, dynamic yield stress σy, and the spall strength σSP of the submicrocrystalline alloy were determined based on the free-surface velocity profiles of samples during shock compression. It has been established that upon shock compression, the σHEL and σy of the submicrocrystalline alloy are higher than those of the coarse-grained alloy and σsp does not depend on the grain size. The maximum value of σHEL reached for the submicrocrystalline alloy is 0.66 GPa, which is greater than that in the coarse-crystalline alloy by 78%. The dynamic yield stress is σy = 0.31 GPa, which is higher than that of the coarse-crystalline alloy by 63%. The spall strength is σsp = 1.49 GPa. The evolution of the submicrocrystalline structure of the alloy during shock compression was studied. It has been established that a mixed nonequilibrium grain-subgrain structure with a fragment size of about 400 nm is retained after shock compression, and the dislocation density and the hardness of the alloy are increased.

Clinical Management of Heat-Related Illnesses

DTIC Science & Technology

2012-01-01

rhabdomyolysis and multiorgan dysfunction syndrome, and it may result in death from overwhelming cell necrosis caused by a lethal heat-shock exposure...complications such as rhabdomyolysis and multiorgan dysfunction syndrome, and it may result in death from overwhelming cell necrosis caused by a...acetaminophen lower Tco by normalizing the elevated hypothalamic set point that is caused by pyrogens; in heatstroke, the set point is normal, with

Energy transformation, transfer, and release dynamics in high speed turbulent flows

DTIC Science & Technology

2017-03-01

experimental techniques developed allowed non -intrusive measurement of convecting velocity fields in supersonic flows and used for validation of LES of...by the absence of (near-)normal shocks that normal injection generates. New experimental techniques were developed that allowed the non -intrusive...and was comprised of several parts in which significant accomplishments were made: 1. An experimental effort focusing on investigations in: a

Sound from apollo rockets in space.

PubMed

Cotten, D; Donn, W L

1971-02-12

Low-frequency sound has been recorded on at least two occasions in Bermuda with the passage of Apollo rocket vehicles 188 kilometers aloft. The signals, which are reminiscent of N-waves from sonic booms, are (i) horizontally coherent; (ii) have extremely high (supersonic) trace velocities across the tripartite arrays; (iii) have nearly identical appearance and frequencies; (iv) have essentially identical arrival times after rocket launch; and (v) are the only coherent signals recorded over many hours. These observations seem to establish that the recorded sound comes from the rockets at high elevation. Despite this high elevation, the values of surface pressure appear to be explainable on the basis of a combination of a kinetic theory approach to shock formation in rarefied atmospheres with established gas-dynamics shock theory.

Influence of Tanshinone IIa on heat shock protein 70, Bcl-2 and Bax expression in rats with spinal ischemia/reperfusion injury.

PubMed

Zhang, Li; Gan, Weidong; An, Guoyao

2012-12-25

Tanshinone IIa is an effective monomer component of Danshen, which is a traditional Chinese medicine for activating blood circulation to dissipate blood stasis. Tanshinone IIa can effectively improve brain tissue ischemia/hypoxia injury. The present study established a rat model of spinal cord ischemia/reperfusion injury and intraperitoneally injected Tanshinone IIa, 0.5 hour prior to model establishment. Results showed that Tanshinone IIa promoted heat shock protein 70 and Bcl-2 protein expression, but inhibited Bax protein expression in the injured spinal cord after ischemia/reperfusion injury. Furthermore, Nissl staining indicated a reduction in nerve cell apoptosis and fewer pathological lesions in the presence of Tanshinone IIa, compared with positive control Danshen injection.

A novel hybrid approach with multidimensional-like effects for compressible flow computations

NASA Astrophysics Data System (ADS)

Kalita, Paragmoni; Dass, Anoop K.

2017-07-01

A multidimensional scheme achieves good resolution of strong and weak shocks irrespective of whether the discontinuities are aligned with or inclined to the grid. However, these schemes are computationally expensive. This paper achieves similar effects by hybridizing two schemes, namely, AUSM and DRLLF and coupling them through a novel shock switch that operates - unlike existing switches - on the gradient of the Mach number across the cell-interface. The schemes that are hybridized have contrasting properties. The AUSM scheme captures grid-aligned (and strong) shocks crisply but it is not so good for non-grid-aligned weaker shocks, whereas the DRLLF scheme achieves sharp resolution of non-grid-aligned weaker shocks, but is not as good for grid-aligned strong shocks. It is our experience that if conventional shock switches based on variables like density, pressure or Mach number are used to combine the schemes, the desired effect of crisp resolution of grid-aligned and non-grid-aligned discontinuities are not obtained. To circumvent this problem we design a shock switch based - for the first time - on the gradient of the cell-interface Mach number with very impressive results. Thus the strategy of hybridizing two carefully selected schemes together with the innovative design of the shock switch that couples them, affords a method that produces the effects of a multidimensional scheme with a lower computational cost. It is further seen that hybridization of the AUSM scheme with the recently developed DRLLFV scheme using the present shock switch gives another scheme that provides crisp resolution for both shocks and boundary layers. Merits of the scheme are established through a carefully selected set of numerical experiments.

An approximate viscous shock layer technique for calculating chemically reacting hypersonic flows about blunt-nosed bodies

NASA Technical Reports Server (NTRS)

Cheatwood, F. Mcneil; Dejarnette, Fred R.

1991-01-01

An approximate axisymmetric method was developed which can reliably calculate fully viscous hypersonic flows over blunt nosed bodies. By substituting Maslen's second order pressure expression for the normal momentum equation, a simplified form of the viscous shock layer (VSL) equations is obtained. This approach can solve both the subsonic and supersonic regions of the shock layer without a starting solution for the shock shape. The approach is applicable to perfect gas, equilibrium, and nonequilibrium flowfields. Since the method is fully viscous, the problems associated with a boundary layer solution with an inviscid layer solution are avoided. This procedure is significantly faster than the parabolized Navier-Stokes (PNS) or VSL solvers and would be useful in a preliminary design environment. Problems associated with a previously developed approximate VSL technique are addressed before extending the method to nonequilibrium calculations. Perfect gas (laminar and turbulent), equilibrium, and nonequilibrium solutions were generated for airflows over several analytic body shapes. Surface heat transfer, skin friction, and pressure predictions are comparable to VSL results. In addition, computed heating rates are in good agreement with experimental data. The present technique generates its own shock shape as part of its solution, and therefore could be used to provide more accurate initial shock shapes for higher order procedures which require starting solutions.

Testing cosmic ray acceleration with radio relics: a high-resolution study using MHD and tracers

NASA Astrophysics Data System (ADS)

Wittor, D.; Vazza, F.; Brüggen, M.

2017-02-01

Weak shocks in the intracluster medium may accelerate cosmic-ray protons and cosmic-ray electrons differently depending on the angle between the upstream magnetic field and the shock normal. In this work, we investigate how shock obliquity affects the production of cosmic rays in high-resolution simulations of galaxy clusters. For this purpose, we performed a magnetohydrodynamical simulation of a galaxy cluster using the mesh refinement code ENZO. We use Lagrangian tracers to follow the properties of the thermal gas, the cosmic rays and the magnetic fields over time. We tested a number of different acceleration scenarios by varying the obliquity-dependent acceleration efficiencies of protons and electrons, and by examining the resulting hadronic γ-ray and radio emission. We find that the radio emission does not change significantly if only quasi-perpendicular shocks are able to accelerate cosmic-ray electrons. Our analysis suggests that radio-emitting electrons found in relics have been typically shocked many times before z = 0. On the other hand, the hadronic γ-ray emission from clusters is found to decrease significantly if only quasi-parallel shocks are allowed to accelerate cosmic ray protons. This might reduce the tension with the low upper limits on γ-ray emission from clusters set by the Fermi satellite.

Experimental investigation on the characteristics of supersonic fuel spray and configurations of induced shock waves.

PubMed

Wang, Yong; Yu, Yu-Song; Li, Guo-Xiu; Jia, Tao-Ming

2017-01-05

The macro characteristics and configurations of induced shock waves of the supersonic sprays are investigated by experimental methods. Visualization study of spray shape is carried out with the high-speed camera. The macro characteristics including spray tip penetration, velocity of spray tip and spray angle are analyzed. The configurations of shock waves are investigated by Schlieren technique. For supersonic sprays, the concept of spray front angle is presented. Effects of Mach number of spray on the spray front angle are investigated. The results show that the shape of spray tip is similar to blunt body when fuel spray is at transonic region. If spray entered the supersonic region, the oblique shock waves are induced instead of normal shock wave. With the velocity of spray increasing, the spray front angle and shock wave angle are increased. The tip region of the supersonic fuel spray is commonly formed a cone. Mean droplet diameter of fuel spray is measured using Malvern's Spraytec. Then the mean droplet diameter results are compared with three popular empirical models (Hiroyasu's, Varde's and Merrigton's model). It is found that the Merrigton's model shows a relative good correlation between models and experimental results. Finally, exponent of injection velocity in the Merrigton's model is fitted with experimental results.

Shock wave polarizations and optical metrics in the Born and the Born–Infeld electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minz, Christoph, E-mail: christoph.minz@alumni.tu-berlin.de; Borzeszkowski, Horst-Heino von, E-mail: borzeszk@mailbox.tu-berlin.de; Chrobok, Thoralf, E-mail: tchrobok@mailbox.tu-berlin.de

We analyze the behavior of shock waves in nonlinear theories of electrodynamics. For this, by use of generalized Hadamard step functions of increasing order, the electromagnetic potential is developed in a series expansion near the shock wave front. This brings about a corresponding expansion of the respective electromagnetic field equations which allows for deriving relations that determine the jump coefficients in the expansion series of the potential. We compute the components of a suitable gauge-normalized version of the jump coefficients given for a prescribed tetrad compatible with the shock front foliation. The solution of the first-order jump relations shows that,more » in contrast to linear Maxwell’s electrodynamics, in general the propagation of shock waves in nonlinear theories is governed by optical metrics and polarization conditions describing the propagation of two differently polarized waves (leading to a possible appearance of birefringence). In detail, shock waves are analyzed in the Born and Born–Infeld theories verifying that the Born–Infeld model exhibits no birefringence and the Born model does. The obtained results are compared to those ones found in literature. New results for the polarization of the two different waves are derived for Born-type electrodynamics.« less

Experimental investigation on the characteristics of supersonic fuel spray and configurations of induced shock waves

PubMed Central

Wang, Yong; Yu, Yu-song; Li, Guo-xiu; Jia, Tao-ming

2017-01-01

The macro characteristics and configurations of induced shock waves of the supersonic sprays are investigated by experimental methods. Visualization study of spray shape is carried out with the high-speed camera. The macro characteristics including spray tip penetration, velocity of spray tip and spray angle are analyzed. The configurations of shock waves are investigated by Schlieren technique. For supersonic sprays, the concept of spray front angle is presented. Effects of Mach number of spray on the spray front angle are investigated. The results show that the shape of spray tip is similar to blunt body when fuel spray is at transonic region. If spray entered the supersonic region, the oblique shock waves are induced instead of normal shock wave. With the velocity of spray increasing, the spray front angle and shock wave angle are increased. The tip region of the supersonic fuel spray is commonly formed a cone. Mean droplet diameter of fuel spray is measured using Malvern’s Spraytec. Then the mean droplet diameter results are compared with three popular empirical models (Hiroyasu’s, Varde’s and Merrigton’s model). It is found that the Merrigton’s model shows a relative good correlation between models and experimental results. Finally, exponent of injection velocity in the Merrigton’s model is fitted with experimental results. PMID:28054555

Larvae of related Diptera species from thermally contrasting habitats exhibit continuous up-regulation of heat shock proteins and high thermotolerance.

PubMed

Garbuz, David G; Zatsepina, Olga G; Przhiboro, Andrey A; Yushenova, Irina; Guzhova, Irina V; Evgen'ev, Michael B

2008-11-01

A population of Stratiomys japonica, a species belonging to the family Stratiomyidae (Diptera), common name 'soldier flies', occurs in a hot volcanic spring, which is apparently among the most inhospitable environments for animals because of chemical and thermal conditions. Larvae of this species, which naturally often experience temperatures more than 40 degrees C, have constitutively high concentrations of the normally inducible heat-shock protein Hsp70, but very low level of corresponding mRNA. Larvae of three other species of the same family, Stratiomys singularior, Nemotelus bipunctatus and Oxycera pardalina, are confined to different type semi-aquatic habitats with contrasting thermal regime. However, all of them shared the same pattern of Hsp70 expression. Interestingly, heat-shock treatment of S. japonica larvae activates heat-shock factor and significantly induces Hsp70 synthesis, whereas larvae of O. pardalina, a species from constant cold environment, produce significantly less Hsp70 in response to heat shock. Adults of the four species also exhibit lower, but detectable levels of Hsp70 without heat shock. Larvae of all species studied have very high tolerance to temperature stress in comparison with other Diptera species investigated, probably representing an inherent adaptive feature of all Stratiomyidae enabling successful colonization of highly variable and extreme habitats.

Original size of the Vredefort structure, South Africa

NASA Technical Reports Server (NTRS)

Therriault, A. M.; Reid, A. M.; Reimold, W. U.

1993-01-01

The Vredefort structure is located approximately 120 km southwest of Johannesburg, South Africa, and is deeply eroded. Controversies remain on the origin of this structure with the most popular hypotheses being: (1) by impact cratering about 2.0 Ga; (2) as a cryptoexplosion structure about 2.0 Ga; and (3) by purely tectonic processes starting at about 3.0 Ga and ending with the Vredefort event at 2.0 Ga. In view of recent work in which the granophyre dikes are interpreted as the erosional remants of a more extensive impact melt sheet, injected downward into the underlying country rocks, the impact origin hypothesis for Vredefort is adopted. In order to estimate the original dimensions of the Vredefort impact structure, it is assumed that the structure was initially circular, that its predeformation center corresponds to the center of the granitic core, and that the pre-Vredefort geology of the area prior to approximately 2.0 Ga ago is as suggested by Fletcher and Reimold. The spatial relationship between shock metamorphic effects, the shock pressures they record, and the morphological features of the crater were established for a number of large terrestrial craters. The principles of crater formation at large complex impact structures comparable in size to Vredefort were also established, although many details remain unresolved. An important conclusion is that the transient crater, which is formed directly by excavation and displacement by the shock-induced cratering flow-field (i.e., the particle velocity flow field existing in the region of the transient crater but behind the initial outgoing shock front), is highly modified during the late stage processes. The original transient crater diameter lies well within the final rim of the crater, which is established by structural movements during late-stage cavity modification.

Impact of Isothermal Aging and Testing Temperature on Large Flip-Chip BGA Interconnect Mechanical Shock Performance

NASA Astrophysics Data System (ADS)

Lee, Tae-Kyu; Chen, Zhiqiang; Guirguis, Cherif; Akinade, Kola

2017-10-01

The stability of solder interconnects in a mechanical shock environment is crucial for large body size flip-chip ball grid array (FCBGA) electronic packages. Additionally, the junction temperature increases with higher electric power condition, which brings the component into an elevated temperature environment, thus introducing another consideration factor for mechanical stability of interconnection joints. Since most of the shock performance data available were produced at room temperature, the effect of elevated temperature is of interest to ensure the reliability of the device in a mechanical shock environment. To achieve a stable␣interconnect in a dynamic shock environment, the interconnections must tolerate mechanical strain, which is induced by the shock wave input and reaches the particular component interconnect joint. In this study, large body size (52.5 × 52.5 mm2) FCBGA components assembled on 2.4-mm-thick boards were tested with various isothermal pre-conditions and testing conditions. With a heating element embedded in the test board, a test temperature range from room temperature to 100°C was established. The effects of elevated temperature on mechanical shock performance were investigated. Failure and degradation mechanisms are identified and discussed based on the microstructure evolution and grain structure transformations.

Changes in transthoracic impedance during sequential biphasic defibrillation.

PubMed

Deakin, Charles D; Ambler, Jonathan J S; Shaw, Steven

2008-08-01

Sequential monophasic defibrillation reduces transthoracic impedance (TTI) and progressively increases current flow for any given energy level. The effect of sequential biphasic shocks on TTI is unknown. We therefore studied patients undergoing elective cardioversion using a biphasic waveform to establish whether this is a phenomenon seen in the clinical setting. Adults undergoing elective DC cardioversion for atrial flutter or fibrillation received sequential transthoracic shocks using an escalating protocol (70J, 100J, 150J, 200J, and 300J) with a truncated exponential biphasic waveform. TTI was calculated through the defibrillator circuit and recorded electronically. Successful cardioversion terminated further defibrillation shocks. A total of 58 patients underwent elective cardioversion. Cardioversion was successful in 93.1% patients. First shock TTI was 92.2 [52.0-126.0]Omega (n=58) and decreased significantly with each sequential shock. Mean TTI in patients receiving five shocks (n=5) was 85.0Omega. Sequential biphasic defibrillation decreases TTI in a similar manner to that seen with monophasic waveforms. The effect is likely during defibrillation during cardiac arrest by the quick succession in which shocks are delivered and the lack of cutaneous blood flow which limits the inflammatory response. The ability of biphasic defibrillators to adjust their waveform according to TTI is likely to minimise any effect of these findings on defibrillation efficacy.

[Serum IgE in Guinea Pigs Died of Anaphylactic Shock and Its Forensic Signifi- cance When the Guinea Pig Cannot be Timely Refrigerated].

PubMed

Su, Jun; Yu, Jian; Liu, Yong

2015-10-01

To investigate the serum IgE with various postmortem intervals (PMI) in guinea pigs due to sudden death from anaphylactic shock and to explore the effect of refrigeration of corpse on serum IgE level and its application value in forensic medicine. The animal death models of anaphylactic shock were established. The corpses were preserved at room temperature (20 °C ) for 6 h and then refrigerated at 4 °C. The serum was sampled at 6, 12, 24, 36 and 48 hours after death. The IgE level of serum was detected with ELISA. The control group was also established. The serum IgE level had significant. difference between the experimental group and the control group (P < 0.05). There was no significant difference among the experimental groups at 6, 12, 24, 36 and 48 hours post- mortem (P > 0.05). If the corpses were placed in 4 °C conditions 6 hours after anaphylactic death, the serum IgE still shows a good marker within 48 h for forensic investigation.

Numerical computation of linear instability of detonations

NASA Astrophysics Data System (ADS)

Kabanov, Dmitry; Kasimov, Aslan

2017-11-01

We propose a method to study linear stability of detonations by direct numerical computation. The linearized governing equations together with the shock-evolution equation are solved in the shock-attached frame using a high-resolution numerical algorithm. The computed results are processed by the Dynamic Mode Decomposition technique to generate dispersion relations. The method is applied to the reactive Euler equations with simple-depletion chemistry as well as more complex multistep chemistry. The results are compared with those known from normal-mode analysis. We acknowledge financial support from King Abdullah University of Science and Technology.

Ejected Particle Size Distributions from Shocked Metal Surfaces

DOE PAGES

Schauer, M. M.; Buttler, W. T.; Frayer, D. K.; ...

2017-04-12

Here, we present size distributions for particles ejected from features machined onto the surface of shocked Sn targets. The functional form of the size distributions is assumed to be log-normal, and the characteristic parameters of the distribution are extracted from the measured angular distribution of light scattered from a laser beam incident on the ejected particles. We also found strong evidence for a bimodal distribution of particle sizes with smaller particles evolved from features machined into the target surface and larger particles being produced at the edges of these features.

Ejected Particle Size Distributions from Shocked Metal Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schauer, M. M.; Buttler, W. T.; Frayer, D. K.

Here, we present size distributions for particles ejected from features machined onto the surface of shocked Sn targets. The functional form of the size distributions is assumed to be log-normal, and the characteristic parameters of the distribution are extracted from the measured angular distribution of light scattered from a laser beam incident on the ejected particles. We also found strong evidence for a bimodal distribution of particle sizes with smaller particles evolved from features machined into the target surface and larger particles being produced at the edges of these features.

Simulation of the Action of a Shock Wave on Titanium Alloy

NASA Astrophysics Data System (ADS)

Afanas'eva, S. A.; Belov, N. N.; Burkin, V. V.; Dudarev, E. F.; Ishchenko, A. N.; Rogaev, K. S.; Dudarev, E. F.; Ishchenko, A. N.; Rogaev, K. S.

2017-01-01

The laws and mechanism of fracture of coarse-grain and ultrafine-grain titanium under shock-wave loading has been investigated. For the shock wave generator a "SINUS-7" accelerator emitting a nanosecond relativistic highcurrent electron beam was used. To test the high-velocity impact at velocities of the order of 2500 m/s, a ballistic installation of caliber 23 mm was used. The mathematical simulation of the high-velocity interaction was carried out with account for the fracture, the phase transitions, and the dependence of the strength characteristics of materials on the internal energy within the framework of continuum mechanics. For both granular structures the general laws and features of the fracture have been established.

Low-Intensity Extracorporeal Shock Wave as a Novel Treatment for Erectile Dysfunction.

PubMed

Pan, Michael M; Raees, Ayman; Kovac, Jason R

2016-03-01

The paradigm of erectile dysfunction (ED) treatment was fundamentally altered following the introduction of oral phosphodiesterase type 5 inhibitors. Unfortunately, a significant number of men exhibit a suboptimal response and require additional management strategies. One of the novel, minimally invasive strategies being developed is low-intensity extracorporeal shock wave therapy. Used in the hope of delaying placement of an inflatable penile prosthesis, the final phase of ED treatment, low-intensity extracorporeal shock wave therapy is a unique application of an established technology that may hopefully one day expand the medical options for patients with ED. This commentary will highlight the physiology underlying this technique and summarize the most recent studies. © The Author(s) 2015.

A compilation of information and data on the Manson impact structure

NASA Technical Reports Server (NTRS)

Hartung, Jack B.; Anderson, Raymond R.

1988-01-01

A problem for the impact hypothesis for the Cretaceous-Tertiary (K-T) mass extinction is the apparent absence of an identifiable impact site. The Manson Impact Structure is a candidate because it is the largest recognized in the U.S.; it is relatively close to the largest and most abundant shocked quartz grains found at the K-T boundary; and its age is indistinguishable from that of the K-T boundary based on paleontological evidence, fission track dates, and preliminary Ar-40/Ar-39 measurements. The region of northwest central Iowa containing the Manson Impact Structure is covered by Quaternary glacial deposits underlain by Phanerozoic sedimentary rocks (mostly flat-lying carbonates) and Proterozoic red clastic, metamorphic, volcanic, and plutonic rocks. In a circular area about 22 miles (35 km) in diameter around Manson, Iowa, this normal sequence is absent or disturbed and near the center of the disturbed area granitic basement rocks have been uplifted some 20,000 ft (6000m). Attention was drawn to Manson initially by the unusual quality of the groundwater there. Within the structure three roughly concentric zones of rock associations have been identified: (1) displaced strata; (2) completely disrupted strata, and igneous and metamorphic rocks. Manson was established as an impact structure based on its circular shape, its central uplift, and the presence of shocked quartz within the granitic central uplift. A gravity survey identified locations of low-density brecciated rocks and high-density uplifted crystalline rocks, but the outer boundary of the structure could not be established. Aeromagnetic and ground magnetic surveys showed locations and depths of shallowly buried crystalline rock and the locations of faults. A refraction seismic survey identified the crystalline central uplift, determined that the average elevation of bedrock is 70 ft (20 m) higher outside the structure than within, and was used to map the bedrock topography within the structure. A connection between the Manson impact and the K-T boundary may be established or refuted through study of the impact energy, the impact time, and composition of host rock, possible impactors, and impact melts.

Unusual locations of Earth's bow shock on September 24 - 25, 1987: Mach number effects

NASA Technical Reports Server (NTRS)

Cairns, Iver H.; Fairfield, Donald H.; Anderson, Oger R.; Carlton, Victoria E. H.; Paularena, Karolen I.; Lazarus, Alan J.

1995-01-01

International Sun Earth Explorer 1 (ISEE 1) and Interplanetary Monitoring Platform 8 (IMP 8) data are used to identify 19 crossings of Earth's bow shock during a 30-hour period following 0000 UT on September 24, 1987. Apparent standoff distances for the shock are calculated for each crossing using two methods and the spacecraft location; one method assumes the average shock shape, while the other assumes a ram pressure-dependent shock shape. The shock's apparent standoff distance, normally approximately 14 R(sub E), is shown to increase from near 10 R(sub E) initially to near 19 R(sub E) during an 8-hour period, followed by an excursion to near 35 R(sub E) (where two IMP 8 shock crossings occur) and an eventual return to values smaller than 19 R(sub E). The Alfven M(sub A) and fast magnetosonic M(sub ms). Mach numbers remain above 2 and the number density above 4/cu cm for almost the entire period. Ram pressure effects produce the initial near-Earth shock location, whereas expansions and contractions of the bow shock due to low Mach number effects account, qualitatively and semiquantitatively, for the timing and existence of almost all the remaining ISEE crossings and both IMP 8 crossings. Significant quantitative differences exist between the apparent standoff distances for the shock crossings and those predicted using the observed plasma parameters and the standard model based on Spreiter et al.'s (1966) gasdynamic equation. These differences can be explained in terms of either a different dependence of the standoff distance on Mach number at low M(sub A) and M(sub ms), or variations in shock shape with M(sub A) and M(sub ms) (becoming increasingly "puffed up" with decreasing M(sub A) and M(sub ms), as expected theoretically), or by a combination of both effects.

Collisionless slow shocks in magnetotail reconnection

NASA Astrophysics Data System (ADS)

Cremer, Michael; Scholer, Manfred

The kinetic structure of collisionless slow shocks in the magnetotail is studied by solving the Riemann problem of the collapse of a current sheet with a normal magnetic field component using 2-D hybrid simulations. The collapse results in a current layer with a hot isotropic distribution and backstreaming ions in a boundary layer. The lobe plasma outside and within the boundary layer exhibits a large perpendicular to parallel temperature anisotropy. Waves in both regions propagate parallel to the magnetic field. In a second experiment a spatially limited high density beam is injected into a low beta background plasma and the subsequent wave excitation is studied. A model for slow shocks bounding the reconnection layer in the magnetotail is proposed where backstreaming ions first excite obliquely propagating waves by the electromagnetic ion/ion cyclotron instability, which lead to perpendicular heating. The T⊥/T∥ temperature anisotropy subsequently excites parallel propagating Alfvén ion cyclotron waves, which are convected into the slow shock and are refracted in the downstream region.

Experimental observations on the links between surface perturbation parameters and shock-induced mass ejection

NASA Astrophysics Data System (ADS)

Monfared, S. K.; Oró, D. M.; Grover, M.; Hammerberg, J. E.; LaLone, B. M.; Pack, C. L.; Schauer, M. M.; Stevens, G. D.; Stone, J. B.; Turley, W. D.; Buttler, W. T.

2014-08-01

We have assembled together our ejecta measurements from explosively shocked tin acquired over a period of about ten years. The tin was cast at 0.99995 purity, and all of the tin targets or samples were shocked to loading pressures of about 27 GPa, allowing meaningful comparisons. The collected data are markedly consistent, and because the total ejected mass scales linearly with the perturbations amplitudes they can be used to estimate how much total Sn mass will be ejected from explosively shocked Sn, at similar loading pressures, based on the surface perturbation parameters of wavelength and amplitude. Most of the data were collected from periodic isosceles shapes that approximate sinusoidal perturbations. Importantly, however, we find that not all periodic perturbations behave similarly. For example, we observed that sawtooth (right triangular) perturbations eject more mass than an isosceles perturbation of similar depth and wavelength, demonstrating that masses ejected from irregular shaped perturbations cannot be normalized to the cross-sectional areas of the perturbations.

Additive Effects of Threat-of-Shock and Picture Valence on Startle Reflex Modulation

PubMed Central

Bublatzky, Florian; Guerra, Pedro M.; Pastor, M. Carmen; Schupp, Harald T.; Vila, Jaime

2013-01-01

The present study examined the effects of sustained anticipatory anxiety on the affective modulation of the eyeblink startle reflex. Towards this end, pleasant, neutral and unpleasant pictures were presented as a continuous stream during alternating threat-of-shock and safety periods, which were cued by colored picture frames. Orbicularis-EMG to auditory startle probes and electrodermal activity were recorded. Previous findings regarding affective picture valence and threat-of-shock modulation were replicated. Of main interest, anticipating aversive events and viewing affective pictures additively modulated defensive activation. Specifically, despite overall potentiated startle blink magnitude in threat-of-shock conditions, the startle reflex remained sensitive to hedonic picture valence. Finally, skin conductance level revealed sustained sympathetic activation throughout the entire experiment during threat- compared to safety-periods. Overall, defensive activation by physical threat appears to operate independently from reflex modulation by picture media. The present data confirms the importance of simultaneously manipulating phasic-fear and sustained-anxiety in studying both normal and abnormal anxiety. PMID:23342060

Large-eddy simulation of the passage of a shock wave through homogeneous turbulence

NASA Astrophysics Data System (ADS)

Braun, N. O.; Pullin, D. I.; Meiron, D. I.

2017-11-01

The passage of a nominally plane shockwave through homogeneous, compressible turbulence is a canonical problem representative of flows seen in supernovae, supersonic combustion engines, and inertial confinement fusion. The interaction of isotropic turbulence with a stationary normal shockwave is considered at inertial range Taylor Reynolds numbers, Reλ = 100 - 2500 , using Large Eddy Simulation (LES). The unresolved, subgrid terms are approximated by the stretched-vortex model (Kosovic et al., 2002), which allows self-consistent reconstruction of the subgrid contributions to the turbulent statistics of interest. The mesh is adaptively refined in the vicinity of the shock to resolve small amplitude shock oscillations, and the implications of mesh refinement on the subgrid modeling are considered. Simulations are performed at a range of shock Mach numbers, Ms = 1.2 - 3.0 , and turbulent Mach numbers, Mt = 0.06 - 0.18 , to explore the parameter space of the interaction at high Reynolds number. The LES shows reasonable agreement with linear analysis and lower Reynolds number direct numerical simulations. LANL Subcontract 305963.

Statistical behavior of post-shock overpressure past grid turbulence

NASA Astrophysics Data System (ADS)

Sasoh, Akihiro; Harasaki, Tatsuya; Kitamura, Takuya; Takagi, Daisuke; Ito, Shigeyoshi; Matsuda, Atsushi; Nagata, Kouji; Sakai, Yasuhiko

2014-09-01

When a shock wave ejected from the exit of a 5.4-mm inner diameter, stainless steel tube propagated through grid turbulence across a distance of 215 mm, which is 5-15 times larger than its integral length scale , and was normally incident onto a flat surface; the peak value of post-shock overpressure, , at a shock Mach number of 1.0009 on the flat surface experienced a standard deviation of up to about 9 % of its ensemble average. This value was more than 40 times larger than the dynamic pressure fluctuation corresponding to the maximum value of the root-mean-square velocity fluctuation, . By varying and , the statistical behavior of was obtained after at least 500 runs were performed for each condition. The standard deviation of due to the turbulence was almost proportional to . Although the overpressure modulations at two points 200 mm apart were independent of each other, we observed a weak positive correlation between the peak overpressure difference and the relative arrival time difference.

Effect of multipath laser shock processing on microhardness, surface roughness, and wear resistance of 2024-T3 Al alloy.

PubMed

Kadhim, Abdulhadi; Salim, Evan T; Fayadh, Saeed M; Al-Amiery, Ahmed A; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

2014-01-01

Laser shock processing (LSP) is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. LSP is based on the application of a high intensity pulsed laser beam (I > 1 GW/cm(2); t < 50 ns) at the interface between the metallic target and the surrounding medium (a transparent confining material, normally water) forcing a sudden vaporization of the metallic surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The shock wave induces plastic deformation and a residual stress distribution in the target material. In this paper we study the increase of microhardness and surface roughness with the increase of laser pulse energy in 2024-T3 Al alloy. The influence of the thickness of the confining layer (water) on microhardness and surface roughness is also studied. In addition, the effect of LSP treatment with best conditions on wear behaviors of the alloy was investigated.

Characterizing detonator output using dynamic witness plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, Michael John; Adrian, Ronald J

2009-01-01

A sub-microsecond, time-resolved micro-particle-image velocimetry (PIV) system is developed to investigate the output of explosive detonators. Detonator output is directed into a transparent solid that serves as a dynamic witness plate and instantaneous shock and material velocities are measured in a two-dimensional plane cutting through the shock wave as it propagates through the solid. For the case of unloaded initiators (e.g. exploding bridge wires, exploding foil initiators, etc.) the witness plate serves as a surrogate for the explosive material that would normally be detonated. The velocity-field measurements quantify the velocity of the shocked material and visualize the geometry of themore » shocked region. Furthermore, the time-evolution of the velocity-field can be measured at intervals as small as 10 ns using the PIV system. Current experimental results of unloaded exploding bridge wire output in polydimethylsiloxane (PDMS) witness plates demonstrate 20 MHz velocity-field sampling just 300 ns after initiation of the wire.« less

Generalized Pseudo-Reaction Zone Model for Non-Ideal Explosives

NASA Astrophysics Data System (ADS)

Wescott, Bradley

2007-06-01

The pseudo-reaction zone model was proposed to improve engineering scale simulations when using Detonation Shock Dynamics with high explosives that have a slow reaction component. In this work an extension of the pseudo-reaction zone model is developed for non-ideal explosives that propagate well below their steady-planar Chapman-Jouguet velocity. A programmed burn method utilizing Detonation Shock Dynamics and a detonation velocity dependent pseudo-reaction rate has been developed for non-ideal explosives and applied to the explosive mixture of ammonium nitrate and fuel oil (ANFO). The pseudo-reaction rate is calibrated to the experimentally obtained normal detonation velocity---shock curvature relation. The generalized pseudo-reaction zone model proposed here predicts the cylinder expansion to within 1% by accounting for the slow reaction in ANFO.

Direct Numerical Simulation of Acoustic Waves Interacting with a Shock Wave in a Quasi-1D Convergent-Divergent Nozzle Using an Unstructured Finite Volume Algorithm

NASA Technical Reports Server (NTRS)

Bui, Trong T.; Mankbadi, Reda R.

1995-01-01

Numerical simulation of a very small amplitude acoustic wave interacting with a shock wave in a quasi-1D convergent-divergent nozzle is performed using an unstructured finite volume algorithm with a piece-wise linear, least square reconstruction, Roe flux difference splitting, and second-order MacCormack time marching. First, the spatial accuracy of the algorithm is evaluated for steady flows with and without the normal shock by running the simulation with a sequence of successively finer meshes. Then the accuracy of the Roe flux difference splitting near the sonic transition point is examined for different reconstruction schemes. Finally, the unsteady numerical solutions with the acoustic perturbation are presented and compared with linear theory results.

Investigation of Three-Dimensional Unsteady Flow Characteristics in Transonic Diffusers

NASA Astrophysics Data System (ADS)

Proshchanka, Dzianis; Yonezawa, Koichi; Tsujimoto, Yoshinobu

Three-dimensional characteristics of unsteady flow in supercritical transonic diffuser are investigated. For various pressure ratios three-dimensional flow containing a normal shock/turbulent boundary layer interaction regions with shockwave and pseudo-shockwaves fluctuating in longitudinal and spanwise directions is observed. Experimental and numerical investigations show details of the flowfield in the vicinity of terminal shock, interaction regions and downstream turbulent unsteady flow. Spectral analysis of pressure fluctuations reveals existence of two characteristic frequencies attributed to the shockwave fluctuation in longitudinal direction for the lower frequency case and acoustic resonance in spanwise direction for the higher one. Vortices appear at each corner in transversal sections modifying the core flow. As a result, size and depth of longitudinal and vertical penetration of separation regions impelled by the terminal shock is either increased or decreased.

[Determination of mRNA-transcripts and heat shock proteins HSP70 and HSP90 in retina of the adult Spanish Ribbed Newt Pleurodeles waltl].

PubMed

Avdonin, P P; Markitantova, Yu V; Poplinskaya, V A; Grigoryan, E N

2013-01-01

Expression of genes and heat shock proteins in normal intact retina of the Spanish Ribbed Newt Pleurodeles waltl was studied using polymerase chain reaction, Western blot hybridization, and immunohistochemistry. It was shown that the proteins HSP70 and HSP90, as well as their encoding transcripts of relevant genes, are constitutively expressed in eye tissues. These proteins were distributed differentially, and they were characterized by expression of different levels in the retina: HSP70 dominated in the external retina, while HSP90 dominated in the internal one, in particular, in Muller glial cells and the optic nerve. Transcripts and heat shock proteins HSP70 and HSP90 were also found in the retinal pigment epithelium and eye growth zone.

Metabolic studies with NMR spectroscopy of the alga Dunaliella salina trapped within agarose beads.

PubMed

Bental, M; Pick, U; Avron, M; Degani, H

1990-02-22

A technique for the entrapment of the unicellular algae Dunaliella salina in agarose beads and their perfusion during NMR measurements is presented. The trapped cells maintained their ability to proliferate under normal growth conditions, and remained viable and stable under steady-state conditions for long periods during NMR measurements. Following osmotic shock in the dark, prominent changes were observed in the intracellular level of ATP and polyphosphates, but little to no changes in the intracellular pH or orthoposphate content. When cells were subjected to hyperosmotic shock, the ATP level decreased. The content of NMR-visible polyphosphates decreased as well, presumably due to the production of longer, NMR-invisible structures. Following hypoosmotic shock, the ATP content increased and longer polyphosphates were broken down to shorter, more mobile polymers.

An in situ Comparison of Electron Acceleration at Collisionless Shocks under Differing Upstream Magnetic Field Orientations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masters, A.; Dougherty, M. K.; Sulaiman, A. H.

A leading explanation for the origin of Galactic cosmic rays is acceleration at high-Mach number shock waves in the collisionless plasma surrounding young supernova remnants. Evidence for this is provided by multi-wavelength non-thermal emission thought to be associated with ultrarelativistic electrons at these shocks. However, the dependence of the electron acceleration process on the orientation of the upstream magnetic field with respect to the local normal to the shock front (quasi-parallel/quasi-perpendicular) is debated. Cassini spacecraft observations at Saturn’s bow shock have revealed examples of electron acceleration under quasi-perpendicular conditions, and the first in situ evidence of electron acceleration at amore » quasi-parallel shock. Here we use Cassini data to make the first comparison between energy spectra of locally accelerated electrons under these differing upstream magnetic field regimes. We present data taken during a quasi-perpendicular shock crossing on 2008 March 8 and during a quasi-parallel shock crossing on 2007 February 3, highlighting that both were associated with electron acceleration to at least MeV energies. The magnetic signature of the quasi-perpendicular crossing has a relatively sharp upstream–downstream transition, and energetic electrons were detected close to the transition and immediately downstream. The magnetic transition at the quasi-parallel crossing is less clear, energetic electrons were encountered upstream and downstream, and the electron energy spectrum is harder above ∼100 keV. We discuss whether the acceleration is consistent with diffusive shock acceleration theory in each case, and suggest that the quasi-parallel spectral break is due to an energy-dependent interaction between the electrons and short, large-amplitude magnetic structures.« less

Intractable bone marrow edema syndrome of the hip.

PubMed

Gao, Fuqiang; Sun, Wei; Li, Zirong; Guo, Wanshou; Kush, Nepali; Ozaki, Koji

2015-04-01

There is a need for an effective and noninvasive treatment for intractable bone marrow edema syndrome of the hip. Forty-six patients with intractable bone marrow edema syndrome of the hip were retrospectively studied to compare the short-term clinical effects of treatment with high-energy extracorporeal shock wave therapy vs femoral head core decompression. The postoperative visual analog scale score decreased significantly more in the extracorporeal shock wave therapy group compared with the femoral head core decompression group (P<.05). For unilateral lesions, postoperative Harris Hip Scores for all hips in the extracorporeal shock wave therapy group were more significantly improved than Harris Hip Scores for all hips in the femoral head core decompression group (P<.05). Patients who underwent extracorporeal shock wave therapy also resumed daily activities significantly earlier. Average overall operative time was similar in both groups. Symptoms disappeared significantly sooner in the extracorporeal shock wave therapy group in patients with both unilateral (P<.01) and bilateral lesions (P<.05). Hospital costs were significantly lower with extracorporeal shock wave therapy compared with femoral head core decompression. The intraoperative fluoroscopy radiation dose was lower in extracorporeal shock wave therapy than in femoral head core decompression for both unilateral (P<.05) and bilateral lesions (P<.01). On magnetic resonance imaging (MRI), bone marrow edema improved in all patients during the follow-up period. After extracorporeal shock wave therapy, all patients remained pain-free and had normal findings on posttreatment radiographs and MRI scans. Extracorporeal shock wave therapy appears to be a valid, reliable, and noninvasive tool for rapidly resolving intractable bone marrow edema syndrome of the hip, and it has a low complication rate and relatively low cost compared with other conservative and surgical treatment approaches. Copyright 2015, SLACK Incorporated.

Does extracorporeal shock wave lithotripsy cause hearing impairment in children?

PubMed

Tuncer, Murat; Sahin, Cahit; Yazici, Ozgur; Kafkasli, Alper; Turk, Akif; Erdogan, Banu A; Faydaci, Gokhan; Sarica, Kemal

2015-03-01

We evaluated the possible effects of noise created by high energy shock waves on the hearing function of children treated with extracorporeal shock wave lithotripsy. A total of 65 children with normal hearing function were included in the study. Patients were divided into 3 groups, ie those becoming stone-free after 1 session of shock wave lithotripsy (group 1, 22 children), those requiring 3 sessions to achieve stone-free status (group 2, 21) and healthy children/controls (group 3, 22). Extracorporeal shock wave lithotripsy was applied with patients in the supine position with a 90-minute frequency and a total of 2,000 shock waves in each session (Compact Sigma, Dornier MedTech, Wessling, Germany). Second energy level was used with a maximum energy value of 58 joules per session in all patients. Hearing function and possible cochlear impairment were evaluated by transient evoked otoacoustic emissions test at 1.0, 1.4, 2.0, 2.8 and 4.0 kHz frequencies before the procedure, 2 hours later, and 1 month after completion of the first shock wave lithotripsy session in groups 1 and 2. In controls the same evaluation procedures were performed at the beginning of the study and 7 weeks later. Regarding transient evoked otoacoustic emissions data, in groups 1 and 2 there was no significant alteration in values obtained after shock wave lithotripsy compared to values obtained at the beginning of the study, similar to controls. A well planned shock wave lithotripsy procedure is a safe and effective treatment in children with urinary stones and causes no detectable harmful effect on hearing function. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Electron temperature and de Hoffmann-Teller potential change across the Earth's bow shock: New results from ISEE 1

NASA Astrophysics Data System (ADS)

Hull, A. J.; Scudder, J. D.; Fitzenreiter, R. J.; Ogilvie, K. W.; Newbury, J. A.; Russell, C. T.

We present a survey of the trends between the electron temperature increase ΔTe and the de Hoffmann-Teller frame (HTF) electrostatic potential jump ΔΦHT and their correlation with other parameters that characterize the shock transition using a new ISEE 1 database of 129 Earth bow shock crossings. A fundamental understanding of the HTF potential is central to distinguishing the reversible and irreversible changes to electron temperature across collisionless shocks. The HTF potential is estimated using three different techniques: (1) integrating the steady state, electron fluid momentum equation across the shock layer using high time resolution plasma and field data from ISEE 1, (2) using the steady state, electron fluid energy equation, and (3) using an electron polytrope approximation. We find that ΔΦHT and ΔTe are strongly and positively correlated with |Δ(mpUn2/2)|, which is in good qualitative agreement with earlier experimental surveys [Thomsen et al., 1987b; Schwartz et al., 1988] that used bow shock model normals and used the flow in the spacecraft frame. There is a strong linear organization of the ΔTe with ΔΦHT, which suggests an average effective electron polytropic index of <γe>~2. In addition, ΔTe and ΔΦHT are organized by βe, although our results may be biased by our limited sampling of shock conditions. Comparisons indicate that the differentials in the HTF potential δΦHT are proportional to the differentials in the magnetic field intensity δB across the shock, with a proportionality constant κ that is a fixed constant for a given shock crossing.

[Acute renal failure in a prisoner after hunger strike].

PubMed

Gorsane, Imène; Zouaghi, Karim; Goucha, Rim; El Younsi, Fethi; Hedri, Hafedh; Barbouch, Samia; Ben Abdallah, Taïeb; Ben Moussa, Fatma; Ben Maiz, Hedi; Kheder, Adel

2007-03-01

Acute renal failure may occur in varied circumstances. It is potentially reversible spontaneously or after specific treatment. It is rare after hunger strike and fewer cases were reported in the literature. The physiopathological mechanisms are varied and remain incompletely known. We report the case of a prisoner having presented an acute renal failure after a hunger strike wich was completely reversible. He's a 29 year old man, without a past medical facts, in July 2004 he was incarcereted in prison. In October 2004 he undertake a hunger strike during one month. In November 2004 he was hospitalized for global dehydration and shock. His physical examination showed blood pressure 60/40 mmHg, weight 59 Kg with a loss of weight about 10 Kg, diuresis 800 cc/day. His biological findings showed urea 100 mmol/l, creatinemia 679 (mo/l, natremia 179 mmol/l, kaliemia 5 mmol/l, glycemia 5.2 mmol/l, albuminemia 35 g/l, calcemia 2.35 mmol/l and biological marques of rhabdomyolysis: CPK at 11 times the normal and LDH two times the normal. His treatment consisted on rehydratation, parenteral then enteral refeeding and psychiatric talks. The evolution was favourable, re-establishment of good hydration state with a gain weight of 7 Kg, normalization of renal function, his creatininemia reached 85 (mol/l in three weeks and normalization of muscles enzymes in one month. Hunger strike continue to pose a problem because of it's frequency in penitentiary structures and its organic disorders which can lead to death. A good psychiatric cares may be undertaked in order to prevent a such bad manifestations.

Numerical study on tailoring the shock sensitivity of TATB-based explosives using mesostructural features

NASA Astrophysics Data System (ADS)

Springer, H. Keo

2017-06-01

Advanced manufacturing techniques offer control of explosive mesostructures necessary to tailor its shock sensitivity. However, structure-property relationships are not well established for explosives so there is little material design guidance for these techniques. The objective of this numerical study is to demonstrate how TATB-based explosives can be sensitized to shocks using mesostructural features. For this study, we use LX-17 (92.5%wt TATB, 7.5%wt Kel-F 800) as the prototypical TATB-based explosive. We employ features with different geometries and materials. HMX-based explosive features, high shock impedance features, and pores are used to sensitive the LX-17. Simulations are performed in the multi-physics hydrocode, ALE3D. A reactive flow model is used to simulate the shock initiation response of the explosives. Our metric for shock sensitivity in this study is run distance to detonation as a function of applied pressure. These numerical studies are important because they guide the design of novel energetic materials. This work was performed under the auspices of the United States Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-724986.

The Riemann problem for the relativistic full Euler system with generalized Chaplygin proper energy density-pressure relation

NASA Astrophysics Data System (ADS)

Shao, Zhiqiang

2018-04-01

The relativistic full Euler system with generalized Chaplygin proper energy density-pressure relation is studied. The Riemann problem is solved constructively. The delta shock wave arises in the Riemann solutions, provided that the initial data satisfy some certain conditions, although the system is strictly hyperbolic and the first and third characteristic fields are genuinely nonlinear, while the second one is linearly degenerate. There are five kinds of Riemann solutions, in which four only consist of a shock wave and a centered rarefaction wave or two shock waves or two centered rarefaction waves, and a contact discontinuity between the constant states (precisely speaking, the solutions consist in general of three waves), and the other involves delta shocks on which both the rest mass density and the proper energy density simultaneously contain the Dirac delta function. It is quite different from the previous ones on which only one state variable contains the Dirac delta function. The formation mechanism, generalized Rankine-Hugoniot relation and entropy condition are clarified for this type of delta shock wave. Under the generalized Rankine-Hugoniot relation and entropy condition, we establish the existence and uniqueness of solutions involving delta shocks for the Riemann problem.

Variational formulation of hybrid problems for fully 3-D transonic flow with shocks in rotor

NASA Technical Reports Server (NTRS)

Liu, Gao-Lian

1991-01-01

Based on previous research, the unified variable domain variational theory of hybrid problems for rotor flow is extended to fully 3-D transonic rotor flow with shocks, unifying and generalizing the direct and inverse problems. Three variational principles (VP) families were established. All unknown boundaries and flow discontinuities (such as shocks, free trailing vortex sheets) are successfully handled via functional variations with variable domain, converting almost all boundary and interface conditions, including the Rankine Hugoniot shock relations, into natural ones. This theory provides a series of novel ways for blade design or modification and a rigorous theoretical basis for finite element applications and also constitutes an important part of the optimal design theory of rotor bladings. Numerical solutions to subsonic flow by finite elements with self-adapting nodes given in Refs., show good agreement with experimental results.

Inconsistent shock advisories for monomorphic VT and Torsade de Pointes--A prospective experimental study on AEDs and defibrillators.

PubMed

Fitzgerald, Abi; Johnson, Meshell; Hirsch, Jan; Rich, Mary-Ann; Fidler, Richard

2015-07-01

Cardiovascular disease and sudden cardiac arrest are the leading causes of death in the United States. Early defibrillation is key to successful resuscitation for patients who experience shockable rhythms during a cardiac arrest. It is therefore vital that the shock advisory of AEDs (automated external defibrillators) or defibrillators in AED mode be reliable and appropriate. The goal of this study was to better understand the performance of multiple lay-rescuer and hospital professional defibrillators in AED mode in their analysis of ventricular arrhythmias. The measurable objectives of this study sought to quantify: 1. No shock advisory for sinus rhythms at any rate. 2. Recognition and shock advisory for ventricular fibrillation (VF). 3. Recognition and shock advisory for monomorphic ventricular tachycardia (VT). 4. Recognition and shock advisory for Torsades de Pointes (TdP). This is a prospective evaluation of two AEDs and four semi-automatic, hospital professional defibrillators. This study represents post-marketing evaluation of FDA approved devices. Each defibrillator was connected to multiple rhythm simulators and presented with simulated ECG waveforms 20 consecutive times at various rates when possible. All four defibrillators and both AEDs tested consistently recognized normal sinus rhythm (NSR) from all rhythm sources, and did not recommend a shock for NSR at any rate (from 80 to 220 bpm). All four defibrillators and both AEDs recognized VF from all rhythm sources tested and recommended a shock 100% of the time. Variations were found in the shock advisory rates among defibrillators when testing simulated VT heart rates at or below 150 bpm. One AED tested did not consistently advise a shock for monomorphic VT or TdP at any tested rate. Lay-rescuer AEDs and professional hospital defibrillators tested in AED mode did not reliably recommend a shock for sustained monomorphic VT or TdP at certain rates, despite the fact that it is a critical component of the currently recommended treatment. These findings require further examination of the risk benefit analysis of shocking or not shocking rhythms such as TdP or pulseless VT. Published by Elsevier Ireland Ltd.

A new facility for studying shock-wave passage over dust layers

NASA Astrophysics Data System (ADS)

Chowdhury, A. Y.; Marks, B. D.; Johnston, H. Greg; Mannan, M. Sam; Petersen, E. L.

2016-03-01

Dust explosion hazards in areas where coal and other flammable materials are found have caused unnecessary loss of life and halted business operations in some instances. The elimination of secondary dust explosion hazards, i.e., reducing dust dispersion, can be characterized in shock tubes to understand shock-dust interactions. For this reason, a new shock-tube test section was developed and integrated into an existing shock-tube facility. The test section has large windows to allow for the use of the shadowgraph technique to track dust-layer growth behind a passing normal shock wave, and it is designed to handle an initial pressure of 1 atm with an incident shock wave Mach number as high as 2 to mimic real-world conditions. The test section features an easily removable dust pan with inserts to allow for adjustment of the dust-layer thickness. The design also allows for changing the experimental variables such as initial pressure, shock Mach number (Ms), dust-layer thickness, and the characteristics of the dust itself. The characterization experiments presented herein demonstrate the advantages of the authors' test techniques toward providing new physical insights over a wider range of data than what have been available heretofore in the literature. Limestone dust with a layer thickness of 3.2 mm was subjected to Ms = 1.23, 1.32, and 1.6 shock waves, and dust-layer rise height was mapped with respect to time after shock passage. Dust particles subjected to a Ms = 1.6 shock wave rose more rapidly and to a greater height with respect to shock wave propagation than particles subjected to Ms = 1.23 and 1.32 shock waves. Although these results are in general agreement with the literature, the new data also highlight physical trends for dust-layer growth that have not been recorded previously, to the best of the authors' knowledge. For example, the dust-layer height rises linearly until a certain time where the growth rate is dramatically reduced, and in this second regime there is clear evidence of surface vertical structures at the dust-air interface.

Flow establishment behind blunt bodies at hypersonic speeds in a shock tunnel

NASA Astrophysics Data System (ADS)

Park, G.; Hruschka, R.; Gai, S. L.; Neely, A. J.

2008-11-01

An investigation of flow establishment behind two blunt bodies, a circular cylinder and a 45° half-angle blunted-cone was conducted. Unlike previous studies which relied solely on surface measurements, the present study combines these with unique high-speed visualisation to image the establishment of the flow structure in the base region. Test flows were generated using a free-piston shock tunnel at a nominal Mach number of 10. The freestream unit Reynolds numbers considered were 3.02x105/m and 1.17x106/m at total enthalpies of 13.35MJ/kg and 3.94MJ/kg, respectively. In general, the experiments showed that it takes longer to establish steady heat flux than pressure. The circular cylinder data showed that the near wake had a slight Reynolds number effect, where the size of the near wake was smaller for the high enthalpy flow condition. The blunted-cone data showed that the heat flux and pressures reached steady states in the near wake at similar times for both high and low enthalpy conditions.

Agreement in electrocardiogram interpretation in patients with septic shock.

PubMed

Mehta, Sangeeta; Granton, John; Lapinsky, Stephen E; Newton, Gary; Bandayrel, Kristofer; Little, Anjuli; Siau, Chuin; Cook, Deborah J; Ayers, Dieter; Singer, Joel; Lee, Terry C; Walley, Keith R; Storms, Michelle; Cooper, Jamie; Holmes, Cheryl L; Hebert, Paul; Gordon, Anthony C; Presneill, Jeff; Russell, James A

2011-09-01

The reliability of electrocardiogram interpretation to diagnose myocardial ischemia in critically ill patients is unclear. In adults with septic shock, we assessed intra- and inter-rater agreement of electrocardiogram interpretation, and the effect of knowledge of troponin values on these interpretations. Prospective substudy of a randomized trial of vasopressin vs. norepinephrine in septic shock. Nine Canadian intensive care units. Adults with septic shock requiring at least 5 μg/min of norepinephrine for 6 hrs. Twelve-lead electrocardiograms were recorded before study drug, and 6 hrs, 2 days, and 4 days after study drug initiation. Two physician readers, blinded to patient data and group, independently interpreted electrocardiograms on three occasions (first two readings were blinded to patient data; third reading was unblinded to troponin). To calibrate and refine definitions, both readers initially reviewed 25 trial electrocardiograms representing normal to abnormal. Cohen's Kappa and the φ statistic were used to analyze intra- and inter-rater agreement. One hundred twenty-one patients (62.2 ± 16.5 yrs, Acute Physiology and Chronic Health Evaluation II 28.6 ± 7.7) had 373 electrocardiograms. Blinded to troponin, readers 1 and 2 interpreted 46.4% and 30.0% of electrocardiograms as normal, and 15.3% and 12.3% as ischemic, respectively. Intrarater agreement was moderate for overall ischemia (κ 0.54 and 0.58), moderate/good for "normal" (κ 0.69 and 0.55), fair to good for specific signs of ischemia (ST elevation, T inversion, and Q waves, reader 1 κ 0.40 to 0.69; reader 2 κ 0.56 to 0.70); and good/very good for atrial arrhythmias (κ 0.84 and 0.79) and bundle branch block (κ 0.88 and 0.79). Inter-rater agreement was fair for ischemia (κ 0.29), moderate for ST elevation (κ 0.48), T inversion (κ 0.52), and Q waves (κ 0.44), good for bundle branch block (κ 0.78), and very good for atrial arrhythmias (κ 0.83). Inter-rater agreement for ischemia improved from fair to moderate (κ 0.52, p = .028) when unblinded to troponin. In patients with septic shock, inter-rater agreement of electrocardiogram interpretation for myocardial ischemia was fair, and improved with troponin knowledge.

An experimental investigation of shock wave-turbulent boundary layer interactions with and without boundary layer suction: A data summary report

NASA Technical Reports Server (NTRS)

Sun, C. C.; Childs, M. E.

1977-01-01

Tabulated data from a series of experimental studies of the interaction of a shock wave with a turbulent boundary layer in axisymmetric flow configurations is presented. The studies were conducted at the walls of circular wind tunnels and on the cylindrical centerbody of an annular flow channel. Detailed pitot pressure profiles and wall static pressure profiles upstream of, within and downstream of the interaction region are given. Results are presented for flows at nominal freestream Mach Numbers of 2, 3 and 4. For studies at the tunnel sidewalls, the shock waves were produced by conical shock generators mounted on the centerline of the wind tunnel at zero angle of attack. The annular ring generator was used to produce the shock wave at the centerbody of the annular flow channel. The effects of boundary layer bleed were examined in the investigation. Both bleed rate and bleed location were studied. Most of the bleed studies were conducted with bleed holes drilled normal to the wall surface but the effects of slot suction were also examined. A summary of the principal results and conclusions is given.

DebtRank: A Microscopic Foundation for Shock Propagation.

PubMed

Bardoscia, Marco; Battiston, Stefano; Caccioli, Fabio; Caldarelli, Guido

2015-01-01

The DebtRank algorithm has been increasingly investigated as a method to estimate the impact of shocks in financial networks, as it overcomes the limitations of the traditional default-cascade approaches. Here we formulate a dynamical "microscopic" theory of instability for financial networks by iterating balance sheet identities of individual banks and by assuming a simple rule for the transfer of shocks from borrowers to lenders. By doing so, we generalise the DebtRank formulation, both providing an interpretation of the effective dynamics in terms of basic accounting principles and preventing the underestimation of losses on certain network topologies. Depending on the structure of the interbank leverage matrix the dynamics is either stable, in which case the asymptotic state can be computed analytically, or unstable, meaning that at least one bank will default. We apply this framework to a dataset of the top listed European banks in the period 2008-2013. We find that network effects can generate an amplification of exogenous shocks of a factor ranging between three (in normal periods) and six (during the crisis) when we stress the system with a 0.5% shock on external (i.e. non-interbank) assets for all banks.

Assessment of In Situ Time Resolved Shock Experiments at Synchrotron Light Sources*

NASA Astrophysics Data System (ADS)

Belak, J.; Ilavsky, J.; Hessler, J. P.

2005-07-01

Prior to fielding in situ time resolved experiments of shock wave loading at the Advanced Photon Source, we have performed feasibility experiments assessing a single photon bunch. Using single and poly-crystal Al, Ti, V and Cu shock to incipient spallation on the gas gun, samples were prepared from slices normal to the spall plane of thickness 100-500 microns. In addition, single crystal Al of thickness 500 microns was shocked to incipient spallation and soft recovered using the LLNL e-gun mini-flyer system. The e-gun mini-flyer impacts the sample target producing a 10's ns flat-top shock transient. Here, we present results for imaging, small-angle scattering (SAS), and diffraction. In particular, there is little SAS away from the spall plane and significant SAS at the spall plane, demonstrating the presence of sub-micron voids. * Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38 and work performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

DebtRank: A Microscopic Foundation for Shock Propagation

PubMed Central

Bardoscia, Marco; Battiston, Stefano; Caccioli, Fabio; Caldarelli, Guido

2015-01-01

The DebtRank algorithm has been increasingly investigated as a method to estimate the impact of shocks in financial networks, as it overcomes the limitations of the traditional default-cascade approaches. Here we formulate a dynamical “microscopic” theory of instability for financial networks by iterating balance sheet identities of individual banks and by assuming a simple rule for the transfer of shocks from borrowers to lenders. By doing so, we generalise the DebtRank formulation, both providing an interpretation of the effective dynamics in terms of basic accounting principles and preventing the underestimation of losses on certain network topologies. Depending on the structure of the interbank leverage matrix the dynamics is either stable, in which case the asymptotic state can be computed analytically, or unstable, meaning that at least one bank will default. We apply this framework to a dataset of the top listed European banks in the period 2008–2013. We find that network effects can generate an amplification of exogenous shocks of a factor ranging between three (in normal periods) and six (during the crisis) when we stress the system with a 0.5% shock on external (i.e. non-interbank) assets for all banks. PMID:26091013

Advantage of four-electrode over two-electrode defibrillators

NASA Astrophysics Data System (ADS)

Bragard, J.; Šimić, A.; Laroze, D.; Elorza, J.

2015-12-01

Defibrillation is the standard clinical treatment used to stop ventricular fibrillation. An electrical device delivers a controlled amount of electrical energy via a pair of electrodes in order to reestablish a normal heart rate. We propose a technique that is a combination of biphasic shocks applied with a four-electrode system rather than the standard two-electrode system. We use a numerical model of a one-dimensional ring of cardiac tissue in order to test and evaluate the benefit of this technique. We compare three different shock protocols, namely a monophasic and two types of biphasic shocks. The results obtained by using a four-electrode system are compared quantitatively with those obtained with the standard two-electrode system. We find that a huge reduction in defibrillation threshold is achieved with the four-electrode system. For the most efficient protocol (asymmetric biphasic), we obtain a reduction in excess of 80% in the energy required for a defibrillation success rate of 90%. The mechanisms of successful defibrillation are also analyzed. This reveals that the advantage of asymmetric biphasic shocks with four electrodes lies in the duration of the cathodal and anodal phase of the shock.

Monte Carlo simulations of thermal comptonization process in a two-component advective flow around a neutron star

NASA Astrophysics Data System (ADS)

Bhattacharjee, Ayan; Chakrabarti, Sandip K.

2017-12-01

We explore spectral properties of a two-component advective flow around a neutron star. We compute the effects of thermal Comptonization of soft photons emitted from a Keplerian disc and the boundary layer of the neutron star by the post-shock region of a sub-Keplerian flow, formed due to the centrifugal barrier. The shock location Xs is also the inner edge of the Keplerian disc. We compute a series of realistic spectra assuming a set of electron temperatures of the post-shock region TCE, the temperature of the Normal BOundary Layer (NBOL) TNS of the neutron star and the shock location Xs. These parameters depend on the disc and halo accretion rates (\\dot{m}d and \\dot{m}h, respectively) that control the resultant spectra. We find that the spectrum becomes harder when \\dot{m}_h is increased. The spectrum is controlled strongly by TNS due to its proximity to the Comptonizing cloud since photons emitted from the NBOL cool down the post-shock region very effectively. We also show the evidence of spectral hardening as the inclination angle of the disc is increased.

The existence of electron-acoustic shock waves and their interactions in a non-Maxwellian plasma with q-nonextensive distributed electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jiu-Ning; He, Yong-Lin; Han, Zhen-Hai

2013-07-15

We present a theoretical investigation for the nonlinear interaction between electron-acoustic shock waves in a nonextensive two-electron plasma. The interaction is governed by a pair of Korteweg-de Vries-Burgers equations. We focus on studying the colliding effects on the propagation of shock waves, more specifically, we have studied the effects of plasma parameters, i.e., the nonextensive parameter q, the “hot” to “cold” electron number density ratio α, and the normalized electron kinematic viscosity η{sub 0} on the trajectory changes (phase shifts) of shock waves. It is found that there are trajectory changes (phase shifts) for both colliding shock waves in themore » present plasma system. We also noted that the nonlinearity has no decisive effect on the trajectory changes, the occurrence of trajectory changes may be due to the combined role played by the dispersion and dissipation of the nonlinear structure. Our theoretical study may be beneficial to understand the propagation and interaction of nonlinear electrostatic waves and may brings a possibility to develop the nonlinear theory of electron-acoustic waves in astrophysical plasma systems.« less

Sequence and structure determinants of Drosophila Hsp70 mRNA translation: 5'UTR secondary structure specifically inhibits heat shock protein mRNA translation.

PubMed Central

Hess, M A; Duncan, R F

1996-01-01

Preferential translation of Drosophila heat shock protein 70 (Hsp70) mRNA requires only the 5'-untranslated region (5'-UTR). The sequence of this region suggests that it has relatively little secondary structure, which may facilitate efficient protein synthesis initiation. To determine whether minimal 5'-UTR secondary structure is required for preferential translation during heat shock, the effect of introducing stem-loops into the Hsp70 mRNA 5'-UTR was measured. Stem-loops of -11 kcal/mol abolished translation during heat shock, but did not reduce translation in non-heat shocked cells. A -22 kcal/mol stem-loop was required to comparably inhibit translation during growth at normal temperatures. To investigate whether specific sequence elements are also required for efficient preferential translation, deletion and mutation analyses were conducted in a truncated Hsp70 5'-UTR containing only the cap-proximal and AUG-proximal segments. Linker-scanner mutations in the cap-proximal segment (+1 to +37) did not impair translation. Re-ordering the segments reduced mRNA translational efficiency by 50%. Deleting the AUG-proximal segment severely inhibited translation. A 5-extension of the full-length leader specifically impaired heat shock translation. These results indicate that heat shock reduces the capacity to unwind 5-UTR secondary structure, allowing only mRNAs with minimal 5'-UTR secondary structure to be efficiently translated. A function for specific sequences is also suggested. PMID:8710519

Retrieval per se is not sufficient to trigger reconsolidation of human fear memory.

PubMed

Sevenster, Dieuwke; Beckers, Tom; Kindt, Merel

2012-03-01

Ample evidence suggests that consolidated memories, upon their retrieval, enter a labile state, in which they might be susceptible to change. It has been proposed that memory labilization allows for the integration of relevant information in the established memory trace (memory updating). Memory labilization and reconsolidation do not necessarily occur when a memory is being reactivated, but only when there is something to be learned during memory retrieval (prediction error). Thus, updating of a fear memory trace should not occur under retrieval conditions in which the outcome is fully predictable (no prediction error). Here, we addressed this issue, using a human differential fear conditioning procedure, by eliminating the very possibility of reinforcement of the reminder cue. A previously established fear memory (picture-shock pairings) was reactivated with shock-electrodes attached (Propranolol group, n=18) or unattached (Propranolol No-Shock Expectation group, n=19). We additionally tested a placebo-control group with the shock-electrodes attached (Placebo group, n=18). Reconsolidation was not triggered when nothing could be learned during the reminder trial, as noradrenergic blockade did not affect expression of the fear memory 24h later in the Propranolol No-Shock Expectation group. Only when the outcome of the retrieval cue was not fully predictable, propranolol, contrary to placebo, reduced the startle fear response and prevented the return of fear (reinstatement) the following day. In line with previous studies, skin conductance response and shock expectancies were not affected by propranolol. Remarkably, a double dissociation emerged between the emotional (startle response) and more cognitive expression (expectancies, SCR) of the fear memory. Our findings have important implications for reconsolidation blockade as treatment strategy for emotional disorders. First, fear reducing procedures that target the emotional component of fear memory do not necessarily affect the cognitive component and vice versa. Second, mere retrieval of the fear memory is not sufficient to induce its labilization and reconsolidation. Copyright © 2012 Elsevier Inc. All rights reserved.

A NOVEL SCORING SYSTEM: PREDICTING SEPTIC SHOCK AT DIAGNOSIS EASILY IN ACUTE COMPLICATED PYELONEPHRITIS PATIENTS.

PubMed

Kubota, Masashi; Kanno, Toru; Nishiyama, Ryuichi; Okada, Takashi; Higashi, Yoshihito; Yamada, Hitoshi

2016-01-01

(Objectives) Because acute complicated pyelonephritis can easily cause sepsis and concomitant shock status, it is a potentially lethal disease. However, the predictors for the severity of pyelonephritis is not well analyzed. In this study, we aimed at clarifying the clinical characteristic risk factors associated with septic shock in patients with acute complicated pyelonephritis. (Materials and methods) From May 2009 to March 2014, 267 patients with acute complicated pyelonephritis were treated at our institution. We investigated the characteristics of the patients associated with septic shock, and assessed risk factors in these patients. By using these risk factors, we established a novel scoring system to predict septic shock. (Results) 267 patients included 145 patients with ureteral calculi and 75 patients with stent-related pyelonephritis. Septic shock occurred in 35 patients (13%), and the mortality rate was 0.75%. Multivariate analysis revealed that (P): Performance Status ≥3 (p=0.0014), (U): Presence of Ureteral calculi (p=0.043), (S): Sex of female (p=0.023), and (H): the presence of Hydronephrosis (p=0.039) were independent risk factors for septic shock. P.U.S.H. scoring system (range 0-4), which consists of these 4 factors, were positively correlated with the rate of septic shock (score 0: 0%, 1: 5.3%, 2: 3.4%, 3: 25.0%, 4: 42.3%). Importantly, patients with 3-4 P.U.S.H. scores were statistically more likely to become septic shock than those with 0-2 score (p=0.00014). (Conclusions) These results suggest that P.U.S.H. scoring system using 4 clinical factors is useful to predict the status of septic shock in patients with acute complicated pyelonephritis.

Spade: An H Chondrite Impact-melt Breccia that Experienced Post-shock Annealing

NASA Technical Reports Server (NTRS)

Rubin, Alan E.; Jones, Rhian H.

2006-01-01

The low modal abundances of relict chondrules (1.8 Vol%) and of coarse (i.e. >= 2200 micron-size) isolated mafic silicate grains (1.8 Vol%) in Spade relative to mean H6 chondrites (11.4 and 9.8 vol%, respectively) show Spade to be a rock that has experienced a significant degree of melting. Various petrographic features (e.g., chromite-plagioclase assemblages, chromite veinlets, silicate darkening) indicate that melting was caused by shock. Plagioclase was melted during the shock event and flowed so that it partially to completely surrounded nearby mafic silicate grains. During crystallization, plagioclase developed igneous zoning. Low-Ca pyroxene that crystallized from the melt (or equilibrated with the melt at high temperatures) acquired relatively high amounts of CaO. Metallic Fe-Ni cooled rapidly below the Fe-Ni solws and transformed into martensite. Subsequent reheating of the rock caused transformation of martensite into abundant duplex plessite. Ambiguities exist in the shock stage assignment of Spade. The extensive silicate darkening, the occurrence of chromite-plagioclase assemblages, and the impact-melted characteristics of Spade are consistent with shock stage S6. Low shock (stage S2) is indicated by the undulose extinction and lack of planar fractures in olivine. This suggests that Spade reached a maximum prior shock level equivalent to stage S6 and then experienced post-shock annealing (probably to stage Sl). These events were followed by a less intense impact that produced the undulose extinction in the olivine, characteristic of shock stage S2. Annealing could have occurred if Spade were emplaced near impact melts beneath the crater floor or deposited in close proximity to hot debris within an ejecta blanket. Spade firmly establishes the case for post-shock annealing. This may have been a common process on ordinary chondrites (OC) asteroids.

Supersonic shock wave/vortex interaction

NASA Technical Reports Server (NTRS)

Settles, G. S.; Cattafesta, L.

1993-01-01

Although shock wave/vortex interaction is a basic and important fluid dynamics problem, very little research has been conducted on this topic. Therefore, a detailed experimental study of the interaction between a supersonic streamwise turbulent vortex and a shock wave was carried out at the Penn State Gas Dynamics Laboratory. A vortex is produced by replaceable swirl vanes located upstream of the throat of various converging-diverging nozzles. The supersonic vortex is then injected into either a coflowing supersonic stream or ambient air. The structure of the isolated vortex is investigated in a supersonic wind tunnel using miniature, fast-response, five-hole and total temperature probes and in a free jet using laser Doppler velocimetry. The cases tested have unit Reynolds numbers in excess of 25 million per meter, axial Mach numbers ranging from 2.5 to 4.0, and peak tangential Mach numbers from 0 (i.e., a pure jet) to about 0.7. The results show that the typical supersonic wake-like vortex consists of a non-isentropic, rotational core, where the reduced circulation distribution is self similar, and an outer isentropic, irrotational region. The vortex core is also a region of significant turbulent fluctuations. Radial profiles of turbulent kinetic energy and axial-tangential Reynolds stress are presented. The interactions between the vortex and both oblique and normal shock waves are investigated using nonintrusive optical diagnostics (i.e. schlieren, planar laser scattering, and laser Doppler velocimetry). Of the various types, two Mach 2.5 overexpanded-nozzle Mach disc interactions are examined in detail. Below a certain vortex strength, a 'weak' interaction exists in which the normal shock is perturbed locally into an unsteady 'bubble' shock near the vortex axis, but vortex breakdown (i.e., a stagnation point) does not occur. For stronger vortices, a random unsteady 'strong' interaction results that causes vortex breakdown. The vortex core reforms downstream of the rear stagnation point, and the reduced circulation distribution once again becomes self-similar in this region. A-new model of this interaction is proposed. Finally, a curve defining the approximate limits of supersonic vortex breakdown is presented.

Wake Closure Characteristics and Afterbody Heating on a Mars Sample Return Orbiter

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; Cheatwood, McNeil F.; Wilmoth, Richard G.; Alter, Stephen J.

2002-01-01

Aeroheating wind-tunnel tests were conducted on a 0.028 scale model of an orbiter concept considered for a possible Mars sample return mission. The primary experimental objectives were to characterize hypersonic near wake closure and determine if shear layer impingement would occur on the proposed orbiter afterbody at incidence angles necessary for a Martian aerocapture maneuver. Global heat transfer mappings, surface streamline patterns, and shock shapes were obtained in the NASA Langley 20-Inch Mach 6 Air and CF4 Tunnels for post-normal shock Reynolds numbers (based on forebody diameter) ranging from 1,400 to 415,000, angles of attack ranging from -5 to 10 degrees at 0, 3, and 6 degree sideslip, and normal-shock density ratios of 5 and 12. Laminar, transitional, and turbulent shear layer impingement on the cylindrical afterbody was inferred from the measurements and resulted in a localized heating maximum that ranged from 40 to 75 percent of the reference forebody stagnation point heating. Comparison of laminar heating prediction to experimental measurement along the orbiter afterbody highlight grid alignment challenges associated with numerical simulation of three- dimensional separated wake flows. Predicted values of a continuum breakdown parameter revealed significant regions of non-continuum flow downstream of the flow separation at the MSRO shoulder and in the region of the reattachment shock on the afterbody. The presence of these regions suggest that the Navier-Stokes predictions at the laminar wind-tunnel condition may encounter errors in the numerical calculation of the wake shear layer development and impingement due to non-continuum effects.

Experimental Study of the Effect of Water Mist Location On Blast Overpressure Attenuation in A Shock Tube

NASA Astrophysics Data System (ADS)

Mataradze, Edgar; Chikhradze, Nikoloz; Bochorishvili, Nika; Akhvlediani, Irakli; Tatishvili, Dimitri

2017-12-01

Explosion protection technologies are based on the formation of a shock wave mitigation barrier between the protection site and the explosion site. Contemporary protective systems use water mist as an extinguishing barrier. To achieve high effectiveness of the protective system, proper selection of water mist characteristics is important. The main factors defining shock wave attenuation in water mist include droplet size distribution, water concentration in the mist, droplet velocity and geometric properties of mist. This paper examines the process of attenuation of shock waves in mist with droplets ranging from 25 to 400 microns under different conditions of water mist location. Experiments were conducted at the Mining Institute with the use of a shock tube to study the processes of explosion suppression by a water mist barrier. The shock tube consists of a blast chamber, a tube, a system for the dosed supply of water, sensors, data recording equipment, and a process control module. Shock wave overpressure reduction coefficient was studied in the shock tube under two different locations of water mist: a) when water mist is created in direct contact with blast chamber and b) the blast chamber and the mist are separated by air space. It is established that in conditions when the air space distance between the blast chamber and the mist is 1 meter, overpressure reduction coefficient is 1.5-1.6 times higher than in conditions when water mist is created in direct contact with blast chamber.

Fourth-power law structure of the shock wave fronts in metals and ceramics

NASA Astrophysics Data System (ADS)

Bayandin, Yuriy; Naimark, Oleg; Saveleva, Natalia

2017-06-01

The plate impact experiments were performed for solids during last fifty years. It was established that the dependence between the strain rate and the shock wave amplitude for metals and ceramics expressed by a fourth-power law. Present study is focused on the theoretical investigation and numerical simulation of plane shock wave propagation in metals and ceramics. Statistically based constitutive model of solid with defects (microcracks and microshears) was developed to provide the relation between damage induced mechanisms of structural relaxation, thermally activated plastic flow and material reactions for extreme loading conditions. Original approach based on the wide range constitutive equations was proposed for the numerical simulation of multiscale damage-failure transition mechanisms and plane shock wave propagation in solids with defects in the range of strain rate 103 -108s-1 . It was shown that mechanisms of plastic relaxation and damage-failure transitions are linked to the multiscale kinetics of defects leading to the self-similar nature of shock wave fronts in metals and ceramics. The work was supported by the Russian Science Foundation (Project No. 14-19-01173).

Analytical method for promoting process capability of shock absorption steel.

PubMed

Sung, Wen-Pei; Shih, Ming-Hsiang; Chen, Kuen-Suan

2003-01-01

Mechanical properties and low cycle fatigue are two factors that must be considered in developing new type steel for shock absorption. Process capability and process control are significant factors in achieving the purpose of research and development programs. Often-used evaluation methods failed to measure process yield and process centering; so this paper uses Taguchi loss function as basis to establish an evaluation method and the steps for assessing the quality of mechanical properties and process control of an iron and steel manufacturer. The establishment of this method can serve the research and development and manufacturing industry and lay a foundation in enhancing its process control ability to select better manufacturing processes that are more reliable than decision making by using the other commonly used methods.

Influence of Tanshinone IIa on heat shock protein 70, Bcl-2 and Bax expression in rats with spinal ischemia/reperfusion injury☆

PubMed Central

Zhang, Li; Gan, Weidong; An, Guoyao

2012-01-01

Tanshinone IIa is an effective monomer component of Danshen, which is a traditional Chinese medicine for activating blood circulation to dissipate blood stasis. Tanshinone IIa can effectively improve brain tissue ischemia/hypoxia injury. The present study established a rat model of spinal cord ischemia/reperfusion injury and intraperitoneally injected Tanshinone IIa, 0.5 hour prior to model establishment. Results showed that Tanshinone IIa promoted heat shock protein 70 and Bcl-2 protein expression, but inhibited Bax protein expression in the injured spinal cord after ischemia/reperfusion injury. Furthermore, Nissl staining indicated a reduction in nerve cell apoptosis and fewer pathological lesions in the presence of Tanshinone IIa, compared with positive control Danshen injection. PMID:25317140

Cardiac output and systemic vascular resistance: Clinical assessment compared with a noninvasive objective measurement in children with shock.

PubMed

Razavi, Asma; Newth, Christopher J L; Khemani, Robinder G; Beltramo, Fernando; Ross, Patrick A

2017-06-01

To evaluate physician assessment of cardiac output and systemic vascular resistance in patients with shock compared with an ultrasonic cardiac output monitor (USCOM). To explore potential changes in therapy decisions if USCOM data were available using physician intervention answers. Double-blinded, prospective, observational study in a tertiary hospital pediatric intensive care unit. Forty children (<18years) admitted with shock, requiring ongoing volume resuscitation or inotropic support. Two to 3 physicians clinically assessed cardiac output and systemic vascular resistance, categorizing them as high, normal, or low. An investigator simultaneously measured cardiac index (CI) and systemic vascular resistance index (SVRI) with USCOM categorized as high, normal, or low. Overall agreement between physician and USCOM for CI (48.5% [κ = 0.18]) and SVRI (45.9% [κ = 0.16]) was poor. Interobserver agreement was also poor for CI (58.7% [κ = 0.33]) and SVRI (52.3% [κ = 0.28]). Comparing theoretical physician interventions to "acceptable" or "unacceptable" clinical interventions, based on USCOM measurement, 56 (21%) physician interventions were found to be "unacceptable." There is poor agreement between physician-assessed CI and SVRI and USCOM, with significant interobserver variability among physicians. Objective measurement of CI and SVRI may reduce variability and improve diagnostic accuracy. Copyright © 2016 Elsevier Inc. All rights reserved.

On the Origin of a Maximum Peak Pressure on the Target Outside of the Stagnation Point upon Normal Impact of a Blunt Projectile and with Underwater Explosion

NASA Astrophysics Data System (ADS)

Gonor, Alexander; Hooton, Irene

2006-07-01

Impact of a rigid projectile (impactor), against a metal target and a condensed explosive surface considered as the important process accompanying the normal entry of a rigid projectile into a target, was overlooked in the preceding studies. Within the framework of accurate shock wave theory, the flow-field, behind the shock wave attached to the perimeter of the adjoined surface, was defined. An important result is the peak pressure rises at points along the target surface away from the stagnation point. The maximum values of the peak pressure are 2.2 to 3.2 times higher for the metallic and soft targets (nitromethane, PBX 9502), than peak pressure values at the stagnation point. This effect changes the commonly held notion that the maximum peak pressure is reached at the projectile stagnation point. In the present study the interaction of a spherical decaying blast wave, caused by an underwater explosion, with a piece-wise plane target, having corner configurations, is investigated. The numerical calculation results in the determination of the vulnerable spots on the target, where the maximum peak overpressure surpassed that for the head-on shock wave reflection by a factor of 4.

Control of a Normal Shock Boundary Layer Interaction with Ramped Vanes of Various Sizes

NASA Astrophysics Data System (ADS)

Lee, Sang; Loth, Eric

2017-11-01

A novel vortex generator design positioned upstream of a normal shock and a subsequent diffuser was investigated using large eddy simulations. In particular, ``ramped-vane'' flow control devices with three difference heights relative to the incoming boundary layer thickness (0.34 δ 0.52 δ and 0.75 δ were placed in a supersonic boundary layer with a freestream Mach number of 1.3 and a Reynolds number of 2,400 based on momentum thickness. These devices are similar to subsonic vanes but are designed to be more mechanically robust while having low wave drag. The devices generated strong streamwise vortices that entrained high momentum fluid to the near-wall region and increased turbulent mixing. The devices also decreased shock-induced flow separation, which resulted in a higher downstream skin friction in the diffuser. In general, the largest ramped-vane (0.75 δ) produced the largest reductions in flow separation, shape factor and overall unsteadiness. However, the medium-sized ramped vane (0.52 δ) was able to also reduce both the separation area and the diffuser displacement thickness. The smallest device (0.34 δ) had a weak impact of the flow in the diffuser, though a 10% reduction in the shape factor was achieved.

A Review of Acquired Thermotolerance, Heat Shock Proteins, and Molecular Chaperones in Archaea: Heat Shock in Archaea

DOE R&D Accomplishments Database

Trent, J. D.

1996-02-09

Acquired thermotolerance, the associated synthesis of heat-shock proteins (HSPs) under stress conditions, and the role of HSPs as molecular chaperones under normal growth conditions have been studied extensively in eukaryotes and bacteria, whereas research in these areas in archaea is only beginning. All organisms have evolved a variety of strategies for coping with high-temperature stress, and among these strategies is the increased synthesis of HSPs. The facts that both high temperatures and chemical stresses induce the HSPs and that some of the HSPs recognize and bind to unfolded proteins in vitro have led to the theory that the function of HSPs is to prevent protein aggregation in vivo. The facts that some HSPs are abundant under normal growth conditions and that they assist in protein folding in vitro have led to the theory that they assist protein folding in vivo; in this role, they are referred to as molecular chaperones. The limited research on acquired thermotolerance, HSPs, and molecular chaperones in archaea, particularly the hyperthermophilic archaea, suggests that these extremophiles provide a new perspective in these areas of research, both because they are members of a separate phylogenetic domain and because they have evolved to live under extreme conditions.

Stable Reference Gene Selection for RT-qPCR Analysis in Nonviruliferous and Viruliferous Frankliniella occidentalis

PubMed Central

Pan, Huipeng; Ma, Yabin; Zhang, Deyong; Liu, Yong; Zhang, Zhanhong; Zheng, Changying; Chu, Dong

2015-01-01

Reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) is a reliable technique for measuring and evaluating gene expression during variable biological processes. To facilitate gene expression studies, normalization of genes of interest relative to stable reference genes is crucial. The western flower thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), the main vector of tomato spotted wilt virus (TSWV), is a destructive invasive species. In this study, the expression profiles of 11 candidate reference genes from nonviruliferous and viruliferous F. occidentalis were investigated. Five distinct algorithms, geNorm, NormFinder, BestKeeper, the ΔC t method, and RefFinder, were used to determine the performance of these genes. geNorm, NormFinder, BestKeeper, and RefFinder identified heat shock protein 70 (HSP70), heat shock protein 60 (HSP60), elongation factor 1 α, and ribosomal protein l32 (RPL32) as the most stable reference genes, and the ΔC t method identified HSP60, HSP70, RPL32, and heat shock protein 90 as the most stable reference genes. Additionally, two reference genes were sufficient for reliable normalization in nonviruliferous and viruliferous F. occidentalis. This work provides a foundation for investigating the molecular mechanisms of TSWV and F. occidentalis interactions. PMID:26244556

Effect of Reynolds number variation on aerodynamics of a hydrogen-fueled transport concept at Mach 6

NASA Technical Reports Server (NTRS)

Penland, Jim A.; Marcum, Don C., Jr.

1987-01-01

Two separate tests have been made on the same blended wing-body hydrogen-fueled transport model at a Mach number of about 6 and a range of Reynolds number (based on theoretical body length) of 1.577 to 55.36 X 10 to the 6th power. The results of these tests, made in a conventional hypersonic blowdown tunnel and a hypersonic shock tunnel, are presented through a range of angle of attack from -1 to 8 deg, with an extended study at a constant angle of attack of 3 deg. The model boundary layer flow appeared to be predominately turbulent except for the low Reynolds number shock tunnel tests. Model wall temperatures varied considerably; the blowdown tunnel varied from about 255 F to 340 F, whereas the shock tunnel had a constant 70 F model wall temperature. The experimental normal-force coefficients were essentially independent of Reynolds number. A current theoretical computer program was used to study the effect of Reynolds number. Theoretical predictions of normal-force coefficients were good, particularly at anticipated cruise angles of attack, that is 2 to 5 deg. Axial-force coefficients were generally underestimated for the turbulent skin friction conditions, and pitching-moment coefficients could not be predicted reliably.

Low Endogenous Fibroblast Growth Factor 2 Levels Are Associated With Heightened Conditioned Fear Expression in Rats and Humans.

PubMed

Graham, Bronwyn M; Zagic, Dino; Richardson, Rick

2017-10-15

Hippocampal concentrations of the neurotrophic factor fibroblast growth factor 2 (FGF2) are negatively associated with the expression of fear following conditioning in rats. Heightened conditioned fear expression may be a prospective risk factor for the development of human anxiety and trauma disorders. However, the relationship between conditioned fear expression and FGF2 is yet to be established in humans. Using a cross-species approach, we first investigated the relationship between serum concentrations of FGF2 and individual differences in conditioned fear expression in rats (n = 19). We then subjected 88 human participants, who were recruited from university and community advertisements, to a differential fear conditioning procedure and assessed the relationship between salivary concentrations of FGF2 and fear expression to a conditioned stimulus (CS) (a stimulus paired with a shock) and a CS that was never paired with shock. Rats with low serum levels of FGF2 exhibited significantly more freezing than rats with high serum levels of FGF2. Similarly, relative to those with high salivary FGF2, human participants with low salivary FGF2 exhibited significantly heightened skin conductance responses to the CS without shock during fear conditioning and to both the CS with shock and CS without shock during fear recall. These studies establish that peripheral markers of FGF2 concentrations are negatively associated with fear expression in both rats and humans. To the extent that conditioned fear expression predicts anxiety and trauma disorder vulnerability, FGF2 may be a clinically useful biomarker in the prediction and eventual prevention of these disorders. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Numerical and Analytical Study of Nonlinear Effects of Transonic Flow Past a Wing Airfoil in Oscillation of its Surface Element

NASA Astrophysics Data System (ADS)

Aul'chenko, S. M.; Zamuraev, V. P.; Kalinina, A. P.

2014-05-01

The present work is devoted to a criterial analysis and mathematical modeling of the influence of forced oscillations of surface elements of a wing airfoil on the shock-wave structure of transonic flow past it. Parameters that govern the regimes of interaction of the oscillatory motion of airfoil sections with the breakdown compression shock have been established. The qualitative and quantitative influence of these parameters on the wave resistance of the airfoil has been investigated.

Establishment and characterization of Xenopus oviduct cells in primary culture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marsh, J.; Tata, J.R.

1987-11-01

Based on previously established procedure of Xenopus hepatocytes, the authors describe tubular oviduct cells in primary culture which continue to secrete substantial quantities of egg jelly for several days, as can be visualized microscopically. Freshly isolated cells exhibited a culture shock response, from which they recovered by the third day in culture. This recovery was characterized by (a) the diminished synthesis of heat shock proteins hsp 70 and hsp 85, (b) the cessation of the drop in number of estrogen receptor, and (c) the enhanced rate of synthesis of cellular and secreted proteins. The oviduct estrogen receptor had the samemore » characteristics as those in other estrogen target tissues and was present in the same amount as in adult female Xenopus hepatocytes. The successful establishment and characterization of primary cultures of both liver and oviduct cells now fulfill the conditions required for investigating the basis for tissue specificity of regulation by estrogen of Xenopus egg protein gene expression in primary cell culture.« less

The Statistical Studies of 0.5-100 keV Electrons Near The ICME-drivens At 1 AU

NASA Astrophysics Data System (ADS)

Yang, L.; Wang, W.; Wang, L.; Li, G.; Wimmer-Schweingruber, R. F.; He, J.; Tu, C. Y.; Bale, S. D.

2017-12-01

We present a statistical survey of the 0.5 - 100 keV electrons near the ICME-driven shocks at 1 AU, using the WIND/3DP electron measurements from 1995 to 2014. We select 74 good ICME-driven shocks, and use the "Rankine-Hugoniot" shock fitting technique to obtain the shock normal, θBn, magnetic compression ratio rB, and magnetosonic Mach number Ms. After averaging the electron data in the 10-minute interval immediately after the shock to obtain the sheath electron fluxes, Jsheath, and in the 2-hour quiet-time interval before the shock to obtain the pre-event electron fluxes, Jpre-event, we calculate the flux ratio, α, of Jsheath over Jpre-event. We find that, in the 59 quasi-perpendicular shocks, both Jsheath and Jpre-event are positively correlated with Ms and α is positively correlated with rB. In the 15 quasi-parallel cases, α is positively correlated with Ms, while neither Jsheath nor Jpre-event has any correlation with the shock parameters. Furthermore, we find that both the pre-event and sheath electron fluxes generally fit well to a double power-law spectrum, . At 0.5 - 2 keV, the fitted spectral index β1 ranges from 2.1 to 5.9, and it becomes larger in the sheah than in the pre-event in nearly a half of the 74 cases and remains the same in the other half of the cases. At 2 - 100 keV, the fitted index β2 ranges from 1.9 to 3.4, similar to the spectral indexes of solar wind superhalo electrons at quiet times (Wang et al., 2015). And β2 becomes larger in the sheah than in the pre-event in over half of the cases. In addition, neither β1 nor β2 is consistent with the diffusive shock theoretical predication. These results suggest that the shock drift acceleration may play a more important role in electron acceleration than the diffusive shock acceleration near 1 AU, and the interplanetary shock acceleration can contribute to the production of solar wind superhalo electrons.

The Effects of FUV Radiation on C-Shocks: Implications for Water and Other O-bearing Species

NASA Astrophysics Data System (ADS)

Kaufman, Michael; Melick, Gary; Tolls, Volker

2015-08-01

Protostellar outflows have long been known to drive endothermic reactions that produce high abundances of oxygen-bearing species. Models of shocks in well-shielded gas made the strong prediction that essentially all of the pre-shock oxygen gets driven into water, so that the post-shock water abundances are order 10-4. Herschel observations, however, including those from the key program “Water in Star Forming Regions with Herschel (WISH)” show that for most sources, the shocked gas water abundances of are far lower, 10-7 - 10-5.This pattern of lower-than-predicted water abundance has led us to consider that our C-shock model (Kaufman & Neufeld 1996) is incomplete. In particular, we did not previously take into account that many outflow sources have higher than average far-ultraviolet radiation fields within their outflow cavities. Strong FUV radiation has important effects on the structure of C-shocks: the ionization fraction is larger than in well-shielded gas, decreasing the coupling length between neutrals and ions, and leading to higher temperatures and a lower breakdown speeds; the pre-shock gas composition, including the presence of ice mantles and the dominant charge carriers, is strongly affected; and abundant species such as water are diminished by photodissociation in the cooled down stream gas.In addition to the normal parameters of density, shock velocity, and magnetic field strength, we now include the external FUV field strength and the extinction between the FUV source and the shock. We use the results of a detailed PDR model to compute pre-shock chemical conditions, including the ionization fraction, the increase of which decreases the maximum velocities of C- shocks. FUV also keeps oxygen in the gas phase, making more available for H2O formarion ; however, photodissociation beyond the temperature peak keeps the average H2O abundance down. We present comparisons of our model results with the inferred water abundances and with observations of H2O, CO, O and OH lines from the Herschel archive.

Systemic Analysis of Heat Shock Response Induced by Heat Shock and a Proteasome Inhibitor MG132

PubMed Central

Kim, Hee-Jung; Joo, Hye Joon; Kim, Yung Hee; Ahn, Soyeon; Chang, Jun; Hwang, Kyu-Baek; Lee, Dong-Hee; Lee, Kong-Joo

2011-01-01

The molecular basis of heat shock response (HSR), a cellular defense mechanism against various stresses, is not well understood. In this, the first comprehensive analysis of gene expression changes in response to heat shock and MG132 (a proteasome inhibitor), both of which are known to induce heat shock proteins (Hsps), we compared the responses of normal mouse fibrosarcoma cell line, RIF- 1, and its thermotolerant variant cell line, TR-RIF-1 (TR), to the two stresses. The cellular responses we examined included Hsp expressions, cell viability, total protein synthesis patterns, and accumulation of poly-ubiquitinated proteins. We also compared the mRNA expression profiles and kinetics, in the two cell lines exposed to the two stresses, using microarray analysis. In contrast to RIF-1 cells, TR cells resist heat shock caused changes in cell viability and whole-cell protein synthesis. The patterns of total cellular protein synthesis and accumulation of poly-ubiquitinated proteins in the two cell lines were distinct, depending on the stress and the cell line. Microarray analysis revealed that the gene expression pattern of TR cells was faster and more transient than that of RIF-1 cells, in response to heat shock, while both RIF-1 and TR cells showed similar kinetics of mRNA expression in response to MG132. We also found that 2,208 genes were up-regulated more than 2 fold and could sort them into three groups: 1) genes regulated by both heat shock and MG132, (e.g. chaperones); 2) those regulated only by heat shock (e.g. DNA binding proteins including histones); and 3) those regulated only by MG132 (e.g. innate immunity and defense related molecules). This study shows that heat shock and MG132 share some aspects of HSR signaling pathway, at the same time, inducing distinct stress response signaling pathways, triggered by distinct abnormal proteins. PMID:21738571

Enrollment into a time sensitive clinical study in the critical care setting: results from computerized septic shock sniffer implementation.

PubMed

Herasevich, Vitaly; Pieper, Matthew S; Pulido, Juan; Gajic, Ognjen

2011-01-01

Recruitment of patients into time sensitive clinical trials in intensive care units (ICU) poses a significant challenge. Enrollment is limited by delayed recognition and late notification of research personnel. The objective of the present study was to evaluate the effectiveness of the implementation of electronic screening (septic shock sniffer) regarding enrollment into a time sensitive (24 h after onset) clinical study of echocardiography in severe sepsis and septic shock. We developed and tested a near-real time computerized alert system, the septic shock sniffer, based on established severe sepsis/septic shock diagnostic criteria. A sniffer scanned patients' data in the electronic medical records and notified the research coordinator on call through an institutional paging system of potentially eligible patients. The performance of the septic shock sniffer was assessed. The septic shock sniffer performed well with a positive predictive value of 34%. Electronic screening doubled enrollment, with 68 of 4460 ICU admissions enrolled during the 9 months after implementation versus 37 of 4149 ICU admissions before sniffer implementation (p<0.05). Efficiency was limited by study coordinator availability (not available at nights or weekends). Automated electronic medical records screening improves the efficiency of enrollment and should be a routine tool for the recruitment of patients into time sensitive clinical trials in the ICU setting.

Enrollment into a time sensitive clinical study in the critical care setting: results from computerized septic shock sniffer implementation

PubMed Central

Pieper, Matthew S; Pulido, Juan; Gajic, Ognjen

2011-01-01

Objective Recruitment of patients into time sensitive clinical trials in intensive care units (ICU) poses a significant challenge. Enrollment is limited by delayed recognition and late notification of research personnel. The objective of the present study was to evaluate the effectiveness of the implementation of electronic screening (septic shock sniffer) regarding enrollment into a time sensitive (24 h after onset) clinical study of echocardiography in severe sepsis and septic shock. Design We developed and tested a near-real time computerized alert system, the septic shock sniffer, based on established severe sepsis/septic shock diagnostic criteria. A sniffer scanned patients' data in the electronic medical records and notified the research coordinator on call through an institutional paging system of potentially eligible patients. Measurement The performance of the septic shock sniffer was assessed. Results The septic shock sniffer performed well with a positive predictive value of 34%. Electronic screening doubled enrollment, with 68 of 4460 ICU admissions enrolled during the 9 months after implementation versus 37 of 4149 ICU admissions before sniffer implementation (p<0.05). Efficiency was limited by study coordinator availability (not available at nights or weekends). Conclusions Automated electronic medical records screening improves the efficiency of enrollment and should be a routine tool for the recruitment of patients into time sensitive clinical trials in the ICU setting. PMID:21508415

A Supersonic Tunnel for Laser and Flow-Seeding Techniques

NASA Technical Reports Server (NTRS)

Bruckner, Robert J.; Lepicovsky, Jan

1994-01-01

A supersonic wind tunnel with flow conditions of 3 lbm/s (1.5 kg/s) at a free-stream Mach number of 2.5 was designed and tested to provide an arena for future development work on laser measurement and flow-seeding techniques. The hybrid supersonic nozzle design that was used incorporated the rapid expansion method of propulsive nozzles while it maintained the uniform, disturbance-free flow required in supersonic wind tunnels. A viscous analysis was performed on the tunnel to determine the boundary layer growth characteristics along the flowpath. Appropriate corrections were then made to the contour of the nozzle. Axial pressure distributions were measured and Mach number distributions were calculated based on three independent data reduction methods. A complete uncertainty analysis was performed on the precision error of each method. Complex shock-wave patterns were generated in the flow field by wedges mounted near the roof and floor of the tunnel. The most stable shock structure was determined experimentally by the use of a focusing schlieren system and a novel, laser based dynamic shock position sensor. Three potential measurement regions for future laser and flow-seeding studies were created in the shock structure: deceleration through an oblique shock wave of 50 degrees, strong deceleration through a normal shock wave, and acceleration through a supersonic expansion fan containing 25 degrees of flow turning.

A fast estimation of shock wave pressure based on trend identification

NASA Astrophysics Data System (ADS)

Yao, Zhenjian; Wang, Zhongyu; Wang, Chenchen; Lv, Jing

2018-04-01

In this paper, a fast method based on trend identification is proposed to accurately estimate the shock wave pressure in a dynamic measurement. Firstly, the collected output signal of the pressure sensor is reconstructed by discrete cosine transform (DCT) to reduce the computational complexity for the subsequent steps. Secondly, the empirical mode decomposition (EMD) is applied to decompose the reconstructed signal into several components with different frequency-bands, and the last few low-frequency components are chosen to recover the trend of the reconstructed signal. In the meantime, the optimal component number is determined based on the correlation coefficient and the normalized Euclidean distance between the trend and the reconstructed signal. Thirdly, with the areas under the gradient curve of the trend signal, the stable interval that produces the minimum can be easily identified. As a result, the stable value of the output signal is achieved in this interval. Finally, the shock wave pressure can be estimated according to the stable value of the output signal and the sensitivity of the sensor in the dynamic measurement. A series of shock wave pressure measurements are carried out with a shock tube system to validate the performance of this method. The experimental results show that the proposed method works well in shock wave pressure estimation. Furthermore, comparative experiments also demonstrate the superiority of the proposed method over the existing approaches in both estimation accuracy and computational efficiency.

Temperature sensing in shock-heated evaporating aerosol using wavelength-modulation absorption spectroscopy of CO2 near 2.7 µm

NASA Astrophysics Data System (ADS)

Ren, Wei; Jeffries, Jay B.; Hanson, Ronald K.

2010-10-01

A tunable diode laser sensor with a detection bandwidth of 40 kHz is developed for measuring the time-varying gas temperature of CO2 during the evaporation of shock-heated hydrocarbon fuel aerosol. Normalized wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f/1f) is used to probe R(28) and P(70) transitions in the ν1 + ν3 combination band of CO2 near 2.7 µm. The fixed-center-wavelength WMS sensor was first validated in a shock tube with non-reactive CO2/Ar gas mixtures, yielding an accuracy of better than 1.5% over the entire range of 650-1500 K. The sensor was then evaluated in a well-controlled aerosol flow cell, demonstrating the potential for precise gas temperature measurement even when aerosol scattering attenuates more than 99% of the incident light. Applications of this sensor for accurate temperature measurement of evaporating n-dodecane aerosol were then performed in an aerosol shock tube. The time-resolved temperature variation due to the evaporation of fuel droplets was accurately captured without using an off-resonant laser to account for the extinction from droplet scattering. Measured temperatures confirmed the accuracy of the gasdynamic model used to calculate the pre- and post-evaporation shock conditions, as needed in shock tube studies on combustion chemistry.

Computational and experimental investigation of two-dimensional scramjet inlets and hypersonic flow over a sharp flat plate

NASA Astrophysics Data System (ADS)

Messitt, Donald G.

1999-11-01

The WIND code was employed to compute the hypersonic flow in the shock wave boundary layer merged region near the leading edge of a sharp flat plate. Solutions were obtained at Mach numbers from 9.86 to 15.0 and free stream Reynolds numbers of 3,467 to 346,700 in-1 (1.365 · 105 to 1.365 · 107 m-1) for perfect gas conditions. The numerical results indicated a merged shock wave and viscous layer near the leading edge. The merged region grew in size with increasing free stream Mach number, proportional to Minfinity 2/Reinfinity. Profiles of the static pressure in the merged region indicated a strong normal pressure gradient (∂p/∂y). The normal pressure gradient has been neglected in previous analyses which used the boundary layer equations. The shock wave near the leading edge was thick, as has been experimentally observed. Computed shock wave locations and surface pressures agreed well within experimental error for values of the rarefaction parameter, chi/M infinity2 < 0.3. A preliminary analysis using kinetic theory indicated that rarefied flow effects became important above this value. In particular, the WIND solution agreed well in the transition region between the merged flow, which was predicted well by the theory of Li and Nagamatsu, and the downstream region where the strong interaction theory applied. Additional computations with the NPARC code, WIND's predecessor, demonstrated the ability of the code to compute hypersonic inlet flows at free stream Mach numbers up to 20. Good qualitative agreement with measured pressure data indicated that the code captured the important physical features of the shock wave - boundary layer interactions. The computed surface and pitot pressures fell within the combined experimental and numerical error bounds for most points. The calculations demonstrated the need for extremely fine grids when computing hypersonic interaction flows.

Low-energy Shock Wave Therapy-A Novel Treatment Option for Erectile Dysfunction in Men With Cardiovascular Disease.

PubMed

Kałka, Dariusz; Gebala, Jana; Smoliński, Ryszard; Rusiecki, Lesław; Pilecki, Witold; Zdrojowy, Romuald

2017-11-01

Patients with cardiovascular disease (CVD) are prone to developing erectile dysfunction (ED) owing to the common risk factors and pathogenesis underlying ED and CVD. As a result, ED affects nearly 80% of male patients with CVD. The efficacy of phosphodiesterase type 5 inhibitors, vacuum erection devices, or intracavernosal injection of vasodilating agents is well established in the treatment of ED; however, their use is limited. Low-energy shock wave therapy is a novel modality that may become a causative treatment for ED. This review aims to assess the efficacy and safety of low-energy shock wave therapy in the treatment of ED in men with CVD. Copyright © 2017 Elsevier Inc. All rights reserved.

A normal shock-wave turbulent boundary-layer interaction at transonic speeds

NASA Technical Reports Server (NTRS)

Mateer, G. G.; Brosh, A.; Viegas, J. R.

1976-01-01

Experimental results, including surveys of the mean and fluctuating flow, and measurements of surface pressure, skin friction, and separation length, are compared with solutions to the Navier-Stokes equations utilizing various algebraic eddy viscosity models to describe the Reynolds shear stresses. The experimental data, obtained at a free-stream Mach number of 1.5 and Reynolds numbers between 10 million and 80 million, show that a separated zone forms near the foot of the shock and that its length is proportional to the initial boundary-layer thickness; that a supersonic region forms downstream of the shock; and that the shear stress increases significantly through the interaction and subsequently decays downstream. The computations adequately represent the qualitative features of the flow field throughout the interaction but quantitatively underpredict the extent of separation and the downstream level of skin friction.

Tako-Tsubo cardiomyopathy presenting with cardiogenic shock successfully treated with milrinone: a case report.

PubMed

Doyen, Denis; Dellamonica, Jean; Moceri, Pamela; Moschietto, Sébastien; Hyvernat, Hervé; Ferrari, Emile; Bernardin, Gilles

2014-01-01

We report the case of a middle age patient presenting with Tako-Tsubo cardiomyopathy (TTC) complicated by cardiogenic shock that was successfully handled with milrinone. A 64-year old man presented with cardiogenic shock after benzodiazepine and alcohol intoxication. A slight elevation of troponin and typical left ventricular ballooning without coronary lesions suggested TTC. Within a few hours milrinone infusion normalized the cardiac index. TTC is responsible for severe transient left ventricular dysfunction occurring after physical or psychological stress. The major pathophysiological mechanism involved is disproportionate catecholamine secretion, which may stun the myocardium. We considered if treatment of this unique physiopathology with catecholamines could be dangerous in these patients and if alternative inotropes such as milrinone should be preferred. Copyright © 2014 The Authors. Published by Mosby, Inc. All rights reserved.

Quasi-monoenergetic protons accelerated by laser radiation pressure and shocks in thin gaseous targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

He Minqing; Shao Xi; Liu Chuansheng

Recent experiments and simulations have demonstrated effective CO{sub 2} laser acceleration of quasi-monoenergetic protons from thick gaseous hydrogen target (of thickness tens of laser wavelengths) via hole boring and shock accelerations. We present here an alternative novel acceleration scheme by combining laser radiation pressure acceleration with shock acceleration of protons in a thin gaseous target of thickness several laser wavelengths. The laser pushes the thin gaseous plasma forward while compressing it with protons trapped in it. We demonstrated the combined acceleration with two-dimensional particle-in-cell simulation and obtained quasi-monoenergetic protons {approx}44 MeV in a gas target of thickness twice of themore » laser wavelength irradiated by circularly polarized CO{sub 2} laser with normalized laser amplitude a{sub 0}=10.« less

[The effect of the membrane attack complex C5b-9 on liver cells during traumatic hemorrhagic shock in rat].

PubMed

Zhao, Zhi-ling; Cao, Shu-hua; Wang, Yong-qiang

2011-03-01

To observe whether the membrane attack complex C5b-9 would accumulate in the rats' liver after receiving the assault of traumatic hemorrhagic shock, and whether the membrane attack complex deals an impact on liver apoptosis. Fifty male healthy Wistar rats were randomly divided into five groups: normal group, 1, 3, 6, 24 hour model groups. The model of traumatic hemorrhagic shock was reproduced by withdrawal of blood from carotid artery after a bone fracture till the blood pressure lowered to 40 mm Hg (1 mm Hg=0.133 kPa). Plasma membrane attack complex C5b-9 concentration was assayed using enzyme linked immunoadsorbent assay. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in blood was determined by Rate method. Immunohistochemistry was used to detect C5b-9 deposition in the liver. Apoptosis of liver cells was then detected by the terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay. The pathological changes in paraffin sections stained with hematoxylin eosin (HE) were observed under light microscope. A small amount of C5b 9 in plasma was found in normal group, and the values (ng/L) of 1, 3, 6 hour models were significantly higher than those of the normal group (272.91 ± 9.56, 192.01 ± 9.04, 156.78 ± 8.37 vs. 25.98 ± 5.87, all <0.05 ). ALT (U/L) in 3 hour model group and AST (U/L) in 1 hour model group were increased significantly (92.90 ± 8.83, 264.83 ± 31.4), peaked at 24 hours (184.30 ± 12.98, 647.36 ± 60.02), and there was significant difference compared with normal group (38.75 ± 5.40, 66.69 ± 19.95, all P <0.05). In the normal group and the 1 hour and 6 hour model groups, no C5b 9 was found in liver, but in the 3 hour model group a large number of liver parenchymal cells in the portal area were found to contain C5b 9 22.60 ± 1.06), however the number decreased significantly in the 24 hour model (2.20 ± 0.60, P<0.05). In normal group there was no apoptotic cell, and in 1, 6, 24 hour model groups there were scattered apoptotic cells (1.20 ± 0.25, 5.60 ± 0.37, 1.60 ± 0.26). In the 3 hour model group apoptosis of hepatic cells around the central vein was increased to the peak (20.60 ± 0.47), and there was significant difference compared with other groups (all P <0.05) . In the model groups the liver cells became edematous, and the integrity of the membrane was lost, and some cells were even lysed.The pathological damage is most serious in 24 hour model group. The membrane attack complex C5b-9 insulted the rats' liver after a traumatic hemorrhagic shock, and apoptosis of hepatic cells and the content of C5b-9 peaked in 3 hour model , though they do not occur in the same site. A low level of C5b-9 in blood 3 hours after shock predict a poor prognosis.

Glioprotective effects of Ashwagandha leaf extract against lead induced toxicity.

PubMed

Kumar, Praveen; Singh, Raghavendra; Nazmi, Arshed; Lakhanpal, Dinesh; Kataria, Hardeep; Kaur, Gurcharan

2014-01-01

Withania somnifera (Ashwagandha), also known as Indian Ginseng, is a well-known Indian medicinal plant due to its antioxidative, antistress, antigenotoxic, and immunomodulatory properties. The present study was designed to assess and establish the cytoprotective potential of Ashwagandha leaf aqueous extract against lead induced toxicity. Pretreatment of C6 cells with 0.1% Ashwagandha extract showed cytoprotection against 25  μM to 400 μM concentration of lead nitrate. Further pretreatment with Ashwagandha extract to lead nitrate exposed cells (200  μM) resulted in normalization of glial fibrillary acidic protein (GFAP) expression as well as heat shock protein (HSP70), mortalin, and neural cell adhesion molecule (NCAM) expression. Further, the cytoprotective efficacy of Ashwagandha extract was studied in vivo. Administration of Ashwagandha extract provided significant protection to lead induced altered antioxidant defense that may significantly compromise normal cellular function. Ashwagandha also provided a significant protection to lipid peroxidation (LPx) levels, catalase, and superoxide dismutase (SOD) but not reduced glutathione (GSH) contents in brain tissue as well as peripheral organs, liver and kidney, suggesting its ability to act as a free radical scavenger protecting cells against toxic insult. These results, thus, suggest that Ashwagandha water extract may have the potential therapeutic implication against lead poisoning.

Semi-actuator disk theory for compressor choke flutter

NASA Technical Reports Server (NTRS)

Micklow, J.; Jeffers, J.

1981-01-01

A mathematical anaysis predict the unsteady aerodynamic utilizing semi actuator theory environment for a cascade of airfoils harmonically oscillating in choked flow was developed. A normal shock is located in the blade passage, its position depending on the time dependent geometry, and pressure perturbations of the system. In addition to shock dynamics, the model includes the effect of compressibility, interblade phase lag, and an unsteady flow field upstream and downstream of the cascade. Calculated unsteady aerodynamics were compared with isolated airfoil wind tunnel data, and choke flutter onset boundaries were compared with data from testing of an F100 high pressure compressor stage.

Numerical modeling of the destruction of steel plates with a gradient substrate

NASA Astrophysics Data System (ADS)

Orlov, M. Yu.; Glazyrin, V. P.; Orlov, Yu. N.

2017-10-01

The paper presents the results of numerical simulation of the shock loading process of steel barriers with a gradient substrate. In an elastic plastic axisymmetric statement, a shock is simulated along the normal in the range of initial velocities up to 300 m / s. A range of initial velocities was revealed, in which the presence of a substrate "saved" the obstacle from spallation. New tasks were announced to deepen scientific knowledge about the behavior of unidirectional gradient barriers at impact. The results of calculations are obtained in the form of graphs, calculated configurations of the "impact - barrier" and tables.

Gas dynamics. Second edition

DOE Office of Scientific and Technical Information (OSTI.GOV)

John, J.E.A.

1984-01-01

The book treats the basic fundamentals of compressible flow and gas dynamics using a wide breadth of topical coverage. It emphasizes the clear, logical development of basic theory and applies theory to real engineering systems. New in this edition is a complete changeover from English units to SI units. New charts for computing flows containing conical shock waves and expanded tables for isentropic flow and normal shocks are featured. The text emphasizes one dimensional and internal flow, and contains: improved illustrations; many new homework problems; examples and problems involving current applications; and new Mollier diagrams for computing real gas effects.

Hsp27 as a therapeutic target in cancers.

PubMed

Acunzo, Julie; Andrieu, Claudia; Baylot, Virginie; So, Alan; Rocchi, Palma

2014-04-01

Heat shock protein 27 (Hsp27), induced by heat shock, environmental and pathophysiological stressors, is a multidimensional protein that acts as a protein chaperone and an antioxidant. This protein plays a major role in the inhibition of apoptosis and actin cytoskeletal remodeling. This stress-activated protein is up-regulated in many cancers and is associated with poor prognosis as well as treatment resistance by protecting cells from therapeutic agent that normally induces apoptosis. This review highlights the most recent findings and role of Hsp27 in cancer and the different strategies to target and inhibit Hsp27 for clinical purposes.

Normal Impingement of a Supersonic Jet on a Plane - A Basic Study of Shock-Interference Heating

DTIC Science & Technology

1975-12-01

George Xaler, Pail Zone Dr. H. Lew 28i0 Mr. J. W. Paust A . Mkrtallucci W. Daskin J. D. Cresaswell J. pvttu" J. Cor%.nto C. l!arri, F. GCOrge1. 4...NSWC/WOL/TR 75195 low zE ~ 1 WHITE OAK LABORATORY SNORMAL IMPINGEMENT OF A SUPERSONIC JET ON A PLANE - A BASIC STUDY OF SHOCK-INTERFERENCE HEATING...OF THIS PAGE ("oin DomejaE’ored) __________________ REPORT DOCUMENTATION PAGE READ INSTRUCTIONS4 2. OV ACE.~ CONTRAT O0GRN NUMBER~ a NS. P ER OR M I

Internal Flow and Burning Characteristics of 16-inch Ram Jet Operating in a Free Jet at Mach Numbers of 1.35 and 1.73

NASA Technical Reports Server (NTRS)

Perchonok, Eugene; Farley, John M

1951-01-01

The effects of mass-flow ratio on the additive drag and normal-shock position of a single oblique-shock diffuser are presented. Also evaluated is the variation with operating condition of the velocity distribution at the combustion-chamber inlet. A comparison with connected-pipe data is included. Burner performance with a corrugated gutter-grid flame holder is discussed. It is shown that the total-pressure drop across the combustion chamber can be predicted with reasonable accuracy from the computed flame holder and combustion momentum pressure losses.

Laboratory observations of fault strength in response to changes in normal stress

USGS Publications Warehouse

Kilgore, Brian D.; Lozos, Julian; Beeler, Nicholas M.; Oglesby, David

2012-01-01

Changes in fault normal stress can either inhibit or promote rupture propagation, depending on the fault geometry and on how fault shear strength varies in response to the normal stress change. A better understanding of this dependence will lead to improved earthquake simulation techniques, and ultimately, improved earthquake hazard mitigation efforts. We present the results of new laboratory experiments investigating the effects of step changes in fault normal stress on the fault shear strength during sliding, using bare Westerly granite samples, with roughened sliding surfaces, in a double direct shear apparatus. Previous experimental studies examining the shear strength following a step change in the normal stress produce contradictory results: a set of double direct shear experiments indicates that the shear strength of a fault responds immediately, and then is followed by a prolonged slip-dependent response, while a set of shock loading experiments indicates that there is no immediate component, and the response is purely gradual and slip-dependent. In our new, high-resolution experiments, we observe that the acoustic transmissivity and dilatancy of simulated faults in our tests respond immediately to changes in the normal stress, consistent with the interpretations of previous investigations, and verify an immediate increase in the area of contact between the roughened sliding surfaces as normal stress increases. However, the shear strength of the fault does not immediately increase, indicating that the new area of contact between the rough fault surfaces does not appear preloaded with any shear resistance or strength. Additional slip is required for the fault to achieve a new shear strength appropriate for its new loading conditions, consistent with previous observations made during shock loading.

The effect of detonation wave incidence angle on the acceleration of flyers by explosives heavily laden with inert additives

NASA Astrophysics Data System (ADS)

Loiseau, Jason; Georges, William; Frost, David L.; Higgins, Andrew J.

2017-01-01

The incidence angle of a detonation wave in a conventional high explosive influences the acceleration and terminal velocity of a metal flyer by increasing the magnitude of the material velocity imparted by the transmitted shock wave as the detonation is tilted towards normal loading. For non-ideal explosives heavily loaded with inert additives, the detonation velocity is typically subsonic relative to the flyer sound speed, leading to shockless accelerations when the detonation is grazing. Further, in a grazing detonation the particles are initially accelerated in the direction of the detonation and only gain velocity normal to the initial orientation of the flyer at later times due to aerodynamic drag as the detonation products expand. If the detonation wave in a non-ideal explosive instead strikes the flyer at normal incidence, a shock is transmitted into the flyer and the first interaction between the particle additives and the flyer occurs due to the imparted material velocity from the passage of the detonation wave. Consequently, the effect of incidence angle and additive properties may play a more prominent role in the flyer acceleration. In the present study we experimentally compared normal detonation loadings to grazing loadings using a 3-mm-thick aluminum slapper to impact-initiate a planar detonation wave in non-ideal explosive-particle admixtures, which subsequently accelerated a second 6.4-mm-thick flyer. Flyer acceleration was measured with heterodyne laser velocimetry (PDV). The explosive mixtures considered were packed beds of glass or steel particles of varying sizes saturated with sensitized nitromethane, and gelled nitromethane mixed with glass microballoons. Results showed that the primary parameter controlling changes in flyer velocity was the presence of a transmitted shock, with additive density and particle size playing only secondary roles. These results are similar to the grazing detonation experiments, however under normal loading the largest, higher density particles yielded the highest terminal flyer velocity, whereas in the grazing experiments the larger, low density particles yielded the highest terminal velocity.

The role of contact system in septic shock: the next target? An overview of the current evidence.

PubMed

Nicola, Henrique

2017-01-01

Septic shock remains challenging to intensive care units worldwide, despite recent documented improvement in mortality over the years. Multiple new therapies have been attempted without success in large clinical trials. Evidence concerning the role of the contact system and bradykinin on septic shock physiological manifestations is shown by this article. The objective of the study is to review the current evidence linking contact system activation and septic shock, as well as efficacy of available therapies targeting this pathophysiological pathway and to evaluate the potential of further researching the matter. Multiple animal studies are already available and suggestive of a meaningful role of contact system activation on septic shock. However, human trials are still scarce, and the ones available are not enough to establish such a strong connection. Furthermore, attempted therapies have been successful across multiple species, but not as much in humans. Therefore, contact system and septic shock relationship remains plentiful in questions to be answered in the coming years or decades. Whether the contact system is not as relevant in humans as it is in animals or there is only lack of evidence remains to be explained. The subject is an attractive open field for further research aiming to aid in tackling such a burdensome condition.

RNAi screen in Drosophila larvae identifies histone deacetylase 3 as a positive regulator of the hsp70 heat shock gene expression during heat shock.

PubMed

Achary, Bhavana G; Campbell, Katie M; Co, Ivy S; Gilmour, David S

2014-05-01

The transcription regulation of the Drosophila hsp70 gene is a complex process that involves the regulation of multiple steps, including the establishment of paused Pol II and release of Pol II into elongation upon heat shock activation. While the major players involved in the regulation of gene expression have been studied in detail, additional factors involved in this process continue to be discovered. To identify factors involved in hsp70 expression, we developed a screen that capitalizes on a visual assessment of heat shock activation using a hsp70-beta galactosidase reporter and publicly available RNAi fly lines to deplete candidate proteins. We validated the screen by showing that the depletion of HSF, CycT, Cdk9, Nurf 301, or ELL prevented the full induction of hsp70 by heat shock. Our screen also identified the histone deacetylase HDAC3 and its associated protein SMRTER as positive regulators of hsp70 activation. Additionally, we show that HDAC3 and SMRTER contribute to hsp70 gene expression at a step subsequent to HSF-mediated activation and release of the paused Pol II that resides at the promoter prior to heat shock induction. Copyright © 2014 Elsevier B.V. All rights reserved.

Implications for paediatric shock management in resource-limited settings: a perspective from the FEAST trial.

PubMed

Houston, Kirsty Anne; George, Elizabeth C; Maitland, Kathryn

2018-05-04

Although the African "Fluid Expansion as Supportive therapy" (FEAST) trial showed fluid resuscitation was harmful in children with severe febrile illness managed in resource-limited hospitals, the most recent evidence reviewed World Health Organization (WHO) guidelines continue to recommend fluid boluses in children with shock according to WHO criteria "WHO shock", arguing that the numbers included in the FEAST trial were too small to provide reasonable certainty. We re-analysed the FEAST trial results for all international definitions for paediatric shock including hypotensive (or decompensated shock) and the WHO criteria. In addition, we examined the clinical relevance of the WHO criteria to published and unpublished observational studies reporting shock in resource-limited settings. We established that hypotension was rare in children with severe febrile illness complicating only 29/3170 trial participants (0.9%). We confirmed that fluid boluses were harmful irrespective of the definitions of shock including the very small number with WHO shock (n = 65). In this subgroup 48% of bolus recipients died at 48 h compared to 20% of the non-bolus control group, an increased absolute risk of 28%, but translating to an increased relative risk of 240% (p = 0.07 (two-sided Fisher's exact test)). Examining studies describing the prevalence of the stringent WHO shock criteria in children presenting to hospital we found this was rare (~ 0.1%) and in these children mortality was very high (41.5-100%). The updated WHO guidelines continue to recommend boluses for a very limited number of children presenting at hospital with the strict definition of WHO shock. Nevertheless, the 3% increased mortality from boluses seen across FEAST trial participants would also include this subgroup of children receiving boluses. Recommendations aiming to differentiate WHO shock from other definitions will invariably lead to "slippage" at the bedside, with the potential of exposing a wider group of children to the harm of fluid-bolus therapy.

A VERY DEEP CHANDRA OBSERVATION OF THE GALAXY GROUP NGC 5813: AGN SHOCKS, FEEDBACK, AND OUTBURST HISTORY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randall, S. W.; Nulsen, P. E. J.; Jones, C.

2015-06-01

We present results from a very deep (650 ks) Chandra X-ray observation of the galaxy group NGC 5813, the deepest Chandra observation of a galaxy group to date. This system uniquely shows three pairs of collinear cavities, with each pair associated with an unambiguous active galactic nucleus (AGN) outburst shock front. The implied mean kinetic power is roughly the same for each outburst, demonstrating that the average AGN kinetic luminosity can remain stable over long timescales (∼50 Myr). The two older outbursts have larger, roughly equal total energies as compared with the youngest outburst, implying that the youngest outburst ismore » ongoing. We find that the gas radiative cooling rate and mean shock heating rate are well balanced at each shock front, suggesting that shock heating alone is sufficient to offset cooling and establish AGN/intracluster medium (ICM) feedback within at least the central 30 kpc. This heating takes place roughly isotropically and most strongly at small radii, as is required for feedback to operate. We suggest that shock heating may play a significant role in AGN feedback at smaller radii in other systems, where weak shocks are more difficult to detect. We find non-zero shock front widths that are too large to be explained by particle diffusion. Instead, all measured widths are consistent with shock broadening due to propagation through a turbulent ICM with a mean turbulent speed of ∼70 km s{sup −1}. Finally, we place lower limits on the temperature of any volume-filling thermal gas within the cavities that would balance the internal cavity pressure with the external ICM.« less

The impact of manual defibrillation technique on no-flow time during simulated cardiopulmonary resuscitation.

PubMed

Perkins, Gavin D; Davies, Robin P; Soar, Jasmeet; Thickett, David R

2007-04-01

Rapid defibrillation is the most effective strategy for establishing return of spontaneous circulation following cardiac arrest due to ventricular fibrillation. The aim of this study is to measure the delay due to of charging the defibrillator during chest compression in an attempt to reduce the duration of the pre-shock pause in between cessation of chest compressions and shock delivery as advocated by the American Heart Association (AHA) guidelines compared to charging the defibrillator immediately following rhythm analysis without resuming chest compressions as recommended by the European Resuscitation Council (ERC). This was a randomised controlled cross over trial comparing pre-shock pause times when defibrillation was performed on a manikin according to the AHA and ERC guidelines using paddles and hands free defibrillation systems. The pre-shock pause between cessation of chest compression and shock delivery was significantly different between techniques (Friedman test, P<0.0001). ERC paddles technique had the greatest pre-shock pause (7.4 s [6.7-11.2]) followed by ERC hands free (7.0 s [6.5-8.5]) and AHA paddles (1.6 s [1.1-2.3]). AHA hands free took the least amount of time (1.5 s [0.8-1.5]). Extrapolating these data to older defibrillators with longer charge times saw pre-shock pause intervals of 9 s (Codemaster XL) and 12 s (Lifepak 20) with the ERC approach. This study demonstrated clinically significant delays to defibrillation by analysing and charging the defibrillator without performing concurrent chest compressions. In a simulated scenario, charging the defibrillator whilst performing chest compressions was perceived as safe and significantly reduced the pre-shock pause between cessation of chest compression and shock delivery.

Attenuated adult biphasic shocks for prolonged pediatric ventricular fibrillation: support for pediatric automated defibrillators.

PubMed

Berg, Robert A

2004-09-01

To evaluate published data regarding the treatment of prolonged pediatric defibrillation, with special emphasis on the use of attenuated adult biphasic shocks for pediatric defibrillation. Review relevant human and animal literature. Rhythm analysis algorithms from two manufacturers of automated external defibrillators can accurately distinguish shockable from nonshockable rhythms in children. Theoretical considerations and transthoracic impedance data from animals and children suggest that pediatric defibrillation doses should not necessarily vary in a simple weight-based manner. Two piglet studies have established that an attenuated adult biphasic dosage can be successfully used for 3.5- to 24-kg animals in ventricular fibrillation. One study established that the attenuated adult biphasic dosage was at least as safe and effective as the standard monophasic weight-based dosing. This review supports the American Heart Association's new guidelines for pediatric automated external defibrillator usage: "Automated external defibrillators may be used for children 1 to 8 yrs of age who have no signs of circulation. Ideally the device should deliver a pediatric dose. The arrhythmia detection system used in the device should demonstrate high specificity for pediatric shockable rhythms, i.e., it will not recommend delivery of a shock for nonshockable rhythms."