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1

Lidar Observations of Subvisual Atmospheric Phenomena  

Microsoft Academic Search

In the past, the study of the dynamics of the atmosphere has been mainly based on in-situ and passive sensors. These have met with partial success in observing subvisual atmospheric phenomena such as clear air inversions, clear air turbulence, wing tip vortices (wake turbulence) and thermals. It is only recently that the atmosphere has been examined by active remote- sensing

S. R. Pal; R. W. Bell; A. I. Carswell

2

EUSO: Extreme Universe Space Observatory atmosphere phenomena  

NASA Astrophysics Data System (ADS)

The idea to use the Earth s atmosphere as a natural laboratory for the detection of EECR events, requires establishment of objective criteria to distinguish between these events and other physical phenomena, which demonstrate optical emissions in the spectral interval under interest, 330400 nm. The atmospheric fluorescence and the Cherenkov emission, caused by EECR should be retrieved from measurements performed in the presence of a continuos background nightglow. Selected spectral interval, foreseen to be examined, contains mainly molecular emissions of O2 Herzberg band, 2nd nd positive band of N2 and the 1st negative band of N+ 2 . Their intensities depend on the season, local time, longitude, latitude, solar activity, geomagnetic activity, etc. While the duration of the nightglow is in order of hours, other type optical phenomena: tropospheric lightening and tropospheric/mesospheric interactions (Blue Jets, Red Starters, Sprites, etc.), have much shorter duration down to milliseconds, while the dynamic range of their brightness ranges several orders. We give also attention to the meteoroids, as a particular class of atmospheric phenomena. It should be mentioned that there is a very few information regarding meteoroids spectral properties in UV range. According to recent theories and models, the meteoroids are able to create marked jet-like structures in the atmosphere, exhibiting optical appearance, which could be wrongly interpreted as EECR events. Such error could arise also for the other aforementioned short-lived optical phenomena. Taking into account all this, it is obvious, that the sophisticate laboratory environment requires detailed analysis of the existing experimental and theoretical studies in order to develop appropriate tests to distinguish EERC and other atmospheric phenomena. The present work stress also on the need to develop appropriate radiation transfer model, which could appear useful tool for assessment of the real brightness of the detected fluorescence and Cherenkov emission. Such model will giving us the possibility to evaluate the energy of the

Kostadinov, I.; Giovannelli, G.; Cevolani, G.; Cupini, E.; Pupillo, G.; Mazzinghi, P.; EUSO Collaboration

3

Polar Phenomena in Outer Planet Atmospheres  

NASA Astrophysics Data System (ADS)

Infrared observations of the polar regions of the outer planets have revealed similarities to the Earth's atmosphere and some new phenomena. The most dominant force which is apparent in time-dependent studies of the poles is seasonal radiative forcing, which was detected in Saturn's stratosphere as early as 1973. For Saturn, Uranus and Neptune, planets with substantial obliquities, the seasonally dependent changes are predictable and can be used to constrain abundances of optically active gases and the rate of restoration by stratospheric circulation. In the case of Neptune, recent evidence shows that the heating is sufficient to allow a "leak" from the reservoir of methane in the deep atmosphere into the polar stratosphere. New thermal images of Uranus show that the winter pole of Uranus which has only recently emerged fully from darkness is colder than when it was in the middle of winter when Voyager 2 visited, confirming the substantial seasonal phase delay associated with radiative heating and cooling models. Even Jupiter with its 3-degree obliquity shows clear evidence for seasonal forcing of temperatures in the upper troposphere and stratosphere. The second most prominent characteristic of the resolvable polar temperature fields in Jupiter and Saturn is the formation of polar vortices. Jupiter's polar vortices are cold, similar to those detected in the terrestrial planets; they have sharp equatorward boundaries which are characterized by Rossby waves which rotate at the speed of the local zonal wind flow and are coincident with the similarly irregular boundaries of a polar haze, also known as "polar hoods". The cold vortex at Saturn's northern winter pole is muted, but Saturn also has a unique "warm polar vortex" in the south (late summer) pole which shows no apparent wave structure. Saturn's warm polar vortex has no counterpart in the Earth's atmosphere, where summer radiative warming simply dissipates the cold winter vortex. Saturn also possesses dynamically driven hot regions within 2 degrees of its poles where dynamics is driving relatively dry air downwards, causing adiabatic warming and clearing the atmosphere; this phenomenon also has no terrestrial counterpart. Jupiter's upper polar stratosphere is warmed in discrete local regions by Joule heating from energetic particles cascading into the neutral atmosphere. The northern auroral-related polar "hot spot" has a very predictable geometry, but an amplitude that is variable over time scales of months. On the other hand, the stratosphere 25-30 degrees from Neptune's pole shows signs of ephemeral hot spots which are more likely to related to dynamics. These phenomena provide a rich basis of constraints for global climate models which must, at least for Jupiter, be coupled with models of auroral energy transport.

Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Leyrat, C.; Greathouse, T.; Parrish, P.; Encrenaz, T.; Simon-Miller, A.

2008-12-01

4

Numerical analysis and modeling of atmospheric phenomena  

NASA Technical Reports Server (NTRS)

For the past 22 years Grant NGR 22-009-727 has been supporting research in the Center for Meteorology and Physical Oceanography (and its predecessors) in a wide variety of diagnostic and modeling studies of atmospheric and ocean phenomena. Professor Jule Charney was the initial Principal Investigator. Professor Peter Stone joined him as co-Principal Investigator in 1975 and became the sole Principal Investigator in 1981. During its lifetime the Grant has supported in whole or in part 11 Master's theses, 14 Ph.D. theses, and 45 papers published in refereed scientific journals. All of these theses and papers (with bibliographic references) are listed below. All but one of the theses were used to fulfill the requirements for MIT (Massachusetts Institute of Technology) degrees and are available from the MIT libraries. The one exception is F. Chen's Ph.D. thesis which was for a Harvard degree and is available from the Harvard libraries. In addition to the work described in the citations listed below, the Grant has supported Research Assistant Amy Solomon during the past two years to carry out a study of how baroclinic adjustment is affected by vertical resolution, vertical temperature structure, and dissipation. Ms. Solomon plans to use this project for her Ph.D. thesis. Support for this project will continue under NASA Grant NAG 5-2490, 'The Factors Controlling Poleward Heat Transport in Climate Models.'

Stone, Peter H.

1994-01-01

5

Atmospheric waves as scaling, turbulent phenomena  

NASA Astrophysics Data System (ADS)

It is paradoxical that while atmospheric dynamics are highly nonlinear and turbulent that atmospheric waves are commonly modelled by linear or weakly nonlinear theories. We postulate that the laws governing atmospheric waves are on the contrary high Reynold's number (Re), emergent laws so that - in common with the emergent high Re turbulent laws - they are also constrained by scaling symmetries. We propose an effective turbulence - wave propagator which corresponds to a fractional and anisotropic extension of the classical wave equation propagator with dispersion relations similar to those of inertial gravity waves (and Kelvin waves) yet with an anomalous (fractional) order Hwav/2. Using geostationary IR radiances, we estimate the parameters finding that Hwav/2 ? 0.17 ± 0.04 (the classical value = 2).

Pinel, J.; Lovejoy, S.

2013-06-01

6

Simulations of atmospheric phenomena at the Phoenix landing site with the Ames General Circulation Model  

Microsoft Academic Search

Phoenix, the first NASA Mars Scout class mission, was designed to ``follow the water'' and study the polar region. Landing in late northern spring, Phoenix measured soil chemistry, near-surface water ice, and studied numerous atmospheric properties and weather phenomena. Here, we use atmospheric measurements made by Phoenix to test and calibrate the Ames General Circulation Model (GCM) and start the

Steven M. Nelli; Nilton O. Renno; James R. Murphy; William C. Feldman; Stephen W. Bougher

2010-01-01

7

Simulations of atmospheric phenomena at the Phoenix landing site with the Ames General Circulation Model  

Microsoft Academic Search

Phoenix, the first NASA Mars Scout class mission, was designed to “follow the water” and study the polar region. Landing in late northern spring, Phoenix measured soil chemistry, near-surface water ice, and studied numerous atmospheric properties and weather phenomena. Here, we use atmospheric measurements made by Phoenix to test and calibrate the Ames General Circulation Model (GCM) and start the

Steven M. Nelli; Nilton O. Renno; James R. Murphy; William C. Feldman; Stephen W. Bougher

2010-01-01

8

Double streamer phenomena in atmospheric pressure low frequency corona plasma  

SciTech Connect

Time-resolved images of an atmospheric pressure corona discharge, generated at 50 kHz in a single pin electrode source, show unique positive and negative corona discharge features: a streamer for the positive period and a glow for the negative period. However, unlike in previous reports of dc pulse and low frequency corona discharges, multistreamers were observed at the initial time stage of the positive corona. A possible physical mechanism for the multistreamers is suggested.

Kim, Dan Bee; Jung, H.; Gweon, B.; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2010-07-15

9

Coronal transient phenomena. [solar atmospheric radial flow model  

NASA Technical Reports Server (NTRS)

A hydrodynamical description of outward propagating disturbances from the sun's surface in a model solar atmosphere is considered. Use is made of this model to explain the coronal transient phenomenon. It was found that this radial flow model clearly indicates the mass flow as being continuous, going out from the surface of the sun. Detailed results are presented for the disturbed density, velocity and temperature of the corona up to 6 solar radii.

Wu, S. T.; Han, S. M.

1974-01-01

10

Space weather driven changes in lower atmosphere phenomena  

NASA Astrophysics Data System (ADS)

During a period of heliospheric disturbance in 2007-9 associated with a co-rotating interaction region (CIR), a characteristic periodic variation becomes apparent in neutron monitor data. This variation is phase-locked to periodic heliospheric current sheet crossings. Phase-locked electrical variations are also seen in the terrestrial lower atmosphere in the southern UK, including an increase in the vertical conduction current density of fair weather atmospheric electricity during increases in galactic cosmic ray-induced neutron monitor count rate at the surface and energetic proton count rates measured by geosynchronous spacecraft. At the same time as the conduction current increases, changes in the cloud microphysical properties lead to an increase in the detected height of the cloud base at Lerwick Observatory, Shetland, with associated changes in surface meteorological quantities. As electrification is expected at the base of layer clouds, which can influence droplet properties, these observations of phase-locked thermodynamic, cloud, atmospheric electricity and solar sector changes are not inconsistent with a heliospheric disturbance driving lower troposphere changes.

Harrison, R. G.; Nicoll, K. A.; McWilliams, K. A.

2013-06-01

11

Phenomena of oscillations in atmospheric pressure direct current glow discharges  

SciTech Connect

Self-sustained oscillations in a dc glow discharge with a semiconductor layer at atmospheric pressure were investigated by means of a one-dimensional fluid model. It is found that the dc glow discharge initially becomes unstable in the subnormal glow region and gives rise to oscillations of plasma parameters. A variety of oscillations with one or more frequencies have been observed under different conditions. The discharge oscillates between the glow discharge mode and the Townsend discharge mode in the oscillations with large amplitude while operates in the subnormal glow discharge mode all the while in the oscillations with small amplitude. Fourier Transform spectra of oscillations reveal the transition mechanism between different oscillations. The effects of semiconductor conductivity on the oscillation frequency of the dominant mode, gas voltage, as well as the discharge current have also been analyzed.

Liu, Fu-cheng [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)] [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Yan, Wen; Wang, De-zhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2013-12-15

12

Wave phenomena comparison between Mars and Titan upper atmospheres  

NASA Astrophysics Data System (ADS)

We will examine the presence of waves in the neutral atmospheres of two terrestrial bodies: Mars and Titan. We will examine the aerobraking datasets from both the Mars Global Surveyor (MGS) and Mars Odyssey (ODY) missions, analyzing the neutral densities to characterize the planetary tides and/or smaller-scale internal gravity waves present in the data. While several studies have examined these features before at Mars (e.g., Forbes et al. [2002] and Fritts and Tolson [2006]), we will be focusing on examining whether or not the wave features observed in the thermosphere could be explained primarily with planetary tides, as posted recently in Klienbohl et al. [2013]. In addition to this, we will also examine the neutral densities obtained by the Cassini Ion-Neutral Mass Spectrometer (INMS) in order to determine if planetary tides can explain the numerous wave-like features that have been interpreted as gravity waves propagating vertically (cf., Mueller-Wodarg et al. [2008], Cui et al. [2013], and Snowden et al. [2013]).

Elrod, Meredith K.; Bell, J. M.

2013-10-01

13

Optical phenomena caused by radioactivity in the atmosphere and their use in remote ecological monitoring  

Microsoft Academic Search

The paper analyzes secondary phenomena of atmospheric radioactive pollution caused by activity of the nuclear cycle enterprises. These effects being as indicators for remote diagnostics of a radio-activity are discussed. Excitation of a molecular and gas component in the air and various chemical reactions under the action of radiation have been considered. As a result of these reactions, new aerosol

Liliya K. Chistyakova

1999-01-01

14

A Study of the Effects of Atmospheric Phenomena on Mars Science Laboratory Entry Performance  

NASA Technical Reports Server (NTRS)

At Earth during entry the shuttle has experienced what has come to be known as potholes in the sky or regions of the atmosphere where the density changes suddenly. Because of the small data set of atmospheric information where the Mars Science Laboratory (MSL) parachute deploys, the purpose of this study is to examine the effect similar atmospheric pothole characteristics, should they exist at Mars, would have on MSL entry performance. The study considers the sensitivity of entry design metrics, including altitude and range error at parachute deploy and propellant use, to pothole like density and wind phenomena.

Cianciolo, Alicia D.; Way, David W.; Powell, Richard W.

2008-01-01

15

Electric currents induced inside biological cells by geomagnetic and atmospheric phenomena.  

PubMed

An increasing number of studies have appeared in the last ten years indicating that some pathologies may correlate with geomagnetic activity and cosmic rays. However a physical mechanism binding both phenomena has not been proposed. In the present work we obtain the amplitude of the magnetic fields at different frequencies, that may induce inside biological cells currents of the same magnitude of the currents generated by the cells themselves. We compare these values with the wave amplitudes produced in geomagnetic and atmospheric phenomena, and found that micropulsations, whistlers and lightning are capable of produce the same or larger values. PMID:11803972

Durand-Manterola, H J; Mendoza, B; Diaz-Sandoval, R

2001-01-01

16

Optical phenomena caused by radioactivity in the atmosphere and their use in remote ecological monitoring  

NASA Astrophysics Data System (ADS)

The paper analyzes secondary phenomena of atmospheric radioactive pollution caused by activity of the nuclear cycle enterprises. These effects being as indicators for remote diagnostics of a radio-activity are discussed. Excitation of a molecular and gas component in the air and various chemical reactions under the action of radiation have been considered. As a result of these reactions, new aerosol and gaseous components in the form of the exited atoms and ions appear in the atmosphere and relax with emission including microwave and optical wavelengths. The observable luminescence of the air during the emergency events at the nuclea power stations are long enough to be detected by modern receivers. Intensity of such radiation in a radioactive plume is estimated for ecological monitoring of the atmosphere. Aerosols appearing, as a result of UF6 hydrolysis, in the atmosphere and their behavior have been also shown to be detectable with remote sensing.

Chistyakova, Liliya K.

1999-11-01

17

The progresses on the magnetodynamic phenomena in the solar and stellar atmosphere.  

NASA Astrophysics Data System (ADS)

The IAU Colloquium No. 153 was held in Makuhari near Tokyo (Japan), from May 22 to 26, 1995. The topic of the meeting, concentrating on the advances of magnetodynamic phenomena in the solar and stellar atmosphere, consists of four parts: magnetic atmospheres of the Sun and stars; wind and mass-loss from the Sun and stars; production of superhot plasma and high-energy particles in the Sun and stars; magnetic behavior of the Sun and stars and their activity cycles. This paper gives a short review on this colloquium.

Gan, W. Q.

1995-12-01

18

Simulations of atmospheric phenomena at the Phoenix landing site with the Ames General Circulation Model  

NASA Astrophysics Data System (ADS)

Phoenix, the first NASA Mars Scout class mission, was designed to “follow the water” and study the polar region. Landing in late northern spring, Phoenix measured soil chemistry, near-surface water ice, and studied numerous atmospheric properties and weather phenomena. Here, we use atmospheric measurements made by Phoenix to test and calibrate the Ames General Circulation Model (GCM) and start the process of analyzing and interpreting the vast data set provided by this groundbreaking mission. The GCM reproduces surface pressures and temperatures within the measured diurnal and seasonal ranges. It also reproduces measured water ice cloud profiles with ground fogs forming after Ls = 120° and a separate cloud deck between 3 km and 6 km above the surface. Near-surface water vapor pressures have daytime maxima above 1 Pa in both the data and model. We find that frosts and fogs observed by Phoenix are correlated with the formation of high-pressure weather systems over the landing site.

Nelli, Steven M.; Renno, Nilton O.; Murphy, James R.; Feldman, William C.; Bougher, Stephen W.

2010-06-01

19

Dynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges  

NASA Astrophysics Data System (ADS)

A study of pulse phenomena in conventional parallel-plate dielectric-barrier controlled atmospheric-pressure glow (DB-APG) discharges in helium is reported. Stable DB-APG discharges are found to occur at arbitrarily low frequencies as long as the gas voltage exceeds the Paschen breakdown voltage, i.e., no lower limit of ~1 kHz exists for DB-APG operation. The interpulse preionization phenomenon is found to be an artifact of typical ~10 kHz operation of DB-APG discharges and does not play a role in the formation of a stable pulse. Multiple pulses result from repeated temporally separated breakdown events in the discharge. A relatively simple zero-dimensional model that treats only the Paschen breakdown mechanism in the discharge and charge trapping phenomena at the dielectric surfaces can be used to simulate all important qualitative features of DB-APG phenomena. Finally, we show that control of the pulse intensity, number of pulses in a pulse train, and the time interval between pulse trains can be achieved using ``ramp-plus-plateau'' voltage input wave forms rather than typical sinusoidal wave forms.

Shin, Jichul; Raja, Laxminarayan L.

2003-12-01

20

Parametric dependence and control of pulsed phenomena in helium dielectric barrier atmospheric-pressure glow discharges  

NASA Astrophysics Data System (ADS)

There is rapidly growing interest in atmospheric-pressure glow (APG) discharges since the first report of such discharges over 10 years ago. Especially, dielectric-barrier controlled APG discharges (DB-APG) are of special interest owing to the large number of possible applications. A number of interesting features of these discharges are currently subject of debate in the literature. For example, the role of metastables in pulse formation and cause for multiple pulses are not clearly understood. In this talk we report new experimental studies that seek to explain several of these observed DB-APG discharge peculiarities. Contrary to literature reports of order 1 kHz lower limit for helium DB-APG phenomena, we report discharge phenomena at arbitrarily low frequencies below the 1 kHz limit, albeit under very weak discharge conditions. The number of pulses formed each half cycle is found increase rapidly with decreasing frequency but pulse widths are found to remain relatively invariant to discharge operational conditions. We conclude that pulse phenomena in DB-APG discharges is controlled by classical Paschen breakdown processes followed immediately by extinction behaviour. External voltage increase rates and the overall duration of external voltage increase are found to determine pulse intensity and the number of pulses per cycle of the discharge. Based on these insights, we report the possibility of significant control over discharge pulse intensity and repetition rate using other waveforms such as square-wave pulses.

Shin, Jichul; Raja, Laxminarayan L.

2003-10-01

21

Long time-scale transient phenomena in dielectric barrier atmospheric pressure glow discharge  

NASA Astrophysics Data System (ADS)

Dielectric barrier controlled atmospheric-pressure glow discharges (APG) can potentially provide new approaches for large-scale, vacuum-chamber-free materials processing. A good understanding of APG phenomena is however a prerequisite to realizing successful applications. Here, we report fundamental studies of long time-scale transient phenomena in APG discharges. APG discharges are observed to have irreproducible V-I characteristics for nominally similar discharge conditions. Also long-term drift in V-I characteristic are observed with time-scales spanning 10's of minutes to hours. We explain these phenomena as a consequence of variation of dielectric surface condition that effectively causes variations in the secondary electron emission coefficient. Asymmetric pulses are also often observed and can be explained by variations in the secondary emission coefficient. We rule out impurities as a cause of variations through a set of experiments involving flow through the APG discharge. Our studies and conclusions are supported through detailed time-resolved imaging of discharge structures as well as zero-dimensional modeling.

Shin, Jichul; Raja, Laxminarayan

2004-09-01

22

PROPAGATING WAVE PHENOMENA DETECTED IN OBSERVATIONS AND SIMULATIONS OF THE LOWER SOLAR ATMOSPHERE  

SciTech Connect

We present high-cadence observations and simulations of the solar photosphere, obtained using the Rapid Oscillations in the Solar Atmosphere imaging system and the MuRAM magnetohydrodynamic (MHD) code, respectively. Each data set demonstrates a wealth of magnetoacoustic oscillatory behavior, visible as periodic intensity fluctuations with periods in the range 110-600 s. Almost no propagating waves with periods less than 140 s and 110 s are detected in the observational and simulated data sets, respectively. High concentrations of power are found in highly magnetized regions, such as magnetic bright points and intergranular lanes. Radiative diagnostics of the photospheric simulations replicate our observational results, confirming that the current breed of MHD simulations are able to accurately represent the lower solar atmosphere. All observed oscillations are generated as a result of naturally occurring magnetoconvective processes, with no specific input driver present. Using contribution functions extracted from our numerical simulations, we estimate minimum G-band and 4170 A continuum formation heights of 100 km and 25 km, respectively. Detected magnetoacoustic oscillations exhibit a dominant phase delay of -8 Degree-Sign between the G-band and 4170 A continuum observations, suggesting the presence of upwardly propagating waves. More than 73% of MBPs (73% from observations and 96% from simulations) display upwardly propagating wave phenomena, suggesting the abundant nature of oscillatory behavior detected higher in the solar atmosphere may be traced back to magnetoconvective processes occurring in the upper layers of the Sun's convection zone.

Jess, D. B.; Shelyag, S.; Mathioudakis, M.; Keys, P. H.; Keenan, F. P. [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN (United Kingdom); Christian, D. J., E-mail: d.jess@qub.ac.uk [Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States)

2012-02-20

23

Determination of constant-volume balloon capabilities for aeronautical research. [specifically measurement of atmospheric phenomena  

NASA Technical Reports Server (NTRS)

The proper application of constant-volume balloons (CVB) for measurement of atmospheric phenomena was determined. And with the proper interpretation of the resulting data. A literature survey covering 176 references is included. the governing equations describing the three-dimensional motion of a CVB immersed in a flow field are developed. The flowfield model is periodic, three-dimensional, and nonhomogeneous, with mean translational motion. The balloon motion and flow field equations are cast into dimensionless form for greater generality, and certain significant dimensionless groups are identified. An alternate treatment of the balloon motion, based on first-order perturbation analysis, is also presented. A description of the digital computer program, BALLOON, used for numerically integrating the governing equations is provided.

Tatom, F. B.; King, R. L.

1977-01-01

24

Invited papers from the International Symposium on Nonequilibrium Processes, Plasma, Combustion and Atmospheric Phenomena  

NASA Astrophysics Data System (ADS)

The International Symposium on Nonequilibrium Processes, Plasma, Combustion and Atmospheric Phenomena is a forum of international experts in such fundamental areas as physical and chemical kinetics, physics of low temperature and cluster plasmas, physics of shock and detonation waves, physics and chemistry of aerosols and nanoparticles, combustion and atmospheric chemistry, physics and chemistry of high speed flows, plasma and laser chemistry, plasma, laser and combustion assisted technologies. This symposium has already become a notable biannual event attracting a growing attendance of scientists from all over the world. The first symposium was organizing in St Petersburg, Russia, 8-11 July 2003, and was dedicated to the memory of N N Semenov, a founder of the chain-branching reaction theory and a Nobel prizewinner. The second, third and fourth symposia were held in Sochi, Russia, 3-7 October 2005; 25-29 June 2007; and 5-9 October 2009. The last (fifth) symposium was also organized in Sochi, Russia, 1-6 October 2012. Here we present selected proceedings of the last symposium, comprised of four invited papers on the topics of ab initio studies of some elementary processes important for atmospheric plasma and combustion, kinetics of low temperature plasma and physics of clusters. The papers have been written by the symposium participants and are based on their reports at the meeting. They are: 'Thermochemistry of small iodine species' by Šulková et al ; 'Analysis of the reaction and quenching channels in a H + O2(a 1?g ) system' by Sharipov and Starik; 'Kinetics of plasmachemical processes in the expanding flow of nitrogen plasma' by Kadochnikov et al ; and 'Theoretical study of structure and physical properties of (Al2O3)n clusters' by Sharipov et al.

Starik, Alexander M.

2013-11-01

25

Long-period fading in atmospherics during severe meteorological activity and associated solar geophysical phenomena at low latitudes  

NASA Astrophysics Data System (ADS)

The records of VLF atmospherics over Calcutta and then over Kalyani (West Bengal) during the torrential rainfall, caused by violent monsoon and post-monsoon depressions, exhibit distinct long-period fadings both at day and night. Interesting results obtained from an analysis of round-the-clock atmospherics data and associated meteorological parameters are reported in this paper. A possible correlation between the severe meteorological activity with the solar geophysical phenomena was studied. The results are indicative of an interesting sequence of solar-terrestrial events. A tentative conclusion is reached, suggesting an origin of the fading from atmospheric gravity waves generated in the centre of activity of the depressions concerned.

Bhattacharya, A. B.; Kar, S. K.; Chatterjee, M. K.; Bhattacharya, R.

1998-02-01

26

Faint electric dynamic forces in atmosphere is a possible precursor for a Seismic events phenomena  

NASA Astrophysics Data System (ADS)

The objective of this paper is to monitor the propagation of faint electric forces (D.C. potentials) in Athens' atmosphere before an earthquake. Many authors refer to radio emissions (ELF,HF,VLF,UHF ) before an event. Several other researches have been done with ICE (Instrument Champ Electrique), measurement of quasi-continuous electric fields and electric components of waves, from DC up to 3.5 MHz, or IMSC (Measuring the magnetic components of waves), for measuring magnetic field from a few Hz up to 18 kHz. More studies, within the last twenty years are correlated also with monitoring underground electromagnetic fields from different countries, but few are dealing with D.C.field. The concept is that, the aerosols are injected into the lower atmosphere due to intensifying soil gas content during the increase of seismic activity. At our station in Athens, a continuous monitoring has been conducted by three D.C.detectors which follow the ionosphere variations of the electric field daily, for the years 2007-2008. Multiple antennas have been posted and tested up to the height of thirty meters above the ground. The faint electro potentials received, had been continuously registered by two electrometers. A cross over study of aerosols simulation has been simultaneously done with photo detectors. For this purpose an array of four photo diodes, posted in infrared and visible band in function, and was connected to electro meters too. Several approaches have been taken in past years by researchers attempting to correlate changes in geophysical parameters with earthquake phenomena. In particular, many works examine possible connections of Geoelectric Field (Long and Sort Term Geoelectric Potential) variations to seismic activity and their possible use as precursors of seismic events. Long Term Geoelectric Potential (LTGP) acquisition data consists of potential difference measured between pairs of electrodes placed in the ground at specific location and distance. The electric field is continuously monitored, usually in two perpendicular directions (e.g. N-S and E-W), by two pairs of electrodes, each corresponding to a separate channel. Here we examine such possible correlations between recorded Long Term Geoelectric Potential (LTGP) acquisition data and the seismic activity observed during the same period. In collaboration with the University of Athens, Laboratory of Climatology and Atmospheric Environment and according their given data, we avoided measurements during periods of rain, snow, storms, lightning or extreme variations of temperature and atmospheric pressure. During these observations we observed an enormous variation in the voltage signals and several potential peaks were registered before the quakes in both detectors and photodiodes. The variations noted before the events, become with an optimum peak between four hours to fourteen days. All cases are related with eight earthquakes, registered in the southern part of Greece. Our conclusions demonstrate that charged aerosol emissions in the atmosphere are possible to influence and increase electro potentials before an earthquake event, under certain atmospheric conditions.

Grigoropoulos, K. N.; Nastos, P. T.; Tselentis, G.; Saragas, E.; Ifantis, A.

2009-04-01

27

Physical phenomena induced by passage of intense electromagnetic pulses (including CO/sub 2/ lasers) through the atmosphere  

SciTech Connect

The electron fluid equations are combined with Maxwell's equations to investigate the physical phenomena that occurs when short, intense electromagnetic pulses (including the CO/sub 2/ laser pulse) interact with the atmosphere. The phenomena of ''tailed erosion'' occurs when the pulse intensity exceeds the air-breakdown threshold. In some cases, the erosion of the pulse occurs first in the middle of the pulse and then occurs in the tail of the pulse. In addition, we discovered that the amount of the energy that a pulse carries through the atmosphere is independent of whether it is propagating vertically upward from the Earth's surface or vertically downward toward the Earth's surface, provided the distance the pulse travels is the same for both directions of the propagation. 20 refs., 9 figs.

Yee, J.H.; Mayhall, D.J.; Alvarez, R.

1985-10-23

28

Phase-locking of lower atmosphere phenomena with space weather changes  

NASA Astrophysics Data System (ADS)

This work presents analysis of solar-terrestrial coupling using a new phase-locking technique, to detect characteristic signatures in solar variability expressed in atmospheric quantities. This method shows that, following changes in the heliosphere, phase-locked changes can be traced through energetic particles and into the lower atmosphere, specifically in the global electric circuit and cloud properties in the lower troposphere. The heliospherically-disturbed period of interest considered occurred during 2007-2009, when a characteristic 27 day variation in neutron monitor data was present, associated with a co-rotating interaction region (CIR). The neutron monitor data was itself phase locked to solar sector boundary changes. During the same period, phase-locked atmospheric electrical variations are apparent in the lower troposphere in the southern UK. Specifically, these include an increase in the vertical conduction current during increases in the neutron counter count rate, together with increases in energetic proton count rates. Suggestions have been made that extensive horizontal layer clouds can respond to conduction current density changes, due to the electrification expected at the base of layer clouds, which can influence droplet properties. We consider the evidence for this in cloud and surface meteorological measurements made at Lerwick Observatory, Shetland, by continued application of the phase-locked analysis method to the lower atmosphere data.

Nicoll, Keri; Harrison, R. Giles

2013-04-01

29

Transient luminous event phenomena and energetic particles impacting the upper atmosphere: Russian space experiment programs  

NASA Astrophysics Data System (ADS)

In Russia several space missions are now planned to study transient luminous events in the atmosphere and high-energy charged particles at satellite altitudes. The experimental goal is to investigate the origin of the high-energy electrons and gamma ray quanta for specific transient luminous events (TLEs) and their role in the ionosphere-magnetosphere system. Simultaneous measurements of electrons at the orbit of the satellite and TLE atmospheric radiation in many wavelength bands will be performed in two missions, Tatiana-2 and RELEC. In the TUS mission UV transient event detection will be accompanied by measurements of the weak UV emission from the “seed” electrons of extensive air showers of extremely high-primary energies.

Panasyuk, M. I.; Bogomolov, V. V.; Garipov, G. K.; Grigoryan, O. R.; Denisov, Y. I.; Khrenov, B. A.; Klimov, P. A.; Lazutin, L. L.; Svertilov, S. I.; Vedenkin, N. N.; Yashin, I. V.; Klimov, S. I.; Zeleny, L. M.; Makhmutov, V. S.; Stozkov, Y. I.; Svirzhevsky, N. S.; Klimenko, V. V.; Mareev, E. A.; Shlyugaev, Y. V.; Korepanov, V. E.; Park, I. H.; Salazar, H. I.; Rothkaehl, H.

2010-06-01

30

The atmosphere UV background phenomena measured by detector on-board ``Tatiana'' satellite  

NASA Astrophysics Data System (ADS)

Near UV detector on-board the “Universitetsky-Tatiana” satellite has observed the atmosphere glow at night side of the Earth. Digital oscilloscopes help to select transient luminous events and to measure their temporal profiles in time scale of 1-64 ms. Data from those detectors were analyzed for prediction the duty cycle of future space detectors of ultra high energy cosmic rays.

Klimov, P. A.; Garipov, G. K.; Khrenov, B. A.; et al.

31

Transient luminous event phenomena and energetic particles impacting the upper atmosphere: Russian space experiment programs  

Microsoft Academic Search

In Russia several space missions are now planned to study transient luminous events in the atmosphere and high-energy charged particles at satellite altitudes. The experimental goal is to investigate the origin of the high-energy electrons and gamma ray quanta for specific transient luminous events (TLEs) and their role in the ionosphere-magnetosphere system. Simultaneous measurements of electrons at the orbit of

M. I. Panasyuk; V. V. Bogomolov; G. K. Garipov; O. R. Grigoryan; Y. I. Denisov; B. A. Khrenov; P. A. Klimov; L. L. Lazutin; S. I. Svertilov; N. N. Vedenkin; I. V. Yashin; S. I. Klimov; L. M. Zeleny; V. S. Makhmutov; Y. I. Stozkov; N. S. Svirzhevsky; V. V. Klimenko; E. A. Mareev; Y. V. Shlyugaev; V. E. Korepanov; I. H. Park; H. I. Salazar; H. Rothkaehl

2010-01-01

32

Waves, shocks and non-stationary phenomena in the outer solar atmosphere  

NASA Technical Reports Server (NTRS)

The dynamics of the solar chromosphere, transition region and corona were investigated. The consequences of the solar dynamics on the formation of spectral features in solar atmosphere regions are discussed. Data mainly from the solar ultraviolet measurement of emitted radiation (SUMER) instrument, showing signatures of non-stationary processes, are presented. These data are compared to the predictions of numerical models of the chromosphere and transition region. The observations seem to support the importance of upwardly propagating acoustic shocks in the heating of the chromosphere.

Hansteen, V. H.

1997-01-01

33

Abnormal winter weather in Japan during 2012 controlled by large-scale atmospheric and small-scale oceanic phenomena  

NASA Astrophysics Data System (ADS)

Negative Arctic Oscillation (AO) and Western Pacific (WP) pattern indices persisted from October through December 2012. For the first time both the monthly AO and WP were negative for three consecutive months. Although negative AOs and WPs make Siberia, Eastern Asia, and Japan abnormally cold, Japan was warm in October 2012. The temperature of the Sea of Japan was a record-breaking high in October 2012. Heating by these very warm waters overwhelmed the cooling effect of the negative AO and WP in October, even though the Sea of Japan is small. Linear regression analyses showed that Japan tends to be warm in years when the Sea of Japan is warm. Consequently, the temperature over Japan is controlled by interannual variations of small-scale oceanic phenomena as well as by large-scale atmospheric patterns. Previous studies have ignored such small-scale oceanic influences on island temperatures.

Ando, Yuta; Ogi, Masayo; Tachibana, Yoshihiro

2014-05-01

34

Modeling of ocean-atmosphere interaction phenomena during the breaking of modulated wave trains  

NASA Astrophysics Data System (ADS)

Air water interaction phenomena taking place during the breaking of ocean waves are investigated here. The study is carried out by exploiting the combination between a potential flow method, which is used to describe the evolution of the wave system up to the onset of the modulational instability, and a two-fluids Navier-Stokes solver which describes the strongly non-linear air-water interaction taking place during breaking events. The potential flow method is based on a fully non-linear mixed Eulerian-Lagrangian approach, whereas the two-fluid model uses a level-set method for the interface capturing. The method is applied to study the evolution of a modulated wave train composed by a fundamental wave component with two side band disturbances. It is shown that breaking occurs when the initial steepness exceed a threshold value. Once the breaking starts, it is not just a single event but it is recurrent with a period associated to the group velocity. Results are presented in terms of free surface shapes, velocity and vorticity fields, energy and viscous dissipation. The analysis reveals the formation of large vortex structures in the air domain which are originated by the separation of the air flow at the crest of the breaking wave. The form drag associated to the flow separation process significantly contributes to the dissipation of the energy content of the wave system. The energy fraction dissipated by each breaking event is distinguished.

Iafrati, A.; Babanin, A.; Onorato, M.

2014-08-01

35

The TUS space fluorescence detector for study of UHECR and other phenomena of variable fluorescence light in the atmosphere  

NASA Astrophysics Data System (ADS)

The Tracking Ultraviolet Set Up (TUS) instrument has been designed to observe from space the fluorescence light in the atmosphere when Extensive Air Shower (EAS) or other phenomena such as meteors or dust grains traverse it. The TUS design concepts will allow us to construct the next generation of fluorescence detectors with increasing light collection power and higher resolution. The KLYPVE instrument with collection power 5 times larger of the TUS will be the next space detector. Light collection is obtained with the help of segmented “low frequency Fresnel type” mirrors. Photo receiver retina in the focal consists of modules of PM tubes. For stable performance in conditions of variable light noise and variable temperature the tube type with a multi-alcali cathode was chosen. Voltage supplies for PMT in one module were designed for keeping the performance of photo receiver retina uniform when the tube gain change. From every tube the signal amplitude is recorded in time bins of 400 ns. The digital data are kept and analyzed in the module FPGA connected to the central FPGA controlling all data. The RAM memory is large, capable to record events with different duration of the light signal (up to several seconds). The preliminary event data are analyzed in the triggering system of the central FPGA. The trigger criteria have several options for events of different origin (different pixel signal duration). The trigger integration time is controlled from the space mission center. The performances of the detector were simulated and zenith angle dependent trigger efficiencies were calculated. The TUS detector will be efficient in recording “horizontal” EAS (zenith angles more than 60°), developed to their maximum above the cloud cover. The EAS Cherenkov light, back scattered from the cloud cover, will be recorded and will improve data on the EAS direction and position of maximum. For better accuracy in physical parameters of the events and for the experimental check of this accuracy the performance of two TUS detectors at the space platform was recommended. The accommodation of 2 TUS detectors at space platform of the “RESURS O” type was tried and approved. The TUS prototypes are being tested in the Mexican mountains. The photo receiver of two PM tubes with the TUS electronics on-board of the MSU Tatiana satellite is measuring the atmosphere light background.

Abrashkin, V.; Alexandrov, V.; Arakcheev, Y.; Bitkin, E.; Cordero, A.; Eremin, S.; Finger, M.; Garipov, G.; Grebenyuk, V.; Kalmykov, N.; Khrenov, B.; Koval, V.; Martinez, O.; Matyushkin, A.; Moreno, E.; Naumov, D.; Olshevsky, A.; Panasyuk, M.; Park, I.; Robledo, C.; Rubinstein, I.; Sharakin, S.; Silaev, A.; Tkatchev, L.; Tulupov, V.; Tyukaev, R.; Sabirov, B.; Salazar, H.; Saprykin, O.; Syromyatnikov, V.; Urmantsev, F.; Villasenor, L.; Yashin, I.; Zaikin, N.; Zepeda, A.

36

Transformation and birth processes of the transient luminous phenomena's in the low atmosphere of the Hessdalen valley, Norway.  

NASA Astrophysics Data System (ADS)

Transient louminous phenomenas has been observed in and over the Hessdalen valley for over 100 years. These phenomena's has been nicknamed "Hessdalen phenomenas", HP, and has been under permanent scientific investigation since 1998, when Norwegian, Italian and later French researchers installed different types of monitoring equipment in the valley. The earth's magnetic field, electromagnetic radiation in different bands, radioactive radiation, electrical resistance in the ground, ultrasound, and seismic activity are some of the signals/parameters that has been monitored. The valley has also been surveillanced by radar, optical spectrometers and automatic video recording devices. So far no electromagnetic radiation, except in the optical band, has been detected that can be coupled to the HP. The phenomenon is characterized by its horizontal movement, intense optical radiation when a transformation process occurs, different colours where white/yellow dominates, no sound, high speed, unpredictable flight patterns, seen by radar while optical invisible and often observed with continuous optical spectrum. The phenomena have been seen touching ground, without leaving burning marks and flying in higher altitudes over the valley apparently ignoring wind/weather conditions. The Hessdalen valley is located in the middle of Norway and is famous for its mines with iron, zinc and copper ore. Big deposits of ore still reside inside the valley, and the mountains are penetrated by several mineshafts, some has depth down to 1000m. No exact birthplace has been located and the phenomenon seems to emerge "out of thin air" anywhere in the valley. Any activity coupled to mineshafts has not been observed. In September 2006 a birth and transformation process was observed and several optical spectrums was obtained. The phenomena appear as a big white light possibly not more than some hundred meters above the ground in a desolated area. The phenomenon starts a transformation process dividing itself into two light balls where the light-intensity increases and showing a continuous optical spectrum. Later on the light intensity decreases and the continuous optical spectrum is broken up and emission lines appearing, as if the phenomenon goes from a plasma to a gas state. The process ends up when two round light balls are formed, with low optical intensity and red colour, showing sign of a thermal process loosing energy. This observation is to be documented and analyzed.

Gitle Hauge, Bjørn; Strand, Erling

2013-04-01

37

Energetic Particles Impacting the Upper Atmosphere in Connection with Transient Luminous Event Phenomena: Russian Space Experiment Programs  

Microsoft Academic Search

In Russia several space missions are now planned to study transient luminous events in the atmosphere and high energy charged particles at satellite altitudes. The experimental goal is to investigate the origin of the high energy electrons and gamma-ray quanta for specific transient luminous events (TLEs) and their role in the ionosphere-magnetosphere system. Simultaneous measurements of electrons at the orbit

M. I. Panasyuk; V. V. Bogomolov; G. K. Garipov; O. R. Grigoryan; Yu. I. Denisov; B. A. Khrenov; P. A. Klimov; L. L. Lazutin; S. I. Svertilov; N. N. Vedenkin; I. V. Yashin; S. I. Klimov; V. S. Makhmutov; Yu. I. Stozkov; N. S. Svirzhevsky; V. V. Klimenko; E. A. Mareev; Y. V. Shlyugaev; V. E. Korepanov; I. H. Park; H. I. Salazar; H. Rothkaehl

2009-01-01

38

Energetic Particles Impacting the Upper Atmosphere in Connection with Transient Luminous Event Phenomena: Russian Space Experiment Programs  

NASA Astrophysics Data System (ADS)

In Russia several space missions are now planned to study transient luminous events in the atmosphere and high energy charged particles at satellite altitudes. The experimental goal is to investigate the origin of the high energy electrons and gamma-ray quanta for specific transient luminous events (TLEs) and their role in the ionosphere-magnetosphere system. Simultaneous measurements of electrons at the orbit of the satellite and TLE atmospheric radiation in many wavelength bands will be performed in two missions, Tatiana-2 and RELEC. In the TUS mission UV transient event detection will be accompanied by measurements of the weak UV emission from the ``seed'' electrons of extensive air showers of extremely high primary energies.

Panasyuk, M. I.; Bogomolov, V. V.; Garipov, G. K.; Grigoryan, O. R.; Denisov, Yu. I.; Khrenov, B. A.; Klimov, P. A.; Lazutin, L. L.; Svertilov, S. I.; Vedenkin, N. N.; Yashin, I. V.; Klimov, S. I.; Makhmutov, V. S.; Stozkov, Yu. I.; Svirzhevsky, N. S.; Klimenko, V. V.; Mareev, E. A.; Shlyugaev, Y. V.; Korepanov, V. E.; Park, I. H.; Salazar, H. I.; Rothkaehl, H.

2009-04-01

39

Paranormal phenomena  

NASA Astrophysics Data System (ADS)

Critical analysis is given of some paranormal phenomena events (UFO, healers, psychokinesis (telekinesis))reported in Moldova. It is argued that correct analysis of paranormal phenomena should be made in the framework of electromagnetism.

Gaina, Alex

1996-08-01

40

A Compact Monitoring System for Recording X-Rays, Gamma Rays and Neutrons Generated By Atmospheric Lightning Discharges and Other Natural Phenomena  

NASA Astrophysics Data System (ADS)

The generation of X-rays, gamma-rays and neutrons by atmospheric lightning discharges has been predicted by different researchers several decades ago. But only within the last 25 years the first experimental evidences of events relating the generation of these radiations with lightning have been made; since then there is a continuing effort to collect more information about this type of phenomenon. In this study we describe a compact monitoring system to detect simultaneously X-rays, gamma-rays and neutrons using rather inexpensive off-the-shelf commercial detectors (Micro Roengten Radiation Monitor, 8-inch gamma tube coupled to a 3x3 inch sodium iodide [Nai(Tl)] crystal, Ludlum He-3 neutron detector) and accompanying computer interfaces. The system is extremely portable and can be powered with small automotive batteries, if necessary. Measurements are performed at ground-level. Preliminary measurements have already yielded positive results, e.g., changes in the neutron flux related to a lightning discharge and varying weather conditions have been observed in the city of Sao Jose dos Campos, Brazil (23° 11? 11?S, 45° 52? 43? W, 600 m above sea level). This a pilot study, in the near future a larger number of these compact monitoring system will be installed in different location in order to increase the area coverage. Although the main objective of the study is to detect high-energy events produced by lightning discharges, the monitoring system will also be able to detect changes in the radiation background produced by other natural phenomena.

Martin, I. M.; Alves, M. A.

2009-12-01

41

Oscillation Phenomena in the Solar Atmosphere and Modulation by Microwave Radiation Fenomenos Oscilatorios NA Atmosfera Solar E Modulacao DA Radiacao Em Microondas.  

National Technical Information Service (NTIS)

An overview of the principal known descriptions of oscillations in the solar atmosphere at different ranges of periods was developed. Particular attention was given to oscillations with time scale of seconds, associated to active regions or bursts. 1.5 qu...

A. M. Z. Vaz

1983-01-01

42

Volcanic Dust Phenomena  

Microsoft Academic Search

THE phenomena connected with the volcanic dust are undergoing distinct changes. In common with observers in the south of England, I noted the fresh appearance of the dust phenomena in the end of June, especially on June 26, but they were not very striking until August 1. At first the most decidedly volcanic feature was the great corona round the

T. W. Backhouse

1902-01-01

43

Coupled Phenomena in Chemistry.  

ERIC Educational Resources Information Center

Various phenomena in chemistry and biology can be understood through Gibbs energy utilization. Some common phenomena in chemistry are explained including neutralization, hydrolysis, oxidation and reaction, simultaneous dissociation equilibrium of two weak acids, and common ion effect on solubility. (Author/SA)

Matsubara, Akira; Nomura, Kazuo

1979-01-01

44

Topological Anderson insulator phenomena  

NASA Astrophysics Data System (ADS)

We study the nature of the disorder-induced quantized conductance, i.e., the phenomena of topological Anderson insulator (TAI). The disorder effect in several different systems where the anomalous Hall effect exists is numerically studied using the tight-binding Hamiltonian. It is found that the TAI phenomena can also exist in the modified Dirac model where the quadratic corrections k2?z are included and the electron-hole symmetry is kept. These phenomena also occur in the graphene system with the next-nearest-neighbor coupling and the staggered sublattice potential. For the graphene sheet with Rashba spin-orbit interaction as well as an exchange field, a precursor of TAI is observed. A comparison between the localization length of the two-dimensional ribbon and two-dimensional cylinder structures clearly reveals the topological nature of these phenomena. Furthermore, analysis on the local current density in anomalous quantum Hall systems where the TAI phenomena may or may not arise reveals the nature of TAI phenomena. In the presence of small disorders, the conductance is not quantized and the bulk and edge states coexist in the system. As disorder strength increases, the bulk state is quickly destroyed, while the robust edge state may survive. When the edge state is robust enough to sustain the strong disorder that completely kills the bulk state, TAI phenomena arise.

Xing, Yanxia; Zhang, Lei; Wang, Jian

2011-07-01

45

Science and Paranormal Phenomena  

SciTech Connect

In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ''historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ''paranormal phenomena'' might-but need not- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be defined as contradicting physics.

Noyes, H. Pierre

1999-06-03

46

Volume tracing of atmospheric environments  

Microsoft Academic Search

Current three-dimensional computer graphics assumes a vacuum space. The inclusion of atmosphere is essential for the modeling and rendering of natural phenomena. This paper presents a method of modeling atmospheric effects and rendering them using a volume tracing renderer. The model is built within a framework called the atmospheric cube. The atmospheric cube, or the A-cube, is a finite volume

Masa Inakage

1991-01-01

47

Meteor Phenomena and Bodies  

Microsoft Academic Search

Meteoroids can be observed at collision with the Earth's atmosphere as meteors. Different methods of observing meteors are\\u000a presented: besides the traditional counts of individual events, exact methods yield also data on the geometry of the atmospheric\\u000a trajectory; on the dynamics and ablation of the body in the atmosphere; on radiation; on the spectral distribution of radiation;\\u000a on ionization; on

Zden?k Ceplecha; Ji?Í Borovi?ka; W. Graham Elford; Douglas O. ReVelle; Robert L. Hawkes; VladimÍr Porub?an; Miloš Šimek

1998-01-01

48

Stress pulse phenomena  

SciTech Connect

This paper is an introductory discussion of stress pulse phenomena in simple solids and fluids. Stress pulse phenomena is a very rich and complex field that has been studied by many scientists and engineers. This paper describes the behavior of stress pulses in idealized materials. Inviscid fluids and simple solids are realistic enough to illustrate the basic behavior of stress pulses. Sections 2 through 8 deal with the behavior of pressure pulses. Pressure is best thought of as the average stress at a point. Section 9 deals with shear stresses which are most important in studying solids.

McGlaun, M.

1993-08-01

49

Imaging of snapping phenomena.  

PubMed

Snapping phenomena result from the sudden impingement between anatomical and/or heterotopical structures with subsequent abrupt movement and noise. Snaps are variously perceived by patients, from mild discomfort to significant pain requiring surgical management. Identifying the precise cause of snaps may be challenging when no abnormality is encountered on routinely performed static examinations. In this regard, dynamic imaging techniques have been developed over time, with various degrees of success. This review encompasses the main features of each imaging technique and proposes an overview of the main snapping phenomena in the musculoskeletal system. PMID:22744321

Guillin, R; Marchand, A J; Roux, A; Niederberger, E; Duvauferrier, R

2012-10-01

50

Transport phenomena in nanofluidics  

Microsoft Academic Search

The transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100nm enables the occurrence of phenomena that are impossible at bigger length scales. This research field was only recently termed nanofluidics, but it has deep roots in science and technology. Nanofluidics has experienced considerable growth in recent years, as is confirmed by significant scientific

Reto B. Schoch; Jongyoon Han; Philippe Renaud

2008-01-01

51

Blood flow multiscale phenomena.  

PubMed

The cardiovascular disease is one of most frequent cause deaths in modern society. The objective of this work is analyse the effect of dynamic vascular geometry (curvature, torsion, bifurcation) and pulsatile blood nature on secondary flow, wall shear stress and platelet deposition. The problem was examined as multi-scale physical phenomena using perturbation analysis and numerical modelling. The secondary flow determined as influence pulsatile pressure, vascular tube time-dependent bending and torsion on the main axial flow. Bifurcation and branching phenomena are analysed experimentally through, blood-like fluid pulsatile flow across elastic rubber-like Y-model model. The problem complex geometry near branching in platelet deposit modelling is resolved numerically as Falker-Skan flow. PMID:17847933

Agi?, Ante; Mijovi?, Budimir; Nikoli?, Tatjana

2007-06-01

52

Lunar transient phenomena  

NASA Astrophysics Data System (ADS)

Lunar transient phenomena (LTP) sightings are classified into five categories: brightenings, darkenings, reddish colorations, bluish colorations, and obscurations. There is evidence that the remaining LTP's are of lunar origin. A substantial number of sightings are independently confirmed. They have been recorded on film and spectrograms, as well as with photoelectric photometers and polarization equipment. It suggested that the LTP's may be gentle outgassings of less-than-volcanic proportions.

Cameron, W. S.

1991-03-01

53

Visual hallucinations as release phenomena  

Microsoft Academic Search

Whereas episodic, stereotype hallucinations represent irritative phenomena, analogous to ictal attacks, the continuous, variable hallucinations are interpreted as release phenomena resulting from loss or suppression of the normal visual input. The latter have only limited topical significance.

David G. Cogan

1973-01-01

54

Wolf-Rayet phenomena  

NASA Technical Reports Server (NTRS)

The properties of stars showing Wolf-Rayet phenomena are outlined along with the direction of future work. Emphasis is placed on the characteristics of W-R spectra. Specifically the following topics are covered: the absolute visual magnitudes; the heterogeneity of WN spectra; the existence of transition type spectra and compositions the mass loss rates; and the existence of very luminous and possibly very massive W-R stars. Also, a brief overview of current understanding of the theoretical aspects of stellar evolution and stellar winds and the various scenarios that have been proposed to understand W-R spectra are included.

Conti, P. S.

1982-01-01

55

High Intensity Laser Propagation in the Atmosphere.  

National Technical Information Service (NTIS)

The phenomena which constitute ultimate limitations to the transmission of intense laser radiation through the atmosphere are investigated, namely, self-defocusing due to atmospheric heating and the stimulated Raman effect. The heating studies are concern...

D. Arnush L. M. Frantz T. D. Holstein

1967-01-01

56

Time-variable phenomena in the Jovian system  

SciTech Connect

The current state of knowledge of dynamic processes in the Jovian system is assessed and summaries are provided of both theoretical and observational foundations upon which future research might be based. There are three sections: satellite phenomena and rings; magnetospheric phenomena, Io's torus, and aurorae; and atmospheric phenomena. Each chapter discusses time dependent theoretical framework for understanding and interpreting what is observed; others describe the evidence and nature of observed changes or their absence. A few chapters provide historical perspective and attempt to present a comprehensive synthesis of the current state of knowledge.

Belton, M.J.S.; West, R.A.; Rahe, J.; Pereyda, M.

1989-01-01

57

Weld pool phenomena  

SciTech Connect

During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

David, S.A.; Vitek, J.M.; Zacharia, T. [Oak Ridge National Lab., TN (United States); DebRoy, T. [Pennsylvania State Univ., University Park, PA (United States)

1994-09-01

58

PREFACE Integrability and nonlinear phenomena Integrability and nonlinear phenomena  

NASA Astrophysics Data System (ADS)

Back in 1967, Clifford Gardner, John Greene, Martin Kruskal and Robert Miura published a seminal paper in Physical Review Letters which was to become a cornerstone in the theory of integrable systems. In 2006, the authors of this paper received the AMS Steele Prize. In this award the AMS pointed out that `In applications of mathematics, solitons and their descendants (kinks, anti-kinks, instantons, and breathers) have entered and changed such diverse fields as nonlinear optics, plasma physics, and ocean, atmospheric, and planetary sciences. Nonlinearity has undergone a revolution: from a nuisance to be eliminated, to a new tool to be exploited.' From this discovery the modern theory of integrability bloomed, leading scientists to a deep understanding of many nonlinear phenomena which is by no means reachable by perturbation methods or other previous tools from linear theories. Nonlinear phenomena appear everywhere in nature, their description and understanding is therefore of great interest both from the theoretical and applicative point of view. If a nonlinear phenomenon can be represented by an integrable system then we have at our disposal a variety of tools to achieve a better mathematical description of the phenomenon. This special issue is largely dedicated to investigations of nonlinear phenomena which are related to the concept of integrability, either involving integrable systems themselves or because they use techniques from the theory of integrability. The idea of this special issue originated during the 18th edition of the Nonlinear Evolution Equations and Dynamical Systems (NEEDS) workshop, held at Isola Rossa, Sardinia, Italy, 16-23 May 2009 (http://needs-conferences.net/2009/). The issue benefits from the occasion offered by the meeting, in particular by its mini-workshops programme, and contains invited review papers and contributed papers. It is worth pointing out that there was an open call for papers and all contributions were peer reviewed according to the standards of the journal. The selection of papers in this issue aims to bring together recent developments and findings, even though it consists of only a fraction of the impressive developments in recent years which have affected a broad range of fields, including the theory of special functions, quantum integrable systems, numerical analysis, cellular automata, representations of quantum groups, symmetries of difference equations, discrete geometry, among others. The special issue begins with four review papers: Integrable models in nonlinear optics and soliton solutions Degasperis [1] reviews integrable models in nonlinear optics. He presents a number of approximate models which are integrable and illustrates the links between the mathematical and applicative aspects of the theory of integrable dynamical systems. In particular he discusses the recent impact of boomeronic-type wave equations on applications arising in the context of the resonant interaction of three waves. Hamiltonian PDEs: deformations, integrability, solutions Dubrovin [2] presents classification results for systems of nonlinear Hamiltonian partial differential equations (PDEs) in one spatial dimension. In particular he uses a perturbative approach to the theory of integrability of these systems and discusses their solutions. He conjectures universality of the critical behaviour for the solutions, where the notion of universality refers to asymptotic independence of the structure of solutions (at the point of gradient catastrophe) from the choice of generic initial data as well as from the choice of a generic PDE. KP solitons in shallow water Kodama [3] presents a survey of recent studies on soliton solutions of the Kadomtsev-Petviashvili (KP) equation. A large variety of exact soliton solutions of the KP equation are presented and classified. The study includes numerical analysis of the stability of the found solution as well as numerical simulations of the initial value problems which indicate that a certain class of initial waves approach asymptotically these exact solutions

Gómez-Ullate, David; Lombardo, Sara; Mañas, Manuel; Mazzocco, Marta; Nijhoff, Frank; Sommacal, Matteo

2010-10-01

59

Photorespiratory Phenomena in Maize  

PubMed Central

Concurrent O2 evolution, O2 uptake, and CO2 uptake by illuminated maize (Zea mays) leaves were measured using 13CO2 and 18O2. Considerable O2 uptake occurred during active photosynthesis. At CO2 compensation, O2 uptake increased. Associated with this increase was a decrease in O2 release such that a stoichiometric exchange of O2 occurred. The rate of O2 exchange at CO2 compensation was directly related to O2 concentration in the atmosphere at least up to 8% (v/v). When illuminated maize leaves were exposed to saturating CO2 concentrations containing approximately equal amounts of 12CO2 and 13CO2, the latter was taken up more rapidly, thus depressing the atom% 13C in the atmosphere. Moreover, upon exposure to CO2 containing 96 atom% 13C, there occurred a directly measurable efflux of 12CO2 from the leaves for at least 15 minutes. During this period an equimolar evolution of 16O2 and uptake of 13CO2 was observed. Thereafter, although the rate of 16O2 evolution remained unchanged, the rate of 13CO2 uptake declined markedly, suggesting continual 13C enrichment of the photorespiratory substrate. It is concluded that a finite photorespiratory process occurs in maize and that the CO2 generated thereby is efficiently recycled. Recycling maintains the internal CO2 concentration at a level difficult to detect by most photorespiratory assays.

Volk, R. J.; Jackson, W. A.

1972-01-01

60

Wolf-Rayet phenomena  

NASA Technical Reports Server (NTRS)

An outline is presented of what is currently known about the properties of stars showing Wolf-Rayet (W-R) phenomena, taking into account also the directions in which future work is leading. W-R spectra are found to be primarily an emission line spectrum superimposed on a 'hot' continuous spectrum. P Cygni absorption components are observed for some lines in some stars. A fact not realized when Thomas (1968) discussed W-R spectra is that a very few W-R stars have intrinsic absorption lines. On the basis of the spectroscopic observations, it could now be inferred that an optically thick stellar wind is involved. Many of the WN subtypes do contain some carbon. The WC subtypes contain little or no nitrogen. Attention is given to absolute visual magnitudes of W-R stars, the heterogeneity of W-R spectra, transition W-R spectra, mass loss rates, very luminous W-R objects, theoretical aspects of stellar structure and stellar winds, and evolutionary scenarios.

Conti, P. S.

1982-01-01

61

On Detecting Transient Phenomena  

NASA Astrophysics Data System (ADS)

Transient phenomena are interesting and potentially highly revealing of details about the processes under observation and study that could otherwise go unnoticed. It is therefore important to maximize the sensitivity of the method used to identify such events. In this article, we present a general procedure based on the use of the likelihood function for identifying transients which is particularly suited for real-time applications because it requires no grouping or pre-processing of the data. The method makes use of all the information that is available in the data throughout the statistical decision-making process, and is suitable for a wide range of applications. Here we consider those most common in astrophysics, which involve searching for transient sources, events or features in images, time series, energy spectra, and power spectra, and demonstrate the use of the method in the case of a weak X-ray flare in a time series and a short-lived quasi-periodic oscillation in a power spectrum. We derive a fit statistic that is ideal for fitting arbitrarily shaped models to a power density distribution, which is of general interest in all applications involving periodogram analysis.

Bélanger, G.

2013-08-01

62

Resolving Localisation Phenomena  

NASA Astrophysics Data System (ADS)

Realistic numerical models of the Earth's crust and lithosphere require consitutive models which account for brittle/semi-brittle deformation. These are typically nonlinear, and produce localisation phenomena (e.g. faults, shear bands). The presence of a fault can cause variations in the deformation field over a length of the order of the fault / fault-zone thickness ?. Depending on the overall scale of the numerical model (global or regional), the interpretation of the fault thickness may vary, however it is typically the feature with the smallest length scale in the system. In order to accurately compute the stress and strain rate from our numerical models, we must ensure that we resolve shear bands to the point where characteristic patterns no longer change with resolution. This means using a discretisation which can resolve length scales of size ?. This is computationally difficult as the location of the shear band are not predefined. Furthermore, the length scale ? is typically several orders of magnitude smaller than the size of the domain. We have developed a numerical scheme suitable for modelling crustal/lithosphere deformation which dynamically modifies the spatial resolution in the vicinity of shear bands. The method comprises a mixed eulerian/lagrangian approach employing both finite elements and moving material points. Adaptivity at the grid and material point level is introduced using techniques from the nonlinear, adaptive finite elements. By combining standard element based error estimators and recovery techniques we can obtain continuous solutions for u_i, p and ?ij which are accurate to within a specified tolerance though out the entire domain. We show that the optimal rate of convergence is obtained for all fields and illustrate the effectiveness of the adaptive material point method via some simple localisation problems.

May, D.; Moresi, L.

2006-12-01

63

Everyday Phenomena and Teachers' Training.  

ERIC Educational Resources Information Center

Investigated the ability of Swedish student teachers to explain everyday phenomena in science education, asking all fourth-term student teachers about phenomena where transformations of matter were involved. Analysis of students' written answers indicates that there is a great need in teacher training to work with conceptual understanding and with…

Eskilsson, Olle; Holgersson, Ingemar

1999-01-01

64

Phenomena resulting from hypergolic contact  

NASA Astrophysics Data System (ADS)

Understanding hypergolic ignition is critical for the safe and successful operation of hypergolic engines. The complex coupling of physical and chemical processes during hypergolic ignition complicates analysis of the event. Presently, hypergolic ignition models cannot simulate liquid contact and mixing or liquid-phase chemical reactions, and rely on experimental results for validation. In some cases, chemical kinetics of hypergolic propellants and fluid dynamics of droplet collisions couple to produce unexpected phenomena. This research investigates contact between droplets and pools of liquid hypergolic propellants under various conditions in order to investigate these liquid-phase reactions and categorize the resulting interaction. During this experiment, 142 drop tests were performed to investigate phenomena associated with hypergolic contact of various propellants. A drop of fuel impacted a semi-ellipsoidal pool of oxidizer at varying impact velocities and impact geometries. The temperature, pressure, ambient atmosphere, and propellant quality were all controlled during the experiment, as these factors have been shown to influence hypergolic ignition delay. Three distinct types of impacts were identified: explosions, bounces, and splashes. The impact type was found to depend on the impact Weber number and impact angle. Splashes occurred above a critical Weber number of 250, regardless of impact angle. Explosions occurred for Weber numbers less than 250, and for impact angles less than seven degrees. If the impact angle was greater than seven degrees then the test resulted in a bounce. Literature related to explosions induced by hypergolic contact was reviewed. Explosions were observed to occur inconsistently, a feature that has never been addressed. Literature related to non-reactive splashing, bouncing, and coalescence was reviewed for insight into the explosion phenomenon. I propose that the dependence of impact angle on the transition between explosion and bounce impacts is partially responsible for the explosion inconsistency in literature. No explosions were observed for the alternative hypergolic propellants tested, which could be due to lower gas production rates or the absence of reactive intermediate species present in certain propellant chemistry. In either case, the fluid dynamics of the impact was consistent, but the chemical kinetics of the propellants were different, and presumably, the two did not couple as strongly. Based on the results, explosions appear to be a mixing driven process caused by the coupling between the fluid dynamics of the impact and the chemical kinetics of the propellants. Upon contact, the fuel drop merges with the oxidizer pool. Liquid-phase neutralization reactions produce enough heat to vaporize propellants, which then accumulate within a gas pocket inside the pool. Exothermic gas-phase reactions result in an explosion originating from within the propellant pool. In addition to investigation of the explosion phenomenon, high-speed videos were taken of the first microseconds of hypergolic contact to observe the liquid-phase chemical reactions in detail. The delay between contact and first gas production was measured to be between 20 and 200 microseconds for monomethylhydrazine and red fuming nitric acid. This delay provides insight into the speed of the liquid-phase chemical reactions, and has helped to calibrate liquid-based ignition models. This research has categorized different interactions resulting from hypergolic contact, and found that the impact Weber number and impact angle were the controlling parameters. I propose that slight changes in the impact angle went unobserved by previous researchers and were partially responsible for the explosion inconsistency in literature. Microsecond scale time delays were measured between contact and gas production and have been used to calibrate previously unknown rate constants of liquid-phase chemical reactions.

Forness, Jordan M.

65

Critical velocity phenomena and the LTP. [Lunar Transient Phenomena  

NASA Technical Reports Server (NTRS)

When the relative velocity between magnetized plasma and neutral gas exceeds a critical value, the gas-plasma interaction is dominated by collective phenomena which rapidly excite and ionize the neutrals. The interaction of the solar wind with a large cloud (between 10 to the 24th and 10 to the 28th power neutrals) vented from the moon should be of this type. Line radiation from such an interaction can yield an apparent lunar surface brightness rivaling reflected sunlight levels over small areas, if the kinetic-energy flow density of the gas is sufficiently high. The aberrated solar-wind flow past the moon would enhance the visibility of such interactions near the lunar sunrise terminator, supporting the statistical studies which indicate that the 'Lunar Transient Phenomena' (anomalous optical phenomena on the moon) are significantly correlated with the position of the terminator on the lunar surface.

Srnka, L. J.

1977-01-01

66

Dynamic phenomena in coronal flux tubes  

NASA Technical Reports Server (NTRS)

The study of stellar atmospheres and the determination of specific physical mechanisms, geometries, and magnetic structures by which coronae are maintained is examined. Ultraviolet and soft X-ray components observed in the radiative output of cool stars and the Sun require counterentropic temperature gradients for their explanation. The existence of a hot corona is recognized as a result of mechanical or fluid dynamic effects and the importance of the magnetic field in the heating is accepted. Magnetohydrodynamic energy release associated with the emergence of magnetic flux through the chromosphere and its dynamic readjustment in the corona are major counterentropic phenomena which are considered as primary candidates for corona heating. Systematic plows in coronal flux tubes result from asymmetric heating and systematic flows can exist without substantial chromospheric pressure differences.

Mariska, J. T.; Boris, J. P.

1981-01-01

67

Abnormal pressures as hydrodynamic phenomena  

USGS Publications Warehouse

So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

Neuzil, C. E.

1995-01-01

68

Luminescence Phenomena in Magnesium Oxide.  

National Technical Information Service (NTIS)

Both intrinsic and impurity centers contribute to x-ray fluorescence and thermoluminescence phenomena in magnesium oxide. It was shown earlier that a thermoluminescent formation of Cr(2+) from Cr(3+) is accompanied by a conversion of Fe(1+) to Fe(2+) and ...

J. E. Wertz L. C. Hall J. Helgeson C. C. Chao W. S. Dykoski

1967-01-01

69

Virtual Physics Laboratory: Wave Phenomena  

NSDL National Science Digital Library

This site from Northwestern University discusses wave phenomena. The site features interactive applets of various wave types, including longitudinal, transverse, mixed, and sound waves. Also included are animations of superposition, beat frequencies, and the distinction between phase and group velocities, wave packets, and wave reflections.

Astronomy, The D.; University, Northwestern

70

Optical Phenomena in the Aether  

Microsoft Academic Search

Although the theory of light seems completed and many believe that the behavior of light has been accounted for down to the most insignificant detail, there are certain experimental facts in optics for which explanations are still unsatisfactory. It may seem surprising - but nevertheless true - if we state that in fact the most basic phenomena of reflection and

Ionel DINU

71

Quantum Phenomena Observed Using Electrons  

SciTech Connect

Electron phase microscopy based on the Aharonov-Bohm (AB) effect principle has been used to illuminate fundamental phenomena concerning magnetism and superconductivity by visualizing quantitative magnetic lines of force. This paper deals with confirmation experiments on the AB effect, the magnetization process of tiny magnetic heads for perpendicular recording, and vortex behaviors in high-Tc superconductors.

Tonomura, Akira [Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0412 (Japan); Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395 (Japan); Advanced Science Institute, RIKEN, Wako, Saitama, 351-0198 (Japan)

2011-05-06

72

Global atmospheric changes.  

PubMed

Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the processes that are responsible for the greenhouse effect, air pollution, acid deposition, and increased exposure to UV radiation. PMID:1820255

Piver, W T

1991-12-01

73

Visible Earth: Atmosphere  

NSDL National Science Digital Library

This site is part of Visible Earth, which is hosted by the National Aeronautics and Space Administration (NASA), and contains a searchable directory of images, visualizations, and animations of the Earth. This section contains images of the Earth's atmosphere, which includes aerosols, air quality, atmospheric phenomena, pressure, radiation, temperature, water, winds, clouds, precipitation, and earth's radiation bidget. Each image is available in a variety of resolutions and sizes, with a brief description, credit, date, and the name of the spacecraft or instrument that captured the image.

74

Global atmospheric changes.  

PubMed Central

Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the processes that are responsible for the greenhouse effect, air pollution, acid deposition, and increased exposure to UV radiation.

Piver, W T

1991-01-01

75

Middle Atmosphere Program. Handbook for MAP, volume 10  

NASA Technical Reports Server (NTRS)

The contributions of ground based investigations to the study of middle atmospheric phenomena are addressed. General topics include diagnostics of the middle atmosphere from D region properties, winter anomaly, seasonal variations and disturbances, dynamics and theoretical models, ground based tracking of winds and waves, lower thermosphere phenomena, and solar-terrestrial influences.

Taubenheim, J. (editor)

1984-01-01

76

Statistical phenomena in particle beams  

SciTech Connect

Particle beams are subject to a variety of apparently distinct statistical phenomena such as intrabeam scattering, stochastic cooling, electron cooling, coherent instabilities, and radiofrequency noise diffusion. In fact, both the physics and mathematical description of these mechanisms are quite similar, with the notion of correlation as a powerful unifying principle. In this presentation we will attempt to provide both a physical and a mathematical basis for understanding the wide range of statistical phenomena that have been discussed. In the course of this study the tools of the trade will be introduced, e.g., the Vlasov and Fokker-Planck equations, noise theory, correlation functions, and beam transfer functions. Although a major concern will be to provide equations for analyzing machine design, the primary goal is to introduce a basic set of physical concepts having a very broad range of applicability.

Bisognano, J.J.

1984-09-01

77

Thermodynamic constraints on fluctuation phenomena  

NASA Astrophysics Data System (ADS)

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.

Maroney, O. J. E.

2009-12-01

78

Thermodynamic constraints on fluctuation phenomena.  

PubMed

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. PMID:20365152

Maroney, O J E

2009-12-01

79

Insulation Phenomena of Compressed Air  

Microsoft Academic Search

Test data on impulse and 60-cycle voltage breakdown strength for compressed air with various electrode configurations are reported. The tests were made with rod-to-plane electrodes with spacings up to 8 inches and pressures to 250 psig (pounds per square inch gage). Breakdown phenomena of air insulation encountered in the development of an air insulated air-blast circuit breaker1 are reported. The

L. D. McConnell

1957-01-01

80

Multiparticle phenomena and Landau damping  

SciTech Connect

The purpose of this paper is to survey various methods of studying multiparticle phenomena in accelerators. Both experimental and theoretical methods are described. An effort has been made to emphasize the intuitive and qualitative aspects rather than the detailed mathematics. Some of the terms or concepts to be explained are coherent and incoherent tunes, normal modes, Landau damping, beam-transfer functions, and feedback. These are all of daily importance in the interpretation of colliding-beam observations and the control of performance.

Talman, R.

1987-02-25

81

Visualization of solidification front phenomena  

NASA Technical Reports Server (NTRS)

Directional solidification experiments have been utilized throughout the Materials Processing in Space Program to provide an experimental platform which minimizes variables in solidification experiments. Because of the wide-spread use of this experimental technique in space-based research, it has become apparent that a better understanding of all the phenomena occurring during solidification can be better understood if direct visualization of the solidification interface were possible.

Workman, Gary L.; Smith, Guy A.

1993-01-01

82

New phenomena searches at CDF  

SciTech Connect

The authors report on recent results from the Collider Detector at Fermilab (CDF) experiment, which is accumulating data from proton-antiproton collisions with {radical}s = 1.96 TeV at Run II of the Fermilab Tevatron. The new phenomena being explored include Higgs, Supersymmetry, and large extra dimensions. They also present the latest results of searches for heavy objects, which would indicate physics beyond the Standard Model.

Soha, Aron; /UC, Davis

2006-04-01

83

Mathematical Modeling of Diverse Phenomena  

NASA Technical Reports Server (NTRS)

Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.

Howard, J. C.

1979-01-01

84

Meteorological phenomena in Western classical orchestral music  

NASA Astrophysics Data System (ADS)

The creative output of composers, writers, and artists is often influenced by their surroundings. To give a literary example, it has been claimed recently that some of the characters in Oliver Twist and A Christmas Carol were based on real-life people who lived near Charles Dickens in London. Of course, an important part of what we see and hear is not only the people with whom we interact, but also our geophysical surroundings. Of all the geophysical phenomena to influence us, the weather is arguably the most significant, because we are exposed to it directly and daily. The weather was a great source of inspiration for Monet, Constable, and Turner, who are known for their scientifically accurate paintings of the skies. But to what extent does weather inspire composers? The authors of this presentation, who are atmospheric scientists by day but amateur classical musicians by night, have been contemplating this question. We have built a systematic musical database, which has allowed us to catalogue and analyze the frequencies with which weather is depicted in a sample of classical orchestral music. The depictions vary from explicit mimicry using traditional and specialized orchestral instruments, through to subtle suggestions. We have found that composers are generally influenced by their own environment in the type of weather they choose to represent. As befits the national stereotype, British composers seem disproportionately keen to depict the UK's variable weather patterns and stormy coastline. Reference: Aplin KL and Williams PD (2011) Meteorological phenomena in Western classical orchestral music. Weather, 66(11), pp 300-306. doi:10.1002/wea.765

Williams, P. D.; Aplin, K. L.

2012-12-01

85

TRANSIENT LUNAR PHENOMENA: REGULARITY AND REALITY  

SciTech Connect

Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled, and even their existence as a coherent phenomenon is controversial. Nonetheless, TLP data show regularities in the observations; a key question is whether this structure is imposed by processes tied to the lunar surface, or by terrestrial atmospheric or human observer effects. I interrogate an extensive catalog of TLPs to gauge how human factors determine the distribution of TLP reports. The sample is grouped according to variables which should produce differing results if determining factors involve humans, and not reflecting phenomena tied to the lunar surface. Features dependent on human factors can then be excluded. Regardless of how the sample is split, the results are similar: {approx}50% of reports originate from near Aristarchus, {approx}16% from Plato, {approx}6% from recent, major impacts (Copernicus, Kepler, Tycho, and Aristarchus), plus several at Grimaldi. Mare Crisium produces a robust signal in some cases (however, Crisium is too large for a 'feature' as defined). TLP count consistency for these features indicates that {approx}80% of these may be real. Some commonly reported sites disappear from the robust averages, including Alphonsus, Ross D, and Gassendi. These reports begin almost exclusively after 1955, when TLPs became widely known and many more (and inexperienced) observers searched for TLPs. In a companion paper, we compare the spatial distribution of robust TLP sites to transient outgassing (seen by Apollo and Lunar Prospector instruments). To a high confidence, robust TLP sites and those of lunar outgassing correlate strongly, further arguing for the reality of TLPs.

Crotts, Arlin P. S. [Department of Astronomy, Columbia University, Columbia Astrophysics Laboratory, 550 West 120th Street, New York, NY 10027 (United States)

2009-05-20

86

Astronomy and Atmospheric Optics  

NASA Astrophysics Data System (ADS)

The authors discusse the insuccess of the observation of the Total Eclipse of the Moon from 10 december 2011 in Romania and relate them with meteoconditions. Only a very short part of the last penumbral phase was observed, while the inital part and the totality was not observed due to very dense clouds. The change in color and brightness during this phase was signaled. Meanwhile, there is an area of science where clouds are of great use and interest. This area is Atmospheric optics, while the science which study clouds is meteorology. Clouds in combination with Solar and Moon light could give rise to a variety of strange, rare and unobvious phenomena in the atmosphere (sky), sometimes confused with Unidentified Flying Objects (UFO). The importance of meteorology for astronomy and atmospheric optics is underlined and an invitation to astronomers to use unfavourable days for athmospheric observations was sent. The web address of the site by Les Cowley, designed for atmospheric optics phenomena is contained in the text of the entry.

Cowley, Les; Gaina, Alex

2011-12-01

87

Jovian atmospheres  

SciTech Connect

A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers.

Allison, M.; Travis, L.D.

1986-10-01

88

BWR core melt progression phenomena: Experimental analyses.  

National Technical Information Service (NTIS)

In the BWR Core Melt in Progression Phenomena Program, experimental results concerning severe fuel damage and core melt progression in BWR core geometry are used to evaluate existing models of the governing phenomena. These include control blade eutectic ...

L. J. Ott

1992-01-01

89

Measurements of Atmospheric Electricity Aloft  

NASA Astrophysics Data System (ADS)

Measurements of the electrical characteristics of the atmosphere above the surface have been made for over 200 years, from a variety of different platforms, including kites, balloons, rockets and aircraft. From these measurements, a great deal of information about the electrical characteristics of the atmosphere has been gained, assisting our understanding of the global atmospheric electric circuit, thunderstorm electrification and lightning generation mechanisms, discovery of transient luminous events above thunderstorms and many other electrical phenomena. This paper surveys the history of atmospheric electrical measurements aloft, from the earliest manned balloon ascents to current day observations with free balloons and aircraft. Measurements of atmospheric electrical parameters in a range of meteorological conditions are described, including clear air conditions, polluted conditions, non-thunderstorm clouds, and thunderstorm clouds, spanning a range of atmospheric conditions, from fair weather to the most electrically active.

Nicoll, K. A.

2012-09-01

90

Correlated randomness and switching phenomena  

NASA Astrophysics Data System (ADS)

One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

2010-08-01

91

Transport phenomena in porous media  

NASA Astrophysics Data System (ADS)

The Advanced Study Institute on Fundamentals of Transport Phenomena in Porous Media, held July 14-23, 1985 in Newark, Del. and directed by Jacob Bear (Israel Institute of Technology, Haifa) and M. Yavuz Corapcioglu (City College of New York), under the auspices of NATO, was a sequel to the NATO Advanced Study Institute (ASI) held in 1982 (proceedings published as Fundamentals of Transport Phenomena in Porous Media, J. Bear, and M.Y. Corapcioglu (Ed.), Martinus Nijhoff, Dordrecht, the Netherlands, 1984). The meeting was attended by 106 participants and lecturers from 21 countries.As in the first NATO/ASI, the objective of this meeting—which was a combination of a conference of experts and a teaching institute— was to present and discuss selected topics of transport in porous media. In selecting topics and lecturers, an attempt was made to bridge the gap that sometimes exists between research and practice. An effort was also made to demonstrate the unified approach to the transport of mass of a fluid phase, components of a fluid phase, momentum, and heat in a porous medium domain. The void space may be occupied by a single fluid phase or by a number of such phases; each fluid may constitute a multicomponent system; the solid matrix may be deformable; and the whole process of transport in the system may take place under nonisothermal conditions, with or without phase changes. Such phenomena are encountered in a variety of disciplines, e.g., petroleum engineering, civil engineering (in connection with groundwater flow and contamination), soil mechanics, and chemical engineering. One of the goals of the 1985 NATO/ASI, as in the 1982 institute, was to bring together experts from all these disciplines and enhance communication among them.

Bear, Jacob; Corapcioglu, M. Yavuz

92

Phenomena and Diosignes of Aratous  

NASA Astrophysics Data System (ADS)

Aratous (305-240B.C.) was a singular intellectual, writer and poet which engage himself to compose a very interesting astronomical poet, using the "Dactylous sixstage' style, the formal style of the ancient Greek Epic poetry. This astronomic poem of Aratous "Phenomena and Diosignes" became very favorite reading during the Alexandrine, the Romman and the Byzandin eras as well and had received many praises from significant poets and particularly from Hipparchous and from Theonas from Alexandria, an astronomer of 4rth century A.C.(in Greeks)

Avgoloupis, S. I.

2013-01-01

93

Natural phenomena hazards, Hanford Site, Washington  

SciTech Connect

This document presents the natural phenomena hazard loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, and supports development of double-shell tank systems specifications at the Hanford Site in south-central Washington State. The natural phenomena covered are seismic, flood, wind, volcanic ash, lightning, snow, temperature, solar radiation, suspended sediment, and relative humidity.

Conrads, T.J.

1998-09-29

94

BOOK REVIEW: Plasma Kinetics in Atmospheric Gases  

Microsoft Academic Search

The book Plasma Kinetics in Atmospheric Gases is a worthwhile contribution to the basic phenomena in nitrogen, oxygen and other atmospheric gases. It contains basic introductory chapters on relaxation in translational, rotational (short) and vibrational (extensive) distribution and on the physics of electron excitation and electron distribution functions. In the latter, electron beam excitation (i.e. high electron energies) are included.

M. Capitelli; C. M. Ferreira; B. F. Gordiets; A. I. Osipov

2001-01-01

95

Sea-surface signatures of the island mass effect phenomena around Madeira Island, Northeast Atlantic  

Microsoft Academic Search

This is an introductory work that describes the manifestation of the island mass effect phenomena in the atmosphere and at the sea surface for a region of the ocean depleted from oceanographic work—the Madeira Archipelago (33°N, 17°W). The use of remote sensing tools becomes essential in recognizing some of the sea-surface features that characterize the island mass effect phenomena. AVHRR,

R. M. A. Caldeira; S. Groom; P. Miller; D. Pilgrim; N. P. Nezlin

2002-01-01

96

Ultraviolet observations of astronomical phenomena  

NASA Technical Reports Server (NTRS)

The purpose was to study various aspects of mass loss in stars of different types. The observational part of the research was directed at three Cepheid variables; the archival part of the research was directed at hot stars (for information on corotating interaction regions) and at cool giants (for study of variability in the mass losing part of the atmosphere).

Mullan, D. J.

1986-01-01

97

Uranium Pyrophoricity Phenomena and Prediction  

SciTech Connect

We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission facilities, and good documentation of experiences is surprisingly sparse. Today, these phenomena are important to site remediation and analysis of packaging, transportation, and processing of unirradiated metal scrap and spent nuclear fuel. Our document, bearing the same title as this paper, will soon be available in the Hanford document system [Plys, et al., 2000]. This paper explains general content of our topical reference and provides examples useful throughout the DOE complex. Moreover, the methods described here can be applied to analysis of potentially pyrophoric plutonium, metal, or metal hydride compounds provided that kinetic data are available. A key feature of this paper is a set of straightforward equations and values that are immediately applicable to safety analysis.

DUNCAN, D.R.

2000-04-20

98

Nonstationary Phenomena in the Heliosheath  

NASA Astrophysics Data System (ADS)

As Voyagers (V1 and V2) are approaching the heliopause (HP), they keep delivering important information about the solar wind (SW) behavior which sometimes appears to be substantially different at V1 and V2 locations. We argue that the observed differences may be attributed to SW variations. In particular, negative values of the radial velocity component derived from V1 observations may be due to the presence of time-dependent magnetic barriers formed due to the slow/fast wind interactions in the vicinity of solar cycle minima. The inner heliosheath is the venue of wave interaction, MHD instabilities, and turbulence. We further investigate these phenomena in the HP vicinity using a new, based on the Ulysses observations, solar cycle model. We show that some puzzling observational data, such as the difference in the heliocentric distances at which V1 and V2 crossed the termination shock, may be attributed to time-dependent effects. We also use other time-dependent sets of observational boundary conditions, e.g., interplanetary scintillation and OMNI data. Phenomena affecting the stability and shape of the HP are also discussed in the context of our time-dependent simulations. The satisfaction of the 2-3 kHz radio emission criteria beyond the HP is analyzed. Numerical results are validated by their comparison with observational data.

Pogorelov, N. V.; Borovikov, S. N.; Ebert, R. W.; Heerikhuisen, J.; Kim, T. K.; Kryukov, I.; Richardson, J. D.; Suess, S. T.; Zank, G. P.

2012-12-01

99

Atmospheric propagation effects relevant to optical communications  

NASA Technical Reports Server (NTRS)

A number of atmospheric phenomena affect the propagation of light. The effects of clear air turbulence are reviewed as well as atmospheric turbidity on optical communications. Among the phenomena considered are astronomical and random refraction, scintillation, beam broadening, spatial coherence, angle of arrival, aperture averaging, absorption and scattering, and the effect of opaque clouds. An extensive reference list is also provided for further study. Useful information on the atmospheric propagation of light in relation to optical deep space communications to an earth based receiving station is available, however, further data must be generated before such a link can be designed with committed performance.

Shaik, K. S.

1988-01-01

100

Atmospheric Propagation Effects Relevant to Optical Communications  

NASA Technical Reports Server (NTRS)

A number of atmospheric phenomena affect the propagation of light. This article reviews the effects of clear-air turbulence as well as atmospheric turbidity on optical communications. Among the phenomena considered are astronomical and random refraction, scintillation, beam broadening, spatial coherence, angle of arrival, aperture averaging, absorption and scattering, and the effect of opaque clouds. An extensive reference list is also provided for further study, Useful information on the atmospheric propagation of light in resolution to optical deep-space communications to an earth-based receiving station is available, however, further data must be generated before such a link can be designed with committed performance.

Shaik, K. S.

1988-01-01

101

EXPERT - Demonstrating Reentry Aerothermodinamics Phenomena from a System Perspective  

NASA Astrophysics Data System (ADS)

EXPERT is developed by the European Space Agency (ESA) in order to provide the scientific community with quality data on critical aero-thermodynamic phenomena encountered during hypersonic flights as well as to provide industry with system experience of re-entry vehicle manufacturing and development of hypersonic instrumentation. EXPERT is equipped with 14 experiments provided by several scientific institutions all around Europe. The experiments address major aerothermodinamics phenomena: TPS material characterization, surface catalysis and oxidation, plasma spectroscopy, laminar to turbulent transition, flow separation and reattachment, shock-boundary layer interactions, base flow characteristic and aerodynamic characterization of flap control surfaces. The paper focus on the status of the EXPERT project: the design activities and the on going manufacturing, the main challenges and the expected flight data results. EXPERT will benefit future atmospheric re- entry activities ranging from cargo to human orbital transportation systems as well as re-usable launchers and scientific probes.

Massobrio, F.; Passarelli, G.; Gavira-Izquierdo, J.; Ratti, F.

2011-08-01

102

Atmospheric effects on oblique impacts  

NASA Technical Reports Server (NTRS)

Laboratory experiments and theoretical calculations often use vertical impact angles (90 deg) in order to avoid the complicating effect of asymmetry. Nevertheless, oblique impacts represent the most likely starting condition for planetary cratering. Changing both impact angles and atmospheric pressure not only allows testing previous results for vertical impacts but also reveals phenomena whose signatures would otherwise be masked in the planetary cratering record. The laboratory studies were performed for investigating impact cratering processes. Impact angles can be increased from 0 to 90 deg in 15 deg increments while maintaining a flat target surface. Different atmospheres (nitrogen, argon, and helium) characterized the effects of both gas density and Mach number. Targets varied according to purpose. Because of the complexities in atmosphere-impactor-ejecta interactions, no single combination allows direct simulation of a planetary-scale (10-100 km) event. Nevertheless, fundamental processes and observed phenomena allow formulating first-order models at such broad scales.

Schultz, P. H.

1991-01-01

103

Are Moreton Waves Coronal Phenomena?  

NASA Astrophysics Data System (ADS)

We report on permeability characteristics of the upper solar atmosphere due to the progression of a Moreton wave. An exceptional Moreton wave is tracked to cover most of the Sun, following an unusually large solar X-ray flare observed on 2003 October 29. Using H? intensity and Doppler measurements, the Moreton wave is tracked for as long as 12 minutes. Moving outward, the wave circumnavigates strong-field active regions. The wave sweeps through solar magnetic neutral lines, disrupting material from filament and filament channels, thereby accentuating the visibility of the wave. We establish that the requirement for the visibility of a Moreton wave is the necessary presence of higher density material in the layers of the corona, besides reaffirming that Moreton waves are observed only when the speed of the disturbance exceeds Mach 2. We suggest that the cause can be a removal of significant amount of material from the solar upper atmosphere due to a coronal mass ejection.

Balasubramaniam, K. S.; Pevtsov, A. A.; Neidig, D. F.

2007-04-01

104

48 Optical Illusions & Visual Phenomena  

NSDL National Science Digital Library

Have you ever wondered how different optical illusions work? This fun, informative, and very cool website developed by ophthalmologist Dr. Michael Bach of the University of Freiburg's Medical School introduces 48 interactive visual illusions and phenomena. The illusions are animated and accompanied by explanations that help visitors make sense of their perceptual responses. Major illusion categories include: Motion & Time, Luminance & Contrast, Colour, Cognitive, and more. The site is still in progress, and Dr. Bach encourages both general feedback, and additional scientific information for improving the illusion explanations. The second site, also from Professor Bach, presents site users with an interactive, online Visual Acuity Test. Note: The Contrast component of the Test has yet to be implemented.

105

Critical phenomena in ferromagnetic superlattices  

NASA Astrophysics Data System (ADS)

Within the framework of the high-temperature series expansions technique, we examine the phase transition and the critical phenomena of a two-component superlattice with simple cubic structure, through three models: Ising, XY and Heisenberg. The reduced critical temperature of the system is studied as a function of the thickness of the constituents and the exchange interactions in each material, and within the interface. We show the existence of a critical thickness of the unit cell at which the reduced critical temperature of the binary superlattice remains insensitive to the exchange coupling within the interfaces. The values of the effective critical exponent ? eff associated with the magnetic susceptibility agreed with the universal classes in the limit cases where the superlattice is still comparable to an infinite simple cubic lattice. We attribute the breakdown in the universality hypothesis to the crossover effects.

Bakrim, H.

2005-06-01

106

Unidentified phenomena - Unusual plasma behavior?  

NASA Astrophysics Data System (ADS)

The paper describes observations of a phenomenon belonging to the UFO category and the possible causes of these events. Special attention is given to an event which occurred during the night of September 19-20, 1974, when a huge 'star' was observed over Pertrozavodsk (Russia), consisting of a bright-white luminous center, emitting beams of light, and a less bright light-blue shell. The star gradually formed a cometlike object with a tail consisting of beams of light and started to descend. It is suggested that this event was related to cosmic disturbances caused by an occurrence of unusually strong solar flares. Other examples are presented that relate unusual phenomena observed in space to the occurrence of strong magnetic turbulence events.

Avakian, S. V.; Kovalenok, V. V.

1992-06-01

107

Onset phenomena in MPD thrusters  

NASA Technical Reports Server (NTRS)

An experimental study has clarified some aspects of MPD thruster onset phenomena. The steep increase in terminal voltage that occurs as the onset current is approached may have different causes, depending on the propellant injection geometry. For propellant injection at the cathode radius, terminal voltage increase corresponds to a growing anode fall voltage; for injection at a larger radius, the increase is related to the back emf in the near-cathode plasma. The formation of the onset current pattern within the arc has been mapped experimentally as the thruster responds to an input current step which rises from below onset to the onset value. The appearance of terminal voltage hash at onset correlates with the extension into the exhaust region of a significant fraction of the arc current.

Barnett, J. W.; Jahn, R. G.

1985-01-01

108

In-vessel phenomena -- CORA  

SciTech Connect

Experiment-specific models have been employed since 1986 by Oak Ridge National Laboratory (ORNL) severe accident analysis programs for the purpose of boiling water reactor experimental planning and optimum interpretation of experimental results. The large integral tests performed to date, which start from an initial undamaged core state, have involved significantly different-from-prototypic boundary and experimental conditions because of either normal facility limitations or specific experimental constraints. These experiments (ACRR: DF-4, NRU: FLHT-6, and CORA) were designed to obtain specific phenomenological information such as the degradation and interaction of prototypic components and the effects on melt progression of control-blade materials and channel boxes. Applications of ORNL models specific to the KfK CORA-16 and CORA-17 experiments are discussed and significant findings from the experimental analyses such as the following are presented: applicability of available Zircaloy oxidation kinetics correlations; influence of cladding strain on Zircaloy oxidation; influence of spacer grids on the structural heatup; and the impact of treating the gaseous coolant as a gray interacting medium. The experiment-specific models supplement and support the systems-level accident analysis codes. They allow the analyst to accurately quantify the observed experimental phenomena and to compensate for the effect of known uncertainties. They provide a basis for the efficient development of new models for phenomena that are currently not modeled (such as material interactions). They can provide validated phenomenological models (from the results of the experiments) as candidates for incorporation in the systems-level whole-core'' codes.

Ott, L.J.; van Rij, W.I.

1991-01-01

109

Atmospheric transport and diffusion mechanisms in coastal circulation systems  

Microsoft Academic Search

This study defines the cyclical aspects of coastal atmospheric behavior that are important to the transport and diffusion (dispersion) of radionuclides. The report is developed around discussions of the meteorological dynamics of the cyclical and (cellular) atmospheric coastal phenomena and the atmospheric transport\\/diffusion mechanisms along with an assessment of the measurements accompanying both. Further, the efforts directed to modeling both

R. J. Kaleel; D. L. Shearer; B. L. MacRae

1983-01-01

110

Turbulence structure in microburst phenomena  

NASA Technical Reports Server (NTRS)

The efect on turbulence of a variable mean wind along the flight path of an aircraft is modeled and analyzed. It is found that the effect of a variable head or tail wind alters the magnitude of the length-scale of sensed microburst turbulence, rendering turbulence more random than usually encountered in the upper atmosphere. This, coupled with accompanying aerodynamic lift loss experienced during the headwind-to-tailwind swing, is what collectively creates the hazardous environment for a microburst-encountering aircraft attempting to land during a thunderstorm.

Trevino, George

1987-01-01

111

Ordering Phenomena in Undercooled Alloys  

SciTech Connect

Much of the work performed under this grant was devoted to using modern ideas in kinetics to understand atom movements in metallic alloys far from thermodynamic equilibrium. Kinetics arguments were based explicitly on the vacancy mechanism for atom movements. The emphasis was on how individual atom movements are influenced by the local chemical environment of the moving atom, and how atom movements cause changes in the local chemical environments. The author formulated a kinetic master equation method to treat atom movements on a crystal lattice with a vacancy mechanism. Some of these analyses [3,10,16] are as detailed as any treatment of the statistical kinetics of atom movements in crystalline alloys. Three results came from this work. Chronologically they were (1) A recognition that tracking time dependencies is not necessarily the best way to study kinetic phenomena. If multiple order parameters can be measured in a material, the ''kinetic path'' through the space spanned by these order parameters maybe just as informative about the chemical factors that affect atom movements [2,3,5-7,9-11,14-16,18,19,21,23,24,26,36,37]. (2) Kinetic paths need not follow the steepest gradient of the free energy function (this should be well-known), and for alloys far from equilibrium the free energy function can be almost useless in describing kinetic behavior. This is why the third result surprised me. (3) In cluster approximations with multiple order parameters, saddle points are common features of free energy functions. Interestingly, kinetic processes stall or change time scale when the kinetic path approaches a state at a saddle point in the free energy function, even though these states exist far from thermodynamic equilibrium. The author calls such a state a ''pseudostable'' (falsely stable) state [6,21,26]. I have also studied these phenomena by more ''exact'' Monte Carlo simulations. The kinetic paths showed features similar to those found in analytical theories. The author found that a microstructure with interfaces arranged in space as a periodic minimal surface is a probably an alloy at a saddle point in its free energy function [21,26,37].

Fultz, Brent

1997-07-17

112

Data acquisition and simulation of natural phenomena  

Microsoft Academic Search

Virtual natural phenomena obtained through mathematical-physical modeling and simulation as well as graphics emulation can\\u000a meet the user’s requirements for sensory experiences to a certain extent but they can hardly have the same accurate physical\\u000a consistency as real natural phenomena. The technology for data acquisition and natural phenomena simulation can enable us\\u000a to obtain multi-dimensional and multi-modal data directly from

QinPing Zhao

2011-01-01

113

Unsteady flow phenomena in industrial centrifugal compressor stage  

NASA Technical Reports Server (NTRS)

The results of an experimental investigation on a typical centrifugal compressor stage running on an atmospheric pressure test rig are shown. Unsteady flow was invariably observed at low flow well before surge. In order to determine the influence of the statoric components, the same impeller was repeatedly tested with the same vaneless diffuser, but varying return channel geometry. Experimental results show the strong effect exerted by the return channel, both on onset and on the behavior of unsteady flow. Observed phenomena have been found to confirm well the observed dynamic behavior of full load tested machines when gas density is high enough to cause appreciable mechanical vibrations. Therefore, testing of single stages at atmospheric pressure may provide a fairly accurate prediction of this kind of aerodynamic excitation.

Bonciani, L.; Terrinoni, L.; Tesei, A.

1982-01-01

114

Nonepileptic motor phenomena in the neonate  

PubMed Central

The newborn infant is prone to clinical motor phenomena that are not epileptic in nature. These include tremors, jitteriness, various forms of myoclonus and brainstem release phenomena. They are frequently misdiagnosed as seizures, resulting in unnecessary investigations and treatment with anticonvulsants, which have potentially harmful side effects. Unfortunately, there is a paucity of literature about many of these phenomena in the newborn, and some of the major textbooks refer to these events as nonepileptic seizures, leading to further confusion for the practitioner. The present paper aims to review these phenomena with special emphasis on differentiating them from epileptic seizures, and offers information on treatment and prognosis wherever possible.

Huntsman, Richard James; Lowry, Noel John; Sankaran, Koravangattu

2008-01-01

115

Monitoring of Transient Lunar Phenomena  

NASA Astrophysics Data System (ADS)

Transient Lunar Phenomena (TLP’s) are described as short-lived changes in the brightness of areas on the face of the Moon. TLP research is characterized by the inability to substantiate, reproduce, and verify findings. Our current research includes the analysis of lunar images taken with two Santa Barbara Instrument Group (SBIG) ST8-E CCD cameras mounted on two 0.36m Celestron telescopes. On one telescope, we are using a sodium filter, and on the other an H-alpha filter, imaging approximately one-third of the lunar surface. We are focusing on two regions: Hyginus and Ina. Ina is of particular interest because it shows evidence of recent activity (Schultz, P., Staid, M., Pieters, C. Nature, Volume 444, Issue 7116, pp. 184-186, 2006). A total of over 50,000 images have been obtained over approximately 35 nights and visually analyzed to search for changes. As of March, 2014, no evidence of TLPs has been found. We are currently developing a Matlab program to do image analysis to detect TLPs that might not be apparent by visual inspection alone.

Barker, Timothy; Farber, Ryan; Ahrendts, Gary

2014-06-01

116

WESF natural phenomena hazards survey  

SciTech Connect

A team of engineers conducted a systematic natural hazards phenomena (NPH) survey for the 225-B Waste Encapsulation and Storage Facility (WESF). The survey is an assessment of the existing design documentation to serve as the structural design basis for WESF, and the Interim Safety Basis (ISB). The lateral force resisting systems for the 225-B building structures, and the anchorages for the WESF safety related systems were evaluated. The original seismic and other design analyses were technically reviewed. Engineering judgment assessments were made of the probability of NPH survival, including seismic, for the 225-B structures and WESF safety systems. The method for the survey is based on the experience of the investigating engineers,and documented earthquake experience (expected response) data.The survey uses knowledge on NPH performance and engineering experience to determine the WESF strengths for NPH resistance, and uncover possible weak links. The survey, in general, concludes that the 225-B structures and WESF safety systems are designed and constructed commensurate with the current Hanford Site design criteria.

Wagenblast, G.R., Westinghouse Hanford

1996-07-01

117

Review - Axial compressor stall phenomena  

NASA Technical Reports Server (NTRS)

Stall in compressors can be associated with the initiation of several types of fluid dynamic instabilities. These instabilities and the different phenomena, surge and rotating stall, which result from them, are discussed in this paper. Assessment is made of the various methods of predicting the onset of compressor and/or compression system instability, such as empirical correlations, linearized stability analyses, and numerical unsteady flow calculation procedures. Factors which affect the compressor stall point, in particular inlet flow distortion, are reviewed, and the techniques which are used to predict the loss in stall margin due to these factors are described. The influence of rotor casing treatment (grooves) on increasing compressor flow range is examined. Compressor and compression system behavior subsequent to the onset of stall is surveyed, with particular reference to the problem of engine recovery from a stalled condition. The distinction between surge and rotating stall is emphasized because of the very different consequences on recoverability. The structure of the compressor flow field during rotating stall is examined, and the prediction of compressor performance in rotating stall, including stall/unstall hysteresis, is described.

Greitzer, E. M.

1980-01-01

118

Photoinduced phenomena in polysilane films  

NASA Astrophysics Data System (ADS)

The photoinduced phenomena involving the photoscission of (sigma) bonds and photocreation of electronic defects have been studied systematically in films of (MeSiPh)n, (n- Hex2Si)n, (c-HeSiMe)n and (n-pentyl2Si)n as different polysilanes with and without phenyl substituents. The results have revealed the followings. A photoscission model established for (MeSiPh)n, where the photoscission cross-section is larger for longer segments and the reaction is thermally activated with the activation energies being distributed in a shape given by a combination with two exponential functions, is consistent with the processes in other polysilanes. The photoscission of (sigma) bonds creates defects to decrease the photoluminescence for polysilanes with phenyl substituents and some centers to enhance the photoluminescence for (c-HexSiMe)n and (n- pentyl2Si)n. The photoscission of (sigma) bonds occurs preferably at edges of the segments in (c-Hex2Si)n and at the inside of the segments for other three polysilanes. The orientation of (MeSiPh)n is effective to decrease the photoscission cross-section.

Nakayama, Yoshikazu; Inagi, Hiroyuki; Fujii, Tatsuo; Pan, Lujun

2000-11-01

119

Quantum phenomena in semiconductor structures  

NASA Astrophysics Data System (ADS)

The research investigated the electronic properties of small semiconductor devices where transport is dominated or affected by quantum phenomena. Topics investigated included small silicon MOS transistors. Here it is shown that large, intrinsic, stresses affect transport in the two dimensional inversion layer. As the stress is at the edge of the device, it is not significant for larger structures. The electron-phonon interaction in epitaxial layers of GaAs has been investigated using Schottky gate FETs (MESFETs). It is shown that the nature and interpretation of magnetophonon oscillations is strongly affected by the geometry of the sample. Studies of small samples were extended to one dimensional GaAs-AlGaAs heterojunctions where it was shown that varying the width at low temperatures resulted in large random conductance fluctuations. These were fitted to the appropriate theory. Quantum corrections to the conductivity and Hall effect were investigated in a range of III-V semiconductors, and, in a new development, a technique of electrostatic squeezing was developed to investigate quantum interference in a ring of electron gas in a GaAs-AlGaAs heterojunction. A description is given of measurements and analysis of electronic transport in MBE grown InSb.

Pepper, M.

1988-12-01

120

Heavy ion beam induced phenomena in polytetrafluoroethylene  

NASA Astrophysics Data System (ADS)

This paper describes the results on thermal and chemical analysis of polytetrafluoroethylene (PTFE) film stack after high-energy heavy ion beam irradiation under atmospheric fields at room temperature. After high-energy C 6+ ion beam irradiation, the PTFE film stack was separated one by one, and then the various measurements such as differential scanning calorimetric (DSC) analysis and solid-state 19F magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy were performed to get information of the chemical reaction and structural change at the localized positions. By ion beam irradiation for PTFE at room temperature, it is suggested that the abnormal phenomena due to the change of morphology could be observed by DSC analysis. In the solid-state 19F-MAS-NMR spectroscopy of ion irradiated PTFE film including Bragg peak region, several new signals were observed besides the intense peak of -CF 2- at -124 ppm. The detected new signals in ion irradiated PTFE should be due to the changed chemical structures. The signals, which are assigned, to the tertiary carbon group with branching site (Y-type crosslinking site), perfluoro-propylene site and chain end methyl site were directly detected, though it was under the oxidation condition. Thus, although it was under the oxidation condition, the branching or crosslinking reaction was taken place with the chain scission in the matrix. Moreover, the branched chain length would become short, compared with EB-crosslinked PTFE. Hence, it could be suggested that the irradiation of heavy ion beam induced large amounts of intermediate species, compared with EB or ?-ray irradiation, and then, those would be reacted with each other in the localized area. Especially, in region of the Bragg peak, the ion beam induced more large amounts of intermediate species than in the other region.

Oshima, Akihiro; Murata, Katsuyoshi; Oka, Toshitaka; Miyoshi, Nozomi; Matsuura, Akio; Kudo, Hisaaki; Murakami, Takeshi; Katoh, Etsuko; Washio, Masakazu; Hama, Yoshimasa

2007-12-01

121

Convective storms in planetary atmospheres  

NASA Astrophysics Data System (ADS)

The atmospheres of the planets in the Solar System have different physical properties that in some cases can be considered as extreme when compared with our own planet's more familiar atmosphere. From the tenuous and cold atmosphere of Mars to the dense and warm atmosphere of Venus in the case of the terrestrial planets, to the gigantic atmospheres of the outer planets, or the nitrogen and methane atmosphere of Saturn's moon Titan, we can find a large variety of physical environments. The comparative study of these atmospheres provides a better understanding of the physics of a geophysical fluid. In many of these worlds convective storms of different intensity appear. They are analogous to terrestrial atmospheres fed by the release of latent heat when one of the gases in the atmosphere condenses and they are therefore called moist convective storms. In many of these planets they can produce severe meteorological phenomena and by studying them in a comparative way we can aspire to get a further insight in the dynamics of these atmospheres even beyond the scope of moist convection. A classical example is the structure of the complex systems of winds in the giant planets Jupiter and Saturn. These winds are zonal and alternate in latitude but their deep structure is not accessible to direct observation. However the behaviour of large--scale convective storms vertically extending over the "weather layer" allows to study the buried roots of these winds. Another interesting atmosphere with a rather different structure of convection is Titan, a world where methane is close to its triple point in the atmosphere and can condense in bright clouds with large precipitation fluxes that may model part of the orography of the surface making Titan a world with a methane cycle similar to the hydrological cycle of Earth's atmosphere.

Hueso, R.; Sánchez-Lavega, A.

2013-05-01

122

Atmosphere control  

NASA Technical Reports Server (NTRS)

Atmospheric control studies emphasized the carbon dioxide problem. Trace contaminants are removed by solid adsorbents and by catalytic oxidation. Humidity control and storage systems for atmospheric constituents are briefly summarized.

Jones, W. L.; Ingelfinger, A. L.

1973-01-01

123

Complex (dusty) plasmas-kinetic studies of strong coupling phenomena  

SciTech Connect

'Dusty plasmas' can be found almost everywhere-in the interstellar medium, in star and planet formation, in the solar system in the Earth's atmosphere, and in the laboratory. In astrophysical plasmas, the dust component accounts for only about 1% of the mass, nevertheless this component has a profound influence on the thermodynamics, the chemistry, and the dynamics. Important physical processes are charging, sputtering, cooling, light absorption, and radiation pressure, connecting electromagnetic forces to gravity. Surface chemistry is another important aspect. In the laboratory, there is great interest in industrial processes (e.g., etching, vapor deposition) and-at the fundamental level-in the physics of strong coupling phenomena. Here, the dust (or microparticles) are the dominant component of the multi-species plasma. The particles can be observed in real time and space, individually resolved at all relevant length and time scales. This provides an unprecedented means for studying self-organisation processes in many-particle systems, including the onset of cooperative phenomena. Due to the comparatively large mass of the microparticles (10{sup -12}to10{sup -9}g), precision experiments are performed on the ISS. The following topics will be discussed: Phase transitions, phase separation, electrorheology, flow phenomena including the onset of turbulence at the kinetic level.

Morfill, Gregor E.; Ivlev, Alexei V.; Thomas, Hubertus M. [Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany)

2012-05-15

124

The Atmosphere  

NSDL National Science Digital Library

This exercise is intended to reinforce the importance of Earth's atmosphere to living organisms. Topics include our bodies' interactions with the atmosphere; its composition and structure; and natural changes in the atmosphere (weather). Students will perform an actvity in which they are asked to observe and record weather conditions for four days, answer questions about their observations, and respond to a series of questions on general atmospheric characteristics. They will also learn how to convert temperature values from degrees Celsius to Fahrenheit.

Fox, Chris

125

Stochastic properties of partial-discharge phenomena  

Microsoft Academic Search

The author presents a bibliography and survey of the literature concerned with theory and measurement of the stochastic behavior of pulsating partial-discharge (PD) phenomena that can occur when insulation is subjected to electrical stress. The types of PD phenomena considered include AC and DC generated electron avalanches, pulsating positive and negative corona in gases, and PD that occur in liquid

R. J. Van Brunt

1991-01-01

126

Interactive atmosphere  

NSDL National Science Digital Library

Where is ozone located in the atmosphere? This informational activity, part of an interactive laboratory series for grades 8-12, explores the changes in ozone concentration with altitude. Students are introduced to layers of the atmosphere and the amount of ozone found at each layer of the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The activity also discusses why the addition of ozone to the atmosphere at different levels determines the temperatures of those levels. Students can move up and down to different layers of the atmosphere. A temperature scale is shown that runs from the surface of the Earth to the outer most reaches of the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

127

NASA/MSFC FY-81 Atmospheric Processes Research Review  

NASA Technical Reports Server (NTRS)

Progress in ongoing research programs and future plans for satellite investigations into global weather, upper atmospheric phenomena, and severe storms and local weather are summarized. Principle investigators and publications since June 1980 are listed.

Turner, R. E. (compiler)

1981-01-01

128

Atmospheric gases  

NSDL National Science Digital Library

Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

129

Nanoflares, Spicules, and Other Small-Scale Dynamic Phenomena on the Sun  

NASA Technical Reports Server (NTRS)

There is abundant evidence of highly dynamic phenomena occurring on very small scales in the solar atmosphere. For example, the observed pr operties of many coronal loops can only be explained if the loops are bundles of unresolved strands that are heated impulsively by nanoflares. Type II spicules recently discovered by Hinode are an example of small-scale impulsive events occurring in the chromosphere. The exist ence of these and other small-scale phenomena is not surprising given the highly structured nature of the magnetic field that is revealed by photospheric observations. Dynamic phenomena also occur on much lar ger scales, including coronal jets, flares, and CMEs. It is tempting to suggest that these different phenomena are all closely related and represent a continuous distribution of sizes and energies. However, this is a dangerous over simplification in my opinion. While it is tru e that the phenomena all involve "magnetic reconnection" (the changin g of field line connectivity) in some form, how this occurs depends s trongly on the magnetic geometry. A nanoflare resulting from the interaction of tangled magnetic strands within a confined coronal loop is much different from a major flare occurring at the current sheet form ed when a CME rips open an active region. I will review the evidence for ubiquitous small-scale dynamic phenomena on the Sun and discuss wh y different phenomena are not all fundamentally the same.

Klimchuk, James

2010-01-01

130

Infrared experiments for spaceborne planetary atmospheres research. Full report  

NASA Technical Reports Server (NTRS)

The role of infrared sensing in atmospheric science is discussed and existing infrared measurement techniques are reviewed. Proposed techniques for measuring planetary atmospheres are criticized and recommended instrument developments for spaceborne investigations are summarized for the following phenomena: global and local radiative budget; radiative flux profiles; winds; temperature; pressure; transient and marginal atmospheres; planetary rotation and global atmospheric activity; abundances of stable constituents; vertical, lateral, and temporal distribution of abundances; composition of clouds and aerosols; radiative properties of clouds and aerosols; cloud microstructure; cloud macrostructure; and non-LTE phenomena.

1981-01-01

131

Project Atmosphere Canada: Teacher's Guide  

NSDL National Science Digital Library

This teacher's guide from Project Atmosphere Canada is designed to promote an interest in meteorology among young people, and to encourage and foster the teaching of the atmospheric sciences and related topics in Canada. Topics include weather hazards such as hurricanes and thunderstorms; the use of radar and satellites in weather prediction; weather phenomena such as El Nino, wind patterns, high and low pressure, and clouds; sunlight, water vapor, and the upper atmopshere; and others. Each module features introductory material, concepts for basic understanding, and activities. This resource is also available in French.

132

A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms  

NASA Technical Reports Server (NTRS)

Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

Simoes, Fernando; Pfaff, Robert; Berthelier, Jean-Jacques; Klenzing, Jeffrey

2012-01-01

133

Mathematics needed for Introduction to Transport Phenomena  

NSDL National Science Digital Library

A collection of math problems based on skills needed to successfully complete homework problems in an introductory course in Transport Phenomena. These problems do not introduce any new material for those who have taken Freshman Calculus classes and a sophomore level Differential Equations class. At Purdue University in the required Transport Phenomena course for MSE undergrads (MSE 340), I give a problem set like this the first day of classes in order to make clear the level of mathematical skill needed for the rest of the semester. I have found that it reduces difficulties with math later in the semester, allowing the students to focus on the transport phenomena.

Krane, Matthew J.

2007-10-12

134

Atmospheric superrotation?  

Microsoft Academic Search

Beginning in 1958 analysis of the atmospheric drag on artificial earth satellites has provided many measurements of the rotation of the earth's thermosphere.11Atmospheric rotation is represented by the ratio: ?=(mean inertial rotation of the atmosphere)\\/(mean earth rotation). Superrotation occurs when ?>1.0. It was reported that there was a net west-to-east wind ranging from 50ms?1 to more than 200ms?1: the so-called

E. M Gaposchkin

2003-01-01

135

Satellite Atmosphere and Io Torus Observations  

NASA Technical Reports Server (NTRS)

Io is the most volcanically active body in the solar system, and it is embedded deep within the strongest magnetosphere of any planet. This combination of circumstances leads to a host of scientifically compelling phenomena, including (1) an atmosphere out of proportion with such a small object, (2) a correspondingly large atmospheric escape rate, (3) a ring of dense plasma locked in a feedback loop with the atmosphere, and (4) a host of Io-induced emissions from radio bursts to UV auroral spots on Jupiter. This proposal seeks to continue our investigation into the physics connecting these phenomena, with emphasis on Io's atmosphere and plasma torus. The physical processes are clearly of interest for Io, and also other places in the solar system where they are important but not readily observable.

Schneider, Nicholas M.

2000-01-01

136

Pluto's atmosphere  

SciTech Connect

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references.

Elliot, J.L.; Dunham, E.W.; Bosh, A.S.; Slivan, S.M.; Young, L.A.

1989-01-01

137

Pluto's atmosphere  

NASA Technical Reports Server (NTRS)

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data.

Elliot, J. L.; Dunham, E. W.; Bosh, A. S.; Slivan, S. M.; Young, L. A.

1989-01-01

138

Electrical Phenomena in Biological Membranes: A Symposium.  

National Technical Information Service (NTIS)

Contents: Biological Systems - General Properties of Biological Membranes, Red Blood Cells, Oscillatory Phenomena in Plant Cells, Chemotaxis, Nerve, Post-Synaptic Membrane, Visual Transduction and Energy Conversion by Rhodopsins; Non-Viable Systems - Mono...

J. B. Bateman

1977-01-01

139

Microbiologically Influenced Corrosion: Global Phenomena, Local Mechanisms.  

National Technical Information Service (NTIS)

Much of the on-going research in microbiologically influenced corrosion (MIC) is directed al identification of unifying mechanisms for global observations of MIC-related phenomena, e.g. ennoblement of passive alloys and corrosion of carbon steel pilings. ...

B. Little J. Lee R. Ray

2011-01-01

140

Transient Phenomena in Asynchronous Motor Drive.  

National Technical Information Service (NTIS)

Transient torques of a motor drive cause torsional stresses in the shaft. Motor is constructed to withstand these torques. In construction of couplings, shaft and drive these torques have to be taken into consideration, too. Transient phenomena are simula...

R. Hirvonen

1989-01-01

141

Bibliography on Electrostatic Phenomena in Aerosol Dissemination.  

National Technical Information Service (NTIS)

The bibliography represents a survey of published information relevant to the manner in which electrostatic phenomena might influence dissemination of chemical warfare agents, covering both the open literature and reports of government-sponsored research....

D. E. Blake C. E. Lapple

1965-01-01

142

Mysterious Phenomena of the Human Psyche.  

National Technical Information Service (NTIS)

Contents: Mysterious psychic phenomena as a source of superstition; Sleep and dreams; Hypnosis and suggestion; Suggestion and autosuggestion in the waking state; Automatic movement; Is there a 'mental radio'; What can be said about 'extrasensory perceptio...

L. L. Vasilev

1967-01-01

143

Canister storage building natural phenomena design loads  

SciTech Connect

This document presents natural phenomena hazard (NPH) loads for use in the design and construction of the Canister Storage Building (CSB), which will be located in the 200 East Area of the Hanford Site.

Tallman, A.M.

1996-02-01

144

Spinal vacuum phenomena: anatomical study and review.  

PubMed

"Vacuum" phenomena relate to the accumulation of gas, principally nitrogen, in crevices within the intervertebral disk or vertebra. Their appearance does not uniformly indicate "degenerative" disk disease (primary intervertebral osteochondrosis), as gaseous collections may accompany other processes (vertebral osteomyelitis, Schmorl node formation, spondylosis deformans, vertebral collapse with osteonecrosis) affecting the disk and adjacent vertebral bodies. The location and appearance of the "vacuum" phenomena are helpful indicators as to the precise nature of the spinal disorder. PMID:7220878

Resnick, D; Niwayama, G; Guerra, J; Vint, V; Usselman, J

1981-05-01

145

Second DOE natural phenomena hazards mitigation conference  

SciTech Connect

This conference has been organized into ten presentation sessions which include an overview of the DOE Natural Phenomena Guidelines, Seismic Analysis, Seismic Design, Modifying Existing Facilities, DOE Orders, Codes, and Standards (2 sessions), Seismic Hazard (2 sessions), and Probabilistic Risk Assessment (2 sessions). Two poster sessions were also included in the program to provide a different forum for communication of ideas. Over the past fourteen years, Lawrence Livermore National Laboratory, Nuclear Systems Safety Program, has been working with the US Department of Energy, Office of Safety Appraisals and their predecessors in the area of natural phenomena hazards. During this time we have developed seismic, extreme wind/tornado, and flood hazard models for DOE sites in the United States. Guidelines for designing and evaluating DOE facilities for natural phenomena have been developed and are in interim use throughout the DOE community. A series of state-of-the practice manuals have also been developed to aid the designers. All of this material is listed in the Natural Phenomena Hazards Bibliography included in these proceedings. This conference provides a mechanism to disseminate current information on natural phenomena hazards and their mitigation. It provides an opportunity to bring together members of the DOE community to discuss current projects, to share information, and to hear practicing members of the structural engineering community discuss their experiences from past natural phenomena, future trends, and any changes to building codes. Each paper or poster presented is included in these proceedings. We have also included material related to the luncheon and dinner talks.

Not Available

1989-01-01

146

Solar Neutrons and Related Phenomena  

NASA Astrophysics Data System (ADS)

EAndersNGrevesse1989Abundances of the elements: meteoritic and solarGeochim Cosmochim Acta (UK)5311972141989GeCoA..53..197A10.1016/0016-7037(89)90286-XAnders E, Grevesse N (1989) Abundances of the elements: meteoritic and solar. Geochim Cosmochim Acta (UK) 53(1):197-214 Aschwanden MJ, Wills MJ, Hudson HS, Kosugi T, Schwartz RA (1996) Electron time-of-flight distances and flare loop geometries compared from CGRO and Yohkoh observations. Astrophys J (USA) 468(1, Part 1):398-417 EAslanidesPFassnachtGDellacasaMGallioJWNTuyn198112C(3He, 3He n)11C cross section at 910 MeVPhys Rev C Nucl Phys (USA)234182618281981PhRvC..23.1826A10.1103/PhysRevC.23.1826Aslanides E, Fassnacht P, Dellacasa G, Gallio M, Tuyn JWN (1981) 12C(3He, 3He n)11C cross section at 910 MeV. Phys Rev C Nucl Phys (USA) 23(4):1826-1828 Avrett EH (1981) Reference model atmosphere calculation - the Sunspot sunspot model. In: Cram LE, Thomas JH (eds) The physics of sunspots, Proceedings of the conference, Sunspot, New Mexico, 1981, conference sponsored by the Sacramento Peak Observatory, Sunspot, NM, pp 235-255, 257 Brekke P, Rottman GJ, Fontenla J, Judge PG (1996) The ultraviolet spectrum of a 3B class flare observed with SOLSTICE. Astrophys J (USA) 468(1, Part 1):418-432 ODBrill1965He3-light nucleus interaction cross sectionsSoviet J Nu

Dorman, Lev I.

147

Atmospheric chemistry  

SciTech Connect

This book covers the predictive strength of atmospheric models. The book covers all of the major important atmospheric areas, including large scale models for ozone depletion and global warming, regional scale models for urban smog (ozone and visibility impairment) and acid rain, as well as accompanying models of cloud processes and biofeedbacks.

Sloane, C.S. (General Motors Research Labs., Warren, MI (United States)); Tesche, T.W. (Alpine Geophysics (US))

1991-01-01

148

Pluto's atmosphere  

Microsoft Academic Search

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates

J. L. Elliot; E. W. Dunham; A. S. Bosh; S. M. Slivan; L. A. Young

1989-01-01

149

Atmospheric Electricity  

Microsoft Academic Search

A number of current problems in atmospheric electricity are discussed in turn; these are: ionization equilibrium in the atmosphere; fine weather fields and currents, particularly conditions close to the earth's surface; point discharge; precipitation currents and their origin; the maintenance of the charge on the earth; the electrical structure of thunderclouds; and theories of the origin of charges in clouds.

J Alan Chalmers

1954-01-01

150

Instrumentation for measurement of atmospheric radiation  

NASA Astrophysics Data System (ADS)

Radiation associated with earth's atmospheric phenomena presents a variety of problems that can be investigated with the technique of radiative transfer. A wide range of both active and passive techniques have been developed for in situ and remote sensing of the atmosphere. A significant fraction of electromagnetic spectrum ranging from ultraviolet to low-frequency radio waves is utilized, which means that many important parameters of the neutral and ionized atmosphere can be studied. The ability of many ground-based techniques to provide almost continuous monitoring of the state of the atmosphere, often with excellent time and height resolution, shows their importance in the atmospheric research programs. A variety of instruments have been developed which focus on different principles of optical probing of the upper atmosphere. Some details are given of the grating spectroscopic systems, interference filter photometers, and Fabry-Perot and wide-angle Michelson interferometers. Finally, application of modern imaging technology is briefly described.

Agashe, V. V.

1991-08-01

151

The atmospheres of M dwarfs: Observations  

NASA Technical Reports Server (NTRS)

After presenting global properties of M dwarfs, the principal diagnostic of activity phenomena occurring in their atmosphere from the geometrical, energetic, and temporal points of view is stressed. Observations of sunspots, plages, flares, and activity cycles are presented. The major sources of activity are discussed with particular emphasis on the generation, intensification, and measurements of stellar magnetic fields.

Rodono, Marcello

1987-01-01

152

Thermodynamics and Transport Phenomena in High Temperature Steam Electrolysis Cells  

SciTech Connect

Hydrogen can be produced from water splitting with relatively high efficiency using high temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high temperature process heat. The overall thermal-to-hydrogen efficiency for high temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. An overview of high temperature electrolysis technology will be presented, including basic thermodynamics, experimental methods, heat and mass transfer phenomena, and computational fluid dynamics modeling.

James E. O'Brien

2012-03-01

153

Investigating the students' understanding of surface phenomena  

NASA Astrophysics Data System (ADS)

This study investigated students' understanding of surface phenomena. The main purpose for conducting this research endeavor was to understand how students think about a complex topic about which they have little direct or formal instruction. The motivation for focusing on surface phenomena stemmed from an interest in integrating research and education. Despite the importance of surfaces and interfaces in research laboratories, in technological applications, and in everyday experiences, no previous systematic effort was done on pedagogy related to surface phenomena. The design of this research project was qualitative, exploratory, based on a Piagetian semi-structured clinical piloted interview, focused on obtaining a longitudinal view of the intended sample. The sampling was purposeful and the sample consisted of forty-four undergraduate students at Kansas State University. The student participants were enrolled in physics classes that spanned a wide academic spectrum. The data were analyzed qualitatively. The main themes that emerged from the analysis were: (a) students used analogies when confronted with novel situations, (b) students mixed descriptions and explanations, (c) students used the same explanation for several phenomena, (d) students manifested difficulties transferring the meaning of vocabulary across discipline boundaries, (e) in addition to the introductory chemistry classes, students used everyday experiences and job-related experiences as sources of knowledge, and (f) students' inquisitiveness and eagerness to investigate and discuss novel phenomena seemed to peak about the time students were enrolled in second year physics classes.

Hamed, Kastro Mohamad

1999-11-01

154

Atmospheric Mass  

NSDL National Science Digital Library

This is a lesson about the amount of atmosphere a planet is likely to have. Learners will look for the relationship between atmospheric mass and other characteristics of the planet. When the results are not completely conclusive, the students explore possible causes of discrepancies in the data. They conclude that gravity, mass and diameter all have a role in determining atmospheric mass. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 11 in the Astro-Venture Astronomy Unit. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

155

Theories of dynamical phenomena in sunspots  

NASA Technical Reports Server (NTRS)

Attempts that have been made to understand and explain observed dynamical phenomena in sunspots within the framework of magnetohydrodynamic theory are surveyed. The qualitative aspects of the theory and physical arguments are emphasized, with mathematical details generally avoided. The dynamical phenomena in sunspots are divided into two categories: aperiodic (quasi-steady) and oscillatory. For each phenomenon discussed, the salient observational features that any theory should explain are summarized. The two contending theoretical models that can account for the fine structure of the Evershed motion, namely the convective roll model and the siphon flow model, are described. With regard to oscillatory phenomena, attention is given to overstability and oscillatory convection, umbral oscillations and flashes. penumbral waves, five-minute oscillations in sunspots, and the wave cooling of sunspots.

Thomas, J. H.

1981-01-01

156

Aura phenomena and psychopathology: a pilot investigation.  

PubMed

We investigated a possible relation between aura phenomena and psychopathology in patients with seizure disorders. Twenty-one patients with a variety of seizure types (90% with generalized seizures, 72% with complex partial seizures, CPS) were studied. Aura phenomena were evaluated with the Silberman-Post Psychosensory Phenomena Scale; psychopathology was assessed with the Schedule for Affective Disorders and Schizophrenia-Lifetime Version (SADS-L), the Minnesota Multiple Personality Inventory (MMPI), and the Washington Psychosocial Seizure Inventory (WPSI). Psychosensory symptoms occurring in the absence of frank seizures, but not those occurring with seizures, were related to increased psychopathology (primarily mood and anxiety related) and greater time in psychiatric treatment. Psychosensory symptoms may reflect ongoing neurophysiologic dysfunction related to epilepsy and may therefore be a useful subject for further study. PMID:8082622

Silberman, E K; Sussman, N; Skillings, G; Callanan, M

1994-01-01

157

Atmospheric processes  

SciTech Connect

In this article the role of vapor-particle partitioning in the atmospheric removal of semivolatile organic compounds (SOC) such as pesticides, PCBs, and PAHs is explored. Prediction of atmospheric fluxes of SOCs is limited by the uncertainties inherent in wet and dry deposition of particles, plus uncertainties in air-to-water vapor exchange and vapor-particle partitioning. Despite artifact problems in hi-vol sampling, it is encouraging that the filter-retained fraction agrees within about a factor of 3 with {phi} calculated from Junge's model, and that apparent aerosol-bound percentages correlate with depositional properties. Additional study is needed on methods to distinguish gaseous and particulate SOCs in the atmosphere, on details of the interactions between SOC vapors and atmospheric particulate matter, and on the physical properties of SOCs.

Bidleman, T.F. (Univ. of South Carolina, Columbia (USA))

1988-04-01

158

Atmospheric holes and small comets  

NASA Technical Reports Server (NTRS)

Global images of Earth's UV dayglow as gained with an imaging photometer on board Dynamics Explorer 1 exhibit transient decreases, or atmospheric holes, in the dayglow intensities over areas with diameters about 50 km. Features of these atmospheric holes include (1) preferential motion in the east-to-west direction across the sunlit face of Earth, (2) similar diurnal variations in occurrence rates as those for radar meteors, (3) correlation of the occurrence rates with the nonshower rates as determined with forward scatter radar, and (4) larger angular diameters for these atmospheric holes when the spacecraft approaches Earth during its perigee passes. These atmospheric holes are interpreted in terms of obscuration of the dayglow by water clouds from the disruption and subsequent vaporization of small comets at low altitudes above the atmosphere. Supporting evidence for the existence of these small comets is given by their telescopic sighting at greater altitudes before disruption and the detection of water bursts in Earth's upper atmosphere. The small-comet hypothesis and its relationship to geophysical, lunar, and interplanetary phenomena are discussed.

Frank, L. A.; Sigwarth, J. B.

1993-01-01

159

Atmospheric pollution  

SciTech Connect

Atmospheric pollution (AP), its causes, and measures to prevent or reduce it are examined in reviews and reports presented at a workshop held in Damascus, Syria in August 1985. Topics discussed include AP and planning studies, emission sources, pollutant formation and transformation, AP effects on man and vegetation, AP control, atmospheric dispersion mechanisms and modeling, sampling and analysis techniques, air-quality monitoring, and applications. Diagrams, graphs, and tables of numerical data are provided.

Pickett, E.E.

1987-01-01

160

Atmospheric Dust  

NSDL National Science Digital Library

Millions of tons of dust are lifted from deserts annually, suspended in the atmosphere, and released to fall on the oceans, but scientists are a long way from understanding the impact of atmospheric dust on the climate and weather systems of Earth or on marine organisms. This radio broadcast explains how the nitrogen, phosphorus and iron released from dust boosts the growth of phytoplankton, which also soak up carbon dioxide and release more gases into the atmosphere. Better monitoring and more sophisticated sensors are giving us a more accurate picture of the dust in the atmosphere; the broadcast reports on investigations of dust from ice cores and on computer simulations of the connections between dust and climate. But the unpredictable nature of dust events makes it extremely difficult to determine their impact on the natural systems of Earth. There are discussions with geographers, oceanographers, environmentalists and climate modelers about atmospheric dust, one of the least understood and most contradictory components of the atmosphere. The broadcast is 28 minutes in length.

161

Third DOE natural phenomena hazards mitigation conference  

SciTech Connect

This conference on Natural Phenomena Hazards Mitigation has been organized into 15 presentation, panel, and poster sessions. The sessions included an overview of activities at DOE Headquarters; natural phenomena hazards tasks underway for DOE; two sessions on codes, standards, orders, criteria, and guidelines; two sessions on seismic hazards; equipment qualification; wind; PRA and margin assessments; modifications, retrofit, and restart; underground structures with a panel discussion; seismic analysis; seismic evaluation and design; and a poster session. Individual projects are processed separately for the data bases.

Not Available

1991-01-01

162

Fundamental investigation of duct/ESP phenomena  

SciTech Connect

Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

Brown, C.A. (Radian Corp., Austin, TX (United States)); Durham, M.D. (ADA Technologies, Inc., Englewood, CO (United States)); Sowa, W.A. (California Univ., Irvine, CA (United States). Combustion Lab.); Himes, R.M. (Fossil Energy Research Corp., Laguna Hills, CA (United States)); Mahaffey, W.A. (CHAM of North America, Inc., Huntsville, AL (United States))

1991-10-21

163

Modeling of fundamental phenomena in welds  

SciTech Connect

Recent advances in the mathematical modeling of fundamental phenomena in welds are summarized. State-of-the-art mathematical models, advances in computational techniques, emerging high-performance computers, and experimental validation techniques have provided significant insight into the fundamental factors that control the development of the weldment. The current status and scientific issues in the areas of heat and fluid flow in welds, heat source metal interaction, solidification microstructure, and phase transformations are assessed. Future research areas of major importance for understanding the fundamental phenomena in weld behavior are identified.

Zacharia, T.; Vitek, J.M. [Oak Ridge National Lab., TN (United States); Goldak, J.A. [Carleton Univ., Ottawa, Ontario (Canada); DebRoy, T.A. [Pennsylvania State Univ., University Park, PA (United States); Rappaz, M. [Ecole Polytechnique Federale de Lausanne (Switzerland); Bhadeshia, H.K.D.H. [Cambridge Univ. (United Kingdom)

1993-12-31

164

Observations of microwave ultra-fast absorption phenomena above solar active region.  

NASA Astrophysics Data System (ADS)

While the authors process observational data of the flares 22, two rare phenomena of microwave ultra-fast absorption (MUFA) are found. They occurred at 3.67 GHz and 4.00 GHz in the atmospheric layers above both active regions of NOAA/USAF 4808 and 5060 in the interval 05h50m17s - 05h50m25sUT on May 19, 1987 and 07h38m50s - 07h38m58sUT on June 29, 1988, respectively. These absorption phenomena were observed with Phoenix II Microwave Spectrometer at three frequencies (1.42, 2.84 and 3.67 GHz) and (1.42, 2.84 and 4.00 GHz) at Yunnan Observatory. Spike emissions appeared at both 2.84 GHz and 1.42 GHz. The notable observational characteristics of both absorption phenomena are given. A possible absorption mechanism of MUFA is discussed.

Chen, Xiajuan; Ji, Shuchen

1999-12-01

165

Formation of Charge Layers in the Planetary Atmospheres  

Microsoft Academic Search

This section focuses on the physical phenomena, leading to large-scale space-charge and electric field generation (electric dynamo) in the planetary atmospheres, and ways of their theoretical description. The main attention is paid to charge-layer formation in atmospheres. Under terrestrial conditions, a problem of charge-layer formation in the atmosphere is important from the viewpoint of both thunderstorm and fair weather electricity.

Evgeny A. Mareev

2008-01-01

166

An artificial neural network predictor for tropospheric surface duct phenomena  

NASA Astrophysics Data System (ADS)

In this work, an artificial neural network (ANN) model is developed and used to predict the presence of ducting phenomena for a specific time, taking into account ground values of atmospheric pressure, relative humidity and temperature. A feed forward backpropagation ANN is implemented, which is trained, validated and tested using atmospheric radiosonde data from the Helliniko airport, for the period from 1991 to 2004. The network's quality and generality is assessed using the Area Under the Receiver Operating Characteristics (ROC) Curves (AUC), which resulted to a mean value of about 0.86 to 0.90, depending on the observation time. In order to validate the ANN results and to evaluate any further improvement options of the proposed method, the problem was additionally treated using Least Squares Support Vector Machine (LS-SVM) classifiers, trained and tested with identical data sets for direct performance comparison with the ANN. Furthermore, time series prediction and the effect of surface wind to the presence of tropospheric ducts appearance are discussed. The results show that the ANN model presented here performs efficiently and gives successful tropospheric ducts predictions.

Isaakidis, S. A.; Dimou, I. N.; Xenos, T. D.; Dris, N. A.

2007-09-01

167

Solid-State Physical Phenomena and Effects Part III  

Microsoft Academic Search

This is the third in a series of four articles describing solid-state phenomena. Twelve solid-state phenomena and physical effects are provided. All of the twelve phenomena belong to a group which includes effects related to the dielectric properties of materials and transport phenomena for particles other than electrons or holes.

E. Scheibner

1962-01-01

168

High field phenomena in insulating polymers  

Microsoft Academic Search

Much research on electrical properties of insulating polymers has been done for a long time to improve their insulation performance. However, high field phenomena in actual insulating polymers are not well understood yet because of their complicated solid structures. They are also sensitive to additives, impurities, electrode materials and so on. In this paper, several topics on carrier transport, high-field

T. Mizutani; Chikusa Nagoya

2004-01-01

169

Gods, Heroes and Natural Phenomena Cosmologies  

Microsoft Academic Search

People have always been worried about the natural phenomena that have influenced their lives and the origin of these natural changes. That is why they have always tried to explain the creation of the world probably as a way to control it, protect them from it, or simply to understand it. It is always relevant to humankind to try to

Miguel Angel Alarcón

170

Cavitation phenomena detection by different methods  

Microsoft Academic Search

This report deals with the cavitation phenomena and its detection by different methods in centrifugal pumps of low specific speed. At a certain running point of the pump the cavitation conditions have been investigated using four methods, e.g. noise, vibration, pulsation and energy method linked with visual observation. Simultaneously, the positioning of an accelerometer and a microphone has been examined

V. Kercan; F. Schweiger

1979-01-01

171

Solar Phenomena Associated with "EIT Waves"  

NASA Technical Reports Server (NTRS)

In an effort to understand what an 'EIT wave' is and what its causes are, we have looked for correlations between the initiation of EIT waves and the occurrence of other solar phenomena. An EIT wave is a coronal disturbance, typically appearing as a diffuse brightening propagating across the Sun. A catalog of EIT waves, covering the period from 1997 March through 1998 June, was used in this study. For each EIT wave, the catalog gives the heliographic location and a rating for each wave, where the rating is determined by the reliability of the observations. Since EIT waves are transient, coronal phenomena, we have looked for correlations with other transient, coronal phenomena: X-ray flares, coronal mass ejections (CMEs), and metric type II radio bursts. An unambiguous correlation between EIT waves and CMEs has been found. The correlation of EIT waves with flares is significantly weaker, and EIT waves frequently are not accompanied by radio bursts. To search for trends in the data, proxies for each of these transient phenomena are examined. We also use the accumulated data to show the robustness of the catalog and to reveal biases that must be accounted for in this study.

Biesecker, D. A.; Myers, D. C.; Thompson, B. J.; Hammer, D. M.; Vourlidas, A.

2002-01-01

172

MIXING PHENOMENA IN INDUSTRIAL FUME AFTERBURNER SYSTEMS  

EPA Science Inventory

The report reviews the physical-mixing phenomena involved in the reactions that occur in afterburners or fume incinerators. It considers mixing in after-burners from three points of view. It first covers typical designs of afterburner components that are involved in the mixing ph...

173

A System For Explaining Affective Phenomena  

Microsoft Academic Search

Presents a speculative psychophysiological view of affective phenomena. The fundamental hypothesis, formed in accordance with the theory of psychophysical parallelism, is, that affective intensity is proportional to the average rate of change of conductance in the synapses. Increased conductance implies pleasantness, while decreased conductance involves unpleasantness. The activity of nociceptors decreases cortical conductance, whereas the stimulation of beneceptors increases it.

L. T. Troland

1920-01-01

174

Velocity dependencies of some impact phenomena  

Microsoft Academic Search

A variety of cratering phenomena is discussed, primarily with respect to their dependencies on impact velocity. Based on experimental evidence, three impact regimes can be established, an elastic, a plastic, and a hydrodynamic regime. Within the hydrodynamic regime, the cartering process becomes uniform and independent of the impact velocity. It is mainly controlled by projectile and target densities and by

E. Schneider

1979-01-01

175

Transfer phenomena in reacting gas mixtures  

NASA Technical Reports Server (NTRS)

In considering transfer phenomena in reacting gas mixtures, the following topics are discussed: (1) dynamics of paired collisions; (2) Enskog method for solving the Boltzmann equation, taking into account inelastic collisions; (3) use of the variation principle for approximate solutions; (4) computations of inelastic bracketed expressions; (5) calculation of collision integrals; and (6) formulas for transfer coefficients.

Alekseyev, B. V.

1972-01-01

176

Long-Wavelength Phenomena in a Plasma  

Microsoft Academic Search

The long-wavelength modes of excitation of a twocomponent plasma in a ; steady magnetic field are examined. Two linearized Boltzmann equations are given ; with collision terms that are coupled through the difference in temperatures and ; difference in velocities of the two gases. A formal means of classification of ; phenomena is described in terms of the nature of

Richard L. Liboff

1962-01-01

177

Long-Wavelength Phenomena in a Plasma  

Microsoft Academic Search

The long-wavelength modes of excitation of a two-component plasma in a steady magnetic field are examined. Two linearized Boltzmann equations are given with collision terms which are coupled through the difference in temperatures and difference in velocities of the two gases. A formal means of classification of phenomena is described in terms of the nature of the roots about k

Richard L. Liboff

1962-01-01

178

Dream phenomena induced by chronic levodopa therapy  

Microsoft Academic Search

Summary Twenty-seven of eighty-eight (30.7%) Parkinsonian patients on chronic levodopa or levodopa\\/carbidopa therapy developed drug related dream phenomena. The patients reported three separate types of new dreams which we have classified as vivid dreams, night terrors and nightmares. These dreams are correlated to the duration of levodopa therapy although the mechanism of their production is unclear.

B. Sharf; Ch. Moskovitz; M. D. Lupton; H. L. Klawans

1978-01-01

179

Simple Phenomena, Slow Motion, Surprising Physics  

ERIC Educational Resources Information Center

This article describes a few simple experiments that are worthwhile for slow motion recording and analysis either because of interesting phenomena that can be seen only when slowed down significantly or because of the ability to do precise time measurements. The experiments described in this article are quite commonly done in Czech schools. All…

Koupil, Jan; Vicha, Vladimir

2011-01-01

180

Intervention in Biological Phenomena via Feedback Linearization  

PubMed Central

The problems of modeling and intervention of biological phenomena have captured the interest of many researchers in the past few decades. The aim of the therapeutic intervention strategies is to move an undesirable state of a diseased network towards a more desirable one. Such an objective can be achieved by the application of drugs to act on some genes/metabolites that experience the undesirable behavior. For the purpose of design and analysis of intervention strategies, mathematical models that can capture the complex dynamics of the biological systems are needed. S-systems, which offer a good compromise between accuracy and mathematical flexibility, are a promising framework for modeling the dynamical behavior of biological phenomena. Due to the complex nonlinear dynamics of the biological phenomena represented by S-systems, nonlinear intervention schemes are needed to cope with the complexity of the nonlinear S-system models. Here, we present an intervention technique based on feedback linearization for biological phenomena modeled by S-systems. This technique is based on perfect knowledge of the S-system model. The proposed intervention technique is applied to the glycolytic-glycogenolytic pathway, and simulation results presented demonstrate the effectiveness of the proposed technique.

Fnaiech, Mohamed Amine; Nounou, Hazem; Nounou, Mohamed; Datta, Aniruddha

2012-01-01

181

Exploratorium Exhibit and Phenomena Cross Reference  

NSDL National Science Digital Library

This alphabetical list of links explains a variety of scientific phenomena. Clicking on the name of a particular phenomenon will provide the user with a written definition or description and a list of links to exhibits (another part of the site) which illustrate it.

182

Oscillation phenomena of pseudo-shock waves  

Microsoft Academic Search

The oscillation phenomena of pseudo-shocks in a straight pipe were experimentally investigated, and the causes and the frequencies of oscillations are discussed. It was found that the oscillation of the pseudo-shock became stronger with the increasing Mach number and the maximum wall static pressure fluctuation induced by the oscillation amounted to about 60% of the difference of static pressures before

T. Ikui; K. Matsuo; M. Nagai; M. Honjo

1974-01-01

183

Animal models of speech perception phenomena  

Microsoft Academic Search

Science, by tradition and foundational philosophy, is conservative. General theories that are broad in app lication and austere in constructs and variables are preferred to proliferation of specific explanations for individual phenomena. When general, simple accounts no longer suffice as explanations of the available data, novel constructs and theories become necessary. Fifty years ago, speech perception was considered to be

Andrew J. Lotto; Keith R. Kluender; Lori L. Holt

184

Physics of Liquefaction Phenomena around Marine Structures  

Microsoft Academic Search

Understanding of the physical backgrounds is essential for good engineering practice with respect to liquefaction of sandy soils around and beneath marine structures. Several types of liquefaction can be distinguished. The corresponding physical phenomena are briefly described. Among them are: compressibility of soil skeleton, dilation, contraction, elastic versus plastic deformation, interaction between pore water and soil skeleton, compressibility of pore

M. B. de Groot; M. D. Bolton; P. Foray; P. Meijers; A. C. Palmer; R. Sandven; A. Sawicki; T. C. Teh

2006-01-01

185

Partial-Discharge Phenomena and the Effect of Their Constituents on Polyethylene  

Microsoft Academic Search

A method of investigating partial-discharge phenomena andtheir effect on polyethylene is described. A physical study was carriedout with air at atmospheric pressure and gaps between 2 and 14 mm.It is shown, that with this range of gaps and with dielectric walls, astreamer process appears as in the case of a positive point and a metallicplane.The evolution of the polyethylene samples

Christian Mayoux

1976-01-01

186

Seasonal Variability of Saturn's Atmosphere  

NASA Technical Reports Server (NTRS)

The seasonal variability of Saturn's clouds and weather layer, currently displaying a variety of phenomena (convective storms, planetary waves, giant storms and lightning-induced events, etc.) is not yet fully understood. Variations of Saturn's radiance at 5.2 microns, a spectral region dominated by thermal emission in an atmospheric window containing weak gaseous absorption, contain a strong axisymmetric component as well as large discrete features at low and mid-latitudes that are several degrees colder than the planetary average and uncorrelated with features at shorter wavelengths that are dominated by reflected sunlight (Yanamandra-Fisher et al., 2001. Icarus, Vol. 150). The characterization of several fundamental atmospheric properties and processes, however, remains incomplete, namely: How do seasons affect (a) the global distribution of gaseous constituents and aerosols; and (b) temperatures and the stability against convection and large scale-atmospheric transport? Do 5-micron clouds have counterparts at other altitude levels? What changes occur during the emergence of Great White Storms? Data acquired at the NASA/IRTF and NAOJ/Subaru from 1995 - 2011; since 2004, high-resolution multi-spectral and high-spatial imaging data acquired by the NASA/ESA Cassini mission, represents half a Saturnian year or two seasons. With the addition of detailed multi-spectral data sets acquired by amateur observers, we study these dramatic phenomena to better understand the timeline of the evolution of these events. Seasonal (or temporal) trends in the observables such as albedo of the clouds, thermal fields of the atmosphere as function of altitude, development of clouds, hazes and global abundances of various hydrocarbons in the atmosphere can now be modeled. We will present results of our ongoing investigation for the search and characterization of periodicities over half a Saturnian year, based on a non-biased a priori approach and time series techniques (such as Principal Component Analysis, PCA and Lomb-Scargle periodograms, LSP).

Yanamandra-Fisher, Padma A.; Simon, Amy; Delcroix, Marc; Orton, Glenn S.; Trinh, Shirley

2012-01-01

187

Atmospheric radiation  

SciTech Connect

Studies of atmospheric radiative processes are summarized for the period 1987-1990. Topics discussed include radiation modeling; clouds and radiation; radiative effects in dynamics and climate; radiation budget and aerosol effects; and gaseous absorption, particulate scattering and surface reflection. It is concluded that the key developments of the period are a defining of the radiative forcing to the climate system by trace gases and clouds, the recognition that cloud microphysics and morphology need to be incorporated not only into radiation models but also climate models, and the isolation of a few important unsolved theoretical problems in atmospheric radiation.

Harshvardhan, M.R. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

188

Usage of Atmospheric Reanalysis Data for Dynamical Diagnoses of the Atmospheric Circulation and Climate Variability  

Microsoft Academic Search

A fixed configuration of a forecast model used for a reanalysis and assimilation of satellite-measured wind and thermal fields throughout the period since the 1980s provide the global atmospheric circulation fields over a quarter of the century. It is particularly beneficial in study of climatic phenomena and monthly or seasonal anomalies in the Tropics and Southern Hemisphere. The following is

Hisashi Nakamura; Y. Kosak; D. Hott; K. Nishii; T. Miyasaka; K. Takaya

189

Auroral Phenomena: Associated with auroras in complex ways are an extraordinary number of other physical phenomena.  

PubMed

The array of auroral phenomena involves all the basic types of physical phenomena: heat, light, sound, electricity and magnetism, atomic physics, and plasma physics. The uncontrollability, the unreproducibility, and the sheer enormity of the phenomena will keep experimentalists and theorists busy but unsatisfied for many years to come. The greatest challenge in this field of research is an adequate experimentally verifiable theory of the local energization of auroral particle fluxes. Once that is achieved, there is every likelihood that the multitude of correlations between auroral phenomena can be understood and appreciated. Until that time, however, such correlations are to be regarded like icebergs-the parts that can be seen are only a small fraction of the whole phenomenon, and it is the large unseen parts that can be dangerous to theorists and experimentalists alike. PMID:17842831

O'brien, B J

1965-04-23

190

A review of impulsive phase phenomena  

NASA Technical Reports Server (NTRS)

A brief review is given of impulsive phase phenomena in support of the models used to compute the energies of the different components of the flares under study. The observational characteristics of the impulsive phase are discussed as well as the evidence for multi-thermal or non-thermal phenomena. The significance of time delays between hard X-rays and microwaves is discussed in terms of electron beams and Alfven waves, two-step acceleration, and secondary bursts at large distances from the primary source. Observations indicating the occurrence of chromospheric evaporation, coronal explosions, and thermal conduction fronts are reviewed briefly, followed by the gamma ray and neutron results. Finally, a preferred flare scenario and energy source are presented involving the interactions in a complex of magnetic loops with the consequent reconnection and electron acceleration.

Dejager, C.

1986-01-01

191

High performance composites: Commonalty of phenomena  

SciTech Connect

This book contains peer-reviewed articles presented at an international symposium, High Performance Composites: Commonalty of Phenomena, held on October 2 through 6, 1994 as a part of Materials Week, under the auspices of Minerals, Materials and Metals Society (TMS) and ASM International at Rosemont, IL., USA. The objective of this symposium was to examine the state of their understanding in process, microstructure, and properties of high performance composites. The idea was to bring together researchers working in these areas with different composites (polymeric, metallic, intermetallic, and ceramic matrix composites). Commonalty of phenomena in different types of composites, such as processing, damage evolution, role of the matrix microstructure, interface, toughening mechanisms, and fracture was the main theme of the symposium. Forty one papers have been processed separately for inclusion on the data base.

Chawla, K.K. [ed.] [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Liaw, P.K. [ed.] [Univ. of Tennessee, Knoxville, TN (United States); Fishman, S.G. [ed.] [Office of Naval Research, Arlington, VA (United States)

1994-12-31

192

How Might You Investigate Scientific Phenomena?  

NSDL National Science Digital Library

This site, part of Exploring Earth Investigation by McDougal Littell and TERC, examines how to investigate scientific phenomena. The investigations "were designed to build students' knowledge of Earth Science conceptsâ¦and to raise student awareness of Earth as a system of interconnected components and processes." Here, visitors will learn about the steps that allow scientists to create valid investigations of phenomena: forming a hypothesis, determining the appropriate method of investigation, collecting and graphing data, and hypothesis testing. Many sections have illustrative images and interactive features which help students understand the topics presented, and the final section ends with questions for students to further explore as well as a link to some NASA datasets. This is an excellent site for any Earth Science classroom as an introductory lecture to the scientific method or as an out-of-class exploration for students.

2008-09-05

193

Perceptual Phenomena in the Agenda Setting Process  

Microsoft Academic Search

The integration of formerly isolated theoretical concepts is probably one of the most challenging tasks in the development of media effects theory. While agenda setting has already been linked to priming and framing via the concept of second level agenda-setting, this article takes a closer look into perceptual phenomena within the agenda-setting process, thus linking micro-level psychological theories with macro-level

Inga Huck; Oliver Quiring; Hans-Bernd Brosius

2009-01-01

194

Bone marrow cytological storage phenomena in lipidoses  

Microsoft Academic Search

The bone marrow cytological storage phenomena in generalized lysosomal lipid storage disorders (Gaucher disease, Niemann-Pick disease, GM1-gangliosidosis, cholesterol ester storage diseases) are reviewed. The value of bone marrow cytology as a pre-screening method in the diagnostic strategy for the different diseases depends on the disease type suspected and the availability of biochemical screening methods. While cytological screening is not necessary

Sargon Ziyeh; Klaus Harzer

1994-01-01

195

Dream phenomena induced by chronic levodopa therapy.  

PubMed

Twenty-seven of eighty-eight (30.7%) Parkinsonian patients on chronic levodopa or levodopa/carbidopa therapy developed drug related dream phenomena. The patients reported three separate types of new dreams which we have classified as vivid dreams, night terrors and nightmares. These dreams are correlated to the duration of levodopa therapy although the mechanism of their production is unclear. PMID:104005

Sharf, B; Moskovitz, C; Lupton, M D; Klawans, H L

1978-01-01

196

Rectification Phenomena Across an Asymmetric Nanofluidic Channel  

NASA Astrophysics Data System (ADS)

We review our recent experimental and theoretical studies of nanofluidic diodes. A continuum theory is developed to show that the literature and our rectification data can be generically classified into two regimes: a low-voltage regime dominated by intra- channel ionic strength (Donnan potential) gradient and a high-voltage regime dominated by external ion depletion. The two regimes drive different anomalous phenomena, like molecular dissociation and microvortex instability, with distinct distinguished limits of dimensionless parameters. Applications to biosensing are discussed.

Chang, Hsueh-Chia

2011-11-01

197

Coherence Related Gain Phenomena in Potassium -  

Microsoft Academic Search

This work focuses on the theoretical and experimental investigations of coherence related gain phenomena in a collisionally assisted, four-level Raman-driven system, where atomic collisions provide incoherent population to the probed excited state. The theory, as originally envisioned by Narducci and coworkers(1) (without collisions), is first introduced and discussed. Modifications to this theory are made to allow for the addition of

Jeffrey A. Kleinfeld

1995-01-01

198

Rheological Properties and Transfer Phenomena of Nanofluids  

Microsoft Academic Search

This study focused on the synthesis of stable nanofluids and investigation of their rhelogical properties and transfer phenomena. Nanofluids of diamond\\/ethylene glycol, alumina\\/transformer oil and silica\\/water were made to use in this study. Rheological properties of diamond nanofluids were determined at constant temperature (25 °C) using a viscometer. For the convective heat transfer experiment, alumina nanofluid passed through the plate

Kang-Min Jung; Sung Hyun Kim

2008-01-01

199

AC Electrokinetic Phenomena Generated by Microelectrode Structures  

PubMed Central

The field of AC electrokinetics is rapidly growing due to its ability to perform dynamic fluid and particle manipulation on the micro- and nano-scale, which is essential for Lab-on-a-Chip applications. AC electrokinetic phenomena use electric fields to generate forces that act on fluids or suspended particles (including those made of dielectric or biological material) and cause them to move in astonishing ways1, 2. Within a single channel, AC electrokinetics can accomplish many essential on-chip operations such as active micro-mixing, particle separation, particle positioning and micro-pattering. A single device may accomplish several of those operations by simply adjusting operating parameters such as frequency or amplitude of the applied voltage. Suitable electric fields can be readily created by micro-electrodes integrated into microchannels. It is clear from the tremendous growth in this field that AC electrokinetics will likely have a profound effect on healthcare diagnostics3-5, environmental monitoring6 and homeland security7. In general, there are three AC Electrokinetic phenomena (AC electroosmosis, dielectrophoresis and AC electrothermal effect) each with unique dependencies on the operating parameters. A change in these operating parameters can cause one phenomena to become dominant over another, thus changing the particle or fluid behavior. It is difficult to predict the behavior of particles and fluids due to the complicated physics that underlie AC electrokinetics. It is the goal of this publication to explain the physics and elucidate particle and fluid behavior. Our analysis also covers how to fabricate the electrode structures that generate them, and how to interpret a wide number of experimental observations using several popular device designs. This video article will help scientists and engineers understand these phenomena and may encourage them to start using AC Electrokinetics in their research.

Hart, Robert; Oh, Jonghyun; Capurro, Jorge; Noh, Hongseok (Moses)

2008-01-01

200

Quasineutral hybrid simulation of macroscopic plasma phenomena  

Microsoft Academic Search

A method for solving the quasineutral hybrid plasma equations in two dimensions is presented, using full ion dynamics and inertialess electrons. The method uses a predictor-corrector field solver and is extended to allow plasma-vacuum interfaces of arbitrary shape. A three-region method for treating the plasma-vacuum interfaces makes possible the simulation of slowly evolving phenomena over time scales much longer than

D HARNED

1982-01-01

201

Fluid dynamics phenomena induced by power ultrasounds  

Microsoft Academic Search

Propagation of power ultrasound (from 20 to 800kHz) through a liquid inside a cylindrical reactor initiates acoustic cavitation and also fluid dynamics phenomena such as free surface deformation, convection, acoustic streaming, etc.Mathematical modelling is performed as a new approach to predict where active bubbles are and how intense cavitation is. A calculation based on fluid dynamics equations is undertaken using

J.-L Laborde; A Hita; J.-P Caltagirone; A Gerard

2000-01-01

202

Breakdown phenomena in high power klystrons  

SciTech Connect

In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The ''practical'' solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented. 9 refs., 5 figs., 3 tabs.

Vlieks, A.E.; Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Hoyt, E.W.; Lebacqz, J.V.; Lee, T.G.

1988-03-01

203

Chemomechanics: chemical kinetics for multiscale phenomena.  

PubMed

The purpose of this critical review is to introduce the reader to an increasingly important class of phenomena: enormous changes in rates of simple chemical reactions within macromolecules as they are stretched by interactions with the environment. In these chemomechanical, or mechanochemical, phenomena the effect of the macromolecular environment can be visualized as a spring (harmonic or anharmonic) bridging and pulling apart a pair of atoms of the macromolecule. Being able to predict how the parameters of this spring affect the kinetics of the reactions occurring between the constrained atoms may create revolutionary opportunities for designing new reactions, molecules and materials that would capture large-scale deformations to drive useful chemistry or, conversely, that would propel autonomous micro- and nanomechanical devices by coupling them to the concerted motion of atoms that convert reactants into products. Although chemists have long studied and exploited coupling between molecular strain and reactivity in small molecules, a quantitative understanding of the relationship between large-scale (>50 nm) strain and localized reactivity presents unique conceptual and experimental challenges. Below we discuss both the phenomenology and the interpretive framework of chemomechanical phenomena (102 references). PMID:21283850

Huang, Zhen; Boulatov, Roman

2011-05-01

204

Physical mechanism of membrane osmotic phenomena  

SciTech Connect

The microscale, physicomechanical cause of osmosis and osmotic pressure in systems involving permeable and semipermeable membranes is not well understood, and no fully satisfactory mechanism has been offered to explain these phenomena. A general theory, albeit limited to dilute systems of inert, noninteracting solute particles, is presented which demonstrates that short-range forces exerted by the membrane on the dispersed solute particles constitute the origin of osmotic phenomena. At equilibrium, the greater total force exerted by the membrane on those solute particles present in the reservoir containing the more concentrated of the two solutions bathing the membrane is balanced by a macroscopically observable pressure difference between the two reservoirs. The latter constitutes the so-called osmotic pressure difference. Under nonequilibrium conditions, the membrane-solute force is transmitted to the solvent, thus driving the convective flow of solvent observed macroscopically as osmosis. While elements of these ideas have been proposed previously in various forms, the general demonstration offered here of the physicomechanical source of osmotic phenomena is novel. Beyond the purely academic interest that exists in establishing a mechanical understanding of osmotic pressure, the analysis lays the foundation underlying a quantitative theory of osmosis in dilute, nonequilibrium systems outlined in a companion paper.

Guell, D.C. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States); Brenner, H. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemical Engineering] [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemical Engineering

1996-09-01

205

Bion and Tustin: the autistic phenomena.  

PubMed

This article examines the implications of the proposal of autistic transformations within the general context of Bion's theory of Transformations. The aim is to confirm the coherence of this proposal of autistic transformations within the overall structure of Bion's theory of Transformations. She examines the relation between emotional links and their negatives, particularly -K. She questions in which of the dimensions of the mind the autistic phenomena are located, the relation between autistic phenomena and beta elements, and where to place them in the Grid. The author tries to form metapsychological support for the incorporation of the autistic area in Bion's theory of Transformations. She argues that, despite the incongruence and imprecision of this incorporation, such autistic phenomena cannot be excluded from the complexus of the human mind and should therefore be accounted for in Bion's transformations. She discusses the idea that the theory of transformations includes the field of the neurosis and psychosis and deals with emotions, whereas the autistic area is dominated by sensations. The author asks how to add the autistic area to Bion's theory. Clinical material of a child for whom the non-psychotic part of the personality predominates and who presents autistic nuclei provides material for the discussion. PMID:23924328

Korbivcher, Celia Fix

2013-08-01

206

Work on Planetary Atmospheres and Planetary Atmosphere Probes  

NASA Technical Reports Server (NTRS)

A summary final report of work accomplished is presented. Work was performed in the following areas: (1) Galileo Probe science analysis, (2) Galileo probe Atmosphere Structure Instrument, (3) Mars Pathfinder Atmosphere Structure/Meteorology instrument, (4) Mars Pathfinder data analysis, (5) Science Definition for future Mars missions, (6) Viking Lander data analysis, (7) winds in Mars atmosphere Venus atmospheric dynamics, (8) Pioneer Venus Probe data analysis, (9) Pioneer Venus anomaly analysis, (10) Discovery Venus Probe Titan probe instrument design, and (11) laboratory studies of Titan probe impact phenomena. The work has resulted in more than 10 articles published in archive journals, 2 encyclopedia articles, and many working papers. This final report is organized around the four planets on which there was activity, Jupiter, Mars, Venus, and Titan, with a closing section on Miscellaneous Activities. A major objective was to complete the fabrication, test, and evaluation of the atmosphere structure experiment on the Galileo probe, and to receive, analyze and interpret data received from the spacecraft. The instrument was launched on April 14, 1989. Calibration data were taken for all experiment sensors. The data were analyzed, fitted with algorithms, and summarized in a calibration report for use in analyzing and interpreting data returned from Jupiter's atmosphere. The sensors included were the primary science pressure, temperature and acceleration sensors, and the supporting engineering temperature sensors. Computer programs were written to decode the Experiment Data Record and convert the digital numbers to physical quantities, i.e., temperatures, pressures, and accelerations. The project office agreed to obtain telemetry of checkout data from the probe. Work to extend programs written for use on the Pioneer Venus project included: (1) massive heat shield ablation leading to important mass loss during entry; and (2) rapid planet rotation, which introduced terms of motion not needed on Venus. When the Galileo Probe encountered Jupiter, analysis and interpretation of data commenced. The early contributions of the experiment were to define (1) the basic structure of the deep atmosphere, (2) the stability of the atmosphere, (3) the upper atmospheric profiles of density, pressure, and temperature. The next major task in the Galileo Probe project was to refine, verify and extend the analysis of the data. It was the verified, and corrected data, which indicated a dry abiabatic atmosphere within measurement accuracy. Temperature in the thermosphere was measured at 900 K. Participation in the Mars atmospheric research included: (1) work as a team member of the Mars Atmosphere Working Group, (2) contribution to the Mars Exobiology Instrument workshop, (3) asssistance in planning the Mars global network and (4) assitance in planning the Soviet-French Mars mission in 1994. This included a return to the Viking Lander parachute data to refine and improve the definition of winds between 1.5 and 4 kilometer altitude at the two entry sites. The variability of the structure of Mars atmosphere was addressed, which is known to vary with season, latitude, hemisphere and dust loading of the atmosphere. This led to work on the Pathfinder project. The probe had a deployable meteorology mast that had three temperature sensors, and a wind sensor at the tip of the mast. Work on the Titan atmospheric probe was also accomplished. This included developing an experiment proposal to the European Space Agency (ESA), which was not selected. However, as an advisor in the design and preparation of the selected experiment the researcher interacted with scientist on the Huygens Probe Atmosphere Structure Experiment. The researcher also participated in the planning for the Venus Chemical Probe. The science objectives of the probe were to resolve unanswered questions concerning the minor species chemistry of Venus' atmosphere that control cloud formation, greenhouse effectiveness, and the thermal structure. The researcher also reviewed problems with the

Lester, Peter

1999-01-01

207

Atmospheric Dynamics  

NASA Astrophysics Data System (ADS)

In his book, John Green presents a unique personal insight into the fundamentals of fluid mechanics and atmospheric dynamics. Generations of students have benefited from his lectures, and this book, many years in the making, is the result of his wide teaching and research experience. The theory of fluid flow has developed to such an extent that very complex mathematics and models are currently used to describe it, but many of the fundamental results follow from relatively simple considerations: these classic principles are derived here in a novel, distinctive, and at times even idiosyncratic, way. The book is an introduction to fluid mechanics in the atmosphere for students and researchers that are already familiar with the subject, but who wish to extend their knowledge and philosophy beyond the currently popular development of conventional undergraduate instruction.

Green, John

2004-12-01

208

Atmospheric superrotation?  

Microsoft Academic Search

Beginning in 1958 analysis of the atmospheric drag on artificial earth satellites has provided many measurements of the rotation of the earth's thermosphere.1 It was reported that there was a net west-to-east wind ranging from 50ms-1 to more than 200ms-1: the so-called superrotation. Although a number of analysts have contributed to these measurements, they have not been confirmed by theoretical

E. M. Gaposchkin

2003-01-01

209

Atmosphere Webquest  

NSDL National Science Digital Library

Use the websites and games provided to answer questions, complete diagrams, and learn more about our Earth's atmosphere TOPIC 1 - Weather vs. Climate - Let's start with a game. Open up Online Stopwatch and click on the stopwatch setting. - Use the stopwatch to time yourself as you play through all three levels of The Weather Game. - On your own piece of paper write down how long it took you to pass all ...

Talley, Mr.

2011-09-27

210

Submarine Atmospheres  

Microsoft Academic Search

Atmosphere control in submarines has developed to meet the operational requirements. Until\\u000a the end of WWII submarines were primarily semi-submersibles spending most of their time on the surface\\u000a and submerged for periods of 12 h or less. However, rudimentary control of oxygen and carbon\\u000a dioxide was available in some WWI boats. In the latter years of WWII, the requirement for longer

Waldemar Mazurek

211

Atmospheric control systems  

NASA Technical Reports Server (NTRS)

Viewgraphs on atmospheric control systems are presented. Techniques to maintain atmospheric control parameters are identified. Fuzzy logic control law is mentioned for application to atmospheric control.

Mankamyer, Melanie

1990-01-01

212

Microgravity Transport Phenomena Experiment (MTPE) Overview  

NASA Technical Reports Server (NTRS)

The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry of constant cross sectional area, and to facilitate fluid filling and draining operations in microgravity. The fluid cells may be used singly for bulk solutions, or in a Stokes diaphragm configuration to investigate membrane mediated phenomena. Thermal and electrical driving potentials are applied to the experiment fluids through boundary plates located at the ends of the fluid cells. In the ground based instrument, two constant temperature baths circulate through reservoirs adjacent to the boundary plates, and establish the thermal environment within the fluid cells. The boundary plates also serve as electrodes for measurement and application of electrical potentials. The Fluid Manipulation System associated with the MTA is a computer controlled system that enables storage and transfer of experiment fluids during on orbit operations. The system is used to automatically initiate experiments and manipulate fluids by orchestrating pump and valve operations through scripted sequences. Unique technologies are incorporated in the MTA for measurement of fluid properties. Volumetric Flow Sensors have been developed for precision measurement of total fluid volume contained within the fluid cells over time. This data is most useful for measuring the kinetics of osmosis, where fluid is transported from one fluid cell to another through a semipermeable membrane. The MicroSensor Array has been designed to perform in situ measurement of several important fluid parameters, providing simultaneous measurement of solution composition at multiple locations within the experiment fluids. Micromachined sensors and interface electronics have been developed to measure temperature, electrical conductivity, pH, cation activity, and anion activity. The Profile Refractometer uses a laser optical system to directly image the fluid Index of Refraction profile that exists along the MTA fluid cell axis. A video system acquires images of the RI profile over time, and records the transport kinetics that occur upon application of chemical, thermal, or electrical driving potentials. Image proces

Mason, Larry W.

1999-01-01

213

Studies of Novel Quantum Phenomena in Ruthenates  

SciTech Connect

Strongly correlated oxides have been the subject of intense study in contemporary condensed matter physics, and perovskite ruthenates (Sr,Ca)n+1RunO3n+1 have become a new focus in this field. One of important characteristics of ruthenates is that both lattice and orbital degrees of freedom are active and are strongly coupled to charge and spin degrees of freedom. Such a complex interplay of multiple degrees of freedom causes the properties of ruthenates to exhibit a gigantic response to external stimuli under certain circumstances. Magnetic field, pressure, and chemical composition all have been demonstrated to be effective in inducing electronic/magnetic phase transitions in ruthenates. Therefore, ruthenates are ideal candidates for searching for novel quantum phenomena through controlling external parameters. The objective of this project is to search for novel quantum phenomena in ruthenate materials using high-quality single crystals grown by the floating-zone technique, and investigate the underlying physics. The following summarizes our accomplishments. We have focused on trilayered Sr4Ru3O10 and bilayered (Ca1-xSrx)3Ru2O7. We have succeeded in growing high-quality single crystals of these materials using the floating-zone technique and performed systematic studies on their electronic and magnetic properties through a variety of measurements, including resistivity, Hall coefficient, angle-resolved magnetoresistivity, Hall probe microscopy, and specific heat. We have also studied microscopic magnetic properties for some of these materials using neutron scattering in collaboration with Los Alamos National Laboratory. We have observed a number of unusual exotic quantum phenomena through these studies, such as an orbital selective metamagnetic transition, bulk spin valve effect, and a heavy-mass nearly ferromagnetic state with a surprisingly large Wilson ratio. Our work has also revealed underlying physics of these exotic phenomena. Exotic phenomena of correlated electron has been among central topics of contempary condensed matter physics. Ultrfast phase transitions accompanied by switching of conductivity or magnetization in stronly correlated materials are believed to be promising in developing next generation of transistors. Our work on layered ruthenates has remarkably advanced our understanding of how the exotic phenomena of correlated electrons is governed by the complex interplay between charge, spin, lattice and orbital degrees of freedom. In addition to studies on ruthenates, we have also expanded our research to the emerging field of Fe-based superconductors, focusing on the iron chalcogenide Fe1+y(Te1-xSex) superconductor system. We first studied the superconductivity of this alloy system following the discovery of superconductivity in FeSe using polycrystalline samples. Later, we successfuly grew high-quality single crystals of these materials. Using these single crystals, we have determined the magnetic structure of the parent compound Fe1+yTe, observed spin resonance of superconducting state in optimally doped samples, and established a phase diagram. Our work has produced an important impact in this burgeoning field. The PI presented an invited talk on this topic at APS March meeting in 2010. We have published 19 papers in these two areas (one in Nature materials, five in Physical Review Letters, and nine in Physical Review B) and submitted two (see the list of publications attached below).

Mao, Zhiqiang

2011-04-08

214

Temporal Variations in Jupiter's Atmosphere  

NASA Technical Reports Server (NTRS)

In recent years, Jupiter has undergone many atmospheric changes from storms turning red to global. cloud upheavals, and most recently, a cornet or asteroid impact. Yet, on top of these seemingly random changes events there are also periodic phenomena, analogous to observed Earth and Saturn atmospheric oscillations. We will present 15 years of Hubble data, from 1994 to 2009, to show how the equatorial tropospheric cloud deck and winds have varied over that time, focusing on the F953N, F41 ON and F255W filters. These filters give leverage on wind speeds plus cloud opacity, cloud height and tropospheric haze thickness, and stratospheric haze, respectively. The wind data consistently show a periodic oscillation near 7-8 S latitude. We will discuss the potential for variations with longitude and cloud height, within the calibration limits of those filters. Finally, we will discuss the role that large atmospheric events, such as the impacts in 1994 and 2009, and the global upheaval of 2007, have on temporal studies, This work was supported by a grant from the NASA Planetary Atmospheres Program. HST observational support was provided by NASA through grants from Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract NAS5-26555.

Simon-Miller, Amy A.; Chanover, N. J.; Yanamandra-Fisher, P.; Hammel, H. B.; dePater, I.; Noll, K.; Wong, M.; Clarke, J.; Sanchez-Levega, A.; Orton, G. S.; Gonzaga, S.

2009-01-01

215

Simulating physical phenomena with a quantum computer  

NASA Astrophysics Data System (ADS)

In a keynote speech at MIT in 1981 Richard Feynman raised some provocative questions in connection to the exact simulation of physical systems using a special device named a ``quantum computer'' (QC). At the time it was known that deterministic simulations of quantum phenomena in classical computers required a number of resources that scaled exponentially with the number of degrees of freedom, and also that the probabilistic simulation of certain quantum problems were limited by the so-called sign or phase problem, a problem believed to be of exponential complexity. Such a QC was intended to mimick physical processes exactly the same as Nature. Certainly, remarks coming from such an influential figure generated widespread interest in these ideas, and today after 21 years there are still some open questions. What kind of physical phenomena can be simulated with a QC?, How?, and What are its limitations? Addressing and attempting to answer these questions is what this talk is about. Definitively, the goal of physics simulation using controllable quantum systems (``physics imitation'') is to exploit quantum laws to advantage, and thus accomplish efficient imitation. Fundamental is the connection between a quantum computational model and a physical system by transformations of operator algebras. This concept is a necessary one because in Quantum Mechanics each physical system is naturally associated with a language of operators and thus can be considered as a possible model of quantum computation. The remarkable result is that an arbitrary physical system is naturally simulatable by another physical system (or QC) whenever a ``dictionary'' between the two operator algebras exists. I will explain these concepts and address some of Feynman's concerns regarding the simulation of fermionic systems. Finally, I will illustrate the main ideas by imitating simple physical phenomena borrowed from condensed matter physics using quantum algorithms, and present experimental quantum simulations performed in a liquid NMR QC.

Ortiz, Gerardo

2003-03-01

216

Fast Particle Methods for Multiscale Phenomena Simulations  

NASA Technical Reports Server (NTRS)

We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

2000-01-01

217

Oscillating heat pipe simulation considering dryout phenomena  

NASA Astrophysics Data System (ADS)

In heat transport devices such as oscillating heat pipe (OHP), dryout phenomena is very important and avoided in order to give the optimum performance. However, from the previous studies (including our studies), the dryout phenomena in OHP and its mechanism are still unclear. In our studies of OHP (Senjaya and Inoue in Appl Thermal Eng 60:251-255, 2013; Int J Heat Mass Transfer 60:816-824, 2013; Int J Heat Mass Transfer 60:825-835, 2013), we introduced the importance and roles of liquid film in the operating principle of OHP. In our previous simulation, the thickness of liquid film was assumed to be uniform along a vapor plug. Then, dryout never occurred because there was the liquid transfer from the liquid film in the cooling section to that in the heating section. In this research, the liquid film is not treated uniformly but it is meshed similarly with the vapor plugs and liquid slugs. All governing equations are also solved in each control volume of liquid film. The simulation results show that dryout occurs in the simulation without bubble generation and growth. Dryout is started in the middle of vapor plug, because the liquid supply from the left and right liquid slugs cannot reach until the liquid film in the middle of vapor plug, and propagates to the left and right sides of a vapor plug. By inserting the bubble generation and growth phenomena, dryout does not occur because the wall of heating section is always wetted during the bubble growth and the thickness of liquid film is almost constant. The effects of meshing size of liquid film and wall temperature of heating section are also investigated. The results show that the smaller meshing size, the smaller liquid transfer rate and the faster of dryout propagation. In the OHP with higher wall temperature of heating section, dryout and its propagation also occur faster.

Senjaya, Raffles; Inoue, Takayoshi

2014-04-01

218

BWR core melt progression phenomena: Experimental analyses  

SciTech Connect

In the BWR Core Melt in Progression Phenomena Program, experimental results concerning severe fuel damage and core melt progression in BWR core geometry are used to evaluate existing models of the governing phenomena. These include control blade eutectic liquefaction and the subsequent relocation and attack on the channel box structure; oxidation heating and hydrogen generation; Zircaloy melting and relocation; and the continuing oxidation of zirconium with metallic blockage formation. Integral data have been obtained from the BWR DF-4 experiment in the ACRR and from BWR tests in the German CORA exreactor fuel-damage test facility. Additional integral data will be obtained from new CORA BWR test, the full-length FLHT-6 BWR test in the NRU test reactor, and the new program of exreactor experiments at Sandia National Laboratories (SNL) on metallic melt relocation and blockage formation. an essential part of this activity is interpretation and use of the results of the BWR tests. The Oak Ridge National Laboratory (ORNL) has developed experiment-specific models for analysis of the BWR experiments; to date, these models have permitted far more precise analyses of the conditions in these experiments than has previously been available. These analyses have provided a basis for more accurate interpretation of the phenomena that the experiments are intended to investigate. The results of posttest analyses of BWR experiments are discussed and significant findings from these analyses are explained. The ORNL control blade/canister models with materials interaction, relocation and blockage models are currently being implemented in SCDAP/RELAP5 as an optional structural component.

Ott, L.J.

1992-01-01

219

BWR core melt progression phenomena: Experimental analyses  

SciTech Connect

In the BWR Core Melt in Progression Phenomena Program, experimental results concerning severe fuel damage and core melt progression in BWR core geometry are used to evaluate existing models of the governing phenomena. These include control blade eutectic liquefaction and the subsequent relocation and attack on the channel box structure; oxidation heating and hydrogen generation; Zircaloy melting and relocation; and the continuing oxidation of zirconium with metallic blockage formation. Integral data have been obtained from the BWR DF-4 experiment in the ACRR and from BWR tests in the German CORA exreactor fuel-damage test facility. Additional integral data will be obtained from new CORA BWR test, the full-length FLHT-6 BWR test in the NRU test reactor, and the new program of exreactor experiments at Sandia National Laboratories (SNL) on metallic melt relocation and blockage formation. an essential part of this activity is interpretation and use of the results of the BWR tests. The Oak Ridge National Laboratory (ORNL) has developed experiment-specific models for analysis of the BWR experiments; to date, these models have permitted far more precise analyses of the conditions in these experiments than has previously been available. These analyses have provided a basis for more accurate interpretation of the phenomena that the experiments are intended to investigate. The results of posttest analyses of BWR experiments are discussed and significant findings from these analyses are explained. The ORNL control blade/canister models with materials interaction, relocation and blockage models are currently being implemented in SCDAP/RELAP5 as an optional structural component.

Ott, L.J.

1992-06-01

220

General unifying features of controlled quantum phenomena  

SciTech Connect

Many proposals have been put forth for controlling quantum phenomena, including open-loop, adaptive feedback, and real-time feedback control. Each of these approaches has been viewed as operationally, and even physically, distinct from the others. This work shows that all such scenarios inherently share the same fundamental control features residing in the topology of the landscape relating the target physical observable to the applied controls. This unified foundation may provide a basis for development of hybrid control schemes that would combine the advantages of the existing approaches to achieve the best overall performance.

Pechen, Alexander; Brif, Constantin; Wu, Rebing; Chakrabarti, Raj; Rabitz, Herschel [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)

2010-09-15

221

Prehistoric Phenomena and Self-referentiality  

NASA Astrophysics Data System (ADS)

By terms-allowed-in-types capacity, the Logic of Proofs LP enjoys a system of advanced combinatory terms, while including types of the form t:?(t), which have self-referential meanings. This paper suggests a research on possible S4 measures of self-referentiality introduced by this capacity. Specifically, we define "prehistoric phenomena" in G3s, a Gentzen-style formulation of modal logic S4. A special phenomenon, namely, "left prehistoric loop", is then shown to be necessary for self-referentiality in realizations of S4 theorems in LP.

Yu, Junhua

222

Polarization Phenomena in Inclusive Nucleon Transfer Reactions  

NASA Astrophysics Data System (ADS)

The theory of the polarization phenomena in the inclusive one- and two-nucleon transfer reactions (d,n) and (3H,n) at intermediate energies is developed on the basis of the S-matrix approach. Since the parameters of the S-matrix are found from fitting the experimental data for the elastic scattering of protons by the nuclei, the calculated polarization observables of the neutrons released in reactions 40Ca(d,n), 208Pb(d,n), 40Ca(3H,n) and 208Pb(3H,n) in the wide energy region do not have any free parameters.

Berezhnoy, Yu. A.; Slipko, V. A.

223

Stress-induced phenomena in metallization  

SciTech Connect

These proceedings represent papers presented at the Second International Workshop on Stress Induced Phenomena in Metallization held on March 29-31, 1993 at the University of Texas at Austin, U.S.A. The papers included in this volume discuss stress-induced void formation and electromigration failures in narrow-line inter-connect metallization. The results presented have a direct relevance to VLSI fabrication technology. The symposium was sponsored by the American Vacuum Society, the Japanese Society of Applied Physics and the University of Texas at Austin. (AIP)

Ho, P.S. (ed.) (University of Texas at Austin (United States)); Li, C.Y. (ed.) (Cornell University (United States)); Totta, P. (ed.) (IBM Microelectronics Division (United States))

1994-01-01

224

Basic diffraction phenomena in time domain.  

PubMed

Using a recently developed technique (SEA TADPOLE) for easily measuring the complete spatiotemporal electric field of light pulses with micrometer spatial and femtosecond temporal resolution, we directly demonstrate the formation of theo-called boundary diffraction wave and Arago's spot after an aperture, as well as the superluminal propagation of the spot. Our spatiotemporally resolved measurements beautifully confirm the time-domain treatment of diffraction. Also they prove very useful for modern physical optics, especially in micro- and meso-optics, and also significantly aid in the understanding of diffraction phenomena in general. PMID:20588965

Saari, Peeter; Bowlan, Pamela; Valtna-Lukner, Heli; Lõhmus, Madis; Piksarv, Peeter; Trebino, Rick

2010-05-24

225

Multiscale phenomena related to diabetic foot.  

PubMed

Diabetes is a group of metabolic diseases causing a system disorder, i.e.; it cannot be explained or understood by phenomena on single material scale. The diabetic foot is studied as flexible multibody structure by nonlinear finite element method. The physical and geometrical multiscale heterogeneity is solved by multilevel finite element approach. The diabetic tissue is described by internal coordinate's formalism, as complex multiscale process in tissue. The accompanying problem of the axisymetric wound healing is solved numerically. Some results related to foot deformity, stress and strain concentration and wound healing are presented. PMID:21755713

Agi?, Ante; Nikoli?, Tatjana; Mijovi?, Budimir

2011-06-01

226

Quasineutral hybrid simulation of macroscopic plasma phenomena  

SciTech Connect

A method for solving the quasineutral hybrid plasma equations in two dimensions is presented, using full ion dynamics and inertialess electrons. The method uses a predictor-corrector field solver and is extended to allow plasma-vacuum interfaces of arbitrary shape. A three-region method for treating the plasma-vacuum interfaces makes possible the simulation of slowly evolving phenomena over time scales much longer than the ion cyclotron period. The algorithm is applied to the study of rotational instabilities in theta pinch Vlasov equilibria.

Harned, D.S.

1982-09-01

227

Observations of cometary plasma wave phenomena  

NASA Technical Reports Server (NTRS)

The ICE plasma wave investigation utilized very long electric antennas (100 m tip-to-tip) and a very high sensitivity magnetic search coil to obtain significant local information on plasma physics phenomena occurring in the distant pickup regions of Comet Giacobini-Zinner and Comet Halley; and information on the processes that developed in the coma and tail of Giacobini-Zinner. The ICE plasma wave measurements associated with both comet encounters are summarized, and high sensitivity ICE observations are related to corresponding measurements from the other Halley spacecraft.

Scarf, F. L.; Coroniti, F. V.; Kennel, C. F.; Gurnett, D. A.; Ip, W.-H.; Smith, E. J.

1986-01-01

228

Can Observed Seismo-Electromagnetic Phenomena Be Explained By Known Mechano-Electromagnetic Mechanisms?  

NASA Astrophysics Data System (ADS)

Seismo-electromagnetism (SEM), in general, and lithospheric-atmospheric-ionospheric coupling in particular, continue to attract attention as possible earthquake precursors. Do these phenomena in fact exist? Currently there are no models which can explain a variety of electromagnetic observations before and after seismic events ranging from atmospheric light to electromagnetic field to ionosphere disturbances. Most existing models are qualitative, and quantitative estimates are usually superficial. Here we present the results of calculation of electromagnetic signals generated by modeled mechanical disturbances in the earth's crust. The major known SEM phenomena, namely, tectonomagnetic variations, electrotelluric anomalies, geomagnetic variations in the ultra-low frequency range and electromagnetic emission in the radio frequency range, have been considered. We discuss the conditions under which electro-kinetic, piezo-magnetic and piezo-electric effects could be responsible for SEM. A comparison of estimated values of SEMs with reported field measurements leads to the conclusion that, although these mechanisms may explain some of the observations, the sources of most anomalous SEM phenomena should be relatively close to the detector. In other words, the source of the signal is local, although the source of the mechanical disturbance which activates it, e.g. the epicenter of an earthquake, may be far away.

Gershenzon, Naum; Bambakidis, Gust

2014-05-01

229

Solid-State Physical Phenomena and Effects Part IV  

Microsoft Academic Search

This is the fourth in a series of articles dealing with phenomena of the solid state. Nineteen solid-state phenomena and physical effects are described. This group of phenomena includes primarily the resonance effects, that is, those effects which can be described in terms of discrete energy levels rather than energy bands.

E. Scheibner

1962-01-01

230

Physique Moleculair: Physique de l'Atmosphere  

NASA Astrophysics Data System (ADS)

Physique Moleculaire: Physique de l'Atmosphere is a collection of lectures presented at a winter school on the “Application of Molecular Physics to the Atmosphere and to the Environment,” organized from December 1-10, 1983, in Montfoulon (Normandy) under the auspices of various French governmental agencies including the National Center for Scientific Research (CNRS), the Center for Nuclear Studies, and the National Center for Space Studies (CNES). This initiative is part of a policy which developed a few years ago in France and is intended to promote interdisciplinary activities in order to foster interdisciplinary research.Since the early 1970s, several serious questions have been put to the scientific community concerning the possible effects of man's activities on the atmosphere and the likely impact these effects have on the climate. The goal of these lectures was to encourage French scientific communities active in aeronomy, chemical kinetics, meterology, and spectroscopy to work together on those questions of upper atmosphere-climate relationships, since they offer a typical interdisciplinary character. Most of the 12 lectures are in French, except for two that are in English, and can be divided into two groups: introductions of the structure of the atmosphere, the photochemistry and spectroscopy of atmospheric gases, the radiative transfer and the dynamic modeling of transport phenomena, and photochemistry in the atmosphere and more specialized treatments of remote sensing and in situ techniques used to gather data on the atmosphere from the ground as well as from airborne and space platforms in passive and active modes.

Ackerman, Marcel

231

Atmospheric science  

NASA Technical Reports Server (NTRS)

The following types of experiments for a proposed Space Station Microgravity Particle Research Facility are described: (1) growth of liquid water drop populations; (2) coalescence; (3) drop breakup; (4) breakup of freezing drops; (5) ice nucleation for large aerosols or bacteria; (6) scavenging of gases, for example, SO2 oxidation; (7) phoretic forces, i.e., thermophoresis versus diffusiophoresis; (8) Rayleigh bursting of drops; (9) charge separation due to collisions of rimed and unrimed ice; (10) charged drop dynamics; (11) growth of particles in other planetary atmospheres; and (12) freezing and liquid-liquid evaporation. The required capabilities and desired hardware for the facility are detailed.

Hamill, Patrick; Ackerman, Thomas; Clarke, Antony; Goodman, Jindra; Levin, Zev; Tomasko, Martin; Toon, O. Brian; Whitten, Robert

1987-01-01

232

Estimating Atmospheric Turbulence From Flight Records  

NASA Technical Reports Server (NTRS)

Method for estimation of atmospheric turbulence encountered by airplanes utilizes wealth of data captured by multichannel digital flight-data recorders and air-traffic-control radar. Developed as part of continuing effort to understand how airplanes respond to such potentially hazardous phenomena as: clear-air turbulence generated by destabilized wind-shear layers above mountains and thunderstorms, and microbursts (intense downdrafts striking ground), associated with thunderstorms. Reconstructed wind fields used to predict and avoid future hazards.

Wingrove, R. C.; Bach, R. E., Jr.; Schultz, T. A.

1991-01-01

233

Establishment of the New Ecuadorian Solar Physics Phenomena Division  

NASA Astrophysics Data System (ADS)

Crucial physical phenomena occur in the equatorial atmosphere and ionosphere, which are currently understudied and poorly understood. Thus, scientific campaigns for monitoring the equatorial region are required in order to provide the necessary data for the physical models. Ecuador is located in strategic geographical position where these studies can be performed, providing quality data for the scientific community working in understanding the nature of these physical systems. The Quito Astronomical Observatory of National Polytechnic School is moving in this direction by promoting research in space sciences for the study of the equatorial zone. With the participation and the valuable collaboration of international initiatives such us AWESOME, MAGDAS, SAVNET and CALLISTO, the Quito Observatory is establishing a new space physics division on the basis of the International Space Weather Initiative. In this contribution, the above initiative is presented by inviting leaders of other scientific projects to deploy its instruments and to work with us providing the necessary support to the creation of this new strategic research center

Lopez, E. D.

2014-02-01

234

Collective phenomena in volume and surface barrier discharges  

NASA Astrophysics Data System (ADS)

Barrier discharges are increasingly used as a cost-effective configuration to produce non-equilibrium plasmas at atmospheric pressure. This way, copious amounts of electrons, ions, free radicals and excited species can be generated without significant heating of the background gas. In most applications the barrier is made of dielectric material. Major applications utilizing mainly dielectric barriers include ozone generation, surface cleaning and modification, polymer and textile treatment, sterilization, pollution control, CO2 lasers, excimer lamps, plasma display panels (flat TV screens). More recent research efforts are devoted to biomedical applications and to plasma actuators for flow control. Sinusoidal feeding voltages at various frequencies as well as pulsed excitation schemes are used. Volume as well as surface barrier discharges can exist in the form of filamentary, regularly patterned or diffuse, laterally homogeneous discharges. The physical effects leading to collective phenomena in volume and surface barrier discharges are discussed in detail. Special attention is paid to self-organization of current filaments and pattern formation. Major similarities of the two types of barrier discharges are elaborated.

Kogelschatz, U.

2010-11-01

235

Sulfation phenomena in fluidized bed combustion systems  

Microsoft Academic Search

Fluidized bed combustors (FBCs) are noted for their ability to capture SO2 in situ via direct reaction with Ca-based sorbents. However, despite more than 30 years of intensive study of sulfation processes in atmospheric FBC boilers and numerous laboratory studies, there are still many uncertainties and disagreements on the subject. In particular, the mechanisms of the sulfation reaction are still

E. J. Anthony; D. L. Granatstein

2001-01-01

236

Animal network phenomena: insights from triadic games  

NASA Astrophysics Data System (ADS)

Games of animal conflict in networks rely heavily on computer simulation because analysis is difficult, the degree of difficulty increasing sharply with the size of the network. For this reason, virtually the entire analytical literature on evolutionary game theory has assumed either dyadic interaction or a high degree of symmetry, or both. Yet we cannot rely exclusively on computer simulation in the study of any complex system. So the study of triadic interactions has an important role to play, because triads are both the simplest groups in which asymmetric network phenomena can be studied and the groups beyond dyads in which analysis of population games is most likely to be tractable, especially when allowing for intrinsic variation. Here we demonstrate how such analyses can illuminate a variety of behavioral phenomena within networks, including coalition formation, eavesdropping (the strategic observation of contests between neighbors) and victory displays (which are performed by the winners of contests but not by the losers). In particular, we show that eavesdropping acts to lower aggression thresholds compared to games without it, and that victory displays to bystanders will be most intense when there is little difference in payoff between dominating an opponent and not subordinating.

Mesterton-Gibbons, Mike; Sherratt, Tom N.

237

Effects of electrostatic correlations on electrokinetic phenomena.  

PubMed

The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture subtle aspects of molecular simulations and allows for simple calculations of electrokinetic flows in correlated ionic fluids. Charge-density oscillations tend to reduce electro-osmotic flow and streaming current, and overscreening of surface charge can lead to flow reversal. These effects also help to explain the suppression of induced-charge electrokinetic phenomena at high salt concentrations. PMID:23214872

Storey, Brian D; Bazant, Martin Z

2012-11-01

238

Quantum Phenomena Tested By Neutron Interferometry  

SciTech Connect

Entanglement of two photons, or atoms is a complementary situation to a double slit situation of a single photon, neutron or atom. With neutrons single particle interference phenomena can be observed and the 'entanglement of degrees of freedom', i.e. contextuality can be verified. In this respect, neutrons are proper tools for testing quantum mechanics because they are massive, they couple to electromagnetic fields due to their magnetic moment and they are subject to all basic interactions, and they are sensitive to topological effects, as well. Related experiments will be discussed. Deterministic and stochastic partial absorption experiments can be described by Bell-type inequalities. Recent neutron interferometry experiments based on postselection methods renewed the discussion about quantum nonlocality and the quantum measuring process. It has been shown that interference phenomena can be revived even when the overall interference pattern has lost its contrast. This indicates a persisting coupling in phase space even in cases of spatially separated Schroedinger cat-like situations. These states are extremely fragile and sensitive against any kind of fluctuations and other decoherence processes. More complete quantum experiments also show that a complete retrieval of quantum states behind an interaction volume becomes impossible in principle.

Rauch, Helmut [Atominstitut der Oesterreichischen Universitaeten, 1020 Vienna (Austria)

2005-02-15

239

Physical phenomena and the microgravity response  

NASA Technical Reports Server (NTRS)

The living biological cell is not a sack of Newtonian fluid containing systems of chemical reactions at equilibrium. It is a kinetically driven system, not a thermodynamically driven system. While the cell as a whole might be considered isothermal, at the scale of individual macromolecular events there is heat generated, and presumably sharp thermal gradients exist at the submicron level. Basic physical phenomena to be considered when exploring the cell's response to inertial acceleration include particle sedimentation, solutal convection, motility electrokinetics, cytoskeletal work, and hydrostatic pressure. Protein crystal growth experiments, for example, illustrate the profound effects of convection currents on macromolecular assembly. Reaction kinetics in the cell vary all the way from diffusion-limited to life-time limited. Transport processes vary from free diffusion, to facilitated and active transmembrane transport, to contractile-protein-driven motility, to crystalline immobilization. At least four physical states of matter exist in the cell: aqueous, non-aqueous, immiscible-aqueous, and solid. Levels of order vary from crystalline to free solution. The relative volumes of these states profoundly influence the cell's response to inertial acceleration. Such subcellular phenomena as stretch-receptor activation, microtubule re-assembly, synaptic junction formation, chemotactic receptor activation, and statolith sedimentation were studied recently with respect to both their basic mechanisms and their responsiveness to inertial acceleration. From such studies a widespread role of cytoskeletal organization is becoming apparent.

Todd, Paul

1989-01-01

240

EUV Dimmings: Formation Mechanisms and Associated Phenomena  

NASA Astrophysics Data System (ADS)

Large-scale coronal EUV dimmings, developing on timescales of minutes to hours in association with a flare or filament eruption, are known to exhibit a high correlation with coronal mass ejections. While most observations indicate that the decrease in emission in a dimming is due, at least in part, to a density decrease, a complete understanding requires us to examine at least four mechanisms that have been observed to cause darkened regions in the corona: 1) mass loss, 2) cooling, 3) heating, and 4) absorption/obscuration. Recent advances in automatic detection, observations with improved cadence and resolution, multi-viewpoint imaging, and spectroscopic studies have continued to shed light on dimming formation, evolution, and recovery. However, there are still some outstanding questions, including 1) Why do some CMEs show dimming and some do not? 2) What determines the location of a dimming? 3) What determines the temporal evolution of a dimming? 4) How does the post-eruption dimming connect to the ICME? 5) What is the relationship between dimmings and other CME-associated phenomena? The talk will emphasize the different formation mechanisms of dimmings and their relationship to CMEs and CME-associated phenomena.

Thompson, B. J.; Mays, M. L.; West, M. J.

2012-12-01

241

Middle atmospheric science  

NASA Technical Reports Server (NTRS)

Scientific objectives of middle atmosphere research in the 1990's are discussed. Radiative, chemical and dynamical processes in the middle atmosphere; long term evolution of middle atmosphere chemistry; and the interannual variability of middle atmosphere dynamics and transport are among the topics discussed. Observational requirements relative to atmospheric processes, atmospheric chemistry, interannual variability, and the upper mesosphere and lower thermosphere are given.

Gille, J. C.

1984-01-01

242

Understanding protein adsorption phenomena at solid surfaces.  

PubMed

Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to explain the frequently observed phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into mathematical concepts and model descriptions. Relevant experimental and computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined. PMID:21295764

Rabe, Michael; Verdes, Dorinel; Seeger, Stefan

2011-02-17

243

Density-functional theory of thermoelectric phenomena.  

PubMed

We introduce a nonequilibrium density-functional theory of local temperature and associated local energy density that is suited for the study of thermoelectric phenomena. The theory rests on a local temperature field coupled to the energy-density operator. We identify the excess-energy density, in addition to the particle density, as the basic variable, which is reproduced by an effective noninteracting Kohn-Sham system. A novel Kohn-Sham equation emerges featuring a time-dependent and spatially varying mass which represents local temperature variations. The adiabatic contribution to the Kohn-Sham potentials is related to the entropy viewed as a functional of the particle and energy density. Dissipation can be taken into account by employing linear response theory and the thermoelectric transport coefficients of the electron gas. PMID:24877951

Eich, F G; Di Ventra, M; Vignale, G

2014-05-16

244

Hadronic and nuclear phenomena in quantum chromodynamics  

SciTech Connect

Many of the key issues in understanding quantum chromodynamics involves processes at intermediate energies. We discuss a range of hadronic and nuclear phenomena - exclusive processes, color transparency, hidden color degrees of freedom in nuclei, reduced nuclear amplitudes, jet coalescence, formation zone effects, hadron helicity selection rules, spin correlations, higher twist effects, and nuclear diffraction - as tools for probing hadron structure and the propagation of quark and gluon jets in nuclei. Many of these processes can be studied in electroproduction, utilizing internal targets in storage rings. We also review several areas where there has been significant theoretical progress in determining the form of hadron and nuclear wavefunctions, including QCD sum rules, lattice gauge theory, and discretized light-cone quantization. 98 refs., 40 figs., 2 tabs.

Brodsky, S.J.

1987-06-01

245

Analysis of oblique hypervelocity impact phenomena  

NASA Technical Reports Server (NTRS)

This paper describes the results of an experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to a meteoroid or space debris environement.

Schonberg, William P.; Taylor, Roy A.

1988-01-01

246

Critical phenomena in N=2* plasma  

SciTech Connect

We use gauge theory/string theory correspondence to study finite temperature critical behavior of mass-deformed N=4 SU(N) supersymmetric Yang-Mills theory at strong coupling, also known as N=2* gauge theory. For a certain range of the mass parameters, N=2* plasma undergoes a second-order phase transition. We compute all the static critical exponents of the model and demonstrate that the transition is of the mean-field theory type. We show that the dynamical critical exponent of the model is z=0, with multiple hydrodynamic relaxation rates at criticality. We point out that the dynamical critical phenomena in N=2* plasma is outside the dynamical universality classes established by Hohenberg and Halperin.

Buchel, Alex [Department of Applied Mathematics University of Western Ontario London, Ontario N6A 5B7 (Canada); Perimeter Institute for Theoretical Physics Waterloo, Ontario N2J 2W9 (Canada); Pagnutti, Chris [Department of Applied Mathematics University of Western Ontario London, Ontario N6A 5B7 (Canada)

2011-02-15

247

Density-Functional Theory of Thermoelectric Phenomena  

NASA Astrophysics Data System (ADS)

We introduce a nonequilibrium density-functional theory of local temperature and associated local energy density that is suited for the study of thermoelectric phenomena. The theory rests on a local temperature field coupled to the energy-density operator. We identify the excess-energy density, in addition to the particle density, as the basic variable, which is reproduced by an effective noninteracting Kohn-Sham system. A novel Kohn-Sham equation emerges featuring a time-dependent and spatially varying mass which represents local temperature variations. The adiabatic contribution to the Kohn-Sham potentials is related to the entropy viewed as a functional of the particle and energy density. Dissipation can be taken into account by employing linear response theory and the thermoelectric transport coefficients of the electron gas.

Eich, F. G.; Di Ventra, M.; Vignale, G.

2014-05-01

248

Stochastic echo phenomena in nonequilibrium systems  

NASA Astrophysics Data System (ADS)

A thermodynamic system is driven out of equilibrium by a time-dependent force or a nonconservative force represented with a protocol ?( t). The dynamics of such a system is irreversible so that the ensemble of trajectories under a time-reversed protocol ?(- t) is not equivalent to that of timereversed trajectories under ?( t). We raise a question whether one can find a suitable protocol under which the system exhibits time-reversed motions of the original system. Such a phenomenon is referred to as a stochastic echo phenomenon. We derive a condition for the optimal protocol that leads to the stochastic echo phenomenon in Langevin systems. We find that any system driven by timeindependent nonconservative forces has a dual system exhibiting the stochastic echo phenomenon perfectly. The stochastic echo phenomena are also demonstrated for harmonic oscillator systems driven by time-dependent forces. Our study provides a novel perspective on the time-irreversibility of nonequilibrium systems.

Noh, Jae Dong

2014-02-01

249

Equatorial phenomena in neutral thermospheric composition.  

NASA Technical Reports Server (NTRS)

Several interesting phenomena relating to the equatorial ionosphere have been observed in the data from the OGO-6 mass spectrometer. The diurnal variations during equinox at an altitude of 450 km show the N2 and O densities peaking near 1500 hr while He peaks near 1000 hr. The latitudinal variation in N2 during the day is very similar to the F-region electron density exhibiting the well known features of the ionospheric anomaly. During periods of intense geomagnetic disturbance (e.g. the large storm of 8 March 1970), the low latitude thermospheric temperature increases on the order of 50-150 K, while at mid latitudes, increases of more than 1000 K are observed.

Reber, C. A.; Hedin, A. E.; Chandra, S.

1973-01-01

250

Boundary quantum critical phenomena with entanglement renormalization  

SciTech Connect

We propose the use of entanglement renormalization techniques to study boundary critical phenomena on a lattice system. The multiscale entanglement renormalization ansatz (MERA), in its scale invariant version, offers a very compact approximation to quantum critical ground states. Here we show that, by adding a boundary to the MERA, an accurate approximation to the ground state of a semi-infinite critical chain with an open boundary is obtained, from which one can extract boundary scaling operators and their scaling dimensions. As in Wilson's renormalization-group formulation of the Kondo problem, our construction produces, as a side result, an effective chain displaying explicit separation of energy scales. We present benchmark results for the quantum Ising and quantum XX models with free and fixed boundary conditions.

Evenbly, G.; Pfeifer, R. N. C.; Tagliacozzo, L.; McCulloch, I. P.; Vidal, G. [School of Physical Sciences, University of Queensland, Queensland 4072 (Australia); Pico, V.; Iblisdir, S. [Depto. Estructura i Constituents de la Materia, Universitat Barcelona, 08028 Barcelona (Spain)

2010-10-15

251

Physical Simulation: Testing the PHYSICALITY of Phenomena  

NASA Astrophysics Data System (ADS)

Theories of Quantum Mechanics in which `consciousness' plays a role have been around for decades. For example, Wheeler maintains that no phenomenon is a real phenomenon unless it has been observed. Also, the von Neumann chain, where the wave function is said to collapse when the chain reaches the mind of a conscious observer, is well known. The author's theory of Quantum Reality (denoted by TK) goes a bit further, saying that at the fundamental levels, all phenomena are logical-mathematical objects only, and the experience of their `physicality' is due to the consciousness of the observer. This paper addresses the question, as to how TK (and, the other related theories) could be tested. A procedure for this, termed `Physical Simulation' is proposed. The idea is to create logical-mathematical objects through a computer. Various aspects of this methodology are discussed.

Srivastava, Jagdish

2004-05-01

252

Coherence Phenomena in Coupled Optical Resonators  

NASA Technical Reports Server (NTRS)

Quantum coherence effects in atomic media such as electromagnetically-induced transparency and absorption, lasing without inversion, super-radiance and gain-assisted superluminality have become well-known in atomic physics. But these effects are not unique to atoms, nor are they uniquely quantum in nature, but rather are fundamental to systems of coherently coupled oscillators. In this talk I will review a variety of analogous photonic coherence phenomena that can occur in passive and active coupled optical resonators. Specifically, I will examine the evolution of the response that can occur upon the addition of a second resonator, to a single resonator that is side-coupled to a waveguide, as the coupling is increased, and discuss the conditions for slow and fast light propagation, coupled-resonator-induced transparency and absorption, lasing without gain, and gain-assisted superluminal pulse propagation. Finally, I will discuss the application of these systems to laser stabilization and gyroscopy.

Smith, David D.

2007-01-01

253

Liquid state theories and critical phenomena  

NASA Astrophysics Data System (ADS)

The description of the critical behaviour within liquid state theories is reviewed with emphasis on both the universal and the non-universal properties. Simple lattice and continuous models, such as the Ising model and the Lennard-Jones fluid, are examined by the use of several techniques, ranging from the integral equation method to the renormalization group analysis. A self-contained derivation of the hierarchical reference theory (HRT) of fluids is given together with a detailed discussion of the universal properties within a simple approximation to the exact HRT equations. Applications to simple models and comparisons with the results of other investigations are presented. HRT is then generalized to binary fluids, allowing for a complete description of the possible critical behaviours in these systems. The problems of a microscopic definition of the order parameter in mixtures and of the origin of strong crossover phenomena in binary fluids are also addressed.

Parola, Alberto; Reatto, Luciano

1995-05-01

254

Lunar orbital photography of astronomical phenomena.  

NASA Technical Reports Server (NTRS)

This paper reports further progress on photography of faint astronomical and geophysical phenomena accomplished during the recent Apollo missions. Command module pilots have been able to photograph such astronomical objects as the solar corona, zodiacal light-corona transition region, lunar libration region, and portions of the Milky Way. The methods utilized for calibration of the film by adaptation of the High Altitude Observatory sensitometer are discussed. Kodak 2485 high-speed recording film was used in both 35-mm and 70-mm formats. The cameras used were Nikon f/1.2 55-mm focal length and Hasselblad f/2.8 80-mm focal length. Preflight and postflight calibration exposures were included on both the flight and control films, corresponding to luminances extending from the inner solar corona to as faint as 1/10 of the luminance of the light of the night sky. The photographs obtained from unique vantage points available during lunar orbit are discussed.

Mercer, R. D.; Dunkelman, L.; Ross, C. L.; Worden, A.

1972-01-01

255

Large Interface Simulation in Multiphase Flow Phenomena  

SciTech Connect

An attempt to represent multiphase multi-scale flow, filling the gap between Direct Numerical Simulation (DNS) and averaged approaches, is the purpose of this paper. We present a kind of Large Interface (LI) simulation formalism obtained after a filtering process on local instantaneous conservation equations of the two-fluid model which distinguishes between small scales and large scales contributions. LI surface tension force is also taken into account. Small scale dynamics call for modelization and large scale for simulation. Joined to this formalism, a criterion to recognize LI's is developed. It is used in an interface recognition algorithm which is qualified on a sloshing case and a bubble oscillation under zero-gravity. This method is applied to a rising bubble in a pool that collapses at a free surface and to a square-base basin experiment where splashing and sloshing at the free surface are the main break-up phenomena. (authors)

Henriques, Aparicio; Coste, Pierre; Pigny, Sylvain [CEA-Grenoble, 17, rue des Martyrs 38054 Grenoble Cedex 9 (France); Magnaudet, Jacques [Institut Mecanique des Fluides de Toulouse, 1 Allee du Professeur Camille Soula, 31400 Toulouse (France)

2006-07-01

256

Natural time analysis of critical phenomena.  

PubMed

A quantity exists by which one can identify the approach of a dynamical system to the state of criticality, which is hard to identify otherwise. This quantity is the variance ?(1)(? - (2)) of natural time ?, where = ?p(k)f(?(k)) and p(k) is the normalized energy released during the kth event of which the natural time is defined as ?(k) = k/N and N stands for the total number of events. Then we show that ?(1) becomes equal to 0.070 at the critical state for a variety of dynamical systems. This holds for criticality models such as 2D Ising and the Bak-Tang-Wiesenfeld sandpile, which is the standard example of self-organized criticality. This condition of ?(1) = 0.070 holds for experimental results of critical phenomena such as growth of rice piles, seismic electric signals, and the subsequent seismicity before the associated main shock. PMID:21700886

Varotsos, Panayiotis; Sarlis, Nicholas V; Skordas, Efthimios S; Uyeda, Seiya; Kamogawa, Masashi

2011-07-12

257

New biological phenomena associated with laser radiation  

SciTech Connect

Low-energy laser irradiation produces significant bioeffects. These effects are manifested in biochemical, physiological and proliferative phenomena in various enzymes, cells, tissues, organs and organisms. Examples are given of the effect of He-Ne laser irradiation in preventing the post-traumatic degeneration of peripheral nerves and the postponement of degeneration of the central nervous system. The damage produced by similar radiant exposures to the corneal epithelium and endothelium is also described. It is suggested that the mechanism of laser/tissue interaction at these low levels of radiant exposure is photochemical in nature, explaining most of the characteristics of these effects. These low-energy laser bioeffects are of importance on a basic scientific level, from a laser safety aspect and as a medical therapeutic modality. 25 references.

Belkin, M.; Schwartz, M.

1989-05-01

258

Reversion phenomena of Cu-Cr alloys  

NASA Technical Reports Server (NTRS)

Cu-Cr alloys which were given various aging and reversion treatments were investigated in terms of electrical resistivity and hardness. Transmission electron microscopy was one technique employed. Some results obtained are as follows: the increment of electrical resistivity after the reversion at a constant temperature decreases as the aging temperature rises. In a constant aging condition, the increment of electrical resistivity after the reversion increases, and the time required for a maximum reversion becomes shorter as the reversion temperature rises. The reversion phenomena can be repeated, but its amount decreases rapidly by repetition. At first, the amount of reversion increases with aging time and reaches its maximum, and then tends to decrease again. Hardness changes by the reversion are very small, but the hardness tends to soften slightly. Any changes in transmission electron micrographs by the reversion treatment cannot be detected.

Nishikawa, S.; Nagata, K.; Kobayashi, S.

1985-01-01

259

Surfactant-based critical phenomena in microgravity  

NASA Technical Reports Server (NTRS)

The objective of this research project is to characterize by experiment and theoretically both the kinetics of phase separation and the metastable structures produced during phase separation in a microgravity environment. The particular systems we are currently studying are mixtures of water, nonionic surfactants, and compressible supercritical fluids at temperatures and pressures where the coexisting liquid phases have equal densities (isopycnic phases). In this report, we describe experiments to locate equilibrium isopycnic phases and to determine the 'local' phase behavior and critical phenomena at nearby conditions of temperature, pressure, and composition. In addition, we report the results of preliminary small angle neutron scattering (SANS) experiments to characterize microstructures that exist in these mixtures at different fluid densities.

Kaler, Eric W.; Paulaitis, Michael E.

1994-01-01

260

Modeling of elasto-capillary phenomena.  

PubMed

Surface energy is an important factor in the deformation of fluids but is typically a minimal or negligible effect in solids. However, when a solid is soft and its characteristic dimension is small, forces due to surface energy can become important and induce significant elastic deformation. The interplay between surface energy and elasticity can lead to interesting elasto-capillary phenomena. We present a finite-element-based numerical simulation capability for modeling these effects in a static, implicit framework. We demonstrate the capacity of the simulation capability by examining three elasto-capillary problems: (i) wetting of an elastic hemispherical droplet on a substrate, (ii) cavitation of an elastomer, and (iii) the Rayleigh-Plateau instability in soft elastic filaments. PMID:24836202

Henann, David L; Bertoldi, Katia

2014-02-01

261

Photonic coherence phenomena in coupled optical resonators  

NASA Astrophysics Data System (ADS)

A structure consisting of N coupled optical resonators exhibits resonances that split into N higher-Q modes due to coherent coupling between resonators. This has a direct analogy with other types of oscillators. In particular, for two (or any even number of) coupled optical resonators, this mode splitting leads to a cancellation of absorption on resonance as a result of classical destructive interference of the symmetric and antisymmetric modes of the system. An analogy between this effect and electromagnetically-induced transparency in an atomic system is explored. Furthermore, a variety of photonic coherence phenomena in passive and active coupled optical resonators is investigated. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. It is also demonstrated that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation. The impulse response of coupled resonators is also derived. It is found that the coupled-resonator photon dynamics display damped Rabi oscillations, which facilitates adiabatic coherent photon transfer techniques such as stimulated Raman adiabatic passage. These effects are predicted directly from coupled-mode theory, and thus are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators. It is also theoretically predicted that in coupled optical resonators slow and fast light can propagate without attenuation. In systems of coupled resonators, slow light can propagate without attenuation by a cancellation of absorption as a result of mode splitting and destructive interference, whereas transparent fast light propagation can be achieved with the assistance of gain and splitting of the intracavity resonances, which consequently switches the dispersion from normal to anomalous.

Chang, Hongrok

262

Space Weather and Planetary Atmospheres  

NASA Astrophysics Data System (ADS)

Space weather is the rubric applied to phenomena that effect the near-Earth space environment and, more importantly, to the response of that environment to external inputs. Space weather at Earth is important in terms of the root cause of some satellite anomalies, effects on radio communications, and changes in atmospheric drag experienced by satellites. Many of these effects are observed at other planets and can rightly be included in any discusion of space weather. As we consider the next steps in the exploration of other planets we need to be aware that space weather will shape how and when we can safely go to other planets and determine to some degree the scope and implementation of the design of missions to these planets. Mars is, after the Moon, the next target for human exploration. The atmosphere of Mars and its interaction with the changing solar system environment is the main subject of this oveview paper. The Mars atmosphere and ionosphere are fascinating - and they represent a true test of the predictive capabilities of our first principles models. There will be brief excursions into the the issues that need to addressed for a Venus mission as well as some consideration of the open questions at Europa and Titan - possible longer-term targets for robotic exploration.

Paxton, L. J.

2006-05-01

263

Earth's Ionosphere as a Gigantic Detector of Extra-terrestrial Energetic Phenomena: A Review  

NASA Astrophysics Data System (ADS)

The paper presents the ionospheric effects due to radiation from the transient extraterrestrial sources like Gamma Ray Bursts, Soft Gamma Ray Repeaters, Anomalous X-ray Pulsars, X-ray novae and X-ray transient sources. Gamma rays could penetrate deep in the atmosphere due to their high energy in comparison with other types of radiation. If the transient radiation from the above sources is strong enough to enhance the ionospheric ionization, VLF radio propagation could be affected. In the paper, we discuss the evidences of detection of such phenomena in VLF data and explain some of the observations using theoretical considerations.

Mondal, S. K.; Chakrabarti, S. K.

2010-10-01

264

Atmospheric electricity  

NASA Technical Reports Server (NTRS)

In the last three years the focus was on the information contained in the lightning measurement, which is independent of other meteorological measurements that can be made from space. The characteristics of lightning activity in mesoscale convective systems were quantified. A strong relationship was found between lightning activity and surface rainfall. It is shown that lightning provides a precursor signature for wet microbursts (the strong downdrafts that produce windshears hazardous to aircraft) and that the lightning signature is a direct consequence of storm evolution. The Universities Space Research Association (USRA) collaborated with NASA scientists in the preliminary analysis and scientific justification for the design and deployment of an optical instrument which can detect lightning from geostationary orbit. Science proposals for the NASA mesoscale science program and for the Tethered Satellite System were reviewed. The weather forecasting research and unmanned space vehicles. Software was written to ingest and analyze the lightning ground strike data on the MSFC McIDAS system. The capabilities which were developed have a wide application to a number of problems associated with the operational impacts of electrical discharge within the atmosphere.

1987-01-01

265

Flashbacks and memory phenomena. A comment on "Flashback phenomena--clinical and diagnostic dilemmas".  

PubMed

Alarcon, Dickinson, and Dohn (J. Nerv. Ment. Dis., 170: 217-223, 1982) recently reviewed the phenomenon of memory flashback following use of hallucinogenic drugs. They point out that while there are a considerable number of explanations concerning the flashback mechanism, little is known about the real causes. This paper examines flashback following drug ingestion in the light of other memory phenomena concerned with "cued retrieval" effects. Such phenomena may include dream recall, delayed post-traumatic stress, mood influence on memory, and drug effects on memory. Rather than view flashbacks as "pathological" in some sense, it may be better to view them as instances of normal memory processes, which may, nevertheless, be accompanied by emotional distress. Such a view relates flashbacks to a wider memory literature, and also makes them amenable to investigation using research designs derived from that literature. PMID:6716092

McGee, R

1984-05-01

266

The Role of Family Phenomena in Posttraumatic Stress in Youth  

PubMed Central

Topic Youth face trauma that can cause posttraumatic stress (PTS). Purpose 1). To identify the family phenomena used in youth PTS research; and 2). Critically examine the research findings regarding the relationship between family phenomena and youth PTS. Sources Systematic literature review in PsycInfo, PILOTS, CINAHL, and MEDLINE. Twenty-six empirical articles met inclusion criteria. Conclusion Measurement of family phenomena included family functioning, support, environment, expressiveness, relationships, cohesion, communication, satisfaction, life events related to family, parental style of influence, and parental bonding. Few studies gave clear conceptualization of family or family phenomena. Empirical findings from the 26 studies indicate inconsistent empirical relationships between family phenomena and youth PTS, though a majority of the prospective studies support a relationship between family phenomena and youth PTS. Future directions for leadership by psychiatric nurses in this area of research and practice are recommended.

Deatrick, Janet A.

2010-01-01

267

Pathways toward understanding Macroscopic Quantum Phenomena  

NASA Astrophysics Data System (ADS)

Macroscopic quantum phenomena refer to quantum features in objects of 'large' sizes, systems with many components or degrees of freedom, organized in some ways where they can be identified as macroscopic objects. This emerging field is ushered in by several categories of definitive experiments in superconductivity, electromechanical systems, Bose-Einstein condensates and others. Yet this new field which is rich in open issues at the foundation of quantum and statistical physics remains little explored theoretically (with the important exception of the work of A J Leggett [1], while touched upon or implied by several groups of authors represented in this conference. Our attitude differs in that we believe in the full validity of quantum mechanics stretching from the testable micro to meso scales, with no need for the introduction of new laws of physics.) This talk summarizes our thoughts in attempting a systematic investigation into some key foundational issues of quantum macroscopic phenomena, with the goal of ultimately revealing or building a viable theoretical framework. Three major themes discussed in three intended essays are the large N expansion [2], the correlation hierarchy [3] and quantum entanglement [4]. We give a sketch of the first two themes and then discuss several key issues in the consideration of macro and quantum, namely, a) recognition that there exist many levels of structure in a composite body and only by judicious choice of an appropriate set of collective variables can one give the best description of the dynamics of a specific level of structure. Capturing the quantum features of a macroscopic object is greatly facilitated by the existence and functioning of these collective variables; b) quantum entanglement, an exclusively quantum feature [5], is known to persist to high temperatures [6] and large scales [7] under certain conditions, and may actually decrease with increased connectivity in a quantum network [8]. We use entanglement as a measure of quantumness here and pick out these somewhat counter-intuitive examples to show that there are blind spots worthy of our attention and issues which we need to analyze closer. Our purpose is to try to remove the stigma that quantum only pertains to micro, in order to make way for deeper probes into the conditions whereby quantum features of macroscopic systems manifest.

Hu, B. L.; Suba?i, Y.

2013-06-01

268

The solar atmosphere, solar magnetism and solar activity  

Microsoft Academic Search

A survey is presented of known physical characteristics of the solar corona, active solar regions and solar magnetism, along with interactions among the various solar dynamical phenomena. Emphasis is placed on features of the solar atmosphere which contribute to RF emissions from the sun, and to those which reveal the structure and behavior of the solar magnetic field. The characteristics

G. A. Dulk

1985-01-01

269

Investigations of atmospheric dynamics using a CW Doppler sounder array  

NASA Technical Reports Server (NTRS)

A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

Rao, G. L.

1974-01-01

270

Magnetospheric waves and the atmosphere-ionosphere layer  

Microsoft Academic Search

A novel approach to the issue of what effect the ionosphere and atmosphere have on magnetospheric phenomena, an approach that provides explicit boundary conditions for coupled hydromagnetic waves and makes it possible to give an explicit solution to the pulsation problem within a particularly simple configuration, is presented. It is shown that, consistent with well-known observations, the amplitude of resonantly

E. Hameiri; M. G. Kivelson

1991-01-01

271

Atmospheric effects on availability of free space optics systems  

Microsoft Academic Search

The availability of free space optics (FSO) systems in dependence on weather conditions and on FSO link parameters, such as transmitted optical power, beam divergence, receiver sensitivity or link path distance, is discussed. A number of phenomena in the atmosphere, such as absorption, scattering, and turbulence, can affect beam attenuation, but in the case of wavelengths typical of FSO systems

Ales Prokes

2009-01-01

272

Atmospheric transport of soil dust from Africa to South America  

Microsoft Academic Search

The arid and desert regions of North Africa are a prolific source of atmospheric dust. This dust is, for example, responsible for the `red snows' reported in the Alps and Pyrenees1 and for dust falls further north in Europe2-6, but these phenomena are infrequent and sporadic. By contrast, the transport of mineral dust into the tropical North Atlantic is common

J. M. Prospero; R. A. Glaccum; R. T. Nees

1981-01-01

273

Spherical formations in the atmosphere as a physical phenomenon  

Microsoft Academic Search

This paper presents an attempt to elucidate the physical nature of the stable luminous spherical formations that are sometimes observed in the atmosphere. It is suggested that there may be a connection between some of these natural formations and Unidentified Flying Objects. Properties common to spherical formations and ball lightnings have been found. A mathematical model describing such natural phenomena

A. I. Mesenyashin

1995-01-01

274

Data Processing for Atmospheric Phase Interferometers  

NASA Technical Reports Server (NTRS)

This paper presents a detailed discussion of calibration procedures used to analyze data recorded from a two-element atmospheric phase interferometer (API) deployed at Goldstone, California. In addition, we describe the data products derived from those measurements that can be used for site intercomparison and atmospheric modeling. Simulated data is used to demonstrate the effectiveness of the proposed algorithm and as a means for validating our procedure. A study of the effect of block size filtering is presented to justify our process for isolating atmospheric fluctuation phenomena from other system-induced effects (e.g., satellite motion, thermal drift). A simulated 24 hr interferometer phase data time series is analyzed to illustrate the step-by-step calibration procedure and desired data products.

Acosta, Roberto J.; Nessel, James A.; Morabito, David D.

2009-01-01

275

In Brief: Atmospheric brown cloud report  

NASA Astrophysics Data System (ADS)

The combined effects of human-made atmospheric brown clouds (ABCs) and greenhouse gases in the atmosphere are having broad-based impacts, including causing some cities to get darker, contributing to faster melting of some glaciers, masking the effects of climate change, and having negative effects on agriculture and air quality, according to a 13 November report released by the United Nations Environment Programme (UNEP). ``We believe today's report brings ever more clarity to the ABC phenomena and in doing so must trigger an international response, one that tackles the twin threats of greenhouse gases and brown clouds and the unsustainable development that underpins both,'' said Veerabhadran Ramanathan, head of the UNEP scientific panel carrying out the research and a professor at the Scripps Institution of Oceanography, La Jolla, Calif. The report, ``Atmospheric brown clouds: Regional assessment report with focus on Asia,'' can be found at http://www.unep.org.

Showstack, Randy

2008-11-01

276

New theoretical treatment of ion resonance phenomena.  

PubMed

Despite experimental evidence supporting ICR-like interactions in biological systems, to date there is no reasonable theoretical explanation for this phenomenon. The parametric resonance approach introduced by Lednev has enjoyed limited success in predicting the response as a function of the ratio of AC magnetic intensity to that of the DC field, explaining the results in terms of magnetically induced changes in the transition probability of calcium binding states. In the present work, we derive an expression for the velocity of a damped ion with arbitrary q/m under the influence of the Lorentz force. Series solutions to the differential equations reveal transient responses as well as resonance-like terms. One fascinating result is that the expressions for ionic drift velocity include a somewhat similar Bessel function dependence as was previously obtained for the transition probability in parametric resonance. However, in the present work, not only is there an explicit effect due to damping, but the previous Bessel dependence now occurs as a subset of a more general solution, including not only the magnetic field AC/DC ratio as an independent variable, but also the ratio of the cyclotronic frequency Omega to the applied AC frequency omega. In effect, this removes the necessity to explain the ICR interaction as stemming from ion-protein binding sites. We hypothesize that the selectively enhanced drift velocity predicted in this model can explain ICR-like phenomena as resulting from increased interaction probabilities in the vicinity of ion channel gates. PMID:18288680

Vincze, G; Szasz, A; Liboff, A R

2008-07-01

277

Recognizing hesitation phenomena in continuous, spontaneous speech  

NASA Astrophysics Data System (ADS)

Spontaneous speech differs from read speech in speaking rate and hesitation. In natural, spontaneous speech, people often start talking and then think along the way; at times, this causes the speech to have hesitation pauses (both filled and unfilled) and restarts. Results are reported on all types of pauses in a widely-used speech database, for both hesitation pauses and semi-intentional pauses. A distinction is made between grammatical pauses (at major syntactic boundaries) and ungrammatical ones. Different types of unfilled pauses cannot be reliably separated based on silence duration, although grammatical pauses tend to be longer. In the prepausal word before ungrammatical pauses, there were few continuation rises in pitch, whereas 80 percent of the grammatical pauses were accompanied by a prior fundamental frequency rise of 10-40 kHz. Identifying the syntactic function of such hesitation phenomena can improve recognition performance by eliminating from consideration some of the hypotheses proposed by an acoustic recognizer. Results presented allow simple identification of filled pauses (such as uhh, umm) and their syntactic function.

Oshaughnessy, Douglas

278

The demystification of autoscopic phenomena: experimental propositions.  

PubMed

Autoscopic phenomena (AP) are rare, illusory visual experiences during which the subject has the impression of seeing a second own body in extrapersonal space. AP consist of out-of-body experience, autoscopic hallucination, and heautoscopy. Recent neurologic reports support the role of multisensory integration deficits of body-related information and vestibular dysfunctions in AP at the temporo-parietal junction. A caveat to test the underlying neurologic and cognitive mechanisms of AP has been their rare and spontaneous occurrence. Recent evidence linked AP to mental own-body imagery engaging brain mechanisms at the temporo-parietal junction. These recent observations open a new avenue for testing AP-related cognitive mechanisms in selected clinical and normal populations. We review evidence on several clinical syndromes (psychosis, depression, anxiety, depersonalization, body dysmorphic disorder), suggesting that some of these syndromes may relate to AP-proneness, thereby leading to testable propositions for future research on body and self processing in addition to AP. PMID:15935132

Mohr, Christine; Blanke, Olaf

2005-06-01

279

[Stochastic phenomena and the tumoral process].  

PubMed

In the reductionist perspective, genetic modifications are considered to initiate cancer. Their appearance is a stochastic phenomenon, but there are some biases linked to DNA sequence or exposure to mutagenic agents for instance. Cancer genome sequencing has shown a high inter- and intra-tumoral heterogeneity, sometimes questioning the genetic origin of cancer. Other stochastic processes are also studied in cancer, especially epigenetic modifications. They have a major role in diversifying phenotypes among cancer cells in the progression steps, but might also provide an alternative to genetic theories of cancer initiation. Nevertheless, the reductionist framework remains dominant here. Finally, stochastic cell-to-cell variations in gene expression constitute a third class of stochastic phenomena that can be considered as causal factors in cancer. Highlighting the role of high gene expression variability due to disruption of cellular interactions and communications allows avoiding reductionism by considering the interplay between genetic and tissue levels at every step of the disease. No organization level is privileged in this alternative theory. PMID:25014464

Capp, Jean-Pascal

2014-01-01

280

Rheological Properties and Transfer Phenomena of Nanofluids  

NASA Astrophysics Data System (ADS)

This study focused on the synthesis of stable nanofluids and investigation of their rhelogical properties and transfer phenomena. Nanofluids of diamond/ethylene glycol, alumina/transformer oil and silica/water were made to use in this study. Rheological properties of diamond nanofluids were determined at constant temperature (25 °C) using a viscometer. For the convective heat transfer experiment, alumina nanofluid passed through the plate heat exchanger. CO2 absorption experiment was conducted in a bubble type absorber containing silica nanofluid. Diamond nanofluid showed non-Newtonian behaviors under a steady-shear flow except the case of very low concentration of solid nanoparticles. The heat transfer coefficient of alumina nanofluid was higher than that of base fluid. One possible reason is that concentration of nanoparticles at the wall side is higher than that of microparticles. Silica nanofluid showed that both average CO2 absorption rate and total absorption amount enhanced than those of base fluid. The stably suspended nanoparticles create a mesh-like structure. That structure arrangement cracks the gas bubble and increases the surface area.

Jung, Kang-Min; Kim, Sung Hyun

2008-07-01

281

Characterizing the Multiscale Phenomena of the Magnetosphere  

NASA Astrophysics Data System (ADS)

The multiscale nature of the magnetospheric response to the driving by the turbulent solar wind is prototypical of open natural systems. The distribution of scales in the magnetosphere are studied using data from space- borne and ground-based measurements. The burst lifetime distribution of the AL index, which is a characteristic response of the magnetosphere, has been found to be a combination of a power law with an exponential cutoff and a log-normal function [Freeman et al., GRL, 27, 1087, 2000]. The distribution of waiting times between substorms above a certain threshold have also been shown to have a similiar behavior [Freeman et.al, Phys. Rev. E 2000]. An important feature of both these distributions is the clear deviation from the power law behavior for longer time scales. The distribution of scales in the AL index (1 min resolution) from January 1978 to June 1988 and from January 1990 to December 1995, consisting of approximately 8.6 million data points, is studied to determine the distribution of scales. There is a clear deviation of the burst duration distribution at lower thresholds from a stretched exponential and the same occurs for the waiting time distribution at higher thresholds. The stretched exponential distributions of waiting times are recognized as a universal behavior for long term correlated data, and the deviations from such a distribution in the case of the magnetosphere indicate the presence of both long and short range correlations. This implies that the magnetospheric dynamics exhibit both global and multiscale phenomena.

Sharma, A.; Veeramani, T.

2007-05-01

282

Chaos and Related Phenomena in Electrical Circuits.  

NASA Astrophysics Data System (ADS)

We will perform demonstrations of chaotic phenomena found in simple electronic circuits. Chaos is produced in a circuit called a diode resonator, which is comprised of a p-n junction diode and an inductor, driven by a sinusoidal source. The circuit follows the period doubling route to chaos and its chaotic attractor will be shown in real time. The control of chaos in this circuit will be demonstrated by using a technique called occasional proportional feedback (OPF). Next we look at the dynamics found of two coupled diode resonators. This circuit shows a Hopf bifurcation followed by the quasiperiodic route to chaos. We will demonstrate OPF control of this circuit to the steady-state, to periodic orbits and to a doubly unstable state. Finally, we hook up a linear array of 32 unidirectionally coupled diode resonators and demonstrate spatiotemporal chaos. We show that stabilizing the first element in particular high- period orbits can stabilize the entire array by creating travelling phase-kink solitons.

Hunt, Earle R.

1996-11-01

283

High energy phenomena during solar flares  

NASA Astrophysics Data System (ADS)

The main purpose is to analyze the characteristics of peculiar solar events that could be produced by ultrarelativistic electrons and try to define the new boundary conditions for the primary energy release during impulsive phase. It seems that submillimeter emission in solar flares is not a rare phenomenon, there is not much evidence, due to the lack of observations in this range of the spectrum. During May 1984 the Sun was observed at 90 GHz with high time resolution and high sensitivity, and evidence was obtained. The May 21, 1984 event, at 1326 UT is the best example of the high energy manifestation during the spectrum and gave us new boundary conditions for the physical phenomena in the Sun. The May 21 event required a detailed analysis of the current interpretation models and suggested the presence of relativistic electrons during the impulsive phase. In this case Syncrotron/inverse compton mechanism was suggested to explain submillimeter/x ray emission and short pulse duration. The new boundary conditions for primary energy release favored Tajima and Sakai's model, based in magnetic island coalescence theory.

Correia, Emilia

1989-11-01

284

Chemically Tunable Transport Phenomena of Functionalized Graphene  

NASA Astrophysics Data System (ADS)

We present an ab initio multiscale study and quantum transport simulations using the Kubo formalism [1] of chemically modified graphene based materials, whose properties are tuned by changing the density and nature of grafted molecular units. Depending on the nature of the introduced molecular bonding different conduction mechanism are obtained, including transition from weak to strong Anderson localization [2,3], as well as spin-dependent phenomena [4] and magnetoresistive fingerprints [5]. [4pt] References: [1] H. Ishii, F. Triozon, N. Kobayashi, K. Hirose, and S. Roche, C. R. Physique 10, 283 (2009) [2] N. Leconte, J. Moser, P. Ordejon, H. Tao, A. Lherbier, A. Bachtold, F. Alsina, C.M. Sotomayor Torres, J.-C. Charlier, and S. Roche, ACS Nano 4, 7, 4033-4038 (2010) [3] N. Leconte, A. Lherbier, F. Varchon, P. Ordejon, S. Roche, and J.-C. Charlier (accepted in PRB) [4] N. Leconte, D. Soriano, S. Roche, P. Ordejon, J.-C. Charlier, and J.J. Palacios, ACS Nano 5, 5, 3987-3992 (2011) [5] D. Soriano, N. Leconte, P. Ordejon, J.-C. Charlier, J.J. Palacios, and S. Roche, Phys. Rev. Lett. 107, 016602 (2011)

Leconte, Nicolas; Lherbier, Aurélien; Varchon, Francois; Charlier, Jean-Christophe; Palacios, Juan Jose; Soriano, David; Ordejon, Pablo; Roche, Stephan

2012-02-01

285

Bubble breakup phenomena in a venturi tube  

NASA Astrophysics Data System (ADS)

Microbubble has distinguished characteristics of large surface area to unit volume and small buoyancy, and it has advantages in many engineering fields. Recently microbubble generators with low energy and high performance are required to wide applications. In the present study, we propose one new effective technique to generate tiny bubbles with less than 200 ?m diameter utilizing venturi tube under high void fraction condition. The objective of the present study is to elucidate the mechanism of bubble breakup phenomena in the venturi tube and to clarify the effects of parameters which are necessary to realize an optimum system experimentally. Experiment was conducted with void fraction of 4% and variation of liquid velocity from 9 to 26 m/s at the throat. Under low velocity condition, bubbles which were observed with a high speed camera parted gradually in a wide region. On the contrary under high velocity condition, bubbles expanded after passing through the throat and shrank rapidly. Since the speed of sound in gas-liquid system is extremely lower than that of single-phase flow, the bubble breakup phenomenon in the venturi tube is explained as the supersonic flow in a Laval nozzle. By rapid pressure recovery in diverging area, expanding bubbles collapse violently. The tiny bubbles are generated due to the surface instability of shrinking bubbles.

Fujiwara, Akiko

2005-11-01

286

Emergent phenomena in manganites under spatial confinement  

NASA Astrophysics Data System (ADS)

It is becoming increasingly clear that the exotic properties displayed by correlated electronic materials such as high-Tc superconductivity in cuprates, colossal magnetoresistance (CMR) in manganites, and heavy-fermion compounds are intimately related to the coexistence of competing nearly degenerate states which couple simultaneously active degrees of freedom—charge, lattice, orbital, and spin states. The striking phenomena associated with these materials are due in a large part to spatial electronic inhomogeneities, or electronic phase separation (EPS). In many of these hard materials, the functionality is a result of the soft electronic component that leads to self-organization. In this paper, we review our recent work on a novel spatial confinement technique that has led to some fascinating new discoveries about the role of EPS in manganites. Using lithographic techniques to confine manganite thin films to length scales of the EPS domains that reside within them, it is possible to simultaneously probe EPS domains with different electronic states. This method allows for a much more complete view of the phases residing in a material and gives vital information on phase formation, movement, and fluctuation. Pushing this trend to its limit, we propose to control the formation process of the EPS using external local fields, which include magnetic exchange field, strain field, and electric field. We term the ability to pattern EPS “electronic nanofabrication." This method allows us to control the global physical properties of the system at a very fundamental level, and greatly enhances the potential for realizing true oxide electronics.

Shen, Jian; Z. Ward, T.; F. Yin, L.

2013-01-01

287

Microbiology and atmospheric processes: research challenges concerning the impact of airborne micro-organisms on the atmosphere and climate  

NASA Astrophysics Data System (ADS)

For the past 200 years, the field of aerobiology has explored the abundance, diversity, survival and transport of micro-organisms in the atmosphere. Micro-organisms have been explored as passive and severely stressed riders of atmospheric transport systems. Recently, an interest in the active roles of these micro-organisms has emerged along with proposals that the atmosphere is a global biome for microbial metabolic activity and perhaps even multiplication. As part of a series of papers on the sources, distribution and roles in atmospheric processes of biological particles in the atmosphere, here we describe the pertinence of questions relating to the potential roles that air-borne micro-organisms might play in meteorological phenomena. For the upcoming era of research on the role of air-borne micro-organisms in meteorological phenomena, one important challenge is to go beyond descriptions of abundance of micro-organisms in the atmosphere toward an understanding of their dynamics in terms of both biological and physico-chemical properties and of the relevant transport processes at different scales. Another challenge is to develop this understanding under contexts pertinent to their potential role in processes related to atmospheric chemistry, the formation of clouds, precipitation and radiative forcing. This will require truly interdisciplinary approaches involving collaborators from the biological and physical sciences, from disciplines as disparate as agronomy, microbial genetics and atmosphere physics, for example.

Morris, C. E.; Sands, D. C.; Bardin, M.; Jaenicke, R.; Vogel, B.; Leyronas, C.; Ariya, P. A.; Psenner, R.

2011-01-01

288

Satellite Observations of Upper Atmospheric Discharges With the ISUAL Instrument on the ROCSAT-2 Satellite  

Microsoft Academic Search

The Imager of Sprites and Upper Atmospheric Lightning (ISUAL) experiment on ROCSAT 2 satellite will make the first synoptic spacecraft based measurements of lightning induced luminous phenomena. Science objectives of the ISUAL instrument are the determination of the spatial, temporal and spectral properties of lightning induced upper atmospheric optical flash transients (sprites, elves, blue jets etc.) and the global (geographic\\/seasonal)

S. B. Mende; L. Lee; J. Chern; R. Hsu; H. Su; H. Fukunishi; Y. Takahashi

2001-01-01

289

Luminous phenomena and electromagnetic VHF wave emission originated from earthquake-related radon exhalation  

NASA Astrophysics Data System (ADS)

Anomalous luminous phenomena and electromagnetic wave emission before or during earthquakes have been reported (e.g., the 1965 Matsushiro earthquake swarm). However, their mechanism is still unsolved, in spite of many models for these phenomena. Here, we propose a new model about luminous phenomena and electromagnetic wave emission during earthquake by focusing on atmospheric radon (Rn-222) and its daughter nuclides (Po-218 and Po-214). Rn-222, Po-218 and Po-214 are alpha emitters, and these alpha particles ionize atmospheric molecules. A light emission phenomenon, called 'the air luminescence', is caused by de-excitation of the ionized molecules of atmospheric nitrogen due to electron impact ionization from alpha particles. The de-excitation is from the second positive system of neutral nitrogen molecules and the first negative system of nitrogen molecule ion. Wavelengths of lights by these transitions include the visible light wavelength. So based on this mechanism, we proposed a new luminous phenomenon model before or during earthquake: 1. The concentration of atmospheric radon and its daughter nuclides increase anomalously before or during earthquakes, 2. Nitrogen molecules and their ions are excited by alpha particles emitted from Rn-222, Po-218 and Po-214, and air luminescence is generated by their de-excitation. Similarly, electromagnetic VHF wave emission can be explained by ionizing effect of radon and its daughter nuclides. Boyarchuk et al. (2005) proposed a model that electromagnetic VHF wave emission is originated when excited state of neutral clusters changes. Radon gas ionizes atmosphere and forms positively and negatively charged heavy particles. The process of ion hydration in ordinary air can be determined by the formation of complex chemically active structures of the various types of ion radicals. As a result of the association of such hydration radical ions, a neutral cluster, which is dipole quasi-molecules, is formed. A neutral cluster's rotation-rotation transition causes electromagnetic VHF wave emission. We also discuss a possibility of electromagnetic VHF wave emission from excitation of polyatomic molecules by alpha particles from Rn-222 and its daughter nuclides, similar to air luminescence by excitation of nitrogen molecule in the viewpoint of electromagnetic radiation in quantum theory.

Seki, A.; Tobo, I.; Omori, Y.; Muto, J.; Nagahama, H.

2013-12-01

290

Remote detection of radioactive contamination in the atmosphere based on secondary optical and microwave radiation of atmospheric components  

Microsoft Academic Search

The paper analyzes secondary phenomena of atmospheric radioactive pollution caused by activity of the nuclear cycle enterprises. These effects being as indicators for remote diagnostics of a radio-activity are discussed. Excitation of a molecular and gas component in the air and various chemical reactions under the action of radiation have been considered. As a result of these reactions, new aerosol

Liliya K. Chistyakova; Sergei T. Penin

1999-01-01

291

Laboratory experiments in atmospheric optics.  

PubMed

Old and new laboratory experiments on atmospheric optics with a focus on mirages, rainbows, and halos are presented. Some qualitative demonstrations serve primarily didactical purposes, e.g., by proving the existence of curved light rays in media with a gradient of the index of refraction, by directly visualizing the minimum-deviation curve for rainbow paths in water droplets, or by helping to elucidate the ray classes in hexagons that contribute to a specific halo. In addition, quantitative experiments allow a direct comparison of angular positions and intensities with analytical computations or Monte Carlo simulations of light scattering from small water droplets or ice hexagons. In particular, the latter can help us to understand complex halo phenomena. PMID:19399049

Vollmer, M; Tammer, R

1999-08-16

292

Laboratory experiments in atmospheric optics.  

PubMed

Old and new laboratory experiments on atmospheric optics with a focus on mirages, rainbows, and halos are presented. Some qualitative demonstrations serve primarily didactical purposes, e.g., by proving the existence of curved light rays in media with a gradient of the index of refraction, by directly visualizing the minimum-deviation curve for rainbow paths in water droplets, or by helping to elucidate the ray classes in hexagons that contribute to a specific halo. In addition, quantitative experiments allow a direct comparison of angular positions and intensities with analytical computations or Monte Carlo simulations of light scattering from small water droplets or ice hexagons. In particular, the latter can help us to understand complex halo phenomena. PMID:18268748

Vollmer, M; Tammer, R

1998-03-20

293

Study of phenomena related to the sintering process of silicon nitride at atmospheric pressure  

NASA Technical Reports Server (NTRS)

A procedure was perfected for the production of components used in engineering applications of silicon nitride. Particles of complex geometry that combine remarkable mechanical properties with a high density are obtained. The process developed, in contrast to the "hot pressing" method, does not use external pressures, and in contrast to the reaction bonding method, final densities close to the theoretical value are obtained.

Bertani, A.

1982-01-01

294

RAMOS: A Space Mission With Real-Time Stereoscopy of Atmospheric Phenomena  

Microsoft Academic Search

RAMOS (Russian American Observational Satellites), scheduled for launch in 2009, is a joint mission of the Russian Federation and the United States of America. Two low earth-orbit satellites with complementary instrument suites will fly in tandem orbits at an altitude of ˜ 500 km and a variable mean separation of ˜ 300 km. The satellites will be capable of simultaneous

P. C. Joss; A. T. Stair; T. Humpherys; V. Sinelshchikov; V. Misnik

2004-01-01

295

Atmospheric tides and other relationships: ``Interpreting the Phenomena'' at the time of the Seeberg conference  

Microsoft Academic Search

Lalande's account of his experiences at Gotha and on his journey back to France [AGE 2 (1798), 381-382] contains an interesting attempt to explain the extremely rainy September weather (``at a time of the year when it is raining more rarely in our countries'') by means of the Moon's southern declination. Actually, there are several other documents on the same

Wolfgang Kokott

1998-01-01

296

Turbulent mixing with scale breaking phenomena  

NASA Astrophysics Data System (ADS)

We study the Rayleigh-Taylor (RT) instability in both the moderately compressible and weakly compressible regimes. Rayleigh-Taylor mixing is an acceleration driven instability of a layer separating two fluids of distinct densities. For the two dimensional single mode case, we find that the dimensionless terminal velocities (and associated Froude numbers) are nearly constant over most of this region of parameter space, as the thermodynamic parameters describing the equation of state are varied. The phenomenological drag coefficient which occurs in the single mode buoyancy-drag equation is directly related to the terminal velocities and has a similar behavior. Pressure differences and interface shape, however, display significant dependence on the EOS parameters even for the weakly compressible flows. For three dimensional multimode mixing, we expect that density stratification rather than drag will provide the leading compressibility effect. We develop an analytical model to account for density stratification effects in multimode self-similar mixing. Our, theory is consistent with and extends numerically based conclusions developed earlier which also identify density stratification as the dominant compressibility effect for multimode three dimensional mixing. New simulations with Locally Grid Based Front Tracking Method compare Rayleigh-Taylor mixing rates for ideal fluids and for real fluids with experimental values for surface tension or mass diffusion. The simulated real fluid mixing rates agree with those measured experimentally. Comparison to theoretical predictions relating the mixing rate, the bubble width and the bubble height fluctuations based on bubble merger models shows similar agreement with experiment. The ideal fluid mixing rate is some 50% larger, providing an example of the sensitivity of the mixing rate to physical scale breaking interfacial phenomena; we also observe sensitivity to numerical scale breaking artifacts. Key Words: Rayleigh-Taylor instability, front racking method, surface tension, mass diffusion.

Liu, Xinfeng

297

Three transport phenomena in molecular crystals  

NASA Astrophysics Data System (ADS)

Modern spectroscopic techniques have moved beyond static structure determination, to studying the dynamics of molecular systems. I explore three areas of investigation into the transport phenomena in molecular crystals. The first section deals with a hydrogen tunneling reaction in the fluorene/acridine photosystem. A simple quantum mechanical model is developed that accurately models the main kinetic features of the reaction. This model relies on calculating Franck-Condon factors between normal modes of fluorene (including phonon modes), and a fictitious acceptor state which is chosen to appropriately represent an acceptor state with proper exothermicity. Both the temperature and pressure dependence are well fit. One area where the model fails is in predicting an increased kinetic sensitivity to pressure with increasing temperature. Instead, a simple and intuitive explanation is offered: the compressibility is most likely a function of temperature. The second section deals with spin diffusion in a deep trap excited triplet state spin system. Isotopic effects on the decay rates of two and three pulse echoes are systematically studied in benzene doped with pyrimidine. Upon full deuteration seven fold and four fold increases in echo decay time are observed for two pulse and three pulse echoes, respectively. When fit to the Hu Hartman model, the three pulse echo data yields anomalously low spin flip rates (tens of Hz) for the bulk nuclei. Typical bulk nuclei flip at tens of kHz. These data are interpreted as being characteristic of nuclear spins within the detuned sphere. Based on this assumption, reasonable hyperfine coupling constants are calculated for these near spins. The final section is a small step on a work in progress. We set out to measure the dispersion of TCB's vibron bands under pressure. Building on a technique developed by J. Schmidt, we attempt to measure the phosphorescence emission of the exciton after singlet to triplet absorption. Our lack of success is attributed to the high vulnerability of TCB crystals to strain induced defects.

Dernis, Mitchell Stephen

1997-07-01

298

CFD Analysis of Core Bypass Phenomena  

SciTech Connect

The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the sector grid can be set as a symmetry boundary

Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz

2010-03-01

299

CFD Analysis of Core Bypass Phenomena  

SciTech Connect

The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the one-twelfth grid can be set as a symmetry boundary

Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz

2009-11-01

300

Psychic phenomena following near-death experiences: An Australian study  

Microsoft Academic Search

This study examines the incidence of reports of psychic phenomena and associated beliefs both before and after the near-death experience (NDE). The near-death experiencers interviewed reported no more psychic phenomena before the NDE than the general population. There was a statistically significant increase following the NDE in the incidence of 14 of 15 items examined.

Cherie Sutherland

1989-01-01

301

Pendulum Phenomena and the Assessment of Scientific Inquiry Capabilities  

ERIC Educational Resources Information Center

Phenomena associated with the "pendulum" present numerous opportunities for assessing higher order human capabilities related to "scientific inquiry" and the "discovery" of natural law. This paper illustrates how systematic "assessment of scientific inquiry capabilities", using "pendulum" phenomena, can provide a useful tool for classroom teachers…

Zachos, Paul

2004-01-01

302

Observing Meteors, Comets, Supernovae and other transient Phenomena  

Microsoft Academic Search

Transient phenomena are short-lived astronomical events, unusual in a science in which time is more often measured in millennia than milliseconds. There is a fascination with transient phenomena, predictable or otherwise, that astronomers of all abilities share. In Meteors, Comets, Supernovae, Neil Bone gives guidelines for observers, including the best possible periods (months or years) to see seasonal but unpredictable

Neil Bone

1999-01-01

303

Irradiation induced phase and polarization phenomena in optical fibers  

Microsoft Academic Search

A theory is developed for evaluation of irradiation induced phase phenomena in optical fibers. The new optical method for control of various ionizing radiations is discussed. The special interest represents the potential ability for control of thermal neutrons and charged particles of low energies. The base of the method makes up the phenomena: the irradiation induced changes of elastic characteristics

F. N. Ignatiev

2003-01-01

304

Cold spray deposition: Significance of particle impact phenomena  

Microsoft Academic Search

A survey of particle impact phenomena is provided with a particular emphasis on impacts resulting in the so-called cold spray phenomenon, i.e., in a strong adherence of particles to the impacted surface. A classification of impact phenomena is made based on particle size and impact velocity. Impact features characteristic of cold sprays are compared with typical features of impacts occurring

Sergei Vladimirovich Klinkov; Vladimir Fedorovich Kosarev; Martin Rein

2005-01-01

305

Hindering Phenomena in Group Supervision: Implications for Practice  

Microsoft Academic Search

Although group supervision is practiced extensively, research on the subject remains scant. This study identified group supervision phenomena that hinder learning. Counseling and counseling psychology graduate students identified 61 group supervision experiences that they felt interfered with their learning. Then, 14 of the 49 original participants sorted the 61 phenomena on the basis of similarity. Hierarchical cluster analysis was used

Karen Chicca Enyedy; Ferdinand Arcinue; Neera Nijhawan Puri; John W. Carter; Rodney K. Goodyear; Michele A. Getzelman

2003-01-01

306

Field dependence, suggestibility and belief in paranormal phenomena  

Microsoft Academic Search

This paper examines the relationships between field dependence, suggestibility and belief in paranormal phenomena. In Experiment 1, 91 subjects underwent an hypnosis session to determine their suggestibility. They also completed a paranormal belief scale and a computer test of field dependence. It was shown that suggestibility and field dependence had positive and significant correlations with the belief in paranormal phenomena.

Andreas Hergovich

2003-01-01

307

Fourier-based spatial mapping of oscillatory phenomena in fungi  

Microsoft Academic Search

Microorganisms display a range of oscillatory phenomena that operate over different temporal scales. Fourier analysis provides a compact description of such oscillations in terms of their frequency, magnitude and phase. However, in the majority of studies there is no explicit consideration of the spatial organisation of the oscillation. Here we describe procedures and a software package to map oscillatory phenomena

M. D. Fricker; M. Tlalka; D. Bebber; S. Tagaki; S. C. Watkinson; P. R. Darrah

2007-01-01

308

Phenomena of liquid drop impact on solid and liquid surfaces  

Microsoft Academic Search

The fluid dynamic phenomena of liquid drop impact are described and reviewed. These phenomena include bouncing, spreading and splashing on solid surfaces, and bouncing, coalescence and splashing on liquid surfaces. Further, cavitation and the entrainment of gas into an impacted liquid may be observed. In order to distinguish properly between the results of different experiments different impact scenarios are discussed.

Martin Rein

1993-01-01

309

Individualization of the anisotropic phenomena of the imbalanced Nature  

NASA Astrophysics Data System (ADS)

What is an individual phenomenon of Nature? Where are the boundaries? Why it is considered as an individual phenomenon? etc. People cannot directly detect the "something isotropic." Sometimes we notice that there is a "black box." But on closer inspection, especially with new methods, the "black box" began to lighten. It seems that his "blackness" is the result of imperfect human sensors and interpretations, but not a phenomenon of Nature. Really people can identify only the anisotropic phenomena of Nature, but with the significant errors. Let's take a look at our home planet Earth. Where are the borders of our planet? It is may seem as the very simple question. People walk on the land and swim on the seas. This is the border on the surface of land and water. But what is about the dust? The dust is a part of the land, which is in the air. Weight of dust is very small compared to the weight of the planet. But it is the dust has formed valleys. Dust can rise very high above the planet's surface and even fly into the space. A similar situation is with the water. The bulk of the liquid water is in surface and underground waters. Water vapor is in the atmosphere. Atmospheric water is much less than on the earth and under the earth. But atmospheric water plays a huge role in the world and even extends into the space. Without a full accounting of dust and water impossible correctly describe the planet. But with considering the dust and water the planet is not solid-liquid ball. It is like "fuzzy blowball" with the boundaries that go to infinity. This "fuzziness" refers to gravity. The gravitational field does not end in the Lagrange points. This "fuzziness" illustrated by the electro-magnetic fields, etc. Our planet can be seen as a multidimensional anisotropic phenomenon of Nature. The anisotropy precisely is, and therefore is the gradient and movement. This phenomenon is clearly imbalanced because nothing ever repeats itself exactly, etc. The borders of any anisotropic imbalanced natural phenomenon can be determined with the precision which allow the sensors and methods of interpretation. The desire to identify the separate object in the imbalanced continuous Nature is the consequence of personalized thinking of people. In Nature is not exists any separate and independent phenomenon. In Nature are exist only the more or less concentrated anisotropy, which are constantly changing in the infinite continuity. Some references: Vladimir A Kontar, Federal GEOS Funding, US: 1. What is Imbalance of Nature? 2. What is the Imbalance of Water in Nature? 3. The Imbalance of Water in Nature as System 4. Axiomatic of the Imbalance of Nature and the Imbalance of Water in Nature 5. Water Management on the Verge of the Imbalanced Revolution 6. Control the Imbalance in Nature for Humanity Survival 7. Proof of the Imbalance of Nature in the Universe 8. Imbalanced Logic as the next level development of science Vladimir A. Kontar, Lyubov M. Shlafman, Federal GEOS Funding, US: 1. The relativity theory of the imbalance of water in nature 2. Redeployment as a Parameter to Measure the Imbalance of Water in Nature 4. Imbalance's Hypothesis for the Origin and Dynamics of Water on the Terrestrial Planets 5. Imbalance of Water and Carbon as Factors of the Global Climate Changes

Shlafman, L. M.; Kontar, V. A.

2013-05-01

310

Tunneling Phenomena in Mesoscopic Normal Junctions  

NASA Astrophysics Data System (ADS)

Single-electron tunneling effects are studied experimentally and theoretically in a system consisting of two normal ultra-small capacitance junctions in series. A Scanning Tunneling Microscope (STM) tip poised over a small conducting particle lodged in the surface oxide of a metallic substrate provides the physical realization of this system. We demonstrate for the first time, that incremental charging effects are important and observable, not only at cryogenic temperatures but also at room temperature, provided that conditions are such that thermal and quantum fluctuations do not destroy the correlation. With current technologies, STM-formed junctions are the only option allowing these phenomena to persist up to room temperature. At elevated temperatures it is particularly important to precisely control a variety of noise sources which can otherwise mimic or obscure the effect. Substrates and tips are fabricated of granular NbN. We find that dc magnetron sputtering of NbN thin films naturally promotes formation of small surface structures appropriate for a double junction system yielding single -electron effects at room temperature. Performing a semiclassical approximation, an analytic expression valid at finite temperature is derived for the current-voltage characteristic of the system. A number of expressions, useful in fitting experiment to theory are subsequently extracted from this result. The Coulomb blockade and Coulomb staircase (occasioned by incremental charging of the central island in a double capacitor system) were both clearly observed at room temperature. The Coulomb staircase observation provides decisive evidence that the blockade is not being caused by an oxide impurity effect, a gap in the density of states in the tip, or merely a lowering of the effective tunneling barrier with increasing bias voltage. Fits with the developed theory yield capacitances on the order of 10^{-18} F and tunneling resistances from 10 MOmega to 800 MOmega.. A study of the noise at room temperature indicates an enhancement of the shot noise at the current steps of the Coulomb staircase. A dependence of the overall noise on the derivative of the conductance is also observed.

Reeve, Mark Douglas

311

Magnetoresistive phenomena in nanoscale magnetic systems  

NASA Astrophysics Data System (ADS)

Nanomagnetic materials are playing an increasingly important role in modern technologies. A particular area of interest involves the interplay between magnetism and electric transport, i.e. magnetoresistive properties. Future generations of field sensors and memory elements will have to be on a length scale of a few nanometers or smaller. Magnetoresistive properties of such nanoscale objects exhibit novel features due to reduced dimensionality, complex surfaces and interfaces, and quantum effects. In this dissertation theoretical aspects of three such nanoscale magnetoresistive phenomena are discussed. Very narrow magnetic domain walls can strongly scatter electrons leading to an increased resistance. Specifically, this dissertation will cover the newly predicted effect of magnetic moment softening in magnetic nanocontacts or nanowires. Atomically thin domain walls in Ni exhibit a reduction, or softening, of the local magnetic moments due to the noncollinearity of the magnetization. This effect leads to a strong enhancement of the resistance of a domain wall. Magnetic tunnel junctions (MTJs) consist of two ferromagnetic electrodes separated by a thin layer of insulating material through which current can be carried by electron tunneling. The resistance of an MTJ depends on the relative orientation of the magnetization of the two ferromagnetic layers, an effect known as tunneling magnetoresistance (TMR). A first-principles analysis of CoFeB|MgO|CoFeB MTJs will be presented. Calculations reveal that it is energetically favorable for interstitial boron atoms to reside at the interface between the electrode and MgO tunneling barrier, which can be detrimental to the TMR effect. Anisotropic magnetoresistance (AMR) is the change in resistance of a ferromagnetic system as the orientation of the magnetization is altered. In this dissertation, the focus will be on AMR in the tunneling regime. Specifically we will present new theoretical results on tunneling AMR (TAMR) in two systems: (i) planar MTJs with CoFe electrodes and (ii) fully broken magnetic break junctions. In both cases electronic resonances in the electrodes lead to complex angular and bias dependence of the TAMR. The theoretical studies demonstrate the basic physical phenomenon behind recent experimental data.

Burton, John D.

312

Karstic Phenomena Susceptibility Map of MÉXICO  

NASA Astrophysics Data System (ADS)

Approximately 20% of the territory of México is underlain by karstifiable rocks, mostly limestones and in lesser proportions gypsum. The majority of these rocks are distributed along the eastern and southern Sierra Madre, the state of Chiapas and the Yucatán peninsula. Differences in geological structure, climate and geomorphic history have resulted in a great variety of karstic landscapes and types of forms. Several important population centers, including large cities with several million inhabitants and numerous smaller towns are built on karstic terrains and obtain their water supplies from karstic aquifers and/or dispose of their waste products on this type of terrain. Severe problems of waste disposal and aquifer contamination have occurred. Additionally, numerous instances of catastrophic collapse and formation of karstic sinkholes have been registered in the Mexican territory, which have affected many communities, roads and other infrastructure, and have even cost several lives. Lack of knowledge of the special characteristics of karstic terrains and their distribution has compounded these problems. As a first approach to these issues, the existing map of Mexican karst (Espinasa-Pereña, 2007) was modified according to the geotechnical classification proposed by Waltham & Fookes (2003). An important consideration taken into account is the difference in speed of development of karstic features depending on lithology, which makes karst developed in gypsum much more hazardous than limestone karst, and also the degree of soil coverage and the types of sinkholes developed on the cover. Also taken in consideration are the differences between karst developed in the Sierra Madre, with rocks highly deformed and fractured, and karst developed on the Yucatán peninsula with almost negligible deformation of the rocks. The resulting map will be useful to Civil Protection authorities as a tool in prognosticating possible affectations due to karstic phenomena. References: ESPINASA-PEREÑA, R., 2007, "El Karst de México", Mapa NA III 3, in Coll-Hurtado, A., Coord., "Nuevo Atlas Nacional de México", Instituto de Geografía, Universidad Nacional Autónoma de México. WALTHAM, A.C. and FOOKES, P.G., 2003, Engineering classification of karst ground conditions, Quarterly Journal of Engineering Geology and Hydrology, Vol. 36, pp. 101-118.

Espinasa-Pereña, R.

2013-05-01

313

Saving the Phenomena in Medieval Astronomy  

NASA Astrophysics Data System (ADS)

Aristotle's theory of motion is based on two principles: (1) all motion to either from the midpoint of the Earth, toward it, or around it, and (2) circular motion must proceed around an immovable point. On this view, the heavenly bodies are individual points of light carried around by a series of concentric spheres rotating at a constant pace around the midpoint of the Earth. But even in Aristotle's day, it was known that this theory had a great deal of difficulty accounting for planetary motion. Ptolemy's alternative was to introduce epicycles and eccentric orbits, thus denying Aristotle's view of natural motion. There was no doubt that Ptolemy's predictions were far better than Aristotle's. But for the medievals, Aristotle's theory made better intuitive sense. Moreover, Ptolemy's theory raised the question of how one sphere could pass through another. What to do? The solution of Moses Maimonides (1138-1204) was to say that it is not the job of the astronomer to tell us how things actually are but merely to propose a series of hypotheses that allow us to explain the relevant data. This view had obvious theological implications. If astronomy could explain planetary motion in an acceptable way, there was reason to believe that the order or structure of the heavens is what it is by necessity. This suggests that God did not exercise any degree of choice in making it that way. But if astronomy cannot explain planetary motion, the most reasonable explanation is that we are dealing with contingent phenomena rather than necessary ones. If there is contingency, there is reason to think God did exercise a degree of choice in making the heavens the way they are. A God who exercises choice is much closer to the God of Scripture. Although Galileo changed all of this, and paved the way for a vastly different view of astronomy, the answer to one set of questions raises a whole different set. In short, the heavenly motion still poses ultimate questions about God, existence, and the origin of the universe.

Seeskin, K.

2011-06-01

314

Solidification phenomena in metal matrix nanocomposites  

NASA Astrophysics Data System (ADS)

Nanoparticles in metal matrix nanocomposites (MMNCs) were shown to act as catalysts for nucleation of solidification of the matrix alloy, as well as to alter the intermetallic phase formation. These phenomena were studied in zinc, aluminum, and magnesium alloys. In all alloys studied, a refinement of the microstructure was seen with the addition of the nanoparticles. Various types of nanoparticles were used and had varying degrees of refinement. In a zinc alloy, AC43A, SiC, TiC, and Al2O3 gamma nanoparticles were all found to refine the alloy. Thermal analysis of bulk samples showed the onset of solidification at reduced undercoolings, indicating nucleation catalysis. Nucleation of the primary phase was also observed by employing the droplet emulsion technique (DET). DET results showed that the secondary phase nucleation was also catalyzed by the nanoparticles. Exploiting the nucleation catalysis of the nanoparticles and the associated grain refinement, a semi-solid casting (SSC) process was demonstrated in AC43A + SiC nanocomposites. This novel process successfully incorporated the strength enhancement of MMNCs and the casting quality benefits of SSC. This process required no additional processing steps or material handling typical of existing SSC processes. The nucleation catalysis of the nanoparticles was sufficient to create semi-solid slurries appropriate for SSC. Nanoparticle induced nucleation catalysis was also examined in a common aluminum alloy, A356, using the DET. All nanoparticles catalyzed nucleation of the primary Al phase. However, undercoolings varied depending on the nanoparticle identity and average diameter. The variation in undercoolings generally agreed with a modified lattice disregistry theory and the free growth theory. For nanoparticles with a small lattice spacing mismatch with the Al phase, undercoolings approached the size dependent free growth limit. Binary alloys of magnesium and zinc showed significant strength and ductility enhancements with the addition of 1.5 weight % SiC nanoparticles. Transmission electron microscope (TEM) study of the nanocomposite showed the MgZn2 phase among the nanoparticles and a reduction of the Mg 7Zn3 and Mg2Zn3 phases that were common in the monolithic samples. Thermal analysis supported this observed phase selection. The demonstrated nucleation catalysis and phase selection resulted in processing and property enhancement in the MMNCs.

de Cicco, Michael Peter

315

Domain specific phenomena at ferroelectric perovskite surfaces  

NASA Astrophysics Data System (ADS)

Ferroelectric compounds are the basis of traditional electronic ceramic devices. The ferroelectric response is being explored as components in emerging nanoscale devices. At these length scales, the fundamental aspects of atomic structure and reactions at ferroelectric surfaces are critical to a range of device applications. In this dissertation, Scanning Probe Microscopy was employed to study the domain specific phenomena at ferroelectric perovskite surfaces. The primary aim of these studies is to acquire a detailed understanding of polarization related processes at ferroelectric surfaces and to generate new insights into basic mechanisms behind them. Using a combination of scanning tunneling microscopy (STM), non-contact atomic force microscopy (nc-AFM), and low energy electron diffraction (LEED), surface structure and stability of BaTiO3 (001) was investigated. It is discovered that this surface adopts a family of reconstructions, each depending on thermo-chemical history. Surface reconstruction evolution with temperature and chemical potential of environments was understood through density function theoretical (DFT) calculations that predict the surface diagram with thermodynamically most favorable surface phases under varying conditions. Theoretical calculations were done by A. Kolpak and A. Rappe. Comparisons of the results from the calculations with the STM and nc-AFM observations were used to construct atomic models for the reconstructed surfaces. The relationship between atomic domain polarization and local surface interactions was studied with two approaches. Using piezoforce microscopy (PFM) and scanning surface potential microscopy (SSPM), the interaction between electron injection and ferroelectric lattice was investigated. The observed polarization reorientation through surface charging was further explored to control domain structure at the nano-meter scale. The effect of electron beam dosage, current, and voltage was quantified for PZT thin films. By coupling the capability of scanning probes and/or electron beams to control the domain polarization at the nanometer scale to the specificity of photochemical reactions on ferroelectric domains, nanostructures with magnetic properties were assembled at ferroelectric surfaces. Using SSPM, the effect of polarization orientation on CO2 adsorption was examined and quantified, leading to the discovery of a sticking coefficient difference by a factor of 4 for opposite domains in both BaTiO 3 and lead zirconate titanate (PZT) crystals. The differences were discussed in terms of the possible adsorption mechanisms at surfaces. The molecular adsorption mechanism was deduced with reference to temperature programmed desorption (TPD) measurements from M. He and J. Vohs and DFT calculations from A. Kolpak and A. Rappe.

Li, Dongbo

316

Fibre Optic Temperature Sensors Using Fluorescent Phenomena.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. A number of fibre optic sensors based on fluorescent phenomena using low cost electronic and optical filtering techniques, for temperature sensing applications are described and discussed. The initial device developed uses the absorption edge change of an optical glass to monitor changes in temperature with a second wavelength reference channel being generated from a fluorescent material, neodymium doped in glass. This device demonstrates the working of the self-referencing principle in a practical device tested over the temperature range of -60^circ C to 200^circC. This initial device was improved by incorporating a microprocessor and by modifying the processing electronic circuitry. An alternative probe was constructed which used a second fibre placed along-side the addressing fibre in contrast to the original device where the fibre is placed at the opposite end of the addressing fibre. A device based on the same principle but with different absorption glasses and a different fluorescent medium, crystalline ruby, was also examined. This device operated at a lower wavelength region compared to the infra -red working region of the first device. This work illustrated the need to make an appropriate choice of sensor absorption glass so that the cheaper indicator type LEDs, which operated at lower wavelengths, may be used. Ruby is a fluorescent material which is characterized by each emission wavelength having its own temperature characteristics. The integrated energy output over the complete emission spectrum is independent of temperature. This provided a means of generating a reference from the complete spectrum while a small frequency band gave a temperature dependent output. This characteristic of ruby was used to develop a temperature measuring device. A final system which utilises the temperature dependent decay-time emission properties of crystalline ruby was developed. In this case the ruby was excited by sinusoidally modulated light. This system employs a single indicator type green LED to excite the ruby sample and a single very sensitive silicon photodiode detector with an integral amplifier for low optical signal detection. Both of these components were inexpensive. The system yielded very high performance levels in terms of precision and resolution which has the potential for commercial exploitation. The different devices developed are compared and contrasted in the light of the commercial instruments on the market and other published data.

Selli, Raman Kumar

317

Present state of knowledge of the upper atmosphere: An assessment report  

NASA Technical Reports Server (NTRS)

A program of research, technology, and monitoring of the phenomena of the upper atmosphere, to provide for an understanding of and to maintain the chemical and physical integrity of the Earth's upper atmosphere was developed. NASA implemented a long-range upper atmospheric science program aimed at developing an organized, solid body of knowledge of upper atmospheric processes while providing, in the near term, assessments of potential effects of human activities on the atmosphere. The effects of chlorofluorocarbon (CFC) releases on stratospheric ozone were reported. Issues relating the current understanding of ozone predictions and trends and highlights recent and future anticipated developments that will improve our understanding of the system are summarized.

1984-01-01

318

Conceptual Framework to Enable Early Warning of Relevant Phenomena (Emerging Phenomena and Big Data)  

SciTech Connect

Graphs are commonly used to represent natural and man-made dynamic systems such as food webs, economic and social networks, gene regulation, and the internet. We describe a conceptual framework to enable early warning of relevant phenomena that is based on an artificial time-based, evolving network graph that can give rise to one or more recognizable structures. We propose to quantify the dynamics using the method of delays through Takens Theorem to produce another graph we call the Phase Graph. The Phase Graph enables us to quantify changes of the system that form a topology in phase space. Our proposed method is unique because it is based on dynamic system analysis that incorporates Takens Theorem, Graph Theory, and Franzosi-Pettini (F-P) theorem about topology and phase transitions. The F-P Theorem states that the necessary condition for phase transition is a change in the topology. By detecting a change in the topology that we represent as a set of M-order Phase Graphs, we conclude a corresponding change in the phase of the system. The onset of this phase change enables early warning of emerging relevant phenomena.

Schlicher, Bob G [ORNL; Abercrombie, Robert K [ORNL; Hively, Lee M [ORNL

2013-01-01

319

Atmospheric corrosion of lithium electrodes  

SciTech Connect

Atmospheric corrosion of lithium during lithium-cell assembly and the dry storage of cells prior to electrolyte fill has been found to initiate lithium corrosion pits and to form corrosion products. Scanning Electron Microscopy (SEM) was used to investigate lithium pitting and the white floccullent corrosion products. Electron Spectroscopy for Chemical Analysis (ESCA) and Auger spectroscopy in combination with X-ray diffraction were used to characterize lithium surfaces. Lithium surfaces with corrosion products were found to be high in carbonate content indicating the presence of lithium carbonate. Lithium electrodes dry stored in unfilled batteries were found to contain high concentration of lithium flouride a possible corrosion product from gaseous materials from the carbon monofluoride cathode. Future investigations of the corrosion phenomena will emphasize the effect of the corrosion products on the electrolyte and ultimate battery performance. The need to protect lithium electrodes from atmospheric exposure is commonly recognized to minimize corrosion induced by reaction with water, oxygen, carbon dioxide or nitrogen (1). Manufacturing facilities customarily limit the relative humidity to less than two percent. Electrodes that have been manufactured for use in lithium cells are typically stored in dry-argon containers. In spite of these precautions, lithium has been found to corrode over a long time period due to residual gases or slow diffusion of the same into storage containers. The purpose of this investigation was to determine the nature of the lithium corrosion.

Johnson, C.J.

1981-10-01

320

Solid State Laser Technology Development for Atmospheric Sensing Applications  

NASA Technical Reports Server (NTRS)

NASA atmospheric scientists are currently planning active remote sensing missions that will enable global monitoring of atmospheric ozone, water vapor, aerosols and clouds as well as global wind velocity. The measurements of these elements and parameters are important because of the effects they have on climate change, atmospheric chemistry and dynamics, atmospheric transport and, in general, the health of the planet. NASA will make use of Differential Absorption Lidar (DIAL) and backscatter lidar techniques for active remote sensing of molecular constituents and atmospheric phenomena from advanced high-altitude aircraft and space platforms. This paper provides an overview of NASA Langley Research Center's (LaRC's) development of advanced solid state lasers, harmonic generators, and wave mixing techniques aimed at providing the broad range of wavelengths necessary to meet measurement goals of NASA's Earth Science Enterprise.

Barnes, James C.

1998-01-01

321

Certain relativistic phenomena in crystal optics  

NASA Astrophysics Data System (ADS)

Relativistic unsteady phenomena are established for a crystalline medium with unaligned sets of permittivity and permeability principal axes, but incorporating a compounded uniaxiality about some nonprincipal direction. All effects originate from a suddenly activated, arbitrarily oriented, maintained line current conducted with a finite velocity v. Integral representations studied in another paper (Chee-Seng) are applied. The original coordinate system is subjected to a series of rotational and translational, scaled and unscaled transformations. No specific coordinate frame is strictly adhered to. Instead, it is often expedient and advantageous to exploit several reference frames simultaneously in the course of the analysis and interpretations. The electric field is directly related to a net scalar field ? involving another scalar ? and its complement ? which can be deduced from ? ? and ? are associated with two expanding, inclined ellipsoidal wavefronts ? and ? these are cocentered at the current origin and touch each other twice along the uniaxis. Elsewhere, ? leads ?. For a source current faster than ?:vt ? ext?, ??30 within a finite but growing ''ice-cream cone'' domain, its nontrivial composition being ?-1/2 inside ? and 2?-1/2 inside part of a tangent cone from the advancing current edge vt to, and terminating at, ? the function ? vanishes along such a tangent cone. Alternatively, for a source current slower than ?:vt? int?, if vt is avoided, ?>~0 everywhere, while ?=?-1/2 inside ? but vanishes identically outside ?. However, the crucial scalar field ? depends on three separate current-velocity regimes. Over a slow regime: vt? int?, ? is nontrivial inside ? wherein it is discontinuous across ?. Over an intermediate regime: vt ? int? ext?, ? takes four distinct forms on 12 adjacent domains bounded by ?, ? and a double-conical tangent surface linking vt to ?. But for a fast regime: vt? ext?, ? assumes six distinct forms on 18 adjacent domains bounded by ?, ? plus two double-conical tangent surfaces, convertexed at vt, to both ? and ?. Singularities are normally confined to these boundaries. Relative to a moving frame, ? is time-independent. Nevertheless, ? and, consequently, ? evolve unsteadily, principally because of transitions across the expanding ellipsoids ? and ? which also acquire a relative retreat from the current edge vt. An evolution scheme is discussed in detail. This produces, among other things, a steady state corollary which, in turn, covers ?erenkov radiation. A quadrical symmetry exists with respect to a family {Q?} of constant ?-surfaces. These are quadric surfaces cocentered at vt and having principal axes inclined to those of ? (and ?). Their interactions with ? are closely examined. If vt ? ext?, each Q? is a hyperboloid of two sheets which are asymptotic to the double-conical tangent surface connecting ? to vt; ? can become nontrivial on only one sheet, viz., that which is approached by ? as the latter retreats from vt; eventually, two permanent intersections, one following the other, occur along two expanding and travelling parallel plane circuits. But if vt ? int?, each Q? is an ellipsoid inside which ? initially evolves until an encounter occurs, first as a point contact which immediately grows into a plane circuit; as this traverses Q?, it expands and then contracts to a diametrically opposite point where contact breaks off. Finally, an elliptical axisymmetry about a principal direction of {Q?} is demonstrated. Corresponding behaviors hold in relation to ?.

Chee-Seng, Lim

1980-01-01

322

Mixed burden softening and melting phenomena  

NASA Astrophysics Data System (ADS)

The blast furnace (BF) will remain the major iron producing unit for the foreseeable future. The cohesive zone, where ferrous materials soften and melt, affects the productivity of the BF. This research was focused on expanding the current understanding of the mechanism of softening and melting of the ferrous materials. The other objective of this project was to examine the potential use of direct reduced iron (DRI) and hot briquetted iron (HBI) as the BF burden. The materials used in this study were DRI, HBI, lump iron ore and pellets. A wide variety of experimental procedures were employed to completely understand the process phenomena. The softening and melting (SM) experiments were conducted under load and X-Ray fluoroscopy was used to visualize the process. The results of these experiments were conducive in determining a suitable mechanism of softening and melting of the burden. For single burdens of DRI and HBI, softening occurred when metal began to melt. For mixed burdens of DRI and pellets/lump ore, the initial deformation was not affected by DRI; however DRI dominated as the temperature increased and melting occurred only when DRI melted. Melt dripping was observed at temperatures close to meltdown. A FactSage slag model was used to obtain the evolution of liquid with temperature. It was compared with the bed shrinkage which indicated that the most likely reason of the softening of the burden is the deformation of solid, phases, especially iron. The bulk SM experiments were interrupted at temperatures of interest and samples were examined for the morphological changes. These experiments were instrumental in studying the burden interaction at different stages during softening and melting of the burden. In addition, in separate experiments (without load), the melting structure of DRI/HBI samples was studied. The results of these experiments were expanded to include viscosity, surface energy and deformation rate calculations which were helpful in understanding the melt exudation phenomenon. The microstructure of the materials showed a transition from heterogeneous to homogenous state with increasing temperatures. The melt dripping was predominantly observed in olivine fluxed pellets. The exuded slag was primarily composed of alkali rich phase which was found least viscous amongst all types of slags present in this system. The viscosity of the liquid and the structure of metallic shell facilitated the melt exudation from the burden. In addition, the liquid filled the iron shell and coarsened its structure. Based on the metallographic examination of the samples a mechanism of burden interaction was proposed. The burden interaction is followed by melt dripping and melting of the burden. The melting onset temperatures were estimated from the isothermal section modeling of the phase diagrams and liquid mass fraction calculations obtained using FactSage software and databases. The phase diagrams supported the experimental observations such as non-melting of olivine particles in the olivine fluxed pellets and slag homogenization at 1300°C in the basic pellets. Addition of magnesia in lieu of lime was found to provide beneficial impact, in particular on the rate of liquid evolution at high temperature. Effect of alkali, even in small amounts, was deleterious for high temperature properties, especially in terms of early melt onset and lowering of the viscosity of the slag formed.

Kaushik, Pallav

323

Synchro-ballistic recording of detonation phenomena  

NASA Astrophysics Data System (ADS)

Synchro-ballistic use of rotating-mirror streak cameras allows for detailed recording of high-speed events of known velocity and direction. After an introduction to the synchro-ballistic technique, this paper details two diverse applications of the technique as applied in the field of high-explosives research. In the first series of experiments detonation-front shape is recorded as the arriving detonation shock wave tilts an obliquely mounted mirror, causing reflected light to be deflected from the imaging lens. These tests were conducted for the purpose of calibrating and confirming the asymptotic detonation shock dynamics (DSD) theory of Bdzil and Stewart. The phase velocities of the events range from ten to thirty millimeters per microsecond. Optical magnification is set for optimal use of the film's spatial dimension and the phase velocity is adjusted to provide synchronization at the camera's maximum writing speed. Initial calibration of the technique is undertaken using a cylindrical HE geometry over a range of charge diameters and of sufficient length-to- diameter ratio to insure a stable detonation wave. The final experiment utilizes an arc-shaped explosive charge, resulting in an asymmetric denotation-front record. The second series of experiments consists of photographing a shaped-charge jet having a velocity range of two to nine millimeters per microsecond. To accommodate the range of velocities it is necessary to fire several tests, each synchronized to a different section of the jet. The experimental apparatus consists of a vacuum chamber to preclude atmospheric ablation of the jet tip with shocked-argon back lighting to produce a shadow-graph image.

Critchfield, Robert R.; Asay, Blaine W.; Bdzil, John B.; Davis, William C.; Ferm, Eric N.; Idar, Deanne J.

1997-12-01

324

On the prediction of flooding and associated phenomena  

SciTech Connect

Of particular importance is the countercurrent flow limitation phenomena (flooding) during a postulated loss-of-coolant accident of a pressurized water reactor or a boiling water reactor. A substantial number of studies have been reported in the literature on the basic mechanisms of flooding. Many of these studies were experimental, and only a few analytical models were presented. Despite these efforts, our understanding of the flooding phenomena and its mechanisms is inadequate. In this paper, the flooding phenomena are predicted by a multifluid model developed by Sami, and the numerical results are compared with available experimental ones.

Sami, S.M.

1989-01-01

325

Analytical investigation of critical phenomena in MHD power generators  

NASA Technical Reports Server (NTRS)

Critical phenomena in the Arnold Engineering Development Center (AEDC) High Performance Demonstration Experiment (HPDE) and the U.S. U-25 Experiment, are analyzed. The performance of a NASA specified 500 MW(th) flow train is analyzed. Critical phenomena analyzed include: Hall voltage overshoots; optimal load schedules; parametric dependence of the electrode voltage drops; boundary layer behavior; near electrode phenomena with finite electrode segmentation; current distribution in the end regions; scale up rules; optimum Mach number distribution; and the effects of alternative cross sectional shapes.

1980-01-01

326

The refraction in the atmospheric surface layer  

NASA Astrophysics Data System (ADS)

An analytical theory of refraction for the atmospheric layer is developed in which the vertical profiles of the refraction are calculated based on the theory of Monin and Obukhov (1954). A similarity parameter is found for the refraction in such conditions. These results are used to clarify the idea of Moroz (1976) that the nearness of the horizon as recorded by the automatic stations on the surface of Venus can be explained by the decrease in the temperature at the very surface of the planet. In addition, several other optical phenomena which occur near the surface of the earth are examined.

Golitsyn, G. S.

1982-12-01

327

Introduction to the Atmosphere: Atmospheric Composition  

NSDL National Science Digital Library

This textual resource describes the eleven most abundant gases found in the Earth's lower atmosphere. A table lists these gases and their corresponding percent composition. For example, Nitrogen makes up approximately 78% of the atmosphere. A glossary of key terms is also available.

Pidwirny, Michael

328

Low energy electron collision parameters for modeling auroral/dayglow phenomena  

NASA Astrophysics Data System (ADS)

From the tenuous atmospheres of Pluto and Triton to the higher pressure atmospheres of Earth and Titan, electron-collisions with molecular nitrogen continue to warrant attention. The airglow emissions of N2 from the atmospheres of Earth and planetary satellites have been extensively observed. Accurate, consistent cross section data is a necessity for accurate models of how upper atmospheres behave. This enables determinations of solar energy inputs and atmospheric expansion and contraction, which influences satellite orbits for instance. Recent work by Lean et al. [1], Stevens et al. [2], and Kato et al. [3] appear to substantiate our e^-+N2 excitation and emission work (e.g., Johnson et al. [4], Malone et al. [5], Young et al. [6] and references therein). Recently, we have focused on the near-threshold-to-peak region of N2 with the goal of providing low energy collision parameters of the X^1?g^+(0)--A^3?u^+, B^3?g, W^3?u, B^'3?u^-, a^'1?u^-, a^1?g, w^1?u, C^3?u, and E^3?g^+ transitions for modeling auroral and dayglow phenomena in these N2-rich atmospheres. The Lyman-Birge-Hopfield (LBH) emissions, from a^1?g(v^')--X^1?g^+(v^'') transitions, are `bellwether' measurements for diurnal Terrestrial Space Weather variations [7]. However, near-threshold cross section data is still lacking for the a^1?g state, as well as the `slow-cascade' a^'1?u^- and w^1?u contributors to LBH emissions. In addition, Vegard-Kaplan (VK) emissions, from the A^3?u^+(v^')--X^1?g^+(v^'') transitions, recently observed in Titan's thermosphere [2], require further improved monoenergetic laboratory measurements. New electron energy-loss measurements, along with direct excitation (integral) cross sections, are presented for excitation of the lower states of N2, with finely-spaced impact energy increments in the threshold-to-peak region. Our recent work, including vibrationally resolved excitation, addresses these atmospheric data needs.[4pt] [1] Lean et al., 2011, JGR, 116, A01102. ,[4] Johnson et al., 2005, JGR, 110, A11311. [2] Stevens et al., 2011, JGR, 116, A05304. [5] Malone et al., 2009, J. Phys. B, 42, 135201. [3] Kato et al., 2010, PRA, 81, 042717. ;;, [6] Young et al., 2010, J. Phys. B, 43, 135201. [7] Ajello et al., 2011, UV Molecular Spectroscopy from Electron Impact for Applications to Planetary Atmospheres and Astrophysics, Book Chapter 28, published in ``Charged Particle and Photon Interactions with Matter'' Recent Advances, Applications, and Interfaces-Eds., Hatano et al., Taylor & Francis, Boca Raton, FL.

Malone, Charles P.

2011-11-01

329

High-Explosive Field Tests, Explosion Phenomena and Environmental Impacts.  

National Technical Information Service (NTIS)

Methodologies are formulated to predict to magnitudes of high-explosive explosions phenomena for various high-explosive charge sizes and configurations and to relate these magnitudes to impacts on the natural physical and biological environment and on hum...

K. E. Gould

1981-01-01

330

Monitoring of Large Phenomena in Developing Countries Through Satellite Imagery.  

National Technical Information Service (NTIS)

Inter-annual comparisons between satellite images showing the effects of slowly evolving phenomena such as forest degradation or desert spreading, and intra-annual comparisons between images showing the flooding conditions over large areas are discussed. ...

L. Guyot

1986-01-01

331

INVESTIGATION INTO BIOFOULING PHENOMENA IN FINE PORE AERATION DEVICES  

EPA Science Inventory

Microbiologically-based procedures were used to describe biofouling phenomena on fine pore aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. ine pore diffusers were obtained from five municipal wastewate...

332

INVESTIGATIONS INTO BIOFOULING PHENOMENA IN FINE PORE AERATION DEVICES  

EPA Science Inventory

Microbiologically-based procedures were used to describe biofouling phenomena on fine pore aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. Fine pore diffusers were obtained from five municipal wastewa...

333

Investigations into Biofouling Phenomena in Fine Pore Aeration Devices.  

National Technical Information Service (NTIS)

Microbiologically-based procedures were used to describe biofouling phenomena on fine pore aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. Fine pore diffusers were obtained fro...

W. Jansen J. W. Costerton H. Melcer

1994-01-01

334

Depicting fire and other gaseous phenomena using diffusion processes  

Microsoft Academic Search

Developing a visually convincing model of fire, smoke, and othergaseousphenomenaisamongthemostdifficult andattractive problems in computer graphics. We have created new methods of animating a wide range of gaseous phenomena, including the particularlysubtleproblemofmodelling\\

Jos Stam; Eugene Fiume

1995-01-01

335

Time-Variable Phenomena in the Jovian System.  

National Technical Information Service (NTIS)

The current state of knowledge of dynamic processes in the Jovian system is assessed and summaries are provided of both theoretical and observational foundations upon which future research might be based. There are three sections: satellite phenomena and ...

M. J. S. Belton R. A. West J. Rahe M. Pereyda

1989-01-01

336

Unilateral autoscopic phenomena as a lateralizing sign in focal epilepsy.  

PubMed

Positive autoscopic phenomena - autoscopy, heautoscopy and out-of-body experience - may occur in a variety of diseases and also in physiological conditions. They are a rare but probably underreported phenomenon in focal epilepsies. Here, we investigate whether ictal lateralized autoscopic phenomena give lateralizing information about the underlying epileptic focus. We present the cases of seven patients from our center who experienced ictal lateralized autoscopic phenomena and analyzed their focus lateralization and localization of the underlying brain lesion. In addition, we reviewed seven cases published in German and English language literature. In the total group of 14 patients with ictal lateralized autoscopic phenomena, 12 (85.7%) of them had a well-defined epileptic focus contralateral to the side of the autoscopic appearance. Therefore, the data point to an association between ictal lateralized autoscopy and contralateral epileptic focus. PMID:22377330

Hoepner, Robert; Labudda, Kirsten; Hoppe, Matthias; Schoendienst, Martin; Schulz, Reinhard; Tomka-Hoffmeister, Maria; Woermann, Friedrich G; Ebner, Alois; Bien, Christian G; Brandt, Christian

2012-03-01

337

Measurement of Phase Distribution Phenomena in a Triangular Conduit.  

National Technical Information Service (NTIS)

Two-phase (air/water) measurements of phase distribution phenomena were made in a triangular test section. These measurements included the lateral void fraction distribution and the velocity profile of the liquid phase. In addition, measurements of the de...

S. Sim R. T. Lahey

1983-01-01

338

Euromech 160 on Periodic Flow and Wake Phenomena  

NASA Astrophysics Data System (ADS)

Several areas of periodic flow and wake phenomena are addressed including vortex shedding, oscillator model theory, unsteady pressure, velocity fields, vortex formation, bluff body wakes, and wind induced vibrations.

339

Ultrasonic Studies of Liquid/Solid Seismoacoustic Wave Phenomena.  

National Technical Information Service (NTIS)

New ultrasonic modeling findings are presented contributing to ten fundamental problems related to low-frequency seismoacoustic wave phenomena resulting from the interaction of underwater acoustic waves with heterogeneous elastic boundaries such as the ic...

J. R. Chamuel

1994-01-01

340

Sub-photosphere to Solar Atmosphere Connection  

NASA Astrophysics Data System (ADS)

Magnetic fields extend from the solar interior through the atmosphere. The formation and evolution of active regions can be studied by measuring subsurface flows with local helioseismology. The emergence of magnetic flux from the solar convection zone is associated with acoustic perturbation signatures. In near-surface layers, the average dynamics can be determined for emerging regions. MHD simulations of the emergence of a twisted flux tube show how magnetic twist and free energy are transported from the interior into the corona and the dynamic signatures associated with such transport in the photospheric and sub-photospheric layers. The subsurface twisted flux tube does not emerge into the corona as a whole in emerging active regions. Shear flows at the polarity inversion line and coherent vortical motions in the subsurface flux tubes are the major means by which twist is transported into the corona, leading to the formation of sigmoid-shaped coronal magnetic fields capable of driving solar eruptions. The transport of twist can be followed from the interior by using the kinetic helicity of subsurface flows as a proxy of magnetic helicity; this quantity holds great promise for improving the understanding of eruptive phenomena. Waves are not only vital for studying the link between the solar interior and the surface but for linking the photosphere with the corona as well. Acoustic waves that propagate from the surface into the magnetically structured, dynamic atmosphere undergo mode conversion and refraction. These effects enable atmospheric seismology to determine the topography of magnetic canopies in the solar atmosphere. Inclined magnetic fields lower the cut-off frequency so that low frequency waves can leak into the outer atmosphere. Recent high resolution, high cadence observations of waves and oscillations in the solar atmosphere, have lead to a renewed interest in the potential role of waves as a heating mechanism. In light of their potential contribution to the heating of the solar atmosphere, some of the recent observations of waves and oscillations and ongoing modelling efforts are reviewed.

Komm, Rudolf; De Moortel, Ineke; Fan, Yuhong; Ilonidis, Stathis; Steiner, Oskar

2013-10-01

341

Nuclear chromodynamics: Novel nuclear phenomena predicted by QCD  

NASA Astrophysics Data System (ADS)

With the acceptance of QCD as the fundamental theory of strong interactions, one of the basic problems in the analysis of nuclear phenomena became how to consistently account for the effects of the underlying quark/gluon structure of nucleons and nuclei. Besides providing more detailed understanding of conventional nuclear physics, QCD may also point to novel phenomena accessible by new or upgraded nuclear experimental facilities. We review several interesting applications of QCD to nuclear physics.

Bakker, Bernard L. G.; Ji, Chueng-Ryong

2014-01-01

342

Search for new phenomena in the CDF top quark sample  

SciTech Connect

We present recent results from CDF in the search for new phenomena appearing in the top quark samples. These results use data from p{bar p} collisions at {radical}s = 1.96 TeV corresponding to an integrated luminosity ranging from 195 pb{sup -1} to 760 pb{sup -1}. No deviations are observed from the Standard Model expectations, so upper limits on the size of possible new phenomena are set.

Lannon, Kevin; /Ohio State U.

2006-10-01

343

Modeling of transient flow phenomena in continuous casting of steel  

Microsoft Academic Search

This paper describes initial efforts to develop and apply 3D finite-difference models to simulate transient flow in the mold. These transient flow phenomena include flow pattern oscillations caused by sudden changes in nozzle inlet conditions and rapid fluctuations in the molten steel?flux interface level at the top surface of the mold. The flow model incorporates interactions with other transport phenomena,

X. Huang; B. G. Thomas

1998-01-01

344

Multiscale phenomena in the near-Earth magnetosphere  

Microsoft Academic Search

Several studies on the scaling properties of the near-Earth magnetosphere and auroral phenomena are reviewed. These studies employ modern analysis techniques that include fractal, multifractal, wavelet, wavelet bicoherence, and sign-singularity analyses as well as cellular automaton simulations of sandpile and avalanches. The results provide strong evidence for the multiscale, cross-scale coupling, and reorganization nature of auroral and magnetospheric phenomena, suggesting

A. T. Y Lui

2002-01-01

345

Department of Energy Natural Phenomena Hazards Mitigation Program  

SciTech Connect

This paper will present a summary of past and present accomplishments of the Natural Phenomena Hazards Program that has been ongoing at Lawrence Livermore National Laboratory since 1975. The Natural Phenomena covered includes earthquake; winds, hurricanes, and tornadoes; flooding and precipitation; lightning; and volcanic events. The work is organized into four major areas (1) Policy, requirements, standards, and guidance (2) Technical support, research development, (3) Technology transfer, and (4) Oversight.

Murray, R.C.

1993-09-01

346

Model conception of quantum phenomena: logical structure and investigation methods  

Microsoft Academic Search

One can construct the model conception of quantum phenomena (MCQP) which\\u000arelates to the axiomatic conception of quantum phenomena (ACQP), (i.e. to the\\u000aconventional quantum mechanics) in the same way, as the statistical physics\\u000arelates to thermodynamics. Such a possibility is based on a new conception of\\u000ageometry, which admits one to construct such a deterministic space-time\\u000ageometry, where motion

Yuri A. Rylov

2003-01-01

347

Atmospheric Science Experiment for Mars: ATMIS for the Netlander 2005 Mission  

NASA Technical Reports Server (NTRS)

ATMIS (Atmospheric and Meteorological Instrumentation System) is a versatile suite of atmospheric instrumentation to be accommodated onboard the Netlander Mission slated for launch in 2005. Four Netlanders are planned to form a geophysical measurement network on the surface of Mars. The atmospheric sciences are among the scientific disciplines benefiting most of the network concept. The goal of the ATMIS instrument is to provide new data on the atmospheric vertical structure, regional and global circulation phenomena, the Martian Planetary Boundary Layer (PBL) and atmosphere-surface interactions, dust storm triggering mechanisms, as well as the climatological cycles of H2O, dust and CO2. To reach the goal of characterization of a number of phenomena exhibiting both spatial and temporal variations, simultaneous observations of multiple variables at spatially displaced sites Deforming a network D are required. The in situ observations made by the ATMIS sensors will be supported by extensive modeling efforts. Additional information is contained in the original extended abstract.

Harri, A.-M.; Siili, T.; Angrilli, A.; Calcutt, S.; Crisp, D.; Larsen, S.; Polkko, J.; Pommereau, J.-P.; Malique, C.; Tillman, J. E.

1999-01-01

348

National Oceanic and Atmospheric Administration : Research Homepage  

NSDL National Science Digital Library

National Oceanic and Atmospheric Administration (NOAA) Research, conducted primarily through the NOAA Office of Oceanic and Atmospheric Research, drives the NOAA environmental products and services that protect life and property and promote sustainable economic growth. Research, conducted by in-house laboratories and by extramural programs, focuses on enhancing understanding of the environmental phenomena such as tornadoes, hurricanes, climate variability, solar flares, changes in the ozone, El Nino/La Nina events, fisheries productivity, ocean currents, deep sea thermal vents, and coastal ecosystem health. NOAA research also develops innovative technologies and observing systems. This clearinghouse website contains an explanation of various types of research conducted by NOAA. Users can access hot research topics, NOAA products and research organizations. This site also contains image galleries and photo albums chronicling NOAA research.

2003-01-01

349

Atmospheric deposition to high-elevation forests  

SciTech Connect

Three important phenomena characterize atmospheric deposition to high-elevation forests: (1) multiple deposition mechanisms (wet, dry, and cloud deposition), (2) high rates of deposition, and (3) high spatial variability. The high rates of deposition are caused by changes in meteorological conditions with elevation, especially increasing wind speed and cloud immersion frequency. The high spatial variability of deposition is a result of the regulation of cloud and dry deposition rates by microclimatic and canopy structure conditions, which can be extremely heterogeneous in mountain landscapes. Spruce-fir forests are often [open quotes]hot spots[close quotes] of deposition when viewed in a landscape or regional context because of their elevation, exposure, and evergreen canopy. In this talk we will consider atmospheric depositions to high-elevation forests in both the northeastern and southeastern U.S., using field data and geographic information systems to illustrate deposition patterns.

Lovett, G.M.; Weathers, K.C.; Lindberg, S.E. (Institute of Ecosystem Studies, Millbrook, NY (United States) Oak Ridge National Lab., TN (United States))

1994-06-01

350

Detecting psychological phenomena: taking bottom-up research seriously.  

PubMed

For more than 50 years, psychology has been dominated by a top-down research strategy in which a simplistic account of the hypothetico-deductive method is paired with null hypothesis testing in order to test hypotheses and theories. As a consequence of this focus on testing, psychologists have failed to pay sufficient attention to a complementary, bottom-up research strategy in which data-to-theory research is properly pursued.This bottom-up strategy has 2 primary aspects: the detection of phenomena, mostly in the form of empirical generalizations, and the subsequent understanding of those phenomena through the abductive generation of explanatory theories. This article provides a methodologically informative account of phenomena detection with reference to psychology. It begins by presenting the important distinctions between data, phenomena, and theory. It then identifies a number of different methodological strategies that are used to identify empirical phenomena. Thereafter, it discusses aspects of the nature of science that are prompted by a consideration of the distinction between data, phenomena, and explanatory theory. Taken together, these considerations press for significant changes in the way we think about and practice psychological research. The adoption of these changes would help psychology correct a number of its major current research deficiencies. PMID:23858950

Haig, Brian D

2013-01-01

351

Light flash phenomena induced by HzE particles  

NASA Technical Reports Server (NTRS)

Astronauts and Apollo and Skylab missions have reported observing a variety of visual phenomena when their eyes are closed and adapted to darkness. These phenomena have been collectively labelled as light flashes. Visual phenomena which are similar in appearance to those observed in space have been demonstrated at the number of accelerator facilities by expressing the eyes of human subjects to beams of various types of radiation. In some laboratory experiments Cerenkov radiation was found to be the basis for the flashes observed while in other experiments Cerenkov radiation could apparently be ruled out. Experiments that differentiate between Cerenkov radiation and other possible mechanisms for inducing visual phenomena was then compared. The phenomena obtained in the presence and absence of Cerenkov radiation were designed and conducted. A new mechanism proposed to explain the visual phenomena observed by Skylab astronauts as they passed through the South Atlantic Anomaly, namely nuclear interactions in and near the sensitive layer of the retina, is covered. Also some studies to search for similar transient effects of space radiation on sensors and microcomputer memories are described.

Mcnulty, P. J.; Pease, V. P.

1980-01-01

352

Stellar atmospheric structural patterns  

NASA Technical Reports Server (NTRS)

The thermodynamics of stellar atmospheres is discussed. Particular attention is given to the relation between theoretical modeling and empirical evidence. The characteristics of distinctive atmospheric regions and their radical structures are discussed.

Thomas, R. N.

1983-01-01

353

Atmospheric Transport of Radionuclides  

SciTech Connect

The purpose of atmospheric transport and diffusion calculations is to provide estimates of concentration and surface deposition from routine and accidental releases of pollutants to the atmosphere. This paper discusses this topic.

Crawford, T.V.

2003-03-03

354

Atmospheric Chemistry (Program Description)  

NSF Publications Database

... model the concentration and distribution of gases and aerosols in the lower and middle atmosphere ... trace gases and aerosols; the aqueous-phase atmospheric chemistry; the transport of gases and ...

355

Exploring Hot Neptune Atmospheres  

Microsoft Academic Search

The first transiting 'hot Neptune'' GJ 436b inhabits an entirely new region of phase space for extrasolar planetary atmospheres. This relatively cool, low-mass object should be the first transiting extrasolar planet to sport a methane-rich atmosphere. Like Uranus and Neptune it may also have an atmosphere highly enriched in heavy elements. Our experience with the complex atmospheres of the known

Jonathan Fortney; Mark Marley; Didier Saumon

2008-01-01

356

PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media  

NASA Astrophysics Data System (ADS)

Proton transport phenomena are of paramount importance for acid-base chemistry, energy transduction in biological organisms, corrosion processes, and energy conversion in electrochemical systems such as polymer electrolyte fuel cells. The relevance for such a plethora of materials and systems, and the ever-lasting fascination with the highly concerted nature of underlying processes drive research across disciplines in chemistry, biology, physics and chemical engineering. A proton never travels alone. Proton motion is strongly correlated with its environment, usually comprised of an electrolyte and a solid or soft host material. For the transport in nature's most benign proton solvent and shuttle, water that is, insights from ab initio simulations, matured over the last 15 years, have furnished molecular details of the structural diffusion mechanism of protons. Excess proton movement in water consists of sequences of Eigen-Zundel-Eigen transitions, triggered by hydrogen bond breaking and making in the surrounding water network. Nowadays, there is little debate about the validity of this mechanism in water, which bears a stunning resemblance to the basic mechanistic picture put forward by de Grotthuss in 1806. While strong coupling of an excess proton with degrees of freedom of solvent and host materials facilitates proton motion, this coupling also creates negative synergies. In general, proton mobility in biomaterials and electrochemical proton conducting media is highly sensitive to the abundance and structure of the proton solvent. In polymer electrolyte membranes, in which protons are bound to move in nano-sized water-channels, evaporation of water or local membrane dehydration due to electro-osmotic coupling are well-known phenomena that could dramatically diminish proton conductivity. Contributions in this special issue address various vital aspects of the concerted nature of proton motion and they elucidate important structural and dynamic effects of solvent, charge-bearing species at interfaces and porous host materials on proton transport properties. As a common thread, articles in this special issue contribute to understanding the functionality provided by complex materials, beyond hydrogen bond fluctuations in water. The first group of articles (Smirnov et al, Henry et al, Medvedev and Stuchebrukhov) elucidates various aspects of the impact of local structural fluctuations, hydrogen bonding and long-range electrostatic forces on proton transfer across and at the surface of mitochondrial membranes. The second group of articles (Ilhan and Spohr, Allahyarov et al and Idupulapati et al) employ molecular dynamics simulations to rationalize vital dependencies of proton transport mechanisms in aqueous-based polymer electrolyte membranes on the nanoporous, phase-separated ionomer morphology, and on the level of hydration. The articles by Gebel et al, Boillat et al, and Aleksandrova et al employ small angle neutron scattering, neutron radiography, and electrochemical atomic force microscopy, respectively, to obtain detailed insights into the kinetics of water sorption, water distribution, water transport properties, as well as spatial maps of proton conductivity in fuel cell membranes. The contribution of Paschos et al provides a comprehensive review of phosphate-based solid state protonic conductors for intermediate temperature fuel cells. The topic of proton conductive materials for high-temperature, water-free operation of fuel cells is continued in the article of Verbraeken et al which addresses synthesis and characterization of a proton conducting perovskite. The guest editor wishes to acknowledge and thank all contributing authors for their commitment to this special issue. Moreover, I would like to thank the staff at IOP Publishing for coordinating submission and refereeing processes. Finally, for the readers, I hope that this special issue will be a valuable and stimulating source of insights into the versatile and eminently important field of transport phenomena in proton conducting media. Complex dynamics of f

Eikerling, Michael

2011-06-01

357

Atmospheric Visualization Collection  

NSDL National Science Digital Library

The intent of the Atmospheric Visualization Collection (AVC) is to enhance physical science education and research through visualization of atmospheric data. This collection includes an archive of atmospheric data images and educational material based on these images. By utilizing collaborative digital library tools, a growing user community assists in the development of this collection.

Klaus, Christopher

2002-10-08

358

Computational Atmospheric Science  

NSDL National Science Digital Library

The goal of this online instructional workshop is to introduce participants to the theories and applications of atmospheric science computer modeling, specifically ozone formation and reactions in the atmosphere. Upon completion of the course, participants should understand the fundamental principles of ozone formation in the atmosphere and be able to understand and use numerical and computational science methods to study ozone science.

The Shodor Education Foundation, Inc.

359

Nonisothermal Pluto atmosphere models  

Microsoft Academic Search

The present thermal profile calculation for a Pluto atmosphere model characterized by a high number fraction of CH4 molecules encompasses atmospheric heating by solar UV flux absorption and conductive transport cooling to the surface of Pluto. The stellar occultation curve predicted for an atmosphere of several-microbar surface pressures (which entail the existence of a substantial temperature gradient close to the

W. B. Hubbard; R. V. Yelle; J. I. Lunine

1990-01-01

360

Nonisothermal Pluto atmosphere models  

SciTech Connect

The present thermal profile calculation for a Pluto atmosphere model characterized by a high number fraction of CH4 molecules encompasses atmospheric heating by solar UV flux absorption and conductive transport cooling to the surface of Pluto. The stellar occultation curve predicted for an atmosphere of several-microbar surface pressures (which entail the existence of a substantial temperature gradient close to the surface) agrees with observations and implies that the normal and tangential optical depth of the atmosphere is almost negligible. The minimum period for atmospheric methane depletion is calculated to be 30 years. 29 refs.

Hubbard, W.B.; Yelle, R.V.; Lunine, J.I. (Arizona Univ., Tucson (USA))

1990-03-01

361

The effects of meteoroids on the Earth atmosphere  

NASA Astrophysics Data System (ADS)

Each year 108 kg of extraterrestrial material is intercepted by the Earth. The fate of entering meteoroids in atmosphere is determined by their size, velocity and material properties. The range of meteoroids entering the Earth is extremely large; their masses varying from about 10-18 g up to asteroid-class impactors ( 1015 kg). Cosmic bodies entering the Earth' atmosphere lose a part of their mass or even the total mass during the interaction with the atmosphere. Material from ablation of small-sized meteors (roughly ¡0.01-1 cm) is mostly deposited between 130 and 70 km altitudes. Larger bodies (up to meter sizes) penetrate deeper into the atmosphere (down to 20 km altitude). Meteoroids larger about Tunguska-sized ( 100 m, 109 kg) ones lose only small part of their mass and energy during their passage through the Earth's atmosphere. The chemistry, composition and thermal structure of the atmosphere can be modified by an influx of material from outside. Ionized and luminous areas appear due to meteoroid interaction with the atmosphere. Meteor spectra confirm appearance of Fe, Si, Mg, H, Na, Ca, Ni, Mn, Cr, Al, Ti, CN, FeO, AlO, MgO, OH due to ablation. Meteors are sometimes considered as the source of organic material deposited into the atmosphere during ablation. Meteor phenomena can contribute as a source of nitric oxides in the mesosphere. Meteoric material is involved into the atmospheric chemistry. The ablation of meteoroids in the Earth's atmosphere gives rise to layers of metal atoms between 80 and 110 km that are global in extent. Dust particles in the atmosphere can originate from meteoroid fragmentation, from the recondensation of ablated meteor vapor and from ablated remnants. Small mineral grains provide the major source of condensation nuclei of stratospheric aerosol formation and may be also a constitutent of the global stratospheric aerosol layer. The evidence for extraplanetary material in the atmosphere will be reviewed.

Popova, Olga

362

Mechanisms for the atmospheric corrosion of carbonate stone  

SciTech Connect

The physical and chemical phenomena responsible for the atmospheric corrosion of carbonate stone are presented. Corrosion product formation, morphology, and chemical makeup are discussed in the context of calcium-containing minerals and other crystalline structures that thermodynamics and kinetics suggest are likely to be present. Formation pathways for the minerals most often reported to occur in carbonate corrosion layers are shown in schematic diagrams. The dominant corrosion products are sulfates and oxalates, the former resulting from interactions with atmospheric sulfur dioxide or sulfate ions, the latter from oxalate secretions from the biological organisms. present (and perhaps to some extent from oxalate deposited from the atmosphere). The degradation processes are enhanced by the catalytic action of transition metal ions present in the stone and of soot deposited from the atmosphere.

Graedel, T.E.

2000-03-01

363

An Atmospheric Science Observing System Simulation Experiment (OSSE) Environment  

NASA Technical Reports Server (NTRS)

An atmospheric sounding mission starts with a wide range of concept designs involving measurement technologies, observing platforms, and observation scenarios. Observing system simulation experiment (OSSE) is a technical approach to evaluate the relative merits of mission and instrument concepts. At Jet Propulsion Laboratory (JPL), the OSSE team has developed an OSSE environment that allows atmospheric scientists to systematically explore a wide range of mission and instrument concepts and formulate a science traceability matrix with a quantitative science impact analysis. The OSSE environment virtually creates a multi-platform atmospheric sounding testbed (MAST) by integrating atmospheric phenomena models, forward modeling methods, and inverse modeling methods. The MAST performs OSSEs in four loosely coupled processes, observation scenario exploration, measurement quality exploration, measurement quality evaluation, and science impact analysis.

Lee, Meemong; Weidner, Richard; Qu, Zheng; Bowman, Kevin; Eldering, Annmarie

2010-01-01

364

Characterization of Microwave-Induced Electric Discharge Phenomena in Metal-Solvent Mixtures  

PubMed Central

Electric discharge phenomena in metal–solvent mixtures are investigated utilizing a high field density, sealed-vessel, single-mode 2.45 GHz microwave reactor with a built-in camera. Particular emphasis is placed on studying the discharges exhibited by different metals (Mg, Zn, Cu, Fe, Ni) of varying particle sizes and morphologies in organic solvents (e.g., benzene) at different electric field strengths. Discharge phenomena for diamagnetic and paramagnetic metals (Mg, Zn, Cu) depend strongly on the size of the used particles. With small particles, short-lived corona discharges are observed that do not lead to a complete breakdown. Under high microwave power conditions or with large particles, however, bright sparks and arcs are experienced, often accompanied by solvent decomposition and formation of considerable amounts of graphitized material. Small ferromagnetic Fe and Ni powders (<40 ?m) are heated very rapidly in benzene suspensions and start to glow in the microwave field, whereas larger particles exhibit extremely strong discharges. Electric discharges were also observed when Cu metal or other conductive materials such as silicon carbide were exposed to the microwave field in the absence of a solvent in an argon or nitrogen atmosphere.

Chen, Wen; Gutmann, Bernhard; Kappe, C Oliver

2012-01-01

365

Ground-based Optical Observations of Geophysical Phenomena: Aurora Borealis and Meteors  

NASA Astrophysics Data System (ADS)

Advances in low-light level imaging technology have enabled significant improvements in the ground based study of geophysical phenomena. In this talk we focus on two such phenomena that occur in the Earth's ionosphere: aurorae and meteors. Imaging the aurora which is created by the interplay of the Earth's magnetosphere, ionosphere and atmosphere, provides a tool for remote sensing physical processes that are otherwise very difficult to study. By quantifying the intensities, scale sizes and lifetimes of auroral structures, we can gain significant insight into the physics behind the generation of the aurora and the interaction of the magnetosphere with the solar wind. Additionally, the combination of imaging with radars provides complimentary data and therefore more information than either method on its own. Meteor observations are a perfect example of this because the radar can accurately determine only the line-of-sight component of velocity, while imaging provides the direction of motion, the perpendicular velocity and brightness (a proxy for mass), therefore enabling a much more accurate determination of the full velocity vector and mass.

Samara, Marilia

2010-10-01

366

Dynamics of the solar photosphere. I. Two-dimensional spectroscopy of mesoscale phenomena.  

NASA Astrophysics Data System (ADS)

We address the "mesogranulation" phenomenon by analyzing a spectral time series, taken at disk center with a two-dimensional spectroscopy device and covering a period of 4 hours. This tunable device was composed by a Fabry-Perot interferometer mounted in tandem with an Universal Birefringent Filter (UBF). We calculate spatial power spectra, spatio-temporal k-? power, phase difference and coherence spectra at different low photospheric levels, in order to investigate the nature of the mesoscale phenomena. At the lowest levels, mesostructures appear as a part of an extended distribution of granular sizes without further distinction from granulation. Here, the plasma flows are driven by convection. On the other hand, a different mesoscale phenomenon emerges at levels as high as approximately 200-300km above ?_5000_=1, at medium spatial (k=~0.5...2Mm^-1^) and medium temporal (?=~0.5...1mHz) frequencies. This phenomenon is distinct from convection by its non-convective phase difference values ({PHI}_v-I_=~-30°, {PHI}_v-v_<0°) and by its different propagation character (almost horizontal propagation). By these properties, the mesoscale phenomena in the higher photosphere can be identified as internal gravity waves in the solar atmosphere.

Straus, T.; Bonaccini, D.

1997-08-01

367

Characterization of microwave-induced electric discharge phenomena in metal-solvent mixtures.  

PubMed

Electric discharge phenomena in metal-solvent mixtures are investigated utilizing a high field density, sealed-vessel, single-mode 2.45 GHz microwave reactor with a built-in camera. Particular emphasis is placed on studying the discharges exhibited by different metals (Mg, Zn, Cu, Fe, Ni) of varying particle sizes and morphologies in organic solvents (e.g., benzene) at different electric field strengths. Discharge phenomena for diamagnetic and paramagnetic metals (Mg, Zn, Cu) depend strongly on the size of the used particles. With small particles, short-lived corona discharges are observed that do not lead to a complete breakdown. Under high microwave power conditions or with large particles, however, bright sparks and arcs are experienced, often accompanied by solvent decomposition and formation of considerable amounts of graphitized material. Small ferromagnetic Fe and Ni powders (<40 ?m) are heated very rapidly in benzene suspensions and start to glow in the microwave field, whereas larger particles exhibit extremely strong discharges. Electric discharges were also observed when Cu metal or other conductive materials such as silicon carbide were exposed to the microwave field in the absence of a solvent in an argon or nitrogen atmosphere. PMID:24551491

Chen, Wen; Gutmann, Bernhard; Kappe, C Oliver

2012-02-01

368

Comprehending emergent systems phenomena through direct-manipulation animation  

NASA Astrophysics Data System (ADS)

This study seeks to understand the type of interaction mode that best supports learning and comprehension of emergent systems phenomena. Given that the literature has established that students hold robust misconceptions of such phenomena, this study investigates the influence of using three types of interaction; speed-manipulation animation (SMN), post-manipulation animation (PMA) and direct-manipulation animation (DMA) for increasing comprehension and testing transfer of the phenomena, by looking at the effect of simultaneous interaction of haptic and visual channels on long term and working memories when seeking to comprehend emergent phenomena. The questions asked were: (1) Does the teaching of emergent phenomena, with the aid of a dynamic interactive modeling tool (i.e., SMA, PMA or DMA), improve students' mental model construction of systems, thus increasing comprehension of this scientific concept? And (2) does the teaching of emergent phenomena, with the aid of a dynamic interactive modeling tool, give the students the necessary complex cognitive skill which can then be applied to similar (near transfer) and/or novel, but different, (far transfer) scenarios? In an empirical study undergraduate and graduate students were asked to participate in one of three experimental conditions: SMA, PMA, or DMA. The results of the study found that it was the participants of the SMA treatment condition that had the most improvement in post-test scores. Students' understanding of the phenomena increased most when they used a dynamic model with few interactive elements (i.e., start, stop, and speed) that allowed for real time visualization of one's interaction on the phenomena. Furthermore, no indication was found that the learning of emergent phenomena, with the aid of a dynamic interactive modeling tool, gave the students the necessary complex cognitive skill which could then be applied to similar (near transfer) and/or novel, but different, (far transfer) scenarios. Finally, besides treatment condition, gender and age were also shown to be predictors of score differences; overall, males did better than females, and younger students did better than older students.

Aguirre, Priscilla Abel

369

Cosmic dust in the earth's atmosphere  

NASA Astrophysics Data System (ADS)

This review discusses the magnitude of the cosmic dust input into the earth's atmosphere, and the resulting impacts from around 100 km to the earth's surface. Zodiacal cloud observations and measurements made with a spaceborne dust detector indicate a daily mass input of interplanetary dust particles ranging from 100 to 300 tonnes, which is in agreement with the accumulation rates of cosmic-enriched elements (Ir, Pt, Os and super-paramagnetic Fe) in polar ice cores and deep-sea sediments. In contrast, measurements in the middle atmosphere - by radar, lidar, high-flying aircraft and satellite remote sensing - indicate that the input is between 5 and 50 tonnes per day. There are two reasons why this huge discrepancy matters. First, if the upper range of estimates is correct, then vertical transport in the middle atmosphere must be considerably faster than generally believed; whereas if the lower range is correct, then our understanding of dust evolution in the solar system, and transport from the middle atmosphere to the surface, will need substantial revision. Second, cosmic dust particles enter the atmosphere at high speeds and undergo significant ablation. The resulting metals injected into the atmosphere are involved in a diverse range of phenomena, including: the formation of layers of metal atoms and ions; the nucleation of noctilucent clouds, which are a sensitive marker of climate change; impacts on stratospheric aerosols and O3 chemistry, which need to be considered against the background of a cooling stratosphere and geo-engineering plans to increase sulphate aerosol; and fertilization of the ocean with bio-available Fe, which has potential climate feedbacks.

Plane, John M. C.

2012-04-01

370

Evolution of the Terrestrial Atmospheres  

NSDL National Science Digital Library

This lecture compares terrestrial atmospheres and discusses atmospheric processes, atmospheric equilibrium, and the atmospheric development of Mars, Venus, and Earth. It ends with a discussion of natural and unnatural climate changes.

O'Connell, Robert

2005-06-28

371

Infrasound as an upper atmospheric probe: review and recent results  

NASA Astrophysics Data System (ADS)

Specification of upper atmospheric properties is hampered by the relatively small amount of direct observations in comparison to the lower atmosphere. Methods to measure the properties of the atmosphere above the stratopause is an active area of scientific research. In the past, a number of studies have focused on the use of infrasound as an upper atmospheric monitor, using naturally occurring infrasound from volcanoes and from microbaroms. It has been shown that infrasound propagation is sensitive to upper atmospheric dynamics, dominated by planetary waves, atmospheric tides, gravity waves and interactions of these phenomena. It has been found that upper atmospheric wind models are not always validated by infrasound data. Thus, infrasound measurements provide valuable information that can be used to validate and improve current understanding of winds in the mesosphere and lower thermosphere. Development of inverse procedures will allow one to use infrasound data to update upper atmospheric horizontal wind models. In this presentation, we will present a review of previous work and the application of an inverse procedure. The method, based on linearization of ray theory, is applied to infrasound signals from detonation activities at the Utah Test and Training Range (UTTR), measured on a dense infrasound network in the American West.

Assink, J. D.; Lalande, J.-M.; Talmadge, C.; Waxler, R.; Le Pichon, A.; Blanc, E.; Blanc-Benon, Ph.

2012-04-01

372

Shumann resonances and electromagnetic transparence in the atmosphere of Titan  

NASA Astrophysics Data System (ADS)

Among the multiple questions that the CASSINI/HUYGENS mission tries to answer is the likelihood of electric discharges in Titan's atmosphere. The instruments ``Huygens Atmospheric Structure Instrument'' and ``Radio and Plasma Wave Science'' will probe the electromagnetic emissions during the Huygens descent and Cassini flybys, respectively. Although no lightning was observed during Voyager's encounters with Titan in 1980 and 1981, this does not exclude the existence of lightning phenomena. Recent investigations show that lightning discharges could occur in the lower atmosphere, such as the detection of methane condensation clouds in the troposphere and the theoretical prediction of an electric field that would be sufficient enough to cause lightning. We present a numerical model of Titan's atmosphere with the aim of calculating the resonance frequencies and the atmospheric transparency to electromagnetic waves. The detection and measurement of these resonances, Schumann frequencies, by the Huygens probe, would show the existence of electric activity connected with lightning discharges in the atmosphere. As it happens with the Schumann frequencies of Earth, losses associated with the electric conductivity will make these frequencies to be lower than the theoretically predicted, the fundamental one being located between 11 and 15 Hz. An analytical study shows that the strong losses associated with the high conductivity make it impossible that an electromagnetic wave generated near the surface with a frequency of 10 MHz or lower reaches the outer part of Titan's atmosphere. Therefore the detection of electromagnetic waves coming from Titan's lower atmosphere by the RPWS instrument is very unlikely.

Molina-Cuberos, G. J.; Porti, J.; Besser, B. P.; Morente, J. A.; Margineda, J.; Lichtenegger, H. I. M.; Salinas, A.; Schwingenschuh, K.; Eichelberger, H. U.

2004-01-01

373

Remote detection of radioactive contamination in the atmosphere based on secondary optical and microwave radiation of atmospheric components  

NASA Astrophysics Data System (ADS)

The paper analyzes secondary phenomena of atmospheric radioactive pollution caused by activity of the nuclear cycle enterprises. These effects being as indicators for remote diagnostics of a radio-activity are discussed. Excitation of a molecular and gas component in the air and various chemical reactions under the action of radiation have been considered. As a result of these reactions, new aerosol and gaseous components in the form of the excited atoms and ions appear in the atmosphere and relax with emission including microwave and optical wavelengths. The observable luminescence of the air during the emergency events at the nuclea power stations are long enough to be dedected by modern receivers. Intensity of such radiation in a radioactive plume is estimated for ecological monitoring of the atmosphere. Aerosols appearing, as a result of UF6 hydrolysis, in the atmosphere and their behavior have been also shown to be detectable with remote sensing.

Chistyakova, Liliya K.; Penin, Sergei T.

1999-12-01

374

Effect of nonlinear optical phenomena on retinal damage  

NASA Astrophysics Data System (ADS)

Recent studies of retinal damage due to ultrashort laser pulses have shown interesting behavior. Laser thresholds for retinal damage from ultrashort (i.e. phenomena affect the characteristics of light impinging the retina and hence, changes the minimum energy required to produce damage. Nonlinear optical phenomena which occur in homogeneous materials like the ocular media include self-focusing, stimulated Brillouin scattering, supercontinuum generation, laser induced breakdown, and nonlinear absorption. We will discuss all relevant thresholds and determine which nonlinear optical phenomena play a role in mediating the reduction in energy required to produce minimum visible lesion damage to the retina.

Rockwell, Benjamin A.; Kennedy, Paul K.; Thomas, Robert J.; Roach, William P.; Rogers, Mark E.

1995-05-01

375

Phenomena Identification and Ranking Technique (PIRT) Panel Meeting Summary Report  

SciTech Connect

Phenomena Identification and Ranking Technique (PIRT) is a systematic way of gathering information from experts on a specific subject and ranking the importance of the information. NRC, in collaboration with DOE and the working group, conducted the PIRT exercises to identify safety-relevant phenomena for NGNP, and to assess and rank the importance and knowledge base for each phenomenon. The overall objective was to provide NRC with an expert assessment of the safety-relevant NGNP phenomena, and an overall assessment of R and D needs for NGNP licensing. The PIRT process was applied to five major topical areas relevant to NGNP safety and licensing: (1) thermofluids and accident analysis (including neutronics), (2) fission product transport, (3) high temperature materials, (4) graphite, and (5) process heat for hydrogen cogeneration.

Mark Holbrook

2007-07-01

376

Reaction and Transport Phenomena in Non-Thermal Equilibrium Plasmas  

NASA Astrophysics Data System (ADS)

The research presented in this dissertation pursued two independent but connected directions. The first was to expand our understanding of the important microscopic phenomena in low temperature plasma systems and of their influence on the observed processing characteristics. The second was to incorporate these microscopic phenomena into a continuum model which allows simulation of the important reaction and transport phenomena at reasonable computational costs. In the process, low temperature plasmas were considered from a thermodynamic view point on a continuum level through the generalized bracket formalism and from a microscopic viewpoint via an analytical solution of the Boltzmann kinetic equation. The continuum model developed, via solution of the Boltzmann kinetic equation, represents an extension to the previous continuum models by allowing for a direct calculation of the parameters based on the kinetic theory governing the microscopic phenomena and for a non-Maxwellian electron energy distribution. The key assumptions for the model validity are a small free path for the electrons, implying a reasonably high pressure, and a dominating electric field. The results from the kinetic theory based model are consistent with previous continuum model results under the assumption of a Maxwellian electron energy distribution. However, there is a large richness of phenomenology that is included in the kinetic model, taking into account the parameter dependence on the simulation variables and the more general non-Maxwellian energy distribution of the electrons, that is not available in previous continuum models. In addition, the current work revealed an inconsistency in the previous model results which suggests that although the model system used in both the previous and the current work is a good representation of the overall reaction and transport phenomena in a glow discharge, it does not adequately represent the ionization chemistry of real chemical systems. The kinetic theory based model developed in this dissertation represents an important step in the continuing investigation of the role played by the microscopic structure of the plasma in determining the macroscopic transport and reaction phenomena.

Gustafson, John Burton

377

Nonlinear Alfvén wave phenomena in the planetary magnetosphere  

NASA Astrophysics Data System (ADS)

Three nonlinear Alfvén wave phenomena in the planetary magnetosphere are discussed: (1) magnetohydrodynamic parametric instabilities induced by a nonlinear standing Alfvén wave, (2) parametric excitation of Alfvén and Langmuir waves by a nonlinear electromagnetic whistler wave, and (3) parametric generation of electromagnetic waves in the vicinity of electron plasma frequency via nonlinear coupling of Langmuir and Alfvén waves. Observational evidence in support of these nonlinear Alfvén wave phenomena, such as the auroral Alfvén-acoustic turbulence and the auroral Langmuir-Alfvén-whistler (LAW) events, in the planetary magnetosphere is presented.

Chian, A. C.-L.

1995-01-01

378

Third DOE natural phenomena hazards mitigation conference. Proceedings  

SciTech Connect

This conference on Natural Phenomena Hazards Mitigation has been organized into 15 presentation, panel, and poster sessions. The sessions included an overview of activities at DOE Headquarters; natural phenomena hazards tasks underway for DOE; two sessions on codes, standards, orders, criteria, and guidelines; two sessions on seismic hazards; equipment qualification; wind; PRA and margin assessments; modifications, retrofit, and restart; underground structures with a panel discussion; seismic analysis; seismic evaluation and design; and a poster session. Individual projects are processed separately for the data bases.

Not Available

1991-12-31

379

RELAP5-3D code validation for RBMK phenomena  

SciTech Connect

The RELAP5-3D thermal-hydraulic code was assessed against Japanese Safety Experiment Loop (SEL) and Heat Transfer Loop (HTL) tests. These tests were chosen because the phenomena present are applicable to analyses of Russian RBMK reactor designs. The assessment cases included parallel channel flow fluctuation tests at reduced and normal water levels, a channel inlet pipe rupture test, and a high power, density wave oscillation test. The results showed that RELAP5-3D has the capability to adequately represent these RBMK-related phenomena.

Fisher, J.E.

1999-09-01

380

RELAP5-3D Code Validation for RBMK Phenomena  

SciTech Connect

The RELAP5-3D thermal-hydraulic code was assessed against Japanese Safety Experiment Loop (SEL) and Heat Transfer Loop (HTL) tests. These tests were chosen because the phenomena present are applicable to analyses of Russian RBMK reactor designs. The assessment cases included parallel channel flow fluctuation tests at reduced and normal water levels, a channel inlet pipe rupture test, and a high power, density wave oscillation test. The results showed that RELAP5-3D has the capability to adequately represent these RBMK-related phenomena.

Fisher, James Ebberly

1999-09-01

381

Micro- and Mesoscale Phenomena in Space Plasmas Conference  

NASA Astrophysics Data System (ADS)

A detailed assessment of many of the important mesoscale and microscale processes in geospace was the purpose of the Chapman Conference on “Micro- and Mesoscale Phenomena in Space Plasmas,” held at Kauai, Hawaii, from February 11 to 16. The practical goals of the conference were to facilitate the exchange of information on small- and medium-scale phenomena in space plasmas and to increase awareness of the needs of experimentalists and theorists, with a certain focus toward the ongoing Geospace Environment Modeling (GEM) and Space Physics Theory programs. The conference was organized by Maha Ashour-Abdalla (UCLA), Tom Chang (MIT), and Paul Dusenbery (U. Colorado).

Burch, J. L.

382

Phenomena & Representations for Instruction of Science in Middle Schools (PRISMS)  

NSDL National Science Digital Library

PRISMS is a collection of reviewed phenomena and representations for middle school science teachers and learners. All resources are evaluated on the basis of their support of learning goals in AAAS Benchmarks for Science Literacy, Science for All Americans, and the NSES (National Science Education Standards). "Phenomena" are real-world objects and events that provide evidence of ideas in science. "Representations" are models, simulations, animations, and diagrams that serve to clarify ideas in science. Topics include astronomy, biology, earth science, structure of matter, energy, force and motion, and ecology. Each resource is accompanied by an annotated review that addresses the scope, quality, and sophistication of the item under review.

2011-04-28

383

Particles Spreading Phenomena in the Case of Glass Thermal Spraying  

NASA Astrophysics Data System (ADS)

The spreading phenomena of particles during thermal spraying are quite difficult to observe given the kinetics of the process. In this work, the splat formation of glass and alumina is theoretically compared, showing that glass transition and low-thermal conductivity yield a higher ratio between cooling and flattening times, which strongly modifies their spreading behavior. Wipe tests show that splash—splat transition temperature can be modified by the glass composition and its subsequent hydrodynamic properties. The detection of peculiar remaining objects, such as fibers and wavelets shows the possibility of “freezing” some phenomena that are totally unobservable with crystalline oxides, except with high-velocity observations.

Poirier, Thierry; Planche, Marie Pierre; Landemarre, Olivier; Coddet, Christian

2008-12-01

384

Fundamental investigation of duct/ESP phenomena. Final report  

SciTech Connect

Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

Brown, C.A. [Radian Corp., Austin, TX (United States); Durham, M.D. [ADA Technologies, Inc., Englewood, CO (United States); Sowa, W.A. [California Univ., Irvine, CA (United States). Combustion Lab.; Himes, R.M. [Fossil Energy Research Corp., Laguna Hills, CA (United States); Mahaffey, W.A. [CHAM of North America, Inc., Huntsville, AL (United States)

1991-10-21

385

Photoinduced Phenomena of Chalcogen Microclusters Confined in the Zeolite Cages  

NASA Astrophysics Data System (ADS)

Photoacoustic spectroscopy measurements have been carried out on the Se-ring microclusters confined in the cages of zeolite 4A. The shift of photoabsorption edge and the new absorption bands around 1.5 and 1.9 eV appeared by illumination of the light having the band-gap energy at low temperature. These phenomena may be associated with the distortion of Se ring and the formation of dangling bonds. Mixing of S or Te to the Se microclusters causes appreciable change in the photoinduced phenomena.

Maruyama, K.; Tsuzuki, T.; Yao, M.; Endo, H.

386

Physics of transport phenomena in magnetic confinement plasmas  

NASA Astrophysics Data System (ADS)

The phenomena caused by the transport of the plasma across the magnetic field in toroidal devices are surveyed, and theoretical models are reviewed. The plasma structure in a steady state is discussed. The recent development of the theory on the plasma transport driven by the microscopic turbulence is explained. The sudden change in confinement, such as the H-mode transition in tokamaks, is discussed next. The physics of the bifurcation of the edge plasma, based on the dynamics of the radial electric field, is discussed. Finally, the role of the anamolous transport on the disruptive phenomena is reviewed.

Itoh, Kimitaka; Itoh, Sanae-I.; Fukayama, Atsushi

1992-12-01

387

Fair weather atmospheric electricity  

NASA Astrophysics Data System (ADS)

Not long after Franklin's iconic studies, an atmospheric electric field was discovered in "fair weather" regions, well away from thunderstorms. The origin of the fair weather field was sought by Lord Kelvin, through development of electrostatic instrumentation and early data logging techniques, but was ultimately explained through the global circuit model of C.T.R. Wilson. In Wilson's model, charge exchanged by disturbed weather electrifies the ionosphere, and returns via a small vertical current density in fair weather regions. New insights into the relevance of fair weather atmospheric electricity to terrestrial and planetary atmospheres are now emerging. For example, there is a possible role of the global circuit current density in atmospheric processes, such as cloud formation. Beyond natural atmospheric processes, a novel practical application is the use of early atmospheric electrostatic investigations to provide quantitative information on past urban air pollution.

Harrison, R. G.

2011-06-01

388

Photochemistry in planetary atmospheres  

NASA Technical Reports Server (NTRS)

Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes in the earth's ancient atmosphere are described, and problems of interest in the earth's present troposphere are discussed, including the down wind effect, plume interactions, aerosol nucleation and growth, acid rain, and the fate of terpenes. Temperature fluctuations in the four principal layers of the earth's atmosphere, predicted decreases in the ozone concentration as a function of time, and spectra of particles in the earth's upper atmosphere are also presented. Finally, the vertical structure of the Venus cloud system and the thermal structure of the Jovian planets are shown graphically.

Levine, J. S.; Graedel, T. E.

1981-01-01

389

Atmospheric Electricity on Mars  

NASA Astrophysics Data System (ADS)

The atmosphere of Mars is one compelling example in our solar system that should possess active electrical processes, where dust storms are known to occur on local, regional, and global scales. Laboratory experiments and simulations all indicate that these events are expected to generate substantial quasi-static electric fields via triboelectric (i.e., frictional) charging, perhaps up to the breakdown potential of the Martian atmosphere. However current observations of potential electrical activity on Mars from both ground-based and orbital platforms have yielded conflicting results. If present, significant atmospheric electricity could be an important source of atmospheric chemistry on Mars, and thus impact our understanding of the evolution of the atmosphere and its past or present astrobiological potential. Here we review the current state of understanding regarding atmospheric electricity on Mars, and discuss its implications pending the results of future measurements.

Delory, G.; Farrell, W.

2011-10-01

390

Pluto's atmosphere near perihelion  

SciTech Connect

A recent stellar occultation has confirmed predictions that Pluto has an atmosphere which is sufficiently thick to uniformly envelope the planet and to extend far above the surface. Pluto's atmosphere consists of methane and perhaps other volatile gases at temperatures below their freezing points; it should regulate the surface temperature of its volatile ices to a globally uniform value. As Pluto approaches and passes through perihelion, a seasonal maximum in the atmospheric bulk and a corresponding minimum in the exposed volatile ice abundance is expected to occur. The lag in maximum atmospheric bulk relative to perihelion will be diagnostic of the surface thermal properties. An estimate of Pluto's atmospheric bulk may result if a global darkening (resulting from the disappearance of the seasonally deposited frosts) occurs before the time of maximum atmospheric bulk. The ice deposited shortly after perihelion may be diagnostic of the composition of Pluto's volatile reservoir.

Trafton, L.M. (Univ. of Texas, Austin (USA))

1989-11-01

391

Pluto's atmosphere near perihelion  

NASA Technical Reports Server (NTRS)

A recent stellar occultation has confirmed predictions that Pluto has an atmosphere which is sufficiently thick to uniformly envelope the planet and to extend far above the surface. Pluto's atmosphere consists of methane and perhaps other volatile gases at temperatures below their freezing points; it should regulate the surface temperature of its volatile ices to a globally uniform value. As Pluto approaches and passes through perihelion, a seasonal maximum in the atmospheric bulk and a corresponding minimum in the exposed volatile ice abundance is expected to occur. The lag in maximum atmospheric bulk relative to perihelion will be diagnostic of the surface thermal properties. An estimate of Pluto's atmospheric bulk may result if a global darkening (resulting from the disappearance of the seasonally deposited frosts) occurs before the time of maximum atmospheric bulk. The ice deposited shortly after perihelion may be diagnostic of the composition of Pluto's volatile reservoir.

Trafton, L. M.

1989-01-01

392

Global Atmospheric Aerosol Modeling  

NASA Technical Reports Server (NTRS)

Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

2012-01-01

393

Water in the Atmosphere  

NSDL National Science Digital Library

In this activity, participants learn about the atmosphere by making observations and taking measurements. They will go outside and use scientific equipment to collect atmospheric moisture data (temperature, relative humidity, precipitation and cloud cover). Students will use this qualitative and quantitative data to understand how water is found in the atmosphere, how the atmosphere determines weather and climate, and how Earthâs spheres are connected through the water cycle. The data collection is based on protocols from the GLOBE program. This activity uses the 5E instructional model and is part of the "Survivor Earth" series of one-hour lessons.

394

Interactive atmosphere lab  

NSDL National Science Digital Library

The ozone layer makes up an important part of our atmosphere. This informational activity, part of an interactive laboratory series for grades 8-12, explores changes in ozone concentration with altitude. Students view a diagram that shows the layers of the atmosphere with a temperature scale running from the surface of the Earth to the outermost reaches of the atmosphere. After reading introductory material, students are presented with nine questions about the layers of the atmosphere and interactions with ozone. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

395

Atmospheric Visualization Collection: Glossary  

NSDL National Science Digital Library

This page contains a glossary of terms commonly used in this collection, publications authored by collection members, scheduled meetings, and documentation on uses of the Atmospheric Visualization Collection.

Klaus, Christopher

2002-10-08

396

High gain observer: attenuation of the peak phenomena  

Microsoft Academic Search

In many problems of estimation, the high gain technique is used to compensate for nonlinear terms in order to guarantee the convergence of the estimator. However, the use of the high gain generally generates the so-called peak phenomena (at the beginning, the estimated trajectory deviates from the desired one). We extend the observer stated in J. P. Gauthier et al.

E. H. El Yaagoubi; A. El Assoudi; H. Hammouri

2004-01-01

397

Mapped Chebyshev pseudospectral method to study multiple scale phenomena  

Microsoft Academic Search

In the framework of mapped pseudospectral methods, we use a polynomial-type mapping function in order to describe accurately the dynamics of systems developing small size structures. Using error criteria related to the spectral interpolation error, the polynomial-type mapping is compared against previously proposed mappings for the study of collapse and shock wave phenomena. As a physical application, we study the

Adrian Alexandrescu; Jose R. Salgueiro; V ´ õctor; M. Perez-Garc

398

SELF-PERCEPTION: AN ALTERNATIVE INTERPRETATION OF COGNITIVE DISSONANCE PHENOMENA  

Microsoft Academic Search

A THEORY OF SELF-PERCEPTION IS PROPOSED TO PROVIDE AN ALTERNATIVE INTERPRETATION FOR SEVERAL OF THE MAJOR PHENOMENA EMBRACED BY FESTINGER'S THEORY OF COGNITIVE DISSONANCE AND TO EXPLICATE SOME OF THE SECONDARY PATTERNS OF DATA THAT HAVE APPEARED IN DISSONANCE EXPERIMENTS. IT IS SUGGESTED THAT THE ATTITUDE STATEMENTS WHICH COMPRISE THE MAJOR DEPENDENT VARIABLES IN DISSONANCE EXPERIMENTS MAY BE REGARDED AS

DARYL J. BEM

1967-01-01

399

Binding Phenomena within a Reductionist Theory of Grammatical Dependencies  

ERIC Educational Resources Information Center

This thesis investigates the implications of binding phenomena for the development of a reductionist theory of grammatical dependencies. The starting point is the analysis of binding and control in Hornstein (2001, 2009). A number of revisions are made to this framework in order to develop a simpler and empirically more successful account of…

Drummond, Alex

2011-01-01

400

Second Graders Read Nonfiction: Investigating Natural Phenomena and Disasters.  

ERIC Educational Resources Information Center

Describes a long-term science study project on natural disasters and phenomena in a second-grade classroom in which students had the major responsibility to plan, choose, inquire, and problem solve as they chose topics, browsed and read, planned and made murals, wrote and drew in their journals, and designed dramas which mixed story and…

Robb, Laura

1994-01-01

401

Secondary autoimmune phenomena in the pathogenesis of psoriasis  

Microsoft Academic Search

Evidence for autoimmune phenomena in the pathogenetic mechanisms of psoriasis with special reference to the in vivo deposits in the keratin layer of complement fixing immune complexes has been provided by several authors already (Krogh 1969; Krogh and Tonder 1968, 1972, 1973; Beutner et al. 1975, 1978; Jablonska et al. 1975, 1978). In the present study, punch biopsy specimens form

A. Tosca; Z. Chrisoboli; J. Hatzis; A. Varelzidis; J. Stratigos

1981-01-01

402

The Effects of Globalization Phenomena on Educational Concepts  

ERIC Educational Resources Information Center

It is becoming more and more apparent that globalization processes represent, theoretically as well as practically, a challenge for educational sciences and therefore, it must be addressed within the sphere of education. Accordingly, educational conceptions have to adapt to globalization phenomena and focus more on alternative and innovative…

Schrottner, Barbara Theresia

2010-01-01

403

Time dependent crack tip phenomena in gas turbine disk alloys  

Microsoft Academic Search

In the continuous quest for improved thrust-to-weight ratio and higher efficiency and power output, designers of aircraft engines and land based power systems subject gas turbine alloys to increasing service temperatures and stresses in aggressive environments. Under these conditions, the determination of component life increasingly requires a detailed understanding of time dependent crack tip phenomena and their ability to degrade

Paul Frederick Browning

1998-01-01

404

Interactive 3D Simulation and Visualization of Optical Phenomena  

Microsoft Academic Search

We describe a multidisciplinary ef fort for creating interacti ve 3D graphical modules for visualizing optical phenomena. These modules are designed for use in an upper-level undergraduate physics course. The modules are devel- oped in Open Inventor, which allows them to run under both Unix and Win- dows. The work is significant in that it applies contemporary interacti ve 3D

David C. Banks; John T. Foley; Kiril N. Vidimce; Ming-Hoe Kiu; Jay Brown

405

Measurements of Extreme Physical Phenomena by Fourier Fringe Analysis  

NASA Astrophysics Data System (ADS)

The paper reviews recent applications of the Fourier transform method (FTM) of fringe pattern analysis to the measurements of extreme physical phenomena, such as those involving ultra fast optical pulses, extremely small atomic displacements, and unconventional electron or EUV waves, and shows how the advantages of FTM are exploited in these cutting edge application areas.

Takeda, Mitsuo

2010-04-01

406

Effects of friction welding conditions on initial joining phenomena  

Microsoft Academic Search

This paper describes an investigation into the effects of friction welding conditions on the initial joining phenomena and joining mechanism in the first and second phases of friction welding on a continuous drive type friction welding machine using mild steel specimens. The results obtained may be summarised as follows:1. At a friction pressure as low as around 35 MPa, the

M. Hasegawa; T. Ieda

1999-01-01

407

How Thought Presents Itself among the Phenomena of Nature  

Microsoft Academic Search

IN your paper of the 5th you give a short abstract of a recent lecture at the Royal Institution by Mr. G. Johnstone Stoney, on the question ``How Thought presents itself among the Phenomena of Nature.'' In this abstract I observe an assertion which is quite new to me, and, I must add, quite unintelligible. It occurs in the first

1885-01-01

408

Mean field theory of self-organized critical phenomena  

SciTech Connect

A mean field theory is presented for the recently discovered self-organized critical phenomena. The critical exponents are calculated and found to be the same as the mean field values for percolation. The power spectrum has 1/f behavior with exponent Phi = 1.

Tang, C.; Bak, P.

1988-06-01

409

An Initial Investigation of the Psychedelic Drug Flashback Phenomena  

ERIC Educational Resources Information Center

This study investigated some characteristics of persons experiencing "flashbacks," and provides systematic descriptions of the flashback phenomena. The drug user showed no significant differences in psychopathological characteristics as measured by the MMPI, nor significant differences in attentional processes as measured by the Embedded Figures…

Matefy, Robert E.; Krall, Roger G.

1974-01-01

410

NUMERICAL STUDY OF DEFROSTING PHENOMENA OF AUTOMOTIVE WINDSHIELD GLASS  

Microsoft Academic Search

The present work was undertaken to analyze numerically the defrosting phenomena of automobile windshield glass. In order to analyze the phase change from frost to water on windshield glass by discharging hot air from a defroster nozzle, the flow and the temperature field of the cabin interior, the heat transfer through the windshield glass, and the phase change of frost

W. G. Park; M. S. Park; Y. R. Jung; K. L. Jang

2005-01-01

411

Interfacial Bonding and Fracture Phenomena between Porcelain and Metal Coping  

Microsoft Academic Search

In last few decades, the porcelain fused to metal crown has been a successful dental restoration and many studies are worked and evaluated, but increasing availability of new base metal alloys demands constant evaluation of bonding and fracture between porcelain and metal coping. The aim of this study is to identify fracture phenomena and to measure bonding strength between porcelain

J. S. Park; H. S. Kim; M. K. Son; H. C. Choe

2011-01-01

412

Developing Critical Thinking through the Study of Paranormal Phenomena.  

ERIC Educational Resources Information Center

Argues that accounts of paranormal phenomena can serve as an ideal medium in which to encourage students to develop critical-thinking skills. Describes a cooperative-learning approach used to teach critical thinking in a course on paranormal events. Reports that critical-thinking skills increased and that the course received favorable student…

Wesp, Richard; Montgomery, Kathleen

1998-01-01

413

Experimental and Analytical Study of the Sputtering Phenomena.  

National Technical Information Service (NTIS)

One form of the sputtering phenomena, the heat-transfer process that occurs when an initially hot vertical surface is cooled by a falling liquid film, was examined from a new experimental approach. The sputtering front is the lowest wetted position on the...

P. A. Howard

1976-01-01

414

Influence of Chemistry on Severe Accident Phenomena in Integral Tests.  

National Technical Information Service (NTIS)

The influence of chemistry on in-vessel severe accident phenomena in integral effects in-pile tests is reviewed. In-vessel severe accident chemistry involves high temperature interactions between the materials used in the tests; namely, fuel rods, control...

R. R. Hobbins D. J. Osetek D. A. Petti D. L. Hagrman

1988-01-01

415

Interferometric CT technique for three-dimensional shock wave phenomena  

Microsoft Academic Search

An interferometric CT technique is developed to observe three- dimensional phenomena in shock tube experiments, and is applied to investigate three-dimensional features of shock waves and vortices discharged from a square open end. A small duct model is introduced in the test section of the shock tube, and is rotated around its central axis to change the observation angle in

Hiroki Honma; Kazuo Maeno; M. Ishihara; T. Yoshimura

2001-01-01

416

Studies of anode sheath phenomena in Hall thrusters  

Microsoft Academic Search

Several issues associated with plasma-wall interactions in Hall thrusters are considered, with the primary focus being experimental and theoretical studies of the plasma-anode sheath. The main goal is to investigate how the sheath voltage drop depends on the thruster operating conditions. Unlike in classic glow discharges, anode sheath phenomena were not studied in Hall thrusters. This investigation gives an insight

Leonid A. Dorf

2004-01-01

417

Tidal phenomena and migration, production, and distribution of hydrocarbon pools  

SciTech Connect

New problems in the migration of fluids and in the formation and distribution of hydrocarbon pools in relation to tidal phenomena are discussed in the context A.R. Kinzikeyev's paper, Effects of Earth Tides as a Factor in the Migration, Formation, and Distribution of Hydrocarbon Pools, Geologiya Nefti i Gaza, 1978, no. 5, 36-39. (JMT)

Lopatin, A.F.

1981-01-01

418

Study of Precipitation Phenomena in Aluminum Alloys by Positron Annihilation.  

National Technical Information Service (NTIS)

To assess the sensitivity of positron annihilation (PA) to precipitation phenomena, the Doppler broadened PA lineshape was monitored as a function of isochronal annealing steps on a series of quenched aluminum alloys. A study of the Al--Cu system, includi...

W. R. Wampler W. B. Gauster

1979-01-01

419

Vapor explosion phenomena with respect to nuclear reactor safety assessment  

Microsoft Academic Search

Stringent licensing procedures for commercial nuclear reactor operation require an in-depth analysis of the phenomena associated with postulated reactor core overheating accidents. One aspect of nuclear reactor safety assessment is a prediction of the consequences of interaction between molten fuel and coolant, in which rapid heat transfer from the fuel may lead to explosive vaporization of the coolant. Some of

A. W. Cronenberg; R. Benz

1978-01-01

420

Nuclear phenomena in low-energy nuclear reaction research.  

PubMed

This is a comment on Storms E (2010) Status of Cold Fusion, Naturwissenschaften 97:861-881. This comment provides the following remarks to other nuclear phenomena observed in low-energy nuclear reactions aside from helium-4 make significant contributions to the overall energy balance; and normal hydrogen, not just heavy hydrogen, produces excess heat. PMID:23949247

Krivit, Steven B

2013-09-01

421

Ferroelectric and Related Phenomena in Biological and Bioinspired Nanostructures  

Microsoft Academic Search

We review ferroelectric and related phenomena in biological materials. Also the results of the study of peptide nanotubes (PNT), which are formed by self-assembly of aromatic peptides building blocks, are presented. We describe a new preparation process for making highly ordered alignments of PNT by vapor deposition of bio-molecules. The conducted optical studies show that PNTs possess nanocrystalline ceramics structure,

N. Amdursky; P. Beker; J. Schklovsky; E. Gazit; G. Rosenman

2010-01-01

422

Natural phenomena risk assessment at Rocky Flats Plant  

SciTech Connect

A realistic approach is currently being used at the Rocky Flats Plant to assess the risks of natural phenomena events. The methodology addresses frequency of occurrence estimates, damage stress on the facility and vital equipment, material-at-risk, release fractions and source terms, leakpath, dispersion and dosimetric models, risk curves, and an uncertainty analysis. 28 refs.

Foppe, T.L.

1985-01-01

423

Physics of Transport Phenomena in Magnetic Confinement Plasmas.  

National Technical Information Service (NTIS)

The phenomena caused by the transport of the plasma across the magnetic field in toroidal devices are surveyed, and theoretical models are reviewed. The plasma structure in a steady state is discussed. The recent development of the theory on the plasma tr...

K. Itoh S. Itoh A. Fukayama

1992-01-01

424

New Phenomena in NC Field Theory and Emergent Spacetime Geometry  

SciTech Connect

We give a brief review of two nonperturbative phenomena typical of noncommutative field theory which are known to lead to the perturbative instability known as the UV-IR mixing. The first phenomena concerns the emergence/evaporation of spacetime geometry in matrix models which describe perturbative noncommutative gauge theory on fuzzy backgrounds. In particular we show that the transition from a geometrical background to a matrix phase makes the description of noncommutative gauge theory in terms of fields via the Weyl map only valid below a critical value g*. The second phenomena concerns the appearance of a nonuniform ordered phase in noncommutative scalar {phi}{sup 4} field theory and the spontaneous symmetry breaking of translational/rotational invariance which happens even in two dimensions. We argue that this phenomena also originates in the underlying matrix degrees of freedom of the noncommutative field theory. Furthermore it is conjectured that in addition to the usual WF fixed point at {theta} = 0 there must exist a novel fixed point at {theta} = {infinity} corresponding to the quartic hermitian matrix model.

Ydri, Badis [Institute of Physics BM Annaba University, BP 12-23000-Annaba (Algeria)

2010-10-31

425

Origin and evolution of planetary atmospheres  

NASA Technical Reports Server (NTRS)

This report concerns several research tasks related to the origin and evolution of planetary atmospheres and the large-scale distribution of volatile elements in the Solar System. These tasks and their present status are as follows: (1) we have conducted an analysis of the volatility and condensation behavior of compounds of iron, aluminum, and phosphorus in the atmosphere of Venus in response to publish interpretations of the Soviet Venera probe XRF experiment data, to investigate the chemistry of volcanic gases, injection of volatiles by cometary and asteroidal impactors, and reactions in the troposphere; (2) we have completed and are now writing up our research on condensation-accretion modeling of the terrestrial planets; (3) we have laid the groundwork for a detailed study of the effects of water transport in the solar nebula on the bulk composition, oxidation state, and volatile content of preplanetary solids; (4) we have completed an extensive laboratory study of cryovolcanic materials in the outer solar system; (5) we have begun to study the impact erosion and shock alteration of the atmosphere of Mars resulting from cometary and asteroidal bombardment; and (6) we have developed a new Monte Carlo model of the cometary and asteroidal bombardment flux on the terrestrial planets, including all relevant chemical and physical processes associated with atmospheric entry and impact, to assess both the hazards posed by this bombardment to life on Earth and the degree of cross-correlation between the various phenomena (NO(x) production, explosive yield, crater production, iridium signature, etc.) that characterize this bombardment. The purpose of these investigations has been to contribute to the developing understanding of both the dynamics of long-term planetary atmosphere evolution and the short-term stability of planetary surface environments.

Lewis, John S.

1992-01-01

426

Giovanni: Exploring, Visualizing, and Acquiring Atmospheric Data  

NASA Astrophysics Data System (ADS)

The NASA Goddard Space Flight Center (GSFC) Earth Sciences (GES) Data and Information Services Center (DISC) has made great strides in facilitating science and applications research by, in consultation with its users, developing innovative tools and data services. One such tool that has gained much popularity and continues to evolve in response to science research and application needs is Giovanni, an interactive data analysis and visualization tool, used primarily for exploring large and many NASA atmospheric datasets for atmospheric phenomena of interest. With the rapidly increasing amounts of archived atmospheric data from NASA missions: Aura (instruments: OMI, MLS, HIRDLS, TES), Aqua (MODIS, AIRS), and Terra (MODIS), and the newest missions (Cloudsat and CALIPSO), as well as data from heritage mission/instruments, such TOMS, UARS, and TOVS, Giovanni easily enables users to manipulate data and uncover nuggets of information that potentially lead to scientific discovery. The basic Giovanni capabilities of providing area plots, one or two variable time plots, Hovmoller plots, ASCII output, image animation, two parameter intercomparisons, two parameter plots, scatter plots (relationships between two parameters), and temporal correlation maps have been enhanced with many new and more advanced functions, such as vertical profiles, vertical cross-sections, zonal averages, and the newest function, multi-instrument vertical plots beneath the A-Train track. This presentation presents remote sensing atmospheric observations measured by several NASA remote sensing instruments utilizing and demonstrating Giovanni's features. A comprehensive list of geophysical parameters measured by the aforementioned instruments, including description of data preparation for utilization in Giovanni will be provided. By emphasizing Giovanni's newest features, which add to those of interest to the atmospheric community, advances in the GES DISC A-Train Data Depot (ATDD) will be described. In addition, potential inclusion of ground station measurements of pollution into Giovanni, and utilization of this system in air-quality studies will be addressed. Additional information can be found at the Giovanni website: http://daac.gsfc.nasa.gov/techlab/giovanni/

Peter, S.; Steven, K.; Greg, L.; Andrey, S.; Irina, G.; Steve, B.

2006-12-01

427

Seasonality of alcohol-related phenomena in Estonia  

NASA Astrophysics Data System (ADS)

We studied alcohol consumption and its consequences as a seasonal phenomenon in Estonia and analysed the social and environmental factors that may cause its seasonal rhythm. There are two important questions when researching the seasonality of human activities: (1) whether it is caused by natural or social factors, and (2) whether the impact of the factors is direct or indirect. Often the seasonality of social phenomena is caused by social factors, but the triggering mechanisms are related to environmental factors like temperature, precipitation, and radiation via the circannual calendar. The indicators of alcohol consumption in the current paper are grouped as: (1) pre-consumption phenomena, i.e. production, tax and excise, sales (beer, wine and vodka are analysed separately), and (2) post-consumption phenomena, i.e. alcohol-related crime and traffic accidents and the number of people detained in lockups and admitted to alcohol treatment clinics. In addition, seasonal variability in the amount of alcohol advertising has been studied, and a survey has been carried out among 87 students of Tartu University. The analysis shows that different phenomena related to alcohol have a clear seasonal rhythm in Estonia. The peak period of phenomena related to beer is in the summer, from June to August and the low point is during the first months of the year. Beer consumption correlates well with air temperature. The consumption of vodka increases sharply at the end of the year and in June; the production of vodka does not have a significant correlation with negative temperatures. The consumption of wine increases during summer and in December. The consequences of alcohol consumption, expressed as the rate of traffic accidents or the frequency of medical treatment, also show seasonal variability. Seasonal variability of alcohol consumption in Estonia is influenced by natural factors (temperature, humidity, etc.) and by social factors (celebrations, vacations, etc.). However, distinguishing between impacts of direct and indirect relationships is complicated, as they are interlinked.

Silm, Siiri; Ahas, Rein

2005-03-01

428

Stability of atmospheric pressure glow discharges  

NASA Astrophysics Data System (ADS)

There has been a considerable interest in non-thermal atmospheric pressure discharges over the past decade due to increased number of industrial applications. Although non-thermal atmospheric pressure discharges have been intensively studied for the past century the clear physical picture of these discharges is far from being complete. Spontaneous transition of non-thermal atmospheric pressure discharges to thermal discharge and discharge filamentation are among least understood plasma phenomena. The discharge stability and reliable control of plasma parameters are highly desirable for numerous applications. This study focuses on stability of atmospheric pressure glow discharges with respect to filamentation and arcing. Atmospheric pressure glow discharge (APG) is the newest and the most promising addition to the family of non-thermal atmospheric pressure discharges. However this discharge is very susceptible to thermal instability which causes arcing, loss of uniformity and significant damage to electrodes. Suppression of thermal instability and effective control of discharge parameters is critical for industrial applications. A model was developed to understand transition to arc in atmospheric pressure glow discharges. APG discharges that operate in pure helium and in helium with addition of oxygen and nitrogen were considered in these studies. Simulation results indicate that arcing is the result of sheath breakdown rather than thermal instability. It was shown that although sheath breakdown is always followed by overheating the transition to arc in atmospheric glow discharges is not a result of thermal instability. In second part of this research interaction between plasma filaments in dielectric barrier discharges has been studied. This interaction is responsible for the formation of microdischarge patterns reminiscent of two-dimensional crystals. Depending on the application, microdischarge patterns may have a significant influence on DBD performance, particularly when spatial uniformity is desired. A microdischarge interaction model is proposed and a Monte-Carlo simulation of microdischarge interactions in the discharge is presented. A new method for analysis of microdischarge patterns that allow measuring the degree of pattern regularity was developed. Simulated and experimental patterns were compared using the newly developed method. Analysis of microdischarge patterns shows that regularity of the patterns increases with the number of excitation cycles used to produce the pattern.

Chirokov, Alexandre V.

429

EDITORIAL: Spin-transfer-torque-induced phenomena Spin-transfer-torque-induced phenomena  

NASA Astrophysics Data System (ADS)

This cluster, consisting of five invited articles on spin-transfer torque, offers the very first review covering both magnetization reversal and domain-wall displacement induced by a spin-polarized current. Since the first theoretical proposal on spin-transfer torque—reported by Berger and Slonczewski independently—spin-transfer torque has been experimentally demonstrated in both vertical magnetoresistive nano-pillars and lateral ferromagnetic nano-wires. In the former structures, an electrical current flowing vertically in the nano-pillar exerts spin torque onto the thinner ferromagnetic layer and reverses its magnetization, i.e., current-induced magnetization switching. In the latter structures, an electrical current flowing laterally in the nano-wire exerts torque onto a domain wall and moves its position by rotating local magnetic moments within the wall, i.e., domain wall displacement. Even though both phenomena are induced by spin-transfer torque, each phenomenon has been investigated separately. In order to understand the physical meaning of spin torque in a broader context, this cluster overviews both cases from theoretical modellings to experimental demonstrations. The earlier articles in this cluster focus on current-induced magnetization switching. The magnetization dynamics during the reversal has been calculated by Kim et al using the conventional Landau--Lifshitz-Gilbert (LLG) equation, adding a spin-torque term. This model can explain the dynamics in both spin-valves and magnetic tunnel junctions in a nano-pillar form. This phenomenon has been experimentally measured in these junctions consisting of conventional ferromagnets. In the following experimental part, the nano-pillar junctions with perpendicularly magnetized FePt and half-metallic Heusler alloys are discussed from the viewpoint of efficient magnetization reversal due to a high degree of spin polarization of the current induced by the intrinsic nature of these alloys. Such switching can be further operated at high frequency resulting in an oscillator, as shown in the article by Sulka et al. These results provide fundamental elements for magnetic random access memories. The later articles discuss domain-wall displacement. Again this phenomenon is also described by Shibata et al based on the LLG equation with spin-torque terms. This analytical model can explain the details of the depinning mechanism and a critical current for the displacement. Experimental observation is presented in the subsequent article by Malinowski et al, showing the depinning processes for the cases of intrinsic and extrinsic pinning sites. Here, the detailed magnetic moment configurations within the wall hold the dominant control over the critical current. These results can be used for future 3-dimensional magnetic memories, such as racetrack memory proposed by IBM. We sincerely hope this cluster offers an up-to-date understanding of macroscopic behaviour induced by spin-transfer torque and contributes to further advancement in this exciting research field. We are grateful to all the authors for spending their precious time and knowledge submitting to this cluster. We would also like to thank Professor Kevin O'Grady for his kind offer of the opportunity to make this review accessible to a general audience.

Hirohata, Atsufumi

2011-09-01

430

Photochemistry of planetary atmospheres. [Mars atmospheric composition  

NASA Technical Reports Server (NTRS)

The atmospheric composition of Mars is presented, and the applicability of laboratory data on CO2 absorption cross sections and quantum yields of dissociation is discussed. A summary and critical evaluation are presented on the various mechanisms proposed for converting the photodissociation products CO and O2 back to CO2.

Stief, L. J.

1973-01-01

431

Comets, Impacts, and Atmospheres.  

National Technical Information Service (NTIS)

Studies of element abundances and values of D/H in the atmospheres of the giant planets and Titan have emphasized the important role of icy planetesimals in the formation of these bodies. In these atmospheres, C/H and D/H increase as the relative masses o...

T. Owen A. Bar-nun

1994-01-01

432

The Earth's Atmosphere  

NSDL National Science Digital Library

This site contains 12 questions on the topic of the atmosphere, which covers electromagnetic radiation and layers of the Earth's atmosphere (exosphere, thermosphere, and more). This is part of the Principles of Earth Science course at the University of South Dakota. Users submit an answer and are provided immediate verification.

Heaton, Timothy

433

Stacking up the Atmosphere  

NSDL National Science Digital Library

In this hands-on activity, participants learn the characteristics of the five layers of the atmosphere and make illustrations to represent them. They roll the drawings and place them in clear plastic cylinders, and then stack the cylinders to make a model column of the atmosphere.

Youngman, Betsy; Pennycook, Jean; Huffman, Louise; Dahlman, Luann; Nebraska, Andrill- U.

434

PANS IN THE ATMOSPHERE  

EPA Science Inventory

The types of PANs and PBzN's present or possibly present in the ambient atmosphere are discussed. iological activities of the PAN's and PBzN's are briefly considered. he concentration and composition of PANs in the atmosphere are discussed and calculations made of the production ...

435

MODIS Atmospheric Data Handler  

NASA Technical Reports Server (NTRS)

The Moderate Resolution Imaging Spectroradiometer (MODIS) Atmosphere Data Handler software converts the HDF data to ASCII format, and outputs: (1) atmospheric profiles of temperature and dew point and (2) total precipitable water. Quality-control data are also considered in the export procedure.

Anantharaj, Valentine; Fitzpatrick, Patrick

2008-01-01

436

Clouds in Planetary Atmospheres  

NASA Technical Reports Server (NTRS)

In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice cyrstals suspended in the air. The study of clouds touches on many facets of armospheric science. The chemistry of clouds is tied to the chemistry of the surrounding atmosphere.

West, R.

1999-01-01

437

Seasonal-scale Observational Data Analysis and Atmospheric Phenomenology for the Cold Land Processes Experiment  

NASA Technical Reports Server (NTRS)

The Cold Land Processes Experiment (CLPX) experiment emphasized the development of a strong synergism between process-oriented understanding, land surface models and microwave remote sensing. Our work sought to investigate which topographically- generated atmospheric phenomena are most relevant to the CLPX MSA's for the purpose of evaluating their climatic importance to net local moisture fluxes and snow transport through the use of high-resolution data assimilation/atmospheric numerical modeling techniques. Our task was to create three long-term, scientific quality atmospheric datasets for quantitative analysis (for all CLPX researchers) and provide a summary of the meteorologically-relevant phenomena of the three MSAs (see Figure) over northern Colorado. Our efforts required the ingest of a variety of CLPX datasets and the execution an atmospheric and land surface data assimilation system based on the Navier-Stokes equations (the Local Analysis and Prediction System, LAPS, and an atmospheric numerical weather prediction model, as required) at topographically- relevant grid spacing (approx. 500 m). The resulting dataset will be analyzed by the CLPX community as a part of their larger research goals to determine the relative influence of various atmospheric phenomena on processes relevant to CLPX scientific goals.

Poulos, Gregory S.; Stamus, Peter A.; Snook, John S.

2005-01-01

438

Magneto-atmospheric waves  

NASA Technical Reports Server (NTRS)

A theoretical treatment of magneto-atmospheric waves is presented and applied to the modelling of waves in the solar atmosphere. The waves arise in compressible, stratified, electrically conductive atmospheres within gravitational fields when permeated by a magnetic field. Compression, buoyancy, and distortion of the magnetic field all contribute to the existence of the waves. Basic linearized equations are introduced to describe the waves and attention is given to plane-stratified atmospheres and their stability. A dispersion relation is defined for wave propagation in a plane-stratified atmosphere when there are no plane-wave solutions. Solutions are found for the full wave equation in the presence of either a vertical or a horizontal magnetic field. The theory is applied to describing waves in sunspots, in penumbrae, and flare-induced coronal disturbances.

Thomas, J. H.

1983-01-01

439

Earth's Atmosphere Wind Dance  

NSDL National Science Digital Library

This lesson introduces the expanding and condensing properties of air masses and the unequal heating of Earth as the force behind the wind, it also displays the structure of the earth's atmosphere and the science concepts of layering, air density, and particles by using dance concepts such as level and shape. Students use previously learned movement skills to relay information about winds and the structure of the atmosphere. Hello Students! In class we have been learning about the atmosphere, to review some of what we've learned please follow the directions below! To read about the five layers that make up the earth's atmosphere click on this link: 5 Layers of the Atmosphere To learn about the properties of wind click on this link: Wind To learn ...

Magnuson, Miss

2009-12-07

440

The atmosphere below  

NASA Astrophysics Data System (ADS)

In this educational 'Liftoff to Learning' video series, astronauts from the STS-45 Space Shuttle Mission (Kathy Sullivan, Byron Lichtenberg, Brian Duffy, Mike Foale, David Leestma, Charlie Bolden, and Dirk Frimont) explain and discuss the Earths atmosphere, its needs, the changes occurring within it, the importance of ozone, and some of the reasons behind the ozone depletion in the Earths atmosphere. The questions of: (1) what is ozone; (2) what has happened to the ozone layer in the atmosphere; and (3) what exactly does ozone do in the atmosphere, are answered. Different chemicals and their reactions with ozone are discussed. Computer animation and graphics show how these chemical reactions affect the atmosphere and how the ozone hole looks and develops at the south pole during its winter season appearance.

1992-05-01

441

The Atmosphere Below  

NASA Technical Reports Server (NTRS)

In this educational 'Liftoff to Learning' video series, astronauts from the STS-45 Space Shuttle Mission (Kathy Sullivan, Byron Lichtenberg, Brian Duffy, Mike Foale, David Leestma, Charlie Bolden, and Dirk Frimont) explain and discuss the Earths atmosphere, its needs, the changes occurring within it, the importance of ozone, and some of the reasons behind the ozone depletion in the Earths atmosphere. The questions of: (1) what is ozone; (2) what has happened to the ozone layer in the atmosphere; and (3) what exactly does ozone do in the atmosphere, are answered. Different chemicals and their reactions with ozone are discussed. Computer animation and graphics show how these chemical reactions affect the atmosphere and how the ozone hole looks and develops at the south pole during its winter season appearance.

1992-01-01

442

Atmospheric Fluorescence Yield  

NASA Technical Reports Server (NTRS)

Several existing and planned experiments estimate the energies of ultra-high energy cosmic rays from air showers using the atmospheric fluorescence from these showers. Accurate knowledge of the conversion from atmospheric fluorescence to energy loss by ionizing particles in the atmosphere is key to this technique. In this paper we discuss a small balloon-borne instrument to make the first in situ measurements versus altitude of the atmospheric fluorescence yield. The instrument can also be used in the lab to investigate the dependence of the fluorescence yield in air on temperature, pressure and the concentrations of other gases that present in the atmosphere. The results can be used to explore environmental effects on and improve the accuracy of cosmic ray energy measurements for existing ground-based experiments and future space-based experiments.

Adams, James H., Jr.; Christl, M. J.; Fountain, W. F.; Gregory, J. C.; Martens, K.; Sokolsky, P.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

443

Impact erosion of planetary atmospheres  

Microsoft Academic Search

The problem of planetary atmospheres evolution due to impacts of large cosmic bodies was investigated by Ahrens, O'Keefe, Cameron, Hunten and others. These studies were focused mainly on the atmosphere growth under impact devolatilization and atmosphere losses due to escape of high velocity ejecta. Most of the results concerning atmosphere erosion were based on assumption that atmosphere itself does not

Valery Shuvalov

1999-01-01

444

Atmospheric Mercury Deposition Monitoring ? National Atmospheric Deposition Program (NADP)  

EPA Science Inventory

The National Atmospheric Deposition Program (NADP) developed and operates a collaborative network of atmospheric mercury monitoring sites based in North America ? the Atmospheric Mercury Network (AMNet). The justification for the network was growing interest and demand from many ...

445

Delusions, illusions and hallucinations in epilepsy: 1. Elementary phenomena.  

PubMed

The purpose of this paper and its pair is to provide a comprehensive review, from the different perspectives of neurology and neuropsychiatry, of the phenomenology and mechanisms of hallucinatory experience in epilepsy. We emphasise the clinical and electrophysiological features, and make comparisons with the primary psychoses. In this paper, we consider definitions and elementary hallucinatory phenomena. Regarding definition, there is a clearly divergent evolution in meaning of the terms delusion, illusion and hallucination in the separate traditions of neurology and psychiatry. Psychiatry makes clear distinctions between the terms and has focussed on the empirical use of descriptive psychopathology in order to delineate the various psychiatric syndromes, including those in epilepsy. These distinctions in psychiatry have stood the test of time and are useful in clinical descriptive terms, but do not help to understand the basic mechanisms. The focus of neurology has been to regard delusions, illusions and hallucinations in epilepsy as a result of localised or network based neuronal epileptic activity that can be investigated especially using intracranial stereoelectroencephalography (SEEG). The neurological approach leads to a more synoptical definition of 'hallucination' than in psychiatry and to the conclusion that there is little point in differentiating hallucination from illusion or delusion in view of the overlap in the physiological bases of the phenomena. The semiologically derived differentiation of these terms in psychiatry is not supported by similarly discrete electrophysiological signatures. However, as discussed in the second paper, some psy