Significance of scatter radar studies of E and F region irregularities at high latitudes

International Nuclear Information System (INIS)

Greenwald, R.A.

1983-01-01

This chapter considers the mechanisms by which electron density irregularities may be generated in the high latitude ionosphere and the techniques through which they are observed with ground base radars. The capabilities of radars used for studying these irregularities are compared with the capabilities of radars used for incoherent scatter measurements. The use of irregularity scatter techniques for dynamic studies of larger scale structured phenomena is discussed. Topics considered include E-region irregularities, observations with auroral radars, plasma drifts associated with a westward travelling surge, and ionospheric plasma motions associated with resonant waves. It is shown why high latitude F-region irregularity studies must be made in the HF frequency band (3-30 MHz). The joint use of the European Incoherent Scatter Association (EISCAT), STARE and SAFARI facilities is examined, and it is concluded that the various techniques will enhance each other and provide a better understanding of the various processes being studied

Energetics and structure of the lower E region associated with sporadic E layer

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K.-I. Oyama

2008-09-01

Full Text Available The electron temperature (T_e, electron density (N_e, and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (E_s at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from N_e and T_e shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of E_s, that was drawn by using T_e, N_e, and the electric field data, corresponded to the computer simulation; the main structure of E_s is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of T_e, N_e and electric field in higher altitude.

Common volume coherent and incoherent scatter radar observations of mid-latitude sporadic E-layers and QP echoes

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D. L. Hysell

2004-09-01

Full Text Available Common-volume observations of sporadic E-layers made on 14-15 June 2002 with the Arecibo incoherent scatter radar and a 30MHz coherent scatter radar imager located on St. Croix are described. Operating in dual-beam mode, the Arecibo radar detected a slowly descending sporadic E-layer accompanied by a series of dense E-region plasma clouds at a time when the coherent scatter radar was detecting quasi-periodic (QP echoes. Using coherent radar imaging, we collocate the sources of the coherent scatter with the plasma clouds observed by Arecibo. In addition to patchy, polarized scattering regions drifting through the radar illuminated volume, which have been observed in previous imaging experiments, the 30MHz radar also detected large-scale electrostatic waves in the E-region over Puerto Rico, with a wavelength of about 30km and a period of about 10min, propagating to the southwest. Both the intensity and the Doppler shifts of the coherent echoes were modulated by the wave.

A preliminary comparison of F region plasma drifts and E region irregularity drifts in the auroral zone

International Nuclear Information System (INIS)

Ecklund, W.L.; Balsley, B.B.; Carter, D.A.

1977-01-01

During several days in April--May 1976 the Chatanika, Alaska, incoherent scatter radar and a temporary Doppler auroral radar located at Aniak, Alaska, were directed toward ionospheric volumes along a common magnetic field line in order to compare E region and F region drifts and associated electric fields. The Chatanika radar measured F region plasma drifts via the incoherent scatter technique, while the Aniak radar measured the drifts of E region irregularities (i.e., the radar aurora). The radar geometry was arranged so that both radars measured approximately the same velocity component of a magnetically westward or eastward motion. Preliminary data show good agreement between the drift velocity components measured by the two techniques during most of the experimental period. This result indicates that relatively modest auroral radar systems may be used, with some qualifications, to determine auroral electric fields

Rocket in situ observation of equatorial plasma irregularities in the region between E and F layers over Brazil

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S. Savio Odriozola

2017-03-01

Full Text Available A two-stage VS-30 Orion rocket was launched from the equatorial rocket launching station in Alcântara, Brazil, on 8 December 2012 soon after sunset (19:00 LT, carrying a Langmuir probe operating alternately in swept and constant bias modes. At the time of launch, ground equipment operated at equatorial stations showed rapid rise in the base of the F layer, indicating the pre-reversal enhancement of the F region vertical drift and creating ionospheric conditions favorable for the generation of plasma bubbles. Vertical profiles of electron density estimated from Langmuir probe data showed wave patterns and small- and medium-scale plasma irregularities in the valley region (100–300 km during the rocket upleg and downleg. These irregularities resemble those detected by the very high frequency (VHF radar installed at Jicamarca and so-called equatorial quasi-periodic echoes. We present evidence suggesting that these observations could be the first detection of this type of irregularity made by instruments onboard a rocket.

Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

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Moro, J.; Resende, L. C. A.; Denardini, C. M.; Xu, J.; Batista, I. S.; Andrioli, V. F.; Carrasco, A. J.; Batista, P. P.; Schuch, N. J.

2017-12-01

Equatorial E region electric fields (EEFs) inferred from coherent radar data, sporadic-E (Es) layers observed from a digital ionosonde data, and modeling results are used to study the responses of the equatorial E region over São Luís (SLZ, 2.3°S, 44.2°W, -7° dip angle), Brazil, during the super storm of November 2004. The EEF is presented in terms of the zonal (Ey) and vertical (Ez) components in order to analyze the corresponding characteristics of different types of Es seen in ionograms and simulated with the E region ionospheric model. We bring out the variabilities of Ey and Ez components with storm time changes in the equatorial E region. In addition, some aspects of the electric fields and Es behavior in three cases of weak, very weak, and strong Type II occurrences during the recovery phase of the geomagnetic storm are discussed. The connection between the enhanced occurrence and suppressions of the Type II irregularities and the q-type Es (Esq) controlled by electric fields, with the development or disruption of the blanketing sporadic E (Esb) layers produced by wind shear mechanism, is also presented. The mutual presence of Esq along with the Esb occurrences is a clear indicator of the secular drift of the magnetic equator and hence that of the equatorial electrojet (EEJ) over SLZ. The results show evidence about the EEJ and Es layer electrodynamics and coupling during geomagnetic disturbance time electric fields.

Study of electromagnetic wave scattering by periodic density irregularities in plasma

International Nuclear Information System (INIS)

Lyle, R.; Kuo, S.P.; Huang, J.

1995-01-01

A quasi-particle approach is used to formulate wave propagation and scattering in a periodically structured plasma. The theory is then applied to study the effect of bottomside sinusoidal (BSS) irregularities on the propagation of beacon satellites signals through the ionosphere. In this approach, the radio wave is treated as a distribution of quasi-particles described by a Wigner distribution function governed by a transport equation. The irregularities providing the collisional effect are modeled as a two dimensional density modulation on a uniform background plasma. The present work generalizes the previous work by including the spectral bandwidth (Δk/k) effect of the spatially periodic irregularities on the transionospheric signal propagation. The collision of quasi-particles with the irregularities modifies the quasi-particle distribution and give rise to the wave scattering phenomenon. The multiple scattering process is generally considered in this deterministic analysis of radio wave scattering off the ionospheric density irregularities. The analysis shows that this two dimensional density grating effectively modulates the intensity of the beacon satellite signals. This spatial modulation of the wave intensity is converted into time modulation due to the drift of the ionospheric irregularities, which then results in the scintillation of the beacon satellite signals

Energetics and structure of the lower E region associated with sporadic E layer

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K.-I. Oyama

2008-09-01

Full Text Available The electron temperature (Te, electron density (Ne, and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (Es at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from Ne and Te shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of Es, that was drawn by using Te, Ne, and the electric field data, corresponded to the computer simulation; the main structure of Es is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of Te, Ne and electric field in higher altitude.

In-Situ Measurement of Ionospheric E-Region Plasma Irregularities over Taiwan

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Chi-Kuang Chao

2012-01-01

Full Text Available One ion trap (IT and one retarding potential analyzer (RPA onboard the Taiwan Sounding Rocket V (SR-V were launched to measure ionospheric plasma irregularities on 18 January 2006. After the fairing separated, voltage readings (VG1 of the first grid (G1 in the IT indicated abnormally high negative voltages appeared at the upleg between 83.7 and 120.1 km altitude for 19.7 seconds. It is postulated G1 had temporarily shorted out with the other two grids. Such the anomaly in the VG1 brought out the expansion of a plasma sheath around opening of the IT. More ions were attracted into the collector. Remarkable ion currents detected by the IT led to malfunctions of the RPA simultaneously. In this article, laboratory simulations and the International Reference Ionosphere model are performed to evaluate scale factors for the IT to the anomaly. The calibrated total ion concentration profile at the upleg indicates a peak density of the Es layer at 93.0 km altitude of about 6.9 × 103 # cm-3 with a thickness of 3.4 km. It is very similar to that at the downleg. It implies that the SR-V might encounter the same Es layer twice in a distance of 150 km away.

Case study of inclined sporadic E layers in the Earth's ionosphere observed by CHAMP/GPS radio occultations: Coupling between the tilted plasma layers and internal waves

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Gubenko, Vladimir N.; Pavelyev, A. G.; Kirillovich, I. A.; Liou, Y.-A.

2018-04-01

We have used the radio occultation (RO) satellite data CHAMP/GPS (Challenging Minisatellite Payload/Global Positioning System) for studying the ionosphere of the Earth. A method for deriving the parameters of ionospheric structures is based upon an analysis of the RO signal variations in the phase path and intensity. This method allows one to estimate the spatial displacement of a plasma layer with respect to the ray perigee, and to determine the layer inclination and height correction values. In this paper, we focus on the case study of inclined sporadic E (Es) layers in the high-latitude ionosphere based on available CHAMP RO data. Assuming that the internal gravity waves (IGWs) with the phase-fronts parallel to the ionization layer surfaces are responsible for the tilt angles of sporadic plasma layers, we have developed a new technique for determining the parameters of IGWs linked with the inclined Es structures. A small-scale internal wave may be modulating initially horizontal Es layer in height and causing a direction of the plasma density gradient to be rotated and aligned with that of the wave propagation vector k. The results of determination of the intrinsic wave frequency and period, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase speeds, and other characteristics of IGWs under study are presented and discussed.

Numerical Simulation of the Time Evolution of Small-Scale Irregularities in the F-Layer Ionospheric Plasma

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O. V. Mingalev

2011-01-01

Full Text Available Dynamics of magnetic field-aligned small-scale irregularities in the electron concentration, existing in the F-layer ionospheric plasma, is investigated with the help of a mathematical model. The plasma is assumed to be a rarefied compound consisting of electrons and positive ions and being in a strong, external magnetic field. In the applied model, kinetic processes in the plasma are simulated by using the Vlasov-Poisson system of equations. The system of equations is numerically solved applying a macroparticle method. The time evolution of a plasma irregularity, having initial cross-section dimension commensurable with a Debye length, is simulated during the period sufficient for the irregularity to decay completely. The results of simulation indicate that the small-scale irregularity, created initially in the F-region ionosphere, decays accomplishing periodic damped vibrations, with the process being collisionless.

The Role of Iron In Sporadic E Layers

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Vondrak, T.; Woodcock, K. R. I.; Plane, J. M. C.

Sporadic E layers in the lower thermosphere are mostly composed of metallic ions, of which Fe+ is the most abundant. Because dielectric recombination (Fe+ + elec- tron) is very slow, the lifetime of Fe+ above about 100 km is at least several days. However, below this height molecular ions such as FeO+, FeO2+ and FeN2+ form in- creasingly rapidly through reactions with O3, O2 and N2, respectively. These undergo rapid dissociative recombination with electrons, causing Fe+ to be neutralised increas- ingly rapidly as a sporadic E layer descends. Indeed, this is the most likely mechanism for the formation of the sporadic neutral Fe layers that are observed by lidar. However, atomic O plays a very important role in reducing these molecular ions back to Fe+, competing with dissociative recombination and thus slowing the rate at which Fe+ is neutralised and a sporadic E layer dissipates. This paper will discuss a laboratory and modelling study of the reactions of FeO+, FeO2+ and FeN2+ with atomic O. These reactions were studied (for the first time) in a fast flow tube, using the pulsed laser ablation of a rotating iron rod as the source of Fe+ ions in the upstream section of the tube. Reactants were then added to produce molecular ions, and atomic O further downstream through a movable injector. Fe+ and the molecular ions were detected at the downstream end of the tube using a two-stage quadrupole mass spectrometer. The spectroscopy of the FeO+ ion, observed by laser induced fluorescence, will also be discussed as a candidate for future ground-based lidar studies of the ion chemistry of the lower thermosphere.

Observations of neutral winds, wind shears, and wave structure during a sporadic-E/QP event

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M. F. Larsen

2005-10-01

Full Text Available The second Sporadic E Experiment over Kyushu (SEEK-2 was carried out on 3 August 2002, during an active sporadic-E event that also showed quasi-periodic (QP echoes. Two rockets were launched into the event from Kagoshima Space Center in southern Japan 15 min apart. Both carried a suite of instruments, but the second rocket also released a trimethyl aluminum (TMA trail to measure the neutral winds and turbulence structure. In a number of earlier measurements in similar conditions, large winds and shears that were either unstable or close to instability were observed in the altitude range where the ionization layer occurred. The SEEK-2 wind measurements showed similar vertical structure, but unlike earlier experiments, there was a significant difference between the up-leg and down-leg wind profiles. In addition, wave or billow-like fluctuations were evident in the up-leg portion of the trail, while the lower portion of the down-leg trail was found to have extremely strong turbulence that led to a rapid break-up of the trail. The large east-west gradient in the winds and the strong turbulence have not been observed before. The wind profiles and shears, as well as the qualitative characteristics of the strong turbulence are presented, along with a discussion of the implications of the dynamical features. Keywords. Ionosphere (Mid-latitude ionosphere; Ionospheric irregularities; Electric field and currents

The structure of plasma-density irregularities in the interplanetary medium

International Nuclear Information System (INIS)

Singleton, D.G.

1975-01-01

The conflict in the literature as to whether the plasma-density spatial spectrum of the irregularities in the interplanetary medium is of Gaussian or power law form is discussed. Particular attention is paid to the interplanetary scintillation effects ascribed to these irregularities. It is shown that the phase-screen theory of scintillations can be invoked to devise a set of critical tests which provide a means of discriminating between the conflicting hypotheses. Differences in the predicted behaviour of the single sensor temporal spectra of the scintillations for the two irregularity forms provide the main tests of the conflicting hypotheses. However, it is also shown that the two hypotheses lead to different forms of the variation of scintillation index with the observing frequency and the solar elongation of the scintillating source. Consideration is given to the optimum conditions for observing the Fourier and Bessel temporal spectra modulation which is due to the Fresnel filtering of the spatial spectrum. Determination of irregularity shape, orientation and motion in terms of this modulation is also discussed. (author)

Ionospheric Storm Effects and Equatorial Plasma Irregularities During the 17-18 March 2015 Event

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Zhou, Yun-Liang; Luhr, Hermann; Xiong, Chao; Pfaff, Robert F.

2016-01-01

The intense magnetic storm on 17-18 March 2015 caused large disturbances of the ionosphere. Based on the plasma density (Ni) observations performed by the Swarm fleet of satellites, the Gravity Recovery and Climate Experiment mission, and the Communications/Navigation Outage Forecasting System satellite, we characterize the storm-related perturbations at low latitudes. All these satellites sampled the ionosphere in morning and evening time sectors where large modifications occurred. Modifications of plasma density are closely related to changes of the solar wind merging electric field (E (sub m)). We consider two mechanisms, prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF), as the main cause for the Ni redistribution, but effects of meridional wind are also taken into account. At the start of the storm main phase, the PPEF is enhancing plasma density on the dayside and reducing it on the nightside. Later, DDEF takes over and causes the opposite reaction. Unexpectedly, there appears during the recovery phase a strong density enhancement in the morning/pre-noon sector and a severe Ni reduction in the afternoon/evening sector, and we suggest a combined effect of vertical plasma drift, and meridional wind is responsible for these ionospheric storm effects. Different from earlier studies about this storm, we also investigate the influence of storm dynamics on the initiation of equatorial plasma irregularities (EPIs). Shortly after the start of the storm main phase, EPIs appear in the post-sunset sector. As a response to a short-lived decline of E (sub m), EPI activity appears in the early morning sector. Following the second start of the main phase, EPIs are generated for a few hours in the late evening sector. However, for the rest of the storm main phase, no more EPIs are initiated for more than 12 hours. Only after the onset of recovery phase does EPI activity start again in the post-midnight sector, lasting more than 7 hours

Thunderstorm related variations of the ionospheric sporadic E layer over Rome

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Barta, Veronika; Scotto, Carlo; Pietrella, Marco

2013-04-01

Meteorological events in the lower atmosphere can affect the ionosphere by electromagnetic and mechanical processes. One type of the latter ones is the internal atmospheric gravity waves (AGWs) which can often be generated by thunderstorms. According to a Superposed Epoch Analyses (SEA) using the time series of the critical frequency (foEs) and virtual height (h'Es) of the sporadic E layer and WWLLN (World Wide Lightning Location Network) lightning data over the ionospheric station of Rome (41.9° 12.5°) there is a statistically significant decrease in the foEs of the sporadic E layer after the time of the lightnings. This may indicate a sudden decrease in the electron density of the sporadic E layer associated to lightnings. In order to understand the physical explanation for this phenomenon further studies are performed as follows: a SEA for different seasons and for daytime - nightime lightnings separately. Direction of arrival of thunderstorms is also taken into account.

Magnetic eta index and the ability to forecast sporadic E layer appearance

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Dziak-Jankowska, Beata; Stanislawska, Iwona; Pozoga, Mariusz; Tomasik, Lukasz; Ernst, Tomasz

2012-07-01

We analysed the correlation of the changes of the magnetic vertical component with the ionospheric deviations from monthly median of the E layer characteristics. Promising results indicate that the eta parameter can be used to predict sporadic E layer during magnetically quiet days. Our previous work concern the data from only one year - 2004. During the descending phase of solar cycle in 2004 there was not numerous amount of quiet days. We extend our research to other years starting from 1996 and focusing on 2007 - 2009, years of the prolonged solar minimum. The analysis shows that under magnetically quiet circumstances the magnetic index eta indicates large magnetic disturbance, especially in vertical component when other magnetic indices inform about quiet magnetic conditions. The results indicate that the increase of the magnetic eta index (the ratio of the variations of vertical component of the external magnetic field to the horizontal component) is associated with the emergence of sporadic E layer or with increase of foEs critical frequency of sporadic E layer. The appearance of sporadic E layer followed 1-2 h after growth of magnetic index eta. An important conclusion is that the analysis of the hourly ionospheric data does not give 100% correlation between the increase of eta and the emergence of Es layer, however, studies of dense measurement data show that the correlation is almost 100%. An advantage of the eta index is the fact that after eliminating the effect of currents induced within the Earth, eta index bring independent and meaningful information on the system of current in the ionosphere. Hence, the eta index could be an important element of the ionosphere monitoring and can be used to predict such local phenomenon like the appearance of the sporadic E layer.

Sporadic potassium layers and their connection to sporadic E layers in the mesopause region at Beijing, China

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Jing Jiao

2017-06-01

Full Text Available A double-laser beam lidar to measure potassium (K layer at Beijing (40.5° N, 116.2° E was successfully developed in 2010. The parameters of sporadic Ks layers and their distributions were given. The seasonal distribution of Ks occurrence frequency was obtained, with two maxima in July and January. The seasonal distributions of sporadic Es layer occurrence frequency over Beijing differ from those of Ks. However, the good correlation between Es and Ks in the case-by-case studies supports the mechanism of neutralization of metal ions in a descending Es layer.

Observation of electron biteout regions below sporadic E layers at polar latitudes

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G. A. Lehmacher

2015-03-01

Full Text Available The descent of a narrow sporadic E layer near 95 km altitude over Poker Flat Research Range in Alaska was observed with electron probes on two consecutive sounding rockets and with incoherent scatter radar during a 2 h period near magnetic midnight. A series of four trimethyl aluminum chemical releases demonstrated that the Es layer remained just slightly above the zonal wind node, which was slowly descending due to propagating long-period gravity waves. The location of the layer is consistent with the equilibrium position due to combined action of the wind shear and electric fields. Although the horizontal electric field could not be measured directly, we estimate that it was ~ 2 mV m−1 southward, consistent with modeling the vertical ion drift, and compatible with extremely quiet conditions. Both electron probes observed deep biteout regions just below the Es enhancements, which also descended with the sporadic layers. We discuss several possibilities for the cause of these depletions; one possibility is the presence of negatively charged, nanometer-sized mesospheric smoke particles. Such particles have recently been detected in the upper mesosphere, but not yet in immediate connection with sporadic E. Our observations of electron depletions suggest a new process associated with sporadic E.

Analysis of Mid-Latitude Plasma Density Irregularities in the Presence of Finite Larmor Radius Effects

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Sotnikov, V. I.; Kim, T. C.; Mishin, E. V.; Kil, H.; Kwak, Y. S.; Paraschiv, I.

2017-12-01

Ionospheric irregularities cause scintillations of electromagnetic signals that can severely affect navigation and transionospheric communication, in particular during space storms. At mid-latitudes the source of F-region Field Aligned Irregularities (FAI) is yet to be determined. They can be created in enhanced subauroral flow channels (SAI/SUBS), where strong gradients of electric field, density and plasma temperature are present. Another important source of FAI is connected with Medium-scale travelling ionospheric disturbances (MSTIDs). Related shear flows and plasma density troughs point to interchange and Kelvin-Helmholtz type instabilities as a possible source of plasma irregularities. A model of nonlinear development of these instabilities based on the two-fluid hydrodynamic description with inclusion of finite Larmor radius effects will be presented. This approach allows to resolve density irregularities on the meter scale. A numerical code in C language to solve the derived nonlinear equations for analysis of interchange and flow velocity shear instabilities in the ionosphere was developed. This code will be used to analyze competition between interchange and Kelvin-Helmholtz instabilities in the mid-latitude region. The high-resolution simulations with continuous density and velocity profiles will be driven by the ambient conditions corresponding to the in situ data obtained during the 2016 Daejeon (Korea) and MU (Japan) radar campaign and data collected simultaneously by the Swarm satellites passed over Korea and Japan. PA approved #: 88ABW-2017-3641

A multi-platform investigation of midlatitude sporadic E and its ties to E–F coupling and meteor activity

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J. Helmboldt

2016-05-01

Full Text Available This paper describes the results of a multi-platform observing campaign aimed at studying midlatitude sporadic E (Es and associated ionospheric phenomena. The assets used were the digisonde in Boulder, Colorado; the first station of the Long Wavelength Array, LWA1, in New Mexico; the transmitters of the radio station WWV in Colorado; and 61 continuously operating GPS receivers between LWA1 and WWV. The results show that southwestward-directed medium-scale traveling ionospheric disturbances (MSTIDs were substantially more prevalent when Es was detected. The amplitudes of these correlate with a plasma frequency up to about 4.5 MHz. For fp ≳ 5 MHz, the MSTIDs become significantly weaker and basically vanish above  ∼ 6.5 MHz. The prevalence of meteor trail reflections observed with LWA1 also correlates with fp up to about 4.5 MHz; above this limit, the relationship exhibits a significant turnover. The observed intensity of coherent backscatter from Es field-aligned irregularities (FAIs also correlates with inferred plasma frequency. However, this trend continues to higher frequencies with a peak near 6 MHz, followed by a much more subtle turnover. The reflected power from Es structures observed with LWA1 is significantly more correlated on spatial scales between 10 and 40 km. The magnitude of this correlation increases with fp up to  ∼  6 MHz, above which it drops. These results are consistent with the following: (1 southwestward-directed MSTIDs are produced via E–F coupling; (2 this coupling is stronger when the Es layer, seeded by meteor ablation, is more dense; (3 the coupling is substantially diminished for Es layers harboring extremely dense structures (fp ≳ 5 MHz.

Multi-layer structure of mid-latitude sporadic-E observed during the SEEK-2 campaign

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T. Ono

2005-10-01

Full Text Available In the mid-latitude ionospheric region, sporadic-E layers (Es layers have often been observed, revealing multiple layers. The Es layers observed during the SEEK-2 rocket campaign showed double electron density peaks; namely, there are stable lower peaks and relatively unstable upper peaks. We examined the effects of wind shear and the electric fields on the generation of the multiple layer structure, in comparison with the electron density profile, the neutral wind, and the DC electric field observed by the S310 rocket experiments. The results showed that the neutral wind shear is mainly responsible for the generation of the lower layer, while the DC electric field makes a significant contribution to the formation of the upper layer. The difference between the lower and upper layers was also explained by the enhanced AC electric field observed at about 103–105 km altitude. The external DC electric field intensity is expected to be ~5 mV/m, which is enough to contribute to generate the Es layers in the ionosphere. Keywords. Ionosphere (Electric fields; Ionospheric irregularities, Mid-latitude ionosphere

Electric Field and Plasma Density Observations of Irregularities and Plasma Instabilities in the Low Latitude Ionosphere Gathered by the C/NOFS Satellite

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Pfaff, Robert F.; Freudenreich, H.; Rowland, D.; Klenzing, J.; Liebrecht, C.

2012-01-01

The Vector Electric Field Investigation (VEFI) on the C/NOFS equatorial satellite provides a unique data set which includes detailed measurements of irregularities associated with the equatorial ionosphere and in particular with spread-F depletions. We present vector AC electric field observations gathered on C/NOFS that address a variety of key questions regarding how plasma irregularities, from meter to kilometer scales, are created and evolve. The talk focuses on occasions where the ionosphere F-peak has been elevated above the C/NOFS satellite perigee of 400 km as solar activity has increased. In particular, during the equinox periods of 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set: The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second result is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is near or below the F-peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field

Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere

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Mošna, Z.; Koucká Knížová, P.

2012-12-01

The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.

Radar observations of artificial E-region field-aligned irregularities

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E. Nossa

2009-07-01

Full Text Available Artificial E region field aligned plasma density irregularities (FAIs were generated using HAARP in four different experimental modes and observed with a coherent scatter radar imager located 450 km to the southwest where it could detect field-aligned backscatter. The experiments were conducted in July of 2008, during the Polar Aeronomy and Radio Science Summer School (PARS, during quiet conditions in the daytime when the E layer was dense and absorption was modest. The echoes observed during zenith and magnetic zenith heating experiments were deflected from their nominally anticipated horizontal positions toward the midpoint position. The occurrence of hysteresis when heating with amplitude modulated pulses implied the development of the resonance instability, although the threshold for the onset of instability appeared to be higher than what has been predicted theoretically. Heating experiments involving pump frequencies slightly above and below the second electron gyroharmonic frequency produced no significant differences in the observed echoes. Finally, heating with a pump frequency slightly above the E region critical frequency appears to have produced FAIs at two distinct altitudes where the upper-hybrid resonance condition could be satisfied.

Electrostatic lower hybrid waves excited by electromagnetic whistler mode waves scattering from planar magnetic-field-aligned plasma density irregularities

International Nuclear Information System (INIS)

Bell, T.F.; Ngo, H.D.

1990-01-01

Recent satellite observations demonstrate that high amplitude, short wavelength (5 m ≤ λ ≤ 100 m) electrostatic waves are commonly excited by electromagnetic whistler mode waves propagating in regions of the magnetosphere and topside ionosphere where small-scale magnetic-field-aligned plasma density irregularities are thought to exist. A new theoretical model of this phenomenon is presented, based upon passive linear scattering in a cold magnetoplasma. In this model the electrostatic waves are excited by linear mode coupling as the incident electromagnetic whistler mode waves scatter from the magnetic-field-aligned plasma density irregularities. The excited short wavelength waves are quasi-electrostatic whistler mode waves, a type of lower hybrid wave, whose wave normal lies near the whistler mode resonance cone where the wave refractive index becomes very large. The amplitude of the excited electrostatic lower hybrid waves is calculated for a wide range of values of input electromagnetic wave frequency, wave normal direction, electron plasma frequency, gyrofrequency, ion composition, and irregularity scale and density enhancement. Results indicate that high amplitude lower hybrid waves can be excited over a wide range of parameters for irregularity density enhancements as low as 5% whenever the scale of the irregularity is of the same order as the lower hybrid wavelength

Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

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H. Chandra

2001-01-01

Full Text Available Rapid radio soundings were made over Ahmedabad, a low latitude station during the period 16–20 November 1998 to study the sporadic-E layer associated with the Leonid shower activity using the KEL Aerospace digital ionosonde. Hourly ionograms for the period 11 November to 24 November were also examined during the years from 1994 to 1998. A distinct increase in sporadic-E layer occurrence is noticed on 17, 18 and 19 November from 1996 to 1998. The diurnal variations  of  f0Es and fbEs also show significantly enhanced values for the morning hours of 18 and 19 November 1998. The ionograms clearly show strong sporadic-E reflections at times of peak shower activity with multiple traces in the altitude range of 100–140 km in few ionograms. Sporadic-E layers with multiple structures in altitude are also seen in some of the ionograms (quarter hourly at Thumba, situated near the magnetic equator. Few of ionograms recorded at Kodaikanal, another equatorial station, also show sporadic- E reflections in spite of the transmitter power being significantly lower. These new results highlighting the effect of intense meteor showers in the equatorial and low latitude E-region are presented.Key words. Ionosphere (equatorial ionosphere – Radio science (ionospheric physics

Allele doses of apolipoprotein E type {epsilon}4 in sporadic late-onset Alzheimer`s disease

Energy Technology Data Exchange (ETDEWEB)

Lucotte, G.; Aouizerate, A.; Gerard, N. [Regional Center of Neurogenetics, Paris (France)] [and others

1995-12-18

Apoliprotein E, type {epsilon}4 allele (ApoE-{epsilon}4) is associated with late-onset sporadic Alzheimer`s disease (AD). We have found that the cumulative probability of remaining unaffected over time decreases for each dose of ApoE-{epsilon}4 in sporadic, late-onset French AD. The effect of genotypes on age at onset of AD was analyzed using the product limit method, to compare unaffected groups during aging. 26 refs., 2 figs., 1 tab.

Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

Directory of Open Access Journals (Sweden)

H. Chandra

Full Text Available Rapid radio soundings were made over Ahmedabad, a low latitude station during the period 16–20 November 1998 to study the sporadic-E layer associated with the Leonid shower activity using the KEL Aerospace digital ionosonde. Hourly ionograms for the period 11 November to 24 November were also examined during the years from 1994 to 1998. A distinct increase in sporadic-E layer occurrence is noticed on 17, 18 and 19 November from 1996 to 1998. The diurnal variations 
of  f₀E_s and f_bE_s also show significantly enhanced values for the morning hours of 18 and 19 November 1998. The ionograms clearly show strong sporadic-E reflections at times of peak shower activity with multiple traces in the altitude range of 100–140 km in few ionograms. Sporadic-E layers with multiple structures in altitude are also seen in some of the ionograms (quarter hourly at Thumba, situated near the magnetic equator. Few of ionograms recorded at Kodaikanal, another equatorial station, also show sporadic- E reflections in spite of the transmitter power being significantly lower. These new results highlighting the effect of intense meteor showers in the equatorial and low latitude E-region are presented.

Key words. Ionosphere (equatorial ionosphere – Radio science (ionospheric physics

Morphological study of the field-aligned E-layer irregularities observed by the Gadanki VHF radar

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C. J. Pan

2004-11-01

Full Text Available We report on the field-aligned irregularities observed in the low-latitude sporadic E-layer (Es with the Gadanki (13.5° N, 79.2° E; geomagnetic latitude 6.3° N VHF radar. The radar was operated intermittently for 15 days during the summer months in 1998 and 1999, for both daytime and nighttime observation. The total observation periods are 161h for the nighttime and 68h for the daytime. The observations were used to study the percentage of occurrence of the E-region echoes for both daytime and nighttime. The statistical characteristics of the mean radial velocity and spectral width are presented for three cases based on the echo occurrence characteristics and the altitude of observations (from 90 to 140km ranges, namely, the lower E-region daytime (90-110km, the lower E-region nighttime (90-105km and the upper E-region nighttime (105-140km echoes. The results are compared with that of Piura, a low-latitude station located at about the same geomagnetic latitude, but to the south of the equator. By comparing the behaviors of the lower E-region radar echoes of the summer months between Gadanki and Piura, we find that the lower altitude echoes below about 100km are rarely reported in Piura but commonly seen in Gadanki. Features of the nighttime echoes observed by these two radars are quite similar but daytime FAI echoes are again seldom detected by Piura.

Observations of peculiar sporadic sodium structures and their relation with wind variations

Science.gov (United States)

Sridharan, S.; Prasanth, P. Vishnu; Kumar, Y. Bhavani; Ramkumar, Geetha; Sathishkumar, S.; Raghunath, K.

2009-04-01

Resonance lidar observations of sodium density in the upper mesosphere region over Gadanki (13.5°N, 79.2°E) rarely show complex structures with rapid enhancements of sodium density, completely different from normal sporadic sodium structures. The hourly averaged meteor radar zonal winds over Trivandrum (8.5°N, 76.5°E) show an eastward shear with altitude during the nights, when these events are formed. As suggested by Kane et al. [2001. Joint observations of sodium enhancements and field-aligned ionospheric irregularities. Geophysical Research Letters 28, 1375-1378], our observations show that the complex structures may be formed due to Kelvin-Helmholtz instability, which can occur in the region of strong wind shear.

Characteristics of low latitude ionospheric E-region irregularities ...

Indian Academy of Sciences (India)

154°E, dip angle = 37.3°, sub-ionospheric dip = 34°) have been analyzed to study the behaviour of ionospheric E-region irregularities during the active solar and magnetic periods. The autocorrelation functions, power spectral densities, signal de-correlation times are computed to study the temporal features of ionospheric ...

Irregular water supply, household usage and dengue: a bio-social study in the Brazilian Northeast Abastecimento irregular de água, seu uso domiciliar e dengue: uma pesquisa biossocial no Nordeste do Brasil

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Andrea Caprara

2009-01-01

Full Text Available Despite increased vector control efforts, dengue fever remains endemic in Fortaleza, Northeast Brazil, where sporadic epidemic outbreaks have occurred since 1986. Multiple factors affect vector ecology such as social policy, migration, urbanization, city water supply, garbage disposal and housing conditions, as well as community level understanding of the disease and related practices. This descriptive study used a multi-disciplinary approach that bridged anthropology and entomology. A multiple case study design was adopted to include research in six study areas, defined as blocks. The water supply is irregular in households from both under-privileged and privileged areas, however, clear differences exist. In the more privileged blocks, several homes are not connected to the public water system, but have a well and pump system and therefore irregularity of supply does not affect them. In households from under-privileged blocks, where the water supply is irregular, the frequent use of water containers such as water tanks, cisterns, barrels and pots, creates environmental conditions with a greater number of breeding areas. In under-privileged homes, there are more possible breeding areas and environmental conditions that may improve the chances of Aedes aegypti survival.Apesar do crescimento de esforços no controle, desde 1986, a dengue, em Fortaleza, Nordeste do Brasil, continua endêmica com esporádicos surtos epidêmicos. Diversos fatores influenciam a ecologia do vetor, como as políticas sociais, a migração, a urbanização, o abastecimento urbano de água, a coleta de resíduos sólidos, as condições das casas, assim como as interpretações e práticas da comunidade. Este estudo descritivo utiliza uma abordagem multidisciplinar conjugando a antropologia e a entomologia. Foi adotado um desenho de estudo de caso múltiplo em seis quarteirões da cidade. O abastecimento de água é irregular seja nas casas pobres, seja naquelas

Comparison between the ionospheric plasma drift and the motion of artificially induced irregularities as observed by HF backscatter radars

International Nuclear Information System (INIS)

Hanuise, C.; Hedberg, A.; Oksman, J.; Nielsen, E.; Stubbe, P.; Kopka, H.

1986-01-01

Theories of striation generation by powerful HF waves state that the irregularities should convect with the plasma, without propagating through the medium. This prediction has been checked by observing, with the two SAFARI radars, the backscatter from striations generated in the F-region by the HEATING facility at Tromso. The magnitude and direction of the Doppler velocity of the fluctuations is derived from the line-of-sight velocities measured by the two HF radar stations. The comparison between the electric field, derived from SAFARI, and the E-region current deduced from magnetometer data show that the magnitudes are well correlated. The directions of the velocity and this current are, however, not exactly antiparallel. Another comparison between the SAFARI F-region Doppler velocity and the E-region drift measured by STARE shows, on the average, a good agreement between the estimates. The experimental evidence therefore agrees with the theoretical suggestion that the irregularity motion should be the ExB drift

On a new process for cusp irregularity production

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H. C. Carlson

2008-09-01

Full Text Available Two plasma instability mechanisms were thought until 2007 to dominate the formation of plasma irregularities in the F region high latitude and polar ionosphere; the gradient-drift driven instability, and the velocity-shear driven instability. The former mechanism was accepted as accounting for plasma structuring in polar cap patches, the latter for plasma structuring in polar cap sun aligned arcs. Recent work has established the need to replace this view of the past two decades with a new patch plasma structuring process (not a new mechanism, whereby shear-driven instabilities first rapidly structure the entering plasma, after which gradient drift instabilities build on these large "seed" irregularities. Correct modeling of cusp and early polar cap patch structuring will not be accomplished without allowing for this compound process. This compound process explains several previously unexplained characteristics of cusp and early polar cap patch irregularities. Here we introduce additional data, coincident in time and space, to extend that work to smaller irregularity scale sizes and relate it to the structured cusp current system.

Scintillations associated with bottomside sinusoidal irregularities in the equatorial F region

Science.gov (United States)

Basu, S.; Basu, S.; Valladares, C. E.; Dasgupta, A.; Whitney, H. E.

1986-01-01

Multisatellite scintillation observations and spaced receiver drift measurements are presented for a category of equatorial F region plasma irregularities characterized by nearly sinusoidal waveforms in the ion number density. The observations were made at Huancayo, Peru, and the measurements at Ancon, Peru, associated with irregularities observed by the Atmospheric-Explorer-E satellite on a few nights in December 1979. Utilizing ray paths to various geostationary satellites, it was found that the irregularities grow and decay almost simultaneously in long-lived patches extending at least 1000 km in the east-west direction.

Aspect sensitive E- and F-region SPEAR-enhanced incoherent backscatter observed by the EISCAT Svalbard radar

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R. S. Dhillon

2009-01-01

Full Text Available Previous studies of the aspect sensitivity of heater-enhanced incoherent radar backscatter in the high-latitude ionosphere have demonstrated the directional dependence of incoherent scatter signatures corresponding to artificially excited electrostatic waves, together with consistent field-aligned signatures that may be related to the presence of artificial field-aligned irregularities. These earlier high-latitude results have provided motivation for repeating the investigation in the different geophysical conditions that obtain in the polar cap ionosphere. The Space Plasma Exploration by Active Radar (SPEAR facility is located within the polar cap and has provided observations of RF-enhanced ion and plasma line spectra recorded by the EISCAT Svalbard UHF incoherent scatter radar system (ESR, which is collocated with SPEAR. In this paper, we present observations of aspect sensitive E- and F-region SPEAR-induced ion and plasma line enhancements that indicate excitation of both the purely growing mode and the parametric decay instability, together with sporadic E-layer results that may indicate the presence of cavitons. We note consistent enhancements from field-aligned, vertical and also from 5° south of field-aligned. We attribute the prevalence of vertical scatter to the importance of the Spitze region, and of that from field-aligned to possible wave/irregularity coupling.

A survey of plasma irregularities as seen by the midlatitude Blackstone SuperDARN radar

Science.gov (United States)

Ribeiro, A. J.; Ruohoniemi, J. M.; Baker, J. B. H.; Clausen, L. B. N.; Greenwald, R. A.; Lester, M.

2012-02-01

The Super Dual Auroral Radar Network (SuperDARN) is a chain of HF radars that monitor plasma dynamics in the ionosphere. In recent years, SuperDARN has expanded to midlatitudes in order to provide enhanced coverage during geomagnetically active periods. A new type of backscatter from F region plasma irregularities with low Doppler velocity has been frequently observed on the nightside during quiescent conditions. Using three years of data from the Blackstone, VA radar, we have implemented a method for extracting this new type of backscatter from routine observations. We have statistically characterized the occurrence properties of the Sub Auroral Ionospheric Scatter (SAIS) events, including the latitudinal relationships to the equatorward edge of the auroral oval and the ionospheric projection of the plasmapause. We find that the backscatter is confined to local night, occurs on ≈70% of nights, is fixed in geomagnetic latitude, and is equatorward of both the auroral region and the plasmapause boundary. We conclude that SAIS irregularities are observed within a range of latitudes that is conjugate to the inner magnetosphere (plasmasphere).

Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

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D. V. Phanikumar

2008-07-01

Full Text Available In this paper, we present seasonal variation of E region field-aligned irregularities (FAIs observed using the Gadanki radar and compare them with the seasonal variation of E_s observed from a nearby location SHAR. During daytime, FAIs occur maximum in summer and throughout the day, as compared to other seasons. During nighttime, FAIs occur equally in both summer and winter, and relatively less in equinoxes. Seasonal variations of E_s (i.e. f_tE_s and f_bE_s show that the daytime activity is maximum in summer and the nighttime activity is maximum in equinoxes. No relation is found between FAIs occurrence/SNR and f_tE_s/f_bE_s. FAIs occurrence, however, is found to be related well with (f_tE_s−f_bE_s. This aspect is discussed in the light of the present understanding of the mid-latitude E_s-FAIs relationship. The seasonal variations of FAIs observed at Gadanki are compared in detail with those of Piura, which show a significant difference in the daytime observations. The observed difference has been discussed considering the factors governing the generation of FAIs.

Planetary and tidal wave-type oscillations in the ionospheric sporadic E layers over Tehran region

Science.gov (United States)

Karami, K.; Ghader, S.; Bidokhti, A. A.; Joghataei, M.; Neyestani, A.; Mohammadabadi, A.

2012-04-01

It is believed that in the lower ionosphere, particularly in the ionospheric sporadic E (Es) layers (90-130 km), the planetary and tidal wave-type oscillations in the ionized component indicate the planetary and tidal waves in the neutral atmosphere. In the present work, the presence of wave-type oscillations, including planetary and tidal waves in the ionospheric sporadic E layers over Tehran region is examined. Data measured by a digital ionosonde at the ionospheric station of the Institute of Geophysics, University of Tehran, from July 2006 to June 2007 are used to investigate seasonal variations of planetary and tidal waves activities. For the purpose of accurate comparison between different seasons, wavelet transform is applied to time series of foEs and h‧Es, namely, the critical frequency and virtual height of Es layers, respectively. The results show that the sporadic E layers over Tehran region are strongly under the influence of upward propagation of waves from below. More specifically, among diverse range of periodicities in the sporadic E layers, we found that diurnal (24 hours) and semidiurnal (12 hours) oscillations in all seasons for both parameters. Moreover, terdiurnal (8 hours) tide-like variation is observed during spring and summer for foEs parameter and summer and winter for h‧Es. Furthermore, the results show that diurnal tidal waves obtain their maximum activities during autumn and winter seasons, and their activities decrease during the late spring and summer. In addition, periods of about 2, 4, 6, 10, 14, and 16 days in our observation verifies the hypothesis of upward propagation of planetary waves from lower atmosphere to the ionosphere. Moreover, planetary waves have their maximum activities during equinox.

Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

Science.gov (United States)

Xiong, C.; Lühr, H.; Ma, S. Y.; Stolle, C.; Fejer, B. G.

2012-08-01

In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76-608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000-2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1). Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010). Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde

Directory of Open Access Journals (Sweden)

D. V. Phanikumar

2008-07-01

Full Text Available In this paper, we present seasonal variation of E region field-aligned irregularities (FAIs observed using the Gadanki radar and compare them with the seasonal variation of Es observed from a nearby location SHAR. During daytime, FAIs occur maximum in summer and throughout the day, as compared to other seasons. During nighttime, FAIs occur equally in both summer and winter, and relatively less in equinoxes. Seasonal variations of Es (i.e. ftEs and fbEs show that the daytime activity is maximum in summer and the nighttime activity is maximum in equinoxes. No relation is found between FAIs occurrence/SNR and ftEs/fbEs. FAIs occurrence, however, is found to be related well with (ftEs−fbEs. This aspect is discussed in the light of the present understanding of the mid-latitude Es-FAIs relationship. The seasonal variations of FAIs observed at Gadanki are compared in detail with those of Piura, which show a significant difference in the daytime observations. The observed difference has been discussed considering the factors governing the generation of FAIs.

Seasonal variability and descent of mid-latitude sporadic E layers at Arecibo

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N. Christakis

2009-03-01

Full Text Available Sporadic E layers (Es follow regular daily patterns in variability and altitude descent, which are determined primarily by the vertical tidal wind shears in the lower thermosphere. In the present study a large set of sporadic E layer incoherent scatter radar (ISR measurements are analyzed. These were made at Arecibo (Geog. Lat. ~18° N; Magnetic Dip ~50° over many years with ISR runs lasting from several hours to several days, covering evenly all seasons. A new methodology is applied, in which both weak and strong layers are clearly traced by using the vertical electron density gradient as a function of altitude and time. Taking a time base equal to the 24-h local day, statistics were obtained on the seasonal behavior of the diurnal and semidiurnal tidal variability and altitude descent patterns of sporadic E at Arecibo. The diurnal tide, most likely the S(1,1 tide with a vertical wavelength around 25 km, controls fully the formation and descent of the metallic Es layers at low altitudes below 110 km. At higher altitudes, there are two prevailing layers formed presumably by vertical wind shears associated mainly with semidiurnal tides. These include: 1 a daytime layer starting at ~130 km around midday and descending down to 105 km by local midnight, and 2 a less frequent and weaker nighttime layer which starts prior to midnight at ~130 km, descending downwards at somewhat faster rate to reach 110 km by sunrise. The diurnal and semidiurnal-like pattern prevails, with some differences, in all seasons. The differences in occurrence, strength and descending speeds between the daytime and nighttime upper layers are not well understood from the present data alone and require further study.

Seizures in E200K familial and sporadic Creutzfeldt-Jakob disease.

Science.gov (United States)

Appel, S; Chapman, J; Cohen, O S; Rosenmann, H; Nitsan, Z; Blatt, I

2015-03-01

Although seizures (other than myoclonus) are frequently reported in Creutzfeldt-Jakob disease (CJD), their frequency, clinical manifestations, and effect on the disease course is unknown. To characterize the frequency of seizures in E200K familial and sporadic CJD, to describe its semiology, EEG and MRI findings. In this retrospective study, we reviewed all patients with CJD who were seen in the Sheba Medical Center between the years 2003-2012 and underwent clinical evaluation, genetic testing, EEG and MRI studies. The diagnosis of seizures was carried out based on documentation of episodes consistent with seizures or episode of unresponsiveness correlated with ictal activity in EEG. Sixty-four probable patients with CJD were included in the study, 57 (89%) with E200K familial (fCJD) and 7 (11%) with sporadic (sCJD). Seizures occurred in 8 patients: 3 of 7 (43%) in patients with sCJD compared to 5/57 (9%) in patients with E200K fCJD (P = 0.04, chi-square test). Two of E200K fCJD patients with seizures had other non-prion etiologies for seizures (brain metastasis, known history of temporal lobe epilepsy which started 44 years before the diagnosis of CJD). Seizures occurred late in the course of the disease with an average of 12 days between the onset of seizures and death. Seizures in E200K fCJD were infrequent and occurred late in the disease course. This difference suggests that E200K fCJD represents a separate subtype of the disease with distinct clinical characteristics. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Multiple frequency radar observations of high-latitude E region irregularities in the HF modified ionosphere

International Nuclear Information System (INIS)

Noble, S.T.; Djuth, F.T.; Jost, R.J.

1987-01-01

In September 1983, experiments were conducted in Scandinavia using the high-power heating facility near Tromso, Norway. The purpose of the HF ionospheric modification experiments was to investigate the behavior of artificially produced E region irregularities at auroral latitudes. The majority of observations were made with backscatter radars operating at 46.9 and 143.8 MHz, but limited observations were also made at 21.4 and 140.0 MHz. These radars are sensitive to irregularities having scale lengths of between 1 and 7 m across the geomagnetic field lines. The growth and decay of the irregularities are scale length dependent with the shorter lengths growing and dissipating more rapidly than the longer lengths (e-folding growth times = 10 1 --10 2 ms; decay times = 10 2 --10 3 ms). During periods of full power ordinary mode heating, irregularities having peak cross sections of 10 4 m 2 at 46.9 MHz and 10 5 m 2 at 143.8 MHz are observed. However, the cross sections normally measured are 1 to 2 orders of magnitude smaller than the peak values. The cross sections are nonlinearly dependent on the HF power and begin to saturate at levels greater than 50--75 percent of full power. Past E and F region data from Arecibo are used in conjunction with the Tromso measurements to ascertain the relative roles played by various mechanisms in exciting irregularities. In the E region, the results tend to favor those instability processes which operate at the upper hybrid resonance level (e.g., thermal parametric and resonance instabilities) over those that operate at the reflection level (e.g., parametric decay instability). However, it is likely that anyh of the mechanisms studied could at times contribute to irregularity production in the E regions

Studies of sporadic E (Es) associated with the main ionospheric trough

International Nuclear Information System (INIS)

Rodger, A.S.; Morrell, C.; Dudeney, J.R.

1983-01-01

Sporadic E, or E(s) events under the main F region trough have been confirmed on the basis of ionograms from a vertical incidence ionosonde at Halley Bay, Antarctica. Analyses indicate that E(s) is frequently observable under both the equatorward and the poleward edges of the trough, as well as poleward of it. Before magnetic midnight, E(s) layers whose semithickness resembles those of the normal E layer are common, in contrast to layers seen after magnetic midnight which show the characteristics of thin E(s) layers. A possible explanation of the observed change in the E(s) layer characteristics at magnetic midnight is related to differences in the type and spectra of the precipitating particles. It is shown that the redistribution of ionization by the convection electric field may be important. 40 references

The formation of sporadic E layers by a vortical perturbation excited in a horizontal wind shear flow

Directory of Open Access Journals (Sweden)

G. G. Didebulidze

2008-06-01

Full Text Available The formation of the mid-latitude sporadic E layers (E_s layers by an atmospheric vortical perturbation excited in a horizontal shear flow (horizontal wind with a horizontal linear shear is investigated. A three-dimensional atmospheric vortical perturbation (atmospheric shear waves, whose velocity vector is in the horizontal plane and has a vertical wavenumber k_z≠0, can provide a vertical shear of the horizontal wind. The shear waves influence the vertical transport of heavy metallic ions and their convergence into thin and dense horizontal layers. The proposed mechanism takes into account the dynamical influence of the shear wave velocity in the horizontal wind on the vertical drift velocity of the ions. It also can explain the multi-layer structure of E_s layers. The pattern of the multi-layer structure depends on the value of the shear-wave vertical wavelength, the ion-neutral collision frequency and the direction of the background horizontal wind. The modelling of formation of sporadic E layers with a single and a double peak is presented. Also, the importance of shear wave coupling with short-period atmospheric gravity waves (AGWs on the variations of sporadic E layer ion density is examined and discussed.

Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

Directory of Open Access Journals (Sweden)

C. Xiong

2012-08-01

Full Text Available In this study five years of CHAMP (Challenging Mini-satellite Payload fluxgate magnetometer (FGM data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs. We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76–608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000–2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1. Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010. Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

Height and critical frequency variations of the sporadic-E layer at midlatitudes

Czech Academy of Sciences Publication Activity Database

Šauli, Petra; Bourdillon, A.

2008-01-01

Roč. 70, č. 15 (2008), s. 1904-1910 ISSN 1364-6826 R&D Projects: GA AV ČR IAA300420704 Grant - others:European Union(XE) COST 296 Institutional research plan: CEZ:AV0Z30420517 Keywords : Sporadic E * Planetary waves * Tidal waves * Mid-latitude ionosphere * Wavelet transform Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.667, year: 2008

Association of apolipoprotein E allele {epsilon}4 with late-onset sporadic Alzheimer`s disease

Energy Technology Data Exchange (ETDEWEB)

Lucotte, G.; David, F.; Berriche, S. [Regional Center of Neurogenetics, Reims (France)] [and others

1994-09-15

Apolipoprotein E, type {epsilon}4 allele (ApoE {epsilon}4), is associated with late-onset sporadic Alzheimer`s disease (AD) in French patients. The association is highly significant (0.45 AD versus 0.12 controls for {epsilon}4 allele frequencies). These data support the involvement of ApoE {epsilon}4 allele as a very important risk factor for the clinical expression of AD. 22 refs., 1 fig., 3 tabs.

Searching for effects caused by thunderstorms in midlatitude sporadic E layers

Czech Academy of Sciences Publication Activity Database

Barta, V.; Haldoupis, C.; Sátori, G.; Burešová, Dalia; Chum, Jaroslav; Pozoga, M.; Berényi, K. A.; Bór, J.; Popek, Martin; Kis, Á.; Bencze, P.

2017-01-01

Roč. 161, August (2017), s. 150-159 ISSN 1364-6826 R&D Projects: GA ČR(CZ) GC15-07281J; GA ČR(CZ) GAP209/12/2440; GA ČR(CZ) GA14-31899S Institutional support: RVO:68378289 Keywords : atmospheric gravity waves * ionosphere coupling * lightning * sporadic E layer * sprites * thunderstorm Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 1.326, year: 2016 https://arxiv.org/abs/1708.00270

Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo

International Nuclear Information System (INIS)

Noble, S.T.; Djuth, F.T.

1990-01-01

Two radar systems with beams intersecting in the HF-modified F region were used to simultaneously measure HF-enhanced plasma lines (HFPLs) and artificial geomagnetic field-aligned irregularities (AFAIs). The Arecibo 430-MHz radar was used for the HFPL observations, and a portable 49.92-MHz backscatter radar was deployed on the island of Guadeloupe to monitor the AFAIs. The experiment was desgined to examine the degree to which HF-induced plasma turbulence influences the development of AFAIs. When the HF beam is stepped up in power, sustained HFPLs and AFAIs are first observed at the same HF power level, indicating that ponderomotively driven instabilities may be involved in the early time development of AFAIs. As the HF power is increased, the HFPL backscatter power begins to saturate at ∼70 MW effective radiated power (ERP). However, the backscatter from AFAIs is linearly dependent on HF power, even at the highest (120 MW ERP) HF power levels available at Arecibo. This suggests that additional processes may contribute to the development of AFAIs. For example, ponderomotively driven instabilities may give rise to weak geomagnetic field-aligned irregularities that are subsequently driven unstable by processes excited near the upper hybrid resonance. It is also likely that AFAIs greatly impact the development of HF-induced plasma turbulence at late times (>1 s) following HF turn-on. Once the ionosphere is preconditioned by high-power HF modifications, AFAIs and HFPLs can be simultaneously sustained at a much lower HF power level than that needed to originally excite them. The nature of the preconditioning process is currently not well understood. New theoretical initiatives are clearly needed to guide future experimental activity in this area

Interaction of plasma cloud with external electric field in lower ionosphere

Directory of Open Access Journals (Sweden)

Y. S. Dimant

2010-03-01

Full Text Available In the auroral lower-E and upper-D region of the ionosphere, plasma clouds, such as sporadic-E layers and meteor plasma trails, occur daily. Large-scale electric fields, created by the magnetospheric dynamo, will polarize these highly conducting clouds, redistributing the electrostatic potential and generating anisotropic currents both within and around the cloud. Using a simplified model of the cloud and the background ionosphere, we develop the first self-consistent three-dimensional analytical theory of these phenomena. For dense clouds, this theory predicts highly amplified electric fields around the cloud, along with strong currents collected from the ionosphere and circulated through the cloud. This has implications for the generation of plasma instabilities, electron heating, and global MHD modeling of magnetosphere-ionosphere coupling via modifications of conductances induced by sporadic-E clouds.

Irregular analytical errors in diagnostic testing - a novel concept.

Science.gov (United States)

Vogeser, Michael; Seger, Christoph

2018-02-23

-isotope-dilution mass spectrometry methods are increasingly used for pre-market validation of routine diagnostic assays (these tests also involve substantial sets of clinical validation samples). Based on this definition/terminology, we list recognized causes of irregular analytical error as a risk catalog for clinical chemistry in this article. These issues include reproducible individual analytical errors (e.g. caused by anti-reagent antibodies) and non-reproducible, sporadic errors (e.g. errors due to incorrect pipetting volume due to air bubbles in a sample), which can both lead to inaccurate results and risks for patients.

Drift motions of small-scale irregularities in the high-latitude F region: An experimental comparison with plasma drift motions

International Nuclear Information System (INIS)

Ruohoniemi, J.M.; Greenwald, R.A.; Baker, K.B.; Villain, J.P.; McCready, M.A.

1987-01-01

On the evening of January 6, 1986, coordinated observations were carried out with the Johns Hopkins University Applied Physics Laboratory HF coherent scatter radar at Goose Bay, Labrador, and the SRI International incoherent scatter radar at Sondre Stromfjord, Greenland. The common field of view comprised a section of high-latitude F region ionosphere centered on the great circle plane between the radar sites. Over a 40-min period, the HF radar observed strong backscatter from small-scale (13.9 m) field-aligned irregularities. The bulk line-of-sight drift velocity of the irregularities is deduced from the backscatter data. The returns collected simultaneously with the incoherent scatter radar are processed for estimates of the mean line-of-sight ion velocity. Approximately 100 distinct comparisons are possible between the two sets of velocity estimates. Reversals exceeding 1,000 m/s are present in both. In this paper, the authors demonstrate a correspondence between the measured irregularity and ion drifts that is consistent with the supposition that the motion of the irregularities is dominated by convective drift of the ambient plasma. This indicates that the small-scale irregularities detected by HF radars in the high-latitude F region can serve as tracers of ionospheric convective drift

Rocket observation of electron density irregularities in the lower E region

International Nuclear Information System (INIS)

Watanabe, Yuzo; Nakamura, Yoshiharu; Amemiya, Hiroshi.

1990-01-01

Local ionospheric electron density irregularities in the scale size of 3 m to 300 m have been measured on the ascending path from 74 km to 93 km by a fix biased Langmuir probe on board the S-310-16 sounding rocket. The rocket was launched at 22:40:00 on February 1, 1986 from Kagoshima Space Center in Japan. It is found from frequency analysis of the data that the spectral index of the irregularities is 0.9 to 1.8 and the irregularity amplitude is 1 to 15 %. The altitude where the amplitude reaches its maximum is 88 km. The generation mechanism of these irregularities is explained by the neutral turbulence theory, which indicates that the spectral index is 5/3 and has been confirmed by a chemical release experiment using rockets over India to be valid up to about 110 km. From frequency analysis of the data observed during the descent in the lower E region, we have found that the rocket-wake effect becomes larger when the probe is situated near the edge of the rocket-wake, and that this is also the case even when the rocket-wake effect does not clearly appear in the DC current signal which approximately changes in proportion to the electron density, where the probe is completely situated inside the rocket-wake region. (author)

Simultaneous radar and spaced receiver VHF scintillation observations of ESF irregularities

Directory of Open Access Journals (Sweden)

D. Tiwari

2006-07-01

Full Text Available Simultaneous observations of equatorial spread F (ESF irregularities made on 10 nights during March-April 1998 and 1999, using an 18-MHz radar at Trivandrum (77° E, 8.5° N, dip 0.5° N and two spaced receivers recording scintillations on a 251-MHz signal at Tirunelveli (77.8° E, 8.7° N, dip 0.4° N, have been used to study the evolution of Equatorial Spread F (ESF irregularities. Case studies have been carried out on the day-to-day variability in ESF structure and dynamics, as observed by 18-MHz radar, and with spaced receiver measurements of average zonal drift Vo of the 251-MHz radio wave diffraction pattern on the ground, random velocity Vc, which is a measure of random changes in the characteristics of scintillation-producing irregularities, and maximum cross-correlation CI of the spaced receivers signals. Results show that in the initial phase of plasma bubble development, the greater the maximum height of ESF irregularities responsible for the radar backscatter, the greater the decorrelation is of the spaced receiver scintillation signals, indicating greater turbulence. The relationship of the maximum spectral width derived from the radar observations and CI also supports this result.

Sporadic sodium and E layers observed during the summer 2002 MaCWAVE/MIDAS rocket campaign

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B. P. Williams

2006-07-01

Full Text Available On 5 July 2002, a MaCWAVE (Mountain and Convective Waves Ascending VErtically payload launched from Andøya Rocket Range, Norway, observed narrow enhanced layers of electron density that were nearly coincident with sporadic sodium layers measured by the Weber sodium lidar at the nearby ALOMAR Observatory. We investigate the formation mechanism of these layers using the neutral wind and temperature profiles measured directly by the lidar and the vertical motion deduced from the sodium mixing ratio. Through comparisons of the lidar data to the sporadic E in situ data, we find support for the concentration and downward motion of ions to an altitude where chemical models predict the rapid conversion of sodium ions to neutral sodium.

Fractal analysis of plaque border, a novel method for the quantification of atherosclerotic plaque contour irregularity, is associated with pro-atherogenic plasma lipid profile in subjects with non-obstructive carotid stenoses.

Science.gov (United States)

Moroni, Francesco; Magnoni, Marco; Vergani, Vittoria; Ammirati, Enrico; Camici, Paolo G

2018-01-01

Plaque border irregularity is a known imaging characteristic of vulnerable plaques, but its evaluation heavily relies on subjective evaluation and operator expertise. Aim of the present work is to propose a novel fractal-analysis based method for the quantification of atherosclerotic plaque border irregularity and assess its relation with cardiovascular risk factors. Forty-two asymptomatic subjects with carotid stenosis underwent ultrasound evaluation and assessment of cardiovascular risk factors. Total, low-density lipoprotein (LDL), high-density lipoprotein (HDL) plasma cholesterol and triglycerides concentrations were measured for each subject. Fractal analysis was performed in all the carotid segments affected by atherosclerosis, i.e. 147 segments. The resulting fractal dimension (FD) is a measure of irregularity of plaque profile on long axis view of the plaque. FD in the severest stenosis (main plaque FD,mFD) was 1.136±0.039. Average FD per patient (global FD,gFD) was 1.145±0.039. FD was independent of other plaque characteristics. mFD significantly correlated with plasma HDL (r = -0.367,p = 0.02) and triglycerides-to-HDL ratio (r = 0.480,p = 0.002). Fractal analysis is a novel, readily available, reproducible and inexpensive technique for the quantitative measurement of plaque irregularity. The correlation between low HDL levels and plaque FD suggests a role for HDL in the acquisition of morphologic features of plaque instability. Further studies are needed to validate the prognostic value of fractal analysis in carotid plaques evaluation.

Sporadic frame dropping impact on quality perception

Science.gov (United States)

Pastrana-Vidal, Ricardo R.; Gicquel, Jean Charles; Colomes, Catherine; Cherifi, Hocine

2004-06-01

Over the past few years there has been an increasing interest in real time video services over packet networks. When considering quality, it is essential to quantify user perception of the received sequence. Severe motion discontinuities are one of the most common degradations in video streaming. The end-user perceives a jerky motion when the discontinuities are uniformly distributed over time and an instantaneous fluidity break is perceived when the motion loss is isolated or irregularly distributed. Bit rate adaptation techniques, transmission errors in the packet networks or restitution strategy could be the origin of this perceived jerkiness. In this paper we present a psychovisual experiment performed to quantify the effect of sporadically dropped pictures on the overall perceived quality. First, the perceptual detection thresholds of generated temporal discontinuities were measured. Then, the quality function was estimated in relation to a single frame dropping for different durations. Finally, a set of tests was performed to quantify the effect of several impairments distributed over time. We have found that the detection thresholds are content, duration and motion dependent. The assessment results show how quality is impaired by a single burst of dropped frames in a 10 sec sequence. The effect of several bursts of discarded frames, irregularly distributed over the time is also discussed.

Stability of plasmas obtained in E.P.P.E; Stabilite des plasmas obtenus dans E. P. P. E

Energy Technology Data Exchange (ETDEWEB)

Adam, J; Rebut, P H; Torossian, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1964-07-01

The stability results obtained on Mest have been extended on a machine ten times more powerful: EppE. A plasma stable during its whole confinement time has been observed. This confinement time seems to be limited by the resistive diffusion of the magnetic fields through the plasma. The main characteristics of this plasma are: Time of confinement: 200 {mu}s; T{sub e} {approx} T{sub i}: 40 eV; {beta} = 8*{pi}*k*T*n{sub e}/B{sup 2}: 8%; n{sub e}: 2.5*10{sup 15}/cm{sup 3}. (authors) [French] Les resultats sur la stabilite obtenus dans Mest ont ete developpes dans une machine dix fois plus puissante: EppE. Un plasma stable pendant toute la duree de son confinement a ete observe et la limitation de ce temps est bien expliquee par la diffusion resistive des champs magnetiques a travers le plasma. Les principales caracteristiques du plasma d'EppE sont: Temps de confinement: 200 {mu}s; T{sub e} {approx} T{sub i}: 40 eV; {beta} 8*{pi}*k*T*n{sub e}/B{sup 2}: 8%; n{sub e}: 2.5*10{sup 15}/cm{sup 3}.

Effects of a conducting E layer on classical F region cross-field plasma diffusion

International Nuclear Information System (INIS)

Vickrey, J.F.; Kelley, M.C.

1982-01-01

The rate of cross-field plasma diffusion in the F region ionosphere is significantly increased when the magnetic field lines thread a highly conducting E region below. This reduces the lifetime of small-scale F region electron density irregularities in the polar ionosphere where the presence of a highly conducting E region is comonplace. A simple mmodel is developed to describe the effects of a conducting E layer on classical F region plasma diffusion. In the absence of an E region, the difference in ion and electron diffusion rates leads to a charge separation and, hence, to an electrostatic field that retards ion diffusion. When the highly conducting magnetic field lines are tied to a conducting E region, however, electrons can flow along B to reduce the ambipolar diffusion electric field, and ions can proceed perpendicular to B at a rate approaching their own (higher) diffusion velocity. It is shown that the enhanced total diffusion rate that results depends strongly on the height of the F layer and on the ratio of the E to F region Pedersen conductivities

Possible mechanism of solar noise storm generation in meter wavelength

International Nuclear Information System (INIS)

Genkin, L.G.; Erukhimov, L.M.; Levin, B.N.

1989-01-01

Fluctuation plasma mechanism of noise storm generation is proposed. The sporadic formation of density irregularities in plasma (Langmuir) turbulence region is shown to be the result of thermal stratification of plasma. The noise storm type 1 bursts in their typical parameters are like radio emission due to plasma turbulence conversion on this structures

ARCAD3-SAFARI coordinated study of auroral and polar F-region ionospheric irregularities

International Nuclear Information System (INIS)

Villain, J.P.; Hanuise, C.

1986-01-01

Simultaneous observations of F-region ionospheric irregularities have been performed with the SAFARI ground-based HF radars and the ISOPROBE experiment on board the AUREOL-3 satellite. Among seven orbits during which the satellite trajectory was directly in the radar beam or in the vicinity, four of them have been analyzed in detail. The spectral power of the electron density variations ΔNsub(e)/Nsub(e) has been calculated for wavelengths between 20 m and 1 km from the isoprobe high time resolution thermal plasma measurements. One spectrum is obtained every 1.2 s, a time which corresponds to about 10 km along the satellite trajectory. The presence of echoes observed in the F-region with the SAFARI radars is compared with the spectral power of the electron density variations deduced from the ISOPROBE ''in situ'' measurements. A good agreement is found between the two sets of observations and a numerical value of the spectral power corresponding to detection of echoes by the radar is given. A synoptical view of the event is given and interpreted according to the existing theories of plasma irregularities

Simultaneous radar and spaced receiver VHF scintillation observations of ESF irregularities

Directory of Open Access Journals (Sweden)

D. Tiwari

2006-07-01

Full Text Available Simultaneous observations of equatorial spread F (ESF irregularities made on 10 nights during March-April 1998 and 1999, using an 18-MHz radar at Trivandrum (77° E, 8.5° N, dip 0.5° N and two spaced receivers recording scintillations on a 251-MHz signal at Tirunelveli (77.8° E, 8.7° N, dip 0.4° N, have been used to study the evolution of Equatorial Spread F (ESF irregularities. Case studies have been carried out on the day-to-day variability in ESF structure and dynamics, as observed by 18-MHz radar, and with spaced receiver measurements of average zonal drift V_o of the 251-MHz radio wave diffraction pattern on the ground, random velocity V_c, which is a measure of random changes in the characteristics of scintillation-producing irregularities, and maximum cross-correlation C_I of the spaced receivers signals. Results show that in the initial phase of plasma bubble development, the greater the maximum height of ESF irregularities responsible for the radar backscatter, the greater the decorrelation is of the spaced receiver scintillation signals, indicating greater turbulence. The relationship of the maximum spectral width derived from the radar observations and C_I also supports this result.

Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere

Czech Academy of Sciences Publication Activity Database

Mošna, Zbyšek; Koucká Knížová, Petra

90-91, SI (2012), s. 172-178 ISSN 1364-6826. [IAGA/ICMA/CAWSES-II TG4 Workshop on Vertical Coupling in the Atmosphere-Ionosphere System /4./. Prague, 14.02.2011-18.02.2011] R&D Projects: GA AV ČR IAA300420704 Institutional support: RVO:68378289 Keywords : Sporadic E * Planetary waves * Tidal waves * Mid-latitude ionosphere Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.417, year: 2012 http://www.sciencedirect.com/science/article/pii/S1364682612001186

Detection of infectivity in blood of persons with variant and sporadic Creutzfeldt-Jakob disease.

Science.gov (United States)

Douet, Jean Yves; Zafar, Saima; Perret-Liaudet, Armand; Lacroux, Caroline; Lugan, Séverine; Aron, Naima; Cassard, Herve; Ponto, Claudia; Corbière, Fabien; Torres, Juan Maria; Zerr, Inga; Andreoletti, Olivier

2014-01-01

We report the presence of infectivity in erythrocytes, leukocytes, and plasma of 1 person with variant Creutzfeldt-Jakob disease and in the plasma of 2 in 4 persons whose tests were positive for sporadic Creutzfeldt-Jakob disease. The measured infectivity levels were comparable to those reported in various animals with transmissible spongiform encephalopathies.

Observations of inner plasmasphere irregularities with a satellite-beacon radio-interferometer array

International Nuclear Information System (INIS)

Jacobson, A.R.; Hoogeveen, G.; Carlos, R.C.; Wu, G.; Fejer, B.G.; Kelley, M.C.

1996-01-01

A radio-interferometer array illuminated by 136-MHz beacons of several geosynchronous satellites has been used to study small (≥10 13 m -2 ) transient disturbances in the total electron content along the lines of sight to the satellites. High-frequency (f>3 mHz) electron content oscillations are persistently observed, particularly during night and particularly during geomagnetically disturbed periods. The oscillations move across the array plane at speeds in the range 200 endash 2000 m/s, with propagation azimuths that are strongly peaked in lobes toward the western half-plane. Detailed analysis of this azimuth behavior, involving comparison between observations on various satellite positions, indicates compellingly that the phase oscillations originate in radio refraction due to geomagnetically aligned plasma density perturbations in the inner plasmasphere. The motion of the phase perturbations across the array plane is caused by EXB drift of the plasma medium in which the irregularities are embedded. We review the statistics of 2.5 years of around-the-clock data on the local time, magnetic disturbance, seasonal, and line-of-sight variations of these observed irregularities. We compare the irregularities close-quote inferred electrodynamic drifts to what is known about midlatitude plasma drift from incoherent scatter. Finally, we show in detail how the observation of these irregularities provides a unique and complementary monitor of inner plasmasphere irregularity incidence and zonal drift.copyright 1996 American Geophysical Union

Very high latitude F-region irregularities observed by HF-radar backscatter

International Nuclear Information System (INIS)

Baker, K.B.; Greenwald, R.A.; Tsunoda, R.T.

1983-01-01

In February and March, 1982, a coherent scatter HF radar was operated from Cleary, Alaska to observe 7- to 15-m wavelength F-region plasma irregularities near the poleward edge of the auroral zone and in the polar cap. The radar operated for five days from February 25 to March 1 and produced approximately 700,000 Doppler spectra during that time. Of those nearly 700,000 spectra, approximately 10% showed backscattered power 3 dB or more above the noise level. A ray tracing technique using electron densities determined by the Chatanika incoherent scatter radar was used to predict locations where the HF waves were approximately normal to the magnetic field. If those locations were also to contain small scale electron density structure, then one would expect them to backscatter the HF waves. Several comparisons were made between predicted and observed locations of radiowave backscatter and excellent agreement was obtained. In addition, comparisons of the Doppler velocities observed by the coherent scatter HF radar and those observed by the Chatanika radar showed good agreement, suggesting that the plasma irregularities observed by the HF radar drift with the ambient plasma. In addition, average vector velocities calculated for the entire 5-day period show a flow pattern consistent with polar cap convection models. This again indicates that the irregularities drift with the plasma, as is predicted by a number of theories of F-region plasma irregularities. In the summer of 1983, the research program begun with those measurements will be continued with a steerable phased-array HF radar located at Goose Bay, Labrador, that will view the same ionospheric region as does the Sondre Stromfjord incoherent scatter radar

Decomposing Oriented Graphs into Six Locally Irregular Oriented Graphs

DEFF Research Database (Denmark)

Bensmail, Julien; Renault, Gabriel

2016-01-01

An undirected graph G is locally irregular if every two of its adjacent vertices have distinct degrees. We say that G is decomposable into k locally irregular graphs if there exists a partition E1∪E2∪⋯∪Ek of the edge set E(G) such that each Ei induces a locally irregular graph. It was recently co...

Migración y violencia en Cancún: estudio de dos asentamientos irregulares; Migração e violencia em Cancún: estudo de dois assentamentos irregulares; Migration and violence in Cancún: study of two irregular settlements

Directory of Open Access Journals (Sweden)

Minerva Alavez San Pedro

2017-07-01

Full Text Available Resumen: El presente texto ofrece una aproximación a las condiciones actuales de violencia en dos asentamientos irregulares de Cancún, que se ubica en el estado de Quintana Roo, México, como consecuencia de la migración laboral que ha experimentado esta localidad desde su creación en 1970 como Centro Turístico Integral. Para elaborar este trabajo se realizó, además de la revisión bibliográfica, un seguimiento hemerográfico de medios de comunicación locales y nacionales y un trabajo etnográfico en las colonias El Milagro y Tres Reyes de abril de 2016 a junio de 2017. De manera general se puede adelantar que las presentes manifestaciones de violencia en Cancún y el continuo surgimiento de asentamientos irregulares ponen en evidencia la incapacidad institucional del Estado para planear y atender las necesidades de seguridad y vivienda de la población. Palabras clave: Cancún, economía, migración, violencia, asentamientos.   Resumo: O presente texto ofrece uma aproximação das condiçõe atuais de violencia em dois assentamentos irregulares em Cancún, que se localiza no estado de Quintana Roo, México, como consequência da migração de trabalhadores que aconteceu nesta localidade desde sua criação em 1970 como Centro Turístico Integral. Para elaborar este trabalho se realizou, ademáis da revisão bibliográfica, um estudo hemerográfico dos meios de comunicação locais e nacionais e um trabalho etnográfico nas colônias de El Milagro e Tres Reyes de abril de 2016 a junho de 2017. De maneira geral se pode antecipar que as presentes manifestações de violencia em Cancún e o contínuo surgimento de assentamentos irregulares colocam em evidencia a capacidade institucional do Estado para planejar e atender as necesidades de segurança e vivência da população. Palavras-chaves: Cancún; economía; migração; violencia; assentamentos.   Abstract: The present text offers an approximation to the current conditions of

The influence of tidal winds in the formation of blanketing sporadic e-layer over equatorial Brazilian region

Science.gov (United States)

Resende, Laysa Cristina Araujo; Batista, Inez Staciarini; Denardini, Clezio Marcos; Batista, Paulo Prado; Carrasco, Alexander José; Andrioli, Vânia Fátima; Moro, Juliano

2018-06-01

This work analysis the blanketing sporadic layers (Esb) behavior over São Luís, Brazil (2° 31‧ S, 44° 16‧ W, dip: -4.80) which is classified as a transition region between equatorial and low-latitude. Hence, some peculiarities can appear as Esb occurrence instead of the common Esq, which is a non-blanketing irregularity layer. The analysis presented here was obtained using a modified version of a theoretical model for the E region (MIRE), which computes the densities of the metallic ions (Fe+ and Mg+) and the densities of the main molecular ions (NO+, O2+, N2+) by solving the continuity and momentum equations for each one of them. In that model, the Es layer physics driven by both diurnal and semidiurnal tidal winds are taken into account and it was extended in height coverage by adding a novel neutral wind model derived from the all-sky meteor radar measurements. Thus, we provide more trustworthy results related to the Es layer formation in the equatorial region. We verified the contribution of each tidal wind component to the Esb layer formation in this equatorial region. Additionally, we compared the Es layer electron density computed by MIRE with the data obtained by using the blanketing frequency parameter (fbEs) deduced from ionograms. The results show that the diurnal component of the tidal wind is more important in the Esb layer formation whereas the semidiurnal component has a little contribution in our simulations. Finally, it was verified that the modified MIRE presented here can be used to study the Esb layers occurrence over the equatorial region in the Brazilian sector.

New Model for Ionospheric Irregularities at Mars

Science.gov (United States)

Keskinen, M. J.

2018-03-01

A new model for ionospheric irregularities at Mars is presented. It is shown that wind-driven currents in the dynamo region of the Martian ionosphere can be unstable to the electromagnetic gradient drift instability. This plasma instability can generate ionospheric density and magnetic field irregularities with scale sizes of approximately 15-20 km down to a few kilometers. We show that the instability-driven magnetic field fluctuation amplitudes relative to background are correlated with the ionospheric density fluctuation amplitudes relative to background. Our results can explain recent observations made by the Mars Atmosphere and Volatile EvolutioN spacecraft in the Martian ionosphere dynamo region.

Sporadic plasma heating in the lower chromosphere

Science.gov (United States)

Zaitsev, V. V.

2014-12-01

It is usually assumed that heating of the chromosphere is caused by the precipitation of energetic particles (electrons and protons) accelerated in the solar corona, namely, at flare arc tops. On the other hand, recently obtained observational data show that the chromospheric footpoints of compact magnetic loops are directly heated to ≥106 K, and hot plasma erupted from the footpoints of such loops. The plasma mechanism of the THz emission of flares may also indicate that deep chromospheric layers with densities up to n ≈ 1015 cm-3 can be heated to about 105-106 K. It has been shown that electrons can be accelerated and plasma can be heated in the lower chromosphere when the Rayleigh-Taylor instability develops at magnetic loop chromo-spheric footpoints. This instability results in the penetration of the upper chromospheric plasma into a loop and induces an electric field that effectively accelerates electrons and leads to in situ heating of the chromo-sphere.

Genetics Home Reference: sporadic hemiplegic migraine

Science.gov (United States)

... Home Health Conditions Sporadic hemiplegic migraine Sporadic hemiplegic migraine Printable PDF Open All Close All Enable Javascript ... view the expand/collapse boxes. Description Sporadic hemiplegic migraine is a rare form of migraine headache. Migraines ...

Total edge irregularity strength of (n,t)-kite graph

Science.gov (United States)

Winarsih, Tri; Indriati, Diari

2018-04-01

Let G(V, E) be a simple, connected, and undirected graph with vertex set V and edge set E. A total k-labeling is a map that carries vertices and edges of a graph G into a set of positive integer labels {1, 2, …, k}. An edge irregular total k-labeling λ :V(G)\\cup E(G)\\to \\{1,2,\\ldots,k\\} of a graph G is a labeling of vertices and edges of G in such a way that for any different edges e and f, weights wt(e) and wt(f) are distinct. The weight wt(e) of an edge e = xy is the sum of the labels of vertices x and y and the label of the edge e. The total edge irregularity strength of G, tes(G), is defined as the minimum k for which a graph G has an edge irregular total k-labeling. An (n, t)-kite graph consist of a cycle of length n with a t-edge path (the tail) attached to one vertex of a cycle. In this paper, we investigate the total edge irregularity strength of the (n, t)-kite graph, with n > 3 and t > 1. We obtain the total edge irregularity strength of the (n, t)-kite graph is tes((n, t)-kite) = \\lceil \\frac{n+t+2}{3}\\rceil .

Dependence on zenith angle of the strength of 3-meter equatorial electrojet irregularities

International Nuclear Information System (INIS)

Ierkic, H.M.; Fejer, B.G.; Farley, D.T.

1980-01-01

Radar measurements in Peru were used to deduce the zenith angle dependence of the scattering cross section of plasma irregularities generated by instabilities in the equatorial electrojet. The irregularities probed by the 50 MHz Jicamarca radar had a wavelength of 3m. The cross section for the type 2 irregularities was isotopic in the plane perpendicular to the magnetic field, while the cross section for the stronger type 1 irregularities varied with zenith angle at a rate of approximately 0.3 dB/degree; the horizontally traveling waves were more than 100 times stronger than those traveling vertically

Solar eclipse effects of 22 July 2009 on Sporadic-E

Directory of Open Access Journals (Sweden)

G. Chen

2010-02-01

Full Text Available The total solar eclipse of 22 July 2009, was visible from some regions of China and the intense sporadic-E (Es that broke out during the solar eclipse period over the eastern China provided a unique chance to study solar eclipse effects on the Es-layer. The ground based high-frequency (HF vertical-incidence and oblique-incidence backscatter radio systems in Wuhan and an HF oblique receivers located in Suzhou were operated to detect the Es-layer. The vertical, oblique and backscatter ionograms of 22 and 23 July were recorded, processed and analyzed. The analyzing results show that the critical frequency of Es, the hop number and power of the rays transmitted from Wuhan to Suzhou as well as the Doppler frequency shift of the one-hop oblique-incidence waves reflected by the Es-layer all increased during the solar eclipse period. These variations are displayed in the paper and explained to be induced by the wind-field, which is produced by the powerful meridional air flows from the sunshine region to the moon's shadow.

Solar eclipse effects of 22 July 2009 on Sporadic-E

Directory of Open Access Journals (Sweden)

G. Chen

2010-02-01

Full Text Available The total solar eclipse of 22 July 2009, was visible from some regions of China and the intense sporadic-E (Es that broke out during the solar eclipse period over the eastern China provided a unique chance to study solar eclipse effects on the Es-layer. The ground based high-frequency (HF vertical-incidence and oblique-incidence backscatter radio systems in Wuhan and an HF oblique receivers located in Suzhou were operated to detect the Es-layer. The vertical, oblique and backscatter ionograms of 22 and 23 July were recorded, processed and analyzed. The analyzing results show that the critical frequency of Es, the hop number and power of the rays transmitted from Wuhan to Suzhou as well as the Doppler frequency shift of the one-hop oblique-incidence waves reflected by the Es-layer all increased during the solar eclipse period. These variations are displayed in the paper and explained to be induced by the wind-field, which is produced by the powerful meridional air flows from the sunshine region to the moon's shadow.

Propagation and scattering of electromagnetic waves by the ionospheric irregularities

International Nuclear Information System (INIS)

Ho, A.Y.; Kuo, S.P.; Lee, M.C.

1993-01-01

The problem of wave propagation and scattering in the ionosphere is particularly important in the areas of communications, remote-sensing and detection. The ionosphere is often perturbed with coherently structured (quasiperiodic) density irregularities. Experimental observations suggest that these irregularities could give rise to significant ionospheric effect on wave propagation such as causing spread-F of the probing HF sounding signals and scintillation of beacon satellite signals. It was show by the latter that scintillation index S 4 ∼ 0.5 and may be as high as 0.8. In this work a quasi-particle theory is developed to study the scintillation phenomenon. A Wigner distribution function for the wave intensity in the (k,r) space is introduced and its governing equation is derived with an effective collision term giving rise to the attenuation and scattering of the wave. This kinetic equation leads to a hierarchy of moment equations in r space. This systems of equations is then truncated to the second moment which is equivalent to assuming a cold quasi-particle distribution In this analysis, the irregularities are modeled as a two dimensional density modulation on an uniform background plasma. The analysis shows that this two dimensional density grating, effectively modulates the intensity of the beacon satellite signals. This spatial modulation of the wave intensity is converted into time modulation due to the drift of the ionospheric irregularities, which then contributes to the scintillation of the beacon satellite signals. Using the proper plasma parameters and equatorial measured data of irregularities, it is shown that the scintillation index defined by S4=( 2 >- 2 )/ 2 where stands for spatial average over an irregularity wavelength is in the range of the experimentally detected values

Comparison Between Sporadic and Misdiagnosed Sporadic Creutzfeldt-Jakob Disease: A Report of Two Cases.

Science.gov (United States)

Zhao, Xiongfei; Yu, Yingxin; Zhao, Zhiru; Xu, Jiaping

2015-06-01

Definite accurate diagnosis for Creutzfeldt-Jakob disease (CJD) depends on neuropathologic examination of brain biopsy or autopsy. However, transmissible nature makes the invasive examination dangerous. This study was set to determine that the clinical features are for the diagnosis of CJD through a comparison study. We compared clinical features of two cases with initial diagnosis of sporadic CJD. One case was finally diagnosed as definite sporadic CJD. According to World Health Organization diagnosis criteria, the other one, which had been diagnosed as probable sporadic CJD, was confirmed as limbic encephalitis after long-term follow-up. Compared with the case of definite sporadic CJD, the misdiagnosed case did not present typical electroencephalogram (EEG) and diffusion-weighted in magnetic resonance images (DWI) of CJD. However, cerebrospinal fluid in the misdiagnosed patient showed 14-3-3 protein positivity. The patient conditions improved after treatment. Through this case comparison, we conclude that EEG and DWI are necessary for accurate diagnosis of sporadic CJD. Further, long-term follow-up is crucial to diagnosis and treatment of CJD.

Catastrophe in plasma focus evolution

International Nuclear Information System (INIS)

Ikuta, Kazunari.

1984-07-01

A theory of generating strong electric field in a dense plasma column in plasma focus is established by applying the formula for the electron thermal conductivity in destroyed magnetic surfaces like those in tokamaks. The origin of the electric field may be from abrupt rise of plasma resistivity when the irregularity of magnetic field is weak. However, the electric field can be from the inductive origin in case the irregularity attains a certain level. Both origin should be mixed up depending on the magnitude of the irregularity. (author)

Introduction to Sporadic Groups

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Luis J. Boya

2011-01-01

Full Text Available This is an introduction to finite simple groups, in particular sporadic groups, intended for physicists. After a short review of group theory, we enumerate the 1+1+16=18 families of finite simple groups, as an introduction to the sporadic groups. These are described next, in three levels of increasing complexity, plus the six isolated ''pariah'' groups. The (old five Mathieu groups make up the first, smallest order level. The seven groups related to the Leech lattice, including the three Conway groups, constitute the second level. The third and highest level contains the Monster group M, plus seven other related groups. Next a brief mention is made of the remaining six pariah groups, thus completing the 5+7+8+6=26 sporadic groups. The review ends up with a brief discussion of a few of physical applications of finite groups in physics, including a couple of recent examples which use sporadic groups.

ARCAD3-SAFARI coordinated study of auroral and polar F-region ionospheric irregularities

International Nuclear Information System (INIS)

Villain, J.P.; Hanuise, C.; Beghin, C.

1985-01-01

Simultaneous observations of F-region ionospheric irregularities have been performed with the SAFARI ground based HF radars and the ISOPROBE experiment on board the AUREOL-3 satellite. Among seven orbits during which the satellite trajectory was directly in the radar beam or in the vicinity, four of them have been analysed in detail. The spectral power of the electron density variations ΔNe/Ne has been calculated for wavelengths between 20 m and 1 km from the ISOPROBE high time resolution thermal plasma measurements. One spectrum is obtained every 1.2 sec., which corresponds to about 10 km along the satellite trajectory. The SAFARI experiment is a set of two HF coherent radars located at Lycksele (Sweden) and Oulu (Finland). These radars are sensitive to F-region ionospheric irregularities of 10 m wavelength in the polar and auroral ionosphere. The phase velocity of the irregularities obtained from the Doppler spectrum is related to the ambient plasma drift. The presence of echoes observed with the SAFARI radars is compared with the spectral power of the electron density variations deduced from the ISOPROBE in-situ measurements. A good agreement is found between the two sets of observations and a numerical value of the spectral power corresponding to detection of echoes by the radar is given. A synoptical view of the event is given and interpreted according to the existing theories on plasma irregularities

Edge irregular total labellings for graphs of linear size

DEFF Research Database (Denmark)

Brandt, Stephan; Rautenbach, D.; Miškuf, J.

2009-01-01

As an edge variant of the well-known irregularity strength of a graph G = (V, E) we investigate edge irregular total labellings, i.e. functions f : V ∪ E → {1, 2, ..., k} such that f (u) + f (u v) + f (v) ≠ f (u) + f (u v) + f (v) for every pair of different edges u v, u v ∈ E. The smallest possi...

Strong Sporadic E Occurrence Detected by Ground-Based GNSS

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Sun, Wenjie; Ning, Baiqi; Yue, Xinan; Li, Guozhu; Hu, Lianhuan; Chang, Shoumin; Lan, Jiaping; Zhu, Zhengping; Zhao, Biqiang; Lin, Jian

2018-04-01

The ionospheric sporadic E (Es) layer has significant impact on radio wave propagation. The traditional techniques employed for Es layer observation, for example, ionosondes, are not dense enough to resolve the morphology and dynamics of Es layer in spatial distribution. The ground-based Global Navigation Satellite Systems (GNSS) technique is expected to shed light on the understanding of regional strong Es occurrence, owing to the facts that the critical frequency (foEs) of strong Es structure is usually high enough to cause pulse-like disturbances in GNSS total electron content (TEC), and a large number of GNSS receivers have been deployed all over the world. Based on the Chinese ground-based GNSS networks, including the Crustal Movement Observation Network of China and the Beidou Ionospheric Observation Network, a large-scale strong Es event was observed in the middle latitude of China. The strong Es shown as a band-like structure in the southwest-northeast direction extended more than 1,000 km. By making a comparative analysis of Es occurrences identified from the simultaneous observations by ionosondes and GNSS TEC receivers over China middle latitude statistically, we found that GNSS TEC can be well employed to observe strong Es occurrence with a threshold value of foEs, 14 MHz.

Seasonal and Local Time Variations of E-Region Field-Aligned Irregularities Observed with 30.8-MHz Radar at Kototabang, Indonesia

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Y. Otsuka

2012-01-01

Full Text Available A VHF backscatter radar with operating frequency 30.8 MHz has been operated at Kototabang (0.20°S, 100.32°E; dip latitude 10.36°S, Indonesia, since February 2006. We analyzed E-region field-aligned irregularities (FAIs observed by this radar through a year of 2007 and found that the E-region FAI observed at Kototabang can be classified into two groups. One is “descending FAI”. Altitude of the FAI echo region descends with time from 102 km to 88 km altitude during 0700–1000 and 1900–0000 LT in June solstice season. The other is “low-altitude FAI”, which is observed in an altitude range from 88 to 94 km mainly during nighttime. The observed Doppler velocity show distinct local time and altitude dependence. The seasonally averaged zonal velocity above (below approximately 94 km altitude is westward (eastward during daytime and eastward (westward during nighttime. Meridional/vertical velocity perpendicular to the geomagnetic fields is upward during daytime and downward during nighttime. The direction of the FAI velocity above approximately 94 km altitude is consistent with that of the background E × B plasma drifts reported previously.

C/NOFS Satellite Electric Field and Plasma Density Observations of Plasma Instabilities Below the Equatorial F-Peak -- Evidence for Approximately 500 km-Scale Spread-F "Precursor" Waves Driven by Zonal Shear Flow and km-Scale, Narrow-Banded Irregularities

Science.gov (United States)

Pfaff, R.; Freudenreich, H.; Klenzing, J.; Liebrecht, C.; Valladares, C.

2011-01-01

As solar activity has increased, the ionosphere F-peak has been elevated on numerous occasions above the C/NOFS satellite perigee of 400km. In particular, during the month of April, 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set (to our knowledge): The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second new result (for C/NOFS) is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is below the F -peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field component of these waves is strongest in the zonal direction. These waves are strongly correlated with simultaneous observations of plasma density oscillations and appear both with, and without, evidence of larger-scale spread-F depletions. These km-scale, quasi-coherent waves strongly resemble the bottomside, sinusoidal irregularities reported in the Atmosphere Explorer satellite data set by Valladares et al. [JGR, 88, 8025, 1983

Irregular water supply, household usage and dengue: a bio-social study in the Brazilian Northeast.

Science.gov (United States)

Caprara, Andrea; Lima, José Wellington de Oliveira; Marinho, Alice Correia Pequeno; Calvasina, Paola Gondim; Landim, Lucyla Paes; Sommerfeld, Johannes

2009-01-01

Despite increased vector control efforts, dengue fever remains endemic in Fortaleza, Northeast Brazil, where sporadic epidemic outbreaks have occurred since 1986. Multiple factors affect vector ecology such as social policy, migration, urbanization, city water supply, garbage disposal and housing conditions, as well as community level understanding of the disease and related practices. This descriptive study used a multi-disciplinary approach that bridged anthropology and entomology. A multiple case study design was adopted to include research in six study areas, defined as blocks. The water supply is irregular in households from both under-privileged and privileged areas, however, clear differences exist. In the more privileged blocks, several homes are not connected to the public water system, but have a well and pump system and therefore irregularity of supply does not affect them. In households from under-privileged blocks, where the water supply is irregular, the frequent use of water containers such as water tanks, cisterns, barrels and pots, creates environmental conditions with a greater number of breeding areas. In under-privileged homes, there are more possible breeding areas and environmental conditions that may improve the chances of Aedes aegypti survival.

Hemolytic disease of the newborn caused by irregular blood subgroup (Kell, C, c, E, and e) incompatibilities: report of 106 cases at a tertiary-care centre.

Science.gov (United States)

Karagol, Belma Saygili; Zenciroglu, Aysegul; Okumus, Nurullah; Karadag, Nilgun; Dursun, Arzu; Hakan, Nilay

2012-06-01

To determine the clinical spectrum of hemolytic disease due to irregular blood subgroup incompatibility in hospitalized neonates. The medical records of the all hospitalized newborn patients diagnosed with indirect hyperbilirubinemia due to subgroup incompatibility in Kell, C, c, E, and e systems were included in the study. Data from 106 newborns with hemolytic jaundice due to irregular blood subgroups were retrospectively evaluated, and clinical and laboratory findings were compared between patients . The treatment modalities given to the patients of each subgroup types and the laboratory findings and treatment modalities of the cases according to Coombs tests results were also analyzed. Fetal affection of the hemolysis and also fetal losses due to irregular red-cell alloimmunization were not detected in prenatal course, as there was no follow-up of these pregnancies. The mean postnatal hospitalizing age was 6.1 ± 5.2 days after birth. The mean total bilirubin level and the mean hemoglobin value on hospitalization were 343.7 ± 63.3 µmol/L (=20.1 ± 3.7 mg/dL) and 14.9 ± 3.4 g/dL, respectively. Of 106 patients identified with irregular subgroup incompatibility, 40 infants (37.7%) were associated with C, 22 (20.8%) with c, 30 (28.3%) with E, 9 (8.5%) with e, and 5 (4.7%) with Kell subgroup system. Positive Coombs tests (either direct and/or indirect) occurred in 28.3% of the study cases. Hydrops fetalis was determined in 5 of 106 neonates (4.7%). Twenty-two of 106 (20.8%) patients required total exchange transfusion. Positive Coombs test in cases required total exchange transfusion was 63.6%. Our data expose the magnitude and spectrum of the potential developing severe hemolytic disease and immune hydrops due to irregular subgroup incompatibility. Minor group antibody screening is recommended both in the mother and the high-risk infants with hyperbilirubinemia and hemolytic disease of the newborn. Copyright © 2012 Thieme Medical Publishers, Inc., 333 Seventh

Coordinated observations of postmidnight irregularities and thermospheric neutral winds and temperatures at low latitudes

Science.gov (United States)

Dao, Tam; Otsuka, Yuichi; Shiokawa, Kazuo; Nishioka, Michi; Yamamoto, Mamoru; Buhari, Suhaila M.; Abdullah, Mardina; Husin, Asnawi

2017-07-01

We investigated a postmidnight field-aligned irregularity (FAI) event observed with the Equatorial Atmosphere Radar at Kototabang (0.2°S, 100.3°E, dip latitude 10.4°S) in Indonesia on the night of 9 July 2010 using a comprehensive data set of both neutral and plasma parameters. We examined the rate of total electron content change index (ROTI) obtained from GPS receivers in Southeast Asia, airglow images detected by an all-sky imager, and thermospheric neutral winds and temperatures obtained by a Fabry-Perot interferometer at Kototabang. Altitudes of the F layer (h'F) observed by ionosondes at Kototabang, Chiang Mai, and Chumphon were also surveyed. We found that the postmidnight FAIs occurred within plasma bubbles and coincided with kilometer-scale plasma density irregularities. We also observed an enhancement of the magnetically equatorward thermospheric neutral wind at the same time as the increase of h'F at low-latitude stations, but h'F at a station near the magnetic equator remained invariant. Simultaneously, a magnetically equatorward gradient of thermospheric temperature was identified at Kototabang. The convergence of equatorward neutral winds from the Northern and Southern Hemispheres could be associated with a midnight temperature maximum occurring around the magnetic equator. Equatorward neutral winds can uplift the F layer at low latitudes and increase the growth rate of Rayleigh-Taylor instabilities, causing more rapid extension of plasma bubbles. The equatorward winds in both hemispheres also intensify the eastward Pedersen current, so a large polarization electric field generated in the plasma bubble might play an important role in the generation of postmidnight FAIs.

Role of parametric decay instabilities in generating ionospheric irregularities

International Nuclear Information System (INIS)

Kuo, S.P.; Cheo, B.R.; Lee, M.C.

1983-01-01

We show that purely growing instabilities driven by the saturation spectrum of parametric decay instabilities can produce a broad spectrum of ionospheric irregularities. The threshold field Vertical BarE/sub th/Vertical Bar of the instabilities decreases with the scale lengths lambda of the ionospheric irregularities as Vertical BarE/sub th/Vertical Barproportionallambda -2 in the small-scale range ( -2 with scale lengths larger than a few kilometers. The excitation of kilometer-scale irregularities is strictly restricted by the instabilities themselves and by the spatial inhomogeneity of the medium. These results are drawn from the analyses of four-wave interaction. Ion-neutral collisions impose no net effect on the instabilities when the excited ionospheric irregularities have a field-aligned nature

VHF and UHF radar observations of equatorial F region ionospheric irregularities and background densities

Science.gov (United States)

Towle, D. M.

1980-02-01

A series of measurements of the properties of equatorial ionospheric irregularities were made at Kwajalein, Marshall Islands (M.I.) in August 1977 and July-August 1978. These measurements, sponsored by the Defense Nuclear Agency (DNA), involved coordinated ground-based and in situ sensors. The ARPA Long-Range Tracking and Instrumentation Radar (ALTAIR), operated by Lincoln Laboratory, obtained backscatter and transmission data during five nights in August 1977 and eight nights in July-August 1978. This report describes the ALTAIR data from the night of August 11, 1978, which yield direct quantitative measurements of 1-m and 3/8-m irregularities and of plasma depleted regions. These plasma depleted regions, previously predicted on the basis of theoretical analysis and in situ data, were observed during the decay phase and not the generative phase of the field-aligned irregularities.

Sporadic Fatal Insomnia in an Adolescent

Science.gov (United States)

Blase, Jennifer L.; Cracco, Laura; Schonberger, Lawrence B.; Maddox, Ryan A.; Cohen, Yvonne; Cali, Ignazio

2014-01-01

The occurrence of sporadic prion disease among adolescents is extremely rare. A prion disease was confirmed in an adolescent with disease onset at 13 years of age. Genetic, neuropathologic, and biochemical analyses of the patient’s autopsy brain tissue were consistent with sporadic fatal insomnia, a type of sporadic prion disease. There was no evidence of an environmental source of infection, and this patient represents the youngest documented case of sporadic prion disease. Although rare, a prion disease diagnosis should not be discounted in adolescents exhibiting neurologic signs. Brain tissue testing is necessary for disease confirmation and is particularly beneficial in cases with an unusual clinical presentation. PMID:24488737

On the influence of solar activity on the mid-latitude sporadic E layer

Science.gov (United States)

Pezzopane, Michael; Pignalberi, Alessio; Pietrella, Marco

2015-09-01

To investigate the influence of solar cycle variability on the sporadic E layer (Es), hourly measurements of the critical frequency of the Es ordinary mode of propagation, foEs, and of the blanketing frequency of the Es layer, fbEs, recorded from January 1976 to December 2009 at the Rome (Italy) ionospheric station (41.8° N, 12.5° E), were examined. The results are: (1) a high positive correlation between the F10.7 solar index and foEs as well as between F10.7 and fbEs, both for the whole data set and for each solar cycle separately, the correlation between F10.7 and fbEs being much higher than the one between F10.7 and foEs; (2) a decreasing long-term trend of the F10.7, foEs and fbEs time series, with foEs decreasing more rapidly than F10.7 and fbEs; (3) clear and statistically significant peaks at 11 years in the foEs and fbEs time series, inferred from Lomb-Scargle periodograms.

A statistical study of sporadic sodium layer observed by Sodium lidar at Hefei (31.8° N, 117.3° E

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X.-K. Dou

2009-06-01

Full Text Available Sodium lidar observations of sporadic sodium layers (SSLs during the past 3 years at a mid-latitude location (Hefei, China, 31.8° N, 117.3° E are reported in this paper. From 64 SSL events detected in about 900 h of observation, an SSL occurrence rate of 1 event every 14 h at our location was obtained. This result, combined with previous studies, reveals that the SSL occurrence can be relatively frequent at some mid-latitude locations. Statistical analysis of main parameters for the 64 SSL events was performed. By examining the corresponding data from an ionosonde, a considerable correlation was found with a Pearson coefficient of 0.66 between seasonal variations of SSL and those of sporadic E (Es during nighttime, which was in line with the research by Nagasawa and Abo (1995. From comparison between observations from the University of Science and Technology of China (USTC lidar and from Wuhan Institute of Physics and Mathematics (WIPM lidar (Wuhan, China, 31° N, 114° E, the minimum horizontal range for some events was estimated to be over 500 km.

Ionospheric Irregularities at Mars Probed by MARSIS Topside Sounding

Science.gov (United States)

Harada, Y.; Gurnett, D. A.; Kopf, A. J.; Halekas, J. S.; Ruhunusiri, S.

2018-01-01

The upper ionosphere of Mars contains a variety of perturbations driven by solar wind forcing from above and upward propagating atmospheric waves from below. Here we explore the global distribution and variability of ionospheric irregularities around the exobase at Mars by analyzing topside sounding data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express. As irregular structure gives rise to off-vertical echoes with excess propagation time, the diffuseness of ionospheric echo traces can be used as a diagnostic tool for perturbed reflection surfaces. The observed properties of diffuse echoes above unmagnetized regions suggest that ionospheric irregularities with horizontal wavelengths of tens to hundreds of kilometers are particularly enhanced in the winter hemisphere and at high solar zenith angles. Given the known inverse dependence of neutral gravity wave amplitudes on the background atmospheric temperature, the ionospheric irregularities probed by MARSIS are most likely associated with plasma perturbations driven by atmospheric gravity waves. Though extreme events with unusually diffuse echoes are more frequently observed for high solar wind dynamic pressures during some time intervals, the vast majority of the diffuse echo events are unaffected by varying solar wind conditions, implying limited influence of solar wind forcing on the generation of ionospheric irregularities. Combination of remote and in situ measurements of ionospheric irregularities would offer the opportunity for a better understanding of the ionospheric dynamics at Mars.

Characteristics of ionospheric irregularities causing scintillations at VHF/UHF

International Nuclear Information System (INIS)

Vats, H.O.; Deshpande, M.R.; Rastogi, R.G.

1978-01-01

Some properties of ionization irregularities using amplitude scintillation records of radio beacons from ATS-6 (phase II) at Ootacamund, India have been investigated. For the estimation of scale-size and strength of the irregularities a simple diffraction model has been used which explains only weak and moderate equatorial scintillation observations. It was found that the scale sizes of day time E-region irregularities are smaller than those in the F-region during night time in addition, irregularities are generated initially at large scale sizes which later break up into smaller scale sizes

The interaction between stratospheric monthly mean regional winds and sporadic-E

International Nuclear Information System (INIS)

Çetin, Kenan; Korlaelçi, Serhat; Özcan, Osman

2017-01-01

In the present study, a statistical investigation is carried out to explore whether there is a relationship between the critical frequency (foEs) of the sporadic-E layer that is occasionally seen on the E region of the ionosphere and the quasi-biennial oscillation (QBO) that flows in the east–west direction in the equatorial stratosphere. Multiple regression model as a statistical tool was used to determine the relationship between variables. In this model, the stationarity of the variables (foEs and QBO) was firstly analyzed for each station (Cocos Island, Gibilmanna, Niue Island, and Tahiti). Then, a co-integration test was made to determine the existence of a long-term relationship between QBO and foEs. After verifying the presence of a long-term relationship between the variables, the magnitude of the relationship between variables was further determined using the multiple regression model. As a result, it is concluded that the variations in foEs were explainable with QBO measured at 10 hPa altitude at the rate of 69%, 94%, 79%, and 58% for Cocos Island, Gibilmanna, Niue Island, and Tahiti stations, respectively. It is observed that the variations in foEs were explainable with QBO measured at 70 hPa altitude at the rate of 66%, 69%, 53%, and 47% for Cocos Island, Gibilmanna, Niue Island, and Tahiti stations, respectively. (paper)

High Frequency Backscatter from the Polar and Auroral E-Region Ionosphere

Science.gov (United States)

Forsythe, Victoriya V.

The Earth's ionosphere contains collisional and partially-ionized plasma. The electric field, produced by the interaction between the Earth's magnetosphere and the solar wind, drives the plasma bulk motion, also known as convection, in the F-region of the ionosphere. It can also destabilize the plasma in the E-region, producing irregularities or waves. Intermediate-scale waves with wavelengths of hundreds of meters can cause scintillation and fading of the Global Navigation Satellite System (GNSS) signals, whereas the small-scale waves (lambda Network (SuperDARN). The theoretical part of this work focuses on symmetry properties of the general dispersion relation that describes wave propagation in the collisional plasma in the two-stream and gradient-drift instability regimes. The instability growth rate and phase velocity are examined under the presence of a background parallel electric field, whose influence is demonstrated to break the spatial symmetry of the wave propagation patterns. In the observational part of this thesis, a novel dual radar setup is used to examine E-region irregularities in the magnetic polar cap by probing the E-region along the same line from opposite directions. The phase velocity analysis together with raytracing simulations demonstrated that, in the polar cap, the radar backscatter is primarily controlled by the plasma density conditions. In particular, when the E-region layer is strong and stratified, the radar backscatter properties are controlled by the convection velocity, whereas for a tilted E-layer, the height and aspect angle conditions are more important. Finally, the fundamental dependence of the E-region irregularity phase velocity on the component of the plasma convection is investigated using two new SuperDARN radars at high southern latitudes where plasma convection estimates are accurately deduced from all SuperDARN radars in the southern hemisphere. Statistical analysis is presented showing that the predominance of the

Artificial periodic irregularities in the auroral ionosphere

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M. T. Rietveld

1996-12-01

Full Text Available Artificial periodic irregularities (API are produced in the ionospheric plasma by a powerful standing electromagnetic wave reflected off the F region. The resulting electron-density irregularities can scatter other high-frequency waves if the Bragg scattering condition is met. Such measurements have been performed at mid-latitudes for two decades and have been developed into a useful ionospheric diagnostic technique. We report here the first measurements from a high-latitude station, using the EISCAT heating facility near Tromsø, Norway. Both F-region and lower-altitude ionospheric echoes have been obtained, but the bulk of the data has been in the E and D regions with echoes extending down to 52-km altitude. Examples of API are shown, mainly from the D region, together with simultaneous VHF incoherent-scatter-radar (ISR data. Vertical velocities derived from the rate of phase change during the irregularity decay are shown and compared with velocities derived from the ISR. Some of the API-derived velocities in the 75–115-km height range appear consistent with vertical neutral winds as shown by their magnitudes and by evidence of gravity waves, while other data in the 50–70-km range show an unrealistically large bias. For a comparison with ISR data it has proved difficult to get good quality data sets overlapping in height and time. The initial comparisons show some agreement, but discrepancies of several metres per second do not yet allow us to conclude that the two techniques are measuring the same quantity. The irregularity decay time-constants between about 53 and 70 km are compared with the results of an advanced ion-chemistry model, and height profiles of recorded signal power are compared with model estimates in the same altitude range. The calculated amplitude shows good agreement with the data in that the maximum occurs at about the same height as that of the measured amplitude. The calculated time-constant agrees very well with the

Sporadic radio emission connected with a definite manifestation of solar activity in the near Earth space

Science.gov (United States)

Dudnic, A. V.; Zaljubovski, I. I.; Kartashev, V. M.; Shmatko, E. S.

1985-01-01

Sporadic radio emission of near Earth space at the frequency of 38 MHz is shown to appear in the event of a rapid development of instabilities in the ionospheric plasma. The instabilities are generated due to primary ionospheric disturbances occurring under the influence of solar chromospheric flares.

Adult onset sporadic ataxias: a diagnostic challenge

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Orlando Graziani Povoas Barsottini

2014-03-01

Full Text Available Patients with adult onset non-familial progressive ataxia are classified in sporadic ataxia group. There are several disease categories that may manifest with sporadic ataxia: toxic causes, immune-mediated ataxias, vitamin deficiency, infectious diseases, degenerative disorders and even genetic conditions. Considering heterogeneity in the clinical spectrum of sporadic ataxias, the correct diagnosis remains a clinical challenge. In this review, the different disease categories that lead to sporadic ataxia with adult onset are discussed with special emphasis on their clinical and neuroimaging features, and diagnostic criteria.

Faith in a seed: on the origins of equatorial plasma bubbles

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J. M. Retterer

2014-05-01

Full Text Available Our faith in the seeds of equatorial plasma irregularities holds that there will generally always be density perturbations sufficient to provide the seeds for irregularity development whenever the Rayleigh–Taylor instability is active. When the duration of the time of the Rayleigh–Taylor instability is short, however, the magnitude of the seed perturbations can make a difference in whether the irregularities have a chance to grow to a strength at which the nonlinear development of plumes occurs. In addition, the character of the resulting irregularities reflects the characteristics of the initial seed density perturbation, e.g., their strength, spacing, and, to some extent, their spatial scales, and it is important to know the seeds to help determine the structure of the developed irregularities. To this end, we describe the climatology of daytime and early-evening density irregularities that can serve as seeds for later development of plumes, as determined from the Planar Langmuir Probe (PLP plasma density measurements on the C/NOFS (Communication and Navigation Outage Forecast System satellite mission, presenting their magnitude as a function of altitude, latitude, longitude, local time, season, and phase in the solar cycle (within the C/NOFS observation era. To examine some of the consequences of these density perturbations, they are used as initial conditions for the PBMOD PBMOD (Retterer, 2010a 3-D irregularity model to follow their potential development into larger-amplitude irregularities, plumes, and radio scintillation. "Though I do not believe that a pla[sma bubble] will spring up where no seed has been, I have great faith in a seed. Convince me that you have a seed there, and I am prepared to expect wonders." – Henry David Thoreau

Backscatter measurements of 11-cm equatorial spread-F irregularities

International Nuclear Information System (INIS)

Tsunoda, R.T.

1980-01-01

In the equatorial F-region ionosphere, a turbulent cascade process has been found to exist that extends from irregularity spatial wavelengths longer than tens of kilometers down to wavelengths as short as 36 cm. To investigate the small-scale regime of wavelengths less than 36 cm, an equatorial radar experiment was conducted using a frequency of 1320 MHz that corresponds to an irregularity wavelength of 11 cm. The first observations of radar backscatter from 11-cm field-aligned irregularities (FAI) are described. These measurements extend the spatial wavelength regime of F-region FAI to lengths that approach both electron gyroradius and the Debye length. Agreement of these results with the theory of high-frequency drift waves suggests that these observations may be unique to the equatorial ionosphere. That is, the requirement of low electron densities for which the theroy calls may preclude the existence of 11-cm FAI elsewhere in the F-region ionosphere, except in equatorial plasma bubbles

Non-storm irregular variation of the Dst index

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S. Nakano

2012-01-01

Full Text Available The Dst index has a long-term variation that is not associated with magnetic storms. We estimated the long-term non-storm component of the Dst variation by removing the short-term variation related to magnetic storms. The results indicate that the variation of the non-storm component includes not only a seasonal variation but also an irregular variation. The irregular long-term variation is likely to be due to an anti-correlation with the long-term variation of solar-wind activity. In particular, a clear anti-correlation is observed between the non-storm component of Dst and the long-term variation of the solar-wind dynamic pressure. This means that in the long term, the Dst index tends to increase when the solar-wind dynamic pressure decreases. We interpret this anti-correlation as an indication that the long-term non-storm variation of Dst is influenced by the tail current variation. The long-term variation of the solar-wind dynamic pressure controls the plasma sheet thermal pressure, and the change of the plasma sheet thermal pressure would cause the non-storm tail current variation, resulting in the non-storm variation of Dst.

Long wavelength irregularities in the equatorial electrojet

OpenAIRE

Kudeki, E.; Farley, D. T.; Fejer, Bela G.

1982-01-01

We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach...

New Opportunities for Remote Sensing Ionospheric Irregularities by Fitting Scintillation Spectra

Science.gov (United States)

Carrano, C. S.; Rino, C. L.; Groves, K. M.

2017-12-01

In a recent paper, we presented a phase screen theory for the spectrum of intensity scintillations when the refractive index irregularities follow a two-component power law [Carrano and Rino, DOI: 10.1002/2015RS005903]. More recently we have investigated the inverse problem, whereby phase screen parameters are inferred from scintillation time series. This is accomplished by fitting the spectrum of intensity fluctuations with a parametrized theoretical model using Maximum Likelihood (ML) methods. The Markov-Chain Monte-Carlo technique provides a-posteriori errors and confidence intervals. The Akaike Information Criterion (AIC) provides justification for the use of one- or two-component irregularity models. We refer to this fitting as Irregularity Parameter Estimation (IPE) since it provides a statistical description of the irregularities from the scintillations they produce. In this talk, we explore some new opportunities for remote sensing ionospheric irregularities afforded by IPE. Statistical characterization of irregularities and the plasma bubbles in which they are embedded provides insight into the development of the underlying instability. In a companion paper by Rino et al., IPE is used to interpret scintillation due to simulated EPB structure. IPE can be used to reconcile multi-frequency scintillation observations and to construct high fidelity scintillation simulation tools. In space-to-ground propagation scenarios, for which an estimate of the distance to the scattering region is available a-priori, IPE enables retrieval of zonal irregularity drift. In radio occultation scenarios, the distance to the irregularities is generally unknown but IPE enables retrieval of Fresnel frequency. A geometric model for the effective scan velocity maps Fresnel frequency to Fresnel scale, yielding the distance to the irregularities. We demonstrate this approach by geolocating irregularities observed by the CORISS instrument onboard the C/NOFS satellite.

Characteristics and sources of the electron density irregularities in the mid latitude E and Fregions

Science.gov (United States)

2017-05-10

and has since been monitoring the occurrence of field-aligned irregularities ( FAIs ) in the northern middle latitudes. We investigated the...characteristics and occurrence climatology of the FAIs in the middle latitude E- and F-region ionosphere using the Daejeon VHF radar data. Depending on the...sunset and post-sunrise periods. The F-region FAIs in the mid-latitude are bounded to occur during the nighttime between local sunset and sunrise [J

Equatorial F-region plasma depletion drifts: latitudinal and seasonal variations

Directory of Open Access Journals (Sweden)

A. A. Pimenta

2003-12-01

Full Text Available The equatorial ionospheric irregularities have been observed in the past few years by different techniques (e.g. ground-based radar, digisonde, GPS, optical instruments, in situ satellite and rocket instrumentation, and its time evolution and propagation characteristics can be used to study important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. At present, one of the most powerful optical techniques to study the large-scale ionospheric irregularities is the all-sky imaging photometer system, which normally measures the strong F-region nightglow 630 nm emission from atomic oxygen. The monochromatic OI 630 nm emission images usually show quasi-north-south magnetic field-aligned intensity depletion bands, which are the bottomside optical signatures of large-scale F-region plasma irregularities (also called plasma bubbles. The zonal drift velocities of the plasma bubbles can be inferred from the space-time displacement of the dark structures (low intensity regions seen on the images. In this study, images obtained with an all-sky imaging photometer, using the OI 630 nm nightglow emission, from Cachoeira Paulista (22.7° S, 45° W, 15.8° S dip latitude, Brazil, have been used to determine the nocturnal monthly and latitudinal variation characteristics of the zonal plasma bubble drift velocities in the low latitude (16.7° S to 28.7° S region. The east and west walls of the plasma bubble show a different evolution with time. The method used here is based on the western wall of the bubble, which presents a more stable behavior. Also, the observed zonal plasma bubble drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-90 model (Hedin et al., 1991 to investigate the thermosphere-ionosphere coupling. Salient features from this study are presented and discussed.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric irregularities; instruments and techniques

Irregular Applications: Architectures & Algorithms

Energy Technology Data Exchange (ETDEWEB)

Feo, John T.; Villa, Oreste; Tumeo, Antonino; Secchi, Simone

2012-02-06

Irregular applications are characterized by irregular data structures, control and communication patterns. Novel irregular high performance applications which deal with large data sets and require have recently appeared. Unfortunately, current high performance systems and software infrastructures executes irregular algorithms poorly. Only coordinated efforts by end user, area specialists and computer scientists that consider both the architecture and the software stack may be able to provide solutions to the challenges of modern irregular applications.

Systematic study of intermediate-scale structures of equatorial plasma irregularities in the ionosphere based on CHAMP observations

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Hermann eLühr

2014-03-01

Full Text Available Equatorial spread-F ionospheric plasma irregularities on the night-side, commonly called equatorial plasma bubbles (EPB, include electron density variations over a wide range of spatial scales. Here we focus on intermediate-scale structures ranging from 100 m to 10 km, which play an important role in the evolution of EPBs. High-resolution CHAMP magnetic field measurements sampled along north-south track at 50 Hz are interpreted in terms of diamagnetic effect for illustrating the details of electron density variations. We provide the first comprehensive study on intermediate-scale density structures associated with EPBs, covering a whole solar cycle from 2000 to 2010. The large number of detected events, almost 9000, allows us to draw a detailed picture of the plasma fine structure. The occurrence of intermediate-scale events is strongly favoured by high solar flux. During times of F10.7 < 100 sfu practically no events were observed. The longitudinal distribution of our events with respect to season or local time agrees well with that of the EPBs, qualifying the fine structure as a common feature, but the occurrence rates are smaller by a factor of 4 during the period 2000-2005. Largest amplitude electron density variations appear at the poleward boundaries of plasma bubbles. Above the dip-equator recorded amplitudes are small and fall commonly below our resolution. Events can generally be found at local times between 19 and 24 LT, with a peak lasting from 20 to 22 LT. The signal spectrum can be approximated by a power law. Over the frequency range 1 – 25 Hz we observe spectral indices between -1.4 and -2.6 with peak occurrence rates around -1.9. There is a weak dependence observed of the spectral index on local time. Towards later hours the spectrum becomes shallower. Similarly for the latitude dependence, there is a preference of shallower spectra for latitudes poleward of the ionisation anomaly crest. Our data suggest that the generation of

Radar Observations of 8.3-m scale equatorial spread F irregularities over Trivandrum

Directory of Open Access Journals (Sweden)

D. Tiwari

2004-03-01

Full Text Available In this paper, we present observations of equatorial spread F (ESF irregularities made using a newly installed 18MHz radar located at Trivandrum. We characterize the morphology and the spectral parameters of the 8.3-m ESF irregularities which are found to be remarkably different from that observed so extensively at the 3-m scale size. We also present statistical results of the irregularities in the form of percentage occurrence of the echoes and spectral parameters (SNR, Doppler velocity, Spectral width. The Doppler spectra are narrower, less structured and less variable in time as compared to those observed for 3-m scale size. We have never observed the ESF irregularity velocities to be supersonic here unlike those at Jicamarca, and the velocities are found to be within ±200ms–1. The spectral widths are found to be less than 150ms–1. Hence, the velocities and spectral width both are smaller than those reported for 3-m scale size. The velocities and spectral widths are further found to be much smaller than those of the American sector. These observations are compared with those reported elsewhere and discussed in the light of present understanding on the ESF irregularities at different wavelengths. Key words. Ionoshphere (equatorial ionosphere, plasma waves and instabilities; ionospheric irregularities

Intermittent thermal plasma acceleration linked to sporadic motions of the magnetopause, first Cluster results

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J.-A. Sauvaud

Full Text Available This paper presents the first observations with Cluster of a very dense population of thermal ionospheric ions (H⁺, He⁺, O⁺ locally "accelerated" perpendicularly to the local magnetic field in a region adjacent to the magnetopause and on its magnetospheric side. The observation periods follow a long period of very weak magnetic activity. Recurrent motions of the magnetopause are, in the presented cases, unexpectedly associated with the appearance inside closed field lines of recurrent energy structures of ionospheric ions with energies in the 5 eV to  ~1000 eV range. The heaviest ions were detected with the highest energies. Here, the ion behaviour is interpreted as resulting from local electric field enhancements/decreases which adiabatically enhance/lower the bulk energy of a local dense thermal ion population. This drift effect, which is directly linked to magnetopause motions caused by pressure changes, allows for the thermal ions to overcome the satellite potential and be detected by the suprathermal CIS Cluster experiment. When fast flowing, i.e. when detectable, the density (~ 1 cm^-3 of these ions from a terrestrial origin is (in the cases presented here largely higher than the local density of ions from magnetospheric/plasma sheet origin which poses again the question of the relative importance of solar and ionospheric sources for the magnetospheric plasma even during very quiet magnetic conditions.

Key words. Ionosphere (planetary ionosphere; plasma convection Magnetospheric physics (magnetopause, cusp and boundary layers

Bottomside sinusoidal irregularities in the equatorial F region

Science.gov (United States)

Valladares, C. E.; Hanson, W. B.; Mcclure, J. P.; Cragin, B. L.

1983-01-01

By using the Ogo 6 satellite, McClure and Hanson (1973) have discovered sinusoidal irregularities in the equatorial F region ion number density. In the present investigation, a description is provided of the properties of a distinct category of sinusoidal irregularities found in equatorial data from the AE-C and AE-E satellites. The observed scale sizes vary from about 300 m to 3 km in the direction perpendicular to B, overlapping with and extending the range observed by using Ogo 6. Attention is given to low and high resolution data, a comparison with Huancayo ionograms, the confinement of 'bottomside sinusoidal' (BSS) irregularities essentially to the bottomside of the F layer, spectral characteristics, and BSS, scintillation, and ionosonde observations.

The Occurrence of Small-scale Irregularities in the Mid-latitude Ionosphere from SuperDARN HF Radar Observations

Science.gov (United States)

Ruohoniemi, J. M.; Baker, J. B.; Maimaiti, M.; Oksavik, K.; Erickson, P. J.; Scales, W.; Eltrass, A.

2017-12-01

The mid-latitude radars of the SuperDARN network routinely observe backscatter from nighttime decameter-scale F region irregularities at latitudes well equatorward of the auroral boundary. This Sub-Auroral Ionospheric Scatter (SAIS) is strongly distinguished from auroral and SAPS backscatter by low Doppler velocities ( tens m/s) and stable, long-lived ( hours) occurrence in discrete events that are extended in both latitude and longitude. Statistical and event studies of SAIS with the SuperDARN radars indicate that the subauroral F region ionosphere is replete with irregularities during events, at least poleward of the 50° Λ horizon of the North American mid-latitude radars, and that radar observation of SAIS backscatter is then primarily limited by the magnetic aspect condition. Joint experiments with incoherent scatter radar have furnished sets of plasma measurements suitable for testing theories of plasma instability. Modeling work stimulated by the observations has explored the temperature-gradient instability (TGI) and the gradient drift instability (GDI) as possible sources of the irregularities. In this talk we review the findings on the occurrence of the SAIS category of mid-latitude F region irregularities, summarize the results of the modeling work, and discuss future research directions.

Equatorial F-region plasma depletion drifts: latitudinal and seasonal variations

Directory of Open Access Journals (Sweden)

A. A. Pimenta

Full Text Available The equatorial ionospheric irregularities have been observed in the past few years by different techniques (e.g. ground-based radar, digisonde, GPS, optical instruments, in situ satellite and rocket instrumentation, and its time evolution and propagation characteristics can be used to study important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. At present, one of the most powerful optical techniques to study the large-scale ionospheric irregularities is the all-sky imaging photometer system, which normally measures the strong F-region nightglow 630 nm emission from atomic oxygen. The monochromatic OI 630 nm emission images usually show quasi-north-south magnetic field-aligned intensity depletion bands, which are the bottomside optical signatures of large-scale F-region plasma irregularities (also called plasma bubbles. The zonal drift velocities of the plasma bubbles can be inferred from the space-time displacement of the dark structures (low intensity regions seen on the images. In this study, images obtained with an all-sky imaging photometer, using the OI 630 nm nightglow emission, from Cachoeira Paulista (22.7° S, 45° W, 15.8° S dip latitude, Brazil, have been used to determine the nocturnal monthly and latitudinal variation characteristics of the zonal plasma bubble drift velocities in the low latitude (16.7° S to 28.7° S region. The east and west walls of the plasma bubble show a different evolution with time. The method used here is based on the western wall of the bubble, which presents a more stable behavior. Also, the observed zonal plasma bubble drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-90 model (Hedin et al., 1991 to investigate the thermosphere-ionosphere coupling. Salient features from this study are presented

Updated clinical diagnostic criteria for sporadic Creutzfeldt-Jakob disease

Science.gov (United States)

Kallenberg, K.; Summers, D. M.; Romero, C.; Taratuto, A.; Heinemann, U.; Breithaupt, M.; Varges, D.; Meissner, B.; Ladogana, A.; Schuur, M.; Haik, S.; Collins, S. J.; Jansen, Gerard H.; Stokin, G. B.; Pimentel, J.; Hewer, E.; Collie, D.; Smith, P.; Roberts, H.; Brandel, J. P.; van Duijn, C.; Pocchiari, M.; Begue, C.; Cras, P.; Will, R. G.; Sanchez-Juan, P.

2009-01-01

Several molecular subtypes of sporadic Creutzfeldt–Jakob disease have been identified and electroencephalogram and cerebrospinal fluid biomarkers have been reported to support clinical diagnosis but with variable utility according to subtype. In recent years, a series of publications have demonstrated a potentially important role for magnetic resonance imaging in the pre-mortem diagnosis of sporadic Creutzfeldt–Jakob disease. Magnetic resonance imaging signal alterations correlate with distinct sporadic Creutzfeldt–Jakob disease molecular subtypes and thus might contribute to the earlier identification of the whole spectrum of sporadic Creutzfeldt–Jakob disease cases. This multi-centre international study aimed to provide a rationale for the amendment of the clinical diagnostic criteria for sporadic Creutzfeldt–Jakob disease. Patients with sporadic Creutzfeldt–Jakob disease and fluid attenuated inversion recovery or diffusion-weight imaging were recruited from 12 countries. Patients referred as ‘suspected sporadic Creutzfeldt–Jakob disease’ but with an alternative diagnosis after thorough follow up, were analysed as controls. All magnetic resonance imaging scans were assessed for signal changes according to a standard protocol encompassing seven cortical regions, basal ganglia, thalamus and cerebellum. Magnetic resonance imaging scans were evaluated in 436 sporadic Creutzfeldt–Jakob disease patients and 141 controls. The pattern of high signal intensity with the best sensitivity and specificity in the differential diagnosis of sporadic Creutzfeldt–Jakob disease was identified. The optimum diagnostic accuracy in the differential diagnosis of rapid progressive dementia was obtained when either at least two cortical regions (temporal, parietal or occipital) or both caudate nucleus and putamen displayed a high signal in fluid attenuated inversion recovery or diffusion-weight imaging magnetic resonance imaging. Based on our analyses, magnetic

Plasma Physics of the Subauroral Space Weather

Science.gov (United States)

2016-03-20

or convey any rights or permission to manufacture, use, or sell any patented invention that may relate to them. This report was cleared for...irregular subauroral regions create strong scintillations of UHF and GPS L1 band signals. Irregular structures in the plasmasphere guide VLF whistler waves ...drifts, substorm-injected plasma jets, SAID/SAPS-related plasma waves , plasmaspheric boundary layer 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

On the Total Edge Irregularity Strength of Generalized Butterfly Graph

Science.gov (United States)

Dwi Wahyuna, Hafidhyah; Indriati, Diari

2018-04-01

Let G(V, E) be a connected, simple, and undirected graph with vertex set V and edge set E. A total k-labeling is a map that carries vertices and edges of a graph G into a set of positive integer labels {1, 2, …, k}. An edge irregular total k-labeling λ: V(G) ∪ E(G) → {1, 2, …, k} of a graph G is a total k-labeling such that the weights calculated for all edges are distinct. The weight of an edge uv in G, denoted by wt(uv), is defined as the sum of the label of u, the label of v, and the label of uv. The total edge irregularity strength of G, denoted by tes(G), is the minimum value of the largest label k over all such edge irregular total k-labelings. A generalized butterfly graph, BFn , obtained by inserting vertices to every wing with assumption that sum of inserting vertices to every wing are same then it has 2n + 1 vertices and 4n ‑ 2 edges. In this paper, we investigate the total edge irregularity strength of generalized butterfly graph, BFn , for n > 2. The result is tes(B{F}n)=\\lceil \\frac{4n}{3}\\rceil .

Radar Observations of 8.3-m scale equatorial spread F irregularities over Trivandrum

Directory of Open Access Journals (Sweden)

D. Tiwari

2004-03-01

Full Text Available In this paper, we present observations of equatorial spread F (ESF irregularities made using a newly installed 18MHz radar located at Trivandrum. We characterize the morphology and the spectral parameters of the 8.3-m ESF irregularities which are found to be remarkably different from that observed so extensively at the 3-m scale size. We also present statistical results of the irregularities in the form of percentage occurrence of the echoes and spectral parameters (SNR, Doppler velocity, Spectral width. The Doppler spectra are narrower, less structured and less variable in time as compared to those observed for 3-m scale size. We have never observed the ESF irregularity velocities to be supersonic here unlike those at Jicamarca, and the velocities are found to be within ±200ms^–1. The spectral widths are found to be less than 150ms^–1. Hence, the velocities and spectral width both are smaller than those reported for 3-m scale size. The velocities and spectral widths are further found to be much smaller than those of the American sector. These observations are compared with those reported elsewhere and discussed in the light of present understanding on the ESF irregularities at different wavelengths.

Key words. Ionoshphere (equatorial ionosphere, plasma waves and instabilities; ionospheric irregularities

Aspects of plasma cutting in AISI 321 stainless steel

International Nuclear Information System (INIS)

Souza Barros, I. de; Cardoso, P.E.

1985-10-01

The utilization of plasma cutting process in AISI 321 stainless steel heavy plates for fabricating nozzles for nuclear reactors was evaluated. The effect of current, electric potential and cutting speed are studied. The superficial irregularity and the microstructure of the zone affected by the cut were analyzed by measurements of roughness, optical metallography and microhardness. (E.G.) [pt

Fatores de risco na gagueira desenvolvimental familial e isolada Risk factors in the familial and sporadic developmental stuttering

Directory of Open Access Journals (Sweden)

Cristiane Moço Canhetti de Oliveira

2011-04-01

Full Text Available OBJETIVO: investigar e comparar os achados dos fatores de risco para a cronicidade da gagueira em crianças com gagueira desenvolvimental familial e isolada. MÉTODOS: participaram 60 crianças de ambos os gêneros, divididas em dois grupos: GI - 30 crianças com gagueira desenvolvimental familial; GII - 30 crianças com gagueira desenvolvimental isolada. A coleta de dados foi realizada por meio do Protocolo de Risco para a Gagueira do Desenvolvimento - PRGD (Andrade, 2006, que considera os seguintes fatores de risco: idade, gênero, tipo de surgimento e tempo de duração das disfluências, tipologia das disfluências, fatores comunicativos e qualitativos associados, histórico mórbido pré, peri e pós natal, fatores estressantes que ocorreram próximo ao surgimento do distúrbio, histórico familial, reação pessoal, familiar e social e atitudes familiares. RESULTADOS: quando o grupo I (GI foi comparado com o grupo II (GII, a única diferença estatisticamente significante foi com relação aos fatores estressantes que ocorreram próximo ao surgimento do distúrbio. CONCLUSÃO: os resultados confirmam a natureza complexa da gagueira, bem como a necessidade de se investigar os vários fatores considerados como de risco para o distúrbio, com intuito de melhorar a compreensão de suas possíveis etiologias.PURPOSE: to investigate and compare the risk factors for stuttering between children with familial developmental stuttering and children with sporadic developmental stuttering. METHODS: 60 children of both genders with stuttering took part, divided in two groups: GI - 30 children with familial developmental stuttering; GII - 30 children with sporadic developmental stuttering. Data were gathered through the Protocol of Risk for the Developmental Stuttering - PRGD (Andrade, 2006, which considers the following factors: age; gender; manner of onset and time of duration for the disfluencies; typology of the disfluencies; associated communicative

Irregular ionization and scintillation of the ionosphere in equator region

International Nuclear Information System (INIS)

Shinno, Kenji

1974-01-01

The latest studies on the scintillation in satellite communication and its related irregularities of ionosphere are reviewed. They were made clear by means of spread-F, the direct measurement with scientific satellites, VHF radar observation, and radio wave propagation in equator region. The fundamental occurrence mechanism may be instability of plasma caused by the interaction of movement of neutral atmosphere and magnetic field. Comparison of the main characteristics of scintillation, namely the dependence on region, solar activity, season, local time, geomagnetic activity, movement in ionosphere, scattering source, frequency and transmission mode, was made and the correlation among spread-F, TEP and scintillation was summarized. The latest principal studies were the observations made by Intelsat and by ATS. Scintillation of Syncom-3 and Intelsat-II-F2 and spread-F by ionosphere observation were compared by Huang. It is reasonable to consider that the occurrence of scintillation is caused by the irregularities in ionosphere which are particular in equator region, because of the similar characteristics of spread-F and VHF propagation in the equator region. These three phenomena may occur in relation to the irregularities of ionosphere. Interpretation of spread-F and the abnormal propagation wave across the equator are given. The study using VHF radar and the movement of irregular ionization by the direct observation with artificial satellites are reviewd. (Iwakiri, K.)

Remote sensing of auroral E region plasma structures by radio, radar, and UV techniques at solar minimum

International Nuclear Information System (INIS)

Basu, S.; Valladares, C.E.; Basu, S.; Eastes, R.; Huffman, R.E.; Daniell, R.E.; Chaturvedi, P.K.; Livingston, R.C.

1993-01-01

The unique capability of the Polar BEAR satellite to simultaneously image auroral luminosities at multiple ultraviolet (UV) wavelengths and to remote sense large-scale (hundreds to tens of kilometers) and small-scale (kilometers to hundreds of meters) plasma density structures with its multifrequency beacon package is utilized to probe the auroral E region in the vicinity of the incoherent scatter radar (ISR) facility near Sondrestrom. In particular, we present coordinated observations on two nights obtained during the sunspot minimum (sunspot number < 10) January-February 1987 period when good spatial and temporal conjunction was obtained between Polar BEAR overflights and Sondrestrom ISR measurements. With careful coordinated observations we were able to confirm that the energetic particle precipitation responsible for the UV emissions causes the electron density increases in the E region. The integrations up to the topside of these ISR electron density profiles were consistent with the total electron content (TEC) measured by the Polar BEAR satellite. An electron transport model was utilized to determine quantitatively the electron density profiles which could be produced by the particle precipitation, which also produced multiple UV emissions measured by the imager; these profiles were found to be in good agreement with the observed ISR profiles in the E region. This outer scale size is also consistent with the measured phase to amplitude scintillation ratio. An estimate of the linear growth rate of the gradient-drift instability in the E region shows that these plasma density irregularities could have been generated by this process. The mutual consistency of these different sets of measurements provides confidence in the ability of the different techniques to remote sense large- and small-scale plasma density structures in the E region at least during sunspot minimum when the convection-dominated high-latitude F region is fairly weak. 56 refs., 16 figs

Pontine hyperperfusion in sporadic hyperekplexia.

Science.gov (United States)

Vetrugno, Roberto; Mascalchi, Mario; Vella, Alessandra; Della Nave, Riccardo; Guerrini, Laura; Vattimo, Angelo; del Giudice, Emanuele Miraglia; Plazzi, Giuseppe; D'Angelo, Roberto; Greco, Giovanni; Montagna, Pasquale

2007-09-01

To explore with neuroimaging techniques the anatomical and functional correlates of sporadic hyperekplexia. Two elderly women with sporadic hyperekplexia underwent neurophysiological assessment, MRI of the brain and proton magnetic resonance spectroscopy (1H-MRS) of the brainstem and frontal lobes. Regional cerebral blood flow was investigated with single photon emission tomography (SPECT) during evoked startles and at rest. Both patients showed excessively large and non-habituating startle responses. In both patients, MRI showed impingement of the brainstem by the vertebrobasilar artery, lack of frontal or brainstem abnormalities on 1H-MRS and hyperperfusion in the dorsal pons and cingulate cortex, and superior frontal gyrus at SPECT during evoked startles. In our patients with hyperekplexia, the vertebrobasilar arteries were found to impinge on the brainstem. Neurophysiological findings and neurofunctional imaging of evoked startles indicated a pontine origin of the movement disorder modulated by activation in cortical, especially frontal, areas. The neurofunctional correlates of evoked startles in human sporadic hyperekplexia are similar to those observed for the startle circuit in animals.

VHF and HF radar measurements of E and R region plasma drifts at the magnetic equator

International Nuclear Information System (INIS)

Viswanathan, K.S.; Namboothiri, S.P.; Rao, P.B.

1992-01-01

Simultaneous observations of E region horizontal irregularity drifts by VHF backscatter radar and of F region vertical plasma drift by HF Doppler radar conducted during daytime on a few magnetically quiet days at Trivandrum (dip 0.2 degree N) are presented. A comparative study of the two measurements indicates broadly (1) a resemblance in the daytime changes of the E-W component between the electric field and (2) evidence of quasi-periodic electric field variations with periods ranging mostly from 1 to 2 hours. The electric fields derived from HF Doppler radar observations are somewhat lower than those deduced by HVHF radar observations. The correlation coefficient for the variations of the electric fields measured by the two experimental techniques is found to be in the range of about 0.5 to 0.9. The observed difference in the E and F region electric fields at the magnetic equator is discussed in terms of the measurement uncertainties and the limitations involved in deriving E-W electric fields. The observations are suggestive of a latitudinal variation in the E-W component of the electric field in the equatorial ionosphere

Niacin treatment increases plasma homocyst(e)ine levels.

Science.gov (United States)

Garg, R; Malinow, M; Pettinger, M; Upson, B; Hunninghake, D

1999-12-01

Studies have reported high levels of plasma homocyst(e)ine as an independent risk factor for arterial occlusive disease. The Cholesterol Lowering Atherosclerosis Study reported an increase in plasma homocyst(e)ine levels in patients receiving both colestipol and niacin compared with placebo. Thus the objective of this study was to examine the effect of niacin treatment on plasma homocyst(e)ine levels. The Arterial Disease Multiple Intervention Trial, a multicenter randomized, placebo-controlled trial, examined the effect of niacin compared with placebo on homocyst(e)ine in a subset of 52 participants with peripheral arterial disease. During the screening phase, titration of niacin dose from 100 mg to 1000 mg daily resulted in a 17% increase in mean plasma homocyst(e)ine level from 13.1 +/- 4.4 micromol/L to 15.3 +/- 5.6 micromol/L (P ine levels in the niacin group and a 7% decrease in the placebo group (P =.0001). This difference remained statistically significant at the end of follow-up at 48 weeks. Niacin substantially increased plasma homocyst(e)ine levels, which could potentially reduce the expected benefits of niacin associated with lipoprotein modification. However, plasma homocyst(e)ine levels can be decreased by folic acid supplementation. Thus further studies are needed to determine whether B vitamin supplementation to patients undergoing long-term niacin treatment would be beneficial.

Hypermethylation of the FANCC and FANCL Promoter Regions in Sporadic Acute Leukaemia

Directory of Open Access Journals (Sweden)

C. J. Hess

2008-01-01

Full Text Available Objective: Inactivation of the FA-BRCA pathway results in chromosomal instability. Fanconi anaemia (FA patients have an inherited defect in this pathway and are strongly predisposed to the development of acute myeloid leukaemia (AML. Studies in sporadic cancers have shown promoter methylation of the FANCF gene in a significant proportion of various solid tumours. However, only a single leukaemic case with methylation of one of the FA-BRCA genes has been described to date, i.e. methylation of FANCF in cell line CHRF-288. We investigated the presence of aberrant methylation in 11 FA-BRCA genes in sporadic cases of leukaemia.

Star Formation in Irregular Galaxies.

Science.gov (United States)

Hunter, Deidre; Wolff, Sidney

1985-01-01

Examines mechanisms of how stars are formed in irregular galaxies. Formation in giant irregular galaxies, formation in dwarf irregular galaxies, and comparisons with larger star-forming regions found in spiral galaxies are considered separately. (JN)

Polimorfismo da apolipoproteína e nos familiares em primeiro grau de pacientes com doença de Alzheimer familial ou esporádica Apolipoprotein e polymorphism in first-degree relatives of patients with familial or sporadic Alzheimer's disease

Directory of Open Access Journals (Sweden)

João de Castilho Cação

2007-06-01

Full Text Available INTRODUÇÃO: A apolipoproteína E (apo E é reconhecida como fator de risco para doença de Alzheimer (DA. OBJETIVO: Analisar o polimorfismo da apo E nos familiares em primeiro grau de pacientes com DA familial ou esporádica do tipo tardio, comparando a famílias sem DA. MÉTODO: Foram estudados 40 pacientes com DA familial ou esporádica do tipo tardio, sendo os grupos classificados como provável, segundo critérios da NINCS-ADRDA. RESULTADO: O alelo épsilon3 foi o mais freqüente em todos os grupos. Observou-se freqüência mais elevada de épsilon4 comparando os familiares dos probandos aos do grupo controle (pINTRODUCTION: Apolipoproteín E (apo E has been recognized as a risk factor for Alzheimer disease (AD. OBJECTIVE: To analyze apo E polymorphism in first-degree relatives of patients with familial or sporadic late-onset AD comparing with families without AD. METHOD: Forty patients with familial or sporadic late-onset of AD, being both groups classified as probable, according of NINCS-ADRDA’s criteria. RESULTS: Allele epsilon3 was the most frequent in all of these groups. Higher frequency of epsilon4 when comparing the relatives of the probands with the relatives of the control group (p<0,0001 was observed. Allele epsilon2 showed significant difference only between relatives of familial AD and relatives of control group (p=0,026. CONCLUSION: Apo E polymorphism has not differentiated familial from sporadic AD. The study of families allows to amplify the alelles epsilon2 and epsilon4 representativity, revealing, their value as protecting factor and of risk for AD, respectively.

Radar observations of density gradients, electric fields, and plasma irregularities near polar cap patches in the context of the gradient-drift instability

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Lamarche, Leslie J.; Makarevich, Roman A.

2017-03-01

We present observations of plasma density gradients, electric fields, and small-scale plasma irregularities near a polar cap patch made by the Super Dual Auroral Radar Network radar at Rankin Inlet (RKN) and the northern face of Resolute Bay Incoherent Scatter Radar (RISR-N). RKN echo power and occurrence are analyzed in the context of gradient-drift instability (GDI) theory, with a particular focus on the previously uninvestigated 2-D dependencies on wave propagation, electric field, and gradient vectors, with the latter two quantities evaluated directly from RISR-N measurements. It is shown that higher gradient and electric field components along the wave vector generally lead to the higher observed echo occurrence, which is consistent with the expected higher GDI growth rate, but the relationship with echo power is far less straightforward. The RKN echo power increases monotonically as the predicted linear growth rate approaches zero from negative values but does not continue this trend into positive growth rate values, in contrast with GDI predictions. The observed greater consistency of echo occurrence with GDI predictions suggests that GDI operating in the linear regime can control basic plasma structuring, but measured echo strength may be affected by other processes and factors, such as multistep or nonlinear processes or a shear-driven instability.

Searching for effects caused by thunderstorms in midlatitude sporadic E layers

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Barta, Veronika; Haldoupis, Christos; Sátori, Gabriella; Buresova, Dalia; Chum, Jaroslav; Pozoga, Mariusz; Berényi, Kitti A.; Bór, József; Popek, Martin; Kis, Árpád; Bencze, Pál

2017-08-01

Possible thunderstorm - sporadic E (Es) layer coupling effects are investigated during two measurement periods, one in 2013 and one in 2014. The analysis was based on ionospheric observations obtained from a Digisonde at Pruhonice, the Czech Republic, an ionosonde at Nagycenk, Hungary, and a 3.59 MHz five-point continuous HF Doppler system located in the western part of the Czech Republic. The latter is capable of detecting ionospheric wave-like variations caused by neutral atmospheric waves generated by thunderstorms. The present study searches for possible impacts on Es layers caused by the presence of two active thunderstorms: one passing across the Czech Republic on June 20, 2013 (19:00-01:00 LT), and one through Hungary on July 30, 2014 (11:00-01:00 LT). During these two time periods, presence and parameters of Es layer were inferred from ionograms, recorded every minute at Pruhonice and every two minutes at Nagycenk, whereas concurrent lightning activity was monitored by the LINET detection network. In addition, transient luminous events (TLEs) were also observed during both nights from Sopron, Hungary and from Nýdek, the Czech Republic. A noticeable fact was the reduction and disappearance of the ongoing Es layer activity during part of the time in both of the traversing thunderstorms. The analysis indicated that the critical frequency foEs dropped below ionosonde detection levels in both cases, possibly because of thunderstorm activity effects. This option, however, needs more case studies in order to be further substantiated.

Parametric studies in ohmically heated plasmas in Heliotron E

International Nuclear Information System (INIS)

Mutoh, T.; Besshou, S.; Ijiri, Y.

1983-01-01

Parametric studies of volume averaged electron temperature and global electron energy confinement time /tau/epsilon /SUB e/ of ohmically heated Heliotron E plasmas have been performed using a data acquisition computer system. The scaling laws α (I /SUB OH/ x B/n /SUB e/) /SUP 1/2/ and /tau/epsilon /SUB e/ α n /SUP -1/2/ /SUB e/ x B/I /SUP 3/2/ /SUB OH/ are obtained directly by a code which fits the exponents of the plasma parameters ponents of the plasma parameters to the electron temperature and confinement time. The ohmically heated plasma confinement time /tau/epsilon /SUB e/ is shown to be related to the drift parameters xi (= V /SUB De/ /V /SUB Te/). The dependences of the energy confinement time on other plasma parameters is also presented. An investigation is made of the correlation between MHD activity and the confinement

Observational study of ionospheric irregularities and GPS scintillations associated with the 2012 tropical cyclone Tembin passing Hong Kong

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Yang, Zhe; Liu, Zhizhao

2016-05-01

This study presents the ionospheric responses observed in Hong Kong to a Typhoon, namely, Tembin, from the aspects of the occurrence of ionospheric irregularities and scintillations, using Global Positioning System (GPS) observations from a ground-based GPS scintillation monitoring station in Hong Kong and from GPS receivers on board the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. The ionospheric irregularities and scintillations are characterized by the rate of total electron content variation index (ROTI) and the amplitude scintillation index S4, respectively. The typhoon Tembin formed over the western North Pacific during 18-30 August 2012 and approached Hong Kong during 24-27 August 2012 with the closest distance 290 km from Hong Kong at around 17 universal time (UT) on 25 August 2012. The ground-based observations indicate that in the nighttime period of 20:00-02:00 local time (LT = UT + 8 h) on 26 August when Tembin passed closely to Hong Kong, the ionospheric irregularities and scintillations of GPS signals were observed in the south of Hong Kong, over the area of 13°N ~ 23°N in latitude and 110°E ~ 120°E in longitude. From the COSMIC observations, it shows that the number of radio occultation scintillation events peaks on 26 August 2012 during the passage of Tembin. Without the presence of strong geomagnetic or solar activity, it is suspected that gravity waves might be generated in the lower atmosphere and likely seed the formation of ionospheric plasma irregularities. This work for the first time from Hong Kong observes the sign of coupling between the lower atmosphere and ionosphere in a tropical cyclone event, combining both ground- and space-based GPS observation data.

Inheritable and sporadic non-autoimmune hyperthyroidism.

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Ferraz, Carolina; Paschke, Ralf

2017-03-01

Hyperthyroidism is a clinical state that results from high thyroid hormone levels which has multiple etiologies, manifestations, and potential therapies. Excluding the autoimmune Graves disease, autonomic adenomas account for the most import cause of non-autoimmune hyperthyroidism. Activating germline mutations of the TSH receptor are rare etiologies for hyperthyroidism. They can be inherited in an autosomal dominant manner (familial or hereditary, FNAH), or may occur sporadically as a de novo condition, also called: persistent sporadic congenital non-autoimmune hyperthyroidism (PSNAH). These three conditions: autonomic adenoma, FNAH and PSNAH constitute the inheritable and sporadic non-autoimmune hyperthyroidism. Particularities in epidemiology, etiology, molecular and clinical aspects of these three entities will be discussed in this review in order to guide to an accurate diagnosis allowing among others genetic counseling and presymptomatic diagnosis for the affected families. The optimal treatment based on the right diagnosis will avoid consequences of a persistent or relapsing hyperthyroidism. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Time and latitudinal distribution of the ionospheric irregularities in Brazil, through the VHF-scintillation and ionogram data analysis

International Nuclear Information System (INIS)

Nelson, O.R.

1984-01-01

Equatorial ionospheric irregularity distribution morphology, and dynamics, and the dynamics of the ambient ionosphere were investigated. Spread F data from ionograms over Fortaleza (4 0 S; 38 0 O) and Cachoeira Paulista (22,7 0 S; 45 0 O), and simultaneous VHF scintillations of geoestationary satellite beacon received over Natal (5,6 0 S; 33,7 0 O) were used to determine the irregularity local time versus seasonal distribution, over the equatorial and low latitude location, during the solar activity maximum as well as minimum epochs. Concept of flux tube alignment properties of the transequatorial plasma bubbles were used to determine statistical features of the plasma bubble rise velocities. Calculations of plasma bubble rise velocities were then carried out for different solar activity epochs and compared with prereversal enhancement amplitude in the F-layer vertical rise velocities, for the same epochs. Using theoretical considerations on the development of plasma bubble based on flux tube integrated properties, the observed dependence of the plasma bubble rise velocities and the F-region dynamo electric field has been analysed to estimate the average ionizations depletions in the plasma bubble. Possible causes for the lack of correlation often observed between bubble rise velocities and F-Layer velocities also are discussed. (Author) [pt

New advantages of the combined GPS and GLONASS observations for high-latitude ionospheric irregularities monitoring: case study of June 2015 geomagnetic storm

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Cherniak, Iurii; Zakharenkova, Irina

2017-05-01

Monitoring, tracking and nowcasting of the ionospheric plasma density disturbances using dual-frequency measurements of the Global Positioning System (GPS) signals are effectively carried out during several decades. Recent rapid growth and modernization of the ground-based segment gives an opportunity to establish a great database consisting of more than 6000 stations worldwide which provide GPS signals measurements with an open access. Apart of the GPS signals, at least two-third of these stations receive simultaneously signals transmitted by another Global Navigation Satellite System (GNSS)—the Russian system GLONASS. Today, GLONASS signal measurements are mainly used in navigation and geodesy only and very rarely for ionosphere research. We present the first results demonstrating advantages of using several independent but compatible GNSS systems like GPS and GLONASS for improvement of the permanent monitoring of the high-latitude ionospheric irregularities. For the first time, the high-resolution two-dimensional maps of ROTI perturbation were made using not only GPS but also GLONASS measurements. We extend the use of the ROTI maps for analyzing ionospheric irregularities distribution. We demonstrate that the meridional slices of the ROTI maps can be effectively used to study the occurrence and temporal evolution of the ionospheric irregularities. The meridional slices of the geographical sectors with a high density of the GPS and GLONASS measurements can represent spatio-temporal dynamics of the intense ionospheric plasma density irregularities with very high resolution, and they can be effectively used for detailed study of the space weather drivers on the processes of the ionospheric irregularities generation, development and their lifetimes. Using a representative database of 5800 ground-based GNSS stations located worldwide, we have investigated the occurrence of the high-latitude ionospheric plasma density irregularities during the geomagnetic storm of

Auroral lights created by high-power radiowaves in the ionospheric E region

International Nuclear Information System (INIS)

Kagan, L M

2008-01-01

Artificial auroral lights are optical emissions induced by high-power radiowaves in a manner similar to the creation of natural auroral lights due to precipitation of superthermal electrons. Here the Earth's atmosphere itself plays the role of a plasma laboratory. A high-power radio-transmitter creates superthermal electrons in situ due to radiowave interactions with the ionospheric plasma. Low-altitude (85-125 km) artificial aurora is a relatively rare phenomenon observed for the first time about 10 years ago. Analysis of available observations shows that its intensity and structure, as well as the very possibility of its generation at these altitudes, depend largely on the presence and features of so-called sporadic ionization, best known for its effect on navigation and communication. Thus, all other parameters unchanged, a 20 times increase in the height-extent of sporadic ionization clouds could under certain circumstances result in a 27-fold increase in the intensity of the low-altitude artificial aurora. Understanding the morphology and typical features of sporadic ionization clouds for a given location would allow proper planning of experimental campaigns and noticeably extend our knowledge of the atmosphere and its use for human needs. Equally important is that low-altitude artificial auroras give information about the horizontal structure and dynamics of E-region sporadic ionization, the airglow-source region, the energy of superthermal electrons and perhaps the local atmospheric temperature and water vapor content at 80-90 km

The Material Plasma Exposure eXperiment (MPEX)

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Rapp, J.; Biewer, T. M.; Bigelow, T. S.; Canik, J.; Caughman, J. B. O.; Duckworth, R. C.; Goulding, R. H.; Hillis, D. L.; Lore, J. D.; Lumsdaine, A.; McGinnis, W. D.; Meitner, S. J.; Owen, L. W.; Shaw, G. C.; Luo, G.-N.

2014-10-01

Next generation plasma generators have to be able to access the plasma conditions expected on the divertor targets in ITER and future devices. The Material Plasma Exposure eXperiment (MPEX) will address this regime with electron temperatures of 1--10 eV and electron densities of 1021--1020 m-3. The resulting heat fluxes are about 10 MW/m2. MPEX is designed to deliver those plasma conditions with a novel Radio Frequency plasma source able to produce high density plasmas and heat electron and ions separately with Electron Bernstein Wave (EBW) heating and Ion Cyclotron Resonance Heating (ICRH). Preliminary modeling has been used for pre-design studies of MPEX. MPEX will be capable to expose neutron irradiated samples. In this concept targets will be irradiated in ORNL's High Flux Isotope Reactor (HFIR) or possibly at the Spallation Neutron Source (SNS) and then subsequently (after a sufficient long cool-down period) exposed to fusion reactor relevant plasmas in MPEX. The current state of the pre-design of MPEX including the concept of handling irradiated samples will be presented. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under Contract DE-AC-05-00OR22725.

Combined radar observations of equatorial electrojet irregularities at Jicamarca

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D. L. Hysell

2007-03-01

Full Text Available Daytime equatorial electrojet plasma irregularities were investigated using five distinct radar diagnostics at Jicamarca including range-time-intensity (RTI mapping, Faraday rotation, radar imaging, oblique scattering, and multiple-frequency scattering using the new AMISR prototype UHF radar. Data suggest the existence of plasma density striations separated by 3–5 km and propagating slowly downward. The striations may be caused by neutral atmospheric turbulence, and a possible scenario for their formation is discussed. The Doppler shifts of type 1 echoes observed at VHF and UHF frequencies are compared and interpreted in light of a model of Farley Buneman waves based on kinetic ions and fluid electrons with thermal effects included. Finally, the up-down and east-west asymmetries evident in the radar observations are described and quantified.

Low plasma taurine concentration in Newfoundland dogs is associated with low plasma methionine and cyst(e)ine concentrations and low taurine synthesis.

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Backus, Robert C; Ko, Kwang Suk; Fascetti, Andrea J; Kittleson, Mark D; Macdonald, Kristin A; Maggs, David J; Berg, John R; Rogers, Quinton R

2006-10-01

Although taurine is not dietarily essential for dogs, taurine deficiency and dilated cardiomyopathy (DCM) are sporadically reported in large-breed dogs. Taurine status and husbandry were examined in 216 privately owned Newfoundlands, a giant dog breed with high incidence of idiopathic DCM (1.3-2.5%). Plasma taurine concentration was positively correlated (P ine (r = 0.37) and methionine (r = 0.35) concentrations and was similar across age, sex, neutering status, body weight, and body-condition scores. Plasma taurine concentration was low (ine, tryptophan, and alpha-amino-n-butyric acid concentrations than the other dogs (P ine and blood glutathione, lower (P < 0.01) de novo taurine synthesis (59 +/- 15 vs. 124 +/- 27 mg x kg(-0.75) x d(-1)), and greater (P < 0.05) fecal bile acid excretion (1.7 +/- 0.2 vs. 1.4 +/- 0.2 micromol/g). Newfoundlands would appear to have a higher dietary sulfur amino acid requirement than Beagles, a model breed used in nutrient requirement determinations.

Spatial relationship of 1-meter equatorial spread-F irregularities and depletions in total electron content

International Nuclear Information System (INIS)

Tsunoda, R.T.; Towle, D.M.

1979-01-01

An experiment was conducted at Kwajalein Atoll, Marshall Islands to investigate the spatial relationship of 1-m equatorial spread-F irregularities to total electron content (TEC) depletions. A high-power radar was operated (1) in a backscatter scan mode to spatially map the distribution of 1-m irregularities, and (2) in a dual-frequency, satellite-track mode to obtain the longitudinal TEC variations. We show that radar backscatter ''plumes'' found in the disturbed, nighttime equatorial ionosphere are longitudinally coincident with TEC depletions. We suggest that the TEC depletions are probably due to the presence of plasma ''bubbles'' in the equatorial F layer

Simulating Seismic Wave Propagation in Viscoelastic Media with an Irregular Free Surface

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Liu, Xiaobo; Chen, Jingyi; Zhao, Zhencong; Lan, Haiqiang; Liu, Fuping

2018-05-01

In seismic numerical simulations of wave propagation, it is very important for us to consider surface topography and attenuation, which both have large effects (e.g., wave diffractions, conversion, amplitude/phase change) on seismic imaging and inversion. An irregular free surface provides significant information for interpreting the characteristics of seismic wave propagation in areas with rugged or rapidly varying topography, and viscoelastic media are a better representation of the earth's properties than acoustic/elastic media. In this study, we develop an approach for seismic wavefield simulation in 2D viscoelastic isotropic media with an irregular free surface. Based on the boundary-conforming grid method, the 2D time-domain second-order viscoelastic isotropic equations and irregular free surface boundary conditions are transferred from a Cartesian coordinate system to a curvilinear coordinate system. Finite difference operators with second-order accuracy are applied to discretize the viscoelastic wave equations and the irregular free surface in the curvilinear coordinate system. In addition, we select the convolutional perfectly matched layer boundary condition in order to effectively suppress artificial reflections from the edges of the model. The snapshot and seismogram results from numerical tests show that our algorithm successfully simulates seismic wavefields (e.g., P-wave, Rayleigh wave and converted waves) in viscoelastic isotropic media with an irregular free surface.

Vitamin E plasma concentration in osteoporotic patients

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Hajimahmoodi M

2007-06-01

Full Text Available Background: The cause of osteoporosis is multifactorial and many dietary factors are important in the prevention of this disease. Antioxidants as free radical scavengers may influence osteoporosis by reducing the effects of oxidative stress that may be associated with bone loss. Vitamin E is an important antioxidant that protects polyunsaturated fatty acids (PUFA in cell membranes from oxidation. There are only two studies regarding vitamin E plasma levels in subjects suffering from osteoporosis. The purpose of this study was to investigate the association between plasma vitamin E levels and bone mineral density (BMD in Iranian patients. Methods: Subjects were consecutively recruited between May and September 2005 from among a total of approximately 1000 people referred for instrumental screening for osteoporosis to the Jami Clinic in Tehran. Inclusion criteria for the study group were: a femoral neck T-score of -1 or less, osteopenia, severe osteopenia and osteoporosis. A total of 137 subjects were enrolled. According to their femoral and spinal BMD scores, 54 persons were selected as a control group. The control group consisted of subjects with a femoral neck T-score and spine T-score of -1 or more. In selecting the case group, only the femoral BMD score was used. Plasma vitamin E was measured, after extraction with methanol, by HPLC with UV detection at 280 nm. Methanol, deionized water and butanol (90:4:6 was used as a mobile phase with a C8 column. The flow rate was 1.0 ml. min-1 and the acetate ester of vitamin E was used as an internal standard. Results: The results show no significant difference in plasma vitamin E between the control and case groups, however linear regression analysis does reveal a significant difference between the T-score and plasma vitamin E. Conclusion: Deceleration Femoral bone Density during osteoporosis will be Accelerated with Decrease of Vitamin E Antioxidant level.

Parathyroid mitogenic activity in plasma from patients with familial multiple endocrine neoplasia type 1

International Nuclear Information System (INIS)

Brandi, M.L.; Aurbach, G.D.; Fitzpatrick, L.A.; Quarto, R.; Spiegel, A.M.; Bliziotes, M.M.; Norton, J.A.; Doppman, J.L.; Marx, S.J.

1986-01-01

Hyperplasia of the parathyroid glands is a central feature of familial multiple endocrine neoplasia type 1. We used cultured bovine parathyroid cells to test for mitogenic activity in plasma from patients with this disorder. Normal plasma stimulated [ 3 H]thymidine incorporation, on the average, to the same extent as it was stimulated in a plasma-free control culture. This contrasted with the results of the tests with plasma from patients with familial multiple endocrine neoplasia type 1, in which parathyroid mitogenic activity increased 2400 percent over the control value (P less than 0.001). Plasma from these patients also stimulated the proliferation of bovine parathyroid cells in culture, whereas plasma from normal subjects inhibited it. Parathyroid mitogenic activity in plasma from the patients with familial multiple endocrine neoplasia type 1 was greater than that in plasma from patients with various other disorders, including sporadic primary hyperparathyroidism (with adenoma, hyperplasia, or cancer of the parathyroid), sporadic primary hypergastrinemia, sporadic pituitary tumor, familial hypocalciuric hypercalcemia, and multiple endocrine neoplasia type 2 (P less than 0.05). Parathyroid mitogenic activity in the plasma of patients with familial multiple endocrine neoplasia type 1 persisted for up to four years after total parathyroidectomy. The plasma also had far more mitogenic activity in cultures of parathyroid cells than did optimal concentrations of known growth factors or of any parathyroid secretagogue. This mitogenic activity had an apparent molecular weight of 50,000 to 55,000. We conclude that primary hyperparathyroidism in familial multiple endocrine neoplasia type 1 may have a humoral cause

On the total irregularity strength of caterpillar with each internal vertex has degree three

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Indriati, Diari; Rosyida, Isnaini; Widodo

2018-04-01

Let G be a simple, connected and undirected graph with vertex set V and edge set E. A total k-labeling f:V \\cup E\\to \\{1,2,\\ldots,k\\} is defined as totally irregular total k-labeling if the weights of any two different both vertices and edges are distinct. The weight of vertex x is defined as wt(x)=f(x)+{\\sum }xy\\in Ef(xy), while the weight of edge xy is wt(xy)=f(x)+f(xy)+f(y). A minimum k for which G has totally irregular total k-labeling is mentioned as total irregularity strength of G and denoted by ts(G). This paper contains investigation of totally irregular total k-labeling and determination of their total irregularity strengths for caterpillar graphs with each internal vertex between two stars has degree three. The results are ts({S}n,3,n)=\\lceil \\frac{2n}{2}\\rceil, ts({S}n,3,3,n)=\\lceil \\frac{2n+1}{2}\\rceil and ts({S}n,3,3,3,n)=\\lceil \\frac{2n+2}{2}\\rceil for n > 4:

Equatorial Ionospheric Irregularities Study from ROCSAT Data

Science.gov (United States)

2017-10-20

UNLIMITED: PB Public Release 13. SUPPLEMENTARY NOTES 14. ABSTRACT Ionospheric irregularity/scintillation occurrences can be caused by external driving ...Academia Sinica, Taipei, Taiwan e-mail: chliu2@gate.sinica.edu.tw phone :886-3-4227151x34757 CoPI: Shin-Yi Su Institution: National Central...University, Chung-Li, Taiwan e-mail: sysu@csrsr.ncu.edu.tw phone :886-3-4227151x57643 CoPI: Lung-Chi Tsai Institution: National Central University, Chung-Li

Application of small-size antennas for estimation of angles of arrival of HF signals scattered by ionospheric irregularities

Science.gov (United States)

Guo, Qiang; Galushko, Volodymyr G.; Zalizovski, Andriy V.; Kashcheyev, Sergiy B.; Zheng, Yu

2018-05-01

A modification of the Doppler Interferometry Technique is suggested to enable estimating angles of arrival of comparatively broadband HF signals scattered by random irregularities of the ionospheric plasma with the use of small-size weakly directional antennas. The technique is based on the measurements of cross-spectra phases of the probe radiation recorded at least in three spatially separated points. The developed algorithm has been used to investigate the angular and frequency-time characteristics of HF signals propagating at frequencies above the maximum usable one (MUF) for the direct radio path Moscow-Kharkiv. The received signal spectra show presence of three families of spatial components attributed, respectively, to scattering by plasma irregularities near the middle point of the radio path, ground backscatter signals and scattering of the sounding signals by the intense plasma turbulence associated with auroral activations. It has been shown that the regions responsible for the formation of the third family components are located well inside the auroral oval. The drift velocity and direction of the auroral ionosphere plasma have been determined. The obtained estimates are consistent with the classical conception of the ionospheric plasma convection at high latitudes and do not contradict the results of investigations of the auroral ionosphere dynamics using the SuperDARN network.

Plasma Deflection Test Setup for E-Sail Propulsion Concept

Science.gov (United States)

Andersen, Allen; Vaughn, Jason; Schneider, Todd; Wright, Ken

2016-01-01

The Electronic Sail or E-Sail is a novel propulsion concept based on momentum exchange between fast solar wind protons and the plasma sheath of long positively charged conductors comprising the E-Sail. The effective sail area increases with decreasing plasma density allowing an E-Sail craft to continue to accelerate at predicted ranges well beyond the capabilities of existing electronic or chemical propulsion spacecraft. While negatively charged conductors in plasmas have been extensively studied and flown, the interaction between plasma and a positively charged conductor is not well studied. We present a plasma deflection test method using a differential ion flux probe (DIFP). The DIFP measures the angle and energy of incident ions. The plasma sheath around a charged body can measured by comparing the angular distribution of ions with and without a positively charged test body. These test results will be used to evaluate numerical calculations of expected thrust per unit length of conductor in the solar wind plasma. This work was supported by a NASA Space Technology Research Fellowship.

Selenofuranoside Ameliorates Memory Loss in Alzheimer-Like Sporadic Dementia: AChE Activity, Oxidative Stress, and Inflammation Involvement

Directory of Open Access Journals (Sweden)

Cristiano Chiapinotto Spiazzi

2015-01-01

Full Text Available Alzheimer’s disease (AD is becoming more common due to the increase in life expectancy. This study evaluated the effect of selenofuranoside (Se in an Alzheimer-like sporadic dementia animal model. Male mice were divided into 4 groups: control, Aβ, Se, and Aβ + Se. Single administration of Aβ peptide (fragments 25–35; 3 nmol/3 μL or distilled water was administered via intracerebroventricular (i.c.v. injection. Selenofuranoside (5 mg/kg or vehicle (canola oil was administered orally 30 min before Aβ and for 7 subsequent days. Memory was tested through the Morris water maze (MWM and step-down passive-avoidance (SDPA tests. Antioxidant defenses along with reactive species (RS were assessed. Inflammatory cytokines levels and AChE activity were measured. SOD activity was inhibited in the Aβ group whereas RS were increased. AChE activity, GSH, and IL-6 levels were increased in the Aβ group. These changes were reflected in impaired cognition and memory loss, observed in both behavioral tests. Se compound was able to protect against memory loss in mice in both behavioral tests. SOD and AChE activities as well as RS and IL-6 levels were also protected by Se administration. Therefore, Se is promising for further studies.

Long wavelength irregularities in the equatorial electrojet

International Nuclear Information System (INIS)

Kudeki, E.; Farley, D.T.; Fejer, B.G.

1982-01-01

We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear theory of the electrojet instability explains this and several other observed features of these dominant primary waves

The Plasma Environment Associated With Equatorial Ionospheric Irregularities

Science.gov (United States)

Smith, Jonathon M.; Heelis, R. A.

2018-02-01

We examine the density structure of equatorial depletions referred to here as equatorial plasma bubbles (EPBs). Data recorded by the Ion Velocity Meter as part of the Coupled Ion Neutral Dynamics Investigation (CINDI) aboard the Communication/Navigation Outage Forecasting System (C/NOFS) satellite are used to study EPBs from 1600 to 0600 h local time at altitudes from 350 to 850 km. The data are taken during the 7 years from 2008 to 2014, more than one half of a magnetic solar cycle, that include solar minimum and a moderate solar maximum. Using a rolling ball algorithm, EPBs are identified by profiles in the plasma density, each having a depth measured as the percent change between the background and minimum density (ΔN/N). During solar moderate activity bubbles observed in the topside postsunset sector are more likely to have large depths compared to those observed in the topside postmidnight sector. Large bubble depths can be observed near 350 km in the bottomside F region in the postsunset period. Conversely at solar minimum the distribution of depths is similar in the postsunset and postmidnight sectors in all longitude sectors. Deep bubbles are rarely observed in the topside postsunset sector and never in the bottomside above 400 km in altitude. We suggest that these features result from the vertical drift of the plasma for these two solar activity levels. These drift conditions affect both the background density in which bubbles are embedded and the growth rate of perturbations in the bottomside where bubbles originate.

Long pulse, plasma cathode E-gun

International Nuclear Information System (INIS)

Goebel, D.M.; Schumacher, R.W.; Watkins, R.M.

1993-01-01

A unique, long-pulse E-gun has been developed for high-power tube applications. The Hollow-Cathode-Plasma (HCP) E-gun overcomes the limitations of conventional thermionic-cathode guns that have limited current density (typically ≤ 10 A/cm 2 ) or field-emission guns that offer high current density but suffer from short pulsewidth capability (typically 50 A/cm 2 ), long-pulse operation without gap closure, and also requires no cathode-heater power. The gun employs a low-pressure glow discharge inside a hollow cathode (HC) structure to provide a stable, uniform plasma surface from which a high current-density electron beam can be extracted. The plasma density is controlled by a low-voltage HC discharge pulser to produce the desired electron current density at the first grid of a multi-grid accelerator system. A dc high-voltage electron-beam supply accelerates the electrons across the gap, while the HC pulser modulates the beam current to generate arbitrary pulse waveforms. The electron accelerator utilizes a multi-aperture array that produces a large area, high perveance (>35 μpervs) beam consisting initially of many individual beamlets. The E-beam is normally operated without an applied magnetic field in the ion-focused regime, where the plasma produced by beam ionization of a background gas space-charge neutralizes the beam, and the Bennett self-pinch compresses the beamlets and increases the current density. The self-pinched beam has been observed to propagate over a meter without beam breakup or instabilities. The HCP E-gun has been operated at voltages up to 150 kV, currents up to 750 A, and pulse lengths of up to 120 μsec

The Prion Protein Preference of Sporadic Creutzfeldt-Jakob Disease Subtypes*

Science.gov (United States)

Klemm, Helen M. J.; Welton, Jeremy M.; Masters, Colin L.; Klug, Genevieve M.; Boyd, Alison; Hill, Andrew F.; Collins, Steven J.; Lawson, Victoria A.

2012-01-01

Sporadic Creutzfeldt-Jakob disease (CJD) is the most prevalent manifestation of the transmissible spongiform encephalopathies or prion diseases affecting humans. The disease encompasses a spectrum of clinical phenotypes that have been correlated with molecular subtypes that are characterized by the molecular mass of the protease-resistant fragment of the disease-related conformation of the prion protein and a polymorphism at codon 129 of the gene encoding the prion protein. A cell-free assay of prion protein misfolding was used to investigate the ability of these sporadic CJD molecular subtypes to propagate using brain-derived sources of the cellular prion protein (PrPC). This study confirmed the presence of three distinct sporadic CJD molecular subtypes with PrPC substrate requirements that reflected their codon 129 associations in vivo. However, the ability of a sporadic CJD molecular subtype to use a specific PrPC substrate was not determined solely by codon 129 as the efficiency of prion propagation was also influenced by the composition of the brain tissue from which the PrPC substrate was sourced, thus indicating that nuances in PrPC or additional factors may determine sporadic CJD subtype. The results of this study will aid in the design of diagnostic assays that can detect prion disease across the diversity of sporadic CJD subtypes. PMID:22930754

Sporadic wind wave horse-shoe patterns

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S. Yu. Annenkov

1999-01-01

Full Text Available The work considers three-dimensional crescent-shaped patterns often seen on water surface in natural basins and observed in wave tank experiments. The most common of these 'horse-shoe-like' patterns appear to be sporadic, i.e., emerging and disappearing spontaneously even under steady wind conditions. The paper suggests a qualitative model of these structures aimed at explaining their sporadic nature, physical mechanisms of their selection and their specific asymmetric form. First, the phenomenon of sporadic horse-shoe patterns is studied numerically using the novel algorithm of water waves simulation recently developed by the authors (Annenkov and Shrira, 1999. The simulations show that a steep gravity wave embedded into widespectrum primordial noise and subjected to small nonconservative effects typically follows the simple evolution scenario: most of the time the system can be considered as consisting of a basic wave and a single pair of oblique satellites, although the choice of this pair tends to be different at different instants. Despite the effective low-dimensionality of the multimodal system dynamics at relatively sho ' rt time spans, the role of small satellites is important: in particular, they enlarge the maxima of the developed satellites. The presence of Benjamin-Feir satellites appears to be of no qualitative importance at the timescales under consideration. The selection mechanism has been linked to the quartic resonant interactions among the oblique satellites lying in the domain of five-wave (McLean's class II instability of the basic wave: the satellites tend to push each other out of the resonance zone due to the frequency shifts caused by the quartic interactions. Since the instability domain is narrow (of order of cube of the basic wave steepness, eventually in a generic situation only a single pair survives and attains considerable amplitude. The specific front asymmetry is found to result from the interplay of quartic

Capture of irregular satellites at Jupiter

International Nuclear Information System (INIS)

Nesvorný, David; Vokrouhlický, David; Deienno, Rogerio

2014-01-01

The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early solar system instability when encounters between the outer planets occurred. Nesvorný et al. already showed that the irregular satellites of Saturn, Uranus, and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encounters with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary disk is found to be (1.3-3.6) × 10 –8 . This is roughly enough to explain the observed population of jovian irregular moons. We also confirm Nesvorný et al.'s results for the irregular satellites of Saturn, Uranus, and Neptune.

Plasma and skin vitamin E concentrations in canine atopic dermatitis.

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Plevnik Kapun, Alja; Salobir, Janez; Levart, Alenka; Tavčar Kalcher, Gabrijela; Nemec Svete, Alenka; Kotnik, Tina

2013-01-01

Altered homeostasis of vitamin E has been demonstrated in human atopic dermatitis. Data on plasma and skin vitamin E concentrations in canine atopic dermatitis (CAD) are not available. To determine vitamin E concentrations in plasma and skin of atopic dogs. Vitamin E concentrations in plasma and full-thickness skin biopsies of 15 atopic dogs were related to CAD extent and severity index (CADESI-03) scores and compared to the equivalent concentrations in 17 healthy dogs. Statistically significant differences of measured parameters between the two groups were determined by the nonparametric Mann Whitney U test and correlations between CADESI-03 scores and vitamin E concentrations were evaluated by the Spearman rank test. A value of P vitamin E were significantly lower in atopic dogs than in healthy dogs, with median values of 29.8 and 52.9 μmol/L, respectively. Skin vitamin E values did not differ significantly between patients and healthy controls. The median concentration of skin vitamin E in atopic dogs was higher than that in healthy dogs. No significant correlations were found between CADESI-03 score and plasma vitamin E or skin vitamin E concentrations. Significantly lower plasma vitamin E concentrations in atopic dogs than in healthy controls indicate altered homeostasis of vitamin E in CAD. Further investigation into vitamin E supplementation in CAD is warranted.

Irregular Migrants and the Law

OpenAIRE

Kassim, Azizah; Mat Zin, Ragayah Hj.

2013-01-01

This paper examines Malaysia`s policy on irregular migrants and its implementation, and discusses its impact. A survey and interview covering 404 respondents was conducted between July 2010 and June 2011 to ascertain the real situations surrounding irregular migrants in Malaysia, which is one of the major host countries of international migrants from developing nations. The policy on foreign workers was formulated in the mid-1980s to deal with the large number of irregular migrants and their ...

Serum uric acid and lipid profiles in sporadic Creutzfeldt-Jakob disease.

Science.gov (United States)

Chen, Shuai; He, Shuang; Shang, Jun-Kui; Ma, Ming-Ming; Xu, Chang-Shui; Shi, Xiao-Hong; Zhang, Jie-Wen

2016-02-01

Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive, and fatal neurodegenerative disease affecting the central nervous system. Brain lipid homeostasis and oxidative stress seem to play an important role in the disease pathogenesis. But little was known whether serum lipids and uric acid (a natural antioxidant) levels changed in patients with prion disease. Here we retrospectively reviewed and compared the serum lipids and uric acid levels of 19 probable sporadic CJD patients and 26 healthy control subjects. We found that the serum uric acid levels in sporadic CJD patients were significantly lower than that in controls (P=0.01). Serum triglycerides, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and apolipoprotein A1 (ApoA1) were similar in sporadic CJD patients and controls. However, LDL/HDL ratio was lower in sporadic CJD patients (P=0.003). The low serum uric acid and LDL/HDL ratio levels in sporadic CJD indicate that dysfunction in the lipid homeostasis and oxidative stress is associated with sporadic prion disease. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Germline Mutations in Cancer Predisposition Genes are Frequent in Sporadic Sarcomas

OpenAIRE

Chan, Sock Hoai; Lim, Weng Khong; Ishak, Nur Diana Binte; Li, Shao-Tzu; Goh, Wei Lin; Tan, Gek San; Lim, Kiat Hon; Teo, Melissa; Young, Cedric Ng Chuan; Malik, Simeen; Tan, Mann Hong; Teh, Jonathan Yi Hui; Chin, Francis Kuok Choon; Kesavan, Sittampalam; Selvarajan, Sathiyamoorthy

2017-01-01

Associations of sarcoma with inherited cancer syndromes implicate genetic predisposition in sarcoma development. However, due to the apparently sporadic nature of sarcomas, little attention has been paid to the role genetic susceptibility in sporadic sarcoma. To address this, we performed targeted-genomic sequencing to investigate the prevalence of germline mutations in known cancer-associated genes within an Asian cohort of sporadic sarcoma patients younger than 50 years old. We observed 13....

Regularities And Irregularities Of The Stark Parameters For Single Ionized Noble Gases

Science.gov (United States)

Peláez, R. J.; Djurovic, S.; Cirišan, M.; Aparicio, J. A.; Mar S.

2010-07-01

Spectroscopy of ionized noble gases has a great importance for the laboratory and astrophysical plasmas. Generally, spectra of inert gases are important for many physics areas, for example laser physics, fusion diagnostics, photoelectron spectroscopy, collision physics, astrophysics etc. Stark halfwidths as well as shifts of spectral lines are usually employed for plasma diagnostic purposes. For example atomic data of argon krypton and xenon will be useful for the spectral diagnostic of ITER. In addition, the software used for stellar atmosphere simulation like TMAP, and SMART require a large amount of atomic and spectroscopic data. Availability of these parameters will be useful for a further development of stellar atmosphere and evolution models. Stark parameters data of spectral lines can also be useful for verification of theoretical calculations and investigation of regularities and systematic trends of these parameters within a multiplet, supermultiplet or transition array. In the last years, different trends and regularities of Stark parameters (halwidths and shifts of spectral lines) have been analyzed. The conditions related with atomic structure of the element as well as plasma conditions are responsible for regular or irregular behaviors of the Stark parameters. The absence of very close perturbing levels makes Ne II as a good candidate for analysis of the regularities. Other two considered elements Kr II and Xe II with complex spectra present strong perturbations and in some cases an irregularities in Stark parameters appear. In this work we analyze the influence of the perturbations to Stark parameters within the multiplets.

Impaired proteasome function in sporadic amyotrophic lateral sclerosis.

Science.gov (United States)

Kabashi, Edor; Agar, Jeffrey N; Strong, Michael J; Durham, Heather D

2012-06-01

Abstract The ubiquitin-proteasome system, important for maintaining protein quality control, is compromised in experimental models of familial ALS. The objective of this study was to determine if proteasome function is impaired in sporadic ALS. Proteasomal activities and subunit composition were evaluated in homogenates of spinal cord samples obtained at autopsy from sporadic ALS and non-neurological control cases, compared to cerebellum as a clinically spared tissue. The level of 20S α structural proteasome subunits was assessed in motor neurons by immunohistochemistry. Catalysis of peptide substrates of the three major proteasomal activities was substantially reduced in ALS thoracic spinal cord, but not in cerebellum, accompanied by alterations in the constitutive proteasome machinery. Chymotrypsin-like activity was decreased to 60% and 65% of control in ventral and dorsal spinal cord, respectively, concomitant with reduction in the β5 subunit with this catalytic activity. Caspase- and trypsin-like activities were reduced to a similar extent (46% - 68% of control). Proteasome levels, although generally maintained, appeared reduced specifically in motor neurons by immunolabelling. In conclusion, there are commonalities of findings in sporadic ALS patients and presymptomatic SOD1-G93A transgenic mice and these implicate inadequate proteasome function in the pathogenesis of both familial and sporadic ALS.

Dietary factors and microsatellite instability in sporadic colon carcinomas

NARCIS (Netherlands)

Diergaarde, B.; Braam, H.; Muijen, van G.N.P.; Ligtenberg, M.J.L.; Kok, F.J.; Kampman, E.

2003-01-01

Microsatellite instability (MSI) occurs in 10-20% of the sporadic colon carcinomas and appears to be primarily due to alterations in hMLH1 and hMSH2. Little is known about the role of diet in MSI-related colon carcinogenesis. We used data from a Dutch population-based case-control study on sporadic

Dietary factors and microsatellite instability in sporadic colon carcinomas.

NARCIS (Netherlands)

Diergaarde, B.; Braam, H.; Muijen, G.N.P. van; Ligtenberg, M.J.L.; Kok, F.J.; Kampman, E.

2003-01-01

Microsatellite instability (MSI) occurs in 10-20% of the sporadic colon carcinomas and appears to be primarily due to alterations in hMLH1 and hMSH2. Little is known about the role of diet in MSI-related colon carcinogenesis. We used data from a Dutch population-based case-control study on sporadic

Visual art therapy in sporadic Creutzfeldt-Jakob disease: a case study.

Science.gov (United States)

Shrestha, Rajeet; Trauger-Querry, Barbara; Loughrin, Athena; Appleby, Brian S

2016-01-01

This paper describes the diagnostic and treatment utility of visual art therapy in a case of sporadic Creutzfeldt-Jakob disease. Visual art therapy was compared longitudinally with clinical and neuroimaging data over five-month period in an autopsy-confirmed case of sporadic Creutzfeldt-Jakob disease of MM2-cortical subtype. Art therapy sessions and content were useful in ascertaining neuropsychiatric symptoms during the course of her illness. Art therapy offered a unique emotional and cognitive outlet as illness progressed. Patients and families affected by sporadic Creutzfeldt-Jakob disease may benefit from art therapy despite the rapidly progressive nature of the illness. Art therapy can also be useful for assessment of patients with sporadic Creutzfeldt-Jakob disease by healthcare professionals.

Case-Control Studies of Sporadic Enteric Infections: A Review and Discussion of Studies Conducted Internationally from 1990 to 2009

Science.gov (United States)

Fullerton, Kathleen E.; Scallan, Elaine; Kirk, Martyn D.; Mahon, Barbara E.; Angulo, Frederick J.; de Valk, Henriette; van Pelt, Wilfrid; Gauci, Charmaine; Hauri, Anja M.; Majowicz, Shannon; O’Brien, Sarah J.

2015-01-01

Epidemiologists have used case-control studies to investigate enteric disease outbreaks for many decades. Increasingly, case-control studies are also used to investigate risk factors for sporadic (not outbreak-associated) disease. While the same basic approach is used, there are important differences between outbreak and sporadic disease settings that need to be considered in the design and implementation of the case-control study for sporadic disease. Through the International Collaboration on Enteric Disease “Burden of Illness” Studies (the International Collaboration), we reviewed 79 case-control studies of sporadic enteric infections caused by nine pathogens that were conducted in 22 countries and published from 1990 through to 2009. We highlight important methodological and study design issues (including case definition, control selection, and exposure assessment) and discuss how approaches to the study of sporadic enteric disease have changed over the last 20 years (e.g., making use of more sensitive case definitions, databases of controls, and computer-assisted interviewing). As our understanding of sporadic enteric infections grows, methods and topics for case-control studies are expected to continue to evolve; for example, advances in understanding of the role of immunity can be used to improve control selection, the apparent protective effects of certain foods can be further explored, and case-control studies can be used to provide population-based measures of the burden of disease. PMID:22443481

Bottomside sinusoidal irregularities in the equatorial F region. II - Cross-correlation and spectral analysis

Science.gov (United States)

Cragin, B. L.; Hanson, W. B.; Mcclure, J. P.; Valladares, C. E.

1985-01-01

Equatorial bottomside sinusoidal (BSS) irregularities have been studied by applying techniques of cross-correlation and spectral analysis to the Atmosphere Explorer data set. The phase of the cross-correlations of the plasma number density is discussed and the two drift velocity components observed using the retarding potential analyzer and ion drift meter on the satellite are discussed. Morphology is addressed, presenting the geographical distributions of the occurrence of BSS events for the equinoxes and solstices. Physical processes including the ion Larmor flux, interhemispheric plasma flows, and variations in the lower F region Pedersen conductivity are invoked to explain the findings.

Collective scattering of electromagnetic waves and cross-B plasma diffusion

International Nuclear Information System (INIS)

Gresillon, D.; Cabrit, B.; Truc, A.

1992-01-01

Magnetized plasmas occuring in nature as well as in fusion laboratories are oftenly irregularly shaked by magnetic field fluctuations. The so-called ''coherent scattering'' of electromagnetic wave from nonuniform, irregularly moving plasmas is investigated in the case where the scattering wavelength is large compared to the Debye length, but of the order of the irregularities correlation length. The scattered signal frequency spectrum is shown to be a transform of the plasma motion statistical characteristics. When the scattering wavelength is larger than the plasma motion correlation length, the frequency spectrum is shown to be of a lorentzian shape, with a frequency width that provides a direct measurement of the cross-B particle diffusion coefficient. This is illustrated by two series of recently obtained experimental results: radar coherent backscattering observations of the auroral plasma, and far infrared scattering from tokamak fusion plasma. Radar coherent backscattering shows the transition from Gauss to Lorentz scattered frequency spectra. In infrared Laser coherent scattering experiments from the Tore-Supra tokamak, a particular frequency line is observed to present a Lorentzian shape, that directly provides an electron cross-field diffusion coefficient. This diffusion coefficient agrees with the electron heat conductivity coefficient that is obtained from the observation of temperature profiles and energy balance. (Author)

Zonal drifts of ionospheric irregularities at temperate latitude in the Indian region

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S. Kumar

1995-07-01

Full Text Available The systematic time differences observed in the onset of postsunset VHF scintillations recorded simultaneously at Ujjain (Geogr. lat. 23.2°N, Geogr. long. 75.6°E and Bhopal (Geogr. lat. 23.2°N, Geogr. long. 77.6°E, situated at the peak of the anomaly crest in the Indian region, have been analysed to determine the zonal drifts of scintillation-producing irregularities. The method is based on the assumption that the horizontal movement of irregularities does not change while crossing the F-region cross-over points of these stations. The calculated velocities of irregularities indicate an eastward drift decreasing from about 180 m s–1 to 55 m s–1 during the course of night. In the premidnight period, the drifts are reduced under the magnetically disturbed conditions. The average east-west extension of irregularites is found to be in the range of 200–500 km.

Plasma folic acid cutoff value, derived from its relationship with homocyst(e)ine

NARCIS (Netherlands)

Brouwer, D A; Welten, H T; Reijngoud, D J; van Doormaal, J J; Muskiet, F A

We established the cutoff value for plasma folic acid, using plasma homocyst(e)ine as the functional marker. To do this, we investigated the relationship of the plasma folic acid of 103 apparently healthy adults with their fasting plasma homocyst(e)ine and with their plasma homocyst(e)ine 6 h after

Characteristics of the plasma injected into D.E.C.A. 2; Caracteristiques du plasma injecte dans D.E.C.A. 2

Energy Technology Data Exchange (ETDEWEB)

Lecoustey, P; Luc, H; Tachon, J; Veron, D [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1963-07-01

Deuterium plasma is injected from an electrode-less plasma gun along the lines of force of a static magnetic field. This field is constant over length of 1 m; it increases thereafter in a 10 to 1 ratio over a 4 meter length up to the chamber where the measurements are carried out. Density measurements are performed using Faraday cups and an 8.6 mm microwave interferometer. For instance in a 1600 G magnetic field a 0.5 x 10{sup 13} deutons/cm{sup 3} density arises for a plasma with velocity 3 x 10{sup 7} cm/s. The transverse energy is first determined from the diamagnetic signal amplitude of magnetic loops. The main results are obtained from the study of plasma transmitted through a magnetic barrier by means of measurements made with a Faraday cup, magnetic loops and thermocouples. The results given by these different methods are in good agreement and allow to define for the whole of the plasma flow a mean < {theta} > value for the ions pitch angle. In a 1600 G, < {theta} > equal 32 degrees; i.e. mean transverse energy of 360 eV for a plasma with a 030 eV longitudinal energy (a velocity equal to 3 x 10{sup 7} cm/s). The high value of the transverse energy might be attributed to a pre-compression in the field gradient. Preliminary measurements seem to indicate the possibility of trapping the plasma between two magnetic barriers. (authors) [French] Un plasma de deuterium est injecte par un canon a induction parallelement aux lignes de force d'un champ magnetique statique, constant sur une longueur de 1 m et ensuite croissant dans un rapport 10 a 1 sur une longueur de 4 m, jusque dans la chambre ou sont effectuees les mesures. La densite est determinee par des mesures d'interferometrie hertzienne et au moyen de cylindres de Faraday. Par exemple dans un champ de 1600 G on trouve une densite de 0,5 x 10{sup 13} deutons/cm{sup 3} pour un plasma anime d'une vitesse de 3 x 10{sup 7} cm/s. Une premiere determination de l'energie transversale est faite a partir des signaux

On H-irregularity strengths of G-amalgamation of graphs

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Faraha Ashraf

2017-10-01

Full Text Available A simple graph G=(V(G,E(G admits an H-covering if every edge in E(G belongs at least to one subgraph of G isomorphic to a given graph H. Then the graph G admitting H-covering admits an H-irregular total k-labeling f: V(G U E(G \\to {1, 2, ..., k} if for every two different subgraphs H' and H'' isomorphic to H there is $wt_{f}(H' \

Legionnaires’ Disease: Clinicoradiological Comparison of Sporadic Versus Outbreak Cases

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Hafiz Rizwan Talib Hashmi

2017-06-01

Full Text Available Background: In 2015, New York City experienced the worst outbreak of Legionnaires’ disease in the history of the city. We compare patients seen during the 2015 outbreak with sporadic cases of Legionella during the past 5 years. Methods: We conducted a retrospective chart review of 90 patients with Legionnaires’ disease, including sporadic cases of Legionella infection admitted from 2010 to 2015 (n = 55 and cases admitted during the 2015 outbreak (n = 35. Results: We saw no significant differences between the 2 groups regarding demographics, smoking habits, alcohol intake, underlying medical disease, or residence type. Univariate and multivariate analyses showed that patients with sporadic case of Legionella had a longer stay in the hospital and intensive care unit as well as an increased stay in mechanical ventilation. Short-term mortality, discharge disposition, and most clinical parameters did not differ significantly between the 2 groups. Conclusions: We found no specific clinicoradiological characteristics that could differentiate sporadic from epidemic cases of Legionella . Early recognition and high suspicion for Legionnaires’ disease are critical to provide appropriate treatment. Cluster of cases should increase suspicion for an outbreak.

Magnetic storm effect on the occurrence of ionospheric irregularities at an equatorial station in the African sector

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Olushola Abel Oladipo

2014-01-01

Full Text Available Large-scale ionospheric irregularities usually measured by GPS TEC fluctuation indices are regular occurrence at the equatorial region shortly after sunset around solar maximum. Magnetic storm can trigger or inhibit the generation of these irregularities depending on the local time the main phase of a particular storm occurs. We studied the effect of nine (9 distinct storms on the occurrence of ionospheric irregularities at Fraceville in Gabon (Lat = −1.63˚, Long = 13.55˚, dip lat. = −15.94˚, an equatorial station in the African sector. These storms occurred between November 2001 and September 2002. We used TEC fluctuation indices (i.e. ROTI and ROTIAVE estimated from 30 s interval Rinex data and also we used the storm indices (i.e. Dst, dDst/dt, and IMF BZ to predict the likely effect of each storm on the irregularities occurrence at this station. The results obtained showed that most of the storms studied inhibited ionospheric irregularities. Only one out of all the storms studied (i.e. September 4, 2002 storms with the main phase on the night of September 7-8 triggered post-midnight ionospheric irregularities. There are two of the storms during which ionospheric irregularities were observed. However, these may not be solely attributed to the storms event because the level of irregularities observed during these two storms is comparable to that observed during previous days before the storms. For this station and for the storms investigated, it seems like a little modification to the use of Aarons categories in terms of the local time the maximum negative Dst occurs could lead to a better prediction. However, it would require investigating many storms during different level of solar activities and at different latitudes to generalize this modification.

Pleural irregularities and mediastinal pleural involvement in early stages of malignant pleural mesothelioma and benign asbestos pleural effusion.

Science.gov (United States)

Kato, Katsuya; Gemba, Kenichi; Fujimoto, Nobukazu; Aoe, Keisuke; Takeshima, Yukio; Inai, Kouki; Kishimoto, Takumi

2016-09-01

To elucidate differences in the level and localization of pleural irregularities in early malignant pleural mesothelioma (eMPM) and benign asbestos pleural effusion (BAPE) using CT. Retrospective assessment of CT findings of consecutive patients with BAPE at a single centre and patients with eMPM reported in Japanese vital statistics. Thirty-six patients with confirmed diagnoses of BAPE and sixty-six patients with confirmed diagnoses of eMPM (mesothelioma stages T1 or T2) were included. Informed consent, CT scans, and clinical and pathologic details were obtained for all patients and were reviewed by one radiologist, two pathologists, and two pulmonologists. Asbestosis, pleural plaque, rounded atelectasis, and diffuse pleural thickening were assessed in all patients. Prevalence of asbestosis, pleural plaque, rounded atelectasis, and diffuse pleural thickening was significantly higher in the BAPE group. Low-level irregularity was more common in the BAPE group (ppleural irregularity was not observed in any patients in the BAPE group, although 55% of patients in the eMPM group showed interlobar pleural irregularity. Mediastinal pleural involvement was observed in 74% of patients in the eMPM group and had a positive predictive value of 89%. This study demonstrates that the level and localization of plural irregularities significantly differed between patients with BAPE and eMPM. Large-scale prospective studies are needed to fully establish the diagnostic utility of such differences. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

F region electron density irregularity spectra near Auroral acceleration and shear regions

International Nuclear Information System (INIS)

Basu, S.; Basu, S.; MacKenzie, E.; Coley, W.R.; Hanson, W.B.; Lin, C.S.

1984-01-01

Spectral characteristics of auroral F region irregularities were studied by the use of high-resolution (approx.35 m) density measurements made by the retarding potential analyzer (RPA) on board the Atmosphere Explorer D (AE-D) satellite during two orbits when the satellite was traversing the high-latitude ionosphere in the evening sector. Coordinated DMSP passes provided synoptic coverage of auroral activity. The auroral energy input was estimated by intergrating the low-energy electron (LEE) data on AE-D. It was found that the one-dimensional in situ spectral index (p 1 ) of the irregularities at scale lengths of 1 values of approx.-3. This is interpreted as resulting from the effects of E region conductivity on the F region irregularity structure. The regions in between the precipitation structures, where presumably the E region conductivity was small, were generally associated with large shears in the horizontal E-W drifts and large velocities, as measured by the ion drift meter on board AE-D. The maximum drifts measured were approx.2 km s -1 , corresponding to an electric field of 100 mV m -1 . The large-velocity regions were also associated with substantial ion heating and electron density depletions. The largest shear magnitudes observed were approx.80 m s -1 km -1 , and the shear gradient scale lengths were approx.10 km, which was approximately the resolution of the ion drift meter data set used. The spectral characteristics of irregularities in the large, variable flow regions were very different, with p 1 being approx.-1

Strategic Analysis of Irregular Warfare

Science.gov (United States)

2010-03-01

the same mathematical equations used by Lanchester .10 Irregular Warfare Theory and Doctrine It is time to develop new analytical methods and models...basis on which to build, similar to what Lanchester provided almost 100 years ago. Figure 9 portrays both Lanchester’s approach and an irregular 17

The nature and source of irregular discharges to stormwater entering Sydney estuary, Australia

International Nuclear Information System (INIS)

Beck, H.J.; Birch, G.F.

2014-01-01

Irregular discharges of polluted stormwater into drainage systems during base flow (no rainfall) result in acute ecological impacts within fluvial and estuarine environments. In this study, metal and TSS concentrations were significantly more variable during business hours of weekdays (i.e. high-business activity) than weekends/public holidays (i.e. low-business activity) within three highly-urbanised catchments of Sydney estuary (Australia), as determined by analysing multivariate dispersion (PERMDISP). Concentrations of TSS and all metals analysed (Al, Ca, Cu, Fe, Mg, Pb and Zn) were also significantly greater during high- than low-business periods within at least one of the three catchments. In no case were concentrations significantly higher during low- than high-business periods. This pattern of contamination supports the hypothesis that commercial and industrial sources are major contributors of irregular discharges of contamination to Sydney estuary. Irregular discharges and consequential ecological impacts may be effectively reduced in this environment by focussing management efforts on these activities. - Highlights: • Irregular discharges of pollution have acute impacts on aquatic ecosystems. • These discharges were thought to be made during low activity periods, such as night. • Pollution was more concentrated and erratic during high- than low-business periods. • Timing of pollution suggests commercial and industrial activities are major sources. • Discharges effectively reduced by managing commercial and industrial activities. - Previously unreported irregular, illegal discharges of polluted stormwater released to estuaries result in acute ecological impacts and are potentially related to commercial/industrial activities

Irregular Migration in Jordan, 1995-2007

OpenAIRE

AROURI, Fathi A.

2008-01-01

Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) This paper tackles the question of irregular migration in Jordan through its four main aspects. The first concerns irregular labour migrants and has been approached by using figures showing the socio-economic profile of non Jordanians working in Jordan and, additionally, unemployment in Jordan. This is done by assuming close similarities between legal and irregular labour migrants. The second is an attemp...

Syntaxin-4 is essential for IgE secretion by plasma cells

Energy Technology Data Exchange (ETDEWEB)

Rahman, Arman; DeCourcey, Joseph; Larbi, Nadia Ben [Immunomodulation Group, School of Biotechnology, Dublin City University (Ireland); Loughran, Sinéad T.; Walls, Dermot [School of Biotechnology and National Centre for Sensor Research, Dublin City University (Ireland); Loscher, Christine E., E-mail: christine.loscher@dcu.ie [Immunomodulation Group, School of Biotechnology, Dublin City University (Ireland)

2013-10-11

Highlights: •Knock-down of syntaxin-4 in U266 plasma cells resulted in reduction of IgE secretion. •Knock-down of syntaxin-4 also leads to the accumulation of IgE in the cell. •Immuno-fluorescence staining shows co-localisation of IgE and syntaxin-4 in U266 cells. •Findings suggest a critical requirement for syntaxin-4 in IgE secretion from plasma cells. -- Abstract: The humoral immune system provides a crucial first defense against the invasion of microbial pathogens via the secretion of antigen specific immunoglobulins (Ig). The secretion of Ig is carried out by terminally differentiated B-lymphocytes called plasma cells. Despite the key role of plasma cells in the immune response, the mechanisms by which they constitutively traffic large volumes of Ig out of the cell is poorly understood. The involvement of Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins in the regulation of protein trafficking from cells has been well documented. Syntaxin-4, a member of the Qa SNARE syntaxin family has been implicated in fusion events at the plasma membrane in a number of cells in the immune system. In this work we show that knock-down of syntaxin-4 in the multiple myeloma U266 human plasma cell line results in a loss of IgE secretion and accumulation of IgE within the cells. Furthermore, we show that IgE co-localises with syntaxin-4 in U266 plasma cells suggesting direct involvement in secretion at the plasma membrane. This study demonstrates that syntaxin-4 plays a critical role in the secretion of IgE from plasma cells and sheds some light on the mechanisms by which these cells constitutively traffic vesicles to the surface for secretion. An understanding of this machinery may be beneficial in identifying potential therapeutic targets in multiple myeloma and autoimmune disease where over-production of Ig leads to severe pathology in patients.

Syntaxin-4 is essential for IgE secretion by plasma cells

International Nuclear Information System (INIS)

Rahman, Arman; DeCourcey, Joseph; Larbi, Nadia Ben; Loughran, Sinéad T.; Walls, Dermot; Loscher, Christine E.

2013-01-01

Highlights: •Knock-down of syntaxin-4 in U266 plasma cells resulted in reduction of IgE secretion. •Knock-down of syntaxin-4 also leads to the accumulation of IgE in the cell. •Immuno-fluorescence staining shows co-localisation of IgE and syntaxin-4 in U266 cells. •Findings suggest a critical requirement for syntaxin-4 in IgE secretion from plasma cells. -- Abstract: The humoral immune system provides a crucial first defense against the invasion of microbial pathogens via the secretion of antigen specific immunoglobulins (Ig). The secretion of Ig is carried out by terminally differentiated B-lymphocytes called plasma cells. Despite the key role of plasma cells in the immune response, the mechanisms by which they constitutively traffic large volumes of Ig out of the cell is poorly understood. The involvement of Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins in the regulation of protein trafficking from cells has been well documented. Syntaxin-4, a member of the Qa SNARE syntaxin family has been implicated in fusion events at the plasma membrane in a number of cells in the immune system. In this work we show that knock-down of syntaxin-4 in the multiple myeloma U266 human plasma cell line results in a loss of IgE secretion and accumulation of IgE within the cells. Furthermore, we show that IgE co-localises with syntaxin-4 in U266 plasma cells suggesting direct involvement in secretion at the plasma membrane. This study demonstrates that syntaxin-4 plays a critical role in the secretion of IgE from plasma cells and sheds some light on the mechanisms by which these cells constitutively traffic vesicles to the surface for secretion. An understanding of this machinery may be beneficial in identifying potential therapeutic targets in multiple myeloma and autoimmune disease where over-production of Ig leads to severe pathology in patients

Numerical simulation of mid-latitude ionospheric E-region based on SEEK and SEEK-2 observations

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T. Yokoyama

2005-10-01

Full Text Available Observational campaigns of the mid-latitude ionospheric E-region with sounding rockets and ground-based instruments were conducted in 1996 (SEEK and 2002 (SEEK-2. Both of them were successfully conducted to bring important findings about the mid-latitude E-region and quasi-periodic (QP VHF radar echoes. The observational results in the SEEK and the SEEK-2 are compared with numerical simulations and discussed in this paper. While sporadic-E (Es-layers are actually formed by the observed neutral wind, it is difficult for the constant wind shear to produce the sharp Es-layer gradient. However, once they are formed in the lower E-region, they cannot easily be dissipated by the simple diffusive motion. The polarization electric field, calculated under the condition at the rocket launch time, shows similar amplitude and structure to the measurement around the Es-layer altitude. The structure of the plasma density and the electric field above the Es-layer observed in the SEEK-2 showed a wave-like pattern up to an altitude of 150 km. Considering a mapping of the polarization electric field generated within the Es-layers, gravity waves are the possible source of the wave-like structure of the measured electric fields and sub-peaks of the electron density above the main Es-layers. Fluctuation of the measured magnetic field is reproduced by Hall or field-aligned current driven by the polarization electric field. The current theoretical models for QP echoes and the polarization electric field are basically verified by the discussion in this paper. Keywords. Ionospheric irregularities – Mid-latitude ionosphere – Numerical simulation studies

Application of Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS) for the investigation of midlatitude ionospheric irregularities

Science.gov (United States)

Wang, Jin; Zhou, Xiaoming; Qiao, Lei; Gong, Wanlin

2018-03-01

An upgrade of Wuhan Ionospheric Backscattering Sounding System (WIOBSS) was developed in 2015. Based on the Universal Serial Bus (USB), and a high performance FPGA, the newly designed WIOBSS has a completely digital structure, which makes it portable and flexible. Two identical WIOBSSs, which were situated at Mile (24.31°N, 103.39°E) and Puer (22.74°N, 101.05°E) respectively, were used to investigate the ionospheric irregularities. The comparisons of group distance, Doppler shift and width between Mile-Puer and Puer-Mile VHF ionospheric propagation paths indicate that the reciprocity of the irregularities is satisfied at midlatitude region. The WIOBSS is robust in the detection of ionospheric irregularities.

Fitting Irregular Shape Figures into Irregular Shape Areas for the Nesting Problem in the Leather Industry

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Guevara-Palma Luis

2015-01-01

Full Text Available The nesting problem of irregular shapes within irregular areas has been studied from several approaches due to their application in different industries. The particular case of cutting leather involves several restrictions that add complexity to this problem, it is necessary to generate products that comply with the quality required by customers This paper presents a methodology for the accommodation of irregular shapes in an irregular area (leather considering the constraints set by the footwear industry, and the results of this methodology when applied by a computer system. The scope of the system is to develop a working prototype that operates under the guidelines of a commercial production line of a sponsor company. Preliminary results got a reduction of 70% of processing time and improvement of 5% to 7% of the area usage when compared with manual accommodation.

Experimental demonstration of vector E x vector B plasma divertor

International Nuclear Information System (INIS)

Strait, E.J.; Kerst, D.W.; Sprott, J.C.

1977-01-01

The vector E x vector B drift due to an applied radial electric field in a tokamak with poloidal divertor can speed the flow of plasma out of the scrape-off region, and provide a means of externally controlling the flow rate and thus the width of the density fall-off. An experiment in the Wisconsin levitated toroidal octupole, using vector E x vector B drifts alone, demonstrates divertor-like behavior, including 70% reduction of plasma density near the wall and 40% reduction of plasma flux to the wall, with no adverse effects on confinement of the main plasma

Effects of surface irregularities on intensity data from laser scanning: an experimental approach.

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G. Teza

2008-06-01

Full Text Available The results of an experiment carried out with the aim to investigate the role of surface irregularities on the intensity data provided by a terrestrial laser scanner (TLS survey are reported here. Depending on surface roughness, the interaction between an electromagnetic wave and microscopic irregularities leads to a Lambertian-like diffusive light reflection, allowing the TLS to receive the backscattered component of the signal. The described experiment consists in a series of TLS-based acquisitions of a rotating artificial target specifically conceived in order to highlight the effects on the intensity data due to surface irregularity. This target is articulated in a flat plate and in an irregular surface, whose macro-roughness has a characteristic length with the same order of the spot size. Results point out the different behavior of the plates. The intensity of the signal backscattered by the planar element decreases if the incidence angle increases, whereas the intensity of the signal backscattered by the irregular surface is almost constant if the incidence angle varies. Since the typical surfaces acquired in a geological/geophysical survey are generally irregular, these results imply that the intensity data can be easily used in order to evaluate the reflectance of the material at the considered wavelength, e.g. for pattern recognition purposes.

An Experiment to Study Sporadic Atom Layers in the Earth's Mesosphere and Lower Thermosphere (SAL)

Science.gov (United States)

Kelley, Michael C.

1999-01-01

The Sudden Atom Layer (SAL) Rocket was successfully launched in February 1998. All instruments worked well except those supplied by NASA Goddard Space Flight Center. (A dummy weight was launched for the neutral mass spectrometer and the ion version died shortly after lift-off.) A paper has already been published in GRL concerning the dust layer detected by an on board instrument and compared to ground-based observations made at the Arecibo Observatory by Cornell graduate student S. Collins (lidar) and Q. Zhou (radar). Collins presented a comparison of the sodium lidar data and onboard observations with a theoretical model by Plane and Cox at the Fan AGU Meeting. In addition Gelinas and Kelley presented a review paper dealing with the entire SAL instrument complement at the same meeting. An unexpected new explanation for the outer scale of E region plasma irregularities has come out of the data set. We anticipate at least a total of four papers will be published within a year of launch.

Kilometer-Spaced GNSS Array for Ionospheric Irregularity Monitoring

Science.gov (United States)

Su, Yang

This dissertation presents automated, systematic data collection, processing, and analysis methods for studying the spatial-temporal properties of Global Navigation Satellite Systems (GNSS) scintillations produced by ionospheric irregularities at high latitudes using a closely spaced multi-receiver array deployed in the northern auroral zone. The main contributions include 1) automated scintillation monitoring, 2) estimation of drift and anisotropy of the irregularities, 3) error analysis of the drift estimates, and 4) multi-instrument study of the ionosphere. A radio wave propagating through the ionosphere, consisting of ionized plasma, may suffer from rapid signal amplitude and/or phase fluctuations known as scintillation. Caused by non-uniform structures in the ionosphere, intense scintillation can lead to GNSS navigation and high-frequency (HF) communication failures. With specialized GNSS receivers, scintillation can be studied to better understand the structure and dynamics of the ionospheric irregularities, which can be parameterized by altitude, drift motion, anisotropy of the shape, horizontal spatial extent and their time evolution. To study the structuring and motion of ionospheric irregularities at the sub-kilometer scale sizes that produce L-band scintillations, a closely-spaced GNSS array has been established in the auroral zone at Poker Flat Research Range, Alaska to investigate high latitude scintillation and irregularities. Routinely collecting low-rate scintillation statistics, the array database also provides 100 Hz power and phase data for each channel at L1/L2C frequency. In this work, a survey of seasonal and hourly dependence of L1 scintillation events over the course of a year is discussed. To efficiently and systematically study scintillation events, an automated low-rate scintillation detection routine is established and performed for each day by screening the phase scintillation index. The spaced-receiver technique is applied to cross

Sporadic colorectal polyps and mismatch repair proteins

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Mahsa Molaei

2011-01-01

Full Text Available Background: Colorectal cancers often arise from benign polyps. Adenomatous polyps and serrated polyps progress step by step to adenocarcinoma and change into malignant cancers. Genetic and epigenetic changes have correlation with specific stages of polyp-adenocarcinoma progression and colorectal cancer histopathological changes. Aims: In this study we used immunohistochemistry (IHC staining in sporadic colorectal polyps to assay functional status of MLH1, MSH2, MSH6, and PMS2 proteins, to track genetic/epigenetic roles of this issue in our patients. Materials and Methods: In this cross-sectional study we assessed all patients who were admitted with sporadic colorectal polyps and underwent polypectomy in endoscopy department during 2004-2008. Result: IHC results were abnormal in 6.8% cases for MLH1, in 4.5% cases for MSH2, in 3% for MSH6, and in 4.8% for PMS2. In all cases with abnormal PMS2, MLH1 was also reported as abnormal. Same results were reported for abnormal MSH2, which is accompanied with abnormal MSH6 in all cases (P values < 0.001. There is no significant difference between IHC staining results, gender, dysplasia grade, adenomatous type, and invasion. On the other hand, there was significant difference between IHC staining results, polyp location, and mean age of patients. The same significant difference was between adenomatous polyps and serrated adenoma polyps by MLH1 and PMS2 (P values < 0.05. Conclusion: According to our findings, maybe MMR dysfunction is the cause of sporadic colorectal polyps in younger age and its increasing risk of dysplasia progression and malignancy progression is only in serrated adenoma. Sporadic polyps in left colon had a higher risk to progress to malignancies, and abnormal IHC staining for MLH1 and PMS2 in serrated polyps is much more than in other adenomatous polyps.

Apolipoprotein e genotype, plasma cholesterol, and cancer: a Mendelian randomization study.

LENUS (Irish Health Repository)

Trompet, Stella

2009-12-01

Observational studies have shown an association between low plasma cholesterol levels and increased risk of cancer, whereas most randomized clinical trials involving cholesterol-lowering medications have not shown this association. Between 1997 and 2002, the authors assessed the association between plasma cholesterol levels and cancer risk, free from confounding and reverse causality, in a Mendelian randomization study using apolipoprotein E (ApoE) genotype. ApoE genotype, plasma cholesterol levels, and cancer incidence and mortality were measured during a 3-year follow-up period among 2,913 participants in the Prospective Study of Pravastatin in the Elderly at Risk. Subjects within the lowest third of plasma cholesterol level at baseline had increased risks of cancer incidence (hazard ratio (HR) = 1.90, 95% confidence interval (CI): 1.34, 2.70) and cancer mortality (HR = 2.03, 95% CI: 1.23, 3.34) relative to subjects within the highest third of plasma cholesterol. However, carriers of the ApoE2 genotype (n = 332), who had 9% lower plasma cholesterol levels than carriers of the ApoE4 genotype (n = 635), did not have increased risk of cancer incidence (HR = 0.86, 95% CI: 0.50, 1.47) or cancer mortality (HR = 0.70, 95% CI: 0.30, 1.60) compared with ApoE4 carriers. These findings suggest that low cholesterol levels are not causally related to increased cancer risk.

Neuronal pentraxin 1: A synaptic-derived plasma biomarker in Alzheimer's disease.

Science.gov (United States)

Ma, Qiu-Lan; Teng, Edmond; Zuo, Xiaohong; Jones, Mychica; Teter, Bruce; Zhao, Evan Y; Zhu, Cansheng; Bilousova, Tina; Gylys, Karen H; Apostolova, Liana G; LaDu, Mary Jo; Hossain, Mir Ahamed; Frautschy, Sally A; Cole, Gregory M

2018-06-01

Synaptic neurodegeneration is thought to be an early event initiated by soluble β-amyloid (Aβ) aggregates that closely correlates with cognitive decline in Alzheimer disease (AD). Apolipoprotein ε4 (APOE4) is the most common genetic risk factor for both familial AD (FAD) and sporadic AD; it accelerates Aβ aggregation and selectively impairs glutamate receptor function and synaptic plasticity. However, its molecular mechanisms remain elusive and these synaptic deficits are difficult to monitor. AD- and APOE4-dependent plasma biomarkers have been proposed, but synapse-related plasma biomarkers are lacking. We evaluated neuronal pentraxin 1 (NP1), a potential CNS-derived plasma biomarker of excitatory synaptic pathology. NP1 is preferentially expressed in brain and involved in glutamate receptor internalization. NP1 is secreted presynaptically induced by Aβ oligomers, and implicated in excitatory synaptic and mitochondrial deficits. Levels of NP1 and its fragments were increased in a correlated fashion in both brain and plasma of 7-8 month-old E4FAD mice relative to E3FAD mice. NP1 was also found in exosome preparations and reduced by dietary DHA supplementation. Plasma NP1 was higher in E4FAD+ (APOE4 +/+ /FAD +/- ) relative to E4FAD- (non-carrier; APOE4 +/+ /FAD -/- ) mice, suggesting NP1 is modulated by Aβ expression. Finally, relative to normal elderly, plasma NP1 was also elevated in patients with mild cognitive impairment (MCI) and elevated further in the subset who progressed to early-stage AD. In those patients, there was a trend towards increased NP1 levels in APOE4 carriers relative to non-carriers. These findings indicate that NP1 may represent a potential synapse-derived plasma biomarker relevant to early alterations in excitatory synapses in MCI and early-stage AD. Copyright © 2018. Published by Elsevier Inc.

Plasma folic acid cutoff value, derived from its relationship with homocyst(e)ine.

Science.gov (United States)

Brouwer, D A; Welten, H T; Reijngoud, D J; van Doormaal, J J; Muskiet, F A

1998-07-01

We established the cutoff value for plasma folic acid, using plasma homocyst(e)ine as the functional marker. To do this, we investigated the relationship of the plasma folic acid of 103 apparently healthy adults with their fasting plasma homocyst(e)ine and with their plasma homocyst(e)ine 6 h after oral methionine challenge (100 mg/kg). We also studied the relationship of their plasma folic acid with the decline of fasting plasma homocyst(e)ine after 7 days of folic acid supplementation (5 mg/day). The three approaches suggested a cutoff value of 10 nmol/L. The chances of individuals to significantly (P ine after folic acid supplementation proved significantly higher at plasma folic acid concentrations < or = 10 nmol/L, as compared with folic acid concentrations above this value (odds ratio, 5.02; 95% confidence interval, 1.87-13.73). We suggest adopting a 10 nmo/L plasma folic acid cutoff value on functional grounds.

Laser ablated copper plasmas in liquid and gas ambient

Energy Technology Data Exchange (ETDEWEB)

Kumar, Bhupesh; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

2013-05-15

The dynamics of copper ablated plasma plumes generated using laser ablation of copper targets in both liquid (de-ionized water) and gas (air) ambients is reported. Using time and space resolved visible emission spectroscopy (450-650 nm), the plasma plumes parameters are investigated. The electron density (n{sub e}) determined using Stark broadening of the Cu I (3d{sup 10}4d{sup 1} {sup 2}D{sub 3/2}-3d{sup 10}4p{sup 1} {sup 2}P{sub 3/2} at 521.8 nm) line is estimated and compared for both plasma plumes. The electron temperature (T{sub e}) was estimated using the relative line emission intensities of the neutral copper transitions. Field emission scanning electron microscopy and energy dispersive x-ray spectral analysis of the ablated copper surface indicated abundance of spherical nanoparticles in liquid while those in air are amalgamates of irregular shapes. The nanoparticles suspended in the confining liquid form aggregates and exhibit a surface plasmon resonance at ∼590 nm.

More evidence for a planetary wave link with midlatitude E region coherent backscatter and sporadic E layers

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K. Schlegel

Full Text Available Measurements of midlatitude E region coherent backscatter obtained during four summers with SESCAT, a 50 MHz Doppler system operating in Crete, Greece, and concurrent ionosonde recordings from the same ionospheric volume obtained with a CADI for one of these summers, are used to analyse the long-term variability in echo and Es occurrence. Echo and Es layer occurrences, computed in percent of time over a 12-h nighttime interval, take the form of time sequences. Linear power spectrum analysis shows that there are dominant spectral peaks in the range of 2–9 days, the most commonly observed periods appearing in two preferential bands, of 2–3 days and 4–7 days. No connection with geomagnetic activity was found. The characteristics of these periodicities compare well with similar properties of planetary waves, which suggests the possibility that planetary waves are responsible for the observed long-term periodicities. These findings indicate also a likely close relation between planetary wave (PW activity and the well known but not well understood seasonal Es dependence. To test the PW postulation, we used simultaneous neutral wind data from the mesopause region around 95 km, measured from Collm, Germany. Direct comparison of the long-term periodicities in echo and Es layer occurrence with those in the neutral wind show some reasonable agreement. This new evidence, although not fully conclusive, is the first direct indication in favour of a planetary wave role on the unstable midlatitude E region ionosphere. Our results suggest that planetary waves observation is a viable option and a new element into the physics of midlatitude Es layers that needs to be considered and investigated.Key words: Ionosphere (ionosphere irregularities; mid-latitude ionosphere – Meteorology and atmospheric dynamics (waves and tides

Note: A single-chamber tool for plasma activation and surface functionalization in microfabrication

Energy Technology Data Exchange (ETDEWEB)

Bowman, Adam J.; Scherrer, Joseph R.; Reiserer, Ronald S., E-mail: ron.reiserer@vanderbilt.edu [Vanderbilt Institute for Integrative Biosystems Research and Education and Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2015-06-15

We present a simple apparatus for improved surface modification of polydimethylsiloxane (PDMS) microfluidic devices. A single treatment chamber for plasma activation and chemical/physical vapor deposition steps minimizes the time-dependent degradation of surface activation that is inherent in multi-chamber techniques. Contamination and deposition irregularities are also minimized by conducting plasma activation and treatment phases in the same vacuum environment. An inductively coupled plasma driver allows for interchangeable treatment chambers. Atomic force microscopy confirms that silane deposition on PDMS gives much better surface quality than standard deposition methods, which yield a higher local roughness and pronounced irregularities in the surface.

White matter involvement in sporadic Creutzfeldt-Jakob disease.

Science.gov (United States)

Caverzasi, Eduardo; Mandelli, Maria Luisa; DeArmond, Stephen J; Hess, Christopher P; Vitali, Paolo; Papinutto, Nico; Oehler, Abby; Miller, Bruce L; Lobach, Irina V; Bastianello, Stefano; Geschwind, Michael D; Henry, Roland G

2014-12-01

Sporadic Creutzfeldt-Jakob disease is considered primarily a disease of grey matter, although the extent of white matter involvement has not been well described. We used diffusion tensor imaging to study the white matter in sporadic Creutzfeldt-Jakob disease compared to healthy control subjects and to correlated magnetic resonance imaging findings with histopathology. Twenty-six patients with sporadic Creutzfeldt-Jakob disease and nine age- and gender-matched healthy control subjects underwent volumetric T1-weighted and diffusion tensor imaging. Six patients had post-mortem brain analysis available for assessment of neuropathological findings associated with prion disease. Parcellation of the subcortical white matter was performed on 3D T1-weighted volumes using Freesurfer. Diffusion tensor imaging maps were calculated and transformed to the 3D-T1 space; the average value for each diffusion metric was calculated in the total white matter and in regional volumes of interest. Tract-based spatial statistics analysis was also performed to investigate the deeper white matter tracts. There was a significant reduction of mean (P=0.002), axial (P=0.0003) and radial (P=0.0134) diffusivities in the total white matter in sporadic Creutzfeldt-Jakob disease. Mean diffusivity was significantly lower in most white matter volumes of interest (PCreutzfeldt-Jakob disease. Mean diffusivity reduction reflected concomitant decrease of both axial and radial diffusivity, without appreciable changes in white matter anisotropy. Tract-based spatial statistics analysis showed significant reductions of mean diffusivity within the white matter of patients with sporadic Creutzfeldt-Jakob disease, mainly in the left hemisphere, with a strong trend (P=0.06) towards reduced mean diffusivity in most of the white matter bilaterally. In contrast, by visual assessment there was no white matter abnormality either on T2-weighted or diffusion-weighted images. Widespread reduction in white matter mean

Post-midnight occurrence of equatorial plasma bubbles

Science.gov (United States)

Ajith, K. K.; Otsuka, Yuichi; Yamamoto, Mamoru; Yokoyama, Tatsuhiro; Tulasiram, S.

2016-07-01

The equatorial plasma bubbles (EPBs)/equatorial spread F (ESF) irregularities are an important topic of space weather interest because of their impact on transionospheric radio communications, satellite-based navigation and augmentation systems. This local plasma depleted structures develop at the bottom side F layer through Rayleigh-Taylor instability and rapidly grow to topside ionosphere via polarization electric fields within them. The steep vertical gradients due to quick loss of bottom side ionization and rapid uplift of equatorial F layer via prereversal enhancement (PRE) of zonal electric field makes the post-sunset hours as the most preferred local time for the formation of EPBs. However, there is a different class of irregularities that occurs during the post-midnight hours of June solstice reported by the previous studies. The occurrence of these post-midnight EPBs maximize during the low solar activity periods. The growth characteristics and the responsible mechanism for the formation of these post-midnight EPBs are not yet understood. Using the rapid beam steering ability of 47 MHz Equatorial Atmosphere Radar (EAR) at Kototabang (0.2°S geographic latitude, 100.3°E geographic longitude, and 10.4°S geomagnetic latitude), Indonesia, the spatial and temporal evolution of equatorial plasma bubbles (EPBs) were examined to classify the evolutionary-type EPBs from those which formed elsewhere and drifted into the field of view of radar. The responsible mechanism for the genesis of summer time post-midnight EPBs were discussed in light of growth rate of Rayleigh-Taylor instability using SAMI2 model.

Legal aspects of the EU policy on irregular immigration

Directory of Open Access Journals (Sweden)

Voinikov Vadim

2015-12-01

Full Text Available This article addresses the issues pertaining to the adoption and development of legislation on irregular migration in the context of uncontrolled growth in the number of immigrants from North Africa and the Middle East to the EU. The article attempts at studying the EU legislation on irregular migration, classifying it, and analysing the prospects of EU migration legislation in the light of an increase in irregular immigration into the EU. The author systematises, classifies the current EU legislation on irregular immigration, and analyses the conditions, in which this legislation was developed. Using the legislation analysis method, the author proposes the following system of EU legislation on irregular immigration: rules preventing assistance to irregular immigration, rules preventing employment of irregular immigrants, rules on the return of irregular migrants and readmission, rules on border control, and rules on collaboration with third countries. The author pays special attention to analysing the current state of irregular immigration to the EU, which was dubbed the ‘greatest migration crisis in Europe’. The conclusion is that the European Union succeeded in the development of pioneering legislation on irregular immigration, which can serve as the basis for reception by other states. However, changes in the political and economic situation in the EU’s southern borderlands made the current legal mechanisms incapable of withstanding new threats. It necessitates a radical reform of the legislation on irregular immigration.

Irregular menstruation according to occupational status.

Science.gov (United States)

Kwak, Yeunhee; Kim, Yoonjung

2017-07-06

This cross-sectional study explored associations of irregular menstruation with occupational characteristics, using secondary analyses of data from 4,731 women aged 19-54 years, collected from a nationally representative sample, the Korea National Health and Nutrition Examination Survey-V during 2010-2012. The associations between irregular menstruation and occupation were explored using multiple logistic regression. Compared to non-manual workers, service/sales workers had a greater odds of irregular menstruation (adjusted odds ratio [aOR]: 1.44; 95percent confidence interval [CI]: 1.04-1.99) as did manual workers and unemployed women (aOR: 1.56; 95percent CI: 1.10-2.22, aOR: 1.46; 95percent CI: 1.14-1.89, respectively). Compared to regular workers, temporary workers and unemployed women had aORs of 1.52 (95percent CI: 1.08-2.13) and 1.33 (95percent CI: 1.05-1.69), respectively. Also, when compared to full-time workers, part-time workers and unemployed women had greater odds of irregular menstruation (aOR: 1.41; 95percent CI: 1.00-2.00 and aOR: 1.29; 95percent CI: 1.03-1.63, respectively). Furthermore, compared to daytime workers, shift workers and unemployed women had greater odds irregular menstruation (aOR: 1.39; 95percent CI: 1.03-1.88 and aOR: 1.28; 95percent CI: 1.04-1.59, respectively). Women with these occupational characteristics should be screened for early diagnosis and intervention for irregular menstruation.

Irregular conformal block, spectral curve and flow equations

International Nuclear Information System (INIS)

Choi, Sang Kwan; Rim, Chaiho; Zhang, Hong

2016-01-01

Irregular conformal block is motivated by the Argyres-Douglas type of N=2 super conformal gauge theory. We investigate the classical/NS limit of irregular conformal block using the spectral curve on a Riemann surface with irregular punctures, which is equivalent to the loop equation of irregular matrix model. The spectral curve is reduced to the second order (Virasoro symmetry, SU(2) for the gauge theory) and third order (W_3 symmetry, SU(3)) differential equations of a polynomial with finite degree. The conformal and W symmetry generate the flow equations in the spectral curve and determine the irregular conformal block, hence the partition function of the Argyres-Douglas theory ala AGT conjecture.

Determinants of plasma homocyst(e)ine in patients with nephrotic syndrome.

Science.gov (United States)

Joven, J; Arcelús, R; Camps, J; Ordóñez-Llanos, J; Vilella, E; González-Sastre, F; Blanco-Vaca, F

2000-01-01

Hyperhomocyst(e)inemia is an independent risk factor for atherothrombosis in several clinical settings in which renal function is impaired, but its prevalence in the nephrotic syndrome has not been investigated in detail, even though this syndrome provides an excellent model in which to study a possible link between albuminuria, proteinuria, and hyperhomocyst(e)inemia. We obtained plasma and urine from 27 patients with biopsy-confirmed membranous glomerulonephritis presenting nephrotic syndrome and 27 matched controls and determined the concentrations of homocyst(e)ine and proteins considered putative markers of glomerular and tubular function. Hyperhomocyst(e)inemia, defined as the mean +SD of the plasma homocyst(e)ine concentration of the controls [plasma homocyst(e)ine concentration >10.8 micromol/l] was present in 26% of the patients with nephrotic syndrome but in only 7.4% of the controls. Furthermore, the degree of hyperhomocyst(e)inemia was more severe in the nephrotic patients than in the controls. The existence of renal failure, tubular damage, and, interestingly, relatively well conserved glomerular function barrier were the main predictors of increased levels of plasma homocyst(e)ine. In conclusion, hyperhomocyst(e)inemia is a frequent cardiovascular risk factor present in patients with nephrotic syndrome and renal failure, but it is not directly associated with proteinuria.

Vitamin intake: a possible determinant of plasma homocyst(e)ine among middle-aged adults.

Science.gov (United States)

Shimakawa, T; Nieto, F J; Malinow, M R; Chambless, L E; Schreiner, P J; Szklo, M

1997-05-01

Many epidemiologic studies have identified elevated plasma homocyst(e)ine as a risk factor for atherosclerosis and thromboembolic disease. To examined the relationship between vitamin intakes and plasma homocyst(e)ine, we analyzed dietary intake data from a case-control study of 322 middle-aged individuals with atherosclerosis in the carotid artery and 318 control subjects without evidence of this disease. All of these individuals were selected from a probability sample of 15,800 men and women who participated in the Atherosclerosis Risk in Communities (ARIC) Study. Plasma homocyst(e)ine was inversely associated with intakes of folate, vitamin B6, and vitamin B12 (controls only for this vitamin)--the three key vitamins in homocyst(e)ine metabolism. Among nonusers of vitamin supplement products, on average each tertile increase in intake of these vitamins was associated with 0.4 to 0.7 mumol/L decrease in plasma homocyst(e)ine. An inverse association of plasma homocyst(e)ine was also found with thiamin, riboflavin, calcium, phosphorus, and iron. Methionine and protein intake did not show any significant association with plasma homocyst(e)ine. In almost all analyses, cases and controls showed similar associations between dietary variables and plasma homocyst(e)ine. Plasma homocyst(e)ine among users of vitamin supplement products was 1.5 mumol/L lower than that among nonusers. Further studies to examine possible causal relationships among vitamin intake, plasma homocyst(e)ine, and cardiovascular disease are needed.

Plasma instabilities multifrequency study in equatorial electrojet

International Nuclear Information System (INIS)

Hanuise, C.

1983-01-01

In this thesis, multifrequential HF coherent radar results are presented, in the field plasma instabilities in equatorial electrojet. In a first part, characteristics of the irregularities observed either at the 3 meter wavelength by VHF radars, either at other wavelengths during pinpoint experiments, or in-situ by probe rockets are recalled. Theoretical studies progressed and are presented, at the same time with these experimental observations: instability linear theory, non linear theories, HF radar specificity, and problems associated to HF waves propagation and refraction in ionosphere. Original experimental results from Ethiopia are gathered in the second part. Plasma instability has been studied in different geophysical conditions and Doppler spectra characteristics are presented for each one of them. These characteristics are completely different according to the various cases; they are also different according to wether observations are made during the day in normal conditions (electric field pointed to the east at the equator) or in counter-electrojet conditions (electric field pointed to the west). The last part is concerned with theoretical interpretation of the previous results. A comprehensive view of the instability physical mechanisms, according to the geophysical conditions encountered, has been allowed by our results, VHF radar measurements at Jicamarca, or in situ probe measurements on the whole. Irregularities study has been limited to the E region [fr

Plasma spheroidization of iron powders in a non-transferred DC thermal plasma jet

International Nuclear Information System (INIS)

Kumar, S.; Selvarajan, V.

2008-01-01

In this paper, the results of plasma spheroidization of iron powders using a DC non-transferred plasma spray torch are presented. The morphology of the processed powders was characterized through scanning electron microscopy (SEM) and optical microscopy (OM). The percentages of spheroidized powders were calculated by the shape factors such as the Irregularity Parameter (IP) and Roundness (RN). A maximum of 83% of spheroidization can be achieved. The spheroidization results are compared with the theoretical estimation and they are found to be in good agreement. The phase composition of the spheroidized powder was analyzed by XRD. The effect of plasma jet temperature and plasma gas flow rate on spheroidization is discussed. At low plasma gas flow rates and at high plasma jet temperatures, the percentage of spheroidization is high

16 CFR 501.6 - Cellulose sponges, irregular dimensions.

Science.gov (United States)

2010-01-01

... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Cellulose sponges, irregular dimensions. 501... REQUIREMENTS AND PROHIBITIONS UNDER PART 500 § 501.6 Cellulose sponges, irregular dimensions. Variety packages of cellulose sponges of irregular dimensions, are exempted from the requirements of § 500.25 of this...

Ethical issues in irregular migration research

NARCIS (Netherlands)

Duvell, F.; Triandafyllidou, A.; Vollmer, B.

2008-01-01

This paper is concerned with the ethical issues arising for researchers engaged in the study of irregular migration. Irregular migration is by definition an elusive phenomenon as it takes place in violation of the law and at the margins of society. This very nature of the phenomenon raises important

Cross-B convection of artificially created, negative-ion clouds and plasma depressions: Low-speed flow

International Nuclear Information System (INIS)

Bernhardt, P.A.

1988-01-01

A negative-ion, positive-ion plasma produced by the release of an electron attachment chemical into the F region becomes electrically polarized by the collisions with neutrals moving across magnetic field lines. The resulting electric field causes E x B drift of the two ion species and the residual electrons. The cross-field flow of the modified ionosphere is computed using a two-dimensional numerical simulation which includes electron attachment and mutual neutralization chemistry, self-consistent electric fields, and three-species plasma transport. The velocity of the plasma is initially in the direction of the neutral wind because the negative-ion cloud is a Pedersen conductivity enhancement. As the positive and negative ions react, the Pedersen conductivity becomes depressed below the ambient value and the velocity of the plasma reverses direction. A plasma hole remains after the positive and negative ions have mutually neutralized. The E x B gradient drift instability produces irregularities on the upwind edge of the hole. These processes may be observed experimentally with optical and backscatter-radar diagnostics

RF heating of currentless plasma in Heliotron E

International Nuclear Information System (INIS)

Iiyoshi, A.; Motojima, O.; Sato, M.

1985-01-01

Recent electron cyclotron resonance heating (ECRH) and ion cyclotron range frequency heating (ICRF) experiments performed with a current-free plasma in Heliotron E are described. Parametric studies of ECRH are in progress. For both fundamental and second-harmonic resonances, optimum heating is observed when the plasma density is near the cutoff density (for the ordinary wave, in the case of fundamental resonance and for the extraordinary wave, in the case of second-harmonic resonance) and when a resonance zone exists on the magnetic axis. The maximum heating efficiencies for the fundamental and second-harmonic resonances are 6.5 eV.kW -1 per 10 19 m -3 and 2.4 eV.kW -1 per 10 19 m -3 , respectively. The ray-tracing analysis agrees qualitatively well with the experimental results. The power dependences of the plasma parameters are also investigated. - The first ICRF experiment with fast-wave heating of a current-free plasma has been performed. The ICRF wave power and pulse length are 550 kW and 15 ms, respectively. The frequency is 26.7 MHz. Ions and electrons are heated effectively. The increase in ion temperature is only slightly changed by varying the hydrogen ratio of the gas puff. On the other hand, the electron temperature increase has a definite peak for a high proton ratio (approx. 15%). This agrees qualitatively with the mode conversion picture of minority heating. (author)

Study of sporadic E layers based on GPS radio occultation measurements and digisonde data over the Brazilian region

Science.gov (United States)

Resende, Laysa C. A.; Arras, Christina; Batista, Inez S.; Denardini, Clezio M.; Bertollotto, Thainá O.; Moro, Juliano

2018-04-01

This work presents new results about sporadic E-layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data. The RO profiles are used to study the Es layer occurrence as well as its intensity of the signal-to-noise ratio (SNR) of the 50 Hz GPS L1 signal. The methodology was applied to identify the Es layer on RO measurements over Cachoeira Paulista, a low-latitude station in the Brazilian region, in which the Es layer development is not driven tidal winds only as it is at middle latitudes. The coincident events were analyzed using the RO technique and ionosonde observations during the year 2014 to 2016. We used the electron density obtained using the blanketing frequency parameter (fbEs) and the Es layer height (h'Es) acquired from the ionograms to validate the satellite measurements. The comparative results show that the Es layer characteristics extracted from the RO measurements are in good agreement with the Es layer parameters from the digisonde.

Vitamin E and vitamin E-quinone levels in red blood cells and plasma of newborn infants and their mothers.

Science.gov (United States)

Jain, S K; Wise, R; Bocchini, J J

1996-02-01

Vitamin E is a physiological antioxidant and protects cell membranes from oxidative damage. This study has determined whether vitamin E level in RBC of newborns has any relationship with its level in their mothers. We have also examined levels of vitamin E and vitamin E-quinone, an oxidized product of vitamin E, in paired samples of red blood cells (RBC) and plasma of newborns and their mothers. Blood was collected from 26 mothers and their full-term placental cords at delivery. Vitamin E and vitamin E-quinone levels were determined in RBC and plasma by HPLC. Newborn-plasma had significantly lower vitamin E levels compared with maternal-plasma both when expressed as nmole/ml (5.5+/-0.4 vs 26.1+/-1.1, p = 0.0001) or nmole/mumole total lipids (1.9+/-0.1 vs 2.6+/-0.1, p = 0.0001). Vitamin E level in the newborn-RBC was similar to that of maternal-RBC when expressed as nmole/ml packed cells (2.77+/-0.14 vs 2.95+/-0.13), but was significantly lower when expressed as nmole/mumole total lipids (0.56+/-0.03 vs 0.64+/-0.04, p = 0.03) from that of maternal-RBC. Vitamin E-quinone levels are significantly elevated in newborns compared with their mothers both in RBC (29.4+/-2.1 vs 24.1+/-1.2, p = 0.04) and plasma (39.9+/-5.3 vs 25.3+/-4.2, p = 0.006) when expressed as nmole/mmole total lipids but not when expressed as nmole/ml. There was a significant correlation of vitamin E between newborn-plasma and newborn-RBC (r = 0.65, p = 0.0002 for nmole per ml packed RBC;r = 0.63, p = 0.0007 for nmole per mumole total lipids). The relationship between maternal plasma and newborn plasma was significant when vitamin E was normalized with nmole/mumole total lipid (r = 0.54, p = 0.007 but not when expressed as nmole/ml (r = 0.09, p = 0.64). However, vitamin E in the RBC of maternal and newborn had significant correlation when expressed as per ml packed cells (r = 0.61, p = 0.001) and per total lipid (r = 0.46, p = 0.02). There was no relationship of vitamin E-quinone levels between RBC and

Design and experiment of high-current low-pressure plasma-cathode e-gun

International Nuclear Information System (INIS)

Xie Wenkai; Li Xiaoyun; Wang Bin; Meng Lin; Yan Yang; Gao Xinyan

2006-01-01

The preliminary design of a new high-power low pressure plasma-cathode e-gun is presented. Based on the hollow cathode effect and low-pressure glow discharge empirical formulas, the hollow cathode, the accelerating gap, and the working gas pressure region are given. The general experimental device of the low-pressure plasma cathode electron-gun generating high current density e-beam source is shown. Experiments has been done in continuous filled-in gases and gases-puff condition, and the discharging current of 150-200 A, the width of 60 μs and the collector current of 30-80 A, the width of 60 μs are obtained. The results show that the new plasma cathode e-gun can take the place of material cathode e-gun, especially in plasma filled microwave tubes. (authors)

Sporadic simple groups and quotient singularities

International Nuclear Information System (INIS)

Cheltsov, I A; Shramov, C A

2013-01-01

We show that if a faithful irreducible representation of a central extension of a sporadic simple group with centre contained in the commutator subgroup gives rise to an exceptional (resp. weakly exceptional but not exceptional) quotient singularity, then that simple group is the Hall-Janko group (resp. the Suzuki group)

Hanseníase e vulnerabilidade social: uma análise do perfil socioeconômico de usuários em tratamento irregular

Directory of Open Access Journals (Sweden)

Viviane Aparecida Siqueira Lopes

Full Text Available Este artigo analisa a determinação social da hanseníase, a partir do reconhecimento da vulnerabilidade social dos usuários em tratamento irregular, no Programa de Controle da Hanseníase do município de Campos dos Goytacazes (RJ. Para isso, apresenta uma pesquisa documental, com base nas Fichas de Cadastro Social dos usuários mencionados, destacando aspectos como trabalho, renda, formação familiar e acesso a políticas públicas. Seus resultados registram significativa presença de trabalho precarizado associado a baixos níveis de renda e de escolaridade, sendo a maioria considerada pobre ou indigente (51,5% e não usuária de benefícios assistenciais (66,7%.

Deletion and reduced expression of the Fanconi anemia FANCA gene in sporadic acute myeloid leukemia.

Science.gov (United States)

Tischkowitz, M D; Morgan, N V; Grimwade, D; Eddy, C; Ball, S; Vorechovsky, I; Langabeer, S; Stöger, R; Hodgson, S V; Mathew, C G

2004-03-01

Fanconi anemia (FA) is an autosomal recessive chromosomal instability disorder caused by mutations in one of seven known genes (FANCA,C,D2,E,F,G and BRCA2). Mutations in the FANCA gene are the most prevalent, accounting for two-thirds of FA cases. Affected individuals have greatly increased risks of acute myeloid leukemia (AML). This raises the question as to whether inherited or acquired mutations in FA genes might be involved in the development of sporadic AML. Quantitative fluorescent PCR was used to screen archival DNA from sporadic AML cases for FANCA deletions, which account for 40% of FANCA mutations in FA homozygotes. Four heterozygous deletions were found in 101 samples screened, which is 35-fold higher than the expected population frequency for germline FANCA deletions (PFANCA in the AML samples with FANCA deletions did not detect mutations in the second allele and there was no evidence of epigenetic silencing by hypermethylation. However, real-time quantitative PCR analysis in these samples showed reduced expression of FANCA compared to nondeleted AML samples and to controls. These findings suggest that gene deletions and reduced expression of FANCA may be involved in the promotion of genetic instability in a subset of cases of sporadic AML.

The mathematical modelling of plasmas at the service of space technologies

International Nuclear Information System (INIS)

Besse, Christophe; Degond, Pierre; Vignal, Marie-Helene

2001-01-01

The objective is here to provide a background for some aspects of the mathematical modelling in physics (i.e. a physical problem, its description by an appropriate set of equations, a reduction of this set, implementation on a computer, selection of test cases, validation, result interpretation, visualisation, exploitation of the code for prediction or production purposes), in the case of aspects related to plasmas in space environment. These plasmas can be those of the environment (ionosphere), those created by abnormal operating conditions of the satellite (induced discharges), or those used for technological purposes (plasma propulsion). After a presentation of some basic notions regarding space environment (scales, sun and solar wind, definition of a plasma, magnetosphere, ionosphere), the authors propose a modelling of ionospheric irregularities (model of Euler-Maxwell, model without dimension, three-dimensional dynamo model, quasi-two-dimensional dynamo model, striation model, turbulence modelling). They address the problem of discharges occurring on satellites: problem description, scenario description, Vlasov equation, limits and numerical results

Occurrence of the lobe plasma at lunar distance

International Nuclear Information System (INIS)

Hardy, D.A.; Hills, H.K.; Freeman, J.W.

1979-01-01

Recent analysis has confirmed and expanded the characterization of the lobe plasma, the extension of the 'boundary layer' and 'plasma mantle' to lunar distances. Careful statistical analysis has verified that Magnetic Field (1MF). When the moon is in the dawnside of the northern lobe or duskside of the southern lobe, the probability for observation of the lobe plasma is greatly increased when, in the hour preceding, the IMF has had a positive y component. Conversely, when the moon is in the duskside of the northern lobe or dawnside of the southern lobe, the probability for observation is much increased when the IMF has a negative y component. Analysis of lobe plasma data in conjunction with high time resolution IMF data has shown the probability of observation also is greater with a southward pointing IMF. The observed correlations with the y and z components the IMF reflect the fact that the asymmetry and changes in magnitude of the polar cap electric field induced by the IMF extends to lunar distances and determines the depth into the tail to which the ions can drift. Generally, the lobe plasma is observed sporadically for a full day after the moon has entered the tail and a full day before the last magnetopause crossing as it exits the tail. An average extent of approx.8--10R/sub e/ inward from the magnetopause is inferred; however, the lobe plasma has been seen all across the tail

Screening of hypoxia-inducible genes in sporadic ALS.

LENUS (Irish Health Repository)

Cronin, Simon

2008-10-01

Genetic variations in two hypoxia-inducible angiogenic genes, VEGF and ANG, have been linked with sporadic amyotrophic lateral sclerosis (SALS). Common variations in these genes may reduce the levels or functioning of their products. VEGF and ANG belong to a larger group of angiogenic genes that are up-regulated under hypoxic conditions. We hypothesized that common genetic variation across other members of this group may also predispose to sporadic ALS. To screen other hypoxia-inducible angiogenic genes for association with SALS, we selected 112 tagging single nucleotide polymorphisms (tgSNPs) that captured the common genetic variation across 16 VEGF-like and eight ANG-like hypoxia-inducible genes. Screening for association was performed in 270 Irish individuals with typical SALS and 272 ethnically matched unrelated controls. SNPs showing association in the Irish phase were genotyped in a replication sample of 281 Swedish sporadic ALS patients and 286 Swedish controls. Seven markers showed association in the Irish. The one modest replication signal observed in the Swedish replication sample, at rs3801158 in the gene inhibin beta A, was for the opposite allele vs. the Irish cohort. We failed to detect association of common variation across 24 candidate hypoxia-inducible angiogenic genes with SALS.

Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

DEFF Research Database (Denmark)

Xiong, C.; Luhr, H.; Ma, S. Y.

2012-01-01

In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using bandpasses with four different cut-off periods to get the EPBs with different......). Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence...

Determination of free and total cyst(e)ine in plasma of dogs and cats.

Science.gov (United States)

Tôrres, Cristina L; Miller, Joshua W; Rogers, Quinton R

2004-01-01

In human blood, the amino acid cysteine forms disulfide bonds with itself and with other sulfhydryl compounds in their free form and with sulfhydryls in protein. Protein-bound cysteine is lost when plasma proteins are removed before amino acid analysis. The purpose of this study was to assess the time course and extent of cyst(e)ine (cysteine + half-cystine) loss in dog and cat plasma. An equal volume of 6% sulfosalicylic acid was added to plasma aliquots at 0, 2, 4, 10, 16, 24, 36, 48, 60, and 72 hours after separation of blood cells. Tris-2-carboxyethyl-phosphine hydrochloride (TCEP - HCl), a reducing agent, was used to regenerate total plasma cyst(e)ine after 3 months of sample storage (-20 degrees C). Initial free cyst(e)ine concentrations (mean +/- SEM) were higher in canine plasma (77 +/- 4 micromol/L) than in feline plasma (37 +/- 3 micromol/L). Free plasma cyst(e)ine concentrations in dogs and cats decreased after first-order kinetics, with a half-life of 23 and 69 hours, respectively. Total plasma cysteine after TCEP - HCl treatment was similar for dogs (290 micromol/L) and cats (296 micromol/L), but the percentage of free cysteine was higher (P = .02) in dogs (27%) than in cats (13%). Over half of the cyst(e)ine, homocysteine, cysteinylglycine, and glutathione were bound in vivo to plasma proteins. These results emphasize the importance of removing plasma proteins within 1 hour after blood collection for reliable assay of free plasma cyst(e)ine.

Locating irregularly shaped clusters of infection intensity

Directory of Open Access Journals (Sweden)

Niko Yiannakoulias

2010-05-01

Full Text Available Patterns of disease may take on irregular geographic shapes, especially when features of the physical environment influence risk. Identifying these patterns can be important for planning, and also identifying new environmental or social factors associated with high or low risk of illness. Until recently, cluster detection methods were limited in their ability to detect irregular spatial patterns, and limited to finding clusters that were roughly circular in shape. This approach has less power to detect irregularly-shaped, yet important spatial anomalies, particularly at high spatial resolutions. We employ a new method of finding irregularly-shaped spatial clusters at micro-geographical scales using both simulated and real data on Schistosoma mansoni and hookworm infection intensities. This method, which we refer to as the “greedy growth scan”, is a modification of the spatial scan method for cluster detection. Real data are based on samples of hookworm and S. mansoni from Kitengei, Makueni district, Kenya. Our analysis of simulated data shows how methods able to find irregular shapes are more likely to identify clusters along rivers than methods constrained to fixed geometries. Our analysis of infection intensity identifies two small areas within the study region in which infection intensity is elevated, possibly due to local features of the physical or social environment. Collectively, our results show that the “greedy growth scan” is a suitable method for exploratory geographical analysis of infection intensity data when irregular shapes are suspected, especially at micro-geographical scales.

Increased androgen, anti-Müllerian hormone, and sporadic anovulation in healthy, eumenorrheic women: a mild PCOS-like phenotype?

Science.gov (United States)

Sjaarda, Lindsey A; Mumford, Sunni L; Kissell, Kerri; Schliep, Karen C; Hammoud, Ahmad O; Perkins, Neil J; Weck, Jennifer; Wactawski-Wende, Jean; Schisterman, Enrique F

2014-06-01

Hyperandrogenism is a hallmark of polycystic ovary syndrome (PCOS) in women with irregular menses, yet the relationship between androgens and ovarian dysfunction remains poorly understood in eumenorrheic women. The objective of the study was to evaluate whether sporadic anovulation was associated with higher T and anti-müllerian hormone (AMH; marker of ovarian follicle count) concentrations in eumenorrheic women. This was a prospective cohort study from 2005 to 2007. The study was conducted at the University of Buffalo in western New York state. A total of 259 eumenorrheic women without a self-reported history of infertility, PCOS, or other endocrine disorder participated in the study. Total T and AMH were measured five to eight times per cycle for one (n = 9) or two (n = 250) cycles per woman (n = 509 cycles) with timing of menstrual cycle phase assisted by fertility monitors. Anovulatory cycles were defined biochemically by progesterone and LH concentrations. Repeated-measures ANOVA was conducted on log-transformed data with adjustment for age. Compared with ovulatory cycles (n = 467), sporadic anovulatory cycles (n = 42) had marginally higher total and significantly higher free T [mean 23.7 ng/dL (95% confidence interval [CI] 21.4-26.3) vs 21.6 ng/dL (95% CI 20.9-22.3), P = .08, and 0.36 ng/dL (95% CI 0.33-0.40) vs 0.32 ng/dL (95% CI 0.31-0.33), P = .02, respectively] during menses and also throughout the luteal phase (P PCOS in women with menstrual disturbances may occur across a continuum of T concentrations, including in eumenorrheic women without clinical hyperandrogenism.

Detecting chaos in irregularly sampled time series.

Science.gov (United States)

Kulp, C W

2013-09-01

Recently, Wiebe and Virgin [Chaos 22, 013136 (2012)] developed an algorithm which detects chaos by analyzing a time series' power spectrum which is computed using the Discrete Fourier Transform (DFT). Their algorithm, like other time series characterization algorithms, requires that the time series be regularly sampled. Real-world data, however, are often irregularly sampled, thus, making the detection of chaotic behavior difficult or impossible with those methods. In this paper, a characterization algorithm is presented, which effectively detects chaos in irregularly sampled time series. The work presented here is a modification of Wiebe and Virgin's algorithm and uses the Lomb-Scargle Periodogram (LSP) to compute a series' power spectrum instead of the DFT. The DFT is not appropriate for irregularly sampled time series. However, the LSP is capable of computing the frequency content of irregularly sampled data. Furthermore, a new method of analyzing the power spectrum is developed, which can be useful for differentiating between chaotic and non-chaotic behavior. The new characterization algorithm is successfully applied to irregularly sampled data generated by a model as well as data consisting of observations of variable stars.

Plasma Immersion Ion Implantation in Radio Frequency Plasma

International Nuclear Information System (INIS)

Bora, B.; Bhuyan, H.; Wyndham, E.

2013-01-01

Plasma immersion ion implantation (PIII) has attracted wide interests since it emulates conventional ion-beam ion implantation (IBII) in niche applications. For instance, the technique has very high throughput, the implantation time is independent of the sample size, and samples with an irregular shape can be implanted without complex beam scanning or sample manipulation. For uniform ion implantation and deposition on to different substrates, like silicon, stainless steel etc., a capacitive coupled Radio frequency (RF), 13.6 MHz, plasma is used. During the PIII process, the physical parameters which are expected to play crucial rule in the deposition process like RF power, Negative pulse voltage and pulse duration, gas type and gas mixture, gas flow rates and the implantation dose are studied. The ion dose is calculated by dynamic sheath model and the plasma parameters are calculated from the V-I characteristic and power balance equation by homogeneous model of rf plasma discharge considering Ohmic as well as Stochastic heating. The correlations between the yield of the implantation process and the physical parameters as well as plasma parameters are discussed. (author)

Fatigue damage estimation using irregularity factor. First report, irregularity factor calculations for narrow and broadband random time histories

Science.gov (United States)

Susuki, I.

1981-11-01

The results of an analysis of the irregularity factors of stationary and Gaussian random processes which are generated by filtering the output of a pure or a band-limited white noise are presented. An ideal band pass filter, a trapezoidal filter, and a Butterworth type band pass filter were examined. It was found that the values of the irregularity factors were approximately equal among these filters if only the end-slopes were the same rates. As the band width of filters increases, irregularity factors increase monotonically and approach the respective constant values depending on the end-slopes. This implies that the noise characteristics relevant to the fatigue damage such as statistical aspects of the height of the rise and fall or the distribution of the peak values are not changed for a broad band random time history. It was also found that the effect of band limitation of input white noise on irregularity factors is negligibly small.

Early Detection of Sporadic Pancreatic Cancer

Science.gov (United States)

Kenner, Barbara J.; Chari, Suresh T.; Cleeter, Deborah F.; Go, Vay Liang W.

2015-01-01

Abstract Innovation leading to significant advances in research and subsequent translation to clinical practice is urgently necessary in early detection of sporadic pancreatic cancer. Addressing this need, the Early Detection of Sporadic Pancreatic Cancer Summit Conference was conducted by Kenner Family Research Fund in conjunction with the 2014 American Pancreatic Association and Japan Pancreas Society Meeting. International interdisciplinary scientific representatives engaged in strategic facilitated conversations based on distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. Ideas generated from the summit have led to the development of a Strategic Map for Innovation built upon 3 components: formation of an international collaborative effort, design of an actionable strategic plan, and implementation of operational standards, research priorities, and first-phase initiatives. Through invested and committed efforts of leading researchers and institutions, philanthropic partners, government agencies, and supportive business entities, this endeavor will change the future of the field and consequently the survival rate of those diagnosed with pancreatic cancer. PMID:25938853

Magnetic resonance spectroscopic abnormalities in sporadic and variant Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Pandya, H.G.; Coley, S.C.; Wilkinson, I.D.; Griffiths, P.D.

2003-01-01

AIM: To study the proton MR spectroscopic findings in Creutzfeldt-Jakob disease (CJD) (sporadic and variant). MATERIALS AND METHODS: MR imaging and proton MR spectra were acquired in two patients with sporadic CJD (biopsy proven) and one patient with variant CJD. RESULTS: The two patients with sporadic CJD demonstrated MR signal change within the basal ganglia and thalami and reduced N-acetylaspartate (NAA):creatine ratios. The patient with variant CJD showed characteristic signal change within the pulvinar of the thalami and a markedly reduced N-acetylaspartate:creatine ratio. CONCLUSION: All three patients with CJD demonstrated evidence of reduced N-acetylaspartate: creatine ratios on MR spectroscopy. These changes imply that neuronal loss and/or dysfunction is a consistent finding in established CJD. Pandya H. G., et al (2003) Clinical Radiology58, 148--153

Magnetic resonance spectroscopic abnormalities in sporadic and variant Creutzfeldt-Jakob disease

Energy Technology Data Exchange (ETDEWEB)

Pandya, H.G.; Coley, S.C.; Wilkinson, I.D.; Griffiths, P.D

2003-02-01

AIM: To study the proton MR spectroscopic findings in Creutzfeldt-Jakob disease (CJD) (sporadic and variant). MATERIALS AND METHODS: MR imaging and proton MR spectra were acquired in two patients with sporadic CJD (biopsy proven) and one patient with variant CJD. RESULTS: The two patients with sporadic CJD demonstrated MR signal change within the basal ganglia and thalami and reduced N-acetylaspartate (NAA):creatine ratios. The patient with variant CJD showed characteristic signal change within the pulvinar of the thalami and a markedly reduced N-acetylaspartate:creatine ratio. CONCLUSION: All three patients with CJD demonstrated evidence of reduced N-acetylaspartate: creatine ratios on MR spectroscopy. These changes imply that neuronal loss and/or dysfunction is a consistent finding in established CJD. Pandya H. G., et al (2003) Clinical Radiology58, 148--153.

Low and Mid-Latitude Ionospheric Irregularities Studies Using TEC and Radio Scintillation Data from the CITRIS Radio Beacon Receiver in Low-Earth-Orbit

Science.gov (United States)

Siefring, C. L.; Bernhardt, P. A.; Huba, J.; Krall, J.; Roddy, P. A.

2009-12-01

Unique data on ionospheric plasma irregularities from the Naval Research Laboratory (NRL) CITRIS (Scintillation and TEC Receiver in Space) instrument will be presented. CITRIS is a multi-band receiver that recorded TEC (Total Electron Content) and radio scintillations from Low-Earth Orbit (LEO) on STPSat1. The 555+/5 km altitude 35° inclination orbit covers low and mid-latitudes. The measurements require propagation from a transmitter to a receiver through the F-region plasma. CITRIS used both 1) satellite beacons in LEO, such as the NRL CERTO (Coherent Electromagnetic Radio TOmography) beacons and 2) the global network of ground-based DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) beacons. The TEC measurements allow for tracking of ionospheric disturbances and irregularities while the measurements of scintillations can simultaneously characterize their effects. CITRIS was operated in a complementary fashion with the C/NOFS (Communication/Navigations Outages Forecasting System) satellite during most of its first year of operations. C/NOFS carries a three-frequency 150/400/1067 MHz CERTO beacon and is dedicated to the study of Spread-F. In the case of Spread-F, ionospheric irregularities start with large scale size density gradients (100s of km) and cascade through complex processes to short scale sizes (10s of meters). It is typically the 100m-1km scale features that harm communication and navigation systems through scintillations. A multi-sensor approach is needed to completely understand this complex system, such as, the combination of CITRIS remote radio sensing and C/NOFS in-situ data. Several types of irregularities have been studied including Spread-F and the newly discovered dawn-side depletions. Comparisons with the physics based SAMI3 model are being performed to help our understanding of the morphology of the irregularities.

Cervical dystonia: about familial and sporadic cases in 88 patients

Directory of Open Access Journals (Sweden)

Carlos Henrique F. Camargo

2014-02-01

Full Text Available Cervical dystonia (CD affects the musculature of the neck in a focal way or associated to other parts of the body. The aim of this study was to identify clinical differences between patients with dystonia patients without family history and with family history (sporadic. Eighty-eight patients with CD were recruited in a Movement Disorders Clinic between June of 2008 and June of 2009. Only patients with no etiological diagnosis were accepted for analysis. The age of onset of symptoms was later in patients with focal and segmental dystonia than in patients with generalized dystonia (p<0.001. The severity of symptoms was higher in patients with sporadic dystonia than in familial patients (p<0.01. Generalized cases were more severe in patients with a family history (p<0.01. Sporadic patients had higher levels of pain than familial cases (p<0.05. We expect soon to present the results of genetic analyzes of these patients.

On irregularity strength of disjoint union of friendship graphs

Directory of Open Access Journals (Sweden)

Ali Ahmad

2013-11-01

Full Text Available We investigate the vertex total and edge total modication of the well-known irregularity strength of graphs. We have determined the exact values of the total vertex irregularity strength and the total edge irregularity strength of a disjoint union of friendship graphs.

New application of intelligent agents in sporadic amyotrophic lateral sclerosis identifies unexpected specific genetic background

Directory of Open Access Journals (Sweden)

Marocchi Alessandro

2008-05-01

Full Text Available Abstract Background Few genetic factors predisposing to the sporadic form of amyotrophic lateral sclerosis (ALS have been identified, but the pathology itself seems to be a true multifactorial disease in which complex interactions between environmental and genetic susceptibility factors take place. The purpose of this study was to approach genetic data with an innovative statistical method such as artificial neural networks to identify a possible genetic background predisposing to the disease. A DNA multiarray panel was applied to genotype more than 60 polymorphisms within 35 genes selected from pathways of lipid and homocysteine metabolism, regulation of blood pressure, coagulation, inflammation, cellular adhesion and matrix integrity, in 54 sporadic ALS patients and 208 controls. Advanced intelligent systems based on novel coupling of artificial neural networks and evolutionary algorithms have been applied. The results obtained have been compared with those derived from the use of standard neural networks and classical statistical analysis Results Advanced intelligent systems based on novel coupling of artificial neural networks and evolutionary algorithms have been applied. The results obtained have been compared with those derived from the use of standard neural networks and classical statistical analysis. An unexpected discovery of a strong genetic background in sporadic ALS using a DNA multiarray panel and analytical processing of the data with advanced artificial neural networks was found. The predictive accuracy obtained with Linear Discriminant Analysis and Standard Artificial Neural Networks ranged from 70% to 79% (average 75.31% and from 69.1 to 86.2% (average 76.6% respectively. The corresponding value obtained with Advanced Intelligent Systems reached an average of 96.0% (range 94.4 to 97.6%. This latter approach allowed the identification of seven genetic variants essential to differentiate cases from controls: apolipoprotein E arg

New application of intelligent agents in sporadic amyotrophic lateral sclerosis identifies unexpected specific genetic background.

Science.gov (United States)

Penco, Silvana; Buscema, Massimo; Patrosso, Maria Cristina; Marocchi, Alessandro; Grossi, Enzo

2008-05-30

Few genetic factors predisposing to the sporadic form of amyotrophic lateral sclerosis (ALS) have been identified, but the pathology itself seems to be a true multifactorial disease in which complex interactions between environmental and genetic susceptibility factors take place. The purpose of this study was to approach genetic data with an innovative statistical method such as artificial neural networks to identify a possible genetic background predisposing to the disease. A DNA multiarray panel was applied to genotype more than 60 polymorphisms within 35 genes selected from pathways of lipid and homocysteine metabolism, regulation of blood pressure, coagulation, inflammation, cellular adhesion and matrix integrity, in 54 sporadic ALS patients and 208 controls. Advanced intelligent systems based on novel coupling of artificial neural networks and evolutionary algorithms have been applied. The results obtained have been compared with those derived from the use of standard neural networks and classical statistical analysis Advanced intelligent systems based on novel coupling of artificial neural networks and evolutionary algorithms have been applied. The results obtained have been compared with those derived from the use of standard neural networks and classical statistical analysis. An unexpected discovery of a strong genetic background in sporadic ALS using a DNA multiarray panel and analytical processing of the data with advanced artificial neural networks was found. The predictive accuracy obtained with Linear Discriminant Analysis and Standard Artificial Neural Networks ranged from 70% to 79% (average 75.31%) and from 69.1 to 86.2% (average 76.6%) respectively. The corresponding value obtained with Advanced Intelligent Systems reached an average of 96.0% (range 94.4 to 97.6%). This latter approach allowed the identification of seven genetic variants essential to differentiate cases from controls: apolipoprotein E arg158cys; hepatic lipase -480 C/T; endothelial

Genetic Relatedness among Nontypeable Pneumococci Implicated in Sporadic Cases of Conjunctivitis

OpenAIRE

Barker, Jason H.; Musher, Daniel M.; Silberman, Ronald; Phan, Hoang M.; Watson, David A.

1999-01-01

Nontypeable Streptococcus pneumoniae is a common cause of epidemic conjunctivitis. A previous molecular fingerprinting study identified a clone of nontypeable pneumococcus that was responsible for a recent outbreak of conjunctivitis. In the present study, we examined the extent to which pneumococci that cause sporadic cases of conjunctivitis are related to this epidemic strain. Using arbitrarily primed BOX-PCR, we have determined that, of 10 nontypeable pneumococci causing sporadic conjunctiv...

Difference in aneurysm characteristics between patients with familial and sporadic aneurysmal subarachnoid haemorrhage

NARCIS (Netherlands)

Mensing, Liselore A.; Rinkel, Gabriel J E; Vlak, Monique H M; Van Der Schaaf, Irene C.; Ruigrok, Ynte M.

2016-01-01

Object Patients with familial intracranial aneurysms (IA) have a higher risk of rupture than patients with sporadic IA. We compared geometric and morphological risk factors for aneurysmal rupture between patients with familial and sporadic aneurysmal subarachnoid hemorrhage (aSAH) to analyse if

Apolipoprotein E in umbilical cord blood plasma

International Nuclear Information System (INIS)

Forte, T.M.; Davis, P.A.; Blum, C.B.

1983-01-01

Adolipoprotein E (apo E), with a molecular weight of approximately 37,000 daltons, is a minor apolipoprotein constituent in adult plasma lipoproteins. This apolipoprotein, like apolipoprotein B, is a ligand recognized by specific lipoprotein receptor sites (B-E receptors) on cell surfaces. We have recently shown that a pronounced apo E band appears in umbilical cord blood low-density (LDL) lipoproteins and also in high density (HDL) lipoproteins. Densitometric scans of Coomassie blue G-250 stained polyacrylamide gels suggested that apo E was probably elevated in cord blood lipoproteins. To pursue this suggestion, apo E in cord blood was quantitated by radioimmunoassay and correlated with cord blood lipid levels. In addition, apo E levels in 20 normal adult volunteers were also examined

Comparative study of the Ar and He atmospheric pressure plasmas on E-cadherin protein regulation for plasma-mediated transdermal drug delivery

Science.gov (United States)

Lee, Hyun Young; Hae Choi, Jeong; Hong, Jin Woo; Kim, Gyoo Cheon; Lee, Hae June

2018-05-01

The effects of argon plasma (ArP) and helium plasma (HeP) jets on E-cadherin protein function have been tested in order to choose the working gas for a better plasma-mediated transdermal drug delivery. The plasma-mediated changes of the E-cadherin function and the skin penetration efficacies of epidermal growth factor (EGF) were monitored in vitro using HaCaT human keratinocytes and in vivo using hairless mice. The ArP showed higher efficacy for E-cadherin regulation and EGF absorption than HeP under the same applied voltage and the same gas flow rate. The ArP generates higher volume power density, higher discharge current peak, and more reactive species than HeP, especially for OH with the same operating parameters. Moreover, the effect of ArP on E-cadherin function was blocked by the use of a grounded metal mesh. Taken together, this study presents the possibility that the synergetic effect of negative charges with radicals plays an important role in plasma-mediated E-cadherin regulation, which leads to enhanced transdermal drug delivery.

Abastecimento irregular de água, seu uso domiciliar e dengue: uma pesquisa biossocial no Nordeste do Brasil

OpenAIRE

Caprara, Andrea; Lima, José Wellington de Oliveira; Marinho, Alice Correia Pequeno; Calvasina, Paola Gondim; Landim, Lucyla Paes; Sommerfeld, Johannes

2009-01-01

Despite increased vector control efforts, dengue fever remains endemic in Fortaleza, Northeast Brazil, where sporadic epidemic outbreaks have occurred since 1986. Multiple factors affect vector ecology such as social policy, migration, urbanization, city water supply, garbage disposal and housing conditions, as well as community level understanding of the disease and related practices. This descriptive study used a multi-disciplinary approach that bridged anthropology and entomology. A multip...

Ultrasmooth plasma polymerized coatings for laser-fusion targets

International Nuclear Information System (INIS)

Letts, S.A.; Myers, D.W.; Witt, L.A.

1980-01-01

Coatings for laser fusion targets were deposited up to 135 μm thick by plasma polymerization onto 140 μm diameter DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 μm) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power, gas flow, and pressure, and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets

Molecular pathogenesis of sporadic prion diseases in man

Science.gov (United States)

Safar, Jiri G.

2012-01-01

The yeast, fungal and mammalian prions determine heritable and infectious traits that are encoded in alternative conformations of proteins. They cause lethal sporadic, familial and infectious neurodegenerative conditions in man, including Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), kuru, sporadic fatal insomnia (SFI) and likely variable protease-sensitive prionopathy (VPSPr). The most prevalent of human prion diseases is sporadic (s)CJD. Recent advances in amplification and detection of prions led to considerable optimism that early and possibly preclinical diagnosis and therapy might become a reality. Although several drugs have already been tested in small numbers of sCJD patients, there is no clear evidence of any agent’s efficacy. Therefore, it remains crucial to determine the full spectrum of sCJD prion strains and the conformational features in the pathogenic human prion protein governing replication of sCJD prions. Research in this direction is essential for the rational development of diagnostic as well as therapeutic strategies. Moreover, there is growing recognition that fundamental processes involved in human prion propagation – intercellular induction of protein misfolding and seeded aggregation of misfolded host proteins – are of far wider significance. This insight leads to new avenues of research in the ever-widening spectrum of age-related human neurodegenerative diseases that are caused by protein misfolding and that pose a major challenge for healthcare. PMID:22421210

Conflict Without Casualties: Non-Lethal Weapons in Irregular Warfare

Science.gov (United States)

2007-09-01

the body,” and the Geneva Protocol of 1925, bans the use of chemical and biological weapons .11 On 8 April 1975, President Ford issued Executive...E Funding – PE 63851M) (accessed 15 December 2006). The American Journal of Bioethics . “Medical Ethics and Non-Lethal Weapons .” Bioethics.net...CASUALTIES: NON-LETHAL WEAPONS IN IRREGULAR WARFARE by Richard L. Scott September 2007 Thesis Advisor: Robert McNab Second Reader

Wettability measurements of irregular shapes with Wilhelmy plate method

Science.gov (United States)

Park, Jaehyung; Pasaogullari, Ugur; Bonville, Leonard

2018-01-01

One of the most accurate methods for measuring the dynamic contact angle of liquids on solid surfaces is the Wilhelmy plate method. This method generally requires the use of rectangular samples having a constant perimeter in the liquid during advancing and receding cycles. A new formulation based on the Wilhelmy force balance equation to determine the contact angle for plate samples with irregular shapes has been developed. This method employs a profile plot obtained from an optical image to determine the perimeter (i.e. wetted length) of the sample as a function of the immersion depth. The raw force data measured by the force tensiometer is manipulated using the profile plot and the Wilhelmy equation to determine the wetting force and consequently advancing and the receding contact angle. This method is verified with both triangular and irregular PTFE samples in water, and measured contact angles are in good agreement with results from conventional regular shaped samples with a constant perimeter.

14 CFR 135.65 - Reporting mechanical irregularities.

Science.gov (United States)

2010-01-01

... irregularities and their correction. (b) The pilot in command shall enter or have entered in the aircraft maintenance log each mechanical irregularity that comes to the pilot's attention during flight time. Before each flight, the pilot in command shall, if the pilot does not already know, determine the status of...

Correção do astigmatismo irregular com lente intraocular tórica em um paciente com catarata e degeneração marginal pelúcida: relato de caso

Directory of Open Access Journals (Sweden)

Ana Luiza Biancardi

2012-12-01

Full Text Available A degeneração marginal pelúcida (DMP é uma rara ectasia corneana cuja progressão resulta em astigmatismo irregular e baixa visual não corrigidos com óculos ou lentes de contato. O presente relato descreve um paciente com catarata e DMP que foi tratado com facoemulsificação e implante de lente intraocular tórica com recuperação da acuidade visual em ambos os olhos.

A first comparison of irregularity and ion drift velocity measurements in the E-region

Directory of Open Access Journals (Sweden)

R. A. Makarevich

2006-09-01

Full Text Available E-region irregularity velocity measurements at large flow angles with the STARE Finland coherent VHF radar are considered in context of the ion and electron velocity data provided by the EISCAT tristatic radar system, CUTLASS Finland coherent HF radar, and IMAGE fluxgate magnetometers. The data have been collected during a special experiment on 27 March 2004 during which EISCAT was scanning between several E- and one F-region altitudes along the magnetic field line. Within the E-region, the EISCAT measurements at two altitudes of 110 and 115 km are considered while the electron velocity is inferred from the EISCAT ion velocity measurements at 278 km. The line-of-sight (l-o-s VHF velocity measured by STARE _{VHF los} is compared to the ion and electron velocity components (V_{i0 comp} and V_{e0 comp} along the STARE l-o-s direction. The comparison with V_{e0 comp} for the entire event shows that the measurements exhibit large scatter and small positive correlation. The correlation with V_{e0 comp} was substantial in the first half of the interval under study when V_{e0 comp} was larger in magnitude. The comparison with V_{i0 comp} at 110 and 115 km shows a considerable positive correlation, with VHF velocity being typically larger (smaller in magnitude than V_{i0 comp} at 110 km (115 km so that V_{VHF los} appears to be bounded by the ion velocity components at two altitudes. It is also demonstrated that the difference between V_{VHF los} and V_{i0 comp} at 110 km can be treated, in the first approximation, as a linear function of the effective backscatter height h_eff also counted from 110 km; h_eff varies in the range 108–114 km due to the altitude integration effects in the scattering cross-section. Our results are consistent with the notion that VHF

Plasma levels of apolipoprotein E and risk of dementia in the general population

DEFF Research Database (Denmark)

Rasmussen, Katrine L.; Tybjaerg-Hansen, Anne; Nordestgaard, Børge G

2015-01-01

OBJECTIVE: The apolipoprotein E (APOE) ε4 allele is a major genetic risk factor for Alzheimer disease and dementia. However, it remains unclear whether plasma levels of apoE confer additional risk. We tested this hypothesis. METHODS: Using 75,708 participants from the general population, we tested...... whether low plasma levels of apoE at study enrollment were associated with increased risk of future Alzheimer disease and all dementia, and whether this association was independent of ε2/ε3/ε4 APOE genotype. RESULTS: Multifactorially adjusted hazard ratios (HRs) for Alzheimer disease and all dementia...... adjustment for ε2/ε3/ε4 APOE genotype, plasma apoE tertiles remained associated with Alzheimer disease (p for trend = 0.007) and all dementia (p for trend = 0.04). Plasma apoE tertiles did not interact with ε2/ε3/ε4 APOE genotype on risk of Alzheimer disease (p = 0.53) or all dementia (p = 0...

Can the TLR-4-Mediated Signaling Pathway Be “A Key Inflammatory Promoter for Sporadic TAA”?

Directory of Open Access Journals (Sweden)

Giovanni Ruvolo

2014-01-01

Full Text Available Thoracic aorta shows with advancing age various changes and a progressive deterioration in structure and function. As a result, vascular remodeling (VR and medial degeneration (MD occur as pathological entities responsible principally for the sporadic TAA onset. Little is known about their genetic, molecular, and cellular mechanisms. Recent evidence is proposing the strong role of a chronic immune/inflammatory process in their evocation and progression. Thus, we evaluated the potential role of Toll like receptor- (TLR- 4-mediated signaling pathway and its polymorphisms in sporadic TAA. Genetic, immunohistochemical, and biochemical analyses were assessed. Interestingly, the rs4986790 TLR4 polymorphism confers a higher susceptibility for sporadic TAA (OR=14.4, P=0.0008 and it represents, together with rs1799752 ACE, rs3918242 MMP-9, and rs2285053 MMP-2 SNPs, an independent sporadic TAA risk factor. In consistency with these data, a significant association was observed between their combined risk genotype and sporadic TAA. Cases bearing this risk genotype showed higher systemic inflammatory mediator levels, significant inflammatory/immune infiltrate, a typical MD phenotype, lower telomere length, and positive correlations with histopatological abnormalities, hypertension, smoking, and ageing. Thus, TLR4 pathway should seem to have a key role in sporadic TAA. It might represent a potential useful tool for preventing and monitoring sporadic TAA and developing personalized treatments.

Orbital and Collisional Evolution of the Irregular Satellites

Science.gov (United States)

Nesvorný, David; Alvarellos, Jose L. A.; Dones, Luke; Levison, Harold F.

2003-07-01

The irregular moons of the Jovian planets are a puzzling part of the solar system inventory. Unlike regular satellites, the irregular moons revolve around planets at large distances in tilted and eccentric orbits. Their origin, which is intimately linked with the origin of the planets themselves, is yet to be explained. Here we report a study of the orbital and collisional evolution of the irregular satellites from times after their formation to the present epoch. The purpose of this study is to find out the features of the observed irregular moons that can be attributed to this evolution and separate them from signatures of the formation process. We numerically integrated ~60,000 test satellite orbits to map orbital locations that are stable on long time intervals. We found that the orbits highly inclined to the ecliptic are unstable due to the effect of the Kozai resonance, which radially stretches them so that satellites either escape from the Hill sphere, collide with massive inner moons, or impact the parent planet. We also found that prograde satellite orbits with large semimajor axes are unstable due to the effect of the evection resonance, which locks the orbit's apocenter to the apparent motion of the Sun around the parent planet. In such a resonance, the effect of solar tides on a resonant moon accumulates at each apocenter passage of the moon, which causes a radially outward drift of its orbital apocenter; once close to the Hill sphere, the moon escapes. By contrast, retrograde moons with large orbital semimajor axes are long-lived. We have developed an analytic model of the distant satellite orbits and used it to explain the results of our numerical experiments. In particular, we analytically studied the effect of the Kozai resonance. We numerically integrated the orbits of the 50 irregular moons (known by 2002 August 16) for 108 yr. All orbits were stable on this time interval and did not show any macroscopic variations that would indicate

Plasma flow measurements in the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) and comparison with B2.5-Eirene modeling

Science.gov (United States)

Kafle, N.; Owen, L. W.; Caneses, J. F.; Biewer, T. M.; Caughman, J. B. O.; Donovan, D. C.; Goulding, R. H.; Rapp, J.

2018-05-01

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory is a linear plasma device that combines a helicon plasma source with additional microwave and radio frequency heating to deliver high plasma heat and particle fluxes to a target. Double Langmuir probes and Thomson scattering are being used to measure local electron temperature and density at various radial and axial locations. A recently constructed Mach-double probe provides the added capability of simultaneously measuring electron temperatures ( T e), electron densities ( n e), and Mach numbers (M). With this diagnostic, it is possible to infer the plasma flow, particle flux, and heat flux at different locations along the plasma column in Proto-MPEX. Preliminary results show Mach numbers of 0.5 (towards the dump plate) and 1.0 (towards the target plate) downstream from the helicon source, and a stagnation point (no flow) near the source for the case where the peak magnetic field was 1.3 T. Measurements of particle flow and ne and Te profiles are discussed. The extensive coverage provided by these diagnostics permits data-constrained B2.5-Eirene modeling of the entire plasma column, and comparison with results of modeling in the high-density helicon plasmas will be presented.

On total irregularity strength of caterpillar graphs with two leaves on each internal vertex

Science.gov (United States)

Rosyida, I.; Widodo; Indriati, D.

2018-04-01

Let G(V, E) be a graph. A function f from V(G)\\cup E(G) to the set {1, 2, …, k} is said to be a totally irregular total k-labeling of G if the weights of any two different vertices x and y in V (G) satisfy {w}f(x)\

RNF43 is mutated less frequently in Lynch Syndrome compared with sporadic microsatellite unstable colorectal cancers.

Science.gov (United States)

Fennell, Lochlan J; Clendenning, Mark; McKeone, Diane M; Jamieson, Saara H; Balachandran, Samanthy; Borowsky, Jennifer; Liu, John; Kawamata, Futoshi; Bond, Catherine E; Rosty, Christophe; Burge, Matthew E; Buchanan, Daniel D; Leggett, Barbara A; Whitehall, Vicki L J

2018-01-01

The WNT signaling pathway is commonly altered during colorectal cancer development. The E3 ubiquitin ligase, RNF43, negatively regulates the WNT signal through increased ubiquitination and subsequent degradation of the Frizzled receptor. RNF43 has recently been reported to harbor frequent truncating frameshift mutations in sporadic microsatellite unstable (MSI) colorectal cancers. This study assesses the relative frequency of RNF43 mutations in hereditary colorectal cancers arising in the setting of Lynch syndrome. The entire coding region of RNF43 was Sanger sequenced in 24 colorectal cancers from 23 patients who either (i) carried a germline mutation in one of the DNA mismatch repair genes (MLH1, MSH6, MSH2, PMS2), or (ii) showed immunohistochemical loss of expression of one or more of the DNA mismatch repair proteins, was BRAF wild type at V600E, were under 60 years of age at diagnosis, and demonstrated no promoter region methylation for MLH1 in tumor DNA. A validation cohort of 44 colorectal cancers from mismatch repair germline mutation carriers from the Australasian Colorectal Cancer Family Registry (ACCFR) were sequenced for the most common truncating mutation hotspots (X117 and X659). RNF43 mutations were found in 9 of 24 (37.5%) Lynch syndrome colorectal cancers. The majority of mutations were frameshift deletions in the G659 G7 repeat tract (29%); 2 cancers (2/24, 8%) from the one patient harbored frameshift mutations at codon R117 (C6 repeat tract) within exon 3. In the ACCFR validation cohort, RNF43 hotspot mutations were identified in 19/44 (43.2%) of samples, which was not significantly different to the initial series. The proportion of mutant RNF43 in Lynch syndrome related colorectal cancers is significantly lower than the previously reported mutation rate found in sporadic MSI colorectal cancers. These findings identify further genetic differences between sporadic and hereditary colorectal cancers. This may be because Lynch Syndrome cancers

Geomagnetic storm effects on the occurrences of ionospheric irregularities over the African equatorial/low-latitude region

Science.gov (United States)

Amaechi, P. O.; Oyeyemi, E. O.; Akala, A. O.

2018-04-01

The study investigated the effects of intense geomagnetic storms of 2015 on the occurrences of large scale ionospheric irregularities over the African equatorial/low-latitude region. Four major/intense geomagnetic storms of 2015 were analyzed for this study. These storms occurred on 17th March 2015 (-229 nT), 22nd June 2015 (-204 nT), 7th October 2015 (-124 nT), and 20th December 2015 (-170 nT). Total Electron Content (TEC) data obtained from five African Global Navigation Satellite Systems (GNSS) stations, grouped into eastern and western sectors were used to derive the ionospheric irregularities proxy indices, e.g., rate of change of TEC (ROT), ROT index (ROTI) and ROTI daily average (ROTIAVE). These indices were characterized alongside with the disturbance storm time (Dst), the Y component of the Interplanetary Electric Field (IEFy), polar cap (PC) index and the H component of the Earth's magnetic field from ground-based magnetometers. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) and disturbance dynamo electric field (DDEF) modulated the behaviour of irregularities during the main and recovery phases of the geomagnetic storms. The effect of electric field over both sectors depends on the local time of southward turning of IMF Bz. Consequently, westward electric field inhibited irregularities during the main phase of March and October 2015 geomagnetic storms, while for the June 2015 storm, eastward electric field triggered weak irregularities over the eastern sector. The effect of electric field on irregularities during December 2015 storm was insignificant. During the recovery phase of the storms, westward DDEF suppressed irregularities.

Redefining periodic patterns on electroencephalograms of patients with sporadic Creutzfeldt-Jakob disease.

Science.gov (United States)

Shin, Jung-Won; Yim, Byeongsoo; Oh, Seung Hun; Kim, Nam Keun; Lee, Sang Kun; Kim, Ok-Joon

2017-05-01

We aimed to redefine various periodic patterns (PPs) observed on electroencephalography (EEG) in patients with sporadic Creutzfeldt-Jakob disease (sCJD) using the American Clinical Neurophysiology Society's (ACNS) Criteria. We analyzed EEG data of 23 patients with sCJD were admitted to two university hospitals between August 2005 and September 2015. We classified PPs on EEG data into three types: irregular periodic discharges (PDs) with superimposed rhythmic activities, appearing at a median of 8weeks after onset (w.a.o.); rhythmic sharp-and-wave, at a median of 11w.a.o.; and PDs with biphasic or triphasic morphology, at a median of 17w.a.o. Of 16 patients presenting with PPs, 14 had widespread lesions in both cortical and subcortical areas with clinical stage III at admission, and shorter time intervals for admission to hospital from disease onset than patients without PPs (Patients with PP, 11.6±12.2weeks; without PP, 18.2±8.3weeks; p=0.033). PPs largely presented as three types at different stages of disease progression, and patients who had PPs had more wide spread lesions and rapid disease progression. Our redefinition of PPs demonstrated on EEG using the ACNS criteria may contribute to further understanding of the pathological mechanisms of sCJD, and PPs might be a predictive factor of a rapid sCJD progression. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Ultrasmooth plasma polymerized coatings for laser fusion targets

International Nuclear Information System (INIS)

Letts, S.A.; Myers, D.W.; Witt, L.A.

1980-01-01

Coatings for laser fusion were deposited up to 135μm thick by plasma polymerization onto 140 μm diameter DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 μm) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power (20 watts), gas flow (0.3 sccm trans-2-butene, 10.0 sccm hydrogen), and pressure (75 millitorr), and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets

Some new features of electron density irregularities over SHAR during strong spread F

Directory of Open Access Journals (Sweden)

S. Raizada

Full Text Available An RH-560 rocket flight was conducted from Sriharikota rocket range (SHAR (14°N, 80°E, dip latitude 5.5°N to study electron density and electric field irregularities during spread F. The rocket was launched at 2130 local time (LT and it attained an apogee of 348 km. Results of electron density fluctuations are presented here. Two extremely sharp layers of very high electron density were observed at 105 and 130 km. The electron density increase in these layers was by a factor of 50 in a vertical extent of 10 km. Large depletions in electron density were observed around 175 and 238 km. Both sharp layers as well as depletions were observed also during the descent. The presence of sharp layers and depletions during the ascent and the descent of the rocket as well as an order of magnitude less electron density, in 150-300 km region during the descent, indicate the presence of strong large-scale horizontal gradients in the electron density. Some of the valley region irregularities (165-178 km, in the intermediate scale size range, observed during this flight, show spectral peaks at 2 km and can be interpreted in terms of the image striation theory suggested by Vickrey et al. The irregularities at 176 km do not exhibit any peak at kilometer scales and appear to be of new type. The growth rate of intermediate scale size irregularities, produced through generalized Rayleigh Taylor instability, was calculated for the 200-330 km altitude, using observed values of electron density gradients and an assumed vertically downward wind of 20 ms^-1. These growth rate calculations suggest that the observed irregularities could be produced by the gradient drift instability.

Key words: Ionosphere (equatorial ionosphere; ionospheric irregularities - Radio science (ionospheric physics

Some new features of electron density irregularities over SHAR during strong spread F

Directory of Open Access Journals (Sweden)

S. Raizada

2000-02-01

Full Text Available An RH-560 rocket flight was conducted from Sriharikota rocket range (SHAR (14°N, 80°E, dip latitude 5.5°N to study electron density and electric field irregularities during spread F. The rocket was launched at 2130 local time (LT and it attained an apogee of 348 km. Results of electron density fluctuations are presented here. Two extremely sharp layers of very high electron density were observed at 105 and 130 km. The electron density increase in these layers was by a factor of 50 in a vertical extent of 10 km. Large depletions in electron density were observed around 175 and 238 km. Both sharp layers as well as depletions were observed also during the descent. The presence of sharp layers and depletions during the ascent and the descent of the rocket as well as an order of magnitude less electron density, in 150-300 km region during the descent, indicate the presence of strong large-scale horizontal gradients in the electron density. Some of the valley region irregularities (165-178 km, in the intermediate scale size range, observed during this flight, show spectral peaks at 2 km and can be interpreted in terms of the image striation theory suggested by Vickrey et al. The irregularities at 176 km do not exhibit any peak at kilometer scales and appear to be of new type. The growth rate of intermediate scale size irregularities, produced through generalized Rayleigh Taylor instability, was calculated for the 200-330 km altitude, using observed values of electron density gradients and an assumed vertically downward wind of 20 ms-1. These growth rate calculations suggest that the observed irregularities could be produced by the gradient drift instability.Key words: Ionosphere (equatorial ionosphere; ionospheric irregularities - Radio science (ionospheric physics

Design Optimization of Irregular Cellular Structure for Additive Manufacturing

Science.gov (United States)

Song, Guo-Hua; Jing, Shi-Kai; Zhao, Fang-Lei; Wang, Ye-Dong; Xing, Hao; Zhou, Jing-Tao

2017-09-01

Irregularcellular structurehas great potential to be considered in light-weight design field. However, the research on optimizing irregular cellular structures has not yet been reporteddue to the difficulties in their modeling technology. Based on the variable density topology optimization theory, an efficient method for optimizing the topology of irregular cellular structures fabricated through additive manufacturing processes is proposed. The proposed method utilizes tangent circles to automatically generate the main outline of irregular cellular structure. The topological layoutof each cellstructure is optimized using the relative density informationobtained from the proposed modified SIMP method. A mapping relationship between cell structure and relative densityelement is builtto determine the diameter of each cell structure. The results show that the irregular cellular structure can be optimized with the proposed method. The results of simulation and experimental test are similar for irregular cellular structure, which indicate that the maximum deformation value obtained using the modified Solid Isotropic Microstructures with Penalization (SIMP) approach is lower 5.4×10-5 mm than that using the SIMP approach under the same under the same external load. The proposed research provides the instruction to design the other irregular cellular structure.

PRKAG3 polymorphisms associated with sporadic Wolff–Parkinson–White syndrome among a Taiwanese population

Directory of Open Access Journals (Sweden)

Ken-Pen Weng

2016-12-01

Conclusion: This study shows that PRKAG3-230 may be associated with sporadic WPW syndrome among a Taiwanese population. Further studies are warranted to elucidate the role of mutations in AMPK subunit genes other than PRKAG3-230 in sporadic WPW syndrome.

Case Studies in e-RPL and e-PR

Science.gov (United States)

Cameron, Roslyn; Miller, Allison

2014-01-01

The use of ePortfolios for recognition of prior learning (e-RPL) and for professional recognition (e-PR) is slowly gaining in popularity in the VET sector however their use is sporadic across educational sectors, disciplines, educational institutions and professions. Added to this is an array of purposes and types of e-RPL and e-PR models and…

An emerging role for misfolded wild-type SOD1 in sporadic ALS pathogenesis

Directory of Open Access Journals (Sweden)

Melissa S Rotunno

2013-12-01

Full Text Available Amyotrophic lateral sclerosis (ALS is a fatal neurodegenerative disorder that targets motor neurons, leading to paralysis and death within a few years of disease onset. While several genes have been linked to the inheritable, or familial, form of ALS, much less is known about the cause(s of sporadic ALS, which accounts for approximately 90% of ALS cases. Due to the clinical similarities between familial and sporadic ALS, it is plausible that both forms of the disease converge on a common pathway and, therefore, involve common factors. Recent evidence suggests the Cu,Zn-superoxide dismutase (SOD1 protein to be one such factor that is common to both sporadic and familial ALS. In 1993, mutations were uncovered in SOD1 that represent the first known genetic cause of familial ALS. While the exact mechanism of mutant-SOD1 toxicity is still not known today, most evidence points to a gain of toxic function that stems, at least in part, from the propensity of this protein to misfold. In the wild-type SOD1 protein, non-genetic perturbations such as metal depletion, disruption of the quaternary structure, and oxidation, can also induce SOD1 to misfold. In fact, these aforementioned post-translational modifications cause wild-type SOD1 to adopt a toxic conformation that is similar to familial ALS-linked SOD1 variants. These observations, together with the detection of misfolded wild-type SOD1 within human post-mortem sporadic ALS samples, have been used to support the controversial hypothesis that misfolded forms of wild-type SOD1 contribute to sporadic ALS pathogenesis. In this review, we present data from the literature that both support and contradict this hypothesis. We also discuss SOD1 as a potential therapeutic target for both familial and sporadic ALS.

Toxicological effects of irregularly shaped and spherical microplastics in a marine teleost, the sheepshead minnow (Cyprinodon variegatus).

Science.gov (United States)

Choi, Jin Soo; Jung, Youn-Joo; Hong, Nam-Hui; Hong, Sang Hee; Park, June-Woo

2018-04-01

The increasing global contamination of plastics in marine environments is raising public concerns about the potential hazards of microplastics to environmental and human health. Microplastics formed by the breakdown of larger plastics are typically irregular in shape. The objective of this study was to compare the effects of spherical or irregular shapes of microplastics on changes in organ distribution, swimming behaviors, gene expression, and enzyme activities in sheepshead minnow (Cyprinodon variegatus). Both types of microplastics accumulated in the digestive system, causing intestinal distention. However, when compared to spherical microplastics, irregular microplastics decreased swimming behavior (i.e., total distance travelled and maximum velocity) of sheepshead minnow. Both microplastics generated cellular reactive oxygen species (ROS), while ROS-related molecular changes (i.e., transcriptional and enzymatic characteristics) differed. This study provides toxicological insights into the impacts of environmentally relevant (fragmented) microplastics on fish and improves our understanding of the environmental effects of microplastics in the ecosystem. Copyright © 2018 Elsevier Ltd. All rights reserved.

The genetics of radiation-induced and sporadic osteosarcoma: a unifying theory?

International Nuclear Information System (INIS)

Rosemann, Michael; Kuosaite, Virginija; Nathrath, Michaela; Atkinson, Michael J.

2002-01-01

Cancer is a disease of the genome, with the neoplastic phenotype being passed from one cell generation to the other. Radiation-induced cancer has often been considered to represent a unique entity amongst neoplasia, with the energy deposition being held responsible for both direct (gene mutations) and indirect (bystander effects, induced instability etc) alterations to the cellular genome. However, radiogenic tumours in man and experimental animals appear to be physiologically and genetically indistinguishable from their sporadic counterparts, suggesting that the aetiologies of these two tumour types are in fact closely related. We have conducted a general screen of the genetic alterations in radiation-induced mouse osteosarcoma, a tumour that is histopathologically indistinguishable from human sporadic osteosarcoma. Comparison of the two tumour types indicates the existence of a common set of genetic changes, providing additional evidence to support the concept that the molecular pathology of radiation-induced malignancy is no different to that of sporadic cancers. (author)

Comparing Sporadic and Outbreak-associated Foodborne Illness

Centers for Disease Control (CDC) Podcasts

2016-11-04

Dr. Eric Ebel, a veterinarian and risk analyst with USDA’s Food Safety and Inspection Service, discusses his article on sporadic and outbreak-associated cases of foodborne illness.  Created: 11/4/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 11/4/2016.

Brain sonography in African infants with complicated sporadic ...

African Journals Online (AJOL)

Background: To determine the structural findings in brain sonography of African infants with complicated sporadic bacterial meningitis. Materials and Methods: Retrospective assessment of medical records of patients who underwent brain sonography on account of complicated bacterial meningitis. The brain sonography ...

Specific deficit of colour-colour short-term memory binding in sporadic and familial Alzheimer's disease.

Science.gov (United States)

Parra, Mario A; Sala, Sergio Della; Abrahams, Sharon; Logie, Robert H; Méndez, Luis Guillermo; Lopera, Francisco

2011-06-01

Short-term memory binding of visual features which are processed across different dimensions (shape-colour) is impaired in sporadic Alzheimer's disease, familial Alzheimer's disease, and in asymptomatic carriers of familial Alzheimer's disease. This study investigated whether Alzheimer's disease also impacts on within-dimension binding processes. The study specifically explored whether visual short-term memory binding of features of the same type (colour-colour) is sensitive to Alzheimer's disease. We used a neuropsychological battery and a short-term memory binding task to assess patients with sporadic Alzheimer's disease (Experiment 1), familial Alzheimer's disease (Experiment 2) due to the mutation E280A of the Presenilin-1 gene and asymptomatic carriers of the mutation. The binding task assessed change detection within arrays of unicoloured objects (Colour Only) or bicoloured objects the colours of which had to be remembered separately (Unbound Colours) or together (Bound Colours). Performance on the Bound Colours condition (1) explained the largest proportion of variance between patients (sporadic and familial Alzheimer's disease), (2) combined more sensitivity and specificity for the disease than other more traditional neuropsychological tasks, (3) identified asymptomatic carriers of the mutation even when traditional neuropsychological measures and other measures of short-term memory did not and, (4) contrary to shape-colour binding, correlated with measures of hippocampal functions. Colour-colour binding and shape-colour binding both appear to be sensitive to AD even though they seem to rely on different brain mechanisms. Copyright © 2011 Elsevier Ltd. All rights reserved.

The Effects of Muscle Mass on Homocyst(e)ine Levels in Plasma and Urine.

Science.gov (United States)

Malinow, M René; Lister, Craig L; DE Crée, Carl

The present study was designed to examine the relationship between homocyst(e)ine (H[e]) levels and muscle mass. Two experimental groups each of 24 Caucasian males, one consisting of higher-muscle mass subjects (HMM) and the other of lower-muscle mass subjects (LMM) participated in this study. Muscle mass was estimated from 24-hour urine collections of creatinine (Crt). Muscle mass was 40.3 ± 15.9 kg in HMM and 37.2 ± 11.4 kg in LMM (P= 0.002). Mean plasma H(e) levels in HMM were 10.29 ± 2.9 nmol/mL, and in LMM were 10.02 ± 2.4 nmol/L (Not significant, [NS]). Urinary H(e) levels (UH[e]) were 9.95 ± 4.3 nmol/mL and 9.22 ± 2.9 nmol/mL for HMM and LMM, respectively (NS). Plasma H(e) levels correlated well with UH(e) (HMM: r= 0.58, P= 0.009; LMM: r= 0.66, P= 0.004). Muscle mass and was not correlated to either plasma H(e) or UH(e). However, in HMM trends were identified for body mass to be correlated with UH(e) (r= 0.39, P= 0.10) and UCrt (r= 0.41, P= 0.08). Surprisingly, in HMM plasma and UCrt were only weakly correlated (r= 0.44, P= 0.06). Our results do not support a causal relationship between the amount of muscle mass and H(e) levels in plasma or urine.

Relation of plasma homocyst(e)ine to cerebral infarction and cerebral atherosclerosis.

Science.gov (United States)

Yoo, J H; Chung, C S; Kang, S S

1998-12-01

A number of investigations support the theory that the elevated plasma homocyst(e)ine is associated with occlusive vascular disease. The aim of this study is to examine whether moderate hyperhomocyst(e)inemia is an independent risk factor for cerebral infarction. In addition, we examined the association between plasma homocyst(e)ine and the severity of cerebral atherosclerosis. We conducted a hospital-based case-control study with 140 male controls and 78 male patients with nonfatal cerebral infarction, aged between 39 and 82 years. Plasma homocyst(e)ine levels were analyzed in 218 subjects. Fifty-five patients were evaluated for cerebral vascular stenosis by MR angiography. The mean plasma level of homocyst(e)ine was higher in cases than in controls (11.8+/-5.6 versus 9.6+/-4.1 micromol/L; P=0.002). The proportion of subjects with moderate hyperhomocyst(e)inemia was significantly higher in cases than in controls (16.7% versus 5.0%; P=0.004). Based on the logistic regression model, the odds ratio of the highest 5% of homocyst(e)ine levels in control group was 4.17 (95% confidence interval, 3.71 to 4. 71)(P=0.0001). After additional adjustment for total cholesterol, hypertension, smoking, diabetes, and age, the odds ratio was 1.70 (95% confidence interval, 1.48 to 1.95) (P=0.0001). The plasma homocyst(e)ine levels of patients having vessels with 3 or 2 stenosed sites were significantly higher than those of patients having vessels with 1 stenosed site or normal vessels (14.6+/-1.4, 11.0+/-1.4 versus 7.8+/-1.5, 8.9+/-1.4 micromol/L respectively; P<0. 02). Multiple logistic regression analysis revealed that moderate hyperhomocyst(e)ienemia was significantly associated with the number of stenosed vessels (P=0.001). These findings suggest that moderate hyperhomocyst(e)inemia is an independent risk factor for cerebral infarction and may predict the severity of cerebral atherosclerosis in patients with cerebral infarction.

Three male patients with sporadic acute hepatitis E in Sendai, Japan, who were domestically infected with hepatitis E virus of genotype III or IV.

Science.gov (United States)

Yamamoto, Takeshi; Suzuki, Hiroshi; Toyota, Takayoshi; Takahashi, Masaharu; Okamoto, Hiroaki

2004-01-01

Recent studies indicate that hepatitis E virus (HEV) infection occurs not only in developing countries but also in industrialized nations. However, the characteristics of domestic infections of hepatitis E in Japan are not fully understood. We analyzed serum samples from 34 patients who were seen at a city hospital in Sendai, Japan, between January 1997 and December 2002, and who had been given the diagnosis of sporadic acute hepatitis of non-A, non-B, non-C etiology. Among these 34 patients, 3 (9%; all men; aged 54, 59, and 61 years) were positive for both IgG and IgM anti-HEV antibodies and for HEV RNA. The HEV isolates (HE-JAS1 and HE-JAS3) obtained from case 1 and case 3, respectively, segregated into genotype III; they had the highest nucleotide sequence identity, of 99.5% and 99.0%, with HE-JA7 and HE-JA8, respectively, both of which had been isolated in Iwate, a neighboring prefecture of Sendai. In contrast, the remaining HEV isolate (HE-JAS2), obtained from case 2, segregated into genotype IV; it had the highest nucleotide sequence identity, of 99.8% and 99.3%, with JKK-Sap and HE-JA3, respectively, both of which had been isolated in Hokkaido, Japan, although case 2 had never been to Hokkaido. Our three patients with hepatitis E had not traveled abroad in the preceding 1 year, had had no contact with pigs, and no history of blood transfusion. These results indicate that HEV should be considered as an etiological agent of acute hepatitis of non-A, non-B, non-C etiology in Japan. The risk factor(s) for acquiring domestic HEV infection in Japan needs to be clarified in future studies.

Spheroidization of molybdenum powder by radio frequency thermal plasma

Science.gov (United States)

Liu, Xiao-ping; Wang, Kuai-she; Hu, Ping; Chen, Qiang; Volinsky, Alex A.

2015-11-01

To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency (RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in this paper. The effects of the carrier gas flow rate and molybdenum powder feeding rate on the shape and size of the final products were studied. The molybdenum powder morphology was examined using high-resolution scanning electron microscopy. The powder phases were analyzed by X-ray diffraction. The tap density and apparent density of the molybdenum powder were investigated using a Hall flow meter and a Scott volumeter. The optimal process parameters for the spherical molybdenum powder preparation are 50 g/min powder feeding rate and 0.6 m3/h carrier gas rate. In addition, pure spherical molybdenum powder can be obtained from irregular powder, and the tap density is enhanced after plasma processing. The average size is reduced from 72 to 62 µm, and the tap density is increased from 2.7 to 6.2 g/cm3. Therefore, RF plasma is a promising method for the preparation of high-density and high-purity spherical powders.

Left frontal hub connectivity delays cognitive impairment in autosomal-dominant and sporadic Alzheimer’s disease

Science.gov (United States)

Franzmeier, Nicolai; Düzel, Emrah; Jessen, Frank; Buerger, Katharina; Levin, Johannes; Duering, Marco; Dichgans, Martin; Haass, Christian; Suárez-Calvet, Marc; Fagan, Anne M; Paumier, Katrina; Benzinger, Tammie; Masters, Colin L; Morris, John C; Perneczky, Robert; Janowitz, Daniel; Catak, Cihan; Wolfsgruber, Steffen; Wagner, Michael; Teipel, Stefan; Kilimann, Ingo; Ramirez, Alfredo; Rossor, Martin; Jucker, Mathias; Chhatwal, Jasmeer; Spottke, Annika; Boecker, Henning; Brosseron, Frederic; Falkai, Peter; Fliessbach, Klaus; Heneka, Michael T; Laske, Christoph; Nestor, Peter; Peters, Oliver; Fuentes, Manuel; Menne, Felix; Priller, Josef; Spruth, Eike J; Franke, Christiana; Schneider, Anja; Kofler, Barbara; Westerteicher, Christine; Speck, Oliver; Wiltfang, Jens; Bartels, Claudia; Araque Caballero, Miguel Ángel; Metzger, Coraline; Bittner, Daniel; Weiner, Michael; Lee, Jae-Hong; Salloway, Stephen; Danek, Adrian; Goate, Alison; Schofield, Peter R; Bateman, Randall J; Ewers, Michael

2018-01-01

Abstract Patients with Alzheimer’s disease vary in their ability to sustain cognitive abilities in the presence of brain pathology. A major open question is which brain mechanisms may support higher reserve capacity, i.e. relatively high cognitive performance at a given level of Alzheimer’s pathology. Higher functional MRI-assessed functional connectivity of a hub in the left frontal cortex is a core candidate brain mechanism underlying reserve as it is associated with education (i.e. a protective factor often associated with higher reserve) and attenuated cognitive impairment in prodromal Alzheimer’s disease. However, no study has yet assessed whether such hub connectivity of the left frontal cortex supports reserve throughout the evolution of pathological brain changes in Alzheimer’s disease, including the presymptomatic stage when cognitive decline is subtle. To address this research gap, we obtained cross-sectional resting state functional MRI in 74 participants with autosomal dominant Alzheimer’s disease, 55 controls from the Dominantly Inherited Alzheimer’s Network and 75 amyloid-positive elderly participants, as well as 41 amyloid-negative cognitively normal elderly subjects from the German Center of Neurodegenerative Diseases multicentre study on biomarkers in sporadic Alzheimer’s disease. For each participant, global left frontal cortex connectivity was computed as the average resting state functional connectivity between the left frontal cortex (seed) and each voxel in the grey matter. As a marker of disease stage, we applied estimated years from symptom onset in autosomal dominantly inherited Alzheimer’s disease and cerebrospinal fluid tau levels in sporadic Alzheimer’s disease cases. In both autosomal dominant and sporadic Alzheimer’s disease patients, higher levels of left frontal cortex connectivity were correlated with greater education. For autosomal dominant Alzheimer’s disease, a significant left frontal cortex connectivity �

Irregular activity arises as a natural consequence of synaptic inhibition

International Nuclear Information System (INIS)

Terman, D.; Rubin, J. E.; Diekman, C. O.

2013-01-01

Irregular neuronal activity is observed in a variety of brain regions and states. This work illustrates a novel mechanism by which irregular activity naturally emerges in two-cell neuronal networks featuring coupling by synaptic inhibition. We introduce a one-dimensional map that captures the irregular activity occurring in our simulations of conductance-based differential equations and mathematically analyze the instability of fixed points corresponding to synchronous and antiphase spiking for this map. We find that the irregular solutions that arise exhibit expansion, contraction, and folding in phase space, as expected in chaotic dynamics. Our analysis shows that these features are produced from the interplay of synaptic inhibition with sodium, potassium, and leak currents in a conductance-based framework and provides precise conditions on parameters that ensure that irregular activity will occur. In particular, the temporal details of spiking dynamics must be present for a model to exhibit this irregularity mechanism and must be considered analytically to capture these effects

Irregular activity arises as a natural consequence of synaptic inhibition

Energy Technology Data Exchange (ETDEWEB)

Terman, D., E-mail: terman@math.ohio-state.edu [Department of Mathematics, The Ohio State University, Columbus, Ohio 43210 (United States); Rubin, J. E., E-mail: jonrubin@pitt.edu [Department of Mathematics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Diekman, C. O., E-mail: diekman@njit.edu [Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States)

2013-12-15

Irregular neuronal activity is observed in a variety of brain regions and states. This work illustrates a novel mechanism by which irregular activity naturally emerges in two-cell neuronal networks featuring coupling by synaptic inhibition. We introduce a one-dimensional map that captures the irregular activity occurring in our simulations of conductance-based differential equations and mathematically analyze the instability of fixed points corresponding to synchronous and antiphase spiking for this map. We find that the irregular solutions that arise exhibit expansion, contraction, and folding in phase space, as expected in chaotic dynamics. Our analysis shows that these features are produced from the interplay of synaptic inhibition with sodium, potassium, and leak currents in a conductance-based framework and provides precise conditions on parameters that ensure that irregular activity will occur. In particular, the temporal details of spiking dynamics must be present for a model to exhibit this irregularity mechanism and must be considered analytically to capture these effects.

Parallel Computing Strategies for Irregular Algorithms

Science.gov (United States)

Biswas, Rupak; Oliker, Leonid; Shan, Hongzhang; Biegel, Bryan (Technical Monitor)

2002-01-01

Parallel computing promises several orders of magnitude increase in our ability to solve realistic computationally-intensive problems, but relies on their efficient mapping and execution on large-scale multiprocessor architectures. Unfortunately, many important applications are irregular and dynamic in nature, making their effective parallel implementation a daunting task. Moreover, with the proliferation of parallel architectures and programming paradigms, the typical scientist is faced with a plethora of questions that must be answered in order to obtain an acceptable parallel implementation of the solution algorithm. In this paper, we consider three representative irregular applications: unstructured remeshing, sparse matrix computations, and N-body problems, and parallelize them using various popular programming paradigms on a wide spectrum of computer platforms ranging from state-of-the-art supercomputers to PC clusters. We present the underlying problems, the solution algorithms, and the parallel implementation strategies. Smart load-balancing, partitioning, and ordering techniques are used to enhance parallel performance. Overall results demonstrate the complexity of efficiently parallelizing irregular algorithms.

Advances in electron dosimetry of irregular fields; Avances en dosimetria de electrones de campos irregulares

Energy Technology Data Exchange (ETDEWEB)

Mendez V, J. [Departamento de Radioterapia, Instituto de Enfermedades Neoplasicas, Avenida Angamos Este 2520, Lima 34 (Peru)

1998-12-31

In this work it is presented an advance in Electron dosimetry of irregular fields for beams emitted by linear accelerators. At present diverse methods exist which are coming to apply in the Radiotherapy centers. In this work it is proposed a method for irregular fields dosimetry. It will be allow to calculate the dose rate absorbed required for evaluating the time for the treatment of cancer patients. Utilizing the results obtained by the dosimetric system, it has been possible to prove the validity of the method describe for 12 MeV energy and for square field 7.5 x 7.5 cm{sup 2} with percentile error less than 1 % . (Author)

Genetic overlap between apparently sporadic motor neuron diseases

NARCIS (Netherlands)

van Blitterswijk, Marka; Vlam, Lotte; van Es, Michael A.; van der Pol, W.-Ludo; Hennekam, Eric A. M.; Dooijes, Dennis; Schelhaas, Helenius J.; van der Kooi, Anneke J.; de Visser, Marianne; Veldink, Jan H.; van den Berg, Leonard H.

2012-01-01

Progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS) are devastating motor neuron diseases (MNDs), which result in muscle weakness and/or spasticity. We compared mutation frequencies in genes known to be associated with MNDs between patients with apparently sporadic PMA and

Plasma homocyst(e)ine concentrations in eclamptic and preeclamptic African women postpartum.

Science.gov (United States)

Rajkovic, A; Mahomed, K; Malinow, M R; Sorenson, T K; Woelk, G B; Williams, M A

1999-09-01

To examine the relationship between plasma homocyst(e)ine and risk of eclampsia and preeclampsia among sub-Saharan African women who delivered at Harare Maternity Hospital in Zimbabwe. We ran a hospital-based, case-control study at Harare Maternity Hospital, University of Zimbabwe, Harare, Zimbabwe comprising 33 pregnant women with eclampsia and 138 with preeclampsia. Controls were 185 normotensive pregnant women. Plasma was collected postpartum and homocyst(e)ine levels were measured by high-performance liquid chromatography and electrochemical detection. Women with eclampsia or preeclampsia had significantly higher mean homocyst(e)ine levels than normotensive controls (12.54 or 12.77 micromol/L versus 9.93 micromol/L, respectively, Pine distribution (median 13.9 micromol/L) compared with women in the lowest quartile (median 6.2 micromol/L). The corresponding OR for preeclampsia was 4.57. Nulliparas with elevated homocyst(e)ine had a 12.90 times higher risk of preeclampsia compared with multiparas without elevated homocyst(e)ine. Postpartum plasma homocyst(e)ine concentrations are higher among Zimbabwean women with eclampsia and preeclampsia compared with normotensive women.

Neuroendocrine Differentiation in Sporadic CRC and Hereditary Nonpolyosis Colorectal Cancer

Directory of Open Access Journals (Sweden)

M. H. Sun

2004-01-01

Full Text Available Extent neuroendocrine differentiation can be encountered in many human neoplasm derived from different organs and systems using immunohistochemistry and ultrastructural techniques. The tumor cells' behaviors resemble those of neurons and neuroendocrine cells. The presence of neuroendocrine differentiation reputedly appears to be associated with a poorer prognosis than the adenocarcinoma counterparts in sporadic human neoplasm. In this review the neuroendocrine carcinoma and the adenocarcinoma with neuroendocrine differentiation of colon and rectum both in sporadic colorectal carcinoma and the hereditary nonpolyposis colorectal cancer, the relationship of neuroendocrine differentiation and some possible molecular pathways in tumorogenesis of colorectal cancer will be discussed. Possible treatment strategy will also be addressed.

Early Detection of Sporadic Pancreatic Cancer

Science.gov (United States)

Chari, Suresh T.; Kelly, Kimberly; Hollingsworth, Michael A.; Thayer, Sarah P.; Ahlquist, David A.; Andersen, Dana K.; Batra, Surinder K.; Brentnall, Teresa A.; Canto, Marcia; Cleeter, Deborah F.; Firpo, Matthew A.; Gambhir, Sanjiv Sam; Go, Vay Liang W.; Hines, O. Joe; Kenner, Barbara J.; Klimstra, David S.; Lerch, Markus M.; Levy, Michael J.; Maitra, Anirban; Mulvihill, Sean J.; Petersen, Gloria M.; Rhim, Andrew D.; Simeone, Diane M.; Srivastava, Sudhir; Tanaka, Masao; Vinik, Aaron I.; Wong, David

2015-01-01

Abstract Pancreatic cancer (PC) is estimated to become the second leading cause of cancer death in the United States by 2020. Early detection is the key to improving survival in PC. Addressing this urgent need, the Kenner Family Research Fund conducted the inaugural Early Detection of Sporadic Pancreatic Cancer Summit Conference in 2014 in conjunction with the 45th Anniversary Meeting of the American Pancreatic Association and Japan Pancreas Society. This seminal convening of international representatives from science, practice, and clinical research was designed to facilitate challenging interdisciplinary conversations to generate innovative ideas leading to the creation of a defined collaborative strategic pathway for the future of the field. An in-depth summary of current efforts in the field, analysis of gaps in specific areas of expertise, and challenges that exist in early detection is presented within distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. In addition, an overview of efforts in familial PC is presented in an addendum to this article. It is clear from the summit deliberations that only strategically designed collaboration among investigators, institutions, and funders will lead to significant progress in early detection of sporadic PC. PMID:25931254

Genetic Relatedness among Nontypeable Pneumococci Implicated in Sporadic Cases of Conjunctivitis

Science.gov (United States)

Barker, Jason H.; Musher, Daniel M.; Silberman, Ronald; Phan, Hoang M.; Watson, David A.

1999-01-01

Nontypeable Streptococcus pneumoniae is a common cause of epidemic conjunctivitis. A previous molecular fingerprinting study identified a clone of nontypeable pneumococcus that was responsible for a recent outbreak of conjunctivitis. In the present study, we examined the extent to which pneumococci that cause sporadic cases of conjunctivitis are related to this epidemic strain. Using arbitrarily primed BOX-PCR, we have determined that, of 10 nontypeable pneumococci causing sporadic conjunctivitis, 5 were clonal and closely related to a previous outbreak strain, whereas 5 others were genetically diverse. PMID:10565927

Mutation analysis for DJ-1 in sporadic and familial parkinsonism: screening strategy in parkinsonism.

Science.gov (United States)

Tomiyama, Hiroyuki; Li, Yuanzhe; Yoshino, Hiroyo; Mizuno, Yoshikuni; Kubo, Shin-Ichiro; Toda, Tatsushi; Hattori, Nobutaka

2009-05-22

DJ-1 mutations cause autosomal recessive parkinsonism (ARP). Although some reports of DJ-1 mutations have been published, there is lack of information on the prevalence of these mutations in large-scale studies of both familial and sporadic parkinsonism. In this genetic screening study, we analyzed the distribution and frequency of DJ-1 mutations by direct nucleotide sequencing of coding exons and exon-intron boundaries of DJ-1, in 386 parkin-negative parkinsonism patients (371 index cases: 67 probands of autosomal recessive parkinsonism families, 90 probands of autosomal dominant parkinsonism families, 201 patients with sporadic parkinsonism, and 13 with unknown family histories) from 12 countries (Japan 283, China 27, Taiwan 22, Korea 22, Israel 16, Turkey 5, Philippines 2, Bulgaria 2, Greece 2, Tunisia 1, USA 2, Ukraine 1, unknown 1). None had causative mutation in DJ-1, suggesting DJ-1 mutation is very rare among patients with familial and sporadic parkinsonism from Asian countries and those with other ethnic background. This is in contrast to the higher frequencies and worldwide distribution of parkin- and PINK1-related parkinsonism in ARP and sporadic parkinsonism. Thus, after obtaining clinical information, screening for mutations in (1) parkin, (2) PINK1, (3) DJ-1, (4) ATP13A2 should be conducted in that order, in ARP and sporadic parkinsonism, based on their reported frequencies. In addition, haplotype analysis should be employed to check for homozygosity of 1p36, which harbors a cluster of causative genes for ARP such as DJ-1, PINK1 and ATP13A2 in ARP and sporadic parkinsonism, especially in parkinsonism with consanguinity.

Neuropathological and biochemical criteria to identify acquired Creutzfeldt-Jakob disease among presumed sporadic cases.

Science.gov (United States)

Kobayashi, Atsushi; Parchi, Piero; Yamada, Masahito; Mohri, Shirou; Kitamoto, Tetsuyuki

2016-06-01

As an experimental model of acquired Creutzfeldt-Jakob disease (CJD), we performed transmission studies of sporadic CJD using knock-in mice expressing human prion protein (PrP). In this model, the inoculation of the sporadic CJD strain V2 into animals homozygous for methionine at polymorphic codon 129 (129 M/M) of the PRNP gene produced quite distinctive neuropathological and biochemical features, that is, widespread kuru plaques and intermediate type abnormal PrP (PrP(Sc) ). Interestingly, this distinctive combination of molecular and pathological features has been, to date, observed in acquired CJD but not in sporadic CJD. Assuming that these distinctive phenotypic traits are specific for acquired CJD, we revisited the literature and found two cases showing widespread kuru plaques despite the 129 M/M genotype, in a neurosurgeon and in a patient with a medical history of neurosurgery without dura mater grafting. By Western blot analysis of brain homogenates, we revealed the intermediate type of PrP(Sc) in both cases. Furthermore, transmission properties of brain extracts from these two cases were indistinguishable from those of a subgroup of dura mater graft-associated iatrogenic CJD caused by infection with the sporadic CJD strain V2. These data strongly suggest that the two atypical CJD cases, previously thought to represent sporadic CJD, very likely acquired the disease through exposure to prion-contaminated brain tissues. Thus, we propose that the distinctive combination of 129 M/M genotype, kuru plaques, and intermediate type PrP(Sc) , represents a reliable criterion for the identification of acquired CJD cases among presumed sporadic cases. © 2015 Japanese Society of Neuropathology.

Radio images of the interplanetary turbulent plasma

International Nuclear Information System (INIS)

Vlasov, V.I.

1979-01-01

The results of the interplanetary scintillation daily observations of approximately 140 radio sources are given. The observations were carried out at the radiotelescope VLPA FIAN during 24 days in October-November 1975 and 6 days in April 1976. The maps (radio images) of interplanetary turbulent plasma are presented. The analysis of the maps reveals the presence of large-scale irregularities in the interplanetary plasma. The variability in large-scale structure of the interplanetary plasma is due mainly to transport of matter from the Sun. A comparison of the scintillation with the geomagnetic activity index detected the presence of a straight connection between them

Contribution of TARDBP mutations to sporadic amyotrophic lateral sclerosis.

Science.gov (United States)

Daoud, H; Valdmanis, P N; Kabashi, E; Dion, P; Dupré, N; Camu, W; Meininger, V; Rouleau, G A

2009-02-01

Mutations in the TARDBP gene, which encodes the TAR DNA binding protein (TDP-43), have been described in individuals with familial and sporadic amyotrophic lateral sclerosis (ALS). We screened the TARDBP gene in 285 French sporadic ALS patients to assess the frequency of TARDBP mutations in ALS. Six individuals had potentially deleterious mutations of which three were novel including a Y374X truncating mutation and P363A and A382P missense mutations. This suggests that TARDBP mutations may predispose to ALS in approximately 2% of the individuals followed in this study. Our findings, combined with those from other collections, brings the total number of mutations in unrelated ALS patients to 17, further suggesting that mutations in the TARDBP gene have an important role in the pathogenesis of ALS.

Prevalence of Abnormal Cervical Smears from Sporadic Screening ...

African Journals Online (AJOL)

The aim of the study was to find the prevalence of abnormal smears in an unscreened population of sexually active women attending a gynaecological clinic. “Pap” smears were taken sporadically for cytological examination from sexually active women attending gynaecological clinics at the Federal Medical Centre Gombe.

The postsunset vertical plasma drift during geomagnetic storms and its effects on the generation of equatorial spread F

Science.gov (United States)

Huang, C.

2017-12-01

We will present two distinct phenomena related to the postsunset vertical plasma drift and equatorial spread F (ESF) observed by the Communication/Navigation Outage Forecasting System satellite over six years. The first phenomenon is the behavior of the prereversal enhancement (PRE) of the vertical plasma drift during geomagnetic storms. Statistically, storm-time disturbance dynamo electric fields cause the PRE to decrease from 30 to 0 m/s when Dst changes from -60 to -100 nT, but the PRE does not show obvious variations when Dst varies from 0 to -60 nT. The observations show that the storm activities affect the evening equatorial ionosphere only for Dst correlated with the PRE and that the occurrence of small-amplitude ESF irregularities does not show a clear pattern at low solar activity but is anti-correlated with large-amplitude irregularities and the PRE at moderate solar activity. That is, the months and longitudes with high occurrence probability of large-amplitude irregularities are exactly those with low occurrence probability of small-amplitude irregularities, and vice versa. The generation of large-amplitude ESF irregularities is controlled by the PRE, and the generation of small-amplitude ESF irregularities may be caused by gravity waves and other disturbances, rather than by the PRE.

MAJOR MOLECULAR GENETIC DRIVERS IN SPORADIC PRIMARY HYPERPARATHYROIDISM.

Science.gov (United States)

Arnold, Andrew

2016-01-01

Primary hyperparathyroidism is primarily due to a solitary parathyroid adenoma but multi-gland disease, parathyroid carcinoma, and ectopic parathyroid hormone production can occur. Although primary hyperparathyroidism mostly presents sporadically, strong familial predispositions also exist. Much is known about heritable genetic mutations responsible for these syndromes, including multiple endocrine neoplasia types 1 and 2A, hyperparathyroidism-jaw tumor syndrome, and familial hypocalciuric hypercalcemia. Acquired mutations in common sporadic hyperparathyroidism have also been discovered. Here we focus on the most common and well-established genetic drivers: 1) involvement of the oncogene cyclin D1 in human neoplasia was first established in parathyroid adenomas, followed by recognition of its importance in other tumor types including breast cancer and B-lymphoid malignancy; and 2) somatic mutation of the MEN1 gene, first identified as the source of pathogenic germline mutations in patients with familial endocrinopathies, is found in a substantial fraction of non-familial parathyroid adenomas.

COL11A1 in FAP polyps and in sporadic colorectal tumors

International Nuclear Information System (INIS)

Fischer, Heléne; Salahshor, Sima; Stenling, Roger; Björk, Jan; Lindmark, Gudrun; Iselius, Lennart; Rubio, Carlos; Lindblom, Annika

2001-01-01

We previously reported that the α-1 chain of type 11 collagen (COL11A1), not normally expressed in the colon, was up-regulated in stromal fibroblasts in most sporadic colorectal carcinomas. Patients with germline mutations in the APC gene show, besides colonic polyposis, symptoms of stromal fibroblast involvement, which could be related to COL11A1 expression. Most colorectal carcinomas are suggested to be a result of an activated Wnt- pathway, most often involving an inactivation of the APC gene or activation of β-catenin. We used normal and polyp tissue samples from one FAP patient and a set of 37 sporadic colorectal carcinomas to find out if the up-regulation of COL11A1 was associated with an active APC/β-catenin pathway. In this study we found a statistically significant difference in COL11A1 expression between normal tissue and adenomas from one FAP patient, and all adenomas gave evidence for an active APC/β-catenin pathway. An active Wnt pathway has been suggested to involve stromal expression of WISP-1. We found a strong correlation between WISP-1 and COL11A1 expression in sporadic carcinomas. Our results suggest that expression of COL11A1 in colorectal tumors could be associated with the APC/β-catenin pathway in FAP and sporadic colorectal cancer

Clinicopathologic factors identify sporadic mismatch repair-defective colon cancers

DEFF Research Database (Denmark)

Halvarsson, Britta; Anderson, Harald; Domanska, Katarina

2008-01-01

Identification of sporadic mismatch repair (MMR)-defective colon cancers is increasingly demanded for decisions on adjuvant therapies. We evaluated clinicopathologic factors for the identification of these prognostically favorable tumors. Histopathologic features in 238 consecutive colon cancers...

Spherical and irregular aberrations are important for the optimal performance of the human eye

NARCIS (Netherlands)

Nio, YK; Jansonius, NM; Fidler, [No Value; Geraghty, E; Norrby, S; Kooijman, AC

Contrast sensitivity measured psychophysically at different levels of defocus can be used to evaluate the eye optics. Possible parameters of spherical and irregular aberrations, e.g, relative modulation transfer (RMT), myopic shift, and depth of focus, can be determined from these measurements. The

The effect of high intensity laser propagation instabilities on channel formation in underdense plasmas

International Nuclear Information System (INIS)

Najmudin, Z.; Krushelnick, K.; Tatarakis, M.; Clark, E.L.; Danson, C.N.; Malka, V.; Neely, D.; Santala, M.I.K.; Dangor, A.E.

2003-01-01

Experiments have been performed using high power laser pulses (up to 50 TW) focused into underdense helium plasmas (n e ≤5x10 19 cm -3 ). Using shadowgraphy, it is observed that the laser pulse can produce irregular density channels, which exhibit features such as long wavelength hosing and 'sausage-like' self-focusing instabilities. This phenomenon is a high intensity effect and the characteristic period of oscillation of these instabilities is typically found to correspond to the time required for ions to move radially out of the region of highest intensity

E x B shearing rate in quasi-symmetric plasmas

International Nuclear Information System (INIS)

Hahm, T.S.

1997-01-01

The suppression of turbulence by the E x B shear is studied in systems with quasi-symmetry using the nonlinear analysis of eddy decorrelation previously utilized in finite aspect ratio tokamak plasmas. The analytically derived E x B shearing rate which contains the relevant geometric dependence can be used for quantitative assessment of the fluctuation suppression in stellarators with quasi-symmetry

State reconstruction and irregular wavefunctions for the hydrogen atom

Science.gov (United States)

Krähmer, D. S.; Leonhardt, U.

1997-07-01

Inspired by a recently proposed procedure by Leonhardt and Raymer for wavepacket reconstruction, we calculate the irregular wavefunctions for the bound states of the Coulomb potential. We select the irregular solutions which have the simplest semiclassical limit.

The Impact of Irregular Warfare on the US Army

National Research Council Canada - National Science Library

McDonald, III, Roger L

2006-01-01

Although the U.S. Army has yet to clearly define irregular warfare, it is imperative that the Army take near-term action to enhance the ability of Soldiers and units to operate effectively in an irregular warfare environment...

Coaxial Plasma Gun Development for the ARPA-E PLX- α Project

Science.gov (United States)

Witherspoon, F. Douglas; Case, Andrew; Brockington, Samuel

2015-11-01

We describe the renewed effort to design and build coaxial plasma guns appropriate for a scaling study of spherically imploding plasma liners as a standoff magneto-inertial-fusion driver under the ARPA-E Accelerating Low-Cost Plasma Heating And Assembly (ALPHA) program. HyperV joins LANL, UAH, UNM, BNL, and Tech-X to develop, build, operate and analyze a 60 plasma gun experiment using the existing PLX facility at LANL. The guns will be designed to operate over a scaling range of operating parameters: 0.5-5.0 mg of Ar, Ne, N2, Kr, and Xe; 20-60 km/s; 1016 -1017 cm-3 muzzle density; and up to 7.5 kJ stored energy per gun. Each gun is planned to incorporate contoured gaps, fast dense gas injection and triggering, and innovative integral sparkgap switching and pfn configurations to reduce inductance, cost, and complexity, and to increase efficiency and system reliability. We will describe the overall design approach for the guns and pulsed power systems. This work supported by the ARPA-E ALPHA Program.

Influence of initial stress, irregularity and heterogeneity on Love-type wave propagation in double pre-stressed irregular layers lying over a pre-stressed half-space

Science.gov (United States)

Singh, Abhishek Kumar; Das, Amrita; Parween, Zeenat; Chattopadhyay, Amares

2015-10-01

The present paper deals with the propagation of Love-type wave in an initially stressed irregular vertically heterogeneous layer lying over an initially stressed isotropic layer and an initially stressed isotropic half-space. Two different types of irregularities, viz., rectangular and parabolic, are considered at the interface of uppermost initially stressed heterogeneous layer and intermediate initially stressed isotropic layer. Dispersion equations are obtained in closed form for both cases of irregularities, distinctly. The effect of size and shape of irregularity, horizontal compressive initial stress, horizontal tensile initial stress, heterogeneity of the uppermost layer and width ratio of the layers on phase velocity of Love-type wave are the major highlights of the study. Comparative study has been made to identify the effects of different shapes of irregularity, presence of heterogeneity and initial stresses. Numerical computations have been carried out and depicted by means of graphs for the present study.

Updated clinical diagnostic criteria for sporadic Creutzfeldt-Jakob disease

NARCIS (Netherlands)

I. Zerr; K. Kallenberg; D.M. Summers; C. Romero; A. Taratuto; U. Heinemann; M. Breithaupt; D. Varges; B. Meissner; A. Ladogana (Anna); M. Schuur (Maaike); S. Haik; S.J. Collins (Steven); G.H. Jansen (Gerard); G.B. Stokin; J. Pimentel; E. Hewer; D. Collie; P. Smith; H. Roberts; J.P. Brandel; P. Tikka-Kleemola (Päivi); M. Pocchiari (Maurizio); C. Begue; P. Cras (Patrick); R.G. Will; P. Sanchez-Juan (Pascual)

2009-01-01

textabstractSeveral molecular subtypes of sporadic Creutzfeldt-Jakob disease have been identified and electroencephalogram and cerebrospinal fluid biomarkers have been reported to support clinical diagnosis but with variable utility according to subtype. In recent years, a series of publications

Sporadic E S Layers at High Latitudes During a Magnetic Storm of March 17, 2015 According to the Vertical and Oblique Ionospheric Sounding Data

Science.gov (United States)

Blagoveshchensky, D. V.; Maltseva, O. A.; Anishin, M. M.; Rogov, D. D.

2017-11-01

We consider the behavior of the parameters of the ionospheric E s layers according to the vertical sounding at the Sodankylä observatory and oblique sounding at the Lovozero (Murmansk region)—Gor'kovskaya station (Leningrad region) path during a superstorm of March 17, 2015. Temporal and spatial behavior of these parameters is compared. It was found that the storm significantly distorted the normal course of variations of the sporadic E s layer characteristics. Specific behavior of the layers during a storm at points separated by about 300 km was detected. With the help of ray tracing calculations using the IRI model, oblique sounding ionograms were constructed for the radio path analyzed. Primary attention is given to the maximum usable frequency of the F 2 layer—MUF- F 2. Additionally, for the disturbed conditions where there is only a high-power E s layer on the experimental ionograms, the values of MUF- E s and the ratio K =MUF- E s/ f o E s for various cutoff frequencies f o E s of the E s layer and its altitudes {h}_{E_s} are calculated within the framework of the well-known approximations. Calculations for the case of weak disturbance and semitransparent E s layers are carried out with the IRI model adapted to the current diagnostics parameters. It was found that the calculated and experimental values of MUF- F 2 are close to each other or coincide, while this cannot be said about MUF- E s. The calculated and experimental values of MUF- E s can be matched in the model of mirror reflection from a flat layer for intense layers and the model of the E layer for thick E s layers of low intensity.

Influence of Ionospheric Irregularities on GNSS Remote Sensing

Directory of Open Access Journals (Sweden)

M. V. Tinin

2015-01-01

Full Text Available We have used numerical simulation to study the effects of ionospheric irregularities on accuracy of global navigation satellite system (GNSS measurements, using ionosphere-free (in atmospheric research and geometry-free (in ionospheric research dual-frequency phase combinations. It is known that elimination of these effects from multifrequency GNSS measurements is handi-capped by diffraction effects during signal propagation through turbulent ionospheric plasma with the inner scale being smaller than the Fresnel radius. We demonstrated the possibility of reducing the residual ionospheric error in dual-frequency GNSS remote sensing in ionosphere-free combination by Fresnel inversion. The inversion parameter, the distance to the virtual screen, may be selected from the minimum of amplitude fluctuations. This suggests the possibility of improving the accuracy of GNSS remote sensing in meteorology. In the study of ionospheric disturbances with the aid of geometry-free combination, the Fresnel inversion eliminates only the third-order error. To eliminate the random TEC component which, like the measured average TEC, is the first-order correction, we should use temporal filtering (averaging.

Short-term folic acid supplementation induces variable and paradoxical changes in plasma homocyst(e)ine concentrations.

Science.gov (United States)

Malinow, M R; Duell, P B; Williams, M A; Kruger, W D; Evans, A A; Anderson, P H; Block, P C; Hess, D L; Upson, B M; Graf, E E; Irvin-Jones, A; Wang, L

2001-01-01

Folic acid is presently the mainstay of treatment for most subjects with elevated plasma homocyst(e)ine concentrations [Plasma or serum homocyst(e)ine, or total homocysteine, refers to the sum of the sulfhydryl amino acid homocysteine and the homocysteinyl moieties of the disulfides homocystine and homocystein-cysteine, whether free or bound to plasma proteins.] Changes in homocyst(e)ine in response to folic acid supplementation are characterized by considerable interindividual variation. The purpose of this study was to identify factors that contribute to heterogeneity in short-term responses to folic acid supplementation. The effects of folic acid supplementation (1 or 2 mg per day) for 3 wk on plasma homocyst(e)ine concentrations were assessed in 304 men and women. Overall, folic acid supplementation increased mean plasma folate 31.5 +/- 98.0 nmol/L and decreased mean plasma homocyst(e)ine concentrations 1.2 +/- 2.4 micromol/L. There was evidence of substantial interindividual variation in the homocyst(e)ine response from -18.5 to +7.1 micromol/L, including an increase in homocyst(e)ine in 20% of subjects (mean increase 1.5 +/- 1.4 micromol/L). Basal homocyst(e)ine, age, male gender, cigarette smoking, use of multivitamins, methylene tetrahydrofolate reductase, and cystathionine beta-synthase polymorphisms accounted for 47.6% of the interindividual variability in the change in homocyst(e)ine after folic acid supplementation, but about 50% of variability in response to folic acid was not explained by the variables we studied.

Imaging movement-related activity in medicated Parkin-associated and sporadic Parkinson's disease

DEFF Research Database (Denmark)

van Eimeren, Thilo; Binkofski, Ferdinand; Buhmann, Carsten

2010-01-01

Treatment-related motor complications such as dyskinesias are a major problem in the long-term management of Parkinson's disease (PD). In sporadic PD, a relatively early onset of the disease is known to be associated with an early development of dyskinesias. Although linked with early onset...... selected movements. Patients with Parkin-associated and sporadic PD showed no difference in movement-related activation patterns. Moreover, the covariates 'age' and 'disease duration' similarly influenced brain activation in both patient groups. The present finding suggests that a stable long-term motor...

Evaluation of statistical methods for quantifying fractal scaling in water-quality time series with irregular sampling

Science.gov (United States)

Zhang, Qian; Harman, Ciaran J.; Kirchner, James W.

2018-02-01

River water-quality time series often exhibit fractal scaling, which here refers to autocorrelation that decays as a power law over some range of scales. Fractal scaling presents challenges to the identification of deterministic trends because (1) fractal scaling has the potential to lead to false inference about the statistical significance of trends and (2) the abundance of irregularly spaced data in water-quality monitoring networks complicates efforts to quantify fractal scaling. Traditional methods for estimating fractal scaling - in the form of spectral slope (β) or other equivalent scaling parameters (e.g., Hurst exponent) - are generally inapplicable to irregularly sampled data. Here we consider two types of estimation approaches for irregularly sampled data and evaluate their performance using synthetic time series. These time series were generated such that (1) they exhibit a wide range of prescribed fractal scaling behaviors, ranging from white noise (β = 0) to Brown noise (β = 2) and (2) their sampling gap intervals mimic the sampling irregularity (as quantified by both the skewness and mean of gap-interval lengths) in real water-quality data. The results suggest that none of the existing methods fully account for the effects of sampling irregularity on β estimation. First, the results illustrate the danger of using interpolation for gap filling when examining autocorrelation, as the interpolation methods consistently underestimate or overestimate β under a wide range of prescribed β values and gap distributions. Second, the widely used Lomb-Scargle spectral method also consistently underestimates β. A previously published modified form, using only the lowest 5 % of the frequencies for spectral slope estimation, has very poor precision, although the overall bias is small. Third, a recent wavelet-based method, coupled with an aliasing filter, generally has the smallest bias and root-mean-squared error among all methods for a wide range of

Software support for irregular and loosely synchronous problems

Science.gov (United States)

Choudhary, A.; Fox, G.; Hiranandani, S.; Kennedy, K.; Koelbel, C.; Ranka, S.; Saltz, J.

1992-01-01

A large class of scientific and engineering applications may be classified as irregular and loosely synchronous from the perspective of parallel processing. We present a partial classification of such problems. This classification has motivated us to enhance FORTRAN D to provide language support for irregular, loosely synchronous problems. We present techniques for parallelization of such problems in the context of FORTRAN D.

Irregular Shaped Building Design Optimization with Building Information Modelling

Directory of Open Access Journals (Sweden)

Lee Xia Sheng

2016-01-01

Full Text Available This research is to recognise the function of Building Information Modelling (BIM in design optimization for irregular shaped buildings. The study focuses on a conceptual irregular shaped “twisted” building design similar to some existing sculpture-like architectures. Form and function are the two most important aspects of new buildings, which are becoming more sophisticated as parts of equally sophisticated “systems” that we are living in. Nowadays, it is common to have irregular shaped or sculpture-like buildings which are very different when compared to regular buildings. Construction industry stakeholders are facing stiff challenges in many aspects such as buildability, cost effectiveness, delivery time and facility management when dealing with irregular shaped building projects. Building Information Modelling (BIM is being utilized to enable architects, engineers and constructors to gain improved visualization for irregular shaped buildings; this has a purpose of identifying critical issues before initiating physical construction work. In this study, three variations of design options differing in rotating angle: 30 degrees, 60 degrees and 90 degrees are created to conduct quantifiable comparisons. Discussions are focused on three major aspects including structural planning, usable building space, and structural constructability. This research concludes that Building Information Modelling is instrumental in facilitating design optimization for irregular shaped building. In the process of comparing different design variations, instead of just giving “yes or no” type of response, stakeholders can now easily visualize, evaluate and decide to achieve the right balance based on their own criteria. Therefore, construction project stakeholders are empowered with superior evaluation and decision making capability.

Conceptual study of lower hybrid frequency heating of the J.E.T. plasma

International Nuclear Information System (INIS)

Tonon, G.; Bernard, M.; Brambilla, M.

1981-04-01

The aim of this report is to bring up the conclusions of the conceptual study of the J.E.T. plasma heating by lower hybrid waves. While giving an overall view of potential use for lower hybrid heating (LHH) in the J.E.T. plasma, this study deals more specificaly with the following concerns: up-to-date status of LHH theory and experiment; the physics of LHH on J.E.T.: RF requirements and expected results from numerical computations; the J.E.T. LHH coupling structure; the 10 MW RF generator; the associated RF diagnostics; the time schedule and the cost estimates

Application of quantitative DTI metrics in sporadic CJD

Directory of Open Access Journals (Sweden)

E. Caverzasi

2014-01-01

Full Text Available Diffusion Weighted Imaging is extremely important for the diagnosis of probable sporadic Jakob–Creutzfeldt disease, the most common human prion disease. Although visual assessment of DWI MRI is critical diagnostically, a more objective, quantifiable approach might more precisely identify the precise pattern of brain involvement. Furthermore, a quantitative, systematic tracking of MRI changes occurring over time might provide insights regarding the underlying histopathological mechanisms of human prion disease and provide information useful for clinical trials. The purposes of this study were: 1 to describe quantitatively the average cross-sectional pattern of reduced mean diffusivity, fractional anisotropy, atrophy and T1 relaxation in the gray matter (GM in sporadic Jakob–Creutzfeldt disease, 2 to study changes in mean diffusivity and atrophy over time and 3 to explore their relationship with clinical scales. Twenty-six sporadic Jakob–Creutzfeldt disease and nine control subjects had MRIs on the same scanner; seven sCJD subjects had a second scan after approximately two months. Cortical and subcortical gray matter regions were parcellated with Freesurfer. Average cortical thickness (or subcortical volume, T1-relaxiation and mean diffusivity from co-registered diffusion maps were calculated in each region for each subject. Quantitatively on cross-sectional analysis, certain brain regions were preferentially affected by reduced mean diffusivity (parietal, temporal lobes, posterior cingulate, thalamus and deep nuclei, but with relative sparing of the frontal and occipital lobes. Serial imaging, surprisingly showed that mean diffusivity did not have a linear or unidirectional reduction over time, but tended to decrease initially and then reverse and increase towards normalization. Furthermore, there was a strong correlation between worsening of patient clinical function (based on modified Barthel score and increasing mean diffusivity.

Observation of total electron content and irregularities in electron density using GHz band radiowaves emitted from satellite

International Nuclear Information System (INIS)

Ogawa, Tadahiko; Fujita, Masaharu; Awaka, Jun.

1978-01-01

The experiments to investigate the influence of troposphere on millimeter and sub-millimeter wave propagation were carried out, using the engineering test satellite -- 2 (ETS-2) which became the Japanese first stationary satellite and carries the transmitter emitting beacon waves of 1.7, 11.5 and 34.5 GHz coherent each other. By these experiments, it was found that the waves of 1.7 and 11.5 GHz were affected by the ionosphere. The measurement of total electron content using GHz band waves was the first trial in the world, and is capable of grasping its change with higher accuracy than conventional methods. Scintillation of 1.7 GHz is mainly the phenomenon during night, and it was revealed that it has a peak at 22.30 local time and occurred through the radiowave scattering owing to the irregularities of the ionosphere. It is also suggested that some plasma instability is generated in the place where electron density gradient in the ionosphere is large, and the irregularities of fine scale are produced, assuming from GHz band scintillations at the time of magnetic storm. The relations among wave number spectrum, scintillation frequency spectrum and S4 index (statistical quantity to give estimate for scintillation amplitude) can be derived by the weak scattering theory (Simple scattering theory). As seen above, the diagnosis of plasma disturbances in the ionosphere is feasible by the simultaneous observations of total electron content and scintillation. (Wakatsuki, Y.)

Elevated levels of plasma homocyst(e)ine and asymmetric dimethylarginine in elderly patients with stroke.

Science.gov (United States)

Yoo, J H; Lee, S C

2001-10-01

Cerebrovascular risk factors, including hypertension, smoking, diabetes mellitus, aging, dyslipidemia, and hyperhomocyst(e)inemia are linked to endothelial dysfunction. Endothelial-derived nitric oxide (NO) has inhibitory effects on key processes in atherothrombosis. Although asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase, is associated with atherosclerotic disease, there has been no report on association of ADMA with ischemic stroke. Here we investigated the relation of plasma ADMA, stroke, and homocyst(e)inemia in the elderly. Plasma ADMA and homocyst(e)ine concentration was determined using high-performance liquid chromatography and fluorescence detection. Patients with ischemic stroke had significantly higher concentrations of plasma ADMA than controls (1.85+/-1.32 vs. 0.93+/-0.32 micromol/l, P=0.0001). After adjustment for risk factors, elevated ADMA levels, above 90th percentile of normal controls (> or =1.43 micromol/l) was associated with stroke (OR=6.05, 95% CI; 2.77-13.3, P=0.02). ADMA plasma levels were positively correlated to homocyst(e)ine levels (r=0.43, P=0.01). Multiple logistic regression analysis revealed that hyperhomocyst(e)inemia (plasma homocyst(e)ine concentration > or =15.0 micromol/l) was a significant predictor of elevated ADMA level. Altogether, findings indicate that elevated ADMA concentrations are at increased risk for ischemic stroke in the elderly, and may account for increased risk of stroke in patients with hyperhomocyst(e)inemia.

Transmission of sporadic Creutzfeldt-Jakob disease by blood transfusion: risk factor or possible biases.

Science.gov (United States)

Puopolo, Maria; Ladogana, Anna; Vetrugno, Vito; Pocchiari, Maurizio

2011-07-01

The occurrence of transfusion transmissions of variant Creutzfeldt-Jakob disease (CJD) cases has reawakened attention to the possible similar risk posed by other forms of CJD. CJD with a definite or probable diagnosis (sporadic CJD, n = 741; genetic CJD, n = 175) and no-CJD patients with definite alternative diagnosis (n = 482) with available blood transfusion history were included in the study. The risk of exposure to blood transfusion occurring more than 10 years before disease onset and for some possible confounding factors was evaluated by calculating crude odds ratios (ORs). Variables with significant ORs in univariate analyses were included in multivariate logistic regression analyses. In the univariate model, blood transfusion occurring more than 10 years before clinical onset is 4.1-fold more frequent in sporadic CJD than in other neurologic disorders. This significance is lost when the 10-year lag time was not considered. Multivariate analyses show that the risk of developing sporadic CJD after transfusion increases (OR, 5.05) after adjusting for possible confounding factors. Analysis conducted on patients with genetic CJD did not reveal any significant risk factor associated with transfusion. This is the first case-control study showing a significant risk of transfusion occurring more than 10 years before clinical onset in sporadic CJD patients. It remains questionable whether the significance of these data is biologically plausible or the consequence of biases in the design of the study, but they counterbalance previous epidemiologic negative reports that might have overestimated the assessment of blood safety in sporadic CJD. © 2010 American Association of Blood Banks.

Saturn's Irregular Moon Ymir

Science.gov (United States)

Denk, Tilmann; Mottola, S.

2012-10-01

Ymir (diameter 18 km), Saturn's second largest retrograde outer or irregular moon, has been observed six times by the Cassini narrow-angle camera (NAC) during the first 7 months in 2012. The observations span phase angles from 2° up to 102° and were taken at ranges between 15 and 18 million kilometers. From such a distance, Ymir is smaller than a pixel in the Cassini NAC. The data reveal a sidereal rotation period of 11.93 hrs, which is 1.6x longer than the previously reported value (Denk et al. 2011, EPSC/DPS #1452). Reason for this discrepancy is that the rotational light curve shows a rather uncommon 3-maxima and 3-minima shape at least in the phase angle range 50° to 100°, which was not recognizable in earlier data. The data cover several rotations from different viewing and illumination geometries and allow for a convex shape inversion with possibly a unique solution for the pole direction. The model reproduces the observed light curves to a very good accuracy without requiring albedo variegation, thereby suggesting that the lightcurve is dominated by the shape of Ymir. Among Saturn's irregular moons, the phenomenon of more than two maxima and minima at moderate to high phase angles is not unique to Ymir. At least Siarnaq and Paaliaq also show light curves with a strong deviation from a double-sine curve. Their rotation periods, however, remain unknown until more data can be taken. The light curve of Phoebe is fundamentally different to Ymir's because it is mainly shaped by local albedo differences and not by shape. Other reliable rotation periods of irregular satellites measured by Cassini include: Mundilfari 6.74 h; Kari 7.70 h; Albiorix 13.32 h; Kiviuq 21.82 h. More uncertain values are: Skathi 12 h; Bebhionn 16 h; Thrymr 27 h; Erriapus 28 h.

Computing Homology Group Generators of Images Using Irregular Graph Pyramids

OpenAIRE

Peltier , Samuel; Ion , Adrian; Haxhimusa , Yll; Kropatsch , Walter; Damiand , Guillaume

2007-01-01

International audience; We introduce a method for computing homology groups and their generators of a 2D image, using a hierarchical structure i.e. irregular graph pyramid. Starting from an image, a hierarchy of the image is built, by two operations that preserve homology of each region. Instead of computing homology generators in the base where the number of entities (cells) is large, we first reduce the number of cells by a graph pyramid. Then homology generators are computed efficiently on...

Uniform irradiation of irregularly shaped cavities for photodynamic therapy

NARCIS (Netherlands)

Rem, A. I.; van Gemert, M. J.; van der Meulen, F. W.; Gijsbers, G. H.; Beek, J. F.

1997-01-01

It is difficult to achieve a uniform light distribution in irregularly shaped cavities. We have conducted a study on the use of hollow 'integrating' moulds for more uniform light delivery of photodynamic therapy in irregularly shaped cavities such as the oral cavity. Simple geometries such as a

Low Temperature Plasma for decontamination of E. coli in milk.

Science.gov (United States)

Gurol, C; Ekinci, F Y; Aslan, N; Korachi, M

2012-06-15

Raw milk is a natural, highly nutritious product and a quick and easy supplement for human dietary requirements. Elimination of bacteria in milk has been a problem for decades and new methods with regards to non-thermal applications which do not harm the chemical composition of milk, are currently under investigation. The objective of the study was to determine the potential use of a novel, Low Temperature Plasma (LTP) system for its capability of killing Escherichia coli in milk with different fat contents. The time dependent effect of atmospheric corona discharge generated with 9kV of AC power supply on E. coli ATCC 25922 dispersed in whole, semi skimmed and skimmed milk was examined. Plasma was applied at time intervals of 0, 3, 6, 9, 12, 15 and 20min. A significant 54% reduction in the population of E. coli cells after only 3min was observed regardless of the fat content of the milk. The initial pre-plasma bacterial count of 7.78 Log CFU/ml in whole milk was decreased to 3.63 Log CFU/ml after 20min of plasma application. LTP did not cause any significant change to the pH and color values of raw milk samples. No viable cells were detected after one week examination in whole milk samples and remained so over the 6week storage period. The findings of this study show that the novel LTP system tested was able to significantly reduce E. coli in milk by more than a 3 fold log reduction without significantly affecting pH or color properties. Copyright © 2012 Elsevier B.V. All rights reserved.

Gastric Medullary Carcinoma with Sporadic Mismatch Repair Deficiency and a TP53 R273C Mutation: An Unusual Case with Wild-Type BRAF

Directory of Open Access Journals (Sweden)

Brett M. Lowenthal

2017-01-01

Full Text Available Medullary carcinoma has long been recognized as a subtype of colorectal cancer associated with microsatellite instability and Lynch syndrome. Gastric medullary carcinoma is a very rare neoplasm. We report a 67-year-old male who presented with a solitary gastric mass. Total gastrectomy revealed a well-demarcated, poorly differentiated carcinoma with an organoid growth pattern, pushing borders, and abundant peritumoral lymphocytic response. The prior cytology was cellular with immunohistochemical panel consistent with upper gastrointestinal/pancreaticobiliary origin. Overall, the histopathologic findings were consistent with gastric medullary carcinoma. A mismatch repair panel revealed a mismatch repair protein deficient tumor with loss of MLH1 and PMS2 expression. BRAF V600E immunostain (VE1 and BRAF molecular testing were negative, indicating a wild-type gene. Tumor sequencing of MLH1 demonstrated a wild-type gene, while our molecular panel identified TP53 c.817C>T (p.R273C mutation. These findings were compatible with a sporadic tumor. Given that morphologically identical medullary tumors often occur in Lynch syndrome, it is possible that mismatch repair loss is an early event in sporadic tumors with p53 mutation being a late event. Despite having wild-type BRAF, this tumor is sporadic and unrelated to Lynch syndrome. This case report demonstrates that coordinate ancillary studies are needed to resolve sporadic versus hereditary rare tumors.

Analysis of an Irregular RC Multi-storeyed Building Subjected to Dynamic Loading

Science.gov (United States)

AkashRaut; Pachpor, Prabodh; Dautkhani, Sanket

2018-03-01

Many buildings in the present scenario have irregular configurations both in plan and elevation. This in future may subject to devastating earthquakes. So it is necessary to analyze the structure. The present paper is made to study three type of irregularity wiz vertical, mass and plan irregularity as per clause 7.1 of IS 1893 (part1)2002 code. The paper discusses the analysis of RC (Reinforced Concrete) Buildings with vertical irregularity. The study as a whole makes an effort to evaluate the effect of vertical irregularity on RC buildings for which comparison of three parameters namely shear force, bending moment and deflection are taken into account.

Near Earth space sporadic radio emission busts occurring during sunrise

Science.gov (United States)

Dudnik, A. V.; Zaljubovsky, I. I.; Kartashev, V. M.; Lasarev, A. V.; Shmatko, E. S.

1985-01-01

During the period of low solar activity at sunrise the effect of sporadic high frequency near Earth space radio emission was experimentally discovered at middle latitudes. The possible mechanism of its origin is discussed.

Oestrogen receptor beta isoform expression in sporadic colorectal cancer, familial adenomatous polyposis and progressive stages of colorectal cancer

DEFF Research Database (Denmark)

Stevanato Filho, Paulo Roberto; Aguiar Júnior, Samuel; Begnami, Maria Dirlei

2017-01-01

BACKGROUND: Among the sex hormones, oestrogen may play a role in colorectal cancer, particularly in conjunction with oestrogen receptor-β (ERβ). The expression of ERβ isoform variants and their correlations with familial adenomatous polyposis (FAP) syndrome and sporadic colorectal carcinomas...... was identified in sporadic polyps and in sporadic colorectal cancer as well as in polyps from FAP syndrome patients compared with normal tissues (p expression in polyps (p ..., no differences were observed when sporadic colorectal carcinomas were compared to normal mucosa tissues. These findings suggest an association of the ERβ isoform variants in individuals affected by germline mutations of the APC gene. Progressively decreased expression of ERβ was found in polyps at early stages...

Spatial irregularities in Jupiter's upper ionosphere observed by Voyager radio occultations

Science.gov (United States)

Hinson, D. P.; Tyler, G. L.

1982-01-01

Radio scintillations (at 3.6 and 13 cm) produced by scattering from ionospheric irregularities during the Voyager occultations are interpreted using a weak-scattering theory. Least squares solutions for ionospheric parameters derived from the observed fluctuation spectra yield estimates of (1) the axial ratio, (2) angular orientation of the anisotropic irregularities, (3) the power law exponent of the spatial spectrum of irregularities, and (4) the magnitude of the spatial variations in electron density. It is shown that the measured angular orientation of the anisotropic irregularities indicates magnetic field direction and may provide a basis for refining Jovian magnetic field models.

Irregular Dwarf Galaxy IC 1613

Science.gov (United States)

2005-01-01

Ultraviolet image (left) and visual image (right) of the irregular dwarf galaxy IC 1613. Low surface brightness galaxies, such as IC 1613, are more easily detected in the ultraviolet because of the low background levels compared to visual wavelengths.

Irregular HF radio propagation on a subauroral path during magnetospheric substorms

Directory of Open Access Journals (Sweden)

D. V. Blagoveshchensky

2006-08-01

Full Text Available The impact of the main ionospheric trough, sporadic structures, gradients and inhomogeneities of the subpolar ionosphere during substorms on the signal amplitude, azimuthal angles of arrival, and propagation modes for the radio path Ottawa (Canada-St. Petersburg (Russia was considered. This subauroral path with the length of about 6600 km has approximately an east-west orientation. The main goals are to carry out numerical modeling of radio propagation for the path and to compare the model calculations with experimental results. Wave absorption and effects of focusing and divergence of rays were taken into consideration in the radio wave modeling process. The following basic results were obtained: The signal amplitude increases by 20–30 dB 1–1.5 h before the substorm expansion phase onset. At the same time the signal azimuth deviates towards north of the great circle arc for the propagation path. Compared with quiet periods there are effects due to irregularities and gradients in the area of the polar edge of the main ionospheric trough on the passing signals. Propagation mechanisms also change during substorms. The growth of signal amplitude before the substorm can be physically explained by both a decrease of the F2-layer ionization and a growth of the F2-layer height that leads to a decrease of the signal field divergence and to a drop of the collision frequency. Ionospheric gradients are also important. This increase of signal level prior to a substorm could be used for forecasting of space weather disturbed conditions.

Regularisation of irregular verbs in child English second language ...

African Journals Online (AJOL)

Data was collected from the language of English medium preschool children. The study concludes that when the Blocking Principle interferes, children resort to a novel interlanguage rule that regularises irregular verbs. This interlanguage rule applies in a similar way to all irregular verbs, thus children produce utterances ...

Low frequency sound reproduction in irregular rooms using CABS (Control Acoustic Bass System)

DEFF Research Database (Denmark)

Celestinos, Adrian; Nielsen, Sofus Birkedal

2011-01-01

of an irregular room model using the FDTD (Finite Difference Time Domain) method has been presented. CABS has been simulated in the irregular room model. Measurements of CABS in a real irregular room have been performed. The performance of CABS was affected by the irregular shape of the room due to the corner...

Influence of Coding Variability in APP-Aβ Metabolism Genes in Sporadic Alzheimer's Disease.

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Celeste Sassi

Full Text Available The cerebral deposition of Aβ42, a neurotoxic proteolytic derivate of amyloid precursor protein (APP, is a central event in Alzheimer's disease (AD(Amyloid hypothesis. Given the key role of APP-Aβ metabolism in AD pathogenesis, we selected 29 genes involved in APP processing, Aβ degradation and clearance. We then used exome and genome sequencing to investigate the single independent (single-variant association test and cumulative (gene-based association test effect of coding variants in these genes as potential susceptibility factors for AD, in a cohort composed of 332 sporadic and mainly late-onset AD cases and 676 elderly controls from North America and the UK. Our study shows that common coding variability in these genes does not play a major role for the disease development. In the single-variant association analysis, the main hits, none of which statistically significant after multiple testing correction (1.9e-4e-3 sporadic AD.

Dual infection with hepatitis A and E viruses in outbreaks and in sporadic clinical cases: Cuba 1998-2003.

Science.gov (United States)

Rodríguez Lay, Licel de los Angeles; Quintana, Ariel; Villalba, María Caridad Montalvo; Lemos, Gilda; Corredor, Marité Bello; Moreno, Aidonis Gutiérrez; Prieto, Pablo Aguiar; Guzmán, María G; Anderson, David

2008-05-01

Viral hepatitis ranks as the fifth cause of morbidity for infectious diseases in Cuba. Epidemics are observed frequently in the population, the hepatitis A virus being the main agent responsible for such epidemics. Previous reports also confirmed the circulation of the hepatitis E virus. From 1998 to 2003, 258 serum samples were collected by the Reference Laboratory on Viral Hepatitis during 33 outbreaks of acute viral hepatitis as well as from 39 sporadic clinical cases. Sera were tested for anti-HAV and anti-HEV IgM by EIA. Overall of the 33 outbreaks studied sera from 12 (36.4%) were positive for anti-HAV IgM only, from 7 (21.2%) were positive for anti-HEV IgM only, and from 14 (42.4%) were positive for antibodies to both viruses. Individually of the 258 sera collected, 137 (53.1%) were positives for anti-HAV IgM, 20 (7.8%) were positives for anti-HEV IgM, 33 (12.8%) were positives for both markers and 68 (26.4%) were negative to both. Of the clinical cases, 4 (10.3%) were positives for anti-HAV IgM, 13 (33.3%) were positives for anti-HEV IgM and 5 (12.8%) were positives for both markers. Seventeen (43.6%) sera were negatives for all viral hepatitis markers available (A-E). A high positivity for HEV was found in outbreaks tested with the kit produced by CIGB. In particular HEV seems to infect individuals of all ages. The results demonstrate the co-circulation of and co-infection with two enterically transmitted viruses; however a higher positivity was observed for anti-HAV than to anti-HEV (53.1% vs. 7.8%) in outbreaks.

High energy model for irregular absorbing particles

International Nuclear Information System (INIS)

Chiappetta, Pierre.

1979-05-01

In the framework of a high energy formulation of relativistic quantum scattering a model is presented which describes the scattering functions and polarization of irregular absorbing particles, whose dimensions are greater than the incident wavelength. More precisely in the forward direction an amplitude parametrization of eikonal type is defined which generalizes the usual diffraction theory, and in the backward direction a reflective model is used including a shadow function. The model predictions are in good agreement with the scattering measurements off irregular compact and fluffy particles performed by Zerull, Giese and Weiss (1977)

Microsatellite D21D210 (GT-12) allele frequencies in sporadic Alzheimer's disease

International Nuclear Information System (INIS)

Lannfelt, L.; Lilius, L.; Viitanen, M.; Winblad, B.; Basun, H.; Houlden, H.; Rossor, M.; Hardy, J.

1995-01-01

Four disease-causing mutations have so far been described in the amyloid precursor protein gene on chromosome 21 in familial early-onset Alzheimer's disease. Linkage analysis with a fourteen-allele microsatellite at D21S210 named GT-12 has proven useful in the elucidation of amyloid presursor protein gene involvement in Alzheimer's disease families, as it is closely linked to the gene. Most cases of Alzheimer's disease are thought to be sporadic and not familial. However, evidence from earlier studies suggests an important genetic contribution also in sporadic cases, where gene-environment interaction may contribute to the disease. We have determined frequencies of the GT-12 alleles in 78 Swedish and 49 British sporadic Alzheimer's disease cases and 104 healthy elderly control subjects, to investigate if the disease associates with a particular genotype in GT-12. However, no differences in allele frequencies were observed between any of the groups. (au) (26 refs.)

Mutation analysis of SDHB and SDHC: novel germline mutations in sporadic head and neck paraganglioma and familial paraganglioma and/or pheochromocytoma

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Wong Nora

2006-01-01

Full Text Available Abstract Background Germline mutations of the SDHD, SDHB and SDHC genes, encoding three of the four subunits of succinate dehydrogenase, are a major cause of hereditary paraganglioma and pheochromocytoma, and demonstrate that these genes are classic tumor suppressors. Succinate dehydrogenase is a heterotetrameric protein complex and a component of both the Krebs cycle and the mitochondrial respiratory chain (succinate:ubiquinone oxidoreductase or complex II. Methods Using conformation sensitive gel electrophoresis (CSGE and direct DNA sequencing to analyse genomic DNA from peripheral blood lymphocytes, here we describe the mutation analysis of the SDHB and SDHC genes in 37 patients with sporadic (i.e. no known family history head and neck paraganglioma and five pheochromocytoma and/or paraganglioma families. Results Two sporadic patients were found to have a SDHB splice site mutation in intron 4, c.423+1G>A, which produces a mis-spliced transcript with a 54 nucleotide deletion, resulting in an 18 amino acid in-frame deletion. A third patient was found to carry the c.214C>T (p.Arg72Cys missense mutation in exon 4 of SDHC, which is situated in a highly conserved protein motif that constitutes the quinone-binding site of the succinate: ubiquinone oxidoreductase (SQR complex in E. coli. Together with our previous results, we found 27 germline mutations of SDH genes in 95 cases (28% of sporadic head and neck paraganglioma. In addition all index patients of five families showing hereditary pheochromocytoma-paraganglioma were found to carry germline mutations of SDHB: four of which were novel, c.343C>T (p.Arg115X, c.141G>A (p.Trp47X, c.281G>A (p.Arg94Lys, and c.653G>C (p.Trp218Ser, and one reported previously, c.136C>T, p.Arg46X. Conclusion In conclusion, these data indicate that germline mutations of SDHB and SDHC play a minor role in sporadic head and neck paraganglioma and further underline the importance of germline SDHB mutations in cases of

Simultaneous observations of ESF irregularities over Indian region using radar and GPS

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S. Sripathi

2008-10-01

Full Text Available In this paper, we present simultaneous observations of temporal and spatial variability of total electron content (TEC and GPS amplitude scintillations on L1 frequency (1.575 GHz during the time of equatorial spread F (ESF while the MST radar (53 MHz located at Gadanki (13.5° N, 79.2° E, Dip latitude 6.3° N, a low latitude station, made simultaneous observations. In particular, the latitudinal and longitudinal extent of TEC and L-band scintillations was studied in the Indian region for different types of ESF structures observed using the MST radar during the low solar activity period of 2004 and 2005. Simultaneous radar and GPS observations during severe ESF events in the pre-midnight hour reveal that significant GPS L band scintillations, depletions in TEC, and the double derivative of the TEC index (DROTI, which is a measure of fluctuations in TEC, obtained at low latitudes coincide with the appearance of radar echoes at Gadanki. As expected, when the irregularities reach higher altitudes as seen in the radar map during pre-midnight periods, strong scintillations on an L-band signal are observed at higher latitudes. Conversely, when radar echoes are confined to only lower altitudes, weak scintillations are found and their latitudinal extent is small. During magnetically quiet periods, we have recorded plume type radar echoes during a post-midnight period that is devoid of L-band scintillations. Using spectral slopes and cross-correlation index of the VHF scintillation observations, we suggest that these irregularities could be "dead" or "fossil" bubbles which are just drifting in from west. This scenario is consistent with the observations where suppression of pre-reversal enhancement (PRE in the eastward electric field is indicated by ionosonde observations of the height of equatorial F layer and also occurrence of low spectral width in the radar observations relative to pre-midnight period. However, absence of L-band scintillations during

The localization of facial motor impairment in sporadic Möbius syndrome.

Science.gov (United States)

Cattaneo, L; Chierici, E; Bianchi, B; Sesenna, E; Pavesi, G

2006-06-27

To investigate the neurophysiologic aspects of facial motor control in patients with sporadic Möbius syndrome defined as nonprogressive congenital facial and abducens palsy. The authors assessed 24 patients with sporadic Möbius syndrome by performing a complete clinical examination and neurophysiologic tests including facial nerve conduction studies, needle electromyography examination of facial muscles, and recording of the blink reflex and of the trigeminofacial inhibitory reflex. Two distinct groups of patients were identified according to neurophysiologic testing. The first group was characterized by increased facial distal motor latencies (DMLs) and poor recruitment of small and polyphasic motor unit action potentials (MUAPs). The second group was characterized by normal facial DMLs and neuropathic MUAPs. It is hypothesized that in the first group, the disorder is due to a rhombencephalic maldevelopment with selective sparing of small-size MUs, and in the second group, the disorder is related to an acquired nervous injury during intrauterine life, with subsequent neurogenic remodeling of MUs. The trigeminofacial reflexes showed that in most subjects of both groups, the functional impairment of facial movements was caused by a nuclear or peripheral site of lesion, with little evidence of brainstem interneuronal involvement. Two different neurophysiologically defined phenotypes can be distinguished in sporadic Möbius syndrome, with different pathogenetic implications.

Developing the science and technology for the Material Plasma Exposure eXperiment

Science.gov (United States)

Rapp, J.; Biewer, T. M.; Bigelow, T. S.; Caneses, J. F.; Caughman, J. B. O.; Diem, S. J.; Goulding, R. H.; Isler, R. C.; Lumsdaine, A.; Beers, C. J.; Bjorholm, T.; Bradley, C.; Canik, J. M.; Donovan, D.; Duckworth, R. C.; Ellis, R. J.; Graves, V.; Giuliano, D.; Green, D. L.; Hillis, D. L.; Howard, R. H.; Kafle, N.; Katoh, Y.; Lasa, A.; Lessard, T.; Martin, E. H.; Meitner, S. J.; Luo, G.-N.; McGinnis, W. D.; Owen, L. W.; Ray, H. B.; Shaw, G. C.; Showers, M.; Varma, V.; the MPEX Team

2017-11-01

Linear plasma generators are cost effective facilities to simulate divertor plasma conditions of present and future fusion reactors. They are used to address important R&D gaps in the science of plasma material interactions and towards viable plasma facing components for fusion reactors. Next generation plasma generators have to be able to access the plasma conditions expected on the divertor targets in ITER and future devices. The steady-state linear plasma device MPEX will address this regime with electron temperatures of 1-10 eV and electron densities of 1021{\\text{}}-1020 m-3 . The resulting heat fluxes are about 10 MW m-2 . MPEX is designed to deliver those plasma conditions with a novel Radio Frequency plasma source able to produce high density plasmas and heat electron and ions separately with electron Bernstein wave (EBW) heating and ion cyclotron resonance heating with a total installed power of 800 kW. The linear device Proto-MPEX, forerunner of MPEX consisting of 12 water-cooled copper coils, has been operational since May 2014. Its helicon antenna (100 kW, 13.56 MHz) and EC heating systems (200 kW, 28 GHz) have been commissioned and 14 MW m-2 was delivered on target. Furthermore, electron temperatures of about 20 eV have been achieved in combined helicon and ECH heating schemes at low electron densities. Overdense heating with EBW was achieved at low heating powers. The operational space of the density production by the helicon antenna was pushed up to 1.1 × 1020 m-3 at high magnetic fields of 1.0 T at the target. The experimental results from Proto-MPEX will be used for code validation to enable predictions of the source and heating performance for MPEX. MPEX, in its last phase, will be capable to expose neutron-irradiated samples. In this concept, targets will be irradiated in ORNL’s High Flux Isotope Reactor and then subsequently exposed to fusion reactor relevant plasmas in MPEX.

Mapping of gene expression reveals CYP27A1 as a susceptibility gene for sporadic ALS.

Directory of Open Access Journals (Sweden)

Frank P Diekstra

Full Text Available Amyotrophic lateral sclerosis (ALS is a progressive, neurodegenerative disease characterized by loss of upper and lower motor neurons. ALS is considered to be a complex trait and genome-wide association studies (GWAS have implicated a few susceptibility loci. However, many more causal loci remain to be discovered. Since it has been shown that genetic variants associated with complex traits are more likely to be eQTLs than frequency-matched variants from GWAS platforms, we conducted a two-stage genome-wide screening for eQTLs associated with ALS. In addition, we applied an eQTL analysis to finemap association loci. Expression profiles using peripheral blood of 323 sporadic ALS patients and 413 controls were mapped to genome-wide genotyping data. Subsequently, data from a two-stage GWAS (3,568 patients and 10,163 controls were used to prioritize eQTLs identified in the first stage (162 ALS, 207 controls. These prioritized eQTLs were carried forward to the second sample with both gene-expression and genotyping data (161 ALS, 206 controls. Replicated eQTL SNPs were then tested for association in the second-stage GWAS data to find SNPs associated with disease, that survived correction for multiple testing. We thus identified twelve cis eQTLs with nominally significant associations in the second-stage GWAS data. Eight SNP-transcript pairs of highest significance (lowest p = 1.27 × 10(-51 withstood multiple-testing correction in the second stage and modulated CYP27A1 gene expression. Additionally, we show that C9orf72 appears to be the only gene in the 9p21.2 locus that is regulated in cis, showing the potential of this approach in identifying causative genes in association loci in ALS. This study has identified candidate genes for sporadic ALS, most notably CYP27A1. Mutations in CYP27A1 are causal to cerebrotendinous xanthomatosis which can present as a clinical mimic of ALS with progressive upper motor neuron loss, making it a plausible

Small scale irregularities in Comet Halley's plasma mantle - An attempt at self-consistent analysis of plasma and magnetic field data

Science.gov (United States)

Vaisberg, O. L.; Russell, C. T.; Luhmann, J. G.; Schwingenschuh, K.

1989-01-01

VEGA-1 measurements of the plasma density and magnetic field in the coma of Comet Halley show characteristic signatures over a significant portion of the outbound pass. It is found that the assumption that there is a balance between the thermal and magnetic pressures in these features can be used to obtain estimates of the plasma temperature as a function of distance from the nucleus. These estimates indicate that the ions cool from about 1.5 x 10 to the 6th K at 10 to the 5th km to 2 x 10 to the 5th K at 5 x 10 to the 4th km. The technique used here represents a novel approach whereby temperature measurements can be made in situations where only plasma density and magnetic field data are available.

The search for quark-gluon plasma at E735

International Nuclear Information System (INIS)

Findeisen, Ch.

1989-01-01

The experiment E735 was designed to measure soft p t physics in proton-antiproton interactions at √s=1.8 TeV performed at Fermilab's Tevatron collider. Some ideas related to Quark Gluon Plasma (QGP) are recalled with emphasis on their applications to E735. The experiment E735 measures minimum-bias soft p t events in proton-antiproton interactions at √s=1.8 TeV. One goal of E735 is to search for signs of a deconfined hadronic phase produced in the central region. Some results including particle identified spectra are presented from the first run in 1987. (R.P.) 25 refs.; 13 figs

Classical limit of irregular blocks and Mathieu functions

International Nuclear Information System (INIS)

Piątek, Marcin; Pietrykowski, Artur R.

2016-01-01

The Nekrasov-Shatashvili limit of the N = 2 SU(2) pure gauge (Ω-deformed) super Yang-Mills theory encodes the information about the spectrum of the Mathieu operator. On the other hand, the Mathieu equation emerges entirely within the frame of two-dimensional conformal field theory (2d CFT) as the classical limit of the null vector decoupling equation for some degenerate irregular block. Therefore, it seems to be possible to investigate the spectrum of the Mathieu operator employing the techniques of 2d CFT. To exploit this strategy, a full correspondence between the Mathieu equation and its realization within 2d CFT has to be established. In our previous paper http://dx.doi.org/10.1007/JHEP12(2014)032, we have found that the expression of the Mathieu eigenvalue given in terms of the classical irregular block exactly coincides with the well known weak coupling expansion of this eigenvalue in the case in which the auxiliary parameter is the noninteger Floquet exponent. In the present work we verify that the formula for the corresponding eigenfunction obtained from the irregular block reproduces the so-called Mathieu exponent from which the noninteger order elliptic cosine and sine functions may be constructed. The derivation of the Mathieu equation within the formalism of 2d CFT is based on conjectures concerning the asymptotic behaviour of irregular blocks in the classical limit. A proof of these hypotheses is sketched. Finally, we speculate on how it could be possible to use the methods of 2d CFT in order to get from the irregular block the eigenvalues of the Mathieu operator in other regions of the coupling constant.

Reactive GTS Allocation Protocol for Sporadic Events Using the IEEE 802.15.4

Directory of Open Access Journals (Sweden)

Mukhtar Azeem

2014-01-01

by the IEEE 802.15.4 standard. The proposed control protocol ensures that a given offline sporadic schedule can be adapted online in a timely manner such that the static periodic schedule has not been disturbed and the IEEE 802.15.4 standard compliance remains intact. The proposed protocol is simulated in OPNET. The simulation results are analyzed and presented in this paper to prove the correctness of the proposed protocol regarding the efficient real-time sporadic event delivery along with the periodic event propagation.

Understanding Transient Forcing with Plasma Instability Model, Ionospheric Propagation Model and GNSS Observations

Science.gov (United States)

Deshpande, K.; Zettergren, M. D.; Datta-Barua, S.

2017-12-01

Fluctuations in the Global Navigation Satellite Systems (GNSS) signals observed as amplitude and phase scintillations are produced by plasma density structures in the ionosphere. Phase scintillation events in particular occur due to structures at Fresnel scales, typically about 250 meters at ionospheric heights and GNSS frequency. Likely processes contributing to small-scale density structuring in auroral and polar regions include ionospheric gradient-drift instability (GDI) and Kelvin-Helmholtz instability (KHI), which result, generally, from magnetosphere-ionosphere interactions (e.g. reconnection) associated with cusp and auroral zone regions. Scintillation signals, ostensibly from either GDI or KHI, are frequently observed in the high latitude ionosphere and are potentially useful diagnostics of how energy from the transient forcing in the cusp or polar cap region cascades, via instabilities, to small scales. However, extracting quantitative details of instabilities leading to scintillation using GNSS data drastically benefits from both a model of the irregularities and a model of GNSS signal propagation through irregular media. This work uses a physics-based model of the generation of plasma density irregularities (GEMINI - Geospace Environment Model of Ion-Neutral Interactions) coupled to an ionospheric radio wave propagation model (SIGMA - Satellite-beacon Ionospheric-scintillation Global Model of the upper Atmosphere) to explore the cascade of density structures from medium to small (sub-kilometer) scales. Specifically, GEMINI-SIGMA is used to simulate expected scintillation from different instabilities during various stages of evolution to determine features of the scintillation that may be useful to studying ionospheric density structures. Furthermore we relate the instabilities producing GNSS scintillations to the transient space and time-dependent magnetospheric phenomena and further predict characteristics of scintillation in different geophysical

A novel method of the image processing on irregular triangular meshes

Science.gov (United States)

Vishnyakov, Sergey; Pekhterev, Vitaliy; Sokolova, Elizaveta

2018-04-01

The paper describes a novel method of the image processing based on irregular triangular meshes implementation. The triangular mesh is adaptive to the image content, least mean square linear approximation is proposed for the basic interpolation within the triangle. It is proposed to use triangular numbers to simplify using of the local (barycentric) coordinates for the further analysis - triangular element of the initial irregular mesh is to be represented through the set of the four equilateral triangles. This allows to use fast and simple pixels indexing in local coordinates, e.g. "for" or "while" loops for access to the pixels. Moreover, representation proposed allows to use discrete cosine transform of the simple "rectangular" symmetric form without additional pixels reordering (as it is used for shape-adaptive DCT forms). Furthermore, this approach leads to the simple form of the wavelet transform on triangular mesh. The results of the method application are presented. It is shown that advantage of the method proposed is a combination of the flexibility of the image-adaptive irregular meshes with the simple form of the pixel indexing in local triangular coordinates and the using of the common forms of the discrete transforms for triangular meshes. Method described is proposed for the image compression, pattern recognition, image quality improvement, image search and indexing. It also may be used as a part of video coding (intra-frame or inter-frame coding, motion detection).

Track Irregularity Time Series Analysis and Trend Forecasting

Directory of Open Access Journals (Sweden)

Jia Chaolong

2012-01-01

Full Text Available The combination of linear and nonlinear methods is widely used in the prediction of time series data. This paper analyzes track irregularity time series data by using gray incidence degree models and methods of data transformation, trying to find the connotative relationship between the time series data. In this paper, GM (1,1 is based on first-order, single variable linear differential equations; after an adaptive improvement and error correction, it is used to predict the long-term changing trend of track irregularity at a fixed measuring point; the stochastic linear AR, Kalman filtering model, and artificial neural network model are applied to predict the short-term changing trend of track irregularity at unit section. Both long-term and short-term changes prove that the model is effective and can achieve the expected accuracy.

Evaluation of statistical methods for quantifying fractal scaling in water-quality time series with irregular sampling

Directory of Open Access Journals (Sweden)

Q. Zhang

2018-02-01

Full Text Available River water-quality time series often exhibit fractal scaling, which here refers to autocorrelation that decays as a power law over some range of scales. Fractal scaling presents challenges to the identification of deterministic trends because (1 fractal scaling has the potential to lead to false inference about the statistical significance of trends and (2 the abundance of irregularly spaced data in water-quality monitoring networks complicates efforts to quantify fractal scaling. Traditional methods for estimating fractal scaling – in the form of spectral slope (β or other equivalent scaling parameters (e.g., Hurst exponent – are generally inapplicable to irregularly sampled data. Here we consider two types of estimation approaches for irregularly sampled data and evaluate their performance using synthetic time series. These time series were generated such that (1 they exhibit a wide range of prescribed fractal scaling behaviors, ranging from white noise (β  =  0 to Brown noise (β  =  2 and (2 their sampling gap intervals mimic the sampling irregularity (as quantified by both the skewness and mean of gap-interval lengths in real water-quality data. The results suggest that none of the existing methods fully account for the effects of sampling irregularity on β estimation. First, the results illustrate the danger of using interpolation for gap filling when examining autocorrelation, as the interpolation methods consistently underestimate or overestimate β under a wide range of prescribed β values and gap distributions. Second, the widely used Lomb–Scargle spectral method also consistently underestimates β. A previously published modified form, using only the lowest 5 % of the frequencies for spectral slope estimation, has very poor precision, although the overall bias is small. Third, a recent wavelet-based method, coupled with an aliasing filter, generally has the smallest bias and root-mean-squared error among

Association between rs6812193 polymorphism and sporadic Parkinson's disease susceptibility.

Science.gov (United States)

Huo, Qiang; Li, Tao; Zhao, Peiqing; Wang, Lianqing

2015-08-01

Recently, the association of a single nucleotide polymorphism rs6812193 C/T with sporadic Parkinson's disease (PD) susceptibility has been widely evaluated, but the results remained inconsistent. This association should be clarified because of the importance of it on human health and quality of life. We performed a comprehensive meta-analysis to evaluate the association between the rs6812193 polymorphism and sporadic PD. PubMed was used to retrieve articles published up to June 2014 for all studies evaluating the rs6812193 polymorphism and PD in humans. Ethnicity-specific subgroup analysis was also performed based on ethnicity susceptibility. A total of 17 independent study samples (15 Caucasians and 2 Asians) including 17,956 cases and 52,751 controls were used in the presented study. The MAFT (minor allele T frequency) in PD patients of European descent is obviously higher than Asian cases (p susceptibility among overall samples (OR 0.882, 95 % CI 0.856-0.908) and Caucasian population (OR 0.881, 95 % CI 0.856-0.907), but not in Asian samples (OR 0.918, 95 % CI 0.721-1.168). No evidence of publication bias was observed. Throughout our analysis, the rs6812193 polymorphism is significantly associated with sporadic PD susceptibility in Caucasian samples, and ethnicity might be the key point of inconsistency in rs6812193 studies. Further studies are warranted to re-examine the observed associations, especially in different ethnicities.

Examining U.S. Irregular Warfare Doctrine

National Research Council Canada - National Science Library

Kimbrough, IV, James M

2008-01-01

... of insurgency and terrorism. In response to the associated strategic challenges, a growing debate occurred among military historians, strategists, and leaders about the proper principles necessary for contemporary irregular...

Traffic dispersion through a series of signals with irregular split

Science.gov (United States)

Nagatani, Takashi

2016-01-01

We study the traffic behavior of a group of vehicles moving through a sequence of signals with irregular splits on a roadway. We present the stochastic model of vehicular traffic controlled by signals. The dynamic behavior of vehicular traffic is clarified by analyzing traffic pattern and travel time numerically. The group of vehicles breaks up more and more by the irregularity of signal's split. The traffic dispersion is induced by the irregular split. We show that the traffic dispersion depends highly on the cycle time and the strength of split's irregularity. Also, we study the traffic behavior through the series of signals at the green-wave strategy. The dependence of the travel time on offset time is derived for various values of cycle time. The region map of the traffic dispersion is shown in (cycle time, offset time)-space.

População estelar jovem em galáxias irregulares próximas

Science.gov (United States)

Guimarães, T. A.; Telles, E.

2003-08-01

A análise do conteúdo estelar de galáxias próximas através da fotometria das suas estrelas resolvidas nos fornece informações importantes sobre a história de formação estelar e os processos de formação estelar em galáxias, que estão diretamente ligados ao estudo de evolução de galáxias. Quando nenhuma estrela puder ser resolvida o método mais poderoso consiste na análise do conteúdo estelar integrado das galáxias através das suas cores integradas em conjunto com informação espectroscópica que combinados com modelos de síntese evolutiva podem restringir simultaneamente a função de massa inicial (IMF) e a taxa de formação estelar (SFR). Nesse contexto, galáxias do tipo tardio, em particular, irregulares, são relevantes por várias razões: elas são objetos relativamente simples, com alta atividade de formação estelar e são objetos relativamente jovens (geralmente apresentam baixas abundâncias de elementos pesados e grande quantidade de gás). Apresentamos uma análise fotométrica de uma amostra de 7 galáxias do tipo tardio do universo local (NGC 2366, NGC 4395, NGC 4656, NGC 4214, NGC 4236, HOII, IC2574) que foram observadas com uma boa resolução espacial nas bandas B, V e R no telescópio Isaac Newton de 2.5m de Roque de los Muchachos nas Ilhas Canárias, Espanha. A distribuição espacial da população estelar jovem dessas galáxias é discutida sobre os pontos de vista dos íindices de cor integrados e dos seus diagramas cor magnitude, que comparados com isócronas teóricas, nos fornecem informações sobre os eventos de formação estelar, como por exemplo, indicações sobre a idade dos mesmos. As principais conclusões do trabalho podem ser resumidas em: (i) As galáxias irregulares possuem formação estelar recente (FE) espalhada ocorrendo nos últimos 50 Manos; (ii) A formação estelar em galáxias irregulares não é auto-propagante em escalas globais ( > 100 pc) ; (iii) A FE pode ser auto-regulável em escalas

GARCH and Irregularly Spaced Data

NARCIS (Netherlands)

Meddahi, N.; Renault, E.; Werker, B.J.M.

2003-01-01

An exact discretization of continuous time stochastic volatility processes observed at irregularly spaced times is used to give insights on how a coherent GARCH model can be specified for such data. The relation of our approach with those in the existing literature is studied.

Studies of small-scale plasma inhomogeneities in the cusp ionosphere using sounding rocket data

Science.gov (United States)

Chernyshov, Alexander A.; Spicher, Andres; Ilyasov, Askar A.; Miloch, Wojciech J.; Clausen, Lasse B. N.; Saito, Yoshifumi; Jin, Yaqi; Moen, Jøran I.

2018-04-01

Microprocesses associated with plasma inhomogeneities are studied on the basis of data from the Investigation of Cusp Irregularities (ICI-3) sounding rocket. The ICI-3 rocket is devoted to investigating a reverse flow event in the cusp F region ionosphere. By numerical stability analysis, it is demonstrated that inhomogeneous-energy-density-driven (IEDD) instability can be a mechanism for the excitation of small-scale plasma inhomogeneities. The Local Intermittency Measure (LIM) method also applied the rocket data to analyze irregular structures of the electric field during rocket flight in the cusp. A qualitative agreement between high values of the growth rates of the IEDD instability and the regions with enhanced LIM is observed. This suggests that IEDD instability is connected to turbulent non-Gaussian processes.

Nonlinear interaction of an intense radio wave with ionospheric D/E layer plasma

Science.gov (United States)

Sodha, Mahendra Singh; Agarwal, Sujeet Kumar

2018-05-01

This paper considers the nonlinear interaction of an intense electromagnetic wave with the D/E layer plasma in the ionosphere. A simultaneous solution of the electromagnetic wave equation and the equations describing the kinetics of D/E layer plasma is obtained; the phenomenon of ohmic heating of electrons by the electric field of the wave causes enhanced collision frequency and ionization of neutral species. Electron temperature dependent recombination of electrons with ions, electron attachment to O 2 molecules, and detachment of electrons from O2 - ions has also been taken into account. The dependence of the plasma parameters on the square of the electric vector of the wave E0 2 has been evaluated for three ionospheric heights (viz., 90, 100, and 110 km) corresponding to the mid-latitude mid-day ionosphere and discussed; these results are used to investigate the horizontal propagation of an intense radio wave at these heights.

Direct evidence of plasma - density structuring in the auroral F-region ionosphere

International Nuclear Information System (INIS)

Tsunoda, R.T.; Haeggstroem, I.; Pellinen-Wannberg, A.; Steen, Aa.; Wannberg, G.

1985-03-01

We investigate the hypothesis that large-scale plasma-density enhancements found in the auroral F layer become structured via a magnetic-flux-tube interchange (MFTI) process. In such a process, plasma structure is produced when spatially irregular electric fields transport higher number-density plasma into a region containing lower number-density plasma, and vice versa. Direct experimental evidence of this process can be obtained by measuring concurrently the spatial distributions of F-region plasma density and electric field. Using the tristatic EISCAT radar facility, we measured these quantities in a two-dimensional plane transverse to the geomagnetic field, at 300-km altitude. We show, in a case study, that plasma-density structure found along the poleward wall of a blob was indeed accompanied by similar-scale variations in the ionospheric electric field, and that the sense of relative motion between high- and low-number-density plasma is consistent with ongoing structuring of the plasma via a MFTI process. From the estimated growth rate of 3 x 10 -3 s -1 , the observed plasma structure could have been produced in several minutes by the irregular electic field pattern. The source of the MFTI process, however, is not clear. The MFTI process did not appear to be driven by F-region polarization electric fields, a conclusion based on (1) the apparent lack of inverse correlation between plasma density and 'slip' velocity patterns, and (2) the positive growth rate found along the poleward wall of the blob in the presence of a westward Pedersen current. This conclusion excludes (at least for this data set) the gradient-drift and current-convective instabilities as primary sources of the ongoing structuring process. (Author)

Collisional Rayleigh-Taylor instability and shear-flow in equatorial Spread-F plasma

Directory of Open Access Journals (Sweden)

N. Chakrabarti

2003-05-01

Full Text Available Collisional Rayleigh-Taylor (RT instability is considered in the bottom side of the equatorial F-region. By a novel nonmodal calculation it is shown that for an applied shear flow in equilibrium, the growth of the instability is considerably reduced. Finite but small amounts of diffusion enhances the stabilization process. The results may be relevant to the observations of long-lived irregularities at the bottom-side of the F-layer.Key words. Ionosphere (ionospheric irregularities, equatorial ionosphere, plasma waves and instabilities

Higher cytoplasmic and nuclear poly(ADP-ribose) polymerase expression in familial than in sporadic breast cancer

NARCIS (Netherlands)

Klauke, M.L.; Hoogerbrugge-van der Linden, N.; Budczies, J.; Bult, P.; Prinzler, J.; Radke, C.; van Krieken, J.H.; Dietel, M.; Denkert, C.; Muller, B.M.

2012-01-01

Poly(ADP-ribose) polymerase 1 (PARP) is a key element of the single-base excision pathway for repair of DNA single-strand breaks. To compare the cytoplasmic and nuclear poly(ADP-ribose) expression between familial (BRCA1, BRCA2, or non BRCA1/2) and sporadic breast cancer, we investigated 39 sporadic

Multiple imputation by chained equations for systematically and sporadically missing multilevel data.

Science.gov (United States)

Resche-Rigon, Matthieu; White, Ian R

2018-06-01

In multilevel settings such as individual participant data meta-analysis, a variable is 'systematically missing' if it is wholly missing in some clusters and 'sporadically missing' if it is partly missing in some clusters. Previously proposed methods to impute incomplete multilevel data handle either systematically or sporadically missing data, but frequently both patterns are observed. We describe a new multiple imputation by chained equations (MICE) algorithm for multilevel data with arbitrary patterns of systematically and sporadically missing variables. The algorithm is described for multilevel normal data but can easily be extended for other variable types. We first propose two methods for imputing a single incomplete variable: an extension of an existing method and a new two-stage method which conveniently allows for heteroscedastic data. We then discuss the difficulties of imputing missing values in several variables in multilevel data using MICE, and show that even the simplest joint multilevel model implies conditional models which involve cluster means and heteroscedasticity. However, a simulation study finds that the proposed methods can be successfully combined in a multilevel MICE procedure, even when cluster means are not included in the imputation models.

Clinical Perspective of Oxidative Stress in Sporadic ALS

Science.gov (United States)

D’Amico, Emanuele; Factor-Litvak, Pam; Santella, Regina M.; Mitsumoto, Hiroshi

2013-01-01

Sporadic amyotrophic lateral sclerosis (sALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/anti-oxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine, are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly support the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis. PMID:23797033

Nonlinear plasma experiments in geospace with gigawatts of RF power at HAARP

Energy Technology Data Exchange (ETDEWEB)

Sheerin, J. P., E-mail: jsheerin@emich.edu [Physics and Astronomy, Eastern Michigan Univ., Ypsilanti, MI 48197 (United States); Cohen, Morris B., E-mail: mcohen@gatech.edu [Electrical and Computer Engineering, Georgia Tech, Atlanta, GA 30332-0250 (United States)

2015-12-10

The ionosphere is the ionized uppermost layer of our atmosphere (from 70 – 500 km altitude) where free electron densities yield peak critical frequencies in the HF (3 – 30 MHz) range. The ionosphere thus provides a quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. High power RF experiments on ionospheric plasma conducted in the U.S. have been reported since 1970. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 – 10 MHz to the ionosphere with microsecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP’s unique features have enabled the conduct of a number of unique nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. One of the primary missions of HAARP, has been the generation of ELF (300 – 3000 Hz) and VLF (3 – 30 kHz) radio waves which are guided to global distances in the Earth

Density gradients in the solar plasma observed by interplanetary scintillation

International Nuclear Information System (INIS)

Gapper, G.R.; Hewish, A.

1981-01-01

A new technique is described which overcomes the limitation set by Fresnel filtering in previous IPS studies of the small-scale density irregularities in the solar plasma. Phase gradients introduced by irregularities larger than the Fresnel limit cause transverse displacements of the small-scale scintillation pattern. In the presence of the solar wind, such refraction effects may be revealed by simultaneous measurements of intensity scintillation at two radio frequencies. Observations show that the structure corresponding to temporal frequencies approximately 0.02 Hz is in agreement with an extrapolation of the Kolmogorov spectrum derived from spacecraft data at lower frequencies. (author)

Modeling of plasma-sheet convection: implications for substorms

International Nuclear Information System (INIS)

Erickson, G.M.

1985-01-01

An answer is suggested to the question of why plasma and magnetic energy accumulate in the Earth's magnetotail to be released in sporadic events, namely substorms. It is shown that the idea of steady convection is inconsistent with the idea of slow, approximately lossless, plasma convection in a long, closed-field-line region that extends into a long magnetotail, such as occurs during Earthward convection in the Earth's plasma sheet. This inconsistency is argued generally and demonstrated specifically using several quantitative models of the Earth's magnetospheric magnetic field. These results suggest that plasma-sheet convection is necessarily time dependent. If flux tubes are to convect adiabatically earthward, the confining magnetic pressure in the tail lobes must increase with time, and the magnetotail must evolve into a more stretched configuration. Eventually, the magnetosphere must find some way to release plasma from inner-plasma-sheet flux tubes. This suggests an obvious role for the magnetospheric substorm in the convection process. To probe this process further, a two-dimensional, self-consistent, quasi-static convection model was developed. This model self consistently includes a dipole field and can reasonably account for the effects of inner-magnetospheric shielding

Plasma skin regeneration technology.

Science.gov (United States)

Bogle, M A

2006-09-01

Plasma skin regeneration (PSR) technology uses energy delivered from plasma rather than light or radiofrequency. Plasma is the fourth state of matter in which electrons are stripped from atoms to form an ionized gas. The plasma is emitted in a millisecond pulse to deliver energy to target tissue upon contact without reliance on skin chromophores. The technology can be used at varying energies for different depths of effect, from superficial epidermal sloughing to deeper dermal heating. With the Portrait PSR device (Rhytec, Inc.) there are three treatment guidelines termed PSR1, PSR2, and PSR3. The PSR1 protocol uses a series of low-energy treatments (1.0,1.2 Joules) spaced 3 weeks apart. The PSR2 protocol uses one high-energy pass (3.0, 4.0 Joules) performed in a single treatment, and the PSR3 protocol uses two high-energy passes (3.0 4.0 Joules) performed in a single treatment. All protocols improve fine lines, textural irregularities, and dyspigmentation; however, skin tightening is probably more pronounced with the high-energy treatments.

High prevalence of exon 8 G533C mutation in apparently sporadic medullary thyroid carcinoma in Greece.

Science.gov (United States)

Sarika, H L; Papathoma, A; Garofalaki, M; Vasileiou, V; Vlassopoulou, B; Anastasiou, E; Alevizaki, M

2012-12-01

Genetic screening for ret mutation has become routine practice in the evaluation of medullary thyroid carcinoma (MTC). Approximately 25% of these tumours are familial, and they occur as components of the multiple endocrine neoplasia type 2 syndromes (MEN 2A and 2B) or familial MTC. In familial cases, the majority of mutations are found in exons 10, 11, 13, 14 or 15 of the ret gene. A rare mutation involving exon 8 (G533C) has recently been reported in familial cases of MTC in Brazil and Greece; some of these cases were originally thought to be sporadic. The aim of this study was to re-evaluate a series of sporadic cases of MTC, with negative family history, and screen them for germline mutations in exon 8. Genomic DNA was extracted from peripheral lymphocytes in 129 unrelated individuals who had previously been characterized as 'sporadic' based on the negative family history and negative screening for ret gene mutations. Samples were analysed in Applied Biosystems 7500 real-time PCR and confirmed by sequencing. The G533C exon 8 mutation was identified in 10 of 129 patients with sporadic MTC. Asymptomatic gene carriers were subsequently identified in other family members. In our study, we found that 7·75% patients with apparently sporadic MTC do carry G533C mutation involving exon 8 of ret. We feel that there is now a need to include exon 8 mutation screening in all patients diagnosed as sporadic MTC, in Greece. © 2012 Blackwell Publishing Ltd.

Influência da temperatura e do tempo de armazenamento nas dosagens bioquímicas de uréia e creatinina em soro ou plasma caninos Effect of temperature and storage time on urea and creatinine dosages from canine serum or plasma

Directory of Open Access Journals (Sweden)

S.T. Fernandes

2001-12-01

Full Text Available O trabalho teve como objetivos avaliar algumas condições de estocagem de soro e de plasma com EDTA 10% utilizados para determinação dos valores de uréia e creatinina em cães, e avaliar a possibilidade de substituir o soro pelo plasma conservado com EDTA 10%. Foram realizadas 3600 análises (1800 amostras de soro e 1800 de plasma com amostras que permaneceram em temperaturas ambiente, de refrigeração e de congelamento. As análises foram realizadas imediatamente após a obtenção da amostra (tempo 0 e após 2, 6, 12, 24, 72 horas e 30 e 60 dias após a coleta do sangue. Os resultados permitiram concluir que a uréia conservou-se por mais tempo na amostra sérica refrigerada até 30 dias e a creatinina na amostra sérica congelada até 72h. O soro mostrou mais estabilidade que o plasma em todas as condições de estoque estabelecidas.Aiming to evaluating some conditions of EDTA 10% serum and plasma storage for urea and creatinine values determinations in canines as well as analyzing the possibility of serum substitution by plasma, a total of 3600 samples (1800 serum and 1800 of plasma were analyzed at room, refrigeration and freezing temperatures. Different time intervals were used in the analysis: immediately after sampling (time 0, and at 2, 6, 12, 24, and 72 hours, and 30 and 60 days after the blood collection. The data showed that urea remains conserved for more time in the refrigerated serum sample until 30 days and the creatinine in the frozen serum sample until 72 hours. Serum showed more stability than plasma in all storage conditions established.

Ontogeny of human IgE?expressing B cells and plasma cells

OpenAIRE

Ramadani, F.; Bowen, H.; Upton, N.; Hobson, P. S.; Chan, Y.?C.; Chen, J.?B.; Chang, T. W.; McDonnell, J. M.; Sutton, B. J.; Fear, D. J.; Gould, H. J.

2016-01-01

BACKGROUND: IgE-expressing (IgE+) plasma cells (PCs) provide a continuous source of allergen specific IgE that is central to allergic responses. The extreme sparsity of IgE+ cells in vivo has confined their study almost entirely to mouse models.OBJECTIVE: To characterise the development pathway of human IgE+ PCs and to determine the ontogeny of human IgE+ PCs.METHODS: To generate human IgE+ cells we cultured tonsil B cells with IL-4 and anti-CD40. Using FACS and RT-PCR we examined the phenoty...

[The practice guideline 'Dermatomyositis, polymyositis and sporadic inclusion body myositis'

NARCIS (Netherlands)

Hoogendijk, J.E.; Bijlsma, J.W.J.; Engelen, B.G.M. van; Lindeman, E.J.M.; Royen-Kerkhof, A. van; Rie, M.A. de; Visser, M. de; Jennekens, F.G.I.

2005-01-01

This guideline presents recommendations for the diagnosis and treatment of dermatomyositis, polymyositis and sporadic inclusion body myositis (sIBM) according to the best available evidence. Characteristic skin abnormalities can be sufficient for the diagnosis of dermatomyositis. In case of doubt, a

Perfil lipídico e peroxidação de lipídeos no plasma em crianças e adolescentes com sobrepeso e obesidade

Directory of Open Access Journals (Sweden)

Lima Severina C. V. C

2004-01-01

Full Text Available OBJETIVO: Identificar o perfil lipídico e a peroxidação de lipídeos no plasma de crianças e adolescentes com sobrepeso e obesidade atendidos no Ambulatório de Endocrinologia Pediátrica do HOSPED/UFRN. MÉTODOS: Foram constituídos grupos com crianças e adolescentes com sobrepeso (n = 15, obesidade (n = 30 e controle (n = 21. O perfil lipídico foi avaliado por meio do colesterol total, LDL-colesterol, HDL-colesterol e triglicerídeos. A peroxidação de lipídeos no plasma foi medida pelo marcador malonildialdeído (MDA. A análise estatística foi realizada através do teste t de Student, teste de Tukey, ANOVA e correlação de Pearson. RESULTADOS: As alterações de colesterol total e LDL-colesterol estavam mais presentes nos grupos sobrepeso e obesidade masculinos. O HDL-colesterol mostrou-se em condições limítrofes nos grupos sobrepeso e obesidade em ambos sexos. As maiores concentrações de triglicerídeos foram registradas no grupo obesidade feminino. Identificou-se elevada peroxidação de lipídeos no plasma no grupo obesidade, principalmente no sexo masculino. CONCLUSÕES: Na amostra estudada, maiores alterações do perfil lipídico foram observadas no sexo masculino nos grupos sobrepeso e obesidade, e a peroxidação de lipídeos estava mais evidente no grupo obesidade em ambos sexos.

Crime among irregular immigrants and the influence of internal border control

OpenAIRE

Leerkes, Arjen; Engbersen, Godfried; Leun, Joanne

2012-01-01

textabstractBoth the number of crime suspects without legal status and the number of irregular or undocumented immigrants held in detention facilities increased substantially in theNetherlands between 1997 and 2003. In this period, theDutch state increasingly attempted to exclude irregular immigrants from the formal labour market and public provisions. At the same time the registered crime among irregular migrants rose. The 'marginalisation thesis' asserts that a larger number of migrants hav...

Measurements of electron density irregularities in the ionosphere of Jupiter by Pioneer 10

International Nuclear Information System (INIS)

Woo, R.; Yang, F.

1976-01-01

In this paper we demonstrate that when the frequency spectrum of the log amplitude fluctuations is used, the radio occultation experiment is a powerful tool for detecting, identifying, and studying ionospheric irregularities. Analysis of the Pioneer 10 radio occultation measurements reveals that the Jovian ionosphere possesses electron density irregularities which are very similar to those found in the earth's ionosphere. This is the first time such irregularities have been found in a planetary ionosphere other than that of earth. The Pioneer 10 results indicate that the spatial wave number spectrum of the electron density irregularities is close to the Kolmogorov spectrum and that the outer scale size is greater than the Fresnel size (6.15 km). This type of spectrum suggests that the irregularities are probably produced by the turbulent dissipation of irregularities larger than the outer scale size

When does ALS start? ADAR2-GluA2 hypothesis for the etiology of sporadic ALS

Directory of Open Access Journals (Sweden)

Takuto eHideyama

2011-11-01

Full Text Available Amyotrophic lateral sclerosis (ALS is the most common adult-onset motor neuron disease. More than 90% of ALS cases are sporadic, and the majority of sporadic ALS patients do not carry mutations in genes causative of familial ALS; therefore, investigation specifically targeting sporadic ALS is needed to discover the pathogenesis. The motor neurons of sporadic ALS patients express unedited GluA2 mRNA at the Q/R site in a disease-specific and motor neuron-selective manner. GluA2 is a subunit of the AMPA receptor, and it has a regulatory role in the Ca2+-permeability of the AMPA receptor after the genomic Q codon is replaced with the R codon in mRNA by adenosine-inosine conversion, which is mediated by adenosine deaminase acting on RNA 2 (ADAR2. Therefore, ADAR2 activity may not be sufficient to edit all GluA2 mRNA expressed in the motor neurons of ALS patients. To investigate whether deficient ADAR2 activity plays pathogenic roles in sporadic ALS, we generated genetically modified mice (AR2 in which the ADAR2 gene was conditionally knocked out in the motor neurons. AR2 mice showed an ALS-like phenotype with the death of ADAR2-lacking motor neurons. Notably, the motor neurons deficient in ADAR2 survived when they expressed only edited GluA2 in AR2/GluR-BR/R (AR2res mice, in which the endogenous GluA2 alleles were replaced by the GluR-BR allele that encoded edited GluA2. In heterozygous AR2 mice with only one ADAR2 allele, approximately 20% of the spinal motor neurons expressed unedited GluA2 and underwent degeneration, indicating that half-normal ADAR2 activity is not sufficient to edit all GluA2 expressed in motor neurons. It is likely therefore that the expression of unedited GluA2 causes the death of motor neurons in sporadic ALS. We hypothesize that a progressive downregulation of ADAR2 activity plays a critical role in the pathogenesis of sporadic ALS and that the pathological process commences when motor neurons express unedited GluA2.

Two-dimensional evaluation of an ion plasma produced by pulsed lasers extracted by non-parallel collectors

International Nuclear Information System (INIS)

Mahdieh, M H; Gavili, A

2003-01-01

Two-dimensional hydrodynamics of ion extraction from quasi-neutral plasmas has been calculated numerically for non-parallel ion extractors, and the results compared with those for the parallel case. The ions were assumed to be initially uniform with a very steep density profile at the boundaries, and held between two non-parallel metal plates as cathode and anode with fixed potentials. Experimentally, tunable pulsed lasers through stepwise photo-excitation and photo-ionization or multi-photo-ionization processes can produce such plasma. Poisson's equation was solved simultaneously with the equations of mass and momentum, assuming the Maxwell-Boltzmann distribution for electrons. Ordinary Cartesian co-ordinates are not suitable for the rotated extractor geometry; therefore using the 'algebraic method' a transformation from the physical domain into the computational rectangular plane is applied for analysing the irregular boundaries. Such a technique provides adequate resolution for the boundary layer. Using a first-order explicit upwind differencing in an appropriate transformed Cartesian co-ordinate system, the hydrodynamics of the plasma ions between the two non-parallel electrodes was evaluated. In these calculations electric potential, ion density between the two electrodes, and the extraction time were assessed, considering three separate regions for the plasma, i.e. the ion sheath where (n i >>n e ∼0), the transition region (pre-sheath) (n i = n e ), and the quasi-neutral plasma (n i -n e i ). The results were compared with those for parallel electrodes. A significant discrepancy was found between the two results. From the calculation, the non-uniform asymmetric potential contour, and the ion density contour across the plasma, were obtained for the non-parallel electrodes. For comparison with the parallel extractors, we have also obtained almost the same extraction time for the non-parallel extractors

Regular and stochastic particle motion in plasma dynamics

International Nuclear Information System (INIS)

Kaufman, A.N.

1979-08-01

A Hamiltonian formalism is presented for the study of charged-particle trajectories in the self-consistent field of the particles. The intention is to develop a general approach to plasma dynamics. Transformations of phase-space variables are used to separate out the regular, adiabatic motion from the irregular, stochastic trajectories. Several new techniques are included in this presentation

Turbulent current heating of dense plasma

International Nuclear Information System (INIS)

Suprunenko, V.A.; Sukhomlin, E.A.; Volkov, E.D.; Perepelkij, N.F.

1976-01-01

Based upon experimental results an attempt is made for systematizing and analysing conditions of experiments in anomalous resistance and turbulent heating of a plasma. The extensive program of such investigations aims at a direct practical study on quasistationary heating and plasma containment in magnetic traps. It has been shown that in real conditions turbulent heating turns out to be a far more complicated phenomenon than that described within the framework of theories developed so far. It has been established that the phenomenon alters in the transition through the critical values of electric and magnetic fields. This makes it possible to separate four characteristic experimental regimes. For all the regimes the stabilization of the electron current drift rate is typical. On the basis of the experimental results obtained an explanation is given of the sporadic character of the ultrathermal radiation in a quasistationary discharge

Influence of initial stress, irregularity and heterogeneity on Love-type ...

Indian Academy of Sciences (India)

The present paper deals with the propagation of Love-type wave in an initially stressed irregular vertically heterogeneous layer lying over an initially stressed isotropic layer and an initially stressed isotropic half- space. Two different types of irregularities, viz., rectangular and parabolic, are considered at the interface.

Finite Length Analysis of Irregular Repetition Slotted ALOHA in the Waterfall Region

OpenAIRE

Amat, Alexandre Graell i; Liva, Gianluigi

2018-01-01

A finite length analysis is introduced for irregular repetition slotted ALOHA (IRSA) that enables to accurately estimate its performance in the moderate-to-high packet loss probability regime, i.e., in the so-called waterfall region. The analysis is tailored to the collision channel model, which enables mapping the description of the successive interference cancellation process onto the iterative erasure decoding of low-density parity-check codes. The analysis provides accurate estimates of t...

Survey of 0.1- to 16-keV/e plasma sheet ion composition

International Nuclear Information System (INIS)

Lennartsson, W.; Shelley, E.G.

1986-01-01

A large statistical survey of the 0.1- to 16-keV/e plasma sheet ion composition has been carried out using data obtained by the Plasma Composition Experiment on ISEE 1 between 10 and 23 R/sub E/ during 1978 and 1979. This survey includes more than 10 times the quantity of data used in earlier studies of the same topic and makes it possible to investigate in finer detail the relationship between the ion composition and the substorm activity. The larger data base also makes it possible for the first time to study the spatial distribution of the principal ion species. As found in previous studies, the ion composition has a large variance at any given value of the AE index, but a number of distinct trends emerge when the data are averaged at each activity level. During quiet conditions the plasma sheet is dominated by ions of solar origin (H + and He ++ ), as found in earlier studies, and these ions are most numerous during extended periods of very low activity (AE< or approx. =30 γ). The quiet time density of these ions is particularly large in the flanks of the plasma sheet (GSM Yapprox. +- 10 R/sub E/), where it is about twice as large as it is near the central axis of the plasma sheet (Y = Z = 0). In contrast, the energy of these ions peaks near the central axis

E-H mode transition in low-pressure inductively coupled nitrogen-argon and oxygen-argon plasmas

International Nuclear Information System (INIS)

Lee, Young Wook; Lee, Hye Lan; Chung, T. H.

2011-01-01

This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N 2 -Ar and O 2 -Ar discharges using rf-compensated Langmuir probe measurements and optical emission spectroscopy (OES). As the ICP power increases, the emission intensities from plasma species, the electron density, the electron temperature, and the plasma potential exhibit sudden changes. The Ar content in the gas mixture and total gas pressure have been varied in an attempt to fully characterize the plasma parameters. With these control parameters varying, the changes of the transition threshold power and the electron energy distribution function (EEDF) are explored. In N 2 -Ar and O 2 -Ar discharges at low-pressures of several millitorr, the transition thresholds are observed to decrease with Ar content and pressure. It is observed that in N 2 -Ar plasmas during the transition, the shape of the EEDF changes from an unusual distribution with a flat hole near the electron energy of 3 eV in the E mode to a Maxwellian distribution in the H mode. However, in O 2 -Ar plasmas, the EEDFs in the E mode at low Ar contents show roughly bi-Maxwellian distributions, while the EEDFs in the H mode are observed to be nearly Maxwellian. In the E and H modes of O 2 -Ar discharges, the dissociation fraction of O 2 molecules is estimated using optical emission actinometry. During the E-H mode transition, the dissociation fraction of molecules is also enhanced.

Latitudinal oscillations of plasma within the Io torus

Science.gov (United States)

Cummings, W. D.; Dessler, A. J.; Hill, T. W.

1980-01-01

The equilibrium latitude and the period of oscillations about this equilibrium latitude are calculated for a plasma in a centrifugally dominated tilted dipole magnetic field representing Jupiter's inner magnetosphere. It is found that for a hot plasma the equilibrium latitude in the magnetic equator, for a cold plasma it is the centrifugal equator, and for a warm plasma it is somewhere in between. An illustrative model is adopted in which atoms are sputtered from the Jupiter-facing hemisphere of Io and escape Io's gravity to be subsequently ionized some distance from Io. Finally, it is shown that ionization generally does not occur at the equilibrium altitude, and that the resulting latitudinal oscillations provide an explanation for the irregularities in electron concentration within the torus, as reported by the radioastronomy experiment aboard Voyager I.

Modeling Laser and e-Beam Generated Plasma-Plume Experiments Using LASNEX

CERN Document Server

Ho, D

1999-01-01

The hydrodynamics code LASNEX is used to model the laser and e-beam generated plasma-plume experiments. The laser used has a wavelength of 1 (micro)m and the FWHM spot size is 1 mm. The total laser energy is 160 mJ. The simulation shows that the plume expands at a velocity of about 6 cm/(micro)s. The e-beam generated from the Experimental Test Accelerator (ETA) has 5.5 MeV and FWHM spot size ranges from 2 to 3.3 mm. From the simulations, the plasma plume expansion velocity ranges from about 3 to 6 mm/(micro)s and the velocity increases with decreasing spot size. All the simulation results reported here are in close agreement with experimental data.

Slower Dynamics and Aged Mitochondria in Sporadic Alzheimer's Disease

Science.gov (United States)

Gargini, Ricardo; García, Esther; Perry, George

2017-01-01

Sporadic Alzheimer's disease corresponds to 95% of cases whose origin is multifactorial and elusive. Mitochondrial dysfunction is a major feature of Alzheimer's pathology, which might be one of the early events that trigger downstream principal events. Here, we show that multiple genes that control mitochondrial homeostasis, including fission and fusion, are downregulated in Alzheimer's patients. Additionally, we demonstrate that some of these dysregulations, such as diminished DLP1 levels and its mitochondrial localization, as well as reduced STOML2 and MFN2 fusion protein levels, take place in fibroblasts from sporadic Alzheimer's disease patients. The analysis of mitochondrial network disruption using CCCP indicates that the patients' fibroblasts exhibit slower dynamics and mitochondrial membrane potential recovery. These defects lead to strong accumulation of aged mitochondria in Alzheimer's fibroblasts. Accordingly, the analysis of autophagy and mitophagy involved genes in the patients demonstrates a downregulation indicating that the recycling mechanism of these aged mitochondria might be impaired. Our data reinforce the idea that mitochondrial dysfunction is one of the key early events of the disease intimately related with aging. PMID:29201274

Flow and aspect angle dependence of 3-m irregularities in the auroral E region

International Nuclear Information System (INIS)

Andre, D.; Sofko, G.J.; Koehler, J.A.; McNamara, A.G.; McIntosh, B.A.

1989-01-01

Measurements from the BARS radars have been used to derive the dependence of the relative backscatter cross section on flow angle, aspect angle and irregularity drift velocity. Aspect angles between 87 degree and 81 degree and drift velocities up to 700 m/s could be covered. The variation of the backscatter cross section shows general agreement with the growth rate for two-stream instability. The flow angle dependence is approximately a cos 2 variation, whose amplitude increases with velocity and decreases with aspect angle. The aspect angle dependence shows almost no variation with velocity; the cross section decreases steeply between 87 degree and 86 degree and stays constant between 86 degree and 81 degree

Characterizing neural activities evoked by manual acupuncture through spiking irregularity measures

International Nuclear Information System (INIS)

Xue Ming; Wang Jiang; Deng Bin; Wei Xi-Le; Yu Hai-Tao; Chen Ying-Yuan

2013-01-01

The neural system characterizes information in external stimulations by different spiking patterns. In order to examine how neural spiking patterns are related to acupuncture manipulations, experiments are designed in such a way that different types of manual acupuncture (MA) manipulations are taken at the ‘Zusanli’ point of experimental rats, and the induced electrical signals in the spinal dorsal root ganglion are detected and recorded. The interspike interval (ISI) statistical histogram is fitted by the gamma distribution, which has two parameters: one is the time-dependent firing rate and the other is a shape parameter characterizing the spiking irregularities. The shape parameter is the measure of spiking irregularities and can be used to identify the type of MA manipulations. The coefficient of variation is mostly used to measure the spike time irregularity, but it overestimates the irregularity in the case of pronounced firing rate changes. However, experiments show that each acupuncture manipulation will lead to changes in the firing rate. So we combine four relatively rate-independent measures to study the irregularity of spike trains evoked by different types of MA manipulations. Results suggest that the MA manipulations possess unique spiking statistics and characteristics and can be distinguished according to the spiking irregularity measures. These studies have offered new insights into the coding processes and information transfer of acupuncture. (interdisciplinary physics and related areas of science and technology)

Advances in electron dosimetry of irregular fields

International Nuclear Information System (INIS)

Mendez V, J.

1998-01-01

In this work it is presented an advance in Electron dosimetry of irregular fields for beams emitted by linear accelerators. At present diverse methods exist which are coming to apply in the Radiotherapy centers. In this work it is proposed a method for irregular fields dosimetry. It will be allow to calculate the dose rate absorbed required for evaluating the time for the treatment of cancer patients. Utilizing the results obtained by the dosimetric system, it has been possible to prove the validity of the method describe for 12 MeV energy and for square field 7.5 x 7.5 cm 2 with percentile error less than 1 % . (Author)

Microsatellite D21D210 (GT-12) allele frequencies in sporadic Alzheimer`s disease

Energy Technology Data Exchange (ETDEWEB)

Lannfelt, L; Lilius, L; Viitanen, M; Winblad, B; Basun, H [Huddinge Hospital, Karolinska Institute, Dept. of Geriatric Medicine, (Sweden); Houlden, H; Rossor, M [St. Mary` s Hospital, Dept. of Neurology, Medical School, London (United Kingdom); Hardy, J [University of South Florida, Suncoast Alzheimer` s Disease Research Labs, Department of Psychiatry, Tampa (United States)

1995-02-01

Four disease-causing mutations have so far been described in the amyloid precursor protein gene on chromosome 21 in familial early-onset Alzheimer`s disease. Linkage analysis with a fourteen-allele microsatellite at D21S210 named GT-12 has proven useful in the elucidation of amyloid presursor protein gene involvement in Alzheimer`s disease families, as it is closely linked to the gene. Most cases of Alzheimer`s disease are thought to be sporadic and not familial. However, evidence from earlier studies suggests an important genetic contribution also in sporadic cases, where gene-environment interaction may contribute to the disease. We have determined frequencies of the GT-12 alleles in 78 Swedish and 49 British sporadic Alzheimer`s disease cases and 104 healthy elderly control subjects, to investigate if the disease associates with a particular genotype in GT-12. However, no differences in allele frequencies were observed between any of the groups. (au) (26 refs.).

Molecular profile and copy number analysis of sporadic colorectal cancer in Taiwan

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Li Ling-Hui

2011-06-01

Full Text Available Abstract Background Colorectal cancer (CRC is a major health concern worldwide, and recently becomes the most common cancer in Asia. The case collection of this study is one of the largest sets of CRC in Asia, and serves as representative data for investigating genomic differences between ethnic populations. We took comprehensive and high-resolution approaches to compare the clinicopathologic and genomic profiles of microsatellite instability (MSI vs. microsatellite stability (MSS in Taiwanese sporadic CRCs. Methods 1,173 CRC tumors were collected from the Taiwan population, and sequencing-based microsatellite typing assay was used to determine MSI and MSS. Genome-wide SNP array was used to detect CN alterations in 16 MSI-H and 13 MSS CRCs and CN variations in 424 general controls. Gene expression array was used to evaluate the effects of CN alterations, and quantitative PCR methods were used to replicate the findings in independent clinical samples. Results These 1,173 CRC tumors can be classified into 75 high-frequency MSI (MSI-H (6.4%, 96 low-frequency MSI (8.2% and 1,002 MSS (85.4%. Of the 75 MSI-H tumors, 22 had a BRAF mutation and 51 showed MLH1 promoter hypermethylation. There were distinctive differences in the extent of CN alterations between CRC MSS and MSI-H subtypes (300 Mb vs. 42 Mb per genome, p-value Conclusions Sporadic CRCs with MSI-H displayed distinguishable clinicopathologic features, which differ from those of MSS. Genomic profiling of the two types of sporadic CRCs revealed significant differences in the extent and distribution of CN alterations in the cancer genome. More than half of expressed genes showing CN differences can directly contribute to their expressional diversities, and the biological functions of the genes associated with CN changes in sporadic CRCs warrant further investigation to establish their possible clinical implications.

A genome-wide investigation of copy number variation in patients with sporadic brain arteriovenous malformation.

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Nasrine Bendjilali

Full Text Available Brain arteriovenous malformations (BAVM are clusters of abnormal blood vessels, with shunting of blood from the arterial to venous circulation and a high risk of rupture and intracranial hemorrhage. Most BAVMs are sporadic, but also occur in patients with Hereditary Hemorrhagic Telangiectasia, a Mendelian disorder caused by mutations in genes in the transforming growth factor beta (TGFβ signaling pathway.To investigate whether copy number variations (CNVs contribute to risk of sporadic BAVM, we performed a genome-wide association study in 371 sporadic BAVM cases and 563 healthy controls, all Caucasian. Cases and controls were genotyped using the Affymetrix 6.0 array. CNVs were called using the PennCNV and Birdsuite algorithms and analyzed via segment-based and gene-based approaches. Common and rare CNVs were evaluated for association with BAVM.A CNV region on 1p36.13, containing the neuroblastoma breakpoint family, member 1 gene (NBPF1, was significantly enriched with duplications in BAVM cases compared to controls (P = 2.2×10(-9; NBPF1 was also significantly associated with BAVM in gene-based analysis using both PennCNV and Birdsuite. We experimentally validated the 1p36.13 duplication; however, the association did not replicate in an independent cohort of 184 sporadic BAVM cases and 182 controls (OR = 0.81, P = 0.8. Rare CNV analysis did not identify genes significantly associated with BAVM.We did not identify common CNVs associated with sporadic BAVM that replicated in an independent cohort. Replication in larger cohorts is required to elucidate the possible role of common or rare CNVs in BAVM pathogenesis.

Cortical restricted diffusion as the predominant MRI finding in sporadic Creutzfeldt-Jakob disease

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Talbott, Sabrina D.; Sattenberg, Ronald J.; Heidenreich, Jens O. (Dept. of Radiology, Univ. of Louisville, Louisville (United States)), e-mail: sdtalb02@gwise.louisville.edu; Plato, Brian M (Dept. of Neurology, Univ. of Louisville, Louisville (United States)); Parker, John (Dept. of Pathology and Laboratory Medicine, Univ. of Louisville, Louisville (United States))

2011-04-15

Creutzfeldt-Jakob disease is a rare and fatal neurodegenerative disorder with MR findings predominantly limited to the grey matter of the cortex and the basal ganglia. Sporadic Creutzfeldt-Jakob disease can produce a spectrum of MR imaging findings of the brain, most notably on DWI and FLAIR sequences. Involvement of the basal ganglia and neocortex is the most common finding, but isolated involvement of the cortex can also be seen. We describe the clinical history and MRI findings of three patients with sporadic Creutzfeldt-Jakob disease confirmed by brain biopsy or autopsy and review the literature of imaging manifestations of this disease

Cortical restricted diffusion as the predominant MRI finding in sporadic Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Talbott, Sabrina D.; Sattenberg, Ronald J.; Heidenreich, Jens O.; Plato, Brian M; Parker, John

2011-01-01

Creutzfeldt-Jakob disease is a rare and fatal neurodegenerative disorder with MR findings predominantly limited to the grey matter of the cortex and the basal ganglia. Sporadic Creutzfeldt-Jakob disease can produce a spectrum of MR imaging findings of the brain, most notably on DWI and FLAIR sequences. Involvement of the basal ganglia and neocortex is the most common finding, but isolated involvement of the cortex can also be seen. We describe the clinical history and MRI findings of three patients with sporadic Creutzfeldt-Jakob disease confirmed by brain biopsy or autopsy and review the literature of imaging manifestations of this disease

Excitation thresholds of field-aligned irregularities and associated ionospheric hysteresis at very high latitudes observed using SPEAR-induced HF radar backscatter

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D. M. Wright

2009-07-01

Full Text Available On 10 October 2006 the SPEAR high power radar facility was operated in a power-stepping mode where both CUTLASS radars were detecting backscatter from the SPEAR-induced field-aligned irregularities (FAIs. The effective radiated power of SPEAR was varied from 1–10 MW. The aim of the experiment was to investigate the power thresholds for excitation (Pt and collapse (Pc of artificially-induced FAIs in the ionosphere over Svalbard. It was demonstrated that FAI could be excited by a SPEAR ERP of only 1 MW, representing only 1/30th of SPEAR's total capability, and that once created the irregularities could be maintained for even lower powers. The experiment also demonstrated that the very high latitude ionosphere exhibits hysteresis, where the down-going part of the power cycle provided a higher density of irregularities than for the equivalent part of the up-going cycle. Although this second result is similar to that observed previously by CUTLASS in conjunction with the Tromsø heater, the same is not true for the equivalent incoherent scatter measurements. The EISCAT Svalbard Radar (ESR failed to detect any hysteresis in the plasma parameters over Svalbard in stark contract with the measurements made using the Tromsø UHF.

Novel Genetic Variants of Sporadic Atrial Septal Defect (ASD) in a Chinese Population Identified by Whole-Exome Sequencing (WES).

Science.gov (United States)

Liu, Yong; Cao, Yu; Li, Yaxiong; Lei, Dongyun; Li, Lin; Hou, Zong Liu; Han, Shen; Meng, Mingyao; Shi, Jianlin; Zhang, Yayong; Wang, Yi; Niu, Zhaoyi; Xie, Yanhua; Xiao, Benshan; Wang, Yuanfei; Li, Xiao; Yang, Lirong; Wang, Wenju; Jiang, Lihong

2018-03-05

BACKGROUND Recently, mutations in several genes have been described to be associated with sporadic ASD, but some genetic variants remain to be identified. The aim of this study was to use whole-exome sequencing (WES) combined with bioinformatics analysis to identify novel genetic variants in cases of sporadic congenital ASD, followed by validation by Sanger sequencing. MATERIAL AND METHODS Five Han patients with secundum ASD were recruited, and their tissue samples were analyzed by WES, followed by verification by Sanger sequencing of tissue and blood samples. Further evaluation using blood samples included 452 additional patients with sporadic secundum ASD (212 male and 240 female patients) and 519 healthy subjects (252 male and 267 female subjects) for further verification by a multiplexed MassARRAY system. Bioinformatic analyses were performed to identify novel genetic variants associated with sporadic ASD. RESULTS From five patients with sporadic ASD, a total of 181,762 genomic variants in 33 exon loci, validated by Sanger sequencing, were selected and underwent MassARRAY analysis in 452 patients with ASD and 519 healthy subjects. Three loci with high mutation frequencies, the 138665410 FOXL2 gene variant, the 23862952 MYH6 gene variant, and the 71098693 HYDIN gene variant were found to be significantly associated with sporadic ASD (PASD (PASD, and supported the use of WES and bioinformatics analysis to identify disease-associated mutations.

Statin therapy and plasma vitamin E concentrations: A systematic review and meta-analysis of randomized placebo-controlled trials.

Science.gov (United States)

Sahebkar, Amirhossein; Simental-Mendía, Luis E; Ferretti, Gianna; Bacchetti, Tiziana; Golledge, Jonathan

2015-12-01

Vitamin E is one of the most important natural antioxidants, and its plasma levels are inversely associated with the progression of atherosclerosis. There have been reports suggesting a potential negative effect of statin therapy on plasma vitamin E levels. The aim of this meta-analysis was to determine the impact of statin therapy on plasma vitamin E concentrations. PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched to identify randomized placebo-controlled trials evaluating the impact of statins on plasma vitamin E concentrations from inception to February 27, 2015. A systematic assessment of bias in the included studies was performed using the Cochrane criteria. A random-effects model (using DerSimonian-Laird method) and the generic inverse variance method were used to examine the effect of statins on plasma vitamin E concentrations. Heterogeneity was quantitatively assessed using the I(2) index. Sensitivity analysis was conducted using the leave-one-out method. A meta-analysis of data from 8 randomized treatment arms including 504 participants indicated a significant reduction in plasma vitamin E concentrations following statin treatment (WMD: -16.30%, 95% CI: -16.93, -15.98, p statin therapy (WMD: 29.35%, 95% CI: 24.98, 33.72, p Statin therapy was not associated with any significant alteration in LDL vitamin E content (SMD: 0.003, 95% CI: -0.90, 0.90, p = 0.995). Findings of the present study suggest that statin therapy has no negative impact on plasma vitamin E concentrations or LDL vitamin E content. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Plasma chromatography

International Nuclear Information System (INIS)

Anon.

1984-01-01

This book examines the fundamental theory and various applications of ion mobility spectroscopy. Plasma chromatography developed from research on the diffusion and mobility of ions. Topics considered include instrument design and description (e.g., performance, spectral interpretation, sample handling, mass spectrometry), the role of ion mobility in plasma chromatography (e.g., kinetic theory of ion transport), atmospheric pressure ionization (e.g., rate equations), the characterization of isomers by plasma chromatography (e.g., molecular ion characteristics, polynuclear aromatics), plasma chromatography as a gas chromatographic detection method (e.g., qualitative analysis, continuous mobility monitoring, quantitative analysis), the analysis of toxic vapors by plasma chromatography (e.g., plasma chromatograph calibration, instrument control and data processing), the analysis of semiconductor devices and microelectronic packages by plasma chromatography/mass spectroscopy (e.g., analysis of organic surface contaminants, analysis of water in sealed electronic packages), and instrument design and automation (hardware, software)

Clinicopathologic factors identify sporadic mismatch repair-defective colon cancers

DEFF Research Database (Denmark)

Halvarsson, Britta; Anderson, Harald; Domanska, Katarina

2008-01-01

Identification of sporadic mismatch repair (MMR)-defective colon cancers is increasingly demanded for decisions on adjuvant therapies. We evaluated clinicopathologic factors for the identification of these prognostically favorable tumors. Histopathologic features in 238 consecutive colon cancers...... and excluded 61.5% of the tumors from MMR testing. This clinicopathologic index thus successfully selects MMR-defective colon cancers. Udgivelsesdato: 2008-Feb...

Differences in histological features and PD-L1 expression between sporadic microsatellite instability and Lynch-syndrome-associated disease in Japanese patients with colorectal cancer.

Science.gov (United States)

Yamada, Rin; Yamaguchi, Tatsuro; Iijima, Takeru; Wakaume, Rika; Takao, Misato; Koizumi, Koichi; Hishima, Tsunekazu; Horiguchi, Shin-Ichiro

2018-06-01

The field of immunotherapy has recently focused on cancers with microsatellite instability (MSI). These cancers include both Lynch-syndrome-associated tumors, which are caused by mismatch repair (MMR) germline mutations, and sporadic MSI tumors, which are mainly attributed to MLH1 promoter methylation. The present study aimed to clarify differences in the histological and PD-L1 expression profiles between these two types of MSI cancers in Japanese patients. Among 908 cases of colorectal cancer treated via surgical resection from 2008 to 2014, we identified 64 MSI cancers, including 36 sporadic MSI and 28 Lynch-syndrome-associated cancers, using a BRAF V600E mutation analysis and MLH1 methylation analysis. Of the latter subgroup, 21 (75%) harbored MMR germline mutations. The following were more frequent with sporadic MSI than with Lynch syndrome associated cancers: poor differentiation (50.0 vs. 7.1%, P = 0.0002), especially solid type (30.6 vs. 3.6%, P = 0.0061); medullary morphology (19.4 and 0%, P = 0.015), Crohn-like lymphoid reaction (50.0 vs. 25.0%, P = 0.042), and PD-L1 expression (25.0 vs. 3.6%, P = 0.034). However, the groups did not differ in terms of the mean invasive front and intratumoral CD8-positive cell densities. In a logistic regression analysis, PD-L1 expression correlated with poor differentiation (odds ratio: 7.65, 95% confidence interval: 1.55-37.7, P = 0.012), but not with the difference between sporadic MSI cancer and Lynch-syndrome-associated cancer (odds ratio: 4.74, 95% confidence interval: 0.50-45.0, P = 0.176). Therefore, compared with Lynch-syndrome-associated cancers, sporadic MSI cancers are more frequently solid, poorly differentiated medullary cancers that express PD-L1.

Um estudo sobre a construção, desempenho e implementação em VHDL de códigos LDPC binários, irregulares e estruturados para aplicação em comunicações ópticas

OpenAIRE

Antônio Unias de Lucena

2015-01-01

Resumo: O emprego de códigos LDPC em comunicações ópticas vem recebendo especial atenção nos últimos anos devido à sua elevada capacidade de correção de erros, fato que possibilita enlaces mais longos e com maior capacidade de transmissão. A presente dissertação apresenta um estudo de códigos LDPC binários, irregulares e estruturados (IE-LDPC), bem como, uma comparação do desempenho de dois algoritmos de decodificação comumente utilizados na decodificação de códigos LDPC: o algoritmo soma-pro...

Study of Track Irregularity Time Series Calibration and Variation Pattern at Unit Section

Directory of Open Access Journals (Sweden)

Chaolong Jia

2014-01-01

Full Text Available Focusing on problems existing in track irregularity time series data quality, this paper first presents abnormal data identification, data offset correction algorithm, local outlier data identification, and noise cancellation algorithms. And then proposes track irregularity time series decomposition and reconstruction through the wavelet decomposition and reconstruction approach. Finally, the patterns and features of track irregularity standard deviation data sequence in unit sections are studied, and the changing trend of track irregularity time series is discovered and described.

Molecular Cytogenetic Characterization Identified the Murine B-Cell Lymphoma Cell Line A-20 as a Model for Sporadic Burkitt's Lymphoma.

Science.gov (United States)

Guja, Karolina; Liehr, Thomas; Rincic, Martina; Kosyakova, Nadezda; Hussein Azawi, Shaymaa S

2017-11-01

Here, we report the first molecular cytogenetic characterization of the BALB/cAnN mouse derived B-cell non-Hodgkin lymphoma (B-cell NHL) cell lines A-20. Even though previously used as a model for testing of, for example, dexametason, up to present, no data in the genetic properties of A-20 were available. The present study closed this gap and provides evidence that A-20 is a model for B-cell NHL subgroup sporadic Burkitt's lymphoma. C-myc oncogene is involved in a translocation and copy number alterations as gain of murine 14q material could be observed. Interestingly, the cell line showed the karyotype 39,X,-X or -Y,t(2;15)(qE5;qD2),del(6)(qB3qC3),del(9)(qA3qA4),dup(14)(qE1qE4) in ~95% of the cells, being exceptionally stable for cell lines being established 38 years ago. Still, ~5% of the cells showed polyploidization followed by chromothripsis. It remains to be determined if this can be observed also in other cell lines, just has not been reported yet, and/or if it is a unique feature of A-20. Overall, finally here, the necessary genetic data to identify A-20 as a model for human sporadic Burkitt's lymphoma are provided.

Measuring sporadic gastrointestinal illness associated with drinking water - an overview of methodologies.

Science.gov (United States)

Bylund, John; Toljander, Jonas; Lysén, Maria; Rasti, Niloofar; Engqvist, Jannes; Simonsson, Magnus

2017-06-01

There is an increasing awareness that drinking water contributes to sporadic gastrointestinal illness (GI) in high income countries of the northern hemisphere. A literature search was conducted in order to review: (1) methods used for investigating the effects of public drinking water on GI; (2) evidence of possible dose-response relationship between sporadic GI and drinking water consumption; and (3) association between sporadic GI and factors affecting drinking water quality. Seventy-four articles were selected, key findings and information gaps were identified. In-home intervention studies have only been conducted in areas using surface water sources and intervention studies in communities supplied by ground water are therefore needed. Community-wide intervention studies may constitute a cost-effective alternative to in-home intervention studies. Proxy data that correlate with GI in the community can be used for detecting changes in the incidence of GI. Proxy data can, however, not be used for measuring the prevalence of illness. Local conditions affecting water safety may vary greatly, making direct comparisons between studies difficult unless sufficient knowledge about these conditions is acquired. Drinking water in high-income countries contributes to endemic levels of GI and there are public health benefits for further improvements of drinking water safety.

The relationship between maternal and neonatal umbilical cord plasma homocyst(e)ine suggests a potential role for maternal homocyst(e)ine in fetal metabolism.

Science.gov (United States)

Malinow, M R; Rajkovic, A; Duell, P B; Hess, D L; Upson, B M

1998-02-01

Data on fetal blood homocyst(e)ine concentrations are not available. We tested the hypothesis that homocyst(e)ine crosses the maternal/placental/fetal interphases and is sequestered by the fetus. The concentration of homocyst(e)ine was determined at parturition in peripheral venous plasma from 35 nulliparous healthy pregnant women and umbilical arterial and venous plasma from their conceptus. Findings demonstrated a descending concentration gradient of plasma homocyst(e)ine from maternal vein to umbilical vein and to umbilical artery; the decrease at each interphase approximated 1 micromol/L. The neonate weight and gestational age were inversely related to maternal homocyst(e)ine concentrations. The umbilical vein to umbilical artery homocyst(e)ine decrement suggests that uptake of homocyst(e)ine occurs in the fetus. The likely incorporation of homocyst(e)ine into the fetal metabolic cycle may implicate maternal homocyst(e)ine as having a potential nutritional role in the fetus. Further studies are required to explain the role of homocyst(e)ine in fetal metabolism and development.

On The Ion Drift Contribution To The Phase Velocity of Electrojet Irregularities

Science.gov (United States)

Uspensky, M.; Koustov, A.; Janhunen, P.; Pellinen, R.; Danskin, D.; Nozawa, S.

The ion drift effect is often ignored in the interpretation of VHF Doppler measure- ments. For example, in the STARE experiment it is assumed that the line-of-sight velocity measured at large flow angles is simply a cosine component of the true elec- tron drift. Previous studies seem to support this assumption, though only to a certain degree. In this study we consider a 3.5-hour morning event of joint STARE-EISCAT observa- tions for which the STARE-Finland radar velocity was mainly larger than the EISCAT convection component. A moderate 5-20 deg offset between the EISCAT convection azimuth and its STARE estimate was also observed. We show that both the STARE- Finland radar velocity "over-speed" and the azimuthal offset between the EISCAT and STARE convection vectors can be explained by fluid plasma theory arguments if the ion drift contribution to the irregularity phase velocity under the condition of moder- ate backscatter off-orthogonality is taken into account. The ion effects were enhanced because of a lifting up of the entire E-region seen by the EISCAT. It perhaps resulted in an increase of the STARE echo heights and aspect angles. The latter are of the order of 1 deg at the top of the electrojet layer. We also compare STARE convection magni- tudes and true velocities measured by the EISCAT to study the potential impact of the ion motions on the STARE velocity estimates.

SARC006: Phase II Trial of Chemotherapy in Sporadic and Neurofibromatosis Type 1 Associated Chemotherapy-Naive Malignant Peripheral Nerve Sheath Tumors

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Christine S. Higham

2017-01-01

Full Text Available Background. Worse chemotherapy response for neurofibromatosis type 1- (NF1- associated compared to sporadic malignant peripheral nerve sheath tumors (MPNST has been reported. Methods. We evaluated the objective response (OR rate of patients with AJCC Stage III/IV chemotherapy-naive NF1 MPNST versus sporadic MPNST after 4 cycles of neoadjuvant chemotherapy, 2 cycles of ifosfamide/doxorubicin, and 2 cycles of ifosfamide/etoposide. A Simon optimal two-stage design was used (target response rate 40%. Results. 34 NF1 (median age 33 years and 14 sporadic (median age 40 years MPNST patients enrolled. Five of 28 (17.9% evaluable NF1 MPNST patients had a partial response (PR, as did 4 of 9 (44.4% patients with sporadic MPNST. Stable disease (SD was achieved in 22 NF1 and 4 sporadic MPNST patients. In both strata, results in the initial stages met criteria for expansion of enrollment. Only 1 additional PR was observed in the expanded NF1 stratum. Enrollment was slower than expected and the trial closed before full accrual. Conclusions. This trial was not powered to detect differences in response rates between NF1 and sporadic MPNST. While the OR rate was lower in NF1 compared to sporadic MPNST, qualitative responses were similar, and disease stabilization was achieved in most patients.

Homocyst(e)ine-lowering therapy does not affect plasma asymmetrical dimethylarginine concentrations in patients with peripheral artery disease.

Science.gov (United States)

Ziegler, Sophie; Mittermayer, Friedrich; Plank, Christina; Minar, Erich; Wolzt, Michael; Schernthaner, Gerit-Holger

2005-04-01

Elevated plasma asymmetrical dimethylarginine (ADMA) is suggested to contribute to hyperhomocyst(e)ine-related vascular dysfunction in patients with peripheral artery disease (PAD). The present trial investigated whether homocyst(e)ine (Hcy)-lowering therapy with vitamin-B (vit-B) and folic acid affects plasma concentrations of ADMA in patients with PAD and hyperhomocyst(e)inemia. Forty-nine subjects (15 women, 34 men) with PAD and fasting plasma total Hcy concentrations greater than 15 micromol/liter were randomized to receive either oral vit-B and folic acid therapy (n = 27) or placebo (n = 22) for 6 wk. Fasting venous blood samples were monitored for plasma total Hcy, vit-B12 and folate, ADMA, symmetric dimethylarginine, L-arginine, and high-sensitivity C-reactive protein. After 6 wk, plasma Hcy concentrations were decreased, and concentrations of vit-B12 and folate were elevated in patients with vitamin supplementation (all P < 0.05 vs. baseline) and unchanged in the placebo group. Dimethylarginine plasma concentrations were not affected by treatment. High-sensitivity C-reactive protein correlated with ADMA plasma concentrations (r = 0.29; P < 0.01). The lack of vit-B and folic acid therapy on plasma concentrations of ADMA renders a role of extracellular methylarginines unlikely to be involved in the pathophysiology of hyperhomocyst(e)inemia and its complications.

MRI of sporadic Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Kong, A.; Vliet, A. Van der.

2008-01-01

Full text: The key MRI findings in five cases of sporadic Creutzfeldt-Jakob disease (CJD) are illustrated with four 'definite' and one 'probable' according to World Health Organization criteria. Close attention to fluid-attenuation inversion recovery and diffusion-weighted imaging sequences are important for diagnosis, noting especially restricted diffusion in cortical and deep grey matter. Our study and those of others show predominant cortical, caudate and thalamic involvement. This pattern is highly sensitive and specific for the diagnosis. Fluid-attenuation inversion recovery and diffusion-weighted imaging signal abnormality becomes progressively more extensive and bilateral as disease progresses, but may become less pronounced in end-stage disease because of atrophy.

Drift velocities of 150-km Field-Aligned Irregularities observed by the Equatorial Atmosphere Radar

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Yuichi Otsuka

2013-11-01

Full Text Available Between 130 and 170 km altitude in the daytime ionosphere, the so-called 150-km field-aligned irregularities (FAIs have been observed since the 1960s at equatorial regions with several very high frequency (VHF radars. We report statistical results of 150-km FAI drift velocities on a plane perpendicular to the geomagnetic field, acquired by analyzing the Doppler velocities of 150-km FAIs observed with the Equatorial Atmosphere Radar (EAR at Kototabang, Indonesia during the period from Aug. 2007 to Oct. 2009. We found that the southward/upward perpendicular drift velocity of the 150-km FAIs tends to decrease in the afternoon and that this feature is consistent with that of F-region plasma drift velocities over the magnetic equator. The zonal component of the 150-km FAI drift velocity is westward and decreases with time, whereas the F-region plasma drift velocity observed with the incoherent scatter radar at Jicamarca, Peru, which is westward, reaches a maximum at about noon. The southward/upward and zonal drift velocities of the 150-km FAIs are smaller than that of the F-region plasma drift velocity by approximately 3 m/s and 25 m/s, respectively, on average. The large difference between the 150-km FAI and F-region plasma drift velocities may not arise from a difference in the magnetic latitudes at which their electric fields are generated. Electric fields generated at the altitude at which the 150-km FAIs occur may not be negligible.

Characterizing spontaneous irregular behavior in coupled map lattices

International Nuclear Information System (INIS)

Dobyns, York; Atmanspacher, Harald

2005-01-01

Two-dimensional coupled map lattices display, in a specific parameter range, a stable phase (quasi-) periodic in both space and time. With small changes to the model parameters, this stable phase develops spontaneous eruptions of non-periodic behavior. Although this behavior itself appears irregular, it can be characterized in a systematic fashion. In particular, parameter-independent features of the spontaneous eruptions may allow useful empirical characterizations of other phenomena that are intrinsically hard to predict and reproduce. Specific features of the distributions of lifetimes and emergence rates of irregular states display such parameter-independent properties

Characterizing spontaneous irregular behavior in coupled map lattices

Energy Technology Data Exchange (ETDEWEB)

Dobyns, York [PEAR, Princeton University Princeton, NJ 08544-5263 (United States); Atmanspacher, Harald [Institut fuer Grenzgebiete der Psychologie und Psychohygiene Wilhelmstrasse 3a, Freiburg 79098 (Germany)]. E-mail: haa@igpp.de

2005-04-01

Two-dimensional coupled map lattices display, in a specific parameter range, a stable phase (quasi-) periodic in both space and time. With small changes to the model parameters, this stable phase develops spontaneous eruptions of non-periodic behavior. Although this behavior itself appears irregular, it can be characterized in a systematic fashion. In particular, parameter-independent features of the spontaneous eruptions may allow useful empirical characterizations of other phenomena that are intrinsically hard to predict and reproduce. Specific features of the distributions of lifetimes and emergence rates of irregular states display such parameter-independent properties.

Magnetic-field-aligned characteristics of plasma bubbles in the nighttime equatorial ionosphere

International Nuclear Information System (INIS)

Tsunoda, R.T.

1980-01-01

Measurements of both incoherent-scatter (IS) and backscatter from field-aligned irregularities (FAI) were made in 1978 with ALTAIR, a fully-steerable high-power radar, to investigate the magnetic-field-aligned characteristics of equatorial plasma bubbles. By operating the radar in a latitude-scan IS mode it was possible to map the location and percentage depletion of plasma bubbles as a function of altitude. By showing that backscatter from FAI is spatially collocated with the upper wall of plasma bubbles it was possible to use the spatial displacement of a field aligned backscatter region to estimate the upward bubble velocity. Besides showing that plasma bubbles are indeed aligned along magnetic field lines, this data set is used to show that a plasma bubble with a percentage depletion of as much as 90% does not have as large an upward velocity as predicted by two-dimensional models. Instead, the inferred bubble velocity is shown to be in better agreement with the bubble velocity predicted by theoretical models using flux-integrated values of electron density and Pedersen conductivity. The need to use flux-tube-integrated values when comparing theory and observation is further stressed by the presence of a non-uniform latitudinal distribution of electron density (i.e. the equatorial anomaly) that was found in the latitude-scan data. (author)

Plasma-implantation-based surface modification of metals with single-implantation mode

Science.gov (United States)

Tian, X. B.; Cui, J. T.; Yang, S. Q.; Fu, Ricky K. Y.; Chu, Paul K.

2004-12-01

Plasma ion implantation has proven to be an effective surface modification technique. Its biggest advantage is the capability to treat the objects with irregular shapes without complex manipulation of target holder. Many metal materials such as aluminum, stainless steel, tool steel, titanium, magnesium etc, has been treated using this technique to improve their wear-resistance, corrosion-resistance, fatigue-resistance, oxidation-resistance, bio-compatiblity etc. However in order to achieve thicker modified layers, hybrid processes combining plasma ion implantation with other techniques have been frequently employed. In this paper plasma implantation based surface modification of metals using single-implantation mode is reviewed.

Dose calculations for irregular fields using three-dimensional first-scatter integration

International Nuclear Information System (INIS)

Boesecke, R.; Scharfenberg, H.; Schlegel, W.; Hartmann, G.H.

1986-01-01

This paper describes a method of dose calculations for irregular fields which requires only the mean energy of the incident photons, the geometrical properties of the irregular field and of the therapy unit, and the attenuation coefficient of tissue. The method goes back to an approach including spatial aspects of photon scattering for inhomogeneities for the calculation of dose reduction factors as proposed by Sontag and Cunningham (1978). It is based on the separation of dose into a primary component and a scattered component. The scattered component can generally be calculated for each field by integration over dose contributions from scattering in neighbouring volume elements. The quotient of this scattering contribution in the irregular field and the scattering contribution in the equivalent open field is then the correction factor for scattering in an irregular field. A correction factor for the primary component can be calculated if the attenuation of the photons in the shielding block is properly taken into account. The correction factor is simply given by the quotient of primary photons of the irregular field and the primary photons of the open field. (author)

Ionospheric irregularities at low latitudes in the American sector

International Nuclear Information System (INIS)

Nakamura, Y.

1981-10-01

A detailed analysis of the atomic oxigem airglow emission at the wavelength of 6300 A observed at Cachoeira Paulista (22 0 41'S, 45 0 00'W) shows that intensity perturbations frequently occur and propagate from north to south and from west to east. Such irregularities originated in the ionospheric F region and occur essencially during the premidnight period. These perturbations have a high frequency of occurrence during spring and summer and are rare during winter and fall. The disturbances are correlated with range type spread F detected over Cachoeira Paulista, and have characteristics similar to equatorial ionospheric plasma bubbles (i.e., similar seazonal variation, time of occurrence, ionogram signatures, direction and speed of propagation, etc.). A numerical simulation is carried out for the generation and evolution of ionospheric bubbles based on the theory of the collisional Rayleigh-Taylor instability for the equatorial and Cachoeira Paulista regions. Also a study was made of the, evolution of the bubble as a function of the electron density profile and as a function of the amplitude of the initial density perturbation. Assuming the electron density profile perturbed by the bubble, the [OI] 6300 A intensity was calculated for various latitudes arbitrarily taken within the photometer scanning range. The bubble was assumed to be aligned with the Earth's magnetic field and extending from higher altitudes at the equatorial region down to be arbitrary height of 150 Km at which a negligible conductivity is assumed. It was also assumed that the bubble was moving upwards with the velocity of 120 m/s, which in turn was estimated from initial numerical simulation results. The airglow calculation results show that as the bubble goes up, the disturbances in the airglow intensity propagate from north to south, in accord with observed experimental results. (Author) [pt

Using forbidden ordinal patterns to detect determinism in irregularly sampled time series.

Science.gov (United States)

Kulp, C W; Chobot, J M; Niskala, B J; Needhammer, C J

2016-02-01

It is known that when symbolizing a time series into ordinal patterns using the Bandt-Pompe (BP) methodology, there will be ordinal patterns called forbidden patterns that do not occur in a deterministic series. The existence of forbidden patterns can be used to identify deterministic dynamics. In this paper, the ability to use forbidden patterns to detect determinism in irregularly sampled time series is tested on data generated from a continuous model system. The study is done in three parts. First, the effects of sampling time on the number of forbidden patterns are studied on regularly sampled time series. The next two parts focus on two types of irregular-sampling, missing data and timing jitter. It is shown that forbidden patterns can be used to detect determinism in irregularly sampled time series for low degrees of sampling irregularity (as defined in the paper). In addition, comments are made about the appropriateness of using the BP methodology to symbolize irregularly sampled time series.

Sporadic Endolymphatic Sac Tumor-A Very Rare Cause of Hearing Loss, Tinnitus, and Dizziness

DEFF Research Database (Denmark)

Schnack, Didde Trærup; Kiss, Katalin; Hansen, Søren

2017-01-01

Sporadic endolymphatic sac tumor is a very rare neoplasm. It is low malignant, locally destructive and expansive, but non-metastasizing. The tumor is very rare in the sporadic form, but more often associated with Von Hippel-Lindau disease. A 65-year old man with left sided tinnitus and hearing loss......-operative freeze-microscopy showed inflammation tissue, whereas subsequent microscopy showed papillary-cystic endolymphatic sac tumor. Endolymphatic sac tumor is a rare neoplasm. The tumor may present with asymmetrically sensory neural hearing loss with or without tinnitus, dizziness and facial nerve paresis...

Physical function and muscle strength in sporadic inclusion body myositis

DEFF Research Database (Denmark)

Jørgensen, Anders N; Aagaard, Per; Nielsen, Jakob L

2017-01-01

INTRODUCTION: In this study, self-reported physical function, functional capacity, and isolated muscle function were investigated in sporadic inclusion body myositis (sIBM) patients. METHODS: The 36-item Short Form (SF-36) Health Survey and 2-min walk test (2MWT), timed up & go test (TUG), and 30-s...

Molecular diversity in irregular or refugee immigrant patients with HBV-genotype-E infection living in the metropolitan area of Naples.

Science.gov (United States)

Sagnelli, Caterina; Ciccozzi, Massimo; Coppola, Nicola; Minichini, Carmine; Lo Presti, Alessandra; Starace, Mario; Alessio, Loredana; Macera, Margherita; Cella, Eleonora; Gualdieri, Luciano; Caprio, Nunzio; Pasquale, Giuseppe; Sagnelli, Evangelista

2017-06-01

In a recent testing in the metropolitan area of Naples, Italy, on 945 irregular immigrants or refugees, 87 HBsAg chronic carriers were identified, 53 of whom were infected by HBV-genotype E. The aim of the present study was to identify the genetic diversity of HBV-genotype E in these 53 immigrants. The 53 immigrant patients with HBV-genotype-E infection were born in Africa, central or eastern Asia, eastern Europe or Latin America. These patients had been seen for a clinical consultation at one of the four first-level units from January 2012 to 2013. The first dataset contained 53 HBV-S gene isolates plus 128 genotype/subgenotype specific reference sequences downloaded from the National Center for Biotechnology Information. The second dataset, comprising the 53 HBV-S gene isolates, previously classified as HBV-genotype E, was used to perform the time-scaled phylogeny reconstruction using a Bayesian approach. Phylogenetic analysis showed that all 53 HBV-S isolates belonged to HBV-genotype E. Bayes factor analysis showed that the relaxed clock exponential growth model fitted the data significantly better than the other models. The time-scaled Bayesian phylogenetic tree of the second dataset showed that the root of the tree dated back to the year 1990 (95% HPD:1984-2000). Four statistically supported clusters were identified. Cluster A dated back to 2012 (95% HPD:1997-2012); cluster B dated back to 2008 (95% HPD:2001-2015); cluster C to 2006 (95% HPD:1999-2013); cluster D to 2004 (95% HPD:1998-2011). This study disclosed the genetic evolution and phylogenesis in a group of HBV-genotype-E-infected immigrants. J. Med. Virol. 89:1015-1024, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Nanoparticles rapidly assess specific IgE in plasma

International Nuclear Information System (INIS)

Ashraf, Sarmadia; Qadri, Shahnaz; Al-Ramadi, Basel; Haik, Yousef

2012-01-01

Allergy is the sixth leading cause of chronic disease in the world. This study demonstrates the feasibility of detecting allergy indicators in human plasma, noninvasively, at the point of care and with a comparable efficiency and reduced turnaround time compared with the gold standard. Peanut allergy was utilized as a model due to its widespread occurrence among the US population and fatality if not treated. The detection procedure utilized magnetic nanoparticles that were coated with an allergen layer (peanut protein extract). Peanut immunoglobulin E (IgE) was detected in concentrations close to the minimum detection range of CAP assay. The results were obtained in minutes compared with the CAP assay which requires more than 3 h. (paper)

Sporadic adult onset primary torsion dystonia is a genetic disorder by the temporal discrimination test.

LENUS (Irish Health Repository)

Kimmich, Okka

2012-02-01

Adult-onset primary torsion dystonia is an autosomal dominant disorder with markedly reduced penetrance; patients with sporadic adult-onset primary torsion dystonia are much more prevalent than familial. The temporal discrimination threshold is the shortest time interval at which two stimuli are detected to be asynchronous and has been shown to be abnormal in adult-onset primary torsion dystonia. The aim was to determine the frequency of abnormal temporal discrimination thresholds in patients with sporadic adult-onset primary torsion dystonia and their first-degree relatives. We hypothesized that abnormal temporal discrimination thresholds in first relatives would be compatible with an autosomal dominant endophenotype. Temporal discrimination thresholds were examined in 61 control subjects (39 subjects <50 years of age; 22 subjects >50 years of age), 32 patients with sporadic adult-onset primary torsion dystonia (cervical dystonia n = 30, spasmodic dysphonia n = 1 and Meige\\'s syndrome n = 1) and 73 unaffected first-degree relatives (36 siblings, 36 offspring and one parent) using visual and tactile stimuli. Z-scores were calculated for all subjects; a Z > 2.5 was considered abnormal. Abnormal temporal discrimination thresholds were found in 1\\/61 (2%) control subjects, 27\\/32 (84%) patients with adult-onset primary torsion dystonia and 32\\/73 (44%) unaffected relatives [siblings (20\\/36; 56%), offspring (11\\/36; 31%) and one parent]. When two or more relatives were tested in any one family, 22 of 24 families had at least one first-degree relative with an abnormal temporal discrimination threshold. The frequency of abnormal temporal discrimination thresholds in first-degree relatives of patients with sporadic adult-onset primary torsion dystonia is compatible with an autosomal dominant disorder and supports the hypothesis that apparently sporadic adult-onset primary torsion dystonia is genetic in origin.

Sporadic adult onset primary torsion dystonia is a genetic disorder by the temporal discrimination test.

Science.gov (United States)

Kimmich, Okka; Bradley, David; Whelan, Robert; Mulrooney, Nicola; Reilly, Richard B; Hutchinson, Siobhan; O'Riordan, Sean; Hutchinson, Michael

2011-09-01

Adult-onset primary torsion dystonia is an autosomal dominant disorder with markedly reduced penetrance; patients with sporadic adult-onset primary torsion dystonia are much more prevalent than familial. The temporal discrimination threshold is the shortest time interval at which two stimuli are detected to be asynchronous and has been shown to be abnormal in adult-onset primary torsion dystonia. The aim was to determine the frequency of abnormal temporal discrimination thresholds in patients with sporadic adult-onset primary torsion dystonia and their first-degree relatives. We hypothesized that abnormal temporal discrimination thresholds in first relatives would be compatible with an autosomal dominant endophenotype. Temporal discrimination thresholds were examined in 61 control subjects (39 subjects 50 years of age), 32 patients with sporadic adult-onset primary torsion dystonia (cervical dystonia n = 30, spasmodic dysphonia n = 1 and Meige's syndrome n = 1) and 73 unaffected first-degree relatives (36 siblings, 36 offspring and one parent) using visual and tactile stimuli. Z-scores were calculated for all subjects; a Z > 2.5 was considered abnormal. Abnormal temporal discrimination thresholds were found in 1/61 (2%) control subjects, 27/32 (84%) patients with adult-onset primary torsion dystonia and 32/73 (44%) unaffected relatives [siblings (20/36; 56%), offspring (11/36; 31%) and one parent]. When two or more relatives were tested in any one family, 22 of 24 families had at least one first-degree relative with an abnormal temporal discrimination threshold. The frequency of abnormal temporal discrimination thresholds in first-degree relatives of patients with sporadic adult-onset primary torsion dystonia is compatible with an autosomal dominant disorder and supports the hypothesis that apparently sporadic adult-onset primary torsion dystonia is genetic in origin.

CpG methylation of APC promoter 1A in sporadic and familial breast cancer patients.

Science.gov (United States)

Debouki-Joudi, Saoussen; Trifa, Fatma; Khabir, Abdelmajid; Sellami-Boudawara, Tahia; Frikha, Mounir; Daoud, Jamel; Mokdad-Gargouri, Raja

2017-01-01

Tumour suppressor gene (TSG) silencing through promoter hypermethylation plays an important role in cancer initiation. The aim of this study was to assess the extent of methylation of APC gene promoter in 91 sporadic and 44 familial cases of Tunisian patients with breast cancer (BC) in. The frequency of APC promoter methylation is somewhat similar for sporadic and familial breast cancer cases, (52.1%, and 54.5% respectively). For sporadic breast cancer patients, there was a significant correlation of APC promoter hypermethylation with TNM stage (p = 0.024) and 3-year survival (p = 0.025). Regarding the hormonal status (HR), we found significant association between negativity to PR and unmethylated APC (p= 0.005) while ER and Her2/neu are not correlated. Moreover, unmethylated APC promoter is more frequent in tumours expressing at least one out the 3 proteins compared to triple negative cases (p= 0.053). On the other hand, aberrant methylation of APC was associated with tumour size (p = 0.036), lymph node (p = 0.028), distant metastasis (p = 0.031), and 3-year survival (p = 0.046) in the group of patients with familial breast cancer. Moreover, patients with sporadic breast cancer displaying the unmethylated profile have a significant prolonged overall survival compared to those with the methylated pattern of APC promoter (p log rank = 0.008). Epigenetic change at the CpG islands in the APC promoter was associated with the silence of its transcript and the loss of protein expression suggesting that this event is the main mechanism regulating the APC expression in breast cancer. In conclusion, our data showed that the loss of APC through aberrant methylation is associated with the aggressive behavior of both sporadic and familial breast cancer in Tunisian patients.

On the Automatic Parallelization of Sparse and Irregular Fortran Programs

Directory of Open Access Journals (Sweden)

Yuan Lin

1999-01-01

Full Text Available Automatic parallelization is usually believed to be less effective at exploiting implicit parallelism in sparse/irregular programs than in their dense/regular counterparts. However, not much is really known because there have been few research reports on this topic. In this work, we have studied the possibility of using an automatic parallelizing compiler to detect the parallelism in sparse/irregular programs. The study with a collection of sparse/irregular programs led us to some common loop patterns. Based on these patterns new techniques were derived that produced good speedups when manually applied to our benchmark codes. More importantly, these parallelization methods can be implemented in a parallelizing compiler and can be applied automatically.

NEOWISE: OBSERVATIONS OF THE IRREGULAR SATELLITES OF JUPITER AND SATURN

Energy Technology Data Exchange (ETDEWEB)

Grav, T. [Planetary Science Institute, Tucson, AZ 85719 (United States); Bauer, J. M.; Mainzer, A. K.; Masiero, J. R.; Sonnett, S.; Kramer, E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Nugent, C. R.; Cutri, R. M., E-mail: tgrav@psi.edu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

2015-08-10

We present thermal model fits for 11 Jovian and 3 Saturnian irregular satellites based on measurements from the WISE/NEOWISE data set. Our fits confirm spacecraft-measured diameters for the objects with in situ observations (Himalia and Phoebe) and provide diameters and albedo for 12 previously unmeasured objects, 10 Jovian and 2 Saturnian irregular satellites. The best-fit thermal model beaming parameters are comparable to what is observed for other small bodies in the outer solar system, while the visible, W1, and W2 albedos trace the taxonomic classifications previously established in the literature. Reflectance properties for the irregular satellites measured are similar to the Jovian Trojan and Hilda Populations, implying common origins.

E-region decameter-scale plasma waves observed by the dual TIGER HF radars

Directory of Open Access Journals (Sweden)

B. A. Carter

2009-01-01

Full Text Available The dual Tasman International Geospace Environment Radar (TIGER HF radars regularly observe E-region echoes at sub-auroral magnetic latitudes 58°–60° S including during geomagnetic storms. We present a statistical analysis of E-region backscatter observed in a period of ~2 years (late 2004–2006 by the TIGER Bruny Island and Unwin HF radars, with particular emphasis on storm-time backscatter. It is found that the HF echoes normally form a 300-km-wide band at ranges 225–540 km. In the evening sector during geomagnetic storms, however, the HF echoes form a curved band joining to the F-region band at ~700 km. The curved band lies close to the locations where the geometric aspect angle is zero, implying little to no refraction during geomagnetic storms, which is an opposite result to what has been reported in the past. The echo occurrence, Doppler velocity, and spectral width of the HF echoes are examined in order to determine whether new HF echo types are observed at sub-auroral latitudes, particularly during geomagnetic storms. The datasets of both TIGER radars are found to be dominated by low-velocity echoes. A separate population of storm-time echoes is also identified within the datasets of both radars with most of these echoes showing similar characteristics to the low-velocity echo population. The storm-time backscatter observed by the Bruny Island radar, on the other hand, includes near-range echoes (r<405 km that exhibit some characteristics of what has been previously termed the High Aspect angle Irregularity Region (HAIR echoes. We show that these echoes appear to be a storm-time phenomenon and further investigate this population by comparing their Doppler velocity with the simultaneously measured F- and E-region irregularity velocities. It is suggested that the HAIR-like echoes are observed only by HF radars with relatively poor geometric aspect angles when electron density is low and when the electric field is particularly

CT and MRI in iatrogenic and sporadic Creutzfeldt-Jakob disease: as far as imaging perseives

Energy Technology Data Exchange (ETDEWEB)

Garcia Santos, J.M. [Servicio de Radiodiagnostico, HU Dr. Morales Meseguer, Murcia (Spain)]|[Section of Neuroradiology, HU Virgen de la Arrixaca, Murcia (Spain); Lopez Corbalan, J.A. [Section of Neuroradiology, HU Virgen de la Arrixaca, Murcia (Spain); Martinez-Lage, J.F. [Service of Neurosurgery, HU Virgen de la Arrixaca, Murcia (Spain); Sicilis Guillen, J. [Service of Neurology, HU Virgen de la Arrixaca, Murcia (Spain)

1996-04-01

Creutzfeldt-Jakob Disease (CJD), an invariably fatal dementing illness, affects patients in middle and old age (sporadic form). However, the association of CJD with certain treatments (iatrogenic form) has been described in younger patients. The clinical onset of the two forms seems to differ; in the iatrogenic form a high frequency of the ataxic CJD variant has been reported. Nowadays, a definitive diagnosis of CJD is exclusively histological. We present five cases of CJD, one sporadic and the others iatrogenic, following dura mater grafts and analyse their CT and MRI features. CT typically demonstrates brain atrophy, generally progressive, but in sporadic CJD midfield MRI also showed abnormal signal, with predominant deep grey matter involvement. The use of narrow windows with proton-density sequences may reveal subtle cortical signal abnormalities not clearly visible with conventional windows. The early demonstration of these changes, in the appropriate clinical context, may suggest CJD and this supports the use of mid- or high magnetic fields in the diagnosis of CJD and other forms of dementia. In our cases of iatrogenic CJD, low-field MRI did not reveal more than the progressive atrophy displayed by CT, and raises the question on the one hand of possible differences, based on imaging, from the sporadic form, and on the other of the lack of sensitivity of low-field magnets to signal changes in CJD. (orig.)

CT and MRI in iatrogenic and sporadic Creutzfeldt-Jakob disease: as far as imaging perseives

International Nuclear Information System (INIS)

Garcia Santos, J.M.; Lopez Corbalan, J.A.; Martinez-Lage, J.F.; Sicilis Guillen, J.

1996-01-01

Creutzfeldt-Jakob Disease (CJD), an invariably fatal dementing illness, affects patients in middle and old age (sporadic form). However, the association of CJD with certain treatments (iatrogenic form) has been described in younger patients. The clinical onset of the two forms seems to differ; in the iatrogenic form a high frequency of the ataxic CJD variant has been reported. Nowadays, a definitive diagnosis of CJD is exclusively histological. We present five cases of CJD, one sporadic and the others iatrogenic, following dura mater grafts and analyse their CT and MRI features. CT typically demonstrates brain atrophy, generally progressive, but in sporadic CJD midfield MRI also showed abnormal signal, with predominant deep grey matter involvement. The use of narrow windows with proton-density sequences may reveal subtle cortical signal abnormalities not clearly visible with conventional windows. The early demonstration of these changes, in the appropriate clinical context, may suggest CJD and this supports the use of mid- or high magnetic fields in the diagnosis of CJD and other forms of dementia. In our cases of iatrogenic CJD, low-field MRI did not reveal more than the progressive atrophy displayed by CT, and raises the question on the one hand of possible differences, based on imaging, from the sporadic form, and on the other of the lack of sensitivity of low-field magnets to signal changes in CJD. (orig.)

The P413L chromogranin B variation in French patients with sporadic amyotrophic lateral sclerosis.

Science.gov (United States)