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.

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.

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

Science.gov (United States)

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.

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

Electron density and plasma waves in mid-latitude sporadic-E layer observed during the SEEK-2 campaign

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M. Wakabayashi

2005-10-01

Full Text Available The SEEK-2 campaign was carried out over Kyushu Island in Japan on 3 August 2002, by using the two sounding rockets of S310-31 and S310-32. This campaign was planned to elucidate generation mechanisms of Quasi-Periodic Echoes (QPEs associated with mid-latitude sporadic-E (Es layers. Electron number densities were successfully measured in the Es layers by using the impedance probe on board two rockets. The plasma waves in the VLF and ELF ranges were also observed on board the S310-32 rocket. Results of electron density measurement showed that there were one or two major peaks in the Es layers along the rockets' trajectories near the altitude of about 10km. There were some smaller peaks associated with the main Es layers in the altitude range from 90 to 120 km. These density peaks were distributed in a very large extent during the SEEK-2 campaign. The Es layer structure is also measured by using the Fixed Bias Probe (FBP, which has a high spatial resolution of several meters (the impedance probe has an altitude resolution of about 400 m. The comparison with the total electron content (TEC measured by the Dual Band Beacon revealed that the Es layer was also modulated in the horizontal direction with the scale size of 30–40 km. It was shown that the QP echoes observed by the ground-based coherent radar come from the major density peak of the Es layer. The plasma wave instrument detected the enhancement of VLF and ELF plasma waves associated with the operation of the TMA release, and also with the passage of the Es layers. Keywords. Ionosphere (Ionospheric irregularities; Midlatitude ionosphere; Plasma temeperature and density

Effects of sporadic E-layer characteristics on spread-F generation in the nighttime ionosphere near a northern equatorial anomaly crest during solar minimum

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Lee, C. C.; Chen, W. S.

2015-06-01

This study is to know how the characteristics of sporadic E-layer (Es-layer) affect the generation of spread-F in the nighttime ionosphere near the crest of equatorial ionization anomaly during solar minimum. The data of Es-layer parameters and spread-F are obtained from the Chungli ionograms of 1996. The Es-layer parameters include foEs (critical frequency of Es-layer), fbEs (blanketing frequency of Es-layer), and Δf (≡foEs-fbEs). Results show that the nighttime variations of foEs and fbEs medians (Δf medians) are different from (similar to) that of the occurrence probabilities of spread-F. Because the total number of Es-layer events is greater than that of spread-F events, the comparison between the medians of Es-layer parameters and the occurrence probabilities of spread-F might have a shortfall. Further, we categorize the Es-layer and spread-F events into each frequency interval of Es-layer parameters. For the occurrence probabilities of spread-F versus foEs, an increasing trend is found in post-midnight of all three seasons. The increasing trend also exists in pre-midnight of the J-months and in post-midnight of all seasons, for the occurrence probabilities of spread-F versus Δf. These demonstrate that the spread-F occurrence increases with increasing foEs and/or Δf. Moreover, the increasing trends indicate that polarization electric fields generated in Es-layer assist to produce spread-F, through the electrodynamical coupling of Es-layer and F-region. Regarding the occurrence probabilities of spread-F versus fbEs, the significant trend only appears in post-midnight of the E-months. This implies that fbEs might not be a major factor for the spread-F formation.

Association of radiowave absorption with E(sporadic)-activity

International Nuclear Information System (INIS)

Ganguly, S.

1975-01-01

Noontime radiowave absorption data for frequencies which are reflected below the height of sporadic-E layers show a strong positive correlation with the sporadic-E layer activity. The possibilities of atmospheric waves affecting both the sporadic-E activity as well as mesospheric ionization are suggested to explain this association

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

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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.

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.

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

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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.

Solar eclipse effects of 22 July 2009 on Sporadic-E

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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

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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.

Mechanism for the formation of sporadic-E layers in the high-latitude ionosphere

Energy Technology Data Exchange (ETDEWEB)

Vlasov, M.N.; Mishin, E.V.; Telegin, V.A.

1980-09-01

A model of the collective interaction of precipitating electrons and the ionospheric plasma is used to explain the formation of short-duration sporadic-E layers in the high-latitude ionosphere. The changes produced in electron density by this collective interaction mechanism are considered.

A spectral study of the mid-latitude sporadic E layer characteristic oscillations comparable to those of the tidal and the planetary waves

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Pignalberi, A.; Pezzopane, M.; Zuccheretti, E.

2015-01-01

In this paper different spectral analyses are employed to investigate the tidal and planetary wave periodicities imprinted in the following two main characteristics of the sporadic E (Es) layer: the top frequency (ftEs) and the lowest virtual height (h‧Es). The study is based on ionograms recorded during the summertime of 2013, and precisely in June, July, August and September, by the Advanced Ionospheric Sounder by Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed at Rome (41.8°N, 12.5°E) and Gibilmanna (37.9°N, 14.0°E), Italy. It was confirmed that the diurnal and semidiurnal atmospheric tides play a fundamental role in the formation of the mid-latitude Es layers, acting through their vertical wind-shear forcing of the long-living metallic ions in the lower thermosphere, and at the same time it was found that the planetary atmospheric waves might affect the Es layers acting through their horizontal wind-shear forcing with periods close to the normal Rossby modes, that is 2, 5, 10 and 16 days. The wavelet analysis shows also that the ftEs and h‧Es tidal oscillations undergo a strong amplitude modulation with periods of several days and with important differences between the two parameters. This amplitude modulation, characterizing markedly the first thirty days of the ftEs spectrogram, suggests that Es layers are affected indirectly by planetary waves through their nonlinear interaction with the atmospheric tides at lower altitudes. This study wants to be a continuation of the Haldoupis et al. (2004) work in order to verify their results for the foEs characteristic and on the other hand to extend the study also to the h‧Es characteristic not yet shown so far. Anyhow, the study confirms that ionosonde data, especially those registered in summertime, represent a powerful tool for studying tidal and planetary waves properties and their climatology in the mesosphere-low-thermosphere region.

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.

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

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

The lunar tide in sporadic E

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R. J. Stening

1999-10-01

Full Text Available It seems that the wind shear theory is accepted for the explanation of sporadic E at mid and low latitudes. Some examples from Arecibo are displayed to show this. The effect of lunar tides should then modify the wind-shear theory in a manner that yields the observed features of the lunar tide in the critical frequency foEs and the height h'Es of the sporadic E. This is shown to imply that the phase of the lunar tide in h'Es should be the same as the phase of the lunar tide in the eastward wind and that the phase of the lunar tide in foEs is three hours later. Hourly values of foEs, f bEs (the blanketing critical frequency and h'Es from several observatories are analysed for the lunar semidiurnal tide. It is found that the phase of the tide in foEs is often about 3 hours later than for h'Es in agreement with the theory. Seasonal variations in the tide are also examined with the statistically most significant results (largest amplitudes usually occurring in summer. After reviewing the many difficulties associated with determining the lunar tide in Es, both experimentally and theoretically, the analysed phase results are compared with what might be expected from Hagan's global scale wave model. Agreement is only fair (a success rate of 69% among the cases examined but probably as good as might be expected.Key words. Ionosphere (ionosphere – atmosphere interactions – ionospheric irregularities, Meteorology and atmosphere dynamics (waves and tides

Investigation on the relationship among sporadic Na, sporadic E, Field aligned irregularities and neutral winds

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Sundararajan, Sridharan; Patra, Amit Kumar; Pant, Tarun; Gurubaran, Subramanian; Raghunath, Karnam

In the Mesosphere and Lower Thermosphere region (80-100 km), metallic atoms, namely, sodium, potassium, lithium, Iron etc are formed due to ablation of meteors. The lidars based on resonance fluorescence principle has been used to study the vertical distribution of sodium atoms, because of their large abundance than other metals. The profiles of sodium density sometimes show enhancement by a factor of 2 than the normal layer in a narrow altitude region of 2 km and on these occasions, they are called sporadic sodium layer, or briefly Ns. On the other hand, there are observations on sporadic E and radar observations of Field Aligned Irregularities (FAI) associated with these sporadic E. Some investigations have been made to understand the relationship between sporadic E and FAI. Considering that sporadic E is composed of metallic ions and the time of metallic ions are larger compared to other ions, the sodium observations in the same height region would be of significant importance to understand the process involved. Despite a few past observations, no clear picture has emerged due to lack of simultaneous measurements of these parameters. The simultaneous observations of FAI echoes by the Indian MST radar and sodium concentration by the sodium lidar at Gadanki (13.5o N, 79.2o E) are being used to investigate the above mentioned relationship. The Sporadic E and neutral wind information are obtained from the ionosonde, meteor/MF radar observations from Trivandrum (8.5o N, 77E) and Tirunelveli (8.7o N, 77.8o E). The results obtained will be presented during the meeting.

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.

Simultaneous lidar observation of peculiar sporadic K and Na layers at São José dos Campos (23.1°S, 45.9°W), Brazil

Science.gov (United States)

Jiao, Jing; Yang, Guotao; Cheng, Xuewu; Liu, Zhengkuan; Wang, Jihong; Yan, Zhenzhong; Wang, Chi; Batista, Paulo; Pimenta, Alexandre; Andrioli, Vânia; Denardini, C. M.

2018-04-01

We present the first simultaneous observation of mesopause sodium (Na) and potassium (K) layer by a lidar which has Na and K channel simultaneously at the South Hemisphere site, São José dos Campos (23.1°S, 45.9°W). Measurements reported here were conducted on two nights with 3.5 and 8 h of observations in November 2016. On 20 November 2016, sporadic layers in both Na and K layer occurred above 100 km, and the higher layers corresponded well with sporadic E (Es) layer. And the density of Na at 100-105 km is higher than that at main layer around 90 km, but K density around 100 km is at least 3 times smaller compared with the K density around 90 km for the similar period. On 21 November 2016, both sporadic layers occurred in main layer height with obvious descending variations with time, which seems like tidal induced. Notably, the peak K/Na ratio slowly increased with time. And Na layer and K layer showed different processes along with time with K density reaching its maximum 1 h later than that of Na. Correlations of Na/K density, Es, and winds were also discussed.

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.

Sporadic and Thermospheric Enhanced Sodium Layers Observed by a Lidar Chain over China

Science.gov (United States)

Xue, X.

2013-12-01

We report the statistical features of sporadic sodium layers (SSLs) and the thermospheric enhanced sodium layers (TeSLs) observed by a lidar chain located at Beijing (40.2N,116.2E), Hefei (31.8N, 117.3E), Wuhan (30.5N, 114.4E), and Haikou (19.5N, 109.1E). The average SSL occurrence rate was approximately 46.0, 12.3, 13.8, and 15.0 hr per SSL at Beijing, Hefei, Wuhan, and Haikou, respectively. However, the TeSLs occurred relatively infrequently and were more likely to appear at low and high latitudinal sites. Both the SSLs and TeSLs at four lidar sites showed evident summer enhancements and correlated well with Es (foEs>4MHz). The co-observations of SSLs at three lidar site pairs, i.e., Hefei -- Beijing, Hefei -- Wuhan and Hefei -- Beijing, indicated that a large-scale SSL extended horizontally for at least a few hundred kilometers and exhibited a tidal-induced modulation. Moreover, the SSLs were better correlated for the Hefei -- Wuhan and Hefei -- Haikou pairs than the Hefei -- Beijing pair, which suggested a difference in the dynamical/chemical process in mesosphere and lower thermosphere (MLT) between the Beijing site and the other sites.

A case study on generation mechanisms of a sporadic sodium layer above Tromsø (69.6° N during a night of high auroral activity

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T. Takahashi

2015-08-01

Full Text Available We have quantitatively evaluated generation mechanisms of a sporadic sodium layer (SSL based on observational data obtained by multiple instruments at a high-latitude station: Ramfjordmoen, Tromsø, Norway (69.6° N, 19.2° E. The sodium lidar observed an SSL at 21:18 UT on 22 January 2012. The SSL was observed for 18 min, with a maximum sodium density of about 1.9 × 1010 m−3 at 93 km with a 1.1 km thickness. The European Incoherent Scatter (EISCAT UHF radar observed a sporadic E layer (Es layer above 90 km from 20:00 to 23:00 UT. After 20:00 UT, the Es layer gradually descended and reached 94 km at 21:18 UT when the SSL appeared at the same altitude. In this event, considering the abundance of sodium ions (10 % or less, the Es layer could provide only about 37 % or less of the sodium atoms to the SSL. We have investigated a temporal development of the normal sodium ion layer with a consideration of chemical reactions and the effect of the (southwestward electric field using observational values of the neutral temperature, electron density, horizontal neutral wind, and electric field. This calculation has shown that those processes, including contributions of the Es layer, would provide about 88 % of sodium atoms of the SSL. The effects of meteor absorption and auroral particle sputtering appear to be less important. Therefore, we have concluded that the major source of the SSL was sodium ions in a normal sodium ion layer. Two processes – namely the downward transportation of sodium ions from a normal sodium ion layer due to the electric field and the additional supply of sodium ions from the Es layer under relatively high electron density conditions (i.e., in the Es layer – played a major role in generating the SSL in this event. Furthermore, we have found that the SSL was located in a lower-temperature region and that the temperature inside the SSL did not show any remarkable temperature enhancements.

Coherent structures in the Es layer and neutral middle atmosphere

Science.gov (United States)

Mošna, Zbyšek; Knížová, Petra Koucká; Potužníková, Kateřina

2015-12-01

The present paper shows results from the summer campaign performed during geomagnetically quiet period from June 1 to August 31, 2009. Within time-series of stratospheric and mesospheric temperatures at pressure levels 10-0.1 hPa, mesospheric winds measured in Collm, Germany, and the sporadic E-layer parameters foEs and hEs measured at the Pruhonice station we detected specific coherent wave-bursts in planetary wave domain. Permanent wave-like activity is observed in all analyzed data sets. However, the number of wave-like structures persistent in large range of height from the stratosphere to lower ionosphere is limited. The only coherent modes that are detected on consequent levels of the atmosphere are those corresponding to eigenmodes of planetary waves.

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.

Instability waves and transition in adverse-pressure-gradient boundary layers

Science.gov (United States)

Bose, Rikhi; Zaki, Tamer A.; Durbin, Paul A.

2018-05-01

Transition to turbulence in incompressible adverse-pressure-gradient (APG) boundary layers is investigated by direct numerical simulations. Purely two-dimensional instability waves develop on the inflectional base velocity profile. When the boundary layer is perturbed by isotropic turbulence from the free stream, streamwise elongated streaks form and may interact with the instability waves. Subsequent mechanisms that trigger transition depend on the intensity of the free-stream disturbances. All evidence from the present simulations suggest that the growth rate of instability waves is sufficiently high to couple with the streaks. Under very low levels of free-stream turbulence (˜0.1 % ), transition onset is highly sensitive to the inlet disturbance spectrum and is accelerated if the spectrum contains frequency-wave-number combinations that are commensurate with the instability waves. Transition onset and completion in this regime is characterized by formation and breakdown of Λ vortices, but they are more sporadic than in natural transition. Beneath free-stream turbulence with higher intensity (1-2 % ), bypass transition mechanisms are dominant, but instability waves are still the most dominant disturbances in wall-normal and spanwise perturbation spectra. Most of the breakdowns were by disturbances with critical layers close to the wall, corresponding to inner modes. On the other hand, the propensity of an outer mode to occur increases with the free-stream turbulence level. Higher intensity free-stream disturbances induce strong streaks that favorably distort the boundary layer and suppress the growth of instability waves. But the upward displacement of high amplitude streaks brings them to the outer edge of the boundary layer and exposes them to ambient turbulence. Consequently, high-amplitude streaks exhibit an outer-mode secondary instability.

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)

Coherent structures in the Es layer and neutral middle atmosphere

Czech Academy of Sciences Publication Activity Database

Mošna, Zbyšek; Koucká Knížová, Petra; Potužníková, Kateřina

136 B, December (2015), s. 155-162 ISSN 1364-6826 R&D Projects: GA ČR(CZ) GA15-24688S; GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : critical frequency foEs * mesospheric temperature * mesospheric winds * planetary waves * Rossby mode * sporadic layer * stratospheric temperature Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.463, year: 2015 http://www.sciencedirect.com/science/article/pii/S1364682615001273

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

Evidence of the Dampening Effect of Dense E-region Structures on E-F Coupling

Science.gov (United States)

Helmboldt, J.

2012-12-01

Results from a combination of instruments including ionosondes, GPS receivers, the Very Large Array (VLA), and the Long Wavelength Array (LWA) are used to demonstrate the role structure within the E-region plays in coupling between instabilities within the E and F regions at midlatitudes. VLA observations of cosmic sources at 74 MHz during summer nighttime in 2002 detected northwest-to-southeast aligned wavefronts, consistent with medium-scale traveling ionospheric disturbances (MSTIDs). These waves were only found when contemporaneous observations from nearby ionosondes detected echoes from sporadic-E layers. However, when the peak density of these layers was high (foEs> 3 MHz), there were no MSTIDs detected. Similar results are presented using the first station of the LWA, LWA1, to perform all-sky imaging of dense E-region structures (sporadic-E "clouds") via coherent scattering of distant analog TV broadcasts at 55 MHz. These observations were conducted during summer/autumn 2012 and include simultaneous GPS-based observations of F-region disturbances.Left: LWA1 all-sky image of ionospheric echoes of analog TV transmissions at 55.25 MHz. Right: Doppler speed maps for the brightest echoes.

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

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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

Effects of sporadic E-layer characteristics on spread-F generation in the nighttime midlatitude ionosphere: A climatological study

Science.gov (United States)

Lee, C. C.; Chen, W. S.

2018-04-01

The aim of this study is to examine the effects of Es-layer characteristics on spread-F generation in the nighttime midlatitude ionosphere. The Es-layer parameters and spread-F appearance of the 23rd solar cycle (1996-2008) are recorded by the Kokubunji ionosonde. The Es-layer parameters are foEs (critical frequency of Es-layer), fbEs (blanketing frequency of Es-layer), and Δf (≡foEs-fbEs). In order to completely explore the effects, the pre-midnight and post-midnight data are classified by seasons, solar activities, and geomagnetic conditions. Results show that the spread-F occurs more frequently in post-midnight and in summer. And, the occurrence probabilities of spread-F are greater, when the solar activity is lower. For the occurrence probabilities of spread-F versus foEs and Δf under geomagnetic quiet-conditions, the trend is increasing, when the associated probabilities are significant. These indicate that the spread-F occurrence increases with increasing foEs and/or Δf. Further, the increasing trends demonstrate that polarization electric fields generated in Es-layer would be helpful to generate spread-F, through the electrodynamical coupling of Es-layer and F-region. Moreover, this electrodynamical coupling is efficient not only under quiet-conditions but under disturbed-conditions, since the significant increasing trend can also be found under disturbed-conditions. Regarding the occurrence probabilities of spread-F versus fbEs, the evident trends are not in the majority. This implies that fbEs might not be a major factor for the spread-F formation.

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

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

Cross-Field Current Instabilities in Thin Ionization Layers and the Enhanced Aurora

International Nuclear Information System (INIS)

Johnson, Jay R.; Okuda, Hideo

2008-01-01

Nearly half of the time, auroral displays exhibit thin, bright layers known as 'enhanced aurora'. There is a substantial body of evidence that connects these displays with thin, dense, heavy ion layers in the E-region. Based on the spectral characteristics of the enhanced layers, it is believed that they result when wave-particle interaction heats ambient electrons to energies at or just above the 17 eV ionization energy of N2. While there are several possible instabilities that could produce suprathermal electrons in thin layers, there has been no clear theoretical investigation which examines in detail how wave instabilities in the thin ionization layers could develop and produce the suprathermal electrons. We examine instabilities which would occur in thin, dense, heavy ion layers using extensive analytical analysis combined with particle simulations. We analyze a cross field current instability that is found to be strongly unstable in the heavy ion layers. Electrostatic simulations show that substantial heating of the ambient electrons occurs with energization at or above the N2 ionization energy.

Fringe instability in constrained soft elastic layers.

Science.gov (United States)

Lin, Shaoting; Cohen, Tal; Zhang, Teng; Yuk, Hyunwoo; Abeyaratne, Rohan; Zhao, Xuanhe

2016-11-04

Soft elastic layers with top and bottom surfaces adhered to rigid bodies are abundant in biological organisms and engineering applications. As the rigid bodies are pulled apart, the stressed layer can exhibit various modes of mechanical instabilities. In cases where the layer's thickness is much smaller than its length and width, the dominant modes that have been studied are the cavitation, interfacial and fingering instabilities. Here we report a new mode of instability which emerges if the thickness of the constrained elastic layer is comparable to or smaller than its width. In this case, the middle portion along the layer's thickness elongates nearly uniformly while the constrained fringe portions of the layer deform nonuniformly. When the applied stretch reaches a critical value, the exposed free surfaces of the fringe portions begin to undulate periodically without debonding from the rigid bodies, giving the fringe instability. We use experiments, theory and numerical simulations to quantitatively explain the fringe instability and derive scaling laws for its critical stress, critical strain and wavelength. We show that in a force controlled setting the elastic fingering instability is associated with a snap-through buckling that does not exist for the fringe instability. The discovery of the fringe instability will not only advance the understanding of mechanical instabilities in soft materials but also have implications for biological and engineered adhesives and joints.

Sporadic-E and spread-F in high latitude region

International Nuclear Information System (INIS)

Tao, Kazuhiko

1974-01-01

The heretofore made morphological studies of sporadic-E and spread-F as the typical irregularities of electron density are reviewed. These phenomena have close correlation with other geophysical phenomena which occur in the atmosphere of superhigh altitude in high latitude region. Many of these phenomena occur from same causes. Although the quantitative data are insufficient, the sporadic-E and spread-F in high latitude region are supposed to be caused by the precipitating charged particles falling from magnetosphere. A system, which can observe such phenomena simultaneously using the measuring instruments carried by satellites in the atmosphere of high altitude over high latitude region, is desirable to solve such problems. In detail, the morphological study on sporadic-E obtained from the observation of vertically projected ionosphere and the morphological study on sporadic-E from the observation of forward scattering and slanting entrance are reviewed. The correlation of the occurrence frequency of sporadic-E with solar activity, geomagnetic activity and other phenomena was studied. The morphological study on spread-F occurrence is reviewed. The observation of the spread-F in high latitude region by the application of top side sounding is reviewed. The correlation of the sporadic-E and spread-F in high latitude region with other geophysical phenomena is discussed. Finally, the discrete phenomenon and the diffuse phenomenon are discussed too. (Iwakiri, K.)

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.

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.

Instability limits for spontaneous double layer formation

International Nuclear Information System (INIS)

Carr, J. Jr.; Galante, M. E.; McCarren, D.; Scime, E. E.; Sears, S.; VanDervort, R. W.; Magee, R. M.; Reynolds, E.

2013-01-01

We present time-resolved measurements that demonstrate that large amplitude electrostatic instabilities appear in pulsed, expanding helicon plasmas at the same time as particularly strong double layers appear in the expansion region. A significant cross-correlation between the electrostatic fluctuations and fluctuations in the number of ions accelerated by the double layer electric field is observed. No correlation is observed between the electrostatic fluctuations and ions that have not passed through the double layer. These measurements confirm that the simultaneous appearance of the electrostatic fluctuations and the double layer is not simple coincidence. In fact, the accelerated ion population is responsible for the growth of the instability. The double layer strength, and therefore, the velocity of the accelerated ions, is limited by the appearance of the electrostatic instability

Incompressible Modes Excited by Supersonic Shear in Boundary Layers: Acoustic CFS Instability

Energy Technology Data Exchange (ETDEWEB)

Belyaev, Mikhail A., E-mail: mbelyaev@berkeley.edu [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

2017-02-01

We present an instability for exciting incompressible modes (e.g., gravity or Rossby modes) at the surface of a star accreting through a boundary layer. The instability excites a stellar mode by sourcing an acoustic wave in the disk at the boundary layer, which carries a flux of energy and angular momentum with the opposite sign as the energy and angular momentum density of the stellar mode. We call this instability the acoustic Chandrasekhar–Friedman–Schutz (CFS) instability, because of the direct analogy to the CFS instability for exciting modes on a rotating star by emission of energy in the form of gravitational waves. However, the acoustic CFS instability differs from its gravitational wave counterpart in that the fluid medium in which the acoustic wave propagates (i.e., the accretion disk) typically rotates faster than the star in which the incompressible mode is sourced. For this reason, the instability can operate even for a non-rotating star in the presence of an accretion disk. We discuss applications of our results to high-frequency quasi-periodic oscillations in accreting black hole and neutron star systems and dwarf nova oscillations in cataclysmic variables.

Temporal evolution of the HF-enhanced plasma line in sporadic E

International Nuclear Information System (INIS)

Djuth, F.T.; Gonzales, C.A.

1988-01-01

The high-power, high-frequency (HF) facility at Arecibo, Puerto Rico, has been used to study the excitation of Langmuir waves in mid-latitude sporadic E. Measurements of the temporal evolution of so-called HF-enhanced plasma line (HFPL) were made using the Arecibo 430-MHz radar. After HF turn-on in the plasma the HFPL exhibits a rapid growth phase followed by a quick overshoot. During periods of strong HFPL excitation the e-folding growth time of the HFPL power is typically approx-lt 20 μs, and the total overshoot period is ∼1 ms. On the basis of the current observations, mode conversion of the HF wave into Langmuir waves near HF reflection appears to be a promising mechanism for the production of Langmuir waves in sporadic E. Caviton formation at the critical layer is expected to accompany this process, and there is some evidence that the 430-MHz radar is probing the plasma in a region where density cavities of this nature form. While no specific explanation is offered for the HFPL overshoot, it appears that this phenomenon is fundamental to the Langmuir wave excitation process

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

Artificial E-region field-aligned plasma irregularities generated at pump frequencies near the second electron gyroharmonic

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D. L. Hysell

2009-07-01

Full Text Available E region ionospheric modification experiments have been performed at HAARP using pump frequencies about 50 kHz above and below the second electron gyroharmonic frequency. Artificial E region field-aligned plasma density irregularities (FAIs were created and observed using the imaging coherent scatter radar near Homer, Alaska. Echoes from FAIs generated with pump frequencies above and below 2Ωe did not appear to differ significantly in experiments conducted on summer afternoons in 2008, and the resonance instability seemed to be at work in either case. We argue that upper hybrid wave trapping and resonance instability at pump frequencies below the second electron gyroharmonic frequency are permitted theoretically when the effects of finite parallel wavenumbers are considered. Echoes from a sporadic E layer were observed to be somewhat weaker when the pump frequency was 50 kHz below the second electron gyroharmonic frequency. This may indicate that finite parallel wavenumbers are inconsistent with wave trapping in thin sporadic E ionization layers.

Artificial E-region field-aligned plasma irregularities generated at pump frequencies near the second electron gyroharmonic

Directory of Open Access Journals (Sweden)

D. L. Hysell

2009-07-01

Full Text Available E region ionospheric modification experiments have been performed at HAARP using pump frequencies about 50 kHz above and below the second electron gyroharmonic frequency. Artificial E region field-aligned plasma density irregularities (FAIs were created and observed using the imaging coherent scatter radar near Homer, Alaska. Echoes from FAIs generated with pump frequencies above and below 2Ω_e did not appear to differ significantly in experiments conducted on summer afternoons in 2008, and the resonance instability seemed to be at work in either case. We argue that upper hybrid wave trapping and resonance instability at pump frequencies below the second electron gyroharmonic frequency are permitted theoretically when the effects of finite parallel wavenumbers are considered. Echoes from a sporadic E layer were observed to be somewhat weaker when the pump frequency was 50 kHz below the second electron gyroharmonic frequency. This may indicate that finite parallel wavenumbers are inconsistent with wave trapping in thin sporadic E ionization layers.

Secondary Instability of Stationary Crossflow Vortices in Mach 6 Boundary Layer Over a Circular Cone

Science.gov (United States)

Li, Fei; Choudhari, Meelan M.; Paredes-Gonzalez, Pedro; Duan, Lian

2015-01-01

Hypersonic boundary layer flows over a circular cone at moderate incidence can support strong crossflow instability. Due to more efficient excitation of stationary crossflow vortices by surface roughness, such boundary layer flows may transition to turbulence via rapid amplification of the high-frequency secondary instabilities of finite amplitude stationary crossflow vortices. The amplification characteristics of these secondary instabilities are investigated for crossflow vortices generated by an azimuthally periodic array of roughness elements over a 7-degree half-angle circular cone in a Mach 6 free stream. Depending on the local amplitude of the stationary crossflow mode, the most unstable secondary disturbances either originate from the second (i.e., Mack) mode instabilities of the unperturbed boundary layer or correspond to genuine secondary instabilities that reduce to stable disturbances at sufficiently small amplitudes of the stationary crossflow vortex. The predicted frequencies of dominant secondary disturbances are similar to those measured during wind tunnel experiments at Purdue University and the Technical University of Braunschweig, Germany.

High-frequency instabilities of stationary crossflow vortices in a hypersonic boundary layer

Science.gov (United States)

Li, Fei; Choudhari, Meelan; Paredes, Pedro; Duan, Lian

2016-09-01

Hypersonic boundary layer flows over a circular cone at moderate incidence angle can support strong crossflow instability in between the windward and leeward rays on the plane of symmetry. Due to more efficient excitation of stationary crossflow vortices by surface roughness, such boundary layer flows may transition to turbulence via rapid amplification of the high-frequency secondary instabilities of finite-amplitude stationary crossflow vortices. The amplification characteristics of these secondary instabilities are investigated for crossflow vortices generated by an azimuthally periodic array of roughness elements over a 7° half-angle circular cone in a Mach 6 free stream. The analysis is based on both quasiparallel stability theory in the form of a partial-differential-equation-based eigenvalue analysis and plane marching parabolized stability equations that account for the effects of the nonparallel basic state on the growth of secondary disturbances. Depending on the local amplitude of the stationary crossflow mode, the most unstable high-frequency disturbances either originate from the second (i.e., Mack) mode instabilities of the unperturbed boundary layer or correspond to genuine secondary instabilities that reduce to stable disturbances at sufficiently small amplitudes of the stationary crossflow vortex. The predicted frequencies of the dominant secondary disturbances of either type are similar to those measured during wind tunnel experiments at Purdue University and the Technical University of Braunschweig, Germany. Including transverse surface curvature within the quasiparallel predictions does not alter the topology of the unstable modes; however, the resulting changes in both mode shape and disturbance growth rate are rather significant and curvature can be either stabilizing or destabilizing depending on the disturbance frequency and mode type. Nonparallel effects are shown to be strongly destabilizing for secondary instabilities originating from

Circuit effects on pierce instabilities, and double-layer formation

International Nuclear Information System (INIS)

Raadu, M.A.; Silevitch, M.B.

1982-11-01

The role of the Pierce instability in the formation of double layers is considered and compared with that of the Buneman instability. Pierce instabilities have been identified in a double-layer experiment, where they lead to ion trapping. Here the effects of external circuit elements are considered. In the case of immobile ions the onset criteria are unaffected, but in the unstable range the growth rate is reduced by the external impedance. Required experimental values of the circuit elements are estimated. The possible relevance to computer simulations is noted. (Authors)

Irrelevance of microsatellite instability in the epidemiology of sporadic pancreatic ductal adenocarcinoma.

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Luigi Laghi

Full Text Available Pancreatic cancer risk is increased in Lynch syndrome (LS patients with mismatch repair gene defects predisposing to colonic and extracolonic cancers with microsatellite instability (MSI. However, the frequency of MSI pancreatic cancers has never been ascertained in consecutive, unselected clinical series, and their contribution to the sporadic and inherited burden of pancreatic cancer remains to be established. Aims of the study were to determine the prevalence of MSI in surgically resected pancreatic cancers in a multicentric, retrospective study, and to assess the occurrence of pancreatic cancer in LS.MS-status was screened by a panel of 5 mononucleotide repeats (Bat26, Bat25, NR-21, NR-24 and NR-27 in 338 consecutive pancreatic ductal adenocarcinoma (PDAC, resected at two Italian and one German referral centres. The personal history of pancreatic cancer was assessed in an independent set of 58 probands with LS and in 138 first degree relatives who had cancers.Only one PDAC (0.3% showed MSI. This was a medullary type cancer, with hMLH1-deficiency, and no identified germ-line mutation but methylation of hMLH1. Pancreatic cancer occurred in 5 (2.5% LS patients. Histological sampling was available for 2 cases, revealing PDAC in one case and an ampullary cancer in the other one.MSI prevalence is negligible in sporadic, resected PDAC. Differently, the prevalence of pancreatic cancer is 2.5% in LS patients, and cancers other than PDAC may be encountered in this setting. Surveillance for pancreatic cancer should be advised in LS mutation carriers at referral centers.

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.

Physics of Transitional Shear Flows Instability and Laminar–Turbulent Transition in Incompressible Near-Wall Shear Layers

CERN Document Server

Boiko, Andrey V; Grek, Genrih R; Kozlov, Victor V

2012-01-01

Starting from fundamentals of classical stability theory, an overview is given of the transition phenomena in subsonic, wall-bounded shear flows. At first, the consideration focuses on elementary small-amplitude velocity perturbations of laminar shear layers, i.e. instability waves, in the simplest canonical configurations of a plane channel flow and a flat-plate boundary layer. Then the linear stability problem is expanded to include the effects of pressure gradients, flow curvature, boundary-layer separation, wall compliance, etc. related to applications. Beyond the amplification of instability waves is the non-modal growth of local stationary and non-stationary shear flow perturbations which are discussed as well. The volume continues with the key aspect of the transition process, that is, receptivity of convectively unstable shear layers to external perturbations, summarizing main paths of the excitation of laminar flow disturbances. The remainder of the book addresses the instability phenomena found at l...

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

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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.

Evidence of Rayleigh-Taylor instabilities in tri-layer targets

International Nuclear Information System (INIS)

Galmiche, D.; Holstein, P.A.; Meyer, B.; Rostaing, M.; Wilke, N.

1988-01-01

The results of the experiments carried out on a laser system are reported. The work is performed in order to investigate the problem of target instability under ablative acceleration and to get direct evidence of Rayleigh-Taylor instabilities. Tri-layer experiments assert the validity of X-ray spectroscopy measurements as experimental method to investigate the problem. A mixing zone is evidenced and general trends of mixing development versus target acceleration are coherent with numerical simulations. Results obtained with optical smoothing demonstrate that the apparent mixing is not due to large scale illumination non uniformities. Numerical simulations confirm that Rayleigh-Taylor instability seems to be the dominant process responsible for the mixing. Benefit of time resolved spectroscopy appears attractive and gives a real knowledge of the mixing layer

Kelvin-Helmholtz instability in a weakly ionized layer

OpenAIRE

Shadmehri, Mohsen; Downes, Turlough P.

2007-01-01

We study the linear theory of Kelvin-Helmholtz instability in a layer of ions and neutrals with finite thickness. In the short wavelength limit the thickness of the layer has a negligible effect on the growing modes. However, perturbations with wavelength comparable to layer's thickness are significantly affected by the thickness of the layer. We show that the thickness of the layer has a stabilizing effect on the two dominant growing modes. Transition between the modes not only depends on th...

Electron-temperature-gradient-induced instability in tokamak scrape-off layers

International Nuclear Information System (INIS)

Berk, H.L.; Ryutov, D.D.; Tsidulko, Y.A.; Xu, X.Q.

1992-08-01

An electron temperature instability driven by the Kunkel-Guillory sheath impedance, has been applied to the scrape-off layer of tokamaks. The formalism has been generalized to more fully account for parallel wavelength dynamics, to differentiate between electromagnetic and electrostatic perturbations and to account for particle recycling effects. It is conjectured that this conducting wall instability leads to edge fluctuations in tokamaks that produce scrape-off widths of many ion Larmor radii ≅10. The predicted instability characteristics correlate somewhat with DIII-D edge fluctuation data, and the scrape-off layer width in the DIII-D experiment agrees with theoretical estimates that can be derived from mixing lenght theory

Effect of Compliant Walls on Secondary Instabilities in Boundary-Layer Transition

Science.gov (United States)

Joslin, Ronald D.; Morris, Philip J.

1991-01-01

For aerodynamic and hydrodynamic vehicles, it is highly desirable to reduce drag and noise levels. A reduction in drag leads to fuel savings. In particular for submersible vehicles, a decrease in noise levels inhibits detection. A suggested means to obtain these reduction goals is by delaying the transition from laminar to turbulent flow in external boundary layers. For hydrodynamic applications, a passive device which shows promise for transition delays is the compliant coating. In previous studies with a simple mechanical model representing the compliant wall, coatings were found that provided transition delays as predicted from the semi-empirical e(sup n) method. Those studies were concerned with the linear stage of transition where the instability of concern is referred to as the primary instability. For the flat-plate boundary layer, the Tollmien-Schlichting (TS) wave is the primary instability. In one of those studies, it was shown that three-dimensional (3-D) primary instabilities, or oblique waves, could dominate transition over the coatings considered. From the primary instability, the stretching and tilting of vorticity in the shear flow leads to a secondary instability mechanism. This has been theoretical described by Herbert based on Floquet theory. In the present study, Herbert's theory is used to predict the development of secondary instabilities over isotropic and non-isotropic compliant walls. Since oblique waves may be dominant over compliant walls, a secondary theory extention is made to allow for these 3-D primary instabilities. The effect of variations in primary amplitude, spanwise wavenumber, and Reynolds number on the secondary instabilities are examined. As in the rigid wall case, over compliant walls the subharmonic mode of secondary instability dominates for low-amplitude primary disturbances. Both isotropic and non-isotropic compliant walls lead to reduced secondary growth rates compared to the rigid wall results. For high frequencies

Absolute/convective secondary instabilities and the role of confinement in free shear layers

Science.gov (United States)

Arratia, Cristóbal; Mowlavi, Saviz; Gallaire, François

2018-05-01

We study the linear spatiotemporal stability of an infinite row of equal point vortices under symmetric confinement between parallel walls. These rows of vortices serve to model the secondary instability leading to the merging of consecutive (Kelvin-Helmholtz) vortices in free shear layers, allowing us to study how confinement limits the growth of shear layers through vortex pairings. Using a geometric construction akin to a Legendre transform on the dispersion relation, we compute the growth rate of the instability in different reference frames as a function of the frame velocity with respect to the vortices. This approach is verified and complemented with numerical computations of the linear impulse response, fully characterizing the absolute/convective nature of the instability. Similar to results by Healey on the primary instability of parallel tanh profiles [J. Fluid Mech. 623, 241 (2009), 10.1017/S0022112008005284], we observe a range of confinement in which absolute instability is promoted. For a parallel shear layer with prescribed confinement and mixing length, the threshold for absolute/convective instability of the secondary pairing instability depends on the separation distance between consecutive vortices, which is physically determined by the wavelength selected by the previous (primary or pairing) instability. In the presence of counterflow and moderate to weak confinement, small (large) wavelength of the vortex row leads to absolute (convective) instability. While absolute secondary instabilities in spatially developing flows have been previously related to an abrupt transition to a complex behavior, this secondary pairing instability regenerates the flow with an increased wavelength, eventually leading to a convectively unstable row of vortices. We argue that since the primary instability remains active for large wavelengths, a spatially developing shear layer can directly saturate on the wavelength of such a convectively unstable row, by

Breast tumor copy number aberration phenotypes and genomic instability

International Nuclear Information System (INIS)

Fridlyand, Jane; Jain, Ajay N; McLennan, Jane; Ziegler, John; Chin, Koei; Devries, Sandy; Feiler, Heidi; Gray, Joe W; Waldman, Frederic; Pinkel, Daniel; Albertson, Donna G; Snijders, Antoine M; Ylstra, Bauke; Li, Hua; Olshen, Adam; Segraves, Richard; Dairkee, Shanaz; Tokuyasu, Taku; Ljung, Britt Marie

2006-01-01

Genomic DNA copy number aberrations are frequent in solid tumors, although the underlying causes of chromosomal instability in tumors remain obscure. Genes likely to have genomic instability phenotypes when mutated (e.g. those involved in mitosis, replication, repair, and telomeres) are rarely mutated in chromosomally unstable sporadic tumors, even though such mutations are associated with some heritable cancer prone syndromes. We applied array comparative genomic hybridization (CGH) to the analysis of breast tumors. The variation in the levels of genomic instability amongst tumors prompted us to investigate whether alterations in processes/genes involved in maintenance and/or manipulation of the genome were associated with particular types of genomic instability. We discriminated three breast tumor subtypes based on genomic DNA copy number alterations. The subtypes varied with respect to level of genomic instability. We find that shorter telomeres and altered telomere related gene expression are associated with amplification, implicating telomere attrition as a promoter of this type of aberration in breast cancer. On the other hand, the numbers of chromosomal alterations, particularly low level changes, are associated with altered expression of genes in other functional classes (mitosis, cell cycle, DNA replication and repair). Further, although loss of function instability phenotypes have been demonstrated for many of the genes in model systems, we observed enhanced expression of most genes in tumors, indicating that over expression, rather than deficiency underlies instability. Many of the genes associated with higher frequency of copy number aberrations are direct targets of E2F, supporting the hypothesis that deregulation of the Rb pathway is a major contributor to chromosomal instability in breast tumors. These observations are consistent with failure to find mutations in sporadic tumors in genes that have roles in maintenance or manipulation of the genome

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.

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.

Equilibrium and stability properties of relativistic electron rings and E-layers

International Nuclear Information System (INIS)

Uhm, H.

1976-01-01

Equilibrium and stability properties of magnetically confined partially-neutralized thin electron ring and E-layer are investigated using the Vlasov-Maxwell equations. The analysis is carried out within the context of the assumption that the minor dimensions (a,b) of the system are much less than the collisionless skin depth (c/antiω/sub p/). The equilibrium configuration of the E-layer is assumed to be an infinitely long, azimuthally symmetric hollow electron beam which is aligned parallel to a uniform axial magnetic field. On the other hand, the electron ring is located at the midplane of an externally imposed mirror field which acts to confine the ring both axially and radially. The equilibrium properties of the E-layer and electron ring are obtained self-consistently for several choices of equilibrium electron distribution function. The negative-mass instability analysis is carried out for the relativistic E-layer equilibrium in which all of the electrons have the same transverse energy and a spread in canonical angular momentum, assuming a fixed ion background. The ion resonance instability properties are investigated for a relativistic nonneutral E-layer aligned parallel to a uniform magnetic field and located between two ground coaxial cylindrical conductors. The stability properties of a nonrelativistic electron ring is investigated within the framework of the linearized Vlasov-Poisson equations. The dispersion relation is obtained for the self-consistent electron distribution function in which all electrons have the same value of energy an the same value of canonical angular momentum. The positive ions in the electron ring are assumed to form an immobile partially neutralizing background. The stability criteria as well as the instability growth rates are derived and discussed including the effect of geometrical configuration of the system. Equilibrium space-charge effects play a significant role in stability behavior

On the role of acoustic feedback in boundary-layer instability.

Science.gov (United States)

Wu, Xuesong

2014-07-28

In this paper, the classical triple-deck formalism is employed to investigate two instability problems in which an acoustic feedback loop plays an essential role. The first concerns a subsonic boundary layer over a flat plate on which two well-separated roughness elements are present. A spatially amplifying Tollmien-Schlichting (T-S) wave between the roughness elements is scattered by the downstream roughness to emit a sound wave that propagates upstream and impinges on the upstream roughness to regenerate the T-S wave, thereby forming a closed feedback loop in the streamwise direction. Numerical calculations suggest that, at high Reynolds numbers and for moderate roughness heights, the long-range acoustic coupling may lead to absolute instability, which is characterized by self-sustained oscillations at discrete frequencies. The dominant peak frequency may jump from one value to another as the Reynolds number, or the distance between the roughness elements, is varied gradually. The second problem concerns the supersonic 'twin boundary layers' that develop along two well-separated parallel flat plates. The two boundary layers are in mutual interaction through the impinging and reflected acoustic waves. It is found that the interaction leads to a new instability that is absent in the unconfined boundary layer. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Microsatellite instability in solitary and sporadic gastric cancer Instabilidade de microsatelites no cancer gástrico solitário e esporádico

Directory of Open Access Journals (Sweden)

Rodrigo Oliva Perez

2004-01-01

.A presença de Instabilidade de microsatellites (IMS tem sido relatada no cancer gastrico e associada a pacientes com idade mais avançada, localização mais distal do tumor, estadios mais precoces e melhor prognostico. Relatamos neste prospectivo estudo envolvendo 24 pacientes com cancer gastrico solitario e esporadico, a incidencia de IMS, sua correlação com parametros epidemiologicos, clinicos e anatomo patológicos e o seu impacto sobre a sobrevida geral e livre de doença. PACIENTES E MÉTODOS: Todos os pacientes haviam sido tratados com cirurgia radical. Fragmentos de tecido normal e tumoral eram extraidos das peças e armazenados a -80ºC antes da extração e purificação DNA. Realizava-se então a amplificação com PCR utilizando marcadores específicos de microsatelites. Os tumores que apresentavam produtos de amplificação anormais foram considerados positivos para IMS. RESULTADOS: Cinco pacientes (21% apresentaram Instabilidade de microsatelites (IMS+ com pelo menos um marcador (primer No grupo de pacientes com adenocarcinomas gástricos do tipo histológico de Lauren, três apresentavam IMS (23% enquanto no grupo portador de cancar gástrico difuso, dois pacientes mostraram IMS (19%.. Embora haja uma tendência dos pacientes IMS+ apresentarem tumores de localização mais proximal, estadios mais precoces e ausência de metástases linfonodais, não se observou diferenças estatisticamente significativas (p > 0,1. A comparação entre as taxas de sobrevida geral e livre de doença não mostrou significância estatistica (p > 0,1. CONCLUSÕES: IMS é um evento frequente na carcinogese gástrica e pode estar associado a caracteristicas clinicas e anátomo-patológicas do câncer gástrico.

Three-dimensional instability analysis of boundary layers perturbed by streamwise vortices

Science.gov (United States)

Martín, Juan A.; Paredes, Pedro

2017-12-01

A parametric study is presented for the incompressible, zero-pressure-gradient flat-plate boundary layer perturbed by streamwise vortices. The vortices are placed near the leading edge and model the vortices induced by miniature vortex generators (MVGs), which consist in a spanwise-periodic array of small winglet pairs. The introduction of MVGs has been experimentally proved to be a successful passive flow control strategy for delaying laminar-turbulent transition caused by Tollmien-Schlichting (TS) waves. The counter-rotating vortex pairs induce non-modal, transient growth that leads to a streaky boundary layer flow. The initial intensity of the vortices and their wall-normal distances to the plate wall are varied with the aim of finding the most effective location for streak generation and the effect on the instability characteristics of the perturbed flow. The study includes the solution of the three-dimensional, stationary, streaky boundary layer flows by using the boundary region equations, and the three-dimensional instability analysis of the resulting basic flows by using the plane-marching parabolized stability equations. Depending on the initial circulation and positioning of the vortices, planar TS waves are stabilized by the presence of the streaks, resulting in a reduction in the region of instability and shrink of the neutral stability curve. For a fixed maximum streak amplitude below the threshold for secondary instability (SI), the most effective wall-normal distance for the formation of the streaks is found to also offer the most stabilization of TS waves. By setting a maximum streak amplitude above the threshold for SI, sinuous shear layer modes become unstable, as well as another instability mode that is amplified in a narrow region near the vortex inlet position.

Sporadic wind wave horse-shoe patterns

Directory of Open Access Journals (Sweden)

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

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

Directory of Open Access Journals (Sweden)

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

Wake Instabilities Behind Discrete Roughness Elements in High Speed Boundary Layers

Science.gov (United States)

Choudhari, Meelan; Li, Fei; Chang, Chau-Lyan; Norris, Andrew; Edwards, Jack

2013-01-01

Computations are performed to study the flow past an isolated, spanwise symmetric roughness element in zero pressure gradient boundary layers at Mach 3.5 and 5.9, with an emphasis on roughness heights of less than 55 percent of the local boundary layer thickness. The Mach 5.9 cases include flow conditions that are relevant to both ground facility experiments and high altitude flight ("cold wall" case). Regardless of the Mach number, the mean flow distortion due to the roughness element is characterized by long-lived streamwise streaks in the roughness wake, which can support instability modes that did not exist in the absence of the roughness element. The higher Mach number cases reveal a variety of instability mode shapes with velocity fluctuations concentrated in different localized regions of high base flow shear. The high shear regions vary from the top of a mushroom shaped structure characterizing the centerline streak to regions that are concentrated on the sides of the mushroom. Unlike the Mach 3.5 case with nearly same values of scaled roughness height k/delta and roughness height Reynolds number Re(sub kk), the odd wake modes in both Mach 5.9 cases are significantly more unstable than the even modes of instability. Additional computations for a Mach 3.5 boundary layer indicate that the presence of a roughness element can also enhance the amplification of first mode instabilities incident from upstream. Interactions between multiple roughness elements aligned along the flow direction are also explored.

Thin layer model for nonlinear evolution of the Rayleigh-Taylor instability

Science.gov (United States)

Zhao, K. G.; Wang, L. F.; Xue, C.; Ye, W. H.; Wu, J. F.; Ding, Y. K.; Zhang, W. Y.

2018-03-01

On the basis of the thin layer approximation [Ott, Phys. Rev. Lett. 29, 1429 (1972)], a revised thin layer model for incompressible Rayleigh-Taylor instability has been developed to describe the deformation and nonlinear evolution of the perturbed interface. The differential equations for motion are obtained by analyzing the forces (the gravity and pressure difference) of fluid elements (i.e., Newton's second law). The positions of the perturbed interface are obtained from the numerical solution of the motion equations. For the case of vacuum on both sides of the layer, the positions of the upper and lower interfaces obtained from the revised thin layer approximation agree with that from the weakly nonlinear (WN) model of a finite-thickness fluid layer [Wang et al., Phys. Plasmas 21, 122710 (2014)]. For the case considering the fluids on both sides of the layer, the bubble-spike amplitude from the revised thin layer model agrees with that from the WN model [Wang et al., Phys. Plasmas 17, 052305 (2010)] and the expanded Layzer's theory [Goncharov, Phys. Rev. Lett. 88, 134502 (2002)] in the early nonlinear growth regime. Note that the revised thin layer model can be applied to investigate the perturbation growth at arbitrary Atwood numbers. In addition, the large deformation (the large perturbed amplitude and the arbitrary perturbed distributions) in the initial stage can also be described by the present model.

Study of effect of a smooth hump on hypersonic boundary layer instability

Science.gov (United States)

Park, Donghun; Park, Seung O.

2016-12-01

Effect of a two-dimensional smooth hump on linear instability of hypersonic boundary layer is studied by using parabolized stability equations. Linear evolution of mode S over a hump is analyzed for Mach 4.5 and 5.92 flat plate and Mach 7.1 sharp cone boundary layers. Mean flow for stability analysis is obtained by solving the parabolized Navier-Stokes equations. Hump with height smaller than local boundary layer thickness is considered. The case of flat plate and sharp cone without the hump are also studied to provide comparable data. For flat plate boundary layers, destabilization and stabilization effect is confirmed for hump located at upstream and downstream of synchronization point, respectively. Results of parametric studies to examine the effect of hump height, location, etc., are also given. For sharp cone boundary layer, stabilization influence of hump is also identified for a specific range of frequency. Stabilization influence of hump on convective instability of mode S is found to be a possible cause of previous experimental observations of delaying transition in hypersonic boundary layers.

The electron-electron instability in a spherical plasma structure with an intermediate double layer

International Nuclear Information System (INIS)

Lapuerta, V.; Ahedo, E.

2003-01-01

A linear dynamic model of a spherical plasma structure with an intermediate double layer is analyzed in the high-frequency range. The two ion populations tend to stay frozen in their stationary response and this prevents the displacement of the double layer. Different electron modes dominate the plasma dynamics in each quasineutral region. The electrostatic potential and the electron current are the magnitudes most perturbed. The structure develops a reactive electron-electron instability, which is made up of a countable family of eigenmodes. Space-charge effects must be included in the quasineutral regions to determine the eigenmode carrying the maximum growth rate. Except for very small Debye lengths, the fundamental eigenmode governs the instability. The growth rate for the higher harmonics approaches that of an infinite plasma. The instability modes develop mainly on the plasma at the high-potential side of the double layer. The influence of the parameters defining the stationary solution on the instability growth rate is investigated, and the parametric regions of stability are found. The comparison with a couple of experiments on plasma contactors is satisfactory

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.

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

Directory of Open Access Journals (Sweden)

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.

The Rayleigh-Taylor instability in a self-gravitating two-layer fluid sphere

International Nuclear Information System (INIS)

Ida, Shigeru; Nakagawa, Yoshitsugu; Nakazawa, Kiyoshi

1989-01-01

The Rayleigh-Taylor instability is studied in a self-gravitating two-layer fluid sphere: an inner sphere and an outer layer. The density and the viscosity are assumed to be constant in each region. Analytic expressions of the dispersion relations are obtained in inviscid and viscid cases. This examination aims at the investigation of the Earth's core formation. The fluid sphere corresponds to the proto-Earth in the accretion stage. The instability is examined without rotation of the fluid sphere, while the proto-Earth is rotating. However, it is shown that the Coriolis force does not influence the conclusion in the Earth's core formation problem. 5 refs.; 10 figs

An Experimental Study of Roughness-Induced Instabilities in a Supersonic Boundary Layer

Science.gov (United States)

Kegerise, Michael A.; King, Rudolph A.; Choudhari, Meelan; Li, Fei; Norris, Andrew

2014-01-01

Progress on an experimental study of laminar-to-turbulent transition induced by an isolated roughness element in a supersonic laminar boundary layer is reported in this paper. Here, the primary focus is on the effects of roughness planform shape on the instability and transition characteristics. Four different roughness planform shapes were considered (a diamond, a circle, a right triangle, and a 45 degree fence) and the height and width of each one was held fixed so that a consistent frontal area was presented to the oncoming boundary layer. The nominal roughness Reynolds number was 462 and the ratio of the roughness height to the boundary layer thickness was 0.48. Detailed flow- field surveys in the wake of each geometry were performed via hot-wire anemometry. High- and low-speed streaks were observed in the wake of each roughness geometry, and the modified mean flow associated with these streak structures was found to support a single dominant convective instability mode. For the symmetric planform shapes - the diamond and circular planforms - the instability characteristics (mode shapes, growth rates, and frequencies) were found to be similar. For the asymmetric planform shapes - the right-triangle and 45 degree fence planforms - the mode shapes were asymmetrically distributed about the roughness-wake centerline. The instability growth rates for the asymmetric planforms were lower than those for the symmetric planforms and therefore, transition onset was delayed relative to the symmetric planforms.

The enhancement of neutral metal Na layer above thunderstorms

Science.gov (United States)

Yu, Bingkun; Xue, Xianghui; Lu, Gaopeng; Kuo, Chengling; Dou, Xiankang; Gao, Qi; Qie, Xiushu; Wu, Jianfei; Tang, Yihuan

2017-04-01

Na (sodium) exists as layers of atoms in the mesosphere/lower thermosphere (MLT) at altitudes between 80 and 105 km. It has lower ionization potential of 5.139 eV than atmospheric species, such as O2 (12.06 eV). Tropospheric thunderstorms affect the lower ionosphere and the ionospheric sporadic E (Es) at 100 km can also be influenced by lightning. The mechanism is expected to be associated with transient luminous events (TLE) as red sprites and gigantic jets at upper atmosphere. However, measurements of ionospheric electric fields of 20mV·m-1 above thunderstorms are less than estimated value (>48 0mV·m-1) to excite ionization in the lower ionosphere. We found an enhancement of Na layer above thunderstorms. The increase of Na density in the statistical result can be as much as 500 cm-3 and it will have an impact on ionospheric chemistry and modify the conductivity properties of the MLT region. The ionospheric observations made with two digisondes near the Na lidar, the thunderstorm model, ionosphere model, and Na chemistry model are all used to discuss the possible mechanisms responsible for the enhancement of Na layer after thunderstorms.

SECULAR GRAVITATIONAL INSTABILITY OF A DUST LAYER IN SHEAR TURBULENCE

International Nuclear Information System (INIS)

Michikoshi, Shugo; Kokubo, Eiichiro; Inutsuka, Shu-ichiro

2012-01-01

We perform a linear stability analysis of a dust layer in a turbulent gas disk. Youdin investigated the secular gravitational instability (GI) of a dust layer using hydrodynamic equations with a turbulent diffusion term. We obtain essentially the same result independently of Youdin. In the present analysis, we restrict the area of interest to small dust particles, while investigating the secular GI in a more rigorous manner. We discuss the time evolution of the dust surface density distribution using a stochastic model and derive the advection-diffusion equation. The validity of the analysis by Youdin is confirmed in the strong drag limit. We demonstrate quantitatively that the finite thickness of a dust layer weakens the secular GI and that the density-dependent diffusion coefficient changes the growth rate. We apply the results obtained to the turbulence driven by the shear instability and find that the secular GI is faster than the radial drift when the gas density is three times as large as that in the minimum-mass disk model. If the dust particles are larger than chondrules, the secular GI grows within the lifetime of a protoplanetary disk.

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.

Görtler instability of the axisymmetric boundary layer along a cone

Science.gov (United States)

ITOH, Nobutake

2014-10-01

Exact partial differential equations are derived to describe Görtler instability, caused by a weakly concave wall, of axisymmetric boundary layers with similar velocity profiles that are decomposed into a sequence of ordinary differential systems on the assumption that the solution can be expanded into inverse powers of local Reynolds number. The leading terms of the series solution are determined by solving a non-parallel version of Görtler’s eigenvalue problem and lead to a neutral stability curve and finite values of critical Görtler number and wave number for stationary and longitudinal vortices. Higher-order terms of the series solution indicate Reynolds-number dependence of Görtler instability and a limited validity of Görtler’s approximation based on the leading terms only. The present formulation is simply applicable to two-dimensional boundary layers of similar profiles, and critical Görtler number and wave number of the Blasius boundary layer on a flat plate are given by G2c = 1.23 and β2c = 0.288, respectively, if the momentum thickness is chosen as the reference length.

Magnetohydrodynamic Kelvin-Helmholtz instabilities in astrophysics. 3. Hydrodynamic flows with shear layers

Energy Technology Data Exchange (ETDEWEB)

Ferraro, A [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Max-Planck-Institut fuer Extraterrestrische Physik, Garching (Germany, F.R.)); Massaglia, S [Turin Univ. (Italy). Ist. di Fisica; Trussoni, E [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica

1982-03-01

In this paper a discussion is presented on Kelvin-Helmholtz instabilities in pressure-confined two-dimensional flows (slabs) delimited by boundary layers with velocity and density gradients. It is found that the fastest growing modes in supersonic flows are produced by perturbations reflecting at the boundaries and have wavelengths of the order of the slab width; this peak of instability is even more evident than in the case of vortex-sheet cylindrical flows, discussed in a previous paper. From a comparison of the results for the two-dimensional slab and three-dimensional cylinder it is concluded that a two-dimensional treatment provides an adequate description of instabilities in fluid flows. In this analogy, symmetric and antisymmetric modes in the slab correspond to pinching and helical modes in the cylinder. In the final section a comparison is attempted of the results obtained with morphologies in collimated jets in extragalactic radio sources; general characteristics appear to be classifiable in terms of scale-lengths of the velocity and density gradients in the boundary layers.

Taylor-Goertler instabilities of Tollmien-Schlichting waves and other flows governed by the interactive boundary-layer equations

Science.gov (United States)

Hall, Philip; Bennett, James

1986-01-01

The Taylor-Goertler vortex instability equations are formulated for steady and unsteady interacting boundary-layer flows. The effective Goertler number is shown to be a function of the wall shape in the boundary layer and the possibility of both steady and unsteady Taylor-Goertler modes exists. As an example the steady flow in a symmetrically constricted channel is considered and it is shown that unstable Goertler vortices exist before the boundary layers at the wall develop the Goldstein singularity discussed by Smith and Daniels (1981). As an example of an unsteady spatially varying basic state, it is considered the instability of high-frequency large-amplitude two- and three-dimensional Tollmien-Schlichting waves in a curved channel. It is shown that they are unstable in the first 'Stokes-layer stage' of the hierarchy of nonlinear states discussed by Smith and Burggraf (1985). This instability of Tollmien-Schlichting waves in an internal flow can occur in the presence of either convex or concave curvature. Some discussion of this instability in external flows is given.

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.

Instabilities in fluid layers and in reaction-diffusion systems: Steady states, time-periodic solutions, non-periodic attractors, and related convective and otherwise non-linear phenomena

International Nuclear Information System (INIS)

Garcia Velarde, M.

1977-01-01

Thermoconvective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Benard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (author) [es

Dynamics Evolution Investigation of Mack Mode Instability in a Hypersonic Boundary Layer by Bicoherence Spectrum Analysis

Science.gov (United States)

Han, Jian; Jiang, Nan

2012-07-01

The instability of a hypersonic boundary layer on a cone is investigated by bicoherence spectrum analysis. The experiment is conducted at Mach number 6 in a hypersonic wind tunnel. The time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface along streamwise direction to investigate the development of the unstable disturbances. The bicoherence spectrum analysis based on wavelet transform is employed to investigate the nonlinear interactions of the instability of Mack modes in hypersonic laminar boundary layer transition. The results show that wavelet bicoherence is a powerful tool in studying the unstable mode nonlinear interaction of hypersonic laminar-turbulent transition. The first mode instability gives rise to frequency shifts to higher unstable modes at the early stage of hypersonic laminar-turbulent transition. The modulations subsequently lead to the second mode instability occurrence. The second mode instability governs the last stage of instability and final breakdown to turbulence with multi-scale disturbances growth.

Dynamics Evolution Investigation of Mack Mode Instability in a Hypersonic Boundary Layer by Bicoherence Spectrum Analysis

International Nuclear Information System (INIS)

Han Jian; Jiang Nan

2012-01-01

The instability of a hypersonic boundary layer on a cone is investigated by bicoherence spectrum analysis. The experiment is conducted at Mach number 6 in a hypersonic wind tunnel. The time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface along streamwise direction to investigate the development of the unstable disturbances. The bicoherence spectrum analysis based on wavelet transform is employed to investigate the nonlinear interactions of the instability of Mack modes in hypersonic laminar boundary layer transition. The results show that wavelet bicoherence is a powerful tool in studying the unstable mode nonlinear interaction of hypersonic laminar-turbulent transition. The first mode instability gives rise to frequency shifts to higher unstable modes at the early stage of hypersonic laminar-turbulent transition. The modulations subsequently lead to the second mode instability occurrence. The second mode instability governs the last stage of instability and final breakdown to turbulence with multi-scale disturbances growth. (fundamental areas of phenomenology(including applications))

The Rayleigh-Taylor instability in a self-gravitating two-layer viscous sphere

Science.gov (United States)

Mondal, Puskar; Korenaga, Jun

2018-03-01

The dispersion relation of the Rayleigh-Taylor instability in the spherical geometry is of profound importance in the context of the Earth's core formation. Here we present a complete derivation of this dispersion relation for a self-gravitating two-layer viscous sphere. Such relation is, however, obtained through the solution of a complex transcendental equation, and it is difficult to gain physical insights directly from the transcendental equation itself. We thus also derive an empirical formula to compute the growth rate, by combining the Monte Carlo sampling of the relevant model parameter space with linear regression. Our analysis indicates that the growth rate of Rayleigh-Taylor instability is most sensitive to the viscosity of inner layer in a physical setting that is most relevant to the core formation.

Gravity Wave Dynamics in a Mesospheric Inversion Layer: 1. Reflection, Trapping, and Instability Dynamics

Science.gov (United States)

Laughman, Brian; Wang, Ling; Lund, Thomas S.; Collins, Richard L.

2018-01-01

Abstract An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having a moderate static stability enhancement and a layer of weaker static stability above. Instabilities occur within the MIL when the GW amplitude approaches that required for GW breaking due to compression of the vertical wavelength accompanying the increasing static stability. Thus, MILs can cause large‐amplitude GWs to yield instabilities and turbulence below the altitude where they would otherwise arise. Smaller‐amplitude GWs encountering a MIL do not lead to instability and turbulence but do exhibit partial reflection and transmission, and the transmission is a smaller fraction of the incident GW when instabilities and turbulence arise within the MIL. Additionally, greater GW transmission occurs for weaker MILs and for GWs having larger vertical wavelengths relative to the MIL depth and for lower GW intrinsic frequencies. These results imply similar dynamics for inversions due to other sources, including the tropopause inversion layer, the high stability capping the polar summer mesopause, and lower frequency GWs or tides having sufficient amplitudes to yield significant variations in stability at large and small vertical scales. MILs also imply much stronger reflections and less coherent GW propagation in environments having significant fine structure in the stability and velocity fields than in environments that are smoothly varying. PMID:29576994

Görtler instability of the axisymmetric boundary layer along a cone

International Nuclear Information System (INIS)

ITOH, Nobutake

2014-01-01

Exact partial differential equations are derived to describe Görtler instability, caused by a weakly concave wall, of axisymmetric boundary layers with similar velocity profiles that are decomposed into a sequence of ordinary differential systems on the assumption that the solution can be expanded into inverse powers of local Reynolds number. The leading terms of the series solution are determined by solving a non-parallel version of Görtler’s eigenvalue problem and lead to a neutral stability curve and finite values of critical Görtler number and wave number for stationary and longitudinal vortices. Higher-order terms of the series solution indicate Reynolds-number dependence of Görtler instability and a limited validity of Görtler’s approximation based on the leading terms only. The present formulation is simply applicable to two-dimensional boundary layers of similar profiles, and critical Görtler number and wave number of the Blasius boundary layer on a flat plate are given by G 2c  = 1.23 and β 2c  = 0.288, respectively, if the momentum thickness is chosen as the reference length. (paper)

Unsteady Heat-Flux Measurements of Second-Mode Instability Waves in a Hypersonic Boundary Layer

Science.gov (United States)

Kergerise, Michael A.; Rufer, Shann J.

2016-01-01

In this paper we report on the application of the atomic layer thermopile (ALTP) heat- flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are in agreement with data previously reported in the literature. Heat flux time series, and the Morlet-wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was developed to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

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)

CAUSAS DE MORTE E RAZÕES PARA EUTANÁSIA DE CÃES

OpenAIRE

Rafael Almeida Fighera

2008-01-01

A crescente aproximação afetiva entre os cães e o homem fez com que nos últimos anos fosse gerada muita informação científica sobre medicina canina. Entretanto, como a maior parte dessas informações é obtida através da literatura internacional, é comum que os clínicos e patologistas veterinários brasileiros necessitem extrapolar dados referentes à prevalência das diferentes doenças que causam morte de cães para nossa realidade. Baseado nisso, este estudo tem como objetivo principal dete...

Convective instability in a time-dependent buoyancy driven boundary layer

Energy Technology Data Exchange (ETDEWEB)

Brooker, A.M.H.; Patterson, J.C.; Graham, T.; Schoepf, W. [University of Western Australia, Nedlands (Australia). Centre for Water Research

2000-01-01

The stability of the parallel time-dependent boundary layer adjacent to a suddenly heated vertical wall is described. The flow is investigated through experiments in water, through direct numerical simulation and also through linear stability analysis. The full numerical simulation of the flow shows that small perturbations to the wall boundary conditions, that are also present in the experimental study, are responsible for triggering the instability. As a result, oscillatory behaviour in the boundary layer is observed well before the transition to a steady two-dimensional flow begins. The properties of the observed oscillations are compared with those predicted by a linear stability analysis of the unsteady boundary layer using a quasi-stationary assumption and also using non-stationary assumptions by the formulation of parabolized equations (PSE). (Author)

The origin and structure of streak-like instabilities in laminar boundary layer flames

Science.gov (United States)

Gollner, Michael; Miller, Colin; Tang, Wei; Finney, Mark

2017-11-01

Streamwise streaks are consistently observed in wildland fires, at the base of pool fires, and in other heated flows within a boundary layer. This study examines both the origin of these structures and their role in influencing some of the macroscopic properties of the flow. Streaks were reproduced and characterized via experiments on stationary heated strips and liquid and gas-fueled burners in laminar boundary layer flows, providing a framework to develop theory based on both observed and measured physical phenomena. The incoming boundary layer was established as the controlling mechanism in forming streaks, which are generated by pre-existing coherent structures, while the amplification of streaks was determined to be compatible with quadratic growth of Rayleigh-Taylor Instabilities, providing credence to the idea that the downstream growth of streaks is strongly tied to buoyancy. These local instabilities were also found to affect macroscopic properties of the flow, including heat transfer to the surface, indicating that a two-dimensional assumption may fail to adequately describe heat and mass transfer during flame spread and other reacting boundary layer flows. This work was supported by NSF (CBET-1554026) and the USDA-FS (13-CS-11221637-124).

Search for Rayleigh-Taylor instability in laser irradiated layered thin foil targets

International Nuclear Information System (INIS)

Kilkenny, J.D.; Hares, J.D.; Rumsby, P.T.

1980-01-01

An experiment to measure the Rayleigh-Taylor instability at the vacuum-ablation surface of laser irradiated layered targets by time resolved x-ray spectroscopy is described. The time taken to burn through a layer of material is measured to be the same for massive targets as for thin foil accelerating targets. It is inferred that the thin foil targets might be Rayleigh-Taylor stable despite the values of γtauapproximately equal to15 calculated from classical theory. (author)

On the secondary instability of three-dimensional boundary layers

Energy Technology Data Exchange (ETDEWEB)

Janke, E. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Goettingen (Germany). Inst. fuer Stroemungsmechanik; Balakumar, P. [Department of Aerospace Engineering, Old Dominion University, Norfolk, VA 23529 (United States)

2000-09-01

One of the possible transition scenarios in three-dimensional boundary layers, the saturation of stationary crossflow vortices and their secondary instability to high-frequency disturbances, is studied using the parabolized stability equations (PSE) and Floquet theory. Starting from nonlinear PSE solutions, we investigate the region where a purely stationary crossflow disturbance saturates for its secondary instability characteristics utilizing global and local eigenvalue solvers that are based on the implicitly restarted Arnoldi method and a Newton-Raphson technique, respectively. Results are presented for swept Hiemenz flow and the DLR swept flat plate experiment. The main focuses of this study are on the existence of multiple roots in the eigenvalue spectrum that could explain experimental observations of time-dependent occurrences of an explosive growth of traveling disturbances, on the origin of high-frequency disturbances, as well as on gaining more information about threshold amplitudes of primary disturbances necessary for the growth of secondary disturbances. (orig.)

Anisotropic gravitational instability

International Nuclear Information System (INIS)

Polyachenko, V.L.; Fridman, A.M.

1988-01-01

Exact solutions of stability problems are obtained for two anisotropic gravitational systems of different geometries - a layer of finite thickness at rest and a rotating cylinder of finite radius. It is shown that the anisotropic gravitational instability which develops in both cases is of Jeans type. However, in contrast to the classical aperiodic Jeans instability, this instability is oscillatory. The physics of the anisotropic gravitational instability is investigated. It is shown that in a gravitating layer this instability is due, in particular, to excitation of previously unknown interchange-Jeans modes. In the cylinder, the oscillatory Jeans instability is associated with excitation of a rotational branch, this also being responsible for the beam gravitational instability. This is the reason why this instability and the anisotropic gravitational instability have so much in common

Ionospheric response to a recurrent magnetic storm during an event of High Speed Stream in October 2016.

Science.gov (United States)

Nicoli Candido, C. M.; Resende, L.; Becker-Guedes, F.; Batista, I. S.

2017-12-01

In this work we investigate the response of the low latitude ionosphere to recurrent geomagnetic activity caused by events of High speed streams (HSSs)/Corotating Interaction Regions (CIRs) during the low descending phase of solar activity in the solar cycle 24. Intense magnetic field regions called Corotating Interaction Regions or CIRs are created by the interaction of fast streams and slow streams ejected by long duration coronal holes in Sun. This interaction leads to an increase in the mean interplanetary magnetic field (IMF) which causes moderate and recurrent geomagnetic activity when interacts with the Earth's magnetosphere. The ionosphere can be affected by these phenomena by several ways, such as an increase (or decrease) of the plasma ionization, intensification of plasma instabilities during post-sunset/post-midnight hours and subsequent development of plasma irregularities/spread-F, as well as occurrence of plasma scintillation. Therefore, we investigate the low latitude ionospheric response during moderate geomagnetic storm associated to an event of High Speed Stream occurred during decreasing phase of solar activity in 2016. An additional ionization increasing is observed in Es layer during the main peak of the geomagnetic storm. We investigate two possible different mechanisms that caused these extras ionization: the role of prompt penetration of interplanetary electric field, IEFEy at equatorial region, and the energetic electrons precipitation on the E and F layers variations. Finally, we used data from Digisondes installed at equatorial region, São Luís, and at conjugate points in Brazilian latitudes, Boa Vista and Cachoeira Paulista. We analyzed the ionospheric parameters such as the critical frequency of F layer, foF2, the F layer peak height, hmF2, the F layer bottomside, h'F, the blanketing frequency of sporadic layer, fbEs, the virtual height of Es layer h'Es and the top frequency of the Es layer ftEs during this event.

Rosenzweig instability in a thin layer of a magnetic fluid

Science.gov (United States)

Korovin, V. M.

2013-12-01

A simple mathematical model of the initial stage of nonlinear evolution of the Rosenzweig instability in a thin layer of a nonlinearly magnetized viscous ferrofluid coating a horizontal nonmagnetizable plate is constructed on the basis of the system of equations and boundary conditions of ferrofluid dynamics. A dispersion relation is derived and analyzed using the linearized equations of this model. The critical magnetization of the initial layer with a flat free surface, the threshold wavenumber, and the characteristic time of evolution of the most rapidly growing mode are determined. The equation for the neutral stability curve, which is applicable for any physically admissible law of magnetization of a ferrofluid, is derived analytically.

Topographic-driven instabilities in terrestrial bodies

Science.gov (United States)

Vantieghem, S.; Cebron, D.; Herreman, W.; Lacaze, L.

2013-12-01

Models of internal planetary fluid layers (core flows, subsurface oceans) commonly assume that these fluid envelopes have a spherical shape. This approximation however entails a serious restriction from the fluid dynamics point of view. Indeed, in the presence of mechanical forcings (precession, libration, nutation or tides) due to gravitational interaction with orbiting partners, boundary topography (e.g. of the core-mantle boundary) may excite flow instabilities and space-filling turbulence. These phenomena may affect heat transport and dissipation at the main order. Here, we focus on instabilities driven by longitudinal libration. Using a suite of theoretical tools and numerical simulations, we are able to discern a parameter range for which instability may be excited. We thereby consider deformations of different azimuthal order. This study gives the first numerical evidence of the tripolar instability. Furthermore, we explore the non-linear regime and investigate the amplitude as well as the dissipation of the saturated instability. Indeed, these two quantities control the torques on the solid layers and the thermal transport. Furthermore, based on this results, we address the issue of magnetic field generation associated with these flows (by induction or by dynamo process). This instability mechanism applies to both synchronized as non-synchronized bodies. As such, our results show that a tripolar instability might be present in various terrestrial bodies (Early Moon, Gallilean moons, asteroids, etc.), where it could participate in dynamo action. Simulation of a libration-driven tripolar instability in a deformed spherical fluid layer: snapshot of the velocity magnitude, where a complex 3D flow pattern is established.

Role of microsatellite instability in colon cancer

Directory of Open Access Journals (Sweden)

M. Yu. Fedyanin

2012-01-01

Full Text Available Coloncancer is among leading causes of cancer morbidity and mortality both inRussiaand worldwide. Development of molecular biology lead to decoding of carcinogenesis and tumor progression mechanisms. These processes require accumulation of genetic and epigenetic alterations in a tumor cell.Coloncancer carcinogenesis is characterized by mutations cumulation in genes controlling growth and differentiation of epithelial cells, which leads to their genetic instability. Microsatellite instability is a type of genetic instability characterized by deterioration of mismatch DNA repair. This leads to faster accumulation of mutations in DNA. Loss of mismatch repair mechanism can easily be diagnosed by length of DNA microsatellites. These alterations are termed microsatellite instability. They can be found both in hereditary and sporadic colon cancers. This review covers the questions of microsatellite instability, its prognostic and predictive value in colon cancer.

Unsteady heat-flux measurements of second-mode instability waves in a hypersonic flat-plate boundary layer

Science.gov (United States)

Kegerise, Michael A.; Rufer, Shann J.

2016-08-01

In this paper, we report on the application of the atomic layer thermopile (ALTP) heat-flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat-plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors, and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are consistent with data previously reported in the literature. Heat flux time series, and the Morlet wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was used to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

High historical values of foEs — Reality or artefact?

Czech Academy of Sciences Publication Activity Database

Laštovička, Jan; Boška, Josef; Burešová, Dalia; Kouba, Daniel

2012-01-01

Roč. 74, - (2012), s. 51-54 ISSN 1364-6826 R&D Projects: GA AV ČR IAA300420704; GA MŠk OC09009; GA AV ČR KJB300420904 Institutional research plan: CEZ:AV0Z30420517 Keywords : Ionosphere * Sporadic-E layer * Ionospheric measurements Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.417, year: 2012 http://www.sciencedirect.com/science/article/pii/S1364682611002811

Model of E-Cloud Instability in the Fermilab Recycler

Energy Technology Data Exchange (ETDEWEB)

Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2015-06-24

Simple model of electron cloud is developed in the paper to explain e-cloud instability of bunched proton beam in the Fermilab Recycler. The cloud is presented as an immobile snake in strong vertical magnetic field. The instability is treated as an amplification of the bunch injection errors from the batch head to its tail. Nonlinearity of the e-cloud field is taken into account. Results of calculations are compared with experimental data demonstrating good correlation.

A virtual remote sensing observation network for continuous, near-real-time monitoring of atmospheric instability

Science.gov (United States)

Toporov, Maria; Löhnert, Ulrich; Potthast, Roland; Cimini, Domenico; De Angelis, Francesco

2017-04-01

Short-term forecasts of current high-resolution numerical weather prediction models still have large deficits in forecasting the exact temporal and spatial location of severe, locally influenced weather such as summer-time convective storms or cool season lifted stratus or ground fog. Often, the thermodynamic instability - especially in the boundary layer - plays an essential role in the evolution of weather events. While the thermodynamic state of the atmosphere is well measured close to the surface (i.e. 2 m) by in-situ sensors and in the upper troposphere by satellite sounders, the planetary boundary layer remains a largely under-sampled region of the atmosphere where only sporadic information from radiosondes or aircraft observations is available. The major objective of the presented DWD-funded project ARON (Extramural Research Programme) is to overcome this observational gap and to design an optimized network of ground based microwave radiometers (MWR) and compact Differential Absorption Lidars (DIAL) for a continuous, near-real-time monitoring of temperature and humidity in the atmospheric boundary layer in order to monitor thermodynamic (in)stability. Previous studies showed, that microwave profilers are well suited for continuously monitoring the temporal development of atmospheric stability (i.e. Cimini et al., 2015) before the initiation of deep convection, especially in the atmospheric boundary layer. However, the vertical resolution of microwave temperature profiles is best in the lowest kilometer above the surface, decreasing rapidly with increasing height. In addition, humidity profile retrievals typically cannot be resolved with more than two degrees of freedom for signal, resulting in a rather poor vertical resolution throughout the troposphere. Typical stability indices used to assess the potential of convection rely on temperature and humidity values not only in the region of the boundary layer but also in the layers above. Therefore, satellite

Nonlinear Dynamics Mechanism of Rock Burst Induced by the Instability of the Layer-Crack Plate Structure in the Coal Wall in Deep Coal Mining

Directory of Open Access Journals (Sweden)

Yanlong Chen

2017-01-01

Full Text Available The instability of layer-crack plate structure in coal wall is one of the causes of rock burst. In the present paper, we investigate the formation and instability processes of layer-crack plate structure in coal wall by experiments and theoretical analysis. The results reveal that layer-crack plate structure formed near the free surface of the coal wall during the loading. During the formation of the layer-crack plate structure, the lateral displacement curve of the coal wall experiences a jagged variation, which suggests the nonlinear instability failure of the coal wall with a sudden release of the elastic energy. Then, a dynamic model for the stability analysis of the layer-crack plate structure was proposed, which takes consideration of the dynamic disturbance factor. Based on the dynamic model, the criterion for dynamic instability of the layer-crack plate structure was determined and demonstrated by an example. According to the analytical results, some control methods of dynamic stability of the layer-crack plate structure was put forward.

Genomic instability--an evolving hallmark of cancer.

Science.gov (United States)

Negrini, Simona; Gorgoulis, Vassilis G; Halazonetis, Thanos D

2010-03-01

Genomic instability is a characteristic of most cancers. In hereditary cancers, genomic instability results from mutations in DNA repair genes and drives cancer development, as predicted by the mutator hypothesis. In sporadic (non-hereditary) cancers the molecular basis of genomic instability remains unclear, but recent high-throughput sequencing studies suggest that mutations in DNA repair genes are infrequent before therapy, arguing against the mutator hypothesis for these cancers. Instead, the mutation patterns of the tumour suppressor TP53 (which encodes p53), ataxia telangiectasia mutated (ATM) and cyclin-dependent kinase inhibitor 2A (CDKN2A; which encodes p16INK4A and p14ARF) support the oncogene-induced DNA replication stress model, which attributes genomic instability and TP53 and ATM mutations to oncogene-induced DNA damage.

Radiative instabilities of atmospheric jets and boundary layers

International Nuclear Information System (INIS)

Candelier, J.

2010-01-01

Complex flows occur in the atmosphere and they can be source of internal gravity waves. We focus here on the sources associated with radiative and shear (or Kelvin-Helmholtz) instabilities. Stability studies of shear layers in a stably stratified fluid concern mainly cases where shear and stratification are aligned along the same direction. In these cases, Miles (1961) and Howard (1961) found a necessary condition for stability based on the Richardson number: Ri ≥ 1/4. In this thesis, we show that this condition is not necessary when shear and stratification are not aligned: we demonstrate that a two-dimensional planar Bickley jet can be unstable for all Richardson numbers. Although the most unstable mode remains 2D, we show there exists an infinite family of 3D unstable modes exhibiting a radiative structure. A WKBJ theory is found to provide the main characteristics of these modes. We also study an inviscid and stratified boundary layer over an inclined wall with non-Boussinesq and compressible effects. We show that this flow is unstable as soon as the wall is not horizontal for all Froude numbers and that strongly stratified 3D perturbations behave exactly like compressible 2D perturbations. Applications of the results to the jet stream and the atmospheric boundary layer are proposed. (author) [fr

Desenvolvimento motor e cognitivo de bebês de mães adolescentes e adultas: estudo longitudinal

Directory of Open Access Journals (Sweden)

Luana Silva de Borba

2015-07-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n4p438   Este estudo teve como objetivos investigar em bebês de mães adolescentes e adultas: (1 os fatores de risco para o desenvolvimento infantil; (2 as mudanças cognitivas e motoras ao longo de quatro meses, (3 as correlações entre o desenvolvimento motor e cognitivo ao longo de quatro meses. Estudo longitudinal com 40 bebês, 20 nascidos de mães adolescentes e 20 de mães adultas, provenientes dos municípios de Porto Alegre e Butiá, no Rio Grande do Sul, Brasil. Foram realizadas três avaliações do desenvolvimento motor e cognitivo, utilizando a Alberta Motor Infant Scale (AIMS e Bayley Scale of Infant Development II. Na postura supina da AIMS, observou-se diferença significativa entre os grupos na terceira avaliação. Os bebês das mães adolescentes apresentaram escores mais baixos em relação aos bebês de mães adultas. Os escores motores de cada postura da AIMS e o escore total AIMS apresentaram diferença significativa ao longo do tempo em geral e em cada grupo. O escore mental bruto da Bayley-II também apresentou diferença significativa ao longo do tempo em geral e em cada grupo. Observou-se associação positiva, forte e significativa entre os escores totais da AIMS e Bayley em todos os três momentos de avaliação no grupo de bebês de mães adolescentes e adultas. Pode-se concluir que bebês de mães adolescentes apresentaram-se piores na postura supina em relação aos bebês de mães adultas. Os desenvolvimentos motor e cognitivo se associaram significativamente em ambos os grupos ao longo do tempo.

E-P instability in the NSNS accumulator ring

Energy Technology Data Exchange (ETDEWEB)

Ruggiero, A.G.; Blaskiewicz, M.

1997-08-01

It has been speculated that the intensity limitation observed in the Los Alamos Proton Storage Ring (PSR) is caused by a coherent instability induced by the presence of pockets of electrons generated by scattering with the molecules of the vacuum residual gas. A theoretical explanation of the e-p instability of course does exist, and is similar to the one developed for the ion-induced instability in electron storage rings. Considering the large beam power (3 MW) involved in the NSNS Accumulator Ring, and the consequences caused by even a small amount of beam loss, we need to carefully assess the effects of electrons that may be generated in the vacuum chamber.

Concentra??o nas exporta??es de eletroeletr?nicos do Polo Industrial de Manaus: aspectos quantitativos e percep??es institucionais

OpenAIRE

Lopes, Vitor Cesar Pican?o

2012-01-01

Esta disserta??o tem como objetivo principal analisar a evolu??o da concentra??o das exporta??es do Subsetor de Eletroeletr?nicos do Polo Industrial de Manais - PIM, verificando as poss?veis implica??es de tal fen?meno em termos de afeta??o no ?mbito comercial do mesmo. Os dados da pesquisa compreendem dois n?veis: dados secund?rios de com?rcio exterior, provenientes dos sistemas de acompanhamento e controle do fluxo de exporta??es do Minist?rio da Ind?stria e Com?rcio MDIC e Superint...

Magnetohydrodynamic Kelvin-Helmholtz instabilities in astrophysics. 1. Relativistic flows-plane boundary layer in vortex sheet approximation

Energy Technology Data Exchange (ETDEWEB)

Ferrari, A; Trussoni, E; Zaninetti, L [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica)

1980-11-01

In this paper some unsolved problems of the linear MHD Kelvin-Helmholtz instability are re-examined, starting from the analysis of relativistic (and non-relativistic) flows in the approximation of a plane vortex sheet, for the contact layer between the fluids in relative motion. Results are discussed for a range of physical parameters in specific connection with application to models of jets in extragalactic radio sources. Other physical aspects of the instability will be considered in forthcoming papers.

Generation of Zonal Flow and Magnetic Field by Electromagnetic Planetary Waves in the Ionospheric E-Layer

Science.gov (United States)

Kahlon, L. Z.; Kaladze, T. D.

2017-12-01

We review the excitation of zonal flow and magnetic field by coupled electromagnetic (EM) ULF planetary waves in the Earth's ionospheric E layer. Coupling of different planetary low-frequency electromagnetic waves under the typical ionospheric E-layer conditions is revealed. Propagation of coupled internal-gravity-Alfvén (CIGA), coupled Rossby-Khantadze (CRK) and coupled Rossby-Alfvén-Khantadze (CRAK) waves is shown and studied. A set of appropriate nonlinear equations describing the interaction of such waves with sheared zonal flow is derived. The conclusion on the instability of short wavelength turbulence of such coupled waves with respect to the excitation of low-frequency and large-scale perturbation of the sheared zonal flow and sheared magnetic field is inferred. This nonlinear instability's mechanism is depended on the parametric excitation of triple finite-amplitude coupled waves leading to the inverse energy cascade towards the longer wavelength. The possibility of generation of the intense mean magnetic field is shown. Obtained growth rates are discussed for each considered coupled waves.

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.

Nonlinear Effects at the Fermilab Recycler e-Cloud Instability

Energy Technology Data Exchange (ETDEWEB)

Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2016-06-10

Theoretical analysis of e-cloud instability in the Fermilab Recycler is represented in the paper. The e-cloud in strong magnetic field is treated as a set of immovable snakes each being initiated by some proton bunch. It is shown that the instability arises because of injection errors of the bunches which increase in time and from bunch to bunch along the batch being amplified by the e-cloud electric field. The particular attention is given to nonlinear additions to the cloud field. It is shown that the nonlinearity is the main factor which restricts growth of the bunch amplitude. Possible role of the field free parts of the Recycler id discussed as well. Results of calculations are compared with experimental data demonstrating good correlation.

Kelvin-Helmholtz instability: the ``atom'' of geophysical turbulence?

Science.gov (United States)

Smyth, William

2017-11-01

Observations of small-scale turbulence in Earth's atmosphere and oceans have most commonly been interpreted in terms of the Kolmogorov theory of isotropic turbulence, despite the fact that the observed turbulence is significantly anisotropic due to density stratification and sheared large-scale flows. I will describe an alternative picture in which turbulence consists of distinct events that occur sporadically in space and time. The simplest model for an individual event is the ``Kelvin-Helmholtz (KH) ansatz'', in which turbulence relieves the dynamic instability of a localized shear layer. I will summarize evidence that the KH ansatz is a valid description of observed turbulence events, using microstructure measurements from the equatorial Pacific ocean as an example. While the KH ansatz has been under study for many decades and is reasonably well understood, the bigger picture is much less clear. How are the KH events distributed in space and time? How do different events interact with each other? I will describe some tentative steps toward a more thorough understanding.

Calage de la partie congestionnée du diagramme fondamental combinant données de boucles et données FCD

OpenAIRE

CLAIRAIS, Aurélien

2015-01-01

Malgré l'essor des données FCD, comme les données GPS, il n'existe pas de méthode de calage de diagramme fondamental basée sur ce type de données. Le rapport propose une méthode de calage al- liant données de boucles electromagnétiques et données FCD. La méthode est développée pour un tronçon simple sans entrée ni sortie. Le modèle utilisé est le modèle LWR associé à un diagramme fondamental triangulaire. La première partie donne une méthode pour simuler un front d'onde de congestion et des t...

Somatic mutations in mismatch repair genes in sporadic gastric carcinomas are not a cause but a consequence of the mutator phenotype

NARCIS (Netherlands)

Pinto, Mafalda; Wub, Ying; Mensink, Rob G. J.; Cirnes, Luis; Seruca, Raquel; Hofstra, Robert M. W.

2008-01-01

In hereditary nonpolyposis colorectal cancer (HNPCC), patients' mismatch repair (MMR) gene mutations cause MMR deficiency, leading to microsatellite instability (MSI-H). MSI-H is also found in a substantial fraction of sporadic gastric carcinomas (SGC), mainly due to MLH1 promoter hypermethylation,

Recurrent RECQL4 Imbalance and Increased Gene Expression Levels Are Associated with Structural Chromosomal Instability in Sporadic Osteosarcoma

Directory of Open Access Journals (Sweden)

Georges Maire

2009-03-01

Full Text Available Osteosarcoma (OS is an aggressive bone tumor with complex abnormal karyotypes and a highly unstable genome, exhibiting both numerical- and structural-chromosomal instability (N- and S-CIN. Chromosomal rearrangements and genomic imbalances affecting 8q24 are frequent in OS. RECQL4 gene maps to this cytoband and encodes a putative helicase involved in the fidelity of DNA replication and repair. This protective genomic function of the protein is relevant because often patients with Rothmund-Thomson syndrome have constitutional mutations of RECQL4 and carry a very high risk of developing OS. To determine the relative level of expression of RECQL4 in OS, 18 sporadic tumors were studied by reverse transcription–polymerase chain reaction. All tumors overexpressed RECQL4 in comparison to control osteoblasts, and fluorescence in situ hybridization analysis of tumor DNA showed that expression levels were strongly copy number–dependent. Relative N- and S-CIN levels were determined by classifying copy number transitions within array comparative genomic hybridization profiles and by enumerating the frequency of break-apart fluorescence in situ hybridization within 8q24 using region-specific and control probes. Although there was no evidence that disruption of 8q24 in OS led to an elevated expression of RECQL4, there was a marked association between increased overall levels of S-CIN, determined by copy number transition frequency and higher levels of RECQL4.

Magnetohydrodynamic Kelvin-Helmholtz instabilities in astrophysics. 2. Cylindrical boundary layer in vortex sheet approximation

Energy Technology Data Exchange (ETDEWEB)

Ferrari, A [Max-Planck-Institut fuer Extraterrestrische Physik, Garching b. Muenchen (Germany, F.R.); Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica); Trussoni, E; Zaninetti, L [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica

1981-09-01

This second paper of the series is devoted to Kelvin-Helmholtz instabilities in cylindrical boundary layer flows (jets). The vortex-sheet approximation is still used, and compressible flows are studied in subsonic, transonic, supersonic and relativistic regimes. Magnetic field effects are analysed, together with density contrast inside and outside the jet. The general result is that, due to the onset of a so-called reflection branch of resonant modes, jets are always unstable, both to pinching and helical perturbations with wavelengths of the order of the jet circumference. In particular the time-scales for instability are such that this certainly plays a significant part in the morphology and energetics of extended radio sources.

Manipulation and control of instabilities for surfactant-laden liquid film flowing down an inclined plane using a deformable solid layer

Science.gov (United States)

Tomar, Dharmendra S.; Sharma, Gaurav

2018-01-01

that for cases when the stabilizing contribution of surfactant is not sufficient for suppressing GL mode instability, a deformable solid coating could be employed to suppress free surface instability without triggering Marangoni or liquid-solid interfacial modes. Specifically, we have shown that for a given solid thickness, as the shear modulus of the solid layer decreases (i.e., the solid becomes more deformable) the GL mode instability is suppressed. With further decrease in shear modulus, the Marangoni and liquid-solid interfacial modes become unstable. Thus, there exists a stability window in terms of shear modulus where the surfactant-laden film flow remains stable even when the Marangoni number is below the critical value required for free surface instability suppression. Further, when the Marangoni number is greater than the critical value so that the GL mode remains stable in the rigid limit or with the deformable wall, the increase in wall deformability or solid thickness triggers Marangoni mode instability and, thus, renders a stable flow configuration into an unstable one. Thus, we show that the soft solid layer can be used to manipulate and control the stability of surfactant-laden film flows.

A nonlinear scenario for development of vortex layer instability in gravity field

International Nuclear Information System (INIS)

Goncharov, V. P.

2007-01-01

A Hamiltonian version of contour dynamics is formulated for models of constant-vorticity plane flows with interfaces. The proposed approach is used as a framework for a nonlinear scenario for instability development. Localized vortex blobs are analyzed as structural elements of a strongly perturbed wall layer of a vorticity-carrying fluid with free boundary in gravity field. Gravity and vorticity effects on the geometry and velocity of vortex structures are examined. It is shown that compactly supported nonlinear solutions (compactons) are candidates for the role of particle-like vortex structures in models of flow breakdown. An analysis of the instability mechanism demonstrates the possibility of a self-similar collapse. It is found that the vortex shape stabilizes at the final stage of the collapse, while the vortex sheet strength on its boundary increases as (t 0 - t) -1 , where t 0 is the collapse time

[Immunohistochemical examination of MSH2, PMS2, MLH1, MSH6 compared with the analysis of microsatellite instability in colon adenocarcinoma].

Science.gov (United States)

Raskin, G A; Ianus, G A; Kornilov, A V; Orlova, R V; Petrov, S V; Protasova, A É; Pozharisskiĭ, K M; Imianitov, E N

2014-01-01

Adenocarcinoma of the colon in 10-20% is associated with microsatellite instability, which can occur both in sporadic cancers and in hereditary nonpolyposis colon cancer. Our analysis of 195 cases of adenocarcinoma of the colon showed that microsatellite instability (MSI-H) was found only in 1.5% of patients. Subsequent choice of patients with suspected hereditary Lynch syndrome led to the identification of additional 17 patients with microsatellite instability. They passed an analysis of genes of repair system of unpaired nucleotides of DNA. The study showed that immunohistochemical staining of MSH2, MSH6, MLH1, PMS2 could effectively conduct a preliminary screening of the Lynch syndrome but was unable to divide cases of sporadic and hereditary MSI-H colon cancer.

Size scale dependence of compressive instabilities in layered composites in the presence of stress gradients

DEFF Research Database (Denmark)

Poulios, Konstantinos; Niordson, Christian Frithiof

2016-01-01

The compressive strength of unidirectionally or layer-wise reinforced composite materials in direction parallel to their reinforcement is limited by micro-buckling instabilities. Although the inherent compressive strength of a given material micro-structure can easily be determined by assessing its...... compressive stress but also on spatial stress or strain gradients, rendering failure initiation size scale dependent. The present work demonstrates and investigates the aforementioned effect through numerical simulations of periodically layered structures withnotches and holes under bending and compressive...... loads, respectively. The presented results emphasize the importance of the reinforcing layer thickness on the load carrying capacity of the investigated structures, at a constant volumetric fraction of the reinforcement. The observed strengthening at higher values of the relative layer thickness...

Absolute & Convective Instabilities in the Boundary Layer on a Rotating Sphere

Science.gov (United States)

Garrett, Stephen; Peake, Nigel

2001-11-01

We are concerned with absolute (AI) and convective instabilities (CI) in the boundary-layer on a sphere rotating in an otherwise still fluid. Both AI and CI are found at every latitude within specific parameter spaces. The local Reynolds number at the predicted onset of AI matches experimental data well for the onset of turbulence at ψ =30^o from the axis of rotation, beyond this latitude the discrepancy increases but remains relatively small below ψ =70^o. We suggest that this AI may cause the onset of transition. The results of the CI analysis show that a crossflow instability mode is the most dangerous below ψ =66^o. Above this latitude a streamline-curvature mode is found to be the most dangerous, which coincides with the appearance of reverse flow in the radial component of the mean flow. Our predictions of the Reynolds number and vortex angle at the onset of CI are consistent with existing experimental measurements. Close to the pole the predictions of each stability analysis are seen to approach those of existing rotating disk investigations.

Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

Czech Academy of Sciences Publication Activity Database

Kopecký, Vladimír; Hrabovský, Milan

2011-01-01

Roč. 31, č. 6 (2011), s. 827-838 ISSN 0272-4324 R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : dc arc jet * plasma jet oscillations * boundary layer instability * frequency spectra Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.602, year: 2011 http://www.springerlink.com/content/v160841757161758/

Thermomagnetic instabilities in a vertical layer of ferrofluid: nonlinear analysis away from a critical point

Energy Technology Data Exchange (ETDEWEB)

Dey, Pinkee; Suslov, Sergey A, E-mail: ssuslov@swin.edu.au [Department of Mathematics H38, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

2016-12-15

A finite amplitude instability has been analysed to discover the exact mechanism leading to the appearance of stationary magnetoconvection patterns in a vertical layer of a non-conducting ferrofluid heated from the side and placed in an external magnetic field perpendicular to the walls. The physical results have been obtained using a version of a weakly nonlinear analysis that is based on the disturbance amplitude expansion. It enables a low-dimensional reduction of a full nonlinear problem in supercritical regimes away from a bifurcation point. The details of the reduction are given in comparison with traditional small-parameter expansions. It is also demonstrated that Squire’s transformation can be introduced for higher-order nonlinear terms thus reducing the full three-dimensional problem to its equivalent two-dimensional counterpart and enabling significant computational savings. The full three-dimensional instability patterns are subsequently recovered using the inverse transforms The analysed stationary thermomagnetic instability is shown to occur as a result of a supercritical pitchfork bifurcation. (paper)

Thermomagnetic instabilities in a vertical layer of ferrofluid: nonlinear analysis away from a critical point

International Nuclear Information System (INIS)

Dey, Pinkee; Suslov, Sergey A

2016-01-01

A finite amplitude instability has been analysed to discover the exact mechanism leading to the appearance of stationary magnetoconvection patterns in a vertical layer of a non-conducting ferrofluid heated from the side and placed in an external magnetic field perpendicular to the walls. The physical results have been obtained using a version of a weakly nonlinear analysis that is based on the disturbance amplitude expansion. It enables a low-dimensional reduction of a full nonlinear problem in supercritical regimes away from a bifurcation point. The details of the reduction are given in comparison with traditional small-parameter expansions. It is also demonstrated that Squire’s transformation can be introduced for higher-order nonlinear terms thus reducing the full three-dimensional problem to its equivalent two-dimensional counterpart and enabling significant computational savings. The full three-dimensional instability patterns are subsequently recovered using the inverse transforms The analysed stationary thermomagnetic instability is shown to occur as a result of a supercritical pitchfork bifurcation. (paper)

Damping the e-p instability in the SNS accumulator ring

Science.gov (United States)

Evans, N. J.; Deibele, C.; Aleksandrov, A.; Xie, Z.

2018-03-01

A broadband, digital damper system for both transverse planes developed for the SNS accumulator ring has recently damped the first indications of the broadband 50-150 MHz e-p instability in a 1.2 MW neutron production beam. This paper presents details of the design and operation of the SNS damper system as well as results of active damping of the e-p instability in the SNS ring showing a reduction in power of betatron oscillation over the 10-300 MHz band of up to 70%. The spectral content of the beam during operation, with and without the damper system is presented and performance of the damper system is evaluated.

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 ...

Sporadi-E layer and metereological activity

Directory of Open Access Journals (Sweden)

C. Scotto

1995-06-01

Full Text Available Obscrvations of Es laycr performed at the ionospheric observatory of Rome from 1982 to 1989 have been used to investigate a possible correlation with cold front passages. Such a correlation may exist because of the AGW excited by tropospheric activity at cold front passages. A relationship with thunderclouds electrostatic field is also marginally considered. The treatment of data shows that the distributions of the frequencies of renection at cold front passages present only small differences compared to normal days, both for the f and for the I type; therefore, a correlation between Es layer anù meteorological activity cannot be affirmed.

Multimaterial Control of Instability in Soft Mechanical Metamaterials

Science.gov (United States)

Janbaz, Shahram; McGuinness, Molly; Zadpoor, Amir A.

2018-06-01

Soft mechanical metamaterials working on the basis of instability have numerous potential applications in the context of "machine materials." Controlling the onset of instability is usually required when rationally designing such metamaterials. We study the isolated and modulated effects of geometrical design and material distribution on the onset of instability in multimaterial cellular metamaterials. We use multimaterial additive manufacturing to fabricate cellular specimens whose unit cells are divided into void space, a square element, and an intermediate ligament. The ratio of the elastic modulus of the ligament to that of the square element [(EL)/(ES)] is changed by using different material types. Computational models are also developed, validated against experimental observations, and used to study a wide range of possible designs. The critical stress can be adjusted independently from the critical strain by changing the material type while keeping [(EL)/(ES)] constant. The critical strain shows a power-law relationship with [(EL)/(ES)] within the range [(EL)/(ES)]=0.1 - 10 . The void shape design alters the critical strain by up to threefold, while the combined effects of the void shape and material distribution cause up to a ninefold change in the critical strain. Our findings highlight the strong influence of material distribution on the onset of the instability and buckling mode.

On the instability of a 3-dimensional attachment line boundary layer: Weakly nonlinear theory and a numerical approach

Science.gov (United States)

Hall, P.; Malik, M. R.

1984-01-01

The instability of a three dimensional attachment line boundary layer is considered in the nonlinear regime. Using weakly nonlinear theory, it is found that, apart from a small interval near the (linear) critical Reynolds number, finite amplitude solutions bifurcate subcritically from the upper branch of the neutral curve. The time dependent Navier-Stokes equations for the attachment line flow have been solved using a Fourier-Chebyshev spectral method and the subcritical instability is found at wavenumbers that correspond to the upper branch. Both the theory and the numerical calculations show the existence of supercritical finite amplitude (equilibrium) states near the lower branch which explains why the observed flow exhibits a preference for the lower branch modes. The effect of blowing and suction on nonlinear stability of the attachment line boundary layer is also investigated.

On the instability of a three-dimensional attachment-line boundary layer - Weakly nonlinear theory and a numerical approach

Science.gov (United States)

Hall, P.; Malik, M. R.

1986-01-01

The instability of a three-dimensional attachment-line boundary layer is considered in the nonlinear regime. Using weakly nonlinear theory, it is found that, apart from a small interval near the (linear) critical Reynolds number, finite-amplitude solutions bifurcate subcritically from the upper branch of the neutral curve. The time-dependent Navier-Stokes equations for the attachment-line flow have been solved using a Fourier-Chebyshev spectral method and the subcritical instability is found at wavenumbers that correspond to the upper branch. Both the theory and the numerical calculations show the existence of supercritical finite-amplitude (equilibrium) states near the lower branch which explains why the observed flow exhibits a preference for the lower branch modes. The effect of blowing and suction on nonlinear stability of the attachment-line boundary layer is also investigated.

Alimenta??o e rede urbana na Amaz?nia brasileira: um estudo das transforma??es e perman?ncias nos h?bitos alimentares de idosas nas cidades de Tef?, Alvar?es e Uarini, Amazonas.

OpenAIRE

Costa, Ellen Anjos Camilo da

2014-01-01

A Amaz?nia ?, sem d?vida, uma ?rea de interesse para o estudo das diferen?as no acesso aos alimentos e, com o r?pido processo de moderniza??o via redes de comunica??o e com?rcio, impacta nos h?bitos alimentares, em especial nas pequenas e m?dias cidades. O principal objetivo desta disserta??o foi analisar na popula??o idosa (feminina) de tr?s cidades do Amazonas, Tef?, Alvar?es e Uarini, as transforma??es e perman?ncias dos h?bitos alimentares. Tem-se como hip?tese de an?lise que o formato da...

A method for the direct numerical simulation of hypersonic boundary-layer instability with finite-rate chemistry

International Nuclear Information System (INIS)

Marxen, Olaf; Magin, Thierry E.; Shaqfeh, Eric S.G.; Iaccarino, Gianluca

2013-01-01

A new numerical method is presented here that allows to consider chemically reacting gases during the direct numerical simulation of a hypersonic fluid flow. The method comprises the direct coupling of a solver for the fluid mechanical model and a library providing the physio-chemical model. The numerical method for the fluid mechanical model integrates the compressible Navier–Stokes equations using an explicit time advancement scheme and high-order finite differences. This Navier–Stokes code can be applied to the investigation of laminar-turbulent transition and boundary-layer instability. The numerical method for the physio-chemical model provides thermodynamic and transport properties for different gases as well as chemical production rates, while here we exclusively consider a five species air mixture. The new method is verified for a number of test cases at Mach 10, including the one-dimensional high-temperature flow downstream of a normal shock, a hypersonic chemical reacting boundary layer in local thermodynamic equilibrium and a hypersonic reacting boundary layer with finite-rate chemistry. We are able to confirm that the diffusion flux plays an important role for a high-temperature boundary layer in local thermodynamic equilibrium. Moreover, we demonstrate that the flow for a case previously considered as a benchmark for the investigation of non-equilibrium chemistry can be regarded as frozen. Finally, the new method is applied to investigate the effect of finite-rate chemistry on boundary layer instability by considering the downstream evolution of a small-amplitude wave and comparing results with those obtained for a frozen gas as well as a gas in local thermodynamic equilibrium

Secondary Instability of Second Modes in Hypersonic Boundary Layers

Science.gov (United States)

Li, Fei; Choudhari, Meelan M.; Chang, Chau-Lyan; White, Jeffery A.

2012-01-01

Second mode disturbances dominate the primary instability stage of transition in a number of hypersonic flow configurations. The highest amplification rates of second mode disturbances are usually associated with 2D (or axisymmetric) perturbations and, therefore, a likely scenario for the onset of the three-dimensionality required for laminar-turbulent transition corresponds to the parametric amplification of 3D secondary instabilities in the presence of 2D, finite amplitude second mode disturbances. The secondary instability of second mode disturbances is studied for selected canonical flow configurations. The basic state for the secondary instability analysis is obtained by tracking the linear and nonlinear evolution of 2D, second mode disturbances using nonlinear parabolized stability equations. Unlike in previous studies, the selection of primary disturbances used for the secondary instability analysis was based on their potential relevance to transition in a low disturbance environment and the effects of nonlinearity on the evolution of primary disturbances was accounted for. Strongly nonlinear effects related to the self-interaction of second mode disturbances lead to an upstream shift in the upper branch neutral location. Secondary instability computations confirm the previously known dominance of subharmonic modes at relatively small primary amplitudes. However, for the Purdue Mach 6 compression cone configuration, it was shown that a strong fundamental secondary instability can exist for a range of initial amplitudes of the most amplified second mode disturbance, indicating that the exclusive focus on subharmonic modes in the previous applications of secondary instability theory to second mode primary instability may not have been fully justified.

POD analysis of the instability mode of a low-speed streak in a laminar boundary layer

Science.gov (United States)

Deng, Si-Chao; Pan, Chong; Wang, Jin-Jun; Rinoshika, Akira

2017-12-01

The instability of one single low-speed streak in a zero-pressure-gradient laminar boundary layer is investigated experimentally via both hydrogen bubble visualization and planar particle image velocimetry (PIV) measurement. A single low-speed streak is generated and destabilized by the wake of an interference wire positioned normal to the wall and in the upstream. The downstream development of the streak includes secondary instability and self-reproduction process, which leads to the generation of two additional streaks appearing on either side of the primary one. A proper orthogonal decomposition (POD) analysis of PIV measured velocity field is used to identify the components of the streak instability in the POD mode space: for a sinuous/varicose type of POD mode, its basis functions present anti-symmetric/symmetric distributions about the streak centerline in the streamwise component, and the symmetry condition reverses in the spanwise component. It is further shown that sinuous mode dominates the turbulent kinematic energy (TKE) through the whole streak evolution process, the TKE content first increases along the streamwise direction to a saturation value and then decays slowly. In contrast, varicose mode exhibits a sustained growth of the TKE content, suggesting an increasing competition of varicose instability against sinuous instability.

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.

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.

Diurnal, seasonal, and interannual differences in the links of probabilities of derivation of different types Es with solar activity

Science.gov (United States)

Petrukhin, Venedict F.; Poddubnaya, I. V.; Ponomarev, Evgenij A.; Sutyrin, Nicolaj A.

2004-12-01

The analysis of the ionospheric data on Irkutsk obtained from 1960 to 1996 was made. Was shown, that the link of probabilities of observation of the sporadic derivations in E-region of ionosphere with solar activity (SA) essentially depends on time of day, season and correlation between solar and geophysical parameters. For different types of sporadic derivations this link has different character and with a different image varies with current of time. It is necessary to mark, that the link of night sporadic derivations (Es such as "f") with solar activity in the summer very high and practically does not vary in time (r=-0.897-/+0.04). The temporary course of coefficients of correlation between solar activity and probability of observation of sporadic stratums (r) of a different type varies depending on the season. Further, for stratums of a type "cl" and "l" the change r happens within increase of SA. At the same time, there is an abnormal behavior of height so f sporadic stratums such as "cl". There is an impression that in a considered time frame there is competition of two factors. One of them - solar activity, which in the norm supports the negative correlation link with frequency of observation and second - a factor of an unknown nature, which has caused evocative anomaly of altitude, becomes dominant above natural negative link.

A trickle instability

Science.gov (United States)

Bossa, Benjamin

2005-11-01

We address the problem of the free fall of a long, horizontal and narrow liquid layer squeezed in a vertical open Hele-Shaw cell. The layer destabilizes as it falls down, evolving into a series of liquid blobs linked together by thin bridges, which ultimately break, leaving the initially connex fluid layer as a set a disjointed drops. The mechanism of this instability is the onset of a vertical pressure gradient due to the curvature difference of the moving contact line between the advancing interface and the rear interface. This instability, whose growth rate scales with a non-trivial power of the capillary number, amplifies indifferently a broad band of wavenumbers because of the flat shape of its dispersion relation in the thin layer limit. We will finally comment on the nature of the final fragmentation process and drop size distributions.

Wavelet Cross-Spectrum Analysis of Multi-Scale Disturbance Instability and Transition on Sharp Cone Hypersonic Boundary Layer

International Nuclear Information System (INIS)

Jian, Han; Nan, Jiang

2008-01-01

Experimental measurement of hypersonic boundary layer stability and transition on a sharp cone with a half angle of 5° is carried out at free-coming stream Mach number 6 in a hypersonic wind tunnel. Mean and fluctuation surface-thermal-flux characteristics of the hypersonic boundary layer flow are measured by Pt-thin-film thermocouple temperature sensors installed at 28 stations on the cone surface along longitudinal direction. At hypersonic speeds, the dominant flow instabilities demonstrate that the growth rate of the second mode tends to exceed that of the low-frequency mode. Wavelet-based cross-spectrum technique is introduced to obtain the multi-scale cross-spectral characteristics of the fluctuating signals in the frequency range of the second mode. Nonlinear interactions both of the second mode disturbance and the first mode disturbance are demonstrated to be dominant instabilities in the initial stage of laminar-turbulence transition for hypersonic shear flow. (fundamental areas of phenomenology (including applications))

Linear and Weakly Nonlinear Instability of Shallow Mixing Layers with Variable Friction

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Irina Eglite

2018-01-01

Full Text Available Linear and weakly nonlinear instability of shallow mixing layers is analysed in the present paper. It is assumed that the resistance force varies in the transverse direction. Linear stability problem is solved numerically using collocation method. It is shown that the increase in the ratio of the friction coefficients in the main channel to that in the floodplain has a stabilizing influence on the flow. The amplitude evolution equation for the most unstable mode (the complex Ginzburg–Landau equation is derived from the shallow water equations under the rigid-lid assumption. Results of numerical calculations are presented.

A propagator matrix method for the Rayleigh-Taylor instability of multiple layers: a case study on crustal delamination in the early Earth

Science.gov (United States)

Mondal, Puskar; Korenaga, Jun

2018-03-01

The dispersion relation of the Rayleigh-Taylor instability, a gravitational instability associated with unstable density stratification, is of profound importance in various geophysical contexts. When more than two layers are involved, a semi-analytical technique based on the biharmonic formulation of Stokes flow has been extensively used to obtain such dispersion relation. However, this technique may become cumbersome when applied to lithospheric dynamics, where a number of layers are necessary to represent the continuous variation of viscosity over many orders of magnitude. Here, we present an alternative and more efficient method based on the propagator matrix formulation of Stokes flow. With this approach, the original instability problem is reduced to a compact eigenvalue equation whose size is solely determined by the number of primary density contrasts. We apply this new technique to the stability of the early crust, and combined with the Monte Carlo sensitivity analysis, we derive an empirical formula to compute the growth rate of the Rayleigh-Taylor instability for this particular geophysical setting. Our analysis indicates that the likelihood of crustal delamination hinges critically on the effective viscosity of eclogite.

Morphology of oesophagus and crop of the partrigde Rhynchotus rufescens (Tiramidae = Morfologia do esôfago e do papo de perdizes Rhynchotus rufescens (Tiramidae

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Juliana Regina Rossi

2006-04-01

Full Text Available Twenty adult partridges Rhynchotus rufescens were used to study themorphology of oesophagus and crop. Materials to the morphologic study were collected and lengths of the oesophagus and of the crop were measured. For histological study, fragments of the oesophagus and of the crop were stained routinely with Masson’s trichrome stain. Total oesophagus was larger in females. In the entrance of the thorax, itsventral wall is enlarged broadly, forming the crop, which is larger in males. Oesophagus mucosa is constituted by stratified squamous epithelium, with mucous glands and lymphatic tissues. There are three layers of smooth muscle, involved in serosa. The histological structure of the crop is similar to the oesophagus. The mucous glands are reduced in size and the lymphatic tissues are dispersed in the connective tissue. There is a thin stratum of smooth muscle and other two wider layers of longitudinal and circular musculature.Vinte exemplares de Rhynchotus rufescens foram utilizadas para estudar a morfologia do esôfago e do papo. O material para o estudo morfológico foi coletado e o comprimento dos órgãos foi avaliado. Para o estudo histológico, as secções histológicas foram coradas com tricromo de Masson, posteriormente analisadas e descritas. O comprimento médio total do esôfago foi maior em fêmeas. Na entrada do tórax, a parede ventral do esôfago se dilata, formando o papo, maior em machos. A mucosa do esôfago é formada por epitélio escamoso estratificado, com glândulas mucosas e nódulos linfáticos. Há três camadas de músculo liso, as quais são envolvidas por serosa. A característica histológica do papo é semelhante à do esôfago. No papo, as glândulas mucosas são menores e os nódulos linfáticos estão dispersos no tecido conjuntivo. Há uma camada delgada de músculo liso e outras duas camadas mais largas de musculaturas longitudinal e circular.

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.

Auto-estima pessoal e coletiva em mães e não-mães Personal and collective self-esteem in mothers and non-mothers

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Daniela Borges Lima de Souza

2005-04-01

Full Text Available O estudo investigou as implicações da condição de maternidade e de não-maternidade para a construção da auto-estima pessoal e coletiva das mulheres, mediante o teste das hipóteses de que os índices de auto-estima pessoal e de auto-estima coletiva obtidos por mulheres mães seriam significativamente maiores do que os índices obtidos por mulheres não-mães. A amostra foi composta por 310 mulheres, com idades variando entre 30 e 69 anos, distribuídas em um grupo de mães e um outro de não-mães, as quais foram solicitadas a responder às versões brasileiras da Escala de Auto-Estima de Rosenberg e da Escala de Auto-Estima Coletiva. A análise dos resultados revelou que as duas hipóteses do estudo foram corroboradas. Concluiu-se que as concepções e representações tradicionais acerca da maternidade ainda desempenham um importante papel na configuração da identidade feminina.The study investigates the motherhood and non-motherhood conditions, and its implications to women in their construction of personal and collective self-esteem. The hypotheses to be tested were that mothers would present personal and collective self-esteem indexes significantly greater than non-mothers. The sample consisted of 310 women, between 30 and 69 years of age, distributed in two groups, mothers and non-mothers. Both groups were asked to answer the Brazilian versions of the Rosenberg's Self-Esteem Scale and Collective Self-Esteem Scale. Results confirmed both hypotheses. It was concluded that traditional conceptions and representations of motherhood still play an important role in the construction of feminine identity.

Edge instability in incompressible planar active fluids

Science.gov (United States)

Nesbitt, David; Pruessner, Gunnar; Lee, Chiu Fan

2017-12-01

Interfacial instability is highly relevant to many important biological processes. A key example arises in wound healing experiments, which observe that an epithelial layer with an initially straight edge does not heal uniformly. We consider the phenomenon in the context of active fluids. Improving upon the approximation used by Zimmermann, Basan, and Levine [Eur. Phys. J.: Spec. Top. 223, 1259 (2014), 10.1140/epjst/e2014-02189-7], we perform a linear stability analysis on a two-dimensional incompressible hydrodynamic model of an active fluid with an open interface. We categorize the stability of the model and find that for experimentally relevant parameters, fingering instability is always absent in this minimal model. Our results point to the crucial role of density variation in the fingering instability in tissue regeneration.

C-Reactor I and E loading instability limits

Energy Technology Data Exchange (ETDEWEB)

Hess, K.W.

1957-01-24

The pilot charging of I & E fuel elements has been implemented at C-Reactor under Production Test IP-19-A. It was necessary to provide adequate tube protection against flow interruption by establishing proper trip setting on the Panellit pressure gauges. the administration of these Panellit trip settings is done by trip-before- boiling tube outlet temperature limits, which are similar in principle to the current instability limits. Trip-before-boiling limits for C-Reactor I & E fuel elements loadings are presented in this document.

Tearing instability in cylindrical plasma configuration

International Nuclear Information System (INIS)

Zelenyj, L.M.

1979-01-01

The effect of the neutral-layer cylindrical geometry on the development of the tearing instability has been investigated in detail. The increments of the instability for all the regimes have been found. The influence of cylindrical effects becomes manifesting itself at small, as compared to the layer characteristic thickness, distances from the axis, and, finally, the electron regime of the instability development transforms into an ion one. The results obtained are of interest for studying the plasma stability in the devices of the ''Astron'' type and in magnetospheres of cosmic objects

Faraday instability on patterned surfaces

Science.gov (United States)

Feng, Jie; Rubinstein, Gregory; Jacobi, Ian; Stone, Howard

2013-11-01

We show how micro-scale surface patterning can be used to control the onset of the Faraday instability in thin liquid films. It is well known that when a liquid film on a planar substrate is subject to sufficient vibrational accelerations, the free surface destabilizes, exhibiting a family of non-linear standing waves. This instability remains a canonical problem in the study of spontaneous pattern formation, but also has practical uses. For example, the surface waves induced by the Faraday instability have been studied as a means of enhanced damping for mechanical vibrations (Genevaux et al. 2009). Also the streaming within the unstable layer has been used as a method for distributing heterogeneous cell cultures on growth medium (Takagi et al. 2002). In each of these applications, the roughness of the substrate significantly affects the unstable flow field. We consider the effect of patterned substrates on the onset and behavior of the Faraday instability over a range of pattern geometries and feature heights where the liquid layer is thicker than the pattern height. Also, we describe a physical model for the influence of patterned roughness on the destabilization of a liquid layer in order to improve the design of practical systems which exploit the Faraday instability.

Multi-Layer E-Textile Circuits

Science.gov (United States)

Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

2012-01-01

Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

Suppression of photo-bias induced instability for amorphous indium tungsten oxide thin film transistors with bi-layer structure

Energy Technology Data Exchange (ETDEWEB)

Liu, Po-Tsun, E-mail: ptliu@mail.nctu.edu.tw; Chang, Chih-Hsiang; Chang, Chih-Jui [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

2016-06-27

This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO{sub 2} backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliability of device under NBTIS.

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

Interaction of plasma cloud with external electric field in lower ionosphere

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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.

Electron Debye scale Kelvin-Helmholtz instability: Electrostatic particle-in-cell simulations

International Nuclear Information System (INIS)

Lee, Sang-Yun; Lee, Ensang; Kim, Khan-Hyuk; Lee, Dong-Hun; Seon, Jongho; Jin, Ho

2015-01-01

In this paper, we investigated the electron Debye scale Kelvin-Helmholtz (KH) instability using two-dimensional electrostatic particle-in-cell simulations. We introduced a velocity shear layer with a thickness comparable to the electron Debye length and examined the generation of the KH instability. The KH instability occurs in a similar manner as observed in the KH instabilities in fluid or ion scales producing surface waves and rolled-up vortices. The strength and growth rate of the electron Debye scale KH instability is affected by the structure of the velocity shear layer. The strength depends on the magnitude of the velocity and the growth rate on the velocity gradient of the shear layer. However, the development of the electron Debye scale KH instability is mainly determined by the electric field generated by charge separation. Significant mixing of electrons occurs across the shear layer, and a fraction of electrons can penetrate deeply into the opposite side fairly far from the vortices across the shear layer

The Effect of Acoustic Forcing on Instabilities and Breakdown in Swept-Wing Flow over a Backward-Facing Step

Science.gov (United States)

Eppink, Jenna L.; Shishkov, Olga; Wlezien, Richard W.; King, Rudolph A.; Choudhari, Meelan

2016-01-01

Instability interaction and breakdown were experimentally investigated in the flow over a swept backward-facing step. Acoustic forcing was used to excite the Tollmien-Schlichting (TS) instability and to acquire phase-locked results. The phase-averaged results illustrate the complex nature of the interaction between the TS and stationary cross flow instabilities. The weak stationary cross flow disturbance causes a distortion of the TS wavefront. The breakdown process is characterized by large positive and negative spikes in velocity. The positive spikes occur near the same time and location as the positive part of the TS wave. Higher-order spectral analysis was used to further investigate the nonlinear interactions between the TS instability and the traveling cross flow disturbances. The results reveal that a likely cause for the generation of the spikes corresponds to nonlinear interactions between the TS, traveling cross flow, and stationary cross flow disturbances. The spikes begin at low amplitudes of the unsteady and steady disturbances (2-4% U (sub e) (i.e. boundary layer edge velocity)) but can achieve very large amplitudes (20-30 percent U (sub e) (i.e. boundary layer edge velocity)) that initiate an early, though highly intermittent, breakdown to turbulence.

Secondary instability and transition in three-dimensional boundary layers

Energy Technology Data Exchange (ETDEWEB)

Stolte, A.; Bertolotti, F.P.; Koch, W. (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany). Inst. fuer Stroemungsmechanik)

1999-01-01

Stationary and traveling crossflow modes are the most prominent disturbances in the highly accelerated three-dimensional flow near the leading edge of a swept wing. Near transition onset, secondary three-dimensional instabilities of high frequency can be observed in such flows. A model flow on the basis of a DLR swept plate experiment allows a detailed study of transition scenarios triggered by crossflow instabilities, since the favorable pressure gradient over the whole plate inhibits instabilities of Tollmien-Schlichting type. In order to shed some light upon the role of the high-frequency secondary instabilities, the saturation characteristics of crossflow vortices in this model flow are investigated using the parabolized stability equations. In contrast to nonlinear equilibrium solutions of steady crossflow vortices, the nonlinear Polarized Stability Equations (PSE) results yield different maximal disturbance amplitudes for different initial amplitudes. (orig./AKF)

Secondary instability and transition in three-dimensional boundary layers

Energy Technology Data Exchange (ETDEWEB)

Stolte, A.; Bertolotti, F.P.; Koch, W. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany). Inst. fuer Stroemungsmechanik

1999-12-01

Stationary and traveling crossflow modes are the most prominent disturbances in the highly accelerated three-dimensional flow near the leading edge of a swept wing. Near transition onset, secondary three-dimensional instabilities of high frequency can be observed in such flows. A model flow on the basis of a DLR swept plate experiment allows a detailed study of transition scenarios triggered by crossflow instabilities, since the favorable pressure gradient over the whole plate inhibits instabilities of Tollmien-Schlichting type. In order to shed some light upon the role of the high-frequency secondary instabilities, the saturation characteristics of crossflow vortices in this model flow are investigated using the parabolized stability equations. In contrast to nonlinear equilibrium solutions of steady crossflow vortices, the nonlinear Polarized Stability Equations (PSE) results yield different maximal disturbance amplitudes for different initial amplitudes. (orig./AKF)

Stabilization of the hypersonic boundary layer by finite-amplitude streaks

Science.gov (United States)

Ren, Jie; Fu, Song; Hanifi, Ardeshir

2016-02-01

Stabilization of two-dimensional disturbances in hypersonic boundary layer flows by finite-amplitude streaks is investigated using nonlinear parabolized stability equations. The boundary-layer flows at Mach numbers 4.5 and 6.0 are studied in which both first and second modes are supported. The streaks considered here are driven either by the so-called optimal perturbations (Klebanoff-type) or the centrifugal instability (Görtler-type). When the streak amplitude is in an appropriate range, i.e., large enough to modulate the laminar boundary layer but low enough to not trigger secondary instability, both first and second modes can effectively be suppressed.

Libration-Driven Elliptical Instability Experiments in Ellipsoidal Shells

Science.gov (United States)

Grannan, A. M.; Lemasquerier, D. G.; Favier, B.; Cebron, D.; Le Bars, M.; Aurnou, J. M.

2016-12-01

Planets and satellites can be subjected to physical libration, which consists in forced periodic variations in their rotation rate induced by gravitational interactions with nearby bodies. These librations may mechanically drive turbulence in interior liquid layers such as subsurface oceans and metallic liquid cores. One possible driving-process is called the Libration-Driven Elliptical Instability (LDEI) and refers to the resonance of two inertial modes with the libration induced base flow. LDEI has been experimentally and numerically studied in the case of a full ellipsoid (e.g. Cébron et al. [2012c], Grannan et al. [2014] and Favier et al. [2015]). In this study, we address the question of the persistence of the LDEI in the theoretically complex case of an ellipsoidal shell which is more geophysically relevant to model planetary liquid layers. We use an ellipsoidal acrylic container filled with water and add spherical inner cores of different sizes. We perform direct side-view visualizations of the flow in the librating frame using Kalliroscope particles. A Fourier analysis of the light intensity extracted from the recorded movies shows that LDEI persists in a shell geometry for a libration frequency which is 4 and 2.4 time the rotation rate, and allows an identification of the mode coupling. Particle Image Velocimetry (PIV) is performed in vertical and horizontal planes on a selected case to confirm our light intensity results. Additionaly, our survey at a fixed forcing-frequency and variable Ekman number (E) allows a comparison with a local stability analysis, and shows that the libration amplitude at the threshold of the instability varies as ≈[E0.63, E0.72]. When extrapolating to planetary interiors conditions, such a scaling leads to an easier excitation of the elliptical instability than the E0.5 scaling commonly considered.

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.

Rayleigh-Taylor and Richtmyer-Meshkov instability induced flow, turbulence, and mixing. I

Science.gov (United States)

Zhou, Ye

2017-12-01

Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities play an important role in a wide range of engineering, geophysical, and astrophysical flows. They represent a triggering event that, in many cases, leads to large-scale turbulent mixing. Much effort has been expended over the past 140 years, beginning with the seminal work of Lord Rayleigh, to predict the evolution of the instabilities and of the instability-induced mixing layers. The objective of Part I of this review is to provide the basic properties of the flow, turbulence, and mixing induced by RT, RM, and Kelvin-Helmholtz (KH) instabilities. Historical efforts to study these instabilities are briefly reviewed, and the significance of these instabilities is discussed for a variety of flows, particularly for astrophysical flows and for the case of inertial confinement fusion. Early experimental efforts are described, and analytical attempts to model the linear, and nonlinear regimes of these mixing layers are examined. These analytical efforts include models for both single-mode and multi-mode initial conditions, as well as multi-scale models to describe the evolution. Comparisons of these models and theories to experimental and simulation studies are then presented. Next, attention is paid to the issue of the influence of stabilizing mechanisms (e.g., viscosity, surface tension, and diffuse interface) on the evolution of these instabilities, as well as the limitations and successes of numerical methods. Efforts to study these instabilities and mixing layers using group-theoretic ideas, as well as more formal notions of turbulence cascade processes during the later stages of the induced mixing layers, are inspected. A key element of the review is the discussion of the late-time self-similar scaling for the RT and RM growth factors, α and θ. These parameters are influenced by the initial conditions and much of the observed variation can be explained by this. In some cases, these instabilities

A intera??o tutor-alunos em EAD: protagonistas de a??es de leitura e escrita

OpenAIRE

Soares, Inaldo Firmino

2010-01-01

Sob os alicerces da Lingu?stica Aplicada, que vem focalizando as atividades linguageiras a partir de diferentes enfoques te?ricos, este trabalho resulta de uma pesquisa sobre as a??es de linguagem nas intera??es realizadas por alunos e tutores de um curso de Especializa??o em Ensino a Dist?ncia, a partir da plataforma Moodle, e os reflexos dessas a??es no desenvolvimento e aprimoramento da linguagem verbal desses sujeitos. O tema foi abordado ? luz do Interacionismo Sociodis...

Sintomatologia da depress?o e representa??es sociais de ser idoso e depress?o

OpenAIRE

Oliveira, Marcos Francisco de

2011-01-01

Introdu??o: O envelhecimento, apesar de ser uma grande vit?ria, est? causando uma ampla preocupa??o para os governantes, devido ao aumento populacional e ao risco de adoecimento, capaz de afetar a qualidade de vida das pessoas idosas. Objetivos: Avaliar a sintomatologia da depress?o referida por idosos; conhecer as representa??es sociais sobre ser idoso e depress?o; e identificar aspectos psicossociais associados a ser idoso e depress?o. Metodologia: Estudo explorat?rio, realiz...

Avaliação Bioquímica do líquido cefalorraquidiano de cães normais e de cães jovens portadores de encefalite por cinomose

Directory of Open Access Journals (Sweden)

Mary Marcondes Feitosa

1997-04-01

Full Text Available O presente experimento teve como objetivos estabelecer padrões de referência para constituintes do líquido cefalorraquidiano, determinar os valores de cloretos, creatina fosfoquinase e aspartato aminotransferase no soro sangüíneo e dosagem de glicose plasmática, na tentativa de verificar se existe correlação entre essas variáveis no sangue e no liquor, de cães normais e de cães jovens portadores de encefalite por cinomose. Foram utilizados 40 animais, sendo 20 cães normais e 20 cães com cinomose. O exame bioquímico do liquor dos cães normais permitiu o estabelecimento de valores para concentração de glicose: 86,09 ± 17,76 mg/dl, níveis de cloretos: 117, 36 ± 21,35 mEq/L, níveis de creatina fosfoquinase; 3,77 ± 1,72 Ul/L e níveis de aspartato aminotransferase 7,43± 4,61 Ul/L. O exame bioquímico do liquor de cães com cinomose permitiu o estabelecimento de valores para concentração de glicose: 80,85 ± 14,82 mg/dl, níveis de cloretos: 118,67± 12,82 mEq/L, níveis de creatina fosfoquinase: 26,38 ± 29,27 Ul/L e níveis de aspartato aminotransferase; 65,70 ± 23,72 Ul/L. Os níveis de cloretos, creatina fosfoquinase e aspartato aminotransferase no soro, e glicose no plasma nos cães normais e nos cães com cinomose foram, respectivamente, 103,43 ± 16,00 e 103,43 ±11,99 mEq/L, 95,75 ± 22,83 e 272,50 ± 140,95 Ul/L, 23,77 ± 5,20 e 23,44 ± 4,81 Ul/L, 119,12 ± 21,46 e 106,12 ± 17,73 mg/dl. Verificou-se uma correlação positiva entre a concentração de glicose liquórica e plasmática nos animais normais e nos animais com cinomose, e entre os níveis de CPK liquórica e sérica nos animais com cinomose. Não foram constatadas diferenças estatisticamente significativas entre os dois grupos de animais com relação aos níveis de cloretos do liquor e do soro. As amostras do liquor dos cães com cinomose apresentaram valores mais elevados de CPK e AST do que as amostras dos cães normais.

Investigation of Kelvin-Helmholtz Instability in the boundary layer using Doppler lidar and radiosonde data

Science.gov (United States)

Das, Subrata Kumar; Das, Siddarth Shankar; Saha, Korak; Murali Krishna, U. V.; Dani, K. K.

2018-04-01

Characteristics of Kelvin Helmholtz Instability (KHI) using Doppler wind lidar observation have rarely been reported during the Indian summer monsoon season. In this paper, we present a case study of KHI near planetary boundary layer using Doppler wind lidar and radiosonde measurements at Mahabubnagar, a tropical Indian station. The data was collected during the Integrated Ground Observation Campaign (June-October 2011) under the Cloud Aerosol Interaction and Precipitation Enhancement EXperiment-2011. The continuous wind lidar observation during 10-16 August 2011 shows there is an increase in carrier-to-noise ratio values near planetary boundary layer from 03:00 to 11:00 LT on 13 August; reveals the formation of KHI. There is a strong power bursts pattern corresponding to high turbulence characteristics in the early half of the day. The KHI temporal evolution from initial to dissipating stage is observed with clear variation in the carrier-to-noise ratio values. The observed KHI billows are in the height between 600 and 1200 m and lasted for about 7.5 h. The vertical velocity from Doppler lidar measurement shows the presence of updrafts after breaking of KHI in the boundary layer. The presence of strong wind shear, high stability parameter, low Richardson number and high relative humidity during the enhanced carrier-to-noise ratio period indicates the ideal condition for the formation and persistence of this dynamic instability. A typical characteristic of trapped humidity above the KHI billows suggest the presence of strong inversion. A wavelet analysis of 3-dimensional wind components show dominant periodicity of 45-65 min and the periodicity in vertical wind is more prominent.

On the instabilities of supersonic mixing layers - A high-Mach-number asymptotic theory

Science.gov (United States)

Balsa, Thomas F.; Goldstein, M. E.

1990-01-01

The stability of a family of tanh mixing layers is studied at large Mach numbers using perturbation methods. It is found that the eigenfunction develops a multilayered structure, and the eigenvalue is obtained by solving a simplified version of the Rayleigh equation (with homogeneous boundary conditions) in one of these layers which lies in either of the external streams. This analysis leads to a simple hypersonic similarity law which explains how spatial and temporal phase speeds and growth rates scale with Mach number and temperature ratio. Comparisons are made with numerical results, and it is found that this similarity law provides a good qualitative guide for the behavior of the instability at high Mach numbers. In addition to this asymptotic theory, some fully numerical results are also presented (with no limitation on the Mach number) in order to explain the origin of the hypersonic modes (through mode splitting) and to discuss the role of oblique modes over a very wide range of Mach number and temperature ratio.

Long-term preclinical magnetic resonance imaging alterations in sporadic Creutzfeldt-Jakob disease.

Science.gov (United States)

Zanusso, Gianluigi; Camporese, Giulia; Ferrari, Sergio; Santelli, Luca; Bongianni, Matilde; Fiorini, Michele; Monaco, Salvatore; Manara, Renzo; Cagnin, Annachiara

2016-10-01

An asymptomatic 74-year-old woman, on follow-up for a carotid body tumor, showed magnetic resonance imaging (MRI) focal restricted diffusion confined to the left temporal and occipital cortices. Thirteen months later, diffusion-weighted images revealed a bilateral cortical ribbon sign involving all lobes. After 1 month, the patient developed gait instability and cognitive decline rapidly evolving to severe dementia and death within 3 months. Prion protein gene sequence, molecular, and neuropathological studies confirmed the diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) MM1 subtype. Here we show the kinetics of MRI changes and prion spreading in preclinical sCJD MM1. Ann Neurol 2016;80:629-632. © 2016 American Neurological Association.

RRAF-V600E is not involved in the colorectal tumorigenesis of HNPCC in patients with functional MLH1 and MSH2 genes

NARCIS (Netherlands)

Domingo, E; Niessen, RC; Oliveira, C; Alhopuro, P; Moutinho, C; Espin, E; Armengol, M; Sijmons, RH; Kleibeuker, JH; Seruca, R; Aaltonen, LA; Imai, K; Yamamoto, H; Schwartz, S; Hofstra, RMW

2005-01-01

Recently, it was shown that the oncogenic activation of BRAF, a member of the RAS/RAF family of kinases, by the V600E mutation is characteristic for sporadic colon tumors with microsatellite instability. Further, it was shown to associate with the silencing of the mismatch repair (MMR) gene MLH1 by

Magnetohydrodynamic Kelvin-Helmholtz instabilities in astrophysics. 4. Single shear layer in MHD flows

Energy Technology Data Exchange (ETDEWEB)

Ferrari, A [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale); Trussoni, E [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Max-Planck-Institut fuer Physik und Astrophysik, Garching (Germany, F.R.). Inst. fuer Extraterrestrische Physik)

1983-11-01

In this further paper on the physics of Kelvin-Helmholtz instabilities the case in which the fluids in relative motion are magnetized and separated by a shear layer is investigated. The present study points out, with respect to previous treatments, that different velocity profiles affect perturbations of short wavelength (as compared to the scale of the shear). Another new result is in the destabilizing effect, even in the subsonic regime, of the magnetic field on modes neutrally stable in the vortex sheet approximation. Such a behaviour is analogous to that found in the fluid case for Mach numbers >approx. = to 2. Possible astrophysical implications are also discussed.

Electrondynamics of the auroral E region

International Nuclear Information System (INIS)

Kirkwood, Sheila.

1990-10-01

This study concentrates on the signatures of the interaction process seen closest to the Earth - i.e. in the region where the visible aurora is produced. A number of experimental investigations are presented which look at details of the dynamics and electrodynamics of auroral ionisation features in the ionospheric E region. The studies are based primarily on measurement with the EISCAT UHF incoherent scatter radar which is located in northern Scandinavia. Initial calibration of the radar, and some measurements of the properties of the background atmosphere are described first. These are a necessary basis for the detailed studies which follow, which are of two aspects of auroral electrodynamics - substorms and aurorally-associated sporadic E layers. For the substorm studies, all-sky camera observations of the aurora over Scandinavia and ultra-violet images from the Viking satellite are used to identify the auroral forms corresponding to EISCAT measurements. This allows the determination of representative conductivities for the different auroral features which are characteristic of the substorm development. These conductivities are an important input for modelling studies of the electric current systems and have not previously been measured directly. Particle measurements from the Viking satellite are used together with EISCAT to determine the origin of the particles precipitated into the ionosphere during the energy-storage phase prior to the substorm. The sporadic E layers studies address the question of how ion layers and associated neutral sodium layers can be produced by some process which is common in association with auroral activity. Two candidates are considered - gravity waves and electric fields. (author)

Progressive deformation of ultramafic rocks accompanied with deflection of layered structure and mylonitization culminating into a pseudotachylyte-bearing seismogenic fault - a field evidence of plastic instability

Science.gov (United States)

Ueda, T.; Obata, M.

2011-12-01

Plastic instability leading to rupture nucleation and propagetion (e.g. Hobbs et al.1986, Kelemen and Hirth, 2007) is an attractive hypothesis for deep earthquakes but lacked clear field evidences. 1D across-fault shear localization observed in some places (e.g. Jin et al.1998) is not clear if the deformation is directly related with seismicity. We present a clear field evidence of plastic instability as guided by pyroxenite/peridotite layering deflection structure (hereafter called LD structure, see figure) accompanied with mylonitization in spinel(Sp)-peridotite facies (P>~1GPa) in Balmuccia peridotite, Ivrea-Verbano Zone, Italy. The studied area contains abundant PST-bearing faults and N-S trending primary pyroxenite layers. Many faults in the area cut pyroxenite layers, but LD structure is found only in one place presented here. Many PSTs in the area have been (re)crystallized in Sp-peridotite facies, and have typically ultramylonitic texture (Ueda et al., 2008) with some injection veins. The fault with LD structure is situated in a fault system, which has two dominant attitudes with regional N-S extension. The shear strain of LD structure measured on outcrop surface is ~2.0. Near the fault, elongated Opx porphyroclasts (ellipses in figure) oblique to local layering are visible in peridotite. The dominant deformation textures are dynamic recrystallization in peridotite and kinking or undulatory extinction in pyroxenite. The mineral assemblages of the mylonite neoblast in the peridotite and the pyroxenite are Ol+Opx+Cpx+Sp+hornblende(Hbl), Cpx+Opx+Sp, respectively. Hbl typically occur only in neoblast. In the vicinity (several hundreds of micron) of the fault, dolomite(Dol) also occur in equilibrium with the assemblage above. The recrystallized grain sizes are 20-50 microns in peridotite and 10-30 microns in pyroxenite. The rarity of LD structure is consistent with general conception that deformation processes which lead to dynamic rupture initiation ought to be

Aerodynamic heating in transitional hypersonic boundary layers: Role of second-mode instability

Science.gov (United States)

Zhu, Yiding; Chen, Xi; Wu, Jiezhi; Chen, Shiyi; Lee, Cunbiao; Gad-el-Hak, Mohamed

2018-01-01

The evolution of second-mode instabilities in hypersonic boundary layers and its effects on aerodynamic heating are investigated. Experiments are conducted in a Mach 6 wind tunnel using fast-response pressure sensors, fluorescent temperature-sensitive paint, and particle image velocimetry. Calculations based on parabolic stability equations and direct numerical simulations are also performed. It is found that second-mode waves, accompanied by high-frequency alternating fluid compression and expansion, produce intense aerodynamic heating in a small region that rapidly heats the fluid passing through it. As the second-mode waves decay downstream, the dilatation-induced aerodynamic heating decreases while its shear-induced counterpart keeps growing. The latter brings about a second growth of the surface temperature when transition is completed.

Chromosomal instability in the progeny of irradiated parents

International Nuclear Information System (INIS)

Voro btsova, I.E.; Vorobyova, M.V.; Bogomazova, A.N.

1997-01-01

Genomic instability have been demonstrated in irradiated cells as the increased frequency of sporadic chromosome aberrations persisted over multiple generations of cell divisions. We found that chromosomal instability characterized as well the somatic cells of irradiated parents progeny. It means that radiation induced genomic instability can be transmitted via germ line cells. As a measure of instability the sensitivity of chromosomes to radiation was estimated. In animal experiments the irradiation of mature germ cells of male rats (dose - 4.5 Gy of X-rays) increase the frequency of chromosome aberrations induced by challenging irradiation in regenerating hepatocytes, in bone marrow cells and in fetal fibroblasts in the progeny of irradiated male rats. The chromosomal sensitivity of cultivated lymphocytes to in vitro irradiation (1.5 Gy of γ(rays 137 Cs) is increased in the children born parents undergone antitumor radiotherapy or worked as 'liquidators' of Chernobyl accident consequences before conception in comparison to the children of unexposed parents. The cytogenetic radiosensitivity of lymphocytes to irradiation in vitro is also increased in children evacuated from contaminated by radionuclides areas ('positive' control group). The increased spontaneous frequency of chromatid-type acentric was found in all group of children with irradiation history. The instability of genome of irradiated parents progeny seems could be the mechanism of these health effects. (authors)

Midlatitude ionospheric F2-layer response to eruptive solar events-caused geomagnetic disturbances over Hungary during the maximum of the solar cycle 24: A case study

Science.gov (United States)

Berényi, K. A.; Barta, V.; Kis, Á.

2018-03-01

In our study we analyze and compare the response and behavior of the ionospheric F2 and of the sporadic E-layer during three strong (i.e., Dst art digital ionosonde of the Széchenyi István Geophysical Observatory located at midlatitude, Nagycenk, Hungary (IAGA code: NCK, geomagnetic latitude: 46.17° geomagnetic longitude: 98.85°). The local time of the sudden commencement (SC) was used to characterize the type of the ionospheric storm (after Mendillo and Narvaez, 2010). This way two regular positive phase (RPP) ionospheric storms and one no-positive phase (NPP) storm have been analyzed. In all three cases a significant increase in electron density of the foF2 layer can be observed at dawn/early morning (around 6:00 UT, 07:00 LT). Also we can observe the fade-out of the ionospheric layers at night during the geomagnetically disturbed time periods. Our results suggest that the fade-out effect is not connected to the occurrence of the sporadic E-layers.

Earth's core formation due to the Rayleigh-Taylor instability

International Nuclear Information System (INIS)

Ida, S.; Nakagawa, Y.; Nakazawa, K.

1987-01-01

A protoearth accretion stage configuration consisting of an undifferentiated solid core, an intermediate metal-melt layer, and an outer silicate-melt layer, is presently taken as the initial state in an investigation of Rayleigh-Taylor instability-induced core formation. The Ida et al. (to be published) quantitative results on the instability in a self-gravitating fluid sphere are used. The instability is found to occur through the translational mode on a time-scale of about 10 hr, in the case where the metal-melt layer is greater than about 1 km; this implies that the earth's core formed due to the undifferentiated solid core's translation upon the outer layer's melting. Differentiation would then have occurred in the late accretion stage. 17 references

Copy number of the Adenomatous Polyposis Coli gene is not always neutral in sporadic colorectal cancers with loss of heterozygosity for the gene.

Science.gov (United States)

Zauber, Peter; Marotta, Stephen; Sabbath-Solitare, Marlene

2016-03-12

Changes in the number of alleles of a chromosome may have an impact upon gene expression. Loss of heterozygosity (LOH) indicates that one allele of a gene has been lost, and knowing the exact copy number of the gene would indicate whether duplication of the remaining allele has occurred. We were interested to determine the copy number of the Adenomatous Polyposis Coli (APC) gene in sporadic colorectal cancers with LOH. We selected 38 carcinomas with LOH for the APC gene region of chromosome 5, as determined by amplification of the CA repeat region within the D5S346 loci. The copy number status of APC was ascertained using the SALSA® MLPA® P043-B1 APC Kit. LOH for the DCC gene, KRAS gene mutation, and microsatellite instability were also evaluated for each tumor, utilizing standard polymerase chain reaction methods. No tumor demonstrated microsatellite instability. LOH of the DCC gene was also present in 33 of 36 (91.7%) informative tumors. A KRAS gene mutation was present in 16 of the 38 (42.1%) tumors. Twenty-four (63.2%) of the tumors were copy number neutral, 10 (26.3%) tumors demonstrated major loss, while two (5.3%) showed partial loss. Two tumors (5.3%) had copy number gain. Results of APC and DCC LOH, KRAS and microsatellite instability indicate our colorectal cancer cases were typical of sporadic cancers following the 'chromosomal instability' pathway. The majority of our colorectal carcinomas with LOH for APC gene are copy number neutral. However, one-third of our cases showed copy number loss, suggesting that duplication of the remaining allele is not required for the development of a colorectal carcinoma.

Transitions to spatiotemporal chaos and turbulence of flute instabilities in a low-β magnetized plasma

International Nuclear Information System (INIS)

Brochard, F.; Gravier, E.; Bonhomme, G.

2006-01-01

The spatiotemporal transition scenario of flute instabilities from a regular to a turbulent state is experimentally investigated in the low-β plasma column of a thermionic discharge. The same transition scenario, i.e., the Ruelle-Takens route to turbulence, is found for both the Kelvin-Helmholtz and the Rayleigh-Taylor instabilities. It is demonstrated that the transition can be more or less smooth, according to the discharge mode. In both cases, a strong radial dependence is observed, which is linked to the velocity shear layer in the case of the Kelvin-Helmholtz instability

Modeling and simulation of melt-layer erosion during a plasma disruption

International Nuclear Information System (INIS)

Hassanein, A.; Belan, V.; Konkashbaev, I.; Nikandrov, L.; Safronov, V.; Zhitlukhin, A.; Litunovsky, V.

1997-01-01

Metallic plasma-facing components (PFCs) e.g. beryllium and tungsten, will be subjected to severe melting during plasma instabilities such as disruptions, edge-localized modes and high power excursions. Because of the greater thickness of the resulting melt layers relative to that of the surface vaporization, the potential loss of the developing melt-layer can significantly shorten PFC lifetime, severely contaminate the plasma and potentially prevent successful operation of the tokamak reactor. Mechanisms responsible for melt-layer loss during plasma instabilities are being modeled and evaluated. Of particular importance are hydrodynamic instabilities developed in the liquid layer due to various forces such as those from magnetic fields, plasma impact momentum, vapor recoil and surface tension. Another mechanism found to contribute to melt-layer splashing loss is volume bubble boiling, which can result from overheating of the liquid layer. To benchmark these models, several new experiments were designed and performed in different laboratory devices for this work; the SPLASH codes) are generally in good agreement with the experimental results. The effect of in-reactor disruption conditions, which do not exist in simulation experiments, on melt-layer erosion is discussed. (orig.)

E × B electron drift instability in Hall thrusters: Particle-in-cell simulations vs. theory

Science.gov (United States)

Boeuf, J. P.; Garrigues, L.

2018-06-01

The E × B Electron Drift Instability (E × B EDI), also called Electron Cyclotron Drift Instability, has been observed in recent particle simulations of Hall thrusters and is a possible candidate to explain anomalous electron transport across the magnetic field in these devices. This instability is characterized by the development of an azimuthal wave with wavelength in the mm range and velocity on the order of the ion acoustic velocity, which enhances electron transport across the magnetic field. In this paper, we study the development and convection of the E × B EDI in the acceleration and near plume regions of a Hall thruster using a simplified 2D axial-azimuthal Particle-In-Cell simulation. The simulation is collisionless and the ionization profile is not-self-consistent but rather is given as an input parameter of the model. The aim is to study the development and properties of the instability for different values of the ionization rate (i.e., of the total ion production rate or current) and to compare the results with the theory. An important result is that the wavelength of the simulated azimuthal wave scales as the electron Debye length and that its frequency is on the order of the ion plasma frequency. This is consistent with the theory predicting destruction of electron cyclotron resonance of the E × B EDI in the non-linear regime resulting in the transition to an ion acoustic instability. The simulations also show that for plasma densities smaller than under nominal conditions of Hall thrusters the field fluctuations induced by the E × B EDI are no longer sufficient to significantly enhance electron transport across the magnetic field, and transit time instabilities develop in the axial direction. The conditions and results of the simulations are described in detail in this paper and they can serve as benchmarks for comparisons between different simulation codes. Such benchmarks would be very useful to study the role of numerical noise (numerical

New developments on the e-p instability at the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Macek, R.J.; Browman, A.; Fitzgerald, D.H.; McCrady, R.; Plum, M.; Spickermann, T.

2001-01-01

New results are reported from an R and D program aimed greater understanding and control of the e-p instability observed at the Los Alamos Proton Storage Rings (PSR). Numerous characteristics of the electron cloud for both stable and unstable beams in PSR were measured with ANL electron analyzers and various collection plates. Strong suppression of the electron flux density by TiN coating of the vacuum chamber in a straight section was also observed, thereby confirming an essential role for secondary emission at the walls. Landau Damping by a variety of techniques including higher rf voltage, transverse coupling, multipole fields in the lattice, and the use of inductive inserts has been effective in controlling the e-p instability. By these methods, the instability threshold has been raised significantly to 9.7 micro Coulombs per stored pulse. (author)

Streaming gravity mode instability

International Nuclear Information System (INIS)

Wang Shui.

1989-05-01

In this paper, we study the stability of a current sheet with a sheared flow in a gravitational field which is perpendicular to the magnetic field and plasma flow. This mixing mode caused by a combined role of the sheared flow and gravity is named the streaming gravity mode instability. The conditions of this mode instability are discussed for an ideal four-layer model in the incompressible limit. (author). 5 refs

Effect of the boundary layer thickness on the hydrodynamic instabilities of coaxial atomization under harmonic flow rate and swirl ratio fluctuations

Science.gov (United States)

Jorajuria, Corentin; Machicoane, Nathanael; Osuna, Rodrigo; Aliseda, Alberto

2017-11-01

Break-up of a liquid jet by a high speed coaxial gas jet is a frequently-used configuration to generate a high quality spray. Despite its extended use in engineering and natural processes, the instabilities that control the liquid droplet size and their spatio-temporal distribution in the spray are not completely understood. We present an experimental measurements of the near field in a canonical coaxial gas-liquid atomizer. The liquid Reynolds number is constant at 103, while the gas jet Reynolds number is varied from 104-106. The liquid injection rate and the swirl ratio are harmonically modulated to understand the effect of unsteadiness on the interfacial instability that triggers primary break-up. The gas velocity is measured using a combination of hot-wire anemometry and 3D PIV, resolving the gas boundary layer and the three-dimensionality of the flow, particularly in the cases with swirl. The development of the hydrodynamic instabilities on the liquid-gas interface is quantified using high speed visualizations at the exit of the nozzle and related to the frequency and growth rates predicted by stability analysis of this boundary layer flow. The resulting droplet size distribution is measured at the end of the break-up process via Particle Phase Doppler Anemometry and compared to stability analysis predictions statistics.

Solution-processed high-LUMO-level polymers in n-type organic field-effect transistors: a comparative study as a semiconducting layer, dielectric layer, or charge injection layer

International Nuclear Information System (INIS)

Liu, Chuan; Xu, Yong; Liu, Xuying; Minari, Takeo; Sirringhaus, Henning; Noh, Yong-Young

2015-01-01

In solution-processed organic field-effect transistors (OFETs), the polymers with high level of lowest unoccupied molecular orbitals (LUMOs, > −3.5 eV) are especially susceptible to electron-trapping that causes low electron mobility and strong instability in successive operation. However, the role of high-LUMO-level polymers could be different depending on their locations relative to the semiconductor/insulator interface, or could even possibly benefit the device in some cases. We constructed unconventional polymer heterojunction n-type OFETs to control the location of the same polymer with a high LUMO level, to be in, under, or above the accumulation channel. We found that although the devices with the polymer in the channel suffer from dramatic instability, the same polymer causes much less instability when it acts as a dielectric modification layer or charge injection layer. Especially, it may even improve the device performance in the latter case. This result helps to improve our understanding of the electron-trapping and explore the value of these polymers in OFETs. (invited article)

INOVAÇÕES EM ALIMENTAÇÃO: AS PERCEPÇÕES DOS CONSUMIDORES SOBRE PRODUTOS ENRIQUECIDOS E TRANSGÊNICOS RESUMO

Directory of Open Access Journals (Sweden)

Thelma Lucchese Cheung

2015-12-01

Full Text Available Logo do cabeçalho da página AJUDA DO SISTEMA USUÁRIO Logado como: elvis MEUS PERIÓDICOS PERFIL SAIR DO SISTEMA CONTEÚDO DA REVISTA Pesquisa Escopo da Busca Pesquisar Procurar POR EDIÇÃO POR AUTOR POR TÍTULO OUTRAS REVISTAS TAMANHO DE FONTE MAKE FONT SIZE SMALLERMAKE FONT SIZE DEFAULTMAKE FONT SIZE LARGER INFORMAÇÕES PARA LEITORES PARA AUTORES PARA BIBLIOTECÁRIOS OPEN JOURNAL SYSTEMS CAPA SOBRE PÁGINA DO USUÁRIO PESQUISA ATUAL ANTERIORES NOTÍCIAS MESTRADO EM DESENVOLVIMENTO TERRITORIAL E SISTEMAS AGROINDUSTRIAIS BOAS PRÁTICAS DA PUBLICAÇÃO - ANPAD AVALIADORES 2012 AVALIADORES 2013 AVALIADORES 2014 AVALIADORES 2015 CAPA > V. 7, N. 4 (2015 >\tCHEUNG INOVAÇÕES EM ALIMENTAÇÃO: AS PERCEPÇÕES DOS CONSUMIDORES SOBRE PRODUTOS ENRIQUECIDOS E TRANSGÊNICOS RESUMO Thelma Lucchese Cheung, Claudia Macedo, Thiago Neves, Wellington da Silva Rodrigues Resumo Pretendeu-se neste artigo apresentar as percepções de um grupo de consumidores brasileiros em relação às inovações no setor de alimentos. Questionados sobre os alimentos transformados, geneticamente modificados e transgênicos que estão no mercado as opiniões dos indivíduos, cheias de valores e atitudes, permitiram a este estudo observar suas representações dessas inovações. O estudo que deu origem a este artigo é exploratório e qualitativo. Questões abertas de um questionário foram utilizadas para compreender as percepções da amostra sobre as inovações estudadas. As declarações de indivíduos adultos, de 20 a 40 anos, de ambos os gêneros e com alto nível de escolaridade e habitantes de diferentes estados brasileiros revelaram reações positivas quanto aos produtos modificados e transgênicos, associando-os com avanços da ciência e benefícios das descobertas científicas como alternativas de consumo conveniente e mais saudável.

Direct observation of nonequilibrium electroosmotic instability

NARCIS (Netherlands)

Rubinstein, S.M.; Manukyan, G.; Staicu, A.D.; Rubinstein, I.; Zaltzman, B.; Lammertink, Rob G.H.; Mugele, Friedrich Gunther; Wessling, Matthias

2008-01-01

We present a visualization of the predicted instability in ionic conduction from a binary electrolyte into a charge selective solid. This instability develops when a voltage greater than critical is applied to a thin layer of copper sulfate flanked by a copper anode and a cation selective membrane.

Numerical study of jets secondary instabilities

International Nuclear Information System (INIS)

Brancher, Pierre

1996-01-01

The work presented in this dissertation is a contribution to the study of the transition to turbulence in open shear flows. Results from direct numerical simulations are interpreted within the framework of hydrodynamic stability theory. The first chapter is an introduction to the primary and secondary instabilities observed in jets and mixing layers. The numerical method used in the present study is detailed in the second chapter. The dynamics of homogeneous circular jets subjected to stream wise and azimuthal perturbations are investigated in the third chapter. A complete scenario describing the evolution of the jet is proposed with emphasis on the dynamics of vorticity within the flow. In the fourth chapter a parametric study reveals a three-dimensional secondary instability mainly controlled in the linear regime by the Strouhal number of the primary instability. In the nonlinear regime the dynamics of the azimuthal harmonies are described by means of model equations and are linked to the formation of stream wise vortices in the braid. The fifth chapter is dedicated to the convective or absolute nature of the secondary instabilities in plane shear layers. It is shown that there are flow configurations for which the two-dimensional secondary instability (pairing) is absolute even though the primary instability (Kelvin-Helmholtz) is convective. Some preliminary results concerning the three-dimensional secondary instabilities arc presented at the end of this chapter. The last chapter summarizes the main results and examines possible extensions of this work. (author) [fr

Cromatografia em camada delgada para o diagnóstico da intoxicação por aldicarb ("chumbinho" em cães e gatos Thin-layer chromatography for aldicarb poisoning diagnosis in dogs and cats

Directory of Open Access Journals (Sweden)

F.G. Xavier

2007-10-01

Full Text Available Avaliou-se a cromatografia em camada delgada (CCD como método de diagnóstico toxicológico para os casos de intoxicação por aldicarb em cães e gatos, utilizando-se 50 amostras de conteúdo gástrico obtidas durante a necropsia e 50 amostras de alimentos utilizados como iscas para intoxicar criminalmente os animais. Todas as amostras resultaram positivas para o aldicarb, mostrando ser a CCD uma técnica qualitativa eficiente, rápida e de baixo custo, com uso potencial na toxicologia veterinária forense.The present study concerns about the identification of aldicarb residues using thin-layer chromatography (TLC in 50 samples of gastric content obtained from the necropsy of dogs and cats and 50 samples of foods suspected of being used as baits. All samples resulted positive for aldicarb showing that the TLC is an efficient, fast and not expensive qualitative method for the detection of aldicarb, being useful for this purpose in the forensic veterinary toxicology.

Instabilities in dynamic anti-plane sliding of an elastic layer on a dissimilar elastic half-space

Science.gov (United States)

Kunnath, R.

2012-12-01

The stability of dynamic anti-plane sliding at an interface between an elastic layer and an elastic half-space with dissimilar elastic properties is studied. Friction at the interface is assumed to follow a rate- and state-dependent law, with a positive instantaneous dependence on slip velocity and a rate weakening behavior in the steady state. The perturbations are of the form exp(ikx+pt), where k is the wavenumber, x is the coordinate along the interface, p is the time response to the perturbation and t is time. The results of the stability analysis are shown in Figs. 1 and 2 with the velocity weakening parameter b/a=5, shear wave speed ratio cs'/cs=1.2, shear modulus ratio μ'/μ=1.2 and non-dimensional layer thickness H=100. The normalized instability growth rate and normalized phase velocity are plotted as a function of wavenumber. Fig.1 is for a non-dimensional unperturbed slip velocity ɛ=5 (rapid sliding) while Fig. 2 is for ɛ=0.05 (slow sliding). The results show the destabilization of interfacial waves. For slow sliding, destabilization of interfacial waves is still seen, indicating that the quasi-static approximation to slow sliding is not valid. This is in agreement with the result of Ranjith (Int. J. Solids and Struct., 2009, 46, 3086-3092) who predicted an instability of long-wavelength Love waves in slow sliding.

Type I intermittency related to the spatiotemporal dynamics of double layers and ion-acoustic instabilities in plasma

International Nuclear Information System (INIS)

Chiriac, S.; Dimitriu, D. G.; Sanduloviciu, M.

2007-01-01

Anodic double layer instabilities occur in low-temperature diffusion filament-type discharge plasma by applying a certain positive bias with respect to the plasma potential to an additional electrode. Periodic nonlinear regimes, characterized by proper dynamics of double layers, are sustained if excitation and ionization rates in front of the electrode reach the value for which current limitation effects appear in the static current-voltage characteristic. It was experimentally shown that under specific experimental conditions these ordered spatiotemporal phenomena can evolve into chaotic states by type I intermittency. This transition was verified by the evolution of time series, fast Fourier transform amplitude plots, three-dimensional reconstructed state spaces, power laws, and flickering phenomena spectrum, as well as by the return map and tangent bifurcation

Formation en TIC destinée aux personnes handicapées en ...

International Development Research Centre (IDRC) Digital Library (Canada)

Formation en TIC destinée aux personnes handicapées en Amérique latine. En Amérique latine et dans les Caraïbes, les personnes handicapées représentent environ 10 % de la population. La population de cette région affiche des taux de pauvreté et de chômage élevés; assurer des moyens de subsistance décents aux ...

Stress, satisfação e expectativas parentais em mães e pais de crianças em idade escolar

OpenAIRE

Vieira, Simone Frazão

2015-01-01

Tese de mestrado, Psicologia (Secção de Psicologia Clínica e da Saúde, Núcleo de Psicologia Clínica Dinâmica), Universidade de Lisboa, Faculdade de Psicologia, 2015 O presente estudo, com mães e pais de crianças em idade escolar, tem os seguintes objetivos: 1) analisar se as mães e os pais se distinguem no stress parental e na satisfação e expectativas parentais; 2) explorar a relação entre o stress parental e a satisfação e expectativas parentais; 3) averiguar a relação das referidas dime...

The equatorial E-region and its plasma instabilities: a tutorial

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D. T. Farley

2009-04-01

Full Text Available In this short tutorial we first briefly review the basic physics of the E-region of the equatorial ionosphere, with emphasis on the strong electrojet current system that drives plasma instabilities and generates strong plasma waves that are easily detected by radars and rocket probes. We then discuss the instabilities themselves, both the theory and some examples of the observational data. These instabilities have now been studied for about half a century (!, beginning with the IGY, particularly at the Jicamarca Radio Observatory in Peru. The linear fluid theory of the important processes is now well understood, but there are still questions about some kinetic effects, not to mention the considerable amount of work to be done before we have a full quantitative understanding of the limiting nonlinear processes that determine the details of what we actually observe. As our observational techniques, especially the radar techniques, improve, we find some answers, but also more and more questions. One difficulty with studying natural phenomena, such as these instabilities, is that we cannot perform active cause-and-effect experiments; we are limited to the inputs and responses that nature provides. The one hope here is the steadily growing capability of numerical plasma simulations. If we can accurately simulate the relevant plasma physics, we can control the inputs and measure the responses in great detail. Unfortunately, the problem is inherently three-dimensional, and we still need somewhat more computer power than is currently available, although we have come a long way.

Circumferential buckling instability of a growing cylindrical tube

KAUST Repository

Moulton, D.E.

2011-03-01

A cylindrical elastic tube under uniform radial external pressure will buckle circumferentially to a non-circular cross-section at a critical pressure. The buckling represents an instability of the inner or outer edge of the tube. This is a common phenomenon in biological tissues, where it is referred to as mucosal folding. Here, we investigate this buckling instability in a growing elastic tube. A change in thickness due to growth can have a dramatic impact on circumferential buckling, both in the critical pressure and the buckling pattern. We consider both single- and bi-layer tubes and multiple boundary conditions. We highlight the competition between geometric effects, i.e. the change in tube dimensions, and mechanical effects, i.e. the effect of residual stress, due to differential growth. This competition can lead to non-intuitive results, such as a tube growing to be thinner and yet buckle at a higher pressure. © 2011 Elsevier Ltd. All rights reserved.

EFEITO DO EXERCÍCIO FÍSICO SOBRE A SAÚDE E SOBRECARGA DE MÃES DE CRIANÇAS E ADOLESCENTES COM PARALISIA CEREBRAL

OpenAIRE

Batista,Moisés Rosa; Batista,Jaqueline Pontes; Furtado,Jussara Caetano; Rocha Junior,Luiz Duarte de Ulhôa; Tavares,Eduardo Henrique; Araújo,Hygor Nunes; Pinto,Rogério de Melo Costa; Morales,Nívea de Macedo Oliveira

2016-01-01

RESUMO Introdução: A paralisia cerebral (PC) é considerada a incapacidade física mais comum na infância. Essa doença afeta profundamente a saúde e o bem-estar dos indivíduos acometidos e também pode influenciar múltiplos aspectos da vida de seus cuidadores, especialmente as mães. Objetivo: Avaliar o efeito de um programa de exercício resistido sobre a qualidade de vida relacionada à saúde (QVRS) de mães de crianças e adolescentes com PC. Método: Vinte e duas mães sedentárias cuidadoras de ...

Boundary Layer Instabilities Generated by Freestream Laser Perturbations

Science.gov (United States)

Chou, Amanda; Schneider, Steven P.

2015-01-01

A controlled, laser-generated, freestream perturbation was created in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). The freestream perturbation convected downstream in the Mach-6 wind tunnel to interact with a flared cone model. The geometry of the flared cone is a body of revolution bounded by a circular arc with a 3-meter radius. Fourteen PCB 132A31 pressure transducers were used to measure a wave packet generated in the cone boundary layer by the freestream perturbation. This wave packet grew large and became nonlinear before experiencing natural transition in quiet flow. Breakdown of this wave packet occurred when the amplitude of the pressure fluctuations was approximately 10% of the surface pressure for a nominally sharp nosetip. The initial amplitude of the second mode instability on the blunt flared cone is estimated to be on the order of 10 -6 times the freestream static pressure. The freestream laser-generated perturbation was positioned upstream of the model in three different configurations: on the centerline, offset from the centerline by 1.5 mm, and offset from the centerline by 3.0 mm. When the perturbation was offset from the centerline of a blunt flared cone, a larger wave packet was generated on the side toward which the perturbation was offset. The offset perturbation did not show as much of an effect on the wave packet on a sharp flared cone as it did on a blunt flared cone.

Tumores de cães e gatos diagnosticados no semiárido da Paraíba

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Rachel L.F.S. Andrade

2012-10-01

Full Text Available Objetivou-se com este estudo determinar a frequência dos tumores diagnosticados em cães e gatos no Hospital Veterinário da Universidade Federal de Campina Grande (UFCG, Patos, Paraíba, Brasil, entre os anos de 2003 a 2010. Foram revisados todos os protocolos de necropsias e biópsias realizadas no Laboratório de Patologia Animal da referida instituição, e computados os dados referentes aos animais afetados. Os tumores mais frequentes em cães ocorreram na pele e anexos (46,7%, seguido da glândula mamária (24%, sistema genital (10,3% e sistema digestório (6,5%. Os tumores malignos foram mais frequentes que os benignos (p=0,001, representando 78% e 22% respectivamente. Em gatos, as frequências de neoplasmas de pele e glândula mamária foram idênticas (39,4% cada, seguidas das do sistema digestório (8,5% e fígado (5,7%. Os tumores malignos representaram 95,8% dos tumores diagnosticados nesta espécie. Cães sem raça definida tiveram menor frequência (16% de tumores do que animais de diferentes raças (37,2% (p<0,0001. A ampla variedade de neoplasmas que acomete cães e gatos dificulta ao veterinário o diagnóstico clínico e o tratamento das mesmas, sendo recomendável o diagnóstico histológico sistemático de todas as lesões suspeitas de serem neoplasias. Além disso, são necessários estudos que determinem os fatores epidemiológicos envolvidos no desenvolvimento dos tumores que acometem os cães e gatos, nas diferentes regiões, a fim de serem tomadas medidas para diminuir sua ocorrência e letalidade.

Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer

Energy Technology Data Exchange (ETDEWEB)

Mardani, Shabnam, E-mail: shabnam.mardani@angstrom.uu.se; Vallin, Örjan; Wätjen, Jörn Timo; Norström, Hans; Olsson, Jörgen; Zhang, Shi-Li, E-mail: shili.zhang@angstrom.uu.se [Solid State Electronics, The Ångström Laboratory, Uppsala University, P.O. Box 534, SE-75121 (Sweden)

2014-08-18

Wide-bandgap (WBG) semiconductor technologies are maturing and may provide increased device performance in many fields of applications, such as high-temperature electronics. However, there are still issues regarding the stability and reliability of WBG devices. Of particular importance is the high-temperature stability of interconnects for electronic systems based on WBG-semiconductors. For metallization without proper encapsulation, morphological degradation can occur at elevated temperatures. Sandwiching Ag films between Ta and/or TaN layers in this study is found to be electrically and morphologically stabilize the Ag metallization up to 800 °C, compared to 600 °C for uncapped films. However, the barrier layer plays a key role and TaN is found to be superior to Ta, resulting in the best achieved stability, whereas the difference between Ta and TaN caps is negligible. The β-to-α phase transition in the underlying Ta barrier layer is identified as the major cause responsible for the morphological instability observed above 600 °C. It is shown that this phase transition can be avoided using a stacked Ta/TaN barrier.

Mix and hydrodynamic instabilities on NIF

Science.gov (United States)

Smalyuk, V. A.; Robey, H. F.; Casey, D. T.; Clark, D. S.; Döppner, T.; Haan, S. W.; Hammel, B. A.; MacPhee, A. G.; Martinez, D.; Milovich, J. L.; Peterson, J. L.; Pickworth, L.; Pino, J. E.; Raman, K.; Tipton, R.; Weber, C. R.; Baker, K. L.; Bachmann, B.; Berzak Hopkins, L. F.; Bond, E.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Dixit, S. N.; Edwards, M. J.; Felker, S.; Field, J. E.; Fittinghoff, D. N.; Gharibyan, N.; Grim, G. P.; Hamza, A. V.; Hatarik, R.; Hohenberger, M.; Hsing, W. W.; Hurricane, O. A.; Jancaitis, K. S.; Jones, O. S.; Khan, S.; Kroll, J. J.; Lafortune, K. N.; Landen, O. L.; Ma, T.; MacGowan, B. J.; Masse, L.; Moore, A. S.; Nagel, S. R.; Nikroo, A.; Pak, A.; Patel, P. K.; Remington, B. A.; Sayre, D. B.; Spears, B. K.; Stadermann, M.; Tommasini, R.; Widmayer, C. C.; Yeamans, C. B.; Crippen, J.; Farrell, M.; Giraldez, E.; Rice, N.; Wilde, C. H.; Volegov, P. L.; Gatu Johnson, M.

2017-06-01

Several new platforms have been developed to experimentally measure hydrodynamic instabilities in all phases of indirect-drive, inertial confinement fusion implosions on National Ignition Facility. At the ablation front, instability growth of pre-imposed modulations was measured with a face-on, x-ray radiography platform in the linear regime using the Hydrodynamic Growth Radiography (HGR) platform. Modulation growth of "native roughness" modulations and engineering features (fill tubes and capsule support membranes) were measured in conditions relevant to layered DT implosions. A new experimental platform was developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, several experimental platforms were developed to measure both low-mode asymmetries and high-mode perturbations near peak compression with x-ray and nuclear techniques. In one innovative technique, the self-emission from the hot spot was enhanced with argon dopant to "self-backlight" the shell in-flight. To stabilize instability growth, new "adiabat-shaping" techniques were developed using the HGR platform and applied in layered DT implosions.

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

Study of genomic instability induced by low dose ionizing radiation

International Nuclear Information System (INIS)

Seoane, A.; Crudeli, C.; Dulout, F.

2006-01-01

The crews of commercial flights and services staff of radiology and radiotherapy from hospitals are exposed to low doses of ionizing radiation. Genomic instability includes those adverse effects observed in cells, several generations after the exposure occurred. The purpose of this study was to analyze the occurrence of genomic instability by very low doses of ionizing radiation [es

Transition Delay in Hypersonic Boundary Layers via Optimal Perturbations

Science.gov (United States)

Paredes, Pedro; Choudhari, Meelan M.; Li, Fei

2016-01-01

The effect of nonlinear optimal streaks on disturbance growth in a Mach 6 axisymmetric flow over a 7deg half-angle cone is investigated in an e ort to expand the range of available techniques for transition control. Plane-marching parabolized stability equations are used to characterize the boundary layer instability in the presence of azimuthally periodic streaks. The streaks are observed to stabilize nominally planar Mack mode instabilities, although oblique Mack mode disturbances are destabilized. Experimentally measured transition onset in the absence of any streaks correlates with an amplification factor of N = 6 for the planar Mack modes. For high enough streak amplitudes, the transition threshold of N = 6 is not reached by the Mack mode instabilities within the length of the cone, but subharmonic first mode instabilities, which are destabilized by the presence of the streaks, reach N = 6 near the end of the cone. These results suggest a passive flow control strategy of using micro vortex generators to induce streaks that would delay transition in hypersonic boundary layers.

Contato precoce pele a pele entre mãe e filho: significado para mães e contribuições para a enfermagem

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Thaís Alves Matos

2010-12-01

Full Text Available Tratou-se de uma pesquisa convergente-assistencial, realizada numa maternidade da Região Sul do Brasil entre abril e maio de 2009, objetivando compreender o significado do contato precoce pele-a-pele mãe-filho para o ser-mãe, identificar características do estabelecimento desse contato e contribuições da enfermagem. Os dados foram coletados pela observação participante e entrevista, com nove mães, identificando-se quatro categorias: a orientações acerca do contato pele-a-pele precoce mãe-filho antes do nascimento; b estabelecimento do contato precoce pele-a-pele mãe-filho; c significado do contato pele-a-pele precoce mãe-filho para o ser-mãe; e d contribuições da enfermagem no estabelecimento do contato precoce pele-a-pele mãe-filho. Conclui-se que o significado do contato precoce mãe-filho atribuído pelas mães é positivo, e a contribuição da enfermagem no estabelecimento desse contato é significativa.

Examining the evolution towards turbulence through spatio-temporal analysis of multi-dimensional structures formed by instability growth along a shear layer

Science.gov (United States)

Merritt, Elizabeth; Doss, Forrest; Loomis, Eric; Flippo, Kirk; Devolder, Barbara; Welser-Sherrill, Leslie; Fincke, James; Kline, John

2014-10-01

The counter-propagating shear campaign is examining instability growth and its transition to turbulence relevant to mix in ICF capsules. Experimental platforms on both OMEGA and NIF use anti-symmetric flows about a shear interface to examine isolated Kelvin-Helmholtz instability growth. Measurements of interface (an Al or Ti tracer layer) dynamics are used to benchmark the LANL RAGE hydrocode with BHR turbulence model. The tracer layer does not expand uniformly, but breaks up into multi-dimensional structures that are initially quasi-2D due to the target geometry. We are developing techniques to analyze the multi-D structure growth along the tracer surface with a focus on characterizing the time-dependent structures' spectrum of scales in order to appraise a transition to turbulence in the system and potentially provide tighter constraints on initialization schemes for the BHR model. To this end, we use a wavelet based analysis to diagnose single-time radiographs of the tracer layer surface (w/low and amplified roughness for random noise seeding) with observed spatially non-repetitive features, in order to identify spatial and temporal trends in radiographs taken at different times across several experimental shots. This work conducted under the auspices of the U.S. Department of Energy by LANL under Contract DE-AC52-06NA25396.

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

Tunable surface plasmon instability leading to emission of radiation

Energy Technology Data Exchange (ETDEWEB)

Gumbs, Godfrey [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Donostia International Physics Center (DIPC), P de Manuel Lardizabal, 4, 20018 San Sebastian, Basque Country (Spain); Iurov, Andrii, E-mail: aiurov@chtm.unm.edu [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Pan, Wei [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)

2015-08-07

We propose a new approach for energy conversion from a dc electric field to tunable terahertz emission based on hybrid semiconductors by combining two-dimensional (2D) crystalline layers and a thick conducting material with possible applications for chemical analysis, security scanning, medical (single-molecule) imaging, and telecommunications. The hybrid nano-structure may consist of a single or pair of sheets of graphene, silicene, or a 2D electron gas. When an electric current is passed through a 2D layer, we discover that two low-energy plasmon branches exhibit a characteristic loop in their dispersion before they merge into an unstable region beyond a critical wave vector q{sub c}. This finite q{sub c} gives rise to a wavenumber cutoff in the emission dispersion of the surface plasmon induced instability and emission of radiation (spiler). However, there is no instability for a single driven layer far from the conductor, and the instability of an isolated pair of 2D layers occurs without a wavenumber cutoff. The wavenumber cutoff is found to depend on the conductor electron density, layer separation, distances of layers from the conductor surface, and the driving-current strength.

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.

Anomalous dc resistivity and double layers in the auroral ionosphere

International Nuclear Information System (INIS)

Kindel, J.M.; Barnes, C.; Forslund, D.W.

1980-01-01

There are at least four candidate instabilities which might account for anomalous dc rereresistivity in the auroral ionosphere. These are: the ion-acoustic instability, the Buneman instability, the ion-cyclotron instability and double layers. Results are reported of computer simulations of these four instabilities which suggest that double layers are most likely to be responsible for sistivity in the auroral zone

Mediastinite por perfuração e ruptura do esôfago torácico

Directory of Open Access Journals (Sweden)

Geraldo Roger Normando Jr.

Full Text Available OBJETIVO: Avaliar a mortalidade por mediastinite e sepse originadas por perfuração e ruptura do esôfago torácico, de acordo o tempo de evolução da doença. MÉTODO: Estudo retrospectivo de 14 anos (1992 a 2006, com pacientes portadores de ruptura e perfuração do esôfago. Foi avaliado sexo, idade, mecanismo de lesão, evolução ( 24 horas e tratamento. RESULTADOS: Foram analisados 44 pacientes, sendo 10 do sexo feminino (22,73% e 34 do sexo masculino (77,27%. A variação da idade foi de dois meses a 77 anos e a média de 33,2. Os ferimentos estiveram presentes em 19 casos (43,18%: Arma branca em cinco e projétil de arma de fogo 14. A instrumentação endoscópica foi detectada em nove casos (20,45%. Nos pacientes submetidos à esofagorrafia (diagnóstico precoce, menos de 24 horas a mortalidade esteve presente três casos (20%. Em pacientes submetidos à esofagectomia (diagnóstico tardio, mais de 24 horas a mortalidade ocorreu em oito casos (36,36%, e essa diferença não foi estatisticamente significante (p 0,05. No tratamento conservador, a mortalidade foi em cinco de sete casos a a diferença foi estatisticamente significativa quando comparado com o tratamento cirúrgico. CONCLUSÕES: O tratamento conservador para mediastinite por ruptura e perfuração do esôfago mostrou mortalidade alta quando comparada com tratamento cirúrgico. Entre os pacientes operados, a diferença não foi estatisticamente significante, confirmando a indicação de esofagectomia para casos de infecção avançada e a esofagorrafia para casos precoces.

Characterizing the Prevalence of Chromosome Instability in Interval Colorectal Cancer

Directory of Open Access Journals (Sweden)

A.L. Cisyk

2015-03-01

Full Text Available A substantial proportion of colorectal cancers (CRCs are interval CRCs (I-CRCs; i.e., CRCs diagnosed soon after a colonoscopy. Chromosomal instability (CIN is defined as an increase in the rate of which whole chromosomes/large chromosomal fragments are gained or lost and is observed in 85% of non-hereditary CRCs. The contribution of CIN to the etiology of I-CRCs remains unknown. We established a fluorescence in situ hybridization (FISH approach to characterize CIN by enumerating specific chromosomes and determined the prevalence of numerical CIN in a population-based cohort of I-CRCs and control (sporadic CRCs. Using the population-based Manitoba Health administrative databases and Manitoba Cancer Registry, we identified an age, sex, and colonic site of CRC matched cohort of I-CRCs and controls and retrieved their archived paraffin-embedded tumor samples. FISH chromosome enumeration probes specifically recognizing the pericentric regions of chromosomes 8, 11, and 17 were first used on cell lines and then CRC tissue microarrays to detect aneusomy, which was then used to calculate a CIN score (CS. The 15th percentile CS for control CRC was used to define CIN phenotype. Mean CSs were similar in the control CRCs and I-CRCs; 82% of I-CRCs exhibited a CIN phenotype, which was similar to that in the control CRCs. This study suggests that CIN is the most prevalent contributor to genomic instability in I-CRCs. Further studies should evaluate CIN and microsatellite instability (MSI in the same cohort of I-CRCs to corroborate our findings and to further assess concomitant contribution of CIN and MSI to I-CRCs.

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

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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.

Otite MÃdia e Externa Bilateral em CÃes. Estudo Comparativo do Perfil MicrobiolÃgico e Susceptibilidade a Antimicrobianos das EspecÃeis Prevalentes

OpenAIRE

Lis Christina de Oliveira

2004-01-01

A otite resulta da inflamaÃÃo do conduto auditivo e representa 8-15% dos casos na prÃtica veterinÃria. Com o objetivo de delinear e comparar o perfil de isolamento de microrganismos a partir dos ouvidos mÃdio e externo de cÃes com otite foi realizado este estudo. No perÃodo de agosto/2003 a marÃo/2004 foram analisados 64 cÃes com otite externa e mÃdia associados e 50 cÃes com conduto auditivo hÃgido. A coleta de amostras foi realizada no Centro de Controle de Zoonoses de Fortaleza-CE e a anÃl...

Copy number of the Adenomatous Polyposis Coli gene is not always neutral in sporadic colorectal cancers with loss of heterozygosity for the gene

International Nuclear Information System (INIS)

Zauber, Peter; Marotta, Stephen; Sabbath-Solitare, Marlene

2016-01-01

Changes in the number of alleles of a chromosome may have an impact upon gene expression. Loss of heterozygosity (LOH) indicates that one allele of a gene has been lost, and knowing the exact copy number of the gene would indicate whether duplication of the remaining allele has occurred. We were interested to determine the copy number of the Adenomatous Polyposis Coli (APC) gene in sporadic colorectal cancers with LOH. We selected 38 carcinomas with LOH for the APC gene region of chromosome 5, as determined by amplification of the CA repeat region within the D5S346 loci. The copy number status of APC was ascertained using the SALSA® MLPA® P043-B1 APC Kit. LOH for the DCC gene, KRAS gene mutation, and microsatellite instability were also evaluated for each tumor, utilizing standard polymerase chain reaction methods. No tumor demonstrated microsatellite instability. LOH of the DCC gene was also present in 33 of 36 (91.7 %) informative tumors. A KRAS gene mutation was present in 16 of the 38 (42.1 %) tumors. Twenty-four (63.2 %) of the tumors were copy number neutral, 10 (26.3 %) tumors demonstrated major loss, while two (5.3 %) showed partial loss. Two tumors (5.3 %) had copy number gain. Results of APC and DCC LOH, KRAS and microsatellite instability indicate our colorectal cancer cases were typical of sporadic cancers following the ‘chromosomal instability’ pathway. The majority of our colorectal carcinomas with LOH for APC gene are copy number neutral. However, one-third of our cases showed copy number loss, suggesting that duplication of the remaining allele is not required for the development of a colorectal carcinoma

Kinetic simulations of Rayleigh-Taylor instabilities

International Nuclear Information System (INIS)

Sagert, Irina; Bauer, Wolfgang; Colbry, Dirk; Howell, Jim; Staber, Alec; Strother, Terrance

2014-01-01

We report on an ongoing project to develop a large scale Direct Simulation Monte Carlo code. The code is primarily aimed towards applications in astrophysics such as simulations of core-collapse supernovae. It has been tested on shock wave phenomena in the continuum limit and for matter out of equilibrium. In the current work we focus on the study of fluid instabilities. Like shock waves these are routinely used as test-cases for hydrodynamic codes and are discussed to play an important role in the explosion mechanism of core-collapse supernovae. As a first test we study the evolution of a single-mode Rayleigh-Taylor instability at the interface of a light and a heavy fluid in the presence of a gravitational acceleration. To suppress small-wavelength instabilities caused by the irregularity in the separation layer we use a large particle mean free path. The latter leads to the development of a diffusion layer as particles propagate from one fluid into the other. For small amplitudes, when the instability is in the linear regime, we compare its position and shape to the analytic prediction. Despite the broadening of the fluid interface we see a good agreement with the analytic solution. At later times we observe the development of a mushroom like shape caused by secondary Kelvin-Helmholtz instabilities as seen in hydrodynamic simulations and consistent with experimental observations.

Instabilities and diffusion in a hydrodynamic model of a fluid membrane coupled to a thin active fluid layer.

Science.gov (United States)

Sarkar, N; Basu, A

2012-11-01

We construct a coarse-grained effective two-dimensional (2d hydrodynamic theory as a theoretical model for a coupled system of a fluid membrane and a thin layer of a polar active fluid in its ordered state that is anchored to the membrane. We show that such a system is prone to generic instabilities through the interplay of nonequilibrium drive, polar order and membrane fluctuation. We use our model equations to calculate diffusion coefficients of an inclusion in the membrane and show that their values depend strongly on the system size, in contrast to their equilibrium values. Our work extends the work of S. Sankararaman and S. Ramaswamy (Phys. Rev. Lett., 102, 118107 (2009)) to a coupled system of a fluid membrane and an ordered active fluid layer. Our model is broadly inspired by and should be useful as a starting point for theoretical descriptions of the coupled dynamics of a cell membrane and a cortical actin layer anchored to it.

Molecular genetic analysis of 103 sporadic colorectal tumours in Czech patients.

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Peter Vasovcak

Full Text Available The Czech Republic has one of the highest incidences of colorectal cancer (CRC in Europe. To evaluate whether sporadic CRCs in Czech patients have specific mutational profiles we analysed somatic genetic changes in known CRC genes (APC, KRAS, TP53, CTNNB1, MUTYH and BRAF, loss of heterozygosity (LOH at the APC locus, microsatellite instability (MSI, and methylation of the MLH1 promoter in 103 tumours from 102 individuals. The most frequently mutated gene was APC (68.9% of tumours, followed by KRAS (31.1%, TP53 (27.2%, BRAF (8.7% and CTNNB1 (1.9%. Heterozygous germline MUTYH mutations in 2 patients were unlikely to contribute to the development of their CRCs. LOH at the APC locus was found in 34.3% of tumours, MSI in 24.3% and MLH1 methylation in 12.7%. Seven tumours (6.9% were without any changes in the genes tested. The analysis yielded several findings possibly specific for the Czech cohort. Somatic APC mutations did not cluster in the mutation cluster region (MCR. Tumours with MSI but no MLH1 methylation showed earlier onset and more severe mutational profiles compared to MSI tumours with MLH1 methylation. TP53 mutations were predominantly located outside the hot spots, and transitions were underrepresented. Our analysis supports the observation that germline MUTYH mutations are rare in Czech individuals with sporadic CRCs. Our findings suggest the influence of specific ethnic genetic factors and/or lifestyle and dietary habits typical for the Czech population on the development of these cancers.

EVIDENCE OF ACTIVE MHD INSTABILITY IN EULAG-MHD SIMULATIONS OF SOLAR CONVECTION

Energy Technology Data Exchange (ETDEWEB)

Lawson, Nicolas; Strugarek, Antoine; Charbonneau, Paul, E-mail: nicolas.laws@gmail.ca, E-mail: strugarek@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, Qc H3C 3J7 (Canada)

2015-11-10

We investigate the possible development of magnetohydrodynamical instabilities in the EULAG-MHD “millennium simulation” of Passos and Charbonneau. This simulation sustains a large-scale magnetic cycle characterized by solar-like polarity reversals taking place on a regular multidecadal cadence, and in which zonally oriented bands of strong magnetic fields accumulate below the convective layers, in response to turbulent pumping from above in successive magnetic half-cycles. Key aspects of this simulation include low numerical dissipation and a strongly sub-adiabatic fluid layer underlying the convectively unstable layers corresponding to the modeled solar convection zone. These properties are conducive to the growth and development of two-dimensional instabilities that are otherwise suppressed by stronger dissipation. We find evidence for the action of a non-axisymmetric magnetoshear instability operating in the upper portions of the stably stratified fluid layers. We also investigate the possibility that the Tayler instability may be contributing to the destabilization of the large-scale axisymmetric magnetic component at high latitudes. On the basis of our analyses, we propose a global dynamo scenario whereby the magnetic cycle is driven primarily by turbulent dynamo action in the convecting layers, but MHD instabilities accelerate the dissipation of the magnetic field pumped down into the overshoot and stable layers, thus perhaps significantly influencing the magnetic cycle period. Support for this scenario is found in the distinct global dynamo behaviors observed in an otherwise identical EULAG-MHD simulations, using a different degree of sub-adiabaticity in the stable fluid layers underlying the convection zone.

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.

Inheritable and sporadic non-autoimmune hyperthyroidism.

Science.gov (United States)

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.

Rayleigh-Taylor instability and mixing in SN 1987A

International Nuclear Information System (INIS)

Ebisuzaki, T.; Shigeyama, T.; Nomoto, K.

1989-01-01

The stability of the supernova ejecta is compared with the Rayleigh-Taylor instability for a realistic model of SN 1987A. A linear analysis indicates that the layers around the composition interface between the hydrogen-rich and helium zones, and become Rayleigh-Taylor unstable between the helium and metal zones. In these layers, the pressure increases outward because of deceleration due to the reverse shock which forms when the blast shock hits the massive hydrogen-rich envelope. On the contrary, the density steeply decreases outward because of the preexisting nuclear burning shell. Then, these layers undergo the Raleigh-Taylor instability because of the opposite signs of the pressure and density gradients. The estimated growth rate is larger than the expansion rate of the supernova. The Rayleigh-Taylor instability near the composition interface is likely to induce mixing, which has been strongly suggested from observations of SN 1987A. 25 refs

Comparative histochemical study of Bowen’s disease and actinic keratosis: preserved normal basal cells in Bowen’s disease

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H Ishida

2009-12-01

Full Text Available The degree of DNA-instability as revealed by immunohistochemical staining with anti-cytidine antibody after acid hydrolysis (DNA-instability test has been recently used as a marker of malignancy. This technique was applied to examine 17 skin tissue samples of Bowen’s disease, 47 of actinic keratosis, 15 of squamous cell carcinoma, 5 of seborrheic keratosis, and 10 of normal skin. All benign neoplastic cells of seborrheic keratosis and normal epidermal cells were negative. On the other hand, all cancer cells were positive with the DNA-instability test, indicating their malignancy, but all basal cells in Bowen’s disease were completely negative. Compatible with this result, the basal cells in Bowen’s disease were characteristically normal as evident in other histochemical examinations. Thus, they were negative with p53 immunohistochemistry, with normal signals of chromosome 17 in situ hybridisation and argyrophilic nucleolar organiser region, and showed slightly enhanced proliferative activity as revealed by proliferating cell nuclear antigen immunohistochemistry. Immunohistochemical staining with 34 ß E12 (monoclonal antibody against cytokeratins 1, 5, 10, and 14, which stains all normal epidermal keratinocytes including basal cells, showed that only the basal cells of Bowen’s disease stained strongly and homogeneously, while all cancer cells in the upper layers of Bowen’s disease and all layers of actinic keratosis were only sporadically or weakly stained. Staining with 34 ß B4 (monoclonal antibody against cytokeratin 1, which recognises the whole epidermis except for the basal layer in the normal epidermis, showed that the basal cells in the Bowen’s disease were completely negative, and lower layer cells in the actinic keratosis and upper layer cells in Bowen’s disease were only sporadically stained positive, although the superficial layer cells in actinic keratosis stained strongly and homogeneously. Our findings clearly

Nonlinear Transient Growth and Boundary Layer Transition

Science.gov (United States)

Paredes, Pedro; Choudhari, Meelan M.; Li, Fei

2016-01-01

Parabolized stability equations (PSE) are used in a variational approach to study the optimal, non-modal disturbance growth in a Mach 3 at plate boundary layer and a Mach 6 circular cone boundary layer. As noted in previous works, the optimal initial disturbances correspond to steady counter-rotating streamwise vortices, which subsequently lead to the formation of streamwise-elongated structures, i.e., streaks, via a lift-up effect. The nonlinear evolution of the linearly optimal stationary perturbations is computed using the nonlinear plane-marching PSE for stationary perturbations. A fully implicit marching technique is used to facilitate the computation of nonlinear streaks with large amplitudes. To assess the effect of the finite-amplitude streaks on transition, the linear form of plane- marching PSE is used to investigate the instability of the boundary layer flow modified by spanwise periodic streaks. The onset of bypass transition is estimated by using an N- factor criterion based on the amplification of the streak instabilities. Results show that, for both flow configurations of interest, streaks of sufficiently large amplitude can lead to significantly earlier onset of transition than that in an unperturbed boundary layer without any streaks.

Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

International Nuclear Information System (INIS)

Vincze, Miklos; Borcia, Ion; Harlander, Uwe; Gal, Patrice Le

2016-01-01

A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. (paper)

Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

Energy Technology Data Exchange (ETDEWEB)

Vincze, Miklos; Borcia, Ion; Harlander, Uwe [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology (BTU) Cottbus-Senftenberg, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Gal, Patrice Le, E-mail: vincze.m@lecso.elte.hu [Institut de Recherche sur les Phénomènes Hors Equilibre, CNRS—Aix-Marseille University—Ecole Centrale Marseille, 49 rue F. Joliot-Curie, F-13384 Marseille (France)

2016-12-15

A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense. (paper)

Lipídios plasmáticos após esplenectomia total e parcial em cães

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Danilo Nagib Salomão Paulo

Full Text Available OBJETIVO: Avaliar o efeito da esplenectomia total e parcial (hemiesplenectomia e esplenectomia subtotal no lipidograma de cães. MÉTODO: Foram operados 38 animais, adultos, machos, mestiços, com peso entre 13kg e 15kg. No pré-operatório, depois do exame clínico e jejum de 12 horas de uma dieta-padrão, foram realizados hemograma e lipidograma. Após anestesia geral com tiopental sódico os cães foram submetidos à laparotomia mediana supra e infra-umbilical. Procedeu-se no grupo 1, de sete cães, apenas à manipulação do baço (simulado; no grupo 2, de nove cães, à hemiesplenectomia cranial; no grupo 3, de nove cães, à esplenectomia subtotal, com preservação do pólo inferior do baço, após ligadura e secção dos troncos principais dos vasos esplênicos próximos ao hilo; e no grupo 4, de 13 cães, à esplenectomia total. RESULTADOS: No grupo 4 (esplenectomia total, quando comparamos os valores do lipidograma dos diferentes períodos pós-operatórios com os do pré-operatório, os nossos resultados mostraram que houve aumento significante do colesterol total em todos os períodos pós-operatórios (p 0,05 no 56º PO. O LDL aumentou significantemente no 56º PO (p < 0,01 em relação também aos demais períodos do pós-operatório. Os triglicerídeos e VLDL não apresentaram alterações significantes. Nos animais dos grupos 1 e 3 não houve alterações significantes. Nos do grupo 2, houve aumento significante do colesterol no 7º PO. Não houve diferença estatisticamente significante de peso entre os remanescentes das esplenectomias parciais. CONCLUSÕES: A análise dos resultados nos permitiu concluir que a esplenectomia total induz aumento significante do colesterol total, das frações HDL e LDL, enquanto os níveis de triglicerídios e a fração VLDL não sofrem alterações; a conservação da metade inferior do baço ou a esplenectomia subtotal, com preservação do pólo inferior, protege o animal de alterações lip

Infecções do trato urinário (ITU de cães e gatos: etiologia e resistência aos antimicrobianos

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Vania M. Carvalho

2014-01-01

Full Text Available As infecções bacterianas do trato urinário (ITUs são causa comum de doença em cães, gatos e humanos. Embora bactérias Gram positivas como Staphylococcus spp., Streptococcus spp. e Enterococcus spp., possam ocasionar ITUs, as bactérias Gram negativas (Escherichia coli, Proteus spp., Klebsiella spp., Pseudomonas spp. e Enterobacter spp. respondem por 75% dos casos. Este estudo teve como objetivo determinar a frequência de diferentes gêneros de bactérias em ITUs em cães e gatos, bem como a sua sensibilidade aos antimicrobianos utilizados na rotina clínica. Portanto, amostras de urina de 100 cães e gatos com sinais de ITU foram coletadas assepticamente, sofrendo avaliação microbiológica por meio de métodos qualitativos e quantitativos, além de urinálise. Todos os isolados foram submetidos a testes de sensibilidade aos antimicrobianos. ITU foi confirmada em 74% dos animais, não havendo predominância quanto ao sexo. No que diz respeito à idade, 85% dos cães e 87% dos gatos tinham idades superiores a seis anos. Noventa e cinco cepas bacterianas foram isoladas, com maior frequência de Escherichia coli (55% do total dos sorogrupos O6 e O2. Constatou-se níveis elevados de resistência a antimicrobianos nas cepas isoladas. Para as cepas Gram positivas, tetraciclina (46,1%, enrofloxacina, cotrimazol e estreptomicina (42,3% cada foram as drogas com os maiores índices de resistência. Para as Gram negativas, amoxacilina e tetraciclina apresentaram percentuais acima de 50%. Multiresistência foi verificada em mais de 50% dos principais gêneros isolados. Considerando-se que as cepas de E. coli apresentam potencial zoonótico e forte participação na disseminação de resistência aos antimicrobianos, ressalta-se a importância do papel do médico veterinário na prevenção e controle das ITUs animais e sua contribuição para a saúde pública.

Dioctophyma renale em 28 cães: aspectos clinicopatológicos e ultrassonográficos

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Caroline S. Silveira

2015-11-01

Full Text Available RESUMO A infecção em cães por Dioctophyma renale, relatada em diversas partes do mundo, é considerada incomum, na maioria das vezes. No entanto, em algumas regiões são descritos números crescentes da infecção e muitos dados da epidemiologia e do ciclo biológico do parasito ainda são obscuros. Dessa forma, o trabalho tem como objetivo descrever os aspectos epidemiológicos, clinicopatológicos e ultrassonográficos de casos de infecção por Dioctophyma renale em cães na região da Fronteira Oeste do Rio Grande do Sul. Foram estudados 28 casos de dioctofimose em cães necropsiados ou clinicamente avaliados, submetidos à ultrassonografia e cirurgia para retirada dos parasitos. Os cães errantes foram os mais acometidos e todos com possível acesso às margens do Rio Uruguai. As lesões renais e extrarrenais foram caracterizadas predominantemente por atrofia do parênquima renal com glomerulonefrite esclerosante e peritonite granulomatosa associada a parasitos adultos livres na cavidade abdominal e ovos, bem como migrações erráticas para o tecido subcutâneo. Por fim, os achados ultrassonográficos corresponderam, especialmente, a imagens transversais circulares de até 0,6 cm de diâmetro, com margem hiperecoica e centro hipoecoico. Esses achados foram patognomônicos para infecção por Dioctophyma renale, e o exame ultrassonográfico se mostrou indispensável para o diagnóstico definitivo durante a avaliação clínica. Os achados observados nesse estudo demonstram a importância dessa parasitose na região. Além disso, alertam para a importância do diagnóstico, que vem sendo subestimado, além de apontar a necessidade de mais dados acerca da epidemiologia da doença para que se chegue a métodos efetivos de controle.

Achados clínicos e patológicos em cães infectados naturalmente por herpesvírus canino

OpenAIRE

Oliveira, Eduardo C.; Sonne, Luciana; Bezerra Júnior, Pedro S.; Teixeira, Elisa M.; Dezengrini, Renata; Pavarini, Saulo P.; Flores, Eduardo F.; Driemeier, David

2009-01-01

Descrevem-se os achados clínicos e patológicos e os exames laboratoriais de filhotes de cães com diagnóstico post mortem de infecção por herpesvírus canino. Os casos ocorreram em duas propriedades da Cidade de Porto Alegre, Rio Grande do Sul, em abril de 2007 e julho de 2008. Clinicamente, os cães apresentaram anorexia, apatia, choro e dispneia. A morte dos cães ocorreu após 24-72 horas do início dos sinais clínicos. Na necropsia observaram-se hemorragia multifocal renal e hepatomegalia com p...

DISCUTINDO RELAÇÕES DE GÊNERO ENTRE DISCENTES E DOCENTES A PARTIR DAS COLABORAÇÕES DE SIMONE DE BEAUVOIR E PIERRE BOURDIEU

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Cristiano das Neves Bodart

2017-01-01

Full Text Available Busca-se por meio deste artigo discutir as relações de gênero no Ensino Superior, mas especificamente entre discentes e docentes. Para tanto, foi realizada uma pesquisa com docentes de uma instituição superior privada localizada na Região Metropolitana da Grande Vitória-ES, sendo a estes aplicados questionários fechados. Objetiva-se, a partir das colaborações teóricas de Bourdieu e Beauvoir, discutir a percepção dos docentes dos sexos masculinos e femininos quanto às relações entre professor-aluno.  Identificou-se que mesmo que o Ensino Superior, campo investigado pela pesquisa, caracterize-se como “menos masculino”, a coleta de campo evidenciou que existem momentos em que a desigualdade entre gênero torna-se mais evidente.   This article seeks to discuss gender relations in Higher Education, but specifically between students and teachers. For this, a survey was conducted with teachers from a private higher education institution located in the Greater Vitória Metropolitan Region-ES, to whom were given closed questionnaires.The objective was to discuss the perceptions of male and female teachers regarding professor-student relationships, from the point of view of the theoretical collaborations of Bourdieu and Beauvoir. It was seen that even though Higher Education, the field investigated by this research, is characterized as "less masculine,” the field collection found evidence that there are moments in which the inequality between genders becomes more evident.

Kelvin-Helmholtz instability in a bounded plasma flow

International Nuclear Information System (INIS)

Burinskaya, T. M.

2008-01-01

Kelvin-Helmholtz instability in a three-layer plane geometry is investigated theoretically. It is shown that, in a three-layer system (in contrast to the traditionally considered case in which instability develops at the boundary between two plasma flows), instability can develop at an arbitrary ratio of the plasma flow velocity to the ion-acoustic velocity. Perturbations with wavelengths on the order of the flow thickness or longer can increase even at a zero temperature. The system can also be unstable against long-wavelength perturbations if the flow velocity at one of the boundaries is lower than the sum of the Alfven velocities in the flow and the ambient plasma. The possibility of applying the results obtained to interpret the experimental data acquired in the framework of the CLUSTER multisatellite project is discussed. It follows from these data that, in many cases, the propagation of an accelerated particle flow in the plasma-sheet boundary layer of the Earth's magnetotail is accompanied by the generation of magnetic field oscillations propagating with a velocity on the order of the local Alfven velocity.

A rela??o entre os estilos de socializa??o materna e as concep??es de perd?o em adolescentes.

OpenAIRE

Santos, Lydia Maria Sena e

2014-01-01

O presente estudo buscou analisar a rela??o entre a percep??o dos adolescentes sobre os estilos de socializa??o materna e concep??es sobre perd?o. Os estilos de socializa??o parental s?o definidos como padr?es de atua??o caracter?sticos, que os pais utilizam em diversas situa??es do cotidiano. Esses padr?es caracterizam-se por um conjunto de t?cnicas e formas de atua??o dos pais, que abrangem desde atitudes de aceita??o at? atitudes de controle dos comportamentos indesejados, al?m da imposi??...

Eficácia do fembendazol e do pamoato de pirantel sobre Ancylostoma sp. e Toxocara canis, parasitos intestinais de cães

OpenAIRE

Carvalho, Rogério Oliva

2004-01-01

Este trabalho teve como objetivo avaliar a eficácia individual do fembendazol e do pamoato de pirantel contra nematóides intestinais de cães. Para tal, foram utilizados 36 filhotes de cães, sendo 18 machos e 18 fêmeas com menos de seis meses de idade , provenientes do canil do Departamento de Veterinária da Universidade Federal de Viçosa, selecionados por meio de exames coprológicos de Willis, sedimentação simples e contagem de ovos por grama de fezes (OPG). Foram utilizados os animais que ap...

Kinetic theory of tearing instabilities

International Nuclear Information System (INIS)

Drake, J.F.; Lee, Y.C.

1977-01-01

The transition of the tearing instability from the collisional to the collisionless regime is investigated kinetically using a Fokker--Planck collision operator to represent electron-ion collisions. As a function of the collisionality of the plasma, the tearing instability falls into three regions, which are referred to as collisionless, semi-collisional, and collisional. The width Δ of the singular layer around kxB 0 =0 is limited by electron thermal motion along B 0 in the collisional and semi-collisional regimes and is typically smaller than rho/sub i/, the ion Larmor radius. Previously accepted theories, which are based on the assumption Δvery-much-greater-thanrho/sub i/, are found to be valid only in the collisional regime. The effects of density and temperature gradients on the instabilities are also studied. The tearing instability is only driven by the temperature gradient in the collisional and semi-collisional regimes. Numerical calculations indicate that the semi-collisional tearing instability is particularly relevant to present day high temperature tokamak discharges

Control of secondary instability of the crossflow and Görtler-like vortices (Success and problems)

Science.gov (United States)

Kozlov, Viktor V.; Grek, Genrich R.

The secondary instability on a group of crossflow vortices developing in a swept wing boundary layer is described. It is shown that, for travelling waves, there is a region of linear development, and the growth rate of disturbances appreciably depends on the separation between the vortices. Methods of controlling the secondary instability of the vortices by a controlled wave and local suction are proposed and substantiated. The stability of a flat plate boundary layer modulated by G&ou ml;rtler-like stationary vortices is described. Vortices were generated inside the boundary layer by means of roughness elements arranged in a regular array along the spanwise (z) direction. Transition is not caused directly by these structures, but by the growth of small amplitude travelling waves riding on top of the steady vortices. This situation is analogous to the transition process in Görtler and cross-flows. The waves were found to amplify up to a stage where higher harmonics are gener ated, leading to turbulent breakdown and disintegration of the spanwise boundary layer structure. For strong modulations, the observed instability is quite powerful, and can be excited "naturally" by small uncontrollable background disturbances. Controlled oscillations were then introduced by means of a vibrating ribbon, allowing a detailed investigation of the wave characteristics. The instability seems to be associated with the spanwise gradients of the mean flow, , and at all z-positions, the maximum wave amplitude was found at a wall-normal position where the mean velocity is equal to the phase velocity of the wave, U(y)=c, i.e., at the local critical layer. Unstable waves were observed at frequency well above those for which Tollmien-Schlichting (TS) waves amplify in the Blasius boundary layer. Excitation at lower frequencies and milder basic flow modulation showed that TS-type waves may a lso develop. Study of the transition control in that flow by means of riblets shows that the effect

Threshold of decay instability in an inhomogeneous plasma (Leningrad 1973)

International Nuclear Information System (INIS)

Piliia, A.D.

It is shown that in a spatially inhomogeneous plasma there can exist an absolute decay instability with a threshold lower than that found earlier. This instability arises when two parametrically coupled waves have turning points inside the plasma layer. The cause of the instability is a positive inverse coupling, caused by a nonlinear conversion and a reflection of the waves

Annealing, temperature, and bias-induced threshold voltage instabilities in integrated E/D-mode InAlN/GaN MOS HEMTs

Science.gov (United States)

Blaho, M.; Gregušová, D.; Haščík, Š.; Ťapajna, M.; Fröhlich, K.; Šatka, A.; Kuzmík, J.

2017-07-01

Threshold voltage instabilities are examined in self-aligned E/D-mode n++ GaN/InAlN/GaN MOS HEMTs with a gate length of 2 μm and a source-drain spacing of 10 μm integrated in a logic invertor. The E-mode MOS HEMT technology is based on selective dry etching of the cap layer which is combined with Al2O3 grown by atomic-layer deposition at 380 K. In the D-mode MOS HEMT, the gate recessing is skipped. The nominal threshold voltage (VT) of E/D-mode MOS HEMTs was 0.6 and -3.4 V, respectively; the technology invariant maximal drain current was about 0.45 A/mm. Analysis after 580 K/15 min annealing step and at an elevated temperature up to 430 K reveals opposite device behavior depending on the HEMT operational mode. It was found that the annealing step decreases VT of the D-mode HEMT due to a reduced electron injection into the modified oxide. On the other hand, VT of the E-mode HEMT increases with reduced density of surface donors at the oxide/InAlN interface. Operation at the elevated temperature produces reversible changes: increase/decrease in the VT of the respective D-/E-mode HEMTs. Additional bias-induced experiments exhibit complex trapping phenomena in the devices: Coaction of shallow (˜0.1 eV below EC) traps in the GaN buffer and deep levels at the oxide/InAlN interface was identified for the E-mode device, while trapping in the D-mode HEMTs was found to be consistent with a thermo-ionic injection of electrons into bulk oxide traps (˜0.14 eV above EF) and trapping at the oxide/GaN cap interface states.

Sedimentation from flocculated suspensions in the presence of settling-driven gravitational interface instabilities

Science.gov (United States)

Rouhnia, Mohamad; Strom, Kyle

2015-09-01

We experimentally examine sedimentation from a freshwater suspension of clay flocs overlying saltwater in the presence of gravitational instabilities. The study seeks to determine: (1) if flocculation hampers or alters interface instability formation; (2) how the removal rates of sediment from the buoyant layer compare to those predicted by individual floc settling; and (3) whether or not it is possible to develop a model for effective settling velocity. The experiments were conducted in a tank at isothermal conditions. All experiments were initially stably stratified but later developed instabilities near the interface that grew into downward convecting plumes of fluid and sediment. Throughout, we measured sediment concentration in the upper and lower layers, floc size, and plume descent rates. The data showed that flocculation modifies the mixture settling velocity, and therefore shifts the mode of interface instability from double-diffusive (what one would expect from unflocculated clay) to settling-driven leaking and Rayleigh-Taylor instability formation. Removal rates of sediment from the upper layer in the presence of these instabilities were on the same order of magnitude as those predicted by individual floc settling. However, removal rates were found to better correlate with the speed of the interface plumes. A simple force-balance model was found to be capable of reasonably describing plume velocity based on concentration in the buoyant layer. This relation, coupled with a critical Grashof number and geometry relations, allowed us to develop a model for the effective settling velocity of the mixture based solely on integral values of the upper layer.

Formation of double layers

International Nuclear Information System (INIS)

Leung, P.; Wong, A.Y.; Quon, B.H.

1981-01-01

Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

Dr. E.S. Mulder, Die Teologie van die Jesaja-apokalipse (Jes. 24-27 ...

African Journals Online (AJOL)

Dr. E.S. Mulder, Die Teologie van die Jesaja-apokalipse (Jes. 24-27). Proefschrift ter verkrijging van de graad van Doctor in de Godgeleerdheid aan de Rijksuniversiteit te Groningen. Groningen, J. B. Wolters, 1954, 125 bis.

EFEITO DO EXERCÍCIO FÍSICO SOBRE A SAÚDE E SOBRECARGA DE MÃES DE CRIANÇAS E ADOLESCENTES COM PARALISIA CEREBRAL

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Moisés Rosa Batista

Full Text Available RESUMO Introdução: A paralisia cerebral (PC é considerada a incapacidade física mais comum na infância. Essa doença afeta profundamente a saúde e o bem-estar dos indivíduos acometidos e também pode influenciar múltiplos aspectos da vida de seus cuidadores, especialmente as mães. Objetivo: Avaliar o efeito de um programa de exercício resistido sobre a qualidade de vida relacionada à saúde (QVRS de mães de crianças e adolescentes com PC. Método: Vinte e duas mães sedentárias cuidadoras de crianças e adolescentes com PC, aptas à prática de exercício resistido, participaram de um programa de exercício resistido de intensidade moderada, em 2 sessões semanais durante 12 semanas. Todos os participantes responderam ao questionário de QVRS, Short Form Questionnaire (SF-36, à escala de sobrecarga Caregiver Burden Scale (CBS e ao Inventário de Depressão de Beck (BDI antes e após o programa de intervenção. Os escores dos questionários pré e pós-intervenção foram comparados pelo teste de Wilcoxon e a magnitude das diferenças foi medida pelo tamanho do efeito. Resultados: A mediana de idade das mães foi de 41 anos e variou de 18 a 58 anos. A mediana da idade das crianças/adolescentes foi de 14 anos, variando 3 a 21 anos. Após a intervenção foram encontrados aumentos significativos nos escores do SF-36 (p < 0,05, exceto nos domínios aspectos físicos e aspectos emocionais, que já obtiveram pontuação máxima pré-intervenção. Os escores do CBS e do BDI tiveram redução significativa pós-intervenção (p < 0,05. Conclusão: A prática regular de exercícios resistidos tem impacto positivo sobre a QVRS, a percepção de sobrecarga e a intensidade de sintomas depressivos de mães cuidadoras de crianças e adolescentes com PC.

Numerical simulation of growth of flames formed in a two-dimensional mixing layer. 3rd Report. Flame instability induced by vortices; Nijigen kongo sonai ni keiseisareta kaen no seicho ni kansuru suchi simulation. 3. Uzu ni yotte reikisareru kaen no fuanteisei

Energy Technology Data Exchange (ETDEWEB)

Noda, S; Makino, H [Toyohashi University of Technology, Aichi (Japan); Nakajima, T [Kobe University, Kobe (Japan). Faculty of Engineering

1996-03-25

The flame instability induced by large vortices has been studied numerically. The numerical simulation is concerned with an unstable, two-dimensional, two-stream, spatially developing, confined, reacting shear layer. The behavior just after ignition is related to the flame instability which is affected strongly by large vortices in the mixing layer. Although flames are basically stable due to the balance between the burning velocity and the stream velocity, it is revealed that the leading edge is exposed under the strain in the mixing layer, and the flame becomes instable. Moreover, a method is also proposed to improve the flame stability by increasing the oxygen concentration in the oxidizer. 13 refs., 6 figs., 2 tabs.

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

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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.

Stability of boundary layer flow based on energy gradient theory

Science.gov (United States)

Dou, Hua-Shu; Xu, Wenqian; Khoo, Boo Cheong

2018-05-01

The flow of the laminar boundary layer on a flat plate is studied with the simulation of Navier-Stokes equations. The mechanisms of flow instability at external edge of the boundary layer and near the wall are analyzed using the energy gradient theory. The simulation results show that there is an overshoot on the velocity profile at the external edge of the boundary layer. At this overshoot, the energy gradient function is very large which results in instability according to the energy gradient theory. It is found that the transverse gradient of the total mechanical energy is responsible for the instability at the external edge of the boundary layer, which induces the entrainment of external flow into the boundary layer. Within the boundary layer, there is a maximum of the energy gradient function near the wall, which leads to intensive flow instability near the wall and contributes to the generation of turbulence.

stockées Ephestia kuehniella (Lepidoptera)

African Journals Online (AJOL)

PR BOKO

de Rebat (2008). [5] - B. DOUMANDJI-MITICHI. Etude d'un ravageur des denrées stockées E. Kuehiella, Am.El Harrach. (1997). [6] - F. TAIBI. Etude comparée du développement et de la reproduction chez deux ravageurs des denrées stockées Ephestia Kuehniella et Tenebrio molitor. Aspect endocrinien en rapport avec.

Centrifugally Driven Rayleigh-Taylor Instability

Science.gov (United States)

Scase, Matthew; Hill, Richard

2017-11-01

The instability that develops at the interface between two fluids of differing density due to the rapid rotation of the system may be considered as a limit of high-rotation rate Rayleigh-Taylor instability. Previously the authors have considered the effect of rotation on a gravitationally dominated Rayleigh-Taylor instability and have shown that some growth modes of instability may be suppressed completely by the stabilizing effect of rotation (Phys. Rev. Fluids 2:024801, Sci. Rep. 5:11706). Here we consider the case of very high rotation rates and a negligible gravitational field. The initial condition is of a dense inner cylinder of fluid surrounded by a lighter layer of fluid. As the system is rotated about the generating axis of the cylinder, the dense inner fluid moves away from the axis and the familiar bubbles and spikes of Rayleigh-Taylor instability develop at the interface. The system may be thought of as a ``fluid-fluid centrifuge''. By developing a model based on an Orr-Sommerfeld equation, we consider the effects of viscosity, surface tension and interface diffusion on the growth rate and modes of instability. We show that under particular circumstances some modes may be stabilized. School of Mathematical Sciences.

Excited waves in shear layers

Science.gov (United States)

Bechert, D. W.

1982-01-01

The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

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

Contato precoce pele a pele entre mãe e filho: significado para mães e contribuições para a enfermagem

OpenAIRE

Matos, Thaís Alves; Souza, Morgana Stefani de; Santos, Evanguelia Kotzias Atherino dos; Velho, Manuela Beatriz; Seibert, Eli Rodrigues Camargo; Martins, Nezi Maria

2010-01-01

Tratou-se de uma pesquisa convergente-assistencial, realizada numa maternidade da Região Sul do Brasil entre abril e maio de 2009, objetivando compreender o significado do contato precoce pele-a-pele mãe-filho para o ser-mãe, identificar características do estabelecimento desse contato e contribuições da enfermagem. Os dados foram coletados pela observação participante e entrevista, com nove mães, identificando-se quatro categorias: a) orientações acerca do contato pele-a-pele precoce mãe-fil...

Design and fabrication of a CH/Al dual-layer perturbation target for hydrodynamic instability experiments in ICF

Energy Technology Data Exchange (ETDEWEB)

Tang, Jun [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Xie, Zhiyong [Shanghai Institute of Laser Plasma, Shanghai 201800 (China); Du, Ai [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Ye, Junjian [Shanghai Institute of Laser Plasma, Shanghai 201800 (China); Zhang, Zhihua; Shen, Jun [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Zhou, Bin, E-mail: zhoubin863@tongji.edu.cn [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China)

2014-04-15

Highlights: • Sinusoidal perturbed Al foil was prepared by single-point diamond turning. • Perturbed Al foil was measured by surface profiler and white light interferometer. • Perturbed Al foil and CH layer adhered with each other via a hot-press process. • Parameters and cross-section of the CH–Al perturbation target was characterized. - Abstract: A polystyrene (CH)/aluminum (Al) dual-layer perturbation target for hydrodynamic instability experiments in inertial confinement fusion (ICF) was designed and fabricated. The target was composed of a perturbed 40 μm Al foil and a CH layer. The detailed fabrication method consisted of four steps. The 40 μm Al foil was first prepared by roll and polish process; the perturbation patterns were then introduced on the surface of the Al foil by the single-point diamond turning (SPDT) technology; the CH layer was prepared via a simple method which called spin-coating process; finally, the CH layer was directly coated on the perturbation surface of Al foil by a hot-press process to avoid the use of a sticker and to eliminate the gaps between the CH layer and the Al foil. The parameters of the target, such as the perturbation wavelength (T) and perturbation amplitude (A), were characterized by a QC-5000 tool microscope, an alpha-step 500 surface profiler and a NT1100 white light interferometer. The results showed that T and A of the target were about 52 μm and 7.34 μm, respectively. Thickness of the Al foil (H1), thickness of the CH layer (H2), and cross-section of the dual-layer target were characterized by a QC-5000 tool microscope and a scanning electron microscope (SEM). H1 and H2 were about 40 μm and 15 μm, respectively, the cross-sectional photographs of the target showed that the CH layer and the Al foil adhered perfectly with each other.

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.

An analytic study of the perpendicularly propagating electromagnetic drift instabilities in the Magnetic Reconnection Experiment

International Nuclear Information System (INIS)

Wang Yansong; Kulsrud, Russell; Ji, Hantao

2008-01-01

A local linear theory is proposed for a perpendicularly propagating drift instability driven by relative drifts between electrons and ions. The theory takes into account local cross-field current, pressure gradients, and modest collisions as in the Magnetic Reconnection Experiment [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)]. The unstable waves have very small group velocities in the direction of the pressure gradient, but have a large phase velocity near the relative drift velocity between electrons and ions in the direction of the cross-field current. By taking into account the electron-ion collisions and applying the theory in the Harris sheet, we establish that this instability could be excited near the center of the Harris sheet and have enough e-foldings to grow to large amplitude before it propagates out of the unstable region. Comparing with the other magnetic reconnection related instabilities (lower-hybrid-drift instability, modified two-stream instability, etc.) studied previously, we believe the instability we found is a favorable candidate to produce anomalous resistivity because of its unique wave characteristics, such as electromagnetic component, large phase velocity, and small group velocity in the cross-current-layer direction.

Bottom-type scattering layers and equatorial spread F

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D. L. Hysell

2004-12-01

Full Text Available Jicamarca radar observations of bottom-type coherent scattering layers in the post-sunset bottomside F-region ionosphere are presented and analyzed. The morphology of the primary waves seen in radar images of the layers supports the hypothesis of kudeki+bhattacharyya-1999 that wind-driven gradient drift instabilities are operating. In one layer event when topside spread F did not occur, irregularities were distributed uniformly in space throughout the layers. In another event when topside spread F did eventually occur, the irregularities within the pre-existing bottom-type layers were horizontally clustered, with clusters separated by about 30km. The same horizontal periodicity was evident in the radar plumes and large-scale irregularities that emerged later in the event. We surmise that horizontal periodicity in bottom-type layer irregularity distribution is indicative of large-scale horizontal waves in the bottomside F-region that may serve as seed waves for large-scale Rayleigh Taylor instabilities. Key words. Ionosphere (equatorial ionosphere; ionospheric irregularties; plasma waves and instabilities

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.

The Rayleigh-Taylor instability in inertial fusion, astrophysical plasma and flames

International Nuclear Information System (INIS)

Bychkov, V; Modestov, M; Akkerman, V; Eriksson, L-E

2007-01-01

Previous results are reviewed and new results are presented on the Rayleigh-Taylor instability in inertial confined fusion, flames and supernovae including gravitational and thermonuclear explosion mechanisms. The instability couples micro-scale plasma effects to large-scale hydrodynamic phenomena. In inertial fusion the instability reduces target compression. In supernovae the instability produces large-scale convection, which determines the fate of the star. The instability is often accompanied by mass flux through the unstable interface, which may have either a stabilizing or a destabilizing influence. Destabilization happens due to the Darrieus-Landau instability of a deflagration front. Still, it is unclear whether the instabilities lead to well-organized large-scale structures (bubbles) or to relatively isotropic turbulence (mixing layer)

Alterações eletromiográficas e histopatológicas da musculatura de cães naturalmente infectados por Leishmania infantum

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Gisela Cristiane Ferraro

2012-10-01

Full Text Available O objetivo do presente estudo foi avaliar as alterações eletromiográficas e histopatológicas de músculos estriados esqueléticos de cães naturalmente infectados por Leishmania infantum. Foram selecionados 25 cães adultos, sem raça definida, com diagnósticos parasitológico, molecular e sorológico estabelecidos para a infecção. Os músculos avaliados foram: tríceps braquial, extensorcarpo radial, bíceps femoral e gastrocnêmio. Um cão possuía problemas locomotores, com paresia de membros posteriores associada à intensa atrofia muscular. Vinte e três (92% apresentavam algum tipo de alteração muscular, sendo que em 22(88% tais alterações foram identificadas diretamente pela eletromiografia. Mesmo sem sinais clínicos, em dez cães (40% foram evidenciadas alterações eletromiográficas e histopatológicas. Antígenos de Leishmania foram identificados na musculatura de quatro (16% cães. Os resultados eletromiográficos indicaram a ocorrência de polimiosite crônica em 13 (52% cães, presença de músculos com inflamação tanto aguda quanto crônica em quatro (16%, miopatia aguda em dois (8%, e ausência de alterações eletromiográficas em três (12%. As alterações histopatológicas mais frequentemente observadas foram degeneração e necrose de miofibras e presença de infiltrado inflamatório verificadas em 12 (48% cães. Outras alterações, quando comparado com as amostras de cães normais, foram do tamanho de grupos de fibras musculares em 15 (60% e fibrose peri ou endomisial em 14(56% animais. As alterações observadas no presente estudo permitiram concluir que mesmo na ausência de sinais clínicos de comprometimento muscular, a maior parte dos cães infectados por L. infantum apresenta polimiosite crônica.

Negative capacitance and instability at electrified interfaces: Lessons from the study of membrane capacitors

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M.B.Partenskii

2005-01-01

Full Text Available Various models leading to predictions of negative capacitance, C, are briefly reviewed. Their relation to the nature of electric control is discussed. We reconfirm that the calculated double layer capacitance can be negative under σ-control - an artificial construct that requires uniform distribution of the electrode surface charge density, σ. However, only the total charge C (or the average surface charge density can be experimentally fixed in isolated cell studies (q-control. For those σ where C becomes negative under σ-control, the transition to q-control (i.e. relaxing the lateral change density distribution, fixing its mean value to σ leads to instability of the uniform distribution and a transition to a non-uniform phase. As an illustration, a “membrane capacitor” model is discussed. This exactly solvable model, allowing for both uniform and inhomogeneous relaxation of the electrical double layer, helps to demonstrate both the onset and some important features of the instability. Possibilities for further development are discussed briefly.

FONOFORESE E ELETROESTIMULAÇÃO NEUROMUSCULAR EM CÃES: UMA CONTRIBUIÇÃO PARA A FISIOTERAPIA VETERINARIA

OpenAIRE

Charles Pelizzari

2011-01-01

Esta tese foi dividida em duas pesquisas distintas utilizando fonoforese e eletroterapia, na primeira pesquisa o objetivo foi constatar a concentração plasmática de diclofenaco sódico emulgel em cães com ou sem o uso de fonoforese e se a fonoforese induz maior absorção deste fármaco. Para a realização da fonoforese foram utilizados cinco cães em oito grupos distintos, denominados: Grupo1: aplicação de ultrassom (US) por 6 minutos, remoção do gel com papel toalha e após aplic...

Magalhães Gomes, físico e humanista

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Ângela Vaz Leão

2002-10-01

Full Text Available Este trabalho tem dois objetivos: primeiro apresentar aos leitores da revista Scripta e aos jovens universitários a figura de um grande pesquisador na área da Física que foi também um humanista eminente, o Professor Francisco de Assis Magalhães Gomes; depois, publicar um erudito trabalho seu, de crítica etimológica, intitulado “Um erro etimológico: a origem do vocábulo gallium para designar o elemento 31 da classificação periódica”. Esse trabalho, apenas introduzido no presente artigo, será transcrito no artigo seguinte.

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....

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.

Faraday instability in a near-critical fluid under weightlessness.

Science.gov (United States)

Gandikota, G; Chatain, D; Amiroudine, S; Lyubimova, T; Beysens, D

2014-01-01

Experiments on near-critical hydrogen have been conducted under magnetic compensation of gravity to investigate the Faraday instability that arises at the liquid-vapor interface under zero-gravity conditions. We investigated such instability in the absence of stabilizing gravity. Under such conditions, vibration orients the interface and can destabilize it. The experiments confirm the existence of Faraday waves and demonstrate a transition from a square to a line pattern close to the critical point. They also show a transition very close to the critical point from Faraday to periodic layering of the vapor-liquid interface perpendicular to vibration. It was seen that the Faraday wave instability is favored when the liquid-vapor density difference is large enough (fluid far from the critical point), whereas periodic layering predominates for small difference in the liquid and vapor densities (close to the critical point). It was observed for the Faraday wave instability that the wavelength of the instability decreases as one approaches the critical point. The experimental results demonstrate good agreement to the dispersion relation for zero gravity except for temperatures very close to the critical point where a transition from a square pattern to a line pattern is detected, similarly to what is observed under 1g conditions.

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.

Manejo nutricional de cães e gatos domiciliados no estado do Espírito Santo - Brasil

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K.P. Aptekmann

2013-04-01

Full Text Available Obtiveram-se informações sobre o manejo nutricional adotado para cães e gatos domiciliados, avaliou-se o grau de conhecimento dos proprietários e correlacionaram-se esses dados com fatores socioeconômicos dos entrevistados. Um questionário foi respondido por 496 proprietários de cães e/ou gatos. Verificou-se que os proprietários reconhecem que a alimentação está diretamente relacionada com a saúde animal e se preocupam com a qualidade do alimento fornecido. A ração seca é considerada a melhor opção para a alimentação de cães e gatos e é o tipo de alimento mais utilizado pelos proprietários. Os cães são alimentados preferencialmente duas vezes ao dia, e os gatos recebem alimento à vontade. Os proprietários buscam informações sobre a alimentação dos animais principalmente com veterinários ou estudantes de veterinária e lojas agropecuárias ou pet shops. Em geral, os proprietários de maior escolaridade têm preferência pela ração seca. O custo com a alimentação dos animais é considerado alto, especialmente para os proprietários que fornecem rações terapêuticas. Dessa forma, não são todos que podem arcar com esse custo. Observou-se que os proprietários que fornecem esse tipo de ração são os que apresentam maior poder aquisitivo. O tipo de alimento fornecido ao animal, ração ou comida caseira, não é influenciado pelo ambiente no qual o proprietário reside (rural ou urbano.

Aprendizagem e cultura organizacional na sa?de da fam?lia: an?lise e reflex?es em uma unidade docente-assistencial.

OpenAIRE

Moreira, Josicleide de Amorim Pereira

2013-01-01

A Estrat?gia Sa?de da Fam?lia enfrenta hoje o grande desafio de superar um modelo de aten??o biologicista, e consolidar-se como espa?o de cuidado integral, de inova??o, e de aprendizagem cont?nua. Reconhecer as diferentes subculturas nas organiza??es e potencializar a aprendizagem individual e coletiva ? essencial em espa?os como este. Nesta pesquisa estudamos a Aprendizagem e a Cultura Organizacional em uma unidade docente-assistencial, campo de pr?tica para alguns cursos de gradua??o...

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

Linearised dynamics and non-modal instability analysis of an impinging under-expanded supersonic jet

Science.gov (United States)

Karami, Shahram; Stegeman, Paul C.; Theofilis, Vassilis; Schmid, Peter J.; Soria, Julio

2018-04-01

Non-modal instability analysis of the shear layer near the nozzle of a supersonic under-expanded impinging jet is studied. The shear layer instability is considered to be one of the main components of the feedback loop in supersonic jets. The feedback loop is observed in instantaneous visualisations of the density field where it is noted that acoustic waves scattered by the nozzle lip internalise as shear layer instabilities. A modal analysis describes the asymptotic limit of the instability disturbances and fails to capture short-time responses. Therefore, a non-modal analysis which allows the quantitative description of the short-time amplification or decay of a disturbance is performed by means of a local far-field pressure pulse. An impulse response analysis is performed which allows a wide range of frequencies to be excited. The temporal and spatial growths of the disturbances in the shear layer near the nozzle are studied by decomposing the response using dynamic mode decomposition and Hilbert transform analysis. The short-time response shows that disturbances with non-dimensionalised temporal frequencies in the range of 1 to 4 have positive growth rates in the shear layer. The Hilbert transform analysis shows that high non-dimensionalised temporal frequencies (>4) are dampened immediately, whereas low non-dimensionalised temporal frequencies (analysis show that spatial frequencies between 1 and 3 have positive spatial growth rates. Finally, the envelope of the streamwise velocity disturbances reveals the presence of a convective instability.

Valores humanos nas organiza??es: rela??o com a s?ndrome de Burnout e o engajamento laboral

OpenAIRE

Coelho, Gabriel Lins de Holanda

2014-01-01

Por muitas d?cadas as pesquisas nas organiza??es focaram nos aspectos negativos ocasionados nos trabalhadores, tendo a s?ndrome de burnout como principal expoente. Nos ?ltimos anos, com a expans?o da Psicologia Positiva, o interesse pelos aspectos positivos aumentou e resultou no estudo do engajamento laboral, considerado a ant?tese do burnout e essencial para a maximiza??o do material humano nas organiza??es. Contudo, para a implementa??o de um ambiente que seja prop?cio estimular o engajame...

APOIO SOCIAL E FAMILIAR AS MÃES DE RECÉM-NASCIDOS DE MUITO BAIXO PESO: ESTUDO A PARTIR DO GENOGRAMA E ECOMAPA

OpenAIRE

Adriana Valongo Zani; Giovana Garbelini de Souza

2014-01-01

Objetivo: Identificar os vínculos apoiadores formados pelas mães que possuíam em seu contexto recém-nascido prematuro de muito baixo peso internados na Unidade de Terapia Intensiva Neonatal. Método:Trata-se de investigação com abordagem qualitativa. A coleta de dados ocorreu no período de janeiro à maio de 2014 por entrevista semiestruturada, a partir da qual se construíram o genograma e o ecomapa das mães do estudo. Resultados: Apresentam-se os dados relativos a cinco famílias de mães dos pr...

Genomic instability following irradiation

International Nuclear Information System (INIS)

Hacker-Klom, U.B.; Goehde, W.

2001-01-01

Ionising irradiation may induce genomic instability. The broad spectrum of stress reactions in eukaryontic cells to irradiation complicates the discovery of cellular targets and pathways inducing genomic instability. Irradiation may initiate genomic instability by deletion of genes controlling stability, by induction of genes stimulating instability and/or by activating endogeneous cellular viruses. Alternatively or additionally it is discussed that the initiation of genomic instability may be a consequence of radiation or other agents independently of DNA damage implying non nuclear targets, e.g. signal cascades. As a further mechanism possibly involved our own results may suggest radiation-induced changes in chromatin structure. Once initiated the process of genomic instability probably is perpetuated by endogeneous processes necessary for proliferation. Genomic instability may be a cause or a consequence of the neoplastic phenotype. As a conclusion from the data available up to now a new interpretation of low level radiation effects for radiation protection and in radiotherapy appears useful. The detection of the molecular mechanisms of genomic instability will be important in this context and may contribute to a better understanding of phenomenons occurring at low doses <10 cSv which are not well understood up to now. (orig.)

Clinical Significance and Prognostic Relevance of Microsatellite Instability in Sporadic Colorectal Cancer Patients

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Angelika Copija

2017-01-01

Full Text Available Microsatellite instability (MSI is a marker of the replication error phenotype. It is caused by impaired DNA mismatch repair processes (MMR, resulting in ineffectiveness of the mechanisms responsible for the DNA replication precision and postreplicative DNA repair. MSI underlies the pathogenesis of 10%–20% of colorectal cancer (CRC cases. The data about the potential value of MMR status as a predictive factor for 5-fluorouracil (FU-based chemotherapy remain unclear. According to National Comprehensive Cancer Network updated guidelines, MSI testing is recommended for all patients with stage II CRC because patients with MSI-H (high-frequency MSI tumour may have a good prognosis and obtain no benefit from 5-FU-based adjuvant chemotherapy. The significance of the MSI status as a predictive factor for patients with metastatic disease was not confirmed. The association between the MSI status and the efficacy of the therapy based on anti-programmed death-1 receptor inhibitors requires further studies.

Aspectos ultrassonográficos e citopatológicos das prostatopatias em 52 cães

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Antonio Carlos Cunha Lacreta Junior

2011-10-01

Full Text Available http://dx.doi.org/10.5007/2175-7925.2012v25n1p137Neste estudo foram avaliados 52 cães, machos, inteiros, de idades e raças diferentes, além de cães sem raça definida, apresentando sinais clínicos sugestivos de doença prostática. Todos os animais foram submetidos a exames ultrassonográfico e punção aspirativa da glândula prostática para avaliação citológica. A hiperplasia prostática benigna (HPB foi a prostatopatia mais frequente, seguida pela hiperplasia prostática benigna cística, prostatite bacteriana, abscesso, cisto, adenocarcinoma, prostatite não bacteriana e cisto paraprostático. Depois dos cães sem raça definida, os da raça Poodle e Pastor alemão foram os que apresentaram maior frequência das afecções prostáticas. O exame ultrassonográfico permitiu a determinação das dimensões prostáticas, bem como a visibilização dos aspectos das enfermidades que acometem a glândula e foi efetivo na orientação da punção aspirativa. A avaliação citológica da glândula, principalmente quando associada às alterações das imagens ultrassonográficas, permitiu determinar o diagnóstico presuntivo da afecção.

On the onset of the plasmoid instability

International Nuclear Information System (INIS)

Baty, H.

2012-01-01

A numerical study of magnetic reconnection in two-dimensional resistive magnetohydrodynamics for marginally unstable Sweet-Parker current sheets that are subject to plasmoid formation is carried out. Despite the procedure used to form the primary Sweet-Parker-like current layer, that is different with respect to previous studies, the reconnection layer is unstable to the plasmoid instability for a Lundquist number greater than the expected critical value S c ≈10 4 . For Lundquist numbers S≳S c , the instability exhibits a quasi-periodic behaviour consisting of formation, rapid growth, and evacuation of a moving magnetic island. The so called “plasmoid” breaks up the primary current layer and significantly enhances the maximum current density over the value expected from Sweet-Parker theory. This local enhancement spatially coincides with the downstream X-point of the magnetic island and is associated with the formation of a pair of slow-mode Petschek-like shocks bounding the outflowing plasma. These results suggest that the inter-plasmoid current layers forming in high-Lundquist-number plasmas (S≫S c ) could not be simply described as marginally stable Sweet-Parker current sheets.

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.

Dynamic stabilization of the imploding-shell Rayleigh-Taylor instability

International Nuclear Information System (INIS)

Boris, J.P.

1977-01-01

A method for dynamic stabilization of the Rayleigh-Taylor (R-T) instability on the surface of an imploding fusion pellet is discussed. The driving laser beams are modulated in intensity so the ablation layer is subject to a rapidly and strongly oscillating acceleration. A substantial band of the Rayleigh-Taylor instability spectrum can be stabilized by this oscillation even though the time average acceleration vector lies in the destabilizing direction. By adjusting the frequency, structure, and amplitude of the modulation, the band of dynamically stabilized modes can be made to include the most unstable and dangerous modes. Thus considerably higher aspect ratio shells (i.e., thinner shells) could implode successfully than had been previously considered stable enough. Both theory and numerical simulations support this conclusion for the case of laser-driven pellet implosions. Similar modulation via transverse beam oscillations or parallel bunching should also work to stabilize the most dangerous surface Rayleigh-Taylor modes in relativistic electron-, ion- and heavy ion-pellet fusion schemes. (U.K.)

Cães e preconceito na África do Sul: um diálogo entre literatura e etnografia

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Antonádia Borges

Full Text Available Resumo: Coadunando ficção literária e etnográfica, o presente artigo toma como inspiração o romance Disgrace de Coetzee, os chamados discursos de ódio atribuídos a Julius Malema e a experiência dos moradores de fazenda na região de Kwazulu-Natal para problematizar disputas entre “ideais de existência” que têm cães como mediadores. O objetivo aqui é atentar para o efeito epistemológico que o entendimento das trocas de insultos por meio dos animais pode ter sobre nossa compreensão do racismo na África do Sul e alhures, e sobre o papel da antropologia a esse respeito.

Amidas halogenadas: rea??es de acoplamento e investiga??o in silico da atividade antimicrobiana

OpenAIRE

Montes, Ricardo Carneiro

2016-01-01

O presente trabalho teve como finalidade preparar uma cole??o de benzilamidas para-halogenadas derivadas de ?cidos cin?micos e benzoicos estruturalmente relacionadas atrav?s de rea??es de acoplamento com 4-(cloro, fluro e bromo) benzilaminas, utilizando o benzotriazol-1-iloxi-tris-(dimetilamino)-fosf?nio (BOP) como agente de acoplamento. Al?m disso, foram preparados derivados ?teres e ?steres da amida do ?cido van?lico. Todos os compostos preparados foram submetidos a testes antimicrobianos p...

Familial or Sporadic Idiopathic Scoliosis – classification based on artificial neural network and GAPDH and ACTB transcription profile

Science.gov (United States)

2013-01-01

Background Importance of hereditary factors in the etiology of Idiopathic Scoliosis is widely accepted. In clinical practice some of the IS patients present with positive familial history of the deformity and some do not. Traditionally about 90% of patients have been considered as sporadic cases without familial recurrence. However the exact proportion of Familial and Sporadic Idiopathic Scoliosis is still unknown. Housekeeping genes encode proteins that are usually essential for the maintenance of basic cellular functions. ACTB and GAPDH are two housekeeping genes encoding respectively a cytoskeletal protein β-actin, and glyceraldehyde-3-phosphate dehydrogenase, an enzyme of glycolysis. Although their expression levels can fluctuate between different tissues and persons, human housekeeping genes seem to exhibit a preserved tissue-wide expression ranking order. It was hypothesized that expression ranking order of two representative housekeeping genes ACTB and GAPDH might be disturbed in the tissues of patients with Familial Idiopathic Scoliosis (with positive family history of idiopathic scoliosis) opposed to the patients with no family members affected (Sporadic Idiopathic Scoliosis). An artificial neural network (ANN) was developed that could serve to differentiate between familial and sporadic cases of idiopathic scoliosis based on the expression levels of ACTB and GAPDH in different tissues of scoliotic patients. The aim of the study was to investigate whether the expression levels of ACTB and GAPDH in different tissues of idiopathic scoliosis patients could be used as a source of data for specially developed artificial neural network in order to predict the positive family history of index patient. Results The comparison of developed models showed, that the most satisfactory classification accuracy was achieved for ANN model with 18 nodes in the first hidden layer and 16 nodes in the second hidden layer. The classification accuracy for positive Idiopathic

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.

Vinculacão em mães adolescentes e seus bebés

OpenAIRE

Jongenelen, Ines; Soares, Isabel; Grossmann, Karin; Martins, Carla

2006-01-01

Neste artigo, as autoras apresentam uma investigação empírica com mães adolescentes e seus bebés, conduzida sob a perspectiva da Teoria da Vinculação de Bowlby. Quarenta adolescentes e seus bebés foram avaliados na gravidez e 12.º mês do pós‑parto, com base, respectivamente, na Adult Attachment Interview e na Situação Estranha. Os resultados revelam que a maioria dos bebés apresenta uma organização de vinculação segura à mãe, aos 12 meses de idade. Não foi encontrada uma associação significat...

Generalized laser filamentation instability coupled to cooling instability

International Nuclear Information System (INIS)

Liang, E.P.; Wong, J.; Garrison, J.

1984-01-01

We consider the propagation of laser light in an initially slightly nonuniform plasma. The classical dispersion relation for the laser filamentation growth rate (see e.g., B. Langdon, in the 1980 Lawrence Livermore National Laboratory Laser Program Annual Report, pp. 3-56, UCRL-50021-80, 1981) can be generalized to include other acoustical effects. For example, we find that the inclusion of potential imbalances in the heating and cooling rates of the ambient medium due to density and temperature perturbations can cause the laser filamentation mode to bifurcate into a cooling instability mode at long acoustic wavelengths. We also attempt to study semi-analytically the nonlinear evolution of this and related instabilities. These results have wide applications to a variety of chemical gas lasers and phenomena related to laser-target interactions (e.g., jet-like behavior)

Electrical instability of InGaZnO thin-film transistors with and without titanium sub-oxide layer under light illumination

Science.gov (United States)

Chiu, Y. C.; Zheng, Z. W.; Cheng, C. H.; Chen, P. C.; Yen, S. S.; Fan, C. C.; Hsu, H. H.; Kao, H. L.; Chang, C. Y.

2017-03-01

The electrical instability behaviors of amorphous indium-gallium-zinc oxide thin-film transistors with and without titanium sub-oxide passivation layer were investigated under light illumination in this study. For the unpassivated IGZO TFT device, in contrast with the dark case, a noticeable increase of the sub-threshold swing was observed when under the illumination environment, which can be attributed to the generation of ionized oxygen vacancies within the α-IGZO active layer by high energy photons. For the passivated TFT device, the much smaller SS of 70 mV/dec and high device mobility of >100 cm2/Vs at a drive voltage of 3 V with negligible degradation under light illumination are achieved due to the passivation effect of n-type titanium sub-oxide semiconductor, which may create potential application for high-performance display.

Analysis of instability growth and collisionless relaxation in thermionic converters using 1-D PIC simulations

International Nuclear Information System (INIS)

Kreh, B.B.

1994-12-01

This work investigates the role that the beam-plasma instability may play in a thermionic converter. The traditional assumption of collisionally dominated relaxation is questioned, and the beam-plasma instability is proposed as a possible dominant relaxation mechanism. Theory is developed to describe the beam-plasma instability in the cold-plasma approximation, and the theory is tested with two common Particle-in-Cell (PIC) simulation codes. The theory is first confirmed using an unbounded plasma PIC simulation employing periodic boundary conditions, ES1. The theoretically predicted growth rates are on the order of the plasma frequencies, and ES1 simulations verify these predictions within the order of 1%. For typical conditions encountered in thermionic converters, the resulting growth period is on the order of 7 x 10 -11 seconds. The bounded plasma simulation PDP1 was used to evaluate the influence of finite geometry and the electrode boundaries. For this bounded plasma, a two-stream interaction was supported and resulting in nearly complete thermalization in approximately 5 x 10 -10 seconds. Since the electron-electron collision rate of 10 9 Hz and the electron atom collision rate of 10 7 Hz are significantly slower than the rate of development of these instabilities, the instabilities appear to be an important relaxation mechanism

Modelagem e simulaçâo de colisôes planas entre corpos rígidos

OpenAIRE

Cataldo, Edson; Sampaio, Rubens

2002-01-01

Em geral, o movimento de corpos se dá em ambiente com barreiras podendo ocorrer colisôes. Para que seja possível fazer previsôes da dinâmica é necessário saber o que acontece quando um corpo colide. O problema é portanto: conhecida a dinâmica do corpo pré-colisâo e as propriedades dos corpos que colidem, prever a dinâmica pós-colisâo. Os primeiros trabalhos publicados sobre o assunto datam de 1668 e, até 1984, os modelos existentes pareciam satisfatórios. Porém, a aplica¸câo de um desse...

Simulation of plasma double-layer structures

International Nuclear Information System (INIS)

Borovsky, J.E.; Joyce, G.

1982-01-01

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2-dimensional particle-in-cell method. The investigation of planar double layers indicates that these one-dimensional potential structures are susceptible to periodic disruption by instabilities in the low-potential plasmas. Only a slight increase in the double-layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double-layer electric-field alignment of accelerated particles and strong magnetization results in their magnetic-field alignment. The numerial simulations of spatially periodic two-dimensional double layers also exhibit cyclical instability. A morphological invariance in two-dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron-beam excited electrostatic electron-cyclotron waves and (ion-beam driven) solitary waves are present in the plasmas adjacent to the double layers

Linear Rayleigh-Taylor instability in an accelerated Newtonian fluid with finite width

Science.gov (United States)

Piriz, S. A.; Piriz, A. R.; Tahir, N. A.

2018-04-01

The linear theory of Rayleigh-Taylor instability is developed for the case of a viscous fluid layer accelerated by a semi-infinite viscous fluid, considering that the top interface is a free surface. Effects of the surface tensions at both interfaces are taken into account. When viscous effects dominate on surface tensions, an interplay of two mechanisms determines opposite behaviors of the instability growth rate with the thickness of the heavy layer for an Atwood number AT=1 and for sufficiently small values of AT. In the former case, viscosity is a less effective stabilizing mechanism for the thinnest layers. However, the finite thickness of the heavy layer enhances its viscous effects that, in general, prevail on the viscous effects of the semi-infinite medium.

Suppression of instability in rotatory hydromagnetic convection

Indian Academy of Sciences (India)

first time by Lord Rayleigh [9] for the idealized case of two free boundaries. Rayleigh's theory shows that the gravity-dominated thermal instability in liquid layer ... suppressed for oscillatory perturbations by the simultaneous application of a ...

Será o essencial inaudível? Estudo da interacção de mães com filhos surdos e mães com filhos ouvintes

OpenAIRE

Correia, Ricardina

2008-01-01

Dissertação de Mestrado apresentada ao ISPA - Instituto Universitário Este estudo procura identificar as diferenças nas interacções de tutela estabelecidas entre mães ouvintes com crianças surdas e mães ouvintes com crianças ouvintes, quer ao nível da partilha de responsabilidade pela execução da tarefa, numa situação de resolução de problemas, quer ao nível da comunicação referencial. Além disso, dentro das díades de mãe/criança surda, pretendeu verificar-se se a percepção ...

Nonlinear saturation of E x B instability in a plasma slab

International Nuclear Information System (INIS)

Alfsen, K.H.; Holter, Oe.

1984-09-01

The saturation of the E bar x B bar instability is investigated in the nonlinear regime. The governing equations are studied analytically and numerically by using a spectral method with mode truncation. The nonlinear stabilization is due to modifications of the background density- and potential profiles. In the time asymptotic limit a stationary solution, which is independent of the initial conditions is obtained. The asymptotic state is characterized by a splitting of the interacting modes into two almost non-interacting groups, where the modes with even mode number sum; i.e. the modes driven by the linearly most unstable mode, is found to dominate the system. For this group fixed point calculations are performed analytically with six interacting modes. Comparison with numerical calculations indicates excellent agreement far into the unstable region. (Auth.)

The Time-Dependent Structure of the Electron Reconnection Layer

Science.gov (United States)

Hesse, Michael; Zenitani, Seiji; Kuznetsova, Masha; Klimas, Alex

2009-01-01

Collisionless magnetic reconnection is often associated with time-dependent behavior. Specifically, current layers in the diffusion region can become unstable to tearing-type instabilities on one hand, or to instabilities with current-aligned wave vectors on the other. In the former case, the growth of tearing instabilities typically leads to the production of magnetic islands, which potentially provide feedback on the reconnection process itself, as well as on the rate of reconnection. The second class of instabilities tend to modulate the current layer along the direction of the current flow, for instance generating kink-type perturbations, or smaller-scale turbulence with the potential to broaden the current layer. All of these processes contribute to rendering magnetic reconnection time-dependent. In this presentation, we will provide a summary of these effects, and a discussion of how much they contribute to the overall magnetic reconnection rate.

Vertical structure of atmospheric boundary layer over Ranchi during the summer monsoon season

Science.gov (United States)

Chandra, Sagarika; Srivastava, Nishi; Kumar, Manoj

2018-04-01

Thermodynamic structure and variability in the atmospheric boundary layer have been investigated with the help of balloon-borne GPS radiosonde over a monsoon trough station Ranchi (Lat. 23°45'N, Long. 85°43'E, India) during the summer monsoon season (June-September) for a period of 2011-2013. Virtual potential temperature gradient method is used for the determination of mixed layer height (MLH). The MLH has been found to vary in the range of 1000-1300 m during the onset, 600-900 m during the active and 1400-1750 m during the break phase of monsoon over this region. Inter-annual variations noticed in MLH could be associated with inter-annual variability in convection and rainfall prevailing over the region. Along with the MLH, the cloud layer heights are also derived from the thermodynamic profiles for the onset, active and break phases of monsoon. Cloud layer height varied a lot during different phases of the monsoon. For the determination of boundary-layer convection, thermodynamic parameter difference (δθ = θ es- θ e) between saturated equivalent potential temperature (θ es ) and equivalent potential temperature (θ e) is used. It is a good indicator of convection and indicates the intense and suppressed convection during different phases of monsoon.

Efeito do soro de leite no teor protéico e na qualidade tecnológica e sensorial de pães

Directory of Open Access Journals (Sweden)

Elessandra da Rosa Zavareze

2008-08-01

Full Text Available O trabalho teve como objetivo utilizar soro de leite in natura, concentrado e desidratado na formulação de pão e avaliar a influência deste ingrediente nas características tecnológicas e sensoriais do produto, assim como o aumento no teor protéico. Os resultados foram avaliados por análise de variância e as médias comparadas por teste de Tukey (p < 0,05. Os dados foram submetidos à correlação de Pearson. Os pães com soro de leite apresentaram maior teor protéico e notas tecnológicas superiores ao pão padrão, com exceção do pão com soro desidratado que apresentou menor volume específico. Na avaliação sensorial, os pães com adição de soro não apresentaram diferença significativa em relação ao pão padrão.

The first coordinated observations of mid-latitude E-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

Directory of Open Access Journals (Sweden)

T. Ogawa

2005-10-01

Full Text Available We present the first coordinated observations of quasi-periodic (QP radar echoes from sporadic-E (Es field-aligned irregularities (FAIs, OI 557.7-nm airglow, and neutral winds in a common volume over Shigaraki, Japan (34.9° N, 136.1° E on the night of 5 August 2002 during the SEEK-2 campaign. QP echo altitudes of 90-110 km were lower than usual by 10 km, enabling us to make a detailed comparison among QP echoes, airglow intensity, and neutral wind at around 96 km altitude. Eastward movement of the QP echo regions is consistent with the motions of neutral winds, airglow structures, and FAIs, suggesting that the electrodynamics of Es-layers is fundamentally controlled by the neutral atmospheric dynamics. During the QP echo event, the echo altitudes clearly went up (down in harmony with an airglow enhancement (subsidence that also moved to the east. This fact suggests that the eastward-moving enhanced airglow region included an upward (downward component of neutral winds to raise (lower the altitude of the wind-shear node responsible for the Es formation. The airglow intensity, echo intensity, and Doppler velocity of FAIs at around 96 km altitude fluctuated with periods from 10 min to 1h, indicating that these parameters were modulated with short-period atmospheric disturbances. Some QP echo regions below 100km altitude contained small-scale QP structures in which very strong neutral winds exceeding 100 m/s existed. The results are compared with recent observations, theories, and simulations of QP echoes. Keywords. Ionosphere (Ionosphere-atmosphere interactions; Ionospheric irregularities; Mid-latitude ionosphere

Estudo retrospectivo de radiografias com fraturas rádio e ulna em cães

Directory of Open Access Journals (Sweden)

Robson Fortes Giglio

2007-12-01

Full Text Available Foram analisadas 528 radiografias simples de fraturas de rádio e ulna do arquivo do Serviço de Diagnostico por Imagem do Departamento de Cirurgia junto ao Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo realizadas no período de julho de 1999 a dezembro de 2005, selecionando-se os meses para análise de forma randomizada. Os principais resultados encontrados foram: Fraturas de rádio e ulna representam 20,9% do total encontradas, destas o tipo mais observado foi a transversal, tanto no rádio (75,5% quanto na ulna (76,6%. 87,1% das fraturas acometeram o rádio e a ulna. O terço distal foi o mais acometido foi o distal, tanto do rádio quanto da ulna (72,9% e 70,1%, respectivamente. Esquírolas ósseas foram observadas em 13,8% e desvio de eixo ósseo em 94,9% dos casos. 40,2% dos cães não possuíam raça definida. 34,3% dos cães possuíam idade entre seis meses a um ano.

Sporadic colorectal polyps and mismatch repair proteins

Directory of Open Access Journals (Sweden)

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.

2D Relativistic MHD simulations of the Kruskal-Schwarzschild instability in a relativistic striped wind

Science.gov (United States)

Gill, Ramandeep; Granot, Jonathan; Lyubarsky, Yuri

2018-03-01

We study the linear and non-linear development of the Kruskal-Schwarzchild instability in a relativisitically expanding striped wind. This instability is the generalization of Rayleigh-Taylor instability in the presence of a magnetic field. It has been suggested to produce a self-sustained acceleration mechanism in strongly magnetized outflows found in active galactic nuclei, gamma-ray bursts, and micro-quasars. The instability leads to magnetic reconnection, but in contrast with steady-state Sweet-Parker reconnection, the dissipation rate is not limited by the current layer's small aspect ratio. We performed two-dimensional (2D) relativistic magnetohydrodynamic (RMHD) simulations featuring two cold and highly magnetized (1 ≤ σ ≤ 103) plasma layers with an anti-parallel magnetic field separated by a thin layer of relativistically hot plasma with a local effective gravity induced by the outflow's acceleration. Our simulations show how the heavier relativistically hot plasma in the reconnecting layer drips out and allows oppositely oriented magnetic field lines to reconnect. The instability's growth rate in the linear regime matches the predictions of linear stability analysis. We find turbulence rather than an ordered bulk flow near the reconnection region, with turbulent velocities up to ˜0.1c, largely independent of model parameters. However, the magnetic energy dissipation rate is found to be much slower, corresponding to an effective ordered bulk velocity inflow into the reconnection region vin = βinc of 10-3 ≲ βin ≲ 5 × 10-3. This occurs due to the slow evacuation of hot plasma from the current layer, largely because of the Kelvin-Helmholtz instability experienced by the dripping plasma. 3D RMHD simulations are needed to further investigate the non-linear regime.

Epidemiologia e distribuição de lesões extrarrenais de uremia em 161 cães

Directory of Open Access Journals (Sweden)

Isadora P. Silveira

2015-06-01

Full Text Available Resumo: Com o objetivo de determinar a epidemiologia e as características morfológicas, incluindo a localização anatômica, das lesões extrarrenais de uremia, bem como determinar as principais lesões do sistema urinário associadas à ocorrência de uremia, foram revisados os protocolos de necropsias de cães realizadas no Laboratório de Patologia Veterinária da Universidade Federal de Santa Maria de janeiro de 1996 a dezembro de 2012 (17 anos. Nesse período foram necropsiados 4.201 cães, sendo que 161 (3,8% apresentaram lesões extrarrenais de uremia. Em 134 cães (83,2% foram descritos sinais clínicos associados à uremia. As lesões extrarrenais mais frequentes, em ordem decrescente, foram: gastrite ulcerativa e hemorrágica (56,5%, mineralização de tecidos moles (55,9%, edema pulmonar (47,2%, estomatite e/ou glossite ulcerativa (30,4%, endocardite/trombose atrial e aórtica (28,6%, hiperplasia das paratireoides (9,3%, osteodistrofia fibrosa (8,1%, anemia (6,2%, laringite ulcerativa (5%, enterite ulcerativa/hemorrágica (3,7%, esofagite fibrinonecrótica (1,9% e pericardite fibrinosa (1.9%. Na maioria dos casos as lesões extrarrenais de uremia foram decorrentes de azotemia prolongada por lesões renais graves, sendo as mais prevalentes a nefrite intersticial e a glomerulonefrite.

Caminhos retóricos e sorrisos incômodos : argumentação e humor em "A encalhada", de Ingrid Guimarães e Aloísio Abre

OpenAIRE

Ferraz, Luana

2015-01-01

Esta dissertação aborda a construção retórica da comicidade em peças teatrais. Para tanto, propõe a investigação das estratégias retóricas que enfatizam o efeito cômico no esquete “A encalhada”, de Ingrid Guimarães e Aloísio de Abreu – uma das nove cenas que compõem o espetáculo Cócegas (EMI, 2004), interpretado pelas atrizes brasileiras Heloísa Périssé e Ingrid Guimarães. O embasamento teórico para este trabalho é fornecido, principalmente, pelos tratados da Retórica Antiga...

Study of parametric instabilities during the Alcator C lower hybrid wave heating experiments

International Nuclear Information System (INIS)

Takase, Y.

1983-10-01

Parametric excitation of ion-cyclotron quasi-modes (ω/sub R/ approx. = nω/sub ci/) and ion-sound quasi-modes (ω/sub R/ approx. = k/sub parallel to/v/sub ti/) during lower hybrid wave heating of tokamak plasmas have been studied in detail. Such instabilities may significantly modify the incident wavenumber spectrum near the plasma edge. Convective losses for these instabilities are high if well-defined resonance cones exist, but they are significantly reduced if the resonance cones spread and fill the plasma volume (or some region of it). These instabilities preferentially excite lower hybrid waves with larger values of n/sub parallel to/ than themselves possess, and the new waves tend to be absorbed near the outer layers of the plasma. Parametric instabilities during lower hybrid heating of Alcator C plasmas have been investigated using rf probes (to study tilde phi and tilde n/sub i/) and CO 2 scattering technique (to study tilde n/sub e/). At lower densities (anti n/sub e/ less than or equal to 0.5 x 10 14 cm -3 ) where waves observed in the plasma interior using CO 2 scattering appear to be localized, parametric decay is very weak. Both ion-sound and ion-cyclotron parametric decay processes have been observed at higher densities (anti n greater than or equal to 1.5 x 10 14 cm -3 ) where waves appear to be unlocalized. Finally, at still higher densities (anti n /sub e/ greater than or equal to 2 x 10 4 cm -3 ) pump depletion has been observed. Above these densities heating and current drive efficiencies are expected to degrade significantly

An explanation for the physical instability of a marketed fixed dose combination (FDC) formulation containing isoniazid and ethambutol and proposed solutions.

Science.gov (United States)

Bhutani, Hemant; Mariappan, T T; Singh, Saranjit

2004-07-01

An investigation was carried out to explore the possible reason for the physical instability of a marketed strip packaged anti-TB fixed dose combination (FDC) tablet containing 300 mg of isoniazid (H) and 800 mg of ethambutol hydrochloride (E). The instability was in the form of distribution of white powder inside the strip pockets. High-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS-MS) studies confirmed that both H and E were present in the powder. The same was also confirmed through Fourier-transform infrared (FTIR) spectroscopy, which also indicated absence of interaction between the two drugs. No sublimation of the drugs was observed up to 110 degrees C, indicating that the observed instability was not due to this reason. Subsequently, attention was paid to the possibility of moisture gain by the tablets through defective packaging (which was established) due to hygroscopicity of E. To understand the phenomenon further, pure drugs and their mixtures were stored under accelerated conditions of temperature and humidity [40 degrees C/75% relative humidity (RH)] and both increase in weight and physical changes were recorded periodically. The mixtures gained moisture at a higher rate than pure E and those with higher content of E became liquid, which on withdrawal from the chambers, became crystallized. The drug mixture containing H:E at a ratio of 30:70 w/w, which was similar to the ratio of the drugs in the tablets (27:73 w/w), crystallized fastest, indicating formation of a rapid crystallizing saturated system at this ratio of the drugs. It is postulated that the problem of instability arises because of the formation of a saturated layer of drugs upon moisture gain through the defective packaging material and drying of this layer with time. The study suggests that barrier packaging free from defects and alternatively (or in combination) film coating of the tablets with water-resistant polymers are essential for this

Oralidade e memória: o registro audiovisual de A história de Lélio e Lina de Guimarães Rosa

Directory of Open Access Journals (Sweden)

Eleni Ferreira de Souza Gonçalves

2016-09-01

Full Text Available Este trabalho aborda as questões da memória e da oralidade na narrativa de Guimarães Rosa. Adotamos uma análise comparativa entre a novela A história de Lélio e Lina e o respectivo registro oral – em forma de documentário – feito pelos Grupos de Contadores de Histórias de Cordisburgo e do Morro da Garça, em Minas Gerais. Analisamos no texto roseano transposto para o suporte audiovisual o que se mantém em um e outro e verificamos os possíveis efeitos que causam ao leitor e ao espectador. Na transposição, se a memória do texto escrito permanece, os elementos da oralidade e da memória sertaneja adquirem outra dimensão na fala dos narradores. Referenciamo-nos no livro A memória Coletiva, de Maurice Halbwachs, e na entrevista de Guimarães Rosa a Gunter Lorenz, na qual o escritor enfatiza aspectos decisivos de sua escrita, sua relação com a língua e linguagem e sua memória em relação ao sertão.

Critical states and thermomagnetic instabilities in three-dimensional nanostructured superconductors

Energy Technology Data Exchange (ETDEWEB)

Tamegai, T., E-mail: tamegai@ap.t.u-tokyo.ac.jp [Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Mine, A.; Tsuchiya, Y.; Miyano, S.; Pyon, S. [Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Mawatari, Y.; Nagasawa, S.; Hidaka, M. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan)

2017-02-15

Highlights: • Critical state field profiles and thermomagnetic instabilities are studied in three-dimensional nanostructured superconductors. • We find that the critical state field profiles in bi-layer systems are not simple superpositions of critical states in the two layers. • We also studied flux avalanches in shifted strip arrays with layer numbers up to six. • Various forms of avalanches either perpendicular or parallel to the strip are observed when the overlap between layers is large. • We find that introduction of asymmetry to shifted strip arrays affects the shape of flux avalanches sensitively. - Abstract: Critical state field profiles and thermomagnetic instabilities are studied in two kinds of three-dimensional nanostructured superconductors. We find that the critical state field profiles in some simple bi-layer systems are not simple superpositions of critical states in the two layers. Competition between the divergence of the local field at the edges of the film and the shielding by the neighboring layer makes novel critical state field profiles. We also studied flux avalanches in shifted strip arrays (SSAs) with layer numbers up to six. Various forms of avalanches either perpendicular or parallel to the strip are observed when the overlap between strips in neighboring layers is large. We also find that introduction of asymmetry in various forms to SSA affects the shape of flux avalanches sensitively.

Dermatofitoses no meio urbano e a coexistência do homem com cães e gatos

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Adriana de Queiroz Pinheiro

1997-08-01

Full Text Available Foram submetidos a exame clínico laboratorial de dermatofitose e inqueridos sobre o possível contato com cães e gatos 158 pacientes residentes na área urbana de Fortaleza, que apresentavam lesões suspeitas de dermatofitose. Esta busca associada aos dados obtidos em questionário permitiram identificar a freqüência de surtos domiciliares. Dentre os 83 dermatófitos isolados de infecções humanas, predominaram as espécies antropofílicas sobre as zoofílicas, tendo sido observado uma confluência de diagnóstico humano e animal em 100% dos casos de dermatofitoses zoofílicas humanas, onde foram identificadas as mesmas espécies no homem e nos animais contactantes: Microsporum canis e Trichophyton mentagrophytes. Já os pacientes portadores de dermatófitos antropofílicos variaram quanto ao contato com animais domésticos, não tendo sido isolado estes fungos de nenhum animal contactante. Diante da baixa freqüência de dermatofitoses zoofílicas, considerou-se que o convívio do homem com cães e gatos domésticos foi pouco representativo como fator condicionante da ocorrência de dermatofitoses no meio urbano.There have been submitted to clinical exam in laboratory of dermatofitosis and inquired about possible contact with domestic animals (dogs and cats 158 patients living in the urban area of Fortaleza, that showed lesions suspected of dermatofitosis. This search associated to the obtained data in questionnaires permitted us to identify the frquency of domicile outbreaks. Within the 83 people with dermatosis isolated of human infections, prevailed the anthopophylical species over the zoophylical ones, and that it was observed a confluence of human and animal diagnosis in 100% of the human dermatophytosis zoophylical cases, where the same species were identified in men and contacting animals: M. canis and T. mentagrophytes. As the patients carrying antropophylical dermatophytosis varied as to the contact with animals, not having been

Laminar Boundary-Layer Instabilities on Hypersonic Cones: Computations for Benchmark Experiments

National Research Council Canada - National Science Library

Robarge, Tyler W; Schneider, Steven P

2005-01-01

.... The STABL code package and its PSE-Chem stability solver are used to compute first and second mode instabilities for both sharp and blunt cones at wind tunnel conditions, with laminar mean flows...

Instability of a double layer and initiation of a photoelectric gas discharge by UV radiation

International Nuclear Information System (INIS)

Meshalkin, E.A.

1991-01-01

At the present time there is no theory or systematic experiments for the conversion of the energy of vacuum uv radiation into current energy in connection with the photoelectric effect in gases. The aim in this work was to study the process by which an SCL is established and to obtain a gas discharge associated with photoemission (a photoelectric gas discharge), similar to the gas discharge in thermal-emission converters, in order to transform optical energy into electrical current. The development of a space-charge layer (SCL) is studied when a metallic target in air or nitrogen at a pressure in the range 10 -3 -10 torr is subjected to UV radiation. A laser plasma was used as the source of the UV radiation, modulated in intensity at a frequency of 75 MHz. It was found that after a period of development in the course of which the potential difference across the SCL can reach 185 V, it drops abruptly. This effect is due to an instability of the SCL which arises because the pressure of the electron gas in the background plasma exceeds the confining pressure of the electric field which penetrates from SCL into the plasma. A photoelectric arc discharge was observed in which the energy of the UV radiation was converted into current energy with an efficiency ∼ 1%. The current was found to be 3.1 A and the power in the load was 10W. Because of the threshold for the occurrence of the instability in the SCL, the potential drop across the SCL could be completely modulated at a frequency of 75 MHz. The amplitude of the HF current reached 0.3 A

A saga do burro e do boi: um estudo de O burrinho pedrÃs e Conversa de bois, de JoÃo GuimarÃes Rosa

OpenAIRE

Kelly Cristina Medeiros Ferreira

2009-01-01

JoÃo GuimarÃes Rosa definia-se como um homem do sertÃo e mostrava-se fortemente ligado à terra. Ao longo de sua monumental obra encontramos densos registros sobre essa ligaÃÃo. Em 1965, revela em entrevista a Gunter W. Lorenz seu peculiar interesse por animais, diplomacia, religiÃes e idiomas. A biografia do escritor nÃo se dissocia da obra. Dessa forma, evidencia-se em O burrinho pedrÃs e Conversa de bois - o tratamento conspÃcuo dispensado aos bichos. Assim sendo, procederemo...

Morfologia do esôfago e do papo de perdizes Rhynchotus rufescens (Tiramidae - DOI: 10.4025/actascibiolsci.v28i2.1041 Morphology of oesophagus and crop of the partrigde Rhynchotus rufescens (Tiramidae - DOI: 10.4025/actascibiolsci.v28i2.1041

Directory of Open Access Journals (Sweden)

Marcos Lania de Araújo

2006-03-01

Full Text Available Vinte exemplares de Rhynchotus rufescens foram utilizadas para estudar a morfologia do esôfago e do papo. O material para o estudo morfológico foi coletado e o comprimento dos órgãos foi avaliado. Para o estudo histológico, as secções histológicas foram coradas com tricromo de Masson, posteriormente analisadas e descritas. O comprimento médio total do esôfago foi maior em fêmeas. Na entrada do tórax, a parede ventral do esôfago se dilata, formando o papo, maior em machos. A mucosa do esôfago é formada por epitélio escamoso estratificado, com glândulas mucosas e nódulos linfáticos. Há três camadas de músculo liso, as quais são envolvidas por serosa. A característica histológica do papo é semelhante à do esôfago. No papo, as glândulas mucosas são menores e os nódulos linfáticos estão dispersos no tecido conjuntivo. Há uma camada delgada de músculo liso e outras duas camadas mais largas de musculaturas longitudinal e circular.Twenty adult partridges Rhynchotus rufescens were used to study the morphology of oesophagus and crop. Materials to the morphologic study were collected and lengths of the oesophagus and of the crop were measured. For histological study, fragments of the oesophagus and of the crop were stained routinely with Masson’s trichrome stain. Total oesophagus was larger in females. In the entrance of the thorax, its ventral wall is enlarged broadly, forming the crop, which is larger in males. Oesophagus mucosa is constituted by stratified squamous epithelium, with mucous glands and lymphatic tissues. There are three layers of smooth muscle, involved in serosa. The histological structure of the crop is similar to the oesophagus. The mucous glands are reduced in size and the lymphatic tissues are dispersed in the connective tissue. There is a thin stratum of smooth muscle and other two wider layers of longitudinal and circular musculature.

RecÃm-nascidos com malformaÃÃes congÃnitas: prevalÃncia e cuidados de enfermagem na unidade neonatal.

OpenAIRE

FabÃola Chaves Fontoura

2012-01-01

Os recÃm-nascidos (RN) com malformaÃÃo congÃnita (MC) requerem dos profissionais de enfermagem atenÃÃo e cuidados especÃficos e individualizados. O estudo objetivou avaliar a prevalÃncia dos recÃm-nascidos com malformaÃÃes congÃnitas em instituiÃÃes pÃblicas e a assistÃncia de enfermagem prestada a essas crianÃas internadas na Unidade Neonatal (UN) nas primeiras 24 horas de vida. Estudo descritivo, transversal, quantitativo, realizado em trÃs Unidades Neonatais de instituiÃÃes hospitalares (A...

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

Incisuroplastia troclear e estabilização articular após transecção do ligamento cruzado cranial: Estudo clínico e radiográfico em cães Intercondylar notchplasty and fascial strip repair following transection of the cranial cruciate ligament: Clinical and radiographic aspects in the dog

Directory of Open Access Journals (Sweden)

André Luis Selmi

2007-10-01

Full Text Available Avaliaram-se as alterações clínicas e radiográficas em nove cães adultos, após a transecção do ligamento cruzado cranial (LCCr seguida da substituição ligamentar por retalho de fáscia lata, associada ou não à incisuroplastia troclear (ITR. O joelho direito (GI foi submetido à ITR e posterior estabilização articular, e o esquerdo somente à substituição ligamentar (GC. Os animais foram avaliados nos períodos pré-operatório, pós-operatório (po imediato e aos 30, 90 e 180 dias de po, período coincidente com o momento de eutanásia de subgrupos de três cães. A instabilidade articular e o grau de claudicação diminuíram significativamente durante o período de avaliação, apesar da instabilidade persistir durante a flexão articular. Observou-se decréscimo significativo do perímetro muscular da coxa aos 30 e 90 dias p.o. em ambos os grupos. Não foram evidenciadas alterações nos graus de extensão e flexão articulares, na rotação interna da tíbia, na amplitude de movimento articular ou de doença articular degenerativa (DAD durante o período de avaliação em ambos os grupos. Conclui-se que a ITR, associada à técnica de estabilização articular, não produz alterações em nenhuma das variáveis estudadas em cães, quando comparada à estabilização intra-articular, isoladamente.Clinical and radiographic changes associated with intercondylar notchplasty (IN after transection of the cranial cruciate ligament (CCL followed by a fascial strip reconstruction were studied in nine adult dogs. The right stifle was submitted to IN followed by fascial strip reconstruction of the CCL (GI while in the left IN was not performed (GC. Dogs were evaluated the day prior to surgery, on the immediate postoperative day and at 30, 90 and 180 days after surgery, time at which a subgroup of three dogs were euthanatized. Instability and lameness significantly decreased throughout the evaluation period, although instability was

Influence of Ionospheric Weather on GNSS Radio Occultation Signals

Science.gov (United States)

Yue, X.; Schreiner, W. S.; Pedatella, N. M.; Kuo, Y. H.

2016-12-01

Transient loss of lock (LOL) is one of the key space weather effects on the Global Navigation Satellite System (GNSS). Based on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Global Positioning System (GPS) radio occultation (RO) observations during 2007-2011, we have analyzed the signal cycle slip (CS) occurrence comprehensively and its correlation to the ionospheric weather phenomena such as sporadic E (Es), equatorial F region irregularity (EFI), and the ionospheric equatorial ionization anomaly (EIA). The high vertical resolution of RO observations enables us to distinguish the CS resulting from different ionospheric layers clearly on a global scale. In the E layer, the CS is dominated by the Es occurrence, while in the F layer, the CS is mainly related to the EIA and EFI at low and equatorial latitudes. In the polar region, the CS is primarily related to polar cap electron density gradients. The overall average CS (> 6 cycles) occurrence is 23% per occultation, with the E (50-150 km) and F (150-600 km) layers contributing 8.3% and 14.7%, respectively. Awareness of the effect of the ionospheric weather on the CS of the low-Earth-orbit (LEO)-based GNSS signal could be beneficial to a variety of applications, including the LEO-based GNSS data processing and the corresponding hardware/firmware design.

Insatisfação corporal, prática de dietas e comportamentos de risco para transtornos alimentares em mães residentes em Santos

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Fernanda Baeza Scagliusi

2012-01-01

Full Text Available OBJETIVO: Avaliar a insatisfação corporal, a prática de dietas e os comportamentos de risco para transtornos alimentares em uma amostra de mães residentes no município de Santos. MÉTODOS: Foi realizado um estudo transversal, de base populacional, com 453 mães de filhos com até 10 anos de idade. As mães responderam ao Teste de Atitudes Alimentares (EAT-26, à Escala de Figuras de Stunkard e a uma questão sobre a prática atual de dietas. RESULTADOS: Das mães, 29,9% apresentaram escore positivo para os comportamentos de risco para transtornos alimentares e 21,8% estavam fazendo dieta para emagrecer no momento da entrevista. No tocante à imagem corporal, 17,5% das mães estavam satisfeitas com o seu tamanho corporal, 71,5% gostariam de diminuir seu tamanho corporal e 11,0% gostariam de aumentá-lo. Os comportamentos de risco para transtornos alimentares foram mais frequentes nas mães insatisfeitas com seus tamanhos corporais (p < 0,0001. CONCLUSÃO: A maioria das mães investigadas estava insatisfeita com os seus tamanhos corporais. A frequência de mães que praticavam dietas ou tinham comportamentos de risco para transtornos alimentares foi similar ou superior aos demais estudos nacionais, conduzidos, em sua maioria, com populações consideradas de risco, como meninas adolescentes e jovens universitárias.

Lower hybrid parametric instabilities nonuniform pump waves and tokamak applications

International Nuclear Information System (INIS)

Berger, R.L.; Chen, L.; Kaw, P.K.; Perkins, F.W.

1976-11-01

Electrostatic lower hybrid ''pump'' waves often launched into tokamak plasmas by structures (e.g., waveguides) whose dimensions are considerably smaller than characteristic plasma sizes. Such waves propagate in well-defined resonance cones and give rise to parametric instabilities driven by electron E x B velocities. The finite size of the resonance cone region determines the threshold for both convective quasimode decay instabilities and absolute instabilities. The excitation of absolute instabilities depends on whether a travelling or standing wave pump model is used; travelling wave pumps require the daughter waves to have a definite frequency shift. Altogether, parametric instabilities driven by E x B velocities occur for threshold fields significantly below the threshold for filamentation instabilities driven by pondermotive forces. Applications to tokamak heating show that nonlinear effects set in when a certain power-per-wave-launching port is exceeded

Vascularização arterial e venosa do linfonodo poplíteo em cães

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Karina de Senna Villar

2009-08-01

Full Text Available O linfonodo poplíteo nos cães situa-se, à direita e à esquerda em um espaço designado fossa poplítea, no terço distal dos músculos bíceps femoral, lateralmente e semitendinoso, medialmente, projetando-se na altura da face caudal das articulações femoro tibial e femoro patelar (articulação do joelho. Neste estudo foram utilizados vinte e cinco cães, machos e fêmeas adultos, procedentes do canil municipal de Araçatuba, São Paulo, cujas capturas foram efetuadas pela defesa sanitária animal desta cidade. Os vasos arteriais destinados a esta estrutura derivam sempre, de ambos os lados, da artéria femoral caudal distal e variam de 10 a 1, com maior freqüência de 2 (7 vezes, 28% à direita e de 6 a 2 igualmente com maior freqüência de 2 (8 vezes, 32%. Tão logo tem-se ainda à direita 5 e 6 ramos (3 vezes, 12%, 1, 7 e 10 (1 vez, 4%. Relativamente às veias derivadas deste linfonodo, convergem sempre para a veia safena lateral, estes vasos oscilam entre 9 e 2, com maior freqüência de 3 (9 vezes, 3,6%, à direita e de 12 a 2, com maior freqüência de 3 (10 vezes, 40% à esquerda. Assim, os demais ramos oriundos da linfonodo poplíteo direito e que se inserem na veia supracitada são em número de 2 e 5 (5 vezes, 20%, 4 e 6 (2 vezes, 8% e 8 e 9 (1 vez, 4%. Não obstante, ao lado esquerdo verifica-se em número de 2 ramos (6 vezes, 24%, 4 (4 vezes, 16%, 6 (3 vezes, 12% e finalizando 9 e 12 ramos (1 vez, 4%. O tamanho do linfonodo poplíteo em cães soropositivos para Leishmaniose Visceral pode encontrar-se entre 7,8 x 3,8 x 6,1 a 50,0 x 20,7 x 28,5 , em mm, sendo a média 26,18 x 10,5 x 15,97 mm para o direito e 26,98 x 11,14 x 15,25 mm para o esquerdo (referente as medidas dorso-ventral, latero-lateral e crânio-caudal, respectivamente.

Sombras da Escuta - Guimarães Rosa criador de livros e textos

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Mônica Gama

2008-10-01

Full Text Available Nous essayerons ici une lecture de l'historicité de la pratique de lecture proposée par Guimarães Rosa, qui même en étant un auteur connu pour sa capacité fabulation, il est aussi remarquable par laisser apparaître dans sa fiction la préoccupation par l'importance de la matérialité du livre et avec les processus d’appréhension de la lecture.

Secondary instabilities of hypersonic stationary crossflow waves

Science.gov (United States)

Edelman, Joshua B.

A sharp, circular 7° half-angle cone was tested in the Boeing/AFOSR Mach-6 Quiet Tunnel at 6° angle of attack. Using a variety of roughness configurations, measurements were made using temperature-sensitive paint (TSP) and fast pressure sensors. High-frequency secondary instabilities of the stationary crossflow waves were detected near the aft end of the cone, from 110° to 163° from the windward ray. At least two frequency bands of the secondary instabilities were measured. The secondary instabilities have high coherence between upstream and downstream sensor pairs. In addition, the amplitudes of the instabilities increase with the addition of roughness elements near the nose of the cone. Two of the measured instabilities were captured over a range of axial Reynolds numbers of about 1 - 2 million, with amplitudes ranging from low to turbulent breakdown. For these instabilities, the wave speed and amplitude growth can be calculated. The wave speeds were all near the edge velocity. Measured growth before breakdown for the two instabilities are between e3 and e4 from background noise levels. The initial linear growth rates for the instabilities are near 50 /m. Simultaneous measurement of two frequency bands of the secondary instabilities was made during a single run. It was found that each mode was spatially confined within a small azimuthal region, and that the regions of peak amplitude for one mode correspond to regions of minimal amplitude for the other.

Simple lecture demonstrations of instability and self-organization

International Nuclear Information System (INIS)

Mayer, V V; Varaksina, E I; Saranin, V A

2014-01-01

A dielectric liquid layer with an electric field created inside it is proposed as a means for demonstrating the phenomenon of self-organization. The field is produced by the distributed charge transferred by a corona discharge from the tip to the liquid surface. The theory of the phenomenon is presented. An analogy with the Rayleigh – Taylor instability is drawn and a comparison with the Benard instability is given. The practicality of the method for both natural sciences and the humanities is discussed. (methodological notes)

Localized instabilities and spinodal decomposition in driven systems in the presence of elasticity

Science.gov (United States)

Meca, Esteban; Münch, Andreas; Wagner, Barbara

2018-01-01

We study numerically and analytically the instabilities associated with phase separation in a solid layer on which an external material flux is imposed. The first instability is localized within a boundary layer at the exposed free surface by a process akin to spinodal decomposition. In the limiting static case, when there is no material flux, the coherent spinodal decomposition is recovered. In the present problem, stability analysis of the time-dependent and nonuniform base states as well as numerical simulations of the full governing equations are used to establish the dependence of the wavelength and onset of the instability on parameter settings and its transient nature as the patterns eventually coarsen into a flat moving front. The second instability is related to the Mullins-Sekerka instability in the presence of elasticity and arises at the moving front between the two phases when the flux is reversed. Stability analyses of the full model and the corresponding sharp-interface model are carried out and compared. Our results demonstrate how interface and bulk instabilities can be analyzed within the same framework which allows us to identify and distinguish each of them clearly. The relevance for a detailed understanding of both instabilities and their interconnections in a realistic setting is demonstrated for a system of equations modeling the lithiation and delithiation processes within the context of lithium ion batteries.

Off-equatorial current-driven instabilities ahead of approaching dipolarization fronts

Science.gov (United States)

Zhang, Xu; Angelopoulos, V.; Pritchett, P. L.; Liu, Jiang

2017-05-01

Recent kinetic simulations have revealed that electromagnetic instabilities near the ion gyrofrequency and slightly away from the equatorial plane can be driven by a current parallel to the magnetic field prior to the arrival of dipolarization fronts. Such instabilities are important because of their potential contribution to global electromagnetic energy conversion near dipolarization fronts. Of the several instabilities that may be consistent with such waves, the most notable are the current-driven electromagnetic ion cyclotron instability and the current-driven kink-like instability. To confirm the existence and characteristics of these instabilities, we used observations by two Time History of Events and Macroscale Interactions during Substorms satellites, one near the neutral sheet observing dipolarization fronts and the other at the boundary layer observing precursor waves and currents. We found that such instabilities with monochromatic signatures are rare, but one of the few cases was selected for further study. Two different instabilities, one at about 0.3 Hz and the other at a much lower frequency, 0.02 Hz, were seen in the data from the off-equatorial spacecraft. A parallel current attributed to an electron beam coexisted with the waves. Our instability analysis attributes the higher-frequency instability to a current-driven ion cyclotron instability and the lower frequency instability to a kink-like instability. The current-driven kink-like instability we observed is consistent with the instabilities observed in the simulation. We suggest that the currents needed to excite these low-frequency instabilities are so intense that the associated electron beams are easily thermalized and hence difficult to observe.

Anomalous plasma transport due to electron temperature gradient instability

International Nuclear Information System (INIS)

Tokuda, Sinji; Ito, Hiroshi; Kamimura, Tetsuo.

1979-01-01

The collisionless drift wave instability driven by an electron temperature inhomogeneity (electron temperature gradient instability) and the enhanced transport processes associated with it are studied using a two-and-a-half dimensional particle simulation code. The simulation results show that quasilinear diffusion in phase space is an important mechanism for the saturation of the electron temperature gradient instability. Also, the instability yields particle fluxes toward the hot plasma regions. The heat conductivity of the electron temperature perpendicular to the magnetic field, T sub(e'), is not reduced by magnetic shear but remains high, whereas the heat conductivity of the parallel temperature, T sub(e''), is effectively reduced, and the instability stabilized. (author)

Ocorrência de protozoários e helmintos em amostras de fezes de cães e gatos da cidade de São Paulo

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Solange Maria Gennari

1999-01-01

Full Text Available Foram examinadas, pelo Laboratório de Doenças Parasitárias do Departamento de Medicina Veterinária Preventiva e Saúde Animal, da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, no período de janeiro de 1991 a janeiro de 1995, amostras de 353 cães e de 187 gatos, com idades variadas e de diferentes áreas da cidade de São Paulo. Os métodos de diagnóstico empregados foram: centrífugo-flutuação em solução de sacarose e centrífugo-sedimentação em água-éter. Aproximadamente 45,0% das amostras de cães examinadas (160 amostras apresentaram-se positivas e o percentual de ocorrência de parasitos, em relação ao total de amostras foi: Ancylostoma spp. 20,40; Toxocara canis 8,49; Giardia sp. 7,65; Cryptosporidium parvum 2,83; Cystoisospora spp. 2,55; Sarcocystis spp. 1,70; Hammondia heydorni 0,85; e Spirocerca lupi, Trichuris vulpis e Dipylidium caninum 0,28. Das 187 amostras recebidas, provenientes de gatos, somente oito eram negativas e observou-se a ocorrência (% de Cystoisospora spp. 38,5; Toxocara sp. 34,22; Giardia sp. 16,04; Cryptosporidium parvum 14,44; Ancylostoma spp. 13,37; Dipylidium caninum 10,69; Sarcocystis spp. 8,56; Physaloptera spp. 4,81; oocistos tipo "Hammondia-Toxoplasma" 1,60; Strongyloides stercoralis 1,60; e Platynosomum concinum 1,07. Em cães, as associações mais freqüentemente observadas foram: Ancylostoma spp. + T. canis em oito amostras e Ancylostoma spp. + Giardia sp. e Ancylostoma spp. + T. vulpis em cinco amostras. Em gatos, Toxocara sp. e Cystoisospora spp., encontrados em 24 amostras, e Toxocara sp. + Ancylostoma spp. em cinco amostras, foram as associações mais comumente observadas.

Expressão dos marcadores tumorais CD-34 e CASPASE-3 no carcinoma epidermóide de esôfago

OpenAIRE

Ferreira,Valério Alves; Czeczko,Nicolau Gregori; Ribas-Filho,Jurandir Marcondes; Malafaia,Osvaldo; Ribas,Carmen Austrália Paredes Marcondes; Gomes,Claudia Stein; Cunha,Regina Maria da; Cuenca,Ronaldo M.

2009-01-01

OBJETIVO: Analisar citofotometricamente a expressão do marcador de densidade microvascular CD-34 e de apoptose caspase-3 no carcinoma epidermóide de esôfago, e correlacionar os marcadores entre si. MÉTODOS: Análise imunoistoquímica de 29 peças cirúrgicas de carcinomas epidermóides de esôfago, baseada nos índices de marcagem dos anticorpos CD-34 e caspase-3, utilizando-se sistema de citofotometria computadorizada. Comparou-se a expressão quantitativa destes marcadores, a relação entre eles, a ...

Double layers above the aurora

International Nuclear Information System (INIS)

Temerin, M.; Mozer, F.S.

1987-01-01

Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial

Carcinoma de células fusiformes de esôfago: relato de caso e revisão da literatura

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Yanaga Ricardo Hideki

2003-01-01

Full Text Available Lesões malignas do esôfago, excluindo-se carcinomas escamocelulares e adenocarcinomas, são bastante incomuns. Os autores relatam um caso de carcinoma de células fusiformes de esôfago. É um tumor maligno raro caracterizado por volumosa massa lobulada no terço médio do esôfago, que causa relativamente pequena obstrução apesar do seu volume. Em seguida é apresentada revisão da literatura sobre o assunto.

New global electron density observations from GPS-RO in the D- and E-Region ionosphere

Science.gov (United States)

Wu, Dong L.

2018-06-01

A novel retrieval technique is developed for electron density (Ne) in the D- and E-region (80-120 km) using the high-quality 50-Hz GPS radio occultation (GPS-RO) phase measurements. The new algorithm assumes a slow, linear variation in the F-region background when the GPS-RO passes through the D- and E-region, and extracts the Ne profiles at 80-130 km from the phase advance signal caused by Ne. Unlike the conventional Abel function, the new approach produces a sharp Ne weighting function in the lower ionosphere, and the Ne retrievals are in good agreement with the IRI (International Reference Ionosphere) model in terms of monthly maps, zonal means and diurnal variations. The daytime GPS-RO Ne profiles can be well characterized by the α-Chapman function of three parameters (NmE, hmE and H), showing that the bottom of E-region is deepening and sharpening towards the summer pole. At high latitudes the monthly GPS-RO Ne maps at 80-120 km reveal clear enhancement in the auroral zones, more prominent at night, as a result of energetic electron precipitation (EEP) from the outer radiation belt. The D-/E-region auroral Ne is strongly correlated with Kp on a daily basis. The new Ne data allow further comprehensive analyses of the sporadic E (Es) phenomena in connection with the background Ne in the E-region. The layered (2-10 km) and fluctuated (Layer than Ne_Pert, are extracted with respect to the background Ne_Region on a profile-by-profile basis. The Ne_Layer component has a strong but highly-refined peak at ∼105 km, with an amplitude smaller than Ne_Region approximately by an order of magnitude. The Ne_Pert component, which was studied extensively in the past, is ∼2 orders of magnitude weaker than Ne_Layer. Both Ne_Layer and Ne_Pert are subject to significant diurnal and semidiurnal variations, showing downward progression with local time in amplitude. The 11-year solar cycle dominates the Ne interannual variations, showing larger Ne_Region and Ne_Layer but smaller

Helical instability in film blowing process: Analogy to buckling instability

Science.gov (United States)

Lee, Joo Sung; Kwon, Ilyoung; Jung, Hyun Wook; Hyun, Jae Chun

2017-12-01

The film blowing process is one of the most important polymer processing operations, widely used for producing bi-axially oriented film products in a single-step process. Among the instabilities observed in this film blowing process, i.e., draw resonance and helical motion occurring on the inflated film bubble, the helical instability is a unique phenomenon portraying the snake-like undulation motion of the bubble, having the period on the order of few seconds. This helical instability in the film blowing process is commonly found at the process conditions of a high blow-up ratio with too low a freezeline position and/or too high extrusion temperature. In this study, employing an analogy to the buckling instability for falling viscous threads, the compressive force caused by the pressure difference between inside and outside of the film bubble is introduced into the simulation model along with the scaling law derived from the force balance between viscous force and centripetal force of the film bubble. The simulation using this model reveals a close agreement with the experimental results of the film blowing process of polyethylene polymers such as low density polyethylene and linear low density polyethylene.

Initiation of genome instability and preneoplastic processes through loss of Fhit expression.

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Joshua C Saldivar

Full Text Available Genomic instability drives tumorigenesis, but how it is initiated in sporadic neoplasias is unknown. In early preneoplasias, alterations at chromosome fragile sites arise due to DNA replication stress. A frequent, perhaps earliest, genetic alteration in preneoplasias is deletion within the fragile FRA3B/FHIT locus, leading to loss of Fhit protein expression. Because common chromosome fragile sites are exquisitely sensitive to replication stress, it has been proposed that their clonal alterations in cancer cells are due to stress sensitivity rather than to a selective advantage imparted by loss of expression of fragile gene products. Here, we show in normal, transformed, and cancer-derived cell lines that Fhit-depletion causes replication stress-induced DNA double-strand breaks. Using DNA combing, we observed a defect in replication fork progression in Fhit-deficient cells that stemmed primarily from fork stalling and collapse. The likely mechanism for the role of Fhit in replication fork progression is through regulation of Thymidine kinase 1 expression and thymidine triphosphate pool levels; notably, restoration of nucleotide balance rescued DNA replication defects and suppressed DNA breakage in Fhit-deficient cells. Depletion of Fhit did not activate the DNA damage response nor cause cell cycle arrest, allowing continued cell proliferation and ongoing chromosomal instability. This finding was in accord with in vivo studies, as Fhit knockout mouse tissue showed no evidence of cell cycle arrest or senescence yet exhibited numerous somatic DNA copy number aberrations at replication stress-sensitive loci. Furthermore, cells established from Fhit knockout tissue showed rapid immortalization and selection of DNA deletions and amplifications, including amplification of the Mdm2 gene, suggesting that Fhit loss-induced genome instability facilitates transformation. We propose that loss of Fhit expression in precancerous lesions is the first step in the

Aspectos epidemiológicos, clínicos e anatomopatológicos da intoxicação por aceturato de diminazeno em cães

OpenAIRE

Flores, Mariana M.; Pereira, Paula R.; Mazzanti, Alexandre; Kommers, Glaucia D.; Fighera, Rafael A.

2014-01-01

Os aspectos epidemiológicos, clínicos e anatomopatológicos da intoxicação espontânea por aceturato de diminazeno foram estudados em 10 cães. Em todos os casos, os cães afetados demonstraram sinais de síndrome tálamo-cortical, principalmente alteração do nível de consciência, tetraparesia, rigidez extensora e crise convulsiva. Em alguns casos, os cães acometidos apresentaram sinais de síndrome cerebelar, como tremores musculares generalizados de alta frequência e baixa amplitude, e/ou de síndr...

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

Current Hypotheses on How Microsatellite Instability Leads to Enhanced Survival of Lynch Syndrome Patients

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Kristen M. Drescher

2010-01-01

Full Text Available High levels of microsatellite instability (MSI-high are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

Current hypotheses on how microsatellite instability leads to enhanced survival of Lynch Syndrome patients.

Science.gov (United States)

Drescher, Kristen M; Sharma, Poonam; Lynch, Henry T

2010-01-01

High levels of microsatellite instability (MSI-high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

Electron temperature gradient driven instability in the tokamak boundary plasma

International Nuclear Information System (INIS)

Xu, X.Q.; Rosenbluth, M.N.; Diamond, P.H.

1992-01-01

A general method is developed for calculating boundary plasma fluctuations across a magnetic separatrix in a tokamak with a divertor or a limiter. The slab model, which assumes a periodic plasma in the edge reaching the divertor or limiter plate in the scrape-off layer(SOL), should provide a good estimate, if the radial extent of the fluctuation quantities across the separatrix to the edge is small compared to that given by finite particle banana orbit. The Laplace transform is used for solving the initial value problem. The electron temperature gradient(ETG) driven instability is found to grow like t -1/2 e γmt

Expressão de p53, p16 E COX-2 em carcinoma escamoso de esôfago e associação histopatológica

OpenAIRE

Felin,Izabella Paz Danezi; Grivicich,Ivana; Felin,Carlos Roberto; Regner,Andrea; Rocha,Adriana Brondani da

2008-01-01

RACIONAL: O câncer de esôfago representa cerca de 2% dos tumores malignos e a terceira causa mais comum de câncer do trato gastrointestinal. A associação do prognóstico do câncer de esôfago com alguns marcadores imunoistoquímicos, como as proteínas p53, p16 e a ciclooxigenase 2 (COX-2) tem sido relatada. A detecção de marcadores moleculares através de imunoistoquímica pode ser utilizada para avaliação prognóstica. OBJETIVOS: Investigar a associação entre a expressão das proteínas p53, p16 e a...

On the existence of hydrodynamic instability in single diffusive ...

Indian Academy of Sciences (India)

bottom heavy systems with permeable boundaries. A K GUPTA1, ... Abstract. We utilize the reformulated equations of the classical theory, as derived by ... of gravity-dominated thermal instability in a horizontal liquid layer heated underside (or.

Efeitos colaterais do uso da ribavirina, prednisona e DMSO em cães naturalmente infectados pelo vírus da cinomose

Directory of Open Access Journals (Sweden)

Simone H. Mangia

2014-05-01

Full Text Available O estudo tem o objetivo de identificar efeitos indesejáveis da ribavirina, prednisona e DMSO em cães naturalmente infectados com o vírus da cinomose. Foram utilizados 60 cães apresentando quadro neurológico da cinomose com evolução de 10 dias. Os animais foram internados e receberam tratamento de suporte; foram avaliados diariamente e realizados hemograma, dosagem bioquímica e exame de urina tipo I. Os grupos 1 e 2 foram tratados com ribavirina e sua associação com DMSO; os grupos 3 e 4 com DMSO e prednisona e o grupos 5 com ribavirina e prednisona e o grupo 6 com ribavirina, prednisona e DMSO. Os animais foram anestesiados para a colheita de líquor, medula óssea e sangue, antes do tratamento para diagnóstico através da RT-PCR. As amostras negativas foram analisadas pela técnica de hn-PCR. Todos os animais apresentaram resultado positivo em pelo menos uma das duas reações. O efeito adverso da ribavirina e a sua associação com a prednisona foi a anemia hemolítica, que foi confirmada pela observação de bilirrubina na urina apenas dos cães tratados com ribavirina.

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

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)

Summary of microsatellite instability test results from laboratories participating in proficiency surveys: proficiency survey results from 2005 to 2012.

Science.gov (United States)

Boyle, Theresa A; Bridge, Julia A; Sabatini, Linda M; Nowak, Jan A; Vasalos, Patricia; Jennings, Lawrence J; Halling, Kevin C

2014-03-01

The College of American Pathologists surveys are the largest laboratory peer comparison programs in the world. These programs allow laboratories to regularly evaluate their performance and improve the accuracy of the patient test results they provide. Proficiency testing is offered twice a year to laboratories performing microsatellite instability testing. These surveys are designed to emulate clinical practice, and some surveys have more challenging cases to encourage the refinement of laboratory practices. This report summarizes the results and trends in microsatellite instability proficiency testing from participating laboratories from the inception of the program in 2005 through 2012. We compiled and analyzed data for 16 surveys of microsatellite instability proficiency testing during 2005 to 2012. The number of laboratories participating in the microsatellite instability survey has more than doubled from 42 to 104 during the 8 years analyzed. An average of 95.4% of the laboratories correctly classified each of the survey test samples from the 2005A through 2012B proficiency challenges. In the 2011B survey, a lower percentage of laboratories (78.4%) correctly classified the specimen, possibly because of overlooking subtle changes of microsatellite instability and/or failing to enrich the tumor content of the specimen to meet the limit of detection of their assay. In general, laboratories performed well in microsatellite instability testing. This testing will continue to be important in screening patients with colorectal and other cancers for Lynch syndrome and guiding the management of patients with sporadic colorectal cancer.

Short telomeres: from dyskeratosis congenita to sporadic aplastic anemia and malignancy.

Science.gov (United States)

Gramatges, Maria M; Bertuch, Alison A

2013-12-01

Telomeres are DNA-protein structures that form a protective cap on chromosome ends. As such, they prevent the natural ends of linear chromosomes from being subjected to DNA repair activities that would result in telomere fusion, degradation, or recombination. Both the DNA and protein components of the telomere are required for this essential function, because insufficient telomeric DNA length, loss of the terminal telomeric DNA structure, or deficiency of key telomere-associated factors may elicit a DNA damage response and result in cellular senescence or apoptosis. In the setting of failed checkpoint mechanisms, such DNA-protein defects can also lead to genomic instability through telomere fusions or recombination. Thus, as shown in both model systems and in humans, defects in telomere biology are implicated in cellular and organismal aging as well as in tumorigenesis. Bone marrow failure and malignancy are 2 life-threatening disease manifestations in the inherited telomere biology disorder dyskeratosis congenita. We provide an overview of basic telomere structure and maintenance. We outline the telomere biology defects observed in dyskeratosis congenita, focusing on recent discoveries in this field. Last, we review the evidence of how telomere biology may impact sporadic aplastic anemia and the risk for various cancers. Copyright © 2013 Mosby, Inc. All rights reserved.

Alimentação natural para cães e gatos Natural foods for dogs and cats

Directory of Open Access Journals (Sweden)

Flávia Maria de Oliveira Borges Saad

2010-07-01

Full Text Available Um grande "recall" de alimentos PET ocorrido em 2007 nos Estados Unidos devido à contaminação fraudulenta por melamina, foi ponto chave para o interesse atual sobre novas alternativas alimentares para cães e gatos, a parte a rações comerciais convencionais. A procura por novidades no setor pet food, combinada com uma tendência permanente de humanização na indústria pet, acarreta aumento da procura por alimentos diferenciados para animais de estimação. Dentre os tipos de dietas alternativas encontram-se as dietas naturais, as orgânicas, entre outras. Entretanto, não existem orientações específicas para a fabricação e rotulagem de produtos que contenham carne crua, o que poderia ocasionar desequilíbrios e risco à saúde de proprietários que fornecem esse tipo de alimentação a seus animais de estimação. Por outro lado, os alimentos naturais podem ser constituídos por ingredientes destinados à alimentação humana, buscando uma aproximação da composição dos alimentos que os animais (cães e gatos obtinham da natureza, com maior contribuição dos nutrientes, como proteína e lipídeos, a esses animais. Os efeitos que estes podem causar em animais de estimação são diversos, desde parâmetros relacionados ao surgimento de doenças, por afetarem o metabolismo de proteínas, carboidratos e/ou lipídeos, até fatores ligados à qualidade fecal e, mais além, na questão da segurança alimentar. Assim, os alimentos comerciais naturais são nichos de mercado potenciais e surgiram para atender a demanda de proprietários cada vez mais exigentes com relação à alimentação e nutrição de seus animais de companhia. Entretanto, é importante uma avaliação criteriosa e científica deste nicho de mercado, buscando estabelecer suas vantagens e desvantagens sob o ponto de vista nutricional e de segurança alimentar.A major pet food recall occurred in 2007 in the United States due to fraudulent contamination with melamine

Monitoração hemodinâmica e da oxigenação tecidual minimamente invasiva em cães

OpenAIRE

Gehrcke, Martielo Ivan

2014-01-01

Devido à importância da monitoração hemodinâmica e da oxigenação tecidual na anestesiologia e em pacientes críticos, buscam-se métodos minimamente invasivos e acurados para monitoração do débito cardíaco e da oxigenação tecidual. Esta tese apresenta quatro estudos que visam a monitoração hemodinâmica e da oxigenação tecidual em cães. O primeiro, trata-se de uma revisão sobre os diferentes métodos para monitoração do débito cardíaco em cães, ressaltando a importância de se utilizar técnicas mi...

Prevalência de HIV em gestantes e transmissão vertical segundo perfil socioeconômico, Vitória, ES

Directory of Open Access Journals (Sweden)

Anne Caroline Barbosa Cerqueira Vieira

2011-08-01

Full Text Available OBJETIVO: Descrever a prevalência de infecção por HIV em gestantes e a taxa de transmissão vertical, segundo o perfil socioeconômico dos bairros de residência das mães. MÉTODOS: Estudo ecológico exploratório utilizando a base de dados do Sistema de Informação de Agravos de Notificação de gestantes HIV-positivas e aids em crianças notificadas entre 2000 e 2006 em Vitória, ES. Para análise das informações socioeconômicas foi utilizado o Índice de Qualidade Urbana. A prevalência de HIV em gestantes e a taxa de transmissão vertical foram calculadas. A distribuição espacial dos casos foi realizada no programa Terraview 3.2.0. Para verificar a associação entre a qualidade urbana e a prevalência de HIV em gestantes utilizou-se o modelo de regressão de Poisson. RESULTADOS: Um total de 137 gestantes e 14 crianças infectadas por transmissão vertical foi notificado no período. Sete crianças correspondiam a mães HIV-positivas sem notificação de caso no período analisado. A prevalência de infecção em gestantes no período foi de 0,44% e a taxa de transmissão vertical foi de 9,7%. CONCLUSÕES: A prevalência de infecção por HIV em gestantes e a transmissão vertical associam-se à qualidade urbana do bairro de residência, indicando que os bairros com menor qualidade urbana devem ser priorizados quanto às ações para redução da transmissão vertical.

Ventos em supergigantes B[e] das nuvens de Magalhães e da Galáxia

Science.gov (United States)

de Araújo, F. X.; Pilling, D. A.; Pereira, C. B.; Fernandes, M. B.

2003-08-01

As Supergigantes B[e] apresentam as seguintes características: (i) alta luminosidade; (ii) espectro típico de estrelas de tipo B; (iii) linhas permitidas e proibidas em emissão de metais de baixa ionização, especialmente FeII; (iv) linhas de Balmer, e por vêzes também dos ions HeI e FeII, com perfis tipo P Cygni indicativos de altas taxas de perda de massa. Atualmente estamos desenvolvendo um projeto que visa comparar as propriedades fisicas (principalmente e v¥) dos ventos destes objetos nas Nuvens de Magalhães e na Galaxia. O objetivo é estudar a influência da metalicidade. No presente painel apresentamos uma determinação das velocidades terminais de 11 estrelas, sendo 4 na GNM (Hen S111, 66, R126 e Hen S93), 4 na PNM (Hen S18, S23, S65 e R4) e 3 na Galaxia (CPD-529243, MWC 300 e GG Car). Nossos dados são espectros de alta resolução obtidos no telescópio 1.52m do ESO com o espectrógrafo FEROS. Para determinar as velocidades terminais usamos as linhas Hd e HeI 3888 Å cujas componentes em absorção costumam estar livres de "blends" e estruturas. Nossos resultados sugerem que as velocidades de expansão na GNM são maiores (ainda que apenas ligeiramente) do que aquelas da PNM, como esperado. No entanto, os objetos da Galaxia não parecem seguir a mesma tendência.

Some aspects of metallic ion chemistry and dynamics in the mesosphere and thermosphere

Science.gov (United States)

Mathews, J. D.

1987-01-01

The relationship between the formation of sporadic layers of metallic ion and the dumping of these ions into the upper mesosphere is discussed in terms of the tidal wind, classical (i.e., windshear) and other more complex, perhaps highly nonlinear layer formation mechanisms, and a possible circulation mechanism for these ions. Optical, incoherent scatter radar, rocket, and satellite derived evidence for various layer formation mechanisms and for the metallic ion circulation system is reviewed. The results of simple one dimensional numerical model calculations of sporadic E and intermediate layer formation are presented along with suggestions for more advanced models of intense or blanketing sporadic E. The flux of metallic ions dumped by the tidal wind system into the mesosphere is estimated and compared with estimates of total particle flux of meteoric origin. Possible effects of the metallic ion flux and of meteoric dust on D region ion chemistry are discussed.

Poliartrite em cães - 27 casos (2007-2013

Directory of Open Access Journals (Sweden)

Rafael Oliveira Chaves

2015-03-01

Full Text Available O objetivo deste estudo foi identificar cães com poliartrite e obter informações a respeito da idade, sexo, raça, peso corporal, queixa principal, alterações no exame físico, do líquido sinovial e resposta à terapia instituída. Os cães sem raça definida e acima de seis anos de idade foram os mais acometidos e o principal sinal clínico observado foi dificuldade de locomoção (71,5%, seguido de dor articular (52,3% e claudicação (33,3%. Febre e inapetência foram observadas em cinco (18,5% e quatro cães (14,8%, respectivamente. As principais alterações hematológicas encontradas foram anemia não regenerativa (29,6%, leucocitose (26% e trombocitopenia (18,5%. Os resultados da bioquímica sérica foram considerados normais em sete de 27 cães (26% e as principais alterações foram hiperproteinemia (55,5% e hipoalbuminemia (37%. A inflamação sinovial foi considerada acentuada em 17 cães (77,5%, sendo os neutrófilos predominantes em 52,4% dos casos (n=14. O tratamento foi realizado em 18 cães com doses imunossupressoras de corticosteroides, sendo efetivo em 89% dos casos

A Casa Grande de Romarigães, um legado arquitectónico e literário de Aquilino Ribeiro

Directory of Open Access Journals (Sweden)

Maria Ribeiro Machado Pedroso de Lima

2017-12-01

Full Text Available A Casa Grande de Romarigães terá servido de cenário literário a uma das mais simbólicas obras do escritor Aquilino Ribeiro: A casa grande de Romarigães. Sua estrutura arquitectónica foi classificada como Imóvel de Interesse Público em 1986, atribuição que ainda não derivou em nenhum estudo rigoroso sobre a sua evolução morfológica. Com base nas constantes descrições na obra de Aquilino Ribeiro, e do seu confronto com a documentação histórica entretanto encontrada (escrita e gráfica, em grande parte inédita, este trabalho de investigação propõe o desenho da evolução morfológica da casa ao longo dos tempos, bem como a enunciação da influência deste solar para a organização social, cultural e económica da aldeia de Romarigães.

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.

Sintomas depressivos e ansiosos em mães de recém-nascidos com e sem malformações Depressive and anxious symptoms in mothers of newborns with and without malformations

Directory of Open Access Journals (Sweden)

Gimol Benzaquen Perosa

2009-09-01

Full Text Available OBJETIVO: comparar as condições emocionais de mães cujos filhos nascem com malformações visíveis (Grupo M com as das mães de crianças eutróficas (Grupo E logo após o nascimento. MÉTODO: foram avaliados os sintomas de ansiedade e depressão de 22 mães de cada grupo por meio do Inventário de Depressão de Beck (BDI e do Inventário de Ansiedade Traço-Estado (IDATE. Foram excluídas as mães portadoras de deficiência sensorial incapacitante, HIV, distúrbios psiquiátricos e síndromes genéticas. Os dados foram complementados com consultas a prontuários médicos da criança e da mãe. Para análise comparativa entre as medianas dos grupos foi utilizado o teste não-paramétrico U de Mann-Whitney; para amostras independentes e para os escores indicativos de sintomas clínicos, o teste exato de Fisher e o teste do χ2. RESULTADOS: houve diferenças significativas nas medianas dos escores das três subescalas (ansiedade-traço, ansiedade-estado e disforia/depressão entre os dois grupos de mães. Houve uma porcentagem significativamente maior de mães do Grupo M com escores indicativos de sinais clínicos para depressão ou ansiedade no pós-parto imediato e, para ambos os quadros, quando comparadas com mães do Grupo E. Os resultados podem ser decorrentes de traços de personalidade materna, visto que os índices de ansiedade-traço eram significativamente maiores nas mães de crianças malformadas, mas especialmente pelo estado da criança, seu encaminhamento para a UTI e sua condição de vida futura. CONCLUSÕES: a porcentagem de mães de recém-nascidos com malformações visíveis que apresentou escores indicativos de sinais clínicos para ansiedade, depressão e ambos sugerem a necessidade de suporte, individual ou em grupo.PURPOSE: the main goal of this study is to evaluate the emotional conditions among mothers of newborns with visible malformation (Group M and mothers of eutrophic newborns (Group E soon after birth. METHODS

Relações entre a resposta de ansiedade de pais e mães e a reposta de ansiedade de seus filhos

OpenAIRE

Nascimento,Célia Regina Rangel

2001-01-01

Este estudo investigou a relação entre as respostas de ansiedade de pais e as respostas de ansiedade de seus filhos, considerando a possibilidade de diferenças de gênero e faixa etária dos filhos nesta relação. Participaram deste estudo 50 crianças e 49 adolescentes, de ambos os sexos, alunos de escolas estaduais de Porto Alegre, e seus pais e mães. Para avaliar a ansiedade das crianças, foi aplicado o Inventário de Ansiedade-traço-Estado para Crianças (IDATE-C). Nos adolescentes, nos pais e ...

Electron surfing acceleration by the electron two-stream instability in a weak magnetic field

International Nuclear Information System (INIS)

Dieckmann, M E; Shukla, P K

2006-01-01

The thermalization of relativistically flowing colliding plasmas is not well understood. The transition layer, in which both plasmas interact and thermalize, is wide and highly structured and the instabilities in this layer may yield non-thermal particle distributions and shock-less energy dissipation. The objective in this work is to explore the ability of an electron two-stream instability for thermalizing a plasma beam that moves at the mildly relativistic speed 0.3c through weakly magnetized plasma and to identify the resulting particle distributions. It is demonstrated here with particle-in-cell simulations that the electron two-stream instability leads to waves that propagate within a wide angular range relative to the flow velocity. The waves are thus not planar, as required for efficient electron surfing acceleration (ESA). The short lifetime of the waves implies, however, only weak modifications of the ESA by the oblique modes, since the waves are sufficiently homogeneous. The ion (proton) beams are not modulated, which would be required to extract some of their energy. The instability can thus heat the electrons significantly, but it fails to accelerate them to relativistic energies and it cannot form a shock layer by thermalizing the protons, at least not for the system and the resolved timescales considered here

Electron surfing acceleration by the electron two-stream instability in a weak magnetic field

Energy Technology Data Exchange (ETDEWEB)

Dieckmann, M E; Shukla, P K [Institut fuer Theoretische Physik IV, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2006-10-15

The thermalization of relativistically flowing colliding plasmas is not well understood. The transition layer, in which both plasmas interact and thermalize, is wide and highly structured and the instabilities in this layer may yield non-thermal particle distributions and shock-less energy dissipation. The objective in this work is to explore the ability of an electron two-stream instability for thermalizing a plasma beam that moves at the mildly relativistic speed 0.3c through weakly magnetized plasma and to identify the resulting particle distributions. It is demonstrated here with particle-in-cell simulations that the electron two-stream instability leads to waves that propagate within a wide angular range relative to the flow velocity. The waves are thus not planar, as required for efficient electron surfing acceleration (ESA). The short lifetime of the waves implies, however, only weak modifications of the ESA by the oblique modes, since the waves are sufficiently homogeneous. The ion (proton) beams are not modulated, which would be required to extract some of their energy. The instability can thus heat the electrons significantly, but it fails to accelerate them to relativistic energies and it cannot form a shock layer by thermalizing the protons, at least not for the system and the resolved timescales considered here.

Mediações poéticas sobre o corpo gordo de Elisa Queiroz e Fernanda Magalhães

Directory of Open Access Journals (Sweden)

Júlia Almeida de Mello

2017-05-01

Full Text Available O presente artigo traz uma interseção entre o projeto poético das artistas brasileiras Elisa Queiroz e Fernanda Magalhães. Ambas possuem produções autorreferenciais que permitem reflexões acerca da corpulência. As artistas provocam os espectadores através de trabalhos feitos em diferentes suportes e superfícies e parecem tensionar as normas e padrões estéticos vigentes na sociedade contemporânea. Para a leitura dos projetos, são considerados os escritos de autores como Donna Haraway (2009, Chantal Mouffe (2007, Whitney Chadwick (2001 e André Rouillé (2005, que tratam de gênero, política e práticas artísticas como política. Os resultados revelam a possibilidade em realizar uma conversa entre as obras das artistas, partindo dos seus corpos para alinhavar discursos concernentes a identidade, gênero e poder. ABSTRACT This article provides an intersection between the poetic project from Brazilian artists Elisa Queiroz and Fernanda Magalhães. Both have self-referential productions that allow reflections about corpulence and seem to tighten standards and aesthetic standards prevailing in contemporary society. For the reading of the projects are considered the writings of authors such as Donna Haraway (2009, Chantal Mouffe (2007, Whitney Chadwick (2001 and Andre Rouillé (2005, dealing with gender, political and artistic practices as politics. The results reveal the possibility to hold a conversation between the artists works starting from their bodies to tack speeches concerning identity, gender and power. KEYWORDS Art, Elisa Queiroz, Fernanda Magalhães, body, gender.

Rotating magnetic shallow water waves and instabilities in a sphere

Science.gov (United States)

Márquez-Artavia, X.; Jones, C. A.; Tobias, S. M.

2017-07-01

Waves in a thin layer on a rotating sphere are studied. The effect of a toroidal magnetic field is considered, using the shallow water ideal MHD equations. The work is motivated by suggestions that there is a stably stratified layer below the Earth's core mantle boundary, and the existence of stable layers in stellar tachoclines. With an azimuthal background field known as the Malkus field, ?, ? being the co-latitude, a non-diffusive instability is found with azimuthal wavenumber ?. A necessary condition for instability is that the Alfvén speed exceeds ? where ? is the rotation rate and ? the sphere radius. Magneto-inertial gravity waves propagating westward and eastward occur, and become equatorially trapped when the field is strong. Magneto-Kelvin waves propagate eastward at low field strength, but a new westward propagating Kelvin wave is found when the field is strong. Fast magnetic Rossby waves travel westward, whilst the slow magnetic Rossby waves generally travel eastward, except for some ? modes at large field strength. An exceptional very slow westward ? magnetic Rossby wave mode occurs at all field strengths. The current-driven instability occurs for ? when the slow and fast magnetic Rossby waves interact. With strong field the magnetic Rossby waves become trapped at the pole. An asymptotic analysis giving the wave speed and wave form in terms of elementary functions is possible both in polar trapped and equatorially trapped cases.

Crown sealing and buckling instability during water entry of spheres

KAUST Repository

Marston, J. O.

2016-04-05

We present new observations from an experimental investigation of the classical problem of the crown splash and sealing phenomena observed during the impact of spheres onto quiescent liquid pools. In the experiments, a 6 m tall vacuum chamber was used to provide the required ambient conditions from atmospheric pressure down to of an atmosphere, whilst high-speed videography was exploited to focus primarily on the above-surface crown formation and ensuing dynamics, paying particular attention to the moments just prior to the surface seal. In doing so, we have observed a buckling-type azimuthal instability of the crown. This instability is characterised by vertical striations along the crown, between which thin films form that are more susceptible to the air flow and thus are drawn into the closing cavity, where they atomize to form a fine spray within the cavity. To elucidate to the primary mechanisms and forces at play, we varied the sphere diameter, liquid properties and ambient pressure. Furthermore, a comparison between the entry of room-temperature spheres, where the contact line pins around the equator, and Leidenfrost spheres (i.e. an immersed superheated sphere encompassed by a vapour layer), where there is no contact line, indicates that the buckling instability appears in all crown sealing events, but is intensified by the presence of a pinned contact line. © 2016 Cambridge University Press.

Transition due to streamwise streaks in a supersonic flat plate boundary layer

Science.gov (United States)

Paredes, Pedro; Choudhari, Meelan M.; Li, Fei

2016-12-01

Transition induced by stationary streaks undergoing transient growth in a supersonic flat plate boundary layer flow is studied using numerical computations. While the possibility of strong transient growth of small-amplitude stationary perturbations in supersonic boundary layer flows has been demonstrated in previous works, its relation to laminar-turbulent transition cannot be established within the framework of linear disturbances. Therefore, this paper investigates the nonlinear evolution of initially linear optimal disturbances that evolve into finite amplitude streaks in the downstream region, and then studies the modal instability of those streaks as a likely cause for the onset of bypass transition. The nonmodal evolution of linearly optimal stationary perturbations in a supersonic, Mach 3 flat plate boundary layer is computed via the nonlinear plane-marching parabolized stability equations (PSE) for stationary perturbations, or equivalently, the perturbation form of parabolized Navier-Stokes equations. To assess the effect of the nonlinear finite-amplitude streaks on transition, the linear form of plane-marching PSE is used to investigate the instability of the boundary layer flow modified by the spanwise periodic streaks. The onset of transition is estimated using an N -factor criterion based on modal amplification of the secondary instabilities of the streaks. In the absence of transient growth disturbances, first mode instabilities in a Mach 3, zero pressure gradient boundary layer reach N =10 at Rex≈107 . However, secondary instability modes of the stationary streaks undergoing transient growth are able to achieve the same N -factor at Rex<2 ×106 when the initial streak amplitude is sufficiently large. In contrast to the streak instabilities in incompressible flows, subharmonic instability modes with twice the fundamental spanwise wavelength of the streaks are found to have higher amplification ratios than the streak instabilities at fundamental

Identificação das competências de Liderança associadas ao comando dos Oficiais subalternos e capitães de Infantaria

OpenAIRE

Lopes, Luís

2015-01-01

O presente trabalho é subordinado ao tema “Identificação das competências de liderança associadas ao comando dos Oficiais Subalternos e Capitães de Infantaria.”, tem como objetivo identificar, analisar e interrelacionar os comportamentos de liderança percecionados pelos subordinados aos Oficiais Subalternos e Capitães de Infantaria nas suas tarefas diárias de comando e de que maneira os Oficiais conseguem obter dos seus homens desempenh...

Electromagnetic internal gravity waves in the Earth's ionospheric E-layer

International Nuclear Information System (INIS)

Kaladze, T.D.; Tsamalashvili, L.V.; Kaladze, D.T.

2011-01-01

In the Earth's ionospheric E-layer existence of the new waves connecting with the electromagnetic nature of internal gravity waves is shown. They represent the mixture of the ordinary internal gravity waves and the new type of dispersive Alfven waves. -- Highlights: ► Existence of electromagnetic internal gravity waves in the ionospheric E-layer is shown. ► Electromagnetic nature of internal gravity waves is described. ► Appearance of the new dispersive Alfven waves is shown.

Long-wave theory for a new convective instability with exponential growth normal to the wall.

Science.gov (United States)

Healey, J J

2005-05-15

A linear stability theory is presented for the boundary-layer flow produced by an infinite disc rotating at constant angular velocity in otherwise undisturbed fluid. The theory is developed in the limit of long waves and when the effects of viscosity on the waves can be neglected. This is the parameter regime recently identified by the author in a numerical stability investigation where a curious new type of instability was found in which disturbances propagate and grow exponentially in the direction normal to the disc, (i.e. the growth takes place in a region of zero mean shear). The theory describes the mechanisms controlling the instability, the role and location of critical points, and presents a saddle-point analysis describing the large-time evolution of a wave packet in frames of reference moving normal to the disc. The theory also shows that the previously obtained numerical solutions for numerically large wavelengths do indeed lie in the asymptotic long-wave regime, and so the behaviour and mechanisms described here may apply to a number of cross-flow instability problems.

DESENVOLVIMENTO DE MUDAS DE ALFACE EM DIFERENTES SUBSTRATOS E CONCENTRAÇÕES

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Mário Pechara Jaeggi

2017-04-01

Full Text Available Objetivou-se com este trabalho avaliar o desempenho de diferentes substratos e concentrações, no desenvolvimento de cultivares de alface. O experimento foi conduzido em casa de vegetação, localizada no setor de Agroecologia do Instituto Federal do Espírito Santo Campus de Alegre, ES. O delineamento utilizado foi em blocos casualizados disposto em um esquema fatorial 4x3x2, sendo quatro tipos substratos (S1: Plantmax®; S2: composto orgânico; S3: húmus de minhoca; S4: borra de cana-de-açúcar, três concentrações (100%, 75% e 50% e duas cultivares de alface. As variáveis avaliadas foram: massa fresca da parte aérea, massa fresca toal e altura da parte aérea. As mudas foram avaliadas ao 21° dia após semeio. Os resultados demostraram que substratos orgânicos se mostraram eficazes para o desenvolvimento das cultivares de alface, os quais podem ser utilizados em diferentes concentrações em substituição ao substrato comercial.

Genomic instability and radiation effects

International Nuclear Information System (INIS)

Christian Streffer

2007-01-01

Complete text of publication follows. Cancer, genetic mutations and developmental abnormalities are apparently associated with an increased genomic instability. Such phenomena have been frequently shown in human cancer cells in vitro and in situ. It is also well-known that individuals with a genetic predisposition for cancer proneness, such as ataxia telangiectesia, Fanconi anaemia etc. demonstrate a general high genomic instability e.g. in peripheral lymphocytes before a cancer has developed. Analogous data have been found in mice which develop a specific congenital malformation which has a genetic background. Under these aspects it is of high interest that ionising radiation can increase the genomic instability of mammalian cells after exposures in vitro an in vivo. This phenomenon is expressed 20 to 40 cell cycles after the exposure e.g. by de novo chromosomal aberrations. Such effects have been observed with high and low LET radiation, high LET radiation is more efficient. With low LET radiation a good dose response is observed in the dose range 0.2 to 2.0 Gy, Recently it has been reported that senescence and genomic instability was induced in human fibroblasts after 1 mGy carbon ions (1 in 18 cells are hit), apparently bystander effects also occurred under these conditions. The instability has been shown with DNA damage, chromosomal aberrations, gene mutation and cell death. It is also transferred to the next generation of mice with respect to gene mutations, chromosomal aberrations and congenital malformations. Several mechanisms have been discussed. The involvement of telomeres has gained interest. Genomic instability seems to be induced by a general lesion to the whole genome. The transmission of one chromosome from an irradiated cell to an non-irradiated cell leads to genomic instability in the untreated cells. Genomic instability increases mutation rates in the affected cells in general. As radiation late effects (cancer, gene mutations and congenital

Generation of an integration-free induced pluripotent stem cell line (CSC-43 from a patient with sporadic Parkinson's disease

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Ana Marote

2018-03-01

Full Text Available An induced pluripotent stem cell (iPSC line was generated from a 36-year-old patient with sporadic Parkinson's disease (PD. Skin fibroblasts were reprogrammed using the non-integrating Sendai virus technology to deliver OCT3/4, SOX2, c-MYC and KLF4 factors. The generated cell line (CSC-43 exhibits expression of common pluripotency markers, in vitro differentiation into three germ layers and normal karyotype. This iPSC line can be used to study the mechanisms underlying the development of PD.

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

A atuação de Cacilda Guimarães: lugares e fazeres (Santa Catarina, 1907-1931 - The actions of Cacilda Guimarães: places and actions (Santa Catarina, 1907-1931

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Elizabeth Martins

2012-03-01

Full Text Available O estudo pretende dar visibilidade à trajetória profissional da professora paulista Cacilda Guimarães, que participou de momentos importantes da educação catarinense, particularmente da reforma da instrução pública de 1911. Apesar da singular participação, é notória a ausência de referências à sua atuação, creditada à falta de fontes e registros que permitam a constituição de uma base empírica capaz de subsidiar as reflexões e análises. A investigação foi conduzida de modo a localizar documentos que se reportavam à Cacilda Guimarães, a seus lugares de formação e primeiros contatos com a realidade educacional catarinense, assim como por seus fazeres, especialmente aqueles relacionados à reforma da instrução pública no Estado. Buscou-se, ainda, relacionar suas experiências ao cenário educativo, marcado pela necessidade de organização de um novo projeto, gestado no interior da reforma da instrução pública.Palavras-chave: memória docente, trajetória profissional, Cacilda Guimarães, história da educação de Santa Catarina. THE ACTIONS OF CACILDA GUIMARÃES: PLACES AND ACTIONS (SANTA CATARINA, 1907-1931AbstractThe aim of this study is to give visibility to the professional trajectory of the teacher Cacilda Guimarães, who participated in important moments in the history of education in the state of Santa Catarina, Brazil, particularly the public education reform of 1911. In spite of the unique role she played in those developments, there are no references to her activities, supposedly due to a lack of sources or records that would allow the establishment of an empirical basis to support reflection and analysis. This investigation was conducted in order to locate documents referring to Cacilda Guimarães, the educational institutions she attebded and her first contacts with the educational reality of Santa Catarina, as well as her activities, particularly those related to the public education reform in that

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.

Cervical dystonia: about familial and sporadic cases in 88 patients

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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.

Levantamento de leishmaniose visceral em cães de Santa Maria e municípios próximos, Estado do Rio Grande do Sul

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Marcondes Carlos Brisola

2003-01-01

Full Text Available A partir de relato de diagnóstico de leishmaniose visceral em cinco cães dos municípios de Santa Maria, Itaara e Júlio de Castilhos, no centro do Estado do Rio Grande do Sul, foi realizado levantamento sorológico através de teste de imunofluorescência indireta em sangue obtido em papel de filtro de 40 cães de Santa Maria, 20 de Itaara e 11 de Júlio de Castilhos, em geral relacionados aos cinco cães considerados como positivos. Além destes, foi também examinado o sangue de 44 cães vadios de Júlio de Castilhos, 68 de Cachoeira do Sul e 20 de Caçapava do Sul. Soros fracamente reagentes com títulos < 1:40 foram avaliados em ensaios de Ensaio Imuno-enzimático. Amostras de fígado, baço, pulmão e linfonodos de um sexto cão de Santa Maria, considerado como positivo à necropsia, foram examinadas através de histopatologia e PCR. Todos os resultados dos 204 cães foram negativos, indicando que, apesar de não ser impossível a ocorrência de leishmaniose visceral na região, por vários fatores aqui discutidos, ela deve ser pelo menos extremamente rara, sendo necessários estudos mais detalhados do material dos cinco cães tidos como positivos.

JUVENTUDE E POBREZA: IMPLICAÇÕES PSICOSSOCIAIS DO FATALISMO