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Sample records for induced pressure waves

  1. Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride

    SciTech Connect

    Hamlin, J.J.; Zocco, D.A.; Sayles, T.A.; Maple, M.B.; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2010-02-15

    A series of high-pressure electrical resistivity measurements on single crystals of TbTe{sub 3} reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge density wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near {approx} 12.4 GPa.

  2. Utilization of sparker induced pressure waves to tenderize meat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the feasibility of tenderizing meat using high pressure waves generated from a sparker source. Beef strip loins were cut into steaks from the anterior end and one to two steaks from each strip loin were randomly selected to serve as non-treated controls and the remaining ste...

  3. The pressure impulse of a laser-induced underwater shock wave

    NASA Astrophysics Data System (ADS)

    Tagawa, Yoshiyuki; Yamamoto, Shota; Hayasaka, Keisuke; Kameda, Masaharu

    2016-11-01

    We investigate the pressure impulse, the time integral of pressure evolution, of a laser-induced underwater shock wave. We simultaneously observe plasma formation, shock-wave expansion, and pressure in water using a combined measurement system that obtains high-resolution nanosecond-order image sequences. Remarkably, pressure impulse is found to distribute symmetrically for a wide range of experimental parameters even when the shock waves are emitted from an elongated plasma. In contrast, distribution of pressure peak is found to be non-spherically-symmetric. We rationalize aforementioned results by considering the structure of the underwater shock wave as a collection of multiple spherical shock waves originated from point-like plasmas in an elongated region. This work was supported by JSPS KAKANHI Grant Number JP26709007.

  4. Wave-induced pore pressure and effective stresses in a porous seabed with variable permeability

    SciTech Connect

    Jeng, D.S.; Seymour, B.R.

    1996-12-31

    An evaluation of wave-induced soil response is particularly useful for geotechnical and coastal engineers involved in the design of foundations for offshore structures. To simplify the mathematical procedure, most theories available for the wave/seabed interaction problem have assumed a porous seabed with uniform permeability, despite strong evidence of variable permeability. This paper proposes an analytical solution for the wave induced soil response in a porous seabed with variable permeability. Verification is available through reduction to the simple case of uniform permeability. The numerical results indicate that the effect of variable soil permeability on pore pressure and effective stresses is significant.

  5. A simplified physical model of pressure wave dynamics and acoustic wave generation induced by laser absorption in the retina.

    PubMed

    Till, S J; Milsom, P K; Rowlands, G

    2004-07-01

    Shock waves have been proposed in the literature as a mechanism for retinal damage induced by ultra-short laser pulses. For a spherical absorber, we derive a set of linear equations describing the propagation of pressure waves. We show that the formation of shock fronts is due to the form of the absorber rather than the inclusion of nonlinear terms in the equations. The analytical technique used avoids the need for a Laplace transform approach and is easily applied to other absorber profiles. Our analysis suggests that the 'soft' nature of the membrane surrounding retinal melanosomes precludes shock waves as a mechanism for the retinal damage induced by ultra-short pulse lasers. The quantitative estimates of the pressure gradients induced by laser absorption which are made possible by this work, together with detailed meso-scale or molecular modelling, will allow alternative damage mechanisms to be identified.

  6. Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2013-09-01

    Influence of ambient pressure on energy conversion efficiency from a Nd : glass laser pulse (λ = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ηbw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (λ = 10.6 µm), higher fraction absorption in the laser supported detonation regime ηLSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ηbw/ηLSD≈90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case.

  7. Shear wave measurements in shock-induced, high-pressure phases

    SciTech Connect

    Aidun, J.B.

    1993-01-01

    Structural phase transformations under shock loading are of considerable interest for understanding the response of solids under nonhydrostatic stresses and at high strain-rates. Examining shock-induced transformations from continuum level measurements is fundamentally constrained by the inability to directly identify microscopic processes, and also by the limited number of material properties that can be directly measured. ne latter limitation can be reduced by measuring both shear and compression waves using Lagrangian gauges in combined, compression and shear loading. The shear wave serves as an important, real-time probe of the shocked state and unloading response. Using results from a recent study of CaCO[sub 3], the unique information obtained from the shear wave speed and the detailed structure of the shear wave are shown to be useful for distinguishing the effects of phase transformations from yielding, as well as in characterizing the high-pressure phases and the yielding process under shock loading.

  8. Shear wave measurements in shock-induced, high-pressure phases

    SciTech Connect

    Aidun, J.B.

    1993-07-01

    Structural phase transformations under shock loading are of considerable interest for understanding the response of solids under nonhydrostatic stresses and at high strain-rates. Examining shock-induced transformations from continuum level measurements is fundamentally constrained by the inability to directly identify microscopic processes, and also by the limited number of material properties that can be directly measured. ne latter limitation can be reduced by measuring both shear and compression waves using Lagrangian gauges in combined, compression and shear loading. The shear wave serves as an important, real-time probe of the shocked state and unloading response. Using results from a recent study of CaCO{sub 3}, the unique information obtained from the shear wave speed and the detailed structure of the shear wave are shown to be useful for distinguishing the effects of phase transformations from yielding, as well as in characterizing the high-pressure phases and the yielding process under shock loading.

  9. Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners.

    PubMed

    Lin, James C; Wang, Zhangwei

    2010-04-01

    The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea.

  10. In situ measurements of impact-induced pressure waves in sandstone targets

    NASA Astrophysics Data System (ADS)

    Hoerth, Tobias; Schäfer, Frank; Nau, Siegfried; Kuder, Jürgen; Poelchau, Michael H.; Thoma, Klaus; Kenkmann, Thomas

    2014-10-01

    In the present study we introduce an innovative method for the measurement of impact-induced pressure waves within geological materials. Impact experiments on dry and water-saturated sandstone targets were conducted at a velocity of 4600 m/s using 12 mm steel projectiles to investigate amplitudes, decay behavior, and speed of the waves propagating through the target material. For this purpose a special kind of piezoresistive sensor capable of recording transient stress pulses within solid brittle materials was developed and calibrated using a Split-Hopkinson pressure bar. Experimental impact parameters (projectile size and speed) were kept constant and yielded reproducible signal curves in terms of rise time and peak amplitudes. Pressure amplitudes decreased by 3 orders of magnitude within the first 250 mm (i.e., 42 projectile radii). The attenuation for water-saturated sandstone is higher compared to dry sandstone which is attributed to dissipation effects caused by relative motion between bulk material and interstitial water. The proportion of the impact energy radiated as seismic energy (seismic efficiency) is in the order of 10-3. The present study shows the feasibility of real-time measurements of waves caused by hypervelocity impacts on geological materials. Experiments of this kind lead to a better understanding of the processes in the crater subsurface during a hypervelocity impact.

  11. Landslide stability: Role of rainfall-induced, laterally propagating, pore-pressure waves

    USGS Publications Warehouse

    Priest, G.R.; Schulz, W.H.; Ellis, W.L.; Allan, J.A.; Niem, A.R.; Niem, W.A.

    2011-01-01

    The Johnson Creek Landslide is a translational slide in seaward-dipping Miocene siltstone and sandstone (Astoria Formation) and an overlying Quaternary marine terrace deposit. The basal slide plane slopes sub-parallel to the dip of the Miocene rocks, except beneath the back-tilted toe block, where it slopes inland. Rainfall events raise pore-water pressure in the basal shear zone in the form of pulses of water pressure traveling laterally from the headwall graben down the axis of the slide at rates of 1-6 m/hr. Infiltration of meteoric water and vertical pressure transmission through the unsaturated zone has been measured at ~50 mm/hr. Infiltration and vertical pressure transmission were too slow to directly raise head at the basal shear zone prior to landslide movement. Only at the headwall graben was the saturated zone shallow enough for rainfall events to trigger lateral pulses of water pressure through the saturated zone. When pressure levels in the basal shear zone exceeded thresholds defined in this paper, the slide began slow, creeping movement as an intact block. As pressures exceeded thresholds for movement in more of the slide mass, movement accelerated, and differential displacement between internal slide blocks became more pronounced. Rainfall-induced pore-pressure waves are probably a common landslide trigger wherever effective hydraulic conductivity is high and the saturated zone is located near the surface in some part of a slide. An ancillary finding is apparently greater accuracy of grouted piezometers relative to those in sand packs for measurement of pore pressures at the installed depth.

  12. Morphological characterization of cardiac induced intracranial pressure (ICP) waves in patients with overdrainage of cerebrospinal fluid and negative ICP.

    PubMed

    Eide, Per Kristian; Sroka, Marek; Wozniak, Aleksandra; Sæhle, Terje

    2012-10-01

    Symptomatic overdrainage of cerebrospinal fluid (CSF) can be seen in shunted hydrocephalus patients and in non-shunted patients with spontaneous intracranial hypotension (SIH). In these patients, intracranial pressure (ICP) monitoring often reveals negative static ICP, while it is less understood how the pulsatile ICP (cardiac induced ICP waves) is affected. This latter aspect is addressed in the present study. A set of 40 ICP recordings from paediatric and adult hydrocephalus patients were randomly selected. Each cardiac induced ICP wave was automatically identified and manually verified by the beginning and ending diastolic minimum pressures and the systolic maximum pressure. The ICP wave parameters (static pressure, amplitude, rise time, rise time coefficient, downward coefficient, wave duration, and area-under-curve) were then automatically computed. The material of 40 ICP recordings provided a total of 3,192,166 cardiac induced ICP waves (1,292,522 in paediatric patients and 1,899,644 in adult patients). No apparent changes in ICP wave parameters were seen when mean ICP became negative, except that the parameters amplitude, rise time coefficient, downward coefficient and area under curve somewhat increased when mean ICP was below -15 mmHg.

  13. Pressure field induced in the water column by acoustic-gravity waves generated from sea bottom motion

    NASA Astrophysics Data System (ADS)

    C. A. Oliveira, Tiago; Kadri, Usama

    2016-10-01

    An uplift of the ocean bottom caused by a submarine earthquake can trigger acoustic-gravity waves that travel at near the speed of sound in water and thus may act as early tsunami precursors. We study the spatiotemporal evolution of the pressure field induced by acoustic-gravity modes during submarine earthquakes, analytically. We show that these modes may all induce comparable temporal variations in pressure at different water depths in regions far from the epicenter, though the pressure field depends on the presence of a leading acoustic-gravity wave mode. Practically, this can assist in the implementation of an early tsunami detection system by identifying the pressure and frequency ranges of measurement equipment and appropriate installation locations.

  14. Pressure-induced quenching of the charge-density-wave state observed by x-ray diffraction

    SciTech Connect

    Sacchetti, A.

    2010-05-03

    We report an x-ray diffraction study on the charge-density-wave (CDW) LaTe{sub 3} and CeTe{sub 3} compounds as a function of pressure. We extract the lattice constants and the CDW modulation wave-vector, and provide direct evidence for a pressure-induced quenching of the CDW phase. We observe subtle differences between the chemical and mechanical compression of the lattice. We account for these with a scenario where the effective dimensionality in these CDW systems is dependent on the type of lattice compression and has a direct impact on the degree of Fermi surface nesting and on the strength of fluctuation effects.

  15. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-09-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  16. Pressure Waves in Medicine: From Tissue Injury to Drug Delivery

    NASA Astrophysics Data System (ADS)

    Doukas, Apostolos G.

    2004-07-01

    Pressure waves have the potential to cause injury to cells and tissue or enable novel therapeutic modalities, such as fragmentation of kidney stones and drug delivery. Research on the biological effects of pressure waves have shown that the biological response on depends the pressure-wave characteristics. One of the most prominent effects induced by pressure waves is the permeabilization of a number of barrier structures (cell plasma membrane, skin and microbial biofilms) and facilitate the delivery of macromolecules. The permeabilization of the barrier structure is transient and the barrier function recovers. Thus, pressure waves can induce delivery of molecular species that would not normally cross the barrier structure.

  17. [Slow pressure waves during intracranial hypertension].

    PubMed

    Lemaire, J J

    1997-01-01

    Intracranial pressure waves include fast waves (pulse and respiration) and slow waves. Only the latter are considered here. Since the definition of three wave types in the pioneering works of Janny (1950) and Lundberg (1960), their study of frequential characteristics shows they are included in a spectrum where three contiguous frequency bands are individualised: the B wave band (BW) between 8 x 10(-3) Hz and 50 x 10(-3) Hz; the Infra B band (IB) below 8 x 10(-3) Hz; and the Ultra B band (UB) beyond 50 x 10(-3) Hz to 200 x 10(-3) Hz. The origin of these waves is vascular and some may be physiological. They are probably generated by central neuro-pacemakers and/or cyclic phenomena of cerebral autoregulation. They are linked with slow peripheral arterial pressure waves, with biological rhythms and with biomechanics and vasomotricity in the craniospinal enclosure. They are pathological for the slowest (IB), particularly if they are plateau waves, but the physiologic-pathologic boundary is not yet established for each type of slow waves. They can cause severe consequences if they result in major cerebral perfusion pressure changes, and if they induce or worsen herniations.

  18. Source duration of stress and water-pressure induced seismicity derived from experimental analysis of P wave pulse width in granite

    NASA Astrophysics Data System (ADS)

    Masuda, K.

    2013-12-01

    Pulse widths of P waves in granite, measured in the laboratory, were analyzed to investigate source durations of rupture processes for water-pressure induced and stress-induced microseismicity. Much evidence suggests that fluids in the subsurface are intimately linked to faulting processes. Studies of seismicity induced by water injection are thus important for understanding the trigger mechanisms of earthquakes as well as for engineering applications such as hydraulic fracturing of rocks at depth for petroleum extraction. Determining the cause of seismic events is very important in seismology and engineering; however, water-pressure induced seismic events are difficult to distinguish from those induced by purely tectonic stress. To investigate this problem, we analyzed the waveforms of acoustic emissions (AEs) produced in the laboratory by both water-pressure induced and stress-induced microseismicity. We used a cylinder (50 mm in diameter and 100 mm in length) of medium-grained granite. We applied a differential stress of about 70% of fracture strength, to the rock sample under 40 MPa confining pressure and held it constant throughout the experiment. When the primary creep stage and acoustic emissions (AEs) caused by the initial loading had ceased, we injected distilled water into the bottom end of the sample at a constant pressure of 17 MPa until macroscopic fracture occurred. We analysed AE waveforms produced by stress-induced AEs which occurred before the water-injection and by water-pressure induced AEs which occurred after the water-injection. Pulse widths were measured from the waveform traces plotted from the digital data. To investigate the source duration of the rupture process, we estimated the pulse width at the source and normalized by event magnitude to obtain a scaled pulse width at the source. After the effects of event size and hypocentral distance were removed from observed pulse widths, the ratio of the scaled source durations of water-pressure

  19. The behavior of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient. Ph.D. Thesis - Washington Univ., Seattle, Aug. 1972

    NASA Technical Reports Server (NTRS)

    Rose, W. C.

    1973-01-01

    The results of an experimental investigation of the mean- and fluctuating-flow properties of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient are presented. The turbulent boundary layer developed on the wall of an axially symmetric nozzle and test section whose nominal free-stream Mach number and boundary-layer thickness Reynolds number were 4 and 100,000, respectively. The adverse pressure gradient was induced by an externally generated conical shock wave. Mean and time-averaged fluctuating-flow data, including the complete experimental Reynolds stress tensor and experimental turbulent mass- and heat-transfer rates are presented for the boundary layer and external flow, upstream, within and downstream of the pressure gradient. The mean-flow data include distributions of total temperature throughout the region of interest. The turbulent mixing properties of the flow were determined experimentally with a hot-wire anemometer. The calibration of the wires and the interpretation of the data are discussed. From the results of the investigation, it is concluded that the shock-wave - boundary-layer interaction significantly alters the turbulent mixing characteristics of the boundary layer.

  20. Fluid pressure waves trigger earthquakes

    NASA Astrophysics Data System (ADS)

    Mulargia, Francesco; Bizzarri, Andrea

    2015-03-01

    Fluids-essentially meteoric water-are present everywhere in the Earth's crust, occasionally also with pressures higher than hydrostatic due to the tectonic strain imposed on impermeable undrained layers, to the impoundment of artificial lakes or to the forced injections required by oil and gas exploration and production. Experimental evidence suggests that such fluids flow along preferred paths of high diffusivity, provided by rock joints and faults. Studying the coupled poroelastic problem, we find that such flow is ruled by a nonlinear partial differential equation amenable to a Barenblatt-type solution, implying that it takes place in form of solitary pressure waves propagating at a velocity which decreases with time as v ∝ t [1/(n - 1) - 1] with n ≳ 7. According to Tresca-Von Mises criterion, these waves appear to play a major role in earthquake triggering, being also capable to account for aftershock delay without any further assumption. The measure of stress and fluid pressure inside active faults may therefore provide direct information about fault potential instability.

  1. The Role of Sub-Target in the Transversely Excited Atmospheric Pressure CO 2 Laser-Induced Shock-Wave Plasma

    NASA Astrophysics Data System (ADS)

    Suliyanti, Maria; Hedwig, Rinda; Kurniawan, Hendrik; Kagawa, Kiichiro

    1998-12-01

    A transversely excited atmospheric pressure (TEA) CO2 laser pulse (50 mJ, 100 ns) was focused on silicon grease which is painted on a copper plate as a subtarget with a power density of 6 GW/cm2 under reduced pressure. The comparison of the characteristics of the induced laser plasma between two cases, with subtarget and without subtarget was made. It is proved that the emission spectrum assigned to the silicon atom can be detected only for the case with the subtarget. It is also proved that in the absence of the subtarget, the gushing speed of the atom is very low, while for the case with subtarget, the gushing speed of atoms becomes very fast. It is shown that the setting of subtarget is very effective for producing laser-induced shock wave plasma and it is very effective for the realize quantitative analysis of a soft material.

  2. Role of anion ordering and effective pressure in the field-induced spin-density-wave phase of (TMTSF)2X

    NASA Astrophysics Data System (ADS)

    Minamidate, T.; Matsunaga, N.; Nomura, K.; Sasaki, T.

    2016-08-01

    Magnetoresistance and Hall resistance measurements were conducted in the field-induced spin-density-wave (FISDW) phase of (TMTSF)2ReO4 above 1.0 GPa, with an anion ordering specified by Q_\\text{AO}=(0, 1/2, 1/2) . The quantized Hall resistance shows the sequence N = 0, 1, 2, -2, 4, -4, -6, -8, \\cdots , with decreasing field that is successfully explained by the “extended standard model”. Consequently, we demonstrate that the difference between the chemical and hydrostatic pressures is linked to the appearance of the peculiar FISDW phase of the TMTSF salts with Q_\\text{AO}=(0, 1/2, *) .

  3. Investigation of Pressurized Wave Bearings

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    2003-01-01

    The wave bearing has been pioneered and developed by Dr. Dimofte over the past several years. This bearing will be the main focus of this research. It is believed that the wave bearing offers a number of advantages over the foil bearing, which is the bearing that NASA is currently pursuing for turbomachinery applications. The wave bearing is basically a journal bearing whose film thickness varies around the circumference approximately sinusoidally, with usually 3 or 4 waves. Being a rigid geometry bearing, it provides precise control of shaft centerlines. The wave profile also provides good load capacity and makes the bearing very stable. Manufacturing techniques have been devised that should allow the production of wave bearings almost as cheaply as conventional full-circular bearings.

  4. Non-β-blocking R-carvedilol enantiomer suppresses Ca2+ waves and stress-induced ventricular tachyarrhythmia without lowering heart rate or blood pressure.

    PubMed

    Zhang, Jingqun; Zhou, Qiang; Smith, Chris D; Chen, Haiyan; Tan, Zhen; Chen, Biyi; Nani, Alma; Wu, Guogen; Song, Long-Sheng; Fill, Michael; Back, Thomas G; Chen, S R Wayne

    2015-09-01

    Carvedilol is the current β-blocker of choice for suppressing ventricular tachyarrhythmia (VT). However, carvedilol's benefits are dose-limited, attributable to its potent β-blocking activity that can lead to bradycardia and hypotension. The clinically used carvedilol is a racemic mixture of β-blocking S-carvedilol and non-β-blocking R-carvedilol. We recently reported that novel non-β-blocking carvedilol analogues are effective in suppressing arrhythmogenic Ca(2+) waves and stress-induced VT without causing bradycardia. Thus, the non-β-blocking R-carvedilol enantiomer may also possess this favourable anti-arrhythmic property. To test this possibility, we synthesized R-carvedilol and assessed its effect on Ca(2+) release and VT. Like racemic carvedilol, R-carvedilol directly reduces the open duration of the cardiac ryanodine receptor (RyR2), suppresses spontaneous Ca(2+) oscillations in human embryonic kidney (HEK) 293 cells, Ca(2+) waves in cardiomyocytes in intact hearts and stress-induced VT in mice harbouring a catecholaminergic polymorphic ventricular tachycardia (CPVT)-causing RyR2 mutation. Importantly, R-carvedilol did not significantly alter heart rate or blood pressure. Therefore, the non-β-blocking R-carvedilol enantiomer represents a very promising prophylactic treatment for Ca(2+)- triggered arrhythmia without the bradycardia and hypotension often associated with racemic carvedilol. Systematic clinical assessments of R-carvedilol as a new anti-arrhythmic agent may be warranted.

  5. Non-β-blocking R-carvedilol enantiomer suppresses Ca2+ waves and stress-induced ventricular tachyarrhythmia without lowering heart rate or blood pressure

    PubMed Central

    Zhang, Jingqun; Zhou, Qiang; Smith, Chris D.; Chen, Haiyan; Tan, Zhen; Chen, Biyi; Nani, Alma; Wu, Guogen; Song, Long-Sheng; Fill, Michael; Back, Thomas G.; Wayne Chen, S.R.

    2016-01-01

    Carvedilol is the current β-blocker of choice for suppressing ventricular tachyarrhythmia (VT). However, carvedilol’s benefits are dose-limited, attributable to its potent β-blocking activity that can lead to bradycardia and hypotension. The clinically used carvedilol is a racemic mixture of β-blocking S-carvedilol and non-β-blocking R-carvedilol. We recently reported that novel non-β-blocking carvedilol analogues are effective in suppressing arrhythmogenic Ca2+ waves and stress-induced VT without causing bradycardia. Thus, the non-β-blocking R-carvedilol enantiomer may also possess this favourable anti-arrhythmic property. To test this possibility, we synthesized R-carvedilol and assessed its effect on Ca2+ release and VT. Like racemic carvedilol, R-carvedilol directly reduces the open duration of the cardiac ryanodine receptor (RyR2), suppresses spontaneous Ca2+ oscillations in human embryonic kidney (HEK) 293 cells, Ca2+ waves in cardiomyocytes in intact hearts and stress-induced VT in mice harbouring a catecholaminergic polymorphic ventricular tachycardia (CPVT)-causing RyR2 mutation. Importantly, R-carvedilol did not significantly alter heart rate or blood pressure. Therefore, the non-β-blocking R-carvedilol enantiomer represents a very promising prophylactic treatment for Ca2+-triggered arrhythmia without the bradycardia and hypotension often associated with racemic carvedilol. Systematic clinical assessments of R-carvedilol as a new anti-arrhythmic agent may be warranted. PMID:26348911

  6. Influence of Plasma Pressure Fluctuation on RF Wave Propagation

    NASA Astrophysics Data System (ADS)

    Liu, Zhiwei; Bao, Weimin; Li, Xiaoping; Liu, Donglin; Zhou, Hui

    2016-02-01

    Pressure fluctuations in the plasma sheath from spacecraft reentry affect radio-frequency (RF) wave propagation. The influence of these fluctuations on wave propagation and wave properties is studied using methods derived by synthesizing the compressible turbulent flow theory, plasma theory, and electromagnetic wave theory. We study these influences on wave propagation at GPS and Ka frequencies during typical reentry by adopting stratified modeling. We analyzed the variations in reflection and transmission properties induced by pressure fluctuations. Our results show that, at the GPS frequency, if the waves are not totally reflected then the pressure fluctuations can remarkably affect reflection, transmission, and absorption properties. In extreme situations, the fluctuations can even cause blackout. At the Ka frequency, the influences are obvious when the waves are not totally transmitted. The influences are more pronounced at the GPS frequency than at the Ka frequency. This suggests that the latter can mitigate blackout by reducing both the reflection and the absorption of waves, as well as the influences of plasma fluctuations on wave propagation. Given that communication links with the reentry vehicles are susceptible to plasma pressure fluctuations, the influences on link budgets should be taken into consideration. supported by the National Basic Research Program of China (No. 2014CB340205) and National Natural Science Foundation of China (No. 61301173)

  7. Extreme Vortical Waves Under External Pressure Action

    NASA Astrophysics Data System (ADS)

    Abrashkin, Anatoly; Soloviev, Alexander

    2013-04-01

    A vortical model for deep-water freak wave formation is presented. The wind action is simulated by non-uniform pressure on the free surface. The motion of the fluid is described by exact solution of 2D hydrodynamics equations for ideal inviscid fluid in Lagrange variables. Two types of flows are studied: the breather and freak wave in the field of Gerstner wave. Fluid particles rotate in circles of different radius and drift current is absent. The pressure on free surface is non-uniform and opposite in phase with the wave profile. It is examined alternating-sign and sign-constant negative distributions of the pressure. Dynamics of free surface and pressure for extreme waves are calculated. Unlike other models the analyzed flows are vortical. The vorticity is located mostly in the neighborhood of their peaks. For enough large amplitudes it has been found the effect of the wave overturn. The influence of distribution of the pressure and vorticity on appearance and character of the overturn are studied. It has been found that increasing of horizontal velocity of fluid with the height causes the overturn as in the case of simple wave. It is shown that the height of freak wave depends on the steepness of Gerstner wave. If its value is near to 1, then the height tends to 0. The freak wave can not form on a steep Gerstner flow. For small steepness the ratio between the height of the peak and Gerstner wave amplitude can reach 10 and even more. The wave of maximal amplitude has length from the range 20-60 m.

  8. Pressure waves in a supersaturated bubbly magma

    USGS Publications Warehouse

    Kurzon, I.; Lyakhovsky, V.; Navon, O.; Chouet, B.

    2011-01-01

    We study the interaction of acoustic pressure waves with an expanding bubbly magma. The expansion of magma is the result of bubble growth during or following magma decompression and leads to two competing processes that affect pressure waves. On the one hand, growth in vesicularity leads to increased damping and decreased wave amplitudes, and on the other hand, a decrease in the effective bulk modulus of the bubbly mixture reduces wave velocity, which in turn, reduces damping and may lead to wave amplification. The additional acoustic energy originates from the chemical energy released during bubble growth. We examine this phenomenon analytically to identify conditions under which amplification of pressure waves is possible. These conditions are further examined numerically to shed light on the frequency and phase dependencies in relation to the interaction of waves and growing bubbles. Amplification is possible at low frequencies and when the growth rate of bubbles reaches an optimum value for which the wave velocity decreases sufficiently to overcome the increased damping of the vesicular material. We examine two amplification phase-dependent effects: (1) a tensile-phase effect in which the inserted wave adds to the process of bubble growth, utilizing the energy associated with the gas overpressure in the bubble and therefore converting a large proportion of this energy into additional acoustic energy, and (2) a compressive-phase effect in which the pressure wave works against the growing bubbles and a large amount of its acoustic energy is dissipated during the first cycle, but later enough energy is gained to amplify the second cycle. These two effects provide additional new possible mechanisms for the amplification phase seen in Long-Period (LP) and Very-Long-Period (VLP) seismic signals originating in magma-filled cracks.

  9. Pressure wave charged repetitively pulsed gas laser

    DOEpatents

    Kulkarny, Vijay A.

    1982-01-01

    A repetitively pulsed gas laser in which a system of mechanical shutters bracketing the laser cavity manipulate pressure waves resulting from residual energy in the cavity gas following a lasing event so as to draw fresh gas into the cavity and effectively pump spent gas in a dynamic closed loop.

  10. Propagation of elastic pressure waves in a beam window

    NASA Astrophysics Data System (ADS)

    Davenne, T. R.; Loveridge, P.

    2016-09-01

    As particle accelerator beam power increases, stress on beam windows and targets increases. Many simulations are carried out to model the dynamic stresses that are induced in these critical components by near instantaneous beam heating. However while it is often easy to obtain simulation results there are few analytical solutions available to check the accuracy of simulation techniques. We follow the strand of several authors over the years who have offered analytical solutions to the classic problem of radial stress waves in a beam window. Many of these significant contributions have still had niggling issues with regard to resolving peak stress and limitations on the applied initial heating condition. We formulate an analytical expression for the radial pressure waves based on a Green's function solution of Feynman's wave equation. A complete analysis of the problem demonstrates that a hypothesis that beam induced pressure waves are composed of a static and transient component is indeed correct. The analytical expression is shown to give stable bounded solutions with easily determined peak stress levels. Finally a comparison between analytical expression and finite element analysis of the problem yields some general guidelines that should be adhered to for achieving accurate stress wave simulations.

  11. Pressure waves generated by steady flames.

    NASA Technical Reports Server (NTRS)

    Kuhl, A. L.; Kamel, M. M.; Oppenheim, A. K.

    1973-01-01

    Analysis of pressure waves that can be generated by clouds of explosive gas mixtures in a free atmosphere which is initially at a uniform state. The treatment is restricted only to the final stage of constant flame velocity when the flowfield is self-similar. By the introduction of reduced blast-wave parameters as phase-plane coordinates, the problem is resolved into the determination of the appropriate integral curves on this plane. Results, including space profiles of gasdynamic parameters, have been computed for a specific case of a hydrocarbon-air mixture characterized by a specific heat ratio of 1.3, sound speed at NTP of 345 m/sec, and volumetric expansion ratio corresponding to constant pressure deflagration of 7. Maximum overpressure ratios that can be generated by such flames in point-and line-symmetrical waves range from .00053, for the lower bound in the burning speed, up to 6 for the deflagration, while, for the average speeds of 5 to 10 m/sec, they are at a level of 0.05 to 0.10.

  12. Pressure induced polymerization of Formates

    NASA Astrophysics Data System (ADS)

    Tschauner, Oliver

    2004-03-01

    The discovery of pressure induced polymerization of CO2 inspired us to search for C-O based chain structures forming at high pressure. We used salts of carboxylic acids as starting materials and exposed them to pressures between 10 and 30 GPa. Upon heating to temperatures above 1800 K we observed deprotonation and significant changes in the Raman shifts of C-O streching modes. Structure analysis based on powder diffraction patterns collected at sector 16 of the APS showed formation of extended C-O chain structures with the cations of the salts residing in the interchain spaces. These new high pressure polymers are interesting by their mechanical strength and provide basic molecular patterns of organic metallic conductors.

  13. Pressure induced metallization of Germane

    NASA Astrophysics Data System (ADS)

    Martinez-Canales, M.; Bergara, A.; Feng, J.; Grochala, W.

    2006-09-01

    Recently reported superconductivity in lithium under pressure has renewed the interest on hydrogen and hydrogen-rich systems in the long standing quest for room temperature superconductivity. Although the required metallization of pure hydrogen cannot be achieved within correct experimental capabilities, chemical precompression exerted by heavier atoms in compounds with a large hydrogen content is expected to imply that lower pressures might be required to attain the metallic transition in these alloys. In this article, we present an ab initio analysis of pressure induced metallization of germane, as a particular case between group IVa hydrides. According to our calculations, metallization of germane is predicted to occur at an experimentally accessible pressure of around 70 GPa, which corresponds to a compression factor of 3.4.

  14. Solitary Water Waves of Large Amplitude Generated by Surface Pressure

    NASA Astrophysics Data System (ADS)

    Wheeler, Miles H.

    2015-11-01

    We consider exact nonlinear solitary water waves on a shear flow with an arbitrary distribution of vorticity. Ignoring surface tension, we impose a non-constant pressure on the free surface. Starting from a uniform shear flow with a flat free surface and a supercritical wave speed, we vary the surface pressure and use a continuation argument to construct a global connected set of symmetric solitary waves. This set includes waves of depression whose profiles increase monotonically from a central trough where the surface pressure is at its lowest, as well as waves of elevation whose profiles decrease monotonically from a central crest where the surface pressure is at its highest. There may also be two waves in this connected set with identical surface pressure, only one of which is a wave of depression.

  15. Pressure wave propagation studies for oscillating cascades

    NASA Technical Reports Server (NTRS)

    Huff, Dennis L.

    1992-01-01

    The unsteady flowfield around an oscillating cascade of flat plates is studied using a time marching Euler code. Exact solutions based on linear theory serve as model problems to study pressure wave propagation in the numerical solution. The importance of using proper unsteady boundary conditions, grid resolution, and time step is demonstrated. Results show that an approximate non-reflecting boundary condition based on linear theory does a good job of minimizing reflections from the inflow and outflow boundaries and allows the placement of the boundaries to be closer than cases using reflective boundary conditions. Stretching the boundary to dampen the unsteady waves is another way to minimize reflections. Grid clustering near the plates does a better job of capturing the unsteady flowfield than cases using uniform grids as long as the CFL number is less than one for a sufficient portion of the grid. Results for various stagger angles and oscillation frequencies show good agreement with linear theory as long as the grid is properly resolved.

  16. Pressure wave propagation studies for oscillating cascades

    NASA Technical Reports Server (NTRS)

    Huff, Dennis L.

    1992-01-01

    The unsteady flow field around an oscillating cascade of flat plates is studied using a time marching Euler code. Exact solutions based on linear theory serve as model problems to study pressure wave propagation in the numerical solution. The importance of using proper unsteady boundary conditions, grid resolution, and time step is demonstrated. Results show that an approximate non-reflecting boundary condition based on linear theory does a good job of minimizing reflections from the inflow and outflow boundaries and allows the placement of the boundaries to be closer than cases using reflective boundary conditions. Stretching the boundary to dampen the unsteady waves is another way to minimize reflections. Grid clustering near the plates does a better job of capturing the unsteady flow field than cases using uniform grids as long as the CFL number is less than one for a sufficient portion of the grid. Results for various stagger angles and oscillation frequencies show good agreement with linear theory as long as the grid is properly resolved.

  17. Measurement of elastic waves induced by the reflection of light.

    PubMed

    Požar, Tomaž; Možina, Janez

    2013-11-01

    The reflection of light from the surface of an elastic solid gives rise to various types of elastic waves that propagate inside the solid. The weakest waves are generally those that are generated by the radiation pressure acting during the reflection of the light. Here, we present the first quantitative measurement of such light-pressure-induced elastic waves inside an ultrahigh-reflectivity mirror. Amplitudes of a few picometers were observed at the rear side of the mirror with a displacement-measuring conical piezoelectric sensor when laser pulses with a fluence of 1 J/cm(2) were reflected from the front side of the mirror.

  18. Wave-Induced Groundwater Flows in a Freshwater Beach Aquifer

    NASA Astrophysics Data System (ADS)

    Malott, S. S.; Robinson, C. E.; O'Carroll, D. M.

    2014-12-01

    Wave-induced recirculation across the sediment-water interface can impact the transport of pollutants through a beach aquifer and their ultimate flux into coastal waters. The fate of nutrients (e.g. from septic and agricultural sources) and fecal indicator bacteria (e.g. E. coil) near the sediment-water interface are of particular concern as these pollutants often lead to degradation of recreational water quality and nearshore ecosystems. This paper presents detailed field measurements of groundwater flows in a freshwater beach aquifer on Lake Huron over periods of intensified wave conditions. Quantifying wave-driven processes in a freshwater beach aquifer enables wave effects to be studied in isolation from density and tidal effects that complicate groundwater flows in marine beaches. Water exchange across the sediment-water interface and groundwater flow patterns were measured using groundwater wells, arrays of vertically nested pressure transducers and manometers. Results show that wave action induces rapid infiltration/exfiltration across the sediment-water interface and a larger recirculation cell through the beach aquifer. Field data is used to validate a numerical groundwater model of wave-induced groundwater flows. While prior studies have simulated the effects of waves on beach groundwater flows, this study is the first attempt to validate these sophisticated modeling approaches. Finally, field data illustrating the impact of wave-induced groundwater flows on nutrient and bacteria fate and transport in beach aquifers will also be presented.

  19. Reconfigurable heat-induced spin wave lenses

    NASA Astrophysics Data System (ADS)

    Dzyapko, O.; Borisenko, I. V.; Demidov, V. E.; Pernice, W.; Demokritov, S. O.

    2016-12-01

    We study the control and manipulation of propagating spin waves in yttrium iron garnet films using a local laser-induced heating. We show that, due to the refraction of spin waves in the thermal gradients, the heated region acts as a defocusing lens for Damon-Eshbach spin waves and as a focusing lens for backward volume waves enabling collimation of spin-wave beams in the latter case. In addition to the focusing/defocusing functionality, the local heating allows one to manipulate the propagation direction of the spin-wave beams and to efficiently suppress their diffraction spreading by utilizing caustic effects.

  20. Plateau Waves of Intracranial Pressure and Multimodal Brain Monitoring.

    PubMed

    Dias, Celeste; Maia, Isabel; Cerejo, Antonio; Smielewski, Peter; Paiva, José-Artur; Czosnyka, Marek

    2016-01-01

    The aim of this study was to describe multimodal brain monitoring characteristics during plateau waves of intracranial pressure (ICP) in patients with head injury, using ICM+ software for continuous recording. Plateau waves consist of an abrupt elevation of ICP above 40 mmHg for 5-20 min. This is a prospective observational study of patients with head injury who were admitted to a neurocritical care unit and who developed plateau waves. We analyzed 59 plateau waves that occurred in 8 of 18 patients (44 %). At the top of plateau waves arterial blood pressure remained almost constant, but cerebral perfusion pressure, cerebral blood flow, brain tissue oxygenation, and cerebral oximetry decreased. After plateau waves, patients with a previously better autoregulation status developed hyperemia, demonstrated by an increase in cerebral blood flow and brain oxygenation. Pressure and oxygen cerebrovascular reactivity indexes (pressure reactivity index and ORxshort) increased significantly during the plateau wave as a sign of disruption of autoregulation. Bedside multimodal brain monitoring is important to characterize increases in ICP and give differential diagnoses of plateau waves, as management of this phenomenon differs from that of regular ICP.

  1. Corotating pressure waves without streams in the solar wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1983-01-01

    Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect; it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun.

  2. Lower-tropospheric waves and wave-induced turbulence zones: Insights from T-REX

    NASA Astrophysics Data System (ADS)

    Grubisic, V.; Xiao, M.; Haimov, S.; French, J.; Oolman, L.

    2009-04-01

    During the Terrain-induced Rotor Experiment (T-REX) in March/April 2006 highly turbulent flows in the lee of the Sierra Nevada were probed by the University of Wyoming King Air (UWKA) aircraft. In situ thermodynamic and kinematic data was obtained by UWKA on rotor and wave structures over Owens Valley in a number of research missions under strong lee-wave conditions. In situ measurements by the UWKA have been used to examine strongly turbulent flow regions documented by the UWKA and their relationship to the flow structures over Owens Valley. Wave-induced pressure perturbations determined from the aircraft measurements are compared with the surface pressure perturbations derived from the network of surface pressure sensors in Owens Valley in order to detect wave-induced boundary-layer separation. Sufficiently strong signal returns from the Wyoming Cloud Radar (WCR) were granted by the presence of ice particles within different types of clouds associated with the wave/rotor system, including mountain cap clouds over the Sierra crest, "spill over" clouds over the eastern Sierra slopes and in a few events rotor clouds over Owens Valley. The results of the dual-Doppler analyses for the rotor clouds reveal the presence of fine-scale structures within the roll clouds in the upper part of the rotor circulation.

  3. Air pressure waves from Mount St. Helens eruptions

    NASA Astrophysics Data System (ADS)

    Reed, Jack W.

    1987-10-01

    Infrasonic recordings of the pressure wave from the Mount St. Helens (MSH) eruption on May 18, 1980, together with the weather station barograph records were used to estimate an equivalent explosion airblast yield for this eruption. Pressure wave amplitudes versus distance patterns were found to be comparable with patterns found for a small-scale nuclear explosion, the Krakatoa eruption, and the Tunguska comet impact, indicating that the MSH wave came from an explosion equivalent of about 5 megatons of TNT. The peculiar audibility pattern reported, with the blast being heard only at ranges beyond about 100 km, is explained by consideration of finite-amplitude shock propagation developments.

  4. Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic power.

    PubMed

    Mynard, Jonathan P; Smolich, Joseph J

    2016-04-15

    Wave intensity analysis provides detailed insights into factors influencing hemodynamics. However, wave intensity is not a conserved quantity, so it is sensitive to diameter variations and is not distributed among branches of a junction. Moreover, the fundamental relation between waves and hydraulic power is unclear. We, therefore, propose an alternative to wave intensity called "wave power," calculated via incremental changes in pressure and flow (dPdQ) and a novel time-domain separation of hydraulic pressure power and kinetic power into forward and backward wave-related components (ΠP±and ΠQ±). Wave power has several useful properties:1) it is obtained directly from flow measurements, without requiring further calculation of velocity;2) it is a quasi-conserved quantity that may be used to study the relative distribution of waves at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between wave power and changes in ΠP±and show that wave reflection reduces transmitted power. Absolute values of ΠP±represent wave potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that wave potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing waves that transfer this energy. These techniques and principles are verified numerically and also experimentally with pressure/flow measurements in all branches of a central bifurcation in sheep, under a wide range of hemodynamic conditions. The proposed "wave power analysis," encompassing wave power, wave potential, and wave separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics.

  5. Hydrogen sulfide induces calcium waves in astrocytes.

    PubMed

    Nagai, Yasuo; Tsugane, Mamiko; Oka, Jun-Ichiro; Kimura, Hideo

    2004-03-01

    Hydrogen sulfide (H2S) modifies hippocampal long-term potentiation (LTP) and functions as a neuromodulator. Here, we show that H2S increases intracellular Ca2+ and induces Ca2+ waves in primary cultures of astrocytes as well as hippocampal slices. H2S increases the influx of Ca2+ and to a lesser extent causes the release from intracellular Ca2+ stores. Ca2+ waves induced by neuronal excitation as well as responses to exogenously applied H2S are potently blocked by La3+ and Gd3+, inhibitors of Ca2+ channels. These observations suggest that H2S induces Ca2+ waves that propagate to neighboring astrocytes.

  6. Characterization of the pressure wave originating in the explosion of a gas cloud

    NASA Astrophysics Data System (ADS)

    Essers, J. A.

    Models for predicting the effects of hydrocarbon explosions on nuclear power plants are discussed. By solving the Euler equations for simple one dimensional models, formulas predicting wave speed, induced flow velocity, reflected wave speed and overpressure as functions of the local value of incident wave overpressure are obtained. A simplified nonlinear isentropic potential flow model is proposed. Errors in predicting wave characteristics from this model or from classical linear acoustic models are evaluated. Formulas to predict the evolution of main pressure pulse characteristics are given. The time and distance required for the formation of a sharp pressure pulse and to obtain a significant spreading of expansion phase is assessed. The ability of models to accurately predict these deformations is discussed. The isentropic model leads to an excellent prediction of all wave characteristics if the overpressure is not very large. Except for very weak overpressures, the accuracy of acoustic models is poor.

  7. Initial condition effect on pressure waves in an axisymmetric jet

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey H.; Raman, Ganesh

    1988-01-01

    A pair of microphones (separated axially by 5.08 cm and laterally by 1.3 cm) are placed on either side of the jet centerline to investigate coherent pressure fluctuations in an axisymmetric jet at Strouhal numbers less than unity. Auto-spectra, transfer-function, and coherence measurements are made for a tripped and untripped boundary layer initial condition. It was found that coherent acoustic pressure waves originating in the upstream plenum chamber propagate a greater distance downstream for the tripped initial condition than for the untripped initial condition. In addition, for the untripped initial condition the development of the coherent hydrodynamic pressure waves shifts downstream.

  8. Induced topological pressure for topological dynamical systems

    SciTech Connect

    Xing, Zhitao; Chen, Ercai

    2015-02-15

    In this paper, inspired by the article [J. Jaerisch et al., Stochastics Dyn. 14, 1350016, pp. 1-30 (2014)], we introduce the induced topological pressure for a topological dynamical system. In particular, we prove a variational principle for the induced topological pressure.

  9. An Experimental Investigation of the Wave Pattern Generated by a Moving Pressure Source: Solitary Capillary-Gravity Waves

    NASA Astrophysics Data System (ADS)

    Duncan, J. H.; Diorio, J. D.; Lisiewski, A.; Harris, R.

    2009-11-01

    The wave pattern generated by a small pressure source moving across a water surface at speeds less than the minimum phase speed for linear gravity-capillary waves (cmin = 23 cm/s) was investigated experimentally. The resulting wave pattern was measured using cinematic shadowgraph and laser-induced fluorescence (LIF) techniques. The results show the existence of several distinct behavioral states. At low speeds, no wave behavior is observed and the pattern resembles the symmetric stationary condition. However, at a critical speed, but still below cmin, the pattern undergoes a sudden transition to an asymmetric state with a stationary, 2D solitary wave that forms behind the pressure source. This solitary wave is elongated in the cross-stream relative to the stream-wise direction and resembles gravity-capillary ``lumps'' observed in previous numerical calculations. As the translation speed approaches cmin, another time-dependent behavior is observed characterized by periodic ``shedding'' from a V-shaped solitary wave pattern. This work will be discussed in conjunction with the recent numerical calculations of T. Akylas and his research group.

  10. Acoustic wave propagation in high-pressure system.

    PubMed

    Foldyna, Josef; Sitek, Libor; Habán, Vladimír

    2006-12-22

    Recently, substantial attention is paid to the development of methods of generation of pulsations in high-pressure systems to produce pulsating high-speed water jets. The reason is that the introduction of pulsations into the water jets enables to increase their cutting efficiency due to the fact that the impact pressure (so-called water-hammer pressure) generated by an impact of slug of water on the target material is considerably higher than the stagnation pressure generated by corresponding continuous jet. Special method of pulsating jet generation was developed and tested extensively under the laboratory conditions at the Institute of Geonics in Ostrava. The method is based on the action of acoustic transducer on the pressure liquid and transmission of generated acoustic waves via pressure system to the nozzle. The purpose of the paper is to present results obtained during the research oriented at the determination of acoustic wave propagation in high-pressure system. The final objective of the research is to solve the problem of transmission of acoustic waves through high-pressure water to generate pulsating jet effectively even at larger distances from the acoustic source. In order to be able to simulate numerically acoustic wave propagation in the system, it is necessary among others to determine dependence of the sound speed and second kinematical viscosity on operating pressure. Method of determination of the second kinematical viscosity and speed of sound in liquid using modal analysis of response of the tube filled with liquid to the impact was developed. The response was measured by pressure sensors placed at both ends of the tube. Results obtained and presented in the paper indicate good agreement between experimental data and values of speed of sound calculated from so-called "UNESCO equation". They also show that the value of the second kinematical viscosity of water depends on the pressure.

  11. Quantification of wave reflection using peripheral blood pressure waveforms.

    PubMed

    Kim, Chang-Sei; Fazeli, Nima; McMurtry, M Sean; Finegan, Barry A; Hahn, Jin-Oh

    2015-01-01

    This paper presents a novel minimally invasive method for quantifying blood pressure (BP) wave reflection in the arterial tree. In this method, two peripheral BP waveforms are analyzed to obtain an estimate of central aortic BP waveform, which is used together with a peripheral BP waveform to compute forward and backward pressure waves. These forward and backward waves are then used to quantify the strength of wave reflection in the arterial tree. Two unique strengths of the proposed method are that 1) it replaces highly invasive central aortic BP and flow waveforms required in many existing methods by less invasive peripheral BP waveforms, and 2) it does not require estimation of characteristic impedance. The feasibility of the proposed method was examined in an experimental swine subject under a wide range of physiologic states and in 13 cardiac surgery patients. In the swine subject, the method was comparable to the reference method based on central aortic BP and flow. In cardiac surgery patients, the method was able to estimate forward and backward pressure waves in the absence of any central aortic waveforms: on the average, the root-mean-squared error between actual versus computed forward and backward pressure waves was less than 5 mmHg, and the error between actual versus computed reflection index was less than 0.03.

  12. Dual mode acoustic wave sensor for precise pressure reading

    NASA Astrophysics Data System (ADS)

    Mu, Xiaojing; Kropelnicki, Piotr; Wang, Yong; Randles, Andrew Benson; Chuan Chai, Kevin Tshun; Cai, Hong; Gu, Yuan Dong

    2014-09-01

    In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm-50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of -50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.

  13. Diaphragm Pressure Wave Generator Developments at Industrial Research Ltd

    NASA Astrophysics Data System (ADS)

    Caughley, A. J.; Emery, N.; Glasson, N. D.

    2010-04-01

    Industrial Research Ltd (IRL) have been developing a unique diaphragm based pressure wave generator technology for pulse tube and Stirling cryocoolers. Our system uses a metal diaphragm to separate the clean cryocooler gas circuit from a conventionally lubricated mechanical driver, thus producing a clean pressure wave with a long life drive that does not require the precision manufacture and associated costs of large linear motors. The first successful diaphragm pressure wave generator produced 3.2 kW of acoustic power at an electro-acoustic efficiency of 72% with a swept volume of 200 ml and a prototype has now accumulated over 2500 hours running. This paper describes recent developments in the technology. To explore scaling, a small diaphragm pressure wave generator with a swept volume of 20 ml has been constructed and has delivered 454 W of acoustic power at an electro-acoustic efficiency of 60%. Improvements have been made to the hydraulic force amplifier mechanism for driving the diaphragms resulting in a cheaper and lighter mechanism than the mechanical linkage originally used. To meet a customer's specific requirements, the 200 ml pressure wave generator's stroke was extended to achieve 240 ml of swept volume thereby increasing its acoustic power delivery to 4.1 kW without compromising efficiency.

  14. 30 kW metal diaphragm pressure wave generator

    NASA Astrophysics Data System (ADS)

    Caughley, A.; Branje, P.; Klok, T.

    2014-01-01

    Callaghan Innovation has been developing a metal-diaphragm pressure wave generator technology for pulse tube or Stirling cryocoolers since 2005. A series of successful pressure wave generators have been designed, fabricated and demonstrated ranging in swept volume from 20 to 240 cc driven by commercially available induction motors of powers from 0.5 kW to 7.5 kW respectively. A number of pulse tubes have also been design and successfully trialed with these pressure wave generators. Cooling powers up to 600 W at 120 K have been achieved. We have now scaled the pressure wave generator technology to 1000cc swept volume, powered by a 30 kW induction motor with the intention of providing over 20 kW of acoustic power to either pulse tube or Stirling expanders. The aim is to develop a cryocooler with more than 1000 W of refrigeration at 77 K. Target applications include liquefaction and High Temperature Superconducting devices. Initial results from testing the 1000 cc pressure wave generator are presented and we will discuss the challenges and advantages involved in scaling the metal diaphragm technology to higher acoustic powers.

  15. Acoustic Wave Propagation in Pressure Sense Lines

    NASA Technical Reports Server (NTRS)

    Vitarius, Patrick; Gregory, Don A.; Wiley, John; Korman, Valentin

    2003-01-01

    Sense lines are used in pressure measurements to passively transmit information from hostile environments to areas where transducers can be used. The transfer function of a sense line can be used to obtain information about the measured environment from the protected sensor. Several properties of this transfer function are examined, including frequency dependence, Helmholtz resonance, and time of flight delay.

  16. Propagation velocity and reflection of pressure waves in the canine coronary artery.

    PubMed

    Arts, T; Kruger, R T; van Gerven, W; Lambregts, J A; Reneman, R S

    1979-10-01

    In this study the pressure wave velocity in the anterior descending branch of the left coronary artery (LADC) of the dog was measured by determining the delay time between pressure pulses along this artery. This method can only be applied if reflections of the pressure wave distal to the sites of pressure measurement are insignificant. From araldite casts of the coronary arteries the following relation between the diameter proximal to (dprox) and distal to (ddist 1, ddist 2) a bifurcation was found: dprox2.55 = ddist12.55 + ddist 22.55, indicating that reflections at a bifurcation areminimal. In dogs reflections were studied by inducing during diastole a pressure pulse in the aorta and measuring pressure and volume flow proximal to and pressure distal to a segment of the LADC at various levels of the coronary peripheral resistance. Reflection of high-frequency components (greater than 7 Hz) was found to be insignificant, allowing application of the above-mentioned method for measuring the wave-front velocity, which is insensitive to low-frequency reflection. At a pressure in the LADC of 13.3 kPa this velocity was 8.6 +/- 1.4 m.s-1 (mean +/- SD). The calculated dynamic cross-sectional stiffness (deltaP/(deltaA/A)) of the LADC was 97 +/- 11 kPa (mean +/- SE) at an arterial pressure of 13.3 kPa.

  17. Cerebral perfusion pressure and abnormal intracranial pressure wave forms: their relation to outcome in birth asphyxia.

    PubMed

    Raju, T N; Vidyasagar, D; Papazafiratou, C

    1981-06-01

    Intracranial pressure (ICP) studies were carried out in 14 infants with severe birth asphyxia and brain damage. A markedly low cerebral perfusion pressure (CPP) was noted in infants who died and in 1 infant who survived with cerebral palsy. The long-term ICP tracing revealed negative waves and plateau waves in 2 infants. Cushing response was noted in 2 infants who had elevated ICP. The value and significance of evaluated CPP and of abnormal waveforms are discussed.

  18. Generation of high pressure and temperature by converging detonation waves

    NASA Astrophysics Data System (ADS)

    Singh, V. P.; Shukla, S. K.

    1987-07-01

    Generation of high pressure and temperature has various applications in defense. Several techniques, viz flying plate method, collapsing of linear, convergence of detonation waves in solid explosives, have been established in this connection. In this paper, converging detonation waves in solid explosives, where variable heat of detonation is being added to the front, are studied by using Whitham's characteristics rule. Results are compared with those reported elsewhere.

  19. Reduction of Orifice-Induced Pressure Errors

    NASA Technical Reports Server (NTRS)

    Plentovich, Elizabeth B.; Gloss, Blair B.; Eves, John W.; Stack, John P.

    1987-01-01

    Use of porous-plug orifice reduces or eliminates errors, induced by orifice itself, in measuring static pressure on airfoil surface in wind-tunnel experiments. Piece of sintered metal press-fitted into static-pressure orifice so it matches surface contour of model. Porous material reduces orifice-induced pressure error associated with conventional orifice of same or smaller diameter. Also reduces or eliminates additional errors in pressure measurement caused by orifice imperfections. Provides more accurate measurements in regions with very thin boundary layers.

  20. Ultrasonic wave based pressure measurement in small diameter pipeline.

    PubMed

    Wang, Dan; Song, Zhengxiang; Wu, Yuan; Jiang, Yuan

    2015-12-01

    An effective non-intrusive method of ultrasound-based technique that allows monitoring liquid pressure in small diameter pipeline (less than 10mm) is presented in this paper. Ultrasonic wave could penetrate medium, through the acquisition of representative information from the echoes, properties of medium can be reflected. This pressure measurement is difficult due to that echoes' information is not easy to obtain in small diameter pipeline. The proposed method is a study on pipeline with Kneser liquid and is based on the principle that the transmission speed of ultrasonic wave in pipeline liquid correlates with liquid pressure and transmission speed of ultrasonic wave in pipeline liquid is reflected through ultrasonic propagation time providing that acoustic distance is fixed. Therefore, variation of ultrasonic propagation time can reflect variation of pressure in pipeline. Ultrasonic propagation time is obtained by electric processing approach and is accurately measured to nanosecond through high resolution time measurement module. We used ultrasonic propagation time difference to reflect actual pressure in this paper to reduce the environmental influences. The corresponding pressure values are finally obtained by acquiring the relationship between variation of ultrasonic propagation time difference and pressure with the use of neural network analysis method, the results show that this method is accurate and can be used in practice.

  1. Hydrodynamic pressure of breaking waves on buildings and their interaction

    NASA Astrophysics Data System (ADS)

    Kashevarova, G. G.; Martirosyan, A. S.

    2016-10-01

    In the course of numerical experiments the problem hydrodynamic pressure of breaking waves on buildings and their interaction was solved in a related setting, e.g. fluid flow and deformation of the building were calculated simultaneously. The method of calculation allows evaluating the dependence of the hydrodynamic pressure of water flow from the shape of the building in plan, size and orientation relative to the direction of flow stream. This study allowed to perform strength analysis of buildings under the action of breakthrough wave for evaluate the necessity of guard measures.

  2. Acoustic waves in gases with strong pressure gradients

    NASA Technical Reports Server (NTRS)

    Zorumski, William E.

    1989-01-01

    The effect of strong pressure gradients on the acoustic modes (standing waves) of a rectangular cavity is investigated analytically. When the cavity response is represented by a sum of modes, each mode is found to have two resonant frequencies. The lower frequency is near the Viaesaela-Brundt frequency, which characterizes the buoyant effect, and the higher frequency is above the ordinary acoustic resonance frequency. This finding shows that the propagation velocity of the acoustic waves is increased due to the pressure gradient effect.

  3. Two-phase flow model for energetic proton beam induced pressure waves in mercury target systems in the planned European Spallation Source

    NASA Astrophysics Data System (ADS)

    Barna, I. F.; Imre, A. R.; Rosta, L.; Mezei, F.

    2008-12-01

    Two-phase flow calculations are presented to investigate the thermo-hydraulical effects of the interaction between 2 ms long 1.3 GeV proton pulses with a closed mercury loop which can be considered as a model system of the target of the planned European Spallation Source (ESS) facility. The two-fluid model consists of six first-order partial differential equations that present one dimensional mass, momentum and energy balances for mercury vapor and liquid phases are capable to describe quick transients like cavitation effects or shock waves. The absorption of the proton beam is represented as instantaneous heat source in the energy balance equations. Densities and internal energies of the mercury liquid-vapor system is calculated from the van der Waals equation, but general method how to obtain such properties using arbitrary equation of state is also presented. A second order accurate high-resolution shock-capturing numerical scheme is applied with different kind of limiters in the numerical calculations. Our analysis show that even 75 degree temperature heat shocks cannot cause considerable cavitation effects in mercury.

  4. Rapid miniature fiber optic pressure sensors for blast wave measurements

    NASA Astrophysics Data System (ADS)

    Zou, Xiaotian; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

    2013-02-01

    Traumatic brain injury (TBI) is a serious potential threat to soldiers who are exposed to explosions. Since the pathophysiology of TBI associated with a blast wave is not clearly defined, it is crucial to have a sensing system to accurately quantify the blast wave dynamics. This paper presents an ultra-fast fiber optic pressure sensor based on Fabry-Perot (FP) interferometric principle that is capable of measuring the rapid pressure changes in a blast event. The blast event in the experiment was generated by a starter pistol blank firing at close range, which produced a more realistic wave profile compared to using compressed air driven shock tubes. To the authors' knowledge, it is also the first study to utilize fiber optic pressure sensors to measure the ballistics shock wave of a pistol firing. The results illustrated that the fiber optic pressure sensor has a rise time of 200 ns which demonstrated that the sensor has ability to capture the dynamic pressure transient during a blast event. Moreover, the resonant frequency of the sensor was determined to be 4.11 MHz, which agrees well with the specific designed value.

  5. An APL function for modeling p-wave induced liquefaction

    NASA Astrophysics Data System (ADS)

    Doehring, Donald O.; Charlie, Wayne A.; Veyera, George E.

    This paper presents an APL function that models particle acceleration, velocity, displacement, and porewater pressure responses induced by the passage of compressional waves through water-saturated soil. Inputs to the function include: mass of soil elements, boundary conditions, spring constants, damping ratio, forces applied to the first element, threshold strain and a time increment. Output closely approximates the results of laboratory and field measurements of this phenomenon.

  6. Air pressure waves from Mount St. Helens eruptions

    SciTech Connect

    Reed, J.W.

    1987-10-20

    Weather station barograph records as well as infrasonic recordings of the pressure wave from the Mount St. Helens eruption of May 18, 1980, have been used to estimate an equivalent explosion airblast yield for this event. Pressure amplitude versus distance patterns in various directions compared with patterns from other large explosions, such as atmospheric nuclear tests, the Krakatoa eruption, and the Tunguska comet impact, indicate that the wave came from an explosion equivalent of a few megatons of TNT. The extent of tree blowdown is considerably greater than could be expected from such an explosion, and the observed forest damage is attributed to outflow of volcanic material. The pressure-time signature obtained at Toledo, Washington, showed a long, 13-min duration negative phase as well as a second, hour-long compression phase, both probably caused by ejacta dynamics rather than standard explosion wave phenomenology. The peculiar audibility pattern, with the blast being heard only at ranges beyond about 100 km, is explicable by finite amplitude propagation effects. Near the source, compression was slow, taking more than a second but probably less than 5 s, so that it went unnoticed by human ears and susceptible buildings were not damaged. There was no damage as Toledo (54 km), where the recorded amplitude would have broken windows with a fast compression. An explanation is that wave emissions at high elevation angles traveled to the upper stratosphere, where low ambient air pressures caused this energetic pressure oscillation to form a shock wave with rapid, nearly instantaneous compression. Atmospheric refraction then returned part of this wave to ground level at long ranges, where the fast compressions were clearly audible. copyright American Geophysical Union 1987

  7. Measurement of Blast Waves from Bursting Pressureized Frangible Spheres

    NASA Technical Reports Server (NTRS)

    Esparza, E. D.; Baker, W. E.

    1977-01-01

    Small-scale experiments were conducted to obtain data on incident overpressure at various distances from bursting pressurized spheres. Complete time histories of blast overpressure generated by rupturing glass spheres under high internal pressure were obtained using eight side-on pressure transducers. A scaling law is presented, and its nondimensional parameters are used to compare peak overpressures, arrival times, impulses, and durations for different initial conditions and sizes of blast source. The nondimensional data are also compared, whenever possible, with results of theoretical calculations and compiled data for Pentolite high explosive. The scaled data are repeatable and show significant differences from blast waves generated by condensed high-explosives.

  8. Pressure induced ageing of polymers

    NASA Technical Reports Server (NTRS)

    Emri, I.; Knauss, W. G.

    1988-01-01

    The nonlinearly viscoelastic response of an amorphous homopolymer is considered under aspects of time dependent free volume behavior. In contrast to linearly viscoelastic solids, this model couples shear and volume deformation through a shift function which influences the rate of molecular relaxation or creep. Sample computations produce all those qualitative features one observes normally in uniaxial tension including the rate dependent formation of a yield point as a consequence of the history of an imposed pressure.

  9. Relationship between high-order non-linearity of random waves and wave pressures acting on offshore breakwaters

    NASA Astrophysics Data System (ADS)

    Kashima, Hiroaki

    2016-04-01

    In the design of breakwaters, the wave pressures out of the surf zone are estimated by the maximum wave height which corresponds to the 1.8 times of significant wave height according to Rayleigh theory. On the other hand, the nonlinear four-wave interactions can lead to a significant enhancement of occurrence frequency of extreme waves which have more than twice the significant wave height. It is necessary to appropriately evaluate the effects of the deviation from Rayleigh theory on the wave pressures acting on offshore breakwaters under extreme wave conditions. In this study, the physical experiments in a wave tank were conducted to understand the effect of the occurrence frequency of the maximum wave height on the wave pressures acting on offshore breakwaters. In our analysis, the wave pressures acting on breakwaters were estimated by using three kinds of the maximum wave heights. The first and second are the maximum wave height and the 1.8 times of significant wave height obtained from the physical experiments. The last is the maximum wave height given by the Japanese design method for breakwaters taking into account the nonlinear wave shoaling effects. As a result, the occurrence frequency of the maximum wave height given by the physical experiments is in a good agreement with the high-order nonlinear theory by Mori and Janssen (2006) and there is the deviation from the Rayleigh theory not only offshore but also in the intermediate depth. Moreover, the wave pressures using the maximum wave height are widely distributed to the designed value of the wave pressure while the dispersion of the wave pressures using the 1.8 times of the significant wave height is small. As the non-linearity of the waves becomes stronger, the wave pressures tend to exceed the designed value of the wave pressure on the average through the behavior of the maximum wave height depending on the kurtosis which is the indicator of the high-order nonlinear interactions. Finally, it is

  10. Internal wave-turbulence pressure above sloping sea bottoms

    NASA Astrophysics Data System (ADS)

    Haren, Hans

    2011-12-01

    An accurate bottom pressure sensor has been moored at different sites varying from a shallow sea strait via open ocean guyots to a 1900 m deep Gulf of Mexico. All sites show more or less sloping bottom topography. Focusing on frequencies (σ) higher than tidal, the pressure records are remarkably similar, to within the 95% statistical significance bounds, in the internal gravity wave continuum (IWC) band up to buoyancy frequency N. The IWC has a relatively uniform spectral slope: log(P(σ)) = -αlog(σ), α = 2 ± 1/3. The spectral collapse is confirmed from independent internal hydrostatic pressure estimate, which suggests a saturated IWC. For σ > N, all pressure-spectra transit to a bulge that differs in magnitude. This bulge is commonly attributed to long surface waves. For the present data it is suggested to be due to stratified turbulence-internal wave coupling, which is typically large over sloping topography. The bulge drops off at a more or less common frequency of 2-3 × 10-2 Hz, which is probably related with typical turbulent overturning scales.

  11. Propagation of waves in a medium with high radiation pressure

    NASA Technical Reports Server (NTRS)

    Bisnovatyy-Kogan, G. S.; Blinnikov, S. I.

    1979-01-01

    The propagation and mutual transformation of acoustic and thermal waves are investigated in media with a high radiative pressure. The equations of hydrodynamics for matter and the radiative transfer equations in a moving medium in the Eddington approximation are used in the investigation. Model problems of waves in a homogeneous medium with an abrupt jump in opacity and in a medium of variable opacity are presented. The characteristic and the times of variability are discussed. Amplitude for the brightness fluctuations for very massive stars are discussed.

  12. Pressure Fluctuations Induced by a Hypersonic Turbulent Boundary Layer

    NASA Technical Reports Server (NTRS)

    Duan, Lian; Choudhari, Meelan M.; Zhang, Chao

    2016-01-01

    Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a spatially-developed Mach 5.86 turbulent boundary layer. The unsteady pressure field is analyzed at multiple wall-normal locations, including those at the wall, within the boundary layer (including inner layer, the log layer, and the outer layer), and in the free stream. The statistical and structural variations of pressure fluctuations as a function of wall-normal distance are highlighted. Computational predictions for mean velocity pro les and surface pressure spectrum are in good agreement with experimental measurements, providing a first ever comparison of this type at hypersonic Mach numbers. The simulation shows that the dominant frequency of boundary-layer-induced pressure fluctuations shifts to lower frequencies as the location of interest moves away from the wall. The pressure wave propagates with a speed nearly equal to the local mean velocity within the boundary layer (except in the immediate vicinity of the wall) while the propagation speed deviates from the Taylor's hypothesis in the free stream. Compared with the surface pressure fluctuations, which are primarily vortical, the acoustic pressure fluctuations in the free stream exhibit a significantly lower dominant frequency, a greater spatial extent, and a smaller bulk propagation speed. The freestream pressure structures are found to have similar Lagrangian time and spatial scales as the acoustic sources near the wall. As the Mach number increases, the freestream acoustic fluctuations exhibit increased radiation intensity, enhanced energy content at high frequencies, shallower orientation of wave fronts with respect to the flow direction, and larger propagation velocity.

  13. Time-resolved wave profile measurements in copper to Megabar pressures

    SciTech Connect

    Chhabildas, L C; Asay, J R

    1981-01-01

    Many time-resolved techniques have been developed which have greatly aided in the understanding of dynamic material behavior such as the high pressure-dynamic strength of materials. In the paper, time-resolved measurements of copper (at shock-induced high pressures and temperatures) are used to illustrate the capability of using such techniques to investigate high pressure strength. Continuous shock loading and release wave profiles have been made in copper to 93 GPa using velocity interferometric techniques. Fine structure in the release wave profiles from the shocked state indicates an increase in shear strength of copper to 1.5 GPa at 93 GPa from its ambient value of 0.08 GPa.

  14. Air pressure waves from Mount St. Helens eruptions

    SciTech Connect

    Reed, J.W.

    1980-01-01

    Barograms from a number of National Weather Service stations were assembled for the May 18, 1980, eruption and compared to airblast wave propagations from large explosions. Wave amplitudes at 50 to 300 km distances were about what might be expected from a nuclear explosion of between 1 megaton and 10 megaton yield. Pressure-time signatures could not be resolved for the first compression phase, because of the slow paper recording speed. The 900 s negative phase duration was much too long for comparison with the negative phase of an explosion. Nevertheless, positive and negative amplitudes were about equal, as often observed at long distances from explosions. Calculations have been made for a simple finite amplitude propagation model. These show rough bounds on the source compression rate, to give the observed inaudible waves at least to 54 km distance, yet cause audibly rapid compression at Seattle, near 150 km, and beyond.

  15. Renal tissue damage induced by focused shock waves

    NASA Astrophysics Data System (ADS)

    Ioritani, N.; Kuwahara, M.; Kambe, K.; Taguchi, K.; Saitoh, T.; Shirai, S.; Orikasa, S.; Takayama, K.; Lush, P. A.

    1990-07-01

    Biological evidence of renal arterial wall damage induced by the microjet due to shock wave-cavitation bubble interaction was demonstrated in living dog kidneys. We also intended to clarify the mechanism of renal tissue damage and the effects of different conditions of shock wave exposure (peak pressure of focused area, number of shots, exposure rate) on the renal tissue damage in comparison to stone disintegration. Disruption of arterial wall was the most remarkable histological change in the focused area of the kidneys. This lesion appeared as if the wall had been punctured by a needle. Large hematoma formation in the renal parenchym, and interstitial hemorrhage seemed to be the results of the arterial lesion. This arterial disorder also led to ischemic necrosis of the tubules surrounding the hematoma. Micro-angiographic examination of extracted kidneys also proved such arterial puncture lesions and ischemic lesions. The number of shots required for model stone disintegration was not inversely proportional to peak pressure. It decreased markedly when peak pressure was above 700 bar. Similarly thenumber of shots for hematoma formation was not inversely proportional to peak pressure, however, this decreased markedly above 500 bar. These results suggested that a hematoma could be formed under a lower peak pressure than that required for stone disintegration.

  16. Free-surface wave-induced separation

    SciTech Connect

    Zhang, Z.J.; Stern, F.

    1996-09-01

    Free-surface wave-induced separation is studied for a surface-piercing NACA 0024 foil over a range of Froude numbers (0, .2, .37, .55) through computational fluid dynamics of the unsteady Reynolds-averaged Navier-Stokes and the continuity equations with the Baldwin-Lomax turbulence model, exact nonlinear kinematic and approximate dynamic free-surface boundary conditions, and a body/free-surface conforming grid. The flow conditions and uncertainty analysis are discussed. A topological rule for a surface-piercing body is derived and verified. Steady-flow results are presented and analyzed with regard to the wave and viscous flow and the nature of the separation.

  17. Gravitational waves induced by spinor fields

    NASA Astrophysics Data System (ADS)

    Feng, Kaixi; Piao, Yun-Song

    2015-07-01

    In realistic model building, spinor fields with various masses are present. During inflation, a spinor field may induce gravitational waves as a second order effect. In this paper, we calculate the contribution of a single massive spinor field to the power spectrum of primordial gravitational wave by using a retarded Green propagator. We find that the correction is scale invariant and of order H4/MP4 for arbitrary spinor mass mψ. Additionally, we also observe that when mψ≳H , the dependence of correction on mψ/H is nontrivial.

  18. Pressure-induced metallization of silane.

    PubMed

    Chen, Xiao-Jia; Struzhkin, Viktor V; Song, Yang; Goncharov, Alexander F; Ahart, Muhtar; Liu, Zhenxian; Mao, Ho-Kwang; Hemley, Russell J

    2008-01-08

    There is a great interest in electronic transitions in hydrogen-rich materials under extreme conditions. It has been recently suggested that the group IVa hydrides such as methane (CH(4)), silane (SiH(4)), and germane (GeH(4)) become metallic at far lower pressures than pure hydrogen at equivalent densities because the hydrogen is chemically compressed in group IVa hydride compounds. Here we report measurements of Raman and infrared spectra of silane under pressure. We find that SiH(4) undergoes three phase transitions before becoming opaque at 27-30 GPa. The vibrational spectra indicate the material transforms to a polymeric (framework) structure in this higher pressure range. Room-temperature infrared reflectivity data reveal that the material exhibits Drude-like metallic behavior above 60 GPa, indicating the onset of pressure-induced metallization.

  19. Narrowed Aortoseptal Angle Is Related to Increased Central Blood Pressure and Aortic Pressure Wave Reflection

    PubMed Central

    Olafiranye, Oladipupo; Ibrahim, Mediha; Kamran, Haroon; Venner-Jones, Kinda; McFarlane, Samy I.; Salciccioli, Louis; Lazar, Jason M.

    2012-01-01

    The left ventricular (LV) aortoseptal angle (ASA) decreases with age, and is associated with basal septal hypertrophy (septal bulge). Enhanced arterial pressure wave reflection is known to impact LV hypertrophy. We assessed whether ASA is related to central blood pressure (BP) and augmentation index (AI), a measure of the reflected pressure wave. We studied 75 subjects (age 62 ± 16 years; 66% female) who were referred for transthoracic echocardiography and had radial artery applanation tonometry within 24 h. Peripheral systolic BP (P-SBP), peripheral diastolic BP (P-DBP), and peripheral pulse pressure (P-PP) were obtained by sphygmomanometry. Central BPs (C-SBP, C-DBP, C-PP) and AI were derived from applanation tonometry. AI was corrected for heart rate (AI75). The basal septal wall thickness (SWT), mid SWT and ASA were measured using the parasternal long axis echocardiographic view. Mean ASA and AI75 were 117 ± 11° and 22 ± 11%, respectively. ASA correlated with AI75 (r = −0.31, p ≤ 0.01), C-SBP (r = −0.24, p = 0.04), C-PP (r = −0.29, p = 0.01), but only showed a trend towards significance with P-SBP (r = −0.2, p = 0.09) and P-PP (r = −0.21, p = 0.08). Interestingly, C-PP was correlated with basal SWT (r = 0.27, p = 0.02) but not with mid SWT (r = 0.19, p = 0.11). On multivariate linear regression analysis, adjusted for age, gender, weight, and mean arterial pressure, AI75 was an independent predictor of ASA (p = 0.02). Our results suggest that a narrowed ASA is related to increased pressure wave reflection and higher central BP. Further studies are needed to determine whether narrowed LV ASA is a cause or consequence of enhanced wave reflection and whether other factors are involved. PMID:22969773

  20. Exercise central (aortic) blood pressure is predominantly driven by forward traveling waves, not wave reflection.

    PubMed

    Schultz, Martin G; Davies, Justin E; Roberts-Thomson, Phillip; Black, J Andrew; Hughes, Alun D; Sharman, James E

    2013-07-01

    Exercise hypertension independently predicts cardiovascular mortality, although little is known about exercise central hemodynamics. This study aimed to determine the contribution of arterial wave travel and aortic reservoir characteristics to central blood pressure (BP) during exercise. We hypothesized that exercise central BP would be principally related to forward wave travel and aortic reservoir function. After routine diagnostic coronary angiography, invasive pressure and flow velocity were recorded in the ascending aorta via sensor-tipped intra-arterial wires in 10 participants (age, 55±10 years; 70% men) free of coronary artery disease with normal left ventricular function. Measures were recorded at baseline and during supine cycle ergometry. Using wave intensity analysis, dominant wave types throughout the cardiac cycle were identified (forward and backward, compression, and decompression), and aortic reservoir and excess pressure were calculated. Central systolic BP increased significantly with exercise (Δ=19±12 mm Hg; P<0.001). This was associated with increases in systolic forward compression waves (Δ=12×10(6)±17×10(6) W·m(-2)·s(-1); P=0.045) and forward decompression waves in late systole (Δ=9×10(6)±6×10(6) W·m(-2)·s(-1); P<0.001). Despite significant augmentation in BP (Δ=9±6 mm Hg; P=0.002), reflected waves did not increase in magnitude (Δ=-1×10(6)±3×10(6) W·m(-2)·s(-1); P=0.2). Excess pressure rose significantly with exercise (Δ=16±9 mm Hg; P<0.001), and reservoir pressure integral fell (Δ=-5×10(5)±5×10(5) Pa·s; P=0.010). Change in reflection coefficient negatively correlated with change in central systolic BP (r=-0.68; P=0.03). We conclude that elevation of exercise central BP is principally because of increases in aortic forward traveling waves generated by left ventricular ejection. These findings have relevance to understanding central BP waveform morphology and pathophysiology of exercise hypertension.

  1. Shock pressures induced in condensed matter by laser ablation.

    PubMed

    Swift, Damian C; Tierney, Thomas E; Kopp, Roger A; Gammel, J Tinka

    2004-03-01

    The Trident laser was used to induce shock waves in samples of solid elements, with atomic numbers ranging from Be to Au, using pulses of 527 nm light around 1 ns long with irradiances of the order of 0.1 to 10 PW/m(2). States induced by the resulting ablation process were investigated using laser Doppler velocimetry to measure the velocity history of the opposite surface. By varying the energy in the laser pulse, relations were inferred between the irradiance and the induced pressure. For samples in vacuo, an irradiance constant in time does not produce a constant pressure. Radiation hydrodynamics simulations were used to investigate the relationship between the precise pulse shape and the pressure history. In this regime of time and irradiance, it was possible to reproduce the experimental data to within their uncertainty by including conductivity-dependent deposition of laser energy, heat conduction, gray radiation diffusion, and three temperature hydrodynamics in the treatment of the plasma, with ionizations calculated using the Thomas-Fermi equation. States induced in the solid sample were fairly insensitive to the details of modeling in the plasma, so Hugoniot points may be estimated from experiments of this type given a reasonable model of the plasma. More useful applications include the generation of dynamic loading to investigate compressive strength and phase transitions, and for sample recovery.

  2. Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse

    NASA Astrophysics Data System (ADS)

    Shen, X. C.; Shi, Q. Q.; Zong, Q.-G.; Tian, A. M.; Nowada, M.; Sun, W. J.; Zhao, H. Y.; Hudson, M. K.; Wang, H. Z.; Fu, S. Y.; Pu, Z. Y.

    2017-02-01

    Ultralow frequency (ULF) waves play an important role in the transport of the solar wind energy to the magnetosphere. In this paper, we present a ULF wave event in the dayside magnetosphere which shows a sudden decrease in frequency from 3.1 to 2.3 mHz around 0756 UT on 11 January 2010, when a solar wind dynamic pressure drop (from ˜5 to ˜2 nPa) was observed simultaneously. The wave exits globally. The phase differences between electric and magnetic fields indicate that the compressional mode wave is standing before and after the wave frequency decrease. This result suggests that the ULF wave should be associated with a cavity mode and the frequency decrease might be induced by the change of the cavity size. A theoretical calculation was made to estimate the cavity mode frequency. The calculated wave frequency before/after the negative impulse is 3.8/2.6 mHz, which is consistent with the observations.

  3. Pressure wave generated by the Mount St. Helens eruption

    SciTech Connect

    Banister, J.B.

    1984-06-20

    Histories of the air pressure wave radiated from the eruption of Mount St. Helens on May 18, 1980, were calculated for two models of the eruption cloud expansion. The first considered the wave radiated from an accelerated plane surface, while the second examined the wave radiated from an expanding hemisphere. Two histories of eruption cloud motion based on photographs were used. Peak positive overpressures were about the same for these cloud motion histories of expansion into a hemisphere was assumed. If an accelerated planar source model was used, the peak positive pressures have again about the same value in east and west direction, but values are about half in the north and south direction. Observed peak overpressures at microbarograph stations are somewhat higher than the calculated with the most marked departures at the greater surface ranges. These observed overpressures may have been about half the correct values, however. Microbarograph records show a weaker rarefaction than calculated histories or none at all. This can be explained, in part, by a lack of a real motion coherence in the slowing eruption cloud. If it is also possible the net ash cloud volume increased considerably after its vertical growth ceased and weakened the negative phase as well as lengthening the positive phase.

  4. Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves

    SciTech Connect

    IceCube Collaboration; Klein, Spencer

    2009-06-04

    We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at {approx}5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.

  5. Pressure-induced transformations in molecular crystals

    SciTech Connect

    Taylor, R.D.; Hearne, G.R. |; Pasternak, M.P.

    1995-09-01

    A review is given on the unique features of the Moessbauer spectroscopy (MS) which by virtue of the quadrupole interaction and the lattice dynamics allows one to characterize some structural properties in the pressure-induced amorphous state of molecular crystals. Experiments were performed in GeI{sub 4}, SnI{sub 4} and SnBr{sub 4} by means of {sup 119}Sn and {sup 129}I MS with pressures to 35 GPa at cryogenic temperatures using diamond anvil cells.

  6. An Analytical Model of Wave-Induced Longshore Current Based on Power Law Wave Height Decay.

    DTIC Science & Technology

    1988-01-01

    34I ANALYtTICAL MODEL OF NAVE-INDUCED LON6SHORE CURRENT BASED ON PONE* LAW.. (U) COASTAL ENG INEERING RESEAKNH CENTER VICKSBURG NS J N SMITH ET AL...j . - .L .V . : ; * AN ANALYTICAL MODEL OF WAVE-INDUCED ~ z * LONGSHORE CURRENT BASED ON POWER LAW * - WAVE HEIGHT DECAY by Jane McKee...I_ I IF 31592 11. TITLE (Include Security Classfication) • An Analytical Model of Wave-Induced Longshore Current Based on Power Law . Wave

  7. Coastal Trapped Waves, Alongshore Pressure Gradients, and the California Undercurrent

    DTIC Science & Technology

    2014-01-01

    REPORJ Db.’XE IDD-MM-YYYYj 06-03-2014 2. REPORT TYPE Journal Article 4 . TITLE AND SUBTITLE Coastal Trapped Waves, Alongshore Pressure Gradients...8217 ’ 1 A^rl b) )1^N Iff^ 0.2 0.1 Z 0 V -0.1 -0.2 4 % ^ ^ w ! , : 1 1 CCMP 10m wind (m/s) 128 126 124 122 120...region 30 - 4 ’) N, 135<>-115 W (Tigs. la.b). and hindcast results aiv pre- sented for the year 20(15. The model is forced with atmospheric products

  8. Nonlinear shock acceleration. III - Finite wave velocity, wave pressure, and entropy generation via wave damping

    NASA Technical Reports Server (NTRS)

    Eichler, D.

    1985-01-01

    The nonlinear theory of shock acceleration developed in earlier papers, which treated the waves as being completely frozen into the fluid, is generalized to include wave dynamics. In the limit where damping keeps the wave amplitude small, it is found that a finite phase velocity (V sub ph) of the scattering waves through the background fluid, tempers the acceleration generated by high Mach number shocks. Asymptotic spectra proportional to 1/E sq are possible only when the ratio of wave velocity to shock velocity is less than 0.13. For a given asymptotic spectrum, the efficiency of relativistic particle production is found to be practically independent of the value of V sub ph, so that earlier results concerning its value remain valid for finite V sub ph. In the limit where there is no wave damping, it is shown that for modest Alfven Mach numbers, approximately greater than 4 and less than 6, the magnetic field is amplified by the energetic particles to the point of being in rough equipartition with them, as models of synchrotron emission frequently take the field to be. In this case, the disordering and amplification of field energy may play a major role in the shock transition.

  9. Tunnel pressure waves - A smartphone inquiry on rail travel

    NASA Astrophysics Data System (ADS)

    Müller, Andreas; Hirth, Michael; Kuhn, Jochen

    2016-02-01

    When traveling by rail, you might have experienced the following phenomenon: The train enters a tunnel, and after some seconds a noticeable pressure change occurs, as perceived by your ears or even by a rapid wobbling of the train windows. The basic physics is that pressure waves created by the train travel down the tunnel, are reflected at its other end, and travel back until they meet the train again. Here we will show (i) how this effect can be well understood as a kind of large-scale outdoor case of a textbook paradigm, and (ii) how, e.g., a prediction of the tunnel length from the inside of a moving train on the basis of this model can be validated by means of a mobile phone measurement.

  10. Simulations of nonlinear continuous wave pressure fields in FOCUS

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaofeng; Hamilton, Mark F.; McGough, Robert J.

    2017-03-01

    The Khokhlov - Zabolotskaya - Kuznetsov (KZK) equation is a parabolic approximation to the Westervelt equation that models the effects of diffraction, attenuation, and nonlinearity. Although the KZK equation is only valid in the far field of the paraxial region for mildly focused or unfocused transducers, the KZK equation is widely applied in medical ultrasound simulations. For a continuous wave input, the KZK equation is effectively modeled by the Bergen Code [J. Berntsen, Numerical Calculations of Finite Amplitude Sound Beams, in M. F. Hamilton and D. T. Blackstock, editors, Frontiers of Nonlinear Acoustics: Proceedings of 12th ISNA, Elsevier, 1990], which is a finite difference model that utilizes operator splitting. Similar C++ routines have been developed for FOCUS, the `Fast Object-Oriented C++ Ultrasound Simulator' (http://www.egr.msu.edu/˜fultras-web) to calculate nonlinear pressure fields generated by axisymmetric flat circular and spherically focused ultrasound transducers. This new routine complements an existing FOCUS program that models nonlinear ultrasound propagation with the angular spectrum approach [P. T. Christopher and K. J. Parker, J. Acoust. Soc. Am. 90, 488-499 (1991)]. Results obtained from these two nonlinear ultrasound simulation approaches are evaluated and compared for continuous wave linear simulations. The simulation results match closely in the farfield of the paraxial region, but the results differ in the nearfield. The nonlinear pressure field generated by a spherically focused transducer with a peak surface pressure of 0.2MPa radiating in a lossy medium with β = 3.5 is simulated, and the computation times are also evaluated. The nonlinear simulation results demonstrate acceptable agreement in the focal zone. These two related nonlinear simulation approaches are now included with FOCUS to enable convenient simulations of nonlinear pressure fields on desktop and laptop computers.

  11. Application of monochromatic ocean wave forecasts to prediction of wave-induced currents

    NASA Technical Reports Server (NTRS)

    Poole, L. R.

    1975-01-01

    The use of monochromatic wind-wave forecasts in prediction of wind-wave-induced currents was assessed. Currents were computed for selected combinations of wind conditions by using a spectrum approach which was developed by using the Bretschneider wave spectrum for partially developed wind seas. These currents were compared with currents computed by using the significant and average monochromatic wave parameters related to the Bretschneider spectrum. Results indicate that forecasts of significant wave parameters can be used to predict surface wind-wave-induced currents. Conversion of these parameters to average wave parameters can furnish reasonable estimates of subsurface current values.

  12. Microcantilever Actuation by Laser Induced Photoacoustic Waves

    PubMed Central

    Gao, Naikun; Zhao, Dongfang; Jia, Ran; Liu, Duo

    2016-01-01

    We present here a combined theoretical and experimental investigation on effective excitation of microcantilever by using photoacoustic waves. The photoacoustic waves arose from a vibrating Al foil induced by an intensity-modulated laser. We demonstrate that, superior to photothermal excitation, this new configuration avoids direct heating of the microcantilever, thus minimizing undesired thermal effects on the vibration of microcantilever, while still keeps the advantage of being a remote, non-contact excitation method. We also measured the vibration amplitude of the microcantilever as a function of distance between the microcantilever and the Al foil and found that the amplitudes decay gradually according to the inverse distance law. This method is universal and can be adopted in bio-microelectromechanical systems (BioMEMs) for the detection of small signals where detrimental thermal effects must be avoided. PMID:26814360

  13. On the Generation of Multiple Atmospheric Pressure Waves Observed During Violent Volcanic Eruptions.

    NASA Astrophysics Data System (ADS)

    Medici, E. F.; Waite, G. P.

    2015-12-01

    One or more atmospheric pressure waves followed by a supersonic jet may be generated during the over pressurized vapor-solid-liquid mixture ejection of a violent volcanic eruption. The source of these multiple atmospheric pressure waves could have different origins. Among the physical mechanisms that could explain these behaviors are pulsating eruptions, the dynamics of shock waves, coupled pressure wave-supersonic jet interaction, or a combination of all these factors. In order to elucidate the causes of these complex fluid flow dynamics, a series of analog volcanic eruption experiments using an atmospheric shock tube were performed. During the testing, single and multiple pressure waves and the subsequent supersonic jet were generated. The controlled laboratory conditions enable studies of the most relevant variables potentially responsible for the formation of the multiple pressure waves. The tests were performed using dry, compressed nitrogen at standard room temperature that was free of particles. Yet, under this idealization of a real volcanic eruption, multiple pressure waves were observed on the high-speed video imaging and recorded on the pressure transducer. The amount of energy being released on each test was varied to achieve different discharge dynamics and the formation of single and multiple pressure waves. The preliminary experimental observations indicate a coupled pressure wave-jet interaction as source of multiple pressure waves.

  14. Field-induced spin-density wave in (TMTSF)2NO3

    NASA Astrophysics Data System (ADS)

    Vignolles, David; Audouard, Alain; Nardone, Marc; Brossard, Luc; Bouguessa, Sabrina; Fabre, Jean-Marc

    2005-01-01

    Interlayer magnetoresistance of the Bechgaard salt (TMTSF)2NO3 is investigated up to 50 T under pressures of a few kilobars. This compound, the Fermi surface of which is quasi-two-dimensional at low temperature, is a semimetal under pressure. Nevertheless, a field-induced spin-density wave is evidenced at 8.5 kbars above ˜20T . This state is characterized by a drastically different spectrum of the quantum oscillations compared to the low-pressure spin-density wave state.

  15. Estimating explosive performance from laser-induced shock waves

    NASA Astrophysics Data System (ADS)

    Gottfried, Jennifer

    2015-06-01

    A laboratory-scale method for predicting explosive performance (e.g., detonation velocity and pressure) based on milligram quantities of material is currently being developed. This technique is based on schlieren imaging of the shock wave generated in air by the formation of a laser-induced plasma on the surface of an energetic material. A large suite of pure and composite conventional energetic materials has been tested. Based on the observed linear correlation between the laser-induced shock velocity and the measured performance from full-scale detonation testing, this method is a potential screening tool for the development of new energetic materials and formulations prior to detonation testing. Recent results on the extension of this method to metal-containing energetic materials will be presented.

  16. Optical Estimation of Depth Induced Wave Breaking Distributions over Complex Bathymetry

    NASA Astrophysics Data System (ADS)

    Keen, A. S.; Holman, R. A.

    2012-12-01

    Parametric depth-induced-breaking dissipation models have shown great skill at predicting time averaged wave heights across the surf zone. First proposed by Battjes & Janssen (1978), these models balance the incoming wave energy flux with a roller dissipation term. This roller dissipation term is estimated by calculating the dissipation for one characteristic broken wave and then multiplying this quantity by the fraction of broken waves. To describe the fraction of broken waves, a typical assumption asserts that wave heights are nearly Rayleigh distributed [Thornton & Guza (1983)] allowing a sea state to be described by only a few parameters. While many experiments have validated the cross shore wave height profiles, few field experiments have been performed to analyze the probability distribution of breaking wave heights over a barred beach profile. The goal of the present research is to determine the distribution of broken and unbroken wave heights across a natural barred beach profile. Field data collected during the Surf Zone Optics experiment (a Multi-disciplinary University Research Initiative) in Duck, North Carolina, consisted of an array of in-situ pressure sensors and optical remote sensing cameras. Sea surface elevation time series from the in-situ pressure sensors are used here to resolve wave height distributions at multiple locations across the surf zone. Breaking wave height distributions are resolved based upon a combination of the pressure sensor and optically based breaker detection algorithm. Since breaking is easily able to be tracked by video imaging, breaking waves are flagged in the sea surface elevation series and binned into a broken wave height distribution. Results of this analysis are compared with model predictions based upon the Battjes & Janssen (1978), Thornton & Guza (1983) and Janssen & Battjes (2007) models to assess the validity of each wave height distribution model.

  17. A Experimental Study of Fluctuating Pressure Loads Beneath Swept Shock Wave/boundary Layer Interactions

    NASA Astrophysics Data System (ADS)

    Garg, Sanjay

    An experimental research program providing basic knowledge and establishing a database on the fluctuating pressure loads produced on aerodynamic surfaces beneath three-dimensional shock wave/boundary layer interactions is described. 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 10 ^circ to 20^circ at freestream Mach numbers of 3 and 4 produce a variety of interaction strengths from weak to very strong. Miniature pressure transducers flush-mounted in the flat plate have been used to measure interaction-induced wall pressure fluctuations. The distributions of properties of the pressure fluctuations, such as their rms level, amplitude distribution and power spectra, are also determined. Measurements have been made for the first time in the aft regions of these interactions, revealing fluctuating pressure levels as high as 155 dB, which places them in the category of significant aeroacoustic load generators. The fluctuations near the foot of the fin are dominated by low frequency (0-5 kHz) components, and are caused by a previously unrecognized random motion of the primary attachment line. This phenomenon is probably intimately linked to the unsteadiness of the separation shock at the start of the interaction. The characteristics of the pressure fluctuations are explained in light of the features of the interaction flowfield. In particular, physical mechanisms responsible for the generation of high levels of surface pressure fluctuations are proposed based on the results of the study. The unsteadiness of the flowfield of the surface is also examined via a novel, non-intrusive optical technique. Results show that the entire shock structure generated by the interaction undergoes relatively low-frequency oscillations.

  18. Effect of focusing conditions on laser-induced shock waves at titanium-water interface.

    PubMed

    Nath, Arpita; Khare, Alika

    2011-07-01

    The spatial and temporal evolution of laser-induced shock waves at a titanium-water interface was analyzed using a beam deflection setup. The focusing conditions of the source laser were varied, and its effect onto the dynamics of shock waves was elucidated. For a tightly focused condition, the speed of the shock wave was ~6.4 Km/s, whereas for a defocused condition the velocities reduced to <3 km/s at the vicinity of the titanium-water interface. When the laser is focused a few millimeters above the target, i.e., within the water, the emission of dual shock waves was observed toward the rear side of the focal volume. These shock waves originate from the titanium-water interface as well as from the pure water breakdown region, respectively. The shock wave pressure is estimated from the shock wave velocity using the Newton's second law across a shock wave discontinuity. The shock wave pressure for a tightly focused condition was 18 GPa, whereas under a defocused condition the pressure experienced was ≤1 GPa in the proximity of target.

  19. Effect of focusing conditions on laser-induced shock waves at titanium-water interface

    SciTech Connect

    Nath, Arpita; Khare, Alika

    2011-07-01

    The spatial and temporal evolution of laser-induced shock waves at a titanium-water interface was analyzed using a beam deflection setup. The focusing conditions of the source laser were varied, and its effect onto the dynamics of shock waves was elucidated. For a tightly focused condition, the speed of the shock wave was {approx}6.4 Km/s, whereas for a defocused condition the velocities reduced to <3 km/s at the vicinity of the titanium-water interface. When the laser is focused a few millimeters above the target, i.e., within the water, the emission of dual shock waves was observed toward the rear side of the focal volume. These shock waves originate from the titanium-water interface as well as from the pure water breakdown region, respectively. The shock wave pressure is estimated from the shock wave velocity using the Newton's second law across a shock wave discontinuity. The shock wave pressure for a tightly focused condition was 18 GPa, whereas under a defocused condition the pressure experienced was {<=}1 GPa in the proximity of target.

  20. Mass Spectrometry of Atmospheric Pressure Surface Wave Discharges

    NASA Astrophysics Data System (ADS)

    Ridenti, M. A.; Souza-Corrêa, J. A.; Amorim, J.

    2016-05-01

    By applying mass spectrometry techniques, we carried out measurements of ionic mass spectrum and their energy distribution in order to investigate an atmospheric argon discharge by using a surfatron surface-wave device. The mass and energy distribution measurements were performed with fixed flow rate (2.5 SLM) of pure argon gas (99.999%) and different Ar-O2 gas mixture compositions (99-1, 98-2 and 97-3). The mass spectra and energy distributions were recorded for Ar+, O+, O+ 2, N+ and N2 +. The axial distribution profiles of ionic mass and their energy were obtained for different experimental conditions as a function of the plasma length. The results showed that the peak of the positive ion energy distributions shifted to higher energies and also that the distribution width increased as the distance between the sampling orifice and the launcher gap was increased. It was also found that under certain experimental conditions the ion flux of atomic species were higher than the ion flux of their diatomic counterpart. The motivation of this study was to obtain a better understanding of a surface wave discharge in atmospheric pressure that may play a key role on new second generation biofuel technologies.

  1. Intraluminal bubble dynamics induced by lithotripsy shock wave

    NASA Astrophysics Data System (ADS)

    Song, Jie; Bai, Jiaming; Zhou, Yufeng

    2016-12-01

    Extracorporeal shock wave lithotripsy (ESWL) has been the first option in the treatment of calculi in the upper urinary tract since its introduction. ESWL-induced renal injury is also found after treatment and is assumed to associate with intraluminal bubble dynamics. To further understand the interaction of bubble expansion and collapse with the vessel wall, the finite element method (FEM) was used to simulate intraluminal bubble dynamics and calculate the distribution of stress in the vessel wall and surrounding soft tissue during cavitation. The effects of peak pressure, vessel size, and stiffness of soft tissue were investigated. Significant dilation on the vessel wall occurs after contacting with rapid and large bubble expansion, and then vessel deformation propagates in the axial direction. During bubble collapse, large shear stress is found to be applied to the vessel wall at a clinical lithotripter setting (i.e. 40 MPa peak pressure), which may be the mechanism of ESWL-induced vessel rupture. The decrease of vessel size and viscosity of soft tissue would enhance vessel deformation and, consequently, increase the generated shear stress and normal stresses. Meanwhile, a significantly asymmetric bubble boundary is also found due to faster axial bubble expansion and shrinkage than in radial direction, and deformation of the vessel wall may result in the formation of microjets in the axial direction. Therefore, this numerical work would illustrate the mechanism of ESWL-induced tissue injury in order to develop appropriate counteractive strategies for reduced adverse effects.

  2. Non-gyrotropic pressure anisotropy induced by velocity shear.

    NASA Astrophysics Data System (ADS)

    Tenerani, A.; Del Sarto, D.; Pegoraro, F.; Califano, F.

    2015-12-01

    We discuss how, in a collisionless magnetized plasma, a sheared velocity field may lead to the anisotropization of an initial Maxwellian state. By including the full pressure tensor dynamics in a fluid plasma model, we show, analytically and numerically, that a sheared velocity field makes an initial isotropic state anisotropic and non-gyrotropic [1], i.e., makes the plasma pressure tensor anisotropic also in the plane perpendicular to the magnetic field. The propagation of transverse magneto-elastic waves in the anisotropic plasma affects the process of formation of a non-gyrotropic pressure and can lead to its spatial filamentation. This plasma dynamics implies in particular that isotropic MHD equilibria cease to be equilibria in presence of a stationary sheared flow. Similarly, in the case of turbulence, where small-scale spatial inhomogeneities are naturally developed during the direct cascade, we may expect that isotropic turbulent states are not likely to exist whenever a full pressure tensor evolution is accounted for. These results may be relevant to understanding the agyrotropic pressure configurations which are well documented in solar wind measurements and possibly correlated to plasma flows (see e.g. Refs.[2,3]), and which have also been measured in Vlasov simulations of Alfvenic turbulence [4]. [1] D. Del Sarto, F. Pegoraro, F. Califano, "Pressure anisotropy and small spatial scales induced by a velocity shear", http://arxiv.org/abs/1507.04895 [2] H.F. Astudillo, E. Marsch, S. Livi, H. Rosenbauer, "TAUS measurements of non-gyrotropic distribution functions of solar wind alpha particles", AIP Conf. Proc. 328, 289 (1996). [3] A. Posner, M.W. Liemhon, T.H. Zurbuchen, "Upstream magnetospheric ion flux tube within a magnetic cloud: Wind/STICS", Geophys. Res. Lett. 30, (2003). [4] S. Servidio, F. Valentini, F. Califano, P. Veltri, "Local kinetic effects in Two-Dimensional Plasma Turbulence", Phys. Rev. Lett. 108, 045001 (2012).

  3. Cavitation inception by the backscattering of pressure waves from a bubble interface

    SciTech Connect

    Takahira, Hiroyuki Ogasawara, Toshiyuki Mori, Naoto Tanaka, Moe

    2015-10-28

    The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

  4. Poroelastic Wave Propagation With a 3D Velocity-Stress-Pressure Finite-Difference Algorithm

    NASA Astrophysics Data System (ADS)

    Aldridge, D. F.; Symons, N. P.; Bartel, L. C.

    2004-12-01

    Seismic wave propagation within a three-dimensional, heterogeneous, isotropic poroelastic medium is numerically simulated with an explicit, time-domain, finite-difference algorithm. A system of thirteen, coupled, first-order, partial differential equations is solved for the particle velocity vector components, the stress tensor components, and the pressure associated with solid and fluid constituents of the two-phase continuum. These thirteen dependent variables are stored on staggered temporal and spatial grids, analogous to the scheme utilized for solution of the conventional velocity-stress system of isotropic elastodynamics. Centered finite-difference operators possess 2nd-order accuracy in time and 4th-order accuracy in space. Seismological utility is enhanced by an optional stress-free boundary condition applied on a horizontal plane representing the earth's surface. Absorbing boundary conditions are imposed on the flanks of the 3D spatial grid via a simple wavefield amplitude taper approach. A massively parallel computational implementation, utilizing the spatial domain decomposition strategy, allows investigation of large-scale earth models and/or broadband wave propagation within reasonable execution times. Initial algorithm testing indicates that a point force density and/or moment density source activated within a poroelastic medium generates diverging fast and slow P waves (and possibly an S-wave)in accord with Biot theory. Solid and fluid particle velocities are in-phase for the fast P-wave, whereas they are out-of-phase for the slow P-wave. Conversions between all wave types occur during reflection and transmission at interfaces. Thus, although the slow P-wave is regarded as difficult to detect experimentally, its presence is strongly manifest within the complex of waves generated at a lithologic or fluid boundary. Very fine spatial and temporal gridding are required for high-fidelity representation of the slow P-wave, without inducing excessive

  5. A thoracic mechanism of mild traumatic brain injury due to blast pressure waves.

    PubMed

    Courtney, A C; Courtney, M W

    2009-01-01

    The mechanisms by which blast pressure waves cause mild-to-moderate traumatic brain injury (mTBI) are an open question. Possibilities include acceleration of the head, direct passage of the blast wave via the cranium, and propagation of the blast wave to the brain via a thoracic mechanism. The hypothesis that the blast pressure wave reaches the brain via a thoracic mechanism is considered in light of ballistic and blast pressure wave research. Ballistic pressure waves, caused by penetrating ballistic projectiles or ballistic impacts to body armor, can only reach the brain via an internal mechanism and have been shown to cause cerebral effects. Similar effects have been documented when a blast pressure wave has been applied to the whole body or focused on the thorax in animal models. While vagotomy reduces apnea and bradycardia due to ballistic or blast pressure waves, it does not eliminate neural damage in the brain, suggesting that the pressure wave directly affects the brain cells via a thoracic mechanism. An experiment is proposed which isolates the thoracic mechanism from cranial mechanisms of mTBI due to blast wave exposure. Results have implications for evaluating risk of mTBI due to blast exposure and for developing effective protection.

  6. On the Concordance of Static High Pressure Phase Transformation Data on Minerals With Shock Wave Data

    NASA Astrophysics Data System (ADS)

    de Carli, P. S.; El Goresy, A.; Xie, Z.; Sharp, T. G.

    2006-12-01

    About 50 years ago, shock wave researchers were confounded by the apparent rapidity of shock-induced phase transformations and invoked special mechanisms as an explanation. Some workers speculatively interpret shock wave data as indicative of very rapid reconstructive phase transformations of minerals at modest temperatures. The belief that kinetic effects are negligible has justified the use of microsecond duration shock recovery experiments to interpret much longer duration shock effects in terrestrial impact craters and in meteorites. Here we summarize the extensive evidence that phase transformations under shock compression are governed by the same kinetics as phase transitions under static compression. Hugoniot measurements on quartz and feldspars have been interpreted as indicating phase transitions to dense phases at pressures near 35 GPa. Release adiabat measurements imply that these phases persist on release of pressure down to about 7 GPa, below which there is expansion to a final density appropriate to a glass. Microsecond-duration shock recovery experiments support this interpretation; a low density amorphous phase (diaplectic glass) is recovered. A similar effect is observed in static compression experiments conducted at room temperature at a lower pressure, 12-15 GPa. The pressure difference is a kinetic effect; the transition requires higher shock pressures (implying higher shock temperatures) to run to completion on a microsecond time scale. Direct evidence for kinetic effects on the tectosilicate transformation is found in studies of naturally shocked meteorites that contain melt veins. When the melt veins solidify under pressure, the resultant mineralogy together with vein cooling calculations constrains the shock pressure-time history. In some samples, in which the shock pressure is constrained by vein mineralogy to a range of 17-25 Gpa, one may observe the presence of diaplectic glass in only near-vein regions heated by conduction from the vein

  7. Frequency and wavelength prediction of ultrasonic induced liquid surface waves.

    PubMed

    Mahravan, Ehsan; Naderan, Hamid; Damangir, Ebrahim

    2016-12-01

    A theoretical investigation of parametric excitation of liquid free surface by a high frequency sound wave is preformed, using potential flow theory. Pressure and velocity distributions, resembling the sound wave, are applied to the free surface of the liquid. It is found that for impinging wave two distinct capillary frequencies will be excited: One of them is the same as the frequency of the sound wave, and the other is equal to the natural frequency corresponding to a wavenumber equal to the horizontal wavenumber of the sound wave. When the wave propagates in vertical direction, mathematical formulation leads to an equation, which has resonance frequency equal to half of the excitation frequency. This can explain an important contradiction between the frequency and the wavelength of capillary waves in the two cases of normal and inclined interaction of the sound wave and the free surface of the liquid.

  8. Study on Pressure Wave Propagation in a Liquid Containing Spherical Bubbles in a Rectangular Duct

    NASA Astrophysics Data System (ADS)

    Kawahara, Junya; Watanabe, Masao; Kobayashi, Kazumichi

    2015-12-01

    Pressure wave propagation in a liquid containing several bubbles is numerically investigated. We simulate liner plane wave propagation in a liquid containing 10 spherical bubbles in a rectangular duct with the equation of motion for N spherical bubbles. The sound pressures of the reflected waves from the rigid walls are calculated by using the method of images. The result shows that the phase velocity of the pressure wave propagating in the liquid containing 10 spherical bubbles in the duct agrees well with the low-frequency speed of sound in a homogeneous bubbly liquid.

  9. An application of Love SH waves for the viscosity measurement of triglycerides at high pressures

    NASA Astrophysics Data System (ADS)

    Rostocki, A. J.; Siegoczyński, R. M.; Kiełczyński, P.; Szalewski, M.

    2010-03-01

    A new ultrasonic method of viscosity measurements at a high-pressure conditions has been presented. The method is based on the Love wave amplitude measurement. The same electronic setup as in the Bleustein-Gulyaev (B-G) wave method applied by the authors recently for a high-pressure measurement was adopted. The new sensors were made of metallic materials, which make them more reliable at high-pressure conditions. The method has been successfully applied for the viscosity measurement of some triglycerides at high-pressure conditions up to 1 GPa. The results have been compared with the earlier results obtained using B-G waves. This comparison has shown that Love wave method sensors are more reliable than B-G wave sensors and are also cheaper in fabrication, although the sensitivity of Love wave sensors is lower. During the measurement, the phase transitions in the investigated liquids were observed.

  10. Predicting S-wave velocities for unconsolidated sediments at low effective pressure

    USGS Publications Warehouse

    Lee, Myung W.

    2010-01-01

    Accurate S-wave velocities for shallow sediments are important in performing a reliable elastic inversion for gas hydrate-bearing sediments and in evaluating velocity models for predicting S-wave velocities, but few S-wave velocities are measured at low effective pressure. Predicting S-wave velocities by using conventional methods based on the Biot-Gassmann theory appears to be inaccurate for laboratory-measured velocities at effective pressures less than about 4-5 megapascals (MPa). Measured laboratory and well log velocities show two distinct trends for S-wave velocities with respect to P-wave velocity: one for the S-wave velocity less than about 0.6 kilometer per second (km/s) which approximately corresponds to effective pressure of about 4-5 MPa, and the other for S-wave velocities greater than 0.6 km/s. To accurately predict S-wave velocities at low effective pressure less than about 4-5 MPa, a pressure-dependent parameter that relates the consolidation parameter to shear modulus of the sediments at low effective pressure is proposed. The proposed method in predicting S-wave velocity at low effective pressure worked well for velocities of water-saturated sands measured in the laboratory. However, this method underestimates the well-log S-wave velocities measured in the Gulf of Mexico, whereas the conventional method performs well for the well log velocities. The P-wave velocity dispersion due to fluid in the pore spaces, which is more pronounced at high frequency with low effective pressures less than about 4 MPa, is probably a cause for this discrepancy.

  11. Vertical structure of pore pressure under surface gravity waves on a steep, megatidal, mixed sand-gravel-cobble beach

    NASA Astrophysics Data System (ADS)

    Guest, Tristan B.; Hay, Alex E.

    2017-01-01

    The vertical structure of surface gravity wave-induced pore pressure is investigated within the intertidal zone of a natural, steeply sloping, megatidal, mixed sand-gravel-cobble beach. Results from a coherent vertical array of buried pore pressure sensors are presented in terms of signal phase lag and attenuation as functions of oscillatory forcing frequency and burial depth. Comparison of the observations with the predictions of a theoretical poro-elastic bed response model indicates that the large observed phase lags and attenuation are attributable to interstitial trapped air. In addition to the dependence on entrapped air volume, the pore pressure phase and attenuation are shown to be sensitive to the hydraulic conductivity of the sediment, to the changing mean water depth during the tidal cycle, and to the redistribution/rearrangement of beach face material by energetic wave action during storm events. The latter result indicates that the effects on pore pressure of sediment column disturbance during instrument burial can persist for days to weeks, depending upon wave forcing conditions. Taken together, these results raise serious questions as to the practicality of using pore pressure measurements to estimate the kinematic properties of surface gravity waves on steep, mixed sand-gravel beaches.

  12. Supersonic shear wave elastography of in vivo pig kidney: influence of blood pressure, urinary pressure and tissue anisotropy.

    PubMed

    Gennisson, Jean-Luc; Grenier, Nicolas; Combe, Christian; Tanter, Mickaël

    2012-09-01

    The in vivo influence of renal anisotropy and of urinary and vascular pressure on elasticity values using ultrasonic supersonic shear wave elastography was studied in pigs. Experiments were conducted in agreement with the European Commission guidelines and directives of the French Research Ministry. Six kidneys in three pigs were studied in vivo. Elasticity of renal cortex and medulla was quantified through the shear modulus (μ) by using the supersonic shear imaging technique with an 8 MHz linear ultrasound probe. All measurements were done peroperatively both in the axis and perpendicular to the main axis of pyramids, in normal condition, after progressive increase of urinary pressure, and after renal artery and renal vein ligation. In normal conditions, cortical (C) and medullary (M) elasticity values were always higher when acquisitions were realized with the ultrasound main axis perpendicular to main pyramid axis (C(//): 7.7 ± 2.3 kPa; M(//): 8.7 ± 2.5 kPa) than parallel (C(⊥): 6.9 ± 1.4 kPa; M(⊥): 6.6 ± 2.3 kPa), demonstrating an effect of renal anisotropy. In renal cortex, two bands were separated, inner cortex showing higher elasticity values (IC(⊥): 8.1 ± 1.9 kPa) than outer cortex (OC(⊥): 6.9 ± 1.4 kPa). Renal artery and renal vein ligation induced a decrease and an increase of elasticity respectively. Parenchymal elasticity increased linearly with elevation of urinary pressure. Intrarenal elasticity values vary with tissue anisotropy and, with vascular and urinary pressure levels. These parameters have to be taken into account for interpretation of tissue changes. Separation of outer and inner cortex could be attributable to perfusion differences.

  13. Enhancement of terahertz wave generation from laser induced plasma

    SciTech Connect

    Xie Xu; Xu Jingzhou; Dai Jianming; Zhang, X.-C.

    2007-04-02

    It is well known that air plasma induced by ultrashort laser pulses emits broadband terahertz waves. The authors report the study of terahertz wave generation from the laser induced plasma where there is a preexisting plasma background. When a laser beam from a Ti:sapphire amplifier is used to generate a terahertz wave, enhancement of the generation is observed if there is another laser beam creating a plasma background. The enhancement of the terahertz wave amplitude lasts hundreds of picoseconds after the preionized background is created, with a maximum enhancement up to 250% observed.

  14. Numerical modeling and characterization of blast waves for application in blast-induced mild traumatic brain injury research

    NASA Astrophysics Data System (ADS)

    Phillips, Michael G.

    Human exposure to blast waves, including blast-induced traumatic brain injury, is a developing field in medical research. Experiments with explosives have many disadvantages including safety, cost, and required area for trials. Shock tubes provide an alternative method to produce free field blast wave profiles. A compressed nitrogen shock tube experiment instrumented with static and reflective pressure taps is modeled using a numerical simulation. The geometry of the numerical model is simplified and blast wave characteristics are derived based upon static and pressure profiles. The pressure profiles are analyzed along the shock tube centerline and radially away from the tube axis. The blast wave parameters found from the pressure profiles provide guidelines for spatial location of a specimen. The location could be based on multiple parameters and provides a distribution of anticipated pressure profiles experience by the specimen.

  15. Pressure-induced s-->d transfer and the equation of state of molybdenum

    NASA Astrophysics Data System (ADS)

    Godwal, B. K.; Jeanloz, Raymond

    1990-04-01

    The equations of state of crystalline (bcc) and liquid molybdenum are calculated to pressure-temperature conditions of 600 GPa and 14 000 K with use of the linear muffin-tin orbitals (LMTO) model and corrected rigid-ion sphere (CRIS) model. Our results agree with those of previous work in documenting a pressure-induced shift of electrons from 5s to 4d states, especially above 100 GPa. An analysis of ultrasonic and shock-wave measurements, along with our theoretical findings, documents that the compressibility of bcc Mo becomes enhanced at pressures of 100-200 GPa. The enhanced compression, and possibly an anomalous increase in rigidity, are caused by the pressure-induced s-->d transfer. Our study reinforces the use of the Mo equation of state as a calibration standard for ultrahigh-pressure static experiments and, in particular, for the ruby-fluorescence technique.

  16. Characteristic enhancement of blood pressure V-shaped waves in sinoaortic-denervated rats in a conscious and quiet state.

    PubMed

    Chang, Huan; Gu, Hong-Xia; Gong, Min; Han, Ji-Ju; Wang, Yun; Xia, Zuo-Li; Zhao, Xiao-Min

    2016-11-08

    A hemodynamic feature of chronic sinoaortic-denervated (SAD) rats is the increase in blood pressure variability (BPV) without significant changes in the average level of blood pressure (BP). The current study was designed to investigate the changes in BP V-shaped waves (V waves) in SAD rats. Sprague-Dawley (SD) rats were divided into 2 groups: SAD rats and sham-operated rats (n=13). Hemodynamics measurements were obtained in conscious, freely moving rats, four weeks after sinoaortic denervation or sham operation. V wave indices were evaluated in rats in both conscious and quiet states. Additionally, normal and high BPV was simulated by the production of V waves with different amplitudes. The results showed that the V wave amplitude was dramatically increased, with a significantly prolonged duration and reduced frequency in SAD rats. V wave BPV in SAD rats was significantly increased, though BP remained unchanged. The twenty-four hour BPV in all rats was positively correlated with amplitude, duration time and V wave BPV and negatively correlated with frequency. The systolic BP spectral powers in the low frequency range (0.38-0.45 Hz) were significantly reduced in the V waves of SAD rats. Moreover, there was a remarkable increase in mean BPV and a normal mean BP after simulating high BPV in SAD rats. These results suggest that enhancement of V waves might be a waveform character of BP in SAD rats in both the conscious and quiet states. These types of V waves appear to be related to a depression of sympathetic regulation of BP induced by sinoaortic denervation.

  17. Rogue wave formation under the action of quasi-stationary pressure

    NASA Astrophysics Data System (ADS)

    Abrashkin, A. A.; Oshmarina, O. E.

    2016-05-01

    The process of rogue wave formation on deep water is considered. A wave of extreme amplitude is born against the background of uniform waves (Gerstner waves) under the action of external pressure on free surface. The pressure distribution has a form of a quasi-stationary "pit". The fluid motion is supposed to be a vortex one and is described by an exact solution of equations of 2D hydrodynamics for an ideal fluid in Lagrangian coordinates. Liquid particles are moving around circumferences of different radii in the absence of drift flow. Values of amplitude and wave steepness optimal for rogue wave formation are found numerically. The influence of vorticity distribution and pressure drop on parameters of the fluid is investigated.

  18. Rogue-wave pattern transition induced by relative frequency

    NASA Astrophysics Data System (ADS)

    Zhao, Li-Chen; Xin, Guo-Guo; Yang, Zhan-Ying

    2014-08-01

    We revisit a rogue wave in a two-mode nonlinear fiber whose dynamics is described by two-component coupled nonlinear Schrödinger equations. The relative frequency between two modes can induce different rogue wave patterns transition. In particular, we find a four-petaled flower structure rogue wave can exist in the two-mode coupled system, which possesses an asymmetric spectrum distribution. Furthermore, spectrum analysis is performed on these different type rogue waves, and the spectrum relations between them are discussed. We demonstrate qualitatively that different modulation instability gain distribution can induce different rogue wave excitation patterns. These results would deepen our understanding of rogue wave dynamics in complex systems.

  19. Identification of rocket-induced acoustic waves in the ionosphere

    NASA Astrophysics Data System (ADS)

    Mabie, Justin; Bullett, Terence; Moore, Prentiss; Vieira, Gerald

    2016-10-01

    Acoustic waves can create plasma disturbances in the ionosphere, but the number of observations is limited. Large-amplitude acoustic waves generated by energetic sources like large earthquakes and tsunamis are more readily observed than acoustic waves generated by weaker sources. New observations of plasma displacements caused by rocket-generated acoustic waves were made using the Vertically Incident Pulsed Ionospheric Radar (VIPIR), an advanced high-frequency radar. Rocket-induced acoustic waves which are characterized by low amplitudes relative to those induced by more energetic sources can be detected in the ionosphere using the phase data from fixed frequency radar observations of a plasma layer. This work is important for increasing the number and quality of observations of acoustic waves in the ionosphere and could help improve the understanding of energy transport from the lower atmosphere to the thermosphere.

  20. Rogue-wave pattern transition induced by relative frequency.

    PubMed

    Zhao, Li-Chen; Xin, Guo-Guo; Yang, Zhan-Ying

    2014-08-01

    We revisit a rogue wave in a two-mode nonlinear fiber whose dynamics is described by two-component coupled nonlinear Schrödinger equations. The relative frequency between two modes can induce different rogue wave patterns transition. In particular, we find a four-petaled flower structure rogue wave can exist in the two-mode coupled system, which possesses an asymmetric spectrum distribution. Furthermore, spectrum analysis is performed on these different type rogue waves, and the spectrum relations between them are discussed. We demonstrate qualitatively that different modulation instability gain distribution can induce different rogue wave excitation patterns. These results would deepen our understanding of rogue wave dynamics in complex systems.

  1. Nonlinear upper hybrid waves and the induced density irregularities

    SciTech Connect

    Kuo, Spencer P.

    2015-08-15

    Upper hybrid waves are excited parametrically by the O-mode high-frequency heater waves in the ionospheric heating experiments. These waves grow to large amplitudes and self-induced density perturbations provide nonlinear feedback. The lower hybrid resonance modifies the nonlinear feedback driven by the ponderomotive force; the nonlinear equation governing the envelope of the upper hybrid waves is derived. Solutions in symmetric alternating functions, in non-alternating periodic functions, as well as in solitary functions are shown. The impact of lower hybrid resonance on the envelope of the upper hybrid waves is explored; the results show that both the spatial period and amplitude are enlarged. The average fluctuation level of induced density irregularities is also enhanced. In the soliton form, the induced density cavity is widened considerably.

  2. Defect induced guided waves mode conversion

    NASA Astrophysics Data System (ADS)

    Wandowski, Tomasz; Kudela, Pawel; Malinowski, Pawel; Ostachowicz, Wieslaw

    2016-04-01

    This paper deals with analysis of guided waves mode conversion phenomenon in fiber reinforced composite materials. Mode conversion phenomenon may take place when propagating elastic guided waves interact with discontinuities in the composite waveguide. The examples of such discontinuities are sudden thickness change or delamination between layers in composite material. In this paper, analysis of mode conversion phenomenon is based on full wave-field signals. In the full wave-field approach signals representing propagation of elastic waves are gathered from dense mesh of points that span over investigated area of composite part. This allow to animate the guided wave propagation. The reported analysis is based on signals resulting from numerical calculations and experimental measurements. In both cases defect in the form of delamination is considered. In the case of numerical research, Spectral Element Method (SEM) is utilized, in which a mesh is composed of 3D elements. Numerical model includes also piezoelectric transducer. Full wave-field experimental measurements are conducted by using piezoelectric transducer for guided wave excitation and Scanning Laser Doppler Vibrometer (SLDV) for sensing.

  3. Spin-transfer torque induced spin waves in antiferromagnetic insulators

    SciTech Connect

    Daniels, Matthew W.; Guo, Wei; Stocks, George Malcolm; Xiao, Di; Xiao, Jiang

    2015-01-01

    We explore the possibility of exciting spin waves in insulating antiferromagnetic films by injecting spin current at the surface. We analyze both magnetically compensated and uncompensated interfaces. We find that the spin current induced spin-transfer torque can excite spin waves in insulating antiferromagnetic materials and that the chirality of the excited spin wave is determined by the polarization of the injected spin current. Furthermore, the presence of magnetic surface anisotropy can greatly increase the accessibility of these excitations.

  4. Seismically induced pressure transients at geothermal reservoirs in the eastern Marmara region

    NASA Astrophysics Data System (ADS)

    Woith, Heiko; Wang, Rongjiang; Caka, Deniz; Irmak, T. Serkan; Tunc, Berna; Luehr, Birger-G.; Baris, Serif

    2014-05-01

    The potential role of fluids in processes related to the triggering of earthquakes and volcanic eruptions is frequently emphasized. Here, we focus on the response of hydrogeological systems to earthquakes, specifically on seismically induced pore-pressure variations in geothermal areas located in the eastern Marmara region. At a 500 m deep artesian geothermal well the pressure is continuously being monitored at a sampling rate of 100 Hz. A seismometer is co-located close to the well-head and the data are recorded by the same digitizer. Hydro-seismograms were recorded in relation to local and distant earthquakes. The ML=5.2 Manyas earthquake which occurred on 20 October 2006 at a distance of 77 km led to a dynamic response of the pore pressure of the order of 4 mbar triggered upon the arrival of the S-wave. Four days later, the ML=5.2 Gemlik earthquake at a distance of 20 km led to a dynamic pore pressure response of the order of 15 mbar triggered upon the arrival of the P-wave. In both cases the peak amplitude of the ground velocity was about 2 mm/s. Weak oscillations of the pore pressure were observed during the passage of surface waves generated by remote earthquakes at distances of up to 9,000 km. Additionally to the dynamic response, a small persistent pressure increase of 1 and 2 mbar had been recorded after both local earthquakes. According to preliminary results, the observed pressure increase is opposite to the static pressure decrease predicted by Okada's model. At the present stage we conclude that the response of the Armutlu geothermal system to earthquakes is likely caused by a dynamic interaction of passing seismic waves (P-, S-, and surface waves) with the fluid reservoir in case a threshold of the ground shaking is exceeded.

  5. Mass transport induced by internal Kelvin waves beneath shore-fast ice

    NASA Astrophysics Data System (ADS)

    StøYlen, Eivind; Weber, Jan Erik H.

    2010-03-01

    A one-layer reduced-gravity model is used to investigate the wave-induced mass flux in internal Kelvin waves along a straight coast beneath shore-fast ice. The waves are generated by barotropic tidal pumping at narrow sounds, and the ice lid introduces a no-slip condition for the horizontal wave motion. The mean Lagrangian fluxes to second order in wave steepness are obtained by integrating the equations of momentum and mass between the material interface and the surface. The mean flow is forced by the conventional radiation stress for internal wave motion, the mean pressure gradient due to the sloping surface, and the frictional drag at the boundaries. The equations that govern the mean fluxes are expressed in terms of mean Eulerian variables, while the wave forcing terms are given by the horizontal divergence of the Stokes flux. Analytical results show that the effect of friction induces a mean Eulerian flux along the coast that is comparable to the Stokes flux. In addition, the horizontal divergence of the total mean flux along the coast induces a small mass flux in the cross-shore direction. This flux changes the mean thickness of the upper layer outside the trapping region and may facilitate geostrophically balanced boundary currents in enclosed basins. This is indeed demonstrated by numerical solutions of the flux equations for confined areas larger than the trapping region. Application of the theory to Arctic waters is discussed, with emphasis on the transport of biological material and pollutants in nearshore regions.

  6. The Generation of Pressure Waves by the Implosion of Light Bulbs in a High-Pressure Water Environment

    NASA Astrophysics Data System (ADS)

    Ikeda, C.; Czechanowski, M.; Duncan, J. H.

    2007-11-01

    The implosion of light bulbs in a high-pressure water environment was studied experimentally in a nearly spherical implosion tank with a nominal internal diameter of 1.77 m. During an experimental run, the light bulb was tethered in the center of the tank which was then filled with water and slowly pressurized by adding nitrogen gas into a small ullage above the water. The gas pressure in the ullage was measured with a slow response transducer and the high-frequency pressure waves in the water were recorded at 14 positions in the tank with underwater blast sensors. The motion of the light bulb was recorded with a high-speed digital movie camera. The implosions occurred at ambient pressures (Pa) ranging from 6.1 bar to 11.6 bar. The collapse times of the light bulbs were found to be about 1.3 times the theoretical collapse time of a spherical bubble at the same ambient pressure and with the same radius as the light bulb. The ratio of the peak pressure increase due to the pressure wave at a fixed distance (r) from the bubble to the ambient pressure at implosion ((P(r)-Pa)/Pa) increased from about 0.5 to 2.7 as the ambient pressure increased over the above-mentioned range.

  7. Pressure-induced decomposition of indium hydroxide.

    PubMed

    Gurlo, Aleksander; Dzivenko, Dmytro; Andrade, Miria; Riedel, Ralf; Lauterbach, Stefan; Kleebe, Hans-Joachim

    2010-09-15

    A static pressure-induced decomposition of indium hydroxide into metallic indium that takes place at ambient temperature is reported. The lattice parameter of c-In(OH)(3) decreased upon compression from 7.977(2) to approximately 7.45 A at 34 GPa, corresponding to a decrease in specific volume of approximately 18%. Fitting the second-order Birch-Murnaghan equation of state to the obtained compression data gave a bulk modulus of 99 +/- 3 GPa for c-In(OH)(3). The c-In(OH)(3) crystals with a size of approximately 100 nm are comminuted upon compression, as indicated by the grain-size reduction reflected in broadening of the diffraction reflections and the appearance of smaller (approximately 5 nm) incoherently oriented domains in TEM. The rapid decompression of compressed c-In(OH)(3) leads to partial decomposition of indium hydroxide into metallic indium, mainly as a result of localized stress gradients caused by relaxation of the highly disordered indium sublattice in indium hydroxide. This partial decomposition of indium hydroxide into metallic indium is irreversible, as confirmed by angle-dispersive X-ray diffraction, transmission electron microscopy imaging, Raman scattering, and FTIR spectroscopy. Recovered c-In(OH)(3) samples become completely black and nontransparent and show typical features of metals, i.e., a falling absorption in the 100-250 cm(-1) region accompanied by a featureless spectrum in the 250-2500 cm(-1) region in the Raman spectrum and Drude-like absorption of free electrons in the region of 4000-8000 cm(-1) in the FTIR spectrum. These features were not observed in the initial c-In(OH)(3), which is a typical white wide-band-gap semiconductor.

  8. [A calibrated method for blood pressure measurement based on volume pulse wave].

    PubMed

    Youde, Ding; Qinkai, Deng; Feixue, Liang; Jinseng, Guo

    2010-01-01

    Physiology parameters measurement based on volume pulse wave is suitable for the monitoring blood pressure continuously. This paper described that the systolic blood pressure (SBP) and diastolic blood pressure (DBP) can be calibrated by measuring the pulse propagation time, just on one point of finger tip. The volume pulse wave was acquired by lighting the red and infrared LED alternately, and after signal processing, an accelerated pulse wave was obtained. Then by measuring the pulse wave propagation time between the progressive wave and reflected wave, we can find the relationship of the time and the blood pressure, and establish the related systolic blood pressure measurement equation. At the same time, based on the relationship between alternating current and direct current components in the volume pulse waveforms and through regression analysising, the relevant diastolic blood pressure measurement equation can be established. 33 clinical experimentation cases have been worked by dividing them into two groups: training group (18 cases) and control group (15 cases), by comparing with the measuring results of the OMRON electronic sphygmomanometer. The results indicated that the two methods had good coherence. The measurement described is simple and reliable, and may be served as a new method for noninvasively and continuously measurement of blood pressure.

  9. Numerical study on wave dynamics and wave-induced bed erosion characteristics in Potter Cove, Antarctica

    NASA Astrophysics Data System (ADS)

    Lim, Chai Heng; Lettmann, Karsten; Wolff, Jörg-Olaf

    2013-12-01

    Wave generation, propagation, and transformation from deep ocean over complex bathymetric terrains to coastal waters around Potter Cove (King George Island, South Shetland Islands, Antarctica) have been simulated for an austral summer month using the Simulating Waves Nearshore (SWAN) wave model. This study aims to examine and understand the wave patterns, energy fluxes, and dissipations in Potter Cove. Bed shear stress due to waves is also calculated to provide a general insight on the bed sediment erosion characteristics in Potter Cove.A nesting approach has been implemented from an oceanic scale to a high-resolution coastal scale around Potter Cove. The results of the simulations were compared with buoy observations obtained from the National Data Buoy Center, the WAVEWATCH III model results, and GlobWave altimeter data. The quality of the modelling results has been assessed using two statistical parameters, namely the Willmott's index of agreement D and the bias index. Under various wave conditions, the significant wave heights at the inner cove were found to be about 40-50 % smaller than the ones near the mouth of Potter Cove. The wave power in Potter Cove is generally low. The spatial distributions of the wave-induced bed shear stress and active energy dissipation were found to be following the pattern of the bathymetry, and waves were identified as a potential major driving force for bed sediment erosion in Potter Cove, especially in shallow water regions. This study also gives some results on global ocean applications of SWAN.

  10. Biological effects of laser-induced stress waves

    SciTech Connect

    Doukas, A.; Lee, S.; McAuliffe, D.

    1995-12-31

    Laser-induced stress waves can be generated by one of the following mechanisms: Optical breakdown, ablation or rapid heating of an absorbing medium. These three modes of laser interaction with matter allow the investigation of cellular and tissue responses to stress waves with different characteristics and under different conditions. The most widely studied phenomena are those of the collateral damage seen in photodisruption in the eye and in 193 run ablation of cornea and skin. On the other hand, the therapeutic application of laser-induced stress waves has been limited to the disruption of noncellular material such as renal stones, atheromatous plaque and vitreous strands. The effects of stress waves to cells and tissues can be quite disparate. Stress waves can fracture tissue, damage cells, and increase the permeability of the plasma membrane. The viability of cell cultures exposed to stress waves increases with the peak stress and the number of pulses applied. The rise time of the stress wave also influences the degree of cell injury. In fact, cell viability, as measured by thymidine incorporation, correlates better with the stress gradient than peak stress. Recent studies have also established that stress waves induce a transient increase of the permeability of the plasma membrane in vitro. In addition, if the stress gradient is below the damage threshhold, the cells remain viable. Thus, stress waves can be useful as a means of drug delivery, increasing the intracellular drug concentration and allowing the use of drugs which are impermeable to the cell membrane. The present studies show that it is important to create controllable stress waves. The wavelength tunability and the micropulse structure of the free electron laser is ideal for generating stress waves with independently adjustable parameters, such as rise time, duration and peak stress.

  11. Quench-induced correlation waves, and quantum grenades

    NASA Astrophysics Data System (ADS)

    Corson, John; Bohn, John

    2016-05-01

    We investigate the wave packet dynamics of a pair of particles that undergoes a rapid change of scattering length. Such quenches have recently become experimentally feasible with fast magnetic-field ramps and optical switching in the vicinity of a Feshbach resonance. The short-range interactions are modelled in the zero-range limit, where the quench is accomplished by switching the boundary condition of the wave function at vanishing particle separation. This generates a correlation wave that propagates rapidly to nonzero particle separations. We have derived universal, analytic results for this process that lead to a simple phase-space picture of quench-induced scattering. Intuitively, the strength of the correlation wave relates to the initial contact of the system. A natural consequence is that the waves are significant when the quench dissociates, at least partially, a bound state. These waves can propagate with high energy from one lattice site to another, potentially triggering highly non-equilibrium dynamics.

  12. Curvature-Induced Asymmetric Spin-Wave Dispersion

    NASA Astrophysics Data System (ADS)

    Otálora, Jorge A.; Yan, Ming; Schultheiss, Helmut; Hertel, Riccardo; Kákay, Attila

    2016-11-01

    In magnonics, spin waves are conceived of as electron-charge-free information carriers. Their wave behavior has established them as the key elements to achieve low power consumption, fast operative rates, and good packaging in magnon-based computational technologies. Hence, knowing alternative ways that reveal certain properties of their undulatory motion is an important task. Here, we show using micromagnetic simulations and analytical calculations that spin-wave propagation in ferromagnetic nanotubes is fundamentally different than in thin films. The dispersion relation is asymmetric regarding the sign of the wave vector. It is a purely curvature-induced effect and its fundamental origin is identified to be the classical dipole-dipole interaction. The analytical expression of the dispersion relation has the same mathematical form as in thin films with the Dzyalonshiinsky-Moriya interaction. Therefore, this curvature-induced effect can be seen as a "dipole-induced Dzyalonshiinsky-Moriya-like" effect.

  13. Limitations of the Use of Pressure Waves to Verify Correct Epidural Needle Position in Dogs

    PubMed Central

    Bergadano, Alessandra; Spadavecchia, Claudia

    2013-01-01

    The use of pressure waves to confirm the correct position of the epidural needle has been described in several domestic species and proposed as a valid alternative to standard methods, namely, control radiographic exam and fluoroscopy. The object of this retrospective clinical study was to evaluate the sensitivity of the epidural pressure waves as a test to verify the correct needle placement in the epidural space in dogs, in order to determine whether this technique could be useful not only in the clinical setting but also when certain knowledge of needle's tip position is required, for instance when performing clinical research focusing on epidural anaesthesia. Of the 54 client-owned dogs undergoing elective surgeries and enrolled in this retrospective study, only 45% showed epidural pressure waves before and after epidural injection. Twenty-six percent of the animals showed epidural pressure waves only after the injection, whereas 29% of the dogs showed epidural pressure waves neither before nor after injection and were defined as false negatives. Our results show that the epidural pressure wave technique to verify epidural needle position lacks sensitivity, resulting in many false negatives. As a consequence, the applicability of this technique is limited to situations in which precise, exact knowledge of the needle's tip position is not mandatory. PMID:23853736

  14. Pressure-induced gelatinization of starch in excess water.

    PubMed

    Vallons, Katleen J R; Ryan, Liam A M; Arendt, Elke K

    2014-01-01

    High pressure processing is a promising non-thermal technology for the development of fresh-like, shelf-stable foods. The effect of high pressure on starch has been explored by many researchers using a wide range of techniques. In general, heat and pressure have similar effects: if sufficiently high, they both induce gelatinization of starch in excess water, resulting in a transition of the native granular structure to a starch paste or gel. However, there are significant differences in the structural and rheological properties between heated and pressurized starches. These differences offer benefits with respect to new product development. However, in order to implement high-pressure technology to starch and starch-containing products, a good understanding of the mechanism of pressure-induced gelatinization is necessary. Studies that are published in this area are reviewed, and the similarities and differences between starches gelatinized by pressure and by temperature are summarized.

  15. Quantification of abnormal intracranial pressure waves and isotope cisternography for diagnosis of occult communicating hydrocephalus

    SciTech Connect

    Cardoso, E.R.; Piatek, D.; Del Bigio, M.R.; Stambrook, M.; Sutherland, J.B.

    1989-01-01

    Nineteen consecutive patients with suspected occult communicating hydrocephalus were investigated by means of clinical evaluation, neuropsychological testing, isotope cisternography, computed tomography scanning, and continuous intracranial pressure monitoring. Semi-quantitative grading systems were used in the evaluation of the clinical, neuropsychological, and cisternographic assessments. Clinical examination, neuropsychological testing, and computed tomography scanning were repeated 3 months after ventriculoperitoneal shunting. All patients showed abnormal intracranial pressure waves and all improved after shunting. There was close correlation between number, peak, and pulse pressures of B waves and the mean intracranial pressure. However, quantification of B waves by means of number, frequency, and amplitude did not help in predicting the degree of clinical improvement postshunting. The most sensitive predictor of favorable response to shunting was enlargement of the temporal horns on computed tomography scan. Furthermore, the size of temporal horns correlated with mean intracranial pressure. There was no correlation between abnormalities on isotope cisternography and clinical improvement.

  16. High Pressure Oxidizer Turbopump (HPOTP) inducer dynamic design environment

    NASA Technical Reports Server (NTRS)

    Herda, D. A.; Gross, R. S.

    1995-01-01

    The dynamic environment must be known to evaluate high pressure oxidizer turbopump inducer fatigue life. This report sets the dynamic design loads for the alternate turbopump inducer as determined by water-flow rig testing. Also, guidelines are given for estimating the dynamic environment for other inducer and impeller applications.

  17. Observations of height-dependent pressure-perturbation structure of a strong mesoscale gravity wave

    NASA Technical Reports Server (NTRS)

    Starr, David O'C.; Korb, C. L.; Schwemmer, Geary K.; Weng, Chi Y.

    1992-01-01

    Airborne observations using a downward-looking, dual-frequency, near-infrared, differential absorption lidar system provide the first measurements of the height-dependent pressure-perturbation field associated with a strong mesoscale gravity wave. A pressure-perturbation amplitude of 3.5 mb was measured within the lowest 1.6 km of the atmosphere over a 52-km flight line. Corresponding vertical displacements of 250-500 m were inferred from lidar-observed displacement of aerosol layers. Accounting for probable wave orientation, a horizontal wavelength of about 40 km was estimated. Satellite observations reveal wave structure of a comparable scale in concurrent cirrus cloud fields over an extended area. Smaller-scale waves were also observed. Local meteorological soundings are analyzed to confirm the existence of a suitable wave duct. Potential wave-generation mechanisms are examined and discussed. The large pressure-perturbation wave is attributed to rapid amplification or possible wave breaking of a gravity wave as it propagated offshore and interacted with a very stable marine boundary layer capped by a strong shear layer.

  18. Pressure-induced referred pain is expanded by persistent soreness.

    PubMed

    Doménech-García, V; Palsson, T S; Herrero, P; Graven-Nielsen, T

    2016-05-01

    Several chronic pain conditions are accompanied with enlarged referred pain areas. This study investigated a novel method for assessing referred pain. In 20 healthy subjects, pressure pain thresholds (PPTs) were recorded and pressure stimuli (120% PPT) were applied bilaterally for 5 and 60 seconds at the infraspinatus muscle to induce local and referred pain. Moreover, PPTs were measured bilaterally at the shoulder, neck, and leg before, during, and after hypertonic saline-induced referred pain in the dominant infraspinatus muscle. The pressure and saline-induced pain areas were assessed on drawings. Subsequently, delayed onset muscle soreness was induced using eccentric exercise of the dominant infraspinatus muscle. The day-1 assessments were repeated the following day (day 2). Suprathreshold pressure stimulations and saline injections into the infraspinatus muscle caused referred pain to the frontal aspect of the shoulder/arm in all subjects. The 60-second pressure stimulation caused larger referred pain areas compared with the 5-second stimulation (P < 0.01). Compared with pressure stimulation, the saline-induced referred pain area was larger (P < 0.02). After saline-induced pain, the PPTs at the infraspinatus and supraspinatus muscles were reduced (P < 0.05), and the 5-second pressure-induced referred pain area was larger than baseline. Pressure pain thresholds at the infraspinatus and supraspinatus muscles were reduced at day 2 in the delayed onset muscle soreness side (P < 0.05). Compared with day 1, larger pressure and saline-induced referred pain areas were observed on day 2 (P < 0.05). Referred pain to the shoulder/arm was consistently induced and enlarged after 1 day of muscle soreness, indicating that the referred pain area may be a sensitive biomarker for sensitization of the pain system.

  19. Pressure induced swelling in microporous materials

    DOEpatents

    Vogt, Thomas; Hriljac, Joseph A.; Lee, Yongjae

    2006-07-11

    A method for capturing specified materials which includes contacting a microporous material with a hydrostatic fluid having at least one specified material carried therein, under pressure which structurally distorts the lattice sufficiently to permit entry of the at least one specified material. The microporous material is capable of undergoing a temporary structural distortion which alters resting lattice dimensions under increased ambient pressure and at least partially returning to rest lattice dimensions when returned to ambient pressure. The pressure of the fluid is then reduced to permit return to at least partial resting lattice dimension while the at least one specified material is therein. By this method, at least one specified material is captured in the microporous material to form a modified microporous material.

  20. Skyrmion-induced bound states in a p -wave superconductor

    NASA Astrophysics Data System (ADS)

    Pöyhönen, Kim; Westström, Alex; Pershoguba, Sergey S.; Ojanen, Teemu; Balatsky, Alexander V.

    2016-12-01

    In s -wave systems, it has been theoretically shown that a ferromagnetic film hosting a skyrmion can induce a bound state embedded in the opposite-spin continuum. In this work, we consider a case of skyrmion-induced state in a p -wave superconductor. We find that the skyrmion induces a bound state that generally resides within the spectral gap and is isolated from all other states, in contrast to the case of conventional superconductors. To this end, we derive an approximate expression for the T matrix, through which we calculate the spin-polarized local density of states which is observable in scanning tunneling microscopy measurements. We find the unique spectroscopic features of the skyrmion-induced bound state and discuss how our predictions could be employed as experimental probes for p -wave superconducting states.

  1. Wave Journal Bearing. Part 2: Experimental Pressure Measurements and Fractional Frequency Whirl Threshold for Wave and Plain Journal Bearings

    NASA Technical Reports Server (NTRS)

    Walker, James F.; Dimofte, Florin; Addy, Harold E., Jr.

    1995-01-01

    A new hydrodynamic bearing concept, the wave journal bearing, is being developed because it has better stability characteristics than plain journal bearings while maintaining similar load capacity. An analysis code to predict the steady state and dynamic performance of the wave journal bearing is also part of the development. To verify numerical predictions and contrast the wave journal bearing's stability characteristics to a plain journal bearing, tests were conducted at NASA Lewis Research Center using an air bearing test rig. Bearing film pressures were measured at 16 ports located around the bearing circumference at the middle of the bearing length. The pressure measurements for both a plain journal bearing and a wave journal bearing compared favorably with numerical predictions. Both bearings were tested with no radial load to determine the speed threshold for self-excited fractional frequency whirl. The plain journal bearing started to whirl immediately upon shaft start-up. The wave journal did not incur self-excited whirl until 800 to 900 rpm as predicted by the analysis. Furthermore, the wave bearing's geometry limited the whirl orbit to less than the bearing's clearance. In contrast, the plain journal bearing did not limit the whirl orbit, causing it to rub.

  2. Molecular-level mechanisms of nanoparticle detachment in laser-induced plasma shock waves

    SciTech Connect

    Zhou Dong; Cetinkaya, Cetin

    2006-04-24

    Detachment and detachment mechanisms of nanoparticles from flat surfaces subjected to shock waves are investigated by employing molecular gas dynamic simulations using the direct simulation Monte Carlo method and experimental transient pressure data. Two mechanisms for nanoparticle detachment based on rolling moment resistance of the adhesion bond and the elastic restitution effect are introduced. As a result of present simulations, it is computationally demonstrated that the pulsed laser-induced shock waves can generate sufficient rolling moments to detach sub-100-nm particles and initiate removal. The transient moment exerted on a 60 nm polystyrene latex particle on a silicon substrate is presented and discussed.

  3. Ultrafast Time Response Pressure-Sensitive Paint for Unsteady Shock-Wave Research

    NASA Astrophysics Data System (ADS)

    Numata, Daiju; Asai, Keisuke

    Pressure-Sensitive Paint (PSP) is an optical pressure measurement technique widely used in aerodynamic experiments, and has been applied to unsteady shock-wave phenomena [1, 2]. However, one of the largest problems to apply PSP to high-speed and unsteady phenomena is the response time of PSP.

  4. Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.

    PubMed

    Berkouk, K; Carpenter, P W; Lucey, A D

    2003-12-01

    Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.

  5. Inducing peer pressure to promote cooperation.

    PubMed

    Mani, Ankur; Rahwan, Iyad; Pentland, Alex

    2013-01-01

    Cooperation in a large society of self-interested individuals is notoriously difficult to achieve when the externality of one individual's action is spread thin and wide on the whole society. This leads to the 'tragedy of the commons' in which rational action will ultimately make everyone worse-off. Traditional policies to promote cooperation involve Pigouvian taxation or subsidies that make individuals internalize the externality they incur. We introduce a new approach to achieving global cooperation by localizing externalities to one's peers in a social network, thus leveraging the power of peer-pressure to regulate behavior. The mechanism relies on a joint model of externalities and peer-pressure. Surprisingly, this mechanism can require a lower budget to operate than the Pigouvian mechanism, even when accounting for the social cost of peer pressure. Even when the available budget is very low, the social mechanisms achieve greater improvement in the outcome.

  6. Inducing Peer Pressure to Promote Cooperation

    PubMed Central

    Mani, Ankur; Rahwan, Iyad; Pentland, Alex

    2013-01-01

    Cooperation in a large society of self-interested individuals is notoriously difficult to achieve when the externality of one individual's action is spread thin and wide on the whole society. This leads to the ‘tragedy of the commons’ in which rational action will ultimately make everyone worse-off. Traditional policies to promote cooperation involve Pigouvian taxation or subsidies that make individuals internalize the externality they incur. We introduce a new approach to achieving global cooperation by localizing externalities to one's peers in a social network, thus leveraging the power of peer-pressure to regulate behavior. The mechanism relies on a joint model of externalities and peer-pressure. Surprisingly, this mechanism can require a lower budget to operate than the Pigouvian mechanism, even when accounting for the social cost of peer pressure. Even when the available budget is very low, the social mechanisms achieve greater improvement in the outcome. PMID:23619166

  7. Inducing Peer Pressure to Promote Cooperation

    NASA Astrophysics Data System (ADS)

    Mani, Ankur; Rahwan, Iyad; Pentland, Alex

    2013-04-01

    Cooperation in a large society of self-interested individuals is notoriously difficult to achieve when the externality of one individual's action is spread thin and wide on the whole society. This leads to the `tragedy of the commons' in which rational action will ultimately make everyone worse-off. Traditional policies to promote cooperation involve Pigouvian taxation or subsidies that make individuals internalize the externality they incur. We introduce a new approach to achieving global cooperation by localizing externalities to one's peers in a social network, thus leveraging the power of peer-pressure to regulate behavior. The mechanism relies on a joint model of externalities and peer-pressure. Surprisingly, this mechanism can require a lower budget to operate than the Pigouvian mechanism, even when accounting for the social cost of peer pressure. Even when the available budget is very low, the social mechanisms achieve greater improvement in the outcome.

  8. Two Dimensional Finite Element Analysis for the Effect of a Pressure Wave in the Human Brain

    NASA Astrophysics Data System (ADS)

    Ponce L., Ernesto; Ponce S., Daniel

    2008-11-01

    Brain injuries in people of all ages is a serious, world-wide health problem, with consequences as varied as attention or memory deficits, difficulties in problem-solving, aggressive social behavior, and neuro degenerative diseases such as Alzheimer's and Parkinson's. Brain injuries can be the result of a direct impact, but also pressure waves and direct impulses. The aim of this work is to develop a predictive method to calculate the stress generated in the human brain by pressure waves such as high power sounds. The finite element method is used, combined with elastic wave theory. The predictions of the generated stress levels are compared with the resistance of the arterioles that pervade the brain. The problem was focused to the Chilean mining where there are some accidents happen by detonations and high sound level. There are not formal medical investigation, however these pressure waves could produce human brain damage.

  9. Transient pressure wave in the behind armor blunt trauma: experimental and computational investigation.

    PubMed

    Luo, Shaomin; Xu, Cheng; Wang, Shu; Wen, Yaoke

    2017-02-01

    In the last few decades, various researches focus on the transient pressure in the behind armor blunt trauma. This paper presented a investigation on the transient pressure in the ballistic gelatin behind a soft body armor subjected to the impacting from three ammunitions. Experimental results show that three peaks appear on the pressure-time curves without taking into account the ammunition type and the impact velocity. Furthermore, numerical models of the test were created to compare modelling results to the pressure from the pressure gauges buried in the gelatin block. The main features on the pressure-time cure were discussed to analyze the wave formation and propagation. With the verified model, the effect of the boundary was also investigated to explain the wave reflection which appeared after two peaks.

  10. Solar wind dynamic pressure effect on planetary wave propagation and synoptic-scale Rossby wave breaking

    NASA Astrophysics Data System (ADS)

    Lu, Hua; Franzke, Christian; Martius, Olivia; Jarvis, Martin J.; Phillips, Tony

    2013-05-01

    We provide statistical evidence of the effect of the solar wind dynamic pressure (Psw) on the northern winter and spring circulations. We find that the vertical structure of the Northern Annular Mode (NAM), the zonal mean circulation, and Eliassen-Palm (EP)-flux anomalies show a dynamically consistent pattern of downward propagation over a period of ~45 days in response to positive Psw anomalies. When the solar irradiance is high, the signature of Psw is marked by a positive NAM anomaly descending from the stratosphere to the surface during winter. When the solar irradiance is low, the Psw signal has the opposite sign, occurs in spring, and is confined to the stratosphere. The negative Psw signal in the NAM under low solar irradiance conditions is primarily governed by enhanced vertical EP-flux divergence and a warmer polar region. The winter Psw signal under high solar irradiance conditions is associated with positive anomalies of the horizontal EP-flux divergence at 55°N-75°N and negative anomalies at 25°N-45°N, which corresponds to the positive NAM anomaly. The EP-flux divergence anomalies occur ~15 days ahead of the mean-flow changes. A significant equatorward shift of synoptic-scale Rossby wave breaking (RWB) near the tropopause is detected during January-March, corresponding to increased anticyclonic RWB and a decrease in cyclonic RWB. We suggest that the barotropic instability associated with asymmetric ozone in the upper stratosphere and the baroclinic instability associated with the polar vortex in the middle and lower stratosphere play a critical role for the winter signal and its downward propagation.

  11. Effect of pressurization on helical guided wave energy velocity in fluid-filled pipes.

    PubMed

    Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

    2017-03-01

    The effect of pressurization stresses on helical guided waves in a thin-walled fluid-filled pipe is studied by modeling leaky Lamb waves in a stressed plate bordered by fluid. Fluid pressurization produces hoop and longitudinal stresses in a thin-walled pipe, which corresponds to biaxial in-plane stress in a plate waveguide model. The effect of stress on guided wave propagation is accounted for through nonlinear elasticity and finite deformation theory. Emphasis is placed on the stress dependence of the energy velocity of the guided wave modes. For this purpose, an expression for the energy velocity of leaky Lamb waves in a stressed plate is derived. Theoretical results are presented for the mode, frequency, and directional dependent variations in energy velocity with respect to stress. An experimental setup is designed for measuring variations in helical wave energy velocity in a thin-walled water-filled steel pipe at different levels of pressure. Good agreement is achieved between the experimental variations in energy velocity for the helical guided waves and the theoretical leaky Lamb wave solutions.

  12. The thermodynamical instability induced by pressure ionization in fluid helium

    NASA Astrophysics Data System (ADS)

    Li, Qiong; Liu, Hai-Feng; Zhang, Gong-Mu; Zhao, Yan-Hong; Lu, Guo; Tian, Ming-Feng; Song, Hai-Feng

    2016-11-01

    A systematic study of pressure ionization is carried out in the chemical picture by the example of fluid helium. By comparing the variants of the chemical model, it is demonstrated that the behavior of pressure ionization depends on the construction of the free energy function. In the chemical model with the Coulomb free energy described by the Padé interpolation formula, thermodynamical instability induced by pressure ionization is found to be manifested by a discontinuous drop or a continuous fall and rise along the pressure-density curve as well as the pressure-temperature curve, which is very much like the first order liquid-liquid phase transition of fluid hydrogen from the first principles simulations. In contrast, in the variant chemical model with the Coulomb free energy term empirically weakened, no thermodynamical instability is induced when pressure ionization occurs, and the resulting equation of state achieves a good agreement with the first principles simulations of fluid helium.

  13. Amplification of Pressure Waves during Vibrational Equilibration of Excited Chemical Reaction Products

    SciTech Connect

    Tarver, C M

    2004-05-11

    The Non-Equilibrium Zeldovich - von Neumann - Doring (NEZND) theory of self-sustaining detonation identified amplification of pressure wavelets during equilibration of vibrationally excited reaction products in the reaction zone as the physical mechanism by which exothermic chemical energy release sustains detonation waves. This mechanism leads to the formation of the well-known, complex three-dimensional structure of a self-sustaining detonation wave. This amplification mechanism is postulated to be a general property of subsonic and supersonic reactive flows occurring during: shock to detonation transition (SDT); hot spot ignition and growth; deflagration to detonation transition (DDT); flame acceleration by shock or compression waves; and acoustic (sound) wave amplification. The existing experimental and theoretical evidence for pressure wave amplification by chemical energy release into highly vibrationally excited product molecules under these reactive flow conditions is reviewed in this paper.

  14. Characterization of laser-driven shock waves in solids using a fiber optic pressure probe

    DOE PAGES

    Cranch, Geoffrey A.; Lunsford, Robert; Grun, Jacob; ...

    2013-11-08

    Measurement of laser-driven shock wave pressure in solid blocks of polymethyl methacrylate is demonstrated using fiber optic pressure probes. Three probes based on a fiber Fabry–Perot, fiber Bragg grating, and interferometric fiber tip sensor are tested and compared. Shock waves are generated using a high-power laser focused onto a thin foil target placed in close proximity to the test blocks. The fiber Fabry–Perot sensor appears capable of resolving the shock front with a rise time of 91 ns. As a result, the peak pressure is estimated, using a separate shadowgraphy measurement, to be 3.4 GPa.

  15. Variation of Pressure Waveforms in Measurements of Extracorporeal Shock Wave Lithotripter

    NASA Astrophysics Data System (ADS)

    Inose, Naoto; Ide, Masao

    1993-05-01

    In this paper, we describe measurement of variation in pressure waveforms of the acoustic field of an extra-corporeal shock-wave lithotripter (ESWL). Variations in the measured acoustic fields and pressure waveform of an underwater spark-gap-type ESWL with an exhausted spark plug electrode have been reported by researchers using crystal sensors. If the ESWL spark plugs become exhausted, patients feel pain during kidney, biliary stone disintegration. We studied the relationship between exhaustion of electrodes and the variation of pressure waveforms and shock-wave fields of the ESWL using a newly developed hydrophone.

  16. Acetabular augmentation induced by extracorporeal shock waves in rabbits.

    PubMed

    Saisu, Takashi; Kamegaya, Makoto; Wada, Yuichi; Takahashi, Kenji; Mitsuhashi, Shigeru; Moriya, Hideshige; Maier, Markus

    2005-05-01

    We conducted this animal study to demonstrate whether exposing the acetabulum in immature rabbits to extracorporeal shock waves induces bone formation in the acetabulum. Five thousand shock waves of 100 MPa each were directed, from outside, at the acetabular roof of eight immature rabbits. At each of two time points (4 and 8 weeks) after treatment, the pelvises of four rabbits were removed and evaluated morphologically. Woven bone formation was observed on the lateral margin of the acetabular roof at 4 weeks after treatment, and the breadth of the acetabular roof in the coronal plane was significantly increased. Eight weeks after treatment, the woven bone disappeared; the breadth of the acetabular roof, however, was significantly increased. These findings demonstrated that extracorporeal shock waves induced acetabular augmentation in rabbits. We conclude that extracorporeal shock waves, perhaps, could be applied clinically for the treatment of acetabular dysplasia.

  17. Xe/+/ -induced ion-cyclotron harmonic waves

    NASA Astrophysics Data System (ADS)

    Jones, D.

    Xenon ion sources on an ejectable package separated from the main payload during the flights of Porcupine rockets F3 and F4 which were launched from Kiruna, Sweden on March 19 and 31, 1979, respectively. The effects of the xenon ion beam, detected by the LF (f less than 16 kHz) wideband electric field experiment and analyzed by using a sonograph, are discussed. Particular attention is given to the stimulation of the ion-cyclotron harmonic waves which are usually linked to the local proton gyro-frequency, but are sometimes related to half that frequency. It was found that in a plasma dominated by O(+) ions, a small amount (1-10%) of protons could cause an effect such that the O(+) cyclotron harmonic waves are set up by the hydrogen ions, the net result being the observation of harmonic emissions separated by the hydrogen ion gyro frequency.

  18. New ultrasonic Bleustein-Gulyaev wave method for measuring the viscosity of liquids at high pressure.

    PubMed

    Kiełczyński, P; Szalewski, M; Siegoczyński, R M; Rostocki, A J

    2008-02-01

    In this paper, a new method for measuring the viscosity of liquids at high pressure is presented. To this end the authors have applied an ultrasonic method using the Bleustein-Gulyaev (BG) surface acoustic wave. By applying the perturbation method, we can prove that the change in the complex propagation constant of the BG wave produced by the layer of liquid loading the waveguide surface is proportional to the shear mechanical impedance of the liquid. In the article, a measuring setup employing the BG wave for the purpose of measuring the viscosity of liquids at high pressure (up to 1 GPa) is presented. The results of high-pressure viscosity measurements of triolein and castor oil are also presented. In this paper the model of a Newtonian liquid was applied. Using this new method it is also possible to measure the viscosity of liquids during the phase transition and during the decompression process (hysteresis of the dependence of viscosity on pressure).

  19. New ultrasonic Bleustein-Gulyaev wave method for measuring the viscosity of liquids at high pressure

    NASA Astrophysics Data System (ADS)

    Kiełczyński, P.; Szalewski, M.; Siegoczyński, R. M.; Rostocki, A. J.

    2008-02-01

    In this paper, a new method for measuring the viscosity of liquids at high pressure is presented. To this end the authors have applied an ultrasonic method using the Bleustein-Gulyaev (BG) surface acoustic wave. By applying the perturbation method, we can prove that the change in the complex propagation constant of the BG wave produced by the layer of liquid loading the waveguide surface is proportional to the shear mechanical impedance of the liquid. In the article, a measuring setup employing the BG wave for the purpose of measuring the viscosity of liquids at high pressure (up to 1GPa) is presented. The results of high-pressure viscosity measurements of triolein and castor oil are also presented. In this paper the model of a Newtonian liquid was applied. Using this new method it is also possible to measure the viscosity of liquids during the phase transition and during the decompression process (hysteresis of the dependence of viscosity on pressure).

  20. Attenuation of propagating spin wave induced by layered nanostructures

    NASA Astrophysics Data System (ADS)

    Sekiguchi, K.; Vader, T. N.; Yamada, K.; Fukami, S.; Ishiwata, N.; Seo, S. M.; Lee, S. W.; Lee, K. J.; Ono, T.

    2012-03-01

    Spin wave attenuation in the layered [FeNi/Pt]6/FeNi thin films was investigated by the time-domain electrical measurement. The spin-wave waveform was detected with an asymmetric coplanar strip transmission line, as an induced voltage flowing into a fast oscilloscope. We report that the amplitude of a spin-wave packet was systematically changed by controlling the thickness of a platinum layer, up to a maximum change of 50%. The virtues of spin wave, ultrafast propagation velocity and non-reciprocal emission, are preserved in this manner. This means that the Pt layer can manipulate an arbitral power-level of spin-wave input signal (reliable attenuator).

  1. Pacemaker interactions induce reentrant wave dynamics in engineered cardiac culture

    NASA Astrophysics Data System (ADS)

    Borek, Bartłomiej; Shajahan, T. K.; Gabriels, James; Hodge, Alex; Glass, Leon; Shrier, Alvin

    2012-09-01

    Pacemaker interactions can lead to complex wave dynamics seen in certain types of cardiac arrhythmias. We use experimental and mathematical models of pacemakers in heterogeneous excitable media to investigate how pacemaker interactions can be a mechanism for wave break and reentrant wave dynamics. Embryonic chick ventricular cells are cultured invitro so as to create a dominant central pacemaker site that entrains other pacemakers in the medium. Exposure of those cultures to a potassium channel blocker, E-4031, leads to emergence of peripheral pacemakers that compete with each other and with the central pacemaker. Waves emitted by faster pacemakers break up over the slower pacemaker to form reentrant waves. Similar dynamics are observed in a modified FitzHugh-Nagumo model of heterogeneous excitable media with two distinct sites of pacemaking. These findings elucidate a mechanism of pacemaker-induced reentry in excitable media.

  2. Ion radial transport induced by ICRF waves in tokamaks

    SciTech Connect

    Chen, L.; Vaclavik, J.; Hammett, G.W.

    1987-05-01

    The wave-induced fluxes of energetic-trapped ions during ICRF heating of tokamak plasmas are calculated using quasilinear equations. A simple single particle model of this transport mechanism is also given. Both a convective flux proportional to k/sub phi/vertical bar E/sub +/vertical bar/sup 2/ and a diffusive flux proportional to k/sub phi//sup 2/vertical bar E/sub +/vertical bar/sup 2/ are found. Here, k/sub phi/ is the toroidal wave number and E/sub +/ is the left-hand polarized wave field. The convective flux may become significant for large k/sub phi/ if the wave spectrum is asymmetric in k/sub phi/. But for the conditions of most previous experiments, these calculations indicate that radial transport driven directly by the ICRF wave is unimportant.

  3. Alfv{acute e}n waves and wave-induced transport near an X point

    SciTech Connect

    Myra, J.R.; DIppolito, D.A.

    1998-03-01

    The behavior of Alfv{acute e}n waves and the corresponding variation of the wave-induced transport coefficients along a field line including the divertor X-point region are examined. It is shown that several competing effects exist and can be quantified using a quasilinear diffusion model that takes the magnetic geometry of the X point into account. To address the issue of mode behavior and the validity of the eikonal approximation near the X point, an exact analytical solution of an equation describing Alfv{acute e}n waves in the X-point region is obtained. The results suggest that the X-point region can only dominate Alfv{acute e}n wave-induced transport on flux surfaces that are very close to the separatrix. {copyright} {ital 1998 American Institute of Physics.}

  4. Current-induced spin-wave Doppler shift.

    PubMed

    Vlaminck, Vincent; Bailleul, Matthieu

    2008-10-17

    Spin transfer appears to be a promising tool for improving spintronics devices. Experiments that quantitatively access the magnitude of the spin transfer are required for a fundamental understanding of this phenomenon. By inductively measuring spin waves propagating along a permalloy strip subjected to a large electrical current, we observed a current-induced spin wave Doppler shift that we relate to the adiabatic spin transfer torque. Because spin waves provide a well-defined system for performing spin transfer, we anticipate that they could be used as an accurate probe of spin-polarized transport in various itinerant ferromagnets.

  5. Modelling and Experimental Verification of Pressure Wave Following Gaseous Helium Storage Tank Rupture

    NASA Astrophysics Data System (ADS)

    Chorowski, M.; Grabowski, M.; Jędrusyna, A.; Wach, J.

    Helium inventory in high energy accelerators, tokamaks and free electron lasers may exceed tens of tons. The gaseous helium is stored in steel tanks under a pressure of about 20 bar and at environment temperature. Accidental rupture of any of the tanks filled with the gaseous helium will create a rapid energy release in form of physical blast. An estimation of pressure wave distribution following the tank rupture and potential consequences to the adjacent research infrastructure and buildings is a very important task, critical in the safety aspect of the whole cryogenic system. According to the present regulations the TNT equivalent approach is to be applied to evaluate the pressure wave following a potential gas storage tank rupture. A special test stand was designed and built in order to verify experimentally the blast effects in controlled conditions. In order to obtain such a shock wave a pressurized plastic tank was used. The tank was ruptured and the resulting pressure wave was recorded using a spatially-distributed array of pressure sensors connected to a high-speed data acquisition device. The results of the experiments and the comparison with theoretical values obtained from thermodynamic model of the blast are presented. A good agreement between the simulated and measured data was obtained. Recommendations regarding the applicability of thermodynamic model of physical blast versus TNT approach, to estimate consequences of gas storage tank rupture are formulated. The laboratory scale experimental results have been scaled to ITER pressurized helium storage tanks.

  6. Impulses and pressure waves cause excitement and conduction in the nervous system.

    PubMed

    Barz, Helmut; Schreiber, Almut; Barz, Ulrich

    2013-11-01

    It is general accepted, that nerval excitement and conduction is caused by voltage changes. However, the influx of fluid into an elastical tube releases impulses or pressure waves. Therefore an influx of ion currents, respectively fluid motions into the elastic neuronal cells and fibres also induce impulses. This motion of charge carriers are measured by voltage devices as oscillations or action potentials, but the voltage changes may be an epiphenomenon of the (mechanical) impulses. Impulse waves can have a high speed. As stiffer or inelastic a tube wall, the greater is the speed of the impulse. Myelin sheaths cause a significant stiffening of the nerve fibre wall and myelinated fibres have a conduction velocity up to 120 m/s. The influx of fluid at the nodes of Ranvier intensifies periodically the impulse wave in the nerve fibres. The authors suggest that also the muscle end-plate acts as a conductor of axonal impulses to the inner of the muscle fibres and that the exocytosis of acetylcholine into the synaptic cleft may be an amplifier of the axonal impulse. It is discussed that intracellular actin filaments may also influence motions at the neuronal membrane. Many sensory nerve cells are excited due to exogenous or endogenous mechanical impulses. It may plausible that such impulses are conducted directly to the sensory nerve cell bodies in the dorsal root ganglia without the transformation in electric energy. Excitation conduction happens without noteworthy energy consumption because the flow of ion currents through the membranes takes place equivalent to the concentration gradient. Impulse waves cause short extensions of the lipid membranes of the cell- and fibres walls and therefore they can induce opening and closing of the included ion channels. This mechanism acts to "voltage gated" and "ligand-gated" channels likewise. The concept of neuronal impulses can be helpful to the understanding of other points of neurophysiology or neuronal diseases. This includes

  7. Pressure-Induced Transformations in Silica

    NASA Astrophysics Data System (ADS)

    Kingma, Kathleen Jane

    Polymorphic phase transitions in the silica minerals alpha-quartz and stishovite have been investigated using diamond-anvil cell techniques at room temperature. Structural and vibrational properties of these materials were monitored as a function of pressure using in situ Raman scattering, synchrotron x-ray diffraction, and optical microscopy. Pressure-quenched samples were characterized at ambient conditions using Raman spectroscopy, electron diffraction, transmission electron microscopy, backscattered and secondary electron imaging, and optical microscopy. Solid-state amorphization of alpha -quartz has been found to begin with formation of crystallographically controlled planar defects, followed by growth of amorphous silica at these defect sites. Characteristic microstructures (planar defects and amorphous lamellae) are found in quartz upon quasihydrostatic and nonhydrostatic compression and from comminution, suggesting that there is a common mechanism for solid-state amorphization of silicates in static and shock compression experiments, meteorite impact, and deformation by tectonic processes. A new crystalline-crystalline transformation has been discovered in alpha-quartz at 21 GPa, documented by abrupt changes in the synchrotron x-ray diffraction pattern and the Raman spectrum. Upon decompression, the high-pressure phase reverts to a quartz -like structure in an unusual twinned state. The Raman spectrum of samples recovered from hydrostatic compression closely resembles spectra of both dynamically shocked quartz and quartz that has experienced extensive grinding; each shows significant deviations from the spectrum of pristine quartz. The transformation from rutile-structured silica (stishovite) to the CaCl_2-structured form has been documented by high-pressure Raman scattering at 51 GPa. At this pressure, the pressure dependence of the soft B_{1rm g} vibrational mode changes sign, and the stishovite E _{rm g} mode splits, as predicted for the transformation

  8. Pressure induced polymerization of fluid ethylene

    NASA Astrophysics Data System (ADS)

    Scelta, Demetrio; Ceppatelli, Matteo; Bini, Roberto

    2016-10-01

    The spontaneous polymerization of fluid ethylene under high temperature and pressure conditions has been characterized by using FTIR absorption spectroscopy. The fluid has been isobarically heated at pressures ranging between 0.4 and 1.5 GPa by means of a resistively heated membrane diamond anvil cell. Besides tracing the instability boundary for spontaneous polymerization in the fluid, we have also measured the reaction kinetics at 1.5 GPa and temperatures ranging between 340 and 423 K. From the rate constants the activation energy of the overall reaction could be computed, information that joined to the molecularity of the initiation step provides some insight about the reaction mechanism. The polymers recovered from the different reactions have been characterized by FTIR, Raman, and X-ray diffraction revealing in all the cases a crystalline material of astonishing quality, likely related to the growth of the polymer in the hot fluid monomer.

  9. Wave reflection augments central systolic and pulse pressures during facial cooling.

    PubMed

    Edwards, David G; Roy, Matthew S; Prasad, Raju Y

    2008-06-01

    Cardiovascular events are more common in the winter months, possibly because of hemodynamic alterations in response to cold exposure. The purpose of this study was to determine the effect of acute facial cooling on central aortic pressure, arterial stiffness, and wave reflection. Twelve healthy subjects (age 23 +/- 3 yr; 6 men, 6 women) underwent supine measurements of carotid-femoral pulse wave velocity (PWV), brachial artery blood pressure, and central aortic pressure (via the synthesis of a central aortic pressure waveform by radial artery applanation tonometry and generalized transfer function) during a control trial (supine rest) and a facial cooling trial (0 degrees C gel pack). Aortic augmentation index (AI), an index of wave reflection, was calculated from the aortic pressure waveform. Measurements were made at baseline, 2 min, and 7 min during each trial. Facial cooling increased (P < 0.05) peripheral and central diastolic and systolic pressures. Central systolic pressure increased more than peripheral systolic pressure (22 +/- 3 vs. 15 +/- 2 mmHg; P < 0.05), resulting in decreased pulse pressure amplification ratio. Facial cooling resulted in a robust increase in AI and a modest increase in PWV (AI: -1.4 +/- 3.8 vs. 21.2 +/- 3.0 and 19.9 +/- 3.6%; PWV: 5.6 +/- 0.2 vs. 6.5 +/- 0.3 and 6.2 +/- 0.2 m/s; P < 0.05). Change in mean arterial pressure but not PWV predicted the change in AI, suggesting that facial cooling may increase AI independent of aortic PWV. Facial cooling and the resulting peripheral vasoconstriction are associated with an increase in wave reflection and augmentation of central systolic pressure, potentially explaining ischemia and cardiovascular events in the cold.

  10. The impact of hepatic pressurization on liver shear wave speed estimates in constrained versus unconstrained conditions

    NASA Astrophysics Data System (ADS)

    Rotemberg, V.; Palmeri, M.; Nightingale, R.; Rouze, N.; Nightingale, K.

    2012-01-01

    Increased hepatic venous pressure can be observed in patients with advanced liver disease and congestive heart failure. This elevated portal pressure also leads to variation in acoustic radiation-force-derived shear wave-based liver stiffness estimates. These changes in stiffness metrics with hepatic interstitial pressure may confound stiffness-based predictions of liver fibrosis stage. The underlying mechanism for this observed stiffening behavior with pressurization is not well understood and is not explained with commonly used linear elastic mechanical models. An experiment was designed to determine whether the stiffness increase exhibited with hepatic pressurization results from a strain-dependent hyperelastic behavior. Six excised canine livers were subjected to variations in interstitial pressure through cannulation of the portal vein and closure of the hepatic artery and hepatic vein under constrained conditions (in which the liver was not free to expand) and unconstrained conditions. Radiation-force-derived shear wave speed estimates were obtained and correlated with pressure. Estimates of hepatic shear stiffness increased with changes in interstitial pressure over a physiologically relevant range of pressures (0-35 mmHg) from 1.5 to 3.5 m s-1. These increases were observed only under conditions in which the liver was free to expand while pressurized. This behavior is consistent with hyperelastic nonlinear material models that could be used in the future to explore methods for estimating hepatic interstitial pressure noninvasively.

  11. Wave-particle interactions induced by SEPAC on Spacelab 1 Wave observations

    NASA Technical Reports Server (NTRS)

    Taylor, W. W. L.; Obayashi, T.; Kawashima, N.; Sasaki, S.; Yanagisawa, M.; Burch, J. L.; Reasoner, D. L.; Roberts, W. T.

    1985-01-01

    Space experiments with particle accelerators (SEPAC) flew on Spacelab 1 in November and December 1983. SEPAC included an accelerator which emitted electrons into the ionospheric plasma with energies up to 5 keV and currents up to 300 mA. The SEPAC equipment also included an energetic plasma generator, a neutral gas generator, and an extensive array of diagnostics. The diagnostics included plasma wave detectors, and energetic electron analyzer, a photometer, a high sensitivity television camera, a Langmuir probe and a pressure gage. Twenty-eight experiments were performed during the mission to investigate beam-plasma interactions, electron beam dynamics, plasma beam propagation, and vehicle charging. The wave-particle interactions were monitored by the plasma wave instrumentation, by the energetic electron detector and by the optical detectors. All show evidence of wave-particle interactions, which are described in this paper.

  12. Pressure gradient induced generation of microbubbles

    NASA Astrophysics Data System (ADS)

    Evangelio, Alvaro; Campo-Cortes, Francisco; Gordillo, Jose Manuel

    2015-11-01

    It is well known that the controlled production of monodisperse bubbles possesses uncountable applications in medicine, pharmacy and industry. Here we provide with a detailed physical description of the bubble formation processes taking place in a type of flow where the liquid pressure gradient can be straightforwardly controlled. In our experiments, a gas flow rate discharges through a cylindrical needle into a pressurized chamber. The pressure gradient created from the exit of the injection needle towards the entrance of a extraction duct promotes the stretching of the gas ligament downstream. In our analysis, which is supported by an exhaustive experimental study in which the liquid viscosity is varied by three orders of magnitude, different regimes can be distinguished depending mainly on the Reynolds number. Through our physical modeling, we provide closed expressions for both the bubbling frequencies and for the bubble diameters as well as the conditions under which a monodisperse generation is obtained in all regimes found. The excellent agreement between our expressions and the experimental data fully validates our physical modeling.

  13. Atmospheric Pressure Oscillations Forced by Surface Waves From the 2003 Tokachi-Oki Earthquake

    NASA Astrophysics Data System (ADS)

    Watada, S.; Nishida, K.; Sekiguchi, S.

    2004-12-01

    Clear atmospheric pressure changes associated with the 2003 Tokachi-Oki Earthquake with M 8.3 were recorded by 8 microbarographs along Japan. The maximum oscillatory pressure change is about 2 Pascal with dominant period is about 15-20 second, and lasted for more than 30 minutes. Comparing the pressure change with broadband seismic records observed near or at the microbarogram, the pressure change starts at the arrival of seismic waves and reaches its maximum amplitude at the arrival of Rayleigh waves. Four microbarographs, co-located with STS-1 broadband seismographs and suffering less atmospheric wind noise, show that peaks in vertical ground velocity records correspond to the peaks of atmospheric pressure records. Similar pressure changes were observed during the largest aftershock (M 7.4). All ground motion analyzed in this paper were recorded by STS-1 broadband sensors. Spectrum analysis in the frequency domain supports that the vertical ground velocity and the pressure change has the same phase and the amplitude ratio is constant up to a period of about 50 second. The constant amplitude ratio is about (atmospheric density) times (sound velocity in the atmosphere), indicating that the surface ground in vertical ground motion compresses or inflates the air above the ground locally and low-frequency sound waves are generated. Pressure change recorded after the passage of Rayleigh waves does not well correlate with the ground velocity. Through the precise atmospheric pressure and ground motion measurement at the same sites, we witnessed the process of low-frequency sound generation by the vertical ground surface motion acted as a vibrating plate of a speaker. The radiated low-frequency sound waves propagates upward and reaches to the ionosphere with large amplitude because of the energy conservation. The ionospheric turbulence reported in the past researches were originated from this low-frequency sound at the ground surface.

  14. Influence of dielectric barrier discharges on low Mach number shock waves at low to medium pressures

    SciTech Connect

    Bletzinger, P.; Ganguly, B.N.; Garscadden, A.

    2005-06-01

    For shock wave propagation in nonequilibrium plasmas, it has been shown that when the electron Debye length exceeds the shock wave discontinuity dimension, strong double layers are generated, propagating with the shock wave. Strong double layer formation leads to the enhancement of the local excitation, ionization, and local neutral gas heating which increases the shock wave velocity. It is shown that dielectric barrier discharges (DBD) in pure N{sub 2} also increase the shock wave velocity and broaden the shock wave. The DBD is considerably more energy efficient in producing these effects compared to a dc glow discharge and can operate over a wide pressure range. It is shown that these effects are also operative in the pure N{sub 2} discharge afterglow, allowing a wide range of pulse repetition frequencies.

  15. Prediction of the characteristics of two types of pressure waves in the cochlea: Theoretical considerations

    NASA Astrophysics Data System (ADS)

    Andoh, Masayoshi; Wada, Hiroshi

    2004-07-01

    The aim of this study was to predict the characteristics of two types of cochlear pressure waves, so-called fast and slow waves. A two-dimensional finite-element model of the organ of Corti (OC), including fluid-structure interaction with the surrounding lymph fluid, was constructed. The geometry of the OC at the basal turn was determined from morphological measurements of others in the gerbil hemicochlea. As far as mechanical properties of the materials within the OC are concerned, previously determined mechanical properties of portions within the OC were adopted, and unknown mechanical features were determined from the published measurements of static stiffness. Time advance of the fluid-structure scheme was achieved by a staggered approach. Using the model, the magnitude and phase of the fast and slow waves were predicted so as to fit the numerically obtained pressure distribution in the scala tympani with what is known about intracochlear pressure measurement. When the predicted pressure waves were applied to the model, the numerical result of the velocity of the basilar membrane showed good agreement with the experimentally obtained velocity of the basilar membrane documented by others. Thus, the predicted pressure waves appeared to be reliable. Moreover, it was found that the fluid-structure interaction considerably influences the dynamic behavior of the OC at frequencies near the characteristic frequency.

  16. Barocaloric effect and the pressure induced solid state refrigerator

    NASA Astrophysics Data System (ADS)

    de Oliveira, N. A.

    2011-03-01

    The current refrigerators are based on the heating and cooling of fluids under external pressure variation. The great inconvenience of this refrigeration technology is the damage caused to the environment by the refrigerant fluids. In this paper, we discuss the magnetic barocaloric effect, i.e., the heating or cooling of magnetic materials under pressure variation and its application in the construction of refrigerators using solid magnetic compounds as refrigerant materials and pressure as the external agent. The discussion presented in this paper points out that such a pressure induced solid state refrigerator can be very interesting because it is not harmful to the environment and can exhibit a good performance.

  17. Optimization of pressure waveform, distribution and sequence in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Zhou, Yufeng

    This work aims to improve shock wave lithotripsy (SWL) technology by increasing stone comminution efficiency while reducing simultaneously the propensity of tissue injury. First, the mechanism of vascular injury in SWL was investigated. Based on in vitro vessel phantom experiment and theoretical calculation, it was found that SWL-induced large intraluminal bubble expansion may constitute a primary mechanism for the rupture of capillaries and small blood vessels. However, when the large intraluminal bubble expansion is suppressed by inversion of the pressure waveform of the lithotripter shock wave (LSW), rupture of a 200-mum cellulose hollow fiber vessel phantom can be avoided. Based on these experimental observations and theoretical assessment of bubble dynamics using the Gilmore model an in situ pulse superposition technique was developed to reduce tissue injury without compromising stone comminution in SWL. A thin shell ellipsoidal reflector insert was fabricated to fit snugly with the original HM-3 reflector. Using the Hamilton model, the effects of reflector geometry on the pulse profile and sequence of the shock waves were evaluated qualitatively. Guided by this analysis, the design of the reflector insert had been refined to suppress the intraluminal bubble expansion, which was confirmed by high-speed imaging of bubble dynamics both in free field and inside a vessel phantom. The pulse pressure, beam size and stone comminution efficiency of the upgraded reflector were all found to be comparable to those of the original reflector. However, the greatest difference lies in the propensity for tissue injury. At the lithotripter focus, about 30 shocks are needed to cause a rupture of the vessel phantom using the original reflector, but no rupture can be produced after 200 shocks by the upgraded reflector. Overall, the upgraded reflector could significantly reduce the propensity of vessel rupture while maintaining satisfactory stone comminution. Second, to improve

  18. Surface modification by subsurface pressure induced diffusion

    SciTech Connect

    Zimmermann, Claus G.

    2012-01-23

    Polycrystalline Ag, covered with a nm thin siloxane layer, was irradiated with ultraviolet light in vacuum at 500 K. Ag particles of different aspect ratios, 50-1000 nm in size, formed on the surface, including a small fraction of nanorods. Pressurized water vapor bubbles are created in the subsurface region by hydrogen radicals photo-chemically released by the siloxane layer. They provide the driving force for a diffusive material flux along grain boundaries to the surface. This mechanism was modeled and found to agree with the experimental timescale: approximately 300 h are required for a 1000 nm particle to form.

  19. Surface modification by subsurface pressure induced diffusion

    NASA Astrophysics Data System (ADS)

    Zimmermann, Claus G.

    2012-01-01

    Polycrystalline Ag, covered with a nm thin siloxane layer, was irradiated with ultraviolet light in vacuum at 500 K. Ag particles of different aspect ratios, 50-1000 nm in size, formed on the surface, including a small fraction of nanorods. Pressurized water vapor bubbles are created in the subsurface region by hydrogen radicals photo-chemically released by the siloxane layer. They provide the driving force for a diffusive material flux along grain boundaries to the surface. This mechanism was modeled and found to agree with the experimental timescale: approximately 300 h are required for a 1000 nm particle to form.

  20. The acute effects of smokeless tobacco on central aortic blood pressure and wave reflection characteristics

    PubMed Central

    Martin, Jeffrey S; Beck, Darren T; Gurovich, Alvaro N; Braith, Randy W

    2010-01-01

    The main objectives of this study were to examine the acute effect of a single dose of smokeless tobacco (ST) on central aortic blood pressure and wave reflection characteristics. Fifteen apparently healthy male subjects (aged 30.6 ± 6.2 y) were given a 2.5 g oral dose of ST after baseline measurements were recorded. Pulse wave analysis using radial artery applanation tonometry was performed in triplicate at baseline (0 min) and at 10-min intervals during (10, 20 and 30 min) and after (40, 50 and 60 min) ST use. An acute dose of ST was associated with a significant increase in heart rate (HR), central aortic systolic and diastolic blood pressure, peripheral brachial systolic and diastolic blood pressure, and aortic augmentation index normalized to a fixed heart rate of 75 bpm (AIx@75). Furthermore, ejection duration and round trip travel time of the reflected pressure wave (Δtp) were significantly decreased as a result of one time ST use. As a result of changes in aortic pressure wave reflection characteristics, there was a significant increase in wasted left ventricular pressure energy (LVEw) and the tension–time index (TTI) as a result of ST use. In conclusion, one time use of ST elicits significant transient increases in HR, central aortic pressures, AIx@75, the TTI and LVEw. Chronic users subjected to decades of elevated central pressures and left ventricular work may have an increased cardiovascular risk as central aortic pressures are even more strongly related to cardiovascular outcomes than peripheral blood pressures. PMID:20719817

  1. The acute effects of smokeless tobacco on central aortic blood pressure and wave reflection characteristics.

    PubMed

    Martin, Jeffrey S; Beck, Darren T; Gurovich, Alvaro N; Braith, Randy W

    2010-10-01

    The main objectives of this study were to examine the acute effect of a single dose of smokeless tobacco (ST) on central aortic blood pressure and wave reflection characteristics. Fifteen apparently healthy male subjects (aged 30.6 ± 6.2 y) were given a 2.5 g oral dose of ST after baseline measurements were recorded. Pulse wave analysis using radial artery applanation tonometry was performed in triplicate at baseline (0 min) and at 10-min intervals during (10, 20 and 30 min) and after (40, 50 and 60 min) ST use. An acute dose of ST was associated with a significant increase in heart rate (HR), central aortic systolic and diastolic blood pressure, peripheral brachial systolic and diastolic blood pressure, and aortic augmentation index normalized to a fixed heart rate of 75 bpm (AIx@75). Furthermore, ejection duration and round trip travel time of the reflected pressure wave (Δt(p)) were significantly decreased as a result of one time ST use. As a result of changes in aortic pressure wave reflection characteristics, there was a significant increase in wasted left ventricular pressure energy (LVE(w)) and the tension-time index (TTI) as a result of ST use. In conclusion, one time use of ST elicits significant transient increases in HR, central aortic pressures, AIx@75, the TTI and LVE(w). Chronic users subjected to decades of elevated central pressures and left ventricular work may have an increased cardiovascular risk as central aortic pressures are even more strongly related to cardiovascular outcomes than peripheral blood pressures.

  2. Wave reflection quantification based on pressure waveforms alone--methods, comparison, and clinical covariates.

    PubMed

    Hametner, Bernhard; Wassertheurer, Siegfried; Kropf, Johannes; Mayer, Christopher; Holzinger, Andreas; Eber, Bernd; Weber, Thomas

    2013-03-01

    Within the last decade the quantification of pulse wave reflections mainly focused on measures of central aortic systolic pressure and its augmentation through reflections based on pulse wave analysis (PWA). A complementary approach is the wave separation analysis (WSA), which quantifies the total amount of arterial wave reflection considering both aortic pulse and flow waves. The aim of this work is the introduction and comparison of aortic blood flow models for WSA assessment. To evaluate the performance of the proposed modeling approaches (Windkessel, triangular and averaged flow), comparisons against Doppler measurements are made for 148 patients with preserved ejection fraction. Stepwise regression analysis between WSA and PWA parameters are performed to provide determinants of methodological differences. Against Doppler measurement mean difference and standard deviation of the amplitudes of the decomposed forward and backward pressure waves are comparable for Windkessel and averaged flow models. Stepwise regression analysis shows similar determinants between Doppler and Windkessel model only. The results indicate that the Windkessel method provides accurate estimates of wave reflection in subjects with preserved ejection fraction. The comparison with waveforms derived from Doppler ultrasound as well as recently proposed simple triangular and averaged flow waves showed that this approach may reduce variability and provide realistic results.

  3. Relationship between radial and central arterial pulse wave and evaluation of central aortic pressure using the radial arterial pulse wave.

    PubMed

    Takazawa, Kenji; Kobayashi, Hideyuki; Shindo, Naohisa; Tanaka, Nobuhiro; Yamashina, Akira

    2007-03-01

    Since a decrease of central aortic pressure contributes to the prevention of cardiovascular events, simple measurement of not only brachial blood pressure but also central aortic pressure may be useful in the prevention and treatment of cardiovascular diseases. In this study, we simultaneously measured radial artery pulse waves non-invasively and ascending aortic pressure invasively, before and after the administration of nicorandil. We then compared changes in central aortic pressure and radial arterial blood pressure calibrated with brachial blood pressure in addition to calculating the augmentation index (AI) at the aorta and radial artery. After nicorandil administration, the reduction in maximal systolic blood pressure in the aorta (Deltaa-SBP) was -14+/-15 mmHg, significantly larger than that in early systolic pressure in the radial artery (Deltar-SBP) (-9+/-12 mmHg). The reduction in late systolic blood pressure in the radial artery (Deltar-SBP2) was -15+/-14 mmHg, significantly larger than Deltar-SBP, but not significantly different from Deltaa-SBP. There were significant relationships between Deltaa-SBP and Deltar-SBP (r=0.81, p<0.001), and between Deltaa-SBP and Deltar-SBP2 (r=0.91, p<0.001). The slope of the correlation regression line with Deltar-SBP2 (0.83) was larger and closer to 1 than that with Deltar-SBP (0.63), showing that the relationship was close to 1:1. Significant correlations were obtained between aortic AI (a-AI) and radial AI (r-AI) (before nicorandil administration: r=0.91, p<0.001; after administration: r=0.70, p<0.001). These data suggest that the measurement of radial artery pulse wave and observation of changes in the late systolic blood pressure in the radial artery (r-SBP2) in addition to the ordinary measurement of brachial blood pressure may enable a more accurate evaluation of changes in maximal systolic blood pressure in the aorta (a-SBP).

  4. Oscillatory pressure wave transmission from the upper airway to the carotid artery.

    PubMed

    Howitt, Lauren; Kairaitis, Kristina; Kirkness, Jason P; Garlick, Sarah R; Wheatley, John R; Byth, Karen; Amis, Terence C

    2007-11-01

    Snoring-associated vibration energy transmission from the upper airway to the carotid artery has been hypothesized as a potential atherosclerotic plaque initiating/rupturing event that may provide a pathogenic mechanism linking snoring and embolic stroke. We examined transmission of oscillatory pressure waves from the pharyngeal lumen to the common carotid artery wall and lumen in seven male, anesthetized, spontaneously breathing New Zealand White rabbits. Airflow was monitored via a pneumotachograph inserted in series in the intact trachea. Fifteen 20-s runs of, separately, 40-, 60-, and 90-Hz oscillatory pressure waves [pressure amplitude in the trachea (Ptr(amp)), amplitude 2-20 cmH(2)O] were generated by a loudspeaker driven by a sine wave generator and amplifier and superimposed on tidal breathing via the cranial tracheal connector. Pressure transducer-tipped catheters measured pressure amplitudes in the tissues adjacent to the common carotid artery bifurcation (Pcti(amp)) and within the lumen (carotid sinus; Pcs(amp)). Data were analyzed using power spectrum analysis and linear mixed-effects statistical modeling. Both the frequency (f) and amplitude of the injected pressure wave influenced Pcti(amp) and Pcs(amp), in that ln Pcti(amp) = 1.2(Ptr(amp)) + 0.02(f) - 5.2, and ln Pcs(amp) = 0.6(Ptr(amp)) + 0.02(f) - 4.9 (both P < 0.05). Across all frequencies tested, transfer of oscillatory pressure across the carotid artery wall was associated with an amplitude gain, as expressed by a Pcs(amp)-to-Pcti(amp) ratio of 1.8 +/- 0.3 (n = 6). Our findings confirm transmission of oscillatory pressure waves from the upper airway lumen to the peripharyngeal tissues and across the carotid artery wall to the lumen. Further studies are required to establish the role of this incident energy in the pathogenesis of carotid artery vascular disease.

  5. Matter-Wave-Optical-Wave Mixing-Induced Transparency and a Nonhyperbolic Matter-Wave Quasisoliton in Quantum Gases

    NASA Astrophysics Data System (ADS)

    Li, Yan; Zhu, Chengjie; Garrett, W. R.; Hagley, E. W.; Deng, L.

    2017-01-01

    The realization of atomic quantum gases has brought out surprising effects that have no correspondence in nonlinear optics with thermal gases, presenting intriguing and exciting challenges to the research discipline of nonlinear optics which has matured since the invention of the laser. Here, we show an unexpected optical wave-mixing gain cancellation effect in a quantum gas that restricts an, otherwise, strongly enhanced backward-propagating light-matter wave-mixing process. This results in a wave-mixing induced transparency and a nonhyperbolic quasi-matter-wave soliton that opens new research opportunities in hydrodynamic fluid research of degenerate quantum gases, such as phonon scattering in a two-dimensional sonic black hole horizon.

  6. Matter-Wave-Optical-Wave Mixing-Induced Transparency and a Nonhyperbolic Matter-Wave Quasisoliton in Quantum Gases.

    PubMed

    Li, Yan; Zhu, Chengjie; Garrett, W R; Hagley, E W; Deng, L

    2017-01-06

    The realization of atomic quantum gases has brought out surprising effects that have no correspondence in nonlinear optics with thermal gases, presenting intriguing and exciting challenges to the research discipline of nonlinear optics which has matured since the invention of the laser. Here, we show an unexpected optical wave-mixing gain cancellation effect in a quantum gas that restricts an, otherwise, strongly enhanced backward-propagating light-matter wave-mixing process. This results in a wave-mixing induced transparency and a nonhyperbolic quasi-matter-wave soliton that opens new research opportunities in hydrodynamic fluid research of degenerate quantum gases, such as phonon scattering in a two-dimensional sonic black hole horizon.

  7. Atmospheric planetary waves induced by solar rotation

    NASA Technical Reports Server (NTRS)

    Krivolutsky, A. A.

    1989-01-01

    It is known that there are variations in the atmospheric processes with a period close to that of the rotation of the Sun (27 days). The variations are discovered in tropospheric processes, rainfalls, geopotential and in stratosphere. The main theoretical problem is the identification of the physical process by which these heterogeneous solar and meteorological phenomena are connected. Ivanovsky and Krivolutsky proposed that the periodic heating of the ozone layer by the short wave radiation would be the reason of excitation the 27-day oscillations. It was also assumed that excitement takes place in condition of resonance with an excited mode corresponding to the conditions present in the stratospheric circulations. The possibility is discussed of the resonant excitation and presentation is made of the data analysis results which support this idea.

  8. A mechanism for sustained groundwater pressure changes induced by distant earthquakes

    USGS Publications Warehouse

    Brodsky, E.E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.

    2003-01-01

    Large sustained well water level changes (>10 cm) in response to distant (more than hundreds of kilometers) earthquakes have proven enigmatic for over 30 years. Here we use high sampling rates at a well near Grants Pass, Oregon, to perform the first simultaneous analysis of both the dynamic response of water level and sustained changes, or steps. We observe a factor of 40 increase in the ratio of water level amplitude to seismic wave ground velocity during a sudden coseismic step. On the basis of this observation we propose a new model for coseismic pore pressure steps in which a temporary barrier deposited by groundwater flow is entrained and removed by the more rapid flow induced by the seismic waves. In hydrothermal areas, this mechanism could lead to 4 ?? 10-2 MPa pressure changes and triggered seismicity.

  9. Superconductivity of Mg/MgO interface formed by shock-wave pressure

    NASA Astrophysics Data System (ADS)

    Sidorov, N. S.; Palnichenko, A. V.; Shakhrai, D. V.; Avdonin, V. V.; Vyaselev, O. M.; Khasanov, S. S.

    2013-05-01

    A mixture of Mg and MgO has been subjected to a shock-wave pressure of ≈170 kbar. The ac susceptibility measurements of the product has revealed a metastable superconductivity with Tc ≈ 30 K, characterized by glassy dynamics of the shielding currents below Tc. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial layer formed between metallic Mg and its oxide due to the shock-wave treatment.

  10. Shear flow induced wave couplings in the solar wind

    SciTech Connect

    Poedts, S.; Rogava, A.D. |; Mahajan, S.M. |

    1998-01-01

    A sheared background flow in a plasma induces coupling between different MHD wave modes, resulting in their mutual transformations with corresponding energy redistributing between the modes. In this way, the energy can be transfered from one wave mode to the other, but energy can also be added to or extracted from the background flow. In the present paper it is investigated whether the wave coupling and energy transfer mechanisms can operate under solar wind conditions. It is shown that this is indeed the case. Hence, the long-period waves observed in the solar wind at r > 0.3 AU might be generated by much faster periodic oscillations in the photosphere of the Sun. Other possible consequences for observable beat phenomena in the wind and the acceleration of the solar wind particles are also discussed.

  11. Wave-induced upper-ocean mixing in a climate model of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Babanin, Alexander V.; Ganopolski, Andrey; Phillips, William R. C.

    Climate modelling, to a great extent, is based on simulating air-sea interactions at larger scales. Small-scale interactions and related phenomena, such as wind-generated waves and wave-induced turbulence are sub-grid processes for such models and therefore cannot be simulated explicitly. In the meantime, the waves play the principal role in the upper-ocean mixing. This role is usually parameterized, mostly to account for the wave-breaking turbulence and to describe downward diffusion of such turbulence. The main purpose of the paper is to demonstrate that an important physical mechanism, that is the ocean mixing due to waves, is presently missing in the climate models, whereas the effect of this mixing is significant. It is argued that the mixing role of the surface waves is not limited to the mere transfer of the wind stress and energy across the ocean interface by means of breaking and surface currents. The waves facilitate two processes in the upper-ocean which can deliver turbulence to the depths of the order of 100 m directly, rather than diffusing it from the surface. The first process is due to capacity of the waves to generate turbulence, unrelated to the wave breaking, at all depths where the wave orbital motion is significant. The second process is Langmuir circulation, triggered by the waves. Such wave-controlled mixing should cause seasonal variations of the mixed-layer depth, which regulates the thermodynamic balance between the ocean and atmosphere. In the present paper, these variations are parameterized in terms of the global winds. The variable mixed-layer depth is then introduced in the climate model of intermediated complexity CLIMBER-2 with a purpose of reproducing the pre-industrial climate. Comparisons are conducted with the NRL global atlas of the mixed layer, and performance of the wave-mixing parameterisations was found satisfactory in circumstances where the mixing is expected to be dominated by the wind-generated waves. It is shown that

  12. Image reconstruction with acoustic radiation force induced shear waves

    NASA Astrophysics Data System (ADS)

    McAleavey, Stephen A.; Nightingale, Kathryn R.; Stutz, Deborah L.; Hsu, Stephen J.; Trahey, Gregg E.

    2003-05-01

    Acoustic radiation force may be used to induce localized displacements within tissue. This phenomenon is used in Acoustic Radiation Force Impulse Imaging (ARFI), where short bursts of ultrasound deliver an impulsive force to a small region. The application of this transient force launches shear waves which propagate normally to the ultrasound beam axis. Measurements of the displacements induced by the propagating shear wave allow reconstruction of the local shear modulus, by wave tracking and inversion techniques. Here we present in vitro, ex vivo and in vivo measurements and images of shear modulus. Data were obtained with a single transducer, a conventional ultrasound scanner and specialized pulse sequences. Young's modulus values of 4 kPa, 13 kPa and 14 kPa were observed for fat, breast fibroadenoma, and skin. Shear modulus anisotropy in beef muscle was observed.

  13. Using pressure and seismological broadband ocean data to model shear wave velocities in the north Atlantic.

    NASA Astrophysics Data System (ADS)

    Rios, Celia; Dahm, Torsten; Jegen, Marion

    2010-05-01

    Seafloor compliance is the transfer function between pressure and vertical displacement at the seafloor Infragravity waves in the oceanic layer have long periods in the range of 30 - 500 s and obey a simple frequency-wavenumber relation. Seafloor compliance from infragravity waves can be analyzed with single station recordings to determinate sub-seafloor shear wave velocities. Previous studies in the Pacific Ocean have demonstrated that reliable near-surface shear wave profiles can be derived from infragravity wave compliance. However, these studies indicate that, beside the water depth the compliance measurements are limited by instrument sensitivity, calibration uncertainties and possibly other effects. In this work seafloor compliance and infragravity waves are observed at two different locations in the Atlantic Ocean: the Logatchev hydrothermal field at the Mid Atlantic Ridge and the Azores (Sao Miguel Island). The data was acquired with the broadband ocean compliance station developed at the University of Hamburg as well as ocean station from the German instrument pool for amphibian seismology (DEPAS) equipped with broadband seismometers and pressure sensors. Vertical velocity and pressure data were used to calculate power spectral densities and normalized compliance along two profiles (one in each location). Power spectral densities show a dominant peak at low frequencies (0.01-0.035Hz) limited by the expected cut-off frequency, which is dependent on the water depth at each station. The peak has been interpreted as a strong infragravity wave with values between 10-14 and 10-11 (m/s2)2/Hz and 104 and 106 (Pa2)2/Hz for acceleration and pressure respectively. The results show compliance values between 10-10 and 10-8 1/Pa and its estimations take into account the coherence between seismic and pressure signals in order to confirm that the seismic signals in the infragravity waves are caused by pressure sources. Shear wave velocity models, with depth resolution

  14. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    PubMed

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  15. Unusual U wave induced by reconstructed retrosternal esophagus

    PubMed Central

    Yamagata, Kenichiro; Uno, Kansei; Mori, Kazuhiko; Seto, Yasuyuki

    2015-01-01

    Key Clinical Message The present case shows that a broad compression of the right ventricle by the reconstructed stomach tube after esophagus cancer surgery induced an abnormal U wave. When facing an abnormal ECG, we should keep in mind of the mechanical compression to the heart as a differential diagnosis. PMID:26576279

  16. Pressure induced breather overturning on deep water: Exact solution

    NASA Astrophysics Data System (ADS)

    Abrashkin, A. A.; Oshmarina, O. E.

    2014-08-01

    A vortical model of breather overturning on deep water is proposed. The action of wind is simulated by nonuniform pressure on the free surface. The fluid motion is described by an exact solution of 2D hydrodynamic equations for an inviscid fluid in Lagrangian variables. Fluid particles rotate in circles of different radii. Formation of contraflexure points on the breather profile is studied. The mechanism of wave breaking and the role of flow vorticity are discussed.

  17. Molecular dynamics study of accelerated ion-induced shock waves in biological media

    NASA Astrophysics Data System (ADS)

    de Vera, Pablo; Mason, Nigel J.; Currell, Fred J.; Solov'yov, Andrey V.

    2016-09-01

    We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model.

  18. Energy Transform and Initial Acoustic Pressure Distribution in Microwave-induced Thermoacoustic Tomography.

    PubMed

    Yan, Jing; Tao, Chunjing; Wu, Shizeng

    2005-01-01

    A study of Microwave-induced Thermoacoustic Tomography is presented in this paper. Microwaves illuminate biological tissues to generate acoustic waves by thermoelastic expansion when electromagnetic energy was absorbed by human tissues. The generated acoustic waves carry information about different electromagnetic properties of different tissues which will be collected and processed to reconstruct human cross section image. In this paper, digital electromagnetic human body model with 1cm resolution was founded according to algorithm requirements. Firstly we analyzed the transform and interrelation among electromagnetic energy, heat energy and acoustic energy. On the basis of established human model: (1) we calculated initial acoustic pressure distribution in cross section image under plane microwave radiation with different frequency. It shows that microwave absorption properties and initial acoustic pressure were different with the change of frequency; (2) using single pulse to illuminate human model, initial acoustic pressure maps of thorax cross section at different time steps were analyzed. These results provided a research basis for further study and calculation of acoustic pressure in microwave-induced thermoacoustic tomography.

  19. In-situ determination of SH-channel wave velocity and the influence of overburden pressure

    SciTech Connect

    Reeves, J.J.; Major, M.W.

    1982-04-01

    In the Dutch Creek 1 Mine at Coal Basin, Colorado, SH-channel waves have been transmitted through floor coal underneath a gob (cave darea) produced by an advancing longwall panel. For any given source, only the receiver directly adjacent or closest to the source was monitored by the Geometrics ES 1210 F seismograph. Two sources were used to excite channel waves at each source location; one an explosive charge, the other a hammer blow. Tests showed that variation in overburden pressure on coal can be detected seismically using channel waves passing through the coal.

  20. Propagation of terahertz waves in an atmospheric pressure microplasma with Epstein electron density profile

    SciTech Connect

    Yuan Chengxun; Zhou Zhongxiang; Zhang, Jingwen W.; Sun Hongguo; Wang He; Du Yanwei; Xiang Xiaoli

    2011-03-15

    Propagation properties of terahertz (THz) waves in a bounded atmospheric-pressure microplasma (AMP) are analyzed in this study. A modified Epstein profile model is used to simulate the electron density distribution caused by the plasma sheaths. By introducing the dielectric constant of a Drude-Lorentz model and using the method of dividing the plasma into a series of subslabs with uniform electron density, the coefficients of power reflection, transmission, and absorption are derived for a bounded microplasma structure. The effects of size of microplasma, electron density profile, and collision frequency on the propagation of THz waves are analyzed numerically. The results indicate that the propagation of THz waves in AMPs depend greatly on the above three parameters. It is demonstrated that the THz wave can play an important role in AMPs diagnostics; meanwhile, the AMP can be used as a novel potential tool to control THz wave propagation.

  1. Experimental observation of standing wave effect in low-pressure very-high-frequency capacitive discharges

    SciTech Connect

    Liu, Yong-Xin; Gao, Fei; Liu, Jia; Wang, You-Nian

    2014-07-28

    Radial uniformity measurements of plasma density were carried out by using a floating double probe in a cylindrical (21 cm in electrode diameter) capacitive discharge reactor driven over a wide range of frequencies (27–220 MHz). At low rf power, a multiple-node structure of standing wave effect was observed at 130 MHz. The secondary density peak caused by the standing wave effect became pronounced and shifts toward the axis as the driving frequency further to increase, indicative of a much more shortened standing-wave wavelength. With increasing rf power, the secondary density peak shift toward the radial edge, namely, the standing-wave wavelength was increased, in good qualitative agreement with the previous theory and simulation results. At higher pressures and high frequencies, the rf power was primarily deposited at the periphery of the electrode, due to the fact that the waves were strongly damped as they propagated from the discharge edge into the center.

  2. Modeling and simulation of pressure waves generated by nano-thermite reactions

    NASA Astrophysics Data System (ADS)

    Martirosyan, Karen S.; Zyskin, Maxim; Jenkins, Charles M.; (Yuki) Horie, Yasuyuki

    2012-11-01

    This paper reports the modeling of pressure waves from the explosive reaction of nano-thermites consisting of mixtures of nanosized aluminum and oxidizer granules. Such nanostructured thermites have higher energy density (up to 26 kJ/cm3) and can generate a transient pressure pulse four times larger than that from trinitrotoluene (TNT) based on volume equivalence. A plausible explanation for the high pressure generation is that the reaction times are much shorter than the time for a shock wave to propagate away from the reagents region so that all the reaction energy is dumped into the gaseous products almost instantaneously and thereby a strong shock wave is generated. The goal of the modeling is to characterize the gas dynamic behavior for thermite reactions in a cylindrical reaction chamber and to model the experimentally measured pressure histories. To simplify the details of the initial stage of the explosive reaction, it is assumed that the reaction generates a one dimensional shock wave into an air-filled cylinder and propagates down the tube in a self-similar mode. Experimental data for Al/Bi2O3 mixtures were used to validate the model with attention focused on the ratio of specific heats and the drag coefficient. Model predictions are in good agreement with the measured pressure histories.

  3. Pressure-induced structural phase transition, elastic and thermodynamic properties of ReC under high pressure

    NASA Astrophysics Data System (ADS)

    Lei, Hui-Ru; Zhu, Jun; Hao, Yan-Jun; Zhang, Lin; Zhao, Yu-Xin; Zhan, Guo-Fu

    2015-10-01

    The pressure-induced structural phase transition of rhenium monocarbon (ReC) is investigated via the projector augmented wave (PAW) method with the generalized gradient approximation (GGA). Using the first-principles calculations, the equilibrium structural parameters of ReC in rocksalt (NaCl), cesium chloride (CsCl), zinc blende (ZB), wurtzite (WZ), nickel arsenide (NiAs) and tungsten carbide (WC) types are successfully obtained, and the results are well consistent with other theoretical data. It is firstly noted that WC-ReC translates into CsCl-ReC at 510.50 GPa by analyzing the enthalpy difference versus pressure. From the calculated elastic constants, the aggregate elastic modulus (B, G, E), the Poisson's ratio (σ) and the Debye temperature ΘD of WC-type are also derived. It is observed that all the data of WC-ReC obtained increase monotonically with increasing pressure. Meanwhile, the thermodynamic properties of WC-ReC under high temperature and high pressure are investigated applying nonempirical Debye model in the quasi-harmonic approximation.

  4. Characteristics of laser-induced shock wave injury to the inner ear of rats

    NASA Astrophysics Data System (ADS)

    Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

    2014-12-01

    Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

  5. Dehydration-induced porosity waves and episodic tremor and slip

    NASA Astrophysics Data System (ADS)

    Skarbek, Rob M.; Rempel, Alan W.

    2016-02-01

    Episodic tremor and slip (ETS) along the subduction interface takes place where there is abundant evidence for elevated, near-lithostatic pore pressures, at sufficiently great depths (30-45 km) that chemical dehydration reactions must act as their dominant source. We simulate fluid and heat flow while tracking the location of a vertically oriented, one-dimensional column of material as it subducts through the slow slip and tremor zone. The material in the column is transformed through a pressure-dependent and temperature-dependent dehydration reaction that we describe with a generalized nonlinear kinetic rate law. Column deformation is largely dominated by viscous creep, with a closure rate that depends linearly on porosity. This behavior causes the dehydration reaction to generate traveling porosity waves that transport increased fluid pressures within the slow slip region. To explore the possibility that the observed periodicity of slow slip and tremor in subduction zones can be explained by the migration of such porosity waves, we derive a dispersion relation that accurately describes our numerical results. We also obtain an expression for how the thickness of the dehydrating layer is expected to vary as a function of the parameters in the reaction rate law. Although the amplitudes of pore pressure perturbations rival those that are produced by known external forcings (e.g., tides or passing surface waves), our analysis suggests that given reasonable estimates of rock viscosity, permeabilities in the range 6.5×10-15 to 5×10-10 m2 are required for porosity wave trains to form at periods comparable to those of slow slip and tremor.

  6. Pressure induced phase transitions in ceramic compounds containing tetragonal zirconia

    SciTech Connect

    Sparks, R.G.; Pfeiffer, G.; Paesler, M.A.

    1988-12-01

    Stabilized tetragonal zirconia compounds exhibit a transformation toughening process in which stress applied to the material induces a crystallographic phase transition. The phase transition is accompanied by a volume expansion in the stressed region thereby dissipating stress and increasing the fracture strength of the material. The hydrostatic component of the stress required to induce the phase transition can be investigated by the use of a high pressure technique in combination with Micro-Raman spectroscopy. The intensity of Raman lines characteristic for the crystallographic phases can be used to calculate the amount of material that has undergone the transition as a function of pressure. It was found that pressures on the order of 2-5 kBar were sufficient to produce an almost complete transition from the original tetragonal to the less dense monoclinic phase; while a further increase in pressure caused a gradual reversal of the transition back to the original tetragonal structure.

  7. Charge Design Considerations and Their Effect on Pressure Waves in Guns

    DTIC Science & Technology

    1980-12-01

    with his invention, the recording crusher gage. The significance of pressure waves, their origin and connection with high pressure and catastrophic...motion. In the second configuration, foam nodules were dispersed in the bed to 2 • expand it fully to the closure plug. The experimental results shown in...PRIMER PROPELLANT BED CORK OR POLYURETHANE WITH POLYSTYRENE FOAM CLOSURE PLUG NODULES Figure 22. Special Experimental Propelling Charges for 5-In./54

  8. The Design, Development, and Evaluation of a Differential Pressure Gauge Directional Wave Monitor.

    DTIC Science & Technology

    1982-10-01

    Ai23 958 THE DESIGN DEVELOPMENT AND EVALUATION OF A DIFFERENTIAL 1/3 PRESSURE GURGE DI..(U) COASTRL ENGINEERING RESEARCH CENTER FORT BELVOIR YR K R...I1IBI =. 5 6 LA 112 MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS-1963- A q.. MR 82-11 k0- The Design, Development, and Evaluation of a ...OF REPORT & PERIOD COVERED THE DESIGN, DEVELOPMENT, AND EVALUATION Miscellaneous Report OF A DIFFERENTIAL PRESSURE GAUGE DIRECTIONAL WAVE MONITOR 6

  9. Transport induced by ion cyclotron range of frequencies waves

    SciTech Connect

    Zhang, Debing Xu, Yingfeng; Wang, Shaojie

    2014-11-15

    The Vlasov equation, which includes the effect of the ion cyclotron range of frequencies (ICRF) waves, can be written as the Fokker-Planck equation which describes the quasilinear transport in phase space by using the Lie-transform method. The radial transport fluxes of particle, energy and parallel momentum driven by ICRF waves in the slab geometry have been derived. The results show that the ICRF-induced radial redistributions of particle, energy and parallel momentum are driven by the inhomogeneity in energy of the equilibrium distribution function, and related to the correlation between the excursion in the real space and the excursion in energy. For the case with strong asymmetry of k{sub y} spectrum, the ICRF-induced radial transport driven by the energy inhomogeneity dominates the ICRF-induced radial transport driven by the spatial inhomogeneity.

  10. Voltage induced mechanical/spin wave propagation over long distances

    NASA Astrophysics Data System (ADS)

    Chen, C.; Barra, A.; Mal, A.; Carman, G.; Sepulveda, A.

    2017-02-01

    We simulated the generation and propagation of spin waves (SWs) using two excitation methods, namely, magnetic field and voltage induced strain. A fully coupled non-linear magnetoelastic model, combining Landau-Lifshitz-Gilbert with elastodynamic equations, is used to study the propagation characteristics of SWs in magnetoelastic materials. Simulation results show that for excitation frequencies above ferromagnetic resonance (FMR), SWs excited by voltage induced strain propagate over longer distances compared to SWs excited by magnetic field. In addition, strain mediated SWs exhibit loss characteristics, which are relatively independent of the magnetic losses (Gilbert damping). Moreover, it is also shown that strain induced SWs can also be excited at frequencies below FMR.

  11. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    NASA Technical Reports Server (NTRS)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  12. Agyrotropic pressure tensor induced by the plasma velocity shear

    NASA Astrophysics Data System (ADS)

    Pegoraro, Francesco; Del Sarto, Danele; Califano, Francesco

    2016-10-01

    We show that the spatial inhomogeneity of a shear flow in a fluid plasma is transferred to a pressure anisotropy that has both a gyrotropic and a non gyrotropic component. We investigate this process both analytically and numerically by including the full pressure tensor dynamics. We determine the time evolution of the pressure agyrotropy and in general of the pressure tensor anisotropization which arise from the action of both the magnetic eld and the flow strain tensor. This mechanism can affect the onset and development of shear-induced fluid instabilities in plasmas and is relevant to the understanding of the origin of some of the non-Maxwellian distribution functions evidenced both in Vlasov simulations and in space plasma measurements that exhibit pressure agyrotropy.

  13. Stratospheric Annular Modes Induced By Stationary Wave Forcing

    NASA Astrophysics Data System (ADS)

    Körnich, H.; Schmitz, G.

    The variability of the winter stratosphere shows distinguishable features in the north- ern and southern hemisphere. Since these differences are based on the different plan- etary waves of the underlying atmosphere, we explore the mechanism how stationary wave forcing in the troposphere can induce a stratospheric Annular Mode using a simple GCM. The model KMCM (Kühlungsborn Mechanistic Circulation Model) extends from the ground up to 60 km height and produces a reasonable winter climate. It takes into account the different large-scale wave forcings in the troposphere as prescribed pro- cesses. This allows us to examine the stratospheric Annular-Mode generation depend- ing on different wave forcings under perpetual January conditions. Principal com- ponent analysis is applied to identify the variability patterns of the geopotential and of the zonally averaged zonal wind. By this way, it is shown that the amplitude and composition of the orographic and thermal eddy forcing determines the stratospheric Annular Mode and the related downward propagation in the temperature field. Further model simplifications are introduced in order to understand the mechanism of the stratospheric AM-generation. Using a linear model version we illuminate the influence of the different wave forcing processes on the Annular Modes. Addition- ally, a constant-troposphere model is used to clarify the importance of transient and stationary waves. Finally, the Annular Mode is interpreted in terms of the dynamical coupling of the troposphere and stratosphere.

  14. Unsteady non-equilibrium model of laser induced detonation wave

    NASA Astrophysics Data System (ADS)

    Oshima, Takeharu; Fujiwara, Toshitaka

    1992-12-01

    Now that laser propulsion is hoped to become a next-generation space propulsion system, it is important to analyze the mechanisms of LSD (Laser-Supported Detonation) wave caused by laser absorption. The performance of laser propulsion is determined mainly by laser absorption efficiency. To absorb laser energy effectively, it is necessary to generate sufficient free electrons in the laser absorbing zone. Thus, the LSD wave must be monitored. At first, the incident laser energy vaporizes the solid propellant and produces free electrons. These free electrons start laser absorption and as a result produce high temperature and pressure. Then an ignition occurs and this grows into a detonation wave. Four types of physico-chemical processes take place in the LSD wave. First, laser energy is first absorbed by free electrons through inverse bremsstrahlung. Next this energy is distributed to heavy particles (atoms and ions) through elastic and inelastic collision processes, and is lost partly by bremsstrahlung as radiation energy. Based on such backgrounds, this LSD wave is simulated by using a plane one-dimensional numerical analysis to clarify the mechanism on the ignition phenomenon in a laser-sustained plasma. In this study, a TVD (Total Variation Diminishing) code which takes account of real gas effects is utilized.

  15. Shear wave induced resonance elastography of spherical masses with polarized torsional waves

    NASA Astrophysics Data System (ADS)

    Hadj Henni, Anis; Schmitt, Cédric; Trop, Isabelle; Cloutier, Guy

    2012-03-01

    Shear wave induced resonance (SWIR) is a technique for dynamic ultrasound elastography of confined mechanical inclusions. It was developed for breast tumor imaging and tissue characterization. This method relies on the polarization of torsional shear waves modeled with the Helmholtz equation in spherical coordinates. To validate modeling, an invitro set-up was used to measure and image the first three eigenfrequencies and eigenmodes of a soft sphere. A preliminary invivo SWIR measurement on a breast fibroadenoma is also reported. Results revealed the potential of SWIR elastography to detect and mechanically characterize breast lesions for early cancer detection.

  16. Control and reduction of unsteady pressure loads in separated shock wave turbulent boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Dolling, David S.; Barter, John W.

    1995-01-01

    The focus was on developing means of controlling and reducing unsteady pressure loads in separated shock wave turbulent boundary layer interactions. Section 1 describes how vortex generators can be used to effectively reduce loads in compression ramp interaction, while Section 2 focuses on the effects of 'boundary-layer separators' on the same interaction.

  17. First-Principles Study of Pressure-Induced Phase Transition in CuGaO2

    NASA Astrophysics Data System (ADS)

    Jiang, Cheng-Lu; Liu, Qi-Jun; Liu, Zheng-Tang

    2017-02-01

    We have studied the structural, elastic, electronic properties, and pressure-induced phase transition of CuGaO2 by using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT). The obtained ground state properties of three phases were in agreement with previous works. The calculated enthalpy variations with pressure showed that the structural phase transition ( β → 3R/2H) appeared at 65.5 ± 1 GPa. The changes in volume and band gap of β phase showed that there was a break between 30 and 40 GPa. The independent elastic constants of three phases were calculated. The 3R, 2H, and β phases were all mechanical stability and behaved in ductile manner under zero pressure.

  18. Effect of the dynamic pressure on the shock wave structure in a rarefied polyatomic gas

    SciTech Connect

    Taniguchi, Shigeru Sugiyama, Masaru; Arima, Takashi; Ruggeri, Tommaso

    2014-01-15

    We study the shock wave structure in a rarefied polyatomic gas based on a simplified model of extended thermodynamics in which the dissipation is due only to the dynamic pressure. In this case the differential system is very simple because it is a variant of Euler system with a new scalar equation for the dynamic pressure [T. Arima, S. Taniguchi, T. Ruggeri, and M. Sugiyama, Phys. Lett. A 376, 2799–2803 (2012)]. It is shown that this theory is able to describe the three types of the shock wave structure observed in experiments: the nearly symmetric shock wave structure (Type A, small Mach number), the asymmetric structure (Type B, moderate Mach number), and the structure composed of thin and thick layers (Type C, large Mach number)

  19. Three-dimensional visualization of shear wave propagation generated by dual acoustic radiation pressure

    NASA Astrophysics Data System (ADS)

    Mochizuki, Yuta; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    An elastic property of biological soft tissue is an important indicator of the tissue status. Therefore, quantitative and noninvasive methods for elasticity evaluation have been proposed. Our group previously proposed a method using acoustic radiation pressure irradiated from two directions for elastic property evaluation, in which by measuring the propagation velocity of the shear wave generated by the acoustic radiation pressure inside the object, the elastic properties of the object were successfully evaluated. In the present study, we visualized the propagation of the shear wave in a three-dimensional space by the synchronization of signals received at various probe positions. The proposed method succeeded in visualizing the shear wave propagation clearly in the three-dimensional space of 35 × 41 × 4 mm3. These results show the high potential of the proposed method to estimate the elastic properties of the object in the three-dimensional space.

  20. Hydrodynamic pressure computation under real sea surface on basis of autoregressive model of irregular waves

    NASA Astrophysics Data System (ADS)

    Degtyarev, A.; Gankevich, I.

    2015-05-01

    Determining the impact of external excitations on a dynamic marine object such as ship hull in a seaway is the main goal of simulations. Now such simulations is most often based on approximate mathematical models that use results of the theory of small amplitude waves. The most complicated software for marine objects behavior simulation LAMP IV (Large amplitude motion program) uses numerical solution of traditional hydrodynamic problem without often used approximations but on the basis of theory of small amplitude waves. For efficiency reasons these simulations can be based on autoregressive model to generate real wave surface. Such a surface possesses all the hydrodynamic characteristics of sea waves, preserves dispersion relation and also shows superior performance compared to other wind wave models. Naturally, the known surface can be used to compute velocity field and in turn to determine pressures in any point under sea surface. The resulting computational algorithm can be used to determine pressures without use of theory of small-amplitude waves.

  1. Wave induced density modification in RF sheaths and close to wave launchers

    SciTech Connect

    Van Eester, D.; Lu, Ling-Feng

    2015-12-10

    With the return to full metal walls - a necessary step towards viable fusion machines - and due to the high power densities of current-day ICRH (Ion Cyclotron Resonance Heating) or RF (radio frequency) antennas, there is ample renewed interest in exploring the reasons for wave-induced sputtering and formation of hot spots. Moreover, there is experimental evidence on various machines that RF waves influence the density profile close to the wave launchers so that waves indirectly influence their own coupling efficiency. The present study presents a return to first principles and describes the wave-particle interaction using a 2-time scale model involving the equation of motion, the continuity equation and the wave equation on each of the time scales. Through the changing density pattern, the fast time scale dynamics is affected by the slow time scale events. In turn, the slow time scale density and flows are modified by the presence of the RF waves through quasilinear terms. Although finite zero order flows are identified, the usual cold plasma dielectric tensor - ignoring such flows - is adopted as a first approximation to describe the wave response to the RF driver. The resulting set of equations is composed of linear and nonlinear equations and is tackled in 1D in the present paper. Whereas the former can be solved using standard numerical techniques, the latter require special handling. At the price of multiple iterations, a simple ’derivative switch-on’ procedure allows to reformulate the nonlinear problem as a sequence of linear problems. Analytical expressions allow a first crude assessment - revealing that the ponderomotive potential plays a role similar to that of the electrostatic potential arising from charge separation - but numerical implementation is required to get a feeling of the full dynamics. A few tentative examples are provided to illustrate the phenomena involved.

  2. Wave induced density modification in RF sheaths and close to wave launchers

    NASA Astrophysics Data System (ADS)

    Van Eester, D.; Crombé, K.; Lu, Ling-Feng

    2015-12-01

    With the return to full metal walls - a necessary step towards viable fusion machines - and due to the high power densities of current-day ICRH (Ion Cyclotron Resonance Heating) or RF (radio frequency) antennas, there is ample renewed interest in exploring the reasons for wave-induced sputtering and formation of hot spots. Moreover, there is experimental evidence on various machines that RF waves influence the density profile close to the wave launchers so that waves indirectly influence their own coupling efficiency. The present study presents a return to first principles and describes the wave-particle interaction using a 2-time scale model involving the equation of motion, the continuity equation and the wave equation on each of the time scales. Through the changing density pattern, the fast time scale dynamics is affected by the slow time scale events. In turn, the slow time scale density and flows are modified by the presence of the RF waves through quasilinear terms. Although finite zero order flows are identified, the usual cold plasma dielectric tensor - ignoring such flows - is adopted as a first approximation to describe the wave response to the RF driver. The resulting set of equations is composed of linear and nonlinear equations and is tackled in 1D in the present paper. Whereas the former can be solved using standard numerical techniques, the latter require special handling. At the price of multiple iterations, a simple 'derivative switch-on' procedure allows to reformulate the nonlinear problem as a sequence of linear problems. Analytical expressions allow a first crude assessment - revealing that the ponderomotive potential plays a role similar to that of the electrostatic potential arising from charge separation - but numerical implementation is required to get a feeling of the full dynamics. A few tentative examples are provided to illustrate the phenomena involved.

  3. Experimental Study on a Standing Wave Thermoacoustic Prime Mover with Air Working Gas at Various Pressures

    NASA Astrophysics Data System (ADS)

    Setiawan, Ikhsan; Achmadin, Wahyu N.; Murti, Prastowo; Nohtomi, Makoto

    2016-04-01

    Thermoacoustic prime mover is an energy conversion device which converts thermal energy into acoustic work (sound wave). The advantages of this machine are that it can work with air as the working gas and does not produce any exhaust gases, so that it is environmentally friendly. This paper describes an experimental study on a standing wave thermoacoustic prime mover with air as the working gas at various pressures from 0.05 MPa to 0.6 MPa. We found that 0.2 MPa is the optimum pressure which gives the lowest onset temperature difference of 355 °C. This pressure value would be more preferable in harnessing low grade heat sources to power the thermoacoustic prime mover. In addition, we find that the lowest onset temperature difference is obtained when rh /δ k ratio is 2.85, where r h is the hydraulic radius of the stack and δ k is the thermal penetration depth of the gas. Moreover, the pressure amplitude of the sound wave is significantly getting larger from 2.0 kPa to 9.0 kPa as the charged pressure increases from 0.05 MPa up to 0.6 MPa.

  4. Measurement of the normal component of compressive wave pressure in a rock with Manganin sensors

    SciTech Connect

    Virchenko, V.A.; Egorov, A.P.; Krasavin, S.V.

    1985-03-01

    Measurement of dynamic pressures in compressed media with manganin wire sensors has become common in the past few years. The increased interest in this method is due to the technological simplicity of measurement and the ease of manufacturing the manganin pickup. The method has been continually improved and put to new applications. In this paper the authors describe an experiment using manganin sensors to measure the normal component of a compressive pressure wave in rocks (marble, schist, and diabase) generated by industrial blasts. Subtle effects not previously identified include: decomposition of the shockwave in the rock and identification of an elastic precursor; features of damping of the normal component of compressive wave pressure as a function of distance from the load application point; and the pattern of destruction of brittle materials. The authors conclude that manganin sensors can be broadly applied in mining for studies of the efficacy of various types of explosives and in investigations of the mechanism of rock destruction.

  5. Irreversibility of Pressure Induced Boron Speciation Change in Glass

    PubMed Central

    Smedskjaer, Morten M.; Youngman, Randall E.; Striepe, Simon; Potuzak, Marcel; Bauer, Ute; Deubener, Joachim; Behrens, Harald; Mauro, John C.; Yue, Yuanzheng

    2014-01-01

    It is known that the coordination number (CN) of atoms or ions in many materials increases through application of sufficiently high pressure. This also applies to glassy materials. In boron-containing glasses, trigonal BO3 units can be transformed into tetrahedral BO4 under pressure. However, one of the key questions is whether the pressure-quenched CN change in glass is reversible upon annealing below the ambient glass transition temperature (Tg). Here we address this issue by performing 11B NMR measurements on a soda lime borate glass that has been pressure-quenched at ~0.6 GPa near Tg. The results show a remarkable phenomenon, i.e., upon annealing at 0.9Tg the pressure-induced change in CN remains unchanged, while the pressurised values of macroscopic properties such as density, refractive index, and hardness are relaxing. This suggests that the pressure-induced changes in macroscopic properties of soda lime borate glasses compressed up to ~0.6 GPa are not attributed to changes in the short-range order in the glass, but rather to changes in overall atomic packing density and medium-range structures. PMID:24442182

  6. Effect of osmolytes on pressure-induced unfolding of proteins: a high-pressure SAXS study.

    PubMed

    Krywka, Christina; Sternemann, Christian; Paulus, Michael; Tolan, Metin; Royer, Catherine; Winter, Roland

    2008-12-22

    Herein, we explore the effect of different types of osmolytes on the high-pressure stability and tertiary structure of a well-characterized monomeric protein, staphylococcal nuclease (SNase). Changes in the denaturation pressure and the radius of gyration are obtained in the presence of different concentrations of trimethylamine N-oxide (TMAO), glycerol and urea. To reveal structural changes in the protein upon compression at various osmolyte conditions, small-angle X-ray scattering (SAXS) experiments were carried out. To this end, a new high-pressure cell suitable for high-precision SAXS studies at synchrotron sources was built, which allows one to carry out scattering experiments up to maximum pressures of about 7 kbar. Our data clearly indicate that the osmolytes that stabilize proteins against temperature-induced unfolding drastically increase their pressure stability and that the elliptically shaped curve of the pressure-temperature-stability diagram of proteins is shifted to higher temperatures and pressures with increasing osmolyte concentration. A drastic stabilization is observed for the osmolyte TMAO, which exhibits not only a significant stabilization against temperature-induced unfolding, but also a particularly strong stabilization of the protein against pressure. In fact, such findings are in accordance with in vivo studies (for example P. J. Yancey, J. Exp. Biol. 2005, 208, 2819-2830), where unusually high TMAO concentrations in some deep-sea animals were found. Conversely, chaotropic agents such as urea have a strong destabilizing effect on both the temperature and pressure stability of the protein. Our data also indicate that sufficiently high TMAO concentrations might be able to largely offset the destabilizing effect of urea. The different scenarios observed are discussed in the context of recent experimental and theoretical studies.

  7. Brachial vs. central systolic pressure and pulse wave transmission indicators: a critical analysis.

    PubMed

    Izzo, Joseph L

    2014-12-01

    This critique is intended to provide background for the reader to evaluate the relative clinical utilities of brachial cuff systolic blood pressure (SBP) and its derivatives, including pulse pressure, central systolic pressure, central augmentation index (AI), and pulse pressure amplification (PPA). The critical question is whether the newer indicators add sufficient information to justify replacing or augmenting brachial cuff blood pressure (BP) data in research and patient care. Historical context, pathophysiology of variations in pulse wave transmission and reflection, issues related to measurement and model errors, statistical limitations, and clinical correlations are presented, along with new comparative data. Based on this overview, there is no compelling scientific or practical reason to replace cuff SBP with any of the newer indicators in the vast majority of clinical situations. Supplemental value for central SBP may exist in defining patients with exaggerated PPA ("spurious systolic hypertension"), managing cardiac and aortic diseases, and in studies of cardiovascular drugs, but there are no current standards for these possibilities.

  8. The quality of high pressure-induced and heat-induced yuzu marmalade

    NASA Astrophysics Data System (ADS)

    Kuwada, Hiroko; Jibu, Yuri; Teramoto, Ai; Fuchigami, Michiko

    2010-12-01

    Yuzu is a typical Japanese citrus with a desirable smell. The objectives of this study are to establish a process for pressure-induced marmalade (without both heating or the addition of pectin) and compare it with heat-induced marmalade. Sliced peel (flavedo) was soaked in 2% citric acid solution (pH 2.0). Albedo, endocarp and juice sacs were homogenized with 0.3% citric acid solution (pH 2.5). After soaking for 24 h, these were mixed and 50% or 60% sucrose of the total weight was added, then pressurized at 500 MPa or boiled (process A). Process B: all processing was done at pH 2.7. Peel of high pressure-induced marmalade maintained a natural color. Flavedo in heat-induced marmalade was softer than that of pressure-induced marmalade. There was no difference in viscosity between heat-induced and high pressure-induced marmalade. High pressure-induced marmalade with 50% sugar was preferred by a sensory test because fresh flavor and color were maintained.

  9. Ballistic quench-induced correlation waves in ultracold gases

    NASA Astrophysics Data System (ADS)

    Corson, John P.; Bohn, John L.

    2016-08-01

    We investigate the wave-packet dynamics of a pair of particles that undergoes a rapid change of scattering length. The short-range interactions are modeled in the zero-range limit, where the quench is accomplished by switching the boundary condition of the wave function at vanishing particle separation. This generates a correlation wave that propagates rapidly to nonzero particle separations. We have derived universal, analytic results for this process that lead to a simple phase-space picture of the quench-induced scattering. Intuitively, the strength of the correlation wave relates to the initial contact of the system. We find that, in one spatial dimension, the k-4 tail of the momentum distribution contains a ballistic contribution that does not originate from short-range pair correlations, and a similar conclusion can hold in other dimensionalities depending on the quench protocol. We examine the resultant quench-induced transport in an optical lattice in one dimension, and a semiclassical treatment is found to give quantitatively accurate estimates for the transport probabilities.

  10. Comparison of actinide production in traveling wave and pressurized water reactors

    SciTech Connect

    Osborne, A.G.; Smith, T.A.; Deinert, M.R.

    2013-07-01

    The geopolitical problems associated with civilian nuclear energy production arise in part from the accumulation of transuranics in spent nuclear fuel. A traveling wave reactor is a type of breed-burn reactor that could, if feasible, reduce the overall production of transuranics. In one possible configuration, a cylinder of natural or depleted uranium would be subjected to a fast neutron flux at one end. The neutrons would transmute the uranium, producing plutonium and higher actinides. Under the right conditions, the reactor could become critical, at which point a self-stabilizing fission wave would form and propagate down the length of the reactor cylinder. The neutrons from the fission wave would burn the fissile nuclides and transmute uranium ahead of the wave to produce additional fuel. Fission waves in uranium are driven largely by the production and fission of {sup 239}Pu. Simulations have shown that the fuel burnup can reach values greater than 400 MWd/kgIHM, before fission products poison the reaction. In this work we compare the production of plutonium and minor actinides produced in a fission wave to that of a UOX fueled light water reactor, both on an energy normalized basis. The nuclide concentrations in the spent traveling wave reactor fuel are computed using a one-group diffusion model and are verified using Monte Carlo simulations. In the case of the pressurized water reactor, a multi-group collision probability model is used to generate the nuclide quantities. We find that the traveling wave reactor produces about 0.187 g/MWd/kgIHM of transuranics compared to 0.413 g/MWd/kgIHM for a pressurized water reactor running fuel enriched to 4.95 % and burned to 50 MWd/kgIHM. (authors)

  11. Pressure fluctuations beneath turbulent spots and instability wave packets in a hypersonic boundary layer.

    SciTech Connect

    Beresh, Steven Jay; Casper, Katya M.; Schneider, Steven P.

    2010-12-01

    The development of turbulent spots in a hypersonic boundary layer was studied on the nozzle wall of the Boeing/AFOSR Mach-6 Quiet Tunnel. Under quiet flow conditions, the nozzle wall boundary layer remains laminar and grows very thick over the long nozzle length. This allows the development of large turbulent spots that can be readily measured with pressure transducers. Measurements of naturally occurring wave packets and developing turbulent spots were made. The peak frequencies of these natural wave packets were in agreement with second-mode computations. For a controlled study, the breakdown of disturbances created by spark and glow perturbations were studied at similar freestream conditions. The spark perturbations were the most effective at creating large wave packets that broke down into turbulent spots. The flow disturbances created by the controlled perturbations were analyzed to obtain amplitude criteria for nonlinearity and breakdown as well as the convection velocities of the turbulent spots. Disturbances first grew into linear instability waves and then quickly became nonlinear. Throughout the nonlinear growth of the wave packets, large harmonics are visible in the power spectra. As breakdown begins, the peak amplitudes of the instability waves and harmonics decrease into the rising broad-band frequencies. Instability waves are still visible on either side of the growing turbulent spots during this breakdown process.

  12. Impact-induced shock pressure distribution in a heterogeneous planetary interior

    NASA Astrophysics Data System (ADS)

    Arkani-Hamed, J.

    2012-12-01

    The shock pressure distribution inside planetary interiors has been investigated on the basis of scaling laws [1,2] and using numerical hydrocode models [2,3]. Here I present a new shock ray formulations derived on the basis of the Hugoniot equations to calculate the impact-induced shock pressure distribution inside heterogeneous terrestrial planets with radially varying physical parameters both in the solid mantle and in the underlying liquid core. Considering a single vertical impact, the formulations are derived in an axi-symmetric spherical coordinate system where the impact is assumed to occur at the north pole. In previous studies the scaling laws of shock pressure distribution [5] have been used to determine the impact heating of the planetary interiors by direct shock waves [2]. Because the main concern was the impact heating of the core, the heating of the antipodal region of the mantle was not investigated. The present study not only considers the impact heating of the entire planetary mantle by direct shock waves but also investigates the effects of the reflected shock waves inside the core. The direct shockwave propagating southward in the core intersects the core mantle boundary in the antipodal region where it partly transmits to the mantle and partly reflects back into the core. Both transmitted and reflected waves converge toward the axis of symmetry and create strong shock pressure near the axis in the antipodal region. Consequently, the antipodal region is significantly heated. In particular, the antipodal region of the core is heated twice, first by the direct shock wave as it propagates southward, and second by the reflected waves which actually increases in intensity close to the axis of symmetry. This feature has been demonstrated by the hydrocode models [3,4] but not by the scaling models based on direct shock wave propagation [1]. The new algorithm is applied to the impact heating of Mars, and the results are compared with those determined

  13. Pressure-induced superconductivity in Bi single crystals

    NASA Astrophysics Data System (ADS)

    Li, Yufeng; Wang, Enyu; Zhu, Xiyu; Wen, Hai-Hu

    2017-01-01

    Measurements on resistivity and magnetic susceptibility have been carried out for Bi single crystals under pressures up to 10.5 GPa. The temperature dependent resistivity shows a semimetallic behavior at ambient and low pressures (below about 1.6 GPa). This is followed by an upturn of resistivity in the low temperature region when the pressure is increased, which is explained as a semiconductor behavior. This feature gradually gets enhanced up to a pressure of about 2.52 GPa. Then a nonmonotonic temperature dependent resistivity appears upon further increasing pressure, which is accompanied by a strong suppression to the low temperature resistivity upturn. Simultaneously, a superconducting transition occurs at about 3.92 K under a pressure of about 2.63 GPa. With further increasing pressure, a second superconducting transition emerges at about 7 K under about 2.8 GPa. For these two superconducting states, the superconductivity induced magnetic screening volumes are quite large. As the pressure further increases to 8.1 GPa, we observe the third superconducting transition at about 8.2 K. The resistivity measurements under magnetic field allow us to determine the upper critical fields μ0Hc 2 of the superconducting phases. The upper critical field for the phase with Tc=3.92 K is extremely low. Based on the Werthamer-Helfand-Hohenberg (WHH) theory, the estimated value of μ0Hc 2 for this phase is about 0.103 T, while the upper critical field for the phase with Tc=7 K is very high with a value of about 4.56 T. Finally, we present a pressure dependent phase diagram of Bi single crystals. Our results reveal the interesting and rich physics in bismuth single crystals under high pressure.

  14. A New Mechanism for Pore Pressure Changes Induced by Distant Earthquakes

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.

    2001-12-01

    Observations during the Mw=7.3 1992 Landers earthquake, Mw=7.4 Izmit earthquake and Mw=7.2 Hector Mine earthquake suggest that seismicity is triggered hundreds of kilometers from a mainshock epicenter. This puzzling phenomenon is not explained by traditional elastic models of seismic stresses. The fact that the triggered sites are often geothermal or magmatic suggests that fluids may be an important part of the triggering process. Rapid changes in pore pressure either reduce the effective stress on faults locally or prompt hydrofracturing to initiate local earthquakes. The challenge is to discover how the seismic waves generate a change in pore fluid pressure. We constrain a mechanism for seismically-induced pore pressure changes by studying coseismic water level drops at a well in Grants Pass, Oregon. Water level drops at the site have been associated with earthquakes for nearly 20 years. High-sample rate (up to 1 Hz) digital water level data is available for the two coseismic drops that have occurred since 1994. The approach of this study is to use the amplification of the seismic waves in the well to constrain variations of the aquifer properties during the water level drops. We find that the amplification of the seismic waves in the well is consistent with standard theory for 7 digitally recorded events without drops, but during an earthquake with a drop a dramatic change in amplification occurs during the passage of the Rayleigh waves. The change in amplification indicates that the transmissivity increases by a factor of 50 during the 11 cm coseismic water level drop accompanying the 1999 Mw=7.5 1999 Oaxaca, Mexico earthquake. Based on these observations, we propose a new model for coseismic pore pressure changes. Drops occur if an earthquake occurs when the well has become temporarily clogged by a solid precipitate or sediment. The seismic shaking induces a flow which removes the obstruction. Once a barrier is removed, water flows rapidly to generate dramatic

  15. Development of laser-induced grating spectroscopy for underwater temperature measurement in shock wave focusing regions

    NASA Astrophysics Data System (ADS)

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

    2004-02-01

    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 gas-dynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm 3 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 are used to empirically establish the equation of states of water, gelatin or agar cell which will work as alternatives of human tissues.

  16. 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.

  17. Giant Deformations of a Liquid-Liquid Interface Induced by the Optical Radiation Pressure

    SciTech Connect

    Casner, Alexis; Delville, Jean-Pierre

    2001-07-30

    Because of the small momentum of photons, very intense fields are generally required to bend a liquid interface with the optical radiation pressure. We explore this issue in a near-critical phase-separated liquid mixture to vary continuously the meniscus softness by tuning the temperature. Low power continuous laser waves become sufficient to induce huge stationary bulges. Using the beam size to build an ''optical'' Bond number, Bo , we investigate the crossover from low to large Bo . The whole set of data collapses onto a single master curve which illustrates the universality of the phenomenon.

  18. Use of Z-pinch sources for high-pressure shock wave studies

    SciTech Connect

    Konrad, C.H.; Asay, J.R.; Hall, C.A.

    1998-01-01

    In this paper, we will discuss the use of z-pinch sources for shock wave studies at multi-Mbar pressures. Experimental plans to use the technique for absolute shock Hugoniot measurements are discussed. Recent developments have demonstrated the use of pulsed power techniques for producing intense radiation sources (Z pinches) for driving planar shock waves in samples with spatial dimensions significantly larger than possible with other radiation sources. Initial indications are that using Z pinch sources for producing Planckian radiation sources in secondary hohlraums can be used to drive shock waves in samples with diameters to a few millimeters and thickness approaching one millimeter in thickness. These dimensions provides the opportunity to measure both shock velocity and the particle velocity behind the shock front with accuracy comparable to that obtained with gun launchers. In addition, the peak hohlraum temperatures of nearly 150 eV that are now possible with Z pinch sources result in shock wave pressures approaching 45 Mbar in high impedance materials such as tungsten and 10-15 Mbar in low impedance materials such as aluminum and plastics. In this paper, we discuss the use of Z pinch sources for making accurate absolute EOS measurements in the megabar pressure range.

  19. Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

    SciTech Connect

    Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo

    1995-09-01

    In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that there exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.

  20. Kinetic model of ionization waves in a positive column at intermediate pressures in inert gases.

    PubMed

    Golubovskii, Y B; Maiorov, V A; Nekutchaev, V O; Behnke, J; Behnke, J F

    2001-03-01

    A kinetic model of ionization waves in the inert gas discharge is constructed, which is based on the simultaneous solution of the kinetic equation for electrons and the continuity equations for ions and excited atoms. The model corresponds to a range of intermediate pressures and small currents, when elastic collisions dominate in the electron energy balance and electron-electron collisions are negligibly small. A linear theory of ionization waves is constructed, growth rates and frequencies of wave disturbances able to propagate in plasma are found. It is shown that there is an upper bound to the existence of striations by pressure, as well as the lower bound by current. The self-consistent solution of the source system of equations is obtained, which describes a nonlinear wave. The profile of electric field and the electron distribution function in this field are calculated. The results of calculations are compared with the experimental data. The wavelengths obtained are essentially larger than the electron energy relaxation length. Such waves cannot be described within the limits of fluid models.

  1. Ventricular size and isotope cisternography in patients with acute transient rises of intracranial pressure (plateau waves)

    SciTech Connect

    Hayashi, M.; Kobayashi, H.; Fujii, H.; Yamamoto, S.

    1982-12-01

    The size of the ventricular system and cerebrospinal fluid (CSF) flow were determined in 17 patients with plateau waves, using computerized tomography (CT) and isotope cisternography. Some patients had increased intracranial pressure (ICP) resulting from space-occupying lesions and other causes, and some had normal ICP observed in normal-pressure hydrocephalus. The size and shape of the ventricular system during plateau wave phases as ascertained by CT showed little or no change as compared with its size and shape during the interval phases between two waves. It was also noticed that, in patients with supratentorial masses, the midline shift showed no difference in degree between the two phases. These findings suggest that there is little change in the intracranial CSF volume between the two phases, that is, there is little compensatory outflow of the intracranial CSF for the ICP variations. These results may also support the assumption that the plateau waves are not caused by an intermittent obstruction of the CSF pathways. Isotope cisternography showed a marked delay of clearance of radioactivity from the intracranial CSF in 15 patients. The cisternographic pattern in patients with increased ICP and the absence of ventricular dilatation demonstrated an abnormally large accumulation of radioactivity over the cerebral convexities, and the pattern in patients with normal-pressure hydrocephalus showed complete obstruction of the subarachnoid space over both cerebral convexities. These observations suggest that, in patients with plateau waves, there is a marked delay in CSF absorption. The authors postulate that the reduction of CSF absorption may create a critically tight condition within the cranial cavity and act as a contributory factor in the development of the plateau waves.

  2. Shock wave induced phase transition in α -FePO 4

    NASA Astrophysics Data System (ADS)

    Joshi, K. D.; Suresh, N.; Jyoti, G.; Kulshreshtha, S. K.; Gupta, S. C.; Sikka, S. K.

    Shock wave induced response of the berlinite form of FePO 4 has been investigated up to 8.5 GPa. The X-ray diffraction measurements on the shock recovered samples reveal transition to the mixture of an amorphous phase and an orthorhombic phase around 5 GPa. The proportion of the amorphous material in the recovered sample is found to decrease at higher pressure. The results are interpreted in terms of a three-level free energy diagram for the crystal to amorphous transitions.

  3. Superconductivity and magnetic field induced spin density waves in the (TMTTF)2X family

    NASA Astrophysics Data System (ADS)

    Balicas, L.; Behnia, K.; Kang, W.; Canadell, E.; Auban-Senzier, P.; Jérome, D.; Ribault, M.; Fabre, J. M.

    1994-10-01

    We report magnetotransport measurements in the quasi one dimensional (Q-1-D) organic conductor (TMTTF)2Br at pressures up to 26 kbar, clown to 0.45 K in magnetic fields up to 19 T along the c^{ast} direction. It is found that a superconducting ground state is stabilized under 26 kbar at T_C = 0.8 K. No magnetic field induced spin density wave (FISDW) transitions are observed below 19T unlike other Q-1-D superconductors pertaining to the selenium series. The computed amplitude of the interchain coupling along transverse directions is unable to explain the missing; FISDW instability.

  4. Characterization of a setup to test the impact of high-amplitude pressure waves on living cells.

    PubMed

    Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O

    2014-01-24

    The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction.

  5. Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells

    PubMed Central

    Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

    2014-01-01

    The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction. PMID:24458018

  6. Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells

    NASA Astrophysics Data System (ADS)

    Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

    2014-01-01

    The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction.

  7. A new modeling approach of pressure waves at the inlet of internal combustion engines

    NASA Astrophysics Data System (ADS)

    Chalet, David; Mahé, Alexandre; Hétet, Jean-François; Migaud, Jérôme

    2011-06-01

    This paper presents a new model used to describe the propagation of pressure waves at the inlet systems of internal combustion engine. In the first part, an analogy is made between the compressible air in a pipe and a mechanical ideal mass damper spring system. A new model is then presented and the parameters of this model are determined by the use of an experimental setup (shock tube test bench). With this model, a transfer function is defined in order to link directly the pressure and the air mass flow rate. In the second part, the model is included into an internal combustion engine simulation code. The results obtained with this code are compared to experimental ones which are measured on a one-cylinder engine test bench. This last one is driven by an electric motor in order to study only the effect of the pressure waves on the engine behavior. A good agreement is obtained between the experimental results and the numerical ones and the new approach is an alternative method for modeling the pressure wave phenomena in an internal combustion engine manifold.

  8. Pressure wave measurements from thermal cook-off of an HMX based high explosive

    SciTech Connect

    Forbes, J W; Tarver, C M; Urtiew, P A; Garcia, F; Greenwood, D W; Vandersall, K S

    2000-10-10

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  9. Pressure Wave Measurements from Thermal Cook-off of an HMX Based Explosive

    SciTech Connect

    Forbes, J W; Tarver, C M; Urtiew, P A; Garcia, F; Greenwood, D W; Vandersall, K S

    2001-05-09

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  10. Pressure Wave Measurements from Thermal Cook-Off of an HMX Based High Explosive PBX 9501

    SciTech Connect

    Garcia, F; Forbes, J W; Tarver, C M; Urtiew, P A; Greenwood, D W; Vandersall, K S

    2001-05-31

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  11. Estimated Pulse Wave Velocity Calculated from Age and Mean Arterial Blood Pressure

    PubMed Central

    Greve, Sara V.; Laurent, Stephan; Olsen, Michael H.

    2017-01-01

    In a recently published paper, Greve et al [J Hypertens 2016;34:1279-1289] investigate whether the estimated carotid-femoral pulse wave velocity (ePWV), calculated using an equation derived from the relationship between carotid-femoral pulse wave velocity (cfPWV), age, and blood pressure, predicts cardiovascular disease (CVD) as good as the measured cfPWV. Because ePWV predicts CVD as good as cfPWV, some might wonder whether ePWV could be replaced by cfPWV, which is a time-consuming measurement requiring an expensive apparatus. This question is addressed in this mini-review. PMID:28229052

  12. Superconductivity of Al/Al2O3 interface formed by shock-wave pressure

    NASA Astrophysics Data System (ADS)

    Palnichenko, A. V.; Shakhrai, D. V.; Avdonin, V. V.; Vyaselev, O. M.; Khasanov, S. S.

    2015-05-01

    A mixture of Al and α -Al2O3 has been subjected to a shock-wave pressure of ≃ 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 37 K, characterized by glassy dynamics of the shielding currents below Tc . Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic Al and its oxide due to the shock-wave treatment.

  13. Superconductivity of Cu/CuOx interface formed by shock-wave pressure

    NASA Astrophysics Data System (ADS)

    Shakhray, D. V.; Avdonin, V. V.; Palnichenko, A. V.

    2016-11-01

    A mixture of powdered Cu and CuO has been subjected to shock-wave pressure of 350 kbar with following quenching of the vacuum-encapsulated product to 77 K. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 19 K, characterized by glassy dynamics of the shielding currents below Tc . Comparison of the ac susceptibility and the DC magnetization measurements infers that the superconductivity arises within the granular interfacial layer formed between metallic Cu and its oxides due to the shock-wave treatment.

  14. Superconductivity of Cu/CuOx interface formed by shock-wave pressure

    NASA Astrophysics Data System (ADS)

    Palnichenko, A. V.; Sidorov, N. S.; Shakhrai, D. V.; Avdonin, V. V.; Vyaselev, O. M.; Khasanov, S. S.

    2014-03-01

    A mixture of powdered Cu and CuO has been subjected to a shock-wave pressure of ≃350 kbar with following quenching of the vacuum-encapsulated product to ≈77 K. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc≈19.5 K, characterized by glassy dynamics of the shielding currents below Tc. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the granular interfacial layer formed between metallic Cu and its oxides due to the shock-wave treatment.

  15. Wave propagation with different pressure signals: an experimental study on the latex tube.

    PubMed

    Ursino, M; Artioli, E; Gallerani, M

    1993-07-01

    To have deeper insight into the main factors affecting wave propagation in real hydraulic lines, we measured the true propagation coefficient in two latex rubber tubes via the three-point pressure method. The measurements were performed using both sinusoidal pressure signals of different amplitudes and periodic square waves as well as aperiodic pressure impulses. The results obtained were then compared with those predicted by a classic linear model valuable for a purely elastic maximally tethered tube. Our measurements demonstrate that the three-point pressure method may introduce significant errors at low frequencies (below 1 Hz in the present experiments) when the distance between two consecutive transducers becomes much lower than the wavelength. The pattern of phase velocity in the range 2-20 Hz turns out to be about 10 per cent higher than the theoretical one computed using the static value of the Young modulus. This result supports the idea that the dynamic Young modulus of the material is slightly higher than that measured in static conditions. The experimental attenuation per wavelength is significantly higher than the theoretical one over most of the frequencies examined, and settles at a constant value as frequency increases. Introduction of wall viscoelasticity in the theoretical model can explain only a portion of the observed high frequency damping and wave attenuation. Finally, increasing the amplitude of pressure changes significantly affects the measured value of the propagation coefficient, especially at those frequencies for which direct and reflected waves sum together in a positive fashion. In these conditions we observed a moderate increase in phase velocity and a much more evident increase in attenuation per wavelength.

  16. Tracking Ocean Gravity Waves in Real-time: Highlights of Bottom Pressure Data Recorded on Ocean Networks Canada's NEPTUNE observatory

    NASA Astrophysics Data System (ADS)

    Heesemann, Martin; Mihaly, Steve; Gemmrich, Johannes; Davis, Earl; Thomson, Richard; Dewey, Richard

    2016-04-01

    Ocean Networks Canada operates two cabled ocean observatories off Vancouver Island on Canada's west coast. The regional NEPTUNE observatory spans the entire Juan de Fuca tectonic plate from the coast across the subduction zone to the hydrothermally active Endeavour Segment of the Juan de Fuca Ridge Segment while the VENUS observatory focuses on coastal processes. Both observatories collect data on physical, chemical, biological, and geological aspects of the ocean over long time periods, supporting research on complex earth processes. High-precision bottom pressure recorders (BPR) deployed on the NEPTUNE observatory are capable of detecting a wide range of phenomena related to sea level variations. The observatory BPRs provide observations of nano-resolution (with respect to full scale of the instrument) pressure variations which correspond to sub-millimeter scale surface water displacements in several kilometers of water. Detected signals include tides, tsunamis, infragravity waves, swell, wave-induced microseisms, storm surge, and seismic signals. Spectral analysis reveals many of these phenomena with periods ranging from a few seconds to many hours. Dispersion patterns from distant swells are prominent in the swell and microseism bands. By comparing the difference of arrival times between longer period waves, which arrive first, and shorter period waves we can estimate the distance the swells travelled since they were generated. Using this information, swell can be tracked back to specific storms across the Pacific. The presentation will high-light some examples of the mentioned phenomena in the continuous time-series that in some instances are more than seven years long.

  17. Radial energy transport by magnetospheric ULF waves: Effects of magnetic curvature and plasma pressure

    NASA Technical Reports Server (NTRS)

    Kouznetsov, Igor; Lotko, William

    1995-01-01

    The 'radial' transport of energy by internal ULF waves, stimulated by dayside magnetospheric boundary oscillations, is analyzed in the framework of one-fluid magnetohydrodynamics. (the term radial is used here to denote the direction orthogonal to geomagnetic flux surfaces.) The model for the inhomogeneous magnetospheric plasma and background magnetic field is axisymmetric and includes radial and parallel variations in the magnetic field, magnetic curvature, plasma density, and low but finite plasma pressure. The radial mode structure of the coupled fast and intermediate MHD waves is determined by numerical solution of the inhomogeneous wave equation; the parallel mode structure is characterized by a Wentzel-Kramer-Brillouin (WKB) approximation. Ionospheric dissipation is modeled by allowing the parallel wave number to be complex. For boudnary oscillations with frequencies in the range from 10 to 48 mHz, and using a dipole model for the background magnetic field, the combined effects of magnetic curvature and finite plasma pressure are shown to (1) enhance the amplitude of field line resonances by as much as a factor of 2 relative to values obtained in a cold plasma or box-model approximation for the dayside magnetosphere; (2) increase the energy flux delivered to a given resonance by a factor of 2-4; and (3) broaden the spectral width of the resonance by a factor of 2-3. The effects are attributed to the existence of an 'Alfven buoyancy oscillation,' which approaches the usual shear mode Alfven wave at resonance, but unlike the shear Alfven mode, it is dispersive at short perpendicular wavelengths. The form of dispersion is analogous to that of an internal atmospheric gravity wave, with the magnetic tension of the curved background field providing the restoring force and allowing radial propagation of the mode. For nominal dayside parameters, the propagation band of the Alfven buoyancy wave occurs between the location of its (field line) resonance and that of the

  18. Shock-wave-induced fracturing of calcareous nannofossils from the Chesapeake Bay impact crater

    USGS Publications Warehouse

    ,

    2003-01-01

    Fractured calcareous nannofossils of the genus Discoaster from synimpact sediments within the Chesapeake Bay impact crater demonstrate that other petrographic shock indicators exist for the cratering process in addition to quartz minerals. Evidence for shock-induced taphonomy includes marginal fracturing of rosette-shaped Discoaster species into pentagonal shapes and pressure- and temperature-induced dissolution of ray tips and edges of discoasters. Rotational deformation of individual crystallites may be the mechanism that produces the fracture pattern. Shock-wave-fractured calcareous nannofossils were recovered from synimpact matrix material representing tsunami or resurge sedimentation that followed impact. Samples taken from cohesive clasts within the crater rubble show no evidence of shock-induced fracturing. The data presented here support growing evidence that microfossils can be used to determine the intensity and timing of wet-impact cratering.

  19. Evidence of the Correspondence of EIT Waves and Coronal Mass Ejections Induced Waves Using a Three-Dimensional Magnetohydrodynamic Simulation

    NASA Astrophysics Data System (ADS)

    Wu, S. T.; Wu, C.-C.; Liou, K.

    2013-04-01

    Before the discovery of EIT waves and coronal mass ejections (CMEs) it was already known that Moreton waves were observed to propagate across the solar disk during some solar flares. This magnetohydrodynamic wave was explained as the intersecting line between the edge of an expanding global coronal wavefront and the chromosphere (Uchida, 1968) where Uchida concluded that the Moreton wave was a fast mode MHD wave. In this presentation, we will show that the EIT wave could be a part of a CME induced wave propagating across the solar disk. To illustrate this scenario, we have employed a global 3D MHD model (Wu et al. 2001) to simulate this phenomenon for the May 12, 1997 event which was an Earth-directed CME observed by SOHO/EIT (Thompson et al. 1998). To carry out this simulation, the measured global magnetic fields obtained from the Stanford University Wilcox Solar Observatory (WSO) were used as the inputs to the simulation model. We were able to show that the scenario suggested by Uchida (1968), namely, the observed EIT wave propagating across the solar disk could be caused by the intersection line between the edge of an expanding CME induced wave front and the chromosphere. In addition to the flare source scenario, we concluded that an EIT (or EUV) wave can also be a part of a flare induced coronal wave with its foot print on the Sun's surface.

  20. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves.

    PubMed

    Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef

    2016-06-02

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

  1. Arterial pulse pressure amplification described by means of a nonlinear wave model: characterization of human aging

    NASA Astrophysics Data System (ADS)

    Alfonso, M.; Cymberknop, L.; Armentano, R.; Pessana, F.; Wray, S.; Legnani, W.

    2016-04-01

    The representation of blood pressure pulse as a combination of solitons captures many of the phenomena observed during its propagation along the systemic circulation. The aim of this work is to analyze the applicability of a compartmental model for propagation regarding the pressure pulse amplification associated with arterial aging. The model was applied to blood pressure waveforms that were synthesized using solitons, and then validated by waveforms obtained from individuals from differentiated age groups. Morphological changes were verified in the blood pressure waveform as a consequence of the aging process (i.e. due to the increase in arterial stiffness). These changes are the result of both a nonlinear interaction and the phenomena present in the propagation of nonlinear mechanic waves.

  2. Reduction of fluctuating pressure loads in shock wave turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Barter, John W.; Dolling, David S.

    1995-01-01

    Fluctuating surface pressure measurements have been made to investigate the effectiveness of boundary layer separators (BLS's) in reducing the fluctuating pressure loads produced by separated shock wave turbulent boundary layer interactions. Measurements have been made under unswept and swept compression corner interactions in a Mach 5 flow. BLS's fix the separation location and eliminate the large-amplitude, low-frequency fluctuating pressure loads upstream of the compression corners. The loads on the unswept compression corner face are reduced by as much as 59%. The BLS's also shift the mean pressure distribution on the unswept corner face in the streamwise direction. Results show that the loads on the corner face vary with the BLS height and the distance between the BLS and the compression corner. Suggestions for the optimum placement and the use of the BLS's are also made.

  3. Negative pressures and spallation in water drops subjected to nanosecond shock waves

    SciTech Connect

    Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.; Koglin, Jason E.; Liang, Mengning; Aquila, Andrew L.; Robinson, Joseph S.; Gumerlock, Karl L.; Blaj, Gabriel; Sierra, Raymond G.; Boutet, Sebastien; Guillet, Serge A. H.; Curtis, Robin H.; Vetter, Sharon L.; Loos, Henrik; Turner, James L.; Decker, Franz -Josef

    2016-05-16

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPa were reached in the drops. As a result, we model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

  4. Negative pressures and spallation in water drops subjected to nanosecond shock waves

    DOE PAGES

    Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.; ...

    2016-05-16

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPamore » were reached in the drops. As a result, we model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.« less

  5. Analysis of Wave Fields induced by Offshore Pile Driving

    NASA Astrophysics Data System (ADS)

    Ruhnau, M.; Heitmann, K.; Lippert, T.; Lippert, S.; von Estorff, O.

    2015-12-01

    Impact pile driving is the common technique to install foundations for offshore wind turbines. With each hammer strike the steel pile - often exceeding 6 m in diameter and 80 m in length - radiates energy into the surrounding water and soil, until reaching its targeted penetration depth. Several European authorities introduced limitations regarding hydroacoustic emissions during the construction process to protect marine wildlife. Satisfying these regulations made the development and application of sound mitigation systems (e.g. bubble curtains or insulation screens) inevitable, which are commonly installed within the water column surrounding the pile or even the complete construction site. Last years' advances have led to a point, where the seismic energy tunneling the sound mitigation systems through the soil and radiating back towards the water column gains importance, as it confines the maximum achievable sound mitigation. From an engineering point of view, the challenge of deciding on an effective noise mitigation layout arises, which especially requires a good understanding of the soil-dependent wave field. From a geophysical point of view, the pile acts like a very unique line source, generating a characteristic wave field dominated by inclined wave fronts, diving as well as head waves. Monitoring the seismic arrivals while the pile penetration steadily increases enables to perform quasi-vertical seismic profiling. This work is based on datasets that have been collected within the frame of three comprehensive offshore measurement campaigns during pile driving and demonstrates the potential of seismic arrivals induced by pile driving for further soil characterization.

  6. Chiral primordial gravitational waves from dilaton induced delayed chromonatural inflation

    NASA Astrophysics Data System (ADS)

    Obata, Ippei; Soda, Jiro; CLEO Collaboration

    2016-06-01

    We study inflation driven by a dilaton and an axion, both of which are coupled to a SU(2) gauge field. We find that the inflation driven by the dilaton occurs in the early stage of inflation during which the gauge field grows due to the gauge-kinetic function. When the energy density of magnetic fields catches up with that of electric fields, chromonatural inflation takes over in the late stage of inflation, which we call delayed chromonatural inflation. Thus, the delayed chromonatural inflation driven by the axion and the gauge field is induced by the dilaton. The interesting outcome of the model is the generation of chiral primordial gravitational waves on small scales. Since the gauge field is inert in the early stage of inflation, it is viable in contrast to the conventional chromonatural inflation. We find the parameter region where chiral gravitational waves are generated in a frequency range higher than nHz, which are potentially detectable in future gravitational wave interferometers and pulsar-timing arrays such as DECi-hertz Interferometer Gravitational wave Observatory (DECIGO), evolved Laser Interferometer Space Antenna (eLISA), and Square Kilometer Array (SKA).

  7. The stress-induced surface wave velocity variations in concrete

    NASA Astrophysics Data System (ADS)

    Spalvier, Agustin; Bittner, James; Evani, Sai Kalyan; Popovics, John S.

    2017-02-01

    This investigation studies the behavior of surface wave velocity in concrete specimens subjected to low levels of compressive and tensile stress in beams from applied flexural loads. Beam specimen is loaded in a 4-point-load bending configuration, generating uniaxial compression and tension stress fields at the top and bottom surfaces of the beam, respectively. Surface waves are generated through contactless air-coupled transducers and received through contact accelerometers. Results show a clear distinction in responses from compression and tension zones, where velocity increases in the former and decreases in the latter, with increasing load levels. These trends agree with existing acoustoelastic literature. Surface wave velocity tends to decrease more under tension than it tends to increase under compression, for equal load levels. It is observed that even at low stress levels, surface wave velocity is affected by acoustoelastic effects, coupled with plastic effects (stress-induced damage). The acoustoelastic effect is isolated by means of considering the Kaiser effect and by experimentally mitigating the viscoelastic effects of concrete. Results of this ongoing investigation contribute to the overall knowledge of the acoustoelastic behavior of concrete. Applications of this knowledge may include structural health monitoring of members under flexural loads, improved high order modelling of materials, and validation of results seen in dynamic acoustoelasticity testing.

  8. CMOS-compatible ruggedized high-temperature Lamb wave pressure sensor

    NASA Astrophysics Data System (ADS)

    Kropelnicki, P.; Muckensturm, K.-M.; Mu, X. J.; Randles, A. B.; Cai, H.; Ang, W. C.; Tsai, J. M.; Vogt, H.

    2013-08-01

    This paper describes the development of a novel ruggedized high-temperature pressure sensor operating in lateral field exited (LFE) Lamb wave mode. The comb-like structure electrodes on top of aluminum nitride (AlN) were used to generate the wave. A membrane was fabricated on SOI wafer with a 10 µm thick device layer. The sensor chip was mounted on a pressure test package and pressure was applied to the backside of the membrane, with a range of 20-100 psi. The temperature coefficient of frequency (TCF) was experimentally measured in the temperature range of -50 °C to 300 °C. By using the modified Butterworth-van Dyke model, coupling coefficients and quality factor were extracted. Temperature-dependent Young's modulus of composite structure was determined using resonance frequency and sensor interdigital transducer (IDT) wavelength which is mainly dominated by an AlN layer. Absolute sensor phase noise was measured at resonance to estimate the sensor pressure and temperature sensitivity. This paper demonstrates an AlN-based pressure sensor which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications.

  9. Elastic wave velocities of lunar samples at high pressures and their geophysical implications.

    PubMed

    Kanamori, H; Nur, A; Chung, D; Wones, D; Simmons, G

    1970-01-30

    Ultrasonic measurement of P and S velocities of Apollo 11 lunar samples 10020, 10057, and 10065 to 5 kilobars pressure at room temperature shows a pronounced increase of velocity (as much as twofold) for the first 2 kilobars. The travel times predicted from the velocity-depth curve of sample 10057 are consistent with the results of the Apollo 12 seismic experiments. At pressures below 200 bars, the samples are highly attenuating; for both P and S waves, the value of Q is about 10.

  10. New experimental capabilities and theoretical insights of high pressure compression waves

    SciTech Connect

    Orlikowski, D; Nguyen, J; Patterson, J R; Minich, R; Martin, L P; Holmes, N

    2007-07-20

    Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition of water plus its associated phase fraction history. We also introduce the Korteweg-deVries-Burgers equation as a means to understand the evolution these RWC waves that propagate through the thickness of the subject material. This equation has the necessary competition between non-linear, dispersion, and dissipation processes, which is shown through observed structures that are manifested in the experimental particle velocity histories. Such methodology points towards a possible quantifiable dissipation, through which RWC experiments may be analyzed.

  11. Instantaneous and efficient surface wave excitation of a low pressure gas or gases

    DOEpatents

    Levy, Donald J.; Berman, Samuel M.

    1988-01-01

    A system for instantaneously ionizing and continuously delivering energy in the form of surface waves to a low pressure gas or mixture of low pressure gases, comprising a source of rf energy, a discharge container, (such as a fluorescent lamp discharge tube), an rf shield, and a coupling device responsive to rf energy from the source to couple rf energy directly and efficiently to the gas or mixture of gases to ionize at least a portion of the gas or gases and to provide energy to the gas or gases in the form of surface waves. The majority of the rf power is transferred to the gas or gases near the inner surface of the discharge container to efficiently transfer rf energy as excitation energy for at least one of the gases. The most important use of the invention is to provide more efficient fluorescent and/or ultraviolet lamps.

  12. Kinetics of motility-induced phase separation and swim pressure

    NASA Astrophysics Data System (ADS)

    Patch, Adam; Yllanes, David; Marchetti, M. Cristina

    2017-01-01

    Active Brownian particles (ABPs) represent a minimal model of active matter consisting of self-propelled spheres with purely repulsive interactions and rotational noise. Here we examine the pressure of ABPs in two dimensions in both closed boxes and systems with periodic boundary conditions and show that its nonmonotonic behavior with density is a general property of ABPs and is not the result of finite-size effects. We correlate the time evolution of the mean pressure towards its steady-state value with the kinetics of motility-induced phase separation. For parameter values corresponding to phase-separated steady states, we identify two dynamical regimes. The pressure grows monotonically in time during the initial regime of rapid cluster formation, overshooting its steady-state value and then quickly relaxing to it, and remains constant during the subsequent slower period of cluster coalescence and coarsening. The overshoot is a distinctive feature of active systems.

  13. Atomistic pathways of the pressure-induced densification of quartz

    NASA Astrophysics Data System (ADS)

    Liang, Yunfeng; Miranda, Caetano R.; Scandolo, Sandro

    2015-10-01

    When quartz is compressed at room temperature it retains its crystal structure at pressures well above its stability domain (0-2 GPa), and collapses into denser structures only when pressure reaches 20 GPa. Depending on the experimental conditions, pressure-induced densification can be accompanied by amorphization; by the formation of crystalline, metastable polymorphs; and can be preceded by the appearance of an intermediate phase, quartz II, with unknown structure. Based on molecular dynamic simulations, we show that this rich phenomenology can be rationalized through a unified theoretical framework of the atomistic pathways leading to densification. The model emphasizes the role played by the oxygen sublattice, which transforms from a bcc-like order in quartz into close-packed arrangements in the denser structures, through a ferroelastic instability of martensitic nature.

  14. Carbon dioxide pressure-induced coagulation of microalgae.

    PubMed

    Lee, Roland; Jessop, Philip G; Champagne, Pascale

    2015-12-28

    The move to a low-carbon economy has generated renewed interest in microalgae for the production of biofuels with the potential mutual benefit of wastewater treatment. However, harvesting has been identified as a limiting factor to the economic viability of this process. This paper explores the harvesting of microalgae using high-pressure gas without the addition of coagulants. Coagulation of microalgae under high-pressure gas was found to be an efficient method to separate algae from suspension. The critical coagulation pressures (CCPs) for H(2) and CO(2) were determined to be 6.1 and 6.2 MPa, respectively. The CO(2)-induced decrease in solution pH positively influenced coagulation rates, without appearing to affect the CCP. This approach could be beneficial for the economic removal of microalgae from solution for the production of both biofuels and biomedical compounds without the addition of non-environmentally friendly chemicals.

  15. Anisotropic poroelasticity and wave-induced fluid flow: harmonic finite-element simulations

    NASA Astrophysics Data System (ADS)

    Carcione, J. M.; Santos, J. E.; Picotti, S.

    2011-09-01

    A dominant P-wave attenuation mechanism in reservoir rocks at seismic frequencies is due to wave-induced fluid flow (mesoscopic loss). The P-wave induces a fluid-pressure difference at mesoscopic-scale inhomogeneities (larger than the pore size but smaller than the wavelength), generating fluid flow and slow (diffusion) Biot waves. The theory has been developed in the 1970s for the symmetry axis of the equivalent transversely isotropic (TI) medium corresponding to a finely layered medium, and has recently been generalized to all propagation angles. The new theory states that the fluid-flow direction is perpendicular to the layering plane and it is independent of the loading direction. As a consequence, the relaxation behaviour can be described by a single relaxation function, since the medium consists of plane homogeneous layers. Besides P-wave losses, the coupling between the qP and qSV waves generates shear-wave anisotropic velocity dispersion and attenuation. In this work, we introduce a set of quasi-static numerical experiments to determine the equivalent viscoelastic TI medium to a finely layered poroelastic medium, which is validated using a recently developed analytical solution. The modelling technique is the finite-element (FE) method, where the equations of motion are solved in the space-frequency domain. Numerical rock physics may, in many circumstances, offer an alternative to laboratory measurements. Numerical experiments are inexpensive and informative since the physical process of wave propagation can be inspected during the experiment. Moreover, they are repeatable, essentially free from experimental errors, and may easily be run using alternative models of the rock and fluid properties. We apply the methodology to the Utsira aquifer of the North Sea, where carbon dioxide (CO2) has been injected during the last 15 years. The tests consider alternating layers of the same rock saturated with gas and brine and a sequence of gas-saturated sandstone and

  16. Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    SciTech Connect

    Guzatov, D V; Gaida, L S; Afanas'ev, Anatolii A

    2008-12-31

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves. (light pressure)

  17. Nonlinear acoustics in a dispersive continuum: Random waves, radiation pressure, and quantum noise

    NASA Astrophysics Data System (ADS)

    Cabot, M. A.

    The nonlinear interaction of sound with sound is studied using dispersive hydrodynamics which derived from a variational principle and the assumption that the internal energy density depends on gradients of the mass density. The attenuation of sound due to nonlinear interaction with a background is calculated and is shown to be sensitive to both the nature of the dispersion and decay bandwidths. The theoretical results are compared to those of low temperature helium experiments. A kinetic equation which described the nonlinear self-inter action of a background is derived. When a Deybe-type cutoff is imposed, a white noise distribution is shown to be a stationary distribution of the kinetic equation. The attenuation and spectrum of decay of a sound wave due to nonlinear interaction with zero point motion is calculated. In one dimension, the dispersive hydrodynamic equations are used to calculate the Langevin and Rayleigh radiation pressures of wave packets and solitary waves.

  18. Relationship between Orientation to a Blast and Pressure Wave Propagation Inside the Rat Brian

    DTIC Science & Technology

    2011-01-01

    generated during an explosion may result in brain damage anll related neuro- logical impairments. Several mechanisms by which the primary blast wave can...CSF). to the central nervous system. To address a basic question related to the mechanisms of blast brain injury. pressure was measured inside the...can damage the bra in have been pro- posed, includi ng: ( 1) mechanical displacement of brain resulting in contusions and hemorrhages and direct

  19. The vibration of a box-type structure. II - Response to a travelling pressure wave.

    NASA Technical Reports Server (NTRS)

    Popplewell, N.

    1971-01-01

    A finite element method is formulated for determining the transient response of a box-type structure to a traveling, arbitrarily shaped pressure wave. The method is illustrated by considering an example of practical concern - the sonic boom. The acceleration-time histories of a closed box are compared with those obtained experimentally from a simulated boom. Satisfactory agreement is obtained with only four rectangular elements per individual face and a simplified loading of the box.

  20. Pressure-induced exotic states in rare earth hexaborides

    NASA Astrophysics Data System (ADS)

    Sun, Liling; Wu, Qi

    2016-08-01

    Finding the exotic phenomena in strongly correlated electron systems (SCESs) and understanding the corresponding microphysics have long been the research frontiers of condensed matter physics. The remarkable examples for the intriguing phenomena discovered in past years include unconventional superconductivity, heavy Fermion behaviors, giant magneto-resistance and so on. A fascinating type of rare earth hexaboride RB6 (R  =  Sm, Yb, Eu and Ce) belongs to a strongly correlated electron system (SCES), but shows unusual ambient-pressure and high-pressure behaviors beyond the phenomena mentioned above. Particularly, the recent discovery of the coexistence of an unusual metallic surface state and an insulating bulk state in SmB6, known to be a Kondo insulator decades ago, by theoretical calculations and many experimental measurements creates new interest for the investigation of the RB6. This significant progress encourages people to revisit the RB6 with an attempt to establish a new physics that links the SCES and the unusual metallic surface state which is a common feature of a topological insulator (TI). It is well known that pressure has the capability of tuning the electronic structure and modifying the ground state of solids, or even inducing a quantum phase transition which is one of the kernel issues in studies of SCESs. In this brief review, we will describe the progress in high pressure studies on the RB6 based on our knowledge and research interests, mainly focusing on the pressure-induced phenomena in YbB6 and SmB6, especially on the quantum phase transitions and their connections with the valence state of the rare earth ions. Moreover, some related high-pressure results obtained from CeB6 and EuB6 are also included. Finally, a summary is given in the conclusions and perspectives section.

  1. Pressure-induced exotic states in rare earth hexaborides.

    PubMed

    Sun, Liling; Wu, Qi

    2016-08-01

    Finding the exotic phenomena in strongly correlated electron systems (SCESs) and understanding the corresponding microphysics have long been the research frontiers of condensed matter physics. The remarkable examples for the intriguing phenomena discovered in past years include unconventional superconductivity, heavy Fermion behaviors, giant magneto-resistance and so on. A fascinating type of rare earth hexaboride RB6 (R  =  Sm, Yb, Eu and Ce) belongs to a strongly correlated electron system (SCES), but shows unusual ambient-pressure and high-pressure behaviors beyond the phenomena mentioned above. Particularly, the recent discovery of the coexistence of an unusual metallic surface state and an insulating bulk state in SmB6, known to be a Kondo insulator decades ago, by theoretical calculations and many experimental measurements creates new interest for the investigation of the RB6. This significant progress encourages people to revisit the RB6 with an attempt to establish a new physics that links the SCES and the unusual metallic surface state which is a common feature of a topological insulator (TI). It is well known that pressure has the capability of tuning the electronic structure and modifying the ground state of solids, or even inducing a quantum phase transition which is one of the kernel issues in studies of SCESs. In this brief review, we will describe the progress in high pressure studies on the RB6 based on our knowledge and research interests, mainly focusing on the pressure-induced phenomena in YbB6 and SmB6, especially on the quantum phase transitions and their connections with the valence state of the rare earth ions. Moreover, some related high-pressure results obtained from CeB6 and EuB6 are also included. Finally, a summary is given in the conclusions and perspectives section.

  2. Pressure-induced phase transition and polymerization of tetracyanoethylene (TCNE)

    NASA Astrophysics Data System (ADS)

    Tomasino, Dane; Chen, Jing-Yin; Kim, Minesob; Yoo, Choong-Shik

    2013-03-01

    We have studied the pressure-induced physical and chemical transformations of tetracyanoethylene (TCNE or C6N4) in diamond anvil cells using micro-Raman spectroscopy, laser-heating, emission spectroscopy, and synchrotron x-ray diffraction. The results indicate that TCNE in a quasi-hydrostatic condition undergoes a shear-induced phase transition at 10 GPa and then a chemical change to two-dimensional (2D) C=N polymers above 14 GPa. These phase and chemical transformations depend strongly on the state of stress in the sample and occur sluggishly in non-hydrostatic conditions over a large pressure range between 7 and 14 GPa. The x-ray diffraction data indicate that the phase transition occurs isostructurally within the monoclinic structure (P21/c) without any apparent volume discontinuity and the C=N polymer is highly disordered but remains stable to 60 GPa—the maximum pressure studied. On the other hand, laser-heating of the C=N polymer above 25 GPa further converts to a theoretically predicted 3D C-N network structure, evident from an emergence of new Raman νs(C-N) at 1404 cm-1 at 25 GPa and the visual appearance of translucent solid. The C-N product is, however, unstable upon pressure unloading below 10 GPa, resulting in a grayish powder that can be considered as nano-diamonds with high-nitrogen content at ambient pressure. The C-N product shows a strong emission line centered at 640 nm at 30 GPa, which linearly shifts toward shorter wavelength at the rate of -1.38 nm/GPa. We conjecture that the observed red shift upon unloading pressure is due to increase of defects in the C-N product and thereby weakening of C-N bonds.

  3. Propagation of impact-induced shock waves in porous sandstone using mesoscale modeling

    NASA Astrophysics Data System (ADS)

    GÜLdemeister, Nicole; WÜNnemann, Kai; Durr, Nathanael; Hiermaier, Stefan

    2013-01-01

    Abstract-Generation and propagation of shock <span class="hlt">waves</span> by meteorite impact is significantly affected by material properties such as porosity, water content, and strength. The objective of this work was to quantify processes related to the shock-<span class="hlt">induced</span> compaction of pore space by numerical modeling, and compare the results with data obtained in the framework of the Multidisciplinary Experimental and Modeling Impact Research Network (MEMIN) impact experiments. We use mesoscale models resolving the collapse of individual pores to validate macroscopic (homogenized) approaches describing the bulk behavior of porous and water-saturated materials in large-scale models of crater formation, and to quantify localized shock amplification as a result of pore space crushing. We carried out a suite of numerical models of planar shock <span class="hlt">wave</span> propagation through a well-defined area (the "sample") of porous and/or water-saturated material. The porous sample is either represented by a homogeneous unit where porosity is treated as a state variable (macroscale model) and water content by an equation of state for mixed material (ANEOS) or by a defined number of individually resolved pores (mesoscale model). We varied porosity and water content and measured thermodynamic parameters such as shock <span class="hlt">wave</span> velocity and particle velocity on meso- and macroscales in separate simulations. The mesoscale models provide additional data on the heterogeneous distribution of peak shock <span class="hlt">pressures</span> as a consequence of the complex superposition of reflecting rarefaction <span class="hlt">waves</span> and shock <span class="hlt">waves</span> originating from the crushing of pores. We quantify the bulk effect of porosity, the reduction in shock <span class="hlt">pressure</span>, in terms of Hugoniot data as a function of porosity, water content, and strength of a quartzite matrix. We find a good agreement between meso-, macroscale models and Hugoniot data from shock experiments. We also propose a combination of a porosity compaction model (ɛ-α model) that was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21424133','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21424133"><span>[Vertigo <span class="hlt">induced</span> by noise or <span class="hlt">pressure</span> to the left ear].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seidel, D U; Dülks, A; Remmert, S</p> <p>2011-06-01</p> <p>A 49-year-old male patient presented with recently acquired vertigo <span class="hlt">induced</span> by noise or <span class="hlt">pressure</span> to the left ear. With appropriate stimulation, oscillopsia with a rotatory component could be reproduced in videooculography. Cervical vestibular evoked myogenic potentials (VEMP) showed increased amplitudes and a lowered threshold on the left side. CT of the petrous bone showed a bony dehiscence of the left superior semicircular canal. Conservative therapy was initiated as a first step.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARQ52011R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARQ52011R"><span>Geometry-<span class="hlt">induced</span> rigidity in <span class="hlt">pressurized</span> elastic shells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reis, Pedro; Florijn, Bastiaan; Lazarus, Arnaud</p> <p>2012-02-01</p> <p>We study the indentation of <span class="hlt">pressurized</span> thin elastic shells, with positive Gauss curvature. In our precision desktop-scale experiments, the geometry of the shells and their material properties are custom-controlled using rapid prototyping and digital fabrication techniques. The mechanical response is quantified through load-displacement compression tests and the differential <span class="hlt">pressure</span> is set by a syringe-pump system under feedback control. Focus is given to the linear regime of the response towards quantifying the geometry-<span class="hlt">induced</span> rigidity of <span class="hlt">pressurized</span> shells with different shapes. We find that this effective stiffness is proportional to the local mean curvature in the neighborhood of the locus of indentation. Combining classic theory of shells with recent developments by D. Vella et al. (2011), we rationalize the dependence of the geometry-<span class="hlt">induced</span> rigidity on: i) the mean curvature at the point of indentation, ii) the material properties of the shell and iii) the in-out differential <span class="hlt">pressure</span>. The proposed predictive framework is in excellent agreement with our experiments, over a wide range of control parameters. The prominence of geometry in this class of problems points to the relevance and applicability of our results over a wide range of lengthscales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvB..91q4440U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvB..91q4440U"><span>Spin-<span class="hlt">wave-induced</span> spin torque in Rashba ferromagnets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Umetsu, Nobuyuki; Miura, Daisuke; Sakuma, Akimasa</p> <p>2015-05-01</p> <p>We study the effects of Rashba spin-orbit coupling on the spin torque <span class="hlt">induced</span> by spin <span class="hlt">waves</span>, which are the plane-<span class="hlt">wave</span> dynamics of magnetization. The spin torque is derived from linear-response theory, and we calculate the dynamic spin torque by considering the impurity-ladder-sum vertex corrections. This dynamic spin torque is divided into three terms: a damping term, a distortion term, and a correction term for the equation of motion. The distorting torque describes a phenomenon unique to the Rashba spin-orbit coupling system, where the distorted motion of magnetization precession is subjected to the anisotropic force from the Rashba coupling. The oscillation mode of the precession exhibits an elliptical trajectory, and the ellipticity depends on the strength of the nesting effects, which could be reduced by decreasing the electron lifetime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E2111Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E2111Y"><span>Gravity-<span class="hlt">wave</span> <span class="hlt">induced</span> CO2 clouds on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yiǧit, Erdal; Medvedev, Alexander S.; Hartogh, Paul</p> <p>2016-07-01</p> <p>We present the first general circulation model simulations that quantify and reproduce patches of extremely cold air required for CO2 condensation and cloud formation in the Martian mesosphere. They are created by subgrid-scale gravity <span class="hlt">waves</span> (GWs) accounted for in the model with the whole atmosphere GW parameterization of Yiǧit et al. (2008)}. Distributions of GW-<span class="hlt">induced</span> temperature fluctuations and occurrences of supersaturation conditions are in a good agreement with observations of high-altitude CO2 ice clouds. Our study confirms the key role of GWs in facilitating CO2 cloud formation, discusses their tidal modulation, and predicts clouds at altitudes higher than have been observed to date. Reference: Yiǧit, E., A. D. Aylward, and A. S. Medvedev (2008), Parameterization of the effects of vertically propagating gravity <span class="hlt">waves</span> for thermosphere general circulation models: Sensitivity study, J. Geophys. Res., 113, D19106, doi:10.1029/2008JD010135.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25535360','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25535360"><span>Transdermal deferoxamine prevents <span class="hlt">pressure-induced</span> diabetic ulcers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Duscher, Dominik; Neofytou, Evgenios; Wong, Victor W; Maan, Zeshaan N; Rennert, Robert C; Inayathullah, Mohammed; Januszyk, Michael; Rodrigues, Melanie; Malkovskiy, Andrey V; Whitmore, Arnetha J; Walmsley, Graham G; Galvez, Michael G; Whittam, Alexander J; Brownlee, Michael; Rajadas, Jayakumar; Gurtner, Geoffrey C</p> <p>2015-01-06</p> <p>There is a high mortality in patients with diabetes and severe <span class="hlt">pressure</span> ulcers. For example, chronic <span class="hlt">pressure</span> sores of the heels often lead to limb loss in diabetic patients. A major factor underlying this is reduced neovascularization caused by impaired activity of the transcription factor hypoxia <span class="hlt">inducible</span> factor-1 alpha (HIF-1α). In diabetes, HIF-1α function is compromised by a high glucose-<span class="hlt">induced</span> and reactive oxygen species-mediated modification of its coactivator p300, leading to impaired HIF-1α transactivation. We examined whether local enhancement of HIF-1α activity would improve diabetic wound healing and minimize the severity of diabetic ulcers. To improve HIF-1α activity we designed a transdermal drug delivery system (TDDS) containing the FDA-approved small molecule deferoxamine (DFO), an iron chelator that increases HIF-1α transactivation in diabetes by preventing iron-catalyzed reactive oxygen stress. Applying this TDDS to a <span class="hlt">pressure-induced</span> ulcer model in diabetic mice, we found that transdermal delivery of DFO significantly improved wound healing. Unexpectedly, prophylactic application of this transdermal delivery system also prevented diabetic ulcer formation. DFO-treated wounds demonstrated increased collagen density, improved neovascularization, and reduction of free radical formation, leading to decreased cell death. These findings suggest that transdermal delivery of DFO provides a targeted means to both prevent ulcer formation and accelerate diabetic wound healing with the potential for rapid clinical translation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4291638','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4291638"><span>Transdermal deferoxamine prevents <span class="hlt">pressure-induced</span> diabetic ulcers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Duscher, Dominik; Neofytou, Evgenios; Wong, Victor W.; Maan, Zeshaan N.; Rennert, Robert C.; Januszyk, Michael; Rodrigues, Melanie; Malkovskiy, Andrey V.; Whitmore, Arnetha J.; Galvez, Michael G.; Whittam, Alexander J.; Brownlee, Michael; Rajadas, Jayakumar; Gurtner, Geoffrey C.</p> <p>2015-01-01</p> <p>There is a high mortality in patients with diabetes and severe <span class="hlt">pressure</span> ulcers. For example, chronic <span class="hlt">pressure</span> sores of the heels often lead to limb loss in diabetic patients. A major factor underlying this is reduced neovascularization caused by impaired activity of the transcription factor hypoxia <span class="hlt">inducible</span> factor-1 alpha (HIF-1α). In diabetes, HIF-1α function is compromised by a high glucose-<span class="hlt">induced</span> and reactive oxygen species-mediated modification of its coactivator p300, leading to impaired HIF-1α transactivation. We examined whether local enhancement of HIF-1α activity would improve diabetic wound healing and minimize the severity of diabetic ulcers. To improve HIF-1α activity we designed a transdermal drug delivery system (TDDS) containing the FDA-approved small molecule deferoxamine (DFO), an iron chelator that increases HIF-1α transactivation in diabetes by preventing iron-catalyzed reactive oxygen stress. Applying this TDDS to a <span class="hlt">pressure-induced</span> ulcer model in diabetic mice, we found that transdermal delivery of DFO significantly improved wound healing. Unexpectedly, prophylactic application of this transdermal delivery system also prevented diabetic ulcer formation. DFO-treated wounds demonstrated increased collagen density, improved neovascularization, and reduction of free radical formation, leading to decreased cell death. These findings suggest that transdermal delivery of DFO provides a targeted means to both prevent ulcer formation and accelerate diabetic wound healing with the potential for rapid clinical translation. PMID:25535360</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21546961','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21546961"><span>Generation of a 400 GPa <span class="hlt">pressure</span> in water using converging strong shock <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fedotov-Gefen, A.; Efimov, S.; Gilburd, L.; Bazalitski, G.; Gurovich, V. Tz.; Krasik, Ya. E.</p> <p>2011-06-15</p> <p>Results related to the generation of an extreme state of water with <span class="hlt">pressure</span> up to (4.3 {+-} 0.2){center_dot}10{sup 11} Pa, density up to 4.2 {+-} 0.1 g/cm{sup 3}, and temperature up to 2.2 {+-} 0.1 eV in the vicinity of the implosion axis of a converging strong shock <span class="hlt">wave</span> are reported. The shock <span class="hlt">wave</span> was produced by the underwater electrical explosion of a cylindrical Cu wire array. A {approx}8 kJ pulse generator with a current amplitude {<=}550 kA and rise time of 350 ns was used to explode arrays having varying lengths, radii, and number of wires. Hydrodynamic numerical simulations coupled to the experimental data of the shock <span class="hlt">wave</span> propagation in water, rate of energy deposition into the array, and light emission from the compressed water in the vicinity of the implosion axis were used to determine the <span class="hlt">pressure</span>, density, and temperature profiles during the implosion. Results of a comparison between these parameters obtained with the SESAME and quantum molecular dynamics data bases of equation of state for water are reported as well. Also, the dependences of the maximal <span class="hlt">pressure</span> in the vicinity of the implosion axes on the array radius and the deposited energy density per unit length are reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhPl...18f2701F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhPl...18f2701F"><span>Generation of a 400 GPa <span class="hlt">pressure</span> in water using converging strong shock <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedotov-Gefen, A.; Efimov, S.; Gilburd, L.; Bazalitski, G.; Gurovich, V. Tz.; Krasik, Ya. E.</p> <p>2011-06-01</p> <p>Results related to the generation of an extreme state of water with <span class="hlt">pressure</span> up to (4.3 ± 0.2).1011 Pa, density up to 4.2 ± 0.1 g/cm3, and temperature up to 2.2 ± 0.1 eV in the vicinity of the implosion axis of a converging strong shock <span class="hlt">wave</span> are reported. The shock <span class="hlt">wave</span> was produced by the underwater electrical explosion of a cylindrical Cu wire array. A ˜8 kJ pulse generator with a current amplitude ≤550 kA and rise time of 350 ns was used to explode arrays having varying lengths, radii, and number of wires. Hydrodynamic numerical simulations coupled to the experimental data of the shock <span class="hlt">wave</span> propagation in water, rate of energy deposition into the array, and light emission from the compressed water in the vicinity of the implosion axis were used to determine the <span class="hlt">pressure</span>, density, and temperature profiles during the implosion. Results of a comparison between these parameters obtained with the SESAME and quantum molecular dynamics data bases of equation of state for water are reported as well. Also, the dependences of the maximal <span class="hlt">pressure</span> in the vicinity of the implosion axes on the array radius and the deposited energy density per unit length are reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4344573','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4344573"><span>Black Tea Lowers Blood <span class="hlt">Pressure</span> and <span class="hlt">Wave</span> Reflections in Fasted and Postprandial Conditions in Hypertensive Patients: A Randomised Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Grassi, Davide; Draijer, Richard; Desideri, Giovambattista; Mulder, Theo; Ferri, Claudio</p> <p>2015-01-01</p> <p>Hypertension and arterial stiffening are independent predictors of cardiovascular mortality. Flavonoids may exert some vascular protection. We investigated the effects of black tea on blood <span class="hlt">pressure</span> (BP) and <span class="hlt">wave</span> reflections before and after fat load in hypertensives. According to a randomized, double-blind, controlled, cross-over design, 19 patients were assigned to consume black tea (129 mg flavonoids) or placebo twice a day for eight days (13 day wash-out period). Digital volume pulse and BP were measured before and 1, 2, 3 and 4 h after tea consumption. Measurements were performed in a fasted state and after a fat load. Compared to placebo, reflection index and stiffness index decreased after tea consumption (p < 0.0001). Fat challenge increased <span class="hlt">wave</span> reflection, which was counteracted by tea consumption (p < 0.0001). Black tea decreased systolic and diastolic BP (−3.2 mmHg, p < 0.005 and −2.6 mmHg, p < 0.0001; respectively) and prevented BP increase after a fat load (p < 0.0001). Black tea consumption lowers <span class="hlt">wave</span> reflections and BP in the fasting state, and during the challenging haemodynamic conditions after a fat load in hypertensives. Considering lipemia-<span class="hlt">induced</span> impairment of arterial function may occur frequently during the day, our findings suggest regular consumption of black tea may be relevant for cardiovascular protection. PMID:25658240</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006cosp...36..349B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006cosp...36..349B"><span>Studies of <span class="hlt">wave</span> phenomena using HF-<span class="hlt">induced</span> scatter target</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blagoveshchenskaya, N.; Borisova, T.; Kornienko, V.; Rietveld, M.; Frolov, V.; Uryadov, V.; Kagan, L.; Yampolski, Y.; Vertogradov, G.; Kelley, M.</p> <p></p> <p>Experimental results from Tromso and Sura heating experiments at high and mid-latitudes are examined It was shown that the combination of HF-<span class="hlt">induced</span> target and bi-static HF Doppler radio scatter observations is a profitable method for the identification and studies of <span class="hlt">wave</span> phenomena of different origin We analysed the ULF activity in the Pc 3-4 range and the medium-scale traveling ionospheric disturbances TIDs at high and mid-latitudes Bi-static HF Doppler radio scatter observations were carried out on the London-Tromso-St Petersburg path in the course of Tromso heating experiments During Sura heating experiments multi-position bi-static HF Doppler radio scatter observations were simultaneously performed at three reception points including St Petersburg Kharkov and Rostov-on-Don Ray tracing and Doppler shift simulations were made for all experiments Parameters of ULF <span class="hlt">waves</span> were found The interesting feature detected from Sura heating experiment was the dependence of the ULF <span class="hlt">wave</span> parameters from the effective radiated power of the heating facility Medium-scale TIDs were observed in the evening and pre-midnight hours TIDs in the auroral E region with periods of 20-25 min were traveling southward at speeds from 190-250 m s TIDs in the mid-latitudinal F region with periods from 15 to 45 min were at speeds between 40 and 120 m s During quiet magnetic conditions the <span class="hlt">waves</span> were traveling in the north-east direction In disturbed conditions the <span class="hlt">waves</span> were moving in the south-west direction with higher speeds as compared with quiet conditions Possible mechanisms</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14986411','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14986411"><span><span class="hlt">Pressure</span> <span class="hlt">wave</span> propagation in fluid-filled co-axial elastic tubes. Part 2: Mechanisms for the pathogenesis of syringomyelia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carpenter, P W; Berkouk, K; Lucey, A D</p> <p>2003-12-01</p> <p>Our aim in this paper is to use a simple theoretical model of the intraspinal cerebrospinal-fluid system to investigate mechanisms proposed for the pathogenesis of syringomyelia. The model is based on an inviscid theory for the propagation of <span class="hlt">pressure</span> <span class="hlt">waves</span> in co-axial, fluid-filled, elastic tubes. According to this model, the leading edge of a <span class="hlt">pressure</span> pulse tends to steepen and form an elastic jump, as it propagates up the intraspinal cerebrospinal-fluid system. We show that when an elastic jump is incident on a stenosis of the spinal subarachnoid space, it reflects to form a transient, localized region of high <span class="hlt">pressure</span> within the spinal cord that for a cough-<span class="hlt">induced</span> pulse is estimated to be 50 to 70 mm Hg or more above the normal level in the spinal subarachnoid space. We propose this as a new mechanism whereby <span class="hlt">pressure</span> pulses created by coughing or sneezing can generate syrinxes. We also use the same analysis to investigate Williams' suck mechanism. Our results do not support his concept, nor, in cases where the stenosis is severe, the differential-<span class="hlt">pressure</span>-propagation mechanism recently proposed by Greitz et al. Our analysis does provide some support for the piston mechanism recently proposed by Oldfield et al. and Heiss et al. For instance, it shows clearly how the spinal cord is compressed by the formation of elastic jumps over part of the cardiac cycle. What appears to be absent for this piston mechanism is any means whereby the elastic jumps can be focused (e.g., by reflecting from a stenosis) to form a transient, localized region of high <span class="hlt">pressure</span> within the spinal cord. Thus it would seem to offer a mechanism for syrinx progression, but not for its formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997PhFl....9.2716D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997PhFl....9.2716D"><span>Coherent vortex model for surface <span class="hlt">pressure</span> fluctuations <span class="hlt">induced</span> by the wall region of a turbulent boundary layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dhanak, Manhar R.; Dowling, Ann P.; Si, Chao</p> <p>1997-09-01</p> <p>Exact solutions of the Navier-Stokes equations describing the interaction of streamwise vortices with a rigid surface are utilized to develop a conceptual model for the surface <span class="hlt">pressure</span> spectrum associated with the wall region of a turbulent boundary layer. The evolution of single as well as pairs of coherent streamwise vortices, which principally govern the production of turbulence in the wall region, is considered in the presence of local straining flow <span class="hlt">induced</span> by larger, outer-layer eddies. The surface <span class="hlt">pressure</span> signatures of the coherent vortex motion and the associated power spectrum of the <span class="hlt">pressure</span> are examined. Based on the results of the exact solutions, the surface <span class="hlt">pressure</span> spectrum of an ensemble of independent coherent structures is modeled using the assumption of ergodicity in the manner described by Townsend and Lundgren for homogeneous turbulence. The free parameters in the model are estimated through comparison with available results from experiments and numerical simulations. The model, especially the one involving pairs of streamwise vortices, predicts the high frequency and high spanwise <span class="hlt">wave</span> number range of the surface <span class="hlt">pressure</span> spectrum quite well. Further, the probability density function of surface <span class="hlt">pressure</span> associated with the model compares well with experimental results. Interestingly, the model also suggests that the contribution of the viscous interaction to low <span class="hlt">wave</span> number spectral elements accounts for the discrepancy between experimental observations at such <span class="hlt">wave</span> numbers and the prediction of the Kraichnan-Phillips theorem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3312616','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3312616"><span>Over-<span class="hlt">Pressure</span> Suppresses Ultrasonic-<span class="hlt">Induced</span> Drug Uptake</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Stringham, S. Briant; Viskovska, Maria A.; Richardson, Eric S.; Ohmine, Seiga; Husseini, Ghaleb A.; Murray, Byron K.; Pitt, William G.</p> <p>2012-01-01</p> <p>Ultrasound (US) is used to enhance and target delivery of drugs and genes to cancer tissues. The present study further examines the role of acoustic cavitation in US-<span class="hlt">induced</span> permeabilization of cell membranes and subsequent drug or gene uptake by the cell. Rat colon cancer cells were exposed to ultrasound at various static <span class="hlt">pressures</span> to examine the hypothesis that oscillating bubbles, also known as cavitating bubbles, permeabilize cells. Increasing <span class="hlt">pressure</span> suppresses bubble cavitation activity; thus if applied <span class="hlt">pressure</span> were to reduce drug uptake, cell permeabilization would be strongly linked to bubble cavitation activity. Cells were exposed to 476 kHz pulsed ultrasound at average intensities of 2.75 W/cm2 and 5.5 W/cm2 at various <span class="hlt">pressures</span> and times in an isothermal chamber. Cell fractions with reversible membrane damage (calcein uptake) and irreversible damage (propidium iodide uptake) were analyzed by flow cytometry. <span class="hlt">Pressurization</span> to 3 atm nearly eliminated the biological effect of US in promoting calcein uptake. Data also showed a linear increase in membrane permeability based upon increased time and intensity. This research shows that US-mediated cell membrane permeability is likely linked to cavitation bubble activity. PMID:19056161</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JAP...113c3511Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JAP...113c3511Z"><span><span class="hlt">Pressure-induced</span> series of phase transitions in sodium azide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Hongyang; Zhang, Fuxiang; Ji, Cheng; Hou, Dongbin; Wu, Jianzhe; Hannon, Trevor; Ma, Yangzhang</p> <p>2013-01-01</p> <p>The phase analysis of sodium azide (NaN3) has been investigated by in situ synchrotron X-ray diffraction measurements in a diamond anvil cell up to 52.0 GPa at room temperature. Three <span class="hlt">pressure-induced</span> phase transitions were observed. The phase transition <span class="hlt">pressures</span> were determined to be 0.3, 17.3, and 28.7 GPa verified by three different <span class="hlt">pressure</span> transmitting media. The first high <span class="hlt">pressure</span> phase, α-NaN3 (0.3 ˜ 17.3 GPa), was identified to be monoclinic with a C2/m space group. The β-NaN3 to α-NaN3 transition is a second-order phase transition, accompanied by the shearing of the Na-layers and the tilting of the azide chains. The second high <span class="hlt">pressure</span> phase, γ-NaN3 (18.4 ˜ 28.7 GPa), has a lower symmetry than the α-NaN3. A further phase transition of γ-NaN3 to δ-NaN3 at 28.7 GPa was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21504017','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21504017"><span><span class="hlt">Pressure</span> <span class="hlt">induced</span> reactions amongst calcium aluminate hydrate phases</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moon, Ju-hyuk; Oh, Jae Eun; Balonis, Magdalena; Glasser, Fredrik P.; Clark, Simon M.; Monteiro, Paulo J.M.</p> <p>2011-06-15</p> <p>The compressibilities of two AFm phases (straetlingite and calcium hemicarboaluminate hydrate) and hydrogarnet were obtained up to 5 GPa by using synchrotron high-<span class="hlt">pressure</span> X-ray powder diffraction with a diamond anvil cell. The AFm phases show abrupt volume contraction regardless of the molecular size of the <span class="hlt">pressure</span>-transmitting media. This volume discontinuity could be associated to a structural transition or to the movement of the weakly bound interlayer water molecules in the AFm structure. The experimental results seem to indicate that the <span class="hlt">pressure-induced</span> dehydration is the dominant mechanism especially with hygroscopic <span class="hlt">pressure</span> medium. The Birch-Murnaghan equation of state was used to compute the bulk modulus of the minerals. Due to the discontinuity in the <span class="hlt">pressure</span>-volume diagram, a two stage bulk modulus of each AFm phase was calculated. The abnormal volume compressibility for the AFm phases caused a significant change to their bulk modulus. The reliability of this experiment is verified by comparing the bulk modulus of hydrogarnet with previous studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18378271','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18378271"><span>Shock <span class="hlt">wave</span> emission from laser-<span class="hlt">induced</span> cavitation bubbles in polymer solutions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brujan, Emil-Alexandru</p> <p>2008-09-01</p> <p>The role of extensional viscosity on the acoustic emission from laser-<span class="hlt">induced</span> cavitation bubbles in polymer solutions and near a rigid boundary is investigated by acoustic measurements. The polymer solutions consist of a 0.5% polyacrylamide (PAM) aqueous solution with a strong elastic component and a 0.5% carboxymethylcellulose (CMC) aqueous solution with a weak elastic component. A reduction of the maximum amplitude of the shock <span class="hlt">wave</span> <span class="hlt">pressure</span> and a prolongation of the oscillation period of the bubble were found in the elastic PAM solution. It might be caused by an increased resistance to extensional flow which is conferred upon the liquid by the polymer additive. In both polymer solutions, however, the shock <span class="hlt">pressure</span> decays proportionally to r(-1) with increasing distance r from the emission centre.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996SPIE.2681..437H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SPIE.2681..437H"><span>Shock <span class="hlt">wave</span> and cavitation bubble measurements of ultrashort-pulse laser-<span class="hlt">induced</span> breakdown in water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hammer, Daniel X.; Thomas, Robert J.; Frenz, Martin; Jansen, E. Duco; Noojin, Gary D.; Diggs, Sarah J.; Noack, Joachim; Vogel, Alfred; Rockwell, Benjamin A.</p> <p>1996-05-01</p> <p>Laser-<span class="hlt">induced</span> breakdown (LIB) has long been used in ophthalmic microsurgery as a mechanism for disruption of tissue. The goal of this surgery has been precise tissue cutting by plasma formation and a minimization of collateral damage due to shock <span class="hlt">wave</span> and cavitation bubble formation. We investigate the strength of the shock <span class="hlt">wave</span> emission, the size of the cavitation bubble, and the amount of plasma shielding to determine the efficacy of using femtosecond pulses in surgery to reduce collateral photoacoustic damage. A pump-probe technique is used to image the time-resolved evolution of the cavitation bubble produced by focused laser pulses with pulsewidths of 130 fs, 300 fs, 3 ps, and 60 ps. Simultaneously, a hydrophone is used to measure the <span class="hlt">pressure</span> response generated by the initial plasma shock <span class="hlt">wave</span> and subsequent shock <span class="hlt">waves</span> generated by the collapse and rebound of the cavitation bubbles. In addition, transmission measurements are made which indicate the amount of energy shielded beyond the focus by the plasma. These measurements give a good indication of the degree to which collateral damage may be reduced as the pulsewidths is decreased from the picosecond to the femtosecond time regime.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ChPhL..29f0509H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ChPhL..29f0509H"><span>Non-Rational Rogue <span class="hlt">Waves</span> <span class="hlt">Induced</span> by Inhomogeneity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Jing-Song; Wang, You-Ying; Li, Lin-Jing</p> <p>2012-06-01</p> <p>The variable Sine—Gordon (VSG) equation is often used to model several kinds of systems with inhomogeneity and it can be realized by the management of dispersion and nonlinearity in optics and Feschbach resonance in Bose-Einstein condensates. We derive four new kinds of non-rational rogue <span class="hlt">wave</span> (RW) of the VSG by using an explicit transformation and the designable integrability. These RWs have novel profiles and interesting internal structures. It is shown that the RW is <span class="hlt">induced</span> by the inhomogeneity of the system modeled by the VSG. The theoretical prediction of the corresponding relations between the RWs and some extreme events in DNA is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800045672&hterms=shocking&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dshocking','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800045672&hterms=shocking&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dshocking"><span>Interaction of laser-<span class="hlt">induced</span> stress <span class="hlt">waves</span> with metals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clauer, A. H.; Fairand, B. P.</p> <p>1979-01-01</p> <p>An investigation of the effect of high intensity laser <span class="hlt">induced</span> stress <span class="hlt">waves</span> on the hardness and tensile strength of 2024 and 7075 aluminum and on the fatigue properties of 7075 aluminum were investigated. Laser shocking increases the hardness of the underaged 2024-T351 but has little or no effect on the peak aged 2024-T351 and 7075-T651 or the overaged 7075-T73. The fretting fatigue life of fastener joints of 7075-T6 was increased by orders of magnitude by laser shocking the region around the fastener hole; the fatigue crack propagation rates were decreased by laser shocking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JaJAP..41.3316H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JaJAP..41.3316H"><span>Visualization and Measurements of Sound <span class="hlt">Pressure</span> Distribution of Ultrasonic <span class="hlt">Wave</span> by Stroboscopic Real-Time Holographic Interferometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hisada, Shigeyoshi; Suzuki, Takahiro; Nakahara, Sumio; Fujita, Takeyoshi</p> <p>2002-05-01</p> <p>The sound <span class="hlt">pressure</span> distribution of underwater ultrasonic <span class="hlt">waves</span> is measured by real-time stroboscope holographic interferometry using bismuth silicon oxide single crystal. Stroboscopic sub-microsecond irradiation of laser light enables the recording of the stationary holographic interferogram of refractive index changes of water by ultrasonic <span class="hlt">waves</span> for the frame time of a charge coupled device camera. The fringe order distribution is calculated from the interferogram by Fourier transform fringe analysis. The optical path differences caused by sound field along the optical path are converted into local field values of sound <span class="hlt">pressure</span>, which is displayed as a gray scale distribution image. In the experiment, the sound <span class="hlt">pressure</span> distributions of ultrasonic <span class="hlt">waves</span> through rectangular and circular apertures are observed. They are compared with the theoretical sound <span class="hlt">pressure</span> distribution. The sound <span class="hlt">pressure</span> values obtained by a hydrophone show good agreement with the measured values obtained by this method. The converging and diverging sound <span class="hlt">pressure</span> fields realized by an acoustic lens are measured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8350814','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8350814"><span><span class="hlt">Pressure</span> <span class="hlt">wave</span> generated by the passage of a heavy charged particle in water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Y Y; Nath, R</p> <p>1993-01-01</p> <p>Energy deposition around the trajectories of ionizing particles with linear energy transfer (LET) of 4, 40, and 400 keV/microns in water and subsequent diffusion of deposited heat is calculated using computational fluid dynamics. Immediately after the deposition of energy by the charged particle, the temperature and <span class="hlt">pressure</span> in the vicinity of the particle track both increase dramatically, leading to the formation of a thermal spike and a <span class="hlt">pressure</span> <span class="hlt">wave</span>. Initially, the region of heat deposition is primarily localized to a region called the "thermal core," which has dimensions of 0.3, 1, and 3 nm for particles with LETs of 4, 40, and 400 keV/microns, respectively. Instantaneous peak temperatures within the thermal core were 800 degrees C-2000 degrees C and peak <span class="hlt">pressures</span> were about 25,000 atm. This sudden deposition of heat in a localized region leads to a very strong shock <span class="hlt">wave</span> around the particle trajectory, which is shown to last for a duration of 10(-9)-10(-8) s. Even at distances beyond 10 nm away from the particle trajectory, <span class="hlt">pressures</span> above 100 atm could exist for a duration of up to 10(-11) s. This local and transient environment, created by the passage of a charged particle in a medium, may lead to new mechanisms of radiation action leading to cell damage, as well as to the development of new radiation detectors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..GECNR3008X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..GECNR3008X"><span>Simulation of High <span class="hlt">Pressure</span> Ionization <span class="hlt">Waves</span> in Straight and Circuitous Dielectric Channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Zhongmin; Takashima, Keisuke; Adamovich, Igor V.; Kushner, Mark J.</p> <p>2011-10-01</p> <p>High <span class="hlt">pressure</span> non-equilibrium plasmas are often transient and in the form of fast ionization <span class="hlt">waves</span> (FIWs) with applications from plasma assisted combustion to plasma medicine. A numerical study of FIWs, with comparison to experiments, was conducted using nonPDPSIM, a 2-d plasma hydrodynamics model with radiation transport. We first investigated the fundamental properties of moderate <span class="hlt">pressure</span> FIWs in straight dielectric channels to quantify their propagation mechanisms. The FIWs were generated by ns high voltage pulses in N2 and He at <span class="hlt">pressures</span> of 10-20 Torr. Simulations are compared to experiments for transient electric fields and <span class="hlt">wave</span> speed. The effects of the secondary emission properties of bounding surfaces on plasma uniformity will be discussed. We then applied these results to a study of the propagation of FIWs in Ne at atmospheric <span class="hlt">pressure</span> through long, circuitous channels (length > 15 cm, width < 1 mm) as used to deliver plasma to remote sites. The FIW speed and front structure for positive and negative polarities, and the effects of channel curvature and dielectric constants of the channel wall on FIW dynamics will be discussed. Work is supported by the DOE Office of Fusion Energy Science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ASAJ..112.2240T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ASAJ..112.2240T"><span>Radiation <span class="hlt">pressure</span> of standing <span class="hlt">waves</span> on liquid columns and small diffusion flames</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thiessen, David B.; Marr-Lyon, Mark J.; Wei, Wei; Marston, Philip L.</p> <p>2002-11-01</p> <p>The radiation <span class="hlt">pressure</span> of standing ultrasonic <span class="hlt">waves</span> in air is demonstrated in this investigation to influence the dynamics of liquid columns and small flames. With the appropriate choice of the acoustic amplitude and wavelength, the natural tendency of long columns to break because of surface tension was suppressed in reduced gravity [M. J. Marr-Lyon, D. B. Thiessen, and P. L. Marston, Phys. Rev. Lett. 86, 2293-2296 (2001); 87(20), 9001(E) (2001)]. Evaluation of the radiation force shows that narrow liquid columns are attracted to velocity antinodes. The response of a small vertical diffusion flame to ultrasonic radiation <span class="hlt">pressure</span> in a horizontal standing <span class="hlt">wave</span> was observed in normal gravity. In agreement with our predictions of the distribution of ultrasonic radiation stress on the flame, the flame is attracted to a <span class="hlt">pressure</span> antinode and becomes slightly elliptical with the major axis in the plane of the antinode. The radiation <span class="hlt">pressure</span> distribution and the direction of the radiation force follow from the dominance of the dipole scattering for small flames. Understanding radiation stress on flames is relevant to the control of hot fluid objects. [Work supported by NASA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.9771C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.9771C"><span>Van Allen Probes observations of electromagnetic ion cyclotron <span class="hlt">waves</span> triggered by enhanced solar wind dynamic <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cho, J.-H.; Lee, D.-Y.; Noh, S.-J.; Shin, D.-K.; Hwang, J.; Kim, K.-C.; Lee, J. J.; Choi, C. R.; Thaller, S.; Skoug, R.</p> <p>2016-10-01</p> <p>Magnetospheric compression due to impact of enhanced solar wind dynamic <span class="hlt">pressure</span> Pdyn has long been considered as one of the generation mechanisms of electromagnetic ion cyclotron (EMIC) <span class="hlt">waves</span>. With the Van Allen Probe-A observations, we identify three EMIC <span class="hlt">wave</span> events that are triggered by Pdyn enhancements under prolonged northward interplanetary magnetic field (IMF) quiet time preconditions. They are in contrast to one another in a few aspects. Event 1 occurs in the middle of continuously increasing Pdyn while Van Allen Probe-A is located outside the plasmapause at postmidnight and near the equator (magnetic latitude (MLAT) -3°). Event 2 occurs by a sharp Pdyn pulse impact while Van Allen Probe-A is located inside the plasmapause in the dawn sector and rather away from the equator (MLAT 12°). Event 3 is characterized by amplification of a preexisting EMIC <span class="hlt">wave</span> by a sharp Pdyn pulse impact while Van Allen Probe-A is located outside the plasmapause at noon and rather away from the equator (MLAT -15°). These three events represent various situations where EMIC <span class="hlt">waves</span> can be triggered by Pdyn increases. Several common features are also found among the three events. (i) The strongest <span class="hlt">wave</span> is found just above the He+ gyrofrequency. (ii) The <span class="hlt">waves</span> are nearly linearly polarized with a rather oblique propagation direction ( 28° to 39° on average). (iii) The proton fluxes increase in immediate response to the Pdyn impact, most significantly in tens of keV energy, corresponding to the proton resonant energy. (iv) The temperature anisotropy with T⊥ > T|| is seen in the resonant energy for all the events, although its increase by the Pdyn impact is not necessarily always significant. The last two points (iii) and (iv) may imply that in addition to the temperature anisotropy, the increase of the resonant protons must have played a critical role in triggering the EMIC <span class="hlt">waves</span> by the enhanced Pdyn impact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JHyd..544..467S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JHyd..544..467S"><span>Two-dimensional vertical moisture-<span class="hlt">pressure</span> dynamics above groundwater <span class="hlt">waves</span>: Sand flume experiments and modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shoushtari, Seyed Mohammad Hossein Jazayeri; Cartwright, Nick; Perrochet, Pierre; Nielsen, Peter</p> <p>2017-01-01</p> <p>This paper presents a new laboratory dataset on the moisture-<span class="hlt">pressure</span> relationship above a dispersive groundwater <span class="hlt">wave</span> in a two-dimensional vertical unconfined sand flume aquifer driven by simple harmonic forcing. A total of five experiments were conducted in which all experimental parameters were kept constant except for the oscillation period, which ranged from 268 s to 2449 s between tests. Moisture content and suction head sensor pairings were co-located at two locations in the unsaturated zone both approximately 0.2 m above the mean watertable elevation and respectively 0.3 m and 0.75 m from the driving head boundary. For all oscillation periods except for the shortest (T = 268s), the formation of a hysteretic moisture-<span class="hlt">pressure</span> scanning loop was observed. Consistent with the decay of the saturated zone groundwater <span class="hlt">wave</span>, the size of the observed moisture-<span class="hlt">pressure</span> scanning loops decayed with increasing distance landward and the decay rate is larger for the shorter oscillation periods. At the shortest period (T = 268s), the observed moisture-<span class="hlt">pressure</span> relationship was observed to be non-hysteretic but with a capillary capacity that differs from that of the static equilibrium wetting and drying curves. This finding is consistent with observations from existing one-dimensional vertical sand column experiments. The relative damping of the moisture content with distance landward is higher than that for the suction head consistent with the fact that transmission of <span class="hlt">pressure</span> through a porous medium occurs more readily than mass transfer. This is further supported by the fact that observed phase lags for the unsaturated zone variables (i.e. suction head and moisture content) relative to the driving head are greater than the saturated zone variables (i.e. piezometric head). Harmonic analysis of the data reveals no observable generation of higher harmonics in either moisture or <span class="hlt">pressure</span> despite the strongly non-linear relationship between the two. In addition, a phase lag</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50nLT01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50nLT01B"><span>Ultrafast laser-collision-<span class="hlt">induced</span> fluorescence in atmospheric <span class="hlt">pressure</span> plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barnat, E. V.; Fierro, A.</p> <p>2017-04-01</p> <p>The implementation and demonstration of laser-collision-<span class="hlt">induced</span> fluorescence (LCIF) generated in atmospheric <span class="hlt">pressure</span> helium environments is presented in this communication. As collision times are observed to be fast (~10 ns), ultrashort pulse laser excitation (<100 fs) of the 23S to 33P (388.9 nm) is utilized to initiate the LCIF process. Both neutral-<span class="hlt">induced</span> and electron-<span class="hlt">induced</span> components of the LCIF are observed in the helium afterglow plasma as the reduced electric field (E/N) is tuned from  <0.1 Td to over 5 Td. Under the discharge conditions presented in this study (640 Torr He), the lower limit of electron density detection is ~1012 e cm‑3. The spatial profiles of the 23S helium metastable and electrons are presented as functions of E/N to demonstrate the spatial resolving capabilities of the LCIF method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23232414','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23232414"><span>Shear <span class="hlt">wave</span> <span class="hlt">induced</span> resonance elastography of venous thrombi: a proof-of-concept.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schmitt, Cédric; Montagnon, Emmanuel; Henni, Anis Hadj; Qi, Shijie; Cloutier, Guy</p> <p>2013-03-01</p> <p>Shear <span class="hlt">wave</span> <span class="hlt">induced</span> resonance elastography (SWIRE) is proposed for deep venous thrombosis (DVT) elasticity assessment. This new imaging technique takes advantage of properly polarized shear <span class="hlt">waves</span> to <span class="hlt">induce</span> resonance of a confined mechanical heterogeneity. Realistic phantoms (n = 9) of DVT total and partial clot occlusions with elasticities from 406 to 3561 Pa were built for in vitro experiments. An ex vivo study was also performed to evaluate the elasticity of two fresh porcine venous thrombi in a pig model. Transient shear <span class="hlt">waves</span> at 45-205 Hz were generated by the vibration of a rigid plate (plane wavefront) or by a needle to simulate a radiation <span class="hlt">pressure</span> on a line segment (cylindrical wavefront). <span class="hlt">Induced</span> propagation of shear <span class="hlt">waves</span> was imaged with an ultrafast ultrasound scanner and a finite element method was developed to simulate tested experimental conditions. An inverse problem was then formulated considering the first resonance frequency of the DVT inclusion. Elasticity agreements between SWIRE and a reference spectroscopy instrument (RheoSpectris) were found in vitro for total clots either in plane (r(2) = 0.989) or cylindrical (r(2) = 0.986) wavefront configurations. For total and partial clots, elasticity estimation errors were 9.0 ±4.6% and 9.3 ±11.3%, respectively. Ex vivo, the blood clot elasticity was 498 ±58 Pa within the inferior vena cava and 436 ±45 Pa in the right common iliac vein (p = 0.22). To conclude, the SWIRE technique seems feasible to quantitatively assess blood clot elasticity in the context of DVT ultrasound imaging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ExFl...57..179H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ExFl...57..179H"><span>Optical-flow-based background-oriented schlieren technique for measuring a laser-<span class="hlt">induced</span> underwater shock <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hayasaka, Keisuke; Tagawa, Yoshiyuki; Liu, Tianshu; Kameda, Masaharu</p> <p>2016-12-01</p> <p>The background-oriented schlieren (BOS) technique with the physics-based optical flow method (OF-BOS) is developed for measuring the <span class="hlt">pressure</span> field of a laser-<span class="hlt">induced</span> underwater shock <span class="hlt">wave</span>. Compared to BOS with the conventional cross-correlation method that is also applied for particle image velocimetry (here called PIV-BOS), by using the OF-BOS, the displacement field generated by a small density gradient in water can be obtained at the spatial resolution of one vector per pixel. The corresponding density and <span class="hlt">pressure</span> fields can be further extracted. It is demonstrated in particular that the sufficiently high spatial resolution of the extracted displacement vector field is required in the tomographic reconstruction to correctly infer the <span class="hlt">pressure</span> field of the spherical underwater shock <span class="hlt">wave</span>. The capability of the OF-BOS method is critically evaluated based on synchronized hydrophone measurements. Special emphasis is placed on direct comparison between the OF-BOS and PIV-BOS methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15002349','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15002349"><span><span class="hlt">Pressure</span> <span class="hlt">Wave</span> Measurements During Thermal Explosion of HMX-Based High Explosives</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Forbes, J W; Garcia, F; Tarver, C M; Urtiew, P A; Greenwood, D W; Vandersall, K S</p> <p>2002-06-27</p> <p>Five different experiments on thermal heating of explosive materials have been performed. Three experiments thermally exploded PBX 9501 (HMX/Estane/BDNPA-F; 9512.512.5 wt %) donor charges while two others thermally exploded LX-04 (HMX/Viton A; 85/15 wt %). These donor charges were encased in 304 stainless steel. The transmitted two-dimensional <span class="hlt">pressure</span> <span class="hlt">waves</span> were measured by gauges in acceptor cylinders of Teflon, PBX 9501, or LX-04 that were in contact with the donors' steel case. A fifth experiment measured the <span class="hlt">pressure</span> in an acceptor charge of PBX 9501 that had a 100 mm stand-off from the top of the steel case of the thermally cooked off PBX 9501 donor charge. Reactive flow hydrodynamic modeling using a rapid deflagration velocity of approximately 500 m/s was able to reproduce the <span class="hlt">pressure</span> gauge records for both the in contact and stand off experiments that used PBX 9501 donors and acceptors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA490380','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA490380"><span><span class="hlt">Wave</span> Reflection and Central Aortic <span class="hlt">Pressure</span> Are Increased in Response to Static and Dynamic Muscle Contraction at Comparable Workloads</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2008-02-01</p> <p><span class="hlt">wave</span> reflec- tion is an important determinant of the central blood <span class="hlt">pressure</span> response during forearm muscle contractions. tension-time index; exercise ...pressor reflex; blood <span class="hlt">pressure</span> THE PRESSOR RESPONSE to exercise had been thought to be greater as a result of static muscle contraction compared with...equivalent peripheral blood <span class="hlt">pressure</span> response to forearm and lower body exercise may result in very different central aortic <span class="hlt">pressures</span> due to differential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAP...118q3102W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAP...118q3102W"><span>Experimental study on <span class="hlt">pressure</span>, stress state, and temperature-dependent dynamic behavior of shear thickening fluid subjected to laser <span class="hlt">induced</span> shock</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Xianqian; Yin, Qiuyun; Huang, Chenguang</p> <p>2015-11-01</p> <p>The dynamic response of the 57 vol./vol. % dense spherical silica particle-polyethylene glycol suspension at high <span class="hlt">pressure</span> was investigated through short pulsed laser <span class="hlt">induced</span> shock experiments by measuring the back free surface velocities of aluminum-shear thickening fluid (STF)-aluminum assembled targets. The results showed that the attenuation behavior of shock <span class="hlt">wave</span> in the STF was dependent on shock <span class="hlt">pressure</span>, stress state, and test temperature. The measured back free particle velocities of the targets and shock <span class="hlt">wave</span> velocities in the STF decreased with the decrease in shock <span class="hlt">pressure</span> while shocked at the same stress state and the same test temperature. In addition, two types of dragging mechanisms in the STF were observed while shocked at different stress states. For a uniaxial strain state, the impact <span class="hlt">induced</span> jamming behavior in the STF is the dragging mechanism for the attenuation of shock <span class="hlt">wave</span>, and a critical shock <span class="hlt">pressure</span> was required for the impact <span class="hlt">induced</span> thickening behavior. However, while the shock <span class="hlt">wave</span> transformed from a uniaxial strain state to a dilatation state after transmitted to a certain distance, beside the dragging effect of impact <span class="hlt">induced</span> jamming behavior, a strong dragging effect, <span class="hlt">induced</span> by shear <span class="hlt">induced</span> thickening behavior, was also observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17825347','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17825347"><span><span class="hlt">Wave</span> aberrations in rhesus monkeys with vision-<span class="hlt">induced</span> ametropias.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ramamirtham, Ramkumar; Kee, Chea-Su; Hung, Li-Fang; Qiao-Grider, Ying; Huang, Juan; Roorda, Austin; Smith, Earl L</p> <p>2007-09-01</p> <p>The purpose of this study was to investigate the relationship between refractive errors and high-order aberrations in infant rhesus monkeys. Specifically, we compared the monochromatic <span class="hlt">wave</span> aberrations measured with a Shack-Hartman wavefront sensor between normal monkeys and monkeys with vision-<span class="hlt">induced</span> refractive errors. Shortly after birth, both normal monkeys and treated monkeys reared with optically <span class="hlt">induced</span> defocus or form deprivation showed a decrease in the magnitude of high-order aberrations with age. However, the decrease in aberrations was typically smaller in the treated animals. Thus, at the end of the lens-rearing period, higher than normal amounts of aberrations were observed in treated eyes, both hyperopic and myopic eyes and treated eyes that developed astigmatism, but not spherical ametropias. The total RMS wavefront error increased with the degree of spherical refractive error, but was not correlated with the degree of astigmatism. Both myopic and hyperopic treated eyes showed elevated amounts of coma and trefoil and the degree of trefoil increased with the degree of spherical ametropia. Myopic eyes also exhibited a much higher prevalence of positive spherical aberration than normal or treated hyperopic eyes. Following the onset of unrestricted vision, the amount of high-order aberrations decreased in the treated monkeys that also recovered from the experimentally <span class="hlt">induced</span> refractive errors. Our results demonstrate that high-order aberrations are influenced by visual experience in young primates and that the increase in high-order aberrations in our treated monkeys appears to be an optical byproduct of the vision-<span class="hlt">induced</span> alterations in ocular growth that underlie changes in refractive error. The results from our study suggest that the higher amounts of <span class="hlt">wave</span> aberrations observed in ametropic humans are likely to be a consequence, rather than a cause, of abnormal refractive development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4286758','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4286758"><span>Artificial magnetic field <span class="hlt">induced</span> by an evanescent <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mochol, Małgorzata; Sacha, Krzysztof</p> <p>2015-01-01</p> <p>Cold atomic gases are perfect laboratories for realization of quantum simulators. In order to simulate solid state systems in the presence of magnetic fields special effort has to be made because atoms are charge neutral. There are different methods for realization of artificial magnetic fields, that is the creation of specific conditions so that the motion of neutral particles mimics the dynamics of charged particles in an effective magnetic field. Here, we consider adiabatic motion of atoms in the presence of an evanescent <span class="hlt">wave</span>. Theoretical description of the adiabatic motion involves artificial vector and scalar potentials related to the Berry phases. Due to the large gradient of the evanescent field amplitude, the potentials can be strong enough to <span class="hlt">induce</span> measurable effects in cold atomic gases. We show that the resulting artificial magnetic field is able to <span class="hlt">induce</span> vortices in a Bose-Einstein condensate trapped close to a surface of a prism where the evanescent <span class="hlt">wave</span> is created. We also analyze motion of an atomic cloud released from a magneto-optical trap that falls down on the surface of the prism. The artificial magnetic field is able to reflect falling atoms that can be observed experimentally. PMID:25567430</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.3694M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3694M"><span>Temporal pore <span class="hlt">pressure</span> <span class="hlt">induced</span> stress changes during injection and depletion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Müller, Birgit; Heidbach, Oliver; Schilling, Frank; Fuchs, Karl; Röckel, Thomas</p> <p>2016-04-01</p> <p><span class="hlt">Induced</span> seismicity is observed during injection of fluids in oil, gas or geothermal wells as a rather immediate response close to the injection wells due to the often high-rate <span class="hlt">pressurization</span>. It was recognized even earlier in connection with more moderate rate injection of fluid waste on a longer time frame but higher <span class="hlt">induced</span> event magnitudes. Today, injection-related <span class="hlt">induced</span> seismicity significantly increased the number of events with M>3 in the Mid U.S. However, <span class="hlt">induced</span> seismicity is also observed during production of fluids and gas, even years after the onset of production. E.g. in the Groningen gas field production was required to be reduced due to the increase in felt and damaging seismicity after more than 50 years of exploitation of that field. Thus, injection and production <span class="hlt">induced</span> seismicity can cause severe impact in terms of hazard but also on economic measures. In order to understand the different onset times of <span class="hlt">induced</span> seismicity we built a generic model to quantify the role of poro-elasticity processes with special emphasis on the factors time, regional crustal stress conditions and fault parameters for three case studies (injection into a low permeable crystalline rock, hydrothermal circulation and production of fluids). With this approach we consider the spatial and temporal variation of reservoir stress paths, the "early" injection-related <span class="hlt">induced</span> events during stimulation and the "late" production <span class="hlt">induced</span> ones. Furthermore, in dependence of the undisturbed in situ stress field conditions the stress tensor can change significantly due to injection and long-term production with changes of the tectonic stress regime in which previously not critically stressed faults could turn to be optimally oriented for fault reactivation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5239981','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5239981"><span>Bezafibrate Attenuates <span class="hlt">Pressure</span> Overload-<span class="hlt">Induced</span> Cardiac Hypertrophy and Fibrosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Si-Chi; Ma, Zhen-Guo; Wei, Wen-Ying; Yuan, Yu-Pei</p> <p>2017-01-01</p> <p>Background. Peroxisome proliferator-activated receptor-α (PPAR-α) is closely associated with the development of cardiac hypertrophy. Previous studies have indicated that bezafibrate (BZA), a PPAR-α agonist, could attenuate insulin resistance and obesity. This study was designed to determine whether BZA could protect against <span class="hlt">pressure</span> overload-<span class="hlt">induced</span> cardiac hypertrophy. Methods. Mice were orally given BZA (100 mg/kg) for 7 weeks beginning 1 week after aortic banding (AB) surgery. Cardiac hypertrophy was assessed based on echocardiographic, histological, and molecular aspects. Moreover, neonatal rat ventricular cardiomyocytes (NRVMs) were used to investigate the effects of BZA on the cardiomyocyte hypertrophic response in vitro. Results. Our study demonstrated that BZA could alleviate cardiac hypertrophy and fibrosis in mice subjected to AB surgery. BZA treatment also reduced the phosphorylation of protein kinase B (AKT)/glycogen synthase kinase-3β (GSK3β) and mitogen-activated protein kinases (MAPKs). BZA suppressed phenylephrine- (PE-) <span class="hlt">induced</span> hypertrophy of cardiomyocyte in vitro. The protective effects of BZA were abolished by the treatment of the PPAR-α antagonist in vitro. Conclusions. BZA could attenuate <span class="hlt">pressure</span> overload-<span class="hlt">induced</span> cardiac hypertrophy and fibrosis. PMID:28127304</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3341048','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3341048"><span>Buckling-<span class="hlt">induced</span> encapsulation of structured elastic shells under <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shim, Jongmin; Perdigou, Claude; Chen, Elizabeth R.; Bertoldi, Katia; Reis, Pedro M.</p> <p>2012-01-01</p> <p>We introduce a class of continuum shell structures, the Buckliball, which undergoes a structural transformation <span class="hlt">induced</span> by buckling under <span class="hlt">pressure</span> loading. The geometry of the Buckliball comprises a spherical shell patterned with a regular array of circular voids. In order for the pattern transformation to be <span class="hlt">induced</span> by buckling, the possible number and arrangement of these voids are found to be restricted to five specific configurations. Below a critical internal <span class="hlt">pressure</span>, the narrow ligaments between the voids buckle, leading to a cooperative buckling cascade of the skeleton of the ball. This ligament buckling leads to closure of the voids and a reduction of the total volume of the shell by up to 54%, while remaining spherical, thereby opening the possibility of encapsulation. We use a combination of precision desktop-scale experiments, finite element simulations, and scaling analyses to explore the underlying mechanics of these foldable structures, finding excellent qualitative and quantitative agreement. Given that this folding mechanism is <span class="hlt">induced</span> by a mechanical instability, our Buckliball opens the possibility for reversible encapsulation, over a wide range of length scales. PMID:22451901</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27165882','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27165882"><span>The Correlation Between Intracranial <span class="hlt">Pressure</span> and Cerebral Blood Flow Velocity During ICP Plateau <span class="hlt">Waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lewis, Philip M; Smielewski, Peter; Rosenfeld, Jeffrey V; Pickard, John D; Czosnyka, Marek</p> <p>2016-01-01</p> <p>We previously showed that the flow-ICP index (Fix), a moving correlation coefficient between intracranial <span class="hlt">pressure</span> (ICP) and cerebral blood flow velocity (CBFV), had marginally greater prognostic value for patients with traumatic brain injury (TBI) than an index of cerebral autoregulation (mean index, Mx). The aim of this study was to further examine the clinical and physiological relevance of Fix by studying its behaviour during ICP plateau <span class="hlt">waves</span> in patients with TBI. Twenty-nine recordings of CBFV made during ICP plateau <span class="hlt">waves</span> were analysed. Both Mx and Fix at baseline and peak ICP were significantly different, although the magnitude of Fix change was slightly greater. The correlation between Fix and cerebral perfusion <span class="hlt">pressure</span> (CPP) was stronger than that between Mx and CPP. Unlike in our previous study, plotting Fix against CPP revealed a peak value in the range of "optimal" CPP, as indicated by the Mx versus CPP plot. The findings suggest that during periods of reduced CPP caused by plateau <span class="hlt">waves</span>, the dynamic behaviour of Fix is similar to that of a measure of cerebral autoregulation. This conclusion needs to be verified against similar results obtained during episodes of supranormal CPP.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19812454','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19812454"><span>Automated identification of peristaltic <span class="hlt">pressure</span> <span class="hlt">waves</span> in oesophageal manometry investigations using the rolling correlation technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perring, S; Jones, E</p> <p>2009-11-01</p> <p>We have implemented the technique of rolling correlation coefficient as proposed by Buttfield and Bolton (2005 Real time measurement of RR intervals using a digital signal processor J. Med. Eng. Technol. 29 8-13) for ECG R-<span class="hlt">wave</span> detection in the detection and timing of oesophageal peristalsis. 43 sequential patients attending for oesophageal manometry were retrospectively reviewed. Two expert reviewers visually assessed each swallow for normality of peristaltic amplitude and propagation speed. Automatic assessment was performed using rolling correlation, maximum amplitude, threshold and maximum gradient techniques of identifying onset of peristalsis. Rolling correlation was comparable with the maximum amplitude technique at identifying peristaltic <span class="hlt">pressure</span> <span class="hlt">waves</span> visually identified as present. Rolling correlation was most effective at correctly identifying propagation velocity as normal (698 out of 845 normally propagating <span class="hlt">waves</span>) and highest correlation with expert visual assessment of percentage abnormal propagation for each patient (R value 0.918). In a sub-group of 11 studies assessed as displaying normal motility, rolling correlation gave lowest variation of propagation speed and highest consistency with visual assessment. The rolling correlation technique is effective and accurate at identifying oesophageal peristalsis and characterizing peristaltic propagation in manometric studies even in the presence of abnormally weak peristalsis and other confounding <span class="hlt">pressure</span> perturbations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840025864&hterms=Atmospheric+pressure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DAtmospheric%2Bpressure','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840025864&hterms=Atmospheric+pressure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DAtmospheric%2Bpressure"><span>Experimental validation of a millimeter <span class="hlt">wave</span> radar technique to remotely sense atmospheric <span class="hlt">pressure</span> at the Earth's surface</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Flower, D. A.; Peckham, G. E.; Bradford, W. J.</p> <p>1984-01-01</p> <p>Experiments with a millimeter <span class="hlt">wave</span> radar operating on the NASA CV-990 aircraft which validate the technique for remotely sensing atmospheric <span class="hlt">pressure</span> at the Earth's surface are described. Measurements show that the precise millimeter <span class="hlt">wave</span> observations needed to deduce <span class="hlt">pressure</span> from space with an accuracy of 1 mb are possible, that sea surface reflection properties agree with theory and that the measured variation of differential absorption with altitude corresponds to that expected from spectroscopic models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4974634','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4974634"><span>The <span class="hlt">Pressure</span> <span class="hlt">induced</span> by salt crystallization in confinement</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Desarnaud, J.; Bonn, D.; Shahidzadeh, N.</p> <p>2016-01-01</p> <p>Salt crystallization is a major cause of weathering of rocks, artworks and monuments. Damage can only occur if crystals continue to grow in confinement, i.e. within the pore space of these materials, thus generating mechanical stress. We report the direct measurement, at the microscale, of the force exerted by growing alkali halide salt crystals while visualizing their spontaneous nucleation and growth. The experiments reveal the crucial role of the wetting films between the growing crystal and the confining walls for the development of the <span class="hlt">pressure</span>. Our results suggest that the measured force originates from repulsion between the similarly charged confining wall and the salt crystal separated by a ~1.5 nm liquid film. Indeed, if the walls are made hydrophobic, no film is observed and no repulsive forces are detected. We also show that the magnitude of the <span class="hlt">induced</span> <span class="hlt">pressure</span> is system specific explaining why different salts lead to different amounts of damage to porous materials. PMID:27493020</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Nanot..21j5706Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Nanot..21j5706Z"><span>Negative capillary-<span class="hlt">pressure-induced</span> cavitation probability in nanochannels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ruijing; Ikoma, Yoshifumi; Motooka, Teruaki</p> <p>2010-03-01</p> <p>The capillarity-<span class="hlt">induced</span> negative <span class="hlt">pressure</span> of water flow has been investigated in nanochannels of a rectangular cross section by using computational fluid dynamics (CFD) simulation. As a consequent effect of negative <span class="hlt">pressure</span>, the cavitation probability has been analyzed numerically. The numerical relation between the critical radius of cavitation (Rc) and geometrical characteristics of channels shows that cavitation does not occur in channels of uniform cross section (UCS), since 2Rc is larger than the smallest dimension of the channel. However, it may occur in channels of non-uniform cross section (NUCS), except for planar or high aspect ratio channels. The inequality in height and width is favorable for the absence of cavitation. The findings can also be applied to channels of elliptical or circular cross section. The results show the influence of geometrical characteristics of channels on the cavitation probability, which is important to engineer the channel geometrical structure in order to avoid undesirable filling problem 'cavitation' during the flow process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PEPS....3...18O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PEPS....3...18O"><span>Ultrahigh-<span class="hlt">pressure</span> acoustic <span class="hlt">wave</span> velocities of SiO2-Al2O3 glasses up to 200 GPa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ohira, Itaru; Murakami, Motohiko; Kohara, Shinji; Ohara, Koji; Ohtani, Eiji</p> <p>2016-12-01</p> <p>Extensive experimental studies on the structure and density of silicate glasses as laboratory analogs of natural silicate melts have attempted to address the nature of dense silicate melts that may be present at the base of the mantle. Previous ultrahigh-<span class="hlt">pressure</span> experiments, however, have been performed on simple systems such as SiO2 or MgSiO3, and experiments in more complex system have been conducted under relatively low-<span class="hlt">pressure</span> conditions below 60 GPa. The effect of other metal cations on structural changes that occur in dense silicate glasses under ultrahigh <span class="hlt">pressures</span> has been poorly understood. Here, we used a Brillouin scattering spectroscopic method up to <span class="hlt">pressures</span> of 196.9 GPa to conduct in situ high-<span class="hlt">pressure</span> acoustic <span class="hlt">wave</span> velocity measurements of SiO2-Al2O3 glasses in order to understand the effect of Al2O3 on <span class="hlt">pressure-induced</span> structural changes in the glasses as analogs of aluminosilicate melts. From 10 to 40 GPa, the transverse acoustic <span class="hlt">wave</span> velocity ( V S ) of Al2O3-rich glass (SiO2 + 20.5 mol% Al2O3) was greater than that of Al2O3-poor glass (SiO2 + 3.9 mol% Al2O3). This result suggests that SiO2-Al2O3 glasses with higher proportions of Al ions with large oxygen coordination numbers (5 and 6) become elastically stiffer up to 40 GPa, depending on the Al2O3 content, but then soften above 40 GPa. At <span class="hlt">pressures</span> from 40 to ~100 GPa, the increase in V S with increasing <span class="hlt">pressure</span> became less steep than below 40 GPa. Above ~100 GPa, there were abrupt increases in the P-V S gradients ( dV S /dP) at 130 GPa in Al2O3-poor glass and at 116 GPa in Al2O3-rich glass. These changes resemble previous experimental results on SiO2 glass and MgSiO3 glass. Given that changes of dV S / dP have commonly been related to changes in the Si-O coordination states in the glasses, our results, therefore, may indicate a drastic structural transformation in SiO2-Al2O3 glasses above 116 GPa, possibly associated with an average Si-O coordination number change to higher than 6. Compared</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24a3511W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24a3511W"><span>Modeling and simulations on the propagation characteristics of electromagnetic <span class="hlt">waves</span> in sub-atmospheric <span class="hlt">pressure</span> plasma slab</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Z. B.; Nie, Q. Y.; Li, B. W.; Kong, F. R.</p> <p>2017-01-01</p> <p>Sub-atmospheric <span class="hlt">pressure</span> plasma slabs exhibit the feature of relatively high plasma number density and high collisional frequency between electrons and neutral gases, as well as similar thickness to the electromagnetic (EM) wavelength in communication bands. The propagation characteristics of EM <span class="hlt">waves</span> in sub-atmospheric <span class="hlt">pressure</span> plasma slabs are attracting much attention of the researchers due to their applications in the plasma antenna, the blackout effect during reentry, <span class="hlt">wave</span> energy injection in the plasma, etc. In this paper, a numerical model with a one-dimensional assumption has been established and therefore, it is used for the investigations of the propagation characteristics of the EM <span class="hlt">waves</span> in plasma slabs. In this model, the EM <span class="hlt">waves</span> propagating in both sub-wavelength plasma slabs and plasmas with thicker slabs can be studied simultaneously, which is superior to the model with geometrical optics approximation. The influence of EM <span class="hlt">wave</span> frequencies and collisional frequencies on the amplitude of the transmitted EM <span class="hlt">waves</span> is discussed in typical plasma profiles. The results will be significant for deep understanding of the propagation behaviors of the EM <span class="hlt">waves</span> in sub-atmospheric <span class="hlt">pressure</span> nonuniform plasma slabs, as well as the applications of the interactions between EM <span class="hlt">waves</span> and the sub-atmospheric <span class="hlt">pressure</span> plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013OptLT..45..540F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013OptLT..45..540F"><span>Effects of the air <span class="hlt">pressure</span> on the <span class="hlt">wave</span>-packet dynamics of gaseous iodine molecules at room temperature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, Rongwei; He, Ping; Chen, Deying; Xia, Yuanqin; Yu, Xin; Wang, Jialing; Jiang, Yugang</p> <p>2013-02-01</p> <p>Based on ultrafast laser pulses, time-resolved resonance enhancement coherent anti-Stokes Raman scattering (RE-CARS) is applied to investigate <span class="hlt">wave</span>-packet dynamics in gaseous iodine. The effects of air <span class="hlt">pressure</span> on the <span class="hlt">wave</span>-packet dynamics of iodine molecules are studied at <span class="hlt">pressures</span> ranging from 1.5 Torr to 750 Torr. The RE-CARS signals are recorded in a gas cell filled with a mixture of about 0.3 Torr iodine in air buffer gas at room temperature. The revivals and fractional revival structures in the <span class="hlt">wave</span>-packet signal are found to gradually disappear with rising air <span class="hlt">pressure</span> up to 750 Torr, and the decay behaviors of the excited B-state and ground X-state become faster with increasing air <span class="hlt">pressure</span>, which is due to the collision effects of the molecules and the growing complexity of the spectra at high <span class="hlt">pressures</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24812515','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24812515"><span>The 24-hour pulse <span class="hlt">wave</span> velocity, aortic augmentation index, and central blood <span class="hlt">pressure</span> in normotensive volunteers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kuznetsova, Tatyana Y; Korneva, Viktoria A; Bryantseva, Evgeniya N; Barkan, Vitaliy S; Orlov, Artemy V; Posokhov, Igor N; Rogoza, Anatoly N</p> <p>2014-01-01</p> <p>The purpose of this study was to examine the pulse <span class="hlt">wave</span> velocity, aortic augmentation index corrected for heart rate 75 (AIx@75), and central systolic and diastolic blood <span class="hlt">pressure</span> during 24-hour monitoring in normotensive volunteers. Overall, 467 subjects (206 men and 261 women) were recruited in this study. Participants were excluded from the study if they were less than 19 years of age, had blood test abnormalities, had a body mass index greater than 2 7.5 kg/m(2), had impaired glucose tolerance, or had hypotension or hypertension. Ambulatory blood <span class="hlt">pressure</span> monitoring (ABPM) with the BPLab(®) device was performed in each subject. ABPM waveforms were analyzed using the special automatic Vasotens(®) algorithm, which allows the calculation of pulse <span class="hlt">wave</span> velocity, AIx@75, central systolic and diastolic blood <span class="hlt">pressure</span> for "24-hour", "awake", and "asleep" periods. Circadian rhythms and sex differences in these indexes were identified. Pending further validation in prospective outcome-based studies, our data may be used as preliminary diagnostic values for the BPLab ABPM additional index in adult subjects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IJCMS...450015V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJCMS...450015V"><span><span class="hlt">Pressure</span> <span class="hlt">induced</span> stiffening, thermal softening of bulk modulus and brittle nature of mercury chalcogenides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varshney, Dinesh; Shriya, Swarna; Sapkale, Raju; Varshney, Meenu; Ameri, M.</p> <p>2015-07-01</p> <p>The <span class="hlt">pressure</span> and temperature dependent elastic properties of mercury chalcogenides (HgX; X = S, Se and Te) with <span class="hlt">pressure</span> <span class="hlt">induced</span> structural transition from ZnS-type (B3) to NaCl-type (B1) structure have been analyzed within the framework of a model interionic interaction potential with long-range Coulomb and charge transfer interactions, short-range overlap repulsion and van der Waals (vdW) interactions as well as zero point energy effects. Emphasis is on the evaluation of the Bulk modulus with <span class="hlt">pressure</span> and temperature dependency to yield the Poisson's ratio ν, the Pugh ratio ϕ, anisotropy parameter, Shear and Young's modulus, Lamé's constant, Klein man parameter, elastic <span class="hlt">wave</span> velocity and Debye temperature. The Poisson's ratio behavior infers that HgX are brittle in nature. To our knowledge this is the first quantitative theoretical prediction of the <span class="hlt">pressure</span> dependence of elastic and thermodynamical properties explicitly the ductile (brittle) nature of HgX and still awaits experimental confirmations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JGR....98.9781R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JGR....98.9781R"><span>Analysis of porous media heterogeneities using the diffusion of <span class="hlt">pressure</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rigord, P.; Caristan, Y.; Hulin, J. P.</p> <p>1993-06-01</p> <p>We present an experimental study and a model of the diffusion of sinusoidal <span class="hlt">pressure</span> <span class="hlt">waves</span> through porous media. We show that measurements of the hydraulic admittance A(omega) in the sine <span class="hlt">wave</span> mode allow us to probe the structure of porous samples with an adjustable investigation depth depending on the frequency omega. The variations of A(omega) in heterogeneous media with a percolationlike geometry are modeled numerically on 2D percolation networks. One obtains a transition from normal diffusion at low frequencies to anomalous diffusion at higher frequencies. At the transition, the penetration depth of the <span class="hlt">wave</span> is of the order of the percolation correlation length. The hydraulic admittance and transmittance of 20 percent porosity pressed calcite have been investigated experimentally with sine <span class="hlt">wave</span> excitations at pulsations omega between 2 x 10 exp -4 and 0.42 rad/s. Both the modulus and the phase of the complex admittance A(omega) display normal diffusive variations as omega increases. Increasing the viscosity reduces the frequency above which the diffusive behavior is observed. The measured diffusion coefficient is 25 percent higher than that computed from permeability and compressibility values measured independently; this difference may be associated with nonconnected porosity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JFST....5..235A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JFST....5..235A"><span><span class="hlt">Pressure</span> Generation from Micro-Bubble Collapse at Shock <span class="hlt">Wave</span> Loading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abe, Akihisa; Ohtani, Kiyonobu; Takayama, Kazuyoshi; Nishio, Shigeru; Mimura, Haruo; Takeda, Minoru</p> <p></p> <p>This paper reports the result of a primary experimental and analytical study used to explore a reliable technology that is potentially applicable to the inactivation of micro-creatures contained in ship ballast water. A shock <span class="hlt">wave</span> generated by the micro-explosion of a 10mg silver azide pellet in a 10mm wide parallel test section was used to interact with a bubble cloud consisting of bubbles with average diameter 10µm produced by a swirling flow type micro-bubble generator. Observations were carried out with a high-speed camera, IMACON200, and the corresponding rebound <span class="hlt">pressures</span> of the collapsing bubbles were measured with a fiber optic probe <span class="hlt">pressure</span> transducer that provides high spatial and temporal resolutions. We found that micro-bubbles collapse in several hundred nanoseconds after the shock exposure and the resulting peak <span class="hlt">pressure</span> pulses that repeatedly occurred exceeded well over 200MPa measured at the 20mm distance from the explosion center. These continued for well over 20µs. The experimental <span class="hlt">pressure</span> responses were explained by solving the one-dimensional bubble Rayleigh-Plesset equation. Such high peak <span class="hlt">pressures</span> could be used effectively for the inactivation of micro-creatures contained in ship ballast water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110022626','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110022626"><span>A Study of Standing <span class="hlt">Pressure</span> <span class="hlt">Waves</span> Within Open and Closed Acoustic Resonators</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Daniels, C.; Steinetz, B.; Finkbeiner, J.; Raman, G.; Li, X.</p> <p>2002-01-01</p> <p>The first section of the results presented herein was conducted on an axisymmetric resonator configured with open ventilation ports on either end of the resonator, but otherwise closed and free from obstruction. The remaining section presents the results of a similar resonator shape that was closed, but contained an axisymmetric blockage centrally located through the axis of the resonator. Ambient air was used as the working fluid. In each of the studies, the resonator was oscillated at the resonant frequency of the fluid contained within the cavity while the dynamic <span class="hlt">pressure</span>, static <span class="hlt">pressure</span>, and temperature of the fluid were recorded at both ends of the resonator. The baseline results showed a marked reduction in the amplitude of the dynamic <span class="hlt">pressure</span> waveforms over previous studies due to the use of air instead of refrigerant as the working fluid. A sharp reduction in the amplitude of the acoustic <span class="hlt">pressure</span> <span class="hlt">waves</span> was expected and recorded when the configuration of the resonators was modified from closed to open. A change in the resonant frequency was recorded when blockages of differing geometries were used in the closed resonator, while acoustic <span class="hlt">pressure</span> amplitudes varied little from baseline measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.5587T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.5587T"><span>Horizontal variability of high-frequency nonlinear internal <span class="hlt">waves</span> in Massachusetts Bay detected by an array of seafloor <span class="hlt">pressure</span> sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, J. A.; Lerczak, J. A.; Moum, J. N.</p> <p>2016-08-01</p> <p>A two-dimensional array of 14 seafloor <span class="hlt">pressure</span> sensors was deployed to measure properties of tidally generated, nonlinear, high-frequency internal <span class="hlt">waves</span> over a 14 km by 12 km area west of Stellwagen Bank in Massachusetts Bay during summer 2009. Thirteen high-frequency internal <span class="hlt">wave</span> packets propagated through the region over 6.5 days (one packet every semidiurnal cycle). Propagation speed and direction of <span class="hlt">wave</span> packets were determined by triangulation, using arrival times and distances between triads of sensor locations. Wavefront curvature ranged from straight to radially spreading, with <span class="hlt">wave</span> speeds generally faster to the south. <span class="hlt">Waves</span> propagated to the southwest, rotating to more westward with shoreward propagation. Linear theory predicts a relationship between kinetic energy and bottom <span class="hlt">pressure</span> variance of internal <span class="hlt">waves</span> that is sensitive to sheared background currents, water depth, and stratification. By comparison to seafloor acoustic Doppler current profiler measurements, observations nonetheless show a strong relationship between kinetic energy and bottom <span class="hlt">pressure</span> variance. This is presumably due to phase-locking of the <span class="hlt">wave</span> packets to the internal tide that dominates background currents and to horizontally uniform and relatively constant stratification throughout the study. This relationship was used to qualitatively describe variations in kinetic energy of the high-frequency <span class="hlt">wave</span> packets. In general, high-frequency internal <span class="hlt">wave</span> kinetic energy was greater near the southern extent of wavefronts and greatly decreased upon propagating shoreward of the 40 m isobath.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..DFD.MJ002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..DFD.MJ002B"><span>Droplet actuation by surface acoustic <span class="hlt">waves</span>: an interplay between acoustic streaming and radiation <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brunet, Philippe; Baudoin, Michael; Matar, Olivier Bou; Zoueshtiagh, Farzam</p> <p>2010-11-01</p> <p>Surface acoustic <span class="hlt">waves</span> (SAW) are known to be a versatile technique for the actuation of sessile drops. Droplet displacement, internal mixing or drop splitting, are amongst the elementary operations that SAW can achieve, which are useful on lab-on-chip microfluidics benches. On the purpose to understand the underlying physical mechanisms involved during these operations, we study experimentally the droplet dynamics varying different physical parameters. Here in particular, the influence of liquid viscosity and acoustic frequency is investigated: it is indeed predicted that both quantities should play a role in the acoustic-hydrodynamic coupling involved in the dynamics. The key point is to compare the relative magnitude of the attenuation length, i.e. the scale within which the acoustic <span class="hlt">wave</span> decays in the fluid, and the size of the drop. This relative magnitude governs the relative importance of acoustic streaming and acoustic radiation <span class="hlt">pressure</span>, which are both involved in the droplet dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22505642','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22505642"><span>Cyclooxygenase inhibition augments central blood <span class="hlt">pressure</span> and aortic <span class="hlt">wave</span> reflection in aging humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barnes, Jill N; Casey, Darren P; Hines, Casey N; Nicholson, Wayne T; Joyner, Michael J</p> <p>2012-06-15</p> <p>The augmentation index and central blood <span class="hlt">pressure</span> increase with normal aging. Recently, cyclooxygenase (COX) inhibitors, commonly used for the treatment of pain, have been associated with transient increases in the risk of cardiovascular events. We examined the effects of the COX inhibitor indomethacin (Indo) on central arterial hemodynamics and <span class="hlt">wave</span> reflection characteristics in young and old healthy adults. High-fidelity radial arterial <span class="hlt">pressure</span> waveforms were measured noninvasively by applanation tonometry before (control) and after Indo treatment in young (25 ± 5 yr, 7 men and 6 women) and old (64 ± 6 yr, 5 men and 6 women) subjects. Aortic systolic (control: 115 ± 3 mmHg vs. Indo: 125 ± 5 mmHg, P < 0.05) and diastolic (control: 74 ± 2 mmHg vs. Indo: 79 ± 3 mmHg, P < 0.05) <span class="hlt">pressures</span> were elevated after Indo treatment in older subjects, whereas only diastolic <span class="hlt">pressure</span> was elevated in young subjects (control: 71 ± 2 mmHg vs. Indo: 76 ± 1 mmHg, P < 0.05). Mean arterial <span class="hlt">pressure</span> increased in both young and old adults after Indo treatment (P < 0.05). The aortic augmentation index and augmented <span class="hlt">pressure</span> were elevated after Indo treatment in older subjects (control: 30 ± 5% vs. Indo 36 ± 6% and control 12 ± 1 mmHg vs. Indo: 18 ± 2 mmHg, respectively, P < 0.05), whereas pulse <span class="hlt">pressure</span> amplification decreased (change: 8 ± 3%, P < 0.05). In addition, older subjects had a 61 ± 11% increase in wasted left ventricular energy after Indo treatment (P < 0.05). In contrast, young subjects showed no significant changes in any of the variables of interest. Taken together, these results demonstrate that COX inhibition with Indo unfavorably increases central <span class="hlt">wave</span> reflection and augments aortic <span class="hlt">pressure</span> in old but not young subjects. Our results suggest that aging individuals have a limited ability to compensate for the acute hemodynamic changes caused by systemic COX inhibition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJD...68...46H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJD...68...46H"><span>Plasmid DNA damage <span class="hlt">induced</span> by helium atmospheric <span class="hlt">pressure</span> plasma jet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia</p> <p>2014-03-01</p> <p>A helium atmospheric <span class="hlt">pressure</span> plasma jet (APPJ) is applied to <span class="hlt">induce</span> damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level <span class="hlt">induced</span> in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9546Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9546Z"><span>Unusual properties of high-compliance porosity extracted from measurements of <span class="hlt">pressure</span>-dependent <span class="hlt">wave</span> velocities in rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaitsev, Vladimir Y.; Radostin, Andrey V.; Pasternak, Elena; Dyskin, Arcady</p> <p>2016-04-01</p> <p>Conventionally the interpretation of <span class="hlt">wave</span> velocities and their variations under load is conducted assuming that closable cracks have simple planar shapes, like the popular model of penny-shape cracks. For such cracks, the proportion between complementary variations in different elastic parameters of rocks (such as S- and P-<span class="hlt">wave</span> velocities) is strictly pre-determined, in particular, it is independent of the crack aspect ratio and rather weakly dependent on the Poisson's ratio of the intact rock. Real rocks, however, contain multitude of cracks of different geometry. Faces of such cracks can exhibit complex modes of interaction when closed by external load, which may result in very different ratios between normal- and shear compliances of such defects. In order to describe the reduction of different elastic moduli, we propose a model in which the compliances of crack-like defects are explicitly decoupled and are not predetermined, so that the ratio q between total normal- and shear- compliances imparted to the rock mass (as well as individual values of these compliances) can be estimated from experimental data on reduction of different elastic moduli (e.g., <span class="hlt">pressure</span> dependences of P- and S-<span class="hlt">wave</span> velocities). Physically, the so-extracted ratio q can be interpreted as intrinsic property of individual crack-like defects similar to each other, or as a characteristic of proportion between concentrations of pure normal cracks with very large q and pure shear cracks with q→0. The latter case can correspond, e.g., to saturated cracks in which weakly-compressible liquid prevents crack closing under normal loading. It can be shown that for conventional dry planar cracks, the compliance ratio is q ˜2. The developed model applied to the data on <span class="hlt">wave</span>-velocity variations with external <span class="hlt">pressure</span> indicates that elastic properties of the real crack-like defects in rocks can differ considerably from the usually assumed ones. Comparison with experimental data on variations P- and S-<span class="hlt">wave</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18835205','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18835205"><span>Continuous-<span class="hlt">wave</span> far-infrared ESR spectrometer for high-<span class="hlt">pressure</span> measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Náfrádi, Bálint; Gaál, Richárd; Sienkiewicz, Andrzej; Fehér, Titusz; Forró, László</p> <p>2008-12-01</p> <p>We present a newly-developed microwave probe for performing sensitive high-field/multi-frequency electron spin resonance (ESR) measurements under high hydrostatic <span class="hlt">pressures</span>. The system consists of a BeCu-made <span class="hlt">pressure</span>-resistant vessel, which accommodates the investigated sample and a diamond microwave coupling window. The probe's interior is completely filled with a <span class="hlt">pressure</span>-transmitting fluid. The setup operates in reflection mode and can easily be assembled with a standard oversized microwave circuitry. The probe-head withstands hydrostatic <span class="hlt">pressures</span> up to 1.6 GPa and interfaces with our home-built quasi-optical high-field ESR facility, operating in a millimeter/submillimeter frequency range of 105-420 GHz and in magnetic fields up to 16 T. The overall performance of the probe was tested, while studying the <span class="hlt">pressure-induced</span> changes in the spin-relaxation mechanisms of a quasi-1D conducting polymer, KC(60). The preliminary measurements revealed that the probe yields similar signal-to-noise ratio to that of commercially available low-frequency ESR spectrometers. Moreover, by observing the conduction electron spin resonance (CESR) linewidth broadening for KC(60) in an unprecedented microwave frequency range of 210-420 GHz and in the <span class="hlt">pressure</span> range of up to 1.6 GPa, we demonstrate that a combination of high-<span class="hlt">pressure</span> ESR probe and high-field/multi-frequency spectrometer allows us to measure the spin relaxation rates in conducting spin systems, like the quasi-1D conductor, KC(60).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4765376','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4765376"><span>Ultrasound Shear <span class="hlt">Wave</span> Elasticity Imaging Quantifies Coronary Perfusion <span class="hlt">Pressure</span> Effect on Cardiac Compliance</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nagle, Matt; Trahey, Gregg E.; Wolf, Patrick D.</p> <p>2016-01-01</p> <p>Diastolic heart failure (DHF) is a major source of cardiac related morbidity and mortality in the world today. A major contributor to, or indicator of DHF is a change in cardiac compliance. Currently, there is no accepted clinical method to evaluate the compliance of cardiac tissue in diastolic dysfunction. Shear <span class="hlt">wave</span> elasticity imaging (SWEI) is a novel ultrasound-based elastography technique that provides a measure of tissue stiffness. Coronary perfusion <span class="hlt">pressure</span> affects cardiac stiffness during diastole; we sought to characterize the relationship between these two parameters using the SWEI technique. In this work, we demonstrate how changes in coronary perfusion <span class="hlt">pressure</span> are reflected in a local SWEI measurement of stiffness during diastole. Eight Langendorff perfused isolated rabbit hearts were used in this study. Coronary perfusion <span class="hlt">pressure</span> was changed in a randomized order (0–90 mmHg range) and SWEI measurements were recorded during diastole with each change. Coronary perfusion <span class="hlt">pressure</span> and the SWEI measurement of stiffness had a positive linear correlation with the 95% confidence interval (CI) for the slope of 0.009–0.011 m/s/mmHg (R2 = 0.88). Furthermore, shear modulus was linearly correlated to the coronary perfusion <span class="hlt">pressure</span> with the 95% CI of this slope of 0.035–0.042 kPa/mmHg (R2 = 0.83). In conclusion, diastolic SWEI measurements of stiffness can be used to characterize factors affecting cardiac compliance specifically the mechanical interaction (cross-talk) between perfusion <span class="hlt">pressure</span> in the coronary vasculature and cardiac muscle. This relationship was found to be linear over the range of <span class="hlt">pressures</span> tested. PMID:25291788</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhyB..404..373M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhyB..404..373M"><span>Fluctuation of the charge density <span class="hlt">wave</span> in TTF-TCNQ under high <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murata, Keizo; Weng, Yufeng; Seno, Yuki; Rani Tamilselvan, Natarajan; Kobayashi, Kensuke; Arumugam, Sonachalam; Takashima, Yusaku; Yoshino, Harukazu; Kato, Reizo</p> <p>2009-03-01</p> <p>Temperature dependence of the resistivity of TTF-TCNQ along the b-(1D)- and a-axes was studied under hydrostatic <span class="hlt">pressure</span> up to 8 GPa. A striking contrast was seen between the b-(1D)- and a-axes in the power-law dependence of resistivity ρ=ρ0Tα in the metallic region as well as the activation energy in the charge density <span class="hlt">wave</span> (CDW) insulating state. We note that the careful terminal configuration is essentially important to obtain these properties.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Nanos...5.3266K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Nanos...5.3266K"><span>Formation of silicon nanoparticles by a <span class="hlt">pressure</span> <span class="hlt">induced</span> nucleation mechanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Myung-Koo; Kim, Si Joon; Kim, Hyun Jae</p> <p>2013-03-01</p> <p>Formation of silicon nanoparticles (SiNPs) was achieved using excimer laser crystallization of an amorphous Si (a-Si) thin film using a SiO2 capping layer (C/L) with improved thin-film transistor (TFT) performance due to the enlarged grain size of polycrystalline Si (poly-Si). After laser irradiation of an a-Si thin film covered with C/L, fluctuation in the surface morphology of the C/L was observed above the critical laser energy density (Ecr) with the formation of SiNPs. The grain size of the poly-Si layer after crystallization increased abruptly at the same time. A non-uniform <span class="hlt">pressure</span> distribution beneath the SiO2 C/L was proposed for the initiation of nucleation, which is named <span class="hlt">pressure</span> <span class="hlt">induced</span> nucleation (PIN) mechanism. Following nucleation, the release of latent heat made it difficult for the remnant liquid Si to solidify and the volume increased due to the density difference between the liquid and solid Si. Consequently, the <span class="hlt">pressure</span> on the liquid Si caused SiNPs to sprout through the SiO2 C/L as grains grew from the low temperature to high temperature point. This study offers not only a simple method to fabricate SiNPs with controllable size/density but also larger grain size with lower laser energy density, which leads to higher TFT performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=work+AND+home&pg=6&id=EJ730123','ERIC'); return false;" href="http://eric.ed.gov/?q=work+AND+home&pg=6&id=EJ730123"><span>The Loss Spiral of Work <span class="hlt">Pressure</span>, Work-Home Interference and Exhaustion: Reciprocal Relations in a Three-<span class="hlt">Wave</span> Study</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Demerouti, Evangelia; Bakker, Arnold B.; Bulters, Annemieke J.</p> <p>2004-01-01</p> <p>This study tested the "loss spiral" hypothesis of work-home interference (WHI). Accordingly, work <span class="hlt">pressure</span> was expected to lead to WHI and exhaustion, and, vice versa, exhaustion was expected to result in more WHI and work <span class="hlt">pressure</span> over time. Results of SEM-analyses using three <span class="hlt">waves</span> of data obtained from 335 employees of an employment agency…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25316410','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25316410"><span>Enhanced acoustic sensing through <span class="hlt">wave</span> compression and <span class="hlt">pressure</span> amplification in anisotropic metamaterials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao</p> <p>2014-10-15</p> <p>Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental <span class="hlt">pressure</span> detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong <span class="hlt">wave</span> compression effect that renders direct amplification of <span class="hlt">pressure</span> fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.2660S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.2660S"><span>A novel method for analyzing seismic energy loss associated with <span class="hlt">wave-induced</span> fluid flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Solazzi, Santiago G.; Germán Rubino, J.; Müller, Tobias M.; Milani, Marco; Guarracino, Luis; Holliger, Klaus</p> <p>2014-05-01</p> <p>Whenever a seismic <span class="hlt">wave</span> propagates through a fluid saturated porous rock that contains heterogeneities in the mesoscopic scale, that is, heterogeneities larger than the typical pore size but smaller than the predominant wavelengths, local gradients in the pore-fluid <span class="hlt">pressure</span> arise. These <span class="hlt">pressure</span> gradients, which are due to the uneven response of the heterogeneities to the stress applied by the passing seismic wavefield, <span class="hlt">induce</span> viscous fluid flow and energy dissipation. Consequently, seismic <span class="hlt">waves</span> tend to be strongly attenuated and dispersed in this kind of media. This attenuation mechanism scales with the compressibility contrast between heterogeneities and the background. Correspondingly, environments characterized by patchy saturation as well as fractured media represent two prominent scenarios where seismic attenuation due to <span class="hlt">wave-induced</span> fluid flow is expected to be the predominant energy dissipation mechanism. Numerical oscillatory compressibility and shear tests based on the quasistatic poroelasticity equations provide an effective means to compute equivalent viscoelastic moduli for representative rock samples of the heterogeneous media under study. Approaches of this type rely on the existence of a dynamic-equivalent medium, that is, the heterogeneous porous rock is represented by an equivalent homogeneous viscoelastic solid that exhibits an overall response similar to that of the original heterogeneous porous sample. This methodology allows for extracting the equivalent seismic attenuation and phase velocity of the sample, but fails to provide any information with regard to the underlying physical processes. In this work, we present a novel approach based on the quantification of the energy loss taking place in the interior of the considered heterogeneous rock sample. To this end, we first determine the spatial distribution of the energy dissipation in response to the applied oscillatory stresses. Next, we quantify the total dissipated energy as well as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/836673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/836673"><span>Seismic attenuation due to <span class="hlt">wave-induced</span> flow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pride, S.R.; Berryman, J.G.; Harris, J.M.</p> <p>2003-10-09</p> <p>Analytical expressions for three P-<span class="hlt">wave</span> attenuation mechanisms in sedimentary rocks are given a unified theoretical framework. Two of the models concern <span class="hlt">wave-induced</span> flow due to heterogeneity in the elastic moduli at mesoscopic scales (scales greater than grain sizes but smaller than wavelengths). In the first model, the heterogeneity is due to lithological variations (e.g., mixtures of sands and clays) with a single fluid saturating all the pores. In the second model, a single uniform lithology is saturated in mesoscopic ''patches'' by two immiscible fluids (e.g., air and water). In the third model, the heterogeneity is at ''microscopic'' grain scales (broken grain contacts and/or micro-cracks in the grains) and the associated fluid response corresponds to ''squirt flow''. The model of squirt flow derived here reduces to proper limits as any of the fluid bulk modulus, crack porosity, and/or frequency is reduced to zero. It is shown that squirt flow is incapable of explaining the measured level of loss (10{sup -2} < Q{sup -1} < 10{sup -1}) within the seismic band of frequencies (1 to 10{sup 4} Hz); however, either of the two mesoscopic scale models easily produce enough attenuation to explain the field data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21663931','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21663931"><span>Application of SH surface acoustic <span class="hlt">waves</span> for measuring the viscosity of liquids in function of <span class="hlt">pressure</span> and temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kiełczyński, P; Szalewski, M; Balcerzak, A; Rostocki, A J; Tefelski, D B</p> <p>2011-12-01</p> <p>Viscosity measurements were carried out on triolein at <span class="hlt">pressures</span> from atmospheric up to 650 MPa and in the temperature range from 10°C to 40°C using ultrasonic measuring setup. Bleustein-Gulyaev SH surface acoustic <span class="hlt">waves</span> waveguides were used as viscosity sensors. Additionally, <span class="hlt">pressure</span> changes occurring during phase transition have been measured over the same temperature range. Application of ultrasonic SH surface acoustic <span class="hlt">waves</span> in the liquid viscosity measurements at high <span class="hlt">pressure</span> has many advantages. It enables viscosity measurement during phase transitions and in the high-<span class="hlt">pressure</span> range where the classical viscosity measurement methods cannot operate. Measurements of phase transition kinetics and viscosity of liquids at high <span class="hlt">pressures</span> and various temperatures (isotherms) is a novelty. The knowledge of changes in viscosity in function of <span class="hlt">pressure</span> and temperature can help to obtain a deeper insight into thermodynamic properties of liquids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..DFD.HU003D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..DFD.HU003D"><span>An Experimental Investigation of the Free Surface Profiles Generated by a Moving <span class="hlt">Pressure</span> Source: Solitary Capillary-Gravity <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diorio, J. D.; Watkins, N.; Zuech, J.; Duncan, J. H.</p> <p>2008-11-01</p> <p>There have been several recent numerical investigations that have shown the existence of three-dimensional nonlinear solitary surface <span class="hlt">wave</span> patterns that propagate with speeds less than the minimum <span class="hlt">wave</span> phase speed prescribed by linear theory (23 cm/s for clean water). In the present study, <span class="hlt">wave</span> patterns were generated by translating a small-diameter region of high <span class="hlt">pressure</span> across a water surface. The high-<span class="hlt">pressure</span> region was created by forcing air through a small-diameter vertically oriented tube attached to a carriage that propelled it horizontally at speeds near 23 cm/s. The <span class="hlt">wave</span> pattern was measured with a cinematic LIF technique. It was found that a steady solitary <span class="hlt">wave</span> pattern can exist at speeds below the linear-theory minimum phase speed, while for speeds above the minimum, a pattern of gravity-capillary <span class="hlt">waves</span> was produced. The solitary <span class="hlt">wave</span> pattern, which only appeared when the <span class="hlt">pressure</span> forcing was large, dissipated rapidly when the forcing was turned off. The streamwise dimension of the solitary <span class="hlt">wave</span> was much smaller than the transverse dimension.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22490925','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22490925"><span>Effect of anisotropic dust <span class="hlt">pressure</span> and superthermal electrons on propagation and stability of dust acoustic solitary <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bashir, M. F.; Behery, E. E.; El-Taibany, W. F.</p> <p>2015-06-15</p> <p>Employing the reductive perturbation technique, Zakharov–Kuznetzov (ZK) equation is derived for dust acoustic (DA) solitary <span class="hlt">waves</span> in a magnetized plasma which consists the effects of dust anisotropic <span class="hlt">pressure</span>, arbitrary charged dust particles, Boltzmann distributed ions, and Kappa distributed superthermal electrons. The ZK solitary <span class="hlt">wave</span> solution is obtained. Using the small-k expansion method, the stability analysis for DA solitary <span class="hlt">waves</span> is also discussed. The effects of the dust <span class="hlt">pressure</span> anisotropy and the electron superthermality on the basic characteristics of DA <span class="hlt">waves</span> as well as on the three-dimensional instability criterion are highlighted. It is found that the DA solitary <span class="hlt">wave</span> is rarefactive (compressive) for negative (positive) dust. In addition, the growth rate of instability increases rapidly as the superthermal spectral index of electrons increases with either positive or negative dust grains. A brief discussion for possible applications is included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5330526','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5330526"><span>Incommensurate atomic density <span class="hlt">waves</span> in the high-<span class="hlt">pressure</span> IVb phase of barium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Arakcheeva, Alla; Bykov, Maxim; Bykova, Elena; Dubrovinsky, Leonid; Pattison, Phil; Dmitriev, Vladimir; Chapuis, Gervais</p> <p>2017-01-01</p> <p>The host–guest structures of elements at high <span class="hlt">pressure</span> discovered a decade ago still leave many open questions due to the lack of precise models based on full exploitation of the diffraction data. This concerns in particular Ba IV, which is stable in the range 12–45 GPa. With the example of phase Ba IVb, which is characterized here for the first time, a systematic analysis is presented of possible host–guest structure models based on high-quality single-crystal diffraction data obtained with synchrotron radiation at six different <span class="hlt">pressures</span> between 16.5 and 19.6 GPa. It is shown that a new incommensurately modulated (IM) structure model better fits the experimental data. Unlike the composite models which are commonly reported for the Ba IV phases, the IM model reveals a density <span class="hlt">wave</span> and its <span class="hlt">pressure</span>-dependent evolution. The crucial role played by the selected model in the interpretation of structure evolution under <span class="hlt">pressure</span> is discussed. The findings give a new experimental basis for a better understanding of the nature of host–guest structures. PMID:28250954</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28250954','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28250954"><span>Incommensurate atomic density <span class="hlt">waves</span> in the high-<span class="hlt">pressure</span> IVb phase of barium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arakcheeva, Alla; Bykov, Maxim; Bykova, Elena; Dubrovinsky, Leonid; Pattison, Phil; Dmitriev, Vladimir; Chapuis, Gervais</p> <p>2017-03-01</p> <p>The host-guest structures of elements at high <span class="hlt">pressure</span> discovered a decade ago still leave many open questions due to the lack of precise models based on full exploitation of the diffraction data. This concerns in particular Ba IV, which is stable in the range 12-45 GPa. With the example of phase Ba IVb, which is characterized here for the first time, a systematic analysis is presented of possible host-guest structure models based on high-quality single-crystal diffraction data obtained with synchrotron radiation at six different <span class="hlt">pressures</span> between 16.5 and 19.6 GPa. It is shown that a new incommensurately modulated (IM) structure model better fits the experimental data. Unlike the composite models which are commonly reported for the Ba IV phases, the IM model reveals a density <span class="hlt">wave</span> and its <span class="hlt">pressure</span>-dependent evolution. The crucial role played by the selected model in the interpretation of structure evolution under <span class="hlt">pressure</span> is discussed. The findings give a new experimental basis for a better understanding of the nature of host-guest structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17550150','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17550150"><span>Generation of shock-free <span class="hlt">pressure</span> <span class="hlt">waves</span> in shaped resonators by boundary driving.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luo, C; Huang, X Y; Nguyen, N T</p> <p>2007-05-01</p> <p>Investigation of high amplitude <span class="hlt">pressure</span> oscillations generated by boundary driving in shaped resonators has been carried out both theoretically and experimentally. In the theoretical modeling, the acoustic resonance in an axisymmetric resonator is studied by the Galerkin method. The resonator is exponentially expanded and the boundary driving is provided by a piston at one end. The <span class="hlt">pressure</span> <span class="hlt">wave</span> forms, amplitudes, resonance frequencies, and ratio of <span class="hlt">pressures</span> at the two ends of the resonator are calculated for various expansion flare constants and driving strengths. These results are partially compared with those generated by shaking the resonator. They are also verified in the experiment, in which an exponentially expanded resonator is connected to a speaker box functioning as the piston. The experiment is further extended to a horn-shaped resonator with a rectangular cross section. The boundary driving in this case is generated by a circular piezoelectric disk, which forms one sidewall of the resonator cavity. The characteristics of axisymmetric resonators, such as the resonance frequency and amplitude ratio of <span class="hlt">pressures</span> at the two ends, are observed in this low aspect ratio rectangular resonator with the sidewall driving.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27997379','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27997379"><span>The impact of intraocular <span class="hlt">pressure</span> on elastic <span class="hlt">wave</span> velocity estimates in the crystalline lens.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Suhyun; Yoon, Heechul; Larin, Kirill V; Emelianov, Stanislav Y; Aglyamov, Salavat R</p> <p>2016-12-20</p> <p>Intraocular <span class="hlt">pressure</span> (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic <span class="hlt">wave</span> velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic <span class="hlt">wave</span> velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear <span class="hlt">wave</span> elasticity imaging. To generate and then image the elastic <span class="hlt">wave</span> propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic <span class="hlt">wave</span> velocity in the cornea increased from 0.96  ±  0.30 m s(-1) to 6.27  ±  0.75 m s(-1) as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic <span class="hlt">wave</span> velocity in the crystalline lens with the minimum and the maximum speeds of 1.44  ±  0.27 m s(-1) and 2.03  ±  0.46 m s(-1), respectively. This study shows that ultrasound shear <span class="hlt">wave</span> elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PMB....62N..45P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PMB....62N..45P"><span>The impact of intraocular <span class="hlt">pressure</span> on elastic <span class="hlt">wave</span> velocity estimates in the crystalline lens</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Suhyun; Yoon, Heechul; Larin, Kirill V.; Emelianov, Stanislav Y.; Aglyamov, Salavat R.</p> <p>2017-02-01</p> <p>Intraocular <span class="hlt">pressure</span> (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic <span class="hlt">wave</span> velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic <span class="hlt">wave</span> velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear <span class="hlt">wave</span> elasticity imaging. To generate and then image the elastic <span class="hlt">wave</span> propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic <span class="hlt">wave</span> velocity in the cornea increased from 0.96  ±  0.30 m s-1 to 6.27  ±  0.75 m s-1 as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic <span class="hlt">wave</span> velocity in the crystalline lens with the minimum and the maximum speeds of 1.44  ±  0.27 m s-1 and 2.03  ±  0.46 m s-1, respectively. This study shows that ultrasound shear <span class="hlt">wave</span> elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22257006','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22257006"><span>Experimental determination of radiated internal <span class="hlt">wave</span> power without <span class="hlt">pressure</span> field data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lee, Frank M.; Morrison, P. J.; Paoletti, M. S.; Swinney, Harry L.</p> <p>2014-04-15</p> <p>We present a method to determine, using only velocity field data, the time-averaged energy flux (J) and total radiated power P for two-dimensional internal gravity <span class="hlt">waves</span>. Both (J) and P are determined from expressions involving only a scalar function, the stream function ψ. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal <span class="hlt">wave</span> power given by the stream function method agree to within 0.5% with results obtained using <span class="hlt">pressure</span> and velocity data from the numerical simulation. The results for the radiated power computed from the stream function agree well with power computed from the velocity and <span class="hlt">pressure</span> if the starting point for the stream function computation is on a solid boundary, but if a boundary point is not available, care must be taken to choose an appropriate starting point. We also test the stream function method by applying it to laboratory data for tidal flow past a knife edge, and the results are found to agree with the direct numerical simulation. The supplementary material includes a Matlab code with a graphical user interface that can be used to compute the energy flux and power from two-dimensional velocity field data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23888287','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23888287"><span>Vibration and <span class="hlt">pressure</span> <span class="hlt">wave</span> therapy for calf strains: a proposed treatment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saxena, Amol; St Louis, Marie; Fournier, Magali</p> <p>2013-04-01</p> <p>Calf (lower leg) strains have a variety of treatment regimens with variable outcomes and return to activity (RTA) time frames. These injuries involve disruption of portions or the entire gastrocnemius-soleus myo-tendinous complex. Conservative treatment initially consists of rest, ice, compression, elevation (RICE). Immediately following calf injury, patients can utilize cryotherapy, massage, passive range of motion, and progressive exercise. In general, Grade I through Grade III calf strains can take up to 6 weeks before the athlete can return to training. It can also involve the loss of more than 50% of muscle integrity. Recently, vibration therapy and radial <span class="hlt">pressure</span> <span class="hlt">waves</span> have been utilized to treat muscular strains and other myo-tendinous injuries that involve trigger points. Studies have suggested vibration therapy with rehabilitation can increase muscle strength and flexibility in patients. Segmental vibration therapy (SVT) is treatment to a more focal area. Vibration therapy (VT) is applied directly to the area of injury. VT is a mechanical stimulus that is thought to stimulate the sensory receptors, as well as decrease inflammatory cells and receptors. Therefore, VT could be a valuable tool in treating athlete effectively and decreasing their recovery time. The purpose of this paper is to give the reader baseline knowledge of VT and propose a treatment protocol for calf strains using this technology along with radial <span class="hlt">pressure</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhDT........39P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT........39P"><span>Spontaneous thermal <span class="hlt">waves</span> and exponential spectra associated with a filamentary <span class="hlt">pressure</span> structure in a magnetized plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pace, David Carl</p> <p></p> <p>An experimental study of plasma turbulence and transport is performed in the fundamental geometry of a narrow <span class="hlt">pressure</span> filament in a magnetized plasma. An electron beam is used to heat a cold background plasma in a linear device, the Large Plasma Device (LAPD-U) [W. Gekelman et al. Rev. Sci. Instrum. 62, 2875 (1991)] operated by the Basic Plasma Science Facility at the University of California, Los Angeles. This results in the generation of a filamentary structure 1000 cm in length and 1 cm in diameter) exhibiting a controllable radial temperature gradient embedded in a large plasma. The filament serves as a resonance cavity for a thermal (diffusive) <span class="hlt">wave</span> manifested by large amplitude, coherent oscillations in electron temperature. Properties of this <span class="hlt">wave</span> are used to determine the electron collision time of the plasma and suggest that a diagnostic method for studying plasma transport can be designed in a similar manner. For short times and low heating powers the filament conducts away thermal energy through particle collisions, consistent with classical theory. Experiments performed with longer heating times or greater injected power feature a transition from the classical transport regime to a regime of enhanced transport levels. During the anomalous transport regime, fluctuations exhibit an exponential power spectrum for frequencies below the ion cyclotron frequency. The exponential feature has been traced to the presence of solitary pulses having a Lorentzian temporal signature. These pulses arise from nonlinear interactions of drift-Alfven <span class="hlt">waves</span> driven by the <span class="hlt">pressure</span> gradients. The temporal width of the pulses is measured to be a fraction of a period of the drift-Alfven <span class="hlt">waves</span>. A second experiment involves a macroscopic (3.5 cm gradient length) limiter-edge geometry in which a density gradient is established by inserting a metallic plate at the edge of the nominal plasma column of the LAPD-U. In both experiments the width of the pulses is narrowly distributed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26302781','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26302781"><span><span class="hlt">Wave</span> trains <span class="hlt">induced</span> by circularly polarized electric fields in cardiac tissues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Feng, Xia; Gao, Xiang; Tang, Juan-Mei; Pan, Jun-Ting; Zhang, Hong</p> <p>2015-08-25</p> <p>Clinically, cardiac fibrillation caused by spiral and turbulent <span class="hlt">waves</span> can be terminated by globally resetting electric activity in cardiac tissues with a single high-voltage electric shock, but it is usually associated with severe side effects. Presently, a promising alternative uses <span class="hlt">wave</span> emission from heterogeneities <span class="hlt">induced</span> by a sequence of low-voltage uniform electric field pulses. Nevertheless, this method can only emit <span class="hlt">waves</span> locally near obstacles in turbulent <span class="hlt">waves</span> and thereby requires multiple obstacles to globally synchronize myocardium and thus to terminate fibrillation. Here we propose a new approach using <span class="hlt">wave</span> emission from heterogeneities <span class="hlt">induced</span> by a low-voltage circularly polarized electric field (i.e., a rotating uniform electric field). We find that, this approach can generate circular <span class="hlt">wave</span> trains near obstacles and they propagate outwardly. We study the characteristics of such circular <span class="hlt">wave</span> trains and further find that, the higher-frequency circular <span class="hlt">wave</span> trains can effectively suppress spiral turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..DFD.EB001V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..DFD.EB001V"><span>Nonlinear <span class="hlt">wave</span> evolution in <span class="hlt">pressure</span>-driven stratified flow of Newtonian and Herschel-Bulkley fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valluri, Prashant; Sahu, Kirti; Ding, Hang; Spelt, Peter; Matar, Omar; Lawrence, Chris</p> <p>2007-11-01</p> <p><span class="hlt">Pressure</span>-driven stratified channel flow of a Newtonian fluid flowing over a Herschel-Bulkley (HB) fluid is considered. The effects of yield stress and shear-thinning rheology on the nonlinear <span class="hlt">wave</span> evolution are studied using numerical simulations; the HB rheology is regularized at low shear rates using a bi-viscosity formulation. Two different numerical methods were used to carry out the computations: a level-set method (based on that by Spelt, J. Comput. Phys. 2005) and a diffuse-interface method (based on that by Ding et al., J. Comput. Phys., in press). The simulations, which account for fluid inertia, surface tension and gravity are validated against linear theory predictions at early times. The results at later times show the spatio-temporal evolution into the nonlinear regime wherein <span class="hlt">waves</span> are strongly deformed, leading to the onset of drop entrainment. It is shown that the apparent viscosity in the region of the HB fluid directly involved in the onset of entrainment is almost constant; unyielded regions are confined to <span class="hlt">wave</span> troughs at late stages of the nonlinear evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRB..121.8175S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRB..121.8175S"><span>Synthesizing ocean bottom <span class="hlt">pressure</span> records including seismic <span class="hlt">wave</span> and tsunami contributions: Toward realistic tests of monitoring systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saito, Tatsuhiko; Tsushima, Hiroaki</p> <p>2016-11-01</p> <p>The present study proposes a method for synthesizing the ocean bottom <span class="hlt">pressure</span> records during a tsunamigenic earthquake. First, a linear seismic <span class="hlt">wave</span> simulation is conducted with a kinematic earthquake fault model as a source. Then, a nonlinear tsunami simulation is conducted using the sea bottom movement calculated in the seismic <span class="hlt">wave</span> simulation. By using these simulation results, this method can provide realistic ocean bottom <span class="hlt">pressure</span> change data, including both seismic and tsunami contributions. A simple theoretical consideration indicates that the dynamic <span class="hlt">pressure</span> change caused by the sea bottom acceleration can contribute significantly until the duration of 90 s for a depth of 4000 m in the ocean. The performance of a tsunami monitoring system was investigated using the synthesized ocean bottom <span class="hlt">pressure</span> records. It indicates that the system based on the hydrostatic approximation could not measure the actual tsunami height when the time does not elapse enough. The dynamic <span class="hlt">pressure</span> change and the permanent sea bottom deformation inside the source region break the condition of a simple hydrostatic approximation. A tsunami source estimation method of tFISH is also examined. Even though the synthesized records contain a large dynamic <span class="hlt">pressure</span> change, which is not considered in the algorithm, tFISH showed a satisfactory performance 5 min after the earthquake occurrence. The <span class="hlt">pressure</span> records synthesized in this study, including both seismic <span class="hlt">wave</span> and tsunami contributions, are more practical for evaluating the performance of our monitoring ability, whereas most tsunami monitoring tests neglect the seismic <span class="hlt">wave</span> contribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhaTr..88...30V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhaTr..88...30V"><span><span class="hlt">Pressure-induced</span> structural phase transition and elastic properties of rare earth Pr chalcogenides and pnictides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varshney, Dinesh; Shriya, Swarna; Varshney, Meenu; Khenata, R.</p> <p>2015-01-01</p> <p><span class="hlt">Pressure-induced</span> structural aspects and elastic properties of NaCl-type (B1) to CsCl-type (B2) structure in praseodymium chalcogenides and pnictides are presented. Ground-state properties are numerically computed by considering long-range Coulomb interactions, Hafemeister and Flygare type short-range overlap repulsion, and van der Waals interaction in the interionic potential. From the elastic constants, Poisson's ratio ν, the ratio RG/B of G (shear modulus) over B (bulk modulus), anisotropy parameter, shear and Young's moduli, Lamé's constant, Kleinman parameter, elastic <span class="hlt">wave</span> velocity and thermodynamical property such as Debye temperature are calculated. Poisson's ratio ν and the ratio RG/B indicate that PrX and PrY are brittle in B1 phase and ductile in B2 phase. To our knowledge, this is the first quantitative theoretical prediction of the ductile (brittle) nature of praseodymium chalcogenides and pnictides and still awaits experimental confirmation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20853011','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20853011"><span>Measurement of radiation-<span class="hlt">pressure-induced</span> optomechanical dynamics in a suspended Fabry-Perot cavity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Corbitt, Thomas; Ottaway, David; Innerhofer, Edith; Pelc, Jason; Mavalvala, Nergis</p> <p>2006-08-15</p> <p>We report on experimental observation of radiation-<span class="hlt">pressure</span> <span class="hlt">induced</span> effects in a high-power optical cavity. These effects play an important role in next-generation gravitational <span class="hlt">wave</span> detectors, as well as in quantum nondemolition interferometers. We measure the properties of an optical spring, created by coupling of an intense laser field to the pendulum mode of a suspended mirror, and also the parametric instability (PI) that arises from the coupling between acoustic modes of the cavity mirrors and the cavity optical mode. We measure an unprecedented optical rigidity of K=(3.08{+-}0.09)x10{sup 4} N/m, corresponding to an optical rigidity that is 6000 times stiffer than the mechanical stiffness, and PI strength R{approx_equal}3. We measure the unstable nature of the optical spring resonance, and demonstrate that the PI can be stabilized by feedback to the frequency of the laser source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1299643','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1299643"><span>Control by osmotic <span class="hlt">pressure</span> of voltage-<span class="hlt">induced</span> permeabilization and gene transfer in mammalian cells.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Golzio, M; Mora, M P; Raynaud, C; Delteil, C; Teissié, J; Rols, M P</p> <p>1998-01-01</p> <p>Cells can be transiently permeabilized by a membrane potential difference increase <span class="hlt">induced</span> by the application of high electric pulses. This was shown to be under the control of the pulsing buffer osmotic <span class="hlt">pressure</span>, when short pulses were applied. In this paper, the effects of buffer osmotic <span class="hlt">pressure</span> during electric treatment and during the following 10 min were investigated in Chinese hamster ovary cells subjected to long (ms) square <span class="hlt">wave</span> pulses, a condition needed to mediate gene transfer. No effect on cell permeabilization for a small molecule such as propidium iodide was observed. The use of a hypoosmolar buffer during pulsation allows more efficient loading of cells with beta-galactosidase, a tetrameric protein, but no effect of the postpulse buffer osmolarity was observed. The resulting expression of plasmid coding for beta-galactosidase was strongly controlled by buffer osmolarity during as well as after the pulse. The results, tentatively explained in terms of the effect of osmotic <span class="hlt">pressure</span> on cell swelling, membrane organization, and interaction between molecules and membrane, support the existence of key steps in plasmid-membrane interaction in the mechanism of cell electrically mediated gene transfer. PMID:9635756</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPUP2052J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPUP2052J"><span>Flow <span class="hlt">induced</span> dust acoustic shock <span class="hlt">waves</span> in a complex plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jaiswal, Surabhi; Bandyopadhyay, Pintu; Sen, Abhijit</p> <p>2015-11-01</p> <p>We report on experimental observations of particle flow <span class="hlt">induced</span> large amplitude shock <span class="hlt">waves</span> in a dusty plasma. These dust acoustic shocks (DAS) are observed for strongly supersonic flows and have been studied in a U-shaped Dusty Plasma Experimental (DPEx) device for charged kaolin dust in a background of Argon plasma. The strong flow of the dust fluid is <span class="hlt">induced</span> by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change of the dust density near the potential hill is used to trigger the onset of high velocity dust acoustic shocks. The dynamics of the shocks are captured by fast video pictures of the structures that are illuminated by a laser sheet beam. The physical characteristics of the shock are delineated from a parametric scan of their dynamical properties over a range of plasma parameters and flow speeds. Details of these observations and a physical explanation based on model calculations will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPSJ...85d4703S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPSJ...85d4703S"><span>Charge Order <span class="hlt">Induced</span> in an Orbital Density-<span class="hlt">Wave</span> State</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, Dheeraj Kumar; Takimoto, Tetsuya</p> <p>2016-04-01</p> <p>Motivated by recent angle resolved photoemission measurements [D. V. Evtushinsky et al., Phys. Rev. Lett. 105, 147201 (2010)] and evidence of the density-<span class="hlt">wave</span> state for the charge and orbital ordering [J. García et al., Phys. Rev. Lett. 109, 107202 (2012)] in La0.5Sr1.5MnO4, the issue of charge and orbital ordering in a two-orbital tight-binding model for layered manganite near half doping is revisited. We find that the charge order with the ordering wavevector 2{Q} = (π ,π ) is <span class="hlt">induced</span> by the orbital order of d-/d+-type having B1g representation with a different ordering wavevector Q, where the orbital order as the primary order results from the strong Fermi-surface nesting. It is shown that the <span class="hlt">induced</span> charge order parameter develops according to TCO - T by decreasing the temperature below the orbital ordering temperature TCO, in addition to the usual mean-field behavior of the orbital order parameter. Moreover, the same orbital order is found to stabilize the CE-type spin arrangement observed experimentally below TCE < TCO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..GECLW1060S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..GECLW1060S"><span>PIC-DSMC analysis on interaction of a laser <span class="hlt">induced</span> discharge and shock <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimamura, Kohei</p> <p>2015-09-01</p> <p>Laser <span class="hlt">induced</span> discharge and the shock <span class="hlt">wave</span> have attracted great interest for use in the electrical engineering. When the high intensity laser (10 GW >) is focused in the atmosphere, the breakdown occurs and the discharge <span class="hlt">wave</span> propagates toward to the laser irradiation. The shock <span class="hlt">wave</span> is generated around the discharge <span class="hlt">wave</span>, which is called as the laser supported detonation <span class="hlt">wave</span>. After breakdown occurred, the initial electron of the avalanche ionization is produced by the photoionization due to the plasma radiation. It is well recognized that the radiation of the laser plasma affects the propagation mechanism of the laser <span class="hlt">induced</span> discharge <span class="hlt">wave</span> after the initiation of the breakdown. However, it is difficult to observe the interaction between the plasma radiation and the electron avalanche in the ionization-<span class="hlt">wave</span> front in experimentally except in the high intensity laser. In the numerical calculation of the laser-<span class="hlt">induced</span> discharge, the fluid dynamics based on the Navier-Stokes equation have been widely used. However, it is difficult to investigate the avalanche ionization at the <span class="hlt">wave</span> front using the fluid dynamics simulation. To investigate the interaction of the ionization-<span class="hlt">wave</span> front and the shock <span class="hlt">wave</span>, it is appropriate to utilize the PIC-DSMC method. The present study showed the propagation of the ionization front of the discharge <span class="hlt">wave</span> and the shock <span class="hlt">wave</span> using the particle simulation. This work was supported by Kato Foundation for Promotion of Science and Japan Power Academy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.109f1108X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.109f1108X"><span>Radiation <span class="hlt">pressure</span> <span class="hlt">induced</span> difference-sideband generation beyond linearized description</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Hao; Fan, Yu-Wan; Yang, Xiaoxue; Wu, Ying</p> <p>2016-08-01</p> <p>We investigate radiation-<span class="hlt">pressure</span> <span class="hlt">induced</span> generation of the frequency components at the difference-sideband in an optomechanical system, which beyond the conventional linearized description of optomechanical interactions between cavity fields and the mechanical oscillation. We analytically calculate amplitudes of these signals, and identify a simple square-root law for both the upper and lower difference-sideband generation which can describe the dependence of the intensities of these signals on the pump power. Further calculation shows that difference-sideband generation can be greatly enhanced via achieving the matching conditions. The effect of difference-sideband generation, which may have potential application for manipulation of light, is especially suited for on-chip optomechanical devices, where nonlinear optomechanical interaction in the weak coupling regime is within current experimental reach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020039729&hterms=Hemoglobin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DHemoglobin','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020039729&hterms=Hemoglobin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DHemoglobin"><span>Cerebrovascular Responses During Lower Body Negative <span class="hlt">Pressure-Induced</span> Presyncope</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kuriyama, Kana; Watenpaugh, D. E.; Hargens, Alan R.; Ueno, T.; Ballard, R. E.; Fortney, S. M.</p> <p>1996-01-01</p> <p>Reduced orthostatic tolerance is commonly observed after space flight, occasionally causing presyncopal conditions. Although the cerebrovascular system may play an important role in presyncope, there have been few reports concerning cerebral hemodynamics during presyncope. The purpose of this study was to investigate cerebrovascular responses during presyncope <span class="hlt">induced</span> by lower body negative <span class="hlt">pressure</span> (LBNP). Seven healthy male volunteers were exposed to LBNP in steps of -10 mmHg every 3 min until presyncopal symptoms were detected. Blood <span class="hlt">pressure</span> (BP) and heart rate (HR) were measured with a finger cuff. Cerebral tissue oxy- and deoxy- hemoglobin (Hb) concentrations were estimated using near infrared spectroscopy (NIRS). Cerebral blood flow (CBF) velocity at the middle cerebral artery was measured with Transcranial Doppler Sonography (TCD). We focused on the data during the 2 min before endpoint. BP marked a gradual decrease (91 to 86 mmHg from 2 min to 30 sec before endpoint), which was accelerated along with HR decrease during the final 30 sec (86 to 71 mmHg). Cerebral oxy-Hb concentration decreases as presyncope is approached while total-Hb concentration remains fairly constant. TCD reveals a decrease in the CBF velocity. The TCD and NIRS results suggest that CBF decreases along with the BP decrease. Cerebrovascular responses during presyncope are closely related to cardiovascular responses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...120w5304V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...120w5304V"><span>A model for <span class="hlt">pressurized</span> hydrogen <span class="hlt">induced</span> thin film blisters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van den Bos, R. A. J. M.; Reshetniak, V.; Lee, C. J.; Benschop, J.; Bijkerk, F.</p> <p>2016-12-01</p> <p>We introduce a model for hydrogen <span class="hlt">induced</span> blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal <span class="hlt">pressure</span>, and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model, the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal <span class="hlt">pressures</span> in the range of 175-280 MPa. Based on the model, a minimum ion dose for the onset of blister formation was calculated to be d = 4.2 × 1018 ions/cm2. From the flux balance equations, the diffusion constant for the Mo/Si blister cap was estimated to be DH2=(10 ±1 )×10-18 cm2/s .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760006623','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760006623"><span>Theoretical monochromatic-<span class="hlt">wave-induced</span> currents in intermediate water with viscosity and nonzero mass transport</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Talay, T. A.</p> <p>1975-01-01</p> <p><span class="hlt">Wave-induced</span> mass-transport current theories with both zero and nonzero net mass (or volume) transport of the water column are reviewed. A relationship based on the Longuet-Higgens theory is derived for <span class="hlt">wave-induced</span>, nonzero mass-transport currents in intermediate water depths for a viscous fluid. The relationship is in a form useful for experimental applications; therefore, some design criteria for experimental <span class="hlt">wave</span>-tank tests are also presented. Sample parametric cases for typical <span class="hlt">wave</span>-tank conditions and a typical ocean swell were assessed by using the relation in conjunction with an equation developed by Unluata and Mei for the maximum <span class="hlt">wave-induced</span> volume transport. Calculations indicate that substantial changes in the <span class="hlt">wave-induced</span> mass-transport current profiles may exist dependent upon the assumed net volume transport. A maximum volume transport, corresponding to an infinite channel or idealized ocean condition, produces the largest <span class="hlt">wave-induced</span> mass-transport currents. These calculations suggest that <span class="hlt">wave-induced</span> mass-transport currents may have considerable effects on pollution and suspended-sediments transport as well as buoy drift, the surface and midlayer water-column currents caused by <span class="hlt">waves</span> increasing with increasing net volume transports. Some of these effects are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008QuEle..38.1155G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008QuEle..38.1155G"><span>LIGHT <span class="hlt">PRESSURE</span>: Theoretical study of the light <span class="hlt">pressure</span> force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guzatov, D. V.; Gaida, L. S.; Afanas'ev, Anatolii A.</p> <p>2008-12-01</p> <p>The light <span class="hlt">pressure</span> force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic <span class="hlt">waves</span> is studied in detail for different particle radii and angles of incidence of <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B22B..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B22B..05K"><span>The relationship between gas hydrate saturation and P-<span class="hlt">wave</span> velocity of <span class="hlt">pressure</span> cores obtained in the Eastern Nankai Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Konno, Y.; Yoneda, J.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Fujii, T.; Nagao, J.</p> <p>2014-12-01</p> <p>P-<span class="hlt">wave</span> velocity is an important parameter to estimate gas hydrate saturation in sediments. In this study, the relationship between gas hydrate saturation and P-<span class="hlt">wave</span> velocity have been analyzed using natural hydrate-bearing-sediments obtained in the Eastern Nankai Trough, Japan. The sediment samples were collected by the Hybrid <span class="hlt">Pressure</span> Coring System developed by Japan Agency for Marine-Earth Science and Technology during June-July 2012, aboard the deep sea drilling vessel CHIKYU. P-<span class="hlt">wave</span> velocity was measured on board by the <span class="hlt">Pressure</span> Core Analysis and Transfer System developed by Geotek Ltd. The samples were maintained at a near in-situ <span class="hlt">pressure</span> condition during coring and measurement. After the measurement, the samples were stored core storage chambers and transported to MHRC under <span class="hlt">pressure</span>. The samples were manipulated and cut by the <span class="hlt">Pressure</span>-core Non-destructive Analysis Tools or PNATs developed by MHRC. The cutting sections were determined on the basis of P-<span class="hlt">wave</span> velocity and visual observations through an acrylic window equipped in the PNATs. The cut samples were depressurized to measure gas volume for saturation calculations. It was found that P-<span class="hlt">wave</span> velocity correlates well with hydrate saturation and can be reproduced by the hydrate frame component model. Using <span class="hlt">pressure</span> cores and <span class="hlt">pressure</span> core analysis technology, nondestructive and near in-situ correlation between gas hydrate saturation and P-<span class="hlt">wave</span> velocity can be obtained. This study was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900011479','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900011479"><span>Experimental feasibility of investigating acoustic <span class="hlt">waves</span> in Couette flow with entropy and <span class="hlt">pressure</span> gradients</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parrott, Tony L.; Zorumski, William E.; Rawls, John W., Jr.</p> <p>1990-01-01</p> <p>The feasibility is discussed for an experimental program for studying the behavior of acoustic <span class="hlt">wave</span> propagation in the presence of strong gradients of <span class="hlt">pressure</span>, temperature, and flow. Theory suggests that gradients effects can be experimentally observed as resonant frequency shifts and mode shape changes in a waveguide. A convenient experimental geometry for such experiments is the annular region between two co-rotating cylinders. Radial temperature gradients in a spinning annulus can be generated by differentially heating the two cylinders via electromagnetic induction. Radial <span class="hlt">pressure</span> gradients can be controlled by varying the cylinder spin rates. Present technology appears adequate to construct an apparatus to allow independent control of temperature and <span class="hlt">pressure</span> gradients. A complicating feature of a more advanced experiment, involving flow gradients, is the requirement for independently controlled cylinder spin rates. Also, the boundary condition at annulus terminations must be such that flow gradients are minimally disturbed. The design and construction of an advanced apparatus to include flow gradients will require additional technology development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5053542','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5053542"><span>Intraocular <span class="hlt">Pressure</span> <span class="hlt">Induced</span> Retinal Changes Identified Using Synchrotron Infrared Microscopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chow, Seong Hoong; Wang, Jiang-Hui; He, Zheng; Nguyen, Christine; Lin, Tsung-Wu; Bui, Bang V.</p> <p>2016-01-01</p> <p>Infrared (IR) spectroscopy has been used to quantify chemical and structural characteristics of a wide range of materials including biological tissues. In this study, we examined spatial changes in the chemical characteristics of rat retina in response to intraocular <span class="hlt">pressure</span> (IOP) elevation using synchrotron infrared microscopy (SIRM), a non-destructive imaging approach. IOP elevation was <span class="hlt">induced</span> by placing a suture around the eye of anaesthetised rats. Retinal sections were collected onto transparent CaF2 slides 10 days following IOP elevation. Using combined SIRM spectra and chemical mapping approaches it was possible to quantify IOP <span class="hlt">induced</span> changes in protein conformation and chemical distribution in various layers of the rat retina. We showed that 10 days following IOP elevation there was an increase in lipid and protein levels in the inner nuclear layer (INL) and ganglion cell layer (GCL). IOP elevation also resulted in an increase in nucleic acids in the INL. Analysis of SIRM spectra revealed a shift in amide peaks to lower vibrational frequencies with a more prominent second shoulder, which is consistent with the presence of cell death in specific layers of the retina. These changes were more substantial in the INL and GCL layers compared with those occurring in the outer nuclear layer. These outcomes demonstrate the utility of SIRM to quantify the effect of IOP elevation on specific layers of the retina. Thus SIRM may be a useful tool for the study of localised tissue changes in glaucoma and other eye diseases. PMID:27711151</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22680599','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22680599"><span>Peregrine rogue <span class="hlt">waves</span> <span class="hlt">induced</span> by the interaction between a continuous <span class="hlt">wave</span> and a soliton.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Guangye; Li, Lu; Jia, Suotang</p> <p>2012-04-01</p> <p>Based on the soliton solution on a continuous <span class="hlt">wave</span> background for an integrable Hirota equation, the reduction mechanism and the characteristics of the Peregrine rogue <span class="hlt">wave</span> in the propagation of femtosecond pulses of optical fiber are discussed. The results show that there exist two processes of the formation of the Peregrine rogue <span class="hlt">wave</span>: one is the localized process of the continuous <span class="hlt">wave</span> background, and the other is the reduction process of the periodization of the bright soliton. The characteristics of the Peregrine rogue <span class="hlt">wave</span> are exhibited by strong temporal and spatial localization. Also, various initial excitations of the Peregrine rogue <span class="hlt">wave</span> are performed and the results show that the Peregrine rogue <span class="hlt">wave</span> can be excited by a small localized (single peak) perturbation pulse of the continuous <span class="hlt">wave</span> background, even for the nonintegrable case. The numerical simulations show that the Peregrine rogue <span class="hlt">wave</span> is unstable. Finally, through a realistic example, the influence of the self-frequency shift to the dynamics of the Peregrine rogue <span class="hlt">wave</span> is discussed. The results show that in the absence of the self-frequency shift, the Peregrine rogue <span class="hlt">wave</span> can split into several subpulses; however, when the self-frequency shift is considered, the Peregrine rogue <span class="hlt">wave</span> no longer splits and exhibits mainly a peak changing and an increasing evolution property of the field amplitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4713536','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4713536"><span>Cinnamaldehyde attenuates <span class="hlt">pressure</span> overload-<span class="hlt">induced</span> cardiac hypertrophy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Liu; Wu, Qing-Qing; Liu, Yuan; Hu, Zhe-Fu; Bian, Zhou-Yan; Tang, Qi-Zhu</p> <p>2015-01-01</p> <p>Background: Cinnamaldehyde is a major bioactive compound isolated from the leaves of Cinnamomum osmophloeum. Studies have demonstrated that cinnamaldehyde has anti-bacterial activity, anti-tumorigenic effect, immunomodulatory effect, anti-fungal activity, anti-oxidative effect, anti-inflammatory and anti-diabetic effect. It has been proven that Cinnamaldehyde improves ischemia/reperfusion injury of pre-treatment. However, little is known about the effect of cinnamaldehyde on cardiac hypertrophy. Methods: Aortic banding (AB) was performed to <span class="hlt">induce</span> cardiac hypertrophy in mice. Cinnamaldehyde premixed in diets was administered to mice after one week of AB. Echocardiography and catheter-based measurements of hemodynamic parameters were performed at week 7 after starting cinnamaldehyde (8 weeks after surgery). The extent of cardiac hypertrophy was evaluated by pathological and molecular analyses of heart samples. Meanwhile, the effect of cinnamaldehyde on myocardial hypertrophy, fibrosis and dysfunction <span class="hlt">induced</span> by AB was investigated, as was assessed by heart weigh/body weight, lung weight/body weight, heart weight/tibia length, echocardiographic and haemodynamic parameters, histological analysis, and gene expression of hypertrophic and fibrotic markers. Results: Our data demonstrated that echocardiography and catheter-based measurements of hemodynamic parameters at week 7 revealed the amelioration of systolic and diastolic abnormalities by cinnamaldehyde intervention. Cardiac fibrosis in AB mice was also decreased by cinnamaldehyde. Moreover, the beneficial effect of cinnamaldehyde was associated with the normalization in gene expression of hypertrophic and fibrotic markers. Further studies showed that <span class="hlt">pressure</span> overload significantly <span class="hlt">induced</span> the activation of extracellular signal-regulated kinase (ERK) signaling pathway, which was blocked by cinnamaldehyde. Conclusion: Cinnamaldehyde may be able to retard the progression of cardiac hypertrophy and fibrosis, probably</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18079263','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18079263"><span><span class="hlt">Wave</span> reflection and central aortic <span class="hlt">pressure</span> are increased in response to static and dynamic muscle contraction at comparable workloads.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Edwards, David G; Mastin, Corey R; Kenefick, Robert W</p> <p>2008-02-01</p> <p>We determined the effects of static and dynamic muscle contraction at equivalent workloads on central aortic <span class="hlt">pressure</span> and <span class="hlt">wave</span> reflection. At random, 14 healthy men and women (23 +/- 5 yr of age) performed a static handgrip forearm contraction [90 s at 30% of maximal voluntary contraction (MVC)], dynamic handgrip contractions (1 contraction/s for 180 s at 30% MVC), and a control trial. During static and dynamic trials, tension-time index was controlled by holding peak tension constant. Measurements of brachial artery blood <span class="hlt">pressure</span> and the synthesis of a central aortic <span class="hlt">pressure</span> waveform (by radial artery applanation tonometry and generalized transfer function) were conducted at baseline, during each trial, and during 1 min of postexercise ischemia (PEI). Aortic augmentation index (AI), an index of <span class="hlt">wave</span> reflection, was calculated from the aortic <span class="hlt">pressure</span> waveform. AI increased during both static and dynamic trials (static, 5.2 +/- 3.1 to 11.8 +/- 3.4%; dynamic, 5.8 +/- 3.0 to 13.3 +/- 3.4%; P < 0.05) and further increased during PEI (static, 18.5 +/- 3.1%; dynamic, 18.6 +/- 2.9%; P < 0.05). Peripheral and central systolic and diastolic <span class="hlt">pressures</span> increased (P < 0.05) during both static and dynamic trials and remained elevated during PEI. AI and <span class="hlt">pressure</span> responses did not differ between static and dynamic trials. Peripheral and central <span class="hlt">pressures</span> increased similarly during static and dynamic contraction; however, the rise in central systolic <span class="hlt">pressure</span> during both conditions was augmented by increased <span class="hlt">wave</span> reflection. The present data suggest that <span class="hlt">wave</span> reflection is an important determinant of the central blood <span class="hlt">pressure</span> response during forearm muscle contractions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SuMi...98..423G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SuMi...98..423G"><span>Effect of hydrostatic <span class="hlt">pressure</span> and magnetic field on electromagnetically <span class="hlt">induced</span> transparency based nonlinear frequency conversion in quantum ring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gumber, Sukirti; Gambhir, Monica; Jha, Pradip Kumar; Mohan, Man</p> <p>2016-10-01</p> <p>We study the combined effect of hydrostatic <span class="hlt">pressure</span> and magnetic field on electromagnetically <span class="hlt">induced</span> transparency in quantum ring. The high flexibility in size and shape of ring makes it possible to fabricate a nearly perfect two-dimensional quantum structure. We also explore the dependence of frequency conversion, measured in terms of third order nonlinear susceptibility χ(3) , on coupling field, hydrostatic <span class="hlt">pressure</span> and magnetic field. Although, a dip in χ(3) is observed with the introduction of strong coupling field, it renders the ring structure transparent to generated <span class="hlt">wave</span> thus effectively enhancing the output of nonlinear frequency conversion process. At a fixed coupling strength, the output can be further enhanced by increasing the magnetic field while it shows an inverse relationship with <span class="hlt">pressure</span>. These parameters, being externally controlled, provide an easy handle to control the output of quantum ring which can be used as frequency converter in communication networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.C2002C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.C2002C"><span>Shock <span class="hlt">wave</span> equation of state experiments at multi-TPa <span class="hlt">pressures</span> on NIF</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Celliers, P. M.; Fratanduono, D. E.; Peterson, J. L.; Meezan, N. B.; MacKinnon, A. J.; Braun, D. G.; Millot, M.; Fry, J.; Boehm, K. J.; Collins, G. W.; Nikroo, A.; Fitzsimmons, P.</p> <p>2015-06-01</p> <p>The National Ignition Facility provides an unprecedented capability to generate steady, planar, ultra-high <span class="hlt">pressure</span> shock <span class="hlt">waves</span> (around 10 TPa) in solid samples. Building on successful laser shock equation of state experiments performed on a variety of other laser facilities, we have designed and fielded experiments to perform impedance match experiments on samples of C, Be, quartz and CH, in the range of 3 to 7 TPa. The experiments use a line-imaging VISAR as the primary diagnostic to measure the shock velocity in an Al reference standard and in an array of the four samples. Initial tests with the line-imaging VISAR show that the NIF is capable of driving shocks that are steady for several ns, with smooth planar breakout patterns over a 2 mm diameter spot. Initial results will be discussed. Prepared by LLNL under Contract DE-AC52-07NA27344.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22493860','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22493860"><span>The transfer of atmospheric-<span class="hlt">pressure</span> ionization <span class="hlt">waves</span> via a metal wire</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Xia, Yang; Liu, Dongping; Wang, Wenchun; Peng, Yifeng; Niu, Jinhai; Bi, Zhenhua; Ji, Longfei; Song, Ying; Wang, Xueyang; Qi, Zhihua</p> <p>2016-01-15</p> <p>Our study has shown that the atmospheric-<span class="hlt">pressure</span> He ionization <span class="hlt">waves</span> (IWs) may be transferred from one dielectric tube (tube 1) to the other one (tube 2) via a floating metal wire. The propagation of IWs along the two tubes is not affected by the diameter of a floating metal wire, however, their propagation is strongly dependent on the length of a floating metal wire. The propagation of one IW along the tube 1 may result in the second IW propagating reversely inside the tube in vicinity of a floating metal wire, which keeps from their further propagation through the tube 1. After they merge together as one conduction channel inside the tube 1, the transferred plasma bullet starts to propagate along the tube 2. The propagation of transferred plasma bullets along the tube 2 is mainly determined by the capacitance and inductance effects, and their velocity and density can be controlled by the length of a floating metal wire.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3617730','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3617730"><span>Sensing the characteristic acoustic impedance of a fluid utilizing acoustic <span class="hlt">pressure</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Antlinger, Hannes; Clara, Stefan; Beigelbeck, Roman; Cerimovic, Samir; Keplinger, Franz; Jakoby, Bernhard</p> <p>2012-01-01</p> <p>Ultrasonic sensors can be used to determine physical fluid parameters like viscosity, density, and speed of sound. In this contribution, we present the concept for an integrated sensor utilizing <span class="hlt">pressure</span> <span class="hlt">waves</span> to sense the characteristic acoustic impedance of a fluid. We note that the basic setup generally allows to determine the longitudinal viscosity and the speed of sound if it is operated in a resonant mode as will be discussed elsewhere. In this contribution, we particularly focus on a modified setup where interferences are suppressed by introducing a wedge reflector. This enables sensing of the liquid's characteristic acoustic impedance, which can serve as parameter in condition monitoring applications. We present a device model, experimental results and their evaluation. PMID:23565036</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JNuM..431..160R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JNuM..431..160R"><span>Status of R&D on mitigating the effects of <span class="hlt">pressure</span> <span class="hlt">waves</span> for the Spallation Neutron Source mercury target</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riemer, Bernard W.; Wendel, Mark W.; Felde, David K.; Abdou, Ashraf A.; McClintock, David A.</p> <p>2012-12-01</p> <p>The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory has been conducting R&D on mitigating the effects of <span class="hlt">pressure</span> <span class="hlt">waves</span> in mercury spallation targets since 2001. More precisely, cavitation damage of the target vessel caused by the short beam pulse threatens to limit its lifetime more severely than radiation damage as well as limit its ultimate power capacity - and hence its neutron intensity performance. The R&D program has moved from verification of the beam-<span class="hlt">induced</span> damage phenomena to study of material and surface treatments for damage resistance to the current emphasis on gas injection techniques for damage mitigation. Two techniques are being worked on: injection of small dispersed gas bubbles that mitigate the <span class="hlt">pressure</span> <span class="hlt">waves</span> volumetrically; and protective gas walls that isolate the vessel from the damaging effects of collapsing cavitation bubbles. The latter has demonstrated good damage mitigation during in-beam testing with limited pulses, and adequate gas wall coverage at the beam entrance window has been demonstrated with the SNS mercury target flow configuration using a full scale mercury test loop. A question on the required area coverage remains which depends on results from SNS target post irradiation examination. The small gas bubble technique has been less effective during past in-beam tests but those results were with un-optimized and un-verified bubble populations. Another round of in-beam tests with small gas bubbles is planned for 2011. The first SNS target was removed from service in mid 2009 and samples were cut from two locations at the target's beam entrance window. Through-wall damage was observed at the innermost mercury vessel wall (not a containment wall). The damage pattern suggested correlation with the local mercury flow condition which is nearly stagnant at the peak damage location. Detailed post irradiation examination of the samples is under way that will assess the erosion and measure irradiation-<span class="hlt">induced</span> changes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1060243','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1060243"><span>Status of R&D on Mitigating the Effects of <span class="hlt">Pressure</span> <span class="hlt">Waves</span> for the Spallation Neutron Source Mercury Target</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Riemer, Bernie; Wendel, Mark W; Felde, David K; Abdou, Ashraf A; McClintock, David A</p> <p>2012-01-01</p> <p>The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory has been conducting R&D on mitigating the effects of <span class="hlt">pressure</span> <span class="hlt">waves</span> in mercury spallation targets since 2001. More precisely, cavitation damage of the target vessel caused by the short beam pulse threatens to limit its lifetime more severely than radiation damage as well as limit its ultimate power capacity and hence its neutron intensity performance. The R&D program has moved from verification of the beam-<span class="hlt">induced</span> damage phenomena to study of material and surface treatments for damage resistance to the current emphasis on gas injection techniques for damage mitigation. Two techniques are being worked on: injection of small dispersed gas bubbles that mitigate the <span class="hlt">pressure</span> <span class="hlt">waves</span> volumetrically; and protective gas walls that isolate the vessel from the damaging effects of collapsing cavitation bubbles. The latter has demonstrated good damage mitigation during in-beam testing with limited pulses, and adequate gas wall coverage at the beam entrance window has been demonstrated with the SNS mercury target flow configuration using a full scale mercury test loop. A question on the required area coverage remains which depends on results from SNS target post irradiation examination. The small gas bubble technique has been less effective during past in-beam tests but those results were with un-optimized and un-verified bubble populations. Another round of in-beam tests with small gas bubbles is planned for 2011. The first SNS target was removed from service in mid 2009 and samples were cut from two locations at the target s beam entrance window. Through-wall damage was observed at the innermost mercury vessel wall (not a containment wall). The damage pattern suggested correlation with the local mercury flow condition which is nearly stagnant at the peak damage location. Detailed post irradiation examination of the samples is under way that will assess the erosion and measure irradiation-<span class="hlt">induced</span> changes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005MPLB...19.1731L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005MPLB...19.1731L"><span>Research on the <span class="hlt">Wave-Induced</span> Ship Motions in Front of Different Types of Wharf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Yan Bao; Jiang, Xue Lian</p> <p></p> <p>One important function of the port is to protect ship or some other facilities from <span class="hlt">wave</span> attack so as to stably handle cargoes. In current design codes, there are mainly two expressions of the tranquility standard of harbor basin: one is the acceptable <span class="hlt">wave</span> height in front of wharf; the other is the tolerable amplitude of ship motion. However, ship motions are affected by some more factors simultaneously, such as <span class="hlt">wave</span> frequency, <span class="hlt">wave</span> height, incident <span class="hlt">wave</span> direction, ship properties and wharf type. This paper presents some computed results of the <span class="hlt">wave-induced</span> ship motions on the basis of a port case in China. First, the Simple Green Function method is employed to solve and compare the 2-dimension hydrodynamic coefficients in front of open or bulkhead wharf. The results show a great difference between them. Then, this paper computes and discusses the ship motions in front of open wharf at different <span class="hlt">wave</span> frequencies and incident <span class="hlt">wave</span> directions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...517852T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...517852T"><span>Nonlinear Generation of Electromagnetic <span class="hlt">Waves</span> through <span class="hlt">Induced</span> Scattering by Thermal Plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.</p> <p>2015-12-01</p> <p>We demonstrate the conversion of electrostatic pump <span class="hlt">waves</span> into electromagnetic <span class="hlt">waves</span> through nonlinear <span class="hlt">induced</span> scattering by thermal particles in a laboratory plasma. Electrostatic <span class="hlt">waves</span> in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10-6 times the background magnetic field, <span class="hlt">wave</span> power is scattered below the pump frequency with <span class="hlt">wave</span> normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered <span class="hlt">wave</span> has a perpendicular wavelength that is an order of magnitude larger than the pump <span class="hlt">wave</span> and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered <span class="hlt">wave</span> normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4673455','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4673455"><span>Nonlinear Generation of Electromagnetic <span class="hlt">Waves</span> through <span class="hlt">Induced</span> Scattering by Thermal Plasma</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.</p> <p>2015-01-01</p> <p>We demonstrate the conversion of electrostatic pump <span class="hlt">waves</span> into electromagnetic <span class="hlt">waves</span> through nonlinear <span class="hlt">induced</span> scattering by thermal particles in a laboratory plasma. Electrostatic <span class="hlt">waves</span> in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10−6 times the background magnetic field, <span class="hlt">wave</span> power is scattered below the pump frequency with <span class="hlt">wave</span> normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered <span class="hlt">wave</span> has a perpendicular wavelength that is an order of magnitude larger than the pump <span class="hlt">wave</span> and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered <span class="hlt">wave</span> normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment. PMID:26647962</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..DPPPP8002P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DPPPP8002P"><span>Lower Hybrid <span class="hlt">Wave</span> <span class="hlt">Induced</span> Rotation on Alcator C-Mod</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parker, Ron; Podpaly, Yuri; Rice, John; Schmidt, Andrea</p> <p>2009-11-01</p> <p>Injection of RF power in the vicinity of the lower hybrid frequency has been observed to cause strong counter current rotation in Alcator C-Mod plasmas [1,2]. The spin-up rate is consistent with the rate at which momentum is injected by the LH <span class="hlt">waves</span>, and also the rate at which fast electron momentum is transferred to the ions. A momentum diffusivity of ˜ 0.1 m^2/s is sufficient to account for the observed steady-state rotation. This value is also comparable with that derived from an analysis of rotation <span class="hlt">induced</span> by RF mode conversion [3]. Radial force balance requires a radial electric field, suggesting a buildup of negative charge in the plasma core. This may be the result of an inward pinch of the LH produced fast electrons, as would be expected for resonant trapped particles. Analysis of the fast-electron-produced bremsstrahlung during LH power modulation experiments yields an inward pinch velocity of ˜ 1 m/s, consistent with the estimated trapped particle pinch velocity. [4pt] [1] A. Ince-Cushman, et.al., Phys. Rev. Lett., 102, 035002 (2009)[0pt] [2] J. E. Rice, et. al., Nucl. Fusion 49, 025004 (2009)[0pt] [3] Y. Lin, et.al., this meeting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21054532','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21054532"><span>High-Frequency Gravitational <span class="hlt">Wave</span> <span class="hlt">Induced</span> Nuclear Fusion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fontana, Giorgio; Baker, Robert M. L. Jr.</p> <p>2007-01-30</p> <p>Nuclear fusion is a process in which nuclei, having a total initial mass, combine to produce a single nucleus, having a final mass less than the total initial mass. Below a given atomic number the process is exothermic; that is, since the final mass is less than the combined initial mass and the mass deficit is converted into energy by the nuclear fusion. On Earth nuclear fusion does not happen spontaneously because electrostatic barriers prevent the phenomenon. To <span class="hlt">induce</span> controlled, industrial scale, nuclear fusion, only a few methods have been discovered that look promising, but net positive energy production is not yet possible because of low overall efficiency of the systems. In this paper we propose that an intense burst of High Frequency Gravitational <span class="hlt">Waves</span> (HFGWs) could be focused or beamed to a target mass composed of appropriate fuel or target material to efficiently rearrange the atomic or nuclear structure of the target material with consequent nuclear fusion. Provided that efficient generation of HFGW can be technically achieved, the proposed fusion reactor could become a viable solution for the energy needs of mankind and alternatively a process for beaming energy to produce a source of fusion energy remotely - even inside solid materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890004471','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890004471"><span>Constraints on gravity <span class="hlt">wave</span> <span class="hlt">induced</span> diffusion in the middle atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Strobel, Darrell F.</p> <p>1988-01-01</p> <p>A review of the important constraints on gravity <span class="hlt">wave</span> <span class="hlt">induced</span> diffusion of chemical tracers, heat and momentum is given. Ground-based microwave spectroscopy measurements of H2O and CO and rocket-based mass spectrometer measurements of Ar constrain the eddy diffusion coefficient for constituent transport (K sub zz) to be (1-3) x 10 to the 5th sq cm/sec in the upper mesosphere. Atomic oxygen data also limits K sub zz to a comparable value in the mesopause. From the energy balance of the upper mesosphere the eddy diffusion coefficient for heat transport (D sub H) is, at most, 6 x 10 to the 5th sq cm/sec at the mesopause and decreasing substantially with decreasing altitude. The available evidence for mean wind deceleration and the corresponding eddy diffusion coefficient for momentum stresses (D sub M) suggests that it is at least 1 x 10 to the 6th sq cm/sec in the upper mesosphere. Consequently the eddy Prandtl number for macroscopic scale lengths is greater than 3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AIPC..829..328I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..829..328I"><span>Characterization of the HIFU-<span class="hlt">induced</span> cloud cavitation for the optimization of high <span class="hlt">pressure</span> concentration for lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ikeda, Teiichiro; Yoshizawa, Shin; Kaneko, Yukio; Matsumoto, Yoichiro</p> <p>2006-05-01</p> <p>The bubble cloud is a highly scattering object; to the contrary, it is also a strong <span class="hlt">pressure</span> <span class="hlt">wave</span> enhancer, if the wavelength and amplitude of the <span class="hlt">wave</span> is appropriate ones. We've been investigated the stone erosion enhancement in the existence of bubble cloud on the stone surface by using high frequency waveform that immediately followed by low frequency trailing pulse (C-C waveform; Cavitation Control waveform). For the optimization of the high <span class="hlt">pressure</span> concentration it is needed to know, "how the enhancement of the <span class="hlt">pressure</span> <span class="hlt">wave</span> through the bubble cloud" and "how we can estimate the efficiency thorough the passive detection of the reflected signal from the bubble cloud". We measured the "Transmittance" and "Reflection" by two types of acoustic emission sensors, PCD (Passive Cavitation Detector) and DCD (Direct Collapse Detector). The results well depict the characteristics of the HIFU-<span class="hlt">induced</span> bubble cloud responses. The response curves reveal that the local maxima of the "Transmittance" and "Reflection" occur at the different bubble cloud volume. The PCD signal is higher in the larger bubble cloud band. The DCD signal is larger in the smaller bubble cloud band. These tendencies imply the therapeutic effect through the bubble cloud is optimized in the small bubble cloud region and too much bubbles scatter the incoming ultrasound <span class="hlt">wave</span> and the ultrasound <span class="hlt">wave</span> does not efficiently propagates inward the bubble cloud. Thus, for the optimization of the bubble cloud collapse, the cavitation threshold can be the lower limit and the large scattering amplitude from bubble cloud can be the upper limit of the ultrasound conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..SHK.F1011B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..SHK.F1011B"><span>Microscopic studies of cellular damage <span class="hlt">induced</span> by compression <span class="hlt">waves</span> in different environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bo, Chiara; Balzer, Jens; Brown, Katherine A.; Proud, William G.</p> <p>2011-06-01</p> <p>The cellular basis of <span class="hlt">induced</span>-damage in biological samples under dynamic loading conditions is largely uncharacterized. In this study we propose a new approach to investigate the effects of compression <span class="hlt">waves</span> on in-vitro grown Stem cells extracted from BALB/c mice. A modified split Hopkinson <span class="hlt">pressure</span> bar system is used to simulate damage in the biological samples: the cells are inserted in a confinement chamber either in their growing media or on a 3D scaffold, they are subjected to compression <span class="hlt">waves</span> and finally recovered for further analysis. The difference in mechanical impedance between the cells and the hosting environments is believed to be a key point in the generation of damage. To discriminate the effects of the different mechanical supports on cell morphology pre and after compression, membrane and cytoskeletal proteins disruptions are investigated using fluorescence confocal microscopy. Understanding the underlying mechanism of damage at the microscopic scale could set the basis for the development of therapeutic applications at the cellular level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5319..155S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5319..155S"><span>Study for prevention of proliferation of smooth muscle cells after balloon angioplasty using Ho:YAG laser-<span class="hlt">induced</span> acoustic <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suga, Eriko; Yamashita, Erika; Futami, Hikaru; Arai, Tsunenori</p> <p>2004-07-01</p> <p>We designed the method for prevention of restenosis after balloon angioplasty using laser-<span class="hlt">induced</span> bubble-collapse acoustic <span class="hlt">wave</span>. This study was performed to evaluate the effect on smooth muscle cells (SMCs) by Ho:YAG laser (λ=2.10μm)-<span class="hlt">induced</span> acoustic <span class="hlt">wave</span>, in vitro and in vivo. The laser energy was delivered by a silica glass fiber into water. Sound <span class="hlt">pressure</span> was measured with a hydrophone changing the laser energy. The laser-<span class="hlt">induced</span> acoustic <span class="hlt">wave</span> was loaded to SMCs in vitro. This acoustic effect on SMCs was measured by MTT assay. The acoustic <span class="hlt">wave</span> loaded SMCs were controllably injured with the laser energy and laser shots. The balloon denudated rabbit aorta was used to evaluate in vivo effect. The laser-<span class="hlt">induced</span> acoustic <span class="hlt">wave</span> loaded aorta was extracted at 42 days after the laser irradiation, and was examined by Hematoxylin-Eosin staining. We found that the laser irradiation of 20 pulses with 60mJ/pulse prevented SMCs proliferation. We think the mechanism of this effect might be same as brachytherapy. We demonstrated the applicability of Ho:YAG laser-<span class="hlt">induced</span> acoustic <span class="hlt">wave</span> against vascular restenosis after balloon angioplasty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27388527','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27388527"><span>Changes in Central Aortic <span class="hlt">Pressure</span> Levels, <span class="hlt">Wave</span> Components and Determinants Associated with High Peripheral Blood <span class="hlt">Pressure</span> States in Childhood: Analysis of Hypertensive Phenotype.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>García-Espinosa, Victoria; Curcio, Santiago; Marotta, Marco; Castro, Juan M; Arana, Maite; Peluso, Gonzalo; Chiesa, Pedro; Giachetto, Gustavo; Bia, Daniel; Zócalo, Yanina</p> <p>2016-10-01</p> <p>The aims were to determine whether children's high peripheral blood <span class="hlt">pressure</span> states (HBP) are associated with increased central aortic blood <span class="hlt">pressure</span> (BP) and to characterize hemodynamic and vascular changes associated with HBP in terms of changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse <span class="hlt">wave</span> velocity, PWV), peripheral vascular resistances (PVR) and net and relative contributions of reflected <span class="hlt">waves</span> to the aortic pulse amplitude. We included 154 subjects (mean age 11; range 4-16 years) assigned to one of two groups: normal peripheral BP (NBP, n = 101), defined as systolic and diastolic BP < 90th percentile, or high BP (HBP, n = 53), defined as average systolic and/or diastolic BP levels ≥90th percentile (curves for sex, age and body height). The HBP group included children with hypertensive and pre-hypertensive BP levels. After a first analysis, groups were compared excluding obese and dyslipidemic children. Peripheral and central aortic BP, PWV and pulse <span class="hlt">wave</span>-derived parameters (augmentation index, forward and backward <span class="hlt">wave</span> components' amplitude) were measured using gold-standard techniques, applanation tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). Independent of the presence of dyslipidemia and/or obesity, aortic systolic and pulse BP were higher in HBP than in NBP children. The increase in central BP could not be explained by an increase in the relative contribution of reflections to the aortic <span class="hlt">pressure</span> <span class="hlt">wave</span>, higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP would be explained by an increase in the amplitude of both incident and reflected <span class="hlt">wave</span> components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17302561','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17302561"><span>Stretch-activated calcium channels relay fast calcium <span class="hlt">waves</span> propagated by calcium-<span class="hlt">induced</span> calcium influx.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaffe, Lionel F</p> <p>2007-03-01</p> <p>For nearly 30 years, fast calcium <span class="hlt">waves</span> have been attributed to a regenerative process propagated by CICR (calcium-<span class="hlt">induced</span> calcium release) from the endoplasmic reticulum. Here, I propose a model containing a new subclass of fast calcium <span class="hlt">waves</span> which is propagated by CICI (calcium-<span class="hlt">induced</span> calcium influx) through the plasma membrane. They are called fast CICI <span class="hlt">waves</span>. These move at the order of 100 to 1000 microm/s (at 20 degrees C), rather than the order of 3 to 30 microm/s found for CICR. Moreover, in this proposed subclass, the calcium influx which drives calcium <span class="hlt">waves</span> is relayed by stretch-activated calcium channels. This model is based upon reports from approx. 60 various systems. In seven of these reports, calcium <span class="hlt">waves</span> were imaged, and, in five of these, evidence was presented that these <span class="hlt">waves</span> were regenerated by CICI. Much of this model involves <span class="hlt">waves</span> that move along functioning flagella and cilia. In these systems, <span class="hlt">waves</span> of local calcium influx are thought to cause <span class="hlt">waves</span> of local contraction by <span class="hlt">inducing</span> the sliding of dynein or of kinesin past tubulin microtubules. Other cells which are reported to exhibit <span class="hlt">waves</span>, which move at speeds in the fast CICI range, include ones from a dozen protozoa, three polychaete worms, three molluscs, a bryozoan, two sea urchins, one arthropod, four insects, Amphioxus, frogs, two fish and a vascular plant (Equisetum), together with numerous healthy, as well as cancerous, mammalian cells, including ones from human. In two of these systems, very gentle local mechanical stimulation is reported to initiate <span class="hlt">waves</span>. In these non-flagellar systems, the calcium influxes are thought to speed the sliding of actinomyosin filaments past each other. Finally, I propose that this mechanochemical model could be tested by seeing if gentle mechanical stimulation <span class="hlt">induces</span> <span class="hlt">waves</span> in more of these systems and, more importantly, by imaging the predicted calcium <span class="hlt">waves</span> in more of them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhD...48y5201O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhD...48y5201O"><span>Diagnostics of surface <span class="hlt">wave</span> driven low <span class="hlt">pressure</span> plasmas based on indium monoiodide-argon system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ögün, C. M.; Kaiser, C.; Kling, R.; Heering, W.</p> <p>2015-06-01</p> <p>Indium monoiodide is proposed as a suitable alternative to hazardous mercury, i.e. the emitting component inside the compact fluorescent lamps (CFL), with comparable luminous efficacy. Indium monoiodide-argon low <span class="hlt">pressure</span> lamps are electrodelessly driven with surface <span class="hlt">waves</span>, which are launched and coupled into the lamp by the ‘surfatron’, a microwave coupler optimized for an efficient operation at a frequency of 2.45 GHz. A non intrusive diagnostic method based on spatially resolved optical emission spectroscopy is employed to characterize the plasma parameters. The line emission coefficients of the plasma are derived by means of Abel’s inversion from the measured spectral radiance data. The characteristic plasma parameters, e.g. electron temperature and density are determined by comparing the experimentally obtained line emission coefficients with simulated ones from a collisional-radiative model. Additionally, a method to determine the absolute plasma efficiency via irradiance measurements without any goniometric setup is presented. In this way, the relationship between the plasma efficiency and the plasma parameters can be investigated systematically for different operating configurations, e.g. electrical input power, buffer gas <span class="hlt">pressure</span> and cold spot temperature. The performance of indium monoiodide-argon plasma is compared with that of conventional CFLs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMMR53B0982K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMMR53B0982K"><span>Sound <span class="hlt">wave</span> velocities of Fe-Ni alloy at high <span class="hlt">pressure</span> and temperature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kantor, A.; Dubrovinsky, L.; Kantor, I.; Kurnosov, A.; Kuznetsov, A.; Dubrovinskaia, N.; Krisch, M.</p> <p>2006-12-01</p> <p>Knowledge of high-<span class="hlt">pressure</span> and high-temperature elasticity of Fe-Ni alloy with low (5-25%) Ni content is crucial for geosciences since it is probably the major component of the core of the Earth, Mars, Mercury, Moon, satellites of Saturn and Jupiter. High-<span class="hlt">pressure</span> and high-temperature (up to 41 GPa and 700 K) study of FeNi alloy with 22% of Ni was carried out by mean of inelastic X-ray scattering (IXS) from polycrystalline material. Two sets of experiments: at room temperature and at 700 K have been performed. Before and after every measurement (taking about 10 hours) an in-situ 1-D monochromatic X-ray diffraction pattern was collected for volume determination exactly from the sample. X-ray diffraction study revealed stability of fcc over hcp phase in the whole studied P,T range. Isothermal equation of state was derived at room temperature and at 700 K. X-ray inelastic scattering measurements allow to calculate longitudinal acoustic <span class="hlt">wave</span> velocity VL, that gives, combined with measured equations of state, full isotropic elasticity of the material. We did not observe strong deviations of fcc iron-nickel alloy bulk elasticity from elastic properties of pure hcp iron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4348918','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4348918"><span>Exercise preconditioning attenuates <span class="hlt">pressure</span> overload-<span class="hlt">induced</span> pathological cardiac hypertrophy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Tongyi; Tang, Hao; Zhang, Ben; Cai, Chengliang; Liu, Xiaohong; Han, Qingqi; Zou, Liangjian</p> <p>2015-01-01</p> <p>Pathological cardiac hypertrophy, a common response of the heart to a variety of cardiovascular diseases, is typically associated with myocytes remodeling and fibrotic replacement, cardiac dysfunction. Exercise preconditioning (EP) increases the myocardial mechanical load and enhances tolerance of cardiac ischemia-reperfusion injury (IRI), however, is less reported in pathological cardiac hypertrophy. To determine the effect of EP in pathological cardiac hypertrophy, Male 10-wk-old Sprague-Dawley rats (n=30) were subjected to 4 weeks of EP followed by 4-8 weeks of <span class="hlt">pressure</span> overload (transverse aortic constriction, TAC) to <span class="hlt">induce</span> pathological remodeling. TAC in untrained controls (n=30) led to pathological cardiac hypertrophy, depressed systolic function. We observed that left ventricular wall thickness in end diastole, heart size, heart weight-to-body weight ratio, heart weight-to-tibia length ratio, cross-sectional area of cardiomyocytes and the reactivation of fetal genes (atrial natriuretic peptide and brain natriuretic peptide) were markedly increased, meanwhile left ventricular internal dimension at end-diastole, systolic function were significantly decreased by TAC at 4 wks after operation (P < 0.01), all of which were effectively inhibited by EP treatment (P < 0.05), but the differences of these parameters were decreased at 8 wks after operation. Furthermore, EP treatment inhibited degradation of IκBα, and decreased NF-κB p65 subunit levels in the nuclear fraction, and then reduced IL2 levels in the myocardium of rats subject to TAC. EP can effectively attenuate pathological cardiac hypertrophic responses <span class="hlt">induced</span> by TAC possibly through inhibition of degradation of IκB and blockade of the NF-κB signaling pathway in the early stage of pathological cardiac hypertrophy. PMID:25755743</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28390176','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28390176"><span>Cucurbitacin B Protects Against <span class="hlt">Pressure</span> Overload <span class="hlt">Induced</span> Cardiac Hypertrophy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xiao, Yang; Yang, Zheng; Wu, Qing-Qing; Jiang, Xiao-Han; Yuan, Yuan; Chang, Wei; Bian, Zhou Yan; Zhu, Jin Xiu; Tang, Qi-Zhu</p> <p>2017-04-08</p> <p>Lack of effective anti-cardiac hypertrophy drugs creates a major cause for the increasing prevalence of heart failure. In the present study, we determined the anti-hypertrophy and anti-fibrosis potential of a natural plant triterpenoid, Cucurbitacin B both in vitro and in vivo. Aortic banding (AB) was performed to <span class="hlt">induce</span> cardiac hypertrophy. After 1 week of surgery, mice were receive cucurbitacin B treatment (Gavage, 0.2 mg/kg body weight/2 day). Afer 4 weeks of AB, cucurbitacin B demonstrated a strong anti- hypertrophy and anti-fibrosis ability as evidenced by decreased of heart weight, myocardial cell cross-sectional area and interstitial fibrosis, ameliorated of systolic and diastolic abnormalities, normalized in gene expression of hypertrophic and fibrotic markers, reserved microvascular density in <span class="hlt">pressure</span> overload <span class="hlt">induced</span> hypertrophic mice. Cucurbitacin B also showed significant hypertrophy inhibitory effect in phenylephrine stimulated cardiomyocytes. The Cucurbitacin B-mediated mitigated cardiac hypertrophy was attributable to the increasing level of autophagy, which was associated with the blockade of Akt/mTOR/FoxO3a signal pathway, validated by SC79, MK2206, and 3-MA, the Akt agonist, inhibitor and autophagy inhibitor in vitro. The overexpression of constitutively active Akt completely abolished the Cucurbitacin B-mediated protection of cardiac hypertrophy in human cardiomyocytes AC16. Collectively, our findings suggest that cucurbitacin B protects against cardiac hypertrophy through increasing the autophagy level in cardiomyocytes, which is associated with the inhibition of Akt/mTOR/FoxO3a signal axis. This article is protected by copyright. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25360944','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25360944"><span>Dispersive radiation <span class="hlt">induced</span> by shock <span class="hlt">waves</span> in passive resonators.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Malaguti, Stefania; Conforti, Matteo; Trillo, Stefano</p> <p>2014-10-01</p> <p>We show that passive Kerr resonators pumped close to zero dispersion wavelengths on the normal dispersion side can develop the resonant generation of linear <span class="hlt">waves</span> driven by cavity (mixed dispersive-dissipative) shock <span class="hlt">waves</span>. The resonance mechanism can be successfully described in the framework of the generalized Lugiato-Lefever equation with higher-order dispersive terms. Substantial differences with radiation from cavity solitons and purely dispersive shock <span class="hlt">waves</span> dispersion are highlighted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA523020','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA523020"><span>High Sea-Floor Stress <span class="hlt">Induced</span> by Extreme Hurricane <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-01-01</p> <p>mean-square amplitude of a sinusoidal <span class="hlt">wave</span>, where uwu σ2= , 141 and uσ is the standard deviation of orbital-velocity fluctuations based on the 512-s...was a factor of 4 smaller than CWτ based on 182 the <span class="hlt">wave</span>-orbital velocity, uwu σ2= (Figure 3). The current-<span class="hlt">wave</span> stress can be 183 approximated as...and was about 15%-20% of the 207 surface wind stress, where uwu σ2= . The maximum stress based on the maximum <span class="hlt">wave</span>-208 orbital velocity was found to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.9717H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.9717H"><span>MAVEN observations of electron-<span class="hlt">induced</span> whistler mode <span class="hlt">waves</span> in the Martian magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harada, Y.; Andersson, L.; Fowler, C. M.; Mitchell, D. L.; Halekas, J. S.; Mazelle, C.; Espley, J.; DiBraccio, G. A.; McFadden, J. P.; Brain, D. A.; Xu, S.; Ruhunusiri, S.; Larson, D. E.; Lillis, R. J.; Hara, T.; Livi, R.; Jakosky, B. M.</p> <p>2016-10-01</p> <p>We report on narrowband electromagnetic <span class="hlt">waves</span> at frequencies between the local electron cyclotron and lower hybrid frequencies observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft in the Martian <span class="hlt">induced</span> magnetosphere. The peaked electric field <span class="hlt">wave</span> spectra below the electron cyclotron frequency were first observed by Phobos-2 in the Martian magnetosphere, but the lack of magnetic field <span class="hlt">wave</span> data prevented definitive identification of the <span class="hlt">wave</span> mode and their generation mechanisms remain unclear. Analysis of electric and magnetic field <span class="hlt">wave</span> spectra obtained by MAVEN demonstrates that the observed narrowband <span class="hlt">waves</span> have properties consistent with the whistler mode. Linear growth rates computed from the measured electron velocity distributions suggest that these whistler mode <span class="hlt">waves</span> can be generated by cyclotron resonance with anisotropic electrons. Large electron anisotropy in the Martian magnetosphere is caused by absorption of parallel electrons by the collisional atmosphere. The narrowband whistler mode <span class="hlt">waves</span> and anisotropic electrons are observed on both open and closed field lines and have similar spatial distributions in MSO and planetary coordinates. Some of the <span class="hlt">waves</span> on closed field lines exhibit complex frequency-time structures such as discrete elements of rising tones and two bands above and below half the electron cyclotron frequency. These MAVEN observations indicate that whistler mode <span class="hlt">waves</span> driven by anisotropic electrons, which are commonly observed in intrinsic magnetospheres and at unmagnetized airless bodies, are also present at Mars. The <span class="hlt">wave-induced</span> electron precipitation into the Martian atmosphere should be evaluated in future studies.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002514&hterms=electron&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Delectron','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002514&hterms=electron&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Delectron"><span>Maven Observations of Electron-<span class="hlt">Induced</span> Whistler Mode <span class="hlt">Waves</span> in the Martian Magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harada, Y.; Andersson, L.; Fowler, C. M.; Mitchell, D. L.; Halekas, J. S.; Mazelle, C.; Espley, J.; DiBraccio, G. A.; McFadden, J. P.; Brian, D. A.; Xu, S.; Ruhunusiri, S.; Larson, D. E.; Lillis, R. J.; Hara, T.; Livi, R.; Jakosky, B. M.</p> <p>2016-01-01</p> <p>We report on narrowband electromagnetic <span class="hlt">waves</span> at frequencies between the local electron cyclotron and lower hybrid frequencies observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft in the Martian <span class="hlt">induced</span> magnetosphere. The peaked electric field <span class="hlt">wave</span> spectra below the electron cyclotron frequency were first observed by Phobos-2 in the Martian magnetosphere, but the lack of magnetic field <span class="hlt">wave</span> data prevented definitive identification of the <span class="hlt">wave</span> mode and their generation mechanisms remain unclear. Analysis of electric and magnetic field <span class="hlt">wave</span> spectra obtained by MAVEN demonstrates that the observed narrowband <span class="hlt">waves</span> have properties consistent with the whistler mode. Linear growth rates computed from the measured electron velocity distributions suggest that these whistler mode <span class="hlt">waves</span> can be generated by cyclotron resonance with anisotropic electrons. Large electron anisotropy in the Martian magnetosphere is caused by absorption of parallel electrons by the collisional atmosphere. The narrowband whistler mode <span class="hlt">waves</span> and anisotropic electrons are observed on both open and closed field lines and have similar spatial distributions in MSO and planetary coordinates. Some of the <span class="hlt">waves</span> on closed field lines exhibit complex frequency-time structures such as discrete elements of rising tones and two bands above and below half the electron cyclotron frequency. These MAVEN observations indicate that whistler mode <span class="hlt">waves</span> driven by anisotropic electrons, which are commonly observed in intrinsic magnetospheres and at unmagnetized airless bodies, are also present at Mars. The <span class="hlt">wave-induced</span> electron precipitation into the Martian atmosphere should be evaluated in future studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMMR31B0367K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMMR31B0367K"><span><span class="hlt">Pressure-Induced</span> Phase Transitions In Gadolinium Iron Borate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kharlamova, S. A.; Struzhkin, V. V.; Sinogeikin, S. V.; Gavriliuk, A. G.; Brown, D.; Toellner, T.; Zhao, J.; Lerche, M.; Lyubutin, I. S.; Ovchinnikov, S. G.; Alp, E. E.; Sturhahn, W.</p> <p>2007-12-01</p> <p>An understanding of spin crossover (SC) dynamics is relevant to understanding of a role or participation of SC in natural systems including lower Mantle minerals, heme proteins as well as from fundamental science of view. For example, <span class="hlt">pressure-induced</span> electronic spin transitions of Fe2+ and Fe3+ iron occur in magnesiowustite, silicate perovskite and post-perovskite which are abundant minerals in the Earth's lower mantle [1-3]. Such a SC phenomenon has recently been observed in a number of magnetic minerals FeBO3 [4, 5], BiFeO3 [6], Fe2O3 [7], and Y3Fe5O12 [8], (La, Pr)FeO3 [9, 10]. In those cases, iron ions are in the trivalent state Fe3+ and the high-spin-low-spin (HS-LS) crossover is manifested as the collapse of the local magnetic moment and as the transition of the antiferromagnet to a paramagnetic state. For example, in FeBO3 at low temperatures a spin-crossover and some magnetic transitions with two triple points were found [4, 5]. Gadolinium iron borate, GdFe3(BO3)4 is also a system with SEC and recently, we have reported on phase transitions <span class="hlt">induced</span> by high <span class="hlt">pressures</span> in this material [11, 12]. We studied the structural and magnetic behavior of GdFe573(BO3)4 at high <span class="hlt">pressures</span> and temperatures using a diamond anvil cell and a Synchrotron Mossbauer Spectroscopy technique. The hyperfine parameters and results obtained from the experiments are discussed. Based on our experimental data and theoretical calculation a tentative magnetic P-T phase diagram and an equation of states of GdFe573(BO3)4 are proposed. Important features of the phase diagram are a spin crossover, insulator-semiconductor transition and possible presence of two triple points where magnetic and paramagnetic phases of the high-spin and low-spin states coexist. 1. J. Badro, J.-P. Rueff, G. Vankó, et al., Science 305, 383 (2004). 2. J. M. Jackson, W. Sturhahn, G. Shen, et al., American Mineralogist 90, 199 (2005). 3. J.Li, V.V. Struzhkin, H.-K. Mao, et al., PNAS 101, 14027 (2004). 4. I.A. Troyan</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ApSS..255.9898A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ApSS..255.9898A"><span>Propagation characteristics of laser-<span class="hlt">induced</span> stress <span class="hlt">wave</span> in deep tissue for gene transfer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ando, Takahiro; Sato, Shunichi; Takano, Shinta; Ashida, Hiroshi; Obara, Minoru</p> <p>2009-09-01</p> <p>Propagation characteristics of laser-<span class="hlt">induced</span> stress <span class="hlt">waves</span> (LISWs) in tissue and their correlation with properties of gene transfection were investigated for targeted deep-tissue gene therapy. LISWs were generated by irradiating a laser-absorbing material with 532-nm Q-switched Nd:YAG laser pulses; a transparent plastic sheet was attached on the absorbing material for plasma confinement. Temporal <span class="hlt">pressure</span> profiles of LISWs that were propagated through different thickness tissues were measured with a needle-type hydrophone and propagation of LISWs in water was visualized by shadowgraph technique. The measurements showed that at a laser fluence of 1.2 J/cm 2 with a laser spot diameter of 3 mm, flat wavefront was maintained for up to 5 mm in depth and peak <span class="hlt">pressure</span> P decreased with increasing tissue thickness d; P was proportional to d-0.54. Rat dorsal skin was injected with plasmid DNA coding for reporter gene, on which different numbers of excised skin(s) was/were placed, and LISWs were applied from the top of the skins. Efficient gene expression was observed in the skin under the 3 mm thick stacked skins, suggesting that deep-located tissue such as muscle can be transfected by transcutaneous application of LISWs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22489555','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22489555"><span>A coupled cluster and Møller-Plesset perturbation theory study of the <span class="hlt">pressure</span> <span class="hlt">induced</span> phase transition in the LiH crystal</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grüneis, Andreas</p> <p>2015-09-14</p> <p>We employ Hartree–Fock, second-order Møller-Plesset perturbation, coupled cluster singles and doubles (CCSD) as well as CCSD plus perturbative triples (CCSD(T)) theory to study the <span class="hlt">pressure</span> <span class="hlt">induced</span> transition from the rocksalt to the cesium chloride crystal structure in LiH. We show that the calculated transition <span class="hlt">pressure</span> converges rapidly in this series of increasingly accurate many-electron <span class="hlt">wave</span> function based theories. Using CCSD(T) theory, we predict a transition <span class="hlt">pressure</span> for the structural phase transition in the LiH crystal of 340 GPa. Furthermore, we investigate the potential energy surface for this transition in the parameter space of the Buerger path.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23556559','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23556559"><span>Spin current-<span class="hlt">induced</span> by a sound <span class="hlt">wave</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lyapilin, Igor I</p> <p>2013-04-01</p> <p>The interaction of conduction electrons with a longitudinal sound <span class="hlt">wave</span> propagating in a crystal in a constant magnetic field is investigated. It is shown that the transverse spin current arises when the longitudinal sound <span class="hlt">wave</span> propagation through the system. The average power absorbed by the spin subsystem of the conduction electrons and the spin-Hall conductivity have a resonant character.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17979449','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17979449"><span>Optimally accurate thermal-<span class="hlt">wave</span> cavity photopyroelectric measurements of <span class="hlt">pressure</span>-dependent thermophysical properties of air: theory and experiments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kwan, Chi-Hang; Matvienko, Anna; Mandelis, Andreas</p> <p>2007-10-01</p> <p>An experimental technique for the measurement of thermal properties of air at low <span class="hlt">pressures</span> using a photopyroelectric (PPE) thermal-<span class="hlt">wave</span> cavity (TWC) was developed. In addition, two theoretical approaches, a conventional one-dimensional thermal-<span class="hlt">wave</span> model and a three-dimensional theory based on the Hankel integral, were applied to interpret the thermal-<span class="hlt">wave</span> field in the thermal-<span class="hlt">wave</span> cavity. The importance of radiation heat transfer mechanisms in a TWC was also investigated. Radiation components were added to the purely conductive model by linearizing the radiation heat transfer component at the cavity boundary. The experimental results indicate that the three-dimensional model is necessary to describe the PPE signal, especially at low frequencies where thermal diffusion length is large and sideways propagation of the thermal-<span class="hlt">wave</span> field becomes significant. Radiation is found to be the dominant contributor of the PPE signal at high frequencies and large cavity lengths, where heat conduction across the TWC length is relatively weak. The three-dimensional theory and the Downhill Simplex algorithm were used to fit the experimental data and extract the thermal diffusivity of air and the heat transfer coefficient in a wide range of <span class="hlt">pressures</span> from 760 to 2.6 Torr. It was shown that judicious adjustments of cavity length and computational best fits to frequency-scanned data using three-dimensional photopyroelectric theory lead to optimally accurate value measurements of thermal diffusivity and heat transfer coefficient at various <span class="hlt">pressures</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.1384C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.1384C"><span>A new climate index controlling winter <span class="hlt">wave</span> activity along the Atlantic coast of Europe: The West Europe <span class="hlt">Pressure</span> Anomaly</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castelle, Bruno; Dodet, Guillaume; Masselink, Gerd; Scott, Tim</p> <p>2017-02-01</p> <p>A pioneering and replicable method based on a 66-year numerical weather and <span class="hlt">wave</span> hindcast is developed to optimize a climate index based on the sea level <span class="hlt">pressure</span> (SLP) that best explains winter <span class="hlt">wave</span> height variability along the coast of western Europe, from Portugal to UK (36-52°N). The resulting so-called Western Europe <span class="hlt">Pressure</span> Anomaly (WEPA) is based on the sea level <span class="hlt">pressure</span> gradient between the stations Valentia (Ireland) and Santa Cruz de Tenerife (Canary Islands). The WEPA positive phase reflects an intensified and southward shifted SLP difference between the Icelandic low and the Azores high, driving severe storms that funnel high-energy <span class="hlt">waves</span> toward western Europe southward of 52°N. WEPA outscores by 25-150% the other leading atmospheric modes in explaining winter-averaged significant <span class="hlt">wave</span> height, and even by a largest amount the winter-averaged extreme <span class="hlt">wave</span> heights. WEPA is also the only index capturing the 2013/2014 extreme winter that caused widespread coastal erosion and flooding in western Europe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4746592','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4746592"><span>Multiple scattering <span class="hlt">induced</span> negative refraction of matter <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pinsker, Florian</p> <p>2016-01-01</p> <p>Starting from fundamental multiple scattering theory it is shown that negative refraction indices are feasible for matter <span class="hlt">waves</span> passing a well-defined ensemble of scatterers. A simple approach to this topic is presented and explicit examples for systems of scatterers in 1D and 3D are stated that imply negative refraction for a generic incoming quantum <span class="hlt">wave</span> packet. Essential features of the effective scattering field, densities and frequency spectrum of scatterers are considered. Additionally it is shown that negative refraction indices allow perfect transmission of the <span class="hlt">wave</span> passing the ensemble of scatterers. Finally the concept of the superlens is discussed, since it is based on negative refraction and can be extended to matter <span class="hlt">waves</span> utilizing the observations presented in this paper which thus paves the way to ‘untouchable’ quantum systems in analogy to cloaking devices for electromagnetic <span class="hlt">waves</span>. PMID:26857266</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26857266','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26857266"><span>Multiple scattering <span class="hlt">induced</span> negative refraction of matter <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pinsker, Florian</p> <p>2016-02-09</p> <p>Starting from fundamental multiple scattering theory it is shown that negative refraction indices are feasible for matter <span class="hlt">waves</span> passing a well-defined ensemble of scatterers. A simple approach to this topic is presented and explicit examples for systems of scatterers in 1D and 3D are stated that imply negative refraction for a generic incoming quantum <span class="hlt">wave</span> packet. Essential features of the effective scattering field, densities and frequency spectrum of scatterers are considered. Additionally it is shown that negative refraction indices allow perfect transmission of the <span class="hlt">wave</span> passing the ensemble of scatterers. Finally the concept of the superlens is discussed, since it is based on negative refraction and can be extended to matter <span class="hlt">waves</span> utilizing the observations presented in this paper which thus paves the way to 'untouchable' quantum systems in analogy to cloaking devices for electromagnetic <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21251579','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21251579"><span>Using line broadening to determine the electron density in an argon surface-<span class="hlt">wave</span> discharge at atmospheric <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Christova, M.; Christov, L.; Castanos-Martinez, E.; Moisan, M.; Dimitrijevic, M. S.</p> <p>2008-10-22</p> <p>Broadening due to collisions with charged particles (Stark broadening ) and neutral atoms, was determined for Ar I 522.1, 549.6 and 603.2 nm spectral lines from the spectral series 3p{sup 5}nd-3p{sup 5}4p, in order to evaluate the electron density in a surface-<span class="hlt">wave</span> discharge at atmospheric <span class="hlt">pressure</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10149081','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10149081"><span>Application of extracorporeal shock <span class="hlt">wave</span> lithotripter (ECSWL) in orthopaedics. II. Dose-response and <span class="hlt">pressure</span> distribution measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, J B; Park, S H; Weinstein, J N; Loening, S; Oster, D</p> <p>1991-01-01</p> <p>In order to apply the extracorporeal shock <span class="hlt">wave</span> lithotripter (ECSWL) technique to the loosening of the bone-cement interface for the extraction of the cement during revision arthroplasty it is essential to know the dose-response characteristics. The present study shows that the number of shocks needed to break the interface between a 2- and 6-mm-thick bovine femoral bone and bone cement is similar to the fatigue behavior of a material, that is, Log(N) = C(kV) + D, where N is the number of shock impulses, kV is the power setting of the lithotripter machine in kilovolts, and C and D are constants. Iso-<span class="hlt">pressure</span> distribution of the traveling shock <span class="hlt">wave</span> front through a simulated bone in a Plexiglass tube using Fuji <span class="hlt">pressure</span> film showed quantitative <span class="hlt">pressure</span> contours from which one can understand the effective area of shock <span class="hlt">wave</span> and its distribution. The most effective area of the shock <span class="hlt">wave</span> was about 1.5 cm in diameter at 23 and 25 kV with <span class="hlt">pressure</span> at least 7.0 MPa which is more than sufficient to break the bone-cement interface in tension.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1133527','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1133527"><span>Small Gas Bubble Experiment for Mitigation of Cavitation Damage and <span class="hlt">Pressure</span> <span class="hlt">Waves</span> in Short-pulse Mercury Spallation Targets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wendel, Mark W; Felde, David K; Sangrey, Robert L; Abdou, Ashraf A; West, David L; Shea, Thomas J; Hasegawa, Shoichi; Kogawa, Hiroyuki; Naoe, Dr. Takashi; Farny, Dr. Caleb H.; Kaminsky, Andrew L</p> <p>2014-01-01</p> <p>Populations of small helium gas bubbles were introduced into a flowing mercury experiment test loop to evaluate mitigation of beam-pulse <span class="hlt">induced</span> cavitation damage and <span class="hlt">pressure</span> <span class="hlt">waves</span>. The test loop was developed and thoroughly tested at the Spallation Neutron Source (SNS) prior to irradiations at the Los Alamos Neutron Science Center - Weapons Neutron Research Center (LANSCE-WNR) facility. Twelve candidate bubblers were evaluated over a range of mercury flow and gas injection rates by use of a novel optical measurement technique that accurately assessed the generated bubble size distributions. Final selection for irradiation testing included two variations of a swirl bubbler provided by Japan Proton Accelerator Research Complex (J-PARC) collaborators and one orifice bubbler developed at SNS. Bubble populations of interest consisted of sizes up to 150 m in radius with achieved gas void fractions in the 10^-5 to 10^-4 range. The nominal WNR beam pulse used for the experiment created energy deposition in the mercury comparable to SNS pulses operating at 2.5 MW. Nineteen test conditions were completed each with 100 pulses, including variations on mercury flow, gas injection and protons per pulse. The principal measure of cavitation damage mitigation was surface damage assessment on test specimens that were manually replaced for each test condition. Damage assessment was done after radiation decay and decontamination by optical and laser profiling microscopy with damaged area fraction and maximum pit depth being the more valued results. Damage was reduced by flow alone; the best mitigation from bubble injection was between half and a quarter that of flow alone. Other data collected included surface motion tracking by three laser Doppler vibrometers (LDV), loop wall dynamic strain, beam diagnostics for charge and beam profile assessment, embedded hydrophones and <span class="hlt">pressure</span> sensors, and sound measurement by a suite of conventional and contact microphones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760023652','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760023652"><span>Pyroxenes and olivines: Structural implications of shock-<span class="hlt">wave</span> data for high <span class="hlt">pressure</span> phases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jeanloz, R.; Ahrens, T. J.</p> <p>1975-01-01</p> <p>The nature of the shock-<span class="hlt">induced</span>, high-<span class="hlt">pressure</span> phases of olivine and pyroxene rocks is examined in the light of data for the densities of a new class of perovskite-related silicate structures. Also examined are some new Hugoniot and release adiabat data for bronzite. Reexamining available shock data for magnesian pyroxenes and olivines leads to the conclusion that they define a mixed phase (or disequilibrium) region to about the 100 GPa range, related to the kinetics of phase transformation in these silicates. By recognizing this point, certain discrepancies in previous interpretations of shock data can be explained. A set of theoretical Hugonoits for pyroxene and olivine stoichiometry, perovskite-bearing assemblages was constructed based on their properties deduced from high-<span class="hlt">pressure</span> work, showing that the shock data is compatible with transformations to perovskites in the 45-7GPa region. Finally, the shock data indicate very similar properties for olivine and pyroxene at high <span class="hlt">pressures</span> making them both equally likely candidates for the lower mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028026','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028026"><span>Nearshore <span class="hlt">wave-induced</span> cyclical flexing of sea cliffs</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Adams, P.N.; Storlazzi, C.D.; Anderson, R. Scott</p> <p>2005-01-01</p> <p>[1] Evolution of a tectonically active coast is driven by geomorphically destructive energy supplied by ocean <span class="hlt">waves</span>. <span class="hlt">Wave</span> energy is episodic and concentrated; sea cliffs are battered by the geomorphic wrecking ball every 4-25 s. We measure the response of sea cliffs to <span class="hlt">wave</span> assault by sensing the ground motion using near-coastal seismometers. Sea cliffs respond to <span class="hlt">waves</span> in two distinct styles. High-frequency motion (20 Hz) reflects the natural frequency of the sea cliff as it rings in response to direct <span class="hlt">wave</span> impact. Low-frequency motion in the 0.1-0.05 Hz (10-20 s) band consistently agrees with the dominant nearshore <span class="hlt">wave</span> period. Integrating microseismic velocities suggests 50 ??m and 10 ??m displacements in horizontal and vertical directions, respectively. Displacement ellipsoids exhibit simultaneous downward and seaward sea cliff motion with each <span class="hlt">wave</span>. Video footage corroborates the downward sea cliff flex in response to the imposed water load on the <span class="hlt">wave</span> cut platform. Gradients in displacement amplitudes documented using multiple seismometers suggest longitudinal and shear strain of the flexing sea cliff on the order of 0.5-4 ?? strains during each <span class="hlt">wave</span> loading cycle. As this sea cliff flexure occurs approximately 3 million times annually, it has the potential to fatigue the rock through cyclical loading. Local sea cliff retreat rates of 10 cm/yr imply that a given parcel of rock is flexed through roughly 109 cycles of increasing amplitude before exposure to direct <span class="hlt">wave</span> attack at the cliff face. Copyright 2005 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMNH32A..08L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMNH32A..08L"><span>Seismic-<span class="hlt">induced</span> water <span class="hlt">waves</span> by the March 2011 Japan earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, L.; Liang, W.; Liang, M.; Huang, N.</p> <p>2011-12-01</p> <p>On March 11, 2011, the Mw 9.0 Tohoku earthquake caused unusual water <span class="hlt">waves</span> in many harbors. After about 10 minutes, significant changes in sea level were observed in the coastal regions of Taiwan. The event also <span class="hlt">induced</span> seismic surface <span class="hlt">waves</span> of ~7 cm displacement. The effects of earthquake on water bodies were examined in Taiwan, Japan and Russia. Results show the effect is more amplified at the islands than in the continental area. Other dominant features from this analysis are the roughly 20-40 cm amplitude, period of 2-5 minutes oscillations and ~20 cm amplitude of tsunami <span class="hlt">waves</span> at the Orchid island of Taiwan. The superposition of two <span class="hlt">waves</span> estimates the amplitude of roughly 40 cm at the island but has two different source mechanisms. Therefore, the real tsunami is overestimate and the arrival time for tsunami <span class="hlt">wave</span> groups need to be adjusted. This study will focus on the forced <span class="hlt">waves</span> caused by the passing of seismic <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16803082','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16803082"><span>Generation of sub-Mbar <span class="hlt">pressure</span> by converging shock <span class="hlt">waves</span> produced by the underwater electrical explosion of a wire array.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Krasik, Ya E; Grinenko, A; Sayapin, A; Gurovich, V Tz; Schnitzer, I</p> <p>2006-05-01</p> <p>We report a demonstration of a generation of sub-Mbar <span class="hlt">pressure</span> on the axis of the implosion <span class="hlt">wave</span> produced by an underwater electrical explosion of a cylindrical wire array. The array was exploded by microsecond time scale discharge of a capacitor bank having a stored energy of 4.5 kJ and discharge current amplitude of up to 90 kA. Optical diagnostics were used to determine the time of flight and the trajectory of the converging shock <span class="hlt">wave</span>. This data were applied for a calculation of the water flow parameters using one-dimensional (1D) and 2D hydrodynamic calculations and the Whitham method. All three methods have shown that the shock <span class="hlt">wave</span> <span class="hlt">pressure</span> at 0.1 mm from the axis reaches .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.5190G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.5190G"><span>A <span class="hlt">pressure-induced</span>, magnetic transition in pyrrhotite: Implications for the formation <span class="hlt">pressure</span> of meteorites and diamonds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gilder, S. A.; Egli, R.; Hochleitner, R.; Roud, S. C.; Volk, M. W. R.; Le Goff, M.; de Wit, M.</p> <p>2012-04-01</p> <p>Meteorites and diamonds encounter high <span class="hlt">pressures</span> during their formation or subsequent evolution. These materials sometimes contain magnetic inclusions of pyrrhotite. Because magnetic properties are sensitive to strain, pyrrhotite can potentially record the shock or formation <span class="hlt">pressures</span> of its host. Moreover, pyrrhotite undergoes a <span class="hlt">pressure-induced</span> phase transition between 1.6 and 6.2 GPa, but the magnetic signature of this transition is poorly known. Here we report room temperature magnetic measurements on multi- and single domain pyrrhotite under non-hydrostatic <span class="hlt">pressure</span> up to 4.5 GPa. We find that the ratio of magnetic coercivity and remanence follows a logarithmic law with respect to <span class="hlt">pressure</span>, which can potentially be used as a geobarometer. Due to the greater thermal expansion of pyrrhotite with respect to diamond, pyrrhotite inclusions in diamond experience a confining <span class="hlt">pressure</span> at the Earth's surface. Applying our experimentally derived magnetic geobarometer to pyrrhotite-bearing diamonds from Botswana and the Central African Republic suggests the <span class="hlt">pressures</span> of the pyrrhotite inclusions in the diamonds range from 1.3 to 2.1 GPa. These overpressures constrain the mantle source <span class="hlt">pressures</span> from 5.4 to 9.5 GPa, depending on which bulk modulus and thermal expansion coefficients of the two phases are used. We are now trying to develop magnetic barometers on other magnetic phases to apply to meteorites, ultimately to constrain the minimum <span class="hlt">pressure</span> in which the meteorite formed and, hence, information regarding the planetesmal's size, and/or depth, in which the meteorite was derived.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004PhRvB..70p5417S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004PhRvB..70p5417S"><span><span class="hlt">Pressure-induced</span> hard-to-soft transition of a single carbon nanotube</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, D. Y.; Shu, D. J.; Ji, M.; Liu, Feng; Wang, M.; Gong, X. G.</p> <p>2004-10-01</p> <p>We demonstrate a hydrostatic <span class="hlt">pressure-induced</span> hard-to-soft transition of an isolated single wall carbon nanotube, using classical and ab initio constant-<span class="hlt">pressure</span> molecular-dynamics simulations and continuum elastic theory analysis. At low <span class="hlt">pressure</span>, the carbon tube is hard. Above a critical <span class="hlt">pressure</span>, the tube becomes much softer with a decrease of bulk modulus by two orders of magnitude. The hard-to-soft transition is caused by a <span class="hlt">pressure-induced</span> shape transition of the tube cross section from circular to elliptical.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3412201','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3412201"><span>Effects of Heat <span class="hlt">Wave</span> on Body Temperature and Blood <span class="hlt">Pressure</span> in the Poor and Elderly</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kim, Soyeon; Cheong, Hae-Kwan; Ahn, Byungok; Choi, Kyusik</p> <p>2012-01-01</p> <p>Objectives We aimed to investigate the acute effects of heat stress on body temperature and blood <span class="hlt">pressure</span> of elderly individuals living in poor housing conditions. Methods Repeated measurements of the indoor temperature, relative humidity, body temperature, and blood <span class="hlt">pressure</span> were conducted for 20 elderly individuals living in low-cost dosshouses in Seoul during hot summer days in 2010. Changes in the body temperature, systolic blood <span class="hlt">pressure</span> (SBP) and diastolic blood <span class="hlt">pressure</span> (DBP) according to variations in the indoor and outdoor temperature and humidity were analyzed using a repeated-measures ANOVA controlling for age, sex, alcohol, and smoking. Results Average indoor and outdoor temperatures were 31.47℃ (standard deviation [SD], 0.97℃) and 28.15℃ (SD, 2.03℃), respectively. Body temperature increased by 0.21℃ (95% confidence interval [CI], 0.16 to 0.26℃) and 0.07℃ (95% CI, 0.04 to 0.10℃) with an increase in the indoor and outdoor temperature of 1℃. DBP decreased by 2.05 mmHg (95% CI, 0.05 to 4.05 mmHg), showing a statistical significance, as the indoor temperature increased by 1℃, while it increased by 0.20 mmHg (95% CI, -0.83 to 1.22 mmHg) as outdoor temperature increased by 1℃. SBP decreased by 1.75 mmHg (95% CI, -1.11 to 4.61 mmHg) and 0.35 mmHg (95% CI, -1.04 to 1.73 mmHg), as the indoor and outdoor temperature increased by 1℃, respectively. The effects of relative humidity on SBP and DBP were not statistically significant for both indoor and outdoor. Conclusions The poor and elderly are directly exposed to heat <span class="hlt">waves</span>, while their vital signs respond sensitively to increase in temperature. Careful adaptation strategies to climate change considering socioeconomic status are therefore necessary. PMID:22888472</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27110789','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27110789"><span>Signal Analysis and Waveform Reconstruction of Shock <span class="hlt">Waves</span> Generated by Underwater Electrical Wire Explosions with Piezoelectric <span class="hlt">Pressure</span> Probes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Haibin; Zhang, Yongmin; Han, Ruoyu; Jing, Yan; Wu, Jiawei; Liu, Qiaojue; Ding, Weidong; Qiu, Aici</p> <p>2016-04-22</p> <p>Underwater shock <span class="hlt">waves</span> (SWs) generated by underwater electrical wire explosions (UEWEs) have been widely studied and applied. Precise measurement of this kind of SWs is important, but very difficult to accomplish due to their high peak <span class="hlt">pressure</span>, steep rising edge and very short pulse width (on the order of tens of μs). This paper aims to analyze the signals obtained by two kinds of commercial piezoelectric <span class="hlt">pressure</span> probes, and reconstruct the correct <span class="hlt">pressure</span> waveform from the distorted one measured by the <span class="hlt">pressure</span> probes. It is found that both PCB138 and Müller-plate probes can be used to measure the relative SW <span class="hlt">pressure</span> value because of their good uniformities and linearities, but none of them can obtain precise SW waveforms. In order to approach to the real SW signal better, we propose a new multi-exponential <span class="hlt">pressure</span> waveform model, which has considered the faster <span class="hlt">pressure</span> decay at the early stage and the slower <span class="hlt">pressure</span> decay in longer times. Based on this model and the energy conservation law, the <span class="hlt">pressure</span> waveform obtained by the PCB138 probe has been reconstructed, and the reconstruction accuracy has been verified by the signals obtained by the Müller-plate probe. Reconstruction results show that the measured SW peak <span class="hlt">pressures</span> are smaller than the real signal. The waveform reconstruction method is both reasonable and reliable.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4851087','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4851087"><span>Signal Analysis and Waveform Reconstruction of Shock <span class="hlt">Waves</span> Generated by Underwater Electrical Wire Explosions with Piezoelectric <span class="hlt">Pressure</span> Probes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhou, Haibin; Zhang, Yongmin; Han, Ruoyu; Jing, Yan; Wu, Jiawei; Liu, Qiaojue; Ding, Weidong; Qiu, Aici</p> <p>2016-01-01</p> <p>Underwater shock <span class="hlt">waves</span> (SWs) generated by underwater electrical wire explosions (UEWEs) have been widely studied and applied. Precise measurement of this kind of SWs is important, but very difficult to accomplish due to their high peak <span class="hlt">pressure</span>, steep rising edge and very short pulse width (on the order of tens of μs). This paper aims to analyze the signals obtained by two kinds of commercial piezoelectric <span class="hlt">pressure</span> probes, and reconstruct the correct <span class="hlt">pressure</span> waveform from the distorted one measured by the <span class="hlt">pressure</span> probes. It is found that both PCB138 and Müller-plate probes can be used to measure the relative SW <span class="hlt">pressure</span> value because of their good uniformities and linearities, but none of them can obtain precise SW waveforms. In order to approach to the real SW signal better, we propose a new multi-exponential <span class="hlt">pressure</span> waveform model, which has considered the faster <span class="hlt">pressure</span> decay at the early stage and the slower <span class="hlt">pressure</span> decay in longer times. Based on this model and the energy conservation law, the <span class="hlt">pressure</span> waveform obtained by the PCB138 probe has been reconstructed, and the reconstruction accuracy has been verified by the signals obtained by the Müller-plate probe. Reconstruction results show that the measured SW peak <span class="hlt">pressures</span> are smaller than the real signal. The waveform reconstruction method is both reasonable and reliable. PMID:27110789</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OptLE..79...61B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OptLE..79...61B"><span>Determination of hydrocarbon levels in water via laser-<span class="hlt">induced</span> acoustics <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bidin, Noriah; Hossenian, Raheleh; Duralim, Maisarah; Krishnan, Ganesan; Marsin, Faridah Mohd; Nughro, Waskito; Zainal, Jasman</p> <p>2016-04-01</p> <p>Hydrocarbon contamination in water is a major environmental concern in terms of foreseen collapse of the natural ecosystem. Hydrocarbon level in water was determined by generating acoustic <span class="hlt">wave</span> via an innovative laser-<span class="hlt">induced</span> breakdown in conjunction with high-speed photographic coupling with piezoelectric transducer to trace acoustic <span class="hlt">wave</span> propagation. A Q-switched Nd:YAG (40 mJ) was focused in cuvette-filled hydrocarbon solution at various concentrations (0-2000 ppm) to <span class="hlt">induce</span> optical breakdown, shock <span class="hlt">wave</span> generation and later acoustic <span class="hlt">wave</span> propagation. A nitro-dye (ND) laser (10 mJ) was used as a flash to illuminate and frozen the acoustic <span class="hlt">wave</span> propagation. Lasers were synchronised using a digital delay generator. The image of acoustic <span class="hlt">waves</span> was grabbed and recorded via charged couple device (CCD) video camera at the speed of 30 frames/second with the aid of Matrox software version 9. The optical delay (0.8-10.0 μs) between the acoustic <span class="hlt">wave</span> formation and its frozen time is recorded through photodetectors. A piezo-electric transducer (PZT) was used to trace the acoustic <span class="hlt">wave</span> (sound signal), which cascades to a digital oscilloscope. The acoustic speed is calculated from the ratio of acoustic <span class="hlt">wave</span> radius (1-8 mm) and optical time delay. Acoustic <span class="hlt">wave</span> speed is found to linearly increase with hydrocarbon concentrations. The acoustic signal generation at higher hydrocarbon levels in water is attributed to supplementary mass transfer and impact on the probe. Integrated high-speed photography with transducer detection system authenticated that the signals indeed emerged from the laser-<span class="hlt">induced</span> acoustic <span class="hlt">wave</span> instead of photothermal processes. It is established that the acoustic <span class="hlt">wave</span> speed in water is used as a fingerprint to detect the hydrocarbon levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2564T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2564T"><span>Microseismicity <span class="hlt">Induced</span> by Fluid <span class="hlt">Pressure</span> Drop (Laboratory Study)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turuntaev, Sergey; Zenchenko, Evgeny; Melchaeva, Olga</p> <p>2013-04-01</p> <p>Pore <span class="hlt">pressure</span> change in saturated porous rocks may result in its fracturing (Maury et Fourmaintraux, 1993) and corresponding microseismic event occurrences. Microseismicity due to fluid injection is considered in numerous papers (Maxwell, 2010, Shapiro et al., 2005). Another type of the porous medium fracturing is related with rapid pore <span class="hlt">pressure</span> drop at some boundary. The mechanism of such fracturing was considered by (Khristianovich, 1985) as a model of sudden coal blowing and by (Alidibirov, Panov, 1998) as a model of volcano eruptions. If the porous saturated medium has a boundary where it directly contacted with fluid under the high <span class="hlt">pressure</span> (in a hydraulic fracture or in a borehole), and the <span class="hlt">pressure</span> at that boundary is dropped, the conditions for tensile cracks can be achieved at some distance from the boundary. In the paper, the results of experimental study of saturated porous sample fracturing due to pore <span class="hlt">pressure</span> rapid drop are discussed. The samples (82 mm high, ∅60 mm) were made of quartz sand, which was cemented by "liquid glass" glue with mass fraction 1%. The sample (porosity 35%, uniaxial unconfined compression strength 2.5 MPa) was placed in a mould and saturated by oil. The upper end of the sample contacted with the mould upper lid, the lower end contacted with fluid. The fluid <span class="hlt">pressure</span> was increased to 10 MPa and then discharged through the bottom nipple. The <span class="hlt">pressure</span> increases/drops were repeated 30-50 times. Pore <span class="hlt">pressure</span> and acoustic emission (AE) were registered by transducers mounted into upper and bottom lids of the mould. It was found, that AE sources (corresponded to microfracturing) were spreading from the open end to the closed end of the sample, and that maximal number of AE events was registered at some distance from the opened end. The number of AE pulses increased with every next <span class="hlt">pressure</span> drop, meanwhile the number of pulses with high amplitudes diminished. It was found that AE maximal rate corresponded to the fluid <span class="hlt">pressure</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9894E..0TL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9894E..0TL"><span>Traveling solitary <span class="hlt">wave</span> <span class="hlt">induced</span> by nonlocality in dispersive shock <span class="hlt">wave</span> generation (Conference Presentation)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Louis, Hélène; Odent, Vincent; Louvergneaux, Eric</p> <p>2016-04-01</p> <p>Shock <span class="hlt">waves</span> are well-known nonlinear <span class="hlt">waves</span>, displaying an abrupt discontinuity. Observation can be made in a lot of physical fields, as in water <span class="hlt">wave</span>, plasma and nonlinear optics. Shock <span class="hlt">waves</span> can either break or relax through either catastrophic or regularization phenomena. In this work, we restrain our study to dispersive shock <span class="hlt">waves</span>. This regularization phenomenon implies the emission of dispersive <span class="hlt">waves</span>. We demonstrate experimentally and numerically the generation of spatial dispersive shock <span class="hlt">waves</span> in a nonlocal focusing media. The generation of dispersive shock <span class="hlt">wave</span> in a focusing media is more problematic than in a defocusing one. Indeed, the modulational instability has to be frustrated to observe this phenomenon. In 2010, the dispersive shock <span class="hlt">wave</span> was demonstrated experimentally in a focusing media with a partially coherent beam [1]. Another way is to use a nonlocal media [2]. The impact of nonlocality is more important than the modulational instability frustration. Here, we use nematic liquid crystals (NLC) as Kerr-like nonlocal medium. To achieve shock formation, we use the Riemann condition as initial spatial condition (edge at the beam entrance of the NLC cell). In these experimental conditions, we generate, experimentally and numerically, shock <span class="hlt">waves</span> that relax through the emission of dispersive <span class="hlt">waves</span>. Associated with this phenomenon, we evidence the emergence of a localized <span class="hlt">wave</span> that travels through the transverse beam profile. The beam steepness, which is a good indicator of the shock formation, is maximal at the shock point position. This latter follows a power law versus the injected power as in [3]. Increasing the injected power, we found multiple shock points. We have good agreements between the numerical simulations and the experimental results. [1] W. Wan, D. V Dylov, C. Barsi, and J. W. Fleischer, Opt. Lett. 35, 2819 (2010). [2] G. Assanto, T. R. Marchant, and N. F. Smyth, Phys. Rev. A - At. Mol. Opt. Phys. 78, 1 (2008). [3] N. Ghofraniha, L. S</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JPhD...41t5203D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JPhD...41t5203D"><span>Polydiagnostic calibration performed on a low <span class="hlt">pressure</span> surface <span class="hlt">wave</span> sustained argon plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Vries, N.; Palomares, J. M.; Iordanova, E. I.; van Veldhuizen, E. M.; van der Mullen, J. J. A. M.</p> <p>2008-10-01</p> <p>The electron density and electron temperature of a low <span class="hlt">pressure</span> surface <span class="hlt">wave</span> sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, ne, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, Te, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon <span class="hlt">pressure</span> of 15 mbar, the ne values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 ± 0.5) × 1019 m-3, whereas the ne value (2 ± 0.5) × 1019 m-3 obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high (~1020 m-3). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the Te values obtained with TS are equal to 13 400 ± 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24116532','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24116532"><span>Reverberation clutter <span class="hlt">induced</span> by nonlinear internal <span class="hlt">waves</span> in shallow water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Henyey, Frank S; Tang, Dajun</p> <p>2013-10-01</p> <p>Clutter is related to false alarms for active sonar. It is demonstrated that, in shallow water, target-like clutter in reverberation signals can be caused by nonlinear internal <span class="hlt">waves</span>. A nonlinear internal <span class="hlt">wave</span> is modeled using measured stratification on the New Jersey shelf. Reverberation in the presence of the internal <span class="hlt">wave</span> is modeled numerically. Calculations show that acoustic energy propagating near a sound speed minimum is deflected as a high intensity, higher angle beam into the bottom, where it is backscattered along the reciprocal path. The interaction of sound with the internal <span class="hlt">wave</span> is isolated in space, hence resulting in a target-like clutter, which is found to be greater than 10 dB above the mean reverberation level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12907428','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12907428"><span>Static filling <span class="hlt">pressure</span> in patients during <span class="hlt">induced</span> ventricular fibrillation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schipke, J D; Heusch, G; Sanii, A P; Gams, E; Winter, J</p> <p>2003-12-01</p> <p>The static <span class="hlt">pressure</span> resulting after the cessation of flow is thought to reflect the filling of the cardiovascular system. In the past, static filling <span class="hlt">pressures</span> or mean circulatory filling <span class="hlt">pressures</span> have only been reported in experimental animals and in human corpses, respectively. We investigated arterial and central venous <span class="hlt">pressures</span> in supine, anesthetized humans with longer fibrillation/defibrillation sequences (FDSs) during cardioverter/defibrillator implantation. In 82 patients, the average number of FDSs was 4 +/- 2 (mean +/- SD), and their duration was 13 +/- 2 s. In a total of 323 FDSs, arterial blood <span class="hlt">pressure</span> decreased with a time constant of 2.9 +/- 1.0 s from 77.5 +/- 34.4 to 24.2 +/- 5.3 mmHg. Central venous <span class="hlt">pressure</span> increased with a time constant of 3.6 +/- 1.3 s from 7.5 +/- 5.2 to 11.0 +/- 5.4 mmHg (36 points, 141 FDS). The average arteriocentral venous blood <span class="hlt">pressure</span> difference remained at 13.2 +/- 6.2 mmHg. Although it slowly decreased, the <span class="hlt">pressure</span> difference persisted even with FDSs lasting 20 s. Lack of true equilibrium <span class="hlt">pressure</span> could possibly be due to a waterfall mechanism. However, waterfalls were identified neither between the left ventricle and large arteries nor at the level of the diaphragm in supine patients. We therefore suggest that static filling <span class="hlt">pressures</span>/mean circulatory <span class="hlt">pressures</span> can only be directly assessed if the time after termination of cardiac pumping is adequate, i.e., >20 s. For humans, such times are beyond ethical options.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22228040','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22228040"><span>Mirror force <span class="hlt">induced</span> <span class="hlt">wave</span> dispersion in Alfvén <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Damiano, P. A.; Johnson, J. R.</p> <p>2013-06-15</p> <p>Recent hybrid MHD-kinetic electron simulations of global scale standing shear Alfvén <span class="hlt">waves</span> along the Earth's closed dipolar magnetic field lines show that the upward parallel current region within these <span class="hlt">waves</span> saturates and broadens perpendicular to the ambient magnetic field and that this broadening increases with the electron temperature. Using resistive MHD simulations, with a parallel Ohm's law derived from the linear Knight relation (which expresses the current-voltage relationship along an auroral field line), we explore the nature of this broadening in the context of the increased perpendicular Poynting flux resulting from the increased parallel electric field associated with mirror force effects. This increased Poynting flux facilitates <span class="hlt">wave</span> energy dispersion across field lines which in-turn allows for electron acceleration to carry the field aligned current on adjacent field lines. This mirror force driven dispersion can dominate over that associated with electron inertial effects for global scale <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15089478','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15089478"><span>Enhanced acceleration of injected electrons in a laser-beat-<span class="hlt">wave-induced</span> plasma channel.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C</p> <p>2004-03-05</p> <p>Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma <span class="hlt">wave</span> (RPW) is demonstrated. Using a CO2 laser beat <span class="hlt">wave</span> of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-<span class="hlt">induced</span> defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-<span class="hlt">wave-induced</span> plasma channel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20860365','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20860365"><span>Charging-delay <span class="hlt">induced</span> dust acoustic collisionless shock <span class="hlt">wave</span>: Roles of negative ions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.</p> <p>2006-11-15</p> <p>The effects of charging-delay and negative ions on nonlinear dust acoustic <span class="hlt">waves</span> are investigated. It has been found that the charging-delay <span class="hlt">induced</span> anomalous dissipation causes generation of dust acoustic collisionless shock <span class="hlt">waves</span> in an electronegative dusty plasma. The small but finite amplitude <span class="hlt">wave</span> is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay <span class="hlt">induced</span> dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA470402','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA470402"><span>Experimental Investigation of High-<span class="hlt">Pressure</span> Steam <span class="hlt">Induced</span> Stall of a Transonic Rotor</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2007-06-01</p> <p>engine, so the steam -<span class="hlt">induced</span> stall characteristic of its compressor must be well understood to help prevent any catastrophic failures of the aircraft...INVESTIGATION OF HIGH-<span class="hlt">PRESSURE</span> STEAM <span class="hlt">INDUCED</span> STALL OF A TRANSONIC ROTOR by Joesph J. Koessler June 2007 Thesis Advisor: Garth V. Hobson...2007 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Experimental Investigation of High-<span class="hlt">Pressure</span> Steam <span class="hlt">Induced</span> Stall of a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPCO4013C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPCO4013C"><span>Shock <span class="hlt">wave</span> equation of state experiments at multi-TPa <span class="hlt">pressures</span> on NIF</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Celliers, P. M.; Fratanduono, D. E.; Peterson, J. L.; Meezan, N. B.; MacKinnon, A. J.; Braun, D. G.; Millot, M.; Fry, J.; Boehm, K. J.; Sterne, P. A.; Collins, G. W.; Nikroo, A.; Fitzsimmons, P.</p> <p>2015-11-01</p> <p>The National Ignition Facility provides an unprecedented capability to generate steady, planar, ultra-high <span class="hlt">pressure</span> shock <span class="hlt">waves</span> (up to 10 TPa or more) in solid samples. Building on successful laser shock equation of state experiments performed on a variety of other laser facilities, we have designed and fielded experiments to perform impedance match experiments on samples of C, Be, SiO2 and CH, in the range of 3 to 7 TPa. The experiments use a line-imaging VISAR as the primary diagnostic to measure the shock velocity in an Al reference standard and in an array of the four samples. Initial tests with the line-imaging VISAR show that the NIF is capable of driving shocks that are steady to better than 2% in velocity for several ns, with smooth planar breakout patterns over a 2 mm diameter spot. Hugoniot data points will be compared to current equation-of-state models for the various materials under study. This work was performed under the auspices of the U.S. Department of Energy by LLNL under contract DE-AC52-07NA27344.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997APS..SHK..C304D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997APS..SHK..C304D"><span>Modeling of Megabar <span class="hlt">Pressure</span> <span class="hlt">Waves</span> Through Low Density Foams Filled with Liquid Deuterium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dahlburg, J. P.; Gardner, J. H.; Sethian, J. D.; Colombant, D.</p> <p>1997-07-01</p> <p>We have performed simulations of low density foam targets, evacuated or filled with liquid deuterium, that have been irradiated by the NRL Nike KrF laser at laser intensities from 5 × 10^13 to 1 × 10^14 W/cm^2. The simulations provide predictions for the resulting megabar <span class="hlt">pressure</span> <span class="hlt">waves</span> that are generated in these targets, target acceleration time histories, and the times that the shocks break out of the rear surface of the targets. Good agreement is obtained between the predicted break-out times and those measured from an experiment which will be described in a companion paper. Predictions for the Rayleigh-Taylor stability of these targets will also be shown. Our simulation tool, FAST2D, is a multidimensional hydrodynamics code with multigroup radiation transport. The code includes FCT advection, classical Spitzer-Harm electron thermal conduction, inverse bremsstrahlung laser deposition, a table look-up equation of state, and opacities supplied by the NRL-STA code.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSV...391..127M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSV...391..127M"><span>Acoustic model of micro-<span class="hlt">pressure</span> <span class="hlt">wave</span> emission from a high-speed train tunnel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miyachi, T.</p> <p>2017-03-01</p> <p>The micro-<span class="hlt">pressure</span> <span class="hlt">wave</span> (MPW) radiated from a tunnel portal can, if audible, cause serious problems around tunnel portals in high-speed railways. This has created a need to develop an acoustic model that considers the topography around a radiation portal in order to predict MPWs more accurately and allow for higher speed railways in the future. An acoustic model of MPWs based on linear acoustic theory is developed in this study. First, the directivity of sound sources and the acoustical effect of topography are investigated using a train launcher facility around a portal on infinitely flat ground and with an infinite vertical baffle plate. The validity of linear acoustic theory is then discussed through a comparison of numerical results obtained using the finite difference method (FDM) and experimental results. Finally, an acoustic model is derived that considers sound sources up to the second order and Green's function to represent the directivity and effect of topography, respectively. The results predicted by this acoustic model are shown to be in good agreement with both numerical and experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010HPR....30..555R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010HPR....30..555R"><span>High <span class="hlt">pressure-induced</span> structural effects in plastic packaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Richter, Tobias; Sterr, Julia; Jost, Verena; Langowski, Horst-Christian</p> <p>2010-12-01</p> <p>Today, flexible vacuum packages are predominantly used for products to be subjected to high <span class="hlt">pressure</span> treatment. However, tray packages with a modified atmosphere are in demand, which provide a high failure rate with respect to gas and water vapour permeability and packaging integrity. Methods to follow permeation processes under high <span class="hlt">pressure</span> were developed and used together with optical microscopy, confocal scanning laser microscopy, Raman spectroscopy and atomic force microscopy to identify the mechanisms for changes in permeability and damage to the packaging materials. Single film samples and pouch packages filled with model products were studied. Results indicate a reversible decrease in the coefficients of diffusion and permeation under the impact of high <span class="hlt">pressure</span>, due to the compression of the polymeric bulk. Irreversible changes in the polymeric materials are associated with gases in the packaging head space, which cause high local temperatures and create damage due to rapid deliberation upon the <span class="hlt">pressure</span> drop at the end of the high <span class="hlt">pressure</span> cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20951192','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20951192"><span><span class="hlt">Pressure-Induced</span> Structural Transformation in Radiation-Amorphized Zircon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Trachenko, Kostya; Dove, Martin T.; Salje, E. K. H.; Brazhkin, V. V.; Tsiok, O. B.</p> <p>2007-03-30</p> <p>We study the response of a radiation-amorphized material to high <span class="hlt">pressure</span>. We have used zircon ZrSiO{sub 4} amorphized by natural radiation over geologic times, and have measured its volume under high <span class="hlt">pressure</span>, using the precise strain-gauge technique. On <span class="hlt">pressure</span> increase, we observe apparent softening of the material, starting from 4 GPa. Using molecular dynamics simulation, we associate this softening with the amorphous-amorphous transformation accompanied by the increase of local coordination numbers. We observe permanent densification of the quenched sample and a nontrivial '<span class="hlt">pressure</span> window' at high temperature. These features point to a new class of amorphous materials that show a response to <span class="hlt">pressure</span> which is distinctly different from that of crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17501211','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17501211"><span><span class="hlt">Pressure-induced</span> structural transformation in radiation-amorphized zircon.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trachenko, Kostya; Brazhkin, V V; Tsiok, O B; Dove, Martin T; Salje, E K H</p> <p>2007-03-30</p> <p>We study the response of a radiation-amorphized material to high <span class="hlt">pressure</span>. We have used zircon ZrSiO4 amorphized by natural radiation over geologic times, and have measured its volume under high <span class="hlt">pressure</span>, using the precise strain-gauge technique. On <span class="hlt">pressure</span> increase, we observe apparent softening of the material, starting from 4 GPa. Using molecular dynamics simulation, we associate this softening with the amorphous-amorphous transformation accompanied by the increase of local coordination numbers. We observe permanent densification of the quenched sample and a nontrivial "<span class="hlt">pressure</span> window" at high temperature. These features point to a new class of amorphous materials that show a response to <span class="hlt">pressure</span> which is distinctly different from that of crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1334100','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1334100"><span>Effect of <span class="hlt">Pressure</span> Gradients on the Initiation of PBX-9502 via Irregular (Mach) Reflection of Low <span class="hlt">Pressure</span> Curved Shock <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hull, Lawrence Mark; Miller, Phillip Isaac; Moro, Erik Allan</p> <p>2016-11-28</p> <p>In the instance of multiple fragment impact on cased explosive, isolated curved shocks are generated in the explosive. These curved shocks propagate and may interact and form irregular or Mach reflections along the interaction loci, thereby producing a single shock that may be sufficient to initiate PBX-9501. However, the incident shocks are divergent and their intensity generally decreases as they expand, and the regions behind the Mach stem interaction loci are generally unsupported and allow release <span class="hlt">waves</span> to rapidly affect the flow. The effects of release <span class="hlt">waves</span> and divergent shocks may be considered theoretically through a “Shock Change Equation”.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1592..341C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1592..341C"><span>Investigation on the generation characteristic of <span class="hlt">pressure</span> pulse <span class="hlt">wave</span> signal during the measurement-while-drilling process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Changqing, Zhao; Kai, Liu; Tong, Zhao; Takei, Masahiro; Weian, Ren</p> <p>2014-04-01</p> <p>The mud-pulse logging instrument is an advanced measurement-while-drilling (MWD) tool and widely used by the industry in the world. In order to improve the signal transmission rate, ensure the accurate transmission of information and address the issue of the weak signal on the ground of oil and gas wells, the signal generator should send out the strong mud-pulse signals with the maximum amplitude. With the rotary valve pulse generator as the study object, the three-dimensional Reynolds NS equations and standard k - ɛ turbulent model were used as a mathematical model. The speed and <span class="hlt">pressure</span> coupling calculation was done by simple algorithms to get the amplitudes of different rates of flow and axial clearances. Tests were done to verify the characteristics of the <span class="hlt">pressure</span> signals. The <span class="hlt">pressure</span> signal was captured by the standpiece <span class="hlt">pressure</span> monitoring system. The study showed that the axial clearances grew bigger as the <span class="hlt">pressure</span> <span class="hlt">wave</span> amplitude value decreased and caused the weakening of the pulse signal. As the rate of flow got larger, the <span class="hlt">pressure</span> <span class="hlt">wave</span> amplitude would increase and the signal would be enhanced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26611813','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26611813"><span>Numerical simulation of the nonlinear ultrasonic <span class="hlt">pressure</span> <span class="hlt">wave</span> propagation in a cavitating bubbly liquid inside a sonochemical reactor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dogan, Hakan; Popov, Viktor</p> <p>2016-05-01</p> <p>We investigate the acoustic <span class="hlt">wave</span> propagation in bubbly liquid inside a pilot sonochemical reactor which aims to produce antibacterial medical textile fabrics by coating the textile with ZnO or CuO nanoparticles. Computational models on acoustic propagation are developed in order to aid the design procedures. The acoustic <span class="hlt">pressure</span> <span class="hlt">wave</span> propagation in the sonoreactor is simulated by solving the Helmholtz equation using a meshless numerical method. The paper implements both the state-of-the-art linear model and a nonlinear <span class="hlt">wave</span> propagation model recently introduced by Louisnard (2012), and presents a novel iterative solution procedure for the nonlinear propagation model which can be implemented using any numerical method and/or programming tool. Comparative results regarding both the linear and the nonlinear <span class="hlt">wave</span> propagation are shown. Effects of bubble size distribution and bubble volume fraction on the acoustic <span class="hlt">wave</span> propagation are discussed in detail. The simulations demonstrate that the nonlinear model successfully captures the realistic spatial distribution of the cavitation zones and the associated acoustic <span class="hlt">pressure</span> amplitudes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830044941&hterms=base+flow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dbase%2Bflow','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830044941&hterms=base+flow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dbase%2Bflow"><span>Evolution of shock-<span class="hlt">induced</span> <span class="hlt">pressure</span> on a flat-face/flat-base body and afterbody flow separation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yoshikawa, K. K.; Wray, A. A.</p> <p>1982-01-01</p> <p>The time-dependent, compressible Reynolds-averaged, Navier-Stokes equations are applied to solve an axisymmetric supersonic flow around a flat-face/flat-base body with and without a sting support. Important transient phenomena, not yet well understood, are investigated, and the significance of the present solution to the phenomena is discussed. The phenomena, described in detail, are as follows: the transient formation of the bow and recompression shock <span class="hlt">waves</span>; the evolution of a <span class="hlt">pressure</span> buildup due to diffraction of the incident shock <span class="hlt">wave</span> in the forebody and afterbody regions, including the luminosity accompanying the <span class="hlt">pressure</span> buildup; the separation of the flow as influenced by <span class="hlt">pressure</span> buildup; the location of the separation and the reattachment points; and the transient period of the shock-<span class="hlt">induced</span> base flow. The important influence of the nonsteady (transient) and steady flow on the aerodynamic characteristics, radiative heat transfer, and, thus, on the survivability or safeguard problems for an aircraft fuselage, missile, or planetary entry probe at very high flight speeds is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1719c0052A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1719c0052A"><span>The use of laser-<span class="hlt">induced</span> shock <span class="hlt">wave</span> plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abdulmadjid, Syahrun Nur; Lahna, Kurnia; Desiyana, Lydia Septa</p> <p>2016-03-01</p> <p>An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma <span class="hlt">induced</span> by Nd-YAG laser at a low <span class="hlt">pressure</span> of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-<span class="hlt">Induced</span> Shock <span class="hlt">Wave</span> Plasma Spectroscopy (LISPS), the shock <span class="hlt">wave</span> has a significant role in <span class="hlt">inducing</span> atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablated atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-<span class="hlt">induced</span> plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26ES...55a2048H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26ES...55a2048H"><span><span class="hlt">Waves</span> <span class="hlt">Induce</span> Sediment Transport at Coastal Region of Timbulsloko Demak</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hawati, Purnomo; Nugroho Sugianto, Denny; Anggoro, Sutrisno; Wirasatriya, Anindya; Widada, Sugeng</p> <p>2017-02-01</p> <p><span class="hlt">Waves</span> have variation of length and period. This influenced by seasonal variation. Impacts of seasonal variation related to <span class="hlt">wave</span> is playing important roles in sediment transport mechanism and coastal changes. This condition not only treats coastal area but also decreases economic capacity of community. This research aim to determine different seasonal based on Indonesia Northwest-Northeast monsoon and Southeast-Southwest monsoon and theirs relation to sediment transport. Area of study is suffered by 938.73 H of abrasion. Conducted by CERC methods, transforming BMKG Ahmad Yani wind database (2005-2015) into wave’s data of seasonal variation and using field measurement recorded by ADCP. Definitely, maximum speed of wind is reached at 23 knots from December to February, wind direction predominantly from North West direction. Range of significant <span class="hlt">Wave</span> Height (Hs) all season is 24.66-30.32 cm and Significant <span class="hlt">Wave</span> period (Ts) count at 3.64-3.78 sec. Net of sediment volume annual 72,353.40 m3year-1 and sediment movement pattern is forwarding from west to east direction. Correlation between breaking <span class="hlt">waves</span> and sediment transport is linier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22311311','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22311311"><span>Rotation-<span class="hlt">induced</span> nonlinear wavepackets in internal <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Whitfield, A. J. Johnson, E. R.</p> <p>2014-05-15</p> <p>The long time effect of weak rotation on an internal solitary <span class="hlt">wave</span> is the decay into inertia-gravity <span class="hlt">waves</span> and the eventual formation of a localised wavepacket. Here this initial value problem is considered within the context of the Ostrovsky, or the rotation-modified Korteweg-de Vries (KdV), equation and a numerical method for obtaining accurate wavepacket solutions is presented. The flow evolutions are described in the regimes of relatively-strong and relatively-weak rotational effects. When rotational effects are relatively strong a second-order soliton solution of the nonlinear Schrödinger equation accurately predicts the shape, and phase and group velocities of the numerically determined wavepackets. It is suggested that these solitons may form from a local Benjamin-Feir instability in the inertia-gravity <span class="hlt">wave</span>-train radiated when a KdV solitary <span class="hlt">wave</span> rapidly adjusts to the presence of strong rotation. When rotational effects are relatively weak the initial KdV solitary <span class="hlt">wave</span> remains coherent longer, decaying only slowly due to weak radiation and modulational instability is no longer relevant. Wavepacket solutions in this regime appear to consist of a modulated KdV soliton wavetrain propagating on a slowly varying background of finite extent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhFl...26e6606W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhFl...26e6606W"><span>Rotation-<span class="hlt">induced</span> nonlinear wavepackets in internal <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Whitfield, A. J.; Johnson, E. R.</p> <p>2014-05-01</p> <p>The long time effect of weak rotation on an internal solitary <span class="hlt">wave</span> is the decay into inertia-gravity <span class="hlt">waves</span> and the eventual formation of a localised wavepacket. Here this initial value problem is considered within the context of the Ostrovsky, or the rotation-modified Korteweg-de Vries (KdV), equation and a numerical method for obtaining accurate wavepacket solutions is presented. The flow evolutions are described in the regimes of relatively-strong and relatively-weak rotational effects. When rotational effects are relatively strong a second-order soliton solution of the nonlinear Schrödinger equation accurately predicts the shape, and phase and group velocities of the numerically determined wavepackets. It is suggested that these solitons may form from a local Benjamin-Feir instability in the inertia-gravity <span class="hlt">wave</span>-train radiated when a KdV solitary <span class="hlt">wave</span> rapidly adjusts to the presence of strong rotation. When rotational effects are relatively weak the initial KdV solitary <span class="hlt">wave</span> remains coherent longer, decaying only slowly due to weak radiation and modulational instability is no longer relevant. Wavepacket solutions in this regime appear to consist of a modulated KdV soliton wavetrain propagating on a slowly varying background of finite extent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT........58R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT........58R"><span><span class="hlt">Pressure-induced</span> phase transitions of indium selenide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rasmussen, Anya Marie</p> <p></p> <p>In2Se3 has potential as a phase-change material for memory applications. Understanding its phase diagram is important to achieve controlled switching between phases. <span class="hlt">Pressure</span>-dependent phase transitions of In2Se3 bulk powders and nanowire samples were studied at room temperature and at elevated temperatures using synchrotron x-ray diffraction and diamond-anvil cells (DACs). alpha-In2Se3 transforms into the beta phase at 0.7 GPa, an order of magnitude lower than phase-transition critical <span class="hlt">pressures</span> in typical semiconductors. The bulk moduli are reported and the c/a ratio for the beta phase is shown to have a highly nonlinear dependence on <span class="hlt">pressure</span>. gamma-In2Se3, metastable under ambient conditions, transforms into to the high-<span class="hlt">pressure</span> beta phase between 2.8 GPa and 3.2 GPa in bulk powder samples and at slightly higher <span class="hlt">pressures</span>, between 3.2 GPa and 3.7 GPa in nanowire samples. While the gamma phase bulk modulus is similar to that of the beta phase, the decrease due to <span class="hlt">pressure</span> in the unit cell parameter ratio, c/a, is less than half the decrease seen in the beta phase. Using high-temperature DACs, we investigated how elevated temperatures and <span class="hlt">pressures</span> affect the crystal structure of In 2Se3. From these measurements, the high-<span class="hlt">pressure</span> beta phase was found to be metastable. The high-<span class="hlt">pressure</span> beta phase transitions into the high-temperature beta phase at temperatures above 380 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880020703&hterms=moreau&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmoreau','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880020703&hterms=moreau&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmoreau"><span>Determination of the specific area of liquid gas and the velocity of weak <span class="hlt">pressure</span> <span class="hlt">waves</span> in aqueous foams</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Saint-Cloud, Jean; Guerraud, Claude; Moreau, Michel; Manson, Numa</p> <p>1988-01-01</p> <p>The specific area of an aqueous foam contained in a tube is obtained by determining the fraction of the quantity of light emitted by a source and diffused by the specific area of the column of the foam. The velocity of the <span class="hlt">waves</span> of weak <span class="hlt">pressure</span> (which propagate in the air with the velocity of sound) is measured by noticing the moment when the <span class="hlt">wave</span> penetrates the column and the moment when, having reached the opposite side, it determines a variation of the light diffused by the area of the latter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRB..11610101G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRB..11610101G"><span>Anatomy of a <span class="hlt">pressure-induced</span>, ferromagnetic-to-paramagnetic transition in pyrrhotite: Implications for the formation <span class="hlt">pressure</span> of diamonds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gilder, Stuart A.; Egli, Ramon; Hochleitner, Rupert; Roud, Sophie C.; Volk, Michael W. R.; Le Goff, Maxime; de Wit, Maarten</p> <p>2011-10-01</p> <p>Meteorites and diamonds encounter high <span class="hlt">pressures</span> during their formation or subsequent evolution. These materials commonly contain magnetic inclusions of pyrrhotite. Because magnetic properties are sensitive to strain, pyrrhotite can potentially record the shock or formation <span class="hlt">pressures</span> of its host. Moreover, pyrrhotite undergoes a <span class="hlt">pressure-induced</span> phase transition between 1.6 and 6.2 GPa, but the magnetic signature of this transition is poorly known. Here we report room temperature magnetic measurements on multidomain and single-domain pyrrhotite under nonhydrostatic <span class="hlt">pressure</span>. Magnetic remanence in single-domain pyrrhotite is largely insensitive to <span class="hlt">pressure</span> until 2 GPa, whereas the remanence of multidomain pyrrhotite increases 50% over that of initial conditions by 2 GPa, and then decreases until only 33% of the original remanence remains by 4.5 GPa. In contrast, magnetic coercivity increases with increasing <span class="hlt">pressure</span> to 4.5 GPa. Below ˜1.5 GPa, multidomain pyrrhotite obeys Néel theory with a positive correlation between coercivity and remanence; above ˜1.5 GPa, it behaves single domain-like yet distinctly different from uncompressed single-domain pyrrhotite. The ratio of magnetic coercivity and remanence follows a logarithmic law with respect to <span class="hlt">pressure</span>, which can potentially be used as a geobarometer. Owing to the greater thermal expansion of pyrrhotite with respect to diamond, pyrrhotite inclusions in diamonds experience a confining <span class="hlt">pressure</span> at Earth's surface. Applying our experimentally derived magnetic geobarometer to pyrrhotite-bearing diamonds from Botswana and the Central African Republic suggests the <span class="hlt">pressures</span> of the pyrrhotite inclusions in the diamonds range from 1.3 to 2.1 GPa. These overpressures constrain the mantle source <span class="hlt">pressures</span> from 5.4 to 9.5 GPa, depending on which bulk modulus and thermal expansion coefficients of the two phases are used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25770242','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25770242"><span><span class="hlt">Pressure</span> dependency of aortic pulse <span class="hlt">wave</span> velocity in vivo is not affected by vasoactive substances that alter aortic wall tension ex vivo.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Butlin, Mark; Lindesay, George; Viegas, Kayla D; Avolio, Alberto P</p> <p>2015-05-15</p> <p>Aortic stiffness, a predictive parameter in cardiovascular medicine, is blood <span class="hlt">pressure</span> dependent and experimentally requires isobaric measurement for meaningful comparison. Vasoactive drug administration to change peripheral resistance and blood <span class="hlt">pressure</span> allows such isobaric comparison but may alter large conduit artery wall tension, directly changing aortic stiffness. This study quantifies effects of sodium nitroprusside (SNP, vasodilator) and phenylephrine (PE, vasoconstrictor) on aortic stiffness measured by aortic pulse <span class="hlt">wave</span> velocity (aPWV) assessed by invasive <span class="hlt">pressure</span> catheterization in anaesthetized Sprague-Dawley rats (n = 7). This was compared with nondrug-dependent alteration of blood <span class="hlt">pressure</span> through reduced venous return <span class="hlt">induced</span> by partial vena cava occlusion. In vivo drug concentration was estimated by modeling clearance rates. Ex vivo responses of excised thoracic and abdominal aortic rings to drugs was measured using myography. SNP administration did not alter aPWV compared with venous occlusion (P = 0.21-0.87). There was a 5% difference in aPWV with PE administration compared with venous occlusion (P < 0.05). The estimated in vivo maximum concentration of PE (7.0 ± 1.8 ×10(-7) M) and SNP (4.2 ± 0.6 ×10(-7) M) caused ex vivo equivalent contraction of 52 mmHg (thoracic) and 112 mmHg (abdominal) and relaxation of 96% (both abdominal and thoracic), respectively, despite having a negligible effect on aPWV in vivo. This study demonstrates that vasoactive drugs administered to alter systemic blood <span class="hlt">pressure</span> have a negligible effect on aPWV and provide a useful tool to study <span class="hlt">pressure</span>-normalized and <span class="hlt">pressure</span>-dependent aPWV in large conduit arteries in vivo. However, similar drug concentrations affect aortic ring wall tension ex vivo. Future studies investigating in vivo and ex vivo kinetics will need to elucidate mechanisms for this marked difference.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22306310','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22306310"><span><span class="hlt">Pressure-induced</span> amorphization of La{sub 1/3}TaO{sub 3}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Noked, O.; Melchior, A.; Shuker, R.; Livneh, T.; Steininger, R.; Kennedy, B.J.; Sterer, E.</p> <p>2013-06-15</p> <p>La{sub 1/3}TaO{sub 3}, an A-site cation deficient perovskite, has been studied under <span class="hlt">pressure</span> by synchrotron X-ray powder diffraction and Raman spectroscopy. It undergoes irreversible <span class="hlt">pressure</span> <span class="hlt">induced</span> amorphization at P=18.5 GPa. An almost linear unit cell volume decrease vs. <span class="hlt">pressure</span> is observed from ambient <span class="hlt">pressure</span> up to the phase transition. The Raman spectroscopy also shows amorphization at the same <span class="hlt">pressure</span>, with positive shifts of all modes as a function of <span class="hlt">pressure</span>. The <span class="hlt">pressure</span> dependence of the E{sub g} and A{sub 1g} Raman modes arising from the octahedral oxygen network is discussed. - Graphical abstract: La{sub 1/3}Tao{sub 3} exhibits linear pressure–volume relation until irreversible <span class="hlt">pressure</span> <span class="hlt">induced</span> amorphization at 18.5 Gpa. - Highlights: • La{sub 1/3}TaO{sub 3} has been studied under <span class="hlt">pressure</span> by synchrotron XRD and Raman spectroscopy. • La{sub 1/3}TaO{sub 3} undergoes irreversible <span class="hlt">pressure</span> <span class="hlt">induced</span> amorphization around 18.5 GPa. • The transition is manifested in both XRD and Raman measurements. • A linear P–V relation is observed from ambient <span class="hlt">pressure</span> up to the phase transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22218497','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22218497"><span>On plasma rotation <span class="hlt">induced</span> by <span class="hlt">waves</span> in tokamaks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guan, Xiaoyin; Dodin, I. Y.; Fisch, N. J.; Qin, Hong; Liu, Jian</p> <p>2013-10-15</p> <p>The momentum conservation for resonant <span class="hlt">wave</span>-particle interactions, now proven rigorously and for general settings, is applied to explain in simple terms how tokamak plasma is spun up by the <span class="hlt">wave</span> momentum perpendicular to the dc magnetic field. The perpendicular momentum is passed through resonant particles to the dc field and, giving rise to the radial electric field, is accumulated as a Poynting flux; the bulk plasma is then accelerated up to the electric drift velocity proportional to that flux, independently of collisions. The presence of this collisionless acceleration mechanism permits varying the ratio of the average kinetic momentum absorbed by the resonant-particle and bulk distributions depending on the orientation of the <span class="hlt">wave</span> vector. Both toroidal and poloidal forces are calculated, and a fluid model is presented that yields the plasma velocity at equilibrium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGP42A..08G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGP42A..08G"><span>A <span class="hlt">pressure-induced</span>, magnetic transition in pyrrhotite: Implications for the formation <span class="hlt">pressure</span> of meteorites and diamonds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gilder, S. A.; Egli, R.; Hochleitner, R.; Roud, S. C.; Volk, M.; Le Goff, M.; de Wit, M.</p> <p>2010-12-01</p> <p>Meteorites and diamonds encounter high-<span class="hlt">pressures</span> during their geologic histories. These materials commonly contain magnetic inclusions of pyrrhotite, and because magnetic properties are sensitive to strain, pyrrhotite can potentially record the shock or formation <span class="hlt">pressures</span> of its host. Moreover, pyrrhotite undergoes a <span class="hlt">pressure-induced</span> phase transition between 1.6 and 6.2 GPa, but the magnetic signature of this transition is poorly known. Here we report magnetic measurements performed at high-<span class="hlt">pressures</span> on single and multi-domain pyrrhotite. A magnetic hysteresis model based on our observations suggests that multidomain pyrrhotite transforms into single domain-like material, and once in the single domain state, hysteresis loops become progressively squarer and then squatter with increasing <span class="hlt">pressure</span>, until they ultimately collapse approaching the paramagnetic state at the transition. The ratio of the bulk magnetic coercive force to magnetic remanence for pure pyrrhotite is reversible with <span class="hlt">pressure</span> and follows a logarithmic law as a function of <span class="hlt">pressure</span>, which can be used as a magnetic barometer for natural systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22490850','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22490850"><span><span class="hlt">Pressure-induced</span> reversible phase transition in thiourea dioxide crystal</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, Qinglei; Yan, Tingting; Zhu, Hongyang; Cui, Qiliang; Zou, Bo E-mail: zoubo@jlu.edu.cn; Wang, Kai E-mail: zoubo@jlu.edu.cn</p> <p>2015-06-28</p> <p>The effect of high <span class="hlt">pressure</span> on the crystal structure of thiourea dioxide has been investigated by Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell up to 10.3 GPa. The marked changes in the Raman spectra at 3.7 GPa strongly indicated a structural phase transition associated with the distortions of hydrogen bonding. There were no further changes up to the maximum <span class="hlt">pressure</span> of 10.3 GPa and the observed transition was completely reversible when the system was brought back to ambient <span class="hlt">pressure</span>. This transition was further confirmed by the changes of ADXRD spectra. The high-<span class="hlt">pressure</span> phase was indexed and refined to an orthorhombic structure with a possible space group Pbam. The results from the first-principles calculations suggested that this phase transition was mainly related to the changes of hydrogen-bonded networks in thiourea dioxide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18764423','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18764423"><span><span class="hlt">Pressure</span> <span class="hlt">induced</span> superconductivity in CaFe2As2.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Torikachvili, Milton S; Bud'ko, Sergey L; Ni, Ni; Canfield, Paul C</p> <p>2008-08-01</p> <p>CaFe2As2 has been found to be exceptionally sensitive to the application of hydrostatic <span class="hlt">pressure</span> and can be tuned to reveal all the salient features associated with FeAs superconductivity without introducing any disorder. The ambient <span class="hlt">pressure</span>, 170 K, structural/magnetic, first-order phase transition is suppressed to 128 K by 3.5 kbar. At 5.5 kbar a new transition is detected at 104 K, increasing to above 300 K by 19 kbar. A low temperature, superconducting dome (T(c) approximately 12 K) is centered around 5 kbar, extending down to 2.3 kbar and up to 8.6 kbar. This superconducting phase appears to exist when the low <span class="hlt">pressure</span> transition is suppressed sufficiently, but before the high <span class="hlt">pressure</span> transition has reduced the resistivity too dramatically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/941082','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/941082"><span><span class="hlt">Pressure</span> <span class="hlt">Induced</span> Superconductivity in CaFe2As2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Milton S. Torikachvili; Sergey L. Bud'ko; Ni Ni; Paul Canfield</p> <p>2008-08-01</p> <p>CaFe{sub 2}As{sub 2} has been found to be exceptionally sensitive to the application of hydrostatic <span class="hlt">pressure</span> and can be tuned to reveal all the salient features associated with FeAs superconductivity without introducing any disorder. The ambient <span class="hlt">pressure</span>, 170 K, structural/magnetic, first-order phase transition is suppressed to 128 K by 3.5 kbar. At 5.5 kbar a new transition is detected at 104 K, increasing to above 300 K by 19 kbar. A low temperature, superconducting dome (T{sub c} {approx} 12 K) is centered around 5 kbar, extending down to 2.3 kbar and up to 8.6 kbar. This superconducting phase appears to exist when the low <span class="hlt">pressure</span> transition is suppressed sufficiently, but before the high <span class="hlt">pressure</span> transition has reduced the resistivity too dramatically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11537424','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11537424"><span>Circulatory filling <span class="hlt">pressures</span> during transient microgravity <span class="hlt">induced</span> by parabolic flight.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Latham, R D; Fanton, J W; White, C D; Vernalis, M N; Crisman, R P; Koenig, S C</p> <p>1993-01-01</p> <p>Theoretical concepts hold that blood in the gravity-dependent portion of the body would relocate to more cephalad compartments under microgravity conditions. The result is an increase in blood volume in the thoracic and cardiac chambers. This increase in central volume shift should result in an increase in central atrial filling <span class="hlt">pressures</span>. However, experimental data has been somewhat contradictory and nonconclusive to date. Early investigations of peripheral venous <span class="hlt">pressure</span> and estimates of central venous <span class="hlt">pressure</span> (CVP) from these data did not show an increase in CVP in the microgravity condition. However, CVP recorded in human volunteers during the parabolic flight by Norsk revealed an increase in CVP during the microgravity state. On the June 1991 STS 40 shuttle mission, a payload specialist wore a fluid line that recorded CVP during the first few hours of orbital insertion. These data revealed decreased CVP. When this CVP catheter was tested during parabolic flight in four subjects, two subjects had increased CVP recordings and two other subjects had decreased CVP measurements. In April 1991, our laboratory performed parabolic flight studies in several chronic-instrumented baboon subjects. It was again noted that centrally recorded right atrial <span class="hlt">pressure</span> varied with exposure to microgravity, some animals having an increase and others having a decrease. Thus, data presently available has demonstrated a variable response in the mechanism not clearly defined. In April 1992, we determined a test hypothesis relating the possible mechanism of these variable <span class="hlt">pressure</span> responses to venous <span class="hlt">pressure</span>-volume relationships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JASTP.103..169P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JASTP.103..169P"><span>Whistler <span class="hlt">wave-induced</span> ionospheric plasma turbulence: Source mechanisms and remote sensing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pradipta, R.; Rooker, L. A.; Whitehurst, L. N.; Lee, M. C.; Ross, L. M.; Sulzer, M. P.; Gonzalez, S.; Tepley, C.; Aponte, N.; See, B. Z.; Hu, K. P.</p> <p>2013-10-01</p> <p>We report a series of experiments conducted at Arecibo Observatory in the past, aimed at the investigation of 40.75 kHz whistler <span class="hlt">wave</span> interactions with ionospheric plasmas and the inner radiation belts at L=1.35. The whistler <span class="hlt">waves</span> are launched from a Naval transmitter (code-named NAU) operating in Aguadilla, Puerto Rico at the frequency and power of 40.75 kHz and 100 kW, respectively. Arecibo radar, CADI, and optical instruments were used to monitor the background ionospheric conditions and detect the <span class="hlt">induced</span> ionospheric plasma effects. Four-<span class="hlt">wave</span> interaction processes produced by whistler <span class="hlt">waves</span> in the ionosphere can excite lower hybrid <span class="hlt">waves</span>, which can accelerate ionospheric electrons. Furthermore, whistler <span class="hlt">waves</span> propagating into the magnetosphere can trigger precipitation of energetic electrons from the radiation belts. Radar and optical measurements can distinguish <span class="hlt">wave-wave</span> and <span class="hlt">wave</span>-particle interaction processes occurring at different altitudes. Electron acceleration by different mechanisms can be verified from the radar measurements of plasma lines. To facilitate the coupling of NAU-launched 40.75 kHz whistler <span class="hlt">waves</span> into the ionosphere, we can rely on naturally occurring spread F irregularities to serve as ionospheric ducts. We can also use HF <span class="hlt">wave</span>-created ducts/artificial waveguides, as demonstrated in our earlier Arecibo experiments and recent Gakona experiments at HAARP. The newly constructed Arecibo HF heater will be employed in our future experiments, which can extend the study of whistler <span class="hlt">wave</span> interactions with the ionosphere and the magnetosphere/radiation belts as well as the whistler <span class="hlt">wave</span> conjugate propagation between Arecibo and Puerto Madryn, Argentina.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996SurSc.347..355M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SurSc.347..355M"><span>Control of the shape of chemical <span class="hlt">wave</span> patterns in the NO + H 2 reaction on Rh(110) by adsorbate-<span class="hlt">induced</span> reconstructions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mertens, F.; Imbihl, R.</p> <p>1996-02-01</p> <p>The NO + H 2 reaction on Rh(110) has been investigated between 480 and 650 K under isothermal low-<span class="hlt">pressure</span> conditions at 10 -6 and 10 -5 mbar. Photoemission electron microscopy (PEEM) was used as a spatially resolving method. Depending on the experimental parameters, a variety of different chemical <span class="hlt">wave</span> patterns such as elliptically and rectangularly shaped target patterns or travelling <span class="hlt">wave</span> fragments were found. The existence range of these patterns has been mapped out in the pH 2, T-parameter range for fixed pNO=1.6×10 -6 mbar. In low energy electron diffraction (LEED) a number of different nitrogen and oxygen <span class="hlt">induced</span> reconstructions was observed in the pattern-forming parameter range. The variations in the shape of the <span class="hlt">wave</span> patterns were traced to the presence of adsorbate-<span class="hlt">induced</span> reconstructions with different anisotropy caused by atomic oxygen and atomic nitrogen, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25515673','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25515673"><span><span class="hlt">Pressure-induced</span> metathesis reaction to sequester Cs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Im, Junhyuck; Seoung, Donghoon; Lee, Seung Yeop; Blom, Douglas A; Vogt, Thomas; Kao, Chi-Chang; Lee, Yongjae</p> <p>2015-01-06</p> <p>We report here a <span class="hlt">pressure</span>-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80·16H2O, Ag-NAT) is <span class="hlt">pressurized</span> in an aqueous CsI solution, resulting in the exchange of Ag(+) by Cs(+) in the natrolite framework forming Cs16Al16Si24O80·16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-<span class="hlt">pressure</span> polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional <span class="hlt">pressure</span> and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after <span class="hlt">pressure</span> release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the <span class="hlt">pressure</span>-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate <span class="hlt">pressures</span> and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6·H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic (137)Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.G51A0940B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.G51A0940B"><span>A Mechanism for Seismically <span class="hlt">Induced</span> Pore <span class="hlt">Pressure</span> Changes Inferred from High Frequency Water Well Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.</p> <p>2002-12-01</p> <p>Earthquakes can produce water level changes in certain distant wells orders of magnitude larger than can be explained by static stress changes. The redistribution of pore <span class="hlt">pressure</span> can generate crustal deformation and perhaps even trigger seismicity. Some studies suggest that earthquakes <span class="hlt">induce</span> permeability increases or other aquifer property changes. Standard hydrogeological methods do not continuously measure aquifer properties therefore it is difficult to monitor the inferred variations. We developed a new method to measure aquifer properties over short times by combining high-sample rate water level data (1 sps) and seismic data for a site near Grants Pass Oregon. The new method motivates a new model in which the seismic <span class="hlt">waves</span> remove transient barriers of sediment in a fracture. Pumping test data for the site is well-modeled by a single, infinitesimally thin square planar fracture embedded in a unbounded, homogeneous and isotropic confined aquifer. For this geometry, the amplification factor χ, defined as the ratio of the water level amplitude to the ground velocity, as a function of frequency f is \\[ χ = A(\</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/381051','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/381051"><span><span class="hlt">Pressure</span> <span class="hlt">waves</span> in liquid mercury target from pulsed heat loads and the possible way controlling their effects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ni, L.; Skala, K.</p> <p>1996-06-01</p> <p>In ESS project liquid metals are selected as the main target for the pulsed spallation neutron source. Since the very high instantaneous energy is deposited on the heavy molten target in a very short period time, <span class="hlt">pressure</span> <span class="hlt">waves</span> are generated. They travel through the liquid and cause high stress in the container. Also, additional stress should be considered in the wall which is the result of direct heating of the target window. These dynamic processes were simulated with computational codes with the static response being analized first. The total resulting dynamic wall stress has been found to have exceeded the design stress for the selected container material. Adding a small amount of gas bubbles in the liquid could be a possible way to reduce the <span class="hlt">pressure</span> <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1043806','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1043806"><span>The AC-Stark Effect in Nitric Oxide <span class="hlt">Induced</span> by Rapidly Swept Continuous <span class="hlt">Wave</span> Quantum Cascade Lasers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Duxbury, Geoffrey; Kelly, James F.; Blake, Thomas A.; Langford, Nigel</p> <p>2012-05-07</p> <p>A large AC Stark effect has been observed when nitric oxide, at low <span class="hlt">pressure</span> in a long optical path (100 m) Herriot cell, is subjected to infrared radiation from a rapidly swept, continuous <span class="hlt">wave</span> infrared quantum cascade laser. As the frequency sweep rate of the laser is increased, an emission signal <span class="hlt">induced</span> by rapid passage, occurs after the laser frequency has passed through the resonance of a molecular absorption line. At very high sweep rates a laser field-<span class="hlt">induced</span> splitting of the absorptive part of the signal is observed, due to the AC Stark effect. This splitting is related to the Autler-Townes mixing of the hyperfine transitions, which lie within the lambda doublet components of the transition, under the Doppler broadened envelope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20631428','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20631428"><span><span class="hlt">Pressure-induced</span> phase transitions in L-alanine, revisited.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tumanov, N A; Boldyreva, E V; Kolesov, B A; Kurnosov, A V; Quesada Cabrera, R</p> <p>2010-08-01</p> <p>The effect of <span class="hlt">pressure</span> on L-alanine has been studied by X-ray powder diffraction (up to 12.3 GPa), single-crystal X-ray diffraction, Raman spectroscopy and optical microscopy (up to approximately 6 GPa). No structural phase transitions have been observed. At approximately 2 GPa the cell parameters a and b become accidentally equal to each other, but without a change in space-group symmetry. Neither of two transitions reported by others (to a tetragonal phase at approximately 2 GPa and to a monoclinic phase at approximately 9 GPa) was observed. The changes in cell parameters were continuous up to the highest measured <span class="hlt">pressures</span> and the cells remained orthorhombic. Some important changes in the intermolecular interactions occur, which also manifest themselves in the Raman spectra. Two new orthorhombic phases could be crystallized from a MeOH/EtOH/H(2)O <span class="hlt">pressure</span>-transmitting mixture in the <span class="hlt">pressure</span> range 0.8-4.7 GPa, but only if the sample was kept at these <span class="hlt">pressures</span> for at least 1-2 d. The new phases converted back to L-alanine on decompression. Judging from the Raman spectra and cell parameters, the new phases are most probably not L-alanine but its solvates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH43A..03W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH43A..03W"><span>Turbulent Heating and <span class="hlt">Wave</span> <span class="hlt">Pressure</span> in Solar Wind Acceleration Modeling: New Insights to Empirical Forecasting of the Solar Wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woolsey, L. N.; Cranmer, S. R.</p> <p>2013-12-01</p> <p>The study of solar wind acceleration has made several important advances recently due to improvements in modeling techniques. Existing code and simulations test the competing theories for coronal heating, which include reconnection/loop-opening (RLO) models and <span class="hlt">wave</span>/turbulence-driven (WTD) models. In order to compare and contrast the validity of these theories, we need flexible tools that predict the emergent solar wind properties from a wide range of coronal magnetic field structures such as coronal holes, pseudostreamers, and helmet streamers. ZEPHYR (Cranmer et al. 2007) is a one-dimensional magnetohydrodynamics code that includes Alfven <span class="hlt">wave</span> generation and reflection and the resulting turbulent heating to accelerate solar wind in open flux tubes. We present the ZEPHYR output for a wide range of magnetic field geometries to show the effect of the magnetic field profiles on wind properties. We also investigate the competing acceleration mechanisms found in ZEPHYR to determine the relative importance of increased gas <span class="hlt">pressure</span> from turbulent heating and the separate <span class="hlt">pressure</span> source from the Alfven <span class="hlt">waves</span>. To do so, we developed a code that will become publicly available for solar wind prediction. This code, TEMPEST, provides an outflow solution based on only one input: the magnetic field strength as a function of height above the photosphere. It uses correlations found in ZEPHYR between the magnetic field strength at the source surface and the temperature profile of the outflow solution to compute the wind speed profile based on the increased gas <span class="hlt">pressure</span> from turbulent heating. With this initial solution, TEMPEST then adds in the Alfven <span class="hlt">wave</span> <span class="hlt">pressure</span> term to the modified Parker equation and iterates to find a stable solution for the wind speed. This code, therefore, can make predictions of the wind speeds that will be observed at 1 AU based on extrapolations from magnetogram data, providing a useful tool for empirical forecasting of the sol! ar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25798749','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25798749"><span>Field-<span class="hlt">induced</span> density <span class="hlt">wave</span> in the heavy-fermion compound CeRhIn₅.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moll, Philip J W; Zeng, Bin; Balicas, Luis; Galeski, Stanislaw; Balakirev, Fedor F; Bauer, Eric D; Ronning, Filip</p> <p>2015-03-23</p> <p>Strong electron correlations lead to a variety of distinct ground states, such as magnetism, charge order or superconductivity. Understanding the competitive or cooperative interplay between neighbouring phases is an outstanding challenge in physics. CeRhIn₅ is a prototypical example of a heavy-fermion superconductor: it orders anti-ferromagnetically below 3.8 K, and moderate hydrostatic <span class="hlt">pressure</span> suppresses the anti-ferromagnetic order <span class="hlt">inducing</span> unconventional superconductivity. Here we show evidence for a phase transition to a state akin to a density <span class="hlt">wave</span> (DW) under high magnetic fields (>27 T) in high-quality single crystal microstructures of CeRhIn₅. The DW is signalled by a hysteretic anomaly in the in-plane resistivity accompanied by non-linear electrical transport, yet remarkably thermodynamic measurements suggest that the phase transition involves only small portions of the Fermi surface. Such a subtle order might be a common feature among correlated electron systems, reminiscent of the similarly subtle charge DW state in the cuprates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16010929','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16010929"><span><span class="hlt">Pressure-induced</span> structural phase transformations in silicon nanowires.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poswal, H K; Garg, Nandini; Sharma, Surinder M; Busetto, E; Sikka, S K; Gundiah, Gautam; Deepak, F L; Rao, C N R</p> <p>2005-05-01</p> <p>High-<span class="hlt">pressure</span> structural behavior of silicon nanowires is investigated up to approximately 22 GPa using angle dispersive X-ray diffraction measurements. Silicon nanowires transform from the cubic to the beta-tin phase at 7.5-10.5 GPa, to the Imma phase at approximately 14 GPa, and to the primitive hexagonal structure at approximately 16.2 GPa. On complete release of <span class="hlt">pressure</span>, it transforms to the metastable R8 phase. The observed sequence of phase transitions is the same as that of bulk silicon. Though the X-ray diffraction experiments do not reveal any size effect, the <span class="hlt">pressure</span> dependence of Raman modes shows that the behavior of nanowires is in between that of the bulk crystal and porous Si.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MARY31005O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MARY31005O"><span><span class="hlt">Pressure-induced</span> structural distortions in copper pyrazine dinitrate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>O'Neal, Kenneth; Cherian, Judy; Landee, Chris; Turnbull, Mark; Liu, Zhenxian; Musfeldt, Janice</p> <p>2015-03-01</p> <p>The vibrational properties of quasi-one-dimensional Heisenberg antiferromagnet copper pyrazine dinitrate were investigated up to 9 GPa using diamond anvil cell techniques and infrared and Raman spectroscopy. Two structural transitions were discovered, at 0.7 GPa and around 5 GPa. The lower <span class="hlt">pressure</span> transition involves only the nitrate ligands, revealing enhanced interchain interactions. The higher <span class="hlt">pressure</span> transition includes modes throughout the spectrum. Importantly, the pyrazine ring-related modes show an overall lowering of symmetry through this transition. Ring buckling under <span class="hlt">pressure</span> likely reduces the exchange along the chains since the exchange pathway becomes distorted. A smaller J may therefore lower the magnetic field of the quantum critical transition. This tunable exchange interaction could be utilized in other pyrazine bridged molecular systems to bring the quantum critical behavior into experimentally realizable fields. We thank the National Science Foundation and the Petroleum Research Fund for support of this work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4827094','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4827094"><span><span class="hlt">Pressure-induced</span> topological phases of KNa2Bi</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sklyadneva, I. Yu.; Rusinov, I. P.; Heid, R.; Bohnen, K.-P.; Echenique, P. M.; Chulkov, E. V.</p> <p>2016-01-01</p> <p>We report an ab initio study of the effect of hydrostatic <span class="hlt">pressure</span> and uniaxial strain on electronic properties of KNa2Bi, a cubic bialkali bismuthide. It is found that this zero-gap semimetal with an inverted band structure at the Brillouin zone center can be driven into various topological phases under proper external <span class="hlt">pressure</span>. We show that upon hydrostatic compression KNa2Bi turns into a trivial semiconductor with a conical Dirac-type dispersion of electronic bands at the point of the topological transition while the breaking of cubic symmetry by applying a uniaxial strain converts the compound into a topological insulator or into a three-dimensional Dirac semimetal with nontrivial surface Fermi arcs depending on the sign of strain. The calculated phonon dispersions show that KNa2Bi is dynamically stable both in the cubic structure (at any considered <span class="hlt">pressures</span>) and in the tetragonal phase (under uniaxial strain). PMID:27064116</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MsT..........3B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MsT..........3B"><span>Ram <span class="hlt">pressure</span> <span class="hlt">induced</span> star formation in Abell 3266</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonsall, Brittany</p> <p></p> <p>An X-ray observation of the merging galaxy cluster Abell 3266 was obtained via the ROSAT PSPC. This information, along with spectroscopic data from the WIde-field Nearby Galaxy-clusters Survey (i.e. WINGS), were used to investigate whether ram <span class="hlt">pressure</span> is a mechanism that influences star formation. Galaxies exhibiting ongoing star formation are identified by the presence of strong Balmer lines (Hbeta), known to correspond to early type stars. Older galaxies where a rapid increase in star formation has recently ceased, known as E+A galaxies, are identified by strong Hbeta absorption coupled with little to no [OII] emission. The correlation between recent star formation and "high" ram <span class="hlt">pressure</span>, as defined by Kapferer et al. (2009) as ≥ 5 x 10-11 dyn cm-2, was tested and lead to a contradiction of the previously held belief that ram <span class="hlt">pressure</span> influences star formation on the global cluster scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27550074','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27550074"><span>Shock <span class="hlt">Wave-Induced</span> Damage and Poration in Eukaryotic Cell Membranes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>López-Marín, Luz M; Millán-Chiu, Blanca E; Castaño-González, Karen; Aceves, Carmen; Fernández, Francisco; Varela-Echavarría, Alfredo; Loske, Achim M</p> <p>2017-02-01</p> <p>Shock <span class="hlt">waves</span> are known to permeabilize eukaryotic cell membranes, which may be a powerful tool for a variety of drug delivery applications. However, the mechanisms involved in shock <span class="hlt">wave</span>-mediated membrane permeabilization are still poorly understood. In this study, the effects on both the permeability and the ultrastructural features of two human cell lineages were investigated after the application of underwater shock <span class="hlt">waves</span> in vitro. Scanning Electron Microscopy of cells derived from a human embryo kidney (HEK)-293 and Michigan Cancer Foundation (MCF)-7 cells, an immortalized culture derived from human breast adenocarcinoma, showed a small amount of microvilli (as compared to control cells), the presence of hole-like structures, and a decrease in cell size after shock <span class="hlt">wave</span> exposure. Interestingly, these effects were accompanied by the permeabilization of acid and macromolecular dyes and gene transfection. Trypan blue exclusion assays indicated that cell membranes were porated during shock <span class="hlt">wave</span> treatment but resealed after a few seconds. Deformations of the cell membrane lasted for at least 5 min, allowing their observation in fixed cells. For each cell line, different shock <span class="hlt">wave</span> parameters were needed to achieve cell membrane poration. This difference was correlated to successful gene transfection by shock <span class="hlt">waves</span>. Our results demonstrate, for the first time, that shock <span class="hlt">waves</span> <span class="hlt">induce</span> transient micro- and submicrosized deformations at the cell membrane, leading to cell transfection and cell survival. They also indicate that ultrastructural analyses of cell surfaces may constitute a useful way to match the use of shock <span class="hlt">waves</span> to different cells and settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2706489','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2706489"><span>Peptide Fragmentation <span class="hlt">Induced</span> by Radicals at Atmospheric <span class="hlt">Pressure</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vilkov, Andrey N.; Laiko, Victor V.; Doroshenko, Vladimir M.</p> <p>2009-01-01</p> <p>A novel ion dissociation technique, which is capable of providing an efficient fragmentation of peptides at essentially atmospheric <span class="hlt">pressure</span> conditions, is developed. The fragmentation patterns observed often contain c-type fragments that are specific to ECD/ETD, along with the y-/b- fragments that are specific to CAD. In the presented experimental setup, ion fragmentation takes place within a flow reactor located in the atmospheric <span class="hlt">pressure</span> region between the ion source and the mass spectrometer. According to a proposed mechanism, the fragmentation results from the interaction of ESI-generated analyte ions with the gas-phase radical species produced by a corona discharge source. PMID:19034885</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986PhyBC.139..404K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986PhyBC.139..404K"><span>Hydrostatic <span class="hlt">pressure</span> <span class="hlt">induced</span> localization effects in InSb</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kadri, A.; Zitouni, K.; Aulombard, R. L.</p> <p>1986-05-01</p> <p>Magnetoresistance and Hall coefficient measurements were made as a function of free carrier concentration, <span class="hlt">pressure</span>, temperature and magnetic field in samples of n-InSb with initial n in the range 2.1 × 10 13-1.4 × 10 14 cm -3. The free carrier concentrations could be controlled down to n « 10 11cm-3 both by using the metastable properties of the lattice coupled defects and by keeping the <span class="hlt">pressure</span> at low temperatures. The results show clear evidence for the interplay between the correlation and the localization effects at the metal-insulator transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130000449','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130000449"><span>Temperature <span class="hlt">Induced</span> Voltage Offset Drifts in Silicon Carbide <span class="hlt">Pressure</span> Sensors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Okojie, Robert S.; Lukco, Dorothy; Nguyen, Vu; Savrun, Ender</p> <p>2012-01-01</p> <p>We report the reduction of transient drifts in the zero <span class="hlt">pressure</span> offset voltage in silicon carbide (SiC) <span class="hlt">pressure</span> sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11017346','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11017346"><span>Ab initio molecular dynamics with a classical <span class="hlt">pressure</span> reservoir: simulation of <span class="hlt">pressure-induced</span> amorphization in a Si35H36 cluster</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martonak; Molteni; Parrinello</p> <p>2000-01-24</p> <p>We present a new constant-<span class="hlt">pressure</span> ab initio molecular dynamics method suitable for studying, e.g., <span class="hlt">pressure-induced</span> structural transformations in finite nonperiodic systems such as clusters. We immerse an ab initio treated cluster into a model classical liquid, described by a soft-sphere potential, which acts as a <span class="hlt">pressure</span> reservoir. The <span class="hlt">pressure</span> is varied by tuning the parameter of the liquid potential. We apply the method to a Si35H36 cluster, which undergoes a <span class="hlt">pressure-induced</span> amorphization at approximately 35 GPa, and remains in a disordered state even upon <span class="hlt">pressure</span> release.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/867193','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/867193"><span>Apparatus and method for enhanced chemical processing in high <span class="hlt">pressure</span> and atmospheric plasmas produced by high frequency electromagnetic <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Efthimion, Philip C.; Helfritch, Dennis J.</p> <p>1989-11-28</p> <p>An apparatus and method for creating high temperature plasmas for enhanced chemical processing of gaseous fluids, toxic chemicals, and the like, at a wide range of <span class="hlt">pressures</span>, especially at atmospheric and high <span class="hlt">pressures</span> includes an electro-magnetic resonator cavity, preferably a reentrant cavity, and a <span class="hlt">wave</span> guiding structure which connects an electro-magnetic source to the cavity. The cavity includes an intake port and an exhaust port, each having apertures in the conductive walls of the cavity sufficient for the intake of the gaseous fluids and for the discharge of the processed gaseous fluids. The apertures are sufficiently small to prevent the leakage of the electro-magnetic radiation from the cavity. Gaseous fluid flowing from the direction of the electro-magnetic source through the guiding <span class="hlt">wave</span> structure and into the cavity acts on the plasma to push it away from the guiding <span class="hlt">wave</span> structure and the electro-magnetic source. The gaseous fluid flow confines the high temperature plasma inside the cavity and allows complete chemical processing of the gaseous fluids at a wide range of <span class="hlt">pressures</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..94n4418M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..94n4418M"><span>Effect of disorder on a <span class="hlt">pressure-induced</span> z =1 magnetic quantum phase transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mannig, A.; Möller, J. S.; Thede, M.; Hüvonen, D.; Lancaster, T.; Xiao, F.; Williams, R. C.; Guguchia, Z.; Khasanov, R.; Morenzoni, E.; Zheludev, A.</p> <p>2016-10-01</p> <p><span class="hlt">Pressure-induced</span> ordering close to a z =1 quantum-critical point is studied in the presence of bond disorder in the quantum spin system (C4H12N2) Cu2(Cl1-xBrx) 6 (PHCX) by means of muon-spin rotation and relaxation. As for the pure system (C4H12N2) Cu2Cl6 , <span class="hlt">pressure</span> allows PHCX with small levels of disorder (x ≤7.5 %) to be driven through a quantum-critical point separating a low-<span class="hlt">pressure</span> quantum paramagnetic phase from magnetic order at high <span class="hlt">pressures</span>. However, the <span class="hlt">pressure-induced</span> ordered state is highly inhomogeneous for disorder concentrations x >1 % . This behavior might be related to the formation of a quantum Griffiths phase above a critical disorder concentration 7.5 %<xc<15 % . Br substitution increases the critical <span class="hlt">pressure</span> and suppresses critical temperatures and ordered moment sizes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26522628','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26522628"><span>Quantum Oscillation Signatures of <span class="hlt">Pressure-induced</span> Topological Phase Transition in BiTeI.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Joonbum; Jin, Kyung-Hwan; Jo, Y J; Choi, E S; Kang, W; Kampert, E; Rhyee, J-S; Jhi, Seung-Hoon; Kim, Jun Sung</p> <p>2015-11-02</p> <p>We report the <span class="hlt">pressure-induced</span> topological quantum phase transition of BiTeI single crystals using Shubnikov-de Haas oscillations of bulk Fermi surfaces. The sizes of the inner and the outer FSs of the Rashba-split bands exhibit opposite <span class="hlt">pressure</span> dependence up to P = 3.35 GPa, indicating <span class="hlt">pressure</span>-tunable Rashba effect. Above a critical <span class="hlt">pressure</span> P ~ 2 GPa, the Shubnikov-de Haas frequency for the inner Fermi surface increases unusually with <span class="hlt">pressure</span>, and the Shubnikov-de Haas oscillations for the outer Fermi surface shows an abrupt phase shift. In comparison with band structure calculations, we find that these unusual behaviors originate from the Fermi surface shape change due to <span class="hlt">pressure-induced</span> band inversion. These results clearly demonstrate that the topological quantum phase transition is intimately tied to the shape of bulk Fermi surfaces enclosing the time-reversal invariant momenta with band inversion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900018386','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900018386"><span>Sideslip-<span class="hlt">induced</span> static <span class="hlt">pressure</span> errors in flight-test measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parks, Edwin K.; Bach, Ralph E., Jr.; Tran, Duc</p> <p>1990-01-01</p> <p>During lateral flight-test maneuvers of a V/STOL research aircraft, large errors in static <span class="hlt">pressure</span> were observed. An investigation of the data showed a strong correlation of the <span class="hlt">pressure</span> record with variations in sideslip angle. The sensors for both measurements were located on a standard air-data nose boom. An algorithm based on potential flow over a cylinder that was developed to correct the <span class="hlt">pressure</span> record for sideslip-<span class="hlt">induced</span> errors is described. In order to properly apply the correction algorithm, it was necessary to estimate and correct the lag error in the <span class="hlt">pressure</span> system. The method developed for estimating <span class="hlt">pressure</span> lag is based on the coupling of sideslip activity into the static ports and can be used as a standard flight-test procedure. The estimation procedure is discussed and the corrected static-<span class="hlt">pressure</span> record for a typical lateral maneuver is presented. It is shown that application of the correction algorithm effectively attenuates sideslip-<span class="hlt">induced</span> errors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28380292','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28380292"><span>Flexible Piezoelectric-<span class="hlt">Induced</span> <span class="hlt">Pressure</span> Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Zefeng; Wang, Zhao; Li, Xinming; Lin, Yuxuan; Luo, Ningqi; Long, Mingzhu; Zhao, Ni; Xu, Jian-Bin</p> <p>2017-04-05</p> <p>The piezoelectric effect is widely applied in <span class="hlt">pressure</span> sensors for the detection of dynamic signals. However, these piezoelectric-<span class="hlt">induced</span> <span class="hlt">pressure</span> sensors have challenges in measuring static signals which are based on the transient flow of electrons in external load as driven by the piezopotential arisen from dynamic stress. Here, we present a <span class="hlt">pressure</span> sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-<span class="hlt">induced</span> polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene <span class="hlt">pressure</span> sensors, this sensor is capable of measuring static <span class="hlt">pressures</span> with a sensitivity up to 9.4×10(-3) kPa(-1) and a fast response time down to 5-7 ms. This demonstration of <span class="hlt">pressure</span> sensors shows great potential in the applications of electronic skin and wearable devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JaJAP..54fGD03O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JaJAP..54fGD03O"><span>Variation of antioxidative activity and growth enhancement of Brassicaceae <span class="hlt">induced</span> by low-<span class="hlt">pressure</span> oxygen plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ono, Reoto; Hayashi, Nobuya</p> <p>2015-06-01</p> <p>The mechanism of growth enhancement <span class="hlt">induced</span> by active oxygen species generated in an oxygen plasma is investigated. The plant growth enhancement <span class="hlt">induced</span> by the active oxygen species would relate to an antioxidative activity, which is one of the biological responses. The amount of generated active oxygen species is varied by the oxygen gas <span class="hlt">pressure</span> in a low-<span class="hlt">pressure</span> RF glow discharge plasma. The antioxidative activity of sprouts of Brassicaceae <span class="hlt">induced</span> by the oxygen plasma is maximized at <span class="hlt">pressures</span> between 30 and 40 Pa, whereas the antioxidative activity becomes small at around 60 and 80 Pa. The <span class="hlt">pressure</span> dependence of the antioxidative activity of sprout stems is opposite to that of the stem length of the sprouts. The growth enhancement would be <span class="hlt">induced</span> by the increase in the concentration of active oxygen species in plants owing to the decrease in the amount of antioxidative substances.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730029793&hterms=beer+stability&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dbeer%2Bstability','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730029793&hterms=beer+stability&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dbeer%2Bstability"><span>Atmospheric <span class="hlt">wave-induced</span> instability in the nighttime E-region.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Beer, T.; Moorcroft, D. R.</p> <p>1972-01-01</p> <p>Examination of the perturbed continuity equation when the perturbations are the result of an internal atmospheric gravity <span class="hlt">wave</span> in the E region. The transient response of the ionization is interpreted as the gradient instability and the values of the vertical and horizontal <span class="hlt">wave</span> numbers that will <span class="hlt">induce</span> it are plotted for various heights. Only in the presence of westward directed electric fields, which are believed to occur only at night, will the gravity <span class="hlt">waves</span> <span class="hlt">induce</span> the gradient instability. Approximate analytic expressions are obtained for the permitted <span class="hlt">wave</span> numbers as well as for the instability growth times. In the course of this analysis it is shown that in the D region all irregularities, even those that are field-aligned, will tend to move with the ion velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvB..87l1112C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvB..87l1112C"><span>Fluctuation-<span class="hlt">induced</span> pair density <span class="hlt">wave</span> in itinerant ferromagnets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conduit, G. J.; Pedder, C. J.; Green, A. G.</p> <p>2013-03-01</p> <p>Magnetic fluctuations near to quantum criticality can have profound effects. They lead to characteristic scaling at high temperature which may ultimately give way to a reconstruction of the phase diagram and the formation of new phases at low temperatures. The ferromagnet UGe2 is unstable to p-<span class="hlt">wave</span> superconducting order—an effect presaged by the superfluidity in 3He—whereas in CeFePO fluctuations drive the formation of spiral magnetic order. Here we develop a general quantum order-by-disorder description of these systems that encompasses both of these instabilities within a unified framework. This allows us to demonstrate that in fact these instabilities intertwine to form a pair density <span class="hlt">wave</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22107734','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22107734"><span>Emission of radiation <span class="hlt">induced</span> by pervading Alfven <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhao, G. Q.; Wu, C. S.</p> <p>2013-03-15</p> <p>It is shown that under certain conditions, propagating Alfven <span class="hlt">waves</span> can energize electrons so that consequently a new cyclotron maser instability is born. The necessary condition is that the plasma frequency is lower than electron gyrofrequency. This condition implies high Alfven speed, which can pitch-angle scatter electrons effectively and therefore the electrons are able to acquire free energy which are needed for the instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA256402','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA256402"><span>Irregular <span class="hlt">Wave-Induced</span> Velocities in Shallow Water</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1992-09-01</p> <p>and Acceleration of the Surface of Wind <span class="hlt">Waves</span>," Rep. Res. Inst. Appl . Mech. (Kyushu Univ.), 24, No. 76, 31-48. 19, Hughes, S.A. (1991) "Estimating...8217 siilk 2 i- (D½ 0 0 411 0 Ursoll No. 0.1 10 100 1000 10000 Ursell No. W (.), z-mid-depth W (#), z-bottom W (-), z-mid-depth W (-), z-bottom (b) Figure 72</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21409059','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21409059"><span>Constraints on primordial density perturbations from <span class="hlt">induced</span> gravitational <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Assadullahi, Hooshyar; Wands, David</p> <p>2010-01-15</p> <p>We consider the stochastic background of gravitational <span class="hlt">waves</span> produced during the radiation-dominated hot big bang as a constraint on the primordial density perturbation on comoving length scales much smaller than those directly probed by the cosmic microwave background or large-scale structure. We place weak upper bounds on the primordial density perturbation from current data. Future detectors such as BBO and DECIGO will place much stronger constraints on the primordial density perturbation on small scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19640000029','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19640000029"><span>Device <span class="hlt">induces</span> lungs to maintain known constant <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lippitt, M. W.; Reed, J. H.</p> <p>1964-01-01</p> <p>This device requires the use of thoracic muscles to maintain prescribed air <span class="hlt">pressure</span> in the lungs for brief periods. It consists of a clear plastic hollow cylinder fitted with a mouthpiece, a spring-loaded piston, and a small vent for escaping air when exhalation into the mouthpiece displaces the piston.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApPhL.110k1901W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApPhL.110k1901W"><span>High stored energy of metallic glasses <span class="hlt">induced</span> by high <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, C.; Yang, Z. Z.; Ma, T.; Sun, Y. T.; Yin, Y. Y.; Gong, Y.; Gu, L.; Wen, P.; Zhu, P. W.; Long, Y. W.; Yu, X. H.; Jin, C. Q.; Wang, W. H.; Bai, H. Y.</p> <p>2017-03-01</p> <p>Modulating energy states of metallic glasses (MGs) is significant in understanding the nature of glasses and controlling their properties. In this study, we show that high stored energy can be achieved and preserved in bulk MGs by high <span class="hlt">pressure</span> (HP) annealing, which is a controllable method to continuously alter the energy states of MGs. Contrary to the decrease in enthalpy by conventional annealing at ambient <span class="hlt">pressure</span>, high stored energy can occur and be enhanced by increasing both annealing temperature and <span class="hlt">pressure</span>. By using double aberration corrected scanning transmission electron microscopy, it is revealed that the preserved high energy, which is attributed to the coupling effect of high <span class="hlt">pressure</span> and high temperature, originates from the microstructural change that involves "negative flow units" with a higher atomic packing density compared to that of the elastic matrix of MGs. The results demonstrate that HP-annealing is an effective way to activate MGs into higher energy states, and it may assist in understanding the microstructural origin of high energy states in MGs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/992292','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/992292"><span><span class="hlt">Pressure-induced</span> isostructural transition in PdN2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Aberg, D; Erhart, P; Crowhurst, J; Zaug, J M; Goncharov, A F; Sadigh, B</p> <p>2010-03-05</p> <p>We show that a synthesized Pd-N compound crystallize into the pyrite structure by comparison of experimental and calculated Raman intensities. The decreasing Raman intensities with decreasing <span class="hlt">pressure</span> is explained by a closing of the fundamental band gap. We further discuss the experimental decomposition of this compound at 11 GPa in terms of an isostructural transition within the pyrite structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011408','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011408"><span>Analysis of Numerical Simulation Database for <span class="hlt">Pressure</span> Fluctuations <span class="hlt">Induced</span> by High-Speed Turbulent Boundary Layers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Duan, Lian; Choudhari, Meelan M.</p> <p>2014-01-01</p> <p>Direct numerical simulations (DNS) of Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Re(sub T) approximately 460 are conducted at two wall temperatures (Tw/Tr = 0.25, 0.76) to investigate the generated <span class="hlt">pressure</span> fluctuations and their dependence on wall temperature. Simulations indicate that the influence of wall temperature on <span class="hlt">pressure</span> fluctuations is largely limited to the near-wall region, with the characteristics of wall-<span class="hlt">pressure</span> fluctuations showing a strong temperature dependence. Wall temperature has little influence on the propagation speed of the freestream <span class="hlt">pressure</span> signal. The freestream radiation intensity compares well between wall-temperature cases when normalized by the local wall shear; the propagation speed of the freestream <span class="hlt">pressure</span> signal and the orientation of the radiation <span class="hlt">wave</span> front show little dependence on the wall temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=208706','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=208706"><span>Dietary copper supplementation reverses hypertrophic cardiomyopathy <span class="hlt">induced</span> by chronic <span class="hlt">pressure</span> overload in mice</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Sustained <span class="hlt">pressure</span> overload causes cardiac hypertrophy and the transition to heart failure. We show here that dietary supplementation with physiologically relevant levels of copper (Cu) reverses pre-established hypertrophic cardiomyopathy in the presence of <span class="hlt">pressure</span> overload <span class="hlt">induced</span> by ascending aor...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890043309&hterms=transfinite&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtransfinite','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890043309&hterms=transfinite&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtransfinite"><span>Evaluation of thermally <span class="hlt">induced</span> non-Fourier stress <span class="hlt">wave</span> disturbances via tailored hybrid transfinite element formulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tamma, Kumar K.; Railkar, Sudhir B.</p> <p>1989-01-01</p> <p>Accurate solutions have been obtained for a class of non-Fourier models in dynamic thermoelasticity which are relevant to the understanding of thermally-<span class="hlt">induced</span> stress <span class="hlt">wave</span> disturbances. The method employs tailored hybrid formulations based on the transfinite element approach. The results show that significant thermal stresses may arise due to non-Fourier effects, especially when the speeds of propagation of the thermal and stress <span class="hlt">waves</span> are equal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15783973','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15783973"><span>Observation of radio-<span class="hlt">wave-induced</span> red hydroxyl emission at low altitude in the ionosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kagan, L M; Nicolls, M J; Kelley, M C; Carlson, H C; Belikovich, V V; Bakhmet'eva, N V; Komrakov, G P; Trondsen, T S; Donovan, E</p> <p>2005-03-11</p> <p>We report the discovery of radio-<span class="hlt">wave-induced</span> red emission of OH Meinel rotation-vibrational bands at 629.79 nm. These are the first measurements of artificial aurora below 100 km. We believe that the 629.79-nm OH emission was due to radio-<span class="hlt">wave</span> focusing by sporadic ionization clouds near 80-85 km altitude, thus giving a technique to visualize the low-altitude sporadic ionization and providing insight into ionospheric interactions at these low altitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5009905','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5009905"><span>Kidney Dysfunction Mediates Salt-<span class="hlt">Induced</span> Increases in Blood <span class="hlt">Pressure</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hall, John E.</p> <p>2016-01-01</p> <p>Chronic excess salt intake increases the risk for hypertension and moderation of salt intake is an important strategy for prevention of cardiovascular and kidney disease, especially in salt-sensitive subjects. Although short-term blood <span class="hlt">pressure</span> (BP) responses to high salt intake over several days are highly variable, chronic high salt intake worsens BP salt-sensitivity. Aging, diabetes, hypertension, and various acquired and genetic kidney disorders also exacerbate salt-sensitivity of BP. Kidney dysfunction, characterized by impaired <span class="hlt">pressure</span> natriuresis, has been demonstrated in all forms of experimental and human genetic or acquired salt-sensitive hypertension studied thus far. Abnormalities of kidney function that directly or indirectly increase NaCl reabsorption, decrease glomerular capillary filtration coefficient, or cause nephron injury/loss exacerbate BP salt-sensitivity. In most cases, salt-sensitive hypertension is effectively treated with drugs that increase glomerular filtration rate or reduce renal NaCl reabsorption (e.g. diuretics, renin-angiotensin-aldosterone system blockers). Increased vascular resistance may occur concomitantly or secondarily to kidney dysfunction and increased BP in salt-sensitive hypertension. However, primary increases in non-renal vascular resistance have not been shown to cause salt-sensitive hypertension or long-term changes in BP in the absence of impaired renal-<span class="hlt">pressure</span> natriuresis. The mechanisms responsible for increased total peripheral resistance (TPR) during high salt intake in salt-sensitive subjects are not fully understood but likely involve <span class="hlt">pressure</span>-dependent and/or flow-dependent autoregulation in peripheral tissues as well as neurohormonal factors that occur concomitantly with kidney dysfunction. Physiological studies have demonstrated that increased BP almost invariably initiates secondary <span class="hlt">pressure</span>-dependent functional and structural vascular changes that increase TPR. PMID:26927007</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5000556','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5000556"><span>Reduced Sodium Current in the Lateral Ventricular Wall <span class="hlt">Induces</span> Inferolateral J-<span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meijborg, Veronique M. F.; Potse, Mark; Conrath, Chantal E.; Belterman, Charly N. W.; De Bakker, Jacques M. T.; Coronel, Ruben</p> <p>2016-01-01</p> <p>Background: J-<span class="hlt">waves</span> in inferolateral leads are associated with a higher risk for idiopathic ventricular fibrillation. We aimed to test potential mechanisms (depolarization or repolarization dependent) responsible for inferolateral J-<span class="hlt">waves</span>. We hypothesized that inferolateral J-<span class="hlt">waves</span> can be caused by regional delayed activation of myocardium that is activated late during normal conditions. Methods: Computer simulations were performed to evaluate how J-point elevation is influenced by reducing sodium current conductivity (GNa), increasing transient outward current conductivity (Gto), or cellular uncoupling in three predefined ventricular regions (lateral, anterior, or septal). Two pig hearts were Langendorff-perfused with selective perfusion with a sodium channel blocker of lateral or anterior/septal regions. Volume-conducted pseudo-electrocardiograms (ECG) were recorded to detect the presence of J-<span class="hlt">waves</span>. Epicardial unipolar electrograms were simultaneously recorded to obtain activation times (AT). Results: Simulation data showed that conduction slowing, caused by reduced sodium current, in lateral, but not in other regions <span class="hlt">induced</span> inferolateral J-<span class="hlt">waves</span>. An increase in transient outward potassium current or cellular uncoupling in the lateral zone elicited slight J-point elevations which did not meet J-<span class="hlt">wave</span> criteria. Additional conduction slowing in the entire heart attenuated J-<span class="hlt">waves</span> and J-point elevations on the ECG, because of masking by the QRS. Experimental data confirmed that conduction slowing attributed to sodium channel blockade in the left lateral but not in the anterior/septal ventricular region <span class="hlt">induced</span> inferolateral J-<span class="hlt">waves</span>. J-<span class="hlt">waves</span> coincided with the delayed activation. Conclusion: Reduced sodium current in the left lateral ventricular myocardium can cause inferolateral J-<span class="hlt">waves</span> on the ECG. PMID:27616994</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22399115','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22399115"><span>Dipolar field-<span class="hlt">induced</span> spin-<span class="hlt">wave</span> waveguides for spin-torque magnonics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Demidov, V. E.; Urazhdin, S.; Zholud, A.; Sadovnikov, A. V.; Demokritov, S. O.</p> <p>2015-01-12</p> <p>We use high-resolution imaging to study the propagation of spin <span class="hlt">waves</span> in magnonic waveguides created by the dipolar magnetic fields of microscopic patterns. We show that the characteristics of spin-<span class="hlt">wave</span> modes in such waveguides depend strongly on their geometry. In particular, by tuning the geometrical parameters, field-<span class="hlt">induced</span> confinement for both the edge and the center waveguide modes can be achieved, enabling control over the spin-<span class="hlt">wave</span> transmission characteristics. The studied waveguiding structures are particularly promising for the implementation of magnonic devices utilizing spin-torque phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23214859','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23214859"><span>Scroll <span class="hlt">wave</span> meandering <span class="hlt">induced</span> by phase difference in a three-dimensional excitable medium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Zhao; Gao, Shiyuan; Ouyang, Qi; Wang, Hongli</p> <p>2012-11-01</p> <p>We investigated scroll <span class="hlt">waves</span> in an inhomogeneous excitable 3D system with gradient of excitability. The gradient promotes twisting of the scroll <span class="hlt">waves</span>. Sufficiently large excitability gradient enhances the twisting and causes simple scroll <span class="hlt">waves</span> to transition to meandering scroll <span class="hlt">waves</span>. For the twist-<span class="hlt">induced</span> instability of scroll <span class="hlt">waves</span>, we analyzed the stability of 2D spiral <span class="hlt">waves</span> sliced from the twisted scroll in the vertical direction. The 3D problem is simplified by taking into account the diffusive coupling in the third direction as a time-delayed perturbation to the 2D spiral <span class="hlt">wave</span>. An additional "negative mass" term measuring the twist thus arises in the 2D system and <span class="hlt">induces</span> the transition from simple rotation to meandering. A further increase in the gradient ruins partially the unity of the meandering scrolls and generates semiturbulence, the analogs of which were observed in the Belousov-Zhabotinski reaction. We also generated the phase diagram in the parameter space by adjusting the threshold for excitation of the media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241942','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241942"><span>Investigating the thermally <span class="hlt">induced</span> acoustoelastic effect in isotropic media with Lamb <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dodson, Jacob C.; Inman, Daniel J.</p> <p>2014-01-01</p> <p>Elastic <span class="hlt">wave</span> velocities in metallic structures are affected by variations in environmental conditions such as changing temperature. This paper extends the theory of acoustoelasticity by allowing thermally <span class="hlt">induced</span> strains in unconstrained isotropic media, and it experimentally examines the velocity variation of Lamb <span class="hlt">waves</span> in aluminum plates (AL-6061) due to isothermal temperature deviations. This paper presents both thermally <span class="hlt">induced</span> acoustoelastic constants and thermally varying effective Young's modulus and Poisson's ratio which include the third order elastic material constants. The experimental thermal sensitivity of the phase velocity (∂vP/∂θ) for both the symmetric and antisymmetric modes are bounded by two theories, the acoustoelastic Lamb <span class="hlt">wave</span> theory with thermo-acoustoelastic tensors and the thermoelastic Lamb <span class="hlt">wave</span> theory using an effective thermo-acoustoelastic moduli. This paper shows the theoretical thermally <span class="hlt">induced</span> acoustoelastic Lamb <span class="hlt">wave</span> thermal sensitivity (∂vP/∂θ) is an upper bound approximation of the experimental thermal changes, but the acoustoelastic Lamb <span class="hlt">wave</span> theory is not valid for predicting the antisymmetric (A0) phase velocity at low frequency-thickness values, <1.55 MHz mm for various temperatures. PMID:25373955</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25373955','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25373955"><span>Investigating the thermally <span class="hlt">induced</span> acoustoelastic effect in isotropic media with Lamb <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dodson, Jacob C; Inman, Daniel J</p> <p>2014-11-01</p> <p>Elastic <span class="hlt">wave</span> velocities in metallic structures are affected by variations in environmental conditions such as changing temperature. This paper extends the theory of acoustoelasticity by allowing thermally <span class="hlt">induced</span> strains in unconstrained isotropic media, and it experimentally examines the velocity variation of Lamb <span class="hlt">waves</span> in aluminum plates (AL-6061) due to isothermal temperature deviations. This paper presents both thermally <span class="hlt">induced</span> acoustoelastic constants and thermally varying effective Young's modulus and Poisson's ratio which include the third order elastic material constants. The experimental thermal sensitivity of the phase velocity (∂v(P)/∂θ) for both the symmetric and antisymmetric modes are bounded by two theories, the acoustoelastic Lamb <span class="hlt">wave</span> theory with thermo-acoustoelastic tensors and the thermoelastic Lamb <span class="hlt">wave</span> theory using an effective thermo-acoustoelastic moduli. This paper shows the theoretical thermally <span class="hlt">induced</span> acoustoelastic Lamb <span class="hlt">wave</span> thermal sensitivity (∂v(P)/∂θ) is an upper bound approximation of the experimental thermal changes, but the acoustoelastic Lamb <span class="hlt">wave</span> theory is not valid for predicting the antisymmetric (A0) phase velocity at low frequency-thickness values, <1.55 MHz mm for various temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730020190','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730020190"><span>Prediction of fluctuating <span class="hlt">pressure</span> environments associated with plume-<span class="hlt">induced</span> separated flow fields</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Plotkin, K. J.</p> <p>1973-01-01</p> <p>The separated flow environment <span class="hlt">induced</span> by underexpanded rocket plumes during boost phase of rocket vehicles has been investigated. A simple semi-empirical model for predicting the extent of separation was developed. This model offers considerable computational economy as compared to other schemes reported in the literature, and has been shown to be in good agreement with limited flight data. The unsteady <span class="hlt">pressure</span> field in plume-<span class="hlt">induced</span> separated regions was investigated. It was found that fluctuations differed from those for a rigid flare only at low frequencies. The major difference between plume-<span class="hlt">induced</span> separation and flare-<span class="hlt">induced</span> separation was shown to be an increase in shock oscillation distance for the plume case. The prediction schemes were applied to PRR shuttle launch configuration. It was found that fluctuating <span class="hlt">pressures</span> from plume-<span class="hlt">induced</span> separation are not as severe as for other fluctuating environments at the critical flight condition of maximum dynamic <span class="hlt">pressure</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvL.113c8101G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvL.113c8101G"><span>Imaging of Shear <span class="hlt">Waves</span> <span class="hlt">Induced</span> by Lorentz Force in Soft Tissues</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grasland-Mongrain, P.; Souchon, R.; Cartellier, F.; Zorgani, A.; Chapelon, J. Y.; Lafon, C.; Catheline, S.</p> <p>2014-07-01</p> <p>This study presents the first observation of elastic shear <span class="hlt">waves</span> generated in soft solids using a dynamic electromagnetic field. The first and second experiments of this study showed that Lorentz force can <span class="hlt">induce</span> a displacement in a soft phantom and that this displacement was detectable by an ultrasound scanner using speckle-tracking algorithms. For a 100 mT magnetic field and a 10 ms, 100 mA peak-to-peak electrical burst, the displacement reached a magnitude of 1 μm. In the third experiment, we showed that Lorentz force can <span class="hlt">induce</span> shear <span class="hlt">waves</span> in a phantom. A physical model using electromagnetic and elasticity equations was proposed. Computer simulations were in good agreement with experimental results. The shear <span class="hlt">waves</span> <span class="hlt">induced</span> by Lorentz force were used in the last experiment to estimate the elasticity of a swine liver sample.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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