WorldWideScience

Sample records for rapid pressure fluctuations

  1. Fluctuating shells under pressure

    Science.gov (United States)

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  2. Pressure Fluctuations in Nonideal Plasma

    NARCIS (Netherlands)

    Lankin, A.; Norman, G.; Saitov, I.

    Fluctuations of pressure of singly ionized nonideal plasma are studied using the fluctuation approach which provides the self-consistent joint description of free and weakly bound electron states. The classical molecular dynamics method is used. The electron-ion interaction is described by the

  3. Chaotic Maps Dynamics, Fractals, and Rapid Fluctuations

    CERN Document Server

    Chen, Goong

    2011-01-01

    This book consists of lecture notes for a semester-long introductory graduate course on dynamical systems and chaos taught by the authors at Texas A&M University and Zhongshan University, China. There are ten chapters in the main body of the book, covering an elementary theory of chaotic maps in finite-dimensional spaces. The topics include one-dimensional dynamical systems (interval maps), bifurcations, general topological, symbolic dynamical systems, fractals and a class of infinite-dimensional dynamical systems which are induced by interval maps, plus rapid fluctuations of chaotic maps as a

  4. RAPID FLUCTUATIONS IN THE LOWER SOLAR ATMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J. K.; Cadavid, A. C.; Christian, D. J. [Department of Physics and Astronomy, California State University, Northridge, Northridge, CA 91330-8268 (United States); Jess, D. B.; Mathioudakis, M., E-mail: john.lawrence@csun.edu [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom)

    2011-12-10

    The Rapid Oscillations in the Solar Atmosphere instrument reveals solar atmospheric fluctuations at high frequencies. Spectra of variations of the G-band intensity (I{sub G} ) and Ca II K-line intensity (I{sub K} ) show correlated fluctuations above white noise to frequencies beyond 300 mHz and 50 mHz, respectively. The noise-corrected G-band spectrum for f = 28-326 mHz shows a power law with exponent -1.21 {+-} 0.02, consistent with the presence of turbulent motions. G-band spectral power in the 25-100 mHz ('UHF') range is concentrated at the locations of magnetic bright points in the intergranular lanes and is highly intermittent in time. The intermittence of the UHF G-band fluctuations, shown by a positive kurtosis {kappa}, also suggests turbulence. Combining values of I{sub G} , I{sub K} , UHF power, and {kappa} reveals two distinct states of the solar atmosphere. State 1, including almost all the data, is characterized by low I{sub G} , I{sub K} , and UHF power and {kappa} Almost-Equal-To 6. State 2, including only a very small fraction of the data, is characterized by high I{sub G} , I{sub K} , and UHF power and {kappa} Almost-Equal-To 3. Superposed epoch analysis shows that the UHF power peaks simultaneously with spatio-temporal I{sub G} maxima in either state. For State 1, I{sub K} shows 3.5 minute chromospheric oscillations with maxima occurring 21 s after I{sub G} maxima implying a 150-210 km effective height difference. However, for State 2 the I{sub K} and I{sub G} maxima are simultaneous; in this highly magnetized environment sites of G-band and K-line emission may be spatially close together.

  5. Rapid Fluctuations in the Lower Solar Atmosphere

    Science.gov (United States)

    Lawrence, J. K.; Cadavid, A. C.; Christian, D. J.; Jess, D. B.; Mathioudakis, M.

    2011-12-01

    The Rapid Oscillations in the Solar Atmosphere instrument reveals solar atmospheric fluctuations at high frequencies. Spectra of variations of the G-band intensity (IG ) and Ca II K-line intensity (IK ) show correlated fluctuations above white noise to frequencies beyond 300 mHz and 50 mHz, respectively. The noise-corrected G-band spectrum for f = 28-326 mHz shows a power law with exponent -1.21 ± 0.02, consistent with the presence of turbulent motions. G-band spectral power in the 25-100 mHz ("UHF") range is concentrated at the locations of magnetic bright points in the intergranular lanes and is highly intermittent in time. The intermittence of the UHF G-band fluctuations, shown by a positive kurtosis κ, also suggests turbulence. Combining values of IG , IK , UHF power, and κ reveals two distinct states of the solar atmosphere. State 1, including almost all the data, is characterized by low IG , IK , and UHF power and κ ≈ 6. State 2, including only a very small fraction of the data, is characterized by high IG , IK , and UHF power and κ ≈ 3. Superposed epoch analysis shows that the UHF power peaks simultaneously with spatio-temporal IG maxima in either state. For State 1, IK shows 3.5 minute chromospheric oscillations with maxima occurring 21 s after IG maxima implying a 150-210 km effective height difference. However, for State 2 the IK and IG maxima are simultaneous; in this highly magnetized environment sites of G-band and K-line emission may be spatially close together.

  6. Refractive-index and absorption fluctuations in the infrared caused by temperature, humidity, and pressure fluctuations

    Science.gov (United States)

    Hill, R. J.; Clifford, S. F.; Lawrence, R. S.

    1980-10-01

    The dependence of fluctuations in atmospheric absorption and refraction upon fluctuations in temperature, humidity, and pressure is found for infrared frequencies. This dependence has contributions from line and continuum absorption and from anomalous refraction by water vapor. The functions that relate these fluctuations are necessary for evaluating degradation of electromagnetic radiation by turbulence. They are computed for a given choice of mean atmospheric conditions and graphed as functions of frequency in the wavelength range 5.7 microns to radio waves. It is found that turbulent fluctuations in total pressure give a negligible contribution to absorption and refraction fluctuations. Humidity fluctuations dominate absorption fluctuations, but contributions by temperature and humidity affect refraction fluctuations. Sufficiently strong humidity fluctuations can dominate the refraction fluctuations for some infrared frequencies but not for visible frequencies. The variance of log amplitude is examined for scintillation of infrared light to determine whether absorption or refraction fluctuations dominate under several conditions.

  7. Turbulent Spot Pressure Fluctuation Wave Packet Model

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    Wave packet analysis provides a connection between linear small disturbance theory and subsequent nonlinear turbulent spot flow behavior. The traditional association between linear stability analysis and nonlinear wave form is developed via the method of stationary phase whereby asymptotic (simplified) mean flow solutions are used to estimate dispersion behavior and stationary phase approximation are used to invert the associated Fourier transform. The resulting process typically requires nonlinear algebraic equations inversions that can be best performed numerically, which partially mitigates the value of the approximation as compared to a more complete, e.g. DNS or linear/nonlinear adjoint methods. To obtain a simpler, closed-form analytical result, the complete packet solution is modeled via approximate amplitude (linear convected kinematic wave initial value problem) and local sinusoidal (wave equation) expressions. Significantly, the initial value for the kinematic wave transport expression follows from a separable variable coefficient approximation to the linearized pressure fluctuation Poisson expression. The resulting amplitude solution, while approximate in nature, nonetheless, appears to mimic many of the global features, e.g. transitional flow intermittency and pressure fluctuation magnitude behavior. A low wave number wave packet models also recover meaningful auto-correlation and low frequency spectral behaviors.

  8. Distribution of Pressure Fluctuations in a Prototype Pump Turbine at Pump Mode

    Directory of Open Access Journals (Sweden)

    Yuekun Sun

    2014-02-01

    Full Text Available Pressure fluctuations are very important characteristics in pump turbine's operation. Many researches have focused on the characteristics (amplitude and frequencies of pressure fluctuations at specific locations, but little researches mentioned the distribution of pressure fluctuations in a pump turbine. In this paper, 3D numerical simulations using SSTk − ω turbulence model were carried out to predict the pressure fluctuations distribution in a prototype pump turbine at pump mode. Three operating points with different mass flow rates and different guide vanes’ openings were simulated. The numerical results show how pressure fluctuations at blade passing frequency (BPF and its harmonics vary along the whole flow path direction, as well as along the circumferential direction. BPF is the first dominant frequency in vaneless space. Pressure fluctuation component at this frequency rapidly decays towards upstream (to draft tube and downstream (to spiral casing. In contrast, pressure fluctuations component at 3BPF spreads to upstream and downstream with almost constant amplitude. Amplitude and frequencies of pressure fluctuations also vary along different circumferential locations in vaneless space. When the mass flow and guide vanes’ opening are different, the distribution of pressure fluctuations along the two directions is different basically.

  9. Rapidly fluctuating anosmia: A clinical sign for unilateral smell impairment.

    Science.gov (United States)

    Negoias, Simona; Friedrich, Hergen; Caversaccio, Marco D; Landis, Basile N

    2016-02-01

    Reports about fluctuating olfactory deficits are rare, as are reports of unilateral olfactory loss. We present a case of unilateral anosmia with contralateral normosmia, presenting as rapidly fluctuating anosmia. The olfactory fluctuation occurred in sync with the average nasal cycle duration. Examination after nasal decongestion, formal smell testing, and imaging revealed unilateral, left-sided anosmia of sinonasal cause, with right-sided normosmia. We hypothesize that the nasal cycle induced transient anosmia when blocking the normosmic side. Fluctuating olfactory deficits might hide a unilateral olfactory loss and require additional unilateral testing and thorough workup. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  10. Intraocular pressure fluctuation during microincision vitrectomy with constellation vision system.

    Science.gov (United States)

    Sugiura, Yoshimi; Okamoto, Fumiki; Okamoto, Yoshifumi; Hiraoka, Takahiro; Oshika, Tetsuro

    2013-11-01

    To investigate intraocular pressure (IOP) fluctuation during various vitrectomy maneuvers using the vitrectomy system (Alcon Constellation Vision System). An experimental study as laboratory investigation. In porcine eyes, 23- and 25-gauge vitrectomy was performed, and IOP fluctuations were evaluated in vitreous cutting mode, in aspiration mode, and during scleral compression. The measurements were performed with the IOP control setting turned on or off. Using the 23-gauge system with the IOP control setting turned on, IOP decreased from 30 to 23.7 mm Hg after starting vitreous cutting, and then returned to 30 mm Hg in 2.6 seconds. When the IOP control setting was turned off, IOP decreased to 19.1 mm Hg in 0.9 seconds, and remained at that pressure. Under aspiration at 650 mm Hg without cutting, IOP showed a sharp depression from 30 to 12.2 mm Hg, and then returned to 30.6 mm Hg in 2.6 seconds with the IOP control setting turned on. When the IOP control setting was turned off, IOP decreased to 2.2 mm Hg in 9.7 seconds, and did not recover. When the sclera was compressed without aspiration, IOP rapidly increased to 70-100 mm Hg, and then slowly decreased to 30 mm Hg in 3.5-4.0 seconds, with or without the IOP control system. Similar data were obtained with 25-gauge vitrectomy. The IOP control system can attenuate IOP fluctuations during vitrectomy maneuvers. There was no significant difference in IOP fluctuations between 23- and 25-gauge systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Influence of ocular perfusion pressure fluctuation on glaucoma

    Directory of Open Access Journals (Sweden)

    Min-Zi Ren

    2015-12-01

    Full Text Available AIM:To investigate the influence of ocular perfusion pressure fluctuation on glaucoma. METHODS:Forty patients with primary open angle glaucoma from January 2013 to June 2015 in our hospital were used as observation group and 40 families were used as control group. Circadian fluctuation of intraocular pressure, blood pressure and ocular perfusion pressure in 24h were determined to obtain systolic ocular perfusion pressure(SOPP, diastolic ocular perfusion pressure(DOPPand mean ocular perfusion pressure(MOPP. Pearson linear correlation was used to analyze the correlation of circadian MOPP fluctuation with cup-disc ratio, mean defect(MDand the picture standard deviation(PSD. RESULTS:The fluctuation of MOPP, SOPP and DOPP of observation group were significantly higher than those of control group(Pr=-0.389, 95%CI:-0.612~-0.082; P=0.011, was positively correlated with PSD(r=0.512, 95%CI:0.139 ~0.782; P=0.008; no correlation was found between it and the vertical cup-disc ratio(r=0.115, 95%CI:0.056~0.369; P=0.355. CONCLUSION:Ocular perfusion pressure fluctuations in patients with primary open angle glaucoma may reflect the severity of the disease and may make the situation aggravating. Therefore through perfusion pressure monitor in 24h may help us understand the ocular blood flow and the development of primary open-angle glaucoma.

  12. Measuring Fluctuating Pressures With Recessed Gauges

    Science.gov (United States)

    Parrott, Tony L.; Jones, Michael G.

    1993-01-01

    Report discusses use of pressure gauges mounted in recesses in interior wall of model scramjet engine. Consists of brief memorandum plus excerpts from NASA Technical Paper 3189, "Unsteady Pressure Loads In A Generic High-Speed Engine Model." Focuses mainly on factors affecting accuracy of gauge readings.

  13. Pressure Fluctuations Induced by a Hypersonic Turbulent Boundary Layer

    Science.gov (United States)

    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.

  14. Prediction of propeller-induced hull-pressure fluctuations

    NARCIS (Netherlands)

    Van Wijngaarden, H.C.J.

    2011-01-01

    The cavitating propeller often forms the primary source of noise and vibration on board ships. The propeller induces hydroacoustic pressure fluctuations due to the passing blades and, more importantly, the dynamic activity of cavities in the propeller’s immediate vicinity. The accurate prediction of

  15. An Elderly Parkinsonian Patient with Extreme Blood Pressure Fluctuations

    Directory of Open Access Journals (Sweden)

    Da-Wei Chen

    2014-09-01

    Full Text Available Blood pressure (BP fluctuations after long-term levodopa therapy are rarely reported. Patients with Parkinson's disease (PD often have dysautonomia, and neuropsychiatric and sleep disorders, which influence BP. It is difficult to control BP when hypertension coexists with these complications. We present the case of a 78-year-old man with PD who had hypotensive shock and extreme fluctuations of BP. Fluctuations in BP with the use of levodopa are more significant in patients with motor symptom fluctuations, autonomic nervous system disorders, primary hypertension, advanced stage of PD, and anxiety or sleep disorders. We controlled BP fluctuations by dividing the total daily levodopa and benserazide (Madopar dose into smaller doses given more often, adding a sedative, and carrying out some simple nonmedical treatments for postprandial and orthostatic hypotension. At the same time, “dyskinesia” and “wearing-off” were also improved. BP fluctuations have a considerable influence on patients' quality of life and can even be life-threatening. The mechanism is complex, therefore a correct analysis of the underlying causes is needed to carry out comprehensive management. Adjustment of levodopa administration can not only stabilize BP well, but also can control PD motor complications.

  16. Pressure measurements in a rapidly sheared turbulent wall layer

    Science.gov (United States)

    Diwan, Sourabh; Morrison, Jonathan

    2014-11-01

    The aim of the present work is to improve understanding of the role of pressure fluctuations in the generation of coherent structures in wall-bounded turbulent flows, with particular regard to the rapid and slow source terms. The work is in part motivated by the recent numerical simulations of Sharma et al. (Phy. Fluids, 23, 2011), which showed the importance of pressure fluctuations (and their spatial gradients) in the dynamics of large-scale turbulent motions. Our experimental design consists of first generating a shearless boundary layer in a wind tunnel by passing a grid-generated turbulent flow over a moving floor whose speed is matched to the freestream velocity, and then shearing it rapidly by passing it over a stationary floor further downstream. Close to the leading edge of the stationary floor, the resulting flow is expected to satisfy the approximations of the Rapid Distortion Theory and therefore would be an ideal candidate for studying linear processes in wall turbulence. We carry out pressure measurements on the wall as well as within the flow - the former using surface mounted pressure transducers and the latter using a static pressure probe similar in design to that used by Tsuji et al. (J. Fluid. Mech. 585, 2007). We also present a comparison between the rapidly sheared flow and a more conventional boundary layer subjected to a turbulent free stream. We acknowledge the financial support from EPSRC (Grant No. EP/I037938).

  17. Fluctuations in Intraocular Pressure Increase the Trabecular Meshwork Extracellular Matrix

    Directory of Open Access Journals (Sweden)

    Huan Zou

    2014-04-01

    Full Text Available Background/Aims: The trabecular meshwork (TM tissue is constantly exposed to dynamic stress caused by intraocular pressure (IOP. The effects of such biomechanical stress on the TM have not been analyzed. This study developed an animal model of fluctuating IOP and evaluated the effects of these fluctuations on TM tissue. Methods: To create fluctuation in the IOP, one eye of adult SD rats was exposed to cyclic stress with IOP fluctuation ranging from 5 mmHg to 45 mmHg at a 1/60 Hz frequency for 30 minutes every day for several weeks. The other eye was not treated and served as the control. Hematoxylin-eosin staining was used to evaluate changes in the ganglion cells and the morphology, thickness and density of the TM; immunohistochemistry was used to detect α-smooth muscle actin (α-SMA, laminin (LA and fibronectin (FN expression in the TM. Results: After several weeks of daily IOP fluctuation, the TM thickness remained unchanged, whereas the density dramatically increased. α-SMA, LA and FN were expressed in rat TM tissue, and the percentages of areas with positive expression significantly increased. The IOP was similar in the treated and control eyes and only tended to increase on day 22 of the experiment. Throughout the 28-day experiment, no ganglion cells were lost. Conclusions: Large fluctuations in IOP promoted the synthesis of α-SMA, LA and FN in the TM and increased the density of the TM, suggesting that fluctuations in IOP can induce pathological changes in the TM.

  18. Blood pressure fluctuation and hypertension in patients with Parkinson's disease

    Science.gov (United States)

    Tsukamoto, Tetsuro; Kitano, Yoshimi; Kuno, Sadako

    2013-01-01

    Objectives Blood pressure (BP) abnormalities have been known in Parkinson's disease (PD) patients. The present study aimed at determining how the BPs of PD patients fluctuate in a day. Methods A total of 37 PD patients and 44 OD (other disease) patients, all of who were inpatients, were monitored every 30 min by 24-h ambulatory blood pressure monitoring (ABPM). Results The average systolic BP and the number of patients who showed postprandial hypotension were not different between the two groups. However, occurrence of nocturnal hypertension, BP fluctuation of over 100 mmHg in a day and BP of over 200 mmHg were significantly more frequently observed in the PD patients than in the OD patients. In the PD patients, these parameters were not different between those who were suffering from the disease for less than 10 years and those with the disease for 10 years or longer, as well as between those who had a Hoehn–Yahr staging scale of 2–3 and those with a scale of 4–5. Conclusion Twenty-four-hour ABPM, not BP measurement once a day, enables us to determine the actual BP in PD patients. Although hypotension is a severe risk factor for falling and syncope, we emphasize the importance of monitoring rather hypertension and fluctuating BP in PD patients that may lead to a variety of other undesirable conditions. Management of hypotension, hypertension, and BP fluctuation is an important issue in the future. PMID:24363973

  19. Dynamic damper pressure fluctuation in the pumping systems

    Directory of Open Access Journals (Sweden)

    O.V. Korolyov

    2016-05-01

    Full Text Available Inertial part of any devices and equipment (e.g., pumps, hung or mounted on the resilient frame and being under the influence of the disturbing force that works at a constant frequency, may be subject to fluctuations, especially near of the resonance area. For elimination these fluctuations, you can resort to the use of a dynamic damper. Aim: The aim of the work is an analytical study of various dynamic dampers to reduce pressure fluctuation problems in pumping systems. Materials and Methods: A comparative analysis of efficiency of functioning was carried out for two types of dynamic dampers - hydraulic and mechanical. Results: The technique for calculating of dynamic damper of fluid pressure fluctuations in the hydraulic and mechanical pumps is presented. Algorithms of calculations are reported to engineering applications and implemented in the production process. The calculations show that the use of dynamic mechanical dampers is expedient at high frequency pumps, and, with increasing frequency of the pump by 6 times, winning in the dimensions of the damper in 3.5 times.

  20. Dynamic Pressure Fluctuations in Stepped Three-Side Spillway

    OpenAIRE

    Hamed Taghizadeh; Seyed Ali Akbar Salehi Neyshabour; Firouz Ghasemzadeh

    2012-01-01

    One type of outlet works in dams are Three-side spillways that despite of their hydraulic limitations and construction problems, they were being selected, in storage dams, as best option under specific topographical conditions. Considerable energy losses and great turbulence are hydraulic characteristic of these spillways. Hydraulic performance with targeting to reduce pressure fluctuations in side channel is an important issue in this type of spillways design. In this study, effect of steppi...

  1. The mechanisms for passive suppression of fluctuating surface pressure in a supersonic cavity flow

    Science.gov (United States)

    Dudley, Jonathan G.

    The study of the passive suppression of supersonic cavity flow using a rod immersed in the upstream boundary layer is a unique and challenging fluid mechanics problem. The flowfield includes a compressible shear layer interacting with a complex pattern of compression and expansion waves. The turbulent fluctuations inside the shear layer may be amplified through a feedback-receptivity cycle resulting in increased pressure loading on the surfaces of the cavity. Studying the mechanisms dictating the suppression of these amplified turbulent fluctuations when control is present makes for an enlightening and challenging problem. A combined experimental and time accurate numerical study using detached-eddy simulation was conducted to study the suppression of pressure fluctuations due to supersonic cavity flow at Minfinity = 1.4 over an open rectangular cavity with a length-to-depth ratio of six. In this study, the focus is confined to suppression due to a rod spoiler. The experimental measurements included temporally resolved fluctuating surface pressure measurements coupled with spatially resolved particle image velocimetry. Analysis of the fluctuating pressures on the cavity surfaces included investigations of the root-mean-square fluctuating pressure, spectral analysis, correlation and coherence analysis and joint time-frequency spectrograms. The shear layer flowfield and turbulence was studied using ensemble averaged turbulent statistics including two-point spatial turbulent velocity correlations and Proper Orthogonal Decomposition. Results indicate that the most effective suppression of the fluctuating pressures was achieved when a rod sized roughly 40% of the boundary layer was placed such that the top of the rod was near the top edge of the boundary layer. It was shown that the rod leads to a thicker shear layer that initially spreads more rapidly. The turbulent structures in the wake of the rod interact with the cavity shear layer with a time periodic excitation

  2. Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint

    Science.gov (United States)

    Panda, J.; Roozeboom, N. H.; Ross, J. C.

    2016-01-01

    The recent advancement in fast-response Pressure-Sensitive Paint (PSP) allows time-resolved measurements of unsteady pressure fluctuations from a dense grid of spatial points on a wind tunnel model. This capability allows for direct calculations of the wavenumber-frequency (k-?) spectrum of pressure fluctuations. Such data, useful for the vibro-acoustics analysis of aerospace vehicles, are difficult to obtain otherwise. For the present work, time histories of pressure fluctuations on a flat plate subjected to vortex shedding from a rectangular bluff-body were measured using PSP. The light intensity levels in the photographic images were then converted to instantaneous pressure histories by applying calibration constants, which were calculated from a few dynamic pressure sensors placed at selective points on the plate. Fourier transform of the time-histories from a large number of spatial points provided k-? spectra for pressure fluctuations. The data provides first glimpse into the possibility of creating detailed forcing functions for vibro-acoustics analysis of aerospace vehicles, albeit for a limited frequency range.

  3. Modelling wall pressure fluctuations under a turbulent boundary layer

    Science.gov (United States)

    Doisy, Yves

    2017-07-01

    The derivation of the wave vector-frequency (w-f) spectrum of wall pressure fluctuations below a turbulent boundary layer developed over a rigid flat plate is re-considered. The Lighthill's equation for pressure fluctuations is derived in a frame of reference fix with respect to the plate, at low Mach numbers, and transformed into the convected frame moving with the flow. To model the source terms of the Lighthill equation, it is assumed that in the inertial range, the turbulence is locally isotropic in the convected frame. The w-f spectrum of isotropic turbulence is obtained from symmetry considerations by extending the isotropy to space time, based on the concept of sweeping velocity. The resulting solution for the pressure w-f spectrum contains a term (the mean shear-turbulence term) which does not fulfill the Kraichnan Philipps theorem, due to the form of the selected turbulent velocity spectrum. The viscous effects are accounted for by a cut-off depending on wall distance; this procedure allows extending the model beyond the inertial range contribution. The w-f pressure spectrum is derived and compared to the experimental low wavenumber data of Farabee and Geib (1991) [8] and Bonness et al. (2010) [5], for which a good agreement is obtained. The derived expression is also compared to Chase theoretical model Chase (1987) [6] and found to agree well in the vicinity of the convective ridge of the subsonic domain and to differ significantly both in supersonic and subsonic low wavenumber limits. The pressure spectrum derived from the model and its scaling are discussed and compared to experimental data and to the empirical model of Goody (2002) [23], which results from the compilation of a large set of experimental data. Very good agreement is obtained, except at vanishing frequencies where it is claimed that the experimental results lack of significance due to the limited size of the experimental facilities. This hypothesis supported by the results obtained from

  4. Decoupling Analysis on Pressure Fluctuation and Needle Valve Response for High Pressure Common Rail Injector

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    Hao Wang

    2017-01-01

    Full Text Available In the process of multiple injections, the influence of different injections makes the controlling of cycle fuel injection quantity more difficult. The high pressure common rail (HPCR simulation model is established in AMESim environment. Through the method of combining numerical simulation and experiment test, it is found that the strong coupling of pressure fluctuation and needle valve response is the fundamental reason, which leads to the fluctuation of main injection fuel quantity (MIFQ with dwell time (DT. The result shows that the largest fluctuation quantity is 3.6mm3 when the reference value of main injection is 60.0mm3. Non-damping LC hydraulic system model is also established. Through the analysis of the model, reducing the length-diameter ratio of internal oil duct and the delivery chamber volume are decoupling methods to the strong coupling.

  5. Measurement of Turbulent Pressure and Temperature Fluctuations in a Gas Turbine Combustor

    Science.gov (United States)

    Povinelli, Louis (Technical Monitor); LaGraff, John E.; Bramanti, Cristina; Pldfield, Martin; Passaro, Andrea; Biagioni, Leonardo

    2004-01-01

    The report summarizes the results of the redesign efforts directed towards the gas-turbine combustor rapid-injector flow diagnostic probe developed under sponsorship of NASA-GRC and earlier reported in NASA-CR-2003-212540. Lessons learned during the theoretical development, developmental testing and field-testing in the previous phase of this research were applied to redesign of both the probe sensing elements and of the rapid injection device. This redesigned probe (referred to herein as Turboprobe) has been fabricated and is ready, along with the new rapid injector, for field-testing. The probe is now designed to capture both time-resolved and mean total temperatures, total pressures and, indirectly, one component of turbulent fluctuations.

  6. Investigation of the spatial variability and possible origins of wind-induced air pressure fluctuations responsible for pressure pumping

    Science.gov (United States)

    Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Zeeman, Matthias; Longdoz, Bernard; Schindler, Dirk

    2017-04-01

    The exchange of greenhouse gases between the soil and the atmosphere is highly relevant for the climate of the Earth. Recent research suggests that wind-induced air pressure fluctuations can alter the soil gas transport and therefore soil gas efflux significantly. Using a newly developed method, we measured soil gas transport in situ in a well aerated forest soil. Results from these measurements showed that the commonly used soil gas diffusion coefficient is enhanced up to 30% during periods of strong wind-induced air pressure fluctuations. The air pressure fluctuations above the forest floor are only induced at high above-canopy wind speeds (> 5 m s-1) and lie in the frequency range 0.01-0.1 Hz. Moreover, the amplitudes of air pressure fluctuations in this frequency range show a clear quadratic dependence on mean above-canopy wind speed. However, the origin of these wind-induced pressure fluctuations is still unclear. Airflow measurements and high-precision air pressure measurements were conducted at three different vegetation-covered sites (conifer forest, deciduous forest, grassland) to investigate the spatial variability of dominant air pressure fluctuations, their origin and vegetation-dependent characteristics. At the conifer forest site, a vertical profile of air pressure fluctuations was measured and an array consisting of five pressure sensors were installed at the forest floor. At the grassland site, the air pressure measurements were compared with wind observations made by ground-based LIDAR and spatial temperature observations from a fibre-optic sensing network (ScaleX Campaign 2016). Preliminary results show that at all sites the amplitudes of relevant air pressure fluctuations increase with increasing wind speed. Data from the array measurements reveal that there are no time lags between the air pressure signals of different heights, but a time lag existed between the air pressure signals of the sensors distributed laterally on the forest floor

  7. Prediction of pressure fluctuation of a hydraulic turbine at no-load condition

    Science.gov (United States)

    Chen, T. J.; Wu, X. J.; Liu, J. T.; Wu, Y. L.

    2015-01-01

    In order to study characteristics of pressure fluctuation of a turbine during the starting period, a turbine with guide vanes device at no-load condition was investigated using RNG k-epsilon turbulence model. The inner flow distribution and pressure fluctuation characteristics were analyzed. Results show that the pressure fluctuations in the region between the runner and guide vanes are different around the runner inlet. The dominant frequency of pressure fluctuation in the vaneless space close to the casing outlet is the blade passing frequency, while the dominant frequency at the rest region is the twice of the blade passing frequency. The increase of amplitude of pressure fluctuation close to the casing outlet can be attribute to the large scale stall at suction side of the runner inlet.

  8. Effects of rapid temperature fluctuations prior to breeding on reproductive efficiency in replacement gilts

    Science.gov (United States)

    Recently, we determined that rapidly cooling pigs after acute heat stress (HS) resulted in a pathological condition, and because rapid temperature fluctuations are often associated with reduced reproductive success in sows it lends itself to the hypothesis that these conditions may be linked. Study ...

  9. Numerical Simulation of Pressure Fluctuation around the Tongue Region in a Centrifugal Pump

    Science.gov (United States)

    Zheng, L. L.; Dou, H.-S.; Chen, X. P.; Zhu, Z. C.; Cui, B. L.

    2016-11-01

    Pressure fluctuation near the tongue is one of the primary sources of pump vibration and noise. In order to investigate the effect of pressure fluctuation near the tongue, the RANS equations and the RNG k-epsilon turbulence model are employed to simulate the flow in the pump. The SIMPLE algorithm is applied to couple the solutions of the system of equations. Flow field within the centrifugal pump under different flow rates are obtained by simulation. The simulation results are compared with the experimental data to verify the reliability of the calculation model. It is found that the pressure fluctuation at each monitor point is a periodic wave but non-uniform under small flow rate. When the flow rate is larger than the design flow rate, average pressure and standard deviation at monitor points is relative uniform. The dominate frequency of pressure fluctuation is the blade passing frequency and the amplitude of pressure fluctuation is regular. At small flow rate, complex unstable flow makes average pressure and standard deviation at monitor points increasing obviously. Amplitude of pressure fluctuation is larger than that of design flow rate conditions and the maximum amplitude of pressure fluctuation in frequency domain exists at the monitor point just behind the tongue along the impeller rotation direction.

  10. STUDY OF IDENTIFICATION OF TWO-PHASE FLOW PARAMETERS BY PRESSURE FLUCTUATION ANALYSIS

    Directory of Open Access Journals (Sweden)

    Ondrej Burian

    2016-12-01

    Full Text Available This paper deals with identification of parameters of simple pool boiling in a vertical rectangular channel by analysis of pressure fluctuation. In this work is introduced a small experimental facility about 9 kW power, which was used for simulation of pool boiling phenomena and creation of steam-water volume. Several pressure fluctuations measurements and differential pressure fluctuations measurements at warious were carried out. Main changed parameters were power of heaters and hydraulics resistance of channel internals. Measured pressure data was statistically analysed and compared with goal to find dependencies between parameters of two-phase flow and statistical properties of pressure fluctuation. At the end of this paper are summarized final results and applicability of this method for parameters determination of two phase flow for pool boiling conditions at ambient pressure.

  11. Evaluation of the diurnal intraocular pressure fluctuations and blood pressure under dehydration due to fasting

    Directory of Open Access Journals (Sweden)

    Gonen Baser

    2016-12-01

    Full Text Available Introduction: This study aimed to investigate the diurnal intraocular pressure fluctuations under dehydration conditions and the relationship between the intraocular pressure fluctuations and blood pressure. Methods: The intraocular pressures (IOP, body weights, as well as systolic and diastolic blood pressures (SBP, DBP of 36 fasting healthy volunteers were recorded at 8:00 a.m. and 5:00 p.m. in the Ramadan of 2014 and two weeks after it. The data were analyzed using paired Student’s t-test and Pearson correlation analysis. Results: As the results demonstrated, the mean diurnal IOP differences of IOP, SBP, DBP, and weight were 2.67±1.33 mmHg, 9.44±8.02 mmHg, 3.33±5.94 mmHg, and 0.90±0.46 kg during the fasting period, respectively. In addition, the mean diurnal IOP differences of IOP, SBP, DBP, and weight were -0.33±1.4 mmHg (P=0.001, 0.55±7.25mmHg (P=0.003, -3.33±5.94 mmHg (P=0.001, and 0.12±0.45 kg (P=0.001 during the control period, respectively. There was a moderate correlation between the diurnal IOP and SBP differences (r=0.517, P=0.028. Conclusion: Based on the findings of the current study, the total fluid volume might have a more dominant effect on IOP peaks than the sympathetic system activity. Furthermore, the SBP was found to correlate with the IOP.

  12. Multi-particle long-range rapidity correlations from fluctuation of the fireball longitudinal shape

    OpenAIRE

    Bzdak, Adam; Bozek, Piotr

    2015-01-01

    We calculate the genuine long-range multi-particle rapidity correlation functions, $C_{n}(y_1,...,y_n)$ for $n=3,4,5,6$, originating from fluctuations of the fireball longitudinal shape. In these correlation functions any contribution from the short-range two-particle correlations, and in general up to $(n-1)$-particle in $C_n$, is suppressed. The information about the fluctuating fireball shape in rapidity is encoded in the cumulants of coefficients of the orthogonal polynomial expansion of ...

  13. Non-Gaussian PDF Modeling of Turbulent Boundary Layer Fluctuating Pressure Excitation

    Science.gov (United States)

    Steinwolf, Alexander; Rizzi, Stephen A.

    2003-01-01

    The purpose of the study is to investigate properties of the probability density function (PDF) of turbulent boundary layer fluctuating pressures measured on the exterior of a supersonic transport aircraft. It is shown that fluctuating pressure PDFs differ from the Gaussian distribution even for surface conditions having no significant discontinuities. The PDF tails are wider and longer than those of the Gaussian model. For pressure fluctuations upstream of forward-facing step discontinuities and downstream of aft-facing step discontinuities, deviations from the Gaussian model are more significant and the PDFs become asymmetrical. Various analytical PDF distributions are used and further developed to model this behavior.

  14. Numerical Investigation of Pressure Fluctuation Characteristics in a Centrifugal Pump with Variable Axial Clearance

    Directory of Open Access Journals (Sweden)

    Lei Cao

    2016-01-01

    Full Text Available Clearance flows in the sidewall gaps of centrifugal pumps are unsteady as well as main flows in the volute casing and impeller, which may cause vibration and noise, and the corresponding pressure fluctuations are related to the axial clearance size. In this paper, unsteady numerical simulations were conducted to predict the unsteady flows within the entire flow passage of a centrifugal pump operating in the design condition. Pressure fluctuation characteristics in the volute casing, impeller, and sidewall gaps were investigated with three axial clearance sizes. Results show that an axial clearance variation affects the pressure fluctuation characteristics in each flow domain by different degree. The greatest pressure fluctuation occurs at the blade pressure surface and is almost not influenced by the axial clearance variation which has a certainly effect on the pressure fluctuation characteristics around the tongue. The maximum pressure fluctuation amplitude in the sidewall gaps is larger than that in the volute casing, and different spectrum characteristics show up in the three models due to the interaction between the clearance flow and the main flow as well as the rotor-stator interaction. Therefore, clearance flow should be taken into consideration in the hydraulic design of centrifugal pumps.

  15. On parton number fluctuations at various stages of the rapidity evolution

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, A.H. [Department of Physics, Columbia University, New York (United States); Munier, S., E-mail: Stephane.Munier@polytechnique.edu [Centre de physique théorique, École Polytechnique, CNRS, Palaiseau (France)

    2014-10-07

    Starting with the interpretation of parton evolution with rapidity as a branching–diffusion process, we describe the different kinds of fluctuations of the density of partons which affect the properties of QCD scattering amplitudes at moderately high energies. We then derive some of these properties as direct consequences of the stochastic picture. We get new results on the expression of the saturation scale of a large nucleus, and a modified geometric scaling valid at intermediate rapidities for dipole–dipole scattering.

  16. The study of pressure fluctuations in the pressure line of the pump and of the efficiency of the vibration absorbers

    Directory of Open Access Journals (Sweden)

    O.V. Korolyov

    2016-12-01

    Full Text Available The article presents the results of experimental studies of pressure fluctuations in the pipes of piston pumps. The relevance of these studies is due to the need to reduce the pressure fluctuations that create a positive displacement pumps, due to their negative impact not only on the reliability of the pump, but the accuracy of flow measurement and pressure of the medium supplied to such pumps. Aim: The aim of this study was to investigate the hydraulic characteristics of pulsating flows in pressure lines piston pumps of liquefied gas, as well as the study of the effectiveness of the dampers of pressure pulsations and conformity of their parameters to the calculation. Materials and Methods: As a drive used the piston pumps − single-line and trilinear. In the tests recorded pressure fluctuations in the pressure line. For this purpose the low-inertia pressure sensors 15.0 MPa working complete with strain test station, which allows registering the pressure fluctuations at frequencies up to 10 kHz. Strain test station output signal fed to the input of the oscilloscope operating in memory mode. In all tests the pressure sensor is mounted at three points - after the piston group on the pressure line before the damping device and after it. In the experiment, three different damper was used - two new, designed by the author's method and one regular damper, which are equipped with serial piston pumps. Dampers installed vertically, the flow entering to the lower cap, and an output through the side surface. Results: The experimental results confirmed the general position of the greater efficiency of complex composite filters and the correctness of chosen method of their calculation, proposed earlier by the authors. In particular, the actual level of weakening of pressure fluctuations on developed damper with a high degree coincided with the calculated results.

  17. Airfoil Trailing Edge Noise Generation and Its Surface Pressure Fluctuation

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong

    2015-01-01

    where the time history pressure data are recorded by the surface pressure microphones. After the flow-field is stabilized, the generated noise from the airfoil Trailing Edge (TE) is predicted using the acoustic analogy solver, where the results from LES are the input. It is found that there is a strong...

  18. Analysis of Numerical Simulation Database for Pressure Fluctuations Induced by High-Speed Turbulent Boundary Layers

    Science.gov (United States)

    Duan, Lian; Choudhari, Meelan M.

    2014-01-01

    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 pressure fluctuations and their dependence on wall temperature. Simulations indicate that the influence of wall temperature on pressure fluctuations is largely limited to the near-wall region, with the characteristics of wall-pressure fluctuations showing a strong temperature dependence. Wall temperature has little influence on the propagation speed of the freestream pressure signal. The freestream radiation intensity compares well between wall-temperature cases when normalized by the local wall shear; the propagation speed of the freestream pressure signal and the orientation of the radiation wave front show little dependence on the wall temperature.

  19. Fluctuation of a Piston in Vacuum Induced by Thermal Radiation Pressure

    Science.gov (United States)

    Inui, Norio

    2017-10-01

    We consider the displacement of a piston dividing a vacuum cavity at a finite temperature T induced by fluctuations in the thermal radiation pressure. The correlation function of the thermal radiation pressure is calculated using the theoretical framework developed by Barton, which was first applied to the fluctuation of the Casimir force at absolute zero. We show that the variance of the radiation pressure at a fixed point is proportional to T8 and evaluate the mean square displacement for a piston with a small cross section in a characteristic correlation timescale ħ/(kBT). At room temperature, the contribution of the thermal radiation to the fluctuation is larger than that of the vacuum fluctuation.

  20. The pressure and entropy of a unitary Fermi gas with particle-hole fluctuation

    Science.gov (United States)

    Gong, Hao; Ruan, Xiao-Xia; Zong, Hong-Shi

    2018-01-01

    We calculate the pressure and entropy of a unitary Fermi gas based on universal relations combined with our previous prediction of energy which was calculated within the framework of the non-self-consistent T-matrix approximation with particle-hole fluctuation. The resulting entropy and pressure are compared with the experimental data and the theoretical results without induced interaction. For entropy, we find good agreement between our results with particle-hole fluctuation and the experimental measurements reported by ENS group and MIT experiment. For pressure, our results suffer from a systematic upshift compared to MIT data.

  1. Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

    Directory of Open Access Journals (Sweden)

    Manuel Mohr

    2016-10-01

    Full Text Available High-precision differential air pressure measurements were conducted in the below-canopy space of a Scots pine forest and in the forest soil to investigate small air pressure fluctuations and their effect on soil gas flux. In addition to air pressure measurements, tracer gas concentration in the soil and airflow characteristics above and below the canopy were measured. Results suggest that air pressure fluctuations in the frequency range of 0.01 Hz–0.1 Hz are strongly dependent on above-canopy wind speed. While amplitudes of the observed air pressure fluctuations (<10 Pa increase significantly with increasing above-canopy wind speed, the periods decrease significantly with increasing above-canopy wind speed. These air pressure fluctuations are associated with the pressure-pumping effect in the soil. A pressure-pumping coefficient was defined, which describes the strength of the pressure-pumping effect. During the measurement period, pressure-pumping coefficients up to 0.44 Pa·s−1 were found. The dependence of the pressure-pumping coefficient on mean above-canopy wind speed can be described well with a polynomial fit of second degree. The knowledge of this relation simplifies the quantification of the pressure-pumping effect in a Scots pine forest considerably, since only the mean above-canopy wind speed has to be measured. In addition, empirical modeling revealed that the pressure-pumping coefficient explains the largest fraction of the variance of tracer gas concentration in the topsoil.

  2. Wall Pressure Fluctuations and Acoustics in Turbulent Pipe Flow

    Science.gov (United States)

    1986-09-01

    finite-sized %’*’• pressure sensors--which average over space --need to be at least as small as the smallest eddies; otherwise, an attenuation of the...high-frequency (small wavelength) spectral contributions (particularly those in this convective ridge) will occur. Kolmogoroff (see Hinze, 1959. for

  3. On parton number fluctuations at various stages of the rapidity evolution

    Directory of Open Access Journals (Sweden)

    A.H. Mueller

    2014-10-01

    Full Text Available Starting with the interpretation of parton evolution with rapidity as a branching–diffusion process, we describe the different kinds of fluctuations of the density of partons which affect the properties of QCD scattering amplitudes at moderately high energies. We then derive some of these properties as direct consequences of the stochastic picture. We get new results on the expression of the saturation scale of a large nucleus, and a modified geometric scaling valid at intermediate rapidities for dipole–dipole scattering.

  4. Time series analysis of pressure fluctuation in gas-solid fluidized beds

    Directory of Open Access Journals (Sweden)

    C. Alberto S. Felipe

    2004-09-01

    Full Text Available The purpose of the present work was to study the differentiation of states of typical fluidization (single bubble, multiple bubble and slugging in a gas-solid fluidized bed, using spectral analysis of pressure fluctuation time series. The effects of the method of measuring (differential and absolute pressure fluctuations and the axial position of the probes in the fluidization column on the identification of each of the regimes studied were evaluated. Fast Fourier Transform (FFT was the mathematic tool used to analysing the data of pressure fluctuations, which expresses the behavior of a time series in the frequency domain. Results indicated that the plenum chamber was a place for reliable measurement and that care should be taken in measurement in the dense phase. The method allowed fluid dynamic regimes to be differentiated by their dominant frequency characteristics.

  5. Chaotic dynamic characteristics of pressure fluctuation signals in hydro-turbine

    Energy Technology Data Exchange (ETDEWEB)

    Su, Wen Tao; An, Shi [School of Management, Harbin Institute of Technology, Harbin (China); Li, Xiao Bin; Lan, Chao Feng; Li, Feng Chen [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin (China); Wang, Jian Sheng [Ministry of Education of China, Tianjin (China)

    2016-11-15

    The pressure fluctuation characteristics in a Francis hydro-turbine running at partial flow conditions were studied based on the chaotic dynamic methods. Firstly, the experimental data of pressure fluctuations in the draft tube at various flow conditions was de-noised using lifting wavelet transformation, then, for the de-noised signals, their spectrum distribution on the frequency domain, the energy variation and the energy partition accounting for the total energy was calculated. Hereby, for the flow conditions ranging from no cavitation to severe cavitation, the chaos dynamic features of fluctuation signals were analyzed, including the temporal-frequency distribution, phase trajectory, Lyapunov exponent and Poincaré map etc. It is revealed that, the main energy of pressure fluctuations in the draft tube locates at low-frequency region. As the cavitation grows, the amplitude of power spectrum at frequency domain becomes larger. For all the flow conditions, all the maximal Lyapunov exponents are larger than zero, and they increase with the cavitation level. Therefore, it is believed that there indeed exist the chaotic attractors in the pressure fluctuation signals for a hydro-turbine.

  6. New insights from well responses to fluctuations in barometric pressure.

    Science.gov (United States)

    Butler, J J; Jin, W; Mohammed, G A; Reboulet, E C

    2011-01-01

    Hydrologists have long recognized that changes in barometric pressure can produce changes in water levels in wells. The barometric response function (BRF) has proven to be an effective means to characterize this relationship; we show here how it can also be utilized to glean valuable insights into semi-confined aquifer systems. The form of the BRF indicates the degree of aquifer confinement, while a comparison of BRFs between wells sheds light on hydrostratigraphic continuity. A new approach for estimating hydraulic properties of aquitards from BRFs has been developed and verified. The BRF is not an invariant characteristic of a well; in unconfined or semi-confined aquifers, it can change with conditions in the vadose zone. Field data from a long-term research site demonstrate the hydrostratigraphic insights that can be gained from monitoring water levels and barometric pressure. Such insights should be of value for a wide range of practical applications. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

  7. Analysis on the blade inlet pressure fluctuation of the centrifugal pump based on LES

    Science.gov (United States)

    Wang, W. J.; Cui, Y. R.; Wang, Y.; Li, G. D.; Liang, Q. H.; Yin, G.

    2013-12-01

    In order to study the characteristics of the blade inlet pressure fluctuation under unsteady flow in centrifugal pump, a three-dimensional model of a pump ns=50 was built. Based on large eddy simulation (LES), the inner flow field of the pump was simulated by the flow field simulation software Fluent in design condition and off-design conditions. The pressure fluctuation of the monitored points was obtained at the blade suction surface and pressure surface at impeller inlet, which was analyzed by time and frequency domain with Fast Fourier Transformation (FFT). The results show that the pressure fluctuation of inlet and outlet in large flow rate is more obvious than low flow rate. It is easily found that the static pressure of outlet in 1.2Qd condition has five peaks and five valleys, but this phenomenon does not exist in 0.6 Qd condition. In the time domain spectrums, the static pressure curve has five peaks and five valleys that the maximum pressure is positive number and the minimum pressure is negative number. In the frequency domains spectrums, the frequency of FFT factors peak is lower than the blade passing frequency 241.65Hz.

  8. Atypical Miller Fisher Syndrome with Anisocoria and Rapidly Fluctuating Pupillary Diameter

    Directory of Open Access Journals (Sweden)

    Garima Gupta

    2015-01-01

    Full Text Available Miller Fisher syndrome is a variant of Guillain-Barre syndrome characterized by the classic triad of ophthalmoplegia, ataxia, and areflexia. Pupillary involvement is common in MFS and has been reported in 35–42% of MFS patients. Although case reports have discussed isolated ophthalmoplegia as a presentation of MFS, anisocoria and rapid fluctuation of pupillary diameter have not been reported in anti-GQ1b antibody positive individuals. Here we describe an individual who presented with diplopia and was found to have progressive internal and external ophthalmoplegia with frequent fluctuations in pupillary diameter and anisocoria. These exam findings are not commonly described even in atypical presentations of MFS. The onset of symptoms was preceded by an upper respiratory infection but no gastrointestinal symptoms. Imaging and CSF studies were unremarkable; however serum levels of immunoglobulin G anti-GQ1b antibody and anti-GAD antibody were elevated confirming the diagnosis of MFS. The patient was treated with IVIG and intravenous steroids with mild resolution of external ophthalmoplegia. He did not go on to develop more typical features of MFS such as ataxia or areflexia. This demonstrates that isolated external and internal ophthalmoparesis with rapidly fluctuating pupillary diameter and associated anisocoria can be the sole manifestation of atypical MFS.

  9. Effects of pressure fluctuations on the combustion process in turbulent premixed flames

    Science.gov (United States)

    Beardsell, Guillaume; Lapointe, Simon; Blanquart, Guillaume

    2016-11-01

    The need for a thorough understanding of turbulence-combustion interactions in compressible flows is driven by recent technological developments in propulsion as well as renewed interest in the development of next generation supersonic and hypersonic vehicles. In such flows, pressure fluctuations displaying a wide range of length and timescales are present. These fluctuations are expected to impact the combustion process to varying degrees, depending amongst other things on the amplitude of the pressure variations and the timescales of the chemical reactions taking place in the flame. In this context, numerical simulations of these flows can provide insight into the impact of pressure fluctuations on the combustion process. In the present work, we analyze data from simulations of statistically-flat premixed n-heptane/air flames at high Karlovitz numbers. The compressible Navier-Stokes equations are solved exactly (DNS) and results obtained with both detailed kinetic modeling and one-step chemistry are considered. The effects of pressure fluctuations on the fuel burning rate are investigated. The findings are compared with results obtained from simulations of one-dimensional premixed flames subjected to various pressure waves.

  10. Circadian Intraocular Pressure Fluctuation and Disease Progression in Primary Angle Closure Glaucoma.

    Science.gov (United States)

    Tan, Shaoying; Yu, Marco; Baig, Nafees; Chan, Poemen Pui-man; Tang, Fang Yao; Tham, Clement C

    2015-07-01

    To document the continuous circadian intraocular pressure (IOP) fluctuation using a contact lens sensor during normal daily activities, and to study the relationship between IOP fluctuation and disease progression in primary angle closure glaucoma (PACG) eyes. Circadian IOP fluctuations were recorded by Sensimed Triggerfish sensors in 25 PACG eyes. The sensor output signals were smoothed using B-spline smoothing transform and described by functional data analysis. Glaucoma progression was documented with serial changes in mean deviation (MD) and visual field index (VFI) in Humphrey automated perimetry and retinal nerve fiber layer (RNFL) thickness. The signals were compared between the progressive and stable groups by permutation tests on functional t-statistic. Statistically significant differences were found from 2200 to 2300 and from 0700 to 0800 in gradients of the IOP fluctuation curve, as well as from 2300 to 2400 and 0800 to 0900 in curvatures of the IOP fluctuation curves, between the progressive MD and stable MD groups (P < 0.05). Significant gradient differences were also found from 1500 to 1600 and 0600 to 0800 between the progressive VFI and stable VFI groups, and from 2400 to 0100 and 0200 to 0300 between the progressive RNFL and stable RNFL groups (P < 0.05). Significant differences in circadian IOP fluctuation between progressive and stable PACG eyes were identified. Large IOP fluctuations may be associated with disease progression in PACG eyes.

  11. Pore Pressure Response to Groundwater Fluctuations in Saturated Double-Layered Soil

    Directory of Open Access Journals (Sweden)

    Hongwei Ying

    2015-01-01

    Full Text Available Analytical solutions are developed for one-dimensional consolidation of double-layered saturated soil subjected to groundwater fluctuations. The solutions are derived by an explicit mathematical procedure using Duhamel’s theorem in conjunction with a Fourier series, when groundwater fluctuation is described by a general time-dependent function and assumed to be the pore water pressure variations at the upper boundary. Taking as an example the harmonic groundwater fluctuation, the relevant response of the excess pore water pressure is discussed in detail, and the main influencing factors of the excess pore pressure distribution are analyzed. A dimensionless parameter θ has been introduced because it significantly affects the phase and the amplitude of excess pore pressures. The influences of the coefficients of permeability and compressibility of soil on the excess pore pressure distribution are different and cannot be incorporated into the coefficient of consolidation in double-layered soil. The relative permeability ratio of two clayey soils also plays an important role on the curves of the distributions of the excess pore pressures. The effects of the thickness of the soil layer on the excess pore pressure distribution should be considered together with the dimensionless parameter θ and the permeability and compressibility of the double-layered soil system.

  12. An energy harvesting system utilizing wind pressure fluctuations on high-rise building envelope

    Science.gov (United States)

    Park, Jae-Chan; Kim, In-Ho; Jang, Seon-Jun; Jung, Hyung-Jo

    2017-04-01

    In this paper, the new energy harvesting system is proposed by using wind pressure fluctuations which are one of existing energy sources that were not taken into consideration around high-rise buildings. The proposed system carries out the role of building envelope also. This research is divided in two parts. At first, Computational Fluid Dynamics (CFD) and wind tunnel experiments are performed for investigating the wind pressure that occur around the high-rise building. Secondly, based on the result of wind pressure analysis, the optimal mechanism is devised and the prototype of the energy harvesting system is designed to verify the possibility of utilization of wind pressure fluctuations through the small wind tunnel experiment, harmonic excitation experiment and numerical analysis. As a result, the performance of proposed energy harvesting system is numerically and experimentally validated.

  13. Buffering blood pressure fluctuations by respiratory sinus arrhythmia may in fact enhance them: a theoretical analysis

    CERN Document Server

    Buchner, Teodor; Gielerak, Grzegorz

    2010-01-01

    Using a three-compartment model of blood pressure dynamics, we analyze theoretically the short term cardiovascular variability: how the respiratory-related blood pressure fluctuations are buffered by appropriate heart rate changes: i.e. the respiratory sinus arrhythmia. The buffering is shown to be crucially dependent on the time delay between the stimulus (such as e.g. the inspiration onset) and the application of the control (the moment in time when the efferent response is delivered to the heart). This theoretical analysis shows that the buffering mechanism is effective only in the upright position of the body. It explains a paradoxical effect of enhancement of the blood pressure fluctuations by an ineffective control. Such a phenomenon was observed experimentally. Using the basis of the model, we discuss the blood pressure variability and heart rate variability under such clinical conditions as the states of expressed adrenergic drive and the tilt-test during the parasympathetic blockade or fixed rate atr...

  14. Energy harvesting from cerebrospinal fluid pressure fluctuations for self-powered neural implants.

    Science.gov (United States)

    Beker, Levent; Benet, Arnau; Meybodi, Ali Tayebi; Eovino, Ben; Pisano, Albert P; Lin, Liwei

    2017-06-01

    In this paper, a novel method to generate electrical energy by converting available mechanical energy from pressure fluctuations of the cerebrospinal fluid within lateral ventricles of the brain is presented. The generated electrical power can be supplied to the neural implants and either eliminate their battery need or extend the battery lifespan. A diaphragm type harvester comprised of piezoelectric material is utilized to convert the pressure fluctuations to electrical energy. The pressure fluctuations cause the diaphragm to bend, and the strained piezoelectric materials generate electricity. In the framework of this study, an energy harvesting structure having a diameter of 2.5 mm was designed and fabricated using microfabrication techniques. A 1:1 model of lateral ventricles was 3D-printed from raw MRI images to characterize the harvester. Experimental results show that a maximum power of 0.62 nW can be generated from the harvester under similar physical conditions in lateral ventricles which corresponds to energy density of 12.6 nW/cm2. Considering the available area within the lateral ventricles and the size of harvesters that can be built using microfabrication techniques it is possible to amplify to power up to 26 nW. As such, the idea of generating electrical energy by making use of pressure fluctuations within brain is demonstrated in this work via the 3D-printed model system.

  15. Pressure Dependence of the Critical Fluctuations in the Singlet-Ground-State System, Pr3TI

    DEFF Research Database (Denmark)

    Kjems, Jørgen; Nielsen, Mourits; Buyers, W. J. L

    1979-01-01

    The pressure dependence of the magnetization and of the critical fluctuations in a polycrystalline sample of Pr3Tl have been studied by neutron scattering. Above Tc the quasielastic intensity is better reproduced by a theory In which the excitons are strongly damped by the conduction electrons th...

  16. Simultaneous optimization of spin fluctuations and superconductivity under pressure in an iron-based superconductor.

    Science.gov (United States)

    Ji, G F; Zhang, J S; Ma, Long; Fan, P; Wang, P S; Dai, J; Tan, G T; Song, Y; Zhang, C L; Dai, Pengcheng; Normand, B; Yu, Weiqiang

    2013-09-06

    We present a high-pressure NMR study of the overdoped iron pnictide superconductor NaFe0.94Co0.06As. The low-energy antiferromagnetic spin fluctuations in the normal state, manifest as the Curie-Weiss upturn in the spin-lattice relaxation rate 1/(75)T1T, first increase strongly with pressure but fall again at P>Popt=2.2  GPa. Neither long-ranged magnetic order nor a structural phase transition is encountered up to 2.5 GPa. The superconducting transition temperature Tc shows a pressure dependence identical to the spin fluctuations. Our observations demonstrate that magnetic correlations and superconductivity are optimized simultaneously as a function of the electronic structure, thereby supporting very strongly a magnetic origin of superconductivity.

  17. Numerical Investigation of Pressure Fluctuation in Centrifugal Pump Volute Based on SAS Model and Experimental Validation

    Directory of Open Access Journals (Sweden)

    Qiaorui Si

    2014-02-01

    Full Text Available This paper presents an investigation of pressure fluctuation of a single-suction volute-type centrifugal pump, particularly volute casing, by using numerical and experimental methods. A new type of hybrid Reynolds-averaged Navier-Stokes/Large Eddy Simulation, referred to as the shear stress transport-scale-adaptive simulation (SAS model, is employed to study the unsteady flow. Statistical analysis method is adopted to show the pressure fluctuation intensity distribution in the volute channel. A test rig for pressure pulsation measurement is built to validate the numerical simulation results using eight transient pressure sensors in the middle section of the volute wall. Results show that the SAS model can accurately predict the inner flow field of centrifugal pumps. Radial force acting on the impeller presents a star distribution related to the blade number. Pressure fluctuation intensity is strongest near the tongue and shows irregular distribution in the pump casing. Pressure fluctuation is distributed symmetrically at the cross-section of the volute casing because the volute can eliminate the rotational movement of the liquid discharged from the impeller. Blade passing frequency and its multiples indicate the dominant frequency of the monitoring points within the volute, and the low-frequency pulsation, particularly in the shaft component, increases when it operates at off-design condition, particularly with a small flow rate. The reason is that the vortex wave is enhanced at the off-design condition, which has an effect on the axle and is presented in the shaft component in the frequency domain.

  18. Optimal operation of rapid pressure swing adsorption with slop recycling

    NARCIS (Netherlands)

    Betlem, Bernardus H.L.; Gotink, R.W.M.; Bosch, H.

    1998-01-01

    Rapid pressure swing adsorption (RPSA) is a cyclic process operating, basically, in three phases: a pressurization, a delay, and a depressurization phase. A new, modified operation is suggested by the addition of either a raffinate recycle phase or an extract recycle phase, during which raffinate

  19. Power spectral analysis of blood pressure fluctuations during sleep in normal and decerebrate cats.

    Science.gov (United States)

    Kanamori, N; Sakai, K; Sei, H; Salvert, D; Vanni-Mercier, G; Yamamoto, M; Jouvet, M

    1994-03-01

    Arterial blood pressure fluctuations during sleep were investigated with power analysis technique in both normal and decerebrate cats. In the initial postoperative stage lasting about 3 to 4 days, intact cats displayed, during paradoxical sleep, phasic increases in arterial blood pressure which were superimposed on a tonic hypotension. In the later chronic stage, however, the animals showed the phasic hypertension being superimposed on the background of a tonic hypertension. Regardless of these stages, the blood pressure during paradoxical sleep exhibited a 1/f-like spectrum, expressed by the power spectral density which is inversely proportional to the Fourier frequency f. On the other hand, a power spectral profile of the blood pressure during slow wave sleep presented a white noise-like pattern within the same frequency range of 0.1-0.01 Hz. After brainstem transections at the pontomesencephalic border, the cats exhibited consistently a sustained fall in blood pressure during paradoxical sleep and the power spectral density of the blood pressure displayed a white noise-like pattern throughout the survival periods of one month or more. These observations indicate that the blood pressure fluctuations in the 1/f spectrum during paradoxical sleep originate in rostral brain structures.

  20. Rapid fluctuations of the air and surface temperature in the city of Bucharest (Romania)

    Science.gov (United States)

    Cheval, Sorin; Dumitrescu, Alexandru; Hustiu, Mihaita-Cristinel

    2016-04-01

    Urban areas derive significant changes of the ambient temperature generating specific challenges for society and infrastructure. Extreme temperature events, heat and cold waves affect the human comfort, increase the health risk, and require specific building regulations and emergency preparedness, strongly related to the magnitude and frequency of the thermal hazards. Rapid changes of the temperature put a particular stress for the urban settlements, and the topic has been approached constantly in the scientific literature. Due to its geographical position in a plain area with a temperate climate and noticeable continental influence, the city of Bucharest (Romania) deals with high seasonal and daily temperature variations. However, rapid fluctuations also occur at sub-daily scale caused by cold or warm air advections or by very local effects (e.g. radiative heat exchange, local precipitation). For example, in the area of Bucharest, the cold fronts of the warm season may trigger temperature decreasing up to 10-15 centigrades / hour, while warm advections lead to increasing of 1-2 centigrades / hour. This study focuses on the hourly and sub-hourly temperature variations over the period November 2014 - February 2016, using air temperature data collected from urban sensors and meteorological stations of the national network, and land surface temperature data obtained from satellite remote sensing. The analysis returns different statistics, such as magnitude, intensity, frequency, simultaneous occurrence and areal coverage of the rapid temperature fluctuations. Furthermore, the generating factors for each case study are assessed, and the results are used to define some preliminary patterns and enhance the urban temperature forecast at fine scale. The study was funded by the Romanian Programme Partnership in Priority Domains, PN - II - PCCA - 2013 - 4 - 0509 - Reducing UHI effects to improve urban comfort and balance energy consumption in Bucharest (REDBHI).

  1. RANS simulation of cavitation and hull pressure fluctuation for marine propeller operating behind-hull condition

    Directory of Open Access Journals (Sweden)

    Kwang-Jun Paik

    2013-12-01

    Full Text Available Simulations of cavitation flow and hull pressure fluctuation for a marine propeller operating behind a hull using the unsteady Reynolds-Averaged Navier-Stokes equations (RANS are presented. A full hull body submerged under the free surface is modeled in the computational domain to simulate directly the wake field of the ship at the propeller plane. Simulations are performed in design and ballast draught conditions to study the effect of cavitation number. And two propellers with slightly different geometry are simulated to validate the detectability of the numerical simulation. All simulations are performed using a commercial CFD software FLUENT. Cavitation patterns of the simulations show good agreement with the experimental results carried out in Samsung CAvitation Tunnel (SCAT. The simulation results for the hull pressure fluctuation induced by a propeller are also compared with the experimental results showing good agreement in the tendency and amplitude, especially, for the first blade frequency.

  2. Blade Section Design of Marine Propellers with Minimum Cavitation Induced Pressure Fluctuations

    Science.gov (United States)

    Zeng, Zhibo; Kuiper, Gert

    2015-12-01

    To minimize cavitation induced pressure fluctuations by marine propellers with minimum efficiency loss, the paper presents a new design and optimization method using a blade section design method. The sheet cavity volume variation on a two-dimensional blade section in quasi-steady condition has been simplified to a relation with only a limited number of non-dimensional parameters. This results in a fast prediction method of the cavity volume of a blade section passing a wake peak, using a pre-calculated database. This makes optimization feasible. The optimization method was applied to the propeller of a container ship. Extensive tests in a towing tank and a cavitation channel validated the reduction of pressure fluctuations: 33% reduction in the first blade frequency amplitude and 18% reduction in the second blade frequency amplitude, with the same open water efficiency.

  3. Stomatal control and leaf thermal and hydraulic capacitances under rapid environmental fluctuations.

    Directory of Open Access Journals (Sweden)

    Stanislaus J Schymanski

    Full Text Available Leaves within a canopy may experience rapid and extreme fluctuations in ambient conditions. A shaded leaf, for example, may become exposed to an order of magnitude increase in solar radiation within a few seconds, due to sunflecks or canopy motions. Considering typical time scales for stomatal adjustments, (2 to 60 minutes, the gap between these two time scales raised the question whether leaves rely on their hydraulic and thermal capacitances for passive protection from hydraulic failure or over-heating until stomata have adjusted. We employed a physically based model to systematically study effects of short-term fluctuations in irradiance on leaf temperatures and transpiration rates. Considering typical amplitudes and time scales of such fluctuations, the importance of leaf heat and water capacities for avoiding damaging leaf temperatures and hydraulic failure were investigated. The results suggest that common leaf heat capacities are not sufficient to protect a non-transpiring leaf from over-heating during sunflecks of several minutes duration whereas transpirative cooling provides effective protection. A comparison of the simulated time scales for heat damage in the absence of evaporative cooling with observed stomatal response times suggested that stomata must be already open before arrival of a sunfleck to avoid over-heating to critical leaf temperatures. This is consistent with measured stomatal conductances in shaded leaves and has implications for water use efficiency of deep canopy leaves and vulnerability to heat damage during drought. Our results also suggest that typical leaf water contents could sustain several minutes of evaporative cooling during a sunfleck without increasing the xylem water supply and thus risking embolism. We thus submit that shaded leaves rely on hydraulic capacitance and evaporative cooling to avoid over-heating and hydraulic failure during exposure to typical sunflecks, whereas thermal capacitance provides

  4. Surface pressure fluctuations on aircraft flaps and their correlation with far-field noise

    Science.gov (United States)

    Guo, Y. P.; Joshi, M. C.; Bent, P. H.; Yamamoto, K. J.

    2000-07-01

    This paper discusses unsteady surface pressures on aircraft flaps and their correlation with far-field noise. Analyses are made of data from a 4.7% DC-10 aircraft model test, conducted in the 40 × 80 feet wind tunnel at NASA Ames Research Center. Results for various slat/wing/flap configurations and various flow conditions are discussed in detail to reveal major trends in surface pressure fluctuations. Spectral analysis, including cross-correlation/coherence, both among unsteady surface pressures and between far-field noise and near-field fluctuations, is used to reveal the most coherent motions in the near field and identify potential sources of noise related to flap flows. Dependencies of surface pressure fluctuations on mean flow Mach numbers, flap settings and slat angles are discussed. Dominant flow features in flap side edge regions, such as the formation of double-vortex structures, are shown to manifest themselves in the unsteady surface pressures as a series of spectral humps. The spectral humps are shown to correlate well with the radiated noise, indicating the existence of major noise sources in flap side edge regions. Strouhal number scaling is used to collapse the data with satisfactory results. The effects of flap side edge fences on surface pressures are also discussed. It is shown that the application of fences effectively increases the thickness of the flaps so that the double-vortex structures have more time to evolve. As a result, the characteristic timescale of the unsteady sources increases, which in turn leads to a decrease in the dominant frequency of the source process. Based on this, an explanation is proposed for the noise reduction mechanism of flap side edge fences.

  5. Non-Gaussian Analysis of Turbulent Boundary Layer Fluctuating Pressure on Aircraft Skin Panels

    Science.gov (United States)

    Rizzi, Stephen A.; Steinwolf, Alexander

    2005-01-01

    The purpose of the study is to investigate the probability density function (PDF) of turbulent boundary layer fluctuating pressures measured on the outer sidewall of a supersonic transport aircraft and to approximate these PDFs by analytical models. Experimental flight results show that the fluctuating pressure PDFs differ from the Gaussian distribution even for standard smooth surface conditions. The PDF tails are wider and longer than those of the Gaussian model. For pressure fluctuations in front of forward-facing step discontinuities, deviations from the Gaussian model are more significant and the PDFs become asymmetrical. There is a certain spatial pattern of the skewness and kurtosis behavior depending on the distance upstream from the step. All characteristics related to non-Gaussian behavior are highly dependent upon the distance from the step and the step height, less dependent on aircraft speed, and not dependent on the fuselage location. A Hermite polynomial transform model and a piecewise-Gaussian model fit the flight data well both for the smooth and stepped conditions. The piecewise-Gaussian approximation can be additionally regarded for convenience in usage after the model is constructed.

  6. Apomorphine: a rapid rescue agent for the management of motor fluctuations in advanced Parkinson disease.

    Science.gov (United States)

    Kolls, Brad J; Stacy, Mark

    2006-01-01

    Parkinson disease is one of the most common neurodegenerative diseases in the United States, and the number of late stage patients is rising. In advance-stage disease, fluctuations in motor function, variability in response to dopaminergic therapy, and dyskinesias related to increasing doses of dopamine agonists and levodopa, present a variety of challenges to a managing physician. Traditional methods of treatment have concentrated on therapies to anticipate or prevent states of poor motor function. With the approval of apomorphine as a rapid-acting, subcutaneous injectable anti-Parkinson disease therapy, these off periods may now be treated with apomorphine as a "rescue" medication when they occur. This article reviews the pharmacology of apomorphine, the clinical data that support its use and suggest dosing and methods for initiating therapy in this challenging population of patients with Parkinson disease.

  7. Rapid fluctuation of the vaginal microbiota measured by Gram stain analysis.

    Science.gov (United States)

    Brotman, Rebecca M; Ravel, Jacques; Cone, Richard A; Zenilman, Jonathan M

    2010-08-01

    The aetiology of bacterial vaginosis (BV) remains unknown. To describe longitudinal changes in vaginal microbiota. Thirty-nine women (mean age 36.8 years; 22 (56.4%) African-American) self-collected vaginal specimens twice weekly for 16 weeks as part of a vaginal douching cessation study. In an analysis where each woman serves as her own control, conditional logistic regression was used to evaluate daily, time-varying factors associated with a woman's incident BV episode(s) as compared with her persistently BV-negative sample(s). BV was defined by a Nugent's Gram stain score >or=7. 46.2% of participants had BV in the first 4 weeks of observation. Rapid fluctuation of vaginal microbiota was observed in 226 transitions to BV or spontaneous remission. Duration of BV was often short: 51% of the episodes lasted for only one sample interval (3 days). Among women who had at least one BV episode, the median number of episodes per woman was 8.7 (SD 7.4, range 1-22). Lubricant use 1 day before specimen collection (adjusted OR (aOR)=11.75, 95% CI 1.96 to 70.27) and rectal sex 2 days before (aOR=4.48, 95% CI 2.79 to 7.17) were associated with BV onset. Rapid fluctuation of the vaginal microbiota was seen. Longitudinal studies with long intervals between sampling are likely to miss episodes of BV. Recent report of lubricant use and rectal sex were associated with incident BV.

  8. Numerical simulation of pressure fluctuation of a pump-turbine with MGV at no-load condition

    Science.gov (United States)

    Liu, J. T.; Liu, S. H.; Sun, Y. K.; Wu, Y. L.; Wang, L. Q.

    2012-11-01

    In order to analyse the pressure fluctuation caused by misaligned guide vanes (MGV) during starting period at no-load condition, 3-D (three dimensional), unsteady flows in a pump-turbine were numerically studied. Pressure fluctuations of different points at no-load condition are obtained. Fast Fourier Transform(FFT) was used to analyse the frequency spectrum of pressure fluctuations. The amplitude and dominant frequency of pressure fluctuation at vaneless space between the runner and guide vane, as well as the inlet of draft tube, was investigated. The amplitude of pressure fluctuation of the pump-turbine with MGV device is twice that of synchronous vanes. This might be caused by the non-uniform flow in the pump-turbine due to the pre-opened guide vanes. The pump-turbine with synchronous vanes has a low frequency which is 0.33fn, while the low frequency changes into 0.63fn when the MGV device is used. The vortex rope in the draft tube is large than that of synchronize vanes. Resultsof pressure fluctuations with synchronous vanes agree with each other between computational and testing results. The numerical study of pressure fluctuations with MGV can provide a basic understanding for the improvement of the instability of a pump-turbine.

  9. Comparison of intraocular pressure fluctuations before and after ab interno trabeculectomy in pseudoexfoliation glaucoma patients.

    Science.gov (United States)

    Tojo, Naoki; Abe, Shinya; Miyakoshi, Mari; Hayashi, Atsushi

    2017-01-01

    Ab interno trabeculectomy (AIT) with the Trabectome has been shown to reduce intraocular pressure (IOP) in eyes with pseudoexfoliation (PEX) glaucoma. Here, we examined the change of IOP fluctuations before and after only AIT or AIT with cataract surgery in PEX patients using the contact lens sensor Triggerfish(®). This was a prospective open-label study. Twenty-four consecutive patients with PEX glaucoma were included. Twelve patients underwent cataract surgery and AIT (triple-surgery group), and 12 patients underwent only AIT (single-surgery group). In each eye, IOP fluctuations over 24 h were measured with the contact lens sensor before and at 3 months after the surgery. We compared the change of IOP fluctuation before and after operation. We also evaluated the difference in IOP changes between the triple- and single-surgery groups. At 3 months after the surgeries, the mean IOP was significantly reduced from 23.5±6.5 mmHg to 14.6±2.8 mmHg in the single-surgery group and from 22.5±3.0 mmHg to 11.5±2.9 mmHg in the triple-surgery group. The mean IOP reduction rate was significantly higher in the triple-surgery group compared to the single-surgery group (p=0.0358). In both groups, the mean range of IOP fluctuations was significantly decreased during nocturnal periods. The mean range of 24 h IOP fluctuations was decreased in the triple-surgery group (p=0.00425), not in the single-surgery group (p=0.970). Triple surgery could decrease IOP value and the IOP fluctuations to a greater extent than single surgery in PEX glaucoma patients.

  10. Influence of the turbulent boundary layer pressure fluctuation on the sound intensity measurement in a mean flow

    DEFF Research Database (Denmark)

    SHI, Xiao-jun; Jacobsen, Finn

    2010-01-01

    overwhelm the true source pressure in some cases. In this paper, the model of the sound intensity caused by the TBL pressure fluctuation is described firstly. Based upon the developed model, the sound intensity caused by the TBL pressure fluctuation is calculated using the available models of the wave......The influence of turbulent boundary layer pressure fluctuation on the sound intensity measurement in a flow is a subject of practical concern, because the sound intensity probe is generally exposed to the airflow and is sensed the turbulent boundary layer (TBL) pressure fluctuation which may even...... spatial response function of the microphone. Also, the characteristics of the measured sound intensity are consistent with that of the calculated sound intensity....

  11. Pressure dependence of critical temperature of bulk FeSe from spin fluctuation theory

    Science.gov (United States)

    Hirschfeld, Peter; Kreisel, Andreas; Wang, Yan; Tomic, Milan; Jeschke, Harald; Jacko, Anthony; Valenti, Roser; Maier, Thomas; Scalapino, Douglas

    2013-03-01

    The critical temperature of the 8K superconductor FeSe is extremely sensitive to pressure, rising to a maximum of 40K at about 10GPa. We test the ability of the current generation of fluctuation exchange pairing theories to account for this effect, by downfolding the density functional theory electronic structure for each pressure to a tight binding model. The Fermi surface found in such a procedure is then used with fixed Hubbard parameters to determine the pairing strength using the random phase approximation for the spin singlet pairing vertex. We find that the evolution of the Fermi surface captured by such an approach is alone not sufficient to explain the observed pressure dependence, and discuss alternative approaches. PJH, YW, AK were supported by DOE DE-FG02-05ER46236, the financial support of MT, HJ, and RV from the DFG Schwerpunktprogramm 1458 is kindly acknowledged.

  12. Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates.

    Science.gov (United States)

    Convey, Peter; Abbandonato, Holly; Bergan, Frode; Beumer, Larissa Teresa; Biersma, Elisabeth Machteld; Bråthen, Vegard Sandøy; D'Imperio, Ludovica; Jensen, Christina Kjellerup; Nilsen, Solveig; Paquin, Karolina; Stenkewitz, Ute; Svoen, Mildrid Elvik; Winkler, Judith; Müller, Eike; Coulson, Stephen James

    2015-12-01

    both direct exposure to at least -24 °C and the rapid and large temperature fluctuations. These results suggest that the studied polar soil invertebrate community may be robust to at least one important predicted consequence of projected climate change. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Effect of postural change on intraocular pressure fluctuation in open angle glaucoma patients after trabeculectomy

    Directory of Open Access Journals (Sweden)

    Wei Li

    2015-02-01

    Full Text Available AIM:To study the effect of postural change on intraocular pressure(IOPfluctuation in open angle glaucoma patients after trabeculectomy, and to discuss the value of this investigation on prognosis. METHODS: Fifty-one cases(62 eyesof primary open angle glaucoma were selected as the research object. Perkins ophthalmotonometer was used to test IOP at the time when patient seat(first seat. The patients were asked to lie supine for 25min, detected IOP, and the patients seated again(final seat, sustaining for 15min, detected IOP. According to whether the IOP range was more than 5mmHg, they were divided into high volatility fluctuation group and low volatility fluctuation group. We recorded their visual field progression(with AGIS score, HPA staging, in order to evaluate the correlation of IOP range with them. Reviews were made 3mo a time, and lasted for 1a, in order to evaluate the relation between IOP range and AGIS scores.RESULTS: The IOP of first seat was 18.1+2.2mmHg. There was no significant difference in the same position(P>0.05. The IOP range was 4.1±1.5mmHg. Low volatility fluctuation group was more likely to have low AGIS score and to be early vision HPA(PPr=0.412, PPCONCLUSION: Visual field progression is related to the degree of IOP fluctuation in open angle glaucoma patients after trabeculectomy, so we can predict the prognosis of patients simply by detect IOP fluctuation. This is good to adjust the IOP control scheme.

  14. Rapid Assessment of Protected area Pressures and Threats in ...

    African Journals Online (AJOL)

    Regular evaluation of protected area operations can enable policy makers develop strategic responses to pervasive management problems. Pressures and threats in seven National Parks of the National Park Service (NPS) were therefore assessed using the Rapid Assessment and Prioritization of Protected Area ...

  15. Fluctuation of intraocular pressure in glaucoma patients before and after trabeculectomy with mitomycin C.

    Directory of Open Access Journals (Sweden)

    Joanna Wasielica-Poslednik

    Full Text Available Intraocular pressure (IOP fluctuation is considered as a risk factor for glaucoma progression. We investigated IOP values and IOP fluctuation before and after trabeculectomy (TE with mitomycin C (MMC measured by 48-hour diurnal-nocturnal-IOP-profiles (DNP.Pre- and postoperative DNPs of 92 eyes undergoing primary TE with MMC were analysed. Each 48-hour IOP-profile involved 10 IOP measurements (8:00 a.m., 2:00 p.m., 6:00 p.m., and 9:00 p.m. in sitting and at 00:00 in supine position. The "preoperative DNP" was performed a few weeks before TE. The "postoperative DNP" was performed at least six months (range: 6 months-2 years after TE. Mean IOP values and IOP fluctuations were calculated.After TE with MMC mean IOP was reduced from 16.94±3.83 to 11.26±3.77 mmHg at daytime and from 18.17±4.26 to 11.76±3.90 mmHg at night. At daytime mean IOP-fluctuation decreased from 8.61±4.19 to 4.92±2.52 mmHg, at night from 3.15±2.95 to 1.99±1.82 mmHg. Mean IOP was lower on the second day of the preoperative DNP. This effect was not present in the postoperative DNP. Preoperatively, IOP was controlled in all eyes with a mean of 3.22±0.94 antiglaucomatous agents. Postoperatively, IOP≤15 mmHg was achieved in 71.7%, IOP≤18 mmHg in 77.1% and a decrease in IOP of >30% in 47.8% without antiglaucomatous therapy. Postoperatively, pseudophakia was associated by a higher mean IOP-fluctuation compared to the phakic eyes.TE with MMC significantly reduces both mean IOP-values and IOP- fluctuations at day and night at least 6 months postoperatively. The effect of TE on the IOP fluctuation was less pronounced in pseudophakic eyes.

  16. Fluctuating Pressure Analysis of a 2-D SSME Nozzle Air Flow Test

    Science.gov (United States)

    Reed, Darren; Hidalgo, Homero

    1996-01-01

    To better understand the Space Shuttle Main Engine (SSME) startup/shutdown tansients, an airflow test of a two dimensional nozzle was conducted at Marshall Space Flight Center's trisonic wind tunnel. Photographic and other instrumentation show during an SSME start large nozzle shell distortions occur as the Mach disk is passing through the nozzle. During earlier develop of the SSME, this startup transient resulted in low cycle fatigue failure of one of the LH2 feedlines. The two dimensional SSME nozzle test was designed to measure the static and fluctuating pressure environment and color Schlieren video during the startup and shutdown phases of the run profile.

  17. Extraction of crustal deformations and oceanic fluctuations from ocean bottom pressures

    Science.gov (United States)

    Ariyoshi, Keisuke; Nagano, Akira; Hasegawa, Takuya; Matsumoto, Hiroyuki; Kido, Motoyuki; Igarashi, Toshihiro; Uchida, Naoki; Iinuma, Takeshi; Yamashita, Yusuke

    2017-04-01

    It has been well known that megathrust earthquakes such as the 2004 Sumatra-Andaman Earthquake (Mw 9.1) and the 2011 the Pacific Coast of Tohoku Earthquake (Mw 9.0) had devastated the coastal areas in the western of Indonesia and in the north-eastern of Japan, respectively. To mitigate the disaster of those forthcoming megathrust earthquakes along Nankai Trough, the Japanese government has established seafloor networks of cable-linked observatories around Japan: DONET (Dense Oceanfloor Network system for Earthquakes and Tsunamis along the Nankai Trough) and S-net (Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench). The advantage of the cable-linked network is to monitor the propagation process of tsunami and seismic waves as well as seismic activity in real time. DONET contains pressure gauges as well as seismometers, which are expected to detect crustal deformations driven by peeling off subduction plate coupling process. From our simulation results, leveling changes are different sense among the DONET points even in the same science node. On the other hand, oceanic fluctuations such as melting ice masses through the global warming have so large scale as to cause ocean bottom pressure change coherently for all of DONET points especially in the same node. This difference suggests the possibility of extracting crustal deformations component from ocean bottom pressure data by differential of stacking data. However, this operation cannot be applied to local-scale fluctuations related to ocean mesoscale eddies and current fluctuations, which affect ocean bottom pressure through water density changes in the water column (from the sea surface to the bottom). Therefore, we need integral analysis by combining seismology, ocean physics and tsunami engineering so as to decompose into crustal deformation, oceanic fluctuations and instrumental drift, which will bring about high precision data enough to find geophysical phenomena. In this study

  18. Fluctuations of multiplicities in rapidity windows in sulphur-sulphur collisions at 200 A GeV

    CERN Document Server

    Bächler, J; Runge, K; Schmoetten, E; Bartke, Jerzy; Gladysz-Dziadus, E; Kowalski, M; Stefanski, P; Bialkowska, H; Böck, R K; Brockmann, R; Sandoval, A; Buncic, P; Ferenc, D; Kadija, K; Ljubicic, A; Vranic, D; Chase, S I; Harris, J W; Odyniec, Grazyna Janina; Pugh, Howel G; Rai, G; Teitelbaum, L; Tonse, S R; Derado, I; Eckardt, V; Gebauer, H J; Rauch, W; Schmitz, N; Seyboth, P; Seyerlein, J; Vesztergombi, G; Eschke, J; Heck, W; Kabana, S; Kühmichel, A; Lahanas, L; Lee, Y; Le Vine, M J; Margetis, S; Renfordt, R E; Röhrich, D; Rothard, H; Schmidt, E; Schneider, I; Stock, Reinhard; Ströbele, H; Wenig, S; Fleischmann, B; Fuchs, M; Gazdzicki, M; Kosiec, J; Skrzypczak, E; Keidel, R; Piper, A; Pühlhofer, F; Nappi, E; Posa, F; Paic, G; Panagiotou, A D; Petridis, A; Vasileiadis, G; Pfennig, J

    1992-01-01

    Multiplicity distributions and their second moments fornegatively charged particles produced in32S-S central and minimum bias interactions at 200A GeV are studied in various rapidity intervals. Fritiof and Venus models mostly describe the dependence of second moments on rapidity intervals in minimum bias interactions, but not in central collisions. For central collisions the behaviour of second moments might indicate enhanced multiplicity fluctuations.

  19. Characteristic analysis on the pressure fluctuation in the impeller of a low specific speed mixed flow pump

    Science.gov (United States)

    Zhang, W. W.; Yu, Z. Y.; Zhu, B. S.

    2016-05-01

    To explore the pressure fluctuation characteristics of a low speed specific speed mixed flow pump caused by rotor-stator interaction, the unsteady flow was simulated with CFX for the whole flow passage of a mixed flow pump with a specific speed of 148.8. The structured mesh of the computation domain was generated with ICEM CFD and TurboGrid, and mesh-independent analysis was done in the design condition. Through the comparison with the experiment data, the reliability of the simulation was verified. In different locations of the impeller passage, monitoring points were set. With Fast Fourier Transform (FFT), the characteristic analysis on the pressure fluctuation in the impeller passage was done for three flow rate conditions (0.75Qd, Qd, 1.25Qd). The results show that the pressure fluctuation amplitude increases from the inlet to the outlet. And the maximum values in different flow rates exist near the hub of the outlet; The pressure fluctuation is small in the design condition, but the largest in the small flow rate condition, accompanied by the secondary dominant frequencies with large amplitudes; In the small flow rate condition and design condition, the dominant frequency varies from the inlet to the outlet because the combine action of the impeller and guide vane; while in the large flow rate condition, the pressure fluctuation in the whole impeller passage is affected significantly by the guide vane, and the domain frequency is 8 times the rotational frequency of impeller. In addition, the change of pressure fluctuation from the pressure surface to the suction surface in the off-design conditions is investigated, and the results demonstrates that the intensity of the pressure fluctuation in the impeller passage is closely related with the impeller as well as the distribution of the vorticity and the pressure.

  20. Characteristics of Turbulent Airflow Deduced from Rapid Surface Thermal Fluctuations: An Infrared Surface Anemometer

    Science.gov (United States)

    Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani

    2017-12-01

    The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.

  1. Pressure Fluctuations in the S-Shaped Region of a Reversible Pump-Turbine

    Directory of Open Access Journals (Sweden)

    Zijie Wang

    2017-01-01

    Full Text Available Numerical simulations were performed to investigate pressure fluctuations in the S-shaped region of a pump-turbine model. Analyses focused on pressure fluctuations in the draft tube and in the gap between the guide vanes and runner. Calculations were made under six different operating conditions with a constant guide vane opening, and the best efficiency point, runaway point, and low-discharge point in the turbine brake zone were determined. The simulated results were compared with experimental measurements. In the draft tube, a twin vortex rope was observed. In the gap between the guide vanes and runner, a low frequency component was captured at both the runaway and low-discharge points in the turbine brake zone, which rotated at 65% of the runner frequency. This low frequency component was induced by the rotating stall phenomenon. At the runaway point, a single stall cell was found in the gap between the guide vanes and runner, while at the low-discharge point, four stall cells were observed.

  2. Prediction of Francis Turbine Prototype Part Load Pressure and Output Power Fluctuations with Hydroelectric Model

    Science.gov (United States)

    Alligné, S.; Nicolet, C.; Béguin, A.; Landry, C.; Gomes, J.; Avellan, F.

    2017-04-01

    The prediction of pressure and output power fluctuations amplitudes on Francis turbine prototype is a challenge for hydro-equipment industry since it is subjected to guarantees to ensure smooth and reliable operation of the hydro units. The European FP7 research project Hyperbole aims to setup a methodology to transpose the pressure fluctuations induced by the cavitation vortex rope from the reduced scale model to the prototype generating units. A Francis turbine unit of 444MW with a specific speed value of ν = 0.29, is considered as case study. A SIMSEN model of the power station including electrical system, controllers, rotating train and hydraulic system with transposed draft tube excitation sources is setup. Based on this model, a frequency analysis of the hydroelectric system is performed for all technologies to analyse potential interactions between hydraulic excitation sources and electrical components. Three technologies have been compared: the classical fixed speed configuration with Synchronous Machine (SM) and the two variable speed technologies which are Doubly Fed Induction Machine (DFIM) and Full Size Frequency Converter (FSFC).

  3. The Warburg effect as an adaptation of cancer cells to rapid fluctuations in energy demand.

    Directory of Open Access Journals (Sweden)

    Tamir Epstein

    Full Text Available To maintain optimal fitness, a cell must balance the risk of inadequate energy reserve for response to a potentially fatal perturbation against the long-term cost of maintaining high concentrations of ATP to meet occasional spikes in demand. Here we apply a game theoretic approach to address the dynamics of energy production and expenditure in eukaryotic cells. Conventionally, glucose metabolism is viewed as a function of oxygen concentrations in which the more efficient oxidation of glucose to CO2 and H2O produces all or nearly all ATP except under hypoxic conditions when less efficient (2 ATP/ glucose vs. about 36ATP/glucose anaerobic metabolism of glucose to lactic acid provides an emergency backup. We propose an alternative in which energy production is governed by the complex temporal and spatial dynamics of intracellular ATP demand. In the short term, a cell must provide energy for constant baseline needs but also maintain capacity to rapidly respond to fluxes in demand particularly due to external perturbations on the cell membrane. Similarly, longer-term dynamics require a trade-off between the cost of maintaining high metabolic capacity to meet uncommon spikes in demand versus the risk of unsuccessfully responding to threats or opportunities. Here we develop a model and computationally explore the cell's optimal mix of glycolytic and oxidative capacity. We find the Warburg effect, high glycolytic metabolism even under normoxic conditions, is represents a metabolic strategy that allow cancer cells to optimally meet energy demands posed by stochastic or fluctuating tumor environments.

  4. Features of daily blood pressure fluctuations in patients with obstructive sleep apnea syndrome and obesity

    Directory of Open Access Journals (Sweden)

    O. I. Tokarenko

    2016-12-01

    Full Text Available Objective: to study the features of daily blood pressure fluctuations according to the ambulatory blood pressure monitoring (ABPM in patients with obstructive sleep apnea syndrome (OSAS and obesity without arterial hypertension (AH. Methods. The study included 86 patients with OSAS and obesity (group 1, 74 obese patients without OSAS (group 2 and 52 patients with OSAS and normal body weight (group 3. The control group consisted of 20 healthy individuals. All participants of the study were carried out physical examination, cardio-respiratory monitoring and ABPM. Results. Systolic and diastolic blood pressure levels in patients from the 1st group were higher than in the control group for the whole day and night. The highest levels of SBP and DBP during the day and night were registered in the 1st group. It has been found that IV for SBP per day exceeded control values by 22%, 22% and 17% in the 1st, 2nd and the 3rd groups, respectively. Average daily IV for DAT was elevated in 15, 12 and 6 patients from the 1st, 2nd and the 3rd groups, respectively. Among the pathological daily profiles «non - dipper» was the predominant. Patients of all three groups more frequently showed significantly increased of SBP and DBP daytime and night time variability than the patients of control group. Conclusions 1. Patients with OSAS and obesity have insufficient blood pressure reduction at night for both SBP and DBP, higher variability of blood pressure during the day, higher level of pressure load index. 2. Inmultiple regression analysis it has been defined the relationship between AHI and SBP at night (β = 0,403, p <0.05, as well as AHI, night DBP (β = 0,308, p <0.05 and BMI (β = 0,314, p <0.05.

  5. Magnetic field and dynamic pressure ULF fluctuations in coronal-mass-ejection-driven sheath regions

    Directory of Open Access Journals (Sweden)

    E. K. J. Kilpua

    2013-09-01

    Full Text Available Compressed sheath regions form ahead of interplanetary coronal mass ejections (ICMEs that are sufficiently faster than the preceding solar wind. The turbulent sheath regions are important drivers of magnetospheric activity, but due to their complex internal structure, relatively little is known on the distribution of the magnetic field and plasma variations in them. In this paper we investigate ultra low frequency (ULF fluctuations in the interplanetary magnetic field (IMF and in dynamic pressure (Pdyn using a superposed epoch analysis of 41 sheath regions observed during solar cycle 23. We find strongest fluctuation power near the shock and in the vicinity of the ICME leading edge. The IMF and Pdyn ULF power have different profiles within the sheath; the former is enhanced in the leading part of the sheath, while the latter is increased in the trailing part of the sheath. We also find that the ICME properties affect the level and distribution of the ULF power in sheath regions. For example, sheath regions associated with strong or fast ICMEs, or those that are crossed at intermediate distances from the center, have strongest ULF power and large variation in the power throughout the sheath region. The weaker or slower ICMEs, or those that are crossed centrally, have in general considerably weaker ULF power with relatively smooth profiles. The strong and abrupt decrease of the IMF ULF power at the ICME leading edge could be used to distinguish the ICME from the preceding sheath plasma.

  6. Detrended Fluctuation Analysis of Intracranial Pressure Predicts Outcome Following Traumatic Brain Injury

    Science.gov (United States)

    Kirkness, Catherine J.; Mitchell, Pamela H.

    2009-01-01

    Detrended fluctuation analysis (DFA) is a recently developed technique suitable for describing scaling behavior of variability in physiological signals. The purpose of this study is to explore applicability of DFA methods to intracranial pressure (ICP) signals recorded in patients with traumatic brain injury (TBI). In addition to establishing the degree of fit of the power-law scaling model of detrended fluctuations of ICP in TBI patients, we also examined the relationship of DFA coefficients (scaling exponent and intercept) to: 1) measures of initial neurological functioning; 2) measures of functional outcome at six month follow-up; and 3) measures of outcome, controlling for patient characteristics, and initial neurological status. In a sample of 147 moderate-to-severely injured TBI patients, we found that a higher DFA scaling exponent is significantly associated with poorer initial neurological functioning, and that lower DFA intercept and higher DFA scaling exponent jointly predict poorer functional outcome at six month follow-up, even after statistical control for covariates reflecting initial neurological condition. DFA describes properties of ICP signal in TBI patients that are associated with both initial neurological condition and outcome at six months postinjury. PMID:18990620

  7. Rapid change of multiplicity fluctuations in system size dependence at SPS energies arXiv

    CERN Document Server

    Recent preliminary results on multiplicity fluctuations in p+p, Be+Be and Ar+Sc collisions from the NA61/SHINE collaboration are presented. The scaled variance of charged hadron multiplicity changes little when going from p+p to Be+Be collisions and drops dramatically from Be+Be to Ar+Sc interactions. The centrality selection procedure and the influence of volume fluctuations are discussed. Comparisons with the EPOS event generator are shown.

  8. Assessment of Fluctuation Patterns Similarity in Temperature and Vapor Pressure Using Discrete Wavelet Transform

    Directory of Open Access Journals (Sweden)

    A. Araghi

    2014-12-01

    Full Text Available Period and trend are two main effective and important factors in hydro-climatological time series and because of this importance, different methods have been introduced and applied to study of them, until now. Most of these methods are statistical basis and they are classified in the non-parametric tests. Wavelet transform is a mathematical based powerful method which has been widely used in signal processing and time series analysis in recent years. In this research, trend and main periodic patterns similarity in temperature and vapor pressure has been studied in Babolsar, Tehran and Shahroud synoptic stations during 55 years period (from 1956 to 2010, using wavelet method and the sequential Mann-Kendall trend test. The results show that long term fluctuation patterns in temperature and vapor pressure have more correlations in the arid and semi-arid climates, as well as short term oscillation patterns in temperature and vapor pressure in the humid climates, and these dominant periods increase with the aridity of region.

  9. Online correlation of spontaneous arterial and intracranial pressure fluctuations in patients with diffuse severe head injury.

    Science.gov (United States)

    Reinert, Michael; Andres, Robert H; Fuhrer, Martin; Müller, Alexander; Schaller, Benoit; Widmer, HansRuedi

    2007-07-01

    Determination of relevant clinical monitoring parameters for helping guide the intensive care therapy in patients with severe head injury, is one of the most demanding issues in neurotrauma research. New insights into cerebral autoregulation and metabolism have revealed that a rigid cerebral perfusion pressure (CPP) regimen might not be suitable for all severe head injured patients. We thus developed an online analysis technique to monitor the correlation (AI rho) between the spontaneous fluctuations of the mean arterial blood pressure (MABP) and the intracranial pressure (ICP). In addition, brain tissue oxygen (PtiO2) and metabolic microdialysate measures including glucose and lactate were registered. We found that in patients with good outcome, the AI rho values were significantly lower as compared with patients with poor outcome. Accordingly, microdialysate glucose and lactate were significantly higher in the good outcome group. We conclude that online determination of AI rho offers a valuable additional and technically easily performable tool for guidance of therapy in patients with severe head injury.

  10. Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer

    Science.gov (United States)

    Mulder, Andrew; Skelley, Stephen

    2011-01-01

    Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small decrease in radial load along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the flow environment.

  11. Comparison of intraocular pressure, blood pressure, ocular perfusion pressure and blood flow fluctuations during dorzolamide versus timolol add-on therapy in prostaglandin analogue treated glaucoma subjects.

    Science.gov (United States)

    Januleviciene, Ingrida; Siaudvytyte, Lina; Diliene, Vaida; Barsauskaite, Ruta; Paulaviciute-Baikstiene, Daiva; Siesky, Brent; Harris, Alon

    2012-03-21

    To compare the effects of dorzolamide and timolol add-on therapy in open-angle glaucoma (OAG) patients previously treated with prostaglandin analogue (Pg), by evaluating fluctuations in the intraocular (IOP), blood (BP), ocular perfusion pressures (OPP) and retrobulbar blood flow (RBF) parameters. 35 OAG patients (35 eyes), 31 women (88.6%) age 63.3 (8.9) years were evaluated in a 3 month randomized, cross-over, single-masked study. During the experiments BP, heart rate, IOP and OPP were assessed 4 times per day (8-12-16-20 h). RBF was measured twice per day (8-20 h) using Color Doppler imaging in the ophthalmic (OA), central retinal (CRA), nasal (nSPCA) and temporal (tSPCA) posterior ciliary arteries. In each vessel, peak systolic velocity (PSV) and end-diastolic velocity (EDV) were assessed and vascular resistance (RI) calculated. Both add-on therapies lowered IOP in a statistically significant manner from 15.7 ± 2.4 mmHg at latanoprost baseline to 14.9 ± 2.2 mmHg using dorzolamide (p add-on therapy showed smaller IOP (2.0 ± 1.4), SPP (13.3 ± 7.9), systolic BP (13.5 ± 8.7) and diastolic BP (8.4 ± 5.4) fluctuations as compared to both latanoprost baseline or timolol add-on therapies. Higher difference between morning and evening BP was correlated to decreased evening CRA EDV in the timolol group (c = -0.41; p = 0.01). With increased MAP in the morning or evening hours, we found increased evening OA RI in timolol add-on group (c = 0.400, p = 0.02; c = 0.513, p = 0.002 accordingly). Higher MAP fluctuations were related to impaired RBF parameters during evening hours-decreased CRA EDV (c = -0.408; p = 0.01), increased CRA RI (c = 0.576; p add-on group. OPP fluctuations correlated with increased nSPCA RI (c = 0.453; p = 0.006) in the timolol group. OPP fluctuations were not related to IOP fluctuations in both add-on therapies (p add-on therapies lowered IOP in a statistically significant fashion dorzolamide add-on therapy showed lower fluctuations in IOP, SPP

  12. The Fluctuation of Intraocular Pressure Measured by a Contact Lens Sensor in Normal-Tension Glaucoma Patients and Nonglaucoma Subjects.

    Science.gov (United States)

    Tojo, Naoki; Abe, Shinya; Ishida, Masaaki; Yagou, Takaaki; Hayashi, Atsushi

    2017-03-01

    We compared the fluctuation of intraocular pressure (IOP) in normal-tension glaucoma (NTG) patients and individuals with nonglaucoma eyes. We obtained continuous IOP values using a SENSIMED Triggerfish contact lens sensor. The eyes of 12 nonglaucoma subjects and 14 NTG patients were examined. In all 26 subjects, the IOP fluctuation was measured continuously for 24 hours with a contact lens sensor. We evaluated the range of IOP fluctuations over the 24-hour period separately for diurnal IOP and nocturnal IOP and identified each subject's maximum value. The range of IOP fluctuation were analyzed, cutoff level of IOP fluctuation was calculated using receiver operating characteristic curve analyses. The mean IOP in the NTG eyes was 11.5±2.4 mm Hg and that in the nonglaucoma eyes was 12.7±2.0 mm Hg, a nonsignificantly difference (P=0.175). The 24-hour range of IOP fluctuations in the NTG group was significantly larger than that of the nonglaucoma group (P=0.007). The percentage of NTG patients who had the peak time of IOP fluctuation during nocturnal sleep was 57.1%, whereas the corresponding rate for the nonglaucoma eyes was 91.7%. The cutoff level of IOP fluctuation for glaucoma was 442 mVeq (sensitivity=1.00; specificity=0.571). The range of IOP fluctuation was larger in the eyes with NTG than in the nonglaucoma eyes. This larger fluctuation might be one of the reasons underlying the aggravation of the visual field by NTG. Measurements of 24-hour continuous IOP might be one of the useful methods to distinguish NTG from nonglaucoma eyes.

  13. Intraocular pressure fluctuation before and after strabismus surgery: a systematic review

    Directory of Open Access Journals (Sweden)

    Aliakbar Saber Moghaddam

    2015-12-01

    Full Text Available Introduction: Intraocular pressure (IOP can be influenced by several factors including corneal thickness, gender, refractive error, and the presence of diabetes mellitus. In the present study, we systematically reviewed published literature to find association between variations of IOP due to strabismus surgery.Method: PubMed and Scopus were systematically searched with the following search terms: (intraocular pressure OR IOP AND (strabismus for the articles in which the fluctuation of IOP before and after strabismus surgery had been evaluated. All types of articles including case series, cross-sectional, clinical trials, and cohort studies with no time limitation were included in this study. Systematically searches, selection of articles, and the extraction of data were performed by two reviewers independently.Result: 1617 out of 1674 articles were excluded due to duplication or irrelevancy. After step by step process of article selection, 57 relevant articles were included for further evaluation. However, only 8 articles met the inclusion criteria.Conclusions: The results of this report showed that IOP may vary due to strabismus surgery, and it decreases after the surgery.

  14. Turbulent flow and pressure fluctuation prediction of the impeller in an axial-flow pump based on LES

    Science.gov (United States)

    Shen, J. F.; Li, Y. J.; Liu, Z. Q.; Tang, X. L.

    2013-12-01

    The Large Eddy Simulation method with sliding mesh technique has been used for analyzing the unsteady flow in an axial-flow pump at five different flow rates. The tip leakage flow in the tip-gap region and the pressure pulsations on the blade surface were examined. The results indicate that the agreement between predicted pump performance and experimental data was reasonably good. The dominate tip-leakage vortex(TLV) extended to the pressure side of the neighboring blade for all five investigated flow rates. As the flow rate increases from 0.7Qd to 1.2Qd, the angle between the dominate TLV and the blade reduced from 20 deg to 14 deg. The results also showed that the amplitude of pressure fluctuation on the near-tip zone of the blade surface increases as the flow rate farer from the design flow rate, especially on the pressure side of the blade. At the 0.7Qd operation condition, the pressure fluctuation amplitude of the monitoring point PP3 (at the near-tip zone on the pressure side of the blade close to the blade leading edge) was 8.5 times of the one at design flow rate, and the high-frequency(18fr) pulsation occurred due to tip leakage vortex. When the flow rate was more than 1.0Qd, the pressure fluctuations of PP3 was dominated by the rotation frequency(fr).

  15. Research of fluid-induced pressure fluctuation due to impeller-volute interaction in a centrifugal pump

    Science.gov (United States)

    Liu, Q. Z.; Yang, K.; Y Li, D.; Gong, R. Z.

    2013-12-01

    The fluid pressure fluctuation generated by unsteady flow is a very important factor to induce vibration of the centrifugal pump. The relative movement between impeller and volute generates an unsteady interaction which affects not only the overall pump performance, but is also responsible for pressure fluctuations. Pressure fluctuations interact with the volute casing or even with the circuit and give rise to dynamic effects over the mechanical parts, which are one of the most important sources of vibration and hydraulic noise. To investigate the flow characteristic in the centrifugal pump, the unsteady flow is simulated by CFD methods in this paper. Unsteady flow characteristic in the centrifugal pump is obtained considering the impeller-volute interaction in the whole flow field. Based on the unsteady flow simulation, amplitude-frequency characteristics of the pressure fluctuation in the centrifugal pump are obtained through setting up monitoring point at the impeller outlet. The research shows that the frequency component include the blade passing frequency as the main component, the multiplication of blade passing frequency, and the harmonic interference due to the unsteady flow.

  16. Modeling cavitation in a rapidly changing pressure field - application to a small ultrasonic horn.

    Science.gov (United States)

    Žnidarčič, Anton; Mettin, Robert; Dular, Matevž

    2015-01-01

    Ultrasonic horn transducers are frequently used in applications of acoustic cavitation in liquids. It has been observed that if the horn tip is sufficiently small and driven at high amplitude, cavitation is very strong, and the tip can be covered entirely by the gas/vapor phase for longer time intervals. A peculiar dynamics of the attached cavity can emerge with expansion and collapse at a self-generated frequency in the subharmonic range, i.e. below the acoustic driving frequency. The term "acoustic supercavitation" was proposed for this type of cavitation Žnidarčič et al. (2014) [1]. We tested several established hydrodynamic cavitation models on this problem, but none of them was able to correctly predict the flow features. As a specific characteristic of such acoustic cavitation problems lies in the rapidly changing driving pressures, we present an improved approach to cavitation modeling, which does not neglect the second derivatives in the Rayleigh-Plesset equation. Comparison with measurements of acoustic supercavitation at an ultrasonic horn of 20kHz frequency revealed a good agreement in terms of cavity dynamics, cavity volume and emitted pressure pulsations. The newly developed cavitation model is particularly suited for simulation of cavitating flow in highly fluctuating driving pressure fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Influence of the quark-gluon string fusion mechanism on long-range rapidity correlations and fluctuations

    Science.gov (United States)

    Andronov, E. V.

    2015-10-01

    Multiparticle production in soft hadronic interactions can be successfully described in the framework of the color-string approach, which will probably be derived from the first principles of chromodynamics in the future. A fundamental property of this approach is the translation invariance of the rapidity spectrum of charged particles produced by one source at high energies. This symmetry results in the appearance of long-range rapidity correlations through event-by-event fluctuations of the number and/or type of strings. We describe the behavior of correlations between multiplicities ( n-n) and between the transverse momentum and multiplicities ( pt-n) of charged particles with the mechanism of forming sources of two types taken into account. We obtain an exact analytic expression for the ( n-n)-correlation coefficient. Because no exact solution can be obtained for the ( pt-n)-correlation coefficient, we propose an effective approximation that significantly simplifies numerical computations. We verify all these results by direct simulation using the Monte Carlo method. We also investigate how the fusion mechanism influences the behavior of strongly intensive variables characterizing the multiplicity fluctuations in two rapidity windows.

  18. Rapid Heat Treatment of Aluminum High-Pressure Diecastings

    Science.gov (United States)

    Lumley, R. N.; Polmear, I. J.; Curtis, P. R.

    2009-07-01

    Recently, it has been demonstrated that common high-pressure diecasting (HPDC) alloys, such as those based on the Al-Si-Cu and Al-Si-Mg-(Cu) systems, may be successfully heat treated without causing surface blistering or dimensional instability. In some compositions, the capacity to exploit age hardening may allow the proof stress values to be doubled when compared to the as-cast condition. This heat treatment procedure involves the use of severely truncated solution treatment cycles conducted at lower than normal temperatures, followed by quenching and natural or artificial aging. The potential therefore exists to develop and evaluate secondary HPDC alloys designed specifically for rapid heat treatment, while still displaying high castability. This article reports results of an experimental program in which responses of various alloy compositions to age hardening have been investigated with the primary aim of further reducing the duration and cost of the heat treatment cycle while maintaining high tensile properties. Composition ranges have been established for which values of 0.2 pct proof stress exceeding 300 MPa ( i.e., increases of ~100 pct above as-cast values) can be achieved using a procedure that involves a total time for solution treatment plus age hardening of only 30 minutes. This rapid aging behavior is shown to be related to precipitation of the complex Q' phase, which forms primarily when Mg contents of the alloys are above ~0.2 wt pct.

  19. Influence of wind-induced air pressure fluctuations on topsoil gas concentrations within a Scots pine forest

    Science.gov (United States)

    Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Schindler, Dirk

    2017-04-01

    Commonly it is assumed that soil gas transport is dominated by molecular diffusion. Few recent studies indicate that the atmosphere above the soil triggers non-diffusive gas transport processes in the soil, which can enhance soil gas transport and therefore soil gas efflux significantly. During high wind speed conditions, the so called pressure pumping effect has been observed: the enhancement of soil gas transport through dynamic changes in the air pressure field above the soil. However, the amplitudes and frequencies of the air pressure fluctuations responsible for pressure pumping are still uncertain. Moreover, an in situ observation of the pressure pumping effect is still missing. To investigate the pressure pumping effect, airflow measurements above and below the canopy of a Scots pine forest and high-precision relative air pressure measurements were conducted in the below-canopy space and in the soil over a measurement period of 16 weeks. To monitor the soil gas transport, a newly developed gas measurement system was used. The gas measurement system continuously injects helium as a tracer gas into the soil until a diffusive steady state is reached. With the steady state concentration profile of the tracer gas, it is possible to inversely model the gas diffusion coefficient profile of the soil. If the gas diffusion coefficient profile differed from steady state, we deduced that the soil gas transport is not only diffusive, but also influenced by non-diffusive processes. Results show that the occurrence of small air pressure fluctuations is strongly dependent on the mean above-canopy wind speed. The wind-induced air pressure fluctuations have mean amplitudes up to 10 Pa and lie in the frequency range 0.01-0.1 Hz. To describe the pumping motion of the air pressure field, the pressure pumping coefficient (PPC) was defined as the mean change in pressure per second. The PPC shows a clear quadratic dependence on mean above-canopy wind speed. Empirical modelling of

  20. Numerical investigation on pressure fluctuations in centrifugal compressor with different inlet guide vanes pre-whirl angles

    Science.gov (United States)

    Wang, Y. C.; Shi, M.; Cao, S. L.; Li, Z. H.

    2013-12-01

    The pressure fluctuations in a centrifugal compressor with different inlet guide vanes (IGV) pre-whirl angles were investigated numerically, as well as the pre-stress model and static structural of blade. The natural frequency was evaluated by pre-stress model analysis. The results show that, the aero-dynamic pressure acting on blade surface is smaller than rotation pre-stress, which wouldn't result in large deformation of blade. The natural frequencies with rotation pre-stress are slightly higher than without rotation pre-stress. The leading mechanism of pressure fluctuations for normal conditions is the rotor-stator (IGVs) interaction, while is serious flow separations for conditions that are close to surge line. A few frequency components in spectra are close to natural frequency, which possibly result in resonant vibration if amplitude is large enough, which is dangerous for compressor working, and should be avoided.

  1. Fluctuating pressures measured beneath a high-temperature, turbulent boundary layer on a flat plate at Mach number of 5

    Science.gov (United States)

    Parrott, Tony L.; Jones, Michael G.; Albertson, Cindy W.

    1989-01-01

    Fluctuating pressures were measured beneath a Mach 5, turbulent boundary layer on a flat plate with an array of piezoresistive sensors. The data were obtained with a digital signal acquisition system during a test run of 4 seconds. Data sampling rate was such that frequency analysis up to 62.5 kHz could be performed. To assess in situ frequency response of the sensors, a specially designed waveguide calibration system was employed to measure transfer functions of all sensors and related instrumentation. Pressure time histories were approximated well by a Gaussian prohibiting distribution. Pressure spectra were very repeatable over the array span of 76 mm. Total rms pressures ranged from 0.0017 to 0.0046 of the freestream dynamic pressure. Streamwise, space-time correlations exhibited expected decaying behavior of a turbulence generated pressure field. Average convection speed was 0.87 of freestream velocity. The trendless behavior with sensor separation indicated possible systematic errors.

  2. Numerical Simulation of Pressure Fluctuations in the Thermo-acoustic Transducer

    Directory of Open Access Journals (Sweden)

    D. A. Uglanov

    2015-01-01

    Full Text Available The article describes the features of numerical simulation of acoustic oscillation excitation in the resonators with a foam insert (regenerator to study the excitation of thermo-acoustic oscillations in the circuit of small-sized engine model on the pulse tube.The aim of this work is the numerical simulation of the emerging oscillations in thermoacoustic engine resonator at the standing wave. As a basis, the work takes a thermo-acoustic resonator model with the open end (without piston developed in DeltaEC software. The precalculated operation frequency of the given resonator model, as a quarter of the wave resonator, is ν = 560 Hz.The paper offers a simplified finite element resonator model and defines the harmonic law of the temperature distribution on regenerator. The time dependences of the speed and pressure amplitude for the open end of the resonator are given; the calculated value of the process operating frequency is approximately equal to the value of the frequency for a given length of the resonator. Key findings, as a result of study, are as follows:1. The paper shows a potential for using this ESI-CFD Advanced software to simulate the processes of thermal excitation of acoustic oscillations.2. Visualization of turbulent flow fluctuations in the regenerator zone extends the analysis capability of gas-dynamic processes.3. Difference between operating frequency of the process simulated by ESI-CFD Advanced and frequency value obtained by analytical methods is about 4%, which is evidence of the model applicability to study the acoustic parameters of thermo-acoustic transducers. Experimental results have proved these data.

  3. Intraocular Pressure Fluctuations and 24-Hour Continuous Monitoring for Glaucoma Risk in Wind Instrument Players.

    Science.gov (United States)

    de Crom, Ronald M P C; Webers, Carroll A B; van Kooten-Noordzij, Marina A W; Michiels, Agnes C; Schouten, Jan S A G; Berendschot, Tos T J M; Beckers, Henny J M

    2017-10-01

    The purpose of this study is to investigate the influence of playing a wind instrument on intraocular pressure (IOP) and to monitor 24-hour (IOP) fluctuations in wind musicians of symphony and wind orchestras to compare IOP levels during normal daily activities with IOP levels during playing. Professional and amateur musicians of symphony and wind orchestras were invited to participate. A total of 42 participants, 9 with glaucoma, underwent a routine ophthalmologic examination. IOP measurements were taken before and immediately after 20 minutes of playing wind instruments. In addition, 6 participants underwent 24-hour IOP monitoring with the Triggerfish (Sensimed AG, Switzerland) sensing contact lens, during which they kept an activity logbook. Eleven professionals and 31 amateur musicians participated in the study. A total of 7 eyes of 6 patients underwent additional 24-hour IOP monitoring. Mean IOP before playing was 13.6±2.6 mm Hg, IOP change after playing was +1.5±2.2 mm Hg with a significant difference between professionals (2.5±1.5 mm Hg) and amateurs (1.1±2.3 mm Hg). There were no significant differences in IOP change between subjects with or without glaucoma. During 24-hour IOP monitoring there were slight increases in IOP while playing an instrument, but also during other activities and overnight. These latter IOP levels were similar or even higher than the IOP rise caused by playing a wind instrument. IOP often rises after playing wind instruments, but similar or even higher IOP levels seem to occur during common other daily activities or at night. These peaks may be relevant for glaucomatous field progression and treatment of glaucoma patients.

  4. Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates

    DEFF Research Database (Denmark)

    Convey, Peter; Abbandonato, Holly; Bergan, Frode

    2015-01-01

    The extreme polar environment creates challenges for its resident invertebrate communities and the stress tolerance of some of these animals has been examined over many years. However, although it is well appreciated that standard air temperature records often fail to describe accurately conditio...... polar soil invertebrate community may be robust to at least one important predicted consequence of projected climate change....... may insulate terrestrial habitats from extreme air temperature fluctuations. Further, climate projections suggest large changes in precipitation will occur in the polar regions, with the greatest changes expected during the winter period and, hence, implications for the insulation of overwintering...... microhabitats. To assess survival of natural High Arctic soil invertebrate communities contained in soil and vegetation cores to natural winter temperature variations, the overwintering temperatures they experienced were manipulated by deploying cores in locations with varying snow accumulation: No Snow...

  5. Increased heterozygosity at the Mdh-B locus in fish inhabiting a rapidly fluctuating thermal environment

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, E.G.; Richmond, M.C.

    1981-05-01

    Populations of a common forage fish, red shiner Notropis lutrensis, were sampled from four localities on the Brazos River, Texas, affected by cold-water discharge from a hydroelectric dam and from unaltered sites in the same region. Polymorphism at the Mdh-B locus, encoding supernatant malate dehydrogenase, indicates that populations within 57 km of the dam are distinctive from other regional populations and possess a unique Mdh-B allele, have significantly higher levels of heterozygosity at the Mdh-B locus, represent a homogeneous set that have significantly different Mdh-B zygotic frequencies from other regional populations, and have significantly different Mdh-B zygotic proportions than would be expected under a Hardy-Weinberg equilibrium. Increased levels of heterozygosity in fish within 57 km of the dam were correlated with discharge-associated fluctuations in water temperature at sampling stations.

  6. [Fluctuation of intraocular pressure in 24-hour telemonitoring compared to tonometry during normal office hours].

    Science.gov (United States)

    Jürgens, C; Antal, S; Henrici, K; Grossjohann, R; Tost, F H

    2009-01-01

    Elevated intraocular pressure (IOP) is a clinically relevant factor in glaucoma progression. As a dynamic parameter the IOP depends on various internal and exogenic influencing factors. Therefore, we analysed intraindividual IOD variations between ambulant care and 24-h home-monitoring using self-tonometry. This study is based on paper-based glaucoma cards of 25 patients with primary open angle glaucoma. Additionally, all patients participated in a telemedical home-monitoring study with self-measurements of IOP and blood pressure stored in an electronic patient record. The glaucoma cards contained a total number of 409 IOP values with documentation periods from 0.5 to 10 years. In the teletonometry project all 25 patients were observed for 6 months with 1490 recorded IOP values. Statistical analysis was performed with SPSS software. Average IOP values for all 25 glaucoma patients were 16.3 +/- 2.9 mmHg for both eyes in glaucoma card documentation, whereas the electronic patient records showed IOP averages of 18.9 +/- 4.7 mmHg for right eyes and 18.2 +/- 4.4 mmHg for left eyes. Corresponding to the practice opening hours the glaucoma cards contained no IOP records from 12:00 pm to 01:30 pm as well as between 06:00 pm and 07:15 am. In these time periods 17 % of all IOP values recorded in 24-hour teletonometry were higher than 20 mmHg. However, statistical analysis and clinical evaluation of device parameters and measurement characteristics revealed sporadic measuring errors. The additional involvement of self-tonometry in telemedical 24-h home-monitoring is a feasible method to record and detect intraday IOP fluctuations. Compared to single IOP measurements documented in common paper-based glaucoma cards, the 24-h electronic patient record showed more frequent circadian IOP variations. As a result, self-tonometry and home-monitoring can be a useful link to fill the gap between singular ambulant IOP measurement and hospitalisation with 24-hour IOP profiles.

  7. Comparison of fluctuations of intraocular pressure before and after selective laser trabeculoplasty in normal-tension glaucoma patients.

    Science.gov (United States)

    Tojo, Naoki; Oka, Miyako; Miyakoshi, Akio; Ozaki, Hironori; Hayashi, Atsushi

    2014-01-01

    The aim of this study was to examine the effects of selective laser trabeculoplasty (SLT) treatment on habitual intraocular pressure (IOP) fluctuations in patients with normal-tension glaucoma (NTG) using a SENSIMED Triggerfish contact lens sensor (CLS). Ten patients diagnosed with NTG were enrolled in this study. All patients underwent SLT treatment. Habitual 24-hour IOP fluctuations were recorded before and after SLT. The IOP fluctuations were divided into diurnal periods and nocturnal periods and compared before and after SLT. Changes in corneal thickness and curvature were measured before and after the CLS use with anterior segment optical coherence tomography. The mean IOP was 13.5±2.5 mm Hg before SLT. The mean IOP at 1, 2, and 3 months after SLT was significantly decreased to 10.1±2.3 mm Hg (P=0.002), 11.2±2.7 mm Hg (P=0.0059), and 11.3±2.4 mm Hg (P=0.018), respectively. The range of IOP fluctuations over 24 hours was not significantly changed between before and after SLT treatment (P=0.77). Although the range of IOP fluctuations during the diurnal periods was not significantly changed between before and after SLT treatment (P=0.92), the range of IOP fluctuations during the nocturnal periods significantly decreased from 290±86 mVEq before SLT to 199±31 mVEq after SLT treatment (P=0.014). With respect to corneal changes, the steeper meridian decreased significantly after the CLS use (P=0.016), although other parameters showed no significant difference between before and after the CLS use. SLT treatment was shown to significantly lower IOP and decrease IOP fluctuations during the nocturnal periods in NTG patients. These effects might be important to prevent the progression of NTG.

  8. Fluctuations of the Intraocular Pressure in Pseudoexfoliation Syndrome and Normal Eyes Measured by a Contact Lens Sensor.

    Science.gov (United States)

    Tojo, Naoki; Hayashi, Atsushi; Otsuka, Mitsuya; Miyakoshi, Akio

    2016-05-01

    We compared the fluctuation of the intraocular pressure (IOP) in patients with pseudoexfoliation syndrome (PE) and individuals with normal healthy eyes. We measured continuous IOP using a SENSIMED Triggerfish contact lens sensor (CLS). Eleven eyes with PE and 11 healthy eyes were examined. In all 22 participants, the IOP fluctuation was measured continuously for 24 hours with a CLS. The CLS could measure every 5 minutes. We evaluated IOP fluctuations over the 24-hour period separately for diurnal IOP and nocturnal IOP. We also identified each participant's maximum value. Changes in the corneal thickness and the corneal curvature were measured before and after the CLS use with anterior-segment optical coherence tomography. The mean IOP within the PE eyes was 20.3±3.9 mm Hg and that in the healthy eyes was 13.1±2.1 mm Hg (P<0.001). The 24-hour range of IOP fluctuations in the PE group was significantly larger than that in the healthy group (P=0.004). The central corneal thickness was significantly thicker after CLS use (P=0.011). The steeper meridian changed slightly to myopia (P=0.0068). All healthy eyes had their maximum value during the nocturnal period, whereas 7 of the 11 PE eyes (64%) had their maximum value in the nocturnal period. The IOP fluctuation was larger in the eyes with PE than in the healthy eyes. This larger fluctuation might be one of the reasons underlying the aggravation of the visual field by PE. Measurements of 24-hour continuous IOP might be useful to evaluate IOP fluctuation.

  9. Atmospheric pressure fluctuations in the far infrasound range and emergency transport events coded as circulatory system diseases.

    Science.gov (United States)

    Didyk, L A; Gorgo, Yu P; Dirckx, J J J; Bogdanov, V B; Buytaert, J A N; Lysenko, V A; Didyk, N P; Vershygora, A V; Erygina, V T

    2008-09-01

    This study examines whether a relation exists between rapid atmospheric pressure fluctuations, attributed to the far infrasound frequency range (APF), and a number of emergency transport events coded as circulatory system diseases (EEC). Over an entire year, the average integral amplitudes of APF in the range of periods from 3 s to 120 s over each hour (HA) were measured. Daily dynamics of HA averaged over the year revealed a wave shape with smooth increase from night to day followed by decrease from day to night. The total daily number of EEC within the city of Kiev, Ukraine, was related to the daily mean of HA (DHA) and to the ratio of HA averaged over the day time to HA averaged over the night time (Rdn), and was checked for confounding effects of classical meteorological variables through non-parametric regression algorithms. The number of EEC were significantly higher on days with high DHA (3.72-11.07 Pa, n = 87) compared to the low DHA (0.7-3.62 Pa, n = 260, p = 0.01), as well at days with low Rdn (0.21-1.64, n = 229) compared to the high Rdn (1.65-7.2, n = 118, p = 0.03). A difference between DHA and Rdn effects on the emergency events related to different categories of circulatory diseases points to a higher sensitivity of rheumatic and cerebro-vascular diseases to DHA, and ischaemic and hypertensive diseases to Rdn. Results suggest that APF could be considered as a meteorotropic factor capable of influencing circulatory system diseases.

  10. Use of Heated Helium to Simulate Surface Pressure Fluctuations on the Launch Abort Vehicle During Abort Motor Firing

    Science.gov (United States)

    Panda, Jayanta; James, George H.; Burnside, Nathan J.; Fong, Robert; Fogt, Vincent A.

    2011-01-01

    The solid-rocket plumes from the Abort motor of the Multi-Purpose Crew Vehicle (MPCV, also know as Orion) were simulated using hot, high pressure, Helium gas to determine the surface pressure fluctuations on the vehicle in the event of an abort. About 80 different abort situations over a wide Mach number range, (0.3abort case, typically two different Helium plume and wind tunnel conditions were used to bracket different flow matching critera. This unique, yet cost-effective test used a custom-built hot Helium delivery system, and a 6% scale model of a part of the MPCV, known as the Launch Abort Vehicle. The test confirmed the very high level of pressure fluctuations on the surface of the vehicle expected during an abort. In general, the fluctuations were found to be dominated by the very near-field hydrodynamic fluctuations present in the plume shear-layer. The plumes were found to grow in size for aborts occurring at higher flight Mach number and altitude conditions. This led to an increase in the extent of impingement on the vehicle surfaces; however, unlike some initial expectations, the general trend was a decrease in the level of pressure fluctuations with increasing impingement. In general, the highest levels of fluctuations were found when the outer edges of the plume shear layers grazed the vehicle surface. At non-zero vehicle attitudes the surface pressure distributions were found to become very asymmetric. The data from these wind-tunnel simulations were compared against data collected from the recent Pad Abort 1 flight test. In spite of various differences between the transient flight situation and the steady-state wind tunnel simulations, the hot-Helium data were found to replicate the PA1 data fairly reasonably. The data gathered from this one-of-a-kind wind-tunnel test fills a gap in the manned-space programs, and will be used to establish the acoustic environment for vibro-acoustic qualification testing of the MPCV.

  11. Circadian Intraocular Pressure Fluctuation and Disease Progression in Primary Angle Closure Glaucoma

    National Research Council Canada - National Science Library

    Tan, Shaoying; Yu, Marco; Baig, Nafees; Chan, Poemen Pui-man; Tang, Fang Yao; Tham, Clement C

    2015-01-01

    .... Circadian IOP fluctuations were recorded by Sensimed Triggerfish sensors in 25 PACG eyes. The sensor output signals were smoothed using B-spline smoothing transform and described by functional data analysis...

  12. BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, AND POPULATION GRADIENTS IN LOW-MASS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    El-Badry, Kareem; Geha, Marla [Department of Astronomy, Yale University, New Haven, CT (United States); Wetzel, Andrew; Hopkins, Philip F. [TAPIR, California Institute of Technology, Pasadena, CA USA (United States); Kereš, Dusan; Chan, T. K. [Department of Physics, Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla (United States); Faucher-Giguère, Claude-André, E-mail: kareem.el-badry@yale.edu [Department of Physics and Astronomy and CIERA, Northwestern University, Evanston, IL (United States)

    2016-04-01

    We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (M{sub star} = 2 × 10{sup 6} − 5 × 10{sup 10} M{sub ⊙}) using the Feedback in Realistic Environments (FIRE) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate ∼1 kpc within their first 100 Myr, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies’ effective radii can fluctuate by factors of >2 over ∼200 Myr, and these rapid size fluctuations can account for much of the observed scatter in the radius at fixed M{sub star}. Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes—and even inverts—intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star formation histories from stellar populations at z = 0 can be severely biased. These effects are strongest at M{sub star} ≈ 10{sup 7–9.6} M{sub ⊙}, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in ΛCDM.

  13. Detection of the Earth rotation response to a rapid fluctuation of Southern Ocean circulation in November 2009

    Science.gov (United States)

    Marcus, S. L.; Dickey, J. O.; Fukumori, I.; de Viron, O.

    2012-02-01

    At seasonal and shorter periods the solid Earth and its overlying geophysical fluids form a closed dynamical system, which (except for tidal forcing) conserves its total angular momentum. While atmospheric effects dominate changes in the Earth's rate of rotation and hence length-of-day (LOD) on these time scales, the addition of oceanic angular momentum (OAM) estimates has been shown to improve closure of the LOD budget in a statistical sense. Here we demonstrate, for the first time, the signature of a specific, sub-monthly ocean current fluctuation on the Earth's rotation rate, coinciding with recently-reported anomalies which developed in southeast Pacific surface temperature and bottom pressure fields during late 2009. Our results show that concurrent variations in the Antarctic Circumpolar Current (ACC), which saw a sharp drop and recovery in zonal transport during a two-week period in November, were strong enough to cause a detectable change in LOD following the removal of atmospheric angular momentum (AAM) computed from the Modern Era Retrospective Analysis for Research and Applications (MERRA) database. The strong OAM variations driving the LOD-AAM changes were diagnosed from ocean state estimates of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO) and involved roughly equal contributions from the current and pressure terms, with in situ confirmation for the latter provided by tide-corrected bottom pressure recorder data from the South Drake Passage site of the Antarctic Circumpolar Current Levels by Altimetry and Island Measurements (ACCLAIM) network.

  14. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations.

    Science.gov (United States)

    Tricomi, Leonardo; Melchiori, Tommaso; Chiaramonti, David; Boulet, Micaël; Lavoie, Jean Michel

    2017-01-01

    Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal's energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum.

  15. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations

    Directory of Open Access Journals (Sweden)

    Leonardo Tricomi

    2017-06-01

    Full Text Available Based upon the two fluid model (TFM theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law, restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal’s energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum.

  16. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations

    Science.gov (United States)

    Tricomi, Leonardo; Melchiori, Tommaso; Chiaramonti, David; Boulet, Micaël; Lavoie, Jean Michel

    2017-01-01

    Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal’s energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum. PMID:28695119

  17. Estimation of Kubo number and correlation length of fluctuating magnetic fields and pressure in BOUT + + edge pedestal collapse simulation

    Science.gov (United States)

    Kim, Jaewook; Lee, W.-J.; Jhang, Hogun; Kaang, H. H.; Ghim, Y.-C.

    2017-10-01

    Stochastic magnetic fields are thought to be as one of the possible mechanisms for anomalous transport of density, momentum and heat across the magnetic field lines. Kubo number and Chirikov parameter are quantifications of the stochasticity, and previous studies show that perpendicular transport strongly depends on the magnetic Kubo number (MKN). If MKN is smaller than one, diffusion process will follow Rechester-Rosenbluth model; whereas if it is larger than one, percolation theory dominates the diffusion process. Thus, estimation of Kubo number plays an important role to understand diffusion process caused by stochastic magnetic fields. However, spatially localized experimental measurement of fluctuating magnetic fields in a tokamak is difficult, and we attempt to estimate MKNs using BOUT + + simulation data with pedestal collapse. In addition, we calculate correlation length of fluctuating pressures and Chirikov parameters to investigate variation correlation lengths in the simulation. We, then, discuss how one may experimentally estimate MKNs.

  18. Posterior reversible encephalopathy syndrome in Parkinson disease probably caused by prominent supine hypertension and blood pressure fluctuation.

    Science.gov (United States)

    Morozumi, Saori; Kato, Shigenori; Yasui, Keizo; Hasegawa, Yasuhiro

    2016-11-29

    We present the case of a 77-year-old man with a 10-year history of Parkinson disease (PD), who developed posterior reversible encephalopathy syndrome (PRES). We diagnosed the case as PRES based on clinical features and MRI findings. He experienced orthostatic hypotension and supine hypertension, including nocturnal hypertension. PRES may result from marked supine/nocturnal hypertension and fluctuation in blood pressure. In addition, exacerbated factors could be representative of neuroleptic malignant syndrome. The hypertensive effect of istradefylline should also not be excluded. We believe this is the first case report of a patient with PD developing PRES without vasopressor use.

  19. Time-frequency analysis of Hilbert spectrum of pressure fluctuation time series in a Kenics Static Mixer based on empirical mode decomposition

    Directory of Open Access Journals (Sweden)

    Huibo Meng

    2012-03-01

    Full Text Available The turbulent flow in a Kenics Static Mixer (KSM was intensified under the mutual-coupling effect between the twisted leaves and the tube-wall. In order to understand the intrinsic features of turbulent flow in KSM, the Hilbert-Huang Transform based on Empirical Mode Decomposition were first introduced to describe the time-frequency features of the pressure fluctuation. The Hilbert spectra of pressure fluctuation time series were quantitatively evaluated under different Reynolds numbers, and different radial and axial positions, respectively. The experimental results showed that: the fluctuation frequencies of pressure signals in a KSM were mainly distributed below 40 Hz, and more than 68% of the energy of signals is concentrated within 10 Hz. Compared with the other IMFs, the pressure component of C6 in the range of 7.82~15.63 Hz has the maximum fluctuation energy ratio. As the flow rate increases, the energy of fluctuation of fluid micelles and the proportion of low-frequency energy increases. The pressure fluctuation with higher energy ratio of low frequency (0~10 Hz had lower amplitudes at r/R=0.3 because of the core of forced vortex. Nevertheless, the effect of the free vortex was that the pressure fluctuation with lower energy ratio of low frequency had higher amplitudes at r/R=0.8. The higher amplitudes of pressure fluctuation at cross sections of CS3 (z=420 mm and CS5 (z=620 mm proved that the transitions between the adjacent mixing element had better mixing performance.

  20. Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion.

    Science.gov (United States)

    Padurariu, Simona; de Greef, Daniël; Jacobsen, Henrik; Nlandu Kamavuako, Ernest; Dirckx, Joris J; Gaihede, Michael

    2016-10-01

    The tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance. The pressure changes in seven normal adult ME's with intact TM's were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle's Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could also be calculated. Finally, the correlation between the ME volume and buffer function was determined. Twenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3% (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10-3 μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R2 = 0.92). These results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. 24-hour intraocular pressure fluctuation monitoring using an ocular telemetry Sensor: tolerability and functionality in healthy subjects.

    Science.gov (United States)

    De Smedt, Stefan; Mermoud, André; Schnyder, Corinne

    2012-01-01

    To evaluate the tolerability, comfort, and reliability of the signal transmission of an ocular Sensor used for 24-hour intraocular pressure fluctuation monitoring in humans. In this uncontrolled open trial involving 10 healthy volunteers, an 8.7-mm radius prototype ocular telemetry Sensor (SENSIMED Triggerfish, Lausanne, Switzerland) and an orbital bandage containing a loop antenna were applied and connected to a portable recorder after full eye examination. Best-corrected visual acuity and position, surface wetting ability, and mobility of the Sensor were assessed after 5 and 30 minutes, 4, 12, and 24 hours. Subjective wearing comfort was scored and activities documented in a logbook. After Sensor removal, a full eye examination was repeated and the recorded signal analyzed. The comfort score was high and did not fluctuate significantly over time. The mobility of the Sensor was limited across follow-up visits and its surface wetting ability remained good. Best-corrected visual acuity was significantly reduced during Sensor wear and immediately after its removal (from 1.07 before, to 0.85 after, P value 0.008). Three subjects developed a mild, transient corneal abrasion. In all but 1 participant, we obtained usable data of a telemetric signal recording with sufficient sensitivity to depict ocular pulsation. This 24-hour trial has encouraging results on the tolerability and functionality of the ocular telemetric Sensor for intraocular pressure fluctuation monitoring. Further studies with different Sensor radii conducted on a larger study population are needed to improve comfort, precision, and interpretation of the telemetric signal.

  2. Sulphate chemistry under pressurized oxidizing, reducing and fluctuating conditions; Sulfatkemi under trycksatta oxiderande, reducerande och fluktuerande foerhaallanden

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Yrjas, P.; Backman, P. [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-10-01

    In the literature it has been reported that sulfur capture with limestone (CaCO{sub 3}) under atmospheric fluidized bed combustion conditions reaches a maximum at about 850 deg C. Previously, the maximum has been attributed to the sintering of sorbent particles which decreases the reactive surface area. Lately, also another explanation has been reported. In this case the sulfur capture decrease at higher temperatures was concluded to be due to fluctuating oxidizing/reducing conditions in the atmospheric combustor. In this work the influence of alternating oxidizing/reducing conditions on SO{sub 2} capture at atmospheric and elevated pressure (15 bar) has been studied. In the pressurized case, the CO{sub 2} partial pressure was kept high enough to prevent CaCO{sub 3} from calcining and therefore the CaSO{sub 4} would not form CaO but CaCO{sub 3} under reducing conditions. The experiments were done with a pressurized TGA by periodically changing the gas environment between oxidizing (O{sub 2}. SO{sub 2}, CO{sub 2} and N{sub 2}) and slightly reducing (CO, SO{sub 2}, CO{sub 2} and N{sub 2}) gas mixtures at different temperatures. The results from the experiments showed that under normal pressure and slightly reducing conditions CaO formation from CaSO{sub 4} increased with temperature as expected. However, no significant amounts of CaCO{sub 3} were formed from CaSO{sub 4} at elevated pressure. It was also concluded that since the formation of CaO from CaSO{sub 4} was relatively slow it could not explain the sharp sulfur capture maximum at about 850 deg C. Therefore, it was assumed that the strongly reducing zones, where CaS thermodynamically is the stable compound, play a more important role concerning the sulfur capture in fluidized bed combustors. (orig.)

  3. Measurement of Pressure Fluctuations inside a Model Thrust Bearing Using PVDF Sensors

    Science.gov (United States)

    Youssef, Andrew; Matthews, David; Guzzomi, Andrew; Pan, Jie

    2017-01-01

    Thrust bearings play a vital role in propulsion systems. They rely on a thin layer of oil being trapped between rotating surfaces to produce a low friction interface. The “quality” of this bearing affects many things from noise transmission to the ultimate catastrophic failure of the bearing itself. As a result, the direct measure of the forces and vibrations within the oil filled interface would be very desirable and would give an indication of the condition of the bearing in situ. The thickness of the oil film is, however, very small and conventional vibration sensors are too cumbersome to use in this confined space. This paper solves this problem by using a piezoelectric polymer film made from Polyvinylidine Fluoride (PVDF). These films are very thin (50 μm) and flexible and easy to install in awkward spaces such as the inside of a thrust bearing. A model thrust bearing was constructed using a 3D printer and PVDF films inserted into the base of the bearing. In doing so, it was possible to directly measure the force fluctuations due to the rotating pads and investigate various properties of the thrust bearing itself. PMID:28420152

  4. 8-13 Hz fluctuations in rectal pressure are an objective marker of clitorally-induced orgasm in women.

    Science.gov (United States)

    van Netten, Jaap J; Georgiadis, Janniko R; Nieuwenburg, Arie; Kortekaas, Rudie

    2008-04-01

    Orgasm is a subjective experience accompanied by involuntary muscle contractions. We hypothesized that orgasm in women would be distinguishable by frequency analysis of a perineal muscle-derived signal. Rectal pressure, an index of perineal muscle activity, was measured continuously in 23 healthy women during different sexual tasks: receiving clitoral stimulation, imitation of orgasm, and attempt to reach orgasm, in which case the women were asked to report whether orgasm had been reached ("orgasm") or not ("failed orgasm attempt"). We performed spectral analysis on the rectal pressure data and calculated the spectral power in the frequency bands delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), and beta (13-25 Hz). The most significant and most important difference in spectral power between orgasm and both control motor tasks (imitation of orgasm and failed orgasm attempt) was found in the alpha band. An objective rule based on spectral power in the alpha band recognized 94% (29/31) of orgasms and correctly labeled 69% (44/64) of all orgasm attempts as either successful or failed. Because outbursts of alpha fluctuations in rectal pressure only occurred during orgasm and not during voluntary imitation of orgasm or failed attempts, we propose that they represent involuntary contractions of muscles in the rectal vicinity. This is the first objective and quantitative measure that has a strong correspondence with the subjective experience of orgasm.

  5. Diurnal fluctuation of higher order ocular aberrations: correlation with intraocular pressure and corneal thickness.

    Science.gov (United States)

    Mierdel, Peter; Krinke, Hans-Eberhard; Pollack, Katharina; Spoerl, Eberhard

    2004-01-01

    Optimal wavefront-guided refractive corneal laser surgery requires sufficiently exact data of optical higher order aberrations. We investigated whether these aberrations had a systematic during-the-day variation, studied the range of variation, and changes in intraocular pressure and central corneal thickness. In 22 eyes of 22 young volunteers the optical aberrations of higher order were measured by means of a Tscherning-type ocular aberrometer three times during one day (7 AM, 12 noon, 4 PM). In addition, in 12 of these eyes the intraocular pressure and central corneal thickness were measured. The intraocular wavefront aberration was computed using Zernike polynomials up to the sixth order, and Zernike coefficients of third and fourth order were analyzed. Only the coefficient Z 2/4 (C13) showed a significant increase during the day by a mean 0.016 microm. A significant regression could be detected between changes of coefficients Z3/3, Z-2/4, Z0/4, Z4/4, and changes of intraocular pressure or central corneal thickness during the day. Due to the small values, the measured during-the-day changes of higher order aberrations had no direct practical consequences for the aberrometry-guided corneal laser surgery. Alterations of some Zernike coefficients during the day may be explained by the biomechanical behavior of the cornea.

  6. Sound Transmission through Cylindrical Shell Structures Excited by Boundary Layer Pressure Fluctuations

    Science.gov (United States)

    Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

    1996-01-01

    This paper examines sound transmission into two concentric cylindrical sandwich shells subject to turbulent flow on the exterior surface of the outer shell. The interior of the shells is filled with fluid medium and there is an airgap between the shells in the annular space. The description of the pressure field is based on the cross-spectral density formulation of Corcos, Maestrello, and Efimtsov models of the turbulent boundary layer. The classical thin shell theory and the first-order shear deformation theory are applied for the inner and outer shells, respectively. Modal expansion and the Galerkin approach are used to obtain closed-form solutions for the shell displacements and the radiation and transmission pressures in the cavities including both the annular space and the interior. The average spectral density of the structural responses and the transmitted interior pressures are expressed explicitly in terms of the summation of the cross-spectral density of generalized force induced by the boundary layer turbulence. The effects of acoustic and hydrodynamic coincidences on the spectral density are observed. Numerical examples are presented to illustrate the method for both subsonic and supersonic flows.

  7. Low frequency geomagnetic field fluctuations at low latitude during the passage of a higher pressure solar wind region

    Directory of Open Access Journals (Sweden)

    U. Villante

    1997-06-01

    Full Text Available The passage of a higher pressure solar wind region at the Earth's orbit marked the onset of low latitude (L=1.6 fluctuations in the frequency range (0.8–5.5 mHz for both the horizontal geomagnetic field components. Spectral peaks mostly occur at the same frequencies as the spectral enhancements which appeared in the long term analysis of experimental measurements from the same station and were tentatively interpreted in terms of ground signatures of global magnetospheric modes. A comparison with simultaneous observations discussed by previous investigations allows us to conclude that the same set of frequencies is enhanced in a wide portion of the Earth's magnetosphere.

  8. Adaptation to fluctuating temperatures in an RNA virus is driven by the most stringent selective pressure.

    Directory of Open Access Journals (Sweden)

    María Arribas

    Full Text Available The frequency of change in the selective pressures is one of the main factors driving evolution. It is generally accepted that constant environments select specialist organisms whereas changing environments favour generalists. The particular outcome achieved in either case also depends on the relative strength of the selective pressures and on the fitness costs of mutations across environments. RNA viruses are characterized by their high genetic diversity, which provides fast adaptation to environmental changes and helps them evade most antiviral treatments. Therefore, the study of the adaptive possibilities of RNA viruses is highly relevant for both basic and applied research. In this study we have evolved an RNA virus, the bacteriophage Qβ, under three different temperatures that either were kept constant or alternated periodically. The populations obtained were analyzed at the phenotypic and the genotypic level to characterize the evolutionary process followed by the virus in each case and the amount of convergent genetic changes attained. Finally, we also investigated the influence of the pre-existent genetic diversity on adaptation to high temperature. The main conclusions that arise from our results are: i under periodically changing temperature conditions, evolution of bacteriophage Qβ is driven by the most stringent selective pressure, ii there is a high degree of evolutionary convergence between replicated populations and also among populations evolved at different temperatures, iii there are mutations specific of a particular condition, and iv adaptation to high temperatures in populations differing in their pre-existent genetic diversity takes place through the selection of a common set of mutations.

  9. Estimating of turbulent velocity fluctuations in boundary layer with pressure gradient by Smoke Image Velocimetry

    Science.gov (United States)

    Mikheev, N. I.; Goltsman, A. E.; Saushin, I. I.

    2017-11-01

    The results of the experimental estimating of the velocity profiles and turbulent pulsations in the boundary layer for adverse and favorable pressure gradients are presented. The profiles of characteristics based on the dynamics of two-component instantaneous velocity vector fields measured by the field optical method of Smoke Image Velocimetry are estimated. The measurements are performed with a large spatial and temporal resolution, the measurement results are relevant for estimating the terms of the conservation equation of turbulent energy in the boundary layer and for improving semiempirical turbulence models.

  10. Rapid control prototyping for cylinder pressure indication; Rapid Control Prototyping fuer Zylinderdruckindizierung

    Energy Technology Data Exchange (ETDEWEB)

    Pfluger, Jan [RWTH Aachen Univ. (Germany). Lehrstuhl fuer Verbrennungskraftmaschinen; Andert, Jakob [FEV GmbH, Aachen (Germany). Fahrzeugelektronik/E-Mobilitaet; Ross, Holger; Mertens, Frank [dSpace GmbH, Paderborn (Germany). Rapid Control Prototyping Systems

    2012-11-15

    Cylinder-pressure-based controls that allow cycle-synchronous reactions to events in the combustion chamber are a particularly promising possibility further optimising engine combustion processes. However, the requirements of real-time cylinder indication are fast pushing today's systems up against their limits. The Institute for Combustion Engines at RWTH Aachen University and dSpace together developed a high performance prototype for online indication with cycle-synchronous combustion control. (orig.)

  11. Renal blood flow regulation and arterial pressure fluctuations: a case study in nonlinear dynamics

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Marsh, D J

    1994-01-01

    of experimental hypertension provide tubular pressure records that pass statistical tests for ordered structure and sensitive dependence on initial conditions in the reconstructed state space, two of the hallmarks of deterministic chaos. These records also pass recent more stringent tests for chaos...... another in a long list of oscillations and related dynamics arising in the inherently nonlinear properties of living systems. Some nonlinear systems can bifurcate to states known collectively as deterministic chaos, and TGF is a clear example of such a system. Rats with two different and unrelated forms....... The significance of deterministic chaos in the context of renal blood flow regulation is that the system regulating blood flow undergoes a physical change to a different dynamical state, and because the change is deterministic, there is every expectation that the critical change will yield itself to experimental...

  12. Pressure and Quantity Thresholds for Ignition of Oil Contamination by Rapid Pressurization in Oxygen Systems

    Science.gov (United States)

    Tapia, Susana; Smith, Sarah; Peralta, Steve; Stoltzfus, Joel

    2009-01-01

    This slide presentation reviews the problem and solution of oil contamination and increased ignition hazard in oxygen systems. The experiments that were used are reviewed, and the contamination level threshold and the oxygen pressure threshold are reviewed.

  13. Analysis of wind-induced dynamic pressure fluctuations during one and a half Martian years at Gale Crater

    Science.gov (United States)

    Ullán, Aurora; Zorzano, María-Paz; Javier Martín-Torres, Francisco; Valentín-Serrano, Patricia; Kahanpää, Henrik; Harri, Ari-Matti; Gómez-Elvira, Javier; Navarro, Sara

    2017-05-01

    The Rover Environmental Monitoring Station (REMS) instrument on-board the Mars Science Laboratory (MSL) has acquired unprecedented measurements of key environmental variables at the base of Gale Crater. The pressure measured by REMS shows modulations with a very structured pattern of short-time scale (of the order of seconds to several minutes) mild fluctuations (typically up to 0.2 Pa at daytime and 1 Pa at night-time). These dynamic pressure oscillations are consistent with wind, air and ground temperature modulations measured simultaneously by REMS. We detect the signals of a repetitive pattern of upslope/downslope winds, with maximal speeds of about 21 m/s, associated with thermal changes in the air and surface temperatures, that are initiated after sunset and finish with sunrise proving that Gale, a 4.5 km deep impact crater, is an active Aeolian environment. At nighttime topographic slope winds are intense with maximal activity from 17:00 through 23:00 Local Mean Solar Time, and simultaneous changes of surface temperature are detected. During the day, the wind modulations are related to convection of the planetary boundary layer, winds are softer with maximum wind speed of about 14 m/s. The ground temperature is modulated by the forced convection of winds, with amplitudes between 0.2 K and 0.5 K, and the air temperatures fluctuate with amplitudes of about 2 K. The analysis of more than one and a half Martian years indicates the year-to-year repeatability of these environmental phenomena. The wind pattern minimizes at the beginning of the south hemisphere winter (Ls 90) season and maximizes during late spring and early summer (Ls 270). The procedure that we present here is a useful tool to investigate in a semi-quantitative way the winds by: i) filling both seasonal and diurnal gaps where wind measurements do not exist, ii) providing an alternative way for comparisons through different measuring principia and, iii) filling the gap of observation of short

  14. Assessing fluctuating evolutionary pressure in yeast and mammal evolutionary rate covariation using bioinformatics of meiotic protein genetic sequences

    Science.gov (United States)

    Dehipawala, Sunil; Nguyen, A.; Tremberger, G.; Cheung, E.; Holden, T.; Lieberman, D.; Cheung, T.

    2013-09-01

    The evolutionary rate co-variation in meiotic proteins has been reported for yeast and mammal using phylogenic branch lengths which assess retention, duplication and mutation. The bioinformatics of the corresponding DNA sequences could be classified as a diagram of fractal dimension and Shannon entropy. Results from biomedical gene research provide examples on the diagram methodology. The identification of adaptive selection using entropy marker and functional-structural diversity using fractal dimension would support a regression analysis where the coefficient of determination would serve as evolutionary pathway marker for DNA sequences and be an important component in the astrobiology community. Comparisons between biomedical genes such as EEF2 (elongation factor 2 human, mouse, etc), WDR85 in epigenetics, HAR1 in human specificity, clinical trial targeted cancer gene CD47, SIRT6 in spermatogenesis, and HLA-C in mosquito bite immunology demonstrate the diagram classification methodology. Comparisons to the SEPT4-XIAP pair in stem cell apoptosis, testesexpressed taste genes TAS1R3-GNAT3 pair, and amyloid beta APLP1-APLP2 pair with the yeast-mammal DNA sequences for meiotic proteins RAD50-MRE11 pair and NCAPD2-ICK pair have accounted for the observed fluctuating evolutionary pressure systematically. Regression with high R-sq values or a triangular-like cluster pattern for concordant pairs in co-variation among the studied species could serve as evidences for the possible location of common ancestors in the entropy-fractal dimension diagram, consistent with an example of the human-chimp common ancestor study using the FOXP2 regulated genes reported in human fetal brain study. The Deinococcus radiodurans R1 Rad-A could be viewed as an outlier in the RAD50 diagram and also in the free energy versus fractal dimension regression Cook's distance, consistent with a non-Earth source for this radiation resistant bacterium. Convergent and divergent fluctuating evolutionary

  15. On the phase between pressure and heat release fluctuations for propane/hydrogen flames and its role in mode transitions

    KAUST Repository

    Hong, Seunghyuck

    2013-12-01

    This paper presents an experimental investigation into mode-transitions observed in a 50-kW, atmospheric pressure, backward-facing step combustor burning lean premixed C3H8/H2 fuel mixtures over a range of equivalence ratios, fuel compositions and preheat temperatures. The combustor exhibits distinct acoustic response and dynamic flame shape (collectively referred to as "dynamic modes") depending on the operating conditions. We simultaneously measure the dynamic pressure and flame chemiluminescence to examine the phase between pressure (p\\') and heat release fluctuations (q\\') in the observed dynamic modes. Results show that the heat release is in phase with the pressure oscillations (θqp≈0) at the onset of a dynamic mode, while as the operating conditions change within the mode, the phase grows until it reaches a critical value θqp=θc, at which the combustor switches to another dynamic mode. According to the classical Rayleigh criterion, this critical phase (θc) should be π/2, whereas our data show that the transition occurs well below this value. A linear acoustic energy balance shows that this critical phase marks the point where acoustic losses across the system boundaries equal the energy addition from the combustion process to the acoustic field. Based on the extended Rayleigh criterion in which the acoustic energy fluxes through the system boundaries as well as the typical Rayleigh source term (p\\'q\\') are included, we derive an extended Rayleigh index defined as Re=θqp/θc, which varies between 0 and 1. This index, plotted against a density-weighted strained consumption speed, indicates that the impact of the operating parameters on the dynamic mode selection of the combustor collapses onto a family of curves, which quantify the state of the combustor within a dynamic mode. At Re=0, the combustor enters a mode, and switches to another as Re approaches 1. The results provide a metric for quantifying the instability margins of fuel

  16. Effect of reduced atmospheric pressure on patients with fluctuating hearing loss due to Ménière's disease.

    Science.gov (United States)

    Younger, R; Longridge, N S; Mekjavic, I

    1984-04-01

    Subjective symptomatic and objective audiologic effects of reduced atmospheric pressure on patients with confirmed fluctuating hearing loss due to Ménière's disease were statistically assessed on a prospective basis. The effect of hypobaric environments on absolute hearing thresholds was investigated in 10 normal subjects at 6,500 ft. Absolute hearing threshold levels obtained at altitude, after one hour altitude exposure, and on descent to normobaric conditions were compared with levels obtained prior to the hypobaric exposure. The results indicated slightly increasing sensitivity of the audiometer headphones with altitude and an insignificant difference in hearing threshold when comparing the differing experimental conditions. The Ménière's disease study group of 16 patients was followed symptomatically and audiologically for one year prehypobaric exposure and for one month post-treatment. The results in this group utilizing the same experimental protocol as with normal subjects indicated a mild deterioration of hearing in the lower frequencies (1,000, 2,000 Hz and calculating the Ménière's pure tone average) despite significant improvements in the vertigo and disability components of their disease.

  17. Influence of Prewhirl Angle and Axial Distance on Energy Performance and Pressure Fluctuation for a Centrifugal Pump with Inlet Guide Vanes

    Directory of Open Access Journals (Sweden)

    Yabin Liu

    2017-05-01

    Full Text Available The energy performance and pressure fluctuations in a centrifugal pump with inlet guide vanes (IGVs are investigated experimentally and numerically in a prewhirl angle range of −24° to 24° and in an axial distance range of 280 mm, 380 mm, and 460 mm. The reliability and accuracy of the numerical method are validated by the satisfactory agreement between the experimental data and numerical results. Prewhirl regulation with IGVs can significantly increase the energy performance and broaden the efficient operation range for the centrifugal pump due to the improvement of flow pattern at the impeller inlet. The prewhirl angle has an obvious impact on pump energy performance, and the maximum amplitudes of pressure fluctuations on the blade leading edge of the pressure and suction sides decrease by 69% and 89%, respectively. The axial distance has a slight impact on pump energy performance, but the maximum amplitudes of pressure fluctuations drop by 35.4% on the blade leading edge of pressure side when the axial distance extends from 280 mm to 460 mm.

  18. Continuous positive airway pressure (CPAP) changes in bariatric surgery patients undergoing rapid weight loss.

    Science.gov (United States)

    Lankford, D Alan; Proctor, Charles D; Richard, Robert

    2005-03-01

    Obstructive sleep apnea (OSA) is a common condition in morbidly obese patients, with the reported prevalence ranging from 12-78%. There is increasing recognition of the need to diagnose and treat/manage OSA both preoperatively and postoperatively. Nasal CPAP is the preferred treatment of OSA; however, weight loss is associated with a reduction in required pressures. We evaluated the CPAP pressure requirements in a group of patients undergoing rapid weight loss following Roux-en-Y gastric bypass. 15 patients who had been diagnosed with OSA before surgery were retrospectively evaluated. All patients had demonstrated compliance on home CPAP therapy, were minimally 3 months post-surgery and had follow-up reports that their CPAP was less effective. We obtained data on age, sex, weight, BMI, and apnea/hypopnea index (AHI). Optimal CPAP pressure was obtained initially through attended in-laboratory complex polysomnography. Follow-up CPAP pressure was obtained using an auto-titrating PAP device at home. These data were used to evaluate the pressure changes that accompanied weight loss. This group of patients had lost an average of 44.5 +/- 19.4 kg. Four patients had achieved their goal weight. Their starting CPAP pressures averaged 11 +/- 3.0 cm H2O, with a range of 7-18 cm H2O. Follow-up CPAP pressures averaged 9 +/- 2.7 cm H2O, with a range of 4-12 cm H2O, representing an overall reduction of 18%. The subgroup of patients who had achieved goal weight had a pressure reduction of 22% (9 +/- 2.0 to 7 +/- 1.0 cm H2O). CPAP pressure requirements change considerably in bariatric surgery patients undergoing rapid weight loss. Auto-titrating PAP devices have promise for facilitating the management of CPAP therapy during this time. Consideration should also be given to the use of autotitrating PAP units as the treatment of choice in these patients.

  19. Pressure fluctuation prediction in pump mode using large eddy simulation and unsteady Reynolds-averaged Navier–Stokes in a pump–turbine

    Directory of Open Access Journals (Sweden)

    De-You Li

    2016-06-01

    Full Text Available For pump–turbines, most of the instabilities couple with high-level pressure fluctuations, which are harmful to pump–turbines, even the whole units. In order to understand the causes of pressure fluctuations and reduce their amplitudes, proper numerical methods should be chosen to obtain the accurate results. The method of large eddy simulation with wall-adapting local eddy-viscosity model was chosen to predict the pressure fluctuations in pump mode of a pump–turbine compared with the method of unsteady Reynolds-averaged Navier–Stokes with two-equation turbulence model shear stress transport k–ω. Partial load operating point (0.91QBEP under 15-mm guide vane opening was selected to make a comparison of performance and frequency characteristics between large eddy simulation and unsteady Reynolds-averaged Navier–Stokes based on the experimental validation. Good agreement indicates that the method of large eddy simulation could be applied in the simulation of pump–turbines. Then, a detailed comparison of variation for peak-to-peak value in the whole passage was presented. Both the methods show that the highest level pressure fluctuations occur in the vaneless space. In addition, the propagation of amplitudes of blade pass frequency, 2 times of blade pass frequency, and 3 times of blade pass frequency in the circumferential and flow directions was investigated. Although the difference exists between large eddy simulation and unsteady Reynolds-averaged Navier–Stokes, the trend of variation in different parts is almost the same. Based on the analysis, using the same mesh (8 million, large eddy simulation underestimates pressure characteristics and shows a better result compared with the experiments, while unsteady Reynolds-averaged Navier–Stokes overestimates them.

  20. A method for rapid measurement of intrarenal and other tissue pressures.

    Science.gov (United States)

    SWANN, H G; MONTGOMERY, A V; DAVIS, J C; MICKLE, E R

    1950-12-01

    A rapid method for measuring tissue pressures has been designed. A pressure of 250 mm. Hg is imposed on a manometer. Then the system is allowed to discharge into a needle cannula inserted in the tissue. The manometer forces out fluid (about 10 c.mm.) until the pressure within it is the same as that within the tissue. Records of the pressure changes are made. Each observation takes about a minute. The method gives results that are closely comparable with other reports of tissue pressures. With this method, the pressure in the following organs of dogs was found to be: kidney, 26 mm. Hg, cerebral cortex, 0 to 5 mm., muscle, 1 to 10 mm., spleen, S to 16 mm., subcutaneous tissue, 0 to 3 mm., and liver -2 to 14 mm. The reliability of the method was tested on the kidneys of decerebrate dogs. Measurements were found to be the same within narrow limits over a period of an hour; they were the same when taken simultaneously in different regions of the same kidney or in opposite kidneys. They were independent of the volume of fluid forced into the tissue. Similar pressures were observed with 1 or 5 or 10 holes bored in the shaft of the cannulating needle. The intrarenal pressure was also measured by inserting a needle cannula into the tissue and then allowing the pressure to reach equilibrium passively with a manometer. This method gave similar results. The intrarenal pressure has now found to be the same when measured by three different technics.

  1. Rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser.

    Science.gov (United States)

    Qu, Yanchen; Ren, Deming; Hu, Xiaoyong; Liu, Fengmei; Zhao, Jingshan

    2002-08-20

    An experimental study of a rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser is reported. To rapidly shift laser wavelengths over selected transitions in the 9-11 microm wavelength region, we have utilized a high-frequency stepping motor and a diffraction grating. The laser is highly automated with a monolithic microprocessor controlled laser line selection. For the achievement of stable laser output, a system of laser excitation with a voltage of 10 kV, providing effective surface corona preionization and allowing one to work at various gas pressures, is utilized. Laser operation at 59 emission lines of the CO2 molecule rotational transition is obtained and at 51 lines, the pulse energy of laser radiation exceeds 30 mJ. The system can be tuned between two different rotational lines spanning the wavelength range from 9.2 to 10.8 microm within 10 ms.

  2. Rapid fluctuations in extracellular brain glucose levels induced by natural arousing stimuli and intravenous cocaine: fueling the brain during neural activation

    Science.gov (United States)

    Lenoir, Magalie

    2012-01-01

    Glucose, a primary energetic substrate for neural activity, is continuously influenced by two opposing forces that tend to either decrease its extracellular levels due to enhanced utilization in neural cells or increase its levels due to entry from peripheral circulation via enhanced cerebral blood flow. How this balance is maintained under physiological conditions and changed during neural activation remains unclear. To clarify this issue, enzyme-based glucose sensors coupled with high-speed amperometry were used in freely moving rats to evaluate fluctuations in extracellular glucose levels induced by brief audio stimulus, tail pinch (TP), social interaction with another rat (SI), and intravenous cocaine (1 mg/kg). Measurements were performed in nucleus accumbens (NAcc) and substantia nigra pars reticulata (SNr), which drastically differ in neuronal activity. In NAcc, where most cells are powerfully excited after salient stimulation, glucose levels rapidly (latency 2–6 s) increased (30–70 μM or 6–14% over baseline) by all stimuli; the increase differed in magnitude and duration for each stimulus. In SNr, where most cells are transiently inhibited by salient stimuli, TP, SI, and cocaine induced a biphasic glucose response, with the initial decrease (−20–40 μM or 5–10% below baseline) followed by a reboundlike increase. The critical role of neuronal activity in mediating the initial glucose response was confirmed by monitoring glucose currents after local microinjections of glutamate (GLU) or procaine (PRO). While intra-NAcc injection of GLU transiently increased glucose levels in this structure, intra-SNr PRO injection resulted in rapid, transient decreases in SNr glucose. Therefore, extracellular glucose levels in the brain change very rapidly after physiological and pharmacological stimulation, the response is structure specific, and the pattern of neuronal activity appears to be a critical factor determining direction and magnitude of physiological

  3. Rapid fluctuations in extracellular brain glucose levels induced by natural arousing stimuli and intravenous cocaine: fueling the brain during neural activation.

    Science.gov (United States)

    Kiyatkin, Eugene A; Lenoir, Magalie

    2012-09-01

    Glucose, a primary energetic substrate for neural activity, is continuously influenced by two opposing forces that tend to either decrease its extracellular levels due to enhanced utilization in neural cells or increase its levels due to entry from peripheral circulation via enhanced cerebral blood flow. How this balance is maintained under physiological conditions and changed during neural activation remains unclear. To clarify this issue, enzyme-based glucose sensors coupled with high-speed amperometry were used in freely moving rats to evaluate fluctuations in extracellular glucose levels induced by brief audio stimulus, tail pinch (TP), social interaction with another rat (SI), and intravenous cocaine (1 mg/kg). Measurements were performed in nucleus accumbens (NAcc) and substantia nigra pars reticulata (SNr), which drastically differ in neuronal activity. In NAcc, where most cells are powerfully excited after salient stimulation, glucose levels rapidly (latency 2-6 s) increased (30-70 μM or 6-14% over baseline) by all stimuli; the increase differed in magnitude and duration for each stimulus. In SNr, where most cells are transiently inhibited by salient stimuli, TP, SI, and cocaine induced a biphasic glucose response, with the initial decrease (-20-40 μM or 5-10% below baseline) followed by a reboundlike increase. The critical role of neuronal activity in mediating the initial glucose response was confirmed by monitoring glucose currents after local microinjections of glutamate (GLU) or procaine (PRO). While intra-NAcc injection of GLU transiently increased glucose levels in this structure, intra-SNr PRO injection resulted in rapid, transient decreases in SNr glucose. Therefore, extracellular glucose levels in the brain change very rapidly after physiological and pharmacological stimulation, the response is structure specific, and the pattern of neuronal activity appears to be a critical factor determining direction and magnitude of physiological

  4. Particle density fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, M.M.; Ahammed, Z.; Angelis, A.L.S.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bucher, D.; Buesching, H.; Carlen, L.; Chattopadhyay, S.; Das, A.C.; Decowski, M.P.; Donni, P.; Dubey, A.K.; Dutta Majumdar, M.R.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M.S.; Garpman, S.; Gavrishcuk, O.; Geurts, F.J.M.; Glasow, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H.H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpio, K.; Kolb, B.W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Loehner, H.; Mahapatra, D.P.; Manko, V.; Martin, M.; Miake, Y.; Mishra, G.C.; Mohanty, B.; Morrison, D.; Mukhopadhayay, D.S.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nishimura, S.; Nomokov, P.; Petracek, V.; Plasil, F.; Purschke, M.L.; Rak, J.; Raniwala, R.; Raniwala, S.; Rao, N.K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Rubio, J.M.; Sambyal, S.S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.-R.; Schutz, Y.; Shabratova, G.; Sibiriak, I.; Siemiarczuk, T.; Sinha, B.C.; Slavine, N.; Soederstroem, K.; Sood, G.; Soerensen, S.P.; Stankus, P.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Trivedi, M.D.; Tsvetkov, A.; Tykarski, L.; Urbahn, J.; Eijinhoven, N. van; Niewenhuizen, G.J. van; Vinogradov, A.; Viyogi, Y.P.; Vodopianov, A.; Voeroes, S.; Wyslouch, B.; Young, G.R

    2003-03-10

    Event-by-event fluctuations in the multiplicities of charged particles and photons at SPS energies are discussed. Fluctuations are studied by controlling the centrality of the reaction and rapidity acceptance of the detectors. Results are also presented on the event-by-event study of correlations between the multiplicity of charged particles and photons to search for DCC-like signals.

  5. Particle density fluctuations

    CERN Document Server

    Mohanty, Bedangadas; Ahammed, Z.; Angelis, A.L.S.; Antonenko, V.; Arefev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bucher, D.; Busching, H.; Carlen, L.; Chattopadhyay, S.; Das, A.C.; Decowski, M.P.; Donni, P.; Dubey, A.K.; Dutta Majumdar, M.R.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M.S.; Garpman, S.; Gavrishchuk, O.; Geurts, F.J.M.; Glasow, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H.H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpio, K.; Kolb, B.W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Lohne, H.; Mahapatra, D.P.; Manko, V.; Martin, M.; Miake, Y.; Mishra, G.C.; Morrison, D.; Mukhopadhyay, D.S.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nishimura, S.; Nomokov, P.; Nystrand, J.; Oskarsson, A.; Otterlund, I.; Phatak, S.C.; Pavliouk, S.; Peitzmann, T.; Petracek, V.; Plasil, F.; Purschke, M.L.; Rak, J.; Raniwala, R.; Raniwala, S.; Rao, N.K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Rubio, J.M.; Sambyal, S.S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.R.; Schutz, Y.; Shabratova, G.; Sibiriak, I.; Siemiarczuk, T.; Sinha, B.C.; Slavine, N.; Soderstrom, K.; Sood, G.; Sorensen, S.P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Trivedi, M.D.; Tsvetkov, A.; Tykarski, L.; Urbahn, J.; van Eijndhoven, N.; van Nieuwenhuizen, G.J.; Vinogradov, A.; Viyogi, Y.P.; Vodopianov, A.S.; Voros, S.; Wyslouch, B.; Young, G.R.; Mohanty, Bedangadas

    2003-01-01

    Event-by-event fluctuations in the multiplicities of charged particles and photons at SPS energies are discussed. Fluctuations are studied by controlling the centrality of the reaction and rapidity acceptance of the detectors. Results are also presented on the event-by-event study of correlations between the multiplicity of charged particles and photons to search for DCC-like signals.

  6. The impact analysis of jacket-space geometric parameters on the characteristics of a reciprocating processor with cooling system using gas pressure fluctuations in the suction line

    Science.gov (United States)

    Shcherba, V. E.; Grigoriev, A. V.; Vedruchenko, V. P.; Galdin, N. S.; Rybak, A. T.; Trukhanova, D. A.

    2017-08-01

    The article analyzes the impact of the jacket-space diameter and length on characteristics of a reciprocating compressor with liquid cooling system using liquid circulation gas pressure fluctuations in the suction line. The following operating characteristics of the machine were constructed and analyzed: the average height of the liquid column in the jacket space; instantaneous velocity and height of the liquid column in the jacket space; the relative height of the liquid column in the jacket space; volumetric efficiency; indicator isothermal efficiency; flowrate in the pump section; relative pressure losses during suction; relative flowrate. The dependence of the instantaneous pressure in the work space and the suction space of the compressor section on the rotation angle of the crankshaft is determined for different values of the external diameter of the jacket space.

  7. Rapid inactivation of Penicillium digitatum spores using high-density nonequilibrium atmospheric pressure plasma

    Science.gov (United States)

    Iseki, Sachiko; Ohta, Takayuki; Aomatsu, Akiyoshi; Ito, Masafumi; Kano, Hiroyuki; Higashijima, Yasuhiro; Hori, Masaru

    2010-04-01

    A promising, environmentally safe method for inactivating fungal spores of Penicillium digitatum, a difficult-to-inactivate food spoilage microorganism, was developed using a high-density nonequilibrium atmospheric pressure plasma (NEAPP). The NEAPP employing Ar gas had a high electron density on the order of 1015 cm-3. The spores were successfully and rapidly inactivated using the NEAPP, with a decimal reduction time in spores (D value) of 1.7 min. The contributions of ozone and UV radiation on the inactivation of the spores were evaluated and concluded to be not dominant, which was fundamentally different from the conventional sterilizations.

  8. Application of the Detrended Fluctuation Analysis method to the trajectory of the centre of pressure of the human body; Aplicacion del metodo Detrended Fluctuation Analysis a la trayectoria del centro de presion del cuerpo humano

    Energy Technology Data Exchange (ETDEWEB)

    Blazquez, M. T.; Anguiano, M.; Arias de Saavedra, F.; Lallena, A. M.; Carpena, P.

    2009-07-01

    The Detrended Fluctuation Analysis is a signal analyzing method which permits to study the correlation properties of the signal analyzed. This algorithm admits different variants which can be used to eliminate trends of different order existing in the signal. In this work we show the results obtained when two of these different variants, the so-called DFA-1 and DFA-2, are applied to the time series of the position and velocity of the centre of pressure of the human body in static conditions. The results show that the correlation exponents {alpha} obtained for each of the four types of analysis performed, depend on the scale studied. For the scales corresponding to large time intervals (above 35 s) the {alpha} values found in the four analyses coincide. (Author) 24 refs.

  9. Optical investigation of BaFe2(As0.77P0.23)2 : Spin-fluctuation-mediated superconductivity under pressure

    Science.gov (United States)

    Uykur, E.; Kobayashi, T.; Hirata, W.; Miyasaka, S.; Tajima, S.; Kuntscher, C. A.

    2017-06-01

    Temperature-dependent reflectivity measurements in the frequency range 75-8000 cm-1 were performed on BaFe2(As0.77P0.23)2 single crystals under pressure up to ˜5 GPa . The obtained optical conductivity spectra have been analyzed to extract the electron-boson spectral density α2F (Ω ) . A sharp resonance peak was observed in α2F (Ω ) upon the superconducting transition, persisting throughout the applied pressure range. The energy and temperature dependences of this peak are consistent with the superconducting gap opening. Furthermore, several similarities with other experimental probes such as inelastic neutron scattering (INS) [D. S. Inosov et al., Nat. Lett. 6, 178 (2010), 10.1038/nphys1483] give evidence for the coupling to a bosonic mode, possibly due to spin fluctuations. Moreover, electronic correlations have been calculated via spectral weight analysis, which revealed that the system stays in the strongly correlated regime throughout the applied pressure range. However, a comparison to the parent compound showed that the electronic correlations are slightly decreased with P doping. The investigation of the phase diagram obtained by our optical study under pressure also revealed the coexistence of the spin-density wave and the superconducting regions, where the coexistence region shifts to the lower pressure range with increasing P content. Moreover, the optimum pressure range, where the highest superconducting transition temperature has been obtained, shows a nonlinear decrease with increasing P content.

  10. Studies of in Situ Pore Pressure Fluctuations At Various Scales Études des fluctuations in situ de la pression de pore à différentes échelles

    Directory of Open Access Journals (Sweden)

    Kümpel H. J.

    2006-12-01

    Full Text Available Pore pressure fluctuations in fluid saturated geological formations, either of natural or anthropogenic origin, can be observed at different scales. Natural fluctuations, e. g. , due to tidal, barometric or seismogenic forcing, or man-made effects as through use of underground fluid reservoirs, or initial filling and cyclic loading of lake reservoirs may have wavelengths from meters to kilometers. In situ monitoring of processes, in which both rock deformation and pore pressure changes are significant, improves our knowledge on the mechanical behaviour and the role of pore pressure in porous rocks and sedimentary layers. Pressure transducers for continuous recording of fluid level variations in wells, reflecting pore pressure changes at depth, or borehole tiltmeters that are sensitive to ground deformation caused by gradients of pore pressure fluctuations are relatively simple means to trace the dynamics of such rock-fluid interactions. The obtained data series are usually interpreted in two ways: by application of analytical solutions-adopting homogeneous poroelastic conditions or single fracture models in a uniform, elastic medium-and by simulation through numerical calculations allowing for some heterogeneity in the model volume. Field cases presented in this article include tilt measurements in the vicinity of pumped wells (1 to 100 m scale, fluid level monitoring in wells (borehole scale, and studies of pore pressure effects induced by seismic events (1 to 100 km scale. Specific rock parameters that can be constrained are the Skempton ratio, the hydraulic diffusivity, and the type of the effective rheology. In cases of tiltmeter studies, anisotropy of pore fluid flow can also be detected. Keywords: fluids in rocks, pore pressure, poroelasticity, hydrology. Les fluctuations de la pression de pore dans les formations géologiques saturées en fluides, d'origine naturelle ou anthropogéniques, peuvent être observées à différentes

  11. Pressure Fluctuations on the Bed of Surge Tank at the H.P. Zimapan, Hgo., with Different Arrangements Studied on Hydraulic Model, with the Lowest Operation Conditions

    Directory of Open Access Journals (Sweden)

    H. Marengo–Mogollón

    2009-10-01

    Full Text Available In this paper, the pressure fluctuations of the surge tank in the Zimapan Hydroelectric Project are compared in a hydraulic model. The shaft is located lateral, over the conduction tunnel and in the simple form (permitting the tunnel entering the shaft, with and without orifice plates taking into account the demand and supply condition of energy with the minimum level of water of the conduction. It was determined the hydraulic efficiency and it was found that it was the best constructive option.

  12. System for Rapid, Precise Modulation of Intraocular Pressure, toward Minimally-Invasive In Vivo Measurement of Intracranial Pressure.

    Directory of Open Access Journals (Sweden)

    Max A Stockslager

    Full Text Available Pathologic changes in intracranial pressure (ICP are commonly observed in a variety of medical conditions, including traumatic brain injury, stroke, brain tumors, and glaucoma. However, current ICP measurement techniques are invasive, requiring a lumbar puncture or surgical insertion of a cannula into the cerebrospinal fluid (CSF-filled ventricles of the brain. A potential alternative approach to ICP measurement leverages the unique anatomy of the central retinal vein, which is exposed to both intraocular pressure (IOP and ICP as it travels inside the eye and through the optic nerve; manipulating IOP while observing changes in the natural pulsations of the central retinal vein could potentially provide an accurate, indirect measure of ICP. As a step toward implementing this technique, we describe the design, fabrication, and characterization of a system that is capable of manipulating IOP in vivo with <0.1 mmHg resolution and settling times less than 2 seconds. In vitro tests were carried out to characterize system performance. Then, as a proof of concept, we used the system to manipulate IOP in tree shrews (Tupaia belangeri while video of the retinal vessels was recorded and the caliber of a selected vein was quantified. Modulating IOP using our system elicited a rapid change in the appearance of the retinal vein of interest: IOP was lowered from 10 to 3 mmHg, and retinal vein caliber sharply increased as IOP decreased from 7 to 5 mmHg. Another important feature of this technology is its capability to measure ocular compliance and outflow facility in vivo, as demonstrated in tree shrews. Collectively, these proof-of-concept demonstrations support the utility of this system to manipulate IOP for a variety of useful applications in ocular biomechanics, and provide a framework for further study of the mechanisms of retinal venous pulsation.

  13. Decreasing pressure ulcer risk during hospital procedures: a rapid process improvement workshop.

    Science.gov (United States)

    Haugen, Vicki; Pechacek, Judy; Maher, Travis; Wilde, Joy; Kula, Larry; Powell, Julie

    2011-01-01

    A 300-bed acute care community hospital used a 2-day "Rapid Process Improvement Workshop" to identify factors contributing to facility-acquired pressure ulcers (PU). The Rapid Process Improvement Workshop included key stakeholders from all procedural areas providing inpatient services and used standard components of rapid process improvement: data analysis, process flow charting, factor identification, and action plan development.On day 1, the discovery process revealed increased PU risk related to prolonged immobility when transporting patients for procedures, during imaging studies, and during the perioperative period. On day 2, action plans were developed that included communication of PU risk or presence of an ulcer,measures to shorten procedure times when clinically appropriate, implementation of prevention techniques during procedures, and recommendations for mattress upgrades. In addition, educational programs about PU prevention were developed, schedules for presentations were established, and an online power point presentation was completed and placed in a learning management system module. Finally, our nursing department amended a hospital wide handoff communication tool to include skin status and PU risk level. This tool is used in all patient handoff situations, including nonnursing departments such as radiology. Patients deemed at risk for ulcers were provided "Braden Risk" armbands to enhance interdepartmental awareness.

  14. Numerical Simulation of the Pressure Distribution in the Reactor Vessel Downcomer Region Fluctuated by the Reactor Coolant Pump

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Dong Hwa; Jung, Byung Ryul; Jang, Ho Cheol; Yune, Seok Jeong; Kim, Eun Kee [KEPCO EnC, Daejeon (Korea, Republic of)

    2015-10-15

    In this study the numerical simulation of the pressure distribution in the downcomer region resulting from the pressure pulsation by the Reactor Coolant Pump (RCP) is performed using the Finite Difference Method (FDM). Simulation is carried out for the cylindrical shaped 2-dimensional model equivalent to the outer surface of the Core Support Barrel (CSB) of APR1400 and a 1/2 model is adopted based on the bilateral symmetry by the inlet nozzle. The fluid temperature is 555 .deg. F and the forcing frequencies are 120Hz, 240Hz, 360Hz and 480Hz. Simulation results of the axial pressure distributions are provided as the Root Mean Square (RMS) values at the five locations of 0°, 45°, 90°, 135° and 180° in the circumferential direction from the inlet nozzle location. In the study, the numerical simulation of pressure distributions in the downcomer region induced by the RCP was performed using FDM and the results were reviewed. The interference of the waves returned from both boundaries in the axial direction and the source of the sinusoidal wave is shown on the inlet nozzle interface pressure point. It seems that the maximum pressures result from the superposition of the waves reflected from the seating surface and the waves newly arrived from the inlet nozzle interface pressure location.

  15. Layers of air in the water beneath the floating fern Salvinia are exposed to fluctuations in pressure.

    Science.gov (United States)

    Mayser, Matthias J; Barthlott, Wilhelm

    2014-12-01

    Superhydrophobic, hierarchically structured, technical surfaces (Lotus-effect) are of high scientific and economic interest because of their remarkable properties. Recently, the immense potential of air-retaining superhydrophobic surfaces, for example, for low-friction transport of fluids and drag-reducing coatings of ships has begun to be explored. A major problem of superhydrophobic surfaces mimicking the Lotus-effect is the limited persistence of the air retained, especially under rough conditions of flow. However, there are a variety of floating or diving plant and animal species that possess air-retaining surfaces optimized for durable water-repellency (Salvinia-effect). Especially floating ferns of the genus Salvinia have evolved superhydrophobic surfaces capable of maintaining layers of air for months. Apart from maintaining stability under water, the layer of air has to withstand the stresses of water pressure (up to 2.5 bars). Both of these aspects have an application to create permanent air layers on ships' hulls. We investigated the effect of pressure on air layers in a pressure cell and exposed the air layer to pressures of up to 6 bars. We investigated the suppression of the air layer at increasing pressures as well as its restoration during decreases in pressure. Three of the four examined Salvinia species are capable of maintaining air layers at pressures relevant to the conditions applying to ships' hulls. High volumes of air per surface area are advantageous for retaining at least a partial Cassie-Baxter-state under pressure, which also helps in restoring the air layer after depressurization. Closed-loop structures such as the baskets at the top of the "egg-beater hairs" (see main text) also help return the air layer to its original level at the tip of the hairs by trapping air bubbles. © The Author 2014. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions

  16. Rapid fluctuations in flow and water-column properties in Asan Bay, Guam: implications for selective resilience of coral reefs in warming seas

    Science.gov (United States)

    Storlazzi, C.D.; Field, M.E.; Cheriton, O.M.; Presto, M.K.; Logan, J.B.

    2013-01-01

    Hydrodynamics and water-column properties were investigated off west-central Guam from July 2007 through January 2008. Rapid fluctuations, on time scales of 10s of min, in currents, temperature, salinity, and acoustic backscatter were observed to occur on sub-diurnal frequencies along more than 2 km of the fore reef but not at the reef crest. During periods characterized by higher sea-surface temperatures (SSTs), weaker wind forcing, smaller ocean surface waves, and greater thermal stratification, rapid decreases in temperature and concurrent rapid increases in salinity and acoustic backscatter coincided with onshore-directed near-bed currents and offshore-directed near-surface currents. During the study, these cool-water events, on average, lasted 2.3 h and decreased the water temperature 0.57 °C, increased the salinity 0.25 PSU, and were two orders of magnitude more prevalent during the summer season than the winter. During the summer season when the average satellite-derived SST anomaly was +0.63 °C, these cooling events, on average, lowered the temperature 1.14 °C along the fore reef but only 0.11 °C along the reef crest. The rapid shifts appear to be the result of internal tidal bores pumping cooler, more saline, higher-backscatter oceanic water from depths >50 m over cross-shore distances of 100 s of m into the warmer, less saline waters at depths of 20 m and shallower. Such internal bores appear to have the potential to buffer shallow coral reefs from predicted increases in SSTs by bringing cool, offshore water to shallow coral environments. These cooling internal bores may also provide additional benefits to offset stress such as supplying food to thermally stressed corals, reducing stress due to ultraviolet radiation and/or low salinity, and delivering coral larvae from deeper reefs not impacted by surface thermal stress. Thus, the presence of internal bores might be an important factor locally in the resilience of select coral reefs facing increased

  17. Rapid intracranial pressure drop as a cause for posterior reversible encephalopathy syndrome: Two case reports.

    Science.gov (United States)

    Niwa, Ryoko; Oya, Soichi; Nakamura, Takumi; Hana, Taijun; Matsui, Toru

    2017-01-01

    Posterior reversible encephalopathy syndrome (PRES) is characterized by reversible edematous lesions on radiological examinations as well as symptoms of altered consciousness and seizures. To date, the underlying mechanism remains largely unknown. Case 1 is a 72-year-old man with a history of hypertension presented with a subarachnoid hemorrhage. Fourteen days after the successful clipping of a ruptured aneurysm; he experienced inadvertent overdrainage via the intraventricular drain. Nine hours later, he started to have seizures followed by disturbances in consciousness. An emergency magnetic resonance imaging showed multiple high-intensity lesions in the frontal, temporal, parietal, and occipital lobes, basal ganglia, brainstem, and cerebellar hemispheres bilaterally, which are compatible with typical magnetic resonance findings in PRES patients. He was treated conservatively and recovered well. Case 2 is a 68-year-old woman with a mild history of hypertension and a ventriculo-peritoneal shunt for obstructive hydrocephalus, who underwent a cysto-peritoneal shunt placement because of an enlarging symptomatic arachnoid cyst. Immediately following surgery, she experienced disturbances in consciousness and developed status epilepticus. Radiological examinations revealed remarkable shrinkage of the arachnoid cyst and multiple edematous lesions, which led us to strongly suspect PRES. With conservative treatment, her symptoms and the radiological abnormalities disappeared. Based on the previous literature and our cases, we believe that the association between rapid reduction of intracranial pressure (ICP) and the development of PRES should be recognized because most neurosurgical procedures such as craniotomy or cerebrospinal fluid diversion present a potential risk of rapid reduction of ICP.

  18. Acute pressure on the sciatic nerve results in rapid inhibition of the wide dynamic range neuronal response

    Directory of Open Access Journals (Sweden)

    Wang Wenxue

    2012-12-01

    Full Text Available Abstract Background Acute pressure on the sciatic nerve has recently been reported to provide rapid short-term relief of pain in patients with various pathologies. Wide dynamic range (WDR neurons transmit nociceptive information from the dorsal horn to higher brain centers. In the present study, we examined the effect of a 2-min application of sciatic nerve pressure on WDR neuronal activity in anesthetized male Sprague–Dawley rats. Results Experiments were carried out on 41 male Sprague–Dawley albino rats weighing 160–280 grams. Dorsal horn WDR neurons were identified on the basis of characteristic responses to mechanical stimuli applied to the cutaneous receptive field. Acute pressure was applied for 2 min to the sciatic nerve using a small vascular clip. The responses of WDR neurons to three mechanical stimuli applied to the cutaneous receptive field were recorded before, and 2, 5 and 20 min after cessation of the 2-min pressure application on the sciatic nerve. Two-min pressure applied to the sciatic nerve caused rapid attenuation of the WDR response to pinching, pressure and brushing stimuli applied to the cutaneous receptive field. Maximal attenuation of the WDR response to pinching and pressure was noted 5 min after release of the 2-min pressure on the sciatic nerve. The mean firing rate decreased from 31.7±1.7 Hz to 13±1.4 Hz upon pinching (p p p Conclusions Our results indicate that acute pressure applied to the sciatic nerve exerts a rapid inhibitory effect on the WDR response to both noxious and innocuous stimuli. Our results may partially explain the rapid analgesic effect of acute sciatic nerve pressure noted in clinical studies, and also suggest a new model for the study of pain.

  19. Turbulent Fluctuations in G-band and K-line Intensities Observed with the Rapid Oscillations in the Solar Atmosphere (ROSA) Instrument

    Science.gov (United States)

    Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.; Jess, D. B.; Mathioudakis, M.

    2012-12-01

    Using the Rapid Oscillation in the Solar Atmosphere (ROSA) instrument at the Dunn Solar Telescope we have found that the spectra of fluctuations of the G-band (cadence 1.05 s) and Ca II K-line (cadence 4.2 s) intensities show correlated fluctuations above white noise out to frequencies beyond 300 mHz and up to 70 mHz, respectively. The noise-corrected G-band spectrum presents a scaling range (Ultra High Frequency “UHF”) for f = 25-100 mHz, with an exponent consistent with the presence of turbulent motions. The UHF power, is concentrated at the locations of magnetic bright points in the intergranular lanes, it is highly intermittent in time and characterized by a positive kurtosis κ. Combining values of G-band and K-line intensities, the UHF power, and κ, reveals two distinct “states” of the internetwork solar atmosphere. State 1, with κ ≍ 6, which includes almost all the data, is characterized by low intensities and low UHF power. State 2, with κ ≍ 3, including a very small fraction of the data, is characterized by high intensities and high UHF power. Superposed epoch analysis shows that for State 1, the K-line intensity presents 3.5 min chromospheric oscillations with maxima occurring 21 s after G-band intensity maxima implying a 150-210 km effective height difference. For State 2, the G-band and K-line intensity maxima are simultaneous, suggesting that in the highly magnetized environment sites of G-band and K-line emission may be spatially close together. Analysis of observations obtained with Hinode/SOT confirm a scaling range in the G-band spectrum up to 53 mHz also consistent with turbulent motions as well as the identification of two distinct states in terms of the H-line intensity and G-band power as functions of G-band intensity.

  20. 8-13 hz fluctuations in rectal pressure are an objective marker of clitorally-induced orgasm in women

    NARCIS (Netherlands)

    van Netten, Jaap J.; Georgiadis, Janniko R.; Nieuwenburg, Arie; Kortekaas, Rudie

    Orgasm is a subjective experience accompanied by involuntary muscle contractions. We hypothesized that orgasm in women would be distinguishable by frequency analysis of a perineal muscle-derived signal. Rectal pressure, an index of perineal muscle activity, was measured continuously in 23 healthy

  1. Thermodynamic and fluid mechanic analysis of rapid pressurization in a dead-end tube

    Science.gov (United States)

    Leslie, Ian H.

    1989-01-01

    Three models have been applied to very rapid compression of oxygen in a dead-ended tube. Pressures as high as 41 MPa (6000 psi) leading to peak temperatures of 1400 K are predicted. These temperatures are well in excess of the autoignition temperature (750 K) of teflon, a frequently used material for lining hoses employed in oxygen service. These findings are in accord with experiments that have resulted in ignition and combustion of the teflon, leading to the combustion of the stainless steel braiding and catastrophic failure. The system analyzed was representative of a capped off-high-pressure oxygen line, which could be part of a larger system. Pressurization of the larger system would lead to compression in the dead-end line, and possible ignition of the teflon liner. The model consists of a large plenum containing oxygen at the desired pressure (500 to 6000 psi). The plenum is connected via a fast acting valve to a stainless steel tube 2 cm inside diameter. Opening times are on the order of 15 ms. Downstream of the valve is an orifice sized to increase filling times to around 100 ms. The total length from the valve to the dead-end is 150 cm. The distance from the valve to the orifice is 95 cm. The models describe the fluid mechanics and thermodynamics of the flow, and do not include any combustion phenomena. A purely thermodynamic model assumes filling to be complete upstream of the orifice before any gas passes through the orifice. This simplification is reasonable based on experiment and computer modeling. Results show that peak temperatures as high as 4800 K can result from recompression of the gas after expanding through the orifice. An approximate transient model without an orifice was developed assuming an isentropic compression process. An analytical solution was obtained. Results indicated that fill times can be considerably shorter than valve opening times. The third model was a finite difference, 1-D transient compressible flow model. Results from

  2. Exploring daily blood pressure fluctuations and cardiovascular risk among individuals with motor complete spinal cord injury: a pilot study.

    Science.gov (United States)

    Dance, Derry L; Chopra, Amit; Campbell, Kent; Ditor, David S; Hassouna, Magdy; Craven, B Catharine

    2017-07-01

    Clinically silent autonomic dysfunction with bowel and bladder care, are postulated to contribute to cardiovascular disease after chronic spinal cord injury (SCI). We describe the frequency and severity of dysreflexic episodes, termed transient blood pressure elevations (T-BPE) over 48 hours in adults with cervical or high-thoracic motor-complete SCI. Tertiary SCI Rehabilitation Centre in Toronto, Canada. Individuals with chronic SCI, C1-T3 AIS A or B, >1 year post-injury, living in the community (n=19). Data were obtained via 48-hour ambulatory blood pressure (BP) and heart rate (HR) monitoring, with data captured at 10-minute intervals and a concurrent diary describing activities of daily living, and bladder/bowel routines. T-BPE were defined as a ≥ 40 mmHg elevation in systolic blood pressure (SBP) above the participant's supine baseline. Severe (≥ 60-79 mmHg) and Extreme ≥80 mmHg elevations in SBP were described. Thirteen participants experienced T-BPE within the assessment period, with 7/13 experiencing "severe", and 3/13 experiencing "extreme" SBP elevations. The median number of T-BPE was 8 (IQR = 3), and the mean ± SD SBP during T-BPE was 150 ± 16 mmHg, These T-BPE were verified as dysreflexic events using a conservative definition of a >40 mmHg increase in SBP, with a concurrent 10 bpm decrease in HR, above the 48-hour average SBP, yielding 12/19 participants with T-BPE. T-BPE were frequent, often with severe or extreme elevations in SBP, despite few reported symptoms. Recognition and management of these dysreflexic events associated with T-BPE are needed, which may ameliorate cardiovascular disease risk.

  3. Experimental investigation of certain internal condensing and boiling flows: Their sensitivity to pressure fluctuations and heat transfer enhancements

    Science.gov (United States)

    Kivisalu, Michael Toomas

    Space-based (satellite, scientific probe, space station, etc.) and millimeter -- to -- micro-scale (such as are used in high power electronics cooling, weapons cooling in aircraft, etc.) condensers and boilers are shear/pressure driven. They are of increasing interest to system engineers for thermal management because flow boilers and flow condensers offer both high fluid flow-rate-specific heat transfer capacity and very low thermal resistance between the fluid and the heat exchange surface, so large amounts of heat may be removed using reasonably-sized devices without the need for excessive temperature differences. However, flow stability issues and degredation of performance of shear/pressure driven condensers and boilers due to non-desireable flow morphology over large portions of their lengths have mostly prevented their use in these applications. This research is part of an ongoing investigation seeking to close the gap between science and engineering by analyzing two key innovations which could help address these problems. First, it is recommended that the condenser and boiler be operated in an innovative flow configuration which provides a non-participating core vapor stream to stabilize the annular flow regime throughout the device length, accomplished in an energy-efficient manner by means of ducted vapor re-circulation. This is demonstrated experimentally.. Second, suitable pulsations applied to the vapor entering the condenser or boiler (from the re-circulating vapor stream) greatly reduce the thermal resistance of the already effective annular flow regime. For experiments reported here, application of pulsations increased time-averaged heat-flux up to 900 % at a location within the flow condenser and up to 200 % at a location within the flow boiler, measured at the heat-exchange surface. Traditional fully condensing flows, reported here for comparison purposes, show similar heat-flux enhancements due to imposed pulsations over a range of frequencies

  4. Pressure applied by the healthcare staff on a cricoids cartilage simulator during Sellick's maneuver in rapid sequence intubation

    NARCIS (Netherlands)

    J.A. Calvache (Jose Andrés); L.C.B. Sandoval (Luz); W.A. Vargas (William Andres)

    2013-01-01

    textabstractBackground: Sellick's maneuver or cricoid pressure is a strategy used to prevent bronchoaspiration during the rapid intubation sequence. Several studies have described that the force required for an adequate maneuver is of 2.5-3.5 kg. The purpose of this paper was to determine the force

  5. Acute pressure on the sciatic nerve results in rapid inhibition of the wide dynamic range neuronal response.

    Science.gov (United States)

    Wang, Wenxue; Tan, Wei; Luo, Danping; Lin, Jianhua; Yu, Yaoqing; Wang, Qun; Zhao, Wangyeng; Wu, Buling; Chen, Jun; He, Jiman

    2012-12-04

    Acute pressure on the sciatic nerve has recently been reported to provide rapid short-term relief of pain in patients with various pathologies. Wide dynamic range (WDR) neurons transmit nociceptive information from the dorsal horn to higher brain centers. In the present study, we examined the effect of a 2-min application of sciatic nerve pressure on WDR neuronal activity in anesthetized male Sprague-Dawley rats. Experiments were carried out on 41 male Sprague-Dawley albino rats weighing 160-280 grams. Dorsal horn WDR neurons were identified on the basis of characteristic responses to mechanical stimuli applied to the cutaneous receptive field. Acute pressure was applied for 2 min to the sciatic nerve using a small vascular clip. The responses of WDR neurons to three mechanical stimuli applied to the cutaneous receptive field were recorded before, and 2, 5 and 20 min after cessation of the 2-min pressure application on the sciatic nerve. Two-min pressure applied to the sciatic nerve caused rapid attenuation of the WDR response to pinching, pressure and brushing stimuli applied to the cutaneous receptive field. Maximal attenuation of the WDR response to pinching and pressure was noted 5 min after release of the 2-min pressure on the sciatic nerve. The mean firing rate decreased from 31.7±1.7 Hz to 13±1.4 Hz upon pinching (p < 0.001), from 31.2±2.3 Hz to 10.9±1.4 Hz (p < 0.001) when pressure was applied, and from 18.9±1.2 Hz to 7.6±1.1 Hz (p < 0.001) upon brushing. Thereafter, the mean firing rates gradually recovered. Our results indicate that acute pressure applied to the sciatic nerve exerts a rapid inhibitory effect on the WDR response to both noxious and innocuous stimuli. Our results may partially explain the rapid analgesic effect of acute sciatic nerve pressure noted in clinical studies, and also suggest a new model for the study of pain.

  6. Deagglomeration and mixing via the rapid expansion of high pressure and supercritical suspensions

    Science.gov (United States)

    To, Daniel

    Nano-materials are the focus of many research activities due to the desirable properties imparted from their small grain size and high interfacial surface area. However, these materials are highly cohesive powders in the dry state and typically form large agglomerates, leading to a diminished surface area or even grain growth, which minimizes the effectiveness of these nanomaterials. This dissertation addresses the issue of mixing nanopowders constituents by deagglomerating them and achieving simultaneous mixing so that even after inevitable reagglomeration, the effectiveness of large interfacial surface area may be preserved. Nano-particle mixtures were prepared using the environmentally benign dry mixing methods of Stirring in Supercritical Fluids and the Rapid Expansion of High Pressure and Supercritical Suspensions (REHPS). Stirring in Supercritical Fluids was capable of producing course scale nano-particle mixtures that were comparable to mixtures produced with more traditional liquid solvents, without the necessity of filtration and caking issues that are typically associated with them. The REHPS process was capable of producing high-quality mixtures on the sub-micron scale, and was made far superior when the nano-powders were first pre-mixed by stirring to decrease inhomogeneity of the feed. It was also shown that in general, conditions that enhanced turbulent shear stress, and thereby deagglomeration, also enhanced mixing, however this effect could be obscured by inhomogeneities introduced by the feed mixtures. Previous authors have suggested that the primary deagglomeration mechanism is the explosive expansion of the carbon dioxide from within the agglomerate as it transitions from a high pressure to an ambient environment. In this study two other deagglomeration mechanisms were proposed, namely intense turbulent shear stress imparted by the fluid in the nozzle and impaction with the Mach disc near the exit of the nozzle. Explosive expansion was observed

  7. Effects of Rapid Vaccine Injection Without Aspiration and Applying Manual Pressure Before Vaccination on Pain and Crying Time in Infants.

    Science.gov (United States)

    Göl, İlknur; Altuğ Özsoy, Süheyla

    2017-04-01

    To compare effects of rapid injection without aspiration and 10-second manual pressure before injection on pain severity and crying time in 4- to 6-month-old infants given the vaccine DTaP/IPV/Hib. This is a randomized double-blind controlled study. The study population included all the infants presenting for DTaP/IPV/Hib to two family health centers between April and August in 2015. The study sample included 128 infants based on confidence interval of 95% and statistical power of 80%. The sample was divided into four groups: manual pressure, rapid injection without aspiration, manual pressure combined with rapid injection without aspiration, and control groups. There were 32 infants in each group. Gender was adjusted in all groups. Stratified and block randomizations were used. Pain severity scores and crying time during and after the injections were significantly lower in the three intervention groups than in the control group (p = .001). The lowest increase in the mean heart rate during and after the injections occurred in the rapid injection without aspiration group (p injections was significantly lower in this group than in the other groups (p injection without aspiration group had low oxygen saturation levels starting before the injections. In fact, mean oxygen saturations did not change across time. This suggests that lower oxygen saturation in the rapid injection without aspiration group cannot be due to vaccines or the techniques used. Manual pressure and rapid injection without aspiration are effective and useful in relief of pain and reduction of crying time due to vaccine injections in 4- to 6-month-old infants. © 2017 Sigma Theta Tau International.

  8. The dynamic pressure response to rapid dilatation of the resting urethra in healthy women

    DEFF Research Database (Denmark)

    Bagi, P; Thind, P; Colstrup, H

    1993-01-01

    The urethral pressure response to a sudden forced dilatation was studied at the bladder neck, in the high-pressure zone and in the distal urethra in ten healthy female volunteers. The pressure response was fitted with a double exponential function of the form Pt = Pequ + P alpha e-t/tau alpha + P...... tissues were computed. The results showed significant differences along the urethra, with the high-pressure zone showing the highest maximum and equilibrium pressures, fastest pressure decay and highest elastic coefficient. The pressure response represents an integrated stress response from...... a detailed assessment of static and dynamic urethral responses to dilatation which can be applied as an experimental simulation of urine ingression, and is therefore presumed to be of value in the evaluation of normal and pathological urethral sphincter function....

  9. Thermally moderated hollow fiber sorbent modules in rapidly cycled pressure swing adsorption mode for hydrogen purification

    KAUST Repository

    Lively, Ryan P.

    2012-10-01

    We describe thermally moderated multi-layered pseudo-monolithic hollow fiber sorbents entities, which can be packed into compact modules to provide small-footprint, efficient H2 purification/CO2 removal systems for use in on-site steam methane reformer product gas separations. Dual-layer hollow fibers are created via dry-jet, wet-quench spinning with an inner "active" core of cellulose acetate (porous binder) and zeolite NaY (69 wt% zeolite NaY) and an external sheath layer of pure cellulose acetate. The co-spun sheath layer reduces the surface porosity of the fiber and was used as a smooth coating surface for a poly(vinyl-alcohol) post-treatment, which reduced the gas permeance through the fiber sorbent by at least 7 orders of magnitude, essentially creating an impermeable sheath layer. The interstitial volume between the individual fibers was filled with a thermally-moderating paraffin wax. CO2 breakthrough experiments on the hollow fiber sorbent modules with and without paraffin wax revealed that the "passively" cooled paraffin wax module had 12.5% longer breakthrough times than the "non-isothermal" module. The latent heat of fusion/melting of the wax offsets the released latent heat of sorption/desorption of the zeolites. One-hundred rapidly cycled pressure swing adsorption cycles were performed on the "passively" cooled hollow fiber sorbents using 25 vol% CO2/75 vol% He (H2 surrogate) at 60 °C and 113 psia, resulting in a product purity of 99.2% and a product recovery of 88.1% thus achieving process conditions and product quality comparable to conventional pellet processes. Isothermal and non-isothermal dynamic modeling of the hollow fiber sorbent module and a traditional packed bed using gPROMS® indicated that the fiber sorbents have sharper fronts (232% sharper) and longer adsorbate breakthrough times (66% longer), further confirming the applicability of the new fiber sorbent approach for H2 purification. © 2012, Hydrogen Energy Publications, LLC

  10. The Rapid Inactivation of Porcine Skin by Applying High Hydrostatic Pressure without Damaging the Extracellular Matrix

    Directory of Open Access Journals (Sweden)

    Naoki Morimoto

    2015-01-01

    Full Text Available We previously reported that high hydrostatic pressure (HHP of 200 MPa for 10 minutes could induce cell killing. In this study, we explored whether HHP at 200 MPa or HHP at lower pressure, in combination with hyposmotic distilled water (DW, could inactivate the skin, as well as cultured cells. We investigated the inactivation of porcine skin samples 4 mm in diameter. They were immersed in either a normal saline solution (NSS or DW, and then were pressurized at 100 and 200 MPa for 5, 10, 30, or 60 min. Next, we explored the inactivation of specimens punched out from the pressurized skin 10 × 2 cm in size. The viability was evaluated using a WST-8 assay and an outgrowth culture. The histology of specimens was analyzed histologically. The mitochondrial activity was inactivated after the pressurization at 200 MPa in both experiments, and no outgrowth was observed after the pressurization at 200 MPa. The arrangement and proportion of the dermal collagen fibers or the elastin fibers were not adversely affected after the pressurization at 200 MPa for up to 60 minutes. This study showed that a HHP at 200 MPa for 10 min could inactivate the skin without damaging the dermal matrix.

  11. The rapid inactivation of porcine skin by applying high hydrostatic pressure without damaging the extracellular matrix.

    Science.gov (United States)

    Morimoto, Naoki; Mahara, Atsushi; Shima, Kouji; Ogawa, Mami; Jinno, Chizuru; Kakudo, Natsuko; Kusumoto, Kenji; Fujisato, Toshia; Suzuki, Shigehiko; Yamaoka, Tetsuji

    2015-01-01

    We previously reported that high hydrostatic pressure (HHP) of 200 MPa for 10 minutes could induce cell killing. In this study, we explored whether HHP at 200 MPa or HHP at lower pressure, in combination with hyposmotic distilled water (DW), could inactivate the skin, as well as cultured cells. We investigated the inactivation of porcine skin samples 4 mm in diameter. They were immersed in either a normal saline solution (NSS) or DW, and then were pressurized at 100 and 200 MPa for 5, 10, 30, or 60 min. Next, we explored the inactivation of specimens punched out from the pressurized skin 10×2 cm in size. The viability was evaluated using a WST-8 assay and an outgrowth culture. The histology of specimens was analyzed histologically. The mitochondrial activity was inactivated after the pressurization at 200 MPa in both experiments, and no outgrowth was observed after the pressurization at 200 MPa. The arrangement and proportion of the dermal collagen fibers or the elastin fibers were not adversely affected after the pressurization at 200 MPa for up to 60 minutes. This study showed that a HHP at 200 MPa for 10 min could inactivate the skin without damaging the dermal matrix.

  12. Use of molecular beacons for the rapid analysis of DNA damage induced by exposure to an atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Kurita, Hirofumi, E-mail: kurita@ens.tut.ac.jp, E-mail: mizuno@ens.tut.ac.jp; Miyachika, Saki; Yasuda, Hachiro; Takashima, Kazunori; Mizuno, Akira, E-mail: kurita@ens.tut.ac.jp, E-mail: mizuno@ens.tut.ac.jp [Department of Environmental and Life Sciences, Toyohashi University of Technology, Aichi 441-8580 (Japan)

    2015-12-28

    A rapid method for evaluating the damage caused to DNA molecules upon exposure to plasma is demonstrated. Here, we propose the use of a molecular beacon for rapid detection of DNA strand breaks induced by atmospheric pressure plasma jet (APPJ) irradiation. Scission of the molecular beacon by APPJ irradiation leads to separation of the fluorophore-quencher pair, resulting in an increase in fluorescence that directly correlates with the DNA strand breaks. The results show that the increase in fluorescence intensity is proportional to the exposure time and the rate of fluorescence increase is proportional to the discharge power. This simple and rapid method allows the estimation of DNA damage induced by exposure to a non-thermal plasma.

  13. The dynamic pressure response to rapid dilatation of the resting urethra in healthy women

    DEFF Research Database (Denmark)

    Bagi, P; Thind, P; Colstrup, H

    1993-01-01

    beta e-t/tau beta, where Pequ, P alpha and P beta are constants, and tau alpha and tau beta are time constants; this equation has previously been demonstrated to describe the pressure decay following dilatation. On the basis of a theoretical model the elastic and viscous constants for the urethral......The urethral pressure response to a sudden forced dilatation was studied at the bladder neck, in the high-pressure zone and in the distal urethra in ten healthy female volunteers. The pressure response was fitted with a double exponential function of the form Pt = Pequ + P alpha e-t/tau alpha + P...... a detailed assessment of static and dynamic urethral responses to dilatation which can be applied as an experimental simulation of urine ingression, and is therefore presumed to be of value in the evaluation of normal and pathological urethral sphincter function....

  14. Possibility for rapid generation of high-pressure phases in single-crystal silicon by fast nanoindentation

    Science.gov (United States)

    Huang, Hu; Yan, Jiwang

    2015-11-01

    High-pressure phases of silicon such as Si-XII/Si-III exhibit attractive optical, electrical and chemical properties, but until now, it has been technologically impossible to produce a significant quantity of Si-XII or Si-III. In this study, to explore the possibility of generating high-pressure silicon phases efficiently, comparative nanoindentation experiments were conducted. Effects of the loading rate, unloading rate and maximum indentation load were investigated, and key factors affecting the high-pressure phase formation were identified. A new nanoindentation protocol is proposed that introduces an intermediate holding stage into the unloading process. The resulting end phases under the indent were detected by a laser micro-Raman spectrometer and compared with those formed in conventional nanoindentation. The results indicate that high-pressure phases Si-XII and Si-III were successfully formed during the intermediate holding stage even with a very high loading/unloading rate. This finding demonstrates the possibility of rapid production of high-pressure phases of silicon through fast mechanical loading and unloading.

  15. Ultra-rapid microwave variable pressure-induced histoprocessing : Description of a new tissue processor

    NARCIS (Netherlands)

    Visinoni, F; Milios, J; Leong, ASY; Boon, ME; Kok, LP; Malcangi, F

    We describe a new method of ultra-rapid histoprocessing that reduces the processing times for needle and endoscopic biopsies to 30 min and that of other surgical biopsy tissue blocks of up to 4 mm thick to 120 min. The MicroMED U R M Histoprocessor, which combines microwave irradiation with precise

  16. Characterization of metal powder based rapid prototyping components under aluminium high pressure die casting process conditions

    CSIR Research Space (South Africa)

    Pereira, MFVT

    2009-11-01

    Full Text Available used in metal high pressure die casting toolsets. The specimens were subjected to a program of cyclic immersion in molten aluminium alloy and cooling in water based die release medium. The heat checking and soldering phenomena were analyzed through...

  17. Rapid Atmospheric-Pressure-Plasma-Jet Processed Porous Materials for Energy Harvesting and Storage Devices

    Directory of Open Access Journals (Sweden)

    Jian-Zhang Chen

    2015-01-01

    Full Text Available Atmospheric pressure plasma jet (APPJ technology is a versatile technology that has been applied in many energy harvesting and storage devices. This feature article provides an overview of the advances in APPJ technology and its application to solar cells and batteries. The ultrafast APPJ sintering of nanoporous oxides and 3D reduced graphene oxide nanosheets with accompanying optical emission spectroscopy analyses are described in detail. The applications of these nanoporous materials to photoanodes and counter electrodes of dye-sensitized solar cells are described. An ultrashort treatment (1 min on graphite felt electrodes of flow batteries also significantly improves the energy efficiency.

  18. Lateral flow assay with pressure meter readout for rapid point-of-care detection of disease-associated protein.

    Science.gov (United States)

    Lin, Bingqian; Guan, Zhichao; Song, Yanling; Song, Eunyeong; Lu, Zifei; Liu, Dan; An, Yuan; Zhu, Zhi; Zhou, Leiji; Yang, Chaoyong

    2018-02-26

    Paper-based assays such as lateral flow assays are good candidates for portable diagnostics owing to their user-friendly format and low cost. In terms of analytical detection, lateral flow assays usually require dedicated instruments to obtain quantitative results. Here we demonstrate a lateral flow assay with handheld pressure meter readout for the rapid detection of disease-related protein with high sensitivity and selectivity. Based on the pressure change produced by the catalytic reaction of Pt nanoparticles related to the concentration of the target, a quantitative reaction platform was established. During the lateral flow assay, the Pt nanoparticles are aggregated in the test line to form a gray band by biomolecular recognition and finally convert the recognition signal into highly sensitive pressure readout for quantitative analysis. Without sophisticated instrumentation and complicated operations, the whole detection process can be completed within 20 minutes. The limit of detection for myoglobin (2.9 ng mL -1 in diluted serum samples) meets the requirements of clinical monitoring. With the advantages of low cost, ease of operation, high sensitivity and selectivity, the method represents a versatile platform for point-of-care testing of disease biomarkers.

  19. Payments for carbon sequestration to alleviate development pressure in a rapidly urbanizing region

    Science.gov (United States)

    Smith, Jordan W.; Dorning, Monica; Shoemaker, Douglas A.; Méley, Andréanne; Dupey, Lauren; Meentemeyer, Ross K.

    2017-01-01

    The purpose of this study was to determine individuals' willingness to enroll in voluntary payments for carbon sequestration programs through the use of a discrete choice experiment delivered to forest owners living in the rapidly urbanizing region surrounding Charlotte, North Carolina. We examined forest owners' willingness to enroll in payments for carbon sequestration policies under different levels of financial incentives (annual revenue), different contract lengths, and different program administrators (e.g., private companies versus a state or federal agency). We also examined the influence forest owners' sense of place had on their willingness to enroll in hypothetical programs. Our results showed a high level of ambivalence toward participating in payments for carbon sequestration programs. However, both financial incentives and contract lengths significantly influenced forest owners' intent to enroll. Neither program administration nor forest owners' sense of place influenced intent to enroll. Although our analyses indicated that payments from carbon sequestration programs are not currently competitive with the monetary returns expected from timber harvest or property sales, certain forest owners might see payments for carbon sequestration programs as a viable option for offsetting increasing tax costs as development encroaches and property values rise.

  20. Fluctuating Selection in the Moran.

    Science.gov (United States)

    Dean, Antony M; Lehman, Clarence; Yi, Xiao

    2017-03-01

    Contrary to classical population genetics theory, experiments demonstrate that fluctuating selection can protect a haploid polymorphism in the absence of frequency dependent effects on fitness. Using forward simulations with the Moran model, we confirm our analytical results showing that a fluctuating selection regime, with a mean selection coefficient of zero, promotes polymorphism. We find that increases in heterozygosity over neutral expectations are especially pronounced when fluctuations are rapid, mutation is weak, the population size is large, and the variance in selection is big. Lowering the frequency of fluctuations makes selection more directional, and so heterozygosity declines. We also show that fluctuating selection raises dn /ds ratios for polymorphism, not only by sweeping selected alleles into the population, but also by purging the neutral variants of selected alleles as they undergo repeated bottlenecks. Our analysis shows that randomly fluctuating selection increases the rate of evolution by increasing the probability of fixation. The impact is especially noticeable when the selection is strong and mutation is weak. Simulations show the increase in the rate of evolution declines as the rate of new mutations entering the population increases, an effect attributable to clonal interference. Intriguingly, fluctuating selection increases the dn /ds ratios for divergence more than for polymorphism, a pattern commonly seen in comparative genomics. Our model, which extends the classical neutral model of molecular evolution by incorporating random fluctuations in selection, accommodates a wide variety of observations, both neutral and selected, with economy. Copyright © 2017 by the Genetics Society of America.

  1. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2018-03-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  2. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2017-12-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  3. Rapid Analysis of Cefazolin in Serum by High-Pressure Liquid Chromatography

    Science.gov (United States)

    Wold, John S.

    1977-01-01

    A high-pressure liquid chromatography (HPLC) method has been developed for the analysis of cefazolin in serum. Serum was deproteinized by the addition of 6% trichloroacetic acid and injected onto a reverse-phase column with a mobile phase of 10 to 15% methanol in 1% aqueous acetic acid. Cefazolin chromatographed without interference from ultraviolet-absorbing components of serum, with a retention time of 3.1 min. Standard curves comparing peak area with concentration prepared from dog or human sera were linear over a range of 1.6 to 200 μg/ml. Results from the HPLC assay were compared with microbiological assays (cylinder plate method) on both standard serum samples and sera from dogs and human subjects receiving intramuscular cefazolin. The HPLC method was somewhat more accurate in comparison with the microbiological assay performed on serum samples of known concentration. The comparison of results from an analysis of serum levels of dogs or human subjects receiving cefazolin indicated that the two methods would lead to identical conclusions concerning pharmacokinetics or the achievement of therapeutic serum levels. The HPLC assay method presents an alternative to conventional microbiological assays, with marked improvement in speed (30 min) and considerable potential for future development. PMID:836007

  4. Genome-wide DNA methylation alterations of Alternanthera philoxeroides in natural and manipulated habitats: implications for epigenetic regulation of rapid responses to environmental fluctuation and phenotypic variation.

    Science.gov (United States)

    Gao, Lexuan; Geng, Yupeng; Li, Bo; Chen, Jiakuan; Yang, Ji

    2010-11-01

    Alternanthera philoxeroides (alligator weed) is an invasive weed that can colonize both aquatic and terrestrial habitats. Individuals growing in different habitats exhibit extensive phenotypic variation but little genetic differentiation in its introduced range. The mechanisms underpinning the wide range of phenotypic variation and rapid adaptation to novel and changing environments remain uncharacterized. In this study, we examined the epigenetic variation and its correlation with phenotypic variation in plants exposed to natural and manipulated environmental variability. Genome-wide methylation profiling using methylation-sensitive amplified fragment length polymorphism (MSAP) revealed considerable DNA methylation polymorphisms within and between natural populations. Plants of different source populations not only underwent significant morphological changes in common garden environments, but also underwent a genome-wide epigenetic reprogramming in response to different treatments. Methylation alterations associated with response to different water availability were detected in 78.2% (169/216) of common garden induced polymorphic sites, demonstrating the environmental sensitivity and flexibility of the epigenetic regulatory system. These data provide evidence of the correlation between epigenetic reprogramming and the reversible phenotypic response of alligator weed to particular environmental factors. © 2010 Blackwell Publishing Ltd.

  5. The impact of rapid sediment accumulation on pore pressure development and dehydration reactions during shallow subduction in the Gulf of Alaska

    Science.gov (United States)

    Meridth, Lanie N.; Screaton, Elizabeth J.; Jaeger, John M.; James, Stephanie R.; Villaseñor, Tania

    2017-01-01

    In the Gulf of Alaska region, sediment has rapidly accumulated (>1 km/my) in the trench sourced from intensified glaciation in the past ˜1.2 million years. This rapid sediment accumulation increases overburden and should accelerate dehydration of hydrous minerals by insulating the underlying sediment column. These processes have the potential to generate fluid overpressures in the low permeability sediments entering the subduction zone. A 1-D model was developed to simulate dehydration reaction progress and investigate excess pore pressures as sediments approach the trench and are subducted. At the deformation front, simulated temperatures increase by ˜30°C due to the insulating effect of trench sediments. As a result, opal-A begins to react to form quartz while smectite remains mostly unreacted. Loading due to the trench sediments elevates excess pore pressures to ˜30% of lithostatic pressure at the deformation front; however, deformation front excess pore pressures are sensitive to assumptions about the permeability of outer wedge sediments. If the outer wedge sediments are coarse-grained and high-permeability rather than mud-dominated, excess pore pressures are lower but still have an insulating effect. During early subduction, simulated pore pressures continue to rise and reach ˜70% of lithostatic by 60 km landward. The 1-D modeling results suggest that the elevated pore pressures are primarily due to loading and that dehydration reactions are not a significant component of excess pore pressure generation at this margin.

  6. Center of Pressure Displacement of Standing Posture during Rapid Movements Is Reorganised Due to Experimental Lower Extremity Muscle Pain.

    Directory of Open Access Journals (Sweden)

    Shinichiro Shiozawa

    Full Text Available Postural control during rapid movements may be impaired due to musculoskeletal pain. The purpose of this study was to investigate the effect of experimental knee-related muscle pain on the center of pressure (CoP displacement in a reaction time task condition.Nine healthy males performed two reaction time tasks (dominant side shoulder flexion and bilateral heel lift before, during, and after experimental pain induced in the dominant side vastus medialis or the tibialis anterior muscles by hypertonic saline injections. The CoP displacement was extracted from the ipsilateral and contralateral side by two force plates and the net CoP displacement was calculated.Compared with non-painful sessions, tibialis anterior muscle pain during the peak and peak-to-peak displacement for the CoP during anticipatory postural adjustments (APAs of the shoulder task reduced the peak-to-peak displacement of the net CoP in the medial-lateral direction (P<0.05. Tibialis anterior and vastus medialis muscle pain during shoulder flexion task reduced the anterior-posterior peak-to-peak displacement in the ipsilateral side (P<0.05.The central nervous system in healthy individuals was sufficiently robust in maintaining the APA characteristics during pain, although the displacement of net and ipsilateral CoP in the medial-lateral and anterior-posterior directions during unilateral fast shoulder movement was altered.

  7. Rapid atmospheric pressure plasma jet processed reduced graphene oxide counter electrodes for dye-sensitized solar cells.

    Science.gov (United States)

    Liu, Hsiao-Wei; Liang, Sheng-Ping; Wu, Ting-Jui; Chang, Haoming; Kao, Peng-Kai; Hsu, Cheng-Che; Chen, Jian-Zhang; Chou, Pi-Tai; Cheng, I-Chun

    2014-09-10

    In this work, we present the use of reduced graphene oxide (rGO) as the counter electrode materials in dye-sensitized solar cells (DSSCs). rGO was first deposited on a fluorine-doped tin oxide glass substrate by screen-printing, followed by post-treatment to remove excessive organic additives. We investigated the effect of atmospheric pressure plasma jet (APPJ) treatment on the DSSC performance. A power conversion efficiency of 5.19% was reached when DSSCs with an rGO counter electrode were treated by APPJs in the ambient air for a few seconds. For comparison, it requires a conventional calcination process at 400 °C for 15 min to obtain comparable efficiency. Scanning electron micrographs show that the APPJ treatment modifies the rGO structure, which may reduce its conductivity in part but simultaneously greatly enhances its catalytic activity. Combined with the rapid removal of organic additives by the highly reactive APPJ, DSSCs with APPJ-treated rGO counter electrode show comparable efficiencies to furnace-calcined rGO counter electrodes with greatly reduced process time. This ultrashort process time renders an estimated energy consumption per unit area of 1.1 kJ/cm(2), which is only one-third of that consumed in a conventional furnace calcination process. This new methodology thus saves energy, cost, and time, which is greatly beneficial to future mass production.

  8. Characterization of initial fluctuations for the hydrodynamical description of heavy ion collisions

    CERN Document Server

    Floerchinger, Stefan

    2013-01-01

    Event-by-event fluctuations in the initial conditions for a hydrodynamical description of heavy-ion collisions are characterized. We propose a Bessel-Fourier decomposition with respect to the azimuthal angle, the radius in the transverse plane and rapidity. This allows for a complete characterization of fluctuations in all hydrodynamical fields including energy density, pressure, fluid velocity, shear stress and bulk viscous pressure. It has the advantage that fluctuations can be ordered with respect to their wave length and that they can be propagated mode-by-mode within the hydrodynamical formalism. Event ensembles can then be characterized in terms of a functional probability distribution. For the event ensemble of a Monte Carlo Glauber model, we provide evidence that the latter is close to Gaussian form, thus allowing for a particularly simple characterization of the event distribution.

  9. Computer simulations of phospholipid - membrane thermodynamic fluctuations

    DEFF Research Database (Denmark)

    Pedersen, U.R.; Peters, Günther H.j.; Schröder, T.B.

    2008-01-01

    This paper reports all-atom computer simulations of five phospholipid membranes, DMPC, DPPC, DMPG, DMPS, and DMPSH, with a focus on the thermal equilibrium fluctuations of volume, energy, area, thickness, and order parameter. For the slow fluctuations at constant temperature and pressure (defined...

  10. A method for predicting full scale buffet response with rigid wind tunnel model fluctuating pressure data. Volume 1: Prediction method development and assessment

    Science.gov (United States)

    Cunningham, A. M., Jr.; Benepe, D. B.; Watts, D.; Waner, P. G.

    1978-01-01

    The method requires unsteady aerodynamic forces, natural airplane modes, and the measured pressure data as input. A gust response computer program is used to calculate buffet response due to the forcing function posed by the measured pressure data. By calculating both symmetric and antisymmetric solutions, upper and lower bounds on full-scale buffet response are formed. Comparisons of predictions with flight test results are made and the effects of horizontal tail loads and static aeroelasticity are shown. Discussions are also presented on the effects of primary wing torsion modes, chordwise and spanwise phase angles, and altitude.

  11. Temperature and pressure dependence of the order parameter fluctuations, conformational compressibility, and the phase diagram of the PEP-PDMS diblock copolymer

    DEFF Research Database (Denmark)

    Schwahn, D.; Frielinghaus, H.; Mortensen, K.

    1996-01-01

    The structure factor of a poly(ethylene-propylene)-poly(dimethylsiloxane) diblock copolymer has been measured by small-angle neutron scattering as a function of temperature and pressure. The conformational compressibility exhibits a pronounced maximum at the order-disorder phase transition...

  12. Rapid and variable-volume sample loading in sieving electrophoresis microchips using negative pressure combined with electrokinetic force.

    Science.gov (United States)

    Qi, Li-Ya; Yin, Xue-Feng; Zhang, Lei; Wang, Min

    2008-07-01

    A rapid and variable-volume sample loading scheme for chip-based sieving electrophoresis was developed by negative pressure combined with electrokinetic force. This was achieved by using a low-cost microvacuum pump and a single potential supply at a constant voltage. Both 12% linear polyacrylamide (LPA) with a high viscosity of 15000 cP and 2% hydroxyethylcellulose (HEC) with a low viscosity of 102 cP were chosen as the sieving materials to study the behavior and the versatility of the proposed method. To reduce the hydrodynamic resistance in the sampling channel, sieving material was only filled in the separation channel between the buffer waste reservoir (BW) to the edge of the crossed intersection. By applying a subambient pressure to the headspace of sample waste reservoir (SW), sample and buffer solution were drawn immediately from sample reservoir (S) and buffer reservoir (B) across the intersection to SW. At the same time, the charged sample in the sample flow was driven across the interface between the sample flow and the sieving matrix into the sieving material filled separation channel by the applied electric field. The injected sample plug length is in proportion with the loading time. Once the vacuum in SW reservoir was released to activate electrophoretic separation, flows from S and B to SW were immediately terminated by the back flow induced by the difference of the liquid levels in the reservoirs to prevent sample leakage during the separation stage. The sample consumption was about 1.7 x 10(2) nL at a loading time of 1 s for each cycle. Only 0.024 s was required to transport bias-free analyte to the injection point. It is easy to freely choose the sample plug volume in this method by simply changing the loading time and to inject high quality sample plug with non-distorted shape into the separation channel. The system has been proved to possess an exciting potential for improving throughput, repeatability, sensitivity and separation performance of

  13. Rapid sample classification using an open port sampling interface coupled with liquid introduction atmospheric pressure ionization mass spectrometry.

    Science.gov (United States)

    Van Berkel, Gary J; Kertesz, Vilmos

    2017-02-15

    An "Open Access"-like mass spectrometric platform to fully utilize the simplicity of the manual open port sampling interface for rapid characterization of unprocessed samples by liquid introduction atmospheric pressure ionization mass spectrometry has been lacking. The in-house developed integrated software with a simple, small and relatively low-cost mass spectrometry system introduced here fills this void. Software was developed to operate the mass spectrometer, to collect and process mass spectrometric data files, to build a database and to classify samples using such a database. These tasks were accomplished via the vendor-provided software libraries. Sample classification based on spectral comparison utilized the spectral contrast angle method. Using the developed software platform near real-time sample classification is exemplified using a series of commercially available blue ink rollerball pens and vegetable oils. In the case of the inks, full scan positive and negative ion ESI mass spectra were both used for database generation and sample classification. For the vegetable oils, full scan positive ion mode APCI mass spectra were recorded. The overall accuracy of the employed spectral contrast angle statistical model was 95.3% and 98% in case of the inks and oils, respectively, using leave-one-out cross-validation. This work illustrates that an open port sampling interface/mass spectrometer combination, with appropriate instrument control and data processing software, is a viable direct liquid extraction sampling and analysis system suitable for the non-expert user and near real-time sample classification via database matching. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.

  14. Thickness fluctuations in turbulent soap films.

    Science.gov (United States)

    Greffier, O; Amarouchene, Y; Kellay, H

    2002-05-13

    Rapidly flowing soap films provide a simple and attractive system to study two-dimensional hydrodynamics and turbulence. By measuring the rapid fluctuations of the thickness of the film in the turbulent regime, we find that the statistics of these fluctuations closely resemble those of a passive scalar field in a turbulent flow. The scalar spectra are well described by Kolmogorov-like scaling while the high-order moments show clear deviations from regular scaling just like dye or temperature fluctuations in 3D turbulent flows.

  15. Leuna methods of rapid emptying and pressure release of operating equipment filled with combustible liquids and gases, as means of prevention of spreading fires

    Energy Technology Data Exchange (ETDEWEB)

    1944-12-14

    At times, the considerable amounts of combustible liquids in the equipment during distillation, gas separation, scrubbing, etc. required special precautionary measures even under normal conditions. Obviously, such amounts of combustibles carried the danger of spreading fires from any disturbance, such as breaks in the piping, of the slides, explosions, and small fires. The past precautions taken in this matter had been fire extinguishers, construction of localizing compartments, spray systems, reduction of the amount of liquids, and other similar measures. However, such measures were of little use in case of an attack. Leuna decided to provide a means of rapid emptying with a simultaneous rapid exhausting of all equipment under danger. Releasing the pressure would prevent the formation of sharp-pointed flames with their devastating consequences. The installation consisted essentially of groups of valves (easily accessible), long pipe lines, storage farms for liquids, and a discharge into the air. Provisions were made for returning the materials under atmospheric pressure to prevent losses. The figures showed rapid emptying of scrubbers for circulating gas under high pressure, gasoline catchpot still, and pressure release of gas separation unit. These installations proved worthy and became a necessary part of operations. Four diagrams are given showing this installation. 4 diagrams

  16. Rapid analysis of formic acid, acetic acid, and furfural in pretreated wheat straw hydrolysates and ethanol in a bioethanol fermentation using atmospheric pressure chemical ionisation mass spectrometry

    Science.gov (United States)

    2011-01-01

    Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) offers advantages as a rapid analytical technique for the quantification of three biomass degradation products (acetic acid, formic acid and furfural) within pretreated wheat straw hydrolysates and the analysis of ethanol during fermentation. The data we obtained using APCI-MS correlated significantly with high-performance liquid chromatography analysis whilst offering the analyst minimal sample preparation and faster sample throughput. PMID:21896164

  17. Quantum Fluctuation Relations

    OpenAIRE

    Facchi, Paolo; Garnero, Giancarlo; Ligabò, Marilena

    2017-01-01

    We present here a set of lecture notes on exact fluctuation relations. We prove the Jarzynski equality and the Crooks fluctuation theorem, two paradigmatic examples of classical fluctuation relations. Finally we consider their quantum versions, and analyze analogies and differences with the classical case.

  18. Rapid Analysis of Apolar Low Molecular Weight Constituents in Wood Using High Pressure Liquid Chromatography with Evaporative Light Scattering Detection

    NARCIS (Netherlands)

    Claassen, F.W.; Haar, van de C.; Beek, van T.A.; Dorado, J.; Martinez-Inigo, M.; Sierra-Alvarez, R.

    2000-01-01

    A new high pressure liquid chromatographic method with evaporative light scattering detection was developed for the qualitative and quantitative analysis of apolar, low molecular weight constituents in wood. The wood extractives were obtained by means of a 6 h Soxhlet extraction with acetone. The

  19. Simultaneous measurements of velocity, temperature, and pressure using rapid CW wavelength-modulation laser-induced fluorescence of OH

    Science.gov (United States)

    Chang, A. Y.; Battles, B. E.; Hanson, R. K.

    1990-01-01

    In high speed flows, laser induced fluorescence (LIF) on Doppler shifted transitions is an attractive technique for velocity measurement. LIF velocimetry was applied to combined single-point measurements of velocity, temperature, and pressure and 2-D imaging of velocity and pressure. Prior to recent research using NO, LIF velocimetry in combustion related flows relied largely on the use of seed molecules. Simultaneous, single-point LIF measurements is reported of velocity, temperature, and pressure using the naturally occurring combustion species OH. This experiment is an extension of earlier research in which a modified ring dye laser was used to make time resolved temperature measurements behind reflected shock waves by using OH absorption an in postflame gases by using OH LIF. A pair of fused-silica rhombs mounted on a single galvanonmeter in an intracavity-doubled Spectra-Physics 380 ring laser permit the UV output to be swept continuously over a few wave numbers at an effective frequency of 3kHz.

  20. Longitudinal fluctuations and decorrelation of anisotropic flow

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Long-Gang [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Qin, Guang-You [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Roy, Victor [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Wang, Xin-Nian [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division MS70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-12-15

    We investigate the decorrelation of 2nd and 3rd order anisotropic flow for charged particles in two different pseudo rapidity (η) windows by varying the pseudo rapidity gap, in an event-by-event (3+1)D ideal hydrodynamic model, with fluctuating initial conditions from A Multi-Phase Transport (AMPT) model. We visualize the parton distribution at initial state for Pb+Pb collisions at LHC and Au+Au collisions at RHIC, and demonstrate the longitudinal fluctuations originating from the asymmetry between forward and backward going participants, the fluctuations of the string length and the fluctuations due to finite number of partons at different beam energies. The decorrelation of anisotropic flow of final hadrons with large η gaps is found to originate from the spatial decorrelation along the longitudinal direction in the AMPT initial conditions through hydrodynamic evolution. The agreement between our results and recent CMS data in most centralities suggests that the string-like mechanism of initial parton production in AMPT model captures the initial longitudinal fluctuation that is responsible for the measured decorrelation of anisotropic flow in Pb+Pb collisions at LHC. Our predictions for Au+Au collisions at the highest RHIC energy show stronger longitudinal decorrelation than at LHC, indicating larger longitudinal fluctuations at lower beam energies.

  1. Study on the interaction between a grid-generated turbulence and a circular cylinder. Influence of the main stream turbulence on the wake-induced velocity field and the pressure fluctuations on the cylinder surface; Koshi ranryu to enchu no kansho ni kansuru kenkyu. Shuru midare no koryu yudo sokudoba to enchu hyomen atsuryokuba eno eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Y.; Sakai, M.; Kushida, T.; Nakamura, I. [Nagoya University, Nagoya (Japan)

    1999-08-25

    The interaction between the grid-generated turbulent flow and a 2-dimensional circular cylinder is investigated experimentally. Particular attention has been devoted to the effect of the main stream turbulence (intensity and scale of the turbulence) on the wake-induced velocity field in the upstream region and the pressure fluctuation on the cylinder surface. The velocity in the upstream region and the pressure on the cylinder surface have been measured simultaneously with the velocity in the near wake, using the I-type hot-wire probes and the pressure transducer. The velocity signals measured in the upstream region and the pressure signals on the cylinder surface are analyzed by the phase average technique on the basis of the reference band-passed velocity signals in the near wake. It is found that in the case that the intensity of main stream turbulence is large and the rate of the scale of turbulence to the cylinder diameter is small, the upstream region where the periodic velocity fluctuations appear becomes large. In this case, the fluctuation of the lift force is also large. (author)

  2. Why ambulatory blood pressure monitoring?

    Science.gov (United States)

    Punzi, H A

    1998-11-15

    Factors that affect the reliability and accuracy of blood pressure measurements are reviewed, and new technologies for measuring blood pressure are discussed. Blood pressure measurements obtained in an office, hospital, or clinic are subject to variation and error. Reasons for variations include the wrong cuff size, improper inflation or deflation technique, and patient apprehension ("white-coat syndrome"). Ambulatory blood pressure monitoring (ABPM) involves the use of a fully automated standard arm cuff that is inflated at predetermined intervals by a small battery-powered pump unit. The most reliable ABPM method is the oscillometric method, which detects subtle changes in air pressure within the cuff system caused by fluctuations of the brachial artery. The process for interpreting 24-hour ABPM data is still evolving. Twenty-four-hour ABPM has been shown to eliminate white-coat hypertension and is also useful for assessing patients whose blood pressure is inappropriately high in the absence of end organ damage, monitoring persons at risk of developing hypertension because of their race or family history, determining a medication's 24-hour effect on blood pressure, and assessing the early-morning rapid rise in blood pressure, which has been linked to an increased risk of nonembolic stroke and myocardial infarction. ABPM enables identification of patients whose blood pressure is elevated in the office but normal at home, allows more appropriate screening of patients for clinical trials, gives reproducible values, and enables evaluation of drug duration and action.

  3. Multicomponent mixed dopant optimization for rapid screening of polycyclic aromatic hydrocarbons using ultra high performance liquid chromatography coupled to atmospheric pressure photoionization high-resolution mass spectrometry

    KAUST Repository

    Sioud, Salim

    2012-05-04

    RATIONALE To enhance the ionization efficiencies in atmospheric pressure photoionization mass spectrometry a dopant with favorable ionization energy such as chlorobenzene is typically used. These dopants are typically toxic and difficult to mix with water-soluble organic solvents. In order to achieve a more efficient and less toxic dopant, a multicomponent mixed dopant was explored. METHODS A multicomponent mixed dopant for non-targeted rapid screening of polycyclic aromatic hydrocarbons (PAHs) was developed and optimized using ultra high performance liquid chromatography (UPLC) coupled to atmospheric pressure photoionization high-resolution mass spectrometry. Various single and multicomponent mixed dopants consisting of ethanol, chlorobenzene, bromobenzene, anisole and toluene were evaluated. RESULTS Fourteen out of eighteen PAHs were successfully separated and detected at low pg/μL levels within 5 min with high mass accuracy ≤4 ppm. The optimal mixed multicomponent dopant consisted of ethanol/chlorobenzene/bromobenzene/anisole (98.975:0.1:0.9:0.025, v/v %) and it improved the limit of detection (LOD) by 2- to 10-fold for the tested PAHs compared to those obtained with pure chlorobenzene. CONCLUSIONS A novel multicomponent dopant that contains 99% ethanol and 1% mixture of chlorobenzene, bromobenzene and anisole was found to be an effective dopant mixture to ionize PAHs. The developed UPLC multicomponent dopant assisted atmospheric pressure photoionization high-resolution mass spectrometry offered a rapid non targeted screening method for detecting the PAHs at low pg/;μL levels within a 5 min run time with high mass accuracy a;circ4 ppm. Copyright © 2012 John Wiley & Sons, Ltd.

  4. Multicomponent mixed dopant optimization for rapid screening of polycyclic aromatic hydrocarbons using ultra high performance liquid chromatography coupled to atmospheric pressure photoionization high-resolution mass spectrometry.

    Science.gov (United States)

    Sioud, Salim; Amad, Ma'an; Al-Talla, Zeyad A

    2012-06-30

    To enhance the ionization efficiencies in atmospheric pressure photoionization mass spectrometry a dopant with favorable ionization energy such as chlorobenzene is typically used. These dopants are typically toxic and difficult to mix with water-soluble organic solvents. In order to achieve a more efficient and less toxic dopant, a multicomponent mixed dopant was explored. A multicomponent mixed dopant for non-targeted rapid screening of polycyclic aromatic hydrocarbons (PAHs) was developed and optimized using ultra high performance liquid chromatography (UPLC) coupled to atmospheric pressure photoionization high-resolution mass spectrometry. Various single and multicomponent mixed dopants consisting of ethanol, chlorobenzene, bromobenzene, anisole and toluene were evaluated. Fourteen out of eighteen PAHs were successfully separated and detected at low pg/μL levels within 5 min with high mass accuracy ≤4 ppm. The optimal mixed multicomponent dopant consisted of ethanol/chlorobenzene/bromobenzene/anisole (98.975:0.1:0.9:0.025, v/v %) and it improved the limit of detection (LOD) by 2- to 10-fold for the tested PAHs compared to those obtained with pure chlorobenzene. A novel multicomponent dopant that contains 99% ethanol and 1% mixture of chlorobenzene, bromobenzene and anisole was found to be an effective dopant mixture to ionize PAHs. The developed UPLC multicomponent dopant assisted atmospheric pressure photoionization high-resolution mass spectrometry offered a rapid non targeted screening method for detecting the PAHs at low pg/μL levels within a 5 min run time with high mass accuracy ≤4 ppm. Copyright © 2012 John Wiley & Sons, Ltd.

  5. Development and validation of a rapid ultra high pressure liquid chromatographic method for the determination of methylxanthines in herbal infusions.

    Science.gov (United States)

    Zacharis, Constantinos K; Kika, Fotini S; Tzanavaras, Paraskevas D; Fytianos, Konstantinos

    2013-05-15

    An ultra high pressure liquid chromatographic method coupled with diode array detector (UHPLC-DAD) has been developed and validated for the fast separation and determination of three major methylxanthines, i.e., caffeine, theophylline and theobromine, in various herbal beverages. Isocratic elution using 0.1vol% formic acid/CH3OH (92.5:7.5, v/v) enabled the completion of the separation cycle in less than 3min using a flow rate of 0.7mL/min and a column temperature of 50°C. Validation of the method included linearity (0.5-50mg/L), limits of detection (12-35μg/L) and quantification (40-120μg/L), precision, matrix effect and accuracy. The percent recoveries ranged between 90 and 108%. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Non-Invasive Method for the Rapid Assessment of Central Venous Pressure: Description and Validation by a Single Examiner

    Directory of Open Access Journals (Sweden)

    Zidulka, Arnold

    2008-11-01

    Full Text Available Objectives: This study describes a means of assessing the external jugular venous pressure (JVP as an indicator of normal or elevated central venous pressure (CVP.Methods: Intensive care unit patients having CVP monitoring were examined. With patients in bed, the external jugular vein (EJV was occluded at the base of the neck and observed to distend. The occlusion was then removed and the vein observed for collapse. Complete collapse was hypothesized to indicate a non-elevated CVP (≤8cm of water. In those patients whose EJV collapsed incompletely, the vein was then occluded with the finger near the angle of the jaw. With the occlusion maintained, the vein was milked downwards with the other hand to cause its emptying and was then observed for filling from below. Filling from below was hypothesized to indicate an elevated CVP (>8cm of water.Results: In 12 of the 40 patients examined, the EJV could not be assessed (EJV not seen at all: 5, and difficult to visualize: 7. For the remaining 28 patients, 11 had a CVP > 8 cm, while 17 had a CVP of < 8. EJV assessment was 100% accurate (95% Confidence Interval 88-100 in predicting whether or not a patient’s CVP was greater or less than 8 cm of water.Conclusion: EJV assessment, when visible, is accurate to clinically assess a patient’s CVP in the hands of the author. Further studies are needed to see if they are reproducible by other observer.[WestJEM. 2008;9:201-205.

  7. Continuous information flow fluctuations

    Science.gov (United States)

    Rosinberg, Martin Luc; Horowitz, Jordan M.

    2016-10-01

    Information plays a pivotal role in the thermodynamics of nonequilibrium processes with feedback. However, much remains to be learned about the nature of information fluctuations in small-scale devices and their relation with fluctuations in other thermodynamics quantities, like heat and work. Here we derive a series of fluctuation theorems for information flow and partial entropy production in a Brownian particle model of feedback cooling and extend them to arbitrary driven diffusion processes. We then analyze the long-time behavior of the feedback-cooling model in detail. Our results provide insights into the structure and origin of large deviations of information and thermodynamic quantities in autonomous Maxwell's demons.

  8. Scaling metabolic rate fluctuations

    OpenAIRE

    Labra, Fabio A.; Marquet, Pablo A.; Bozinovic, Francisco

    2007-01-01

    Complex ecological and economic systems show fluctuations in macroscopic quantities such as exchange rates, size of companies or populations that follow non-Gaussian tent-shaped probability distributions of growth rates with power-law decay, which suggests that fluctuations in complex systems may be governed by universal mechanisms, independent of particular details and idiosyncrasies. We propose here that metabolic rate within individual organisms may be considered as an example of an emerge...

  9. Modeling multiphase flow using fluctuating hydrodynamics.

    Science.gov (United States)

    Chaudhri, Anuj; Bell, John B; Garcia, Alejandro L; Donev, Aleksandar

    2014-09-01

    Fluctuating hydrodynamics provides a model for fluids at mesoscopic scales where thermal fluctuations can have a significant impact on the behavior of the system. Here we investigate a model for fluctuating hydrodynamics of a single-component, multiphase flow in the neighborhood of the critical point. The system is modeled using a compressible flow formulation with a van der Waals equation of state, incorporating a Korteweg stress term to treat interfacial tension. We present a numerical algorithm for modeling this system based on an extension of algorithms developed for fluctuating hydrodynamics for ideal fluids. The scheme is validated by comparison of measured structure factors and capillary wave spectra with equilibrium theory. We also present several nonequilibrium examples to illustrate the capability of the algorithm to model multiphase fluid phenomena in a neighborhood of the critical point. These examples include a study of the impact of fluctuations on the spinodal decomposition following a rapid quench, as well as the piston effect in a cavity with supercooled walls. The conclusion in both cases is that thermal fluctuations affect the size and growth of the domains in off-critical quenches.

  10. In vivo biosynthesis of L-(/sup 35/S)Cys-arginine vasopressin, -oxytocin, and -somatostatin: rapid estimation using reversed phase high pressure liquid chromatography. [Rats

    Energy Technology Data Exchange (ETDEWEB)

    Franco-Bourland, R.E.; Fernstrom, J.D.

    1981-01-01

    L(/sup 35/S)Cys-arginine vasopressin, -oxytocin, and -somatostatin were purified from hypothalami and neurohypophyses 4 h after rats received L(/sup 35/S)Cys via the third ventricle. After acetic acid extraction, Sephadex G-25 filtration, and chemoadsorption to C18-silica (Sep-Pak cartridges), the labeled peptides were rapidly separated by gradient elution, reversed phase, high pressure liquid chromatography (HPLC). The identity and isotopic purity of the labeled peptides were determined by several reversed phase HPLC procedures in conjunction with chemical modification. The labeled peptide fractions were at least 50% radiochemically pure. Using this HPLC isolation procedure, incorporation of L-(/sup 35/S)Cys into each peptide was determined in hydrated and dehydrated rats. Label incorporation into arginine vasopressin and oxytocin in the hypothalamus and the neurohypophysis of dehydrated rats was 2-3 times greater than that in hydrated rats. Incorporation of label into hypothalamic and neurohypophyseal somatostatin was unaffected by the hydration state of the animal. This procedure thus provides a very rapid, but sensitive, set of techniques for studying the control of small peptide biosynthesis in the brain.

  11. Fluctuations in solidification

    Energy Technology Data Exchange (ETDEWEB)

    Karma, A. (Physics Department, Northeastern University, Boston, Massachusetts 02115 (United States))

    1993-11-01

    We present an analytical treatment of (i) the incorporation of thermal noise in the basic continuum models of solidification, (ii) fluctuations about nonequilibrium steady states, and (iii) the amplification of noise near the onset of morphological instability. In (i), we find that the proper Langevin formalism, consistent with both bulk and interfacial equilibrium fluctuations, consists of the usual bulk forces and an extra stochastic force on the interface associated with its local kinetics. At sufficiently large solidification rate, this force affects interfacial fluctuations on scales where they are macroscopically amplified and, thus, becomes relevant. An estimate of this rate is given. In (ii), we extend the Langevin formalism outside of equilibrium to characterize the fluctuations of a stationary and a directionally solidified planar interface in a temperature gradient. Finally, in (iii), we derive an analytic expression for the linear growth of the mean-square amplitude of fluctuations slightly above the onset of morphological instability. The amplitude of the noise is found to be determined by the small parameter [ital k][sub [ital B]T[ital E]d0][sup [ital c]l][sub [ital T

  12. Spin fluctuations and the

    Directory of Open Access Journals (Sweden)

    V.M. Loktev

    2008-09-01

    Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.

  13. Optimization of pressurized liquid extraction (PLE) for rapid determination of mineral oil saturated (MOSH) and aromatic hydrocarbons (MOAH) in cardboard and paper intended for food contact.

    Science.gov (United States)

    Moret, Sabrina; Sander, Maren; Purcaro, Giorgia; Scolaro, Marianna; Barp, Laura; Conte, Lanfranco S

    2013-10-15

    Packaging can represent a primary source of food contamination with mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH), especially when recycled cardboard or mineral oil based printing inks are used. A pressurized liquid extraction (PLE) method, followed by on-line LC-GC analysis, has been optimized for rapid mineral oil determination in cardboard and paper samples. The proposed method involves extraction with hexane (2 cycles) at 60°C for 5 min, and allows for the processing of up to 6 samples in parallel with minimal sample manipulation and solvent consumption. It gave good repeatability (coefficient of variation lower than 5%) and practically quantitative extraction yield (less than 2% of the total contamination found in a third separate cycle). The method was applied to different cardboards and paper materials intended for food contact. Results obtained were similar to those obtained by applying classical solvent extraction with hexane/ethanol 1:1 (v/v) as described by Lorenzini et al. [20]. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Microcanonical quantum fluctuation theorems.

    Science.gov (United States)

    Talkner, Peter; Hänggi, Peter; Morillo, Manuel

    2008-05-01

    Previously derived expressions for the characteristic function of work performed on a quantum system by a classical external force are generalized to arbitrary initial states of the considered system and to Hamiltonians with degenerate spectra. In the particular case of microcanonical initial states, explicit expressions for the characteristic function and the corresponding probability density of work are formulated. Their classical limit as well as their relations to the corresponding canonical expressions are discussed. A fluctuation theorem is derived that expresses the ratio of probabilities of work for a process and its time reversal to the ratio of densities of states of the microcanonical equilibrium systems with corresponding initial and final Hamiltonians. From this Crooks-type fluctuation theorem a relation between entropies of different systems can be derived which does not involve the time-reversed process. This entropy-from-work theorem provides an experimentally accessible way to measure entropies.

  15. Accurate Mass Fragment Library for Rapid Analysis of Pesticides on Produce Using Ambient Pressure Desorption Ionization with High-Resolution Mass Spectrometry

    Science.gov (United States)

    Kern, Sara E.; Lin, Lora A.; Fricke, Frederick L.

    2014-08-01

    U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]+) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]+ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]+ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli. The

  16. Astrocyte Structural and Molecular Response to Elevated Intraocular Pressure Occurs Rapidly and Precedes Axonal Tubulin Rearrangement within the Optic Nerve Head in a Rat Model.

    Directory of Open Access Journals (Sweden)

    Shandiz Tehrani

    Full Text Available Glaucomatous axon injury occurs at the level of the optic nerve head (ONH in response to uncontrolled intraocular pressure (IOP. The temporal response of ONH astrocytes (glial cells responsible for axonal support to elevated IOP remains unknown. Here, we evaluate the response of actin-based astrocyte extensions and integrin-based signaling within the ONH to 8 hours of IOP elevation in a rat model. IOP elevation of 60 mm Hg was achieved under isoflurane anesthesia using anterior chamber cannulation connected to a saline reservoir. ONH astrocytic extension orientation was significantly and regionally rearranged immediately after IOP elevation (inferior ONH, 43.2° ± 13.3° with respect to the anterior-posterior axis versus 84.1° ± 1.3° in controls, p<0.05, and re-orientated back to baseline orientation 1 day post IOP normalization. ONH axonal microtubule filament label intensity was significantly reduced 1 and 3 days post IOP normalization, and returned to control levels on day 5. Phosphorylated focal adhesion kinase (FAK levels steadily decreased after IOP normalization, while levels of phosphorylated paxillin (a downstream target of FAK involved in focal adhesion dynamics were significantly elevated 5 days post IOP normalization. The levels of phosphorylated cortactin (a downstream target of Src kinase involved in actin polymerization were significantly elevated 1 and 3 days post IOP normalization and returned to control levels by day 5. No significant axon degeneration was noted by morphologic assessment up to 5 days post IOP normalization. Actin-based astrocyte structure and signaling within the ONH are significantly altered within hours after IOP elevation and prior to axonal cytoskeletal rearrangement, producing some responses that recover rapidly and others that persist for days despite IOP normalization.

  17. Dynamic photosynthesis under a fluctuating environment: a modelling-based analysis

    NARCIS (Netherlands)

    Morales Sierra, Alejandro

    2017-01-01

    In their natural environment, leaves are exposed to rapid fluctuations of irradiance. Research on CO2 assimilation under fluctuating irradiance often relies on measurements of gas exchange during transients where irradiance is rapidly increased or decreased, after the leaf has adapted to a

  18. Gambling with Superconducting Fluctuations

    Science.gov (United States)

    Foltyn, Marek; Zgirski, Maciej

    2015-08-01

    Josephson junctions and superconducting nanowires, when biased close to superconducting critical current, can switch to a nonzero voltage state by thermal or quantum fluctuations. The process is understood as an escape of a Brownian particle from a metastable state. Since this effect is fully stochastic, we propose to use it for generating random numbers. We present protocol for obtaining random numbers and test the experimentally harvested data for their fidelity. Our work is prerequisite for using the Josephson junction as a tool for stochastic (probabilistic) determination of physical parameters such as magnetic flux, temperature, and current.

  19. Fluctuation relations for anisotropic systems

    Science.gov (United States)

    Villavicencio-Sanchez, R.; Harris, R. J.; Touchette, H.

    2014-02-01

    Currents of particles or energy in driven non-equilibrium steady states are known to satisfy certain symmetries, referred to as fluctuation relations, determining the ratio of the probabilities of positive fluctuations to negative ones. A generalization of these fluctuation relations has been proposed recently for extended non-equilibrium systems of dimension greater than one, assuming, crucially, that they are isotropic (Hurtado P. I., Pérez-Espigares C., del Pozo J. J. and Garrido P. L., Proc. Natl. Acad. Sci. U.S.A., 108 (2011) 7704). Here we relax this assumption and derive a fluctuation relation for d-dimensional systems having anisotropic bulk driving rates. We test the validity of this anisotropic fluctuation relation by calculating the particle current fluctuations in the 2d anisotropic zero-range process, using both exact and fluctuating hydrodynamic approaches.

  20. Noisy fluctuation of heart rate indicates cardiovascular system instability.

    Science.gov (United States)

    Fortrat, Jacques-Olivier; Baum, Charlotte; Jeanguillaume, Christian; Custaud, Marc-Antoine

    2013-09-01

    Heart rate spontaneously fluctuates despite homeostatic regulatory mechanisms to stabilize it. Harmonic and fractal fluctuations have been described. Non-harmonic non-fractal fluctuation has not been studied because it is usually thought that it is caused by apparatus noise. We hypothesized that this fluctuation looking like apparatus noise (that we call "noisy fluctuation") is linked to challenged blood pressure stabilization and not to apparatus noise. We assessed noisy fluctuation by quantifying the small and fastest beat-to-beat fluctuation of RR-interval by means of spectral analysis (Nyquist power of heart rate variability: nyHRV) after filtering out its fractal component. We observed nyHRV in healthy supine subjects and in patients with vasovagal symptoms. We challenged stabilization of blood pressure by upright posture (by means of a head-up tilt table test). Head-up position on the tilt table dramatically decreased nyHRV (0.128 ± 0.063 vs. 0.004 ± 0.002, p cardiovascular system is challenged (upright posture). It also indicates cardiovascular instability because it does not disappear in upright patients before vasovagal syncope, a transient failure of cardiovascular regulation.

  1. Mesoscale wind fluctuations over Danish waters

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, C.L.

    2010-12-15

    mesoscale fluctuations in a mesoscale model is then examined using the weather research and forecasting (WRF) model. A set of case studies demonstrate that realistic hour-scale wind fluctuations and open cellular convection patterns develop in WRF simulations with 2 km horizontal grid spacing. The atmospheric conditions during one of the case studies are then used to initialise a simplified version of the model that has no large scale weather forcing, topography or surface inhomogeneties. Using the simplified model, the sensitivity of the modelled open cellular convection to choices in model setup and to aspects of the environmental forcing are tested. Finally, the cell-scale kinetic energy budget of the modelled cells is calculated, and it is shown that the buoyancy and pressure balance terms are important for cell maintenance. It is explained that the representation of mesoscale convection in a mesoscale model is not only important to end users such as wind farm operators, but to the treatment of energy transport within the boundary layer. (Author)

  2. Adjustment of the basin-scale circulation at 26° N to variations in Gulf Stream, deep western boundary current and Ekman transports as observed by the Rapid array

    Directory of Open Access Journals (Sweden)

    S. A. Cunningham

    2009-10-01

    Full Text Available The Rapid instrument array across the Atlantic Ocean along 26° N provides unprecedented monitoring of the basin-scale circulation. A unique feature of the Rapid array is the combination of full-depth moorings with instruments measuring temperature, salinity, pressure time series at many depths with co-located bottom pressure measurements so that dynamic pressure can be measured from surface to bottom. Bottom pressure measurements show a zonally uniform rise (and fall of bottom pressure of 0.015 dbar on a 5 to 10 day time scale, suggesting that the Atlantic basin is filling and draining on a short time scale. After removing the zonally uniform bottom pressure fluctuations, bottom pressure variations at 4000 m depth against the western boundary compensate instantaneously for baroclinic fluctuations in the strength and structure of the deep western boundary current so there is no basin-scale mass imbalance resulting from variations in the deep western boundary current. After removing the mass compensating bottom pressure, residual bottom pressure fluctuations at the western boundary just east of the Bahamas balance variations in Gulf Stream transport. Again the compensation appears to be especially confined close to the western boundary. Thus, fluctuations in either Gulf Stream or deep western boundary current transports are compensated in a depth independent (barotropic manner very close to the continental slope off the Bahamas. In contrast, compensation for variations in wind-driven surface Ekman transport appears to involve fluctuations in both western basin and eastern basin bottom pressures, though the bottom pressure difference fluctuations appear to be a factor of 3 too large, perhaps due to an inability to resolve small bottom pressure fluctuations after removal of larger zonal average, baroclinic, and Gulf Stream pressure components. For 4 tall moorings where time series dynamic height (geostrophic pressure profiles can be estimated from

  3. Simulation analysis of within-day flow fluctuation effects on trout below flaming Gorge Dam.

    Energy Technology Data Exchange (ETDEWEB)

    Railsback, S. F.; Hayse, J. W.; LaGory, K. E.; Environmental Science Division; EPRI

    2006-01-01

    In addition to being renewable, hydropower has the advantage of allowing rapid load-following, in that the generation rate can easily be varied within a day to match the demand for power. However, the flow fluctuations that result from load-following can be controversial, in part because they may affect downstream fish populations. At Flaming Gorge Dam, located on the Green River in northeastern Utah, concern has been raised about whether flow fluctuations caused by the dam disrupt feeding at a tailwater trout fishery, as fish move in response to flow changes and as the flow changes alter the amount or timing of the invertebrate drift that trout feed on. Western Area Power Administration (Western), which controls power production on submonthly time scales, has made several operational changes to address concerns about flow fluctuation effects on fisheries. These changes include reducing the number of daily flow peaks from two to one and operating within a restricted range of flows. These changes significantly reduce the value of the power produced at Flaming Gorge Dam and put higher load-following pressure on other power plants. Consequently, Western has great interest in understanding what benefits these restrictions provide to the fishery and whether adjusting the restrictions could provide a better tradeoff between power and non-power concerns. Directly evaluating the effects of flow fluctuations on fish populations is unfortunately difficult. Effects are expected to be relatively small, so tightly controlled experiments with large sample sizes and long study durations would be needed to evaluate them. Such experiments would be extremely expensive and would be subject to the confounding effects of uncontrollable variations in factors such as runoff and weather. Computer simulation using individual-based models (IBMs) is an alternative study approach for ecological problems that are not amenable to analysis using field studies alone. An IBM simulates how a

  4. Biomolecules: Fluctuations and relaxations

    Science.gov (United States)

    Parak, F.; Ostermann, A.; Gassmann, A.; Scherk, C.; Chong, S.-H.; Kidera, A.; Go, N.

    1999-10-01

    The normal-mode refinement of X-ray crystallographic data opened a new possibility to analyze the mean-square displacements in a protein molecule. A comparison of the X-ray structure of myoglobin at several temperatures with Mössbauer data is performed. In the low-temperature regime below 180 K the iron mean-square displacements obtained by Mössbauer spectroscopy are in good agreement with a normal-mode analysis. The X-ray mean-square displacements at the position of the iron, after the motion originated from the external degrees of freedom are subtracted, have practically the same temperature dependence as those from Mössbauer spectroscopy. The difference between the X-ray mean-square displacements and those predicted by normal-mode analysis measures the distribution of molecules into conformational substates. Above 180 K the Mössbauer effect indicates fluctuations between conformational substates. The relaxation from a Fe(III) conformation to a Fe(II) conformation is shown for superoxide dismutase of Propionibacterium shermanii.

  5. Fluctuating attention in Parkinson's disease

    DEFF Research Database (Denmark)

    Starrfelt, Randi; Aarsland, Dag; Janvin, Carmen

    2001-01-01

    Lewy body dementia (DLB), which share many clinical and pathological features with Parkinson’s disease (PD), is charac- terised by marked fluctuations in cognition and consciousness. Fluctuating cognition has not been formally studied in PD, although some studies indicate that PD patients show...

  6. Quantum Correction of Fluctuation Theorem

    OpenAIRE

    Monnai, T.; Tasaki, S.

    2003-01-01

    Quantum analogues of the transient fluctuation theorem(TFT) and steady-state fluctuation theorem(SSFT) are investigated for a harmonic oscillator linearly coupled with a harmonic reservoir. The probability distribution for the work done externally is derived and quantum correction for TFT and SSFT are calculated.

  7. Fluctuation conductivity in cuprate superconductors

    Indian Academy of Sciences (India)

    superconducting layers in each unit cell is also not adequate. We suggest the fluctuation conductivity to be reduced due to the reduction in the density of states (DOS) of the quasiparticles which results due to the formation of Cooper pairs at the onset of the fluctuations. The data agrees with the theory proposed by Dorin et al ...

  8. Stress-induced electric current fluctuations in rocks: a superstatistical model

    Science.gov (United States)

    Cartwright-Taylor, Alexis; Vallianatos, Filippos; Sammonds, Peter

    2017-04-01

    equilibrium processes whose variance fluctuates over time. The appearance of q-Gaussian statistics are caused by the fluctuating β parameter, which effectively models the fluctuating energy dissipation rate in the system. This concept is known as superstatistics and is physically relevant for modelling driven non-equilibrium systems where the environmental conditions fluctuate on a large scale. The idea is that the environmental variable, such as temperature or pressure, changes so slowly that a rapidly fluctuating variable within that environment has time to relax back to equilibrium between each change in the environment. The application of superstatistical techniques to our experimental electric current fluctuations show that they can indeed be described, to good approximation, by the superposition of local Gaussian processes with fluctuating variance. We conclude, then, that the measured electric current fluctuates in response to intermittent energy dissipation and is driven to varying temporary local equilibria during deformation by the variations in stress intensity. The advantage of this technique is that, once the model has been established to be a good description of the system in question, the average β parameter (a measure of the average energy dissipation rate) for the system can be obtained simply from the macroscopic q-Gaussian distribution parameters.

  9. Nonmotor Fluctuations in Parkinson's Disease.

    Science.gov (United States)

    Franke, Christiana; Storch, Alexander

    2017-01-01

    The advanced stage of Parkinson's disease (PD) is characterized by motor complications such as motor fluctuations and dyskinesias induced by long-term levodopa treatment. Recent clinical research provides growing evidence that various nonmotor symptoms such as neuropsychiatric, autonomic, and sensory symptoms (particularly pain) also show fluctuations in patients with motor fluctuations (called nonmotor fluctuations or NMF). However, NMF have not yet been adequately considered in routine care of advanced PD patients and only few therapeutic studies are available. Since the pathophysiology of NMF remains largely unknown, innovative therapeutic concepts are largely missing. The close connection of NMF and motor fluctuations, however, strongly suggests that the strategies used to treat motor complications-namely continuous dopaminergic stimulation-also apply for the therapy of NMF. Future controlled clinical trials specifically addressing NMF are urgently warranted. © 2017 Elsevier Inc. All rights reserved.

  10. Staggered Schemes for Fluctuating Hydrodynamics

    CERN Document Server

    Balboa, F; Delgado-Buscalioni, R; Donev, A; Fai, T; Griffith, B; Peskin, C S

    2011-01-01

    We develop numerical schemes for solving the isothermal compressible and incompressible equations of fluctuating hydrodynamics on a grid with staggered momenta. We develop a second-order accurate spatial discretization of the diffusive, advective and stochastic fluxes that satisfies a discrete fluctuation-dissipation balance, and construct temporal discretizations that are at least second-order accurate in time deterministically and in a weak sense. Specifically, the methods reproduce the correct equilibrium covariances of the fluctuating fields to third (compressible) and second (incompressible) order in the time step, as we verify numerically. We apply our techniques to model recent experimental measurements of giant fluctuations in diffusively mixing fluids in a micro-gravity environment [A. Vailati et. al., Nature Communications 2:290, 2011]. Numerical results for the static spectrum of non-equilibrium concentration fluctuations are in excellent agreement between the compressible and incompressible simula...

  11. Fluctuations in catalytic surface reactions

    CERN Document Server

    Imbihl, R

    2003-01-01

    The internal reaction-induced fluctuations which occur in catalytic CO oxidation on a Pt field emitter tip have been studied using field electron microscopy (FEM) as a spatially resolving method. The structurally heterogeneous Pt tip consists of facets of different orientations with nanoscale dimensions. The FEM resolution of roughly 2 nm corresponds to a few hundred reacting adsorbed particles whose variations in the density are imaged as brightness fluctuations. In the bistable range of the reaction one finds fluctuation-induced transitions between the two stable branches of the reaction kinetics. The fluctuations exhibit a behaviour similar to that of an equilibrium phase transition, i.e. the amplitude diverges upon approaching the bifurcation point terminating the bistable range of the reaction. Simulations with a hybrid Monte Carlo/mean-field model reproduce the experimental observations. Fluctuations on different facets are typically uncorrelated but within a single facet a high degree of spatial cohere...

  12. A proposal on Correction of the Data obtained by Pressure Transducer Fitted on Vibratory Flat Plate in Water

    OpenAIRE

    黒部, 雄三; 吉田, 三雄; Yuzo, KUROBE; Mitsuo, YOSHIDA; 運輸省船舶技術研究所推進性能部

    1985-01-01

    The pressure fluctuations induced by marine propellers are usually measured by means of pressure transducers fitted on hull plate or the local plate of ocean structure. In such a case the pressure transducers are oscillated with the plate, so the measured pressure fluctuations would be shifted from the real pressure fluctuations. If these vibrations are excessive, the effect of vibrations on the measured pressure fluctuations should be corrected. In this paper, as one of the simple cases the ...

  13. Rapidity Density Fluctuations in Hadron-Nucleus Interactions: Spikes, Intermittency, and Fractal Properties of Multiple Production in Ag, Au, and Mg Targets with p, $\\bar{p}$, and π- Projectiles at 100 and 320 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Mattingly, Margarita Claudia Krieghoff [Univ. of Notre Dame, IN (United States)

    1991-01-01

    The space-time development of hadron-nucleus interactions is examined using bubble chamber and downstream particle identifier data from the hybrid spectrometer of Fermilab experiment E597. 5583 events representing 12 interactions are studied with conventional and fractal techniques. Comparisons are made to simulated events from the Lund Monte Carlo FRITIOF 1.6. Multiplicities are studied conventionally. Negative binomial descriptions of produced particle multiplicities are interpreted in terms of clusters and cascading and in terms of partial stimulated emission; forwardbackward correlations, in terms of short- and long-range correlations and multiple scattering. Multiplicities are consistent with a multiple collision view of multiparticle production mechanisms and are investigated in terms of the number of collisions v. Rapidity density fluctuations are studied fractally. The possibility of new dynamics is considered on the basis of event-by-event studies of spike phenomena, intermittency, and fractal dimensions. Results from these exploratory studies are consistent with predictions made for quark-gluon plasma transitions. 131 spike events are analyzed; intermittency is investigated with normalized factorial moments and cumulants; and fractal dimensions and correlations dimensions are calculated. ··Seagull effects and production region sizes from Bose-Einstein pion interferometry are also considered.

  14. Effects of phase transition induced density fluctuations on pulsar dynamics

    Directory of Open Access Journals (Sweden)

    Partha Bagchi

    2015-07-01

    Full Text Available We show that density fluctuations during phase transitions in pulsar cores may have non-trivial effects on pulsar timings, and may also possibly account for glitches and anti-glitches. These density fluctuations invariably lead to non-zero off-diagonal components of the moment of inertia, leading to transient wobbling of star. Thus, accurate measurements of pulsar timing and intensity modulations (from wobbling may be used to identify the specific pattern of density fluctuations, hence the particular phase transition, occurring inside the pulsar core. Changes in quadrupole moment from rapidly evolving density fluctuations during the transition, with very short time scales, may provide a new source for gravitational waves.

  15. Fluctuations of Bacteria-laden Microbeads in a Liquid

    Science.gov (United States)

    Kara, Vural; Lissandrello, Charles; O'Connor, Joan; Romero Rodriguez, Jose Alberto; Li, Le; Ekinci, Kamil

    2015-11-01

    The motion of bacteria adhered on surfaces may lead to powerful approaches for novel diagnostic tests. Examples were recently shown using microcantilevers on which bacteria were adhered using surface chemistry. In these experiments, the presence of bacteria led to an increase in the fluctuations of the microcantilevers in the frequency range 1-100 Hz. After administering antibiotics, the fluctuations returned to their control value. Here, we build on these studies by monitoring the fluctuations of micro-beads with bacteria adhered on their surfaces. We coat the micro-beads with Poly D Lysine (PDL) in order to attach Escherichia coli. We measure the fluctuations of the beads in motility buffer media using an optical microscope with and without bacteria. We calculate the diffusion coefficients from the mean square displacements (MSD) and correlate these with the presence of bacteria on the beads. These studies lay the foundation for the development of a rapid antibiotic susceptibility test based on bacterial activity.

  16. Rapidity dependence of multiplicity fluctuations and correlations in ...

    Indian Academy of Sciences (India)

    2011-08-02

    nucleus and hadron–nucleus interactions at accelerator energies. They have been interpreted in terms of several models: as a possible indication of hadronic phase transition, as Cherenkov radi- ation or simply originating from ...

  17. Single-shot fluctuations in waveguided high-harmonic generation.

    Science.gov (United States)

    Goh, S J; Tao, Y; van der Slot, P J M; Bastiaens, H J M; Herek, J; Biedron, S G; Danailov, M B; Milton, S V; Boller, K-J

    2015-09-21

    For exploring the application potential of coherent soft x-ray (SXR) and extreme ultraviolet radiation (XUV) provided by high-harmonic generation, it is important to characterize the central output parameters. Of specific importance are pulse-to-pulse (shot-to-shot) fluctuations of the high-harmonic output energy, fluctuations of the direction of the emission (pointing instabilities), and fluctuations of the beam divergence and shape that reduce the spatial coherence. We present the first single-shot measurements of waveguided high-harmonic generation in a waveguided (capillary-based) geometry. Using a capillary waveguide filled with Argon gas as the nonlinear medium, we provide the first characterization of shot-to-shot fluctuations of the pulse energy, of the divergence and of the beam pointing. We record the strength of these fluctuations vs. two basic input parameters, which are the drive laser pulse energy and the gas pressure in the capillary waveguide. In correlation measurements between single-shot drive laser beam profiles and single-shot high-harmonic beam profiles we prove the absence of drive laser beam-pointing-induced fluctuations in the high-harmonic output. We attribute the main source of high-harmonic fluctuations to ionization-induced nonlinear mode mixing during propagation of the drive laser pulse inside the capillary waveguide.

  18. Quantum fluctuations from thermal fluctuations in Jacobson formalism

    Energy Technology Data Exchange (ETDEWEB)

    Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Ashour, Amani; Alcheikh, Mohammad [Damascus University, Mathematics Department, Faculty of Science, Damascus (Syrian Arab Republic); Alasfar, Lina [Universite Clermont Auvergne, Laboratoire de Physique Corpusculaire de Clermont-Ferrand, Aubiere (France); Alsaleh, Salwa; Mahroussah, Ahmed [King Saud University, Department of Physics and Astronomy, Riyadh (Saudi Arabia)

    2017-09-15

    In the Jacobson formalism general relativity is obtained from thermodynamics. This is done by using the Bekenstein-Hawking entropy-area relation. However, as a black hole gets smaller, its temperature will increase. This will cause the thermal fluctuations to also increase, and these will in turn correct the Bekenstein-Hawking entropy-area relation. Furthermore, with the reduction in the size of the black hole, quantum effects will also start to dominate. Just as the general relativity can be obtained from thermodynamics in the Jacobson formalism, we propose that the quantum fluctuations to the geometry can be obtained from thermal fluctuations. (orig.)

  19. Photoprotection of photosystems in fluctuating light intensities.

    Science.gov (United States)

    Allahverdiyeva, Yagut; Suorsa, Marjaana; Tikkanen, Mikko; Aro, Eva-Mari

    2015-05-01

    Oxygenic photosynthetic organisms experience strong fluctuations in light intensity in their natural terrestrial and aquatic growth environments. Recent studies with both plants and cyanobacteria have revealed that Photosystem (PS) I is the potential target of damage upon abrupt changes in light intensity. Photosynthetic organisms have, however, developed powerful mechanisms in order to protect their photosynthetic apparatus against such potentially hazardous light conditions. Although the electron transfer chain has remained relatively unchanged in both plant chloroplasts and their cyanobacterial ancestors, the photoprotective and regulatory mechanisms of photosynthetic light reactions have experienced conspicuous evolutionary changes. In cyanobacteria, the specific flavodiiron proteins (Flv1 and Flv3) are responsible for safeguarding PSI under rapidly fluctuating light intensities, whilst the thylakoid located terminal oxidases are involved in the protection of PSII during 12h diurnal cycles involving abrupt, square-wave, changes from dark to high light. Higher plants such as Arabidopsis thaliana have evolved different protective mechanisms. In particular, the PGR5 protein controls electron flow during sudden changes in light intensity by allowing the regulation mostly via the Cytochrome b6f complex. Besides the function of PGR5, plants have also acquired other dynamic regulatory mechanisms, among them the STN7-related LHCII protein phosphorylation that is similarly responsible for protection against rapid changes in the light environment. The green alga Chlamydomonas reinhardtii, as an evolutionary intermediate between cyanobacteria and higher plants, probably possesses both protective mechanisms. In this review, evolutionarily different photoprotective mechanisms under fluctuating light conditions are described and their contributions to cyanobacterial and plant photosynthesis are discussed. © The Author 2014. Published by Oxford University Press on behalf of

  20. Skewness of elliptic flow fluctuations

    Science.gov (United States)

    Giacalone, Giuliano; Yan, Li; Noronha-Hostler, Jacquelyn; Ollitrault, Jean-Yves

    2017-01-01

    Using event-by-event hydrodynamic calculations, we find that the fluctuations of the elliptic flow (v2) in the reaction plane have a negative skew. We compare the skewness of v2 fluctuations to that of initial eccentricity fluctuations. We show that skewness is the main effect lifting the degeneracy between higher-order cumulants, with negative skew corresponding to the hierarchy v2{4 } >v2{6 } observed in Pb+Pb collisions at the CERN Large Hadron Collider. We describe how the skewness can be measured experimentally and show that hydrodynamics naturally reproduces its magnitude and centrality dependence.

  1. Fluctuation theorem: A critical review

    Science.gov (United States)

    Malek Mansour, M.; Baras, F.

    2017-10-01

    Fluctuation theorem for entropy production is revisited in the framework of stochastic processes. The applicability of the fluctuation theorem to physico-chemical systems and the resulting stochastic thermodynamics were analyzed. Some unexpected limitations are highlighted in the context of jump Markov processes. We have shown that these limitations handicap the ability of the resulting stochastic thermodynamics to correctly describe the state of non-equilibrium systems in terms of the thermodynamic properties of individual processes therein. Finally, we considered the case of diffusion processes and proved that the fluctuation theorem for entropy production becomes irrelevant at the stationary state in the case of one variable systems.

  2. Density fluctuations in traffic flow

    CERN Document Server

    Yukawa, S

    1996-01-01

    Density fluctuations in traffic current are studied by computer simulations using the deterministic coupled map lattice model on a closed single-lane circuit. By calculating a power spectral density of temporal density fluctuations at a local section, we find a power-law behavior, \\sim 1/f^{1.8}, on the frequency f, in non-congested flow phase. The distribution of the headway distance h also shows the power law like \\sim 1/h^{3.0} at the same time. The power law fluctuations are destroyed by the occurence of the traffic jam.

  3. Study on the Effect of Inlet Fluctuation on Cavitation in a Cone Flow Channel.

    Science.gov (United States)

    Hai, Liu; Shuping, Cao; Xiaohui, Luo

    2015-05-01

    A mathematical method was conducted to investigate the mechanism of formation of cavitation cloud, while the inlet stream contains a fluctuating flow. Based on the Rayleigh-Plesset equation and the static pressure distribution in a cone flow channel, parameters related to cavitation cloud are estimated, and the collapse pressure of the cavitation cloud is obtained by solving the equation of Mørch's model. Moreover, the effect of the amplitude and frequency of inlet fluctuation on cavitation is studied. Results revealed that the smaller the amplitude, the smaller the cloud and the lower the collapse pressure. And frequency of fluctuating stream was found to have a relative great effect on frequency of peak pressure but not so significant on peak collapse pressure and size of cloud. It is concluded that limiting the inlet fluctuation reduces the erosion and noise generated by cavitation collapse.

  4. Estimation of Several Turbulent Fluctuation Quantities Using an Approximate Pulsatile Flow Model

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    Turbulent fluctuation behavior is approximately modeled using a pulsatile flow model analogy.. This model follows as an extension to the turbulent laminar sublayer model developed by Sternberg (1962) to be valid for a fully turbulent flow domain. Here unsteady turbulent behavior is modeled via a sinusoidal pulsatile approach. While the individual modes of the turbulent flow fluctuation behavior are rather crudely modeled, approximate temporal integration yields plausible estimates for Root Mean Square (RMS) velocity fluctuations. RMS pressure fluctuations and spectra are of particular interest and are estimated via the pressure Poisson expression. Both RMS and Power Spectral Density (PSD), i.e. spectra are developed. Comparison with available measurements suggests reasonable agreement. An additional fluctuating quantity, i.e. RMS wall shear fluctuation is also estimated, yielding reasonable agreement with measurement.

  5. Fluctuations and Instability in Sedimentation

    KAUST Repository

    Guazzelli, Élisabeth

    2011-01-21

    This review concentrates on the fluctuations of the velocities of sedimenting spheres, and on the structural instability of a suspension of settling fibers. For many years, theoretical estimates and numerical simulations predicted the fluctuations of the velocities of spheres to increase with the size of the container, whereas experiments found no such variation. Two ideas have increased our understanding. First, the correlation length of the velocity fluctuations was found experimentally to be 20 interparticle separations. Second, in dilute suspensions, a vertical variation in the concentration due to the spreading of the front with the clear fluid can inhibit the velocity fluctuations. In a very dilute regime, a homogeneous suspension of fibers suffers a spontaneous instability in which fast descending fiber-rich columns are separated by rising fiber-sparse columns. In a semidilute regime, the settling is hindered, more so than for spheres. © 2011 by Annual Reviews. All rights reserved.

  6. Molecular evolution under fitness fluctuations.

    Science.gov (United States)

    Mustonen, Ville; Lässig, Michael

    2008-03-14

    Molecular evolution is a stochastic process governed by fitness, mutations, and reproductive fluctuations in a population. Here, we study evolution where fitness itself is stochastic, with random switches in the direction of selection at individual genomic loci. As the correlation time of these fluctuations becomes larger than the diffusion time of mutations within the population, fitness changes from an annealed to a quenched random variable. We show that the rate of evolution has its maximum in the crossover regime, where both time scales are comparable. Adaptive evolution emerges in the quenched fitness regime (evidence for such fitness fluctuations has recently been found in genomic data). The joint statistical theory of reproductive and fitness fluctuations establishes a conceptual connection between evolutionary genetics and statistical physics of disordered systems.

  7. Gaussian fluctuations in chaotic eigenstates

    CERN Document Server

    Srednicki, M A; Srednicki, Mark; Stiernelof, Frank

    1996-01-01

    We study the fluctuations that are predicted in the autocorrelation function of an energy eigenstate of a chaotic, two-dimensional billiard by the conjecture (due to Berry) that the eigenfunction is a gaussian random variable. We find an explicit formula for the root-mean-square amplitude of the expected fluctuations in the autocorrelation function. These fluctuations turn out to be O(\\hbar^{1/2}) in the small \\hbar (high energy) limit. For comparison, any corrections due to scars from isolated periodic orbits would also be O(\\hbar^{1/2}). The fluctuations take on a particularly simple form if the autocorrelation function is averaged over the direction of the separation vector. We compare our various predictions with recent numerical computations of Li and Robnik for the Robnik billiard, and find good agreement. We indicate how our results generalize to higher dimensions.

  8. Quantum entanglement and temperature fluctuations.

    Science.gov (United States)

    Ourabah, Kamel; Tribeche, Mouloud

    2017-04-01

    In this paper, we consider entanglement in a system out of equilibrium, adopting the viewpoint given by the formalism of superstatistics. Such an approach yields a good effective description for a system in a slowly fluctuating environment within a weak interaction between the system and the environment. For this purpose, we introduce an alternative version of the formalism within a quantum mechanical picture and use it to study entanglement in the Heisenberg XY model, subject to temperature fluctuations. We consider both isotropic and anisotropic cases and explore the effect of different temperature fluctuations (χ^{2}, log-normal, and F distributions). Our results suggest that particular fluctuations may enhance entanglement and prevent it from vanishing at higher temperatures than those predicted for the same system at thermal equilibrium.

  9. Neutral fragment filtering for rapid identification of new diester-diterpenoid alkaloids in roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with linear ion trap-orbitrap mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    Full Text Available A rapid and effective method was developed for separation and identification of diester-diterpenoid alkaloids (DDA in the roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with high resolution LTQ-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS(n. According to accurate mass measurement and the characteristic neutral loss filtering strategy, a total of 42 diester-diterpenoid alkaloids (DDA were rapidly detected and characterized or tentatively identified. Meanwhile, the proposed fragmentation pathways and the major diagnostic fragment ions of aconitine, mesaconitine and hypaconitine were investigated to trace DDA derivatives in crude plant extracts. 23 potential new compounds were successfully screened and characterized in Aconitum carmichaeli, including 16 short chain fatty acyls DDA, 4 N-dealkyl DDA and several isomers of aconitine, mesaconitine and hypaconitine.

  10. Creep- and fatigue-resistant, rapid piezoresistive responses of elastomeric graphene-coated carbon nanotube aerogels over a wide pressure range.

    Science.gov (United States)

    Tsui, Michelle N; Islam, Mohammad F

    2017-01-19

    Lightweight, flexible piezoresistive materials with wide operational pressure ranges are in demand for applications such as human physical activity and health monitoring, robotics, and for functional interfacing between living systems and wearable electronics. Piezoresistivity of many elastomeric foams of polymers and carbon allotropes satisfies much of the required characteristics for these applications except creep and fatigue resistance due to their viscoelasticity, critically limiting the reliability and lifetime of integrated devices. We report the piezoresistive responses from aerogels of graphene-coated single-walled carbon nanotubes (SWCNTs), made using a facile and versatile sol-gel method. Graphene crosslinks the junctions of the underlying random network of SWCNTs, generating lightweight elastomeric aerogels with a mass density of ≈11 mg mL-1 (volume fraction ≈7.7 × 10-3) and a Young's modulus of ≈0.4 MPa. The piezoresistivity of these aerogels spans wide compressive pressures up to at least 120 kPa with sensitivity that exhibit ultrafast temporal responses of <27 ms and <3% delay ratio over 104 compressive loading-unloading cycles at rates between 0.1-10 Hz. Most importantly, the piezoresistive responses do not show any creep at least for 1 hour and 80 kPa of compressive static loading. We suggest that the fatigue- and creep-resistant, ultrafast piezoresistive responses of these elastomeric aerogels are highly attractive for use in dynamic and static lightweight, pressure sensing applications such as human activity monitoring and soft robotics.

  11. Relations between a novel, reliable, and rapid index of arterial compliance (PP-HDI) and well-established inidices of arterial blood pressure (ABP) in a sample of hypertensive elderly subjects.

    Science.gov (United States)

    Bergamini, L; Finelli, M E; Bendini, C; Ferrari, E; Veschi, M; Neviani, F; Manni, B; Pelosi, A; Rioli, G; Neri, M

    2009-01-01

    Hypertension is a risk factor for a long-lasting arterial wall-remodelling leading to stiffness. The rapid method measuring the pulse pressure (PP) by means of the tool of Hypertension Diagnostic Instruments (HDI) called PP-HDI, overcomes some of the problems arising with more-time consuming methods, like ambulatory blood pressure monitoring (ABPM), and give information about the elasticity of the arterial walls. We studied the relationship between the PP-HDI, the large artery compliance (LA-C) and small artery compliance (SA-C) and few well-established indices of arterial blood pressure (ABP) in a sample of 75 hypertensive subjects, aged 65 years and over. Significant correlations between LA-C and heart rate (HR), PP-ABPM and PP-HDI were found. SA-C relates with HR and systolic blood pressure (SBP) measured in lying and standing positions. Applying a stepwise regression analysis, we found that LA-C variance stems from PP-HDI and HR, while SA-C variance stems from SBP in lying position. Receiver operator characteristic (ROC) curves for thresholds of PP showed that PP-HDI reached levels of sensitivity/specificity similar to PP-ABPM. In conclusion, surveillance of ABP through hemo-dynamic indices, in particular of SBP, is essential, nevertheless the advantage of this control is not known in an elderly population where the organ damage is already evident. PP needs necessarily an instrumental measurement. The PP-HDI result is similar in reliability with respect to PPABPM, but is more rapid and well applicable in an elderly population.

  12. Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry.

    Science.gov (United States)

    Ehlert, S; Hölzer, J; Rittgen, J; Pütz, M; Schulte-Ladbeck, R; Zimmermann, R

    2013-09-01

    Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully.

  13. Quasispecies evolution on a fitness landscape with a fluctuating peak

    OpenAIRE

    Nilsson, Martin; Snoad, Nigel

    2000-01-01

    A quasispecies evolving on a fitness landscape with a single peak of fluctuating height is studied. In the approximation that back mutations can be ignored, the rate equations can be solved analytically. It is shown that the error threshold on this class of dynamic landscapes is defined by the time average of the selection pressure. In the case of a periodically fluctuating fitness peak we also study the phase-shift and response amplitude of the previously documented low-pass filter effect. T...

  14. Vacuum fluctuations of the supersymmetric field in curved background

    Energy Technology Data Exchange (ETDEWEB)

    Bilic, Neven, E-mail: bilic@thphys.irb.hr [Rudjer Boskovic Institute, POB 180, HR-10002 Zagreb (Croatia); Domazet, Silvije, E-mail: sdomazet@irb.hr [Rudjer Boskovic Institute, POB 180, HR-10002 Zagreb (Croatia); Guberina, Branko, E-mail: guberina@thphys.irb.hr [Rudjer Boskovic Institute, POB 180, HR-10002 Zagreb (Croatia)

    2012-01-16

    We study a supersymmetric model in curved background spacetime. We calculate the effective action and the vacuum expectation value of the energy momentum tensor using a covariant regularization procedure. A soft supersymmetry breaking induces a nonzero contribution to the vacuum energy density and pressure. Assuming the presence of a cosmic fluid in addition to the vacuum fluctuations of the supersymmetric field an effective equation of state is derived in a self-consistent approach at one loop order. The net effect of the vacuum fluctuations of the supersymmetric fields in the leading adiabatic order is a renormalization of the Newton and cosmological constants.

  15. Thermodynamic constraints on fluctuation phenomena

    Science.gov (United States)

    Maroney, O. J. E.

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  16. Fluctuation theorems for quantum processes.

    Science.gov (United States)

    Albash, Tameem; Lidar, Daniel A; Marvian, Milad; Zanardi, Paolo

    2013-09-01

    We present fluctuation theorems and moment generating function equalities for generalized thermodynamic observables and quantum dynamics described by completely positive trace preserving maps, with and without feedback control. Our results include the quantum Jarzynski equality and Crooks fluctuation theorem, and clarify the special role played by the thermodynamic work and thermal equilibrium states in previous studies. We show that for a specific class of generalized measurements, which include projective measurements, unitality replaces microreversibility as the condition for the physicality of the reverse process in our fluctuation theorems. We present an experimental application of our theory to the problem of extracting the system-bath coupling magnitude, which we do for a system of pairs of coupled superconducting flux qubits undergoing quantum annealing.

  17. Fluctuation theorems for stochastic dynamics

    Science.gov (United States)

    Harris, R. J.; Schütz, G. M.

    2007-07-01

    Fluctuation theorems make use of time reversal to make predictions about entropy production in many-body systems far from thermal equilibrium. Here we review the wide variety of distinct, but interconnected, relations that have been derived and investigated theoretically and experimentally. Significantly, we demonstrate, in the context of Markovian stochastic dynamics, how these different fluctuation theorems arise from a simple fundamental time-reversal symmetry of a certain class of observables. Appealing to the notion of Gibbs entropy allows for a microscopic definition of entropy production in terms of these observables. We work with the master equation approach, which leads to a mathematically straightforward proof and provides direct insight into the probabilistic meaning of the quantities involved. Finally, we point to some experiments that elucidate the practical significance of fluctuation relations.

  18. Fluctuation theorems for quantum processes

    Science.gov (United States)

    Albash, Tameem; Lidar, Daniel A.; Marvian, Milad; Zanardi, Paolo

    2013-09-01

    We present fluctuation theorems and moment generating function equalities for generalized thermodynamic observables and quantum dynamics described by completely positive trace preserving maps, with and without feedback control. Our results include the quantum Jarzynski equality and Crooks fluctuation theorem, and clarify the special role played by the thermodynamic work and thermal equilibrium states in previous studies. We show that for a specific class of generalized measurements, which include projective measurements, unitality replaces microreversibility as the condition for the physicality of the reverse process in our fluctuation theorems. We present an experimental application of our theory to the problem of extracting the system-bath coupling magnitude, which we do for a system of pairs of coupled superconducting flux qubits undergoing quantum annealing.

  19. Modeling fluctuations in scattered waves

    CERN Document Server

    Jakeman, E

    2006-01-01

    Fluctuations in scattered waves limit the performance of imaging and remote sensing systems that operate on all wavelengths of the electromagnetic spectrum. To better understand these fluctuations, Modeling Fluctuations in Scattered Waves provides a practical guide to the phenomenology, mathematics, and simulation of non-Gaussian noise models and discusses how they can be used to characterize the statistics of scattered waves.Through their discussion of mathematical models, the authors demonstrate the development of new sensing techniques as well as offer intelligent choices that can be made for system analysis. Using experimental results and numerical simulation, the book illustrates the properties and applications of these models. The first two chapters introduce statistical tools and the properties of Gaussian noise, including results on phase statistics. The following chapters describe Gaussian processes and the random walk model, address multiple scattering effects and propagation through an extended med...

  20. Rapid determination of vial heat transfer parameters using tunable diode laser absorption spectroscopy (TDLAS) in response to step-changes in pressure set-point during freeze-drying.

    Science.gov (United States)

    Kuu, Wei Y; Nail, Steven L; Sacha, Gregory

    2009-03-01

    The purpose of this study was to perform a rapid determination of vial heat transfer parameters, that is, the contact parameter K(cs) and the separation distance l(v), using the sublimation rate profiles measured by tunable diode laser absorption spectroscopy (TDLAS). In this study, each size of vial was filled with pure water followed by a freeze-drying cycle using a LyoStar II dryer (FTS Systems) with step-changes of the chamber pressure set-point at to 25, 50, 100, 200, 300, and 400 mTorr. K(cs) was independently determined by nonlinear parameter estimation using the sublimation rates measured at the pressure set-point of 25 mTorr. After obtaining K(cs), the l(v) value for each vial size was determined by nonlinear parameter estimation using the pooled sublimation rate profiles obtained at 25 to 400 mTorr. The vial heat transfer coefficient K(v), as a function of the chamber pressure, was readily calculated, using the obtained K(cs) and l(v) values. It is interesting to note the significant difference in K(v) of two similar types of 10 mL Schott tubing vials, primary due to the geometry of the vial-bottom, as demonstrated by the images of the contact areas of the vial-bottom. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

  1. Chromodynamic Fluctuations in Quark-Gluon Plasma

    OpenAIRE

    Mrowczynski, Stanislaw

    2008-01-01

    Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations...

  2. Measurement of magnetic fluctuation-induced heat transport in tokamaks and RFP

    Energy Technology Data Exchange (ETDEWEB)

    Fiksel, G.; Hartog, D.D.; Cekic, M.; Prager, S.C. [and others

    1996-08-01

    It has long been recognized that fluctuations in the magnetic field are a potent mechanism for the anomalous transport of energy in confined plasmas. The energy transport process originates from particle motion along magnetic fields, which have a fluctuating component in the radial direction (perpendicular to the confining equilibrium magnetic surfaces). A key feature is that the transport can be large even if the fluctuation amplitude is small. If the fluctuations are resonant with the equilibrium magnetic field (i.e., the fluctuation amplitude is constant along an equilibrium field line) then a small fluctuation can introduce stochasticity to the field line trajectories. Particles following the chaotically wandering field lines can rapidly carry energy across the plasma.

  3. Cirrus feedback on interannual climate fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, C; Dessler, A E; Zelinka, M D; Yang, P; Wang, T

    2014-12-28

    Cirrus clouds are not only important in determining the current climate, but also play an important role in climate change and variability. Analysis of satellite observations shows that the amount and altitude of cirrus clouds (optical depth <3.6, cloud top pressure <440 hPa) increase in response to inter-annual surface warming. Thus, cirrus clouds are likely to act as a positive feedback on short-term climate fluctuations, by reducing the planet’s ability to radiate longwave radiation to space in response to planetary surface warming. Using cirrus cloud radiative kernels, the magnitude of cirrus feedback is estimated to be 0.20±0.21W/m2/°C, which is comparable to the surface albedo feedback. Most of the cirrus feedback comes from increasing cloud amount in the tropical tropopause layer (TTL) and subtropical upper troposphere.

  4. A rapid, sensitive and validated method for the determination of ondansetron in human plasma by reversed-phase high-pressure liquid chromatography.

    Science.gov (United States)

    Chandrasekar, Durairaj; Ramakrishna, Sistla; Diwan, Prakash V

    2004-01-01

    A simple and sensitive method for the determination of ondansetron (CAS 116002-70-1) in human plasma was developed using high-pressure liquid chromatography (HPLC). The procedure involves extraction of human plasma with tertiary butyl methyl ether containing 2 mol/l sodium hydroxide, followed by reversed-phase HPLC using a LiChrospher 100 RP-18e 5 microm column and UV detection at 305 nm. The retention times of ondansetron and internal standard (propranolol hydrochloride, CAS 318-98-9) were 9.38 and 13.40 min, respectively. The calibration curves were linear over the range of 10 ng/ml (lower limit of quantitation, LOQ) and 380 ng/ml for ondansetron. The intra- and inter-assay coefficients of variation for all the criteria of validation were less than 15% over the linearity range. Ondansetron was stable upon storage in human plasma. The sensitivity and precision of the method were within the accepted limits (< 15 %) throughout the validation period. The present method is useful for determination of plasma concentrations of ondansetron during human pharmacokinetic studies.

  5. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Science.gov (United States)

    How, Penelope; Benn, Douglas I.; Hulton, Nicholas R. J.; Hubbard, Bryn; Luckman, Adrian; Sevestre, Heïdi; van Pelt, Ward J. J.; Lindbäck, Katrin; Kohler, Jack; Boot, Wim

    2017-11-01

    Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  6. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Directory of Open Access Journals (Sweden)

    P. How

    2017-11-01

    Full Text Available Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  7. Low Mach number fluctuating hydrodynamics of multispecies liquid mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Donev, Aleksandar, E-mail: donev@courant.nyu.edu; Bhattacharjee, Amit Kumar [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Nonaka, Andy; Bell, John B. [Center for Computational Science and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, San Jose, California 95192 (United States)

    2015-03-15

    We develop a low Mach number formulation of the hydrodynamic equations describing transport of mass and momentum in a multispecies mixture of incompressible miscible liquids at specified temperature and pressure, which generalizes our prior work on ideal mixtures of ideal gases [Balakrishnan et al., “Fluctuating hydrodynamics of multispecies nonreactive mixtures,” Phys. Rev. E 89 013017 (2014)] and binary liquid mixtures [Donev et al., “Low mach number fluctuating hydrodynamics of diffusively mixing fluids,” Commun. Appl. Math. Comput. Sci. 9(1), 47-105 (2014)]. In this formulation, we combine and extend a number of existing descriptions of multispecies transport available in the literature. The formulation applies to non-ideal mixtures of arbitrary number of species, without the need to single out a “solvent” species, and includes contributions to the diffusive mass flux due to gradients of composition, temperature, and pressure. Momentum transport and advective mass transport are handled using a low Mach number approach that eliminates fast sound waves (pressure fluctuations) from the full compressible system of equations and leads to a quasi-incompressible formulation. Thermal fluctuations are included in our fluctuating hydrodynamics description following the principles of nonequilibrium thermodynamics. We extend the semi-implicit staggered-grid finite-volume numerical method developed in our prior work on binary liquid mixtures [Nonaka et al., “Low mach number fluctuating hydrodynamics of binary liquid mixtures,” http://arxiv.org/abs/1410.2300 (2015)] and use it to study the development of giant nonequilibrium concentration fluctuations in a ternary mixture subjected to a steady concentration gradient. We also numerically study the development of diffusion-driven gravitational instabilities in a ternary mixture and compare our numerical results to recent experimental measurements [Carballido-Landeira et al., “Mixed-mode instability of a

  8. Pressure fluctuations on the bed of surge tank at the H.P. Zimapan, Hgo., with different arrangements studied on hydraulic model, with the lowest operation conditions; Fluctuaciones de presion en la base del pozo de oscilacion del P.H. Zimapan Hgo., con diferentes arreglos estudiados en modelo hidraulico ante las condiciones minimas de operacion

    Energy Technology Data Exchange (ETDEWEB)

    Marengo Mogollon, H. [Facultad de Ingenieria, Universidad Nacional Autonoma de Mexico (Mexico)]. E-mail: humberto.marengo@cfe.gob.mx; Ochoa Alvarez, F.J.; Cortes Cortes, C. [Comision Federal de Electricidad (Mexico)]. E-mail: federico.ochoa@cfe.gob.mx; carlos.cortes01@cfe.gob.mx

    2009-10-15

    In this paper, the pressure fluctuations of the surge tank in the Zimapan Hydroelectric Project are compared in a hydraulic model. The shaft is located lateral, over the conduction tunnel and in the simple form (permitting the tunnel entering the shaft); with and without orifice plates taking into account the demand and supply condition of energy with the minimum level of water of the conduction. It was determined the hydraulic efficiency and it was found that it was the best constructive option. [Spanish] En este articulo se comparan las fluctuaciones de presion en el pozo de oscilacion del P.H. Zimapan, Hgo., Mexico las cuales fueron estudiadas en modelo hidraulico al considerar dicho pozo ubicado en diferentes posiciones; lateralmente y sobre el eje de la conduccion; pozo simple y con tuberia de conexion; con y sin placa de orificio, para maniobras de rechazo y demanda de carga de las turbinas de generacion con el nivel del agua correspondiente al NAMINO. Se determino la eficiencia hidraulica comparandola con las otras opciones encontrandose que la mejor opcion para el funcionamiento hidraulico es el pozo lateral, que ademas permite optimizar el procedimiento constructivo.

  9. Linear modeling of glacier fluctuations

    NARCIS (Netherlands)

    Oerlemans, J.|info:eu-repo/dai/nl/06833656X

    2012-01-01

    In this contribution a linear first-order differential equation is used to model glacier length fluctuations. This equation has two parameters describing the physical characteristics of a glacier: the climate sensitivity, expressing how the equilibrium glacier length depends on the climatic state,

  10. Fluctuating hydrodynamics for ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Lazaridis, Konstantinos [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States); Wickham, Logan [Department of Computer Science, Washington State University, Richland, 99354 (United States); Voulgarakis, Nikolaos, E-mail: n.voulgarakis@wsu.edu [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States)

    2017-04-25

    We present a mean-field fluctuating hydrodynamics (FHD) method for studying the structural and transport properties of ionic liquids in bulk and near electrified surfaces. The free energy of the system consists of two competing terms: (1) a Landau–Lifshitz functional that models the spontaneous separation of the ionic groups, and (2) the standard mean-field electrostatic interaction between the ions in the liquid. The numerical approach used to solve the resulting FHD-Poisson equations is very efficient and models thermal fluctuations with remarkable accuracy. Such density fluctuations are sufficiently strong to excite the experimentally observed spontaneous formation of liquid nano-domains. Statistical analysis of our simulations provides quantitative information about the properties of ionic liquids, such as the mixing quality, stability, and the size of the nano-domains. Our model, thus, can be adequately parameterized by directly comparing our prediction with experimental measurements and all-atom simulations. Conclusively, this work can serve as a practical mathematical tool for testing various theories and designing more efficient mixtures of ionic liquids. - Highlights: • A new fluctuating hydrodynamics method for ionic liquids. • Description of ionic liquid morphology in bulk and near electrified surfaces. • Direct comparison with experimental measurements.

  11. Reaction rates when barriers fluctuate

    OpenAIRE

    Reimann, Peter

    1999-01-01

    Reaction rates when barriers fluctuate : a path integral approach / P. Hänggi and P. Reimann. - In: International Conference on Path Integrals from peV to TeV : Proceedings of the ... / eds.: R. Casalbuoni ... - Singapore u.a. : World Scientific, 1999. - S. 407-409

  12. Mobile tablet audiometry in fluctuating autoimmune ear disease.

    Science.gov (United States)

    Kohlert, Scott; Bromwich, Matthew

    2017-03-07

    Autoimmune inner ear disease (AIED) is a rare condition characterized by bilateral fluctuating sensorineural hearing loss (SNHL). The labile nature of this hearing loss makes it difficult to accurately quantify with conventional methods, and therefore it is challenging to rehabilitate. Over a 9-month period one pediatric patient with severe AIED was monitored and conducted home audiograms using a previously validated testing system (Shoebox Audiometry). During this period he also underwent several clinical audiograms. The correlation between clinical and home audiograms was analyzed with a Pearson coefficient, and the range and frequency of fluctuations was recorded. Sixty-four automated home audiograms and nine clinical audiograms were conducted. When tested at home using a calibrated system the pure tone average (PTA) fluctuated between 12 dB and 72 dB indicating large variability in hearing. Fluctuations were frequent: on 28 occasions the PTA varied by at least 5 dB when retested within 4 days. The mean PTA was 50 dB and 95% of the thresholds were within 36 dB of the mean. Clinical audiograms obtained on the same day or within 1 day of home testing were highly concordant (with a Pearson coefficient of 0.93). AIED can result in significant fluctuations in hearing over short periods of time. Home testing enables a more granular look at variations over time and correlates well with clinical testing, and thus facilitates rapid action and informed rehabilitation.

  13. Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth.

    Science.gov (United States)

    Lillie, M A; Piscitelli, M A; Vogl, A W; Gosline, J M; Shadwick, R E

    2013-07-15

    Fin whales have an incompliant aorta, which, we hypothesize, represents an adaptation to large, depth-induced variations in arterial transmural pressures. We hypothesize these variations arise from a limited ability of tissues to respond to rapid changes in ambient ocean pressures during a dive. We tested this hypothesis by measuring arterial mechanics experimentally and modelling arterial transmural pressures mathematically. The mechanical properties of mammalian arteries reflect the physiological loads they experience, so we examined a wide range of fin whale arteries. All arteries had abundant adventitial collagen that was usually recruited at very low stretches and inflation pressures (2-3 kPa), making arterial diameter largely independent of transmural pressure. Arteries withstood significant negative transmural pressures (-7 to -50 kPa) before collapsing. Collapse was resisted by recruitment of adventitial collagen at very low stretches. These findings are compatible with the hypothesis of depth-induced variation of arterial transmural pressure. Because transmural pressures depend on thoracic pressures, we modelled the thorax of a diving fin whale to assess the likelihood of significant variation in transmural pressures. The model predicted that deformation of the thorax body wall and diaphragm could not always equalize thoracic and ambient pressures because of asymmetrical conditions on dive descent and ascent. Redistribution of blood could partially compensate for asymmetrical conditions, but inertial and viscoelastic lag necessarily limits tissue response rates. Without pressure equilibrium, particularly when ambient pressures change rapidly, internal pressure gradients will develop and expose arteries to transient pressure fluctuations, but with minimal hemodynamic consequence due to their low compliance.

  14. Nematic fluctuations and resonance in iron-based superconductors

    Science.gov (United States)

    Gallais, Yann

    The spontaneous appearance of nematicity, a state of matter that breaks rotation but not translation symmetry, is ubiquitous in many iron based superconductors (Fe SC), and has relevance for the cuprates as well. Here I will review recent electronic Raman scattering experiments which report the presence of critical nematic fluctuations in the charge channel in the tetragonal phase of several Fe SC systems. In electron doped Co-BaFe2As2 (Co-Ba122), these fluctuations extend over most of the superconducting dome. Their associated nematic susceptibility shows Curie-Weiss behavior, and its doping dependence suggests the presence of a nematic quantum critical point near optimal TC Similar nematic fluctuations are also observed in FeSe despite the absence of magnetic order, raising the question of the link between nematicity and magnetism in Fe SC. In FeSe I will further contrast the evolution of nematic fluctuations under isoelectronic S substitution and hydrostatic pressures up to 8 GPa, with only the former showing evidence for a nematic quantum critical point. In the superconducting state of Co-Ba122, I will show that a resonance emerges in the Raman spectra near the nematic quantum critical point. This nematic resonance is a clear fingerprint of the coupling between nematic fluctuations and Bogoliubov quasiparticles, and can be thought as the nematic counterpart of the spin resonance observed in neutron scattering experiments. Support from Agence Nationale de la Recherche via ANR Grant ''Pnictides'' is acknowledged.

  15. Blood Pressure Fluctuations Tied to Dementia Risk in Study

    Science.gov (United States)

    ... Ph.D., assistant professor, neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka City, Japan; Costantino Iadecola, M.D., professor, neurology, director, Feil Family Brain and Mind Research Institute, Weill Cornell College of Medicine, New York ...

  16. Superposed epoch analysis of physiological fluctuations: possible space weather connections

    Science.gov (United States)

    Wanliss, James; Cornélissen, Germaine; Halberg, Franz; Brown, Denzel; Washington, Brien

    2017-10-01

    There is a strong connection between space weather and fluctuations in technological systems. Some studies also suggest a statistical connection between space weather and subsequent fluctuations in the physiology of living creatures. This connection, however, has remained controversial and difficult to demonstrate. Here we present support for a response of human physiology to forcing from the explosive onset of the largest of space weather events—space storms. We consider a case study with over 16 years of high temporal resolution measurements of human blood pressure (systolic, diastolic) and heart rate variability to search for associations with space weather. We find no statistically significant change in human blood pressure but a statistically significant drop in heart rate during the main phase of space storms. Our empirical findings shed light on how human physiology may respond to exogenous space weather forcing.

  17. Superposed epoch analysis of physiological fluctuations: possible space weather connections.

    Science.gov (United States)

    Wanliss, James; Cornélissen, Germaine; Halberg, Franz; Brown, Denzel; Washington, Brien

    2017-10-13

    There is a strong connection between space weather and fluctuations in technological systems. Some studies also suggest a statistical connection between space weather and subsequent fluctuations in the physiology of living creatures. This connection, however, has remained controversial and difficult to demonstrate. Here we present support for a response of human physiology to forcing from the explosive onset of the largest of space weather events-space storms. We consider a case study with over 16 years of high temporal resolution measurements of human blood pressure (systolic, diastolic) and heart rate variability to search for associations with space weather. We find no statistically significant change in human blood pressure but a statistically significant drop in heart rate during the main phase of space storms. Our empirical findings shed light on how human physiology may respond to exogenous space weather forcing.

  18. Characterizing the dynamic property of the vortex tail in a gas cyclone by wall pressure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Cuizhi; Sun, Guogang; Dong, Ruiqian; Fu, Shuangcheng [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249 (China)

    2010-08-15

    To explore a determination method for cyclone vortex tail, the wall pressures at different axial and radial positions of a cylinder-on-cone cyclone were measured and analyzed by the Fast Fourier Transform (FFT) and probability density analyses in this paper. The cyclone vortex tail was also visualized by a red ink tracer. The results show that the cyclone wall pressure does not change in the cylindrical section and gradually decreases in the conical section. The magnitudes of wall pressure at different azimuths are almost identical, indicating an axisymmetrical wall pressure radial profile in these parts of the cyclone. Whereas in the lower part of the cone and/or the upper part of dipleg, there is a sudden fall of wall pressure and non-axisymmetrical pressure radial profile. The minimum wall pressure occurs at about 270 azimuth in this region. Underneath in the next part of the dipleg, the wall pressure rapidly rises and returns to axisymmetry. These characteristics indicate that the vortex tail is bended to wall, turns around in this region, and can be used as evidences of the vortex tail. The position determined by the pressure measurement is close to the position of the rotating ring observed in the tracing experiment. It is also found that the frequency of the inner vortex is different from that of the outer vortex. The inner vortex flow fluctuates stronger and faster than its outer partner. At the vortex tail zone, the vortex breaks and the inner vortex fluctuation is involved in the wall pressure signal. Therefore, the position and dynamic property of the vortex tail can be well identified from the wall pressure measurement. The pressure measurement could provide some solid experimental basis for assessing relations of natural vortex length. (author)

  19. Fluctuation-Induced Pattern Formation in a Surface Reaction

    DEFF Research Database (Denmark)

    Starke, Jens; Reichert, Christian; Eiswirth, Markus

    2006-01-01

    Spontaneous nucleation, pulse formation, and propagation failure have been observed experimentally in CO oxidation on Pt(110) at intermediate pressures ($\\approx 10^{-2}$mbar). This phenomenon can be reproduced with a stochastic model which includes temperature effects. Nucleation occurs randomly...... due to fluctuations in the reaction processes, whereas the subsequent damping out essentially follows the deterministic path. Conditions for the occurence of stochastic effects in the pattern formation during CO oxidation on Pt are discussed....

  20. Molecular Thermodynamic Modeling of Fluctuation Solution Theory Properties

    DEFF Research Database (Denmark)

    O’Connell, John P.; Abildskov, Jens

    2013-01-01

    Fluctuation Solution Theory provides relationships between integrals of the molecular pair total and direct correlation functions and the pressure derivative of solution density, partial molar volumes, and composition derivatives of activity coefficients. For dense fluids, the integrals follow...... a relatively simple corresponding-states behavior even for complex systems, show welldefined relationships for infinite dilution properties in complex and near-critical systems, allow estimation of mixed-solvent solubilities of gases and pharmaceuticals, and can be expressed by simple perturbation models...

  1. Parity fluctuations in stellar dynamos

    Science.gov (United States)

    Moss, D. L.; Sokoloff, D. D.

    2017-10-01

    Observations of the solar butterfly diagram from sunspot records suggest persistent fluctuations in parity, away from the overall, approximately dipolar pattern. A simple mean-field dynamo model is used with a solar-like rotation law and perturbed α effect. The parity of the magnetic field relative to the rotational equator can demonstrate can be described as resonance behavior, while the magnetic energy behaves in a more or less expected way. Possible applications of this effect are discussed in the context of various deviations of the solar magnetic field from dipolar symmetry, as reported from analyses of archival sunspot data. The model produces fluctuations in field parity, and hence in the butterfly diagram, that are consistent with observed fluctuaions in solar behavior.

  2. Fuel Temperature Fluctuations During Storage

    Science.gov (United States)

    Levitin, R. E.; Zemenkov, Yu D.

    2016-10-01

    When oil and petroleum products are stored, their temperature significantly impacts how their properties change. The paper covers the problem of determining temperature fluctuations of hydrocarbons during storage. It provides results of the authors’ investigations of the stored product temperature variations relative to the ambient temperature. Closeness and correlation coefficients between these values are given. Temperature variations equations for oil and petroleum products stored in tanks are deduced.

  3. A Generalization of Electromagnetic Fluctuation-Induced Casimir Energy

    Directory of Open Access Journals (Sweden)

    Yi Zheng

    2015-01-01

    Full Text Available Intermolecular forces responsible for adhesion and cohesion can be classified according to their origins; interactions between charges, ions, random dipole—random dipole (Keesom, random dipole—induced dipole (Debye are due to electrostatic effects; covalent bonding, London dispersion forces between fluctuating dipoles, and Lewis acid-base interactions are due to quantum mechanical effects; pressure and osmotic forces are of entropic origin. Of all these interactions, the London dispersion interaction is universal and exists between all types of atoms as well as macroscopic objects. The dispersion force between macroscopic objects is called Casimir/van der Waals force. It results from alteration of the quantum and thermal fluctuations of the electrodynamic field due to the presence of interfaces and plays a significant role in the interaction between macroscopic objects at micrometer and nanometer length scales. This paper discusses how fluctuational electrodynamics can be used to determine the Casimir energy/pressure between planar multilayer objects. Though it is confirmation of the famous work of Dzyaloshinskii, Lifshitz, and Pitaevskii (DLP, we have solved the problem without having to use methods from quantum field theory that DLP resorted to. Because of this new approach, we have been able to clarify the contributions of propagating and evanescent waves to Casimir energy/pressure in dissipative media.

  4. Relationship among phenotypic plasticity, phenotypic fluctuations ...

    Indian Academy of Sciences (India)

    Prakash

    These results provide quantitative formulation on canalization and genetic assimilation, in terms of fluctuations of gene expression levels. [Kaneko K 2009 Relationship among phenotypic plasticity, phenotypic fluctuations, robustness, and evolvability; Waddington's legacy revisited under the spirit of Einstein; J. Biosci.

  5. Some comments to the quantum fluctuation theorems

    OpenAIRE

    Kuzovlev, Yu. E.

    2011-01-01

    It is demonstrated that today's quantum fluctuation theorems are component part of old quantum fluctuation-dissipation relations [Sov.Phys.-JETP 45, 125 (1977)], and typical misunderstandings in this area are pointed out.

  6. Correlated interaction fluctuations in photosynthetic complexes

    CERN Document Server

    Vlaming, Sebastiaan M

    2011-01-01

    The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies of and interactions between the chlorophyll molecules, and due to the fact that different fluctuations will partially be caused by the same environmental factors, correlations between the various fluctuations will occur. We argue that fluctuations of the interactions should in general not be neglected, as these have a considerable impact on population transfer rates, decoherence rates and the efficiency of photosynthetic complexes. Furthermore, while correlations between transition energy fluctuations have been studied, we provide the first quantitative study of the effect of correlations between interaction fluctuations and transition energy fluctuations, and of correlations between the various interaction fluctuations. It is shown t...

  7. Fluctuation theory of luminance and chromaticity discrimination

    NARCIS (Netherlands)

    Bouman, M.A.; Vos, J.J.; Walraven, P.L.

    1963-01-01

    An attempt has been made to describe brightness and color discrimination in the framework of a fluctuation theory. The fluctuation theory states that a difference between two stimuli will be just noticeable if it exceeds, by some factor, the average of the fluctuations in the stimuli. If the

  8. Simulating the seismic pressure noise on Mars

    Science.gov (United States)

    Murdoch, N.; Kenda, B.; Kawamura, T.; Spiga, A.; Lognonné, P.; Mimoun, D.; Banerdt, W. B.

    2017-09-01

    The atmospheric pressure fluctuations on Mars will induce an elastic response in the ground that will create a ground tilt, detectable as a seismic signal on SEIS. We use Large Eddy Simulations of the wind and surface pressure at the InSight landing site, combined with ground deformation models to investigate the atmospheric pressure signals on SEIS.

  9. The initiation of boiling during pressure transients. [water boiling on metal surfaces

    Science.gov (United States)

    Weisman, J.; Bussell, G.; Jashnani, I. L.; Hsieh, T.

    1973-01-01

    The initiation of boiling of water on metal surfaces during pressure transients has been investigated. The data were obtained by a new technique in which light beam fluctuations and a pressure signal were simultaneously recorded on a dual beam oscilloscope. The results obtained agreed with those obtained using high speed photography. It was found that, for water temperatures between 90-150 C, the wall superheat required to initiate boiling during a rapid pressure transient was significantly higher than required when the pressure was slowly reduced. This result is explained by assuming that a finite time is necessary for vapor to fill the cavity at which the bubble originates. Experimental measurements of this time are in reasonably good agreement with calculations based on the proposed theory. The theory includes a new procedure for estimating the coefficient of vaporization.

  10. Beam Energy and System Size Dependence of Dynamical Net Charge Fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    STAR Coll

    2008-07-21

    We present measurements of net charge fluctuations in Au + Au collisions at {radical}s{sub NN} = 19.6, 62.4, 130, and 200 GeV, Cu + Cu collisions at {radical}s{sub NN} = 62.4, 200 GeV, and p + p collisions at {radical}s = 200 GeV using the dynamical net charge fluctuations measure {nu}{sub {+-},dyn}. We observe that the dynamical fluctuations are non-zero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/N{sub ch} scaling, but display approximate 1/N{sub part} scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity widths integrated to measure the correlation.

  11. Chaotic fluctuations in mathematical economics

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Hiroyuki, E-mail: yoshida.hiroyuki@nihon-u.ac.jp [College of Economics, Nihon University, Chiyoda-ku, Tokyo 101-8360 (Japan)

    2011-03-01

    In this paper we examine a Cournot duopoly model, which expresses the strategic interaction between two firms. We formulate the dynamic adjustment process and investigate the dynamic properties of the stationary point. By introducing a memory mechanism characterized by distributed lag functions, we presuppose that each firm makes production decisions in a cautious manner. This implies that we have to deal with the system of integro-differential equations. By means of numerical simulations we show the occurrence of chaotic fluctuations in the case of fixed delays.

  12. Noise and fluctuations an introduction

    CERN Document Server

    MacDonald, D K C

    2006-01-01

    An understanding of fluctuations and their role is both useful and fundamental to the study of physics. This concise study of random processes offers graduate students and research physicists a survey that encompasses both the relationship of Brownian Movement with statistical mechanics and the problem of irreversible processes. It outlines the basics of the physics involved, without the strictures of mathematical rigor.The three-part treatment starts with a general survey of Brownian Movement, including electrical Brownian Movement and ""shot-noise,"" Part two explores correlation, frequency

  13. Electrostatic fluctuations in soap films.

    Science.gov (United States)

    Dean, D S; Horgan, R R

    2002-06-01

    A field theory to describe electrostatic interactions in soap films, described by electric multilayers with a generalized thermodynamic surface-charging mechanism, is studied. In the limit where the electrostatic interactions are weak, this theory is exactly soluble. The theory incorporates in a consistent way, the surface-charging mechanism and the fluctuations in the electrostatic field that correspond to the zero-frequency component of the van der Waals force. It is shown that these terms lead to a Casimir-like attraction that can be sufficiently large to explain the transition between the common black film to a Newton black film.

  14. An objective fluctuation score for Parkinson's disease.

    Directory of Open Access Journals (Sweden)

    Malcolm K Horne

    Full Text Available Establishing the presence and severity of fluctuations is important in managing Parkinson's Disease yet there is no reliable, objective means of doing this. In this study we have evaluated a Fluctuation Score derived from variations in dyskinesia and bradykinesia scores produced by an accelerometry based system.The Fluctuation Score was produced by summing the interquartile range of bradykinesia scores and dyskinesia scores produced every 2 minutes between 0900-1800 for at least 6 days by the accelerometry based system and expressing it as an algorithm.This Score could distinguish between fluctuating and non-fluctuating patients with high sensitivity and selectivity and was significant lower following activation of deep brain stimulators. The scores following deep brain stimulation lay in a band just above the score separating fluctuators from non-fluctuators, suggesting a range representing adequate motor control. When compared with control subjects the score of newly diagnosed patients show a loss of fluctuation with onset of PD. The score was calculated in subjects whose duration of disease was known and this showed that newly diagnosed patients soon develop higher scores which either fall under or within the range representing adequate motor control or instead go on to develop more severe fluctuations.The Fluctuation Score described here promises to be a useful tool for identifying patients whose fluctuations are progressing and may require therapeutic changes. It also shows promise as a useful research tool. Further studies are required to more accurately identify therapeutic targets and ranges.

  15. Rapid wide-scope screening of drugs of abuse, prescription drugs with potential for abuse and their metabolites in influent and effluent urban wastewater by ultrahigh pressure liquid chromatography-quadrupole-time-of-flight-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Felix, E-mail: felix.hernandez@qfa.uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat s/n, E-12071 Castellon (Spain); Bijlsma, Lubertus, E-mail: bijlsma@guest.uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat s/n, E-12071 Castellon (Spain); Sancho, Juan V.; Diaz, Ramon; Ibanez, Maria [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat s/n, E-12071 Castellon (Spain)

    2011-01-17

    This work illustrates the potential of hybrid quadrupole-time-of-flight mass spectrometry (QTOF MS) coupled to ultrahigh pressure liquid chromatography (UHPLC) to investigate the presence of drugs of abuse in wastewater. After solid-phase extraction with Oasis MCX cartridges, seventy-six illicit drugs, prescription drugs with potential for abuse, and metabolites were investigated in the samples by TOF MS using electrospray interface under positive ionization mode, with MS data acquired over an m/z range of 50-1000 Da. For 11 compounds, reference standards were available, and experimental data (e.g., retention time and fragmentation data) could be obtained, facilitating a more confident identification. The use of a QTOF instrument enabled the simultaneous application of two acquisition functions with different collision energies: a low energy (LE) function, where none or poor fragmentation took place, and a high energy (HE) function, where fragmentation in the collision cell was promoted. This approach, known as MS{sup E}, enabled the simultaneous acquisition of full-spectrum accurate mass data of both protonated molecules and fragment ions in a single injection, providing relevant information that facilitates the rapid detection and reliable identification of these emerging contaminants in the sample matrices analyzed. In addition, isomeric compounds, like the opiates, morphine and norcodeine, could be discriminated by their specific fragments observed in HE TOF MS spectra, without the need of reference standards. UHPLC-QTOF MS was proven to be a powerful and efficient technique for rapid wide-scope screening and identification of many relevant drugs in complex matrices, such as influent and effluent urban wastewater.

  16. Toward models for fluctuating wall quantities in incompressible turbulent flows

    Science.gov (United States)

    Towne, Aaron; Yang, Xiang; Moin, Parviz

    2017-11-01

    Wall models for large-eddy simulation have been developed that provide accurate estimates of mean wall quantities such as shear stress, heat transfer, and pressure. However, these models typically do not deliver accurate predictions of the space-time fluctuations of these quantities. In this presentation, we describe some first steps toward constructing new wall models that predict the spatiotemporal properties of wall quantities by taking advantage of recent advances in our ability to identify and model the coherent structures that are known to play a central role in the near-wall dynamics. We first analyze data from a direct numerical simulation of a channel at Reτ = 1000 using spectral estimation techniques to isolate the contribution from different scales to fluctuating wall quantities and correlation analysis to link different spatial locations. Then, we explore how modes obtained via singular value decomposition of the resolvent operator, which is obtained from the linearized flow equations, could be used to model these fluctuations. This analysis provides a starting point for leveraging these model reduction ideas to improve the prediction of near-wall fluctuations using wall-modelled large-eddy simulation. Funded by NASA Grant No. NNX15AU93A and PSAAPII Grant No. DE-NA0002373.

  17. Real gas effects on receptivity to kinetic fluctuations

    Science.gov (United States)

    Tumin, Anatoli; Edwards, Luke

    2016-11-01

    Receptivity of high-speed boundary layers is considered within the framework of fluctuating hydrodynamics where stochastic forcing is introduced through fluctuating shear stress and heat flux stemming from kinetic fluctuations (thermal noise). The forcing generates unstable modes whose amplification downstream and may lead to transition. An example of high-enthalpy (16 . 53 MJ / kg) boundary layer at relatively low wall temperatures (Tw = 1000 K - 3000 K), free stream temperature (Te = 834 K), and low pressure (0 . 0433 atm) is considered. Dissociation at the chosen flow parameters is still insignificant. The stability and receptivity analyses are carried out using a solver for calorically perfect gas with effective Prandtl number and specific heats ratio. The receptivity phenomenon is unchanged by the inclusion of real gas effects in the mean flow profiles. This is attributed to the fact that the mechanism for receptivity to kinetic fluctuations is localized near the upper edge of the boundary layer. Amplitudes of the generated wave packets are larger downstream in the case including real gas effects. It was found that spectra in both cases include supersonic second Mack unstable modes despite the temperature ratio Tw /Te > 1 . Supported by AFOSR.

  18. Multifractal conductance fluctuations in graphene

    Science.gov (United States)

    Bid, Aveek; Rafsanjani Amin, Kazi; Pal, Nairita; Sankar Ray, Samriddhi; Pandit, Rahul

    A multifractal (MF) system is characterized by scaling laws involving an infinite number of exponents. In condensed-matter systems, signatures of multifractality have typically been found in the structure of the critical wave functions at localization delocalization (LD) transitions. We report here the first experimental observation of MF statistics in the transport coefficients of a quantum-condensed matter system. We unearth this through a careful investigation of the magneto-conductance fluctuations in ultra-high mobility single layer graphene at ultra-low temperatures. We obtain the MF spectra over a wide range of temperature and doping levels and show that the multifractality decreases as the temperature increases or as the doping moves the system away from the Dirac point. We show that the fractal exponents are a universal function of the phase coherence length of the carriers. We propose that a probable origin of the MF magneto-conductance fluctuations observed by us is an incipient Anderson LD transition in graphene near the charge neutrality point - a phenomenon predicted but never observed in single layer graphene. We also explore alternate possibilities of the origin of the multifractality namely relativistic quantum scars. AB acknowledges funding from Nanomission, DST, Govt. of India and SERB, DST, Govt. of India.

  19. Protrusion Fluctuations Direct Cell Motion

    Science.gov (United States)

    Caballero, David; Voituriez, Raphaël; Riveline, Daniel

    2014-01-01

    Many physiological phenomena involve directional cell migration. It is usually attributed to chemical gradients in vivo. Recently, other cues have been shown to guide cells in vitro, including stiffness/adhesion gradients or micropatterned adhesive motifs. However, the cellular mechanism leading to these biased migrations remains unknown, and, often, even the direction of motion is unpredictable. In this study, we show the key role of fluctuating protrusions on ratchet-like structures in driving NIH3T3 cell migration. We identified the concept of efficient protrusion and an associated direction index. Our analysis of the protrusion statistics facilitated the quantitative prediction of cell trajectories in all investigated conditions. We varied the external cues by changing the adhesive patterns. We also modified the internal cues using drug treatments, which modified the protrusion activity. Stochasticity affects the short- and long-term steps. We developed a theoretical model showing that an asymmetry in the protrusion fluctuations is sufficient for predicting all measures associated with the long-term motion, which can be described as a biased persistent random walk. PMID:24988339

  20. Entropic fluctuations in DNA sequences

    Science.gov (United States)

    Thanos, Dimitrios; Li, Wentian; Provata, Astero

    2018-03-01

    The Local Shannon Entropy (LSE) in blocks is used as a complexity measure to study the information fluctuations along DNA sequences. The LSE of a DNA block maps the local base arrangement information to a single numerical value. It is shown that despite this reduction of information, LSE allows to extract meaningful information related to the detection of repetitive sequences in whole chromosomes and is useful in finding evolutionary differences between organisms. More specifically, large regions of tandem repeats, such as centromeres, can be detected based on their low LSE fluctuations along the chromosome. Furthermore, an empirical investigation of the appropriate block sizes is provided and the relationship of LSE properties with the structure of the underlying repetitive units is revealed by using both computational and mathematical methods. Sequence similarity between the genomic DNA of closely related species also leads to similar LSE values at the orthologous regions. As an application, the LSE covariance function is used to measure the evolutionary distance between several primate genomes.

  1. Consistency of detrended fluctuation analysis

    Science.gov (United States)

    Løvsletten, O.

    2017-07-01

    The scaling function F (s ) in detrended fluctuation analysis (DFA) scales as F (s ) ˜sH for stochastic processes with Hurst exponent H . This scaling law is proven for stationary stochastic processes with 0 DFA is equal in expectation to (i) a weighted sum of the ACF and (ii) a weighted sum of the second-order structure function. These results enable us to compute the exact finite-size bias for signals that are scaling and to employ DFA in a meaningful sense for signals that do not exhibit power-law statistics. The usefulness is illustrated by examples where it is demonstrated that a previous suggested modified DFA will increase the bias for signals with Hurst exponents 1 application of these developments, an estimator F ̂(s ) is proposed. This estimator can handle missing data in regularly sampled time series without the need of interpolation schemes. Under mild regularity conditions, F ̂(s ) is equal in expectation to the fluctuation function F (s ) in the gap-free case.

  2. Differential pressure gauge has fast response

    Science.gov (United States)

    Weber, H. S.

    1965-01-01

    Differential pressure gage with semiconductor type strain gage elements measures rapidly changing pressure. Output of the strain gage elements is a dc voltage that is directly proportional to the pressure difference being measured.

  3. Transverse Momentum Fluctuations in Nuclear Collisions at 158 AGeV

    CERN Document Server

    Anticic, T.; Barna, D.; Bartke, J.; Behler, M.; Betev, L.; Bialkowska, H.; Billmeier, A.; Blume, C.; Boimska, B.; Botje, M.; Bracinik, J.; Bramm, R.; Brun, R.; Buncic, P.; Cerny, V.; Christakoglou, P.; Chvala, O.; Cramer, J.G.; Csato, P.; Darmenov, N.; Dimitrov, A.; Dinkelaker, P.; Eckardt, V.; Filip, P.; Flierl, D.; Fodor, Z.; Foka, P.; Freund, P.; Friese, V.; Gal, J.; Gazdzicki, M.; Georgopoulos, G.; Gladysz, E.; Hegyi, S.; Hohne, C.; Kadija, K.; Karev, A.; Kolesnikov, V.I.; Kollegger, T.; Korus, R.; Kowalski, M.; Kraus, I.; Kreps, M.; van Leeuwen, M.; Levai, P.; Litov, L.; Makariev, M.; Malakhov, A.I.; Markert, C.; Mateev, M.; Mayes, B.W.; Melkumov, G.L.; Meurer, C.; Mischke, A.; Mitrovski, M.; Molnar, J.; Mrowczynski, S.; Palla, G.; Panagiotou, A.D.; Panayotov, D.; Perl, K.; Petridis, A.; Pikna, M.; Pinsky, Lawrence S.; Puhlhofer, F.; Reid, J.G.; Renfordt, R.; Retyk, W.; Roland, C.; Roland, G.; Rybczynski, M.; Rybicki, A.; Sandoval, A.; Sann, H.; Schmitz, N.; Seyboth, P.; Sikler, F.; Sitar, B.; Skrzypczak, E.; Stefanek, G.; Stock, R.; Strobele, H.; Susa, T.; Szentpetery, I.; Sziklai, J.; Trainor, T.A.; Varga, D.; Vassiliou, M.; Veres, G.I.; Vesztergombi, G.; Vranic, D.; Wetzler, A.; Wlodarczyk, Z.; Yoo, I.K.; Zaranek, J.; Zimanyi, J.

    2004-01-01

    Results are presented on event-by-event fluctuations in transverse momentum of charged particles, produced at forward rapidities in p+p, C+C, Si+Si and Pb+Pb collisions at 158 AGeV. Three different characteristics are discussed: the average transverse momentum of the event, the Phi_pT fluctuation measure and two-particle transverse momentum correlations. In the kinematic region explored, the dynamical fluctuations are found to be small. However, a significant system size dependence of Phi_pT is observed, with the largest value measured in peripheral Pb+Pb interactions. The data are compared with predictions of several models.

  4. Wall shear stress fluctuations: Mixed scaling and their effects on velocity fluctuations in a turbulent boundary layer

    Science.gov (United States)

    Diaz-Daniel, Carlos; Laizet, Sylvain; Vassilicos, J. Christos

    2017-05-01

    The present work investigates numerically the statistics of the wall shear stress fluctuations in a turbulent boundary layer (TBL) and their relation to the velocity fluctuations outside of the near-wall region. The flow data are obtained from a Direct Numerical Simulation (DNS) of a zero pressure-gradient TBL using the high-order flow solver Incompact3D [S. Laizet and E. Lamballais, "High-order compact schemes for incompressible flows: A simple and efficient method with quasi-spectral accuracy," J. Comput. Phys. 228(16), 5989 (2009)]. The maximum Reynolds number of the simulation is R e𝜃≈2000 , based on the free-stream velocity and the momentum thickness of the boundary layer. The simulation data suggest that the root-mean-squared fluctuations of the streamwise and spanwise wall shear-stress components τx and τz follow a logarithmic dependence on the Reynolds number, consistent with the empirical correlation of Örlü and Schlatter [R. Örlü and P. Schlatter, "On the fluctuating wall-shear stress in zero pressure-gradient turbulent boundary layer flows," Phys. Fluids 23, 021704 (2011)]. These functional dependencies can be used to estimate the Reynolds number dependence of the wall turbulence dissipation rate in good agreement with reference DNS data. Our results suggest that the rare negative events of τx can be associated with the extreme values of τz and are related to the presence of coherent structures in the buffer layer, mainly quasi-streamwise vortices. We also develop a theoretical model, based on a generalisation of the Townsend-Perry hypothesis of wall-attached eddies, to link the statistical moments of the filtered wall shear stress fluctuations and the second order structure function of fluctuating velocities at a distance y from the wall. This model suggests that the wall shear stress fluctuations may induce a higher slope in the turbulence energy spectra of streamwise velocities than the one predicted by the Townsend-Perry attached

  5. Fluctuations in plasma oestradiol levels in normal men.

    Science.gov (United States)

    Kicóvíc, P M; Luisi, M; Cortés-Prieto, J; Franchi, F

    1980-01-01

    Plasma levels of oestradiol were measured in blood samples obtained from 6 normal men every 12 minutes for two 4-hour periods: between 08.00 and 12.00h and between 18.00 and 22.00h. Circulating oestradiol was measured by radioimmunoassay after chromatographic separation on microcolumns of Sephadex LH-20. Mean values of oestradiol concentrations and coefficients of variation for two 4-hour periods were calculated for each subject and for the whole group. Data were statistically evaluated by means of the Wilcoxon signed-rank test. Rapid fluctuations in plasma oestradiol levels were observed in all subjects. The pattern of the fluctuations was found to be irregular and different in each subject. The mean concentration and coefficient of variation were significantly (p less than 0.05) higher in the morning, suggesting the possibility of a circadian rhythm in the secretion of oestradiol in men.

  6. Vacuum Fluctuations, Cosmogenesis and Prime Number Gaps

    Science.gov (United States)

    Berezin, Alexander A.

    2002-10-01

    Starting from E.Tryon (1973), idea of cosmogenesis through quantum tunnelling "from nothing" became popular. Both complimentary streams of it, inflationary models (Guth, Linde) and quantum parallelism (Everett, Deutsch), require some starting point as, e.g., concretisation of Leibnitz Principle (Omnibus ex nihil decendis sufficit unum). This leads to propositional conjecture (axiom?) that (meta)physical "Platonic Pressure" of infinitude of numbers and Cantor "alephs" becomes an engine for self-generation of physical universe directly out of mathematics: inexhaustibility of Number Theory (NT) drives cosmogenesis. While physics in other quantum branches of inflating universe (Megaverse) can be (arbitrary) different from ours, NT is not (it is unique, absolute, immutable and infinitely resourceful). Energy-time uncertainty principle (UP) allows indefinite lifetime provided we start from total zero energy. Analogue of UP in NT is theorem by H.Maier (1981) stating the existence of arbitrary long trails of isolated primes such that each next gap is arbitrary greater than average gap (logN). On physical level these arbitrary large deviations from Prime Number Theorem translate into permissiveness of (arbitrary) large quantum fluctuations.

  7. Detecting IOP Fluctuations in Glaucoma Patients.

    Science.gov (United States)

    Nuyen, Brenda; Mansouri, Kaweh

    2016-01-01

    Lowering intraocular pressure (IOP) remains the guiding principle of glaucoma management. Although IOP is the only treatable risk factor, its 24-hour behavior is poorly understood. Current glaucoma management usually relies on single IOP measurements during clinic hours, even though IOP is a dynamic parameter with rhythms dependent on individual patients. It has further been shown that most glaucoma patients have their highest IOP measurements outside clinic hours. The fact that these IOP peaks go largely undetected may explain why certain patients progress in their disease despite treatment. Nevertheless, single IOP measurements have determined all major clinical guidelines regarding glaucoma treatment. Other potentially informative parameters, such as fluctuations in IOP and peak IOP, have been neglected, and effects of IOP-lowering interventions on such measures are largely unknown. Continuous 24-hour IOP monitoring has been an interest for more than 50 years, but only recent technological advances have provided clinicians with a device for such an endeavor. This review discusses current uses and shortcomings of current measurement techniques, and provides an overview on current and future methods for 24-hour IOP assessment. It may be possible to incorporate continuous IOP monitoring into clinical practice, potentially to reduce glaucoma-related vision loss.

  8. Fluctuations and transport in the TCV scrape-off layer

    DEFF Research Database (Denmark)

    Garcia, Odd Erik; Horacek, J.; Pitts, R.A.

    2007-01-01

    at the outer midplane scales linearly with the local particle density, suggesting that the particle flux here can be parameterized in terms of an effective convection velocity. Experimental probe measurements also provide evidence for significant parallel flows in the scrape-off layer caused by ballooning...... in the transport of particles and heat into the scrape-off layer. The magnitude of this flow estimated from pressure fluctuation statistics is found to compare favourably with the measured flow offset derived by averaging data obtained from flow profiles observed in matched forward and reversed field discharges....... An interchange turbulence simulation has been performed for a single, relatively high density case, where comparison between code and experiment has been possible. Good agreement is found for almost all aspects of the experimental measurements, indicating that plasma fluctuations and transport in TCV scrape...

  9. Bet Hedging against Demographic Fluctuations

    Science.gov (United States)

    Xue, BingKan; Leibler, Stanislas

    2017-09-01

    Biological organisms have to cope with stochastic variations in both the external environment and the internal population dynamics. Theoretical studies and laboratory experiments suggest that population diversification could be an effective bet-hedging strategy for adaptation to varying environments. Here we show that bet hedging can also be effective against demographic fluctuations that pose a trade-off between growth and survival for populations even in a constant environment. A species can maximize its overall abundance in the long term by diversifying into coexisting subpopulations of both "fast-growing" and "better-surviving" individuals. Our model generalizes statistical physics models of birth-death processes to incorporate dispersal, during which new populations are founded, and can further incorporate variations of local environments. In this way, we unify different bet-hedging strategies against demographic and environmental variations as a general means of adaptation to both types of uncertainties in population growth.

  10. Glacial greenhouse-gas fluctuations controlled by ocean circulation changes.

    Science.gov (United States)

    Schmittner, Andreas; Galbraith, Eric D

    2008-11-20

    Earth's climate and the concentrations of the atmospheric greenhouse gases carbon dioxide (CO(2)) and nitrous oxide (N(2)O) varied strongly on millennial timescales during past glacial periods. Large and rapid warming events in Greenland and the North Atlantic were followed by more gradual cooling, and are highly correlated with fluctuations of N(2)O as recorded in ice cores. Antarctic temperature variations, on the other hand, were smaller and more gradual, showed warming during the Greenland cold phase and cooling while the North Atlantic was warm, and were highly correlated with fluctuations in CO(2). Abrupt changes in the Atlantic meridional overturning circulation (AMOC) have often been invoked to explain the physical characteristics of these Dansgaard-Oeschger climate oscillations, but the mechanisms for the greenhouse-gas variations and their linkage to the AMOC have remained unclear. Here we present simulations with a coupled model of glacial climate and biogeochemical cycles, forced only with changes in the AMOC. The model simultaneously reproduces characteristic features of the Dansgaard-Oeschger temperature, as well as CO(2) and N(2)O fluctuations. Despite significant changes in the land carbon inventory, CO(2) variations on millennial timescales are dominated by slow changes in the deep ocean inventory of biologically sequestered carbon and are correlated with Antarctic temperature and Southern Ocean stratification. In contrast, N(2)O co-varies more rapidly with Greenland temperatures owing to fast adjustments of the thermocline oxygen budget. These results suggest that ocean circulation changes were the primary mechanism that drove glacial CO(2) and N(2)O fluctuations on millennial timescales.

  11. Fluctuations in strongly coupled cosmologies

    Energy Technology Data Exchange (ETDEWEB)

    Bonometto, Silvio A. [Department of Physics, Astronomy Unit, Trieste University, Via Tiepolo 11, I 34143 Trieste (Italy); Mainini, Roberto, E-mail: bonometto@oats.inaf.it, E-mail: mainini@mib.infn.it [Department of Physics G. Occhialini, Milano-Bicocca University, Piazza della Scienza 3, I 20126 Milano (Italy)

    2014-03-01

    In the early Universe, a dual component made of coupled CDM and a scalar field Φ, if their coupling β > (3){sup 1/2}/2, owns an attractor solution, making them a stationary fraction of cosmic energy during the radiation dominated era. Along the attractor, both such components expand ∝a{sup −4} and have early density parameters Ω{sub d} = 1/(4β{sup 2}) and Ω{sub c} = 2 Ω{sub d} (field and CDM, respectively). In a previous paper it was shown that, if a further component, expanding ∝a{sup −3}, breaks such stationary expansion at z ∼ 3–5 × 10{sup 3}, cosmic components gradually acquire densities consistent with observations. This paper, first of all, considers the case that this component is warm. However, its main topic is the analysis of fluctuation evolution: out of horizon modes are then determined; their entry into horizon is numerically evaluated as well as the dependence of Meszaros effect on the coupling β; finally, we compute: (i) transfer function and linear spectral function; (ii) CMB C{sub l} spectra. Both are close to standard ΛCDM models; in particular, the former one can be so down to a scale smaller than Milky Way, in spite of its main DM component being made of particles of mass < 1 keV. The previously coupled CDM component, whose present density parameter is O(10{sup −3}), exhibits wider fluctuations δρ/ρ, but approximately β-independent δρ values. We discuss how lower scale features of these cosmologies might ease quite a few problems that ΛCDM does not easily solve.

  12. The infinite line pressure probe

    Science.gov (United States)

    Englund, D. R.; Richards, W. B.

    1985-01-01

    The infinite line pressure probe provides a means for measuring high frequency fluctuating pressures in difficult environments. A properly designed infinite line probe does not resonate; thus its frequency response is not limited by acoustic resonance in the probe tubing, as in conventional probes. The characteristics of infinite line pressure probes are reviewed and some applications in turbine engine research are described. A probe with a flat-oval cross section, permitting a constant-impedance pressure transducer installation, is described. Techniques for predicting the frequency response of probes with both circular and flat-oval cross sections are also cited.

  13. 24-hour intraocular pressure and ocular perfusion pressure in glaucoma.

    Science.gov (United States)

    Quaranta, Luciano; Katsanos, Andreas; Russo, Andrea; Riva, Ivano

    2013-01-01

    This review analyzes the currently available literature on circadian rhythms of intraocular pressure (IOP), blood pressure, and calculated ocular perfusion pressure (OPP) in patients with open-angle glaucoma. Although adequately powered, prospective trials are not available. The existing evidence suggests that high 24-hour IOP and OPP fluctuations can have detrimental effects in eyes with glaucoma. The currently emerging continuous IOP monitoring technologies may soon offer important contributions to the study of IOP rhythms. Once telemetric technologies become validated and widely available for clinical use, they may provide an important tool towards a better understanding of long- and short-term IOP fluctuations during a patient's daily routine. Important issues that need to be investigated further include the identification of appropriate surrogate measures of IOP and OPP fluctuation for patients unable to undergo 24-hour measurements, the determination of formulae that best describe the relationship between systemic blood pressure and IOP with OPP, and the exact clinical relevance of IOP and OPP fluctuation in individual patients. Despite the unanswered questions, a significant body of literature suggests that OPP assessment may be clinically relevant in a significant number of glaucoma patients. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Wind fluctuations over the North Sea

    DEFF Research Database (Denmark)

    Vincent, Claire Louise; Pinson, Pierre; Giebel, Gregor

    2011-01-01

    Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms. The Hil......Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms...

  15. Reconstruction of brachial pressure from finger arterial pressure during orthostasis

    DEFF Research Database (Denmark)

    Bogert, Lysander W J; Harms, Mark P M; Pott, Frank

    2004-01-01

    In patients with recurrent syncope, monitoring of intra-arterial pressure during orthostatic stress testing is recommended because of the potentially sudden and rapid development of hypotension. Replacing brachial arterial pressure (BAP) by the non-invasively obtained finger arterial pressure (Fin...

  16. Rapid response manufacturing (RRM)

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)

    1997-02-18

    US industry is fighting to maintain its competitive edge in the global market place. Today markets fluctuate rapidly. Companies, to survive, have to be able to respond with quick-to-market, improved, high quality, cost efficient products. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies. The RRM project was established to leverage the expertise and resources of US private industries and federal agencies to develop, integrate, and deploy new technologies that meet critical needs for effective product realization. The RRM program addressed a needed change in the US Manufacturing infrastructure that will ensure US competitiveness in world market typified by mass customization. This project provided the effort needed to define, develop and establish a customizable infrastructure for rapid response product development design and manufacturing. A major project achievement was the development of a broad-based framework for automating and integrating the product and process design and manufacturing activities involved with machined parts. This was accomplished by coordinating and extending the application of feature-based product modeling, knowledge-based systems, integrated data management, and direct manufacturing technologies in a cooperative integrated computing environment. Key technological advancements include a product model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering environment, knowledge-based software aids for design and process planning, and new production technologies to make products directly from design application software.

  17. Fluctuations in Urban Traffic Networks

    Science.gov (United States)

    Chen, Yu-Dong; Li, Li; Zhang, Yi; Hu, Jian-Ming; Jin, Xue-Xiang

    Urban traffic network is a typical complex system, in which movements of tremendous microscopic traffic participants (pedestrians, bicyclists and vehicles) form complicated spatial and temporal dynamics. We collected flow volumes data on the time-dependent activity of a typical urban traffic network, finding that the coupling between the average flux and the fluctuation on individual links obeys a certain scaling law, with a wide variety of scaling exponents between 1/2 and 1. These scaling phenomena can explain the interaction between the nodes' internal dynamics (i.e. queuing at intersections, car-following in driving) and changes in the external (network-wide) traffic demand (i.e. the every day increase of traffic amount during peak hours and shocking caused by traffic accidents), allowing us to further understand the mechanisms governing the transportation system's collective behavior. Multiscaling and hotspot features are observed in the traffic flow data as well. But the reason why the separated internal dynamics are comparable to the external dynamics in magnitude is still unclear and needs further investigations.

  18. Wave Beam Propagation Through Density Fluctuations

    NARCIS (Netherlands)

    Balakin, A. A.; Bertelli, N.; Westerhof, E.

    2011-01-01

    Perturbations induced by edge density fluctuations on electron cyclotron wave beams propagating in fusion plasmas are studied by means of a quasi-optical code. The effects of such fluctuations are illustrated here by showing the beam propagation in the case of single harmonic perturbations to the

  19. temperature fluctuation inside inert atmosphere silos

    African Journals Online (AJOL)

    This research was conducted to study temperature fluctuation inside the inert atmosphere silos loaded with wheat, compare the temperature fluctuation across the top, middle and bottom part of the silo in relation to the ambient temperature. Temperature readings of the ambient and at the top, middle and bottom part of the ...

  20. Nonconformal Fluctuations in Radiation Dominated Anisotropic ...

    Indian Academy of Sciences (India)

    tribpo

    the non-conformal quantum fluctuations (of expansion and shear) and axisymmetric singularity case in radiation dominated anisotropic cosmology. We show that near the classical singularity the quantum fluctuations tend to diverge. Key words. Quantum Cosmology—Anisotropic universes. 1. Introduction. It has been ...

  1. Pairing fluctuations in trapped Fermi gases

    DEFF Research Database (Denmark)

    Bruun, Georg Morten; Minguzzi, Anna; Rosario, F.

    2004-01-01

    A0530F- Fermion-systems-and-electron-gas-quantum-statistical-mechanics; A0540-Fluctuation-phenomena-random-processes-and-Brownian-motion......A0530F- Fermion-systems-and-electron-gas-quantum-statistical-mechanics; A0540-Fluctuation-phenomena-random-processes-and-Brownian-motion...

  2. A data set of worldwide glacier fluctuations

    NARCIS (Netherlands)

    Leclercq, P.W.|info:eu-repo/dai/nl/339579951; Oerlemans, J.|info:eu-repo/dai/nl/06833656X; Basagic, H.J.; Bushueva, I.; Cook, A.J.; Le Bris, R.

    2014-01-01

    Glacier fluctuations contribute to variations in sea level and historical glacier length fluctuations are natural indicators of past climate change. To study these subjects, longterm information of glacier change is needed. In this paper we present a data set of global long-term glacier length

  3. The Spectrum of Wind Power Fluctuations

    Science.gov (United States)

    Bandi, Mahesh

    2016-11-01

    Wind is a variable energy source whose fluctuations threaten electrical grid stability and complicate dynamical load balancing. The power generated by a wind turbine fluctuates due to the variable wind speed that blows past the turbine. Indeed, the spectrum of wind power fluctuations is widely believed to reflect the Kolmogorov spectrum; both vary with frequency f as f - 5 / 3. This variability decreases when aggregate power fluctuations from geographically distributed wind farms are averaged at the grid via a mechanism known as geographic smoothing. Neither the f - 5 / 3 wind power fluctuation spectrum nor the mechanism of geographic smoothing are understood. In this work, we explain the wind power fluctuation spectrum from the turbine through grid scales. The f - 5 / 3 wind power fluctuation spectrum results from the largest length scales of atmospheric turbulence of order 200 km influencing the small scales where individual turbines operate. This long-range influence spatially couples geographically distributed wind farms and synchronizes farm outputs over a range of frequencies and decreases with increasing inter-farm distance. Consequently, aggregate grid-scale power fluctuations remain correlated, and are smoothed until they reach a limiting f - 7 / 3 spectrum. This work was funded by the Collective Interactions Unit, OIST Graduate University, Japan.

  4. Response of Fusarium solani to Fluctuating Temperatures

    Science.gov (United States)

    Keith F. Jensen; Phillip E. Reynolds; Phillip E. Reynolds

    1971-01-01

    The purpose of this study was to measure growth under a range of constant temperatures and under a series of fluctuating temperature regimes, and to determine if growth in the fluctuating temperiture regimes could be predicted satisfactorily from the growth data collected in the constant temperature experiments. Growth was measured on both agar and liquid culture to...

  5. Seasonal fluctuations in photochemical efficiency of Symbiodinium ...

    African Journals Online (AJOL)

    A. formosa and P. verucosa responded significantly to seasonal fluctuation in both solar radiation and sea surface temperature by regulating their Symbiodinium cells densities and photochemical efficiencies except P. cylindrica. However, such seasonal fluctuations in these environmental parameters are not accompanied ...

  6. Multiplicity Distributions and Charged-neutral Fluctuations

    CERN Document Server

    Nayak, Tapan K.; Agnihotri, A.; Ahammed, Z.; Angelis, A.L.S.; Antonenko, V.; Arefev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Baldine, A.; Barabach, L.; Barlag, C.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bock, R.; Bohne, E.M.; Bucher, D.; Buijs, A.; Buis, E.J.; Busching, H.; Carlen, L.; Chalyshev, V.; Chattopadhyay, S.; Chenawi, K.E.; Cherbatchev, R.; Chujo, T.; Claussen, A.; Das, A.C.; Decowski, M.P.; Djordjadze, V.; Donni, P.; Doubovik, I.; Dubey, A.K.; Dutta Majumda, M.R.; Eliseev, S.; Enosawa, K.; Feldmann, H.; Foka, P.; Fokin, S.; Frolov, V.; Ganti, M.S.; Garpman, S.; Gavrishchuk, O.; Geurts, F.J.M.; Ghosh, T.K.; Glasow, R.; Gupta, S.K.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H.H.; Higuchi, R.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Kampert, K.H.; Karadjev, K.; Karpio, K.; Kato, S.; Kees, S.; Kim, H.; Kolb, B.W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kumar, V.; Kurata, M.; Kurita, K.; Kuzmin, N.; Langbein, I.; Lebedev, A.; Lee, Y.Y.; Lohner, H.; Mahapatra, D.P.; Manko, V.; Martin, M.; Maximov, A.; Mehdiyev, Rashid R.; Mgebrichvili, G.; Miake, Y.; Mikhalev, D.; Mishra, G.C.; Miyamoto, Y.; Mohanty, B.; Morrison, Douglas R.O.; Mukhopadhyay, D.S.; Myalkovski, V.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Neumaier, S.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nishimura, S.; Nomokov, P.; Nystrand, J.; Obenshain, F.E.; Oskarsson, A.; Otterlund, I.; Pachr, M.; Parfenov, A.; Pavliouk, S.; Peitzmann, T.; Petracek, V.; Plasil, F.; Purschke, M.L.; Raeven, B.; Rak, J.; Raniwala, R.; Raniwala, S.; Ramamurthy, V.S.; Rao, N.K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Rubio, J.M.; Sambyal, S.S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.R.; Shabratova, G.; Sibiriak, I.; Siemiarczuk, T.; Sinha, B.C.; Slavine, N.; Soderstrom, K.; Solomey, N.; Sood, G.; Sorensen, S.P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Stuken, D.; Sumbera, M.; Svensson, T.; Trivedi, M.D.; Tsvetkov, A.; Twenhofel, C.; Tykarski, L.; Urbahn, J.; van Eijndhoven, N.; van Heeringen, W.H.; van Nieuwenhuizen, G.J.; Vinogradov, A.; Viyogi, Y.P.; Vodopianov, A.S.; Voros, S.; Vos, M.A.; Wyslouch, B.; Yagi, K.; Yokota, Y.; Young, G.R.; Nayak, Tapan K.

    2001-01-01

    Results from the multiplicity distributions of inclusive photons and charged particles, scaling of particle multiplicities, event-by-event multiplicity fluctuations, and charged-neutral fluctuations in 158$\\cdot A$ GeV Pb+Pb collisions are presented and discussed. A scaling of charged particle multiplicity as $N_{part}^{1.07\\pm 0.05}$ and photons as $N_{part}^{1.12\\pm 0.03}$ have been observed, indicating violation of naive wounded nucleon model. The analysis of localized charged-neutral fluctuation indicates a model-independent demonstration of non-statistical fluctuations in both charged particles and photons in limited azimuthal regions. However, no correlated charged-neutral fluctuations are observed.

  7. Research on the Voltage Fluctuation Rules of Power System Containing Wind Farms

    Science.gov (United States)

    Chen, Yixi; Xu, Guchao; Ma, Gang; Li, Feng; Ju, Rong

    2017-05-01

    The global energy shortage and environmental problems have contributed to the rapid development of wind power. However, due to the randomness and volatility of wind power, large-scale access may cause voltage fluctuation in power grid. Therefore, the reactive power control of power system containing wind farms has become a hot research topic in recent years, in which finding key nodes of voltage fluctuation is a foundation work. In this paper, the power model of wind farm is established first. Then, the influence on nodes voltage when wind farms access simple power system is analysed, and promoted to complex power systems in order to reveal the fluctuation rules of nodes voltage, and to summarize the distribution characteristics of key nodes of voltage fluctuation, which can provide the basis for reactive power optimization. At last, the conclusions are verified by IEEE 30-node system.

  8. London penetration depth and thermal fluctuations in the sulphur hydride 203 K superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Talantsev, E.F.; Crump, W.P. [Robinson Research Institute, Victoria University of Wellington, Lower Hutt (New Zealand); Storey, J.G.; Tallon, J.L. [Robinson Research Institute, Victoria University of Wellington, Lower Hutt (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology, Lower Hutt (New Zealand)

    2017-03-15

    Recently, compressed H{sub 2}S has been shown to become superconducting at 203 K under a pressure of 155 GPa. One might expect fluctuations to dominate at such temperatures. Using the magnetisation critical current, we determine the ground-state London penetration depth, λ{sub 0} = 189 nm, and the superconducting energy gap, Δ{sub 0} = 27.8 meV, and find these parameters are similar to those of cuprate superconductors. We also determine the fluctuation temperature scale, T{sub fluc} = 1470 K, which shows that, unlike the cuprates, T{sub c} of the hydride is not limited by fluctuations. This is due to its three dimensionality and suggests the search for better superconductors should refocus on three-dimensional systems where the inevitable thermal fluctuations are less likely to reduce the observed T{sub c}. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Bridging the gap between event-by-event fluctuation measurements and theory predictions in relativistic nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Braun-Munzinger, P., E-mail: p.braun-munzinger@gsi.de [Extreme Matter Institute EMMI, GSI, Darmstadt (Germany); Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany); Rustamov, A., E-mail: a.rustamov@cern.ch [Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany); National Nuclear Research Center, Baku (Azerbaijan); Stachel, J., E-mail: stachel@physi.uni-heidelberg.de [Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany)

    2017-04-15

    We develop methods to deal with non-dynamical contributions to event-by-event fluctuation measurements of net-particle numbers in relativistic nuclear collisions. These contributions arise from impact parameter fluctuations and from the requirement of overall net-baryon number or net-charge conservation and may mask the dynamical fluctuations of interest, such as those due to critical endpoints in the QCD phase diagram. Within a model of independent particle sources we derive formulae for net-particle fluctuations and develop a rigorous approach to take into account contributions from participant fluctuations in realistic experimental environments and at any cumulant order. Interestingly, contributions from participant fluctuations to the second and third cumulants of net-baryon distributions are found to vanish at mid-rapidity for LHC energies while higher cumulants of even order are non-zero even when the net-baryon number at mid-rapidity is zero. At lower beam energies the effect of participant fluctuations increases and induces spurious higher moments. The necessary corrections become large and need to be carefully taken into account before comparison to theory. We also provide a procedure for selecting the optimal phase–space coverage of particles for fluctuation analyses and discuss quantitatively the necessary correction due to global charge conservation.

  10. Density fluctuations in lattice-Boltzmann simulations of multiphase fluids in a closed system

    Energy Technology Data Exchange (ETDEWEB)

    H. Basagaoglu; Paul Meakin

    2007-02-01

    A two-dimensional single component two-phase lattice Boltzmann model was used to simulate the Rayleigh-Taylor instability in a closed system. Spatiotemporally variable densities were generated by gravity acting on the fluid density. The density fluctuations were triggered by rapid changes in the fluid velocity induced by changes in the interface geometry and impact of the dense fluid on the rigid lower boundary of the computational domain. The ratio of the maximum density fluctuations to the maximum fluid velocity increased more rapidly at low velocities than at high velocities. The ratio of the maximum density fluctuations in the dense phase to its maximum velocity was on the order of the inverse of the sound speed. The solution became unstable when the density-based maximum local Knudsen number exceeded 0.13.

  11. Rapid Prototyping

    Science.gov (United States)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  12. Science in the Sandbox: Fluctuations, Friction and Instabilities

    Science.gov (United States)

    Behringer, Robert P.; Clement, Eric; Geng, Junfei; Kondic, Ljubinko; Metcalfe, Guy; Reydellet, Guillaume; Tennakoon, Sarath

    The study of granular materials is a novel and rapidly growing field. These materials are interest for a number of reasons, both practical and theoretical. They exhibit a rich of novel dyanamical states, and they exhibit 'phases'-solid, liquid, and gas-that resemble conventional thermodynamic phases. However, the presence of strong dissipation through friction and inelasticity places these systems well outside the usual class of systems that can be explained by equilibrium thermodynamics. Thus, there are important challenges to create new kinds of statistical physics and new analytical descriptions for the mean and fluctuating behavior of these materials. We explore recent work that focuses on several important issues. These include force propagation and fluctuations in static and driven systems. It is well known that forces propagate through granular structures along networks-force chains, whose structure is a function of history. It is much less clear how to describe this process, and even what kind of structures evolve in physical experiments. After a brief overview of the field, we consider models of force propagation and recent experiments to test these models. Among the latter are experiments that probe force profiles at the base of sandpiles, and experiments that determine the Green's function response to point perturbations in granular systems. We also explore the nature of force fluctuations in slowly evolving systems, particulary sheared granular systems. These can be very strong-with rms fluctuations in the force that are as strong as the mean force. Finally, we pursue the analogy between conventional phases of matter, where we particularly focus on the transition between fluid and solid granular states in the presence of sustained horizontal shaking.

  13. Fluctuating Asymmetry of Human Populations: A Review

    Directory of Open Access Journals (Sweden)

    John H. Graham

    2016-12-01

    Full Text Available Fluctuating asymmetry, the random deviation from perfect symmetry, is a widely used population-level index of developmental instability, developmental noise, and robustness. It reflects a population’s state of adaptation and genomic coadaptation. Here, we review the literature on fluctuating asymmetry of human populations. The most widely used bilateral traits include skeletal, dental, and facial dimensions; dermatoglyphic patterns and ridge counts; and facial shape. Each trait has its advantages and disadvantages, but results are most robust when multiple traits are combined into a composite index of fluctuating asymmetry (CFA. Both environmental (diet, climate, toxins and genetic (aneuploidy, heterozygosity, inbreeding stressors have been linked to population-level variation in fluctuating asymmetry. In general, these stressors increase average fluctuating asymmetry. Nevertheless, there have been many conflicting results, in part because (1 fluctuating asymmetry is a weak signal in a sea of noise; and (2 studies of human fluctuating asymmetry have not always followed best practices. The most serious concerns are insensitive asymmetry indices (correlation coefficient and coefficient of indetermination, inappropriate size scaling, unrecognized mixture distributions, inappropriate corrections for directional asymmetry, failure to use composite indices, and inattention to measurement error. Consequently, it is often difficult (or impossible to compare results across traits, and across studies.

  14. Continuous IOP fluctuation recording in normal tension glaucoma patients.

    Science.gov (United States)

    Pajic, Bojan; Pajic-Eggspuchler, Brigitte; Haefliger, Ivan

    2011-12-01

    Intraocular pressure (IOP) remains the only treatable risk factor of progressive glaucoma. Recently a device became available to continuously record IOP fluctuation in contrast to classical, discreet IOP measurements. To perform 24-h IOP fluctuation monitoring using a CE-marked silicone lens-embedded strain gauge sensor (SENSIMED Triggerfish) in five normal tension glaucoma patients in the presence and absence of anti-glaucomatous treatment and to show the clinical importance of this diagnostic tool. 24-h continuous IOP fluctuation monitoring was performed on two occasions separated by at least 6 weeks in each patient. In the control session patients were untreated or previous IOP-lowering medication was washed-out for at least 6 weeks. In the treatment session patients received IOP-lowering medication for at least 6 weeks. The continuous recordings were analyzed for differences between daytime and nighttime data and for repeatability over time. Furthermore, profiles recorded in each patient in treated and non-treated conditions were compared. Highly individual and repeatable profiles were obtained. Data recorded during daytime portions of the recordings showed higher coefficients of variation than nighttime data. Positive and significant linear slopes for the transition period from wake time to sleep time were detected in all patients in the absence of anti-glaucomatous treatment, while in three patients of five no significant slopes were detected under treated conditions. Our data suggest that the continuous IOP fluctuation monitoring device is sensitive to individual IOP rhythms and to differences in such rhythms due to anti-glaucomatous drug therapy.

  15. Plasma β Scaling of Anisotropic Magnetic Field Fluctuations in the Solar Wind Flux Tube

    Science.gov (United States)

    Sarkar, Aveek; Bhattacharjee, Amitava; Ebrahimi, Fatima

    2014-03-01

    Based on various observations, it has been suggested that at 1 AU, solar wind consists of "spaghetti"-like magnetic field structures that have the magnetic topology of flux tubes. It is also observed that the plasma fluctuation spectra at 1 AU show a plasma β dependence. Reconciling these two sets of observations and using the Invariance Principle, Bhattacharjee et al. suggested that the plasma inside every flux tube may become unstable with respect to pressure-driven instabilities and gives rise to fluctuation spectra that depend on the local plasma β. The present work is the first direct numerical simulation of such a flux tube. We solve the full magnetohydrodynamic equations using the DEBS code and show that if the plasma inside the flux tube is driven unstable by spatial inhomogeneities in the background plasma pressure, the observed nature of the fluctuating power spectra agrees reasonably well with observations, as well as the analytical prediction of Bhattacharjee et al.

  16. Plasma β scaling of anisotropic magnetic field fluctuations in the solar wind flux tube

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Aveek [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Bhattacharjee, Amitava; Ebrahimi, Fatima, E-mail: aveek.sarkar@unh.edu, E-mail: amitava@princeton.edu, E-mail: ebrahimi@princeton.edu [Department of Astrophysical Sciences and Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States)

    2014-03-10

    Based on various observations, it has been suggested that at 1 AU, solar wind consists of 'spaghetti'-like magnetic field structures that have the magnetic topology of flux tubes. It is also observed that the plasma fluctuation spectra at 1 AU show a plasma β dependence. Reconciling these two sets of observations and using the Invariance Principle, Bhattacharjee et al. suggested that the plasma inside every flux tube may become unstable with respect to pressure-driven instabilities and gives rise to fluctuation spectra that depend on the local plasma β. The present work is the first direct numerical simulation of such a flux tube. We solve the full magnetohydrodynamic equations using the DEBS code and show that if the plasma inside the flux tube is driven unstable by spatial inhomogeneities in the background plasma pressure, the observed nature of the fluctuating power spectra agrees reasonably well with observations, as well as the analytical prediction of Bhattacharjee et al.

  17. Volcanoes drive climate variability by emitting ozone weeks before eruptions, by forming lower stratospheric aerosols, by causing sustained ozone depletion, and by causing rapid changes in regional ozone concentrations affecting temperature and pressure differences driving atmospheric oscillations

    Science.gov (United States)

    Ward, P. L.

    2016-12-01

    Total column ozone observed by satellite on February 19, 2010, increased 75% in a plume from Eyjafjallajökull volcano in southern Iceland eastward past Novaya Zemlya, extending laterally from northern Greenland to southern Norway (http://youtu.be/wJFZcPEfoR4). Contemporaneous ground deformation and rapidly increasing numbers of earthquakes imply magma began rising from a sill 4-6 km below the volcano, erupting a month later. Whether the ozone formed from the magma or from very hot gases rising through cracks in the ground is unclear. On February 20-22, 1991, similar increases in ozone were observed north of Pinatubo volcano before its initial eruption on April 2 (http://youtu.be/5y1PU2Qu3ag). Annual average total column ozone during the year of most moderate to large explosive volcanic eruptions since routine observations of ozone began in 1927 has been substantially higher than normal. Increased total column ozone absorbs more solar ultraviolet-B radiation, warming the ozone layer and cooling Earth. Most major volcanic eruptions form sulfuric-acid aerosols in the lower part of the ozone layer providing aqueous surfaces on which heterogeneous chemical reactions enhance ozone depletion. Within a year, aerosol droplets grew large enough to reflect and scatter high-frequency solar radiation, cooling Earth 0.5oC for 2-3 years. Temperature anomalies in the northern hemisphere rose 0.7oC in 28 years from 1970 to 1998 (HadCRUT4), while annual average ozone at Arosa dropped 27 DU because of manufactured CFC gases. Beginning in August 2014, temperature anomalies in the northern hemisphere rose another 0.6oC in less than two years apparently because of the 6-month eruption of Bárðarbunga volcano in central Iceland, the highest rate of basaltic lava extrusion since 1783. Large extrusions of basaltic lava are typically contemporaneous with the greatest periods of warming throughout Earth history. Ozone concentrations at Arosa change by season typically from 370 DU during

  18. Spin-fluctuation theory beyond Gaussian approximation

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, N B [Moscow State University, 119992 Moscow (Russian Federation); Reser, B I; Grebennikov, V I, E-mail: melnikov@cs.msu.s, E-mail: reser@imp.uran.r, E-mail: greben@imp.uran.r [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg (Russian Federation)

    2010-05-14

    A characteristic feature of the Gaussian approximation in the functional-integral approach to the spin-fluctuation theory is the jump phase transition to the paramagnetic state. We eliminate the jump and obtain a continuous second-order phase transition by taking into account high-order terms in the expansion of the free energy in powers of the fluctuating exchange field. The third-order term of the free energy renormalizes the mean field, and the fourth-order term, responsible for the interaction of the fluctuations, renormalizes the spin susceptibility. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar.

  19. Fluctuation theorems for quantum master equations.

    Science.gov (United States)

    Esposito, Massimiliano; Mukamel, Shaul

    2006-04-01

    A quantum fluctuation theorem for a driven quantum subsystem interacting with its environment is derived based solely on the assumption that its reduced density matrix obeys a closed evolution equation--i.e., a quantum master equation (QME). Quantum trajectories and their associated entropy, heat, and work appear naturally by transforming the QME to a time-dependent Liouville space basis that diagonalizes the instantaneous reduced density matrix of the subsystem. A quantum integral fluctuation theorem, a steady-state fluctuation theorem, and the Jarzynski relation are derived in a similar way as for classical stochastic dynamics.

  20. Population Genetics with Fluctuating Population Sizes

    Science.gov (United States)

    Chotibut, Thiparat; Nelson, David R.

    2017-05-01

    Standard neutral population genetics theory with a strictly fixed population size has important limitations. An alternative model that allows independently fluctuating population sizes and reproduces the standard neutral evolution is reviewed. We then study a situation such that the competing species are neutral at the equilibrium population size but population size fluctuations nevertheless favor fixation of one species over the other. In this case, a separation of timescales emerges naturally and allows adiabatic elimination of a fast population size variable to deduce the fluctuation-induced selection dynamics near the equilibrium population size. The results highlight the incompleteness of the standard population genetics with a strictly fixed population size.

  1. Spin-current noise from fluctuation relations

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jong Soo [Institut de Fisica Interdisciplinària i Sistemes Complexos IFISC (UIB-CSIC), E-07122 Palma de Mallorca (Spain); Sánchez, David; López, Rosa [Institut de Fisica Interdisciplinària i Sistemes Complexos IFISC (UIB-CSIC), E-07122 Palma de Mallorca, Spain and Departement de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2013-12-04

    We present fluctuation relations that connect spin-polarized current and noise in mesoscopic conductors. In linear response, these relations are equivalent to the fluctuation-dissipation theorem that relates equilibrium current-current correlations to the linear conductance. More interestingly, in the weakly nonlinear regime of transport, these relations establish a connection between the leading-order rectification spin conductance, the spin noise susceptibility and the third cumulant of spin current fluctuations at equilibrium. Our results are valid even for systems in the presence of magnetic fields and coupled to ferromagnetic electrodes.

  2. Probability distribution of vertical longitudinal shear fluctuations.

    Science.gov (United States)

    Fichtl, G. H.

    1972-01-01

    This paper discusses some recent measurements of third and fourth moments of vertical differences (shears) of longitudinal velocity fluctuations obtained in unstable air at the NASA 150 m meteorological tower site at Cape Kennedy, Fla. Each set of measurements consisted of longitudinal velocity fluctuation time histories obtained at the 18, 30, 60, 90, 120 and 150 m levels, so that 15 wind-shear time histories were obtained from each set of measurements. It appears that the distribution function of the longitudinal wind fluctuations at two levels is not bivariate Gaussian. The implications of the results relative to the design and operation of aerospace vehicles are discussed.-

  3. Macroscopic realism of quantum work fluctuations

    Science.gov (United States)

    Blattmann, Ralf; Mølmer, Klaus

    2017-07-01

    We study the fluctuations of the work performed on a driven quantum system, defined as the difference between subsequent measurements of energy eigenvalues. These work fluctuations are governed by statistical theorems with similar expressions in classical and quantum physics. We show that we can distinguish quantum and classical work fluctuations, as the latter can be described by a macrorealistic theory and hence obey Leggett-Garg inequalities. We show that these inequalities are violated by quantum processes in a driven two-level system and in a harmonic oscillator subject to a squeezing transformation.

  4. Cascading of Fluctuations in Interdependent Energy Infrastructures. Gas-Grid Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lebedev, Vladimir [Russian Academy of Sciences (RAS), Moscow (Russian Federation). L.D. Landau Inst. for Theoretical Physics; Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-09-05

    The revolution of hydraulic fracturing has dramatically increased the supply and lowered the cost of natural gas in the United States driving an expansion of natural gas-fired generation capacity in many electrical grids. Unrelated to the natural gas expansion, lower capital costs and renewable portfolio standards are driving an expansion of intermittent renewable generation capacity such as wind and photovoltaic generation. These two changes may potentially combine to create new threats to the reliability of these interdependent energy infrastructures. Natural gas-fired generators are often used to balance the fluctuating output of wind generation. However, the time-varying output of these generators results in time-varying natural gas burn rates that impact the pressure in interstate transmission pipelines. Fluctuating pressure impacts the reliability of natural gas deliveries to those same generators and the safety of pipeline operations. We adopt a partial differential equation model of natural gas pipelines and use this model to explore the effect of intermittent wind generation on the fluctuations of pressure in natural gas pipelines. The mean square pressure fluctuations are found to grow linearly in time with points of maximum deviation occurring at the locations of flow reversals.

  5. Effects of sound level fluctuations on annoyance caused by aircraft-flyover noise

    Science.gov (United States)

    Mccurdy, D. A.

    1979-01-01

    A laboratory experiment was conducted to determine the effects of variations in the rate and magnitude of sound level fluctuations on the annoyance caused by aircraft-flyover noise. The effects of tonal content, noise duration, and sound pressure level on annoyance were also studied. An aircraft-noise synthesis system was used to synthesize 32 aircraft-flyover noise stimuli representing the factorial combinations of 2 tone conditions, 2 noise durations, 2 sound pressure levels, 2 level fluctuation rates, and 2 level fluctuation magnitudes. Thirty-two test subjects made annoyance judgements on a total of 64 stimuli in a subjective listening test facility simulating an outdoor acoustic environment. Variations in the rate and magnitude of level fluctuations were found to have little, if any, effect on annoyance. Tonal content, noise duration, sound pressure level, and the interaction of tonal content with sound pressure level were found to affect the judged annoyance significantly. The addition of tone corrections and/or duration corrections significantly improved the annoyance prediction ability of noise rating scales.

  6. temperature fluctuation inside inert atmosphere silos

    African Journals Online (AJOL)

    user

    This research was conducted to study temperature fluctuation inside the inert atmosphere silos loaded with wheat, compare ... gases most especially carbondioxide (CO2) is due to safety of ... even to agriculture and resistance of pests to some.

  7. Fluctuations, Environment, Mutations Accumulation and Ageing

    Science.gov (United States)

    Biecek, Przemysław; Cebrat, Stanisław

    We present a model of evolution of the age structured population based on the Monte Carlo method. We have assumed that the health status of an individual is described by variance of its fluctuations. Each expressed deleterious mutation increases the fluctuations. Additionally, the fluctuations of the environment are superimposed on the fluctuations of individuals in the population. An individual dies if the combination of both stochastic processes trespass the limit (level of homeostasis) set as the model parameter. The genes are switched on chronologically, what leads to accumulating defective genes expressed during the late periods of life in the genetic pool of the population. That results in the specific age structured population, in accordance with the predictions of Medawar's hypothesis of ageing and the results of the Penna model simulations. A decrease of the variation of the environmental noise increases the average expected lifespan of individuals.

  8. Fluctuations of Intensive Quantities in Statistical Thermodynamics

    Directory of Open Access Journals (Sweden)

    Artur E. Ruuge

    2013-11-01

    Full Text Available In phenomenological thermodynamics, the canonical coordinates of a physical system split in pairs, with each pair consisting of an extensive quantity and an intensive one. In the present paper, the quasithermodynamic fluctuation theory of a model system of a large number of oscillators is extended to statistical thermodynamics based on the idea of perceiving the fluctuations of intensive variables as the fluctuations of specific extensive ones in a “thermodynamically dual” system. The extension is motivated by the symmetry of the problem in the context of an analogy with quantum mechanics, which is stated in terms of a generalized Pauli problem for the thermodynamic fluctuations. The doubled Boltzmann constant divided by the number of particles plays a similar role as the Planck constant.

  9. A stochastic model of river discharge fluctuations

    Science.gov (United States)

    Livina, V.; Ashkenazy, Y.; Kizner, Z.; Strygin, V.; Bunde, A.; Havlin, S.

    2003-12-01

    We study the daily river flow fluctuations of 30 international rivers. Using the detrended fluctuation analysis, we study the correlations in the magnitudes of river flow increments (volatilities), and find power-law correlations in volatilities for time scales less than 1 year; these correlations almost disappear for time scales larger than 1 year. Using surrogate data test for nonlinearity, we show that correlations in the magnitudes of river flow fluctuations are a measure for nonlinearity. We propose a simple nonlinear stochastic model for river flow fluctuations that reproduces the main scaling properties of the river flow series as well as the correlations and periodicities in the magnitudes of river flow increments. According to our model, the source of nonlinearity observed in the data is an interaction between a long-term correlated process and the river discharge itself.

  10. Fluctuating Asymmetry: Methods, Theory, and Applications

    Directory of Open Access Journals (Sweden)

    John H. Graham

    2010-03-01

    Full Text Available Fluctuating asymmetry consists of random deviations from perfect symmetry in populations of organisms. It is a measure of developmental noise, which reflects a population’s average state of adaptation and coadaptation. Moreover, it increases under both environmental and genetic stress, though responses are often inconsistent. Researchers base studies of fluctuating asymmetry upon deviations from bilateral, radial, rotational, dihedral, translational, helical, and fractal symmetries. Here, we review old and new methods of measuring fluctuating asymmetry, including measures of dispersion, landmark methods for shape asymmetry, and continuous symmetry measures. We also review the theory, developmental origins, and applications of fluctuating asymmetry, and attempt to explain conflicting results. In the process, we present examples from the literature, and from our own research at “Evolution Canyon” and elsewhere.

  11. Fluctuation Diamagnetism in Two-Band Superconductors

    OpenAIRE

    Adachi, Kyosuke; Ikeda, Ryusuke

    2016-01-01

    Anomalously large fluctuation diamagnetism around the superconducting critical temperature has been recently observed on iron selenide (FeSe) [S. Kasahara et al., unpublished]. This indicates that superconducting fluctuations (SCFs) play a more significant role in FeSe, which supposedly has two-band structure, than in the familiar single-band superconductors. Motivated by the data in FeSe, SCF-induced diamagnetism is examined in a two-band system, on the basis of a phenomenological approach w...

  12. Fluorescence fluctuation spectroscopy (FFS), part A

    CERN Document Server

    Tetin, Sergey

    2013-01-01

    This new volume of Methods in Enzymology continues the legacy of this premier serial by containing quality chapters authored by leaders in the field. This volume covers Fluorescence Fluctuation SpectroscopyContains chapters on such topics as Time-integrated fluorescence cumulant analysis, Pulsed Interleaved Excitation, and raster image correlation spectroscopy and number and brightness analysis.Continues the legacy of this premier serial with quality chapters authored by leaders in the fieldCovers fluorescence fluctuation spectroscopyContains chapte

  13. Quantum fluctuations of the superconducting cosmic string

    Science.gov (United States)

    Zhang, Shoucheng

    1987-01-01

    Quantum fluctuations of the proposed superconducting string with Bose charge carriers are studied in terms of the vortices on the string world sheet. In the thermodynamical limit, it is found that they appear in the form of free vortices rather than as bound pairs. This fluctuation mode violates the topological conservation law on which superconductivity is based. However, this limit may not be reached. The critical size of the superconducting string is estimated as a function of the coupling constants involved.

  14. Thermal Fluctuations in Electroweak Phase Transition

    Science.gov (United States)

    Shiromizu, T.; Morikawa, M.; Yokoyama, J.

    1995-11-01

    We estimate the amplitude of thermal fluctuations by calculating the typical size of subcritical bubbles in cosmological electroweak phase transition and show that this thermal fluctuation effect drastically changes dynamics of the phase transition from the ordinary first order type with supercooling. From this fact, we conclude that the standard electroweak baryogenesis scenario associated with such a first order transition does not work in the minimal standard model in certain conditions.

  15. Kink fluctuation asymptotics and zero modes

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, A.A. [Universidad de Salamanca, Departamento de Matematica Aplicada and IUFFyM, Salamanca (Spain); Guilarte, J.M. [Universidad de Salamanca, Departamento de Fisica Fundamental and IUFFyM, Salamanca (Spain)

    2012-10-15

    In this paper we propose a refinement of the heat-kernel/zeta function treatment of kink quantum fluctuations in scalar field theory, further analyzing the existence and implications of a zero-energy fluctuation mode. Improved understanding of the interplay between zero modes and the kink heat-kernel expansion delivers asymptotic estimations of one-loop kink mass shifts with remarkably higher precision than previously obtained by means of the standard Gilkey-DeWitt heat-kernel expansion. (orig.)

  16. Molecular thermodynamics using fluctuation solution theory

    DEFF Research Database (Denmark)

    Ellegaard, Martin Dela

    to relevant experimental data is limited. This thesis addresses the issue of generating and using simple thermodynamic models within a rigorous statistical mechanical framework, the so-called fluctuation solution theory, from which relations connecting properties and phase equilibria can be obtained....... The framework relates thermodynamic variables to molecular pair correlation functions of liquid mixtures. In this thesis, application of the framework is illustrated using two approaches: 1. Solubilities of solid solutes in mixed solvent systems are determined from fluctuation solution theory application...

  17. Semiclassical form factor of matrix element fluctuations

    CERN Document Server

    Eckhardt, B; Eckhardt, Bruno; Main, Joerg

    1995-01-01

    We analyze within a semiclassical approximation the form factor for the fluctuations of quantum matrix elements around their classical average. We find two contributions: one is proportional to the form factor for the density of states, with an amplitude determined by the squared average of the matrix elements. The other is constant and related to the fluctuations of finite time classical trajectory segments around the phase space average. The results are illustrated for an observable in the quadratic Zeeman effect.

  18. Hydrodynamic fluctuations in thermostatted multiparticle collision dynamics.

    Science.gov (United States)

    Híjar, Humberto; Sutmann, Godehard

    2011-04-01

    In this work we study the behavior of mesoscopic fluctuations of a fluid simulated by Multiparticle Collision Dynamics when this is applied together with a local thermostatting procedure that constrains the strength of temperature fluctuations. We consider procedures in which the thermostat interacts with the fluid at every simulation step as well as cases in which the thermostat is applied only at regular time intervals. Due to the application of the thermostat temperature fluctuations are forced to relax to equilibrium faster than they do in the nonthermostatted, constant-energy case. Depending on the interval of application of the thermostat, it is demonstrated that the thermodynamic state changes gradually from isothermal to adiabatic conditions. In order to exhibit this effect we compute from simulations diverse correlation functions of the hydrodynamic fluctuating fields. These correlation functions are compared with those predicted by a linearized hydrodynamic theory of a simple fluid in which a thermostat is applied locally. We find a good agreement between the model and the numerical results, which confirms that hydrodynamic fluctuations in Multiparticle Collision Dynamics in the presence of the thermostat have the properties expected for spontaneous fluctuations in fluids in contact with a heat reservoir.

  19. Multiscale temporal integrators for fluctuating hydrodynamics

    Science.gov (United States)

    Delong, Steven; Sun, Yifei; Griffith, Boyce E.; Vanden-Eijnden, Eric; Donev, Aleksandar

    2014-12-01

    Following on our previous work [S. Delong, B. E. Griffith, E. Vanden-Eijnden, and A. Donev, Phys. Rev. E 87, 033302 (2013), 10.1103/PhysRevE.87.033302], we develop temporal integrators for solving Langevin stochastic differential equations that arise in fluctuating hydrodynamics. Our simple predictor-corrector schemes add fluctuations to standard second-order deterministic solvers in a way that maintains second-order weak accuracy for linearized fluctuating hydrodynamics. We construct a general class of schemes and recommend two specific schemes: an explicit midpoint method and an implicit trapezoidal method. We also construct predictor-corrector methods for integrating the overdamped limit of systems of equations with a fast and slow variable in the limit of infinite separation of the fast and slow time scales. We propose using random finite differences to approximate some of the stochastic drift terms that arise because of the kinetic multiplicative noise in the limiting dynamics. We illustrate our integrators on two applications involving the development of giant nonequilibrium concentration fluctuations in diffusively mixing fluids. We first study the development of giant fluctuations in recent experiments performed in microgravity using an overdamped integrator. We then include the effects of gravity and find that we also need to include the effects of fluid inertia, which affects the dynamics of the concentration fluctuations greatly at small wave numbers.

  20. Net-Charge Fluctuations in Pb-Pb collisions at $\\sqrt{s_{NN}}= 2.76$ TeV

    CERN Document Server

    Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergognon, Anais Annick Erica; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Bock, Nicolas; Boettger, Stefan; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Boyer, Bruno Alexandre; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Busch, Oliver; Buthelezi, Edith Zinhle; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Sukalyan; Chattopadhyay, Subhasis; Chawla, Isha; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Colella, Domenico; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; D'Erasmo, Ginevra; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Kushal; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; de Rooij, Raoul Stefan; Delagrange, Hugues; Deloff, Andrzej; Demanov, Vyacheslav; Denes, Ervin; Deppman, Airton; Di Bari, Domenico; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erazmus, Barbara; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Fenton-Olsen, Bo; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Alessandro; Ferretti, Roberta; Festanti, Andrea; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Andrey; Ivanov, Marian; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacobs, Peter; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jha, Deeptanshu Manu; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jusko, Anton; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Mohisin Mohammed; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Dong Jo; Kim, Do Won; Kim, Jonghyun; Kim, Jin Sook; Kim, Minwoo; Kim, Mimae; Kim, Se Yong; Kim, Seon Hee; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Koch, Kathrin; Kohler, Markus; Kollegger, Thorsten; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kugathasan, Thanushan; Kuhn, Christian Claude; Kuijer, Paul; Kulakov, Igor; Kumar, Jitendra; Kurashvili, Podist; Kurepin, A; Kurepin, AB; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasily; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; Lazzeroni, Cristina; Le Bornec, Yves; Lea, Ramona; Lechman, Mateusz; Lee, Graham Richard; Lee, Ki Sang; Lee, Sung Chul; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lemmon, Roy Crawford; Lenti, Vito; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Leoncino, Marco; Levai, Peter; Lien, Jorgen; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Rongrong; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Mal'Kevich, Dmitry; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Marin Tobon, Cesar Augusto; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Niculescu, Mihai; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Oleniacz, Janusz; Oppedisano, Chiara; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, Susanta Kumar; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodrigues Fernandes Rabacal, Bartolomeu; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Sano, Satoshi; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selyuzhenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szostak, Artur Krzysztof; Szymanski, Maciej; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tarazona Martinez, Alfonso; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Toia, Alberica; Torii, Hisayuki; Tosello, Flavio; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; van Leeuwen, Marco; Vande Vyvre, Pierre; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; Øvrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Weber, Michael; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Alexander; Wilk, Grzegorz Andrzej; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo; Zyzak, Maksym

    2013-04-10

    We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudo-rapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the ALICE data points are between the theoretically predicted values for a hadron gas and a Quark-Gluon Plasma.

  1. Determination of humidity and temperature fluctuations based on MOZAIC data and parametrisation of persistent contrail coverage for general circulation models

    Directory of Open Access Journals (Sweden)

    K. M. Gierens

    1997-08-01

    Full Text Available Humidity and temperature fluctuations at pressure levels between 166 and 290 hPa on the grid scale of general circulation models for a region covered by the routes of airliners, mainly over the Atlantic, have been determined by evaluation of the data obtained with almost 2000 flights within the MOZAIC programme. It is found that the distributions of the fluctuations cannot be modelled by Gaussian distributions, because large fluctuations appear with a relatively high frequency. Lorentz distributions were used for the analytical representation of the fluctuation distributions. From these a joint probability distribution has been derived for simultaneous temperature and humidity fluctuations. This function together with the criteria for the formation and persistence of contrails are used to derive the maximum possible fractional coverage of persistent contrails in a grid cell of a GCM. This can be employed in a statistical formulation of contrail appearance in a climate model.

  2. Determination of humidity and temperature fluctuations based on MOZAIC data and parametrisation of persistent contrail coverage for general circulation models

    Directory of Open Access Journals (Sweden)

    K. M. Gierens

    Full Text Available Humidity and temperature fluctuations at pressure levels between 166 and 290 hPa on the grid scale of general circulation models for a region covered by the routes of airliners, mainly over the Atlantic, have been determined by evaluation of the data obtained with almost 2000 flights within the MOZAIC programme. It is found that the distributions of the fluctuations cannot be modelled by Gaussian distributions, because large fluctuations appear with a relatively high frequency. Lorentz distributions were used for the analytical representation of the fluctuation distributions. From these a joint probability distribution has been derived for simultaneous temperature and humidity fluctuations. This function together with the criteria for the formation and persistence of contrails are used to derive the maximum possible fractional coverage of persistent contrails in a grid cell of a GCM. This can be employed in a statistical formulation of contrail appearance in a climate model.

  3. Direct numerical simulation of expiratory crackles: Relationship between airway closure dynamics and acoustic fluctuations.

    Science.gov (United States)

    Ii, Satoshi; Wada, Shigeo

    2017-01-04

    This paper investigates the relationship between airway closure dynamics and acoustic fluctuations in expiratory crackles using direct numerical simulation. A unified mathematical model is proposed to deal with flow in an airway, elastic deformation of the airway wall, surface tension driven motion of the liquid film that lines the airway, and their acoustic fluctuations because of material compressibility. Airway closure is induced by increasing the surrounding pressure, then the source of the pressure fluctuations is measured over time. Our results show that the airway closure occurs suddenly because of a bridge formation of the liquid film, and high energy transfer occurs between the kinetic energy, the surface energy of the liquid interface, and the elastic energy of the airway wall, invoking a large acoustic fluctuation that causes the expiratory crackles. Nonlinear behavior is observed in terms of the airway wall stiffness; the dynamic motion of the airway closure becomes moderate and both the energy transfer and acoustic fluctuations are dramatically reduced with an increase in airway wall stiffness. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Studies of Fluctuation Processes in Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ayik, Sakir [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

    2016-04-14

    The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and

  5. Compressibilities and Volume Fluctuations of Archaeal Tetraether Liposomes

    Science.gov (United States)

    Chong, Parkson Lee-Gau; Sulc, Michael; Winter, Roland

    2010-01-01

    Bipolar tetraether lipids (BTLs) are abundant in crenarchaeota, which thrive in both thermophilic and nonthermophilic environments, with wide-ranging growth temperatures (4–108°C). BTL liposomes can serve as membrane models to explore the role of BTLs in the thermal stability of the plasma membrane of crenarchaeota. In this study, we focus on the liposomes made of the polar lipid fraction E (PLFE). PLFE is one of the main BTLs isolated from the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. Using molecular acoustics (ultrasound velocimetry and densimetry), pressure perturbation calorimetry, and differential scanning calorimetry, we have determined partial specific adiabatic and isothermal compressibility, their respective compressibility coefficients, partial specific volume, and relative volume fluctuations of PLFE large unilamellar vesicles (LUVs) over a wide range of temperatures (20–85°C). The results are compared with those obtained from liposomes made of dipalmitoyl-L-α-phosphatidylcholine (DPPC), a conventional monopolar diester lipid. We found that, in the entire temperature range examined, compressibilities of PLFE LUVs are low, comparable to those found in gel state of DPPC. Relative volume fluctuations of PLFE LUVs at any given temperature examined are 1.6–2.2 times more damped than those found in DPPC LUVs. Both compressibilities and relative volume fluctuations in PLFE LUVs are much less temperature-sensitive than those in DPPC liposomes. The isothermal compressibility coefficient (βTlipid) of PLFE LUVs changes from 3.59 × 10−10 Pa−1 at 25°C to 4.08 × 10−10 Pa−1 at 78°C. Volume fluctuations of PLFE LUVs change only 0.25% from 30°C to 80°C. The highly damped volume fluctuations and their low temperature sensitivity, echo that PLFE liposomes are rigid and tightly packed. To our knowledge, the data provide a deeper understanding of lipid packing in PLFE liposomes than has been previously reported, as well as a molecular

  6. Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for pure liquids

    Energy Technology Data Exchange (ETDEWEB)

    Ploetz, Elizabeth A.; Karunaweera, Sadish; Smith, Paul E. [Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan, Kansas 66506 (United States)

    2015-01-28

    Fluctuation solution theory has provided an alternative view of many liquid mixture properties in terms of particle number fluctuations. The particle number fluctuations can also be related to integrals of the corresponding two body distribution functions between molecular pairs in order to provide a more physical picture of solution behavior and molecule affinities. Here, we extend this type of approach to provide expressions for higher order triplet and quadruplet fluctuations, and thereby integrals over the corresponding distribution functions, all of which can be obtained from available experimental thermodynamic data. The fluctuations and integrals are then determined using the International Association for the Properties of Water and Steam Formulation 1995 (IAPWS-95) equation of state for the liquid phase of pure water. The results indicate small, but significant, deviations from a Gaussian distribution for the molecules in this system. The pressure and temperature dependence of the fluctuations and integrals, as well as the limiting behavior as one approaches both the triple point and the critical point, are also examined.

  7. Asymptotics of QCD traveling waves with fluctuations and running coupling effects

    Science.gov (United States)

    Beuf, Guillaume

    2008-09-01

    Extending the Balitsky-Kovchegov (BK) equation independently to running coupling or to fluctuation effects due to pomeron loops is known to lead in both cases to qualitative changes of the traveling-wave asymptotic solutions. In this paper we study the extension of the forward BK equation, including both running coupling and fluctuations effects, extending the method developed for the fixed coupling case [E. Brunet, B. Derrida, A.H. Mueller, S. Munier, Phys. Rev. E 73 (2006) 056126, cond-mat/0512021]. We derive the exact asymptotic behavior in rapidity of the probabilistic distribution of the saturation scale.

  8. Quantum fluctuations and stability of vortex lattices in a nonresonantly pumped exciton-polariton condensate.

    Science.gov (United States)

    Chen, Ting-Wei; Jheng, Shih-Da; Jiang, T F; Cheng, Szu-Cheng

    2017-03-01

    The dynamics of an exciton-polariton condensate (EPC) subject to harmonic confinement can cause spontaneously formed vortices to arrange into a triangular vortex lattice. The stability of such a spontaneously formed vortex lattice is still unknown. We investigate the quantum fluctuations of vortex lattices in a rapidly rotating EPC with a rotation frequency close to the harmonic trap. In such a large condensate, we find that a vortex lattice with a triangular structure is stable, whereas one with a square structure becomes unstable. This result indicates that a driven-dissipative vortex array with strong quantum fluctuations can occur in an EPC.

  9. Thermal equilibrium of a Brownian particle in a fluctuating fluid: a numerical study

    Science.gov (United States)

    Liu, Yi; Nie, Deming

    2017-07-01

    In this work the fluctuating lattice Boltzmann method was adopted to simulate the motion of a Brownian particle in a fluid in two dimensions. The temperatures characterizing the translation motion and rotational motion of the particle were calculated to evaluate the thermal equilibrium between the particle and the fluid. Furthermore, the effects of the fluid temperature and viscosity on the fluid pressure fluctuation were investigated. The linear relationships were observed in a log-log coordinate. Besides, the slopes of the linear relation were obtained, which keeps constant for all cases studied.

  10. Model for probing membrane-cortex adhesion by micropipette aspiration and fluctuation spectroscopy

    CERN Document Server

    Alert, Ricard; Brugués, Jan; Sens, Pierre

    2016-01-01

    We propose a model for membrane-cortex adhesion which couples membrane deformations, hydrodynamics and kinetics of membrane-cortex ligands. In its simplest form, the model gives explicit predictions for the critical pressure for membrane detachment and for the value of adhesion energy. We show that these quantities exhibit a significant dependence on the active acto-myosin stresses. The model provides a simple framework to access quantitative information on cortical activity by means of micropipette experiments. We also extend the model to incorporate fluctuations and show that detailed information on the stability of membrane-cortex coupling can be obtained by a combination of micropipette aspiration and fluctuation spectroscopy measurements.

  11. Correlation length of magnetosheath fluctuations: Cluster statistics

    Directory of Open Access Journals (Sweden)

    O. Gutynska

    2008-09-01

    Full Text Available Magnetosheath parameters are usually described by gasdynamic or magnetohydrodynamic (MHD models but these models cannot account for one of the most important sources of magnetosheath fluctuations – the foreshock. Earlier statistical processing of a large amount of magnetosheath observations has shown that the magnetosheath magnetic field and plasma flow fluctuations downstream of the quasiparallel shock are much larger than those at the opposite flank. These studies were based on the observations of a single spacecraft and thus they could not provide full information on propagation of the fluctuations through the magnetosheath. We present the results of a statistical survey of the magnetosheath magnetic field fluctuations using two years of Cluster observations. We discuss the dependence of the cross-correlation coefficients between different spacecraft pairs on the orientation of the separation vector with respect to the average magnetic field and plasma flow vectors and other parameters. We have found that the correlation length does not exceed ~1 RE in the analyzed frequency range (0.001–0.125 Hz and does not depend significantly on the magnetic field or plasma flow direction. A close connection of cross-correlation coefficients computed in the magnetosheath with the cross-correlation coefficients between a solar wind monitor and a magnetosheath spacecraft suggests that solar wind structures persist on the background of magnetosheath fluctuations.

  12. Fluctuation diamagnetism in two-band superconductors

    Science.gov (United States)

    Adachi, Kyosuke; Ikeda, Ryusuke

    2016-04-01

    Anomalously large fluctuation diamagnetism around the superconducting critical temperature has been recently observed in iron selenide (FeSe) [Kasahara et al. (unpublished)]. This indicates that superconducting fluctuations (SCFs) play a more significant role in FeSe, which supposedly has a two-band structure, than in the familiar single-band superconductors. Motivated by the data on FeSe, SCF-induced diamagnetism is examined in a two-band system, on the basis of a phenomenological approach with a Ginzburg-Landau functional. The obtained results indicate that the SCF-induced diamagnetism may be more enhanced than that in a single-band system due to the existence of two distinct fluctuation modes. Such enhancement of diamagnetism unique to a two-band system seems consistent with the large diamagnetism observed in FeSe, though still far from a quantitative agreement.

  13. Exchange fluctuation theorem for correlated quantum systems.

    Science.gov (United States)

    Jevtic, Sania; Rudolph, Terry; Jennings, David; Hirono, Yuji; Nakayama, Shojun; Murao, Mio

    2015-10-01

    We extend the exchange fluctuation theorem for energy exchange between thermal quantum systems beyond the assumption of molecular chaos, and describe the nonequilibrium exchange dynamics of correlated quantum states. The relation quantifies how the tendency for systems to equilibrate is modified in high-correlation environments. In addition, a more abstract approach leads us to a "correlation fluctuation theorem". Our results elucidate the role of measurement disturbance for such scenarios. We show a simple application by finding a semiclassical maximum work theorem in the presence of correlations. We also present a toy example of qubit-qudit heat exchange, and find that non-classical behaviour such as deterministic energy transfer and anomalous heat flow are reflected in our exchange fluctuation theorem.

  14. Faraday polarization fluctuations of satellite beacon signals

    Science.gov (United States)

    Lee, M. C.; Klobuchar, J. A.

    1988-01-01

    The anisotropic effects of random density irregularities in causing Faraday polarization fluctuations of VHF radio signals are examined, taking both rod-like and sheet-like irregularities into consideration. It is found that the variance of Faraday polarization fluctuations depends on the ratio of perpendicular to parallel correlation lengths. The anisotropic effect of rod-like ionospheric irregularities are shown to be most appreciable for longitudinal propagation. The anisotropic effect of sheet-like ionospheric irregularities, however, is not strongly dependent on the radio propagation angle. During transionospheric propagation at large angles with respect to the geomagnetic field, sheet-like irregularities may cause greater Faraday polarization fluctuations than rod-like irregularities.

  15. Low Mach Number Fluctuating Hydrodynamics for Electrolytes

    CERN Document Server

    Péraud, Jean-Philippe; Chaudhri, Anuj; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L

    2016-01-01

    We formulate and study computationally the low Mach number fluctuating hydrodynamic equations for electrolyte solutions. We are interested in studying transport in mixtures of charged species at the mesoscale, down to scales below the Debye length, where thermal fluctuations have a significant impact on the dynamics. Continuing our previous work on fluctuating hydrodynamics of multicomponent mixtures of incompressible isothermal miscible liquids (A. Donev, et al., Physics of Fluids, 27, 3, 2015), we now include the effect of charged species using a quasielectrostatic approximation. Localized charges create an electric field, which in turn provides additional forcing in the mass and momentum equations. Our low Mach number formulation eliminates sound waves from the fully compressible formulation and leads to a more computationally efficient quasi-incompressible formulation. We demonstrate our ability to model saltwater (NaCl) solutions in both equilibrium and nonequilibrium settings. We show that our algorithm...

  16. Classical and quantum temperature fluctuations via holography

    Energy Technology Data Exchange (ETDEWEB)

    Balatsky, Alexander V. [KTH Royal Inst. of Technology, Stockholm (Sweden); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gudnason, Sven Bjarke [KTH Royal Inst. of Technology, Stockholm (Sweden); Thorlacius, Larus [KTH Royal Inst. of Technology, Stockholm (Sweden); University of Iceland, Reykjavik (Iceland); Zarembo, Konstantin [KTH Royal Inst. of Technology, Stockholm (Sweden); Inst. of Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation); Uppsala Univ. (Sweden); Krikun, Alexander [KTH Royal Inst. of Technology, Stockholm (Sweden); Inst. of Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation); Kedem, Yaron [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2014-05-27

    We study local temperature fluctuations in a 2+1 dimensional CFT on the sphere, dual to a black hole in asymptotically AdS space-time. The fluctuation spectrum is governed by the lowest-lying hydrodynamic sound modes of the system whose frequency and damping rate determine whether temperature fluctuations are thermal or quantum. We calculate numerically the corresponding quasinormal frequencies and match the result with the hydrodynamics of the dual CFT at large temperature. As a by-product of our analysis we determine the appropriate boundary conditions for calculating low-lying quasinormal modes for a four-dimensional Reissner-Nordstrom black hole in global AdS.

  17. RSA fluctuation in major depressive disorder.

    Science.gov (United States)

    Rottenberg, Jonathan; Clift, April; Bolden, Sarah; Salomon, Kristen

    2007-05-01

    Cardiac vagal control, as measured by indices of respiratory sinus arrhythmia (RSA), has been investigated as a marker of impaired self-regulation in mental disorders, including depression. Past work in depressed samples has focused on deficits in resting RSA levels, with mixed results. This study tested the hypothesis that depression involves abnormal RSA fluctuation. RSA was measured in depressed and healthy control participants during rest and during two reactivity tasks, each followed by a recovery period. Relative to controls, depressed persons exhibited lower resting RSA levels as well as less RSA fluctuation, primarily evidenced by a lack of task-related vagal suppression. Group differences in RSA fluctuation were not accounted for by differences in physical health or respiration, whereas group differences in resting RSA level did not survive covariate analyses. Depression may involve multiple deficits in cardiac vagal control.

  18. Investigation of the Ionospheric Fluctuations Caused by Space Weather Effects Using GNSS TEC Measurements

    Science.gov (United States)

    Shagimuratov, Irk; Krankowski, Andrzej; Cherniak, Iurii; Ephishov, Ivan; Zakharenkova, Irina; Yakimova, Galina

    2013-04-01

    It is known that GPS radio signals passing through the ionosphere suffer varying degrees of rapid variations of their amplitude and phase - signal scintillations. The scintillations are caused by the presence of wide range of scale size irregularities in the ionosphere. It is very important to estimate scintillation and phase fluctuation effects on GNSS navigation system (GPS/GLONASS) performance and consequently on the precession of the obtained position. Effects of the ionospheric irregularities on the GPS signals can be evaluated by measurements of the differential phase time rate of dual frequency GPS signals. GPS observations carried out at the Arctic IGS (International GNSS Service) stations were used to study the development of TEC fluctuations in the high latitude ionosphere. Standard GPS measurements with 30s sampling rate allow the detection of middle- and large-scale ionospheric irregularities. For detection of ionospheric fluctuations the rate of TEC (ROT, in the unit of TECU/min) at 1 min interval was used. The temporal occurrence of TEC fluctuations is clearly observed in time variations in the dual frequency carrier phase along satellite passes. As a measure of the fluctuation activity level the Rate of TEC Index (ROTI) based on standard deviation of ROT was also used. ROTI was estimated in 10-minute interval. These techniques and IGS data were used to study the occurrence of TEC fluctuations at the northern latitude ionosphere for selected geomagnetic storms occurred at the end of 23rd and beginning of new 24th solar cycles. Results demonstrate that fluctuation activity of GPS signals in the high latitude ionosphere is depended on geomagnetic conditions. Intensity of fluctuations essentially increases during geomagnetic storms. The strongest TEC fluctuations occurred as short time rate of TEC enhancements of a factor of 2-5 relative to the quiet time. During geomagnetic disturbed conditions strong phase fluctuations can register at latitudes low

  19. Scale invariance and universality of economic fluctuations

    Science.gov (United States)

    Stanley, H. E.; Amaral, L. A. N.; Gopikrishnan, P.; Plerou, V.

    2000-08-01

    In recent years, physicists have begun to apply concepts and methods of statistical physics to study economic problems, and the neologism “econophysics” is increasingly used to refer to this work. Much recent work is focused on understanding the statistical properties of time series. One reason for this interest is that economic systems are examples of complex interacting systems for which a huge amount of data exist, and it is possible that economic time series viewed from a different perspective might yield new results. This manuscript is a brief summary of a talk that was designed to address the question of whether two of the pillars of the field of phase transitions and critical phenomena - scale invariance and universality - can be useful in guiding research on economics. We shall see that while scale invariance has been tested for many years, universality is relatively less frequently discussed. This article reviews the results of two recent studies - (i) The probability distribution of stock price fluctuations: Stock price fluctuations occur in all magnitudes, in analogy to earthquakes - from tiny fluctuations to drastic events, such as market crashes. The distribution of price fluctuations decays with a power-law tail well outside the Lévy stable regime and describes fluctuations that differ in size by as much as eight orders of magnitude. (ii) Quantifying business firm fluctuations: We analyze the Computstat database comprising all publicly traded United States manufacturing companies within the years 1974-1993. We find that the distributions of growth rates is different for different bins of firm size, with a width that varies inversely with a power of firm size. Similar variation is found for other complex organizations, including country size, university research budget size, and size of species of bird populations.

  20. Fluctuations and localization in mesoscopic electron

    CERN Document Server

    Janssen, Martin

    2001-01-01

    The quantum phenomena of tunneling and interference show up not only in the microscopic world of atoms and molecules, but also in cold materials of the real world, such as metals and semiconductors. Though not fully macroscopic, such mesoscopic systems contain a huge number of particles, and the holistic nature of quantum mechanics becomes evident already in simple electronic measurements. The measured quantity fluctuates as a function of applied fields in an unpredictable, yet reproducible way. Despite this fingerprint character of fluctuations, their statistical properties are universal, i.e

  1. Chiral edge fluctuations of colloidal membranes

    Science.gov (United States)

    Jia, Leroy; Zakhary, Mark; Dogic, Zvonimir; Pelcovits, Robert; Powers, Thomas

    Using experiments and theory we study chiral fluctuations of the edge of a nearly flat colloidal membrane, consisting of rod-like viruses held together by the depletion interaction. Our measurements show an anomalous peak in the power spectrum around 1 inverse micron. Using an effective theory to describe the liquid crystal degrees of freedom by geometric properties of the edge, such as length, geodesic torsion, and curvature, we calculate the spectrum of out-of-plane edge fluctuations. The peak arises for sufficiently strong chirality, and corresponds to the instability of a flat membrane to a shape with helical, rippled edges.

  2. Fluctuation theorems for continuously monitored quantum fluxes.

    Science.gov (United States)

    Campisi, Michele; Talkner, Peter; Hänggi, Peter

    2010-10-01

    It is shown that quantum fluctuation theorems remain unaffected if measurements of any kind and number of observables are performed during the action of a force protocol. That is, although the backward and forward probabilities entering the fluctuation theorems are both altered by these measurements, their ratio remains unchanged. This observation allows us to describe the measurement of fluxes through interfaces and, in this way, to bridge the gap between the current theory, based on only two measurements performed at the beginning and end of the protocol, and experiments that are based on continuous monitoring.

  3. Inverse scattering problem in turbulent magnetic fluctuations

    Directory of Open Access Journals (Sweden)

    R. A. Treumann

    2016-08-01

    Full Text Available We apply a particular form of the inverse scattering theory to turbulent magnetic fluctuations in a plasma. In the present note we develop the theory, formulate the magnetic fluctuation problem in terms of its electrodynamic turbulent response function, and reduce it to the solution of a special form of the famous Gelfand–Levitan–Marchenko equation of quantum mechanical scattering theory. The last of these applies to transmission and reflection in an active medium. The theory of turbulent magnetic fluctuations does not refer to such quantities. It requires a somewhat different formulation. We reduce the theory to the measurement of the low-frequency electromagnetic fluctuation spectrum, which is not the turbulent spectral energy density. The inverse theory in this form enables obtaining information about the turbulent response function of the medium. The dynamic causes of the electromagnetic fluctuations are implicit to it. Thus, it is of vital interest in low-frequency magnetic turbulence. The theory is developed until presentation of the equations in applicable form to observations of turbulent electromagnetic fluctuations as input from measurements. Solution of the final integral equation should be done by standard numerical methods based on iteration. We point to the possibility of treating power law fluctuation spectra as an example. Formulation of the problem to include observations of spectral power densities in turbulence is not attempted. This leads to severe mathematical problems and requires a reformulation of inverse scattering theory. One particular aspect of the present inverse theory of turbulent fluctuations is that its structure naturally leads to spatial information which is obtained from the temporal information that is inherent to the observation of time series. The Taylor assumption is not needed here. This is a consequence of Maxwell's equations, which couple space and time evolution. The inversion procedure takes

  4. Two beam surface fluctuation specular reflection spectroscopy.

    Science.gov (United States)

    Raudsepp, Allan; Fretigny, Christian; Lequeux, François; Talini, Laurence

    2012-01-01

    In surface fluctuation specular reflection spectroscopy (SFSRS) deflections of a specularly reflected laser beam are used to characterize thermally excited surface waves. Here we report on a new two beam version of SFSRS in which the deflections of two reflected laser beams from separate locations on a surface are correlated. We demonstrate that this new two beam SFSRS technique can be used to determine directly the power spectrum of height fluctuation of thermally excited surface waves over a large range of both frequencies and wavevectors. In addition, we show that the technique is well suited for materials ranging from simple liquids to complex liquids and soft solids, including turbid materials.

  5. Quantum Fluctuation Theorems, Contextuality, and Work Quasiprobabilities

    Science.gov (United States)

    Lostaglio, Matteo

    2018-01-01

    We discuss the role of contextuality within quantum fluctuation theorems, in the light of a recent no-go result by Perarnau-Llobet et al. We show that any fluctuation theorem reproducing the two-point-measurement scheme for classical states either admits a notion of work quasiprobability or fails to describe protocols exhibiting contextuality. Conversely, we describe a protocol that smoothly interpolates between the two-point-measurement work distribution for projective measurements and Allahverdyan's work quasiprobability for weak measurements, and show that the negativity of the latter is a direct signature of contextuality.

  6. Acute intermittent porphyria with SIADH and fluctuating dysautonomia.

    Science.gov (United States)

    Nabin, A; Thapa, L J; Paudel, R; Rana, P V S

    2012-01-01

    Three cases of acute intermittent porphyria are reported. While in first case severe pain in abdomen with intermittent exacerbation was the only presentation, the second patient presented as accelerated hypertension and acute abdominal crises in whom the clinical course was characterized by development of deep coma due to inappropriate secretion of antidiuretic hormone before she made complete recovery. The third patient, initially manifested as acute encephalitic syndrome. After initial improvement, she developed features of acute intermittent porphyria i.e. acute abdomen, neuropsychiatric symptoms, and rapidly progressing acute motor neuropathy leading to respiratory and bulbar paralysis. In addition, she developed severe and fluctuating dysautonomia leading to cardiac arrest and fatal termination. The importance of early diagnosis, recognition of autonomic disturbances, prompt treatment and counseling for avoidance of precipitating factors is stressed.

  7. Geometric fluctuation theorem for a spin-boson system.

    Science.gov (United States)

    Watanabe, Kota L; Hayakawa, Hisao

    2017-08-01

    We derive an extended fluctuation theorem for geometric pumping of a spin-boson system under periodic control of environmental temperatures by using a Markovian quantum master equation. We obtain the current distribution, the average current, and the fluctuation in terms of the Monte Carlo simulation. To explain the results of our simulation we derive an extended fluctuation theorem. This fluctuation theorem leads to the fluctuation dissipation relations but the absence of the conventional reciprocal relation.

  8. Characterizing the human postural control system using detrended fluctuation analysis

    Science.gov (United States)

    Teresa Blázquez, M.; Anguiano, Marta; de Saavedra, Fernando Arias; Lallena, Antonio M.; Carpena, Pedro

    2010-01-01

    Detrended fluctuation analysis is used to study the behaviour of the time series of the position of the center of pressure, output from the activity of a human postural control system. The results suggest that these trajectories present a crossover in their scaling properties from persistent (for high frequencies, short-range time scale) to anti-persistent (for low frequencies, long-range time scale) behaviours. The values of the scaling exponent found for the persistent parts of the trajectories are very similar for all the cases analysed. The similarity of the results obtained for the measurements done with both eyes open and both eyes closed indicate either that the visual system may be disregarded by the postural control system, while maintaining quiet standing, or that the control mechanisms associated with each type of information (visual, vestibular and somatosensory) cannot be disentangled with this technique.

  9. Spatial correlations of hydrodynamic fluctuations in simple fluids under shear flow: A mesoscale simulation study.

    Science.gov (United States)

    Varghese, Anoop; Gompper, Gerhard; Winkler, Roland G

    2017-12-01

    Hydrodynamic fluctuations in simple fluids under shear flow are demonstrated to be spatially correlated, in contrast to the fluctuations at equilibrium, using mesoscopic hydrodynamic simulations. The simulation results for the equal-time hydrodynamic correlations in a multiparticle collision dynamics (MPC) fluid in shear flow are compared with the explicit expressions obtained from fluctuating hydrodynamics calculations. For large wave vectors k, the nonequilibrium contributions to transverse and longitudinal velocity correlations decay as k^{-4} for wave vectors along the flow direction and as k^{-2} for the off-flow directions. For small wave vectors, a crossover to a slower decay occurs, indicating long-range correlations in real space. The coupling between the transverse velocity components, which vanishes at equilibrium, also exhibits a k^{-2} dependence on the wave vector. In addition, we observe a quadratic dependency on the shear rate of the nonequilibrium contribution to pressure.

  10. Fluctuations and structure of amphiphilic films; Fluctuations et structure de films d`amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Gourier, CH

    1996-07-01

    This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

  11. Temporal and spatial variations in wildlife population fluctuations in Greenland; The effect of climate, environment and man

    DEFF Research Database (Denmark)

    Moshøj, Charlotte Margaret; Forchhammer, Mads C.; Forbes, Valery E.

    2009-01-01

    fluctuations throughout recordable historical time. The most detailed accounts are found for the species that were harvested or had economical value. While several recent studies from northern latitudes have shown the relative roles of climate, the exogenous and endogenous environment of species and man...... as factors driving species population dynamics, the relative contributions and potential interactions among these factors remains unsolved. In Greenland, these fluctuations in the harvests of individual species are believed to be related to changes in climate, as well as variations in hunting pressure....... The results of this study will model future predictions of wildlife populations under changing climate variables and human hunting pressure....

  12. Generalized entropy production fluctuation theorems for quantum ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 80; Issue 2. Generalized entropy ... Based on trajectory-dependent path probability formalism in state space, we derive generalized entropy production fluctuation relations for a quantum system in the presence of measurement and feedback. We have obtained these ...

  13. Magnetic fluctuations in UNi4B

    DEFF Research Database (Denmark)

    Mentink, S.A.M.; Mason, T.E.; Buyers, W.J.L.

    1997-01-01

    We investigate the magnetic fluctuation spectrum of the geometrically frustrated antiferromagnetic compound UNi4B, which partially orders below T-N = 20 K. An overdamped spin excitation is observed at the AF wave vector around 2.4 meV. Low-frequency, weakly Q-dependent inelastic scattering...

  14. Relationship among phenotypic plasticity, phenotypic fluctuations ...

    Indian Academy of Sciences (India)

    2009-09-04

    Sep 4, 2009 ... ... and evolution speed is obtained. The correlation between developmental robustness to noise and evolutionary robustness to mutation is analysed by simulations of the gene network model. These results provide quantitative formulation on canalization and genetic assimilation, in terms of fluctuations of ...

  15. temperature fluctuation inside inert atmosphere silos

    African Journals Online (AJOL)

    user

    TEMPERATURE FLUCTUATION INSIDE INERT ATMOSPHERE SILOS. E. S. Ajayi, et al. Nigerian Journal of Technology. Vol. 35, No. 3, July 2016. 643 also resist heat flow from solar radiation from outside. This is usually achieved by painting the silo wall with white paint. Some of the advantages of inert atmosphere storage ...

  16. Critical point fluctuations in supported lipid membranes.

    Science.gov (United States)

    Connell, Simon D; Heath, George; Olmsted, Peter D; Kisil, Anastasia

    2013-01-01

    In this paper, we demonstrate that it is possible to observe many aspects of critical phenomena in supported lipid bilayers using atomic force microscopy (AFM) with the aid of stable and precise temperature control. The regions of criticality were determined by accurately measuring and calculating phase diagrams for the 2 phase L(d)-L(o) region, and tracking how it moves with temperature, then increasing the sampling density around the estimated critical regions. Compositional fluctuations were observed above the critical temperature (T(c)) and characterised using a spatial correlation function. From this analysis, the phase transition was found to be most closely described by the 2D Ising model, showing it is a critical transition. Below T(c) roughening of the domain boundaries occurred due to the reduction in line tension close to the critical point. Smaller scale density fluctuations were also detected just below T(c). At T(c), we believe we have observed fluctuations on length scales greater than 10 microm. The region of critically fluctuating 10-100 nm nanodomains has been found to extend a considerable distance above T(c) to temperatures within the biological range, and seem to be an ideal candidate for the actual structure of lipid rafts in cell membranes. Although evidence for this idea has recently emerged, this is the first direct evidence for nanoscale domains in the critical region.

  17. Fluctuation scaling, Taylor's law, and crime.

    Science.gov (United States)

    Hanley, Quentin S; Khatun, Suniya; Yosef, Amal; Dyer, Rachel-May

    2014-01-01

    Fluctuation scaling relationships have been observed in a wide range of processes ranging from internet router traffic to measles cases. Taylor's law is one such scaling relationship and has been widely applied in ecology to understand communities including trees, birds, human populations, and insects. We show that monthly crime reports in the UK show complex fluctuation scaling which can be approximated by Taylor's law relationships corresponding to local policing neighborhoods and larger regional and countrywide scales. Regression models applied to local scale data from Derbyshire and Nottinghamshire found that different categories of crime exhibited different scaling exponents with no significant difference between the two regions. On this scale, violence reports were close to a Poisson distribution (α = 1.057 ± 0.026) while burglary exhibited a greater exponent (α = 1.292 ± 0.029) indicative of temporal clustering. These two regions exhibited significantly different pre-exponential factors for the categories of anti-social behavior and burglary indicating that local variations in crime reports can be assessed using fluctuation scaling methods. At regional and countrywide scales, all categories exhibited scaling behavior indicative of temporal clustering evidenced by Taylor's law exponents from 1.43 ± 0.12 (Drugs) to 2.094 ± 0081 (Other Crimes). Investigating crime behavior via fluctuation scaling gives insight beyond that of raw numbers and is unique in reporting on all processes contributing to the observed variance and is either robust to or exhibits signs of many types of data manipulation.

  18. Fluctuations in doubly scattered laser light

    NARCIS (Netherlands)

    Rijswijk, F.C. van; Smith, U.L.

    1975-01-01

    Fluctuations in laser light, doubly scattered by brownian particles, were analysed by measuring the spectral noise power of the photodetector current. Scattering took place at two spatially separated systems of spherical particles. Analytic expressions for the field and intensity correlations are

  19. Effect of programmed circadian temperature fluctuations on ...

    African Journals Online (AJOL)

    Effect of programmed circadian temperature fluctuations on population dynamics of. Biomphalaria pfeifferi (Krauss). K.N. de Kock and J.A. van Eeden. Snail Research Unit, Medical Research Council, Potchefstroom University for Christian Higher Education,. Potchefstroom. Until now all life-table studies on freshwater snails.

  20. Advantages of storage in a fluctuating environment.

    NARCIS (Netherlands)

    Kooi, B.W.; Troost, T.A.

    2006-01-01

    We will elaborate the evolutionary course of an ecosystem consisting of a population in a chemostat environment with periodically fluctuating nutrient supply. The organisms that make up the population consist of structural biomass and energy storage compartments. In a constant chemostat environment

  1. Quantum and Thermal Fluctuations in Field Theory

    OpenAIRE

    Liao, Sen-Ben; Polonyi, Janos; Xu, Dapeng

    1994-01-01

    Blocking transformation is performed in quantum field theory at finite temperature. It is found that the manner temperature deforms the renormalized trajectories can be used to understand better the role played by the quantum fluctuations. In particular, it is conjectured that domain formation and mass parameter generation can be observed in theories without spontaneous symmetry breaking.

  2. PREDICTION OF VOLTAGE FLUCTUATION IN ELECTRIC GRIDS

    Directory of Open Access Journals (Sweden)

    V.A. Sapryka

    2013-06-01

    Full Text Available A mathematical model of voltage fluctuation versus parameters of power quality and power consumption is developed to allow predicting parameters of the power quality in electric grids. Application of the model will result in an electrical complex functioning optimization

  3. Fluctuation scaling, Taylor's law, and crime.

    Directory of Open Access Journals (Sweden)

    Quentin S Hanley

    Full Text Available Fluctuation scaling relationships have been observed in a wide range of processes ranging from internet router traffic to measles cases. Taylor's law is one such scaling relationship and has been widely applied in ecology to understand communities including trees, birds, human populations, and insects. We show that monthly crime reports in the UK show complex fluctuation scaling which can be approximated by Taylor's law relationships corresponding to local policing neighborhoods and larger regional and countrywide scales. Regression models applied to local scale data from Derbyshire and Nottinghamshire found that different categories of crime exhibited different scaling exponents with no significant difference between the two regions. On this scale, violence reports were close to a Poisson distribution (α = 1.057 ± 0.026 while burglary exhibited a greater exponent (α = 1.292 ± 0.029 indicative of temporal clustering. These two regions exhibited significantly different pre-exponential factors for the categories of anti-social behavior and burglary indicating that local variations in crime reports can be assessed using fluctuation scaling methods. At regional and countrywide scales, all categories exhibited scaling behavior indicative of temporal clustering evidenced by Taylor's law exponents from 1.43 ± 0.12 (Drugs to 2.094 ± 0081 (Other Crimes. Investigating crime behavior via fluctuation scaling gives insight beyond that of raw numbers and is unique in reporting on all processes contributing to the observed variance and is either robust to or exhibits signs of many types of data manipulation.

  4. A theory of fluctuations in plasmas

    NARCIS (Netherlands)

    Felderhof, B.U.

    A theory of thermal fluctuations in plasmas is developed based on a probability ensemble for one-particle distribution functions ƒ(r, ν). The probability for a specific ƒ(r, ν) is obtained from the canonical ensemble with the aid of the continuum approximation. Subsequently the probability

  5. Macroeconomic fluctuations and mortality in postwar Japan.

    Science.gov (United States)

    Granados, José A Tapia

    2008-05-01

    Recent research has shown that after long-term declining trends are excluded, mortality rates in industrial countries tend to rise in economic expansions and fall in economic recessions. In the present work, co-movements between economic fluctuations and mortality changes in postwar Japan are investigated by analyzing time series of mortality rates and eight economic indicators. To eliminate spurious associations attributable to trends, series are detrended either via Hodrick-Prescott filtering or through differencing. As previously found in other industrial economies, general mortality and age-specific death rates in Japan tend to increase in expansions and drop in recessions, for both males and females. The effect, which is slightly stronger for males, is particularly noticeable in those aged 45-64. Deaths attributed to heart disease, pneumonia, accidents, liver disease, and senility--making up about 41% of total mortality--tend to fluctuate procyclically, increasing in expansions. Suicides, as well as deaths attributable to diabetes and hypertensive disease, make up about 4% of total mortality and fluctuate countercyclically, increasing in recessions. Deaths attributed to other causes, making up about half of total deaths, don't show a clearly defined relationship with the fluctuations of the economy.

  6. Low Mach number fluctuating hydrodynamics for electrolytes

    Science.gov (United States)

    Péraud, Jean-Philippe; Nonaka, Andy; Chaudhri, Anuj; Bell, John B.; Donev, Aleksandar; Garcia, Alejandro L.

    2016-11-01

    We formulate and study computationally the low Mach number fluctuating hydrodynamic equations for electrolyte solutions. We are interested in studying transport in mixtures of charged species at the mesoscale, down to scales below the Debye length, where thermal fluctuations have a significant impact on the dynamics. Continuing our previous work on fluctuating hydrodynamics of multicomponent mixtures of incompressible isothermal miscible liquids [A. Donev et al., Phys. Fluids 27, 037103 (2015), 10.1063/1.4913571], we now include the effect of charged species using a quasielectrostatic approximation. Localized charges create an electric field, which in turn provides additional forcing in the mass and momentum equations. Our low Mach number formulation eliminates sound waves from the fully compressible formulation and leads to a more computationally efficient quasi-incompressible formulation. We demonstrate our ability to model saltwater (NaCl) solutions in both equilibrium and nonequilibrium settings. We show that our algorithm is second order in the deterministic setting and for length scales much greater than the Debye length gives results consistent with an electroneutral approximation. In the stochastic setting, our model captures the predicted dynamics of equilibrium and nonequilibrium fluctuations. We also identify and model an instability that appears when diffusive mixing occurs in the presence of an applied electric field.

  7. Quantum fluctuations in FRLW space-time

    OpenAIRE

    Rabochaya, Y.

    2015-01-01

    In this paper we study a quantum field theoretical approach, where a quantum probe is used to investigate the properties of generic non-flat FRLW space time. The fluctuations related to a massless conformal coupled scalar field defined on a space-time with horizon is identified with a probe and the procedure to measure the local temperature is presented.

  8. Role of turgor pressure and solute transport in plant cell growth: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Cosgrove, D.J.

    1987-10-15

    Plant cell expansion requires coordinationion of three distinct processes: wall relaxation and synthesis, water uptake, and solute uptake. Wall relaxation reduces cell turgor pressure and thereby generates the reduced water for water potential needed uptake. Our studies with pea (Pisum sativum L.) and soybean (Glycine max Merr.) seedlings have shown that water uptake is rapid and is not a major control point for growth. Our current focus is on the processes of wall relaxation and solute transport, and how they are influenced by water stress. One major goal of this project is to examine in detail the dependence of wall yielding on turgor pressure. This is being done by detailed measurements of wall relaxation in living cells, using a computer-assisted pressure microprobe and the new pressure-block technique. Our pressure-block results indicate that wall relaxation is more dynamic than expected. Rapid changes in wall yielding appear to compensate for minor fluctuations in cell turgor pressure, thus maintaining stable growth rates. A second major goal of this project is to determine the interrelationship between cell expansion and solute transport into expanding cells. We will selectively block either cell expansion or solute transport, and measure the effect of such blockage on the unblocked process. A third goal is to examine the basis for reduced cell expansion when plants are water stressed. Our results indicate that growth is retarded in part because of reduced turgor pressure, and in part because of reduced cell wall relaxation. The alteration in wall relaxation will be examined by in-vivo relaxation methods. Thus studies will provide insight into the basic cellular and physical processes controlling plant growth, and how they are perturbed by water stress. 8 refs., 1 fig.

  9. Pressure ulcers

    National Research Council Canada - National Science Library

    Reddy, Madhuri

    2011-01-01

    Unrelieved pressure or friction of the skin, particularly over bony prominences, can lead to pressure ulcers in up to one third of people in hospitals or community care, and one fifth of nursing home residents...

  10. Rapid mineralocorticoid receptor trafficking.

    Science.gov (United States)

    Gekle, M; Bretschneider, M; Meinel, S; Ruhs, S; Grossmann, C

    2014-03-01

    The mineralocorticoid receptor (MR) is a ligand-dependent transcription factor that physiologically regulates water-electrolyte homeostasis and controls blood pressure. The MR can also elicit inflammatory and remodeling processes in the cardiovascular system and the kidneys, which require the presence of additional pathological factors like for example nitrosative stress. However, the underlying molecular mechanism(s) for pathophysiological MR effects remain(s) elusive. The inactive MR is located in the cytosol associated with chaperone molecules including HSP90. After ligand binding, the MR monomer rapidly translocates into the nucleus while still being associated to HSP90 and after dissociation from HSP90 binds to hormone-response-elements called glucocorticoid response elements (GREs) as a dimer. There are indications that rapid MR trafficking is modulated in the presence of high salt, oxidative or nitrosative stress, hypothetically by induction or posttranslational modifications. Additionally, glucocorticoids and the enzyme 11beta hydroxysteroid dehydrogenase may also influence MR activation. Because MR trafficking and its modulation by micro-milieu factors influence MR cellular localization, it is not only relevant for genomic but also for nongenomic MR effects. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Critical fluctuations in cortical models near instability

    Directory of Open Access Journals (Sweden)

    Matthew J. Aburn

    2012-08-01

    Full Text Available Computational studies often proceed from the premise that cortical dynamics operate in a linearly stable domain, where fluctuations dissipate quickly and show only short memory. Studies of human EEG, however, have shown significant autocorrelation at time lags on the scale of minutes, indicating the need to consider regimes where nonlinearities influence the dynamics. Statistical properties such as increased autocorrelation length, increased variance, power-law scaling and bistable switching have been suggested as generic indicators of the approach to bifurcation in nonlinear dynamical systems. We study temporal fluctuations in a widely-employed computational model (the Jansen-Rit model of cortical activity, examining the statistical signatures that accompany bifurcations. Approaching supercritical Hopf bifurcations through tuning of the background excitatory input, we find a dramatic increase in the autocorrelation length that depends sensitively on the direction in phase space of the input fluctuations and hence on which neuronal subpopulation is stochastically perturbed. Similar dependence on the input direction is found in the distribution of fluctuation size and duration, which show power law scaling that extends over four orders of magnitude at the Hopf bifurcation. We conjecture that the alignment in phase space between the input noise vector and the center manifold of the Hopf bifurcation is directly linked to these changes. These results are consistent with the possibility of statistical indicators of linear instability being detectable in real EEG time series. However, even in a simple cortical model, we find that these indicators may not necessarily be visible even when bifurcations are present because their expression can depend sensitively on the neuronal pathway of incoming fluctuations.

  12. Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral Pocillopora damicornis

    Directory of Open Access Journals (Sweden)

    L. Jiang

    2017-12-01

    Full Text Available Diurnal fluctuations in seawater temperature are ubiquitous on tropical reef flats. However, the effects of such dynamic temperature variations on the early stages of corals are poorly understood. In this study, we investigated the responses of larvae and new recruits of Pocillopora damicornis to two constant temperature treatments (29 and 31 °C and two diurnally fluctuating treatments (28–31 and 30–33 °C with daily means of 29 and 31 °C, respectively simulating the 3 °C diel oscillations at 3 m depth on the Luhuitou fringing reef (Sanya, China. Results showed that the thermal stress on settlement at 31 °C was almost negated by the fluctuating treatment. Further, neither elevated temperature nor temperature fluctuations caused bleaching responses in recruits, while the maximum excitation pressure over photosystem II (PSII was reduced under fluctuating temperatures. Although early growth and development were highly stimulated at 31 °C, oscillations of 3 °C had little effects on budding and lateral growth at either mean temperature. Nevertheless, daytime encounters with the maximum temperature of 33 °C in fluctuating 31 °C elicited a notable reduction in calcification compared to constant 31 °C. These results underscore the complexity of the effects caused by diel temperature fluctuations on early stages of corals and suggest that ecologically relevant temperature variability could buffer warming stress on larval settlement and dampen the positive effects of increased temperatures on coral growth.

  13. Barometric pressure

    Science.gov (United States)

    Billings, C. E.

    1973-01-01

    The effects of alterations in barometric pressure on human beings are described. Human tolerances for gaseous environments and low and high barometric pressure are discussed, including effects on specific areas, such as the ear, lungs, teeth, and sinuses. Problems due to trapped gas within the body, high dynamic pressures on the body, and blasts are also considered.

  14. Characterization of broadband fluctuations in wide-pedestal QH-mode plasmas on DIII-D

    Science.gov (United States)

    Muscatello, C. M.; Burrell, K. H.; Luhmann, N. C., Jr.; McKee, G. R.; Tobias, B.

    2016-10-01

    Edge broadband fluctuations observed in wide pedestal quiescent H-mode plasmas may play an important role in driving transport necessary for stabilizing the edge to kink-peeling modes, thought to lead to ELMs. Density fluctuation measurements from BES and MIR independently observe periodic bursts in the pedestal that show up spectrally as broadband fluctuations. The period of the fluctuation bursts correlate with the period of enhanced bicoherence in the frequency range of the fluctuations, suggesting nonlinear coupling of turbulence. Time-delay estimation analysis of the 2D BES data shows strong evidence of a low-frequency zonal flow in the pedestal with a period matching that of the bursts. The carbon pressure gradient and E × B velocity, determined from CER, and ECE emission also oscillate with the same period. This behavior can be described as a quasi-stationary, limit-cycle oscillation and modeled by a set of predator-prey equations relating the zonal flow, equilibrium flow, and turbulence amplitude. Supported by the US DOE under DE-FC02-04ER54698, DE-FG02-99ER54531, DE-AC02-09CH11466.

  15. Numerical Investigation on a Prototype Centrifugal Pump Subjected to Fluctuating Rotational Speed

    Directory of Open Access Journals (Sweden)

    Yu-Liang Zhang

    2014-01-01

    Full Text Available The rotational speed of pumps often encounters fluctuation in engineering for some reasons. In this paper, in order to study the transient response characteristic of a prototype centrifugal pump subjected to fluctuating rotational speed, a closed-loop pipe system including the pump is built to accomplish unsteady flow calculations in which the boundary conditions at the inlet and the outlet of the pump are not required to be set. The external performance results show that the head’s responsiveness to the fluctuating rotational speed is very good, while the flow rate’s responsiveness is slightly delayed. The variation tendencies of the static pressures at the inlet and the outlet of the pump are almost completely opposite, wherein the variation tendency of the static pressure at the outlet is identical with that of the rotational speed. The intensity of the turbulence energy in each impeller channel is relatively uniform in the transient flow calculations, while, in the quasi-steady flow calculation, it becomes weaker in a channel closed to the volute tongue. The nondimensional flow rate and head coefficients are dependent on the rotational speed, and their variation tendencies are opposite to that of the fluctuating rotational speed as a whole.

  16. MEASUREMENTS OF PRESSURE DISTRIBUTIONS ON A ROTOR BLADE USING PSP TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Kidong Kim

    2011-12-01

    Full Text Available Surface pressure distributions on a rotating blade were measured by using pressure sensitive paint (PSP to understand aerodynamic characteristics of a rotor blade. The present study was conducted to investigate the PSP techniques for measuring the pressure distributions on a rotor blade. In order to perform the experiment, the PSP was required to response very fast due to rapid pressure fluctuations on a rotor blade. High energy excitation light source was also needed to acquire proper intensity images in a short excitation time. The techniques were based on a lifetime method. Qualitative pressure distributions on an upper surface of small scale rotor in hovering condition were measured as a preliminary experiment prior to forward flight conditions in the KARI low speed wind tunnel laboratory. From measured pressure distributions, striking pressure gradient was observed on an upper surface of rotor blade and the resulting pressure showed expected gradient depending on different collective pitch angles. ABSTRAK : Pengagihan tekanan permukaan ke atas berbilah putar disukat menggunakan cat sensitive tekanan (pressure sensitive paint (PSP untuk memahami sifat-sifat aerodinamik suatu berbilah putar. Kajian telah dijalankan untuk menyelidik teknik-teknik PSP dengan mengukur agihan tekanan ke atas suatu berbilah putar. Agar eksperimen dapat dijalankan dengan baik, PSP harus bertindak cepat kerana tekanan naik turun dengan pantas ke atas berbilah putar. Sumber cahaya ujaan tenaga tinggi diperlukan untuk mendapatkan imej keamatan wajar dalam jangka masa ujaan yang pendek. Teknik-teknik tersebut terhasil daripada kajian semasa hayat. Agihan tekanan kualitatif ke permukaan atas berskala kecil pemutar dalam keadaan mengapung diukur sebagai permulaan eksperimen, sebelum penerbangan kehadapan dalam makmal terowong angin laju rendah KARI. Daripada agihan tekanan yang disukat, kecerunan tekanan yang ketara diperolehi daripada permerhatian terhadap permukaan

  17. Heat fluctuations of Brownian oscillators in nonstationary processes: Fluctuation theorem and condensation transition.

    Science.gov (United States)

    Crisanti, A; Sarracino, A; Zannetti, M

    2017-05-01

    We study analytically the probability distribution of the heat released by an ensemble of harmonic oscillators to the thermal bath, in the nonequilibrium relaxation process following a temperature quench. We focus on the asymmetry properties of the heat distribution in the nonstationary dynamics, in order to study the forms taken by the fluctuation theorem as the number of degrees of freedom is varied. After analyzing in great detail the cases of one and two oscillators, we consider the limit of a large number of oscillators, where the behavior of fluctuations is enriched by a condensation transition with a nontrivial phase diagram, characterized by reentrant behavior. Numerical simulations confirm our analytical findings. We also discuss and highlight how concepts borrowed from the study of fluctuations in equilibrium under symmetry-breaking conditions [Gaspard, J. Stat. Mech. (2012) P0802110.1088/1742-5468/2012/08/P08021] turn out to be quite useful in understanding the deviations from the standard fluctuation theorem.

  18. Classical fluctuations in dissipative quantum systems - metamorphosisof quantum fluctuations into cosmic non-uniformity.

    Science.gov (United States)

    Morikawa, M.

    Assuming an inflationary phase in the early universe, this paper studies the generation of non-uniformity from an entirely uniform universe where no statistical fluctuations nor structure are present.

  19. Universal Property of Quantum Measurements of Equilibrium Fluctuations and Violation of the Fluctuation-Dissipation Theorem

    Science.gov (United States)

    Fujikura, Kyota; Shimizu, Akira

    2016-07-01

    For macroscopic quantum systems, we study what is measured when equilibrium fluctuations of macrovariables are measured in an ideal way that mimics classical ideal measurements as closely as possible. We find that the symmetrized time correlation is always obtained for such measurements. As an important consequence, we show that the fluctuation-dissipation theorem is partially violated as a relation between observed quantities in macroscopic quantum systems even if measurements are made in such an ideal way.

  20. Universal Property of Quantum Measurements of Equilibrium Fluctuations and Violation of the Fluctuation-Dissipation Theorem.

    Science.gov (United States)

    Fujikura, Kyota; Shimizu, Akira

    2016-07-01

    For macroscopic quantum systems, we study what is measured when equilibrium fluctuations of macrovariables are measured in an ideal way that mimics classical ideal measurements as closely as possible. We find that the symmetrized time correlation is always obtained for such measurements. As an important consequence, we show that the fluctuation-dissipation theorem is partially violated as a relation between observed quantities in macroscopic quantum systems even if measurements are made in such an ideal way.

  1. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Directory of Open Access Journals (Sweden)

    Behnam Pourhassan

    2016-04-01

    Full Text Available In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  2. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Energy Technology Data Exchange (ETDEWEB)

    Pourhassan, Behnam, E-mail: b.pourhassan@du.ac.ir [School of Physics, Damghan University, Damghan (Iran, Islamic Republic of); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)

    2016-04-10

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  3. Effect of Thermal Fluctuations on a Charged Dilatonic Black Saturn

    CERN Document Server

    Pourhassan, Behnam

    2016-01-01

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  4. Numerical Investigation of Periodically Unsteady Pressure Field in a High Power Centrifugal Diffuser Pump

    Directory of Open Access Journals (Sweden)

    Ji Pei

    2014-05-01

    Full Text Available Pressure fluctuations are the main factors that can give rise to reliability problems in centrifugal pumps. The periodically unsteady pressure characteristics caused by rotor-stator interaction have been investigated by CFD calculation in a residual heat removal pump. Side chamber flow effect is also considered for the simulation to accurately predict the flow in whole flow passage. The pressure fluctuation results in time and frequency domains were considered for several typical monitoring points in impeller and diffuser channels. In addition, the pressure fluctuation intensity coefficient (PFIC based on standard deviation was defined on each grid node for entire space and impeller revolution period. The results show that strong pressure fluctuation intensity can be found in the gap between impeller and diffuser. As a source, the fluctuation can spread to the upstream and downstream flow channels as well as the side chamber channels. Meanwhile, strong pressure fluctuation intensity can be found in the discharge tube of the circular casing. In addition, the obvious influence of operational flow rate on the PFIC distribution can be found. The analysis indicates that the pressure fluctuations in the aspects of both frequency and intensity can be used to comprehensively evaluate the unsteady pressure characteristics in centrifugal pumps.

  5. Effect of mesoscopic fluctuations on equation of state in cluster-forming systems

    Directory of Open Access Journals (Sweden)

    A. Ciach

    2012-06-01

    Full Text Available Equation of state for systems with particles self-assembling into aggregates is derived within a mesoscopic theory combining density functional and field-theoretic approaches. We focus on the effect of mesoscopic fluctuations in the disordered phase. The pressure - volume fraction isotherms are calculated explicitly for two forms of the short-range attraction long-range repulsion potential. Mesoscopic fluctuations lead to an increased pressure in each case, except for very small volume fractions. When large clusters are formed, the mechanical instability of the system is present at much higher temperature than found in mean-field approximation. In this case phase separation competes with the formation of periodic phases (colloidal crystals. In the case of small clusters, no mechanical instability associated with separation into dilute and dense phases appears.

  6. Cascading of Fluctuations in Interdependent Energy Infrastructures: Gas-Grid Coupling

    CERN Document Server

    Chertkov, Michael; Backhaus, Scott

    2014-01-01

    The revolution of hydraulic fracturing has dramatically increased the supply and lowered the cost of natural gas in the United States driving an expansion of natural gas-fired generation capacity in many electrical grids. Unrelated to the natural gas expansion, lower capital costs and renewable portfolio standards are driving an expansion of intermittent renewable generation capacity such as wind and photovoltaic generation. These two changes may potentially combine to create new threats to the reliability of these interdependent energy infrastructures. Natural gas-fired generators are often used to balance the fluctuating output of wind generation. However, the time-varying output of these generators results in time-varying natural gas burn rates that impact the pressure in interstate transmission pipelines. Fluctuating pressure impacts the reliability of natural gas deliveries to those same generators and the safety of pipeline operations. We adopt a partial differential equation model of natural gas pipeli...

  7. The correlation between the Nernst effect and fluctuation diamagnetism in strongly fluctuating superconductors

    Science.gov (United States)

    Sarkar, Kingshuk; Banerjee, Sumilan; Mukerjee, Subroto; Ramakrishnan, T. V.

    2017-07-01

    We study the Nernst effect in fluctuating superconductors by calculating the transport coefficient {α }{xy} in a phenomenological model where the relative importance of phase and amplitude fluctuations of the order parameter is tuned continuously to smoothly evolve from an effective XY model to the more conventional Ginzburg-Landau description. To connect with a concrete experimental realization we choose the model parameters appropriate for cuprate superconductors and calculate {α }{xy} and the magnetization {M} over the entire range of experimentally accessible values of field, temperature and doping. We argue that {α }{xy} and {M} are both determined by the equilibrium properties of the superconducting fluctuations (and not their dynamics) despite the former being a transport quantity. Thus, the experimentally observed correlation between the Nernst signal and the magnetization arises primarily from the correlation between {α }{xy} and {M}. Further, there exists a dimensionless ratio {M}/(T{α }{xy}) that quantifies this correlation. We calculate, for the first time, this ratio over the entire phase diagram of the cuprates and find it agrees with previous results obtained in specific parts of the phase diagram. We conclude that there appears to be no sharp distinction between the regimes dominated by phase fluctuations and Gaussian fluctuations for this ratio in contrast to {α }{xy} and {M} individually. The utility of this ratio is that it can be used to determine the extent to which superconducting fluctuations contribute to the Nernst effect in different parts of the phase diagram given the measured values of magnetization.

  8. Deformation analysis and prediction of bank protection structure with river level fluctuations

    Science.gov (United States)

    Hu, Rui; Xing, Yixuan

    2017-04-01

    Bank structure is an important barrier to maintain the safety of the embankment. The deformation of bank protection structure is not only affected by soil pressure caused by the excavation of the riverway, but also by the water pressure caused river water level fluctuations. Thus, it is necessary to establish a coupled soil-water model to analyze the deformation of bank structure. Based on Druck-Prager failure criteria and groundwater seepage theory, a numerical model of bank protection structure with consideration of the pore water pressure of soil mass is established. According to the measured river level data with seasonal fluctuating, numerical analysis of the deformation of bank protection structure is implemented. The simulation results show that the river water level fluctuation has clear influence on the maximum lateral displacement of the pile. Meanwhile, the distribution of plastic zone is related to the depth of groundwater level. Finally, according to the river water level data of the recent ten years, we analyze the deformation of the bank structure under extreme river level. The result shows that, compared with the scenario of extreme high river level, the horizontal displacement of bank protection structure is larger (up to 65mm) under extreme low river level, which is a potential risk to the embankment. Reference Schweiger H F. On the use of drucker-prager failure criteria for earth pressure problems[J]. Computers and Geotechnics, 1994, 16(3): 223-246. DING Yong-chun,CHENG Ze-kun. Numerical study on performance of waterfront excavation[J]. Chinese Journal of Geotechnical Engineering,2013,35(2):515-521. Wu L M, Wang Z Q. Three gorges reservoir water level fluctuation influents on the stability of the slope[J]. Advanced Materials Research. Trans Tech Publications, 2013, 739: 283-286.

  9. Signal fluctuations in crystal-APD systems

    Energy Technology Data Exchange (ETDEWEB)

    Kocak, F., E-mail: fkocak@uludag.edu.tr [Uludag University, Department of Physics, 16059 Bursa (Turkey); Tapan, I.; Pilicer, E. [Uludag University, Department of Physics, 16059 Bursa (Turkey)

    2011-08-21

    PbWO{sub 4} and CsI(Tl) crystals are widely used in high energy physics experiments. The photons generated from incident particles in the crystal material are detected by the Avalanche photodiodes (APD) placed at the end of the crystals. In this work, the light generated by 0.1-5 GeV electrons in the crystals has been obtained using with the GEANT4 simulation code. The Single Particle Monte Carlo technique has been used to calculate APD output signals and their fluctuations at a constant avalanche gain value of 50 for both the CsI(Tl) and PbWO{sub 4} crystals emission spectrum. The simulation results are agreed well with the experimental results. CsI(Tl) crystal-APD system has provided a good material-device combination. The high signal values and the low signal fluctuations make this combination an excellent choice for scintillating light detection.

  10. Fluctuation theorem in quantum heat conduction.

    Science.gov (United States)

    Saito, Keiji; Dhar, Abhishek

    2007-11-02

    We consider steady-state heat conduction across a quantum harmonic chain connected to reservoirs modeled by infinite collection of oscillators. The heat, Q, flowing across the oscillator in a time interval tau is a stochastic variable and we study the probability distribution function P(Q). We compute the exact generating function of Q at large tau and the large deviation function. The generating function has a symmetry satisfying the steady-state fluctuation theorem without any quantum corrections. The distribution P(Q) is non-Gaussian with clear exponential tails. The effect of finite tau and nonlinearity is considered in the classical limit through Langevin simulations. We also obtain the prediction of quantum heat current fluctuations at low temperatures in clean wires.

  11. Trapped Electron Precession Shear Induced Fluctuation Decorrelation

    Energy Technology Data Exchange (ETDEWEB)

    T.S. Hahm; P.H. Diamond; E.-J. Kim

    2002-07-29

    We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.

  12. Prevention of Employees Fluctuation in IT

    Directory of Open Access Journals (Sweden)

    Libor Mesicek

    2017-10-01

    Full Text Available The aim of this paper is to present results of implementation fluctuation preventing counter-measures among other positions in IT department. In 2017 there is still one of the lowest unemployment rates in the history of the Czech Republic (especially in IT and companies are trying to preserve and prevent their key employees from moving to another employer. One of the tools, which could help reduce this risk, is providing additional education, certification and qualification with laying great emphasis on most valuable and essential personnel. The paper present updated results after 6 months since the company started with selection of high risks employees. It has been found that group of employees with high risk of leaving the company has shrunk and overall fluctuation index has also plunged.

  13. Classicalization of Quantum Fluctuation in Inflationary Universe

    Science.gov (United States)

    Kubotani, H.; Uesugi, T.; Morikawa, M.; Sugamoto, A.

    1997-11-01

    We discuss the classicalization of a quantum state induced by an environment in the inflationary stage of the universe. The classicalization is necessary for the homogeneous ground state to become the inhomogeneous classical one accompanied with statistical fluctuations, which is a plausible candidate for the seeds of structure formation. Using simple models, we show that i) the two classicalization criteria, the classical correlation and quantum decoherence, are simultaneously satisfied by the environment and that ii) the power spectrum of the resultant statistical fluctuations depends upon the details of the classicalization process. In particular, the result ii) means that, taking into account the classicalization process, the inflationary scenario does not necessarily predict the unique spectrum which is usually believed.

  14. Energy utilization in fluctuating biological energy converters

    Directory of Open Access Journals (Sweden)

    Abraham Szőke

    2016-05-01

    Full Text Available We have argued previously [Szoke et al., FEBS Lett. 553, 18–20 (2003; Curr. Chem. Biol. 1, 53–57 (2007] that energy utilization and evolution are emergent properties based on a small number of established laws of physics and chemistry. The relevant laws constitute a framework for biology on a level intermediate between quantum chemistry and cell biology. There are legitimate questions whether these concepts are valid at the mesoscopic level. Such systems fluctuate appreciably, so it is not clear what their efficiency is. Advances in fluctuation theorems allow the description of such systems on a molecular level. We attempt to clarify this topic and bridge the biochemical and physical descriptions of mesoscopic systems.

  15. Intermittent character of interplanetary magnetic field fluctuations

    Science.gov (United States)

    Bruno, Roberto; Carbone, Vincenzo; Chapman, Sandra; Hnat, Bogdan; Noullez, Alain; Sorriso-Valvo, Luca

    2007-03-01

    Interplanetary magnetic field magnitude fluctuations are notoriously more intermittent than velocity fluctuations in both fast and slow wind. This behavior has been interpreted in terms of the anomalous scaling observed in passive scalars in fully developed hydrodynamic turbulence. In this paper, the strong intermittent nature of the interplanetary magnetic field is briefly discussed comparing results performed during different phases of the solar cycle. The scaling properties of the interplanetary magnetic field magnitude show solar cycle variation that can be distinguished in the scaling exponents revealed by structure functions. The scaling exponents observed around the solar maximum coincide, within the errors, to those measured for passive scalars in hydrodynamic turbulence. However, it is also found that the values are not universal in the sense that the solar cycle variation may be reflected in dependence on the structure of the velocity field.

  16. Quantum Fluctuations of a Superconductor Order Parameter.

    Science.gov (United States)

    Arutyunov, K Yu; Lehtinen, J S

    2016-12-01

    Tunneling I-V characteristics between very narrow titanium nanowires and "massive" superconducting aluminum were measured. The clear trend was observed: the thinner the titanium electrode, the broader the singularity at eV = Δ1(Al) + Δ2(Ti). The phenomenon can be explained by broadening of the gap edge of the quasi-one-dimensional titanium channels due to quantum fluctuations of the order parameter modulus |Δ2|. The range of the nanowire diameters, where the effect is pronounced, correlates with dimensions where the phase fluctuations of the complex superconducting order parameter Δ = |Δ|e(iφ), the quantum phase slips, broadening the R(T) dependencies, have been observed.

  17. Balancing Aggradation and Progradation on a Vegetated Delta: The Importance of Fluctuating Discharge in Depositional Systems

    Science.gov (United States)

    Piliouras, Anastasia; Kim, Wonsuck; Carlson, Brandee

    2017-10-01

    Vegetation is an important component of constructional landscapes, as plants enhance deposition and provide organic sediment that can increase aggradation rates to combat land loss. We conducted two sets of laboratory experiments using alfalfa (Medicago sativa) to determine the effects of plants on channel organization and large-scale delta dynamics. In the first set, we found that rapid vegetation colonization enhanced deposition but inhibited channelization via increased form drag that reduced the shear stress available for sediment entrainment and transport. A second set of experiments used discharge fluctuations between flood and base flow (or interflood). Interfloods were critical for reworking the topset via channel incision and lateral migration to create channel relief and prevent rapid plant colonization. These low-flow periods also greatly reduced the topset slope in the absence of vegetation by removing topset sediment and delivering it to the shoreline. Floods decreased relief by filling channels with sediment, resulting in periods of rapid progradation and enhanced aggradation over the topset surface, which was amplified by vegetation. The combination of discharge fluctuations and vegetation thus provided a balance of vertical aggradation and lateral progradation. We conclude that plants can inhibit channelization in depositional systems and that discharge fluctuations encourage channel network organization to naturally balance against aggradation. Thus, variations in discharge are an important aspect of understanding the ecomorphodynamics of aggrading surfaces and modeling vegetated deltaic systems, and the combined influences of plants and discharge variations can act to balance vertical and lateral delta growth.

  18. Single molecule detection, thermal fluctuation and life

    Science.gov (United States)

    YANAGIDA, Toshio; ISHII, Yoshiharu

    2017-01-01

    Single molecule detection has contributed to our understanding of the unique mechanisms of life. Unlike artificial man-made machines, biological molecular machines integrate thermal noises rather than avoid them. For example, single molecule detection has demonstrated that myosin motors undergo biased Brownian motion for stepwise movement and that single protein molecules spontaneously change their conformation, for switching to interactions with other proteins, in response to thermal fluctuation. Thus, molecular machines have flexibility and efficiency not seen in artificial machines. PMID:28190869

  19. Climatically driven fluctuations in Southern Ocean ecosystems.

    Science.gov (United States)

    Murphy, Eugene J; Trathan, Philip N; Watkins, Jon L; Reid, Keith; Meredith, Michael P; Forcada, Jaume; Thorpe, Sally E; Johnston, Nadine M; Rothery, Peter

    2007-12-22

    Determining how climate fluctuations affect ocean ecosystems requires an understanding of how biological and physical processes interact across a wide range of scales. Here we examine the role of physical and biological processes in generating fluctuations in the ecosystem around South Georgia in the South Atlantic sector of the Southern Ocean. Anomalies in sea surface temperature (SST) in the South Pacific sector of the Southern Ocean have previously been shown to be generated through atmospheric teleconnections with El Niño Southern Oscillation (ENSO)-related processes. These SST anomalies are propagated via the Antarctic Circumpolar Current into the South Atlantic (on time scales of more than 1 year), where ENSO and Southern Annular Mode-related atmospheric processes have a direct influence on short (less than six months) time scales. We find that across the South Atlantic sector, these changes in SST, and related fluctuations in winter sea ice extent, affect the recruitment and dispersal of Antarctic krill. This oceanographically driven variation in krill population dynamics and abundance in turn affects the breeding success of seabird and marine mammal predators that depend on krill as food. Such propagating anomalies, mediated through physical and trophic interactions, are likely to be an important component of variation in ocean ecosystems and affect responses to longer term change. Population models derived on the basis of these oceanic fluctuations indicate that plausible rates of regional warming of 1oC over the next 100 years could lead to more than a 95% reduction in the biomass and abundance of krill across the Scotia Sea by the end of the century.

  20. Fluctuation sensitivity of a transcriptional signaling cascade

    Science.gov (United States)

    Pilkiewicz, Kevin R.; Mayo, Michael L.

    2016-09-01

    The internal biochemical state of a cell is regulated by a vast transcriptional network that kinetically correlates the concentrations of numerous proteins. Fluctuations in protein concentration that encode crucial information about this changing state must compete with fluctuations caused by the noisy cellular environment in order to successfully transmit information across the network. Oftentimes, one protein must regulate another through a sequence of intermediaries, and conventional wisdom, derived from the data processing inequality of information theory, leads us to expect that longer sequences should lose more information to noise. Using the metric of mutual information to characterize the fluctuation sensitivity of transcriptional signaling cascades, we find, counter to this expectation, that longer chains of regulatory interactions can instead lead to enhanced informational efficiency. We derive an analytic expression for the mutual information from a generalized chemical kinetics model that we reduce to simple, mass-action kinetics by linearizing for small fluctuations about the basal biological steady state, and we find that at long times this expression depends only on a simple ratio of protein production to destruction rates and the length of the cascade. We place bounds on the values of these parameters by requiring that the mutual information be at least one bit—otherwise, any received signal would be indistinguishable from noise—and we find not only that nature has devised a way to circumvent the data processing inequality, but that it must be circumvented to attain this one-bit threshold. We demonstrate how this result places informational and biochemical efficiency at odds with one another by correlating high transcription factor binding affinities with low informational output, and we conclude with an analysis of the validity of our assumptions and propose how they might be tested experimentally.

  1. Financial Factors, Rare Disasters and Macroeconomic Fluctuations.

    OpenAIRE

    Gruss, Bertrand

    2010-01-01

    Defense date: 25/10/2010 Examining Board: Prof. Giancarlo Corsetti, EUI, Supervisor Prof. Ramon Marimon, EUI Prof. Enrique Mendoza, University of Maryland Prof. Vincenzo Quadrini, University of Southern California This thesis attempts to shed light on the role of financial factors and vulnerabilities in shaping macroeconomic fluctuations. It contributes to the literature that integrates financial factors into the real business cycle paradigm by introducing asymmetries and di...

  2. Thermodynamics and fluctuations far from equilibrium

    CERN Document Server

    Ross, John

    2008-01-01

    This book deals with the formulation of the thermodynamics of chemical and other systems far from equilibrium, including connections to fluctuations. It contains applications to non-equilibrium stationary states and approaches to such states, systems with multiple stationary states, stability and equi-stability conditions, reaction diffusion systems, transport properties, and electrochemical systems. The theoretical treatment is complemented by experimental results to substantiate the formulation. Dissipation and efficiency are analyzed in autonomous and externally forced reactions, including several biochemical systems.

  3. Fluctuations along supersymmetric flat directions during Inflation

    OpenAIRE

    Enqvist, Kari; Figueroa, Daniel G.; Rigopoulos, Gerasimos

    2011-01-01

    We consider a set of scalar fields, consisting of a single flat direction and one or several non-flat directions. We take our cue from the MSSM, considering separately D-flat and F-flat directions, but our results apply to any supersymmetric scenario containing flat directions. We study the field fluctuations during pure de Sitter Inflation, following the evolution of the infrared modes by numerically solving the appropriate Langevin equations. We demonstrate that for the Standard Model U(1),...

  4. Multiplane 3D superresolution optical fluctuation imaging

    OpenAIRE

    Geissbuehler, Stefan; Sharipov, Azat; Godinat, Aurélien; Bocchio, Noelia; Dubikovskaya, Elena; Lasser, Theo; Leutenegger, Marcel

    2013-01-01

    By switching fluorophores on and off in either a deterministic or a stochastic manner, superresolution microscopy has enabled the imaging of biological structures at resolutions well beyond the diffraction limit. Superresolution optical fluctuation imaging (SOFI) provides an elegant way of overcoming the diffraction limit in all three spatial dimensions by computing higher-order cumulants of image sequences of blinking fluorophores acquired with a conventional widefield microscope. So far, th...

  5. Demographic Fluctuation and Institutional Response in Sparta

    OpenAIRE

    DORAN, TIMOTHY DONALD

    2011-01-01

    AbstractDemographic Fluctuation and Institutional Response in SpartabyTimothy Donald DoranDoctor of Philosophy in Ancient History and Mediterranean ArchaeologyUniversity of California, BerkeleyProfessor Emily Mackil, ChairThe Spartiate population declined from 8000 in the early fifth century to less than 1000 in the mid-fourth, and caused Sparta's political fortunes to drop dramatically from being the unofficial hegemon of the Greek-speaking peoples to a strictly local power in the Hellenisti...

  6. Freeze-out conditions from net-proton and net-charge fluctuations at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Alba, Paolo; Alberico, Wanda [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Bellwied, Rene [Department of Physics, University of Houston, Houston, TX 77204 (United States); Bluhm, Marcus [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Mantovani Sarti, Valentina [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Nahrgang, Marlene [Department of Physics, Duke University, Durham, NC 27708-0305 (United States); Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Ratti, Claudia [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy)

    2014-11-10

    We calculate ratios of higher-order susceptibilities quantifying fluctuations in the number of net-protons and in the net-electric charge using the Hadron Resonance Gas (HRG) model. We take into account the effect of resonance decays, the kinematic acceptance cuts in rapidity, pseudo-rapidity and transverse momentum used in the experimental analysis, as well as a randomization of the isospin of nucleons in the hadronic phase. By comparing these results to the latest experimental data from the STAR Collaboration, we determine the freeze-out conditions from net-electric charge and net-proton distributions and discuss their consistency.

  7. Fluctuation microscopy analysis of amorphous silicon models

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, J.M., E-mail: jmgibson@fsu.edu [Northeastern University, Department of Physics, Boston MA 02115 (United States); FAMU/FSU Joint College of Engineering, 225 Pottsdamer Street, Tallahassee, FL 32310 (United States); Treacy, M.M.J. [Arizona State University, Department of Physics, Tempe AZ 85287 (United States)

    2017-05-15

    Highlights: • Studied competing computer models for amorphous silicon and simulated fluctuation microscopy data. • Show that only paracrystalline/random network composite can fit published data. • Specifically show that pure random network or random network with void models do not fit available data. • Identify a new means to measure volume fraction of ordered material. • Identify unreported limitations of the Debye model for simulating fluctuation microscopy data. - Abstract: Using computer-generated models we discuss the use of fluctuation electron microscopy (FEM) to identify the structure of amorphous silicon. We show that a combination of variable resolution FEM to measure the correlation length, with correlograph analysis to obtain the structural motif, can pin down structural correlations. We introduce the method of correlograph variance as a promising means of independently measuring the volume fraction of a paracrystalline composite. From comparisons with published data, we affirm that only a composite material of paracrystalline and continuous random network that is substantially paracrystalline could explain the existing experimental data, and point the way to more precise measurements on amorphous semiconductors. The results are of general interest for other classes of disordered materials.

  8. Stress fluctuations in sheared Stokesian suspensions.

    Science.gov (United States)

    Dasan, J; Ramamohan, T R; Singh, Anugrah; Nott, Prabhu R

    2002-08-01

    We report an analysis, using the tools of nonlinear dynamics and chaos theory, of the fluctuations in the stress determined from simulations of shear flow of Stokesian suspensions. The simulations are for shear between plane parallel walls of a suspension of rigid identical spheres in a Newtonian fluid, over a range of particle concentration. By analyzing the time series of the stress, we find that the dynamics underlying these fluctuations is deterministic, low-dimensional, and chaotic. We use the dynamic and metric invariants of the underlying dynamics as a means of characterizing suspension behavior. The dimension of the chaotic attractor increases with particle concentration, indicating the increasing influence of multiple-body interactions on the rheology of the suspension with rise in particle concentration. We use our analysis to make accurate predictions of the short-term evolution of a stress component from its preceding time series, and predict the evolution of one component of the stress using the time series of another. We comment on the physical origin of the chaotic stress fluctuations, and on the implications of our results on the relation between the microstructure and the stress.

  9. Water-level fluctuations influence sediment porewater ...

    Science.gov (United States)

    Reservoirs typically have elevated fish mercury (Hg) levels compared to natural lakes and rivers. A unique feature of reservoirs is water-level management which can result in sediment exposure to the air. The objective of this study is to identify how reservoir water-level fluctuations impact Hg cycling, particularly the formation of the more toxic and bioaccumulative methylmercury (MeHg). Total-Hg (THg), MeHg, stable isotope methylation rates and several ancillary parameters were measured in reservoir sediments (including some in porewater and overlying water) that are seasonally and permanently inundated. The results showed that sediment and porewater MeHg concentrations were over 3-times higher in areas experiencing water-level fluctuations compared to permanently inundated sediments. Analysis of the data suggest that the enhanced breakdown of organic matter in sediments experiencing water-level fluctuations has a two-fold effect on stimulating Hg methylation: 1) it increases the partitioning of inorganic Hg from the solid phase into the porewater phase (lower log Kd values) where it is more bioavailable for methylation; and 2) it increases dissolved organic carbon (DOC) in the porewater which can stimulate the microbial community that can methylate Hg. Sulfate concentrations and cycling were enhanced in the seasonally inundated sediments and may have also contributed to increased MeHg production. Overall, our results suggest that reservoir management a

  10. Behavior of axisymmetric density fluctuations in TCV

    Science.gov (United States)

    Merlo, Gabriele; Jenko, Frank; Brunner, Stephan; Coda, Stefano; Huang, Zhouji; Villard, Laurent; Goerler, Tobias; Navarro, Alejandro B.; Told, Daniel

    2017-10-01

    Axisymmetric density fluctuations, either with a radially coherent or dispersive nature, are routinely observed in the TCV tokamak and experimentally interpreted as Geodesic Acoustic Modes (GAMs). We use local and global GENE simulations to investigate their behavior. With a simplified physical model, neglecting impurities and using heavy electrons, simulations reproduce the observed behavior. Simulations allow to conclude that the modification of the safety factor q alone cannot explain the transition between these two different fluctuation regimes, which thus appear as a consequence of variations of other parameters, including collisionality and finite machine size effects. The behavior of the radially coherent GAM is further investigated with high-realism GENE simulations. With this set-up, local simulations reproduce the experimental transport level at different radii while matching the observed GAM frequency at the location where the mode peaks. Global high-realism runs, aiming at reproducing the radial extent of the fluctuations, will be discussed as well. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under Grant Agreement No 633053.

  11. Fluctuation of Ultrafiltration Coefficient of Hemodialysis Membrane During Reuse

    Science.gov (United States)

    Arif, Idam; Christin

    2010-12-01

    Hemodialysis treatment for patient with kidney failure is to regulate body fluid and to excrete waste products of metabolism. The patient blood and the dialyzing solution (dialysate) are flowed counter currently in a dialyzer to allow volume flux of fluid and diffusion of solutes from the blood to the dialysate through a semipermiable membrane. The volume flux of fluid depends on the hydrostatic and the osmotic pressure difference between the blood and the dialysate. It also depends on the membrane parameter that represents how the membrane allows the fluid and the solutes to move across as a result of the pressure difference, known as the ultrafiltration coefficient Kuf. The coefficient depends on the number and the radius of membrane pores for the movement of the fluids and the solutes across the membrane. The measured membrane ultrafiltration coefficient of reused dialyzer shows fluctuation between one uses to another without any significant trend of change. This indicates that the cleaning process carried out before reuse does not cause perfect removal of clots that happen in the previous use. Therefore the unblocked pores are forced to work hardly to obtain targeted volume flux in a certain time of treatment. This may increase the unblocked pore radius. Reuse is stopped when there is indication of blood leakage during the hemodialysis treatment.

  12. The Effect of Climate, Environment and Man on Variations in Wildlife Population Fluctuations in Greenland Over 200 Years

    DEFF Research Database (Denmark)

    Moshøj, Charlotte Margaret

    2008-01-01

    The Effect of Climate, Environment and Man on Variations in Wildlife Population Fluctuations in Greenland Over 200 Years Moshøj, Charlotte The underlying factors of species fluctuating population dynamics has been the dominant focus of attention in population ecology throughout much of this century...... in the harvests of individual species are believed to be related to changes in climate, as well as variations in hunting pressure. Dating back 200 years, these hunting records therefore represent a unique time series for retrospective modelling of annual and decadal fluctuations in relation to long-term climatic...... data, environmental factors and temporal variations in social and demographic parameters in the existing society. The results of this study model future predictions of wildlife populations under changing climate variables and human hunting pressure. View Presentation....

  13. Fluctuation-Noise Model for PEM Fuel Cell

    Science.gov (United States)

    Denisov, E. S.; Salakhova, A. Sh.; Adiutantov, N. A.; Evdokimov, Yu. K.

    2017-08-01

    The fluctuation-noise model is presented. This model allows to describe the power spectral density of PEM fuel cell electrical fluctuation. The proposed model can be used for diagnostics of PEM fuel cell state of health.

  14. Experimental setup for rapid crystallization using favoured chemical ...

    Indian Academy of Sciences (India)

    Unknown

    tors (3005 type), the output of which drives the d.c. motor. M3. The solution of ... to motor M1 prevents rapid temperature fluctuations and hence ensures very good temperature control. The thermostatic bath is heated with an infrared lamp I at the base of the unit and ... through chains of hydrogen bonds and these polymers.

  15. The Origin of the Density Fluctuations in De Sitter Space

    Science.gov (United States)

    Morikawa, M.

    1987-05-01

    As the origin of the large scale structure in the universe, statistical fluctuations of a c-number scalar field are evaluated on the basis of the double time-contour path integral method. The source of the fluctuation is a backreaction of spontaneous particle production in de Sitter space. The evaluated fluctuations are quite different from the ordinary quantum fluctuations and are proportional to the particle production rate.

  16. Experimental study of wind-induced pressures on buildings of ...

    African Journals Online (AJOL)

    same plan area and height but having the different dimensions were tested in a closed circuit wind tunnel under boundary layer flow. The models were made from Perspex sheets at a geometrical scale of 1:300. Fluctuating values of wind pressures are measured at pressure points on all the sides of the models and mean, ...

  17. Common Origin of Quantum Regression and Quantum Fluctuation Dissipation Theorems

    OpenAIRE

    Shiktorov, P.; Starikov, E.; Gruzinskis, V.; Reggiani, L.; L. Varani; Vaissiere, J. C.

    2000-01-01

    It is shown that the quantum fluctuation dissipation theorem can be considered as a mathematical formulation in the spectral representation of Onsager hypothesis on the regression of fluctuations in physical systems. It is shown that the quantum fluctuation dissipation theorem can be generalized to an arbitrary stationary state.

  18. Correlations and Fluctuations, A Summary of Quark Matter 2002

    OpenAIRE

    Pratt, Scott

    2003-01-01

    Results for correlations and fluctuations presented at Quark Matter 2002 are summarized. These results include Hanbury-Brown Twiss interferometry of a wide variety of species, large scale fluctuations and correlations in $p_t$ and multiplicity, and charge fluctuations and charge balance functions.

  19. The new IGS ionospheric product - TEC fluctuation maps and their scientific application

    Science.gov (United States)

    Krankowski, Andrzej; Cherniak, Iurii; Zakharenkova, Irina

    2017-04-01

    The GPS signals fading due to presence of the plasma irregularities in the ionosphere can decrease an operational availability of navigation systems. This effect can be estimated by measuring its impact on phase of the received GPS signal. The new IGS ionospheric fluctuation maps product is based on estimates of the TEC rapid changes. For an overall representation of the spatial evolution of the ionospheric irregularities, which caused the GPS signal fluctuations over the Northern Hemisphere in middle and high latitudes, a daily map of the ROTI index is produced basing on data derived from a representative set of 700 permanent GPS stations. We use the corrected geomagnetic (CGM) coordinates with DGRF/IGRF models. For daily ROTI maps, we averaged and binned all ROTI values collected during 00-24 UT period of a considered day. The grid size is 8 min MLT by 2° MLAT, with the latter covering 50° - 90°. The averaged ROTI value in each MLAT-MLT bin corresponds to probability of the GPS signals phase fluctuations caused by passing of radio signals through the ionospheric irregularities. The resulted ionospheric fluctuation product is represented in the ASCII IONEX-like data format and can be visualized. This data format is described in details. We demonstrate the IGS ionospheric fluctuation map product performance for scientific research application on set of test-cases (geomagnetic storms occurred in the years 2013-2015) for comparative analysis of the resulted daily ROTI maps for quiet and geomagnetically disturbed periods. The intense phase scintillations depicted in the diurnal ROTI maps can provide an important information about development of the severe storm-induced gradients in the ionospheric plasma density, both caused by auroral particle precipitation and plasma flows. It is possible to conclude that IGS ionospheric fluctuation maps product can be effectively used for monitoring of the plasma irregularities with different origin. The independent ground

  20. Pressure and temperature effects in homopolymer blends and diblock copolymers

    DEFF Research Database (Denmark)

    Frielinghaus, H.; Schwahn, D.; Mortensen, K.

    1997-01-01

    fluctuations. Phase boundaries, the Flory-Huggins interaction parameter and the Ginzburg number were obtained. The packing of the molecules changes with pressure. Therefore, the degree of thermal fluctuation as a function of packing and temperature was studied. While in polymer blends packing leads, in some......Thermal composition fluctuations in a homogeneous binary polymer blend and in a diblock copolymer were measured by small-angle neutron scattering as a function of temperature and pressure. The experimental data were analyzed with theoretical expressions, including the important effect of thermal...... of the 'mean-field' approximation and the three-dimensional Ising model. The phase boundaries in blends increase with pressure, while the phase boundary of the studied block copolymer shows an unusual shape: with increasing pressure it first decreases and then increases. Its origin is an increase...

  1. Role of valence fluctuations in the superconductivity of Ce122 compounds.

    Science.gov (United States)

    Yamaoka, H; Ikeda, Y; Jarrige, I; Tsujii, N; Zekko, Y; Yamamoto, Y; Mizuki, J; Lin, J-F; Hiraoka, N; Ishii, H; Tsuei, K-D; Kobayashi, T C; Honda, F; Onuki, Y

    2014-08-22

    Pressure dependence of the Ce valence in CeCu(2)Ge(2) has been measured up to 24 GPa at 300 K and to 17 GPa at 18-20 K using x-ray absorption spectroscopy in the partial fluorescence yield. A smooth increase of the Ce valence with pressure is observed across the two superconducting (SC) regions without any noticeable irregularity. The chemical pressure dependence of the Ce valence was also measured in Ce(Cu(1-x)Ni(x))(2)Si(2) at 20 K. A very weak, monotonic increase of the valence with x was observed, without any significant change in the two SC regions. Within experimental uncertainties, our results show no evidence for the valence transition with an abrupt change in the valence state near the SC II region, challenging the valence-fluctuation mediated superconductivity model in these compounds at high pressure and low temperature.

  2. ON THE NATURE OF X-RAY SURFACE BRIGHTNESS FLUCTUATIONS IN M87

    Energy Technology Data Exchange (ETDEWEB)

    Arévalo, P. [Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretana N 1111, Playa Ancha, Valparaíso (Chile); Churazov, E. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85741 Garching (Germany); Zhuravleva, I. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Forman, W. R.; Jones, C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

    2016-02-10

    X-ray images of galaxy clusters and gas-rich elliptical galaxies show a wealth of small-scale features that reflect fluctuations in density and/or temperature of the intracluster medium. In this paper we study these fluctuations in M87/Virgo to establish whether sound waves/shocks, bubbles, or uplifted cold gas dominate the structure. We exploit the strong dependence of the emissivity on density and temperature in different energy bands to distinguish between these processes. Using simulations we demonstrate that our analysis recovers the leading type of fluctuation even in the presence of projection effects and temperature gradients. We confirm the isobaric nature of cool filaments of gas entrained by buoyantly rising bubbles, extending to 7′ to the east and southwest, and the adiabatic nature of the weak shocks at 40″ and 3′ from the center. For features of ∼5–10 kpc, we show that the central 4′ × 4′ region is dominated by cool structures in pressure equilibrium with the ambient hotter gas while up to 30% of the variance in this region can be ascribed to adiabatic fluctuations. The remaining part of the central 14′ × 14′ region, excluding the arms and shocks described above, is dominated by apparently isothermal fluctuations (bubbles) with a possible admixture (at the level of ∼30%) of adiabatic (sound waves) and by isobaric structures. Larger features, of about 30 kpc, show a stronger contribution from isobaric fluctuations. The results broadly agree with a model based on feedback from an active galactic nucleus mediated by bubbles of relativistic plasma.

  3. Curvature of fluctuation geometry and its implications on Riemannian fluctuation theory

    Science.gov (United States)

    Velazquez, L.

    2013-08-01

    Fluctuation geometry was recently proposed as a counterpart approach of the Riemannian geometry of inference theory (widely known as information geometry). This theory describes the geometric features of the statistical manifold {M} of random events that are described by a family of continuous distributions dp(x|θ). A main goal of this work is to clarify the statistical relevance of the Levi-Civita curvature tensor Rijkl(x|θ) of the statistical manifold {M}. For this purpose, the notion of irreducible statistical correlations is introduced. Specifically, a distribution dp(x|θ) exhibits irreducible statistical correlations if every distribution dp(\\check{x}|\\theta ) obtained from dp(x|θ) by considering a coordinate change \\check{x}=\\phi (x) cannot be factorized into independent distributions as dp(\\check{x}|\\theta )=\\prod _{i}dp^{(i)}(\\check{x}^{i}|\\theta ). It is shown that the curvature tensor Rijkl(x|θ) arises as a direct indicator about the existence of irreducible statistical correlations. Moreover, the curvature scalar R(x|θ) allows us to introduce a criterium for the applicability of the Gaussian approximation of a given distribution function. This type of asymptotic result is obtained in the framework of the second-order geometric expansion of the distribution family dp(x|θ), which appears as a counterpart development of the high-order asymptotic theory of statistical estimation. In physics, fluctuation geometry represents the mathematical apparatus of a Riemannian extension for Einstein’s fluctuation theory of statistical mechanics. Some exact results of fluctuation geometry are now employed to derive the invariant fluctuation theorems. Moreover, the curvature scalar allows us to express some asymptotic formulae that account for the system fluctuating behavior beyond the Gaussian approximation, e.g.: it appears as a second-order correction of the Legendre transformation between thermodynamic potentials, P(\\theta )=\\theta _{i

  4. Pressure pulsations on a flat plate normal to an underexpanded supersonic jet

    Science.gov (United States)

    Back, L. H.; Sarohia, V.

    1978-01-01

    An experiment was devised to study the interaction between an underexpanded supersonic gas jet and a flat plate, with the plate located in a region in which the interaction produces shock wave and flow fluctuations. Nitrogen gas at ambient stagnation temperature flowed through a convergent nozzle with exit diameter of 2.03 cm and impinged on a square metal plate normal to the jet. Results revealed local peak pressure fluctuations on the plate at nozzle pressure ratios of about 2 and 4.5, with the latter case producing fluctuations of the same order as the mean pressure on the plate; the frequency of the oscillations was as large as 20 kHz. For choked jet flow at ambient pressure higher than atmospheric, the pressure fluctuations would increase accordingly, and adjacent solid structures would therefore be subjected to proportionately higher normal stresses.

  5. Sources of Economic Fluctuations in Central America

    Directory of Open Access Journals (Sweden)

    Wilfredo Toledo

    2014-06-01

    Full Text Available Using panel data from Central America, this paper studies the determining factors of inflation and aggregate output fluctuations by estimating two Structural Vector Autoregressive (SVAR models. Price and output variables are included in one of the models, whereas M2 and the price of oil are additional variables in the other one. Findings of this study suggest that price is determined by the demand, while output seems to be influenced mainly by the supply shocks in that area. It was also evidenced that the price of oil does not have a significant impact on the general price level in that region.

  6. Fluctuations of wavefunctions about their classical average

    CERN Document Server

    Bénet, L; Hernandez-Saldana, H; Izrailev, F M; Leyvraz, F; Seligman, T H

    2003-01-01

    Quantum-classical correspondence for the average shape of eigenfunctions and the local spectral density of states are well-known facts. In this paper, the fluctuations of the quantum wavefunctions around the classical value are discussed. A simple random matrix model leads to a Gaussian distribution of the amplitudes whose width is determined by the classical shape of the eigenfunction. To compare this prediction with numerical calculations in chaotic models of coupled quartic oscillators, we develop a rescaling method for the components. The expectations are broadly confirmed, but deviations due to scars are observed. This effect is much reduced when both Hamiltonians have chaotic dynamics.

  7. Fluctuation Solution Theory Properties from Molecular Simulation

    DEFF Research Database (Denmark)

    Abildskov, Jens; Wedberg, R.; O’Connell, John P.

    2013-01-01

    The thermodynamic properties obtained in the Fluctuation Solution Theory are based on spatial integrals of molecular TCFs between component pairs in the mixture. Molecular simulation, via either MD or MC calculations, can yield these correlation functions for model inter- and intramolecular...... potential functions. However, system-size limitations and statistical noise cause uncertainties in the functions at long range, and thus uncertainties or errors in the integrals. A number of methods such as truncation, distance shifting, long-range modeling, transforms, DCF matching, finite-size scaling...

  8. Sample size determination for the fluctuation experiment.

    Science.gov (United States)

    Zheng, Qi

    2017-01-01

    The Luria-Delbrück fluctuation experiment protocol is increasingly employed to determine microbial mutation rates in the laboratory. An important question raised at the planning stage is "How many cultures are needed?" For over 70 years sample sizes have been determined either by intuition or by following published examples where sample sizes were chosen intuitively. This paper proposes a practical method for determining the sample size. The proposed method relies on existing algorithms for computing the expected Fisher information under two commonly used mutant distributions. The role of partial plating in reducing sample size is discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Classical fluctuations in quantum field theory

    Science.gov (United States)

    Morikawa, M.

    The question as to whether quantum fluctuations can induce the spontaneous breaking of translational invariance (SBTI) in the extreme cosmic expansion that occurs during any type of inflation is considered. Attention is given to the unstable field, thermofield dynamic, and cosmic anisotropic relaxation quantum systems, defining the appropriate order parameters for each and discussing their properties. A mechanism for SBTI is presented which possesses both generality and applicability to various problems; a complex effective potential can, for example, be obtained for a nonconvex potential, so that a random force arises and stochastically agitates order parameters.

  10. Universality and Specificity in Protein Fluctuation Dynamics

    Science.gov (United States)

    Copperman, J.; Dinpajooh, M.; Beyerle, E. R.; Guenza, M. G.

    2017-10-01

    We investigate the universal scaling of protein fluctuation dynamics with a site-specific diffusive model of protein motion, which predicts an initial subdiffusive regime in the configurational relaxation. The long-time dynamics of proteins is controlled by an activated regime. We argue that the hierarchical free energy barriers set the time scales of biological processes and establish an upper limit to the size of single protein domains. We find it compelling that the scaling behavior for the protein dynamics is in close agreement with the Kardar-Parisi-Zhang scaling exponents.

  11. Universal fluctuations the phenomenology of hadronic matter

    CERN Document Server

    Botet, Robert

    2002-01-01

    The main purpose of this book is to present, in a comprehensive and progressive way, the appearance of universal limit probability laws in physics, and their connection with the recently developed scaling theory of fluctuations. Arising from the probability theory and renormalization group methods, this novel approach has been proved recently to provide efficient investigative tools for the collective features that occur in any finite system. The mathematical background is self-contained and is formulated in terms which are easy to apply to the physical context. After illustrating the problem

  12. Detrended fluctuation analysis of multivariate time series

    Science.gov (United States)

    Xiong, Hui; Shang, P.

    2017-01-01

    In this work, we generalize the detrended fluctuation analysis (DFA) to the multivariate case, named multivariate DFA (MVDFA). The validity of the proposed MVDFA is illustrated by numerical simulations on synthetic multivariate processes, where the cases that initial data are generated independently from the same system and from different systems as well as the correlated variate from one system are considered. Moreover, the proposed MVDFA works well when applied to the multi-scale analysis of the returns of stock indices in Chinese and US stock markets. Generally, connections between the multivariate system and the individual variate are uncovered, showing the solid performances of MVDFA and the multi-scale MVDFA.

  13. Rapidly rotating red giants

    Science.gov (United States)

    Gehan, Charlotte; Mosser, Benoît; Michel, Eric

    2017-10-01

    Stellar oscillations give seismic information on the internal properties of stars. Red giants are targets of interest since they present mixed modes, wich behave as pressure modes in the convective envelope and as gravity modes in the radiative core. Mixed modes thus directly probe red giant cores, and allow in particular the study of their mean core rotation. The high-quality data obtained by CoRoT and Kepler satellites represent an unprecedented perspective to obtain thousands of measurements of red giant core rotation, in order to improve our understanding of stellar physics in deep stellar interiors. We developed an automated method to obtain such core rotation measurements and validated it for stars on the red giant branch. In this work, we particularly focus on the specific application of this method to red giants having a rapid core rotation. They show complex spectra where it is tricky to disentangle rotational splittings from mixed-mode period spacings. We demonstrate that the method based on the identification of mode crossings is precise and efficient. The determination of the mean core rotation directly derives from the precise measurement of the asymptotic period spacing ΔΠ1 and of the frequency at which the crossing of the rotational components is observed.

  14. Fluctuation functions in aqueous NaCl and urea.

    Science.gov (United States)

    Siu, David; Koga, Yoshikata

    2005-09-08

    We earlier devised a set of fluctuation functions that provide relative qualitative differences of the amplitude (intensity) and the wavelength (extensity) of fluctuations in entropy and volume and the entropy-volume cross fluctuations. We discuss the mixing schemes in aqueous NaCl and urea using these fluctuation functions. Our earlier studies by using the second and third derivatives of Gibbs energy indicated that their effects on H2O are qualitatively different. An NaCl hydrates 7.5 molecules of H2O but leaves the bulk H2O away from the hydration shell unperturbed. Urea, on the other hand, connects onto the hydrogen bond network of H2O but retards the degree of fluctuation inherent in H2O. The behavior of the fluctuation functions calculated here are consistent with the above mixing schemes. Furthermore, urea was found to reduce the wavelength of fluctuation more strongly than NaCl.

  15. Energy dependence of multiplicity fluctuations in heavy ion collisions at the CERN SPS

    CERN Document Server

    Lungwitz, Benjamin

    2008-01-01

    In this work data of the NA49 experiment at CERN SPS on the energy dependence of multiplicity fluctuations in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV, as well as the system size dependence at 158A GeV, is analysed for positively, negatively and all charged hadrons. Furthermore the rapidity and transverse momentum dependence of multiplicity fluctuations are studied. The experimental results are compared to predictions of statistical hadron-gas and string-hadronic models. It is expected that multiplicity fluctuations are sensitive to the phase transition to quark-gluon-plasma (QGP) and to the critical point of strongly interacting matter. It is predicted that both the onset of deconfinement, the lowest energy where QGP is created, and the critical point are located in the SPS energy range. Furthermore, the predictions for the multiplicity fluctuations of statistical and string-hadronic models are different, the experimental data might allow to distinguish between them. The used measure of mu...

  16. Rapid Response Concentration-Controlled Desorption of Activated Carbon to Dampen Concentration Fluctuations

    Science.gov (United States)

    2007-01-01

    will be much smaller and will sustain a much more stable microbial population because the microorganisms will not experience starvation during times...activated carbon biofilter. Bioprocess Eng. 1997, 16, 331-337. (10) Weber, F. J.; Hartmans, S. Use of activated carbon as a buffer in biofiltration of waste

  17. A physiological role of cyclic electron transport around photosystem I in sustaining photosynthesis under fluctuating light in rice.

    Science.gov (United States)

    Yamori, Wataru; Makino, Amane; Shikanai, Toshiharu

    2016-02-02

    Plants experience a highly variable light environment over the course of the day. To reveal the molecular mechanisms of their photosynthetic response to fluctuating light, we examined the role of two cyclic electron flows around photosystem I (CEF-PSI)--one depending on PROTON GRADIENT REGULATION 5 (PGR5) and one on NADH dehydrogenase-like complex (NDH)--in photosynthetic regulation under fluctuating light in rice (Oryza sativa L.). The impairment of PGR5-dependent CEF-PSI suppressed the photosynthetic response immediately after sudden irradiation, whereas the impairment of NDH-dependent CEF-PSI did not. However, the impairment of either PGR5-dependent or NDH-dependent CEF-PSl reduced the photosynthetic rate under fluctuating light, leading to photoinhibition at PSI and consequently a reduction in plant biomass. The results highlight that (1) PGR5-dependent CEF-PSI is a key regulator of rapid photosynthetic responses to high light intensity under fluctuating light conditions after constant high light; and (2) both PGR5-dependent and NDH-dependent CEF-PSI have physiological roles in sustaining photosynthesis and plant growth in rice under repeated light fluctuations. The highly responsive regulatory system managed by CEF-PSI appears able to optimize photosynthesis and plant growth under naturally fluctuating light conditions.

  18. Fluctuating wall shear stress and velocity measurements in a turbulent boundary layer

    Science.gov (United States)

    Pabon, Rommel; Ukeiley, Lawrence; Barnard, Casey; Sheplak, Mark

    2014-11-01

    Knowledge of mean wall shear stress on a surface can shed light on important performance parameters, but the fluctuating shear, even in simple flows, has not been as easily measured, and can be of interest in fundamental boundary layer research. Experiments on a flat plate model were performed to investigate the relationship between the wall shear stress and large scale events in the turbulent boundary layer. A MEMS based differential capacitance shear stress system with 1 mm × 1 mm floating element which can measure the fluctuating and static components of shear simultaneously, coupled with a hot wire anemometer were used for characterizing the turbulent boundary layer. Velocity profiles and turbulence statistics approaching the wall characterized the two dimensionality of the flat plate, and a trailing edge flap was used to impose a zero pressure gradient. The mean streamwise velocity profile was scaled by the friction velocity using the measured shear stress and independently compared to classical fits. Correlations between the fluctuating shear and measured velocities were used to elucidate the large scale events and to compare with previous fluctuating shear measurements for validation.

  19. Temperature fluctuations underneath the ice in Diamond Lake, Hennepin County, Minnesota

    Science.gov (United States)

    Kletetschka, Gunther; Fischer, Tomas; Mls, Jiří; DěDeček, Petr

    2013-06-01

    Diamond Lake in Minnesota is covered every winter with ice and snow providing a modified thermal insulation between water and air. Autonomous temperature sensors, data loggers, were placed in this lake so that hourly measurements could be obtained from the snow-covered ice and water. The sensors that became frozen measured damped and delayed thermal response from the air-temperature fluctuation. Those sensors that were deeper within the snow-covered ice measured continuous, almost constant, temperature values near freezing. Several of them were within the liquid water and responded with a fluctuation of 24 h periods of amplitudes up to 0.2°C. Our analysis of the vertical temperature profiles suggested that the source of periodic water heating comes from the lake bottom. Because of the absence of daily temperature variations of the snow-covered ice, the influence of the air-temperature fluctuation can be ruled out. We attribute the heating process to the periodic inflow of groundwater to the lake and the cooling to the heat diffusion to the overlying ice cover. The periodic groundwater inflow is interpreted due to solid Earth tides, which cause periodic fluctuations of the groundwater pressure head.

  20. Velocity-pressure correlation measurements in complex free shear flows

    Energy Technology Data Exchange (ETDEWEB)

    Naka, Yoshitsugu [Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-city 223-8522 (Japan)], E-mail: y09774@educ.cc.keio.ac.jp; Obi, Shinnosuke [Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-city 223-8522 (Japan)], E-mail: obsn@mech.keio.ac.jp

    2009-06-15

    Simultaneous measurements of fluctuating velocity and pressure were performed in various turbulent free shear flows including a turbulent mixing layer and the wing-tip vortex trailing from a NACA0012 half-wing. Two different methods for fluctuating static pressure measurement were considered: a direct method using a miniature Pitot tube and an indirect method where static pressure was calculated from total pressure. The pressure obtained by either of these methods was correlated with the velocity measured by an X-type hot-wire probe. The results from these two techniques agreed with each other in the turbulent mixing layer. In the wing-tip vortex case, however, some discrepancies were found, although overall characteristics of the pressure-related statistics were adequately captured by both methods.

  1. THE EFFECT OF RESERVOIR WATER LEVEL FLUCTUATION TO THE SEEPAGE ON EARTH DAM

    Directory of Open Access Journals (Sweden)

    H. Sudardja

    2012-06-01

    Full Text Available The modeling of earth dam was carried out in a drainage and seepage tank to analyze the seepage resulting from water level fluctuation in the upstream of the dam. The dam models were made of the mixture of Mt. Merapi sand deposit with the soil of sandy-silt from Wonosari area. The variations of sand content in the mixture were 100%; 90% and 80% and the upstream slope inclinations were 1:1; 1:1.5 and 1:2. The result showed that the dams with more sandy-silt in the mixture have smaller seepage and the dams with steeper upstream slope have greater seepage. During rapid rising of water level, the dams with steeper upstream slope have a high rising rate of upstream water level and higher height of downstream slope failure. Moreover, during rapid drawdown, the dams with gentler upstream slope have a smaller rate of upstream drawdown and lower height of upstream slope failure. The dams with more sandy-silt in the mixture have a higher value of rising rate and drawdown of upstream water level but lower height of downstream and upstream slope failure. In the dam management, continuous monitoring of the seepage resulting from reservoir water level fluctuation is required to avoid dam failure. Keywords: Earth dam, rapid rising, rapid drawdown, seepage, slope failure.

  2. Development and validation of the pressure surge computer code DYVRO mod. 3

    Energy Technology Data Exchange (ETDEWEB)

    Neuhaus, T.; Schaffrath, A. [TUEV NORD Systec GmbH und Co. KG, Hamburg (Germany); Altstadt, E. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (DE). Inst. fuer Sicherheitsforschung (IFS)

    2008-11-15

    Pressure fluctuations are generated in pipeline systems, when a fluid is rapidly accelerated or decelerated by fast closing or opening a valve, pump trip or start, breaking of pipes etc. TUEV NORD SysTec GmbH and Co. KG performs calculations of pressure surges in power plants and especially in nuclear power plants for many years. For this reason TUEV NORD has developed and qualified the pressure surge computer code DYVRO. This contribution describes in detail the actual code version DYVRO mod. 3 that has been modified with regard to the system of partial differential equations and the numerical scheme. Also the validation against representative experiments like the Simpson's experiment and an experiment at the Cold Water Hammer Test Facility CWHTF is shown. Results of DYVRO calculations are afterwards compared with results of own and external simulations with system codes (ATHLET and RELAP5) and with the pressure surge code WAHA. For this purpose the outcome of the EU project WAHALOADS that was supported within the 5{sup th} framework programme has been used. (orig.)

  3. Normal-pressure microwave rapid synthesis of hierarchical SnO₂@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials.

    Science.gov (United States)

    Yin, Li; Chen, Deliang; Cui, Xue; Ge, Lianfang; Yang, Jing; Yu, Lanlan; Zhang, Bing; Zhang, Rui; Shao, Guosheng

    2014-11-21

    Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn(2+) ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m(2) g(-1) consists of 92 mass% SnO2 NPs and ∼8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets.

  4. Normal-pressure microwave rapid synthesis of hierarchical SnO2@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials

    Science.gov (United States)

    Yin, Li; Chen, Deliang; Cui, Xue; Ge, Lianfang; Yang, Jing; Yu, Lanlan; Zhang, Bing; Zhang, Rui; Shao, Guosheng

    2014-10-01

    Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn2+ ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m2 g-1 consists of 92 mass% SnO2 NPs and ~8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets.

  5. SOL width and intermittent fluctuations in KSTAR

    Directory of Open Access Journals (Sweden)

    O.E. Garcia

    2017-08-01

    Full Text Available Radial profiles of the ion saturation current and its fluctuation statistics are presented from probe measurements in L-mode, neutral beam heated plasmas at the outboard mid-plane region of KSTAR. The results are consistent with the familiar two-layer structure, seen elsewhere in tokamak L-mode discharges, with a steep near-SOL profile and a broad far-SOL profile. The profile scale length in the far-SOL increases drastically with line-averaged density, thereby enhancing plasma interactions with the main chamber walls. Time series from the far-SOL region are characterised by large-amplitude bursts attributed to the radial motion of blob-like plasma filaments. Analysis of a data time series of several seconds duration under stationary plasma conditions reveals the statistical properties of these fluctuations, including the rate of level crossings and the average duration of periods spent above a given threshold level. This is shown to be in excellent agreement with predictions of a stochastic model, giving novel predictions of plasma–wall interactions due to transient transport events.

  6. 5th International Conference on Valence Fluctuations

    CERN Document Server

    Malik, S

    1987-01-01

    During the Koln meeting (August 28-31, 1984), Irdia was chosen as the venue for the next International Conference on Valence Fluctuations. lhis was in recognition ard appreciation of the work done, both experimental ard theoretical, by the Irdian scientists in this area during the last decade. We decided to hold this Conference in the month of January, 1987 at Bangalore. lhe subject of Valence Fluctuations has kept itself alive ard active as it has provided many shocks ard suprises particularly among the Ce- ard U-based intermetallies. lhe richness of many interesting physical phenomena occurring in mixed valent materials, the flexibility of modifying their physical properties (by alloying, for example) ard the possibility of synthesizing a wide variety of new such materials seem to be the key factors in this regard. Barely six months before this Conference, an International Conference on Anomalous Rare Earths and Actinides (ICAREA) had been held at Grenoble (July, 1986) which also focussed on mixed valence a...

  7. SOL width and intermittent fluctuations in KSTAR

    CERN Document Server

    Garcia, O E; Theodorsen, A; Bak, J -G; Hong, S -H; Kim, H -S; Pitts, R A

    2016-01-01

    Radial profiles of the ion saturation current and its fluctuation statistics are presented from probe measurements in L-mode, neutral beam heated plasmas at the outboard mid-plane region of KSTAR. The familiar two-layer structure, seen elsewhere in tokamak L-mode discharges, with a steep near-SOL profile and a broad far-SOL profile, is observed. The profile scale length in the far-SOL increases drastically with line-averaged density, thereby enhancing plasma interactions with the main chamber walls. Time series from the far-SOL region are characterised by large-amplitude bursts attributed to the radial motion of blob-like plasma filaments. Analysis of a data time series of several seconds duration under stationary plasma conditions reveals the statistical properties of these fluctuations, including the rate of level crossings and the average duration of periods spent above a given threshold level. This is shown to be in excellent agreement with predictions of a stochastic model, giving novel predictions of pl...

  8. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  9. Fluctuations When Driving Between Nonequilibrium Steady States

    Science.gov (United States)

    Riechers, Paul M.; Crutchfield, James P.

    2017-08-01

    Maintained by environmental fluxes, biological systems are thermodynamic processes that operate far from equilibrium without detailed-balanced dynamics. Yet, they often exhibit well defined nonequilibrium steady states (NESSs). More importantly, critical thermodynamic functionality arises directly from transitions among their NESSs, driven by environmental switching. Here, we identify the constraints on excess heat and dissipated work necessary to control a system that is kept far from equilibrium by background, uncontrolled "housekeeping" forces. We do this by extending the Crooks fluctuation theorem to transitions among NESSs, without invoking an unphysical dual dynamics. This and corresponding integral fluctuation theorems determine how much work must be expended when controlling systems maintained far from equilibrium. This generalizes thermodynamic feedback control theory, showing that Maxwellian Demons can leverage mesoscopic-state information to take advantage of the excess energetics in NESS transitions. We also generalize an approach recently used to determine the work dissipated when driving between functionally relevant configurations of an active energy-consuming complex system. Altogether, these results highlight universal thermodynamic laws that apply to the accessible degrees of freedom within the effective dynamic at any emergent level of hierarchical organization. By way of illustration, we analyze a voltage-gated sodium ion channel whose molecular conformational dynamics play a critical functional role in propagating action potentials in mammalian neuronal membranes.

  10. Quantum fluctuations of voltage in superconducting nanowires

    Science.gov (United States)

    Semenov, Andrew G.; Zaikin, Andrei D.

    2017-07-01

    At low temperatures non-equilibrium voltage fluctuations can be generated in current-biased superconducting nanowires due to proliferation of quantum phase slips (QPS) or, equivalently, due to quantum tunneling of magnetic flux quanta across the wire. In this paper we review and further extend recent theoretical results related to this phenomenon. Employing the phase-charge duality arguments combined with Keldysh path integral technique we analyze such fluctuations within the two-point and four-point measurement schemes demonstrating that voltage noise detected in such nanowires in general depends on the particular measurement setup. In the low frequency limit we evaluate all cumulants of the voltage operator which turn out to obey Poisson statistics and exhibit a power law dependence on the external bias. We also specifically address a non-trivial frequency dependence of quantum shot noise power spectrum SΩ for both longer and shorter superconducting nanowires. In particular, we demonstrate that SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T → 0. Furthermore, we predict that SΩ may depend non-monotonously on temperature due to quantum coherent nature of QPS noise. The results of our theoretical analysis can be directly tested in future experiments with superconducting nanowires.

  11. Rapid and automated analysis of aflatoxin M1 in milk and dairy products by online solid phase extraction coupled to ultra-high-pressure-liquid-chromatography tandem mass spectrometry.

    Science.gov (United States)

    Campone, Luca; Piccinelli, Anna Lisa; Celano, Rita; Pagano, Imma; Russo, Mariateresa; Rastrelli, Luca

    2016-01-08

    This study reports a fast and automated analytical procedure for the analysis of aflatoxin M1 (AFM1) in milk and dairy products. The method is based on the simultaneous protein precipitation and AFM1 extraction, by salt-induced liquid-liquid extraction (SI-LLE), followed by an online solid-phase extraction (online SPE) coupled to ultra-high-pressure-liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis to the automatic pre-concentration, clean up and sensitive and selective determination of AFM1. The main parameters affecting the extraction efficiency and accuracy of the analytical method were studied in detail. In the optimal conditions, acetonitrile and NaCl were used as extraction/denaturant solvent and salting-out agent in SI-LLE, respectively. After centrifugation, the organic phase (acetonitrile) was diluted with water (1:9 v/v) and purified (1mL) by online C18 cartridge coupled with an UHPLC column. Finally, selected reaction monitoring (SRM) acquisition mode was applied to the detection of AFM1. Validation studies were carried out on different dairy products (whole and skimmed cow milk, yogurt, goat milk, and powder infant formula), providing method quantification limits about 25 times lower than AFM1 maximum levels permitted by EU regulation 1881/2006 in milk and dairy products for direct human consumption. Recoveries (86-102%) and repeatability (RSDmilk and dairy products studied. The proposed method improves the performance of AFM1 analysis in milk samples as AFM1 determination is performed with a degree of accuracy higher than the conventional methods. Other advantages are the reduction of sample preparation procedure, time and cost of the analysis, enabling high sample throughput that meet the current concerns of food safety and the public health protection. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Propeller Cavitation in Non-Uniform Flow and Correlation with the Near Pressure Field

    Directory of Open Access Journals (Sweden)

    Francisco Alves Pereira

    2016-11-01

    Full Text Available An experimental study is carried out in a cavitation tunnel on a propeller operating downstream of a non-uniform wake. The goal of this work is to establish quantitative correlations between the near pressure field and the cavitation pattern that takes place on the propeller blades. The pressure field is measured at the walls of the test section and in the near wake of the propeller and is combined with quantitative high-speed image recording of the cavitation pattern. Through harmonic analysis of the pressure data and image processing techniques that allow retrieving the cavitation extension and volume, we discuss the potential sources that generate the pressure fluctuations. Time correlations are unambiguously established between pressure peak fluctuations and cavitation collapse events, based on the Rayleigh collapse time. Finally, we design a model to predict the cavitation-induced pressure fluctuations from the derivation of the cavitation volume acceleration. A remarkable agreement is observed with the actual pressure field.

  13. Pressure sensor

    Science.gov (United States)

    Mee, David K.; Ripley, Edward B.; Nienstedt, Zachary C.; Nienstedt, Alex W.; Howell, Jr., Layton N.

    2015-09-29

    Disclosed is a passive, in-situ pressure sensor. The sensor includes a sensing element having a ferromagnetic metal and a tension inducing mechanism coupled to the ferromagnetic metal. The tension inducing mechanism is operable to change a tensile stress upon the ferromagnetic metal based on a change in pressure in the sensing element. Changes in pressure are detected based on changes in the magnetic switching characteristics of the ferromagnetic metal when subjected to an alternating magnetic field caused by the change in the tensile stress. The sensing element is embeddable in a closed system for detecting pressure changes without the need for any penetrations of the system for power or data acquisition by detecting changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

  14. Voltage quality. Fluctuations and flicker; Qualite de la tension. Fluctuations et flicker

    Energy Technology Data Exchange (ETDEWEB)

    Ott, R. [Electricite de France (EDF), Recherche et Developpement, 75 - Paris (France)

    2002-11-01

    Voltage fluctuations can be periodical, irregular or aleatory. If they stay in the normal limits of voltage variation the main effect is the physiological discomfort generated by the flicker of lighting systems. This article presents the causes and effects of voltage variations: 1 - definitions: classification, flicker, bulbs sensitiveness, origin, estimation; 2 - flicker measurement: regular voltage surges, any shape voltage variations: flicker-meter; 3 - isolated variations: determination of the upstream impedance, capacitors interlock, start-up of asynchronous motors; 4 - generators of repetitive or aleatory fluctuations: arc furnace, resistance welding machine, resistance furnace, influence of 175 Hz centralized remote control signals on fluorescent lamps; 5 - propagation; 6 - standards and recommendations: two particularities of flicker, emission levels; 7 - flicker abatement: increase of short-circuit power, abatement of reactive power variations, other solutions; 8 - treatment of a voltage fluctuation problem: diagnosis, voltage variations in the form of distinct rectangular surges, connection of fluctuating resistive loads, voltage variations in the form of non-rectangular surges, connection of an arc furnace. (J.S.)

  15. Ejector Enhanced Pulsejet Based Pressure Gain Combustors: An Old Idea With a New Twist

    Science.gov (United States)

    Paxson, Daniel E.; Dougherty, Kevin T.

    2005-01-01

    An experimental investigation of pressure-gain combustion for gas turbine application is described. The test article consists of an off-the-shelf valved pulsejet, and an optimized ejector, both housed within a shroud. The combination forms an effective can combustor across which there is a modest total pressure rise rather than the usual loss found in conventional combustors. Although the concept of using a pulsejet to affect semi-constant volume (i.e., pressure-gain) combustion is not new, that of combining it with a well designed ejector to efficiently mix the bypass flow is. The result is a device which to date has demonstrated an overall pressure rise of approximately 3.5 percent at an overall temperature ratio commensurate with modern gas turbines. This pressure ratio is substantially higher than what has been previously reported in pulsejet-based combustion experiments. Flow non-uniformities in the downstream portion of the device are also shown to be substantially reduced compared to those within the pulsejet itself. The standard deviation of total pressure fluctuations, measured just downstream of the ejector was only 5.0 percent of the mean. This smoothing aspect of the device is critical to turbomachinery applications since turbine performance is, in general, negatively affected by flow non-uniformities and unsteadiness. The experimental rig will be described and details of the performance measurements will be presented. Analyses showing the thermodynamic benefits from this level of pressure-gain performance in a gas turbine will also be assessed for several engine types. Issues regarding practical development of such a device are discussed, as are potential emissions reductions resulting from the rich burning nature of the pulsejet and the rapid mixing (quenching) associated with unsteady ejectors.

  16. Monitoring Personalized Trait Using Oscillometric Arterial Blood Pressure Measurements

    OpenAIRE

    Young-Suk Shin

    2012-01-01

    The blood pressure patterns obtained from a linearly or stepwise deflating cuff exhibit personalized traits, such as fairly uniform peak patterns and regular beat geometry; it can support the diagnosis and monitoring of hypertensive patients with reduced sensitivity to fluctuations in Blood Pressure (BP) over time. Monitoring of personalized trait in Oscillometric Arterial Blood Pressure Measurements (OABPM) uses the Linear Discriminant Analysis (LDA) algorithm. The representation of personal...

  17. Effects of clonidine and scopolamine on multiple target detection in rapid serial visual presentation

    NARCIS (Netherlands)

    Brown, S.B.R.E.; Slagter, H.A.; van Noorden, M.S.; Giltay, E.J.; van der Wee, N.J.A.; Nieuwenhuis, S.

    2016-01-01

    Rationale: The specific role of neuromodulator systems in regulating rapid fluctuations of attention is still poorly understood. Objectives: In this study, we examined the effects of clonidine and scopolamine on multiple target detection in a rapid serial visual presentation task to assess the role

  18. Intra- and extra-cranial effects of transient blood pressure changes on brain near-infrared spectroscopy (NIRS) measurements.

    Science.gov (United States)

    Minati, Ludovico; Kress, Inge U; Visani, Elisa; Medford, Nick; Critchley, Hugo D

    2011-04-30

    Brain near-infrared spectroscopy (NIRS) is an emerging neurophysiological tool that combines straightforward activity localization with cost-economy, portability and patient compatibility. NIRS is proving its empirical utility across specific cognitive and emotional paradigms. However, a potential limitation is that it is not only sensitive to haemodynamic changes taking place in the cortex, and task-related cardiovascular responses expressed in the perfusion of extracranial layers may be confounding. Existing literature reports correlations between brain NIRS and systemic blood pressure, yet it falls short of establishing whether in normal participants the blood pressure changes encountered in experimental settings can have confounding effects. Here, we tested this hypothesis by performing two experimental manipulations while recording from superficial occipital cortex, encompassing striate and extrastriate regions. Visual stimulation with reversing chequerboards evoked cortical haemodynamic responses. Simultaneously and independently, transient systemic blood pressure changes were generated through rapid arm-raising. Shallow-penetration NIRS recordings, probing only extra-cerebral tissues, highlighted close haemodynamic coupling with blood pressure. A different coupling pattern was observed in deep-penetration recordings directed at haemodynamic signals from visual cortex. In absence of blood-pressure changes, NIRS signals tracked differences in visual stimulus duration. However when blood pressure was actively manipulated, this effect was absent and replaced by a very large pressure-related response. Our observations demonstrate that blood pressure fluctuations can exert confounding effects on brain NIRS, through expression in extracranial tissues and within the brain itself. We highlight the necessity for continuous blood pressure monitoring alongside brain NIRS, and for further research on methods to correct for physiological confounds. Copyright © 2011

  19. Detrended fluctuation analysis made flexible to detect range of cross-correlated fluctuations

    Science.gov (United States)

    Kwapień, Jarosław; Oświecimka, Paweł; DroŻdŻ, Stanisław

    2015-11-01

    The detrended cross-correlation coefficient ρDCCA has recently been proposed to quantify the strength of cross-correlations on different temporal scales in bivariate, nonstationary time series. It is based on the detrended cross-correlation and detrended fluctuation analyses (DCCA and DFA, respectively) and can be viewed as an analog of the Pearson coefficient in the case of the fluctuation analysis. The coefficient ρDCCA works well in many practical situations but by construction its applicability is limited to detection of whether two signals are generally cross-correlated, without the possibility to obtain information on the amplitude of fluctuations that are responsible for those cross-correlations. In order to introduce some related flexibility, here we propose an extension of ρDCCA that exploits the multifractal versions of DFA and DCCA: multifractal detrended fluctuation analysis and multifractal detrended cross-correlation analysis, respectively. The resulting new coefficient ρq not only is able to quantify the strength of correlations but also allows one to identify the range of detrended fluctuation amplitudes that are correlated in two signals under study. We show how the coefficient ρq works in practical situations by applying it to stochastic time series representing processes with long memory: autoregressive and multiplicative ones. Such processes are often used to model signals recorded from complex systems and complex physical phenomena like turbulence, so we are convinced that this new measure can successfully be applied in time-series analysis. In particular, we present an example of such application to highly complex empirical data from financial markets. The present formulation can straightforwardly be extended to multivariate data in terms of the q -dependent counterpart of the correlation matrices and then to the network representation.

  20. Decoherence and electric field noise analysis of nitrogen vacancy center diamonds due to the surface charge fluctuations and lattice strain

    Science.gov (United States)

    Santamore, Deborah

    2017-04-01

    We theoretically investigate the decoherence mechanisms due to the electric field noise in nitrogen vacancy (NV) center diamonds. The noise is caused by both the surface charge fluctuations and strain due to surface contaminants and bulk impurities. The system is modeled with nitrogen impurities in diamond and hydrogen surface terminations with water. We obtain the equations of motion, calculate the electric field fluctuations, and analyze noise. We find that the surface effect is greater than lattice distortion by the bulk impurity substitution. We also discuss how to minimize the noise. Finally, we examine lattice distortion and stability of NV centers under high pressure. NSF: DMR-1505641.