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Sample records for midday aurorae

  1. Midday auroras and magnetospheric substorms.

    NASA Technical Reports Server (NTRS)

    Akasofu, S. I.

    1972-01-01

    Auroral activity in the midday sector is examined in some detail on the basis of all-sky photographs taken from Pyramida, Spitzbergen. The equatorward motion of the midday auroras observed during substorms and the subsequent poleward shift during the recovery phase are discussed.

  2. Measurements of optical and midday auroras

    NASA Technical Reports Server (NTRS)

    Sivjee, G. G.

    1974-01-01

    Measurements made in the midday auroras are analyzed and compared to measurements from the nighttime auroras. Examples are given of coordinated programs in Alaska which involve satellites, radars, ground optical instrumentation, and other types of observing satellites for the study of auroras.

  3. Coordinated analysis of airborne spectrophotometric measurements from the mid-day auroras

    NASA Technical Reports Server (NTRS)

    Sivjee, G. G.

    1974-01-01

    Measurements made in the midday auroras are analyzed and compared to measurements from the nighttime auroras. The auroral emission features in the UV spectrum, the N2(+)ING, the N22PG, and N2VK bands, are discussed. Spectral profiles of different bands are presented, and intensity distributions are obtained. Three mechanisms are suggested which can account for the marked differences between the intensity distributions of the N2(+)ING bands of the high altitude midday auroras and the low altitude nighttime auroras: (1) differences in vibrational, rotational, and transitional temperatures; (2) resonant scattering of solar radiation; and (3) excitation of slow ions.

  4. Coordinated analysis of airborne spectrophotometric measurements from the mid-day auroras

    NASA Technical Reports Server (NTRS)

    Sivjee, G. G.

    1974-01-01

    Measurements made in the midday auroras are analyzed and compared to measurements from the nighttime auroras. The auroral emission features in the UV spectrum, the N2(+)ING, the N22PG, and N2VK bands, are discussed. Spectral profiles of different bands are presented, and intensity distributions are obtained. Three mechanisms are suggested which can account for the marked differences between the intensity distributions of the N2(+)ING bands of the high altitude midday auroras and the low altitude nighttime auroras: (1) differences in vibrational, rotational, and transitional temperatures; (2) resonant scattering of solar radiation; and (3) excitation of slow ions.

  5. Auroral forms that extend equatorward from the persistent midday aurora during geomagnetically quiet periods

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. V.; Carlson, H. C.; Heelis, R. A.

    2012-09-01

    Auroral forms (“crewcuts”) that extend equatorward from the geomagnetically east-west aligned persistent midday aurora have been characterized based on a survey of Svalbard 630.0-nm all-sky images from eight December solstice seasons. The 630.0-nm forms are directly related to a mix of precipitating magnetosheath and plasma sheet electrons embedded in a population of boundary layer ions, as observed by NOAA 6. The associated midday aurora lies at the equatorward edge of poleward velocity-dispersed cusp ‘ion plumes’ observed by DMSP F7 at 1000 magnetic local time. In this survey, crewcuts are found to occur for Kp≤3. Distinct in many salient ways (including dynamics, orientation and associated IMF polarity) from the poleward-moving auroral forms (PMAFs) associated with transient dayside merging, crewcuts represent a solar wind-magnetosphere interaction that is more characteristic of quiet geomagnetic conditions. Crewcuts are present on 44% of the days for which all-sky images are complete and observing conditions are clear ±1.5 h around geomagnetic noon. During these periods, crewcuts are observed during 10.6% of the minutes for which IMF data from ISEE 2 or IMP 8 are available. We derive from the data a simple set of IMF “search criteria” that maximize the likelihood of observing crewcuts around the December solstice. The IMF magnitude range for which crewcuts are most commonly observed is 3.5±0.5 nT (36%). The IMF GSM component ranges in which crewcuts are most commonly observed are: Bx=-3.5±0.5 nT (27%), By=-1.5±0.5 nT (25%), and Bz=0.5±0.5 nT (26%). The IMF clock angular ranges for which crewcuts are most commonly observed are -70°±10° and 90°±10° (both 21%). The IMF cone angular range for which crewcuts are most commonly observed is 12.5°±2.5° (28%). Considering these observations in the context of magnetic merging topologies, we suggest crewcuts observed at Svalbard are most likely to lie at the foot of overdraped field lines

  6. Electron precipitation in the midday auroral oval

    SciTech Connect

    Meng, C.

    1981-04-01

    Simultaneous observations of auroral displays and electron precipitations by the DMSP 33 satellite provide an excellent and unique opportunity to study precipitation characteristics of the midday auroral oval. Attention is given to two topics: (1) the nature of the 'gap' of the midday discrete auroras which is a permanent feature of the dayside auroral oval observed by both Isis 2 and DMSP satellites and (2) the relationship of this gap with the polar cusp region. Based on 2-month (June, July 1975) observations of the midday auroras over the southern hemisphere, it is found that inside the 'gap' of the discrete auroras along the dayside auroral oval, soft electron precipitations with a magnetosheathlike spectrum were invariably detected. The spatial extent of this region was about few degrees in latitude and about 2--3 hours in local time near 1130 magnetic local time meridian. No significant electron precipitation was detected poleward of the instantaneous midday auroral oval. Typical plasma sheet and discrete auroral types of electron precipitations were detected in the other parts of the midday auroral oval. Therefore it is proposed that the ionospheric projection of the polar cusp is a small region of the instantaneous dayside auroral oval near the noon meridian, coinciding with the 'gap' of the midday discrete auroras.

  7. Rainbow Near Midday

    NASA Astrophysics Data System (ADS)

    Cornell, David A.

    2012-12-01

    It was near midday on Sunday, Sept. 25, 2011. My family and I were coming home in the car when we saw strongly colored bands in the sky near the northern horizon. The effect was striking and attracted motorists to stop and gaze at it. Houses in the north seemed to be wearing a gently curving band of colors above the roof. If this were a rainbow, it was like no other that I had seen before. I quickly ran to get a camera to capture the effect before it vanished. See Fig. 1 for an image of the phenomenon.

  8. Aurorae Chaos

    NASA Image and Video Library

    2010-09-22

    Located at the eastern end of Vallis Marineris is the region of chaos called Aurorae. This image from NASA Mars Odyssey is from the northern part of Aurorae Chaos and contains mesas separated by complex low lying regions.

  9. Aurora Australis

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Red and Green colors predominate in this view of the Aurora Australis photographed from the Space Shuttle Discovery (STS-39) in May 1991 at the peak of the last geomagnetic maximum. The payload bay and tail of the shuttle can be seen on the left hand side of the picture. Auroras are caused when high-energy electrons pour down from the Earth's magnetosphere and collide with atoms. Red aurora occurs from 200 km to as high as 500 km altitude and is caused by the emission of 6300 Angstrom wavelength light from oxygen atoms. Green aurora occurs from about 100 km to 250 km altitude and is caused by the emission of 5577 Angstrom wavelength light from oxygen atoms. The light is emitted when the atoms return to their original unexcited state. At times of peaks in solar activity, there are more geomagnetic storms and this increases the auroral activity viewed on Earth and by astronauts from orbit.

  10. Aurorae Chaos

    NASA Image and Video Library

    2011-07-12

    Aurorae Chaos is located at the eastern end of the chasmata forming Vallis Marineris. This image from NASA 2001 Mars Odyssey spacecraft is very close to the chasmata and at a higher elevation than the floor of the chasmata.

  11. Aurora sequence

    NASA Image and Video Library

    2015-04-27

    ISS043E155854 (04/27/2015) --- A rising sun spreads across the Earth and through the green blooming aurora to silhouette the blackened outline of the International Space Station on the morning of Apr. 27, 2015.

  12. Aurorae Chaos

    NASA Image and Video Library

    2010-04-01

    The landslide deposit in this image captured by NASA 2001 Mars Odyssey spacecraft is located in Aurorae Chaos distinctive area of broken terrain. Several regions of chaotic terrain are located on the eastern end of the Valles Marineris system.

  13. Aurora Borealis

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This photograph of aurora borealis, northern aurora, was taken during the Spacelab-J (SL-J) mission (STS-47). People who live in the northernmost areas like Alaska or work in the southernmost regions like Antarctica often see colorful lights produced by Earth's natural electromagnetic generator; these shimmering expanses of light are auroras, commonly called the northern and southern lights. Charged particles from the magnetosphere follow magnetic fields and are accelerated toward Earth at the magnetic poles where they strike molecules in the upper atmosphere, staining the sky with the red and green lights of oxygen and hydrogen, and the purples and pinks of nitrogen. The altitude and inclination of the Spacelab will give scientists unique views of auroras, which occur at altitudes ranging from about 90 to 300 kilometers (56 to 186 miles). Most views of the auroras have been from the ground where only limited parts can be seen. These Spacelab views will give scientists information on their complex structure and chemical composition. The Spacelab-J was a joint mission of NASA and the National Space Development Agency of Japan (NASDA) utilizing a marned Spacelab module. The mission conducted microgravity investigations in materials and life sciences. The SL-J was launched aboard the Space Shuttle Orbiter Endeavour (STS-47) on September 12, 1992.

  14. Aurora Borealis

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This photograph of aurora borealis, northern aurora, was taken during the Spacelab-J (SL-J) mission (STS-47). People who live in the northernmost areas like Alaska or work in the southernmost regions like Antarctica often see colorful lights produced by Earth's natural electromagnetic generator; these shimmering expanses of light are auroras, commonly called the northern and southern lights. Charged particles from the magnetosphere follow magnetic fields and are accelerated toward Earth at the magnetic poles where they strike molecules in the upper atmosphere, staining the sky with the red and green lights of oxygen and hydrogen, and the purples and pinks of nitrogen. The altitude and inclination of the Spacelab will give scientists unique views of auroras, which occur at altitudes ranging from about 90 to 300 kilometers (56 to 186 miles). Most views of the auroras have been from the ground where only limited parts can be seen. These Skylab views will give scientists information on their complex structure and chemical composition. The Spacelab-J was a joint mission of NASA and the National Space Development Agency of Japan (NASDA) utilizing a marned Spacelab module. The mission conducted microgravity investigations in materials and life sciences. The SL-J was launched aboard the Space Shuttle Orbiter Endeavour (STS-47) on September 12, 1992.

  15. Midday reversal of equatorial ionospheric electric field

    NASA Astrophysics Data System (ADS)

    Rastogi, R. G.

    1997-10-01

    A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956-1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

  16. Aurora Australis

    NASA Image and Video Library

    Video of the Aurora Australis taken by the crew of Expedition 29 on board the International Space Station. This sequence of shots was taken September 17, 2011 from 17:22:27 to 17:45:12 GMT, on an a...

  17. Morning reduction of photosynthetic capacity before midday depression

    PubMed Central

    Koyama, Kohei; Takemoto, Shuhei

    2014-01-01

    Midday depression of photosynthesis has important consequences for ecosystem carbon exchange. Recent studies of forest trees have demonstrated that latent reduction of photosynthetic capacity can begin in the early morning, preceding the midday depression. We investigated whether such early morning reduction also occurs in an herbaceous species, Oenothera biennis. Diurnal changes of the photosynthetic light response curve (measured using a light-emitting diode) and incident sunlight intensity were measured under field conditions. The following results were obtained: (1) the light-saturated photosynthetic rate decreased beginning at sunrise; (2) the incident sunlight intensity on the leaves increased from sunrise; and (3) combining (1) and (2), the net photosynthetic rate under natural sunlight intensity increased from sunrise, reached a maximum at mid-morning, and then showed midday depression. Our results demonstrate that the latent morning reduction of photosynthetic capacity begins at sunrise, preceding the apparent midday depression, in agreement with previous studies of forest trees. PMID:24633128

  18. Watching the Earth Spin: A Determination of Midday.

    ERIC Educational Resources Information Center

    Hansgen, Richard

    1995-01-01

    Presents activities that enable students to determine the exact time of midday and to use this to plot a north-south line. Uses shadow experiments to teach the concepts of rotation of the earth and calculation of latitude. (JRH)

  19. Saturn Colorful Aurora

    NASA Image and Video Library

    2014-02-11

    While the curtain-like auroras we see at Earth are green at bottom and red at top, NASA Cassini spacecraft has shown us similar curtain-like auroras at Saturn that are red at bottom and purple at top. This is how the auroras would look to the human eye.

  20. Los Angeles summer midday particulate carbon: Primary and secondary aerosol

    SciTech Connect

    Turpin, B.J.; Huntzicker, J.J. ); Larson, S.M.; Cass, G.R. )

    1991-10-01

    Aerosol sampling during photochemically active times across the Los Angeles Basin has provided evidence of secondary formation of organic aerosol from gas-phase precursors at midday. Ambient organic carbon/elemental carbon ratios exceeded the estimated ratio of organic carbon/elemental carbon in primary source emissions on most sampling days at all sites. The concentration of secondary organic aerosol was calculated by using ambient data and estimates of the organic carbon/elemental carbon ratio in primary source emissions. Nonparametric sign correlations comparing calculated secondary organic carbon concentrations with tracers of both primary and secondary aerosols supported the method used to quantify secondary organic carbon. Secondary organic aerosol appears to have contributed roughly half of the organic aerosol in Pasadena during midday summer conditions.

  1. Midday auroral observations in the oval, cusp region, and polar cap.

    NASA Technical Reports Server (NTRS)

    Romick, G. J.; Brown, N. B.

    1971-01-01

    Evaluation of combined photographic and photometric measurements made on the 1969 NASA airborne expedition, yielding a description of the midday oval, cusp region, and polar cap auroral precipitation at low magnetic activity (Kp = 0, 1+). The observations delineate three regions through the description of the type of aurora observed and the photometrically inferred change in energy of the particles: (1) the region in and equatorward of the oval where greater than 3-keV electrons are associated with 6300 A/4278 A ratios less than or equal to 1 and with a diffuse glow or structured arcs; (2) the cusp region where electrons of several hundred electron volts and spikes of more energetic electrons are associated with 6300 A/4278 A ratios between 10 and 35 in broken, fragmented, rayed features and patches; (3) the polar cap where discrete earth-sun-aligned arcs have height luminosity profiles in 5577 A, 6300 A (forbidden O I), and 4278 A (N2(+)) that suggest incoming electrons with an energy spectrum of 2-keV characteristic energy above a low-energy (few hundred electron volts) background.

  2. Auroras in the region of the near-polar boundary of the cusp in the case the northward IMF

    NASA Astrophysics Data System (ADS)

    Gabis, I. P.; Pudovkin, M. I.

    1992-08-01

    All-sky camera data from the Antarctic station Vostok are used to analyze the characteristics of auroras associated with midday anomalous ionization in the E-layer appearing in the case of the northward IMF. Arc-type auroras, single or multiple, are shown to appear in the corrected geomagnetic-latitude interval of 80-83 deg a few minutes before or simultaneously with the anomalous ionization in the E-region. The observed midday anomalous ionization and the associated auroras appear to be a manifestation of the reconnection process of the northward interplanetary and geomagnetic fields at the high-latitude magnetopause, leading to the precipitation of particles into the ionosphere.

  3. Modeling the Jovian aurora

    NASA Technical Reports Server (NTRS)

    Waite, J. Hunter, Jr.

    1992-01-01

    The Jovian aurora is the most powerful aurora in the solar system, over 100 times more powerful than the Earth's aurora. These magnificent visual displays can provide important information about the planetary magnetosphere which is responsible for the acceleration of energetic particles that produce aurora at any planet. Similarities and differences in planetary auroral emissions are thus a viable means of classifying and studying both comparative atmospheric and magnetospheric processes. For instance, at Earth the solar wind is the primary source of auroral power while at Jupiter it is conjectured that the rotation of the planet is the major source of magnetospheric and auroral power. The purpose of this IR project was to develop a model: (1) for use in interpreting the existing set of multispectral observations of Jupiter's aurora; and (2) to design new experiments based on the findings to improve understanding of the underlying auroral processes.

  4. Alien aurorae on Uranus

    NASA Image and Video Library

    2017-04-03

    Ever since Voyager 2 beamed home spectacular images of the planets in the 1980s, planet-lovers have been hooked on extra-terrestrial aurorae. Aurorae are caused by streams of charged particles like electrons, that come from various origins such as solar winds, the planetary ionosphere, and moon volcanism. They become caught in powerful magnetic fields and are channelled into the upper atmosphere, where their interactions with gas particles, such as oxygen or nitrogen, set off spectacular bursts of light. The alien aurorae on Jupiter and Saturn are well-studied, but not much is known about the aurorae of the giant ice planet Uranus. In 2011, the NASA/ESA Hubble Space Telescope became the first Earth-based telescope to snap an image of the aurorae on Uranus. In 2012 and 2014 astronomers took a second look at the aurorae using the ultraviolet capabilities of the Space Telescope Imaging Spectrograph (STIS) installed on Hubble. They tracked the interplanetary shocks caused by two powerful bursts of solar wind travelling from the Sun to Uranus, then used Hubble to capture their effect on Uranus’ aurorae — and found themselves observing the most intense aurorae ever seen on the planet. By watching the aurorae over time, they collected the first direct evidence that these powerful shimmering regions rotate with the planet. They also re-discovered Uranus’ long-lost magnetic poles, which were lost shortly after their discovery by Voyager 2 in 1986 due to uncertainties in measurements and the featureless planet surface. This is a composite image of Uranus by Voyager 2 and two different observations made by Hubble — one for the ring and one for the aurorae.

  5. Saturn's Visible Aurora

    NASA Astrophysics Data System (ADS)

    Dyudina, U.; Ingersoll, A. P.; Wellington, D. F.; Ewald, S.; Porco, C.

    2013-12-01

    Cassini camera's movies show Saturn's aurora in both the northern and southern hemispheres. The color of the aurora changes from pink at a few hundreds of km above the cloud tops to purple at 1000-1500 km above the cloud tops. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with the laboratory simulated auroras by [1]. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs, sometimes a spiral around the pole, and sometimes double arcs. Auroras are observed at 70-75 degrees both north and south latitude. 10,000-km-scale longitudinal brightness structure can persist for more than 3 days. This structure rotates together with Saturn. Besides the steady structure, the auroras brighten suddenly on the timescales of few minutes. 1000-km-scale disturbances may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The stability of the longitudinal structure of the aurora in 2009 allowed us to estimate its period of rotation of about 10.65 h. This is consistent with Voyager System III rotation and with the Saturn Kilometric Radiation (SKR) period detected by Cassini at the time of aurora observations. These periods are also close to the rotation period of the lightning storms on Saturn. We discuss those periodicities and their relevance to Saturn's rotation. In April-May 2013 a multi-instrument campaign using Cassini and Earth-based data was monitoring Saturn's aurora. We will discuss the results of this campaign. [1] Aguilar, A. et al. The Electron-Excited Mid-Ultraviolet to Near-Infrared Spectrum of H2: Cross Sections and Transition Probabilities. Astrophys. J. Supp. Ser. 177, 388-407 (2008).

  6. Jupiter's Auroras Acceleration Processes

    NASA Image and Video Library

    2017-09-06

    This image, created with data from Juno's Ultraviolet Imaging Spectrometer (UVS), marks the path of Juno's readings of Jupiter's auroras, highlighting the electron measurements that show the discovery of the so-called discrete auroral acceleration processes indicated by the "inverted Vs" in the lower panel (Figure 1). This signature points to powerful magnetic-field-aligned electric potentials that accelerate electrons toward the atmosphere to energies that are far greater than what drive the most intense aurora at Earth. Scientists are looking into why the same processes are not the main factor in Jupiter's most powerful auroras. https://photojournal.jpl.nasa.gov/catalog/PIA21937

  7. Look out, aurorae about!

    NASA Astrophysics Data System (ADS)

    Wild, Jim

    2006-02-01

    Myths and legends abound concerning the aurora borealis; observations, at least in the UK, are considerably more rare, yet people continue to be interested in observing them on the few times a year they are visible. AuroraWatch hopes to boost this interest by providing an email alert service that, since 2000, has used real-time information from a network of magnetometers to assess when aurorae might be visible. Alerts can be sent to mobile phones as well as by conventional email, and have already enabled many people to see this beautiful natural phenomenon.

  8. Earth Observation - small aurora

    NASA Image and Video Library

    2014-06-22

    ISS040-E-016995 (22 June 2014) --- This nighttime view featuring portions of an aurora and a Russian spacecraft docked to the International Space Station was photographed by an Expedition 40 crew member on the station.

  9. Earth Observation - Aurora

    NASA Image and Video Library

    2014-08-27

    Earth Observation taken during a night pass by the Expedition 40 crew aboard the International Space Station (ISS). Folder lists this as: Phenomenal Aurora. Part of the Space Station Remote Manipulator System (SSRMS) arm is also visible.

  10. Sleep spindles in midday naps enhance learning in preschool children.

    PubMed

    Kurdziel, Laura; Duclos, Kasey; Spencer, Rebecca M C

    2013-10-22

    Despite the fact that midday naps are characteristic of early childhood, very little is understood about the structure and function of these sleep bouts. Given that sleep benefits memory in young adults, it is possible that naps serve a similar function for young children. However, children transition from biphasic to monophasic sleep patterns in early childhood, eliminating the nap from their daily sleep schedule. As such, naps may contain mostly light sleep stages and serve little function for learning and memory during this transitional age. Lacking scientific understanding of the function of naps in early childhood, policy makers may eliminate preschool classroom nap opportunities due to increasing curriculum demands. Here we show evidence that classroom naps support learning in preschool children by enhancing memories acquired earlier in the day compared with equivalent intervals spent awake. This nap benefit is greatest for children who nap habitually, regardless of age. Performance losses when nap-deprived are not recovered during subsequent overnight sleep. Physiological recordings of naps support a role of sleep spindles in memory performance. These results suggest that distributed sleep is critical in early learning; when short-term memory stores are limited, memory consolidation must take place frequently.

  11. Saturn's visible aurora

    NASA Astrophysics Data System (ADS)

    Dyudina, U.; Ingersoll, A. P.; Ewald, S.; Porco, C. C.

    2013-09-01

    Cassini camera's movies show Saturn's aurora in both the northern and southern hemispheres. The color of the aurora changes from pink at a few hundreds of km above the cloud tops to purple at 1000-1500 km above the cloud tops. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with the laboratory simulated auroras by [1]. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs, sometimes a spiral around the pole, and sometimes double arcs at 70-75° both north and south latitude. 10,000-km-scale longitudinal brightness structure can persist for ∼˜3 days. This structure rotates together with Saturn. Besides the steady structure, the auroras brighten suddenly on the timescales of few minutes. 1000-km-scale disturbances may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The auroral curtains can extend more than 1200 km from their base to their top. The stability of the longitudinal structure of the aurora in 2009 allowed us to estimate its period of rotation of 10.65 ± 0.05 h. This is consistent to the Saturn Kilometric Radiation (SKR) period detected by Cassini in 2009. These periods are also close to the rotation period of the lightning storms on Saturn. We discuss those periodicities and their relevance to Saturn's rotation. In April-May 2013 a multi-instrument campaign using Cassini and Earth-based data was monitoring Saturn's aurora. We will discuss the results of this campaign.

  12. The dynamic aurora

    SciTech Connect

    Akasofu, Syunichi )

    1989-05-01

    Auroral physicists today know that auroras are lights emitted when atoms and molecules in the ionosphere are struck by electrons blowing in from the sun. The apparent motion of the auroral curtain is caused not by atmospheric turbulence but by changes in the electromagnetic conditions that propel the electrons, just as motion on a television screen is an illusion created by changes in the magnetic field that directs electrons from a cathode tube onto the screen. In the case of the aurora, what serves as the cathode tube Where is its power supply Why does that power seem to fluctuate from time to time, causing the aurora to ebb and flow across the polar sky More than 20 years ago it was determined that auroral emissions occur because the ionosphere is bombarded by electron beams generated by a complex interaction between the solar wind and the earth's magnetic envelope. The geomagnetic nature of the aurora can be seen clearly from outer space. Centered on each of the geomagnetic poles is a great luminous oval that is a permanent feature of the planet. The one around the North Pole is the aurora borealis. Its counterpart in the south is the aurora australis. The authors and his colleagues have now found a numerical relation between the solar wind and the generation of the power that drives the aurora, as well as other disturbances of the geomagnetic field. They are also gaining a better idea of how the sun's activity affects the solar wind. This progress raises the interesting possibility of developing a computer method to predict the intensity of auroral activity. Because auroras can interfere significantly with radio and satellite communications, as well as with power lines and some defense systems, the ability to predict auroral intensity has become increasingly important as human activity expands into polar regions and into space.

  13. AuroraMAX!

    NASA Astrophysics Data System (ADS)

    Donovan, E.; Spanswick, E. L.; Chicoine, R.; Pugsley, J.; Langlois, P.

    2011-12-01

    AuroraMAX is a public outreach and education initiative that brings auroral images to the public in real time. AuroraMAX utilizes an observing station located just outside Yellowknife, Canada. The station houses a digital All-Sky Imager (ASI) that collects full-colour images of the night sky every six seconds. These images are then transmitted via satellite internet to our web server, where they are made instantly available to the public. Over the last two years this program has rapidly become one of the most successful outreach programs in the history of Space Science in Canada, with hundreds of thousands of distinct visitors to the CSA AuroraMAX website, thousands of followers on social media, and hundreds of newspaper, magazine, radio, and television spots. Over the next few years, the project will expand to include a high-resolution SLR delivering real-time auroral images (also from Yellowknife), as well as a program where astronauts on the ISS will take pictures of the aurora with a handheld SLR. The objectives of AuroraMAX are public outreach and education. The ASI design, operation, and software were based on infrastructure that was developed for the highly successful ASI component of the NASA THEMIS mission as well as the Canadian Space Agency (CSA) Canadian GeoSpace Monitoring (CGSM) program. So from an education and public outreach perspective, AuroraMAX is a single camera operating in the Canadian north. On the other hand, AuroraMAX is one of nearly 40 All-Sky Imagers that are operating across North America. The AuroraMAX camera produces data that is seamlessly integrated with the CGSM ASI data, and made widely available to the Space Science community through open-access web and FTP sites. One of our objectives in the next few years is to incorporate some of the data from the THEMIS and CGSM imagers into the AuroraMAX system, to maximize viewing opportunities and generate more real-time data for public outreach. This is an exemplar of a program that

  14. A single starfish Aurora kinase performs the combined functions of Aurora-A and Aurora-B in human cells.

    PubMed

    Abe, Yusuke; Okumura, Eiichi; Hosoya, Takamitsu; Hirota, Toru; Kishimoto, Takeo

    2010-11-15

    Aurora, an essential mitotic kinase, is highly conserved during evolution. Most vertebrates have at least two Aurora kinases, Aurora-A and Aurora-B, which have distinct functions in the centrosome-spindle and inner centromere-midbody, respectively. However, some non-vertebrate deuterostomes have only a single Aurora. It remains to be verified whether the single Aurora performs the same functions as vertebrate Auroras A and B combined. We have isolated a cDNA of a single Aurora (ApAurora) from the echinoderm starfish, Asterina pectinifera, and show that ApAurora displays most features of both Aurora-A and Aurora-B in starfish oocytes and early embryos. Furthermore, ApAurora that is stably expressed in HeLa cells can substitute for both human Aurora-A and Aurora-B when either is reduced by RNAi. A single ApAurora thus has properties of both Aurora-A and Aurora-B in starfish eggs and HeLa cells. Together with phylogenetic analysis indicating that ApAurora forms a clade with all types of vertebrate Auroras and single Auroras of non-vertebrate deuterostomes, our observations support the idea that the single Aurora found in non-vertebrate deuterostomes represents the ancestor that gave rise to various types of vertebrate Auroras. This study thus provides functional evidence for phylogenetic considerations.

  15. NASA Observes Auroras Across Canada

    NASA Image and Video Library

    The dancing lights in the image above are the aurora borealis, viewed from the ground looking up. The aurora shown above occurred as the result of a CME that struck Earth’s magnetic field early on ...

  16. Space Weather and Earth's Aurora

    NASA Image and Video Library

    Aurora are colorful lights in the night time sky primarily appearing in Earth's polar regions. But what causes them? The culprit behind aurora is our own Sun and the solar plasma that is ejected du...

  17. Understanding the theta aurora

    NASA Astrophysics Data System (ADS)

    Fear, Robert; Milan, Steve; Carter, Jennifer; Maggiolo, Romain; Fazakerley, Andrew; Dandouras, Iannis; Mende, Stephen

    2015-04-01

    The theta aurora, first observed by Dynamics Explorer in the 1980s, is a configuration of the Earth's aurora in which auroral emissions extend into and across the polar cap in the form of a transpolar arc. It is well established that the theta aurora occurs predominantly when the interplanetary magnetic field has a northward component, but over the last thirty years various mechanisms have been put forward to explain this intriguing phenomenon. In the last couple of years, a range of evidence has accumulated which strongly suggests that the transpolar arc is formed as proposed by Milan et al. (2005): magnetotail reconnection occurs during intervals of northward IMF, which results in a local "wedge" of closed magnetospheric flux that remains trapped in the magnetotail. Precipitation on these closed field lines results in the transpolar arc analogously to the formation of the aurora in the main oval. Evidence for magnetotail reconnection as the cause of the theta aurora includes the timescales necessary to influence the location at which the transpolar arc forms, and the presence of characteristic ionospheric flows which are excited by magnetotail reconnection and which are statistically associated with transpolar arcs (Fear & Milan, 2012a,b). Most recently, direct observation has been made of a localised wedge of closed magnetic flux, "trapped" in the lobe, which was observed to move back and forth in a manner which (to our knowledge) can only be explained by the magnetotail reconnection mechanism (Fear et al., 2014). In this talk, we summarise the evidence for the formation of the theta aurora by magnetotail reconnection, and discuss the remaining challenges in obtaining a comprehensive understanding of this spectacular phenomenon.

  18. Structure of black aurora associated with pulsating aurora

    NASA Astrophysics Data System (ADS)

    Fritz, Bruce A.; Lessard, Marc L.; Blandin, Matthew J.; Fernandes, Philip A.

    2015-11-01

    Morphological behavior of black aurora as it relates to pulsating aurora is investigated by examining a collection of ground-based observations from January 2007 in support of the Rocket Observations of Pulsating Aurora rocket campaign. Images were sampled from video recorded by a Xybion intensified camera (30 fps) at Poker Flat Research Range, AK. The primary observations of black aurora recorded during the substorm recovery phase were between separate patches of pulsating aurora as well as pulsating aurora separated from diffuse aurora. In these observations the black aurora forms an apparent firm boundary between the auroral forms in a new behavior that is in contrast with previously reported observations. Also presented for the first time are black curls in conjunction with pulsating aurora. Curl structures that indicate shear plasma flows in the ionosphere may be used as a proxy for converging/diverging electric fields in and above the ionosphere. This new subset of black auroral behavior may provide visual evidence of black aurora as an ionospheric feedback mechanism as related to pulsating aurora.

  19. Thermospheric aurora and airglow

    SciTech Connect

    Meier, R.R.

    1987-04-01

    New information added in the years between 1983 and 1986 to the understanding of the physics and chemistry responsible for the production of aurora and airglow emissions is presented. On auroras, the bulk of new information comes from the information obtained from satellite-based imaging (by DE1) and spectroscopy, rocket-based observations of bremsstrahlung from electrons precipitating in the auroral zone, and measurements of metastable ion species. On airglow, the DE1 photometric experiment has provided the opportunity of studying the geocorona on a global scale. A geotail was detected in the antisolar direction, confirming earlier observations. 123 references.

  20. Imaging Sunlit Aurora from Balloon

    NASA Astrophysics Data System (ADS)

    Lummerzheim, D.; Zhou, X.

    2012-12-01

    Since 1892 when aurora was first imaged by Martin Brendel, useful auroral images have been obtained only when the aurora is in darkness. While UV imagers onboard satellite provide global auroral dynamics, the sunlit aurora in the UV band is overwhelmed by the UV airglow that has the same wavelengths with the UV auroral emissions. The visible band imaging is feasible only when the aurora is in darkness to avoid the sunlight contamination. However, sunlit aurora (such as dayside aurora) is closely related to the solar wind - magnetosphere - ionosphere coupling. In addition, limited land area has badly restricted the capability of imaging dayside aurora from the northern hemisphere and nightside aurora from the southern hemisphere. We have confirmed that sunlit aurora can be imaged using a near-infrared (NIR) camera on board the balloon platform flying in Antarctica or Arctic. This method provides a unique capability for dayside and conjugate auroral investigations. Scientific questions that can be addressed by such observations include how does the dayside aurora respond to solar wind transient variations? Are auroras hemispherically symmetric? Are auroral forms and their variations under sunlight the same as those in darkness? etc. The new method is also cost effective comparing to space-borne imagers, and offers capabilities not obtainable from space and the ground. With the accomplishment of identifying auroral dynamics in sunlight and darkness, in the south and north simultaneously, our knowledge and understanding of auroral phenomenon and its causes will be expanded.

  1. Midday stomatal conductance is more related to stem rather than leaf water status in subtropical deciduous and evergreen broadleaf trees

    Treesearch

    Yong-Jiang Zhang; Frederick C. Meinzer; Qi Jin-Hua; Guillermo Goldstein; Cao. Kun-Fang

    2012-01-01

    Midday depressions in stomatal conductance (gs/>) and photosynthesis are common in plants. The aim of this study was to understand the hydraulic determinants of midday gs, the coordination between leaf and stem hydraulics and whether regulation of midday gs/> differed between...

  2. Midday stomatal conductance is more related to stem rather than leaf water status in subtropical deciduous and evergreen broadleaf trees.

    PubMed

    Zhang, Yong-Jiang; Meinzer, Frederick C; Qi, Jin-Hua; Goldstein, Guillermo; Cao, Kun-Fang

    2013-01-01

    Midday depressions in stomatal conductance (g(s) ) and photosynthesis are common in plants. The aim of this study was to understand the hydraulic determinants of midday g(s) , the coordination between leaf and stem hydraulics and whether regulation of midday g(s) differed between deciduous and evergreen broadleaf tree species in a subtropical cloud forest of Southwest (SW) China. We investigated leaf and stem hydraulics, midday leaf and stem water potentials, as well as midday g(s) of co-occurring deciduous and evergreen tree species. Midday g(s) was correlated positively with midday stem water potential across both groups of species, but not with midday leaf water potential. Species with higher stem hydraulic conductivity and greater daily reliance on stem hydraulic capacitance were able to maintain higher stem water potential and higher g(s) at midday. Deciduous species exhibited significantly higher stem hydraulic conductivity, greater reliance on stem capacitance, higher stem water potential and g(s) at midday than evergreen species. Our results suggest that midday g(s) is more associated with midday stem than with leaf water status, and that the functional significance of stomatal regulation in these broadleaf tree species is probably for preventing stem xylem dysfunction.

  3. Time lapse - Aurora Australis

    NASA Image and Video Library

    2013-07-05

    ISS040-E-040103 (5 July 2014) --- As the International Space Station was flying at an altitude of 226 nautical miles on July 5 above a point in the southern Indian Ocean near South Africa's Prince Edwards Islands, one of the Expedition 40 crew members photographed this image of Aurora Australis.

  4. Dark aurora shots

    NASA Image and Video Library

    2014-09-02

    ISS040-E-125550 (2 Sept. 2014) --- One of the Expedition 40 crew members aboard the International Space Station captured this image of the Aurora Australis 228 nautical miles above a point in the Indian Ocean half way between southern Africa and southern Australia, near the Tropic of Capricorn on Sept. 2, 2014. The moon is in the upper right corner of the frame.

  5. Time lapse - Aurora Australis

    NASA Image and Video Library

    2013-07-05

    ISS040-E-040088 (5 July 2014) --- As the International Space Station was flying at an altitude of 226 nautical miles on July 5 above a point in the southern Indian Ocean near South Africa's Prince Edwards Islands, one of the Expedition 40 crew members photographed this image of Aurora Australis.

  6. Aurora over Earth limb

    NASA Image and Video Library

    1994-04-10

    STS059-52-029 (9-20 April 1994) --- The constellation Orion is backdropped against a colorful display of the Southern Lights (aurora australis) in this 35mm image. Six NASA astronauts went on to spend a week and a half aboard the Space Shuttle Endeavour in support of the Space Radar Laboratory (SRL-1) mission.

  7. Visible Jovian Aurora

    NASA Image and Video Library

    1997-09-23

    Jupiter's aurora on the night side of the planet is seen here at five different wavelengths. Jupiter's bright crescent, which is about half illuminated, is out of view to the right. North is at the top. The images are centered at 57 degrees north and 184 degrees West and were taken on April 2, 1997 at a range of 1.7 million kilometers (1.05 million miles) by the Solid State Imaging (SSI) camera system aboard NASA's Galileo spacecraft. Although Jupiter's aurora had been imaged from Earth in the ultraviolet and infrared, these are the first images at visible wavelengths, where most of the emission takes place. CLR stands for clear (no filter) and shows the integrated brightness at all wavelengths. The other panels show the violet, green, red, and 889 nanometer-wavelength filtered images. The brightness of the aurora is roughly independent of wavelength, at least at the spectral resolution obtainable with these filters. As on Earth, the aurora is caused by electrically charged particles striking the upper atmosphere, causing the molecules of the atmosphere to glow. The brightness in the different filters contains information about the energy of the impinging particles and the composition of the upper atmosphere. If atomic hydrogen were the only emitter, the light would be much stronger in the red filter, which is not consistent with the observed distribution. http://photojournal.jpl.nasa.gov/catalog/PIA00605

  8. Tabletop Aurora Demonstrator.

    ERIC Educational Resources Information Center

    Zaffo, Peter Alfred

    1991-01-01

    A simple apparatus for studying various forms of the aurora borealis on a miniature scale can be constructed from a neon-storage flask, aluminum tape, a cardboard box, and a small piezoelectric ion gun of the type used to neutralize static charges on phonograph records. (PR)

  9. Fast aurora zone analysis

    NASA Technical Reports Server (NTRS)

    Booker, Mattie

    1992-01-01

    The Flight Dynamics Facility (FDF) of the Flight Dynamics Division (FDD), of the Goddard Space Flight Center provides acquisition data to tracking stations and orbit and attitude services to scientists and mission support personnel. The following paper explains how a method was determined that found spacecraft entry and exit times of the aurora zone.

  10. Tabletop Aurora Demonstrator.

    ERIC Educational Resources Information Center

    Zaffo, Peter Alfred

    1991-01-01

    A simple apparatus for studying various forms of the aurora borealis on a miniature scale can be constructed from a neon-storage flask, aluminum tape, a cardboard box, and a small piezoelectric ion gun of the type used to neutralize static charges on phonograph records. (PR)

  11. Structure of Black Aurora Associated With Pulsating Aurora

    NASA Astrophysics Data System (ADS)

    Kenward, D. R.; Fritz, B.; Lessard, M.; Fernandes, P. A.; Blandin, M.

    2015-12-01

    Morphological behavior of black aurora as it relates to pulsating aurora is investigated by examining a collection of ground-based observations from January 2007 in support of the ROPA rocket campaign. Images were sampled from video recorded by a Xybion intensified camera (30 fps) at Poker Flat Research Range, AK. The primary observations of black aurora were observed during the substorm recovery phase and separate patches of pulsating aurora as well as pulsating aurora from diffuse aurora. In these observations the black aurora forms an apparent firm boundary between the auroral forms in a new behavior that is in contrast with previously reported observations. Also presented for the first time are black curls in conjunction with pulsating aurora. Curl structures that indicate shear plasma flows in the ionosphere may be used as a proxy for converging/diverging electric fields in and above the ionosphere. This new subset of black auroral behavior may provide visual evidence of black aurora as an ionospheric feedback mechanism as related to pulsating aurora.

  12. "St. Patrick's Aurora"

    NASA Image and Video Library

    2017-09-28

    Geomagnetic Storms Sometimes during the solar magnetic events, solar explosions hurl clouds of magnetized particles into space. Traveling more than a million miles per hour, these coronal mass ejections, or CMEs, made up of hot material called plasma take up to three days to reach Earth. Spacecraft and satellites in the path of CMEs can experience glitches as these plasma clouds pass by. In near-Earth space, magnetic reconnection incites explosions of energy driving charged solar particles to collide with atoms in Earth’s upper atmosphere. We see these collisions near Earth’s polar regions as the aurora. The prevalence of specific gases in the atmosphere determines the color of the aurora. For example, if charged particles strike oxygen atoms, the aurora will appear green. Excited nitrogen closer to 60 miles above Earth’s surface will produce a blood red color. Three spacecraft from NASA’s Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, observe these outbursts known as substorms. Substorms can intensify aurora’s near Earth’s poles. To learn more about the aurora, go to NASA’s THEMIS mission: www.nasa.gov/mission_pages/themis/main/index.html ---------- Original caption: How about a little something green for St. Patrick's Day? "St. Patrick's Aurora" was taken at Donnelly Creek, Alaska at 1:30 am, March 17, 2015 by our good friend Sebastian Saarloos! You can see more images from Sebastian here: www.facebook.com/SebastianSaarloos Credit: Sebastian Saarloos NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  13. Aurora Kinases Throughout Plant Development.

    PubMed

    Weimer, Annika K; Demidov, Dmitri; Lermontova, Inna; Beeckman, Tom; Van Damme, Daniël

    2016-01-01

    Aurora kinases are evolutionarily conserved key mitotic determinants in all eukaryotes. Yeasts contain a single Aurora kinase, whereas multicellular eukaryotes have at least two functionally diverged members. The involvement of Aurora kinases in human cancers has provided an in-depth mechanistic understanding of their roles throughout cell division in animal and yeast models. By contrast, understanding Aurora kinase function in plants is only starting to emerge. Nevertheless, genetic, cell biological, and biochemical approaches have revealed functional diversification between the plant Aurora kinases and suggest a role in formative (asymmetric) divisions, chromatin modification, and genome stability. This review provides an overview of the accumulated knowledge on the function of plant Aurora kinases as well as some major challenges for the future.

  14. Visible Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jupiter's aurora on the night side of the planet is seen here at five different wavelengths. Jupiter's bright crescent, which is about half illuminated, is out of view to the right. North is at the top. The images are centered at 57 degrees north and 184 degrees West and were taken on April 2, 1997 at a range of 1.7 million kilometers (1.05 million miles) by the Solid State Imaging (SSI) camera system aboard NASA's Galileo spacecraft.

    Although Jupiter's aurora had been imaged from Earth in the ultraviolet and infrared, these are the first images at visible wavelengths, where most of the emission takes place. CLR stands for clear (no filter) and shows the integrated brightness at all wavelengths. The other panels show the violet, green, red, and 889 nanometer-wavelength filtered images. The brightness of the aurora is roughly independent of wavelength, at least at the spectral resolution obtainable with these filters.

    As on Earth, the aurora is caused by electrically charged particles striking the upper atmosphere, causing the molecules of the atmosphere to glow. The brightness in the different filters contains information about the energy of the impinging particles and the composition of the upper atmosphere. If atomic hydrogen were the only emitter, the light would be much stronger in the red filter, which is not consistent with the observed distribution.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

  15. Aurora Australis, Sinuous Loop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the Aurora Australis or Southern Lights (location unknown) shows a sinuous looping band of airglow above the Earth Limb. Calculated to be in the 80 - 120 km altitude region, auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  16. Aurora Australis, Red Crown

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the Aurora Australis or Southern Lights (location unknown) shows a spiked band of red airglow called a 'Red Crown' above the Earth Limb. Calculated to be in the 80 - 120 km altitude region, auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  17. Baxter Aurora dialysis system.

    PubMed

    Kelly, Thomas D

    2004-01-01

    With the recent focus on the benefits of more frequent dialysis, the Baxter Aurora dialysis system provides maximum flexibility for therapy prescription, including short daily treatments, long nocturnal treatments, hemodialysis, hemofiltration, and online hemodiafiltration, all in a compact, reliable, easy to use system. A self-prompting touch screen user interface mounted on a movable arm provides for comfortable operation, whether sitting and standing. An automatic treatment setup mode facilitates easy treatment setup. Complex menus are eliminated by the use of a hardware key that automatically selects only the prescribed options during power up, eliminating all menus associated with nonprescribed functions and modalities. This prevents the user from becoming confused or accidentally altering the dialysis treatment. Prior to dialysis the instrument goes through an automatic self-test that confirms the operation of internal systems. The screen will dim when there is no action that the patient needs to attend to on the instrument. After dialysis, press the disinfect button and the instrument disinfects itself and shuts off. For patient safety, the "disinfect" menus are not available during dialysis. The instrument can also be programmed to automatically start and rinse at a set time. For remote treatment monitoring, the instrument connects to the Internet. The Aurora records information about the machine's technical status, providing a record of instrument history for easy servicing. The Aurora is a flexible platform that provides the desired renal therapy with ease of use and proper support for the hemodialysis patient when combined with Baxter's 24-hour infrastructure and support.

  18. Characteristics of Pulsating Aurora

    NASA Astrophysics Data System (ADS)

    Humberset, B. K.; Gjerloev, J. W.; Mann, I. R.; Samara, M.; Michell, R.

    2013-12-01

    We have investigated the spatiotemporal characteristics of pulsating auroral patches observed with an all-sky imager located at Poker Flat, Alaska. Pulsating aurora often covers the entire sky with intermixed large and small-scale patches that vary in intensity or disappear and reappear on different time scales and timings. The broad definition of pulsating aurora covers patches and bands from tens to several tens of km which have a quasi-periodic temporal variation from 1 s to tens of seconds. In this paper we examine >15 patches from different events. We analyze all-sky movies (557.7 nm, 3.31 Hz) with a simple, yet robust, technique that allows us to determine the scale size dependent variability of the >15 individual patches. A spatial 2D Fourier Transform is used to separate the aurora into different horizontal scale sizes, and by correlating each patch for all image separations and available scale sizes smaller than the patch itself, we reveal what scale sizes are pulsating and their variability. The patches are found to be persistent, meaning that we can follow them for typically 5 minutes. The period of the pulsations is often remarkably variable and it seems that only certain scale sizes pulsate (typically the size of the patch). The patches drift with the background ExB plasma drift indicating that the magnetospheric source mechanism drifts with the field lines.

  19. Southern Auroras Over Saturn

    NASA Image and Video Library

    2017-07-28

    Cassini gazed toward high southern latitudes near Saturn's south pole to observe ghostly curtains of dancing light -- Saturn's southern auroras, or southern lights. These natural light displays at the planet's poles are created by charged particles raining down into the upper atmosphere, making gases there glow. The dark area at the top of this scene is Saturn's night side. The auroras rotate from left to right, curving around the planet as Saturn rotates over about 70 minutes, compressed here into a movie sequence of about five seconds. Background stars are seen sliding behind the planet. Cassini was moving around Saturn during the observation, keeping its gaze fixed on a particular spot on the planet, which causes a shift in the distant background over the course of the observation. Some of the stars seem to make a slight turn to the right just before disappearing. This effect is due to refraction -- the starlight gets bent as it passes through the atmosphere, which acts as a lens. Random bright specks and streaks appearing from frame to frame are due to charged particles and cosmic rays hitting the camera detector. The aim of this observation was to observe seasonal changes in the brightness of Saturn's auroras, and to compare with the simultaneous observations made by Cassini's infrared and ultraviolet imaging spectrometers. The original images in this movie sequence have a size of 256x256 pixels; both the original size and a version enlarged to 500x500 pixels are available here. The small image size is the result of a setting on the camera that allows for shorter exposure times than full-size (1024x1024 pixel) images. This enabled Cassini to take more frames in a short time and still capture enough photons from the auroras for them to be visible. The images were taken in visible light using the Cassini spacecraft narrow-angle camera on July 20, 2017, at a distance of about 620,000 miles (1 million kilometers) from Saturn. The views look toward 74 degrees south

  20. Aurora Australis, Red Crown

    NASA Image and Video Library

    1991-05-06

    STS039-23-036 (28 April-6 May 1991) --- A 35mm frame of the Aurora Australis, also known as the Southern Lights, photographed from the Space Shuttle Discovery's flight deck by one of its seven crew members. One of the mission objectives was to measure the spectral and spatial characteristics of auroral emissions. While passing over the sunlit portion of Earth, the crew was able to take a number of photos of the various geographic points on the planet; much of the time on nightside passes was devoted to a thorough study and documentation of auroral displays.

  1. Aurora Australis, Sinuous Loop

    NASA Image and Video Library

    1991-05-06

    STS039-23-020 (28 April-6 May 1991) --- A 35mm frame of the Aurora Australis, also known as the Southern Lights, photographed from Space Shuttle Discovery's flight deck by one of its seven crew members. One of the mission objectives was to measure the spectral and spatial characteristics of auroral emissions. While passing over the sunlighted portion of Earth, the crew was able to take a number of photos of the various geographic points on the planet; much of the time on nightside passes was devoted to a thorough study and documentation of auroral displays.

  2. Night Side Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian aurora on the night side of the planet. The upper bright arc is auroral emission seen 'edge on' above the planetary limb with the darkness of space as a background. The lower bright arc is seen against the dark clouds of Jupiter. The aurora is easier to see on the night side of Jupiter because it is fainter than the clouds when they are illuminated by sunlight. Jupiter's north pole is out of view to the upper right. The images were taken in the clear filter (visible light) and are displayed in shades of blue.

    As on Earth, the auroral emission is caused by electrically charged particles striking the upper atmosphere from above. The particles travel along the magnetic field lines of the planet, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image to the right. In multispectral observations the aurora appears red, consistent with glow from atomic hydrogen in Jupiter's atmosphere. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in sequences of Galileo images.

    North is at the top of the picture. A grid of planetocentric latitude and west longitude is overlain on the images. The images were taken on November 5, 1997 at a range of 1.3 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the

  3. Night Side Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian aurora on the night side of the planet. The upper bright arc is auroral emission seen 'edge on' above the planetary limb with the darkness of space as a background. The lower bright arc is seen against the dark clouds of Jupiter. The aurora is easier to see on the night side of Jupiter because it is fainter than the clouds when they are illuminated by sunlight. Jupiter's north pole is out of view to the upper right. The images were taken in the clear filter (visible light) and are displayed in shades of blue.

    As on Earth, the auroral emission is caused by electrically charged particles striking the upper atmosphere from above. The particles travel along the magnetic field lines of the planet, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image to the right. In multispectral observations the aurora appears red, consistent with glow from atomic hydrogen in Jupiter's atmosphere. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in sequences of Galileo images.

    North is at the top of the picture. A grid of planetocentric latitude and west longitude is overlain on the images. The images were taken on November 5, 1997 at a range of 1.3 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the

  4. Simultaneous observations of auroras from the South Pole Station and of precipitating electrons by Isis 1.

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.; Akasofu, S.-I.; Yasuhara, F.

    1973-01-01

    On the basis of the simultaneous observations of auroras from the South Pole and of precipitating electrons by the Isis 1 satellite it is shown that (1) a midday auroral arc (photographed on black and white film) occurs within the cleft (cusp) region projected to the appropriate auroral height along the geomagnetic field; (2) in the evening sector an aurora, observed by Isis 1 and the South Pole all-sky camera, extended for at least 5 hours of local geomagnetic time in the expected position of the auroral oval; and (3) during a period of extreme magnetic quiet, cleftlike electrons were observed just poleward of a narrow region of intense precipitation in the midnight sector. An earth-sun oriented arc was seen at the projected location of the intense electron flux.

  5. Using midday stem water potential to assess irrigation needs of landscape valley oaks

    Treesearch

    Ken Shackel; Rob Gross

    2002-01-01

    In a number of deciduous tree crops a reliable pressure chamber measurement of water stress (midday stem water potential or SWP) has been recently developed and found to be closely related to both irrigation regime and tree physiological responses to stress. A standard pressure chamber is used for the measurement of SWP, but prior to sampling, the leaf is enclosed in a...

  6. Aurorae in Australian Aboriginal Traditions

    NASA Astrophysics Data System (ADS)

    Hamacher, Duane W.

    2013-07-01

    Transient celestial phenomena feature prominently in the astronomical knowledge and traditions of Aboriginal Australians. In this paper, I collect accounts of the Aurora Australis from the literature regarding Aboriginal culture. Using previous studies of meteors, eclipses, and comets in Aboriginal traditions, I anticipate that the physical properties of aurora, such as their generally red colour as seen from southern Australia, will be associated with fire, death, blood, and evil spirits. The survey reveals this to be the case and also explores historical auroral events in Aboriginal cultures, aurorae in rock art, and briefly compares Aboriginal auroral traditions with other global indigenous groups, including the Maori of New Zealand.

  7. False Color Aurora

    NASA Image and Video Library

    1997-09-23

    Data from NASA's Galileo spacecraft were used to produce this false-color composite of Jupiter's northern aurora on the night side of the planet. The height of the aurora, the thickness of the auroral arc, and the small-scale structure are revealed for the first time. Images in Galileo's red, green, and clear filters are displayed in red, green, and blue respectively. The smallest resolved features are tens of kilometers in size, which is a ten-fold improvement over Hubble Space Telescope images and a hundred-fold improvement over ground-based images. The glow is caused by electrically charged particles impinging on the atmosphere from above. The particles travel along Jupiter's magnetic field lines, which are nearly vertical at this latitude. The auroral arc marks the boundary between the "closed" field lines that are attached to the planet at both ends and the "open" field lines that extend out into interplanetary space. At the boundary the particles have been accelerated over the greatest distances, and the glow is especially intense. The latitude-longitude lines refer to altitudes where the pressure is 1 bar. The image shows that the auroral emissions originate about 500 kilometers (about 310 miles) above this surface. The colored background is light scattered from Jupiter's bright crescent, which is out of view to the right. North is at the top. The images are centered at 57 degrees north and 184 degrees west and were taken on April 2, 1997 at a range of 1.7 million kilometers (1.05 million miles) by Galileo's Solid State Imaging (SSI) system. http://photojournal.jpl.nasa.gov/catalog/PIA00603

  8. Adventures in search of auroras

    NASA Astrophysics Data System (ADS)

    Forsyth, Colin

    2016-09-01

    In her book Aurora: In Search of the Northern Lights, Melanie Windridge describes travelling around the Arctic Circle on a quest to see the biggest and best auroral displays and to understand the physics that drives them.

  9. Juno Listens to Jupiters Auroras

    NASA Image and Video Library

    2016-09-01

    During Juno's close flyby of Jupiter on August 27, 2016, the Waves instrument received radio signals associated with the giant planet's intense auroras. Animation and audio display the signals after they have been shifted into the audio frequency range.

  10. Aurora Australis, Seen From Space

    NASA Image and Video Library

    This video of the Aurora Australis was created from a sequence of still shots taken by astronauts on board the International Space Station. The images were acquired on September 11, 2011 as the ISS...

  11. Aurora Australis over Indian Ocean

    NASA Image and Video Library

    Video of the Aurora Australis taken by the crew of Expedition 28 on board the International Space Station. This sequence of shots was taken September 7, 2011 from 17:38:03 to 17:49:15 GMT, from the...

  12. Aurora Kinase Inhibitors: Current Status and Outlook.

    PubMed

    Bavetsias, Vassilios; Linardopoulos, Spiros

    2015-01-01

    The Aurora kinase family comprises of cell cycle-regulated serine/threonine kinases important for mitosis. Their activity and protein expression are cell cycle regulated, peaking during mitosis to orchestrate important mitotic processes including centrosome maturation, chromosome alignment, chromosome segregation, and cytokinesis. In humans, the Aurora kinase family consists of three members; Aurora-A, Aurora-B, and Aurora-C, which each share a conserved C-terminal catalytic domain but differ in their sub-cellular localization, substrate specificity, and function during mitosis. In addition, Aurora-A and Aurora-B have been found to be overexpressed in a wide variety of human tumors. These observations led to a number of programs among academic and pharmaceutical organizations to discovering small molecule Aurora kinase inhibitors as anti-cancer drugs. This review will summarize the known Aurora kinase inhibitors currently in the clinic, and discuss the current and future directions.

  13. Aurora Kinase Inhibitors: Current Status and Outlook

    PubMed Central

    Bavetsias, Vassilios; Linardopoulos, Spiros

    2015-01-01

    The Aurora kinase family comprises of cell cycle-regulated serine/threonine kinases important for mitosis. Their activity and protein expression are cell cycle regulated, peaking during mitosis to orchestrate important mitotic processes including centrosome maturation, chromosome alignment, chromosome segregation, and cytokinesis. In humans, the Aurora kinase family consists of three members; Aurora-A, Aurora-B, and Aurora-C, which each share a conserved C-terminal catalytic domain but differ in their sub-cellular localization, substrate specificity, and function during mitosis. In addition, Aurora-A and Aurora-B have been found to be overexpressed in a wide variety of human tumors. These observations led to a number of programs among academic and pharmaceutical organizations to discovering small molecule Aurora kinase inhibitors as anti-cancer drugs. This review will summarize the known Aurora kinase inhibitors currently in the clinic, and discuss the current and future directions. PMID:26734566

  14. Molecular Distinctions between Aurora A and B: A Single Residue Change Transforms Aurora A into Correctly Localized and Functional Aurora B

    PubMed Central

    Hans, Fabienne; Skoufias, Dimitrios A.

    2009-01-01

    Aurora A and Aurora B, paralogue mitotic kinases, share highly similar primary sequence. Both are important to mitotic progression, but their localizations and functions are distinct. We have combined shRNA suppression with overexpression of Aurora mutants to address the cause of the distinction between Aurora A and Aurora B. Aurora A residue glycine 198 (G198), mutated to asparagine to mimic the aligned asparagine 142 (N142) of Aurora B, causes Aurora A to bind the Aurora B binding partner INCENP but not the Aurora A binding partner TPX2. The mutant Aurora A rescues Aurora B mitotic function. We conclude that binding to INCENP is alone critical to the distinct function of Aurora B. Although G198 of Aurora A is required for TPX2 binding, N142G Aurora B retains INCENP binding and Aurora B function. Thus, although a single residue change transforms Aurora A, the reciprocal mutation of Aurora B does not create Aurora A function. An Aurora A-Δ120 N-terminal truncation construct reinforces Aurora A similarity to Aurora B, because it does not associate with centrosomes but instead associates with kinetochores. PMID:19494039

  15. The Concept of Qailulah (Midday Napping) from Neuroscientific and Islamic Perspectives.

    PubMed

    Tumiran, Mohd Amzari; Rahman, Noor Naemah Abdul; Saat, Rohaida Mohd; Kabir, Nurul; Zulkifli, Mohd Yakub; Adli, Durriyyah Sharifah Hasan

    2015-08-13

    Napping/siesta during the day is a phenomenon, which is widely practised in the world. However, the timing, frequency, and duration may vary. The basis of napping is also diverse, but it is mainly done for improvement in alertness and general well-being. Neuroscience reveals that midday napping improves memory, enhances alertness, boosts wakefulness and performance, and recovers certain qualities of lost night sleep. Interestingly, Islam, the religion of the Muslims, advocates midday napping primarily because it was a practice preferred by Prophet Muhammad (pbuh). The objectives of this review were to investigate and compare identical key points on focused topic from both neuroscientific and Islamic perspectives and make recommendations for future researches.

  16. Patchy stomatal behavior during midday depression of leaf CO₂ exchange in tropical trees.

    PubMed

    Kamakura, Mai; Kosugi, Yoshiko; Takanashi, Satoru; Matsumoto, Kazuho; Okumura, Motonori; Philip, Elizabeth

    2011-02-01

    We investigated effects of heterogeneous stomatal behavior on diurnal patterns of leaf gas exchange in 10 tree species. Observations were made in middle and upper canopy layers of potted tropical rainforest trees in a nursery at the Forest Research Institute Malaysia. Measurements were taken from 29 January to 3 February 2010. We measured in situ diurnal changes in net photosynthetic rate and stomatal conductance in three leaves of each species under natural light. In both top-canopy and sub-canopy species, midday depression of net assimilation rate occurred in late morning. Numerical analysis showed that patchy bimodal stomatal behavior occurred only during midday depression, suggesting that the distribution pattern of stomatal apertures (either uniform or non-uniform stomatal behavior) varies flexibly within single days. Direct observation of stomatal aperture using Suzuki's Universal Micro-Printing (SUMP) method demonstrated midday patchy stomatal closure that fits a bimodal pattern in Shorea leprosula Miq., Shorea macrantha Brandis. and Dipterocarpus tempehes V.Sl. Inhibition of net assimilation rate and stomatal conductance appears to be a response to changes in vapor pressure deficit (VPD). Variable stomatal closure with increasing VPD is a mechanism used by a range of species to prevent excess water loss from leaves through evapotranspiration (viz., inhibition of midday leaf gas exchange). Bimodal stomatal closure may occur among adjacent stomata within a single patch, rather than among patches on a single leaf. Our results suggest the occurrence of patches at several scales within single leaves. Further analysis should consider variable spatial scales in heterogeneous stomatal behavior between and within patches and within single leaves.

  17. Plastid gene expression is not associated with midday depression in CO(2) assimilation and electron transport.

    PubMed

    Trivedi; Reddy; Sane

    2000-06-29

    To investigate the effect of diurnal variations on chloroplastic electron transport as well as accumulation of gene products associated with it, studies were carried out on Populus deltoides, a tree species. Electron transport studies showed two peak responses as a large diurnal change with pronounced midday depression in whole chain (H(2)O--> MV) as well as partial reactions for PSII (H(2)O-->PBQ) and PSI (DCPIP-->MV). The electron transport rates first increased from 05:00 h to a maximum at around 09:00 h and then showed a decrease at 13:00 h followed by recovery and further decrease. The pigments associated with electron transport chain did not show any change during the day. Surprisingly midday depression in the accumulation of transcripts and polypeptides related to electron transport was not observed. This suggests that chloroplastic gene expression is not associated with the midday depression observed for both CO(2) assimilation and electron transport. Studies on the transcripts of psbD/C operon during the day showed that there were differences in the processing pattern although the steady state levels of the processed transcripts of this operon did not show any variation.

  18. Exploring the nap paradox: are mid-day sleep bouts a friend or foe?

    PubMed

    Mantua, Janna; Spencer, Rebecca M C

    2017-09-01

    The mid-day nap, sometimes called a siesta, is a ubiquitous occurrence across the lifespan. It is well established that in addition to reducing sleepiness, mid-day naps offer a variety of benefits: memory consolidation, preparation for subsequent learning, executive functioning enhancement, and a boost in emotional stability. These benefits are present even if a sufficient amount of sleep is obtained during the night prior. However, we present a paradox: in spite of these reported benefits of naps, frequent napping has also been associated with numerous negative outcomes (eg, cognitive decline, hypertension, diabetes), particularly in older populations. This association exists even when statistically controlling for relevant health- and sleep-affecting determinants. An emerging hypothesis suggests inflammation is a mediator between mid-day naps and poor health outcomes, yet further research is necessary. Given this, it may be premature to 'prescribe' naps as a health enhancer. Herein, we aggregate findings from several branches of sleep research (eg, developmental neuroscience, cognitive neuroscience, sleep medicine) to critically examine the paradoxical role of naps in cognitive and somatic health. This review uncovers gaps in the literature to guide research opportunities in the field. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Aurora Borealis on Jupiter

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image, taken by NASA's Galileo spacecraft, shows the darkside of Jupiter, the part not illuminated by sunlight. The curved line crossing from the lower left to the upper right is the auroral arc on the horizon. With north at the top of the image, the central part of the auroral arc has a latitude of 57 degrees north. When this same region was imaged 30 seconds later, the central part had changed. The left and right boxes below show a magnified view of the central region at the earlier and later times, respectively. The aurora is dynamic on Jupiter, just as it is here on Earth. The eerie, glowing light is created when molecules in the upper atmosphere are struck by charge particles from the space around Jupiter. Fluctuations in the charged particle flow cause variations in the auroral emission.

    This image was part of a multi-instrument set of observations made as Galileo flew through a region of space rich in charged particles. The particles follow the magnetic field and, in this case, the spacecraft was flying through the particular field line that was imaged. With these observations, scientists hope to learn more about the particles and their interaction with the molecules in the atmosphere. This image provides a severe test of the camera optics. The overexposed region at the lower right is the illuminated part of the planet, which is much brighter than the aurora. When light from this region is scattered into the telescope, it creates a diffuse background. The long exposure subjects the detector to more cosmic rays than usual. These create spikes, the bright dots that are sprinkled throughout the image. These images were taken in the clear filter of the solid state imaging (CCD) system aboard the Galileo spacecraft on Nov. 5, 1996. Each pixel subtends a square about 30 kilometers (18.5 miles) throughout the image. The range is 1.433 million kilometers (0.89 million miles).

    Launched in October 1989, Galileo entered orbit around Jupiter on Dec. 7, 1995

  20. False Color Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Data from NASA's Galileo spacecraft were used to produce this false-color composite of Jupiter's northern aurora on the night side of the planet. The height of the aurora, the thickness of the auroral arc, and the small-scale structure are revealed for the first time. Images in Galileo's red, green, and clear filters are displayed in red, green, and blue respectively. The smallest resolved features are tens of kilometers in size, which is a ten-fold improvement over Hubble Space Telescope images and a hundred-fold improvement over ground-based images.

    The glow is caused by electrically charged particles impinging on the atmosphere from above. The particles travel along Jupiter's magnetic field lines, which are nearly vertical at this latitude. The auroral arc marks the boundary between the 'closed' field lines that are attached to the planet at both ends and the 'open' field lines that extend out into interplanetary space. At the boundary the particles have been accelerated over the greatest distances, and the glow is especially intense.

    The latitude-longitude lines refer to altitudes where the pressure is 1 bar. The image shows that the auroral emissions originate about 500 kilometers (about 310 miles) above this surface. The colored background is light scattered from Jupiter's bright crescent, which is out of view to the right. North is at the top. The images are centered at 57 degrees north and 184 degrees west and were taken on April 2, 1997 at a range of 1.7 million kilometers (1.05 million miles) by Galileo's Solid State Imaging (SSI) system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http:// galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

  1. Pulsating aurora: The importance of the ionosphere

    SciTech Connect

    Stenbaek-Nielsen, H.C.

    1980-05-01

    A number of different, but mainly optical, observations made in pulsating auroras are presented. These observations indicate that active ionospheric processes are likely to play an important role in causing and/or modifying pulsating aurora.

  2. Aurorae and Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  3. Aurora kinases: novel therapy targets in cancers.

    PubMed

    Tang, Anqun; Gao, Keyu; Chu, Laili; Zhang, Rui; Yang, Jing; Zheng, Junnian

    2017-01-29

    Aurora kinases, a family of serine/threonine kinases, consisting of Aurora A (AURKA), Aurora B (AURKB) and Aurora C (AURKC), are essential kinases for cell division via regulating mitosis especially the process of chromosomal segregation. Besides regulating mitosis, Aurora kinases have been implicated in regulating meiosis. The deletion of Aurora kinases could lead to failure of cell division and impair the embryonic development. Overexpression or gene amplification of Aurora kinases has been clarified in a number of cancers. And a growing number of studies have demonstrated that inhibition of Aurora kinases could potentiate the effect of chemotherapies. For the past decades, a series of Aurora kinases inhibitors (AKIs) developed effectively repress the progression and growth of many cancers both in vivo and in vitro, suggesting that Aurora kinases could be a novel therapeutic target. In this review, we'll first briefly present the structure, localization and physiological functions of Aurora kinases in mitosis, then describe the oncogenic role of Aurora kinases in tumorigenesis, we shall finally discuss the outcomes of AKIs combination with conventional therapy.

  4. Aurora taken during Joint Operations

    NASA Image and Video Library

    2008-03-21

    S123-E-008018 (21 March 2008) --- While docked and onboard the International Space Station, a STS-123 Endeavour crewmember captured the glowing green beauty of the Aurora Borealis. Looking northward across the Gulf of Alaska, over a low pressure area (cloud vortex), the aurora brightens the night sky. This image was taken on March 21, 2008 at 09:08:46 (GMT) with a 28 mm lens from the nadir point of 47.9 degrees north latitude and 146.8 degrees west longitude.

  5. Spatial Compartmentalization Specializes the Function of Aurora A and Aurora B.

    PubMed

    Li, Si; Deng, Zhaoxuan; Fu, Jingyan; Xu, Caiyue; Xin, Guangwei; Wu, Zhige; Luo, Jia; Wang, Gang; Zhang, Shuli; Zhang, Boyan; Zou, Fangdong; Jiang, Qing; Zhang, Chuanmao

    2015-07-10

    Aurora kinase A and B share great similarity in sequences, structures, and phosphorylation motif, yet they show different localizations and play distinct crucial roles. The factors that determine such differences are largely unknown. Here we targeted Aurora A to the localization of Aurora B and found that Aurora A phosphorylates the substrate of Aurora B and substitutes its function in spindle checkpoint. In return, the centrosome targeting of Aurora B substitutes the function of Aurora A in the mitotic entry. Expressing the chimera proteins of the Auroras with exchanged N termini in cells indicates that the divergent N termini are also important for their spatiotemporal localizations and functions. Collectively, we demonstrate that functional divergence of Aurora kinases is determined by spatial compartmentalization, and their divergent N termini also contribute to their spatial and functional differentiation.

  6. Spatial Compartmentalization Specializes the Function of Aurora A and Aurora B*

    PubMed Central

    Li, Si; Deng, Zhaoxuan; Fu, Jingyan; Xu, Caiyue; Xin, Guangwei; Wu, Zhige; Luo, Jia; Wang, Gang; Zhang, Shuli; Zhang, Boyan; Zou, Fangdong; Jiang, Qing; Zhang, Chuanmao

    2015-01-01

    Aurora kinase A and B share great similarity in sequences, structures, and phosphorylation motif, yet they show different localizations and play distinct crucial roles. The factors that determine such differences are largely unknown. Here we targeted Aurora A to the localization of Aurora B and found that Aurora A phosphorylates the substrate of Aurora B and substitutes its function in spindle checkpoint. In return, the centrosome targeting of Aurora B substitutes the function of Aurora A in the mitotic entry. Expressing the chimera proteins of the Auroras with exchanged N termini in cells indicates that the divergent N termini are also important for their spatiotemporal localizations and functions. Collectively, we demonstrate that functional divergence of Aurora kinases is determined by spatial compartmentalization, and their divergent N termini also contribute to their spatial and functional differentiation. PMID:25987563

  7. An overnight chill induces a delayed inhibition of photosynthesis at midday in mango (Mangifera indica L.).

    PubMed

    Allen, D J; Ratner, K; Giller, Y E; Gussakovsky, E E; Shahak, Y; Ort, D R

    2000-11-01

    The effect of a cold night on photosynthesis in herbaceous chilling-sensitive crops, like tomato, has been extensively studied and is well characterized. This investigation examined the behaviour of the sub-tropical fruit tree, mango, to enable comparison with these well-studied systems. Unlike tomato, chilling between 5 degrees C and 7 degrees C overnight produced no significant inhibition of light-saturated CO(2) assimilation (A:) during the first hours following rewarming, measured either under controlled environment conditions or in the field. By midday, however, there was a substantial decline in A:, which could not be attributed to photoinhibition of PSII, but rather was associated with an increase in stomatal limitation of A: and lower Rubisco activity. Overnight chilling of tomato can cause severe disruption in the circadian regulation of key photosynthetic enzymes and is considered to be a major factor underlying the dysfunction of photosynthesis in chilling-sensitive herbaceous plants. Examination of the gas exchange of mango leaves maintained under constant conditions for 2 d, demonstrated that large depressions in A: during the subjective night were primarily the result of stomatal closure. Chilling did not disrupt the ability of mango leaves to produce a circadian rhythm in stomatal conductance. Rather, the midday increase in stomatal limitation of A: appeared to be the result of altered guard cell sensitivity to CO(2) following the dark chill.

  8. Aurora kinase inhibitors as anticancer molecules.

    PubMed

    Katayama, Hiroshi; Sen, Subrata

    2010-01-01

    Aurora kinase family of serine/threonine kinases are important regulators of mitosis that are frequently over expressed in human cancers and have been implicated in oncogenic transformation including development of chromosomal instability in cancer cells. In humans, among the three members of the kinase family, Aurora-A, -B and -C, only Aurora-A and -B are expressed at detectable levels in all somatic cells undergoing mitotic cell division and have been characterized in greater detail for their involvement in cellular pathways relevant to the development of cancer associated phenotypes. Aurora-A and -B are being investigated as potential targets for anticancer therapy. Development of inhibitors against Aurora kinases as anticancer molecules gained attention because of the facts that aberrant expression of these kinases leads to chromosomal instability and derangement of multiple tumor suppressor and oncoprotein regulated pathways. Preclinical studies and early phase I and II clinical trials of multiple Aurora kinase inhibitors as targeted anticancer drugs have provided encouraging results. This article discusses functional involvement of Aurora kinase-A and -B in the regulation of cancer relevant cellular phenotypes together with findings on some of the better characterized Aurora kinase inhibitors in modulating the functional interactions of Aurora kinases. Future possibilities about developing next generation Aurora kinase inhibitors and their clinical utility as anticancer therapeutic drugs are also discussed.

  9. Aurora Kinase inhibitors as Anticancer Molecules

    PubMed Central

    Katayama, Hiroshi; Sen, Subrata

    2015-01-01

    Aurora kinase family of serine/threonine kinases are important regulators of mitosis that are frequently over expressed in human cancers and have been implicated in oncogenic transformation including development of chromosomal instability in cancer cells. In humans, among the three members of the kinase family, Aurora-A, -B and -C, only Aurora-A and -B are expressed in detectable levels in somatic cells undergoing mitotic cell division and have been characterized in greater detail for their involvement in cellular pathways relevant to the development of cancer associated phenotypes. Aurora-A and -B are being investigated as potential targets for anticancer therapy. Development of inhibitors against Aurora kinases as anticancer molecules gained attention because of the facts that aberrant expression of these kinases lead to chromosomal instability and derangement of multiple tumor suppressor and oncoprotein regulated pathways. Pre-clinical studies and early phase I and II clinical trials of multiple Aurora kinase inhibitors as targeted anticancer drugs have provided encouraging results. This article discusses functional involvement of Aurora kinase-A and -B in the regulation of cancer relevant cellular phenotypes together with findings on some of the better characterized Aurora kinase inhibitors in modulating the functional interactions of Aurora kinases. Future possibilities about developing next generation Aurora kinase inhibitors and their clinical utility as anticancer therapeutic drugs are also discussed. PMID:20863917

  10. GREECE Mission Launching Into Aurora

    NASA Image and Video Library

    2017-09-27

    Caption: A NASA-funded sounding rocket launches into an aurora in the early morning of March 3, 2014, over Venetie, Alaska. The GREECE mission studies how certain structures – classic curls like swirls of cream in coffee -- form in the aurora. Credit: NASA/Christopher Perry More info: On March 3, 2014, at 6:09 a.m. EST, a NASA-funded sounding rocket launched straight into an aurora over Venetie, Alaska. The Ground-to-Rocket Electrodynamics – Electron Correlative Experiment, or GREECE, sounding rocket mission, which launched from Poker Flat Research Range in Poker Flat, Alaska, will study classic curls in the aurora in the night sky. The GREECE instruments travel on a sounding rocket that launches for a ten-minute ride right through the heart of the aurora reaching its zenith over the native village of Venetie, Alaska. To study the curl structures, GREECE consists of two parts: ground-based imagers located in Venetie to track the aurora from the ground and the rocket to take measurements from the middle of the aurora itself. At their simplest, auroras are caused when particles from the sun funnel over to Earth's night side, generate electric currents, and trigger a shower of particles that strike oxygen and nitrogen some 60 to 200 miles up in Earth's atmosphere, releasing a flash of light. But the details are always more complicated, of course. Researchers wish to understand the aurora, and movement of plasma in general, at much smaller scales including such things as how different structures are formed there. This is a piece of information, which in turn, helps paint a picture of the sun-Earth connection and how energy and particles from the sun interact with Earth's own magnetic system, the magnetosphere. GREECE is a collaborative effort between SWRI, which developed particle instruments and the ground-based imaging, and the University of California, Berkeley, measuring the electric and magnetic fields. The launch is supported by a sounding rocket team from

  11. The morphology of displays of pulsating auroras.

    NASA Technical Reports Server (NTRS)

    Cresswell, G. R.

    1972-01-01

    An auroral substorm generates displays of pulsating auroras in ways which show a dependence upon both local time and latitude relative to the auroral oval. For several hours after midnight pulsating auroras can be observed in the wake of poleward expansions or within equatorward spreading diffuse envelopes of meridional extent of several hundred kilometers. As the dawn meridian is approached the displays of pulsating auroras tend increasingly to be comprised of distinct eastward drifting patches easily recorded by all-sky cameras.

  12. Electron Observations Near ``Martian Aurora''

    NASA Astrophysics Data System (ADS)

    Winningham, J. D.; Frahm, R. A.; Sharber, J. R.; Liemohn, M. W.; Ma, Y.; Coates, A. J.; Linder, D. R.; Soobiah, Y.; Team, A.

    2005-12-01

    Earlier in 2005, Bertaux et al. in a letter to Nature titled ``Discovery of an Aurora on Mars'' reported an observation of a UV aurora on Mars as measured by the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) experiment on the Mars Express (MEX) spacecraft. We have examined the electron observations for the same time period as the reported aurora using the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) Electron Spectrometer (ELS), also on MEX. SPICAM and ELS do not observe the same volume of space, but do survey the same large region of near-vertical remanent Martian crustal magnetic field. During the auroral observation period, MEX crossed several regions of near-vertical fields based on the Cain et al. 2003 model and ELS observed brief bursts of low-energy electrons. No pitch angle data was available at that time as the field of view of ELS is approximately parallel to the Martian surface. Examination of the burst spectra showed evidence of Martian atmospheric photoelectrons, including carbon dioxide peaks from exobase emissions. At the time of observation, both MEX and the Mars atmosphere beneath were not sunlit. Thus, the photoelectrons must have come from a sunlit region of Mars. Ray tracing with the Cain et al. model shows that the filed lines within the bursts are closed loops connecting to Mars, with one field line foot in the Martian day-lit region. Results will be presented from the University of Michigan MHD model (which includes external magnetic fields) that will show, with a more sophisticated model, that the observed particles are on closed magnetic field loops. Thus, one can more accurately call the UV emissions ``airglow'' rather than ``aurora''.

  13. Morphologies of omega band auroras

    NASA Astrophysics Data System (ADS)

    Sato, Natsuo; Yukimatu, Akira Sessai; Tanaka, Yoshimasa; Hori, Tomoaki

    2017-08-01

    We examined the morphological signatures of 315 omega band aurora events observed using the Time History of Events and Macroscale Interactions during Substorm ground-based all-sky imager network over a period of 8 years. We find that omega bands can be classified into the following three subtypes: (1) classical (O-type) omega bands, (2) torch or tongue (T-type) omega bands, and (3) combinations of classical and torch or tongue (O/T-type) omega bands. The statistical results show that T-type bands occur the most frequently (45%), followed by O/T-type bands (35%) and O-type bands (18%). We also examined the morphologies of the omega bands during their formation, from the growth period to the declining period through the maximum period. Interestingly, the omega bands are not stable, but rather exhibit dynamic changes in shape, intensity, and motion. They grow from small-scale bumps (seeds) at the poleward boundary of preexisting east-west-aligned auroras, rather than via the rotation or shear motion of preexisting east-west-aligned auroras, and do not exhibit any shear motion during the periods of auroral activity growth. Furthermore, the auroral luminosity is observed to increase during the declining period, and the total time from the start of the growth period to the end of the declining period is found to be about 20 min. Such dynamical signatures may be important in determining the mechanism responsible for omega band formation.

  14. Discovery of Diffuse Aurora on Mars

    NASA Astrophysics Data System (ADS)

    Stiepen, A.; Schneider, N. M.; Jain, S. K.; Deighan, J.; Stewart, A. I. F.; Evans, J. S.; Stevens, M. H.; Larson, D.; Mitchell, D.; Montmessin, F.; Chaffin, M. H.; McClintock, W. E.; Clarke, J. T.; Holsclaw, G. M.; Jakosky, B. M.

    2015-10-01

    The Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2014) onboard the MAVEN spacecraft has discovered diffuse aurora in Mars'northern hemisphere spanning a wide range of geographic latitudes and longitudes (Figure 1). This widespread aurora differs from the small auroral patches discovered by the SPICAM instrument onboard the Mars Express spacecraft (Bertaux et al., 2005; Leblanc et al., 2008; Gérard et al., submitted; Soret et al., submitted) restricted to regions of crustal magnetic fields in the southern hemisphere. Furthermore, the northern diffuse aurora appears to peak at altitudes below 100 km, while the crustal field aurora peaked around 120 km.

  15. Mitotic mechanics: the auroras come into view.

    PubMed

    Andrews, Paul D; Knatko, Elena; Moore, William J; Swedlow, Jason R

    2003-12-01

    Aurora kinases have recently taken centre stage in the regulation of key cell cycle processes. Aurora A is emerging as a critical regulator of centrosome and spindle function. Aurora B mediates chromosome segregation by ensuring proper biorientation of sister chromatids, possibly through the regulation of microtubule dynamics. This enzyme also functions in cytokinesis apparently by interacting with a critical GTPase and a kinesin-like protein. Recent work on both kinases has revealed functional links between Aurora kinase activity and the mechanics of cell division.

  16. Aurora europe's space exploration programme

    NASA Astrophysics Data System (ADS)

    Ongaro, F.; Swings, J. P.; Condessa, R.

    2003-04-01

    What will happen after the ISS in terms of space exploration, specifically to the human presence beyond Earth? What will be the role of Europe in the future international venture to explore space? What are the most immediate actions to be undertaken in Europe in order to best profit from the efforts made through the participation in the ISS and to position Europe's capabilities according to its interests? As approved by the Ministers at the Edinburgh Council in November 2001, the European Space Exploration Programme - Aurora - is ESA's programme in charge of defining and implementing the long term plan for human and robotic exploration of the Solar system. The Aurora programme started in 2002 and extends until the end goal of Aurora: the first human mission to Mars, expected in the 2025-2030 time-frame. The approach of Aurora is to implement a robust development of technologies and robotic missions, in parallel to the utilization phase of the ISS, to prepare for a continuous and sustainable future of human space exploration (which shall include the Moon, Mars and the asteroids as targets), in which Europe will be a valuable partner. Two classes of missions are foreseen in the programme's strategy: Flagships, defined as major missions driving to soft landing, in-situ analysis, sample return from other planetary bodies and eventually human missions; and Arrows, defined as cost-capped, short development time missions to demonstrate new technologies or mission approaches, or to exploit opportunities for payloads on European or international missions. So far the participating national delegations have approved two Flagships (ExoMars and Mars Sample Return) and two Arrows (Earth Re-entry and Mars Aerocapture) for phase A industrial studies. Although the last call for ideas of Aurora resulted in the definition of two Flagship missions targeted to Mars, the next one might be aimed to the Moon. At this stage the role of the Moon, on the path of Mars exploration is not

  17. Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle

    PubMed Central

    Hochegger, Helfrid; Hégarat, Nadia; Pereira-Leal, Jose B.

    2013-01-01

    The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules. PMID:23516109

  18. Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle.

    PubMed

    Hochegger, Helfrid; Hégarat, Nadia; Pereira-Leal, Jose B

    2013-03-20

    The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules.

  19. Aurora University: Cornerstone for Community Partnerships.

    ERIC Educational Resources Information Center

    Wasicsko, M. Mark; And Others

    1996-01-01

    Out of a 1995 meeting of local educational stakeholders, the Aurora (Illinois) Online Community Network was born. The purpose was to share resources among schools, colleges, and other educational organizations and learn about the Internet. Aurora University shared its technological expertise with the community, initiated a cooperative master's…

  20. Aurora University: Cornerstone for Community Partnerships.

    ERIC Educational Resources Information Center

    Wasicsko, M. Mark; And Others

    1996-01-01

    Out of a 1995 meeting of local educational stakeholders, the Aurora (Illinois) Online Community Network was born. The purpose was to share resources among schools, colleges, and other educational organizations and learn about the Internet. Aurora University shared its technological expertise with the community, initiated a cooperative master's…

  1. Generation of proton aurora by magnetosonic waves

    PubMed Central

    Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

    2014-01-01

    Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2–10 keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora. PMID:24898626

  2. Generation of proton aurora by magnetosonic waves.

    PubMed

    Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

    2014-06-05

    Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2-10 keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora.

  3. Uranus's auroras observed from Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-05-01

    New observations from the Hubble Space Telescope provide the first ever images of Uranus's auroras. The new observations, described by Lamy et al., are also the first unambiguous detections of Uranus's auroras since they were first discovered using the Voyager 2 spacecraft, which few by the planet in 1986. Auroras arise from the solar wind's interaction with a planet's magnetosphere. Uranus's magnetosphere, which is not well studied, is unusual because the planet's magnetic axis is both offset and sharply tilted with respect to the planet's spin axis. The newly detected auroras, seen on the dayside of the planet in November 2011, are quite different from Earth's—Uranus's auroras were faint dots of light that lasted online a few minutes, unlike the dancing colored curtains organized along rings of emissions around Earth's magnetic poles, intensified on the nightside and lasting for hours. (Geophysical Research Letters, doi:10.1029/ 2012GL051312, 2012)

  4. Aurorae: The earliest datable observation of the aurora borealis

    NASA Astrophysics Data System (ADS)

    Stephenson, F. Richard; Willis, David M.; Hallinan, Thomas J.

    2004-12-01

    The Late Babylonian astronomical texts, discovered at the site of Babylon (32.5°N, 44.4°E) more than a century ago, contain what is probably the earliest reliable account of the aurora borealis. A clay tablet recording numerous celestial observations made by the official astronomers during the 37th year of King Nebuchadnezzar II (568/567 BC) describes an unusual ``red glow'' in the sky at night; the exact date of this observation corresponds to the night of 12/13 March in 567 BC. The most likely interpretation of the phenomenon is an auroral display. This event occurred several centuries before the first clearly identifiable observation of the aurora from elsewhere in the world, namely China in 193 BC. The Babylonian auroral observation is remarkable in the sense that it is one of a series of carefully recorded astronomical observations, for each of which the year, month and day are known precisely. This observation occurred at a time when the geomagnetic (dipole) latitude of Babylon was about 41°N compared with the present value of 27.5°N, suggesting a higher auroral incidence at Babylon in 567 BC than at present.

  5. Global seasonal variations of midday planetary boundary layer depth from CALIPSO space-borne LIDAR

    NASA Astrophysics Data System (ADS)

    McGrath-Spangler, Erica L.; Denning, A. Scott

    2013-02-01

    We present a new global analysis of the depth of the planetary boundary layer (PBL) and consider regional variations throughout the year. PBL depth is estimated from the vertical variance of CALIPSO space-borne LIDAR backscatter associated with aerosol and shallow clouds during midday satellite overpasses and is only retrieved in the absence of optically thick clouds. The resulting analysis of over 100 million retrievals per year is therefore only a sample with higher frequency over deserts and other regions of strong subsidence, and lower frequency over regions of deep convection such as the ITCZ, tropical rainforests, and the Asian Monsoon. The mean of sampled PBL depths ranges from 500 m over cold oceans to more than 3000 m over hot deserts. The seasonal cycle of analyzed PBL depth is stronger over land than over water, and seasonality over land and midlatitude oceans is of opposite sign. Wintertime storm tracks and stratocumulus regions over subtropical oceans are prominent features of the analysis. Although evaluation of the new analysis is difficult due to previous sparse sampling by other methods, comparison of LIDAR-retrieved PBL depth with data collected by commercial aircraft generally shows good agreement.

  6. The cyanobacterial circadian clock follows midday in vivo and in vitro

    PubMed Central

    Leypunskiy, Eugene; Lin, Jenny; Yoo, Haneul; Lee, UnJin; Dinner, Aaron R; Rust, Michael J

    2017-01-01

    Circadian rhythms are biological oscillations that schedule daily changes in physiology. Outside the laboratory, circadian clocks do not generally free-run but are driven by daily cues whose timing varies with the seasons. The principles that determine how circadian clocks align to these external cycles are not well understood. Here, we report experimental platforms for driving the cyanobacterial circadian clock both in vivo and in vitro. We find that the phase of the circadian rhythm follows a simple scaling law in light-dark cycles, tracking midday across conditions with variable day length. The core biochemical oscillator comprised of the Kai proteins behaves similarly when driven by metabolic pulses in vitro, indicating that such dynamics are intrinsic to these proteins. We develop a general mathematical framework based on instantaneous transformation of the clock cycle by external cues, which successfully predicts clock behavior under many cycling environments. DOI: http://dx.doi.org/10.7554/eLife.23539.001 PMID:28686160

  7. Time Spent Outdoors at Midday and Children’s Body Mass Index

    PubMed Central

    Milne, Elizabeth; Simpson, Julie A.; Johnston, Robyn; Giles-Corti, Billie; English, Dallas R.

    2007-01-01

    Objectives. We investigated whether the Kidskin sun protection intervention increased children’s body mass index by reducing the time spent outdoors at midday. Methods. The Kidskin sun protection intervention involved 1614 Australian school children assigned to 1 of 3 groups: a control group, a moderate-intervention group, or a high-intervention group. Schools in the control group received the standard health curriculum and schools in the intervention groups received a multicomponent intervention. Outcomes included time spent outdoors and nevus development (a marker of melanoma risk). Height and weight were measured at 3 time points. Body mass index was transformed into age- and gender-specific z scores; z scores at each age were modeled simultaneously. Time spent outdoors at ages 10 and 12 years was analyzed using a linear mixed effects modeling. Results. The proportion of children who were overweight or obese increased with age. The moderate-intervention and control groups had a minimal increase in z score over time, and the z score for the high-intervention group decreased over time. There were no differences among groups with respect to total time outdoors at any age. Conclusions. It is possible to reduce the time children spend outdoors when ultraviolet radiation is high without producing an unfavorable effect on the children’s body mass index. PMID:17194858

  8. Nature's Fireworks: The Inner Workings of the Auroras.

    ERIC Educational Resources Information Center

    Kikoyin, A. K.

    1992-01-01

    Describes the great variety of observations surrounding the auroras (both borealis and australis), and provides photographs from the space shuttle, Discovery. Discusses where and when the auroras can be observed, the process that the Earth's magnetic phenomena fulfill in how and why auroras appear, and the effects of solar wind upon auroras. (JJK)

  9. Validating Aurora B as an anti-cancer drug target.

    PubMed

    Girdler, Fiona; Gascoigne, Karen E; Eyers, Patrick A; Hartmuth, Sonya; Crafter, Claire; Foote, Kevin M; Keen, Nicholas J; Taylor, Stephen S

    2006-09-01

    The Aurora kinases, a family of mitotic regulators, have received much attention as potential targets for novel anti-cancer therapeutics. Several Aurora kinase inhibitors have been described including ZM447439, which prevents chromosome alignment, spindle checkpoint function and cytokinesis. Subsequently, ZM447439-treated cells exit mitosis without dividing and lose viability. Because ZM447439 inhibits both Aurora A and B, we set out to determine which phenotypes are due to inhibition of which kinase. Using molecular genetic approaches, we show that inhibition of Aurora B kinase activity phenocopies ZM447439. Furthermore, a novel ZM compound, which is 100 times more selective for Aurora B over Aurora A in vitro, induces identical phenotypes. Importantly, inhibition of Aurora B kinase activity induces a penetrant anti-proliferative phenotype, indicating that Aurora B is an attractive anti-cancer drug target. Using molecular genetic and chemical-genetic approaches, we also probe the role of Aurora A kinase activity. We show that simultaneous repression of Aurora A plus induction of a catalytic mutant induces a monopolar phenotype. Consistently, another novel ZM-related inhibitor, which is 20 times as potent against Aurora A compared with ZM447439, induces a monopolar phenotype. Expression of a drug-resistant Aurora A mutant reverts this phenotype, demonstrating that Aurora A kinase activity is required for spindle bipolarity in human cells. Because small molecule-mediated inhibition of Aurora A and Aurora B yields distinct phenotypes, our observations indicate that the Auroras may present two avenues for anti-cancer drug discovery.

  10. Nature's Fireworks: The Inner Workings of the Auroras.

    ERIC Educational Resources Information Center

    Kikoyin, A. K.

    1992-01-01

    Describes the great variety of observations surrounding the auroras (both borealis and australis), and provides photographs from the space shuttle, Discovery. Discusses where and when the auroras can be observed, the process that the Earth's magnetic phenomena fulfill in how and why auroras appear, and the effects of solar wind upon auroras. (JJK)

  11. Aurora over the Southern Hemisphere

    NASA Image and Video Library

    1985-05-02

    51B-116-005 (29 April - 6 May 1985) --- Astronaut Don L. Lind, mission specialist, termed this scene of an aurora in the Southern Hemisphere as "spectacular," during a TV down link featuring discussion of the auroral observations on the seven-day flight. This scene was captured by astronaut Robert F. Overmyer, crew commander, using a 35mm camera. Dr. Lind, monitoring activity in the magnetosphere at various points throughout the flight, pinpointed the spacecraft's location as being over a point halfway between Australia and the Antarctic continent. There are moonlit clouds on Earth. The blue-green band and the tall red rays are aurora. The brownish band parallel to the Earth's horizon is a luminescence of the atmosphere itself and is referred to as airglow. Dr. T. Hallinan of the Geophysical Institute of Fairbanks serves as principal investigator for the auroral observations experiment and spent a great deal of time with Dr. Lind in preparation for the flight. Photo credit: NASA

  12. Time Series of Jupiter Aurora

    NASA Image and Video Library

    1998-06-10

    These mosaics of Jupiter's night side show the Jovian aurora at approximately 45 minute intervals as the auroral ring rotated with the planet below the spacecraft. The images were obtained by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. during its eleventh orbit of Jupiter. The auroral ring is offset from Jupiter's pole of rotation and reaches the lowest latitude near 165 degrees west longitude. The aurora is hundreds of kilometers wide, and when it crosses the edge of Jupiter, it is about 250 kilometers above the planet. As on Earth, the auroral emission is caused by electrically charged particles striking atoms in the upper atmosphere from above. The particles travel along Jupiter's magnetic field lines, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image. In multispectral observations the aurora appears red, consistent with how atomic hydrogen in Jupiter's atmosphere would glow. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in this sequence of Galileo images. In the first mosaic, the auroral ring is directly over Jupiter's limb and is seen "edge on." In the fifth mosaic, the auroral emission is coming from several distinct bands. This mosaic also shows the footprint of the Io flux tube. Volcanic eruptions on Jupiter's moon, Io, spew forth particles that become ionized and are pulled into Jupiter's magnetic field to form an invisible tube, the Io flux tube, between Jupiter and Io. The bright circular feature towards the lower right may mark the location where these energetic particles impact Jupiter. Stars

  13. Occurrence and average behavior of pulsating aurora

    NASA Astrophysics Data System (ADS)

    Partamies, N.; Whiter, D.; Kadokura, A.; Kauristie, K.; Nesse Tyssøy, H.; Massetti, S.; Stauning, P.; Raita, T.

    2017-05-01

    Motivated by recent event studies and modeling efforts on pulsating aurora, which conclude that the precipitation energy during these events is high enough to cause significant chemical changes in the mesosphere, this study looks for the bulk behavior of auroral pulsations. Based on about 400 pulsating aurora events, we outline the typical duration, geomagnetic conditions, and change in the peak emission height for the events. We show that the auroral peak emission height for both green and blue emission decreases by about 8 km at the start of the pulsating aurora interval. This brings the hardest 10% of the electrons down to about 90 km altitude. The median duration of pulsating aurora is about 1.4 h. This value is a conservative estimate since in many cases the end of event is limited by the end of auroral imaging for the night or the aurora drifting out of the camera field of view. The longest durations of auroral pulsations are observed during events which start within the substorm recovery phases. As a result, the geomagnetic indices are not able to describe pulsating aurora. Simultaneous Antarctic auroral images were found for 10 pulsating aurora events. In eight cases auroral pulsations were seen in the southern hemispheric data as well, suggesting an equatorial precipitation source and a frequent interhemispheric occurrence. The long lifetimes of pulsating aurora, their interhemispheric occurrence, and the relatively high-precipitation energies make this type of aurora an effective energy deposition process which is easy to identify from the ground-based image data.

  14. Birkeland currents associated with optical aurora

    NASA Astrophysics Data System (ADS)

    Guo, W.; McEwen, D. J.; Clemmons, J. H.; Luehr, H.

    1999-01-01

    The location and magnitude of Birkeland currents associated with auroras were determined from an analysis of electron and magnetometer data from the Freja satellite during auroral overpasses in northern Saskatchewan. The upward field-aligned currents connected directly with the optical aurora. There were downward currents equatorward of the aurora in every case but for only 3 of 16 cases were there also poleward currents. The current carried by energetic electrons (.02 to 25 keV) accounted for only about 14 of the upward Birkeland current inferred, on average.

  15. Aurora Austrailis taken during Expedition Six

    NASA Image and Video Library

    2003-02-16

    ISS006-E-028961 (16 Feb. 2003) --- The Expedition Six crew enjoyed this green aurora dancing over the night side of the Earth just after sunset on February 16, 2003. The reds and blues of sunset light up the air layer to the west. The image was recorded with a 58 mm lens on a digital still camera. Because auroras follow Earth's magnetic field, they are observed at Earth's poles when the oxygen and nitrogen atoms start to glow when bombarded by charged particles coming from the sun. In a sense, auroras are the "neon lights" of the poles.

  16. The emperor of Japan and the aurora

    NASA Astrophysics Data System (ADS)

    Akasofu, S. I.

    On October 3, 1985, I gave a special lecture on the aurora for the Emperor of Japan in his palace in Tokyo. It seems the Emperor, a marine biologist, has an unusual interest in the aurora. After my slide presentation, he asked how we confirm ancient sighting reports of the aurora in Japan. He was not satisfied with my response that anomalous events in the sky were well documented in an ancient publication entitled Japanese Meteorological Data and asked further how one could confirm such sightings as auroral events. He was visibly pleased to learn that the dates of these sightings coincided with those recorded elsewhere in the world.

  17. Monohydrated Sulfates in Aurorae Chaos

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image of sulfate-containing deposits in Aurorae Chaos was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0653 UTC (2:53 a.m. EDT) on June 10, 2007, near 7.5 degrees south latitude, 327.25 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The region covered is roughly 12 kilometers (7.5 miles) wide at its narrowest point.

    Aurorae Chaos lies east of the Valles Marineris canyon system. Its western edge extends toward Capri and Eos Chasmata, while its eastern edge connects with Aureum Chaos. Some 750 kilometers (466 miles) wide, Aurorae Chaos is most likely the result of collapsed surface material that settled when subsurface ice or water was released.

    The top panel in the montage above shows the location of the CRISM image on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data covers an area featuring several knobs of erosion-resistant material at one end of what appears to be a large teardrop shaped plateau. Similar plateaus occur throughout the interior of Valles Marineris, and they are formed of younger, typically layered rocks that post-date formation of the canyon system. Many of the deposits contain sulfate-rich layers, hinting at ancient saltwater.

    The center left image, an infrared false color image, reveals a swath of light-colored material draped over the knobs. The center right image unveils the mineralogical composition of the area, with yellow representing monohydrated sulfates (sulfates with one water molecule incorporated into each molecule of the mineral).

    The lower two images are renderings of data draped over topography with 5 times vertical exaggeration. These images provide a view of the topography and reveal how the monohydrated sulfate-containing deposits drape over the knobs and also an outcrop in lower-elevation parts of the

  18. Twice daily (mid-day and evening) quadruple therapy for H. pylori infection in the United States.

    PubMed

    Graham, D Y; Belson, G; Abudayyeh, S; Osato, M S; Dore, M P; El-Zimaity, H M T

    2004-06-01

    Quadruple therapy provided inadequate eradication rate when given twice-a-day at breakfast and evening meals. To test twice daily (mid-day and evening) quadruple therapy for Helicobacter pylori eradication. This was a single-centre pilot study in which H. pylori-infected (positive histology and culture and RUT) patients were given 2 x 250 mg of metronidazole and 2 x 250 mg of tetracycline, two Pepto-Bismol tablets, plus one 20 mg rabeprazole tablet twice-a-day for 14 days. H. pylori status was confirmed 4 or more weeks after the end of therapy. Thirty-seven patients including 3 with peptic ulcer disease, 19 asymptomatic infected, 4 GERD, and 11 with NUD. Mid-day quadruple therapy was successful in 92.3% (95% CI: 79-98%) including 96.2% of those with metronidazole-susceptible strains, and in 83.3% (10/12) of those with metronidazole-resistant H. pylori. Compliance was 100% by pill count except in one individual who stopped medication after 12 days because of side-effects and who failed therapy. Moderate or greater side-effects were experienced by five patients. Twice-a-day, mid-day, quadruple therapy proved effective using the combination of bismuth subsalicylate and rabeprazole instead of bismuth subcitrate and omeprazole. Detailed studies of different formulations (e.g. 2 x 250 mg versus 1 x 500 mg of metronidazole or tetracycline) and timing of administration (breakfast and evening meal versus mid-day and evening meals) may result in significant improvements in H. pylori eradication regimens.

  19. Variability in the outer planet aurorae

    NASA Technical Reports Server (NTRS)

    Clarke, John T.

    1992-01-01

    Multiwavelength observations of the aurorae of the outer planets are reviewed emphasizing the findings on physical processes derived from specific wavelengths. The review examines features of the auroral zones such as ionospheric currents, atmospheric heating, and compositional changes in the aurorae of Jupiter, Saturn, Uranus, Neptune, and the earth for comparison. Jupiter's multiwavelength aurora receives special attention since recent observations shed light on the distribution of the UV auroral ovals, the spectroscopy of the UV auroral emissions, auroral dynamics and ion upwelling, and IR emission from auroral latitudes. The observational data on Jupiter facilitate the modeling of variability and detailed thermospheric and magnetospheric processes. Saturn can be studied by extending findings fron Jupiter's aurora, and deficiencies are found in the observational datasets for Neptune and Uranus.

  20. Determining the mechanism of cusp proton aurora

    PubMed Central

    Xiao, Fuliang; Zong, Qiugang; Su, Zhenpeng; Yang, Chang; He, Zhaoguo; Wang, Yongfu; Gao, Zhonglei

    2013-01-01

    Earth's cusp proton aurora occurs near the prenoon and is primarily produced by the precipitation of solar energetic (2–10 keV) protons. Cusp auroral precipitation provides a direct source of energy for the high-latitude dayside upper atmosphere, contributing to chemical composition change and global climate variability. Previous studies have indicated that magnetic reconnection allows solar energetic protons to cross the magnetopause and enter the cusp region, producing cusp auroral precipitation. However, energetic protons are easily trapped in the cusp region due to a minimum magnetic field existing there. Hence, the mechanism of cusp proton aurora has remained a significant challenge for tens of years. Based on the satellite data and calculations of diffusion equation, we demonstrate that EMIC waves can yield the trapped proton scattering that causes cusp proton aurora. This moves forward a step toward identifying the generation mechanism of cusp proton aurora. PMID:23575366

  1. Determining the mechanism of cusp proton aurora.

    PubMed

    Xiao, Fuliang; Zong, Qiugang; Su, Zhenpeng; Yang, Chang; He, Zhaoguo; Wang, Yongfu; Gao, Zhonglei

    2013-01-01

    Earth's cusp proton aurora occurs near the prenoon and is primarily produced by the precipitation of solar energetic (2-10 keV) protons. Cusp auroral precipitation provides a direct source of energy for the high-latitude dayside upper atmosphere, contributing to chemical composition change and global climate variability. Previous studies have indicated that magnetic reconnection allows solar energetic protons to cross the magnetopause and enter the cusp region, producing cusp auroral precipitation. However, energetic protons are easily trapped in the cusp region due to a minimum magnetic field existing there. Hence, the mechanism of cusp proton aurora has remained a significant challenge for tens of years. Based on the satellite data and calculations of diffusion equation, we demonstrate that EMIC waves can yield the trapped proton scattering that causes cusp proton aurora. This moves forward a step toward identifying the generation mechanism of cusp proton aurora.

  2. Variability in the outer planet aurorae

    NASA Technical Reports Server (NTRS)

    Clarke, John T.

    1992-01-01

    Multiwavelength observations of the aurorae of the outer planets are reviewed emphasizing the findings on physical processes derived from specific wavelengths. The review examines features of the auroral zones such as ionospheric currents, atmospheric heating, and compositional changes in the aurorae of Jupiter, Saturn, Uranus, Neptune, and the earth for comparison. Jupiter's multiwavelength aurora receives special attention since recent observations shed light on the distribution of the UV auroral ovals, the spectroscopy of the UV auroral emissions, auroral dynamics and ion upwelling, and IR emission from auroral latitudes. The observational data on Jupiter facilitate the modeling of variability and detailed thermospheric and magnetospheric processes. Saturn can be studied by extending findings fron Jupiter's aurora, and deficiencies are found in the observational datasets for Neptune and Uranus.

  3. Low Latitude Aurora: Index of Solar Activity

    NASA Astrophysics Data System (ADS)

    Bekli, M. R.; Aissani, D.; Chadou, I.

    2010-10-01

    Observations of aurora borealis at low latitudes are rare, and are clearly associated with high solar activity. In this paper, we analyze some details of the solar activity during the years 1769-1792. Moreover, we describe in detail three low latitude auroras. The first event was reported by ash-Shalati and observed in North Africa (1770 AD). The second and third events were reported by l'Abbé Mann and observed in Europe (1770 and 1777 AD).

  4. Aurorae Observed at the Canary Islands

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.

    2010-12-01

    Descriptions of eleven aurorae observed in the Canary Islands during the period 1770 - 2010 have been found in different documents. Most of them are coincident with periods of strong solar activity, with the geomagnetic latitude playing a minor role. Coronal mass ejections are the most probable solar source of these low-latitude events. The absence of low-latitude aurorae is verified in our sample during the Dalton Minimum and the first half of the twentieth century.

  5. Discovery of an aurora on Mars.

    PubMed

    Bertaux, Jean-Loup; Leblanc, François; Witasse, Olivier; Quemerais, Eric; Lilensten, Jean; Stern, S A; Sandel, B; Korablev, Oleg

    2005-06-09

    In the high-latitude regions of Earth, aurorae are the often-spectacular visual manifestation of the interaction between electrically charged particles (electrons, protons or ions) with the neutral upper atmosphere, as they precipitate along magnetic field lines. More generally, auroral emissions in planetary atmospheres "are those that result from the impact of particles other than photoelectrons" (ref. 1). Auroral activity has been found on all four giant planets possessing a magnetic field (Jupiter, Saturn, Uranus and Neptune), as well as on Venus, which has no magnetic field. On the nightside of Venus, atomic O emissions at 130.4 nm and 135.6 nm appear in bright patches of varying sizes and intensities, which are believed to be produced by electrons with energy <300 eV (ref. 7). Here we report the discovery of an aurora in the martian atmosphere, using the ultraviolet spectrometer SPICAM on board Mars Express. It corresponds to a distinct type of aurora not seen before in the Solar System: it is unlike aurorae at Earth and the giant planets, which lie at the foot of the intrinsic magnetic field lines near the magnetic poles, and unlike venusian auroras, which are diffuse, sometimes spreading over the entire disk. Instead, the martian aurora is a highly concentrated and localized emission controlled by magnetic field anomalies in the martian crust.

  6. Ubiquitin-Mediated Degradation of Aurora Kinases.

    PubMed

    Lindon, Catherine; Grant, Rhys; Min, Mingwei

    2015-01-01

    The Aurora kinases are essential regulators of mitosis in eukaryotes. In somatic cell divisions of higher eukaryotes, the paralogs Aurora kinase A (AurA) and Aurora kinase B (AurB) play non-overlapping roles that depend on their distinct spatiotemporal activities. These mitotic roles of Aurora kinases depend on their interactions with different partners that direct them to different mitotic destinations and different substrates: AurB is a component of the chromosome passenger complex that orchestrates the tasks of chromosome segregation and cytokinesis, while AurA has many known binding partners and mitotic roles, including a well-characterized interaction with TPX2 that mediates its role in mitotic spindle assembly. Beyond the spatial control conferred by different binding partners, Aurora kinases are subject to temporal control of their activation and inactivation. Ubiquitin-mediated proteolysis is a critical route to irreversible inactivation of these kinases, which must occur for ordered transition from mitosis back to interphase. Both AurA and AurB undergo targeted proteolysis after anaphase onset as substrates of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase, even while they continue to regulate steps during mitotic exit. Temporal control of Aurora kinase destruction ensures that AurB remains active at the midbody during cytokinesis long after AurA activity has been largely eliminated from the cell. Differential destruction of Aurora kinases is achieved despite the fact that they are targeted at the same time and by the same ubiquitin ligase, making these substrates an interesting case study for investigating molecular determinants of ubiquitin-mediated proteolysis in higher eukaryotes. The prevalence of Aurora overexpression in cancers and their potential as therapeutic targets add importance to the task of understanding the molecular determinants of Aurora kinase stability. Here, we review what is known about ubiquitin-mediated targeting

  7. Ubiquitin-Mediated Degradation of Aurora Kinases

    PubMed Central

    Lindon, Catherine; Grant, Rhys; Min, Mingwei

    2016-01-01

    The Aurora kinases are essential regulators of mitosis in eukaryotes. In somatic cell divisions of higher eukaryotes, the paralogs Aurora kinase A (AurA) and Aurora kinase B (AurB) play non-overlapping roles that depend on their distinct spatiotemporal activities. These mitotic roles of Aurora kinases depend on their interactions with different partners that direct them to different mitotic destinations and different substrates: AurB is a component of the chromosome passenger complex that orchestrates the tasks of chromosome segregation and cytokinesis, while AurA has many known binding partners and mitotic roles, including a well-characterized interaction with TPX2 that mediates its role in mitotic spindle assembly. Beyond the spatial control conferred by different binding partners, Aurora kinases are subject to temporal control of their activation and inactivation. Ubiquitin-mediated proteolysis is a critical route to irreversible inactivation of these kinases, which must occur for ordered transition from mitosis back to interphase. Both AurA and AurB undergo targeted proteolysis after anaphase onset as substrates of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase, even while they continue to regulate steps during mitotic exit. Temporal control of Aurora kinase destruction ensures that AurB remains active at the midbody during cytokinesis long after AurA activity has been largely eliminated from the cell. Differential destruction of Aurora kinases is achieved despite the fact that they are targeted at the same time and by the same ubiquitin ligase, making these substrates an interesting case study for investigating molecular determinants of ubiquitin-mediated proteolysis in higher eukaryotes. The prevalence of Aurora overexpression in cancers and their potential as therapeutic targets add importance to the task of understanding the molecular determinants of Aurora kinase stability. Here, we review what is known about ubiquitin-mediated targeting

  8. Making the Auroras glow: regulation of Aurora A and B kinase function by interacting proteins

    PubMed Central

    Carmena, Mar; Ruchaud, Sandrine; Earnshaw, William C

    2009-01-01

    The conserved Aurora family of protein kinases have emerged as crucial regulators of mitosis and cytokinesis. Despite their high degree of homology, Aurora A and B have very distinctive localisations and functions: Aurora A associates with the spindle poles to regulate entry into mitosis, centrosome maturation and spindle assembly; Aurora B is a member of the Chromosomal Passenger Complex (CPC) that transfers from the inner centromere in early mitosis to the spindle midzone, equatorial cortex and midbody in late mitosis and cytokinesis. Aurora B functions include regulation of chromosome–microtubule interactions, cohesion, spindle stability and cytokinesis. This review will focus on how interacting proteins make this functional diversity possible by targeting the kinases to different subcellular locations and regulating their activity. PMID:19836940

  9. Making the Auroras glow: regulation of Aurora A and B kinase function by interacting proteins.

    PubMed

    Carmena, Mar; Ruchaud, Sandrine; Earnshaw, William C

    2009-12-01

    The conserved Aurora family of protein kinases have emerged as crucial regulators of mitosis and cytokinesis. Despite their high degree of homology, Aurora A and B have very distinctive localisations and functions: Aurora A associates with the spindle poles to regulate entry into mitosis, centrosome maturation and spindle assembly; Aurora B is a member of the Chromosomal Passenger Complex (CPC) that transfers from the inner centromere in early mitosis to the spindle midzone, equatorial cortex and midbody in late mitosis and cytokinesis. Aurora B functions include regulation of chromosome-microtubule interactions, cohesion, spindle stability and cytokinesis. This review will focus on how interacting proteins make this functional diversity possible by targeting the kinases to different subcellular locations and regulating their activity.

  10. Hubble Images Reveal Jupiter's Auroras

    NASA Technical Reports Server (NTRS)

    1996-01-01

    These images, taken by the Hubble Space Telescope, reveal changes in Jupiter's auroral emissions and how small auroral spots just outside the emission rings are linked to the planet's volcanic moon, Io. The images represent the most sensitive and sharply-detailed views ever taken of Jovian auroras.

    The top panel pinpoints the effects of emissions from Io, which is about the size of Earth's moon. The black-and-white image on the left, taken in visible light, shows how Io and Jupiter are linked by an invisible electrical current of charged particles called a 'flux tube.' The particles - ejected from Io (the bright spot on Jupiter's right) by volcanic eruptions - flow along Jupiter's magnetic field lines, which thread through Io, to the planet's north and south magnetic poles. This image also shows the belts of clouds surrounding Jupiter as well as the Great Red Spot.

    The black-and-white image on the right, taken in ultraviolet light about 15 minutes later, shows Jupiter's auroral emissions at the north and south poles. Just outside these emissions are the auroral spots. Called 'footprints,' the spots are created when the particles in Io's 'flux tube' reach Jupiter's upper atmosphere and interact with hydrogen gas, making it fluoresce. In this image, Io is not observable because it is faint in the ultraviolet.

    The two ultraviolet images at the bottom of the picture show how the auroral emissions change in brightness and structure as Jupiter rotates. These false-color images also reveal how the magnetic field is offset from Jupiter's spin axis by 10 to 15 degrees. In the right image, the north auroral emission is rising over the left limb; the south auroral oval is beginning to set. The image on the left, obtained on a different date, shows a full view of the north aurora, with a strong emission inside the main auroral oval.

    The images were taken by the telescope's Wide Field and Planetary Camera 2 between May 1994 and September 1995.

    This image and

  11. Recognizing blue emission in artificial aurora

    NASA Astrophysics Data System (ADS)

    Holma, H.; Kaila, K.; Jussila, J.; Kosch, M.; Rietveld, M.

    On 12th November 2001, during the EISCAT UK/GE artificial aurora campaign, the optical group of University of Oulu performed the optical measurements at the EISCAT site in Ramfjordmoen. That campaign was the first successful attempt of inducing blue emission in artificial aurora at high latitudes. Optical instruments were monitoring emis-sions and they included a photometer, a real speed TV camera and a digital camera. The emissions measured by the photometer are 557.7 nm (OI), 630.0 nm (OI) and 427.8 nm (N2+). The threshold energies for these emissions to arise are 2 eV, 4 eV and 19 eV, re-spectively. In the natural aurora the blue emission at around 427 nm is always highly dominated by N2+ 1NG (0,1) rotational band. However, there are two weak emissions lying under this strong emission. These bands are N2 VK(4,15) (threshold energy 6 eV) and N2 2P(1,5) (threshold 11 eV). These energies are remarkably lower and could obviously have stronger intensity in the spectrum of artificial aurora than in natural aurora that is domi-nated by harder electron bombardment. The auroral photometer of the university of Oulu has been designed for investigating natural aurora, which results some limitations regarding the artificial aurora, to the data that has been obtained. The photometer was equipped with two channels measuring two close wavelength bands around 427 nm. These channels were aimed to be used to de-termine rotational temperature from the ratio of the intensities through the channels. Now they will be used to estimate the intensities of the three overlapping emission bands instead.

  12. Statistical study of dayside pulsating aurora

    NASA Astrophysics Data System (ADS)

    Kanmae, T.; Kadokura, A.; Ogawa, Y.; Ebihara, Y.; Motoba, T.; Gerrard, A. J.; Weatherwax, A. T.

    2015-12-01

    Pulsating aurora normally occurs after a substorm breakup in the midnight sector, often observed to persist through the morning sector and beyond. Indeed, it has also been observed on the dayside; however, the characteristics of the dayside pulsating aurora are poorly known. A handful of observational studies have been reported, but the results are somewhat disputable because most of the studies had non-uniform sampling of the dark dayside region. Furthermore, the previous studies used photometer data, with which the spatial characteristics of the pulsating aurora cannot be examined. To determine both temporal and spatial characteristics of the pulsating aurora, we have studied three years of all-sky image data obtained at the South Pole station. Because of its unique geographical location, the station has 24 hours of darkness during the austral winter from April to August, providing an ideal platform for studying dayside aurora. In a preliminary survey of the data, we have identified the pulsating auroras in 198 days out of 365 days of observations. The magnetic local time (MLT) distribution of the occurrence peaks between 9:00 and 11:00, but shows no or little dependence on the geomagnetic activity. In many events, pulsating patches initially appear as east-west aligned arc segments and later in the afternoon sector develop into large, diffuse patches, which occasionally fill a large part of the field of view. Using the long-term data, we will statistically examine both temporal (occurrence rate, duration and pulsation period) and spatial (sizes and shapes) characteristics of the dayside pulsating aurora.

  13. Evaluation of the Aurora Application Shade Measurement Accuracy

    SciTech Connect

    2015-12-01

    Aurora is an integrated, Web-based application that helps solar installers perform sales, engineering design, and financial analysis. One of Aurora's key features is its high-resolution remote shading analysis.

  14. Atmospheric physics: Chorus keeps the diffuse aurora humming

    NASA Astrophysics Data System (ADS)

    Newell, Patrick T.

    2010-10-01

    The origin of the diffuse aurora, whose beauty and intensity pale beside those of the famous aurora borealis, has remained controversial. A convincing explanation for this auroral display is now at hand. See Letter p.943

  15. Space- and ground-based observations of pulsating aurora

    NASA Astrophysics Data System (ADS)

    Jones, Sarah

    Pulsating aurora is a frequently occurring phenomenon generally believed to occur mainly in the aftermath of a substorm, resulting in widespread auroral luminosity corresponding to a significant transfer of power from the magnetosphere to the ionosphere. A handful of theories have been proposed to explain the associated precipitation mechanism, which have been shown to ineffectively explain certain aspects of pulsating aurora. Previous research into pulsating aurora has provided a wealth of observations, yet much remains unknown about this phenomenon and some previous observations are contradictory. The focus of this presentation is the analysis of ground- and space-based measurements of pulsating aurora (primarily THEMIS ASI array, Poker Flat ISR, and Rocket Observations of Pulsating Aurora) to provide information regarding the large-scale spatial and temporal evolution of pulsating aurora events and the relationship to substorms, to determine the altitude extent and precipitating electron distribution corresponding to pulsating aurora, and to understand commonly occurring features within pulsating aurora.

  16. Satellite Footprints Seen in Jupiter Aurora

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This is a spectacular NASA Hubble Space Telescope close-up view of an electric-blue aurora that is eerily glowing one half billion miles away on the giant planet Jupiter. Auroras are curtains of light resulting from high-energy electrons racing along the planet's magnetic field into the upper atmosphere. The electrons excite atmospheric gases, causing them to glow. The image shows the main oval of the aurora, which is centered on the magnetic north pole, plus more diffuse emissions inside the polar cap.

    Though the aurora resembles the same phenomenon that crowns Earth's polar regions, the Hubble image shows unique emissions from the magnetic 'footprints' of three of Jupiter's largest moons. (These points are reached by following Jupiter's magnetic field from each satellite down to the planet).

    Auroral footprints can be seen in this image from Io (along the lefthand limb), Ganymede (near the center), and Europa (just below and to the right of Ganymede's auroral footprint). These emissions, produced by electric currents generated by the satellites, flow along Jupiter's magnetic field, bouncing in and out of the upper atmosphere. They are unlike anything seen on Earth.

    This ultraviolet image of Jupiter was taken with the Hubble Space Telescope Imaging Spectrograph (STIS) on November 26, 1998. In this ultraviolet view, the aurora stands out clearly, but Jupiter's cloud structure is masked by haze.

    December 14, 2000 inaugurates an intensive two weeks of joint observation of Jupiter's aurora by Hubble and the Cassini spacecraft. Cassini will make its closest approach to Jupiter enroute to a July 2004 rendezvous with Saturn. A second campaign in January 2001 will consist of Hubble images of Jupiter's day-side aurora and Cassini images of Jupiter's night-side aurora, obtained just after Cassini has flown past Jupiter. The team will develop computer models that predict how the aurora operates, and this will yield new insights into the effects of the solar wind

  17. A Cell Biologist's Field Guide to Aurora Kinase Inhibitors.

    PubMed

    de Groot, Christian O; Hsia, Judy E; Anzola, John V; Motamedi, Amir; Yoon, Michelle; Wong, Yao Liang; Jenkins, David; Lee, Hyun J; Martinez, Mallory B; Davis, Robert L; Gahman, Timothy C; Desai, Arshad; Shiau, Andrew K

    2015-01-01

    Aurora kinases are essential for cell division and are frequently misregulated in human cancers. Based on their potential as cancer therapeutics, a plethora of small molecule Aurora kinase inhibitors have been developed, with a subset having been adopted as tools in cell biology. Here, we fill a gap in the characterization of Aurora kinase inhibitors by using biochemical and cell-based assays to systematically profile a panel of 10 commercially available compounds with reported selectivity for Aurora A (MLN8054, MLN8237, MK-5108, MK-8745, Genentech Aurora Inhibitor 1), Aurora B (Hesperadin, ZM447439, AZD1152-HQPA, GSK1070916), or Aurora A/B (VX-680). We quantify the in vitro effect of each inhibitor on the activity of Aurora A alone, as well as Aurora A and Aurora B bound to fragments of their activators, TPX2 and INCENP, respectively. We also report kinome profiling results for a subset of these compounds to highlight potential off-target effects. In a cellular context, we demonstrate that immunofluorescence-based detection of LATS2 and histone H3 phospho-epitopes provides a facile and reliable means to assess potency and specificity of Aurora A versus Aurora B inhibition, and that G2 duration measured in a live imaging assay is a specific readout of Aurora A activity. Our analysis also highlights variation between HeLa, U2OS, and hTERT-RPE1 cells that impacts selective Aurora A inhibition. For Aurora B, all four tested compounds exhibit excellent selectivity and do not significantly inhibit Aurora A at effective doses. For Aurora A, MK-5108 and MK-8745 are significantly more selective than the commonly used inhibitors MLN8054 and MLN8237. A crystal structure of an Aurora A/MK-5108 complex that we determined suggests the chemical basis for this higher specificity. Taken together, our quantitative biochemical and cell-based analyses indicate that AZD1152-HQPA and MK-8745 are the best current tools for selectively inhibiting Aurora B and Aurora A, respectively

  18. Latitudinal motions of the aurora during substorms

    NASA Technical Reports Server (NTRS)

    Craven, J. D.; Frank, L. A.

    1987-01-01

    Sequences of auroral images obtained with Dynamics Explorer 1 are used to investigate latitudinal motions of the aurora in substorms. Average speeds of poleward motion are about 230 m/s near local midnight for two isolated, small substorms and about 1000 m/s during an intensification within a previously active auroral oval. The speed of poleward expansion measured at about 6-min temporal resolution can differ greatly from the average speed because of the episodic development of substorms. Recovery of the high-latitude boundary of the aurora to presubstorm latitudes is first observed in the postmidnight sector. In the premidnight sector the discrete aurora can become stationary for a period of time or even continue further poleward before a retreat to lower latitudes begins. During the recovery phase, a prominent decrease in luminosities is first observed at intermediate latitudes within the auroral distribution. This region is bounded at higher latitudes by the discrete aurora and at lower latitudes by bright diffuse aurora. Given that magnetic field lines threading these auroral distributions map to the plasma sheet boundary layer and to the central plasma sheet, respectively, magnetic field lines at the intermediate auroral latitudes then map to the plasma sheet at distances of more than about 22 earth radii.

  19. Breakfast, midday meals and academic achievement in rural primary schools in Uganda: implications for education and school health policy

    PubMed Central

    Acham, Hedwig; Kikafunda, Joyce K.; Malde, Marian K.; Oldewage-Theron, Wilna H.; Egal, AbdulKadir A.

    2012-01-01

    Background Underachievement in schools is a global problem and is especially prevalent in developing countries. Indicators of educational performance show that Uganda has done remarkably well on education access-related targets since the introduction of universal primary education in 1997. However, educational outcomes remain disappointing. The absence of school feeding schemes, one of the leading causes of scholastic underachievement, has not been given attention by the Ugandan authorities. Instead, as a national policy, parents are expected to provide meals even though many, especially in the rural areas, cannot afford to provide even the minimal daily bowl of maize porridge. Objective To assess and demonstrate the effect of breakfast and midday meal consumption on academic achievement of schoolchildren. Design, Materials and Methods We assessed household characteristics, feeding patterns and academic achievement of 645 schoolchildren (aged 9–15 years) in Kumi district, eastern Uganda, in 2006–2007, using a modified cluster sampling design which involved only grade 1 schools (34 in total) and pupils of grade four. Household questionnaires and school records were used to collect information on socio-demographic factors, feeding patterns and school attendance. Academic achievement was assessed using unstandardized techniques, specifically designed for this study. Results Underachievement (the proportion below a score of 120.0 points) was high (68.4%); in addition, significantly higher achievement and better feeding patterns were observed among children from the less poor households (p<0.05). Achievement was significantly associated with consumption of breakfast and a midday meal, particularly for boys (p<0.05), and a greater likelihood of scoring well was observed for better nourished children (all OR values>1.0). Conclusion We observed that underachievement was relatively high; inadequate patterns of meal consumption, particularly for the most poor

  20. FBXW7 is involved in Aurora B degradation

    PubMed Central

    Teng, Chieh-Lin; Hsieh, Yun-Chi; Phan, Liem; Shin, Jihyun; Gully, Chris; Velazquez-Torres, Guermarie; Skerl, Stephen; Yeung, Sai-Ching J.; Hsu, Shih-Lan; Lee, Mong-Hong

    2012-01-01

    FBXW7, a component of E3 ubiquitin ligase, plays an important role in mitotic checkpoint, but its role remains unclear. Aurora B is a mitotic checkpoint kinase that plays a pivotal role in mitosis by ensuring correct chromosome segregation and normal progression through mitosis. Whether Aurora B and FBXW7 are coordinately regulated during mitosis is not known. Here, we show that FBXW7 is a negative regulator for Aurora B. Ectopic expression of FBXW7 can suppress the expression of Aurora B. Accordingly, FBXW7 deficiency leads to Aurora B elevation. Mechanistic studies show that all FBXW7 isoforms are negative regulators of Aurora B expression through ubiquitination-mediated protein degradation. Aurora B interacts with R465 and R505 residues of WD 40 domain of FBXW7. Significantly, inverse correlation between FBXW7 and Aurora B elevation is translated into the deregulation of mitosis. FBWX7 expression mitigates Aurora B-mediated cell growth and mitotic deregulation. In addition, FBXW7 reduces the percentage of multinucleated cells caused by Aurora B overexpression. These data suggest that FBXW7 is an important negative regulator of Aurora B, and that the loss or mutation of FBXW7 as seen in many types of cancer could lead to an abnormal elevation of Aurora B and result in deregulated mitosis, which accelerates cancer cell growth. PMID:23095493

  1. Hubble Provides Clear Images of Saturn's Aurora

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This is the first image of Saturn's ultraviolet aurora taken by the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST) in October 1998, when Saturn was a distance of 810 million miles (1.3 billion kilometers) from Earth. The new instrument, used as a camera, provides more than 10 times the sensitivity of the previous HST instruments in the ultraviolet. STIS images reveal exquisite detail never before seen in the spectacular auroral curtains of light that encircle Saturn's north and south poles which rise more than a thousand miles above the cloud tops. Saturn's auroral displays are caused by an energetic wind from the Sun that sweeps over the planet, much like the Earth's aurora that is occasionally seen in the nighttime sky. Unlike the Earth, Saturn's aurora is only seen in ultraviolet light that is invisible from the Earth's surface, hence can only be observed from space.

  2. Discovery of diffuse aurora on Mars.

    PubMed

    Schneider, N M; Deighan, J I; Jain, S K; Stiepen, A; Stewart, A I F; Larson, D; Mitchell, D L; Mazelle, C; Lee, C O; Lillis, R J; Evans, J S; Brain, D; Stevens, M H; McClintock, W E; Chaffin, M S; Crismani, M; Holsclaw, G M; Lefevre, F; Lo, D Y; Clarke, J T; Montmessin, F; Jakosky, B M

    2015-11-06

    Planetary auroras reveal the complex interplay between an atmosphere and the surrounding plasma environment. We report the discovery of low-altitude, diffuse auroras spanning much of Mars' northern hemisphere, coincident with a solar energetic particle outburst. The Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, detected auroral emission in virtually all nightside observations for ~5 days, spanning nearly all geographic longitudes. Emission extended down to ~60 kilometer (km) altitude (1 microbar), deeper than confirmed at any other planet. Solar energetic particles were observed up to 200 kilo--electron volts; these particles are capable of penetrating down to the 60 km altitude. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit auroras more globally than Earth.

  3. Recognizing the blue emission in artificial aurora

    NASA Astrophysics Data System (ADS)

    Holma, H.; Kaila, K. U.; Kosch, M. J.; Rietveld, M. T.

    2006-01-01

    On 12th November 2001, during an EISCAT UK/GE artificial aurora campaign, the optical group from the University of Oulu performed optical measurements at the EISCAT site in Ramfjordmoen, including the first measurement of blue emissions in artificial aurora at high latitudes. Optical instruments, including a photometer, a real speed TV camera and a digital camera, were monitoring the emissions. The emissions that the photometer was designed to measure were 557.7 nm (OI), 630.0 nm (OI) and 427.8 nm (N2+). The energy thresholds of these emissions are approximately 2, 4 and 19 eV, respectively. In the natural aurora the blue emission at around 427.8 nm is always dominated by the N2+ 1NG(0, 1) band. However, there are two weak emission bands lying under this strong emission, namely, the N2 VK(4, 15) (threshold energy 6 eV) and N2 2P(1, 5) (threshold 11 eV). These excitation energies are lower than the energy needed to excite N2+ 1NG(0, 1) level and therefore could have a stronger intensity compared with N2+ 1NG(0, 1) in the spectrum of artificial aurora than in natural aurora. The auroral photometer of the University of Oulu has been designed for investigating natural aurora. The photometer was equipped with two channels measuring different wavelength bands around 427.8 nm. These channels were intended to be used to determine rotational temperature from the ratio of the intensities through the channels. However, here we estimate the intensities of the three overlapping emission bands instead.

  4. A new theory of the aurora

    NASA Astrophysics Data System (ADS)

    Bryant, D. A.

    1993-03-01

    Experiments made using sounding rockets have played a key role in studying the physics of the aurora. The development of a theory to explain the acceleration of the electrons responsible for one of the most striking and highly characteristic forms of aurora - the auroral arc - in terms of acceleration through a potential difference is outlined and fundamental difficulties with this theory are discussed. A new theory in which acceleration is caused by electrostatic waves is examined and found to provide a promising explanation of this key problem in space plasma physics. The techniques by which the measurements are obtained in such experiments are summarized.

  5. Dynamics of the dayside Aurora Australis

    NASA Astrophysics Data System (ADS)

    McEwen, D. J.; Sivjee, G. G.; Azeem, S. I.

    2010-01-01

    Current dayside optical studies of Aurora Australis from the Amundsen-Scott Research Station at the South Pole (74 degrees magnetic latitude) show some striking differences from optical results reported from Svalbard. A 6-channel meridian scanning photometer operating during the past three austral winters shows, in particular, the 630 nm emission is much lower, on average, than the Arctic dayside aurora and very weak on some days. The 558 nm intensity is higher relative to 630 nm suggesting the incoming electrons have a higher average energy. There are notable differences in auroral forms, giving further evidence of asymmetries in the two dayside ovals.

  6. The first accurate description of an aurora

    NASA Astrophysics Data System (ADS)

    Schröder, Wilfried

    2006-12-01

    As technology has advanced, the scientific study of auroral phenomena has increased by leaps and bounds. A look back at the earliest descriptions of aurorae offers an interesting look into how medieval scholars viewed the subjects that we study.Although there are earlier fragmentary references in the literature, the first accurate description of the aurora borealis appears to be that published by the German Catholic scholar Konrad von Megenberg (1309-1374) in his book Das Buch der Natur (The Book of Nature). The book was written between 1349 and 1350.

  7. Enhanced-rise-time bremsstrahlung Aurora environment

    SciTech Connect

    Bushell, M.; Graybill, S.; Litz, M.; Merkel, G.

    1984-12-01

    The technique of beam nose erosion has been employed at the Aurora flash x-ray machine to obtain a modified bremsstrahlung pulse with a shorter rise time. When the Aurora is operated in its conventional mode the individual thick target bremsstrahlung sources each have a rise time of about 40 to 50 nanoseconds. The modifications described here involve the insertion of a beam erosion chamber between one of the four anodes and its bremsstrahlung target. Bremsstrahlung rise times varied, depending on the anode-cathode gap and the chamber pressures, between 10 nanoseconds and 100 nanoseconds.

  8. Possible Role of Aurora-C in Meiosis.

    PubMed

    Yang, Kuo-Tai; Tang, Chieh-Ju C; Tang, Tang K

    2015-01-01

    The meiotic generation of haploid gametes with equal contents of genetic material is important for sexual reproduction in mammals. Errors in the transmission of chromosomes during meiosis may lead to aneuploidy, which is the leading cause of miscarriage and congenital birth defects in humans. The Aurora kinases, which include Aurora-A, Aurora-B, and Aurora-C, are highly conserved serine-threonine kinases that play essential roles in centrosome function, chromosome segregation, and cytokinesis during mitosis and meiosis. While Aurora-A and Aurora-B have been extensively studied in mitosis, the role of Aurora-C in meiosis is only now starting to be revealed. For example, the perturbation of Aurora-C kinase activity by microinjection of Aurora-C-kinase-dead mutant mRNAs into mouse oocytes induced multiple defects, including chromosome misalignment, abnormal kinetochore-microtubule attachment, premature chromosome segregation, and failure of cytokinesis during meiotic division. However, the analysis of such defects is complicated by the possibility that Aurora-B may be present in mammalian germ cells. Interestingly, a homozygous mutation of Aurora-C in humans leads to the production of large-headed polyploid spermatozoa and causes male infertility, but homozygous females are fertile. Mouse studies regarding the roles of Aurora-B and Aurora-C in female meiotic divisions have yielded inconsistent results, and it has proven difficult to explain why homozygous human females have no significant clinical phenotype. In this review, we will discuss the controversial status of Aurora-B in oocytes and the possible role of Aurora-C during meiotic division.

  9. Possible Role of Aurora-C in Meiosis

    PubMed Central

    Yang, Kuo-Tai; Tang, Chieh-Ju C.; Tang, Tang K.

    2015-01-01

    The meiotic generation of haploid gametes with equal contents of genetic material is important for sexual reproduction in mammals. Errors in the transmission of chromosomes during meiosis may lead to aneuploidy, which is the leading cause of miscarriage and congenital birth defects in humans. The Aurora kinases, which include Aurora-A, Aurora-B, and Aurora-C, are highly conserved serine–threonine kinases that play essential roles in centrosome function, chromosome segregation, and cytokinesis during mitosis and meiosis. While Aurora-A and Aurora-B have been extensively studied in mitosis, the role of Aurora-C in meiosis is only now starting to be revealed. For example, the perturbation of Aurora-C kinase activity by microinjection of Aurora-C-kinase-dead mutant mRNAs into mouse oocytes induced multiple defects, including chromosome misalignment, abnormal kinetochore–microtubule attachment, premature chromosome segregation, and failure of cytokinesis during meiotic division. However, the analysis of such defects is complicated by the possibility that Aurora-B may be present in mammalian germ cells. Interestingly, a homozygous mutation of Aurora-C in humans leads to the production of large-headed polyploid spermatozoa and causes male infertility, but homozygous females are fertile. Mouse studies regarding the roles of Aurora-B and Aurora-C in female meiotic divisions have yielded inconsistent results, and it has proven difficult to explain why homozygous human females have no significant clinical phenotype. In this review, we will discuss the controversial status of Aurora-B in oocytes and the possible role of Aurora-C during meiotic division. PMID:26322271

  10. Midday dew--an overlooked factor enhancing photosynthetic activity of corticolous epiphytes in a wet tropical rain forest.

    PubMed

    Lakatos, Michael; Obregón, André; Büdel, Burkhard; Bendix, Jörg

    2012-04-01

    • Additional water supplied by dew formation is an important resource for microbes, plants and animals in precipitation-limited habitats, but has received little attention in tropical forests until now. • We evaluated the micro-environmental conditions of tree stem surfaces and their epiphytic organisms in a neotropical forest, and present evidence for a novel mechanism of diurnal dew formation on these surfaces until midday that has physiological implications for corticolous epiphytes such as lichens. • In the understorey of a lowland forest in French Guiana, heat storage of stems during the day and delayed radiative loss during the night decreased stem surface temperatures by 6°C in comparison to the dew-point temperature of ambient air. This measured phenomenon induced modelled totals of diurnal dew formation between 0.29 and 0.69 mm d⁻¹ on the surface of the bark and the lichens until early afternoon. • Crustose lichens substantially benefit from this dew formation, because it prolongs photosynthetic activity. This previously unrecognized mechanism of midday dew formation contributes to the water supply of most corticolous organisms, and may be a general feature in forest habitats world-wide. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  11. Hubble Provides Clear Images of Saturn's Aurora

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This is the first image of Saturn's ultraviolet aurora taken by the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope in October 1997, when Saturn was a distance of 810 million miles (1.3 billion kilometers) from Earth. The new instrument, used as a camera, provides more than ten times the sensitivity of previous Hubble instruments in the ultraviolet. STIS images reveal exquisite detail never before seen in the spectacular auroral curtains of light that encircle Saturn's north and south poles and rise more than a thousand miles above the cloud tops.

    Saturn's auroral displays are caused by an energetic wind from the Sun that sweeps over the planet, much like the Earths aurora that is occasionally seen in the nighttime sky and similar to the phenomenon that causes fluorescent lamps to glow. But unlike the Earth, Saturn's aurora is only seen in ultraviolet light that is invisible from the Earths surface, hence the aurora can only be observed from space. New Hubble images reveal ripples and overall patterns that evolve slowly, appearing generally fixed in our view and independent of planet rotation. At the same time, the curtains show local brightening that often follow the rotation of the planet and exhibit rapid variations on time scales of minutes. These variations and regularities indicate that the aurora is primarily shaped and powered by a continual tug-of-war between Saturn's magnetic field and the flow of charged particles from the Sun.

    Study of the aurora on Saturn had its beginnings just seventeen years ago. The Pioneer 11 spacecraft observed a far-ultraviolet brightening on Saturn's poles in 1979. The Saturn flybys of the Voyager 1 and 2 spacecraft in the early 1980s provided a basic description of the aurora and mapped for the first time planets enormous magnetic field that guides energetic electrons into the atmosphere near the north and south poles.

    The first images of Saturn's aurora were provided in 1994-5 by the

  12. Clinical experience with aurora kinase inhibitors: a review.

    PubMed

    Boss, David S; Beijnen, Jos H; Schellens, Jan H M

    2009-08-01

    The aurora kinase family of serine/threonine kinases comprises three members, designated auroras A, B, and C. Auroras A and B are essential components of the mitotic pathway, ensuring proper chromosome assembly, formation of the mitotic spindle, and cytokinesis. The role of aurora C is less clear. Overexpression of aurora A and B has been observed in several tumor types, and has been linked with a poor prognosis of cancer patients. Several small molecules targeting aurora kinases A and B or both have been evaluated preclinically and in early phase I trials. In this review we aim to summarize the most recent advances in the development of aurora kinase inhibitors, with a focus on the clinical data.

  13. Aurora kinase targeted therapeutics in oncology: past, present and future.

    PubMed

    Mahadevan, Daruka; Beeck, Sunni

    2007-07-01

    Aurora A, B and C are a family of serine-threonine protein kinases that regulate distinct functions of the mitotic phase of the cell cycle. All three Auroras are overexpressed in human cancers with an associated polyploid phenotype. Crystal structures of Aurora A or B with bound small molecular inhibitors have provided detailed insight of the active site, mode of binding and hotspots for developing resistance through point mutations. Structural studies have aided fragment-based rational drug discovery of Aurora inhibitors, including compounds specific for Aurora A or B. Aurora inhibitors have excellent antitumor activity in rodent models of cancer. At present, Aurora inhibitors are being evaluated in Phase I trials. The future holds promise for rational combinations in both solid and hematological malignancies.

  14. Aurora Australis as seen from STS-62

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Aurora Australis or southern lights as seen from STS-62. The multi-hued shafts of light, extending upward to 200 miles above the Earth's surface, are caused by beams of energetic electrons colliding with the oxygen and nitrogen in the Earth's upper atmosphere.

  15. TL Aurora Night 500 mm lens

    NASA Image and Video Library

    2014-07-07

    ISS040-E-048011 (7 July 2014) --- One of the Expedition 40 crew members aboard the International Space Station, flying 226 nautical miles above the Indian Ocean, south of Australia, recorded this image of Aurora Australis or the Southern Lights on July 7, 2014.

  16. STS-47 view of the Aurora Australis

    NASA Image and Video Library

    1992-09-20

    STS047-20-015 (12-20 Sept. 1992) --- This 35mm frame represents one of the more spectacular views of Aurora Australis, photographed by the crew. The crew observed and photographed a great deal of auroral activity from the Earth-orbiting Space Shuttle Endeavour during the eight-day Spacelab-J mission.

  17. TL Aurora Night 500 mm lens

    NASA Image and Video Library

    2014-07-07

    ISS040-E-048027 (7 July 2014) --- One of the Expedition 40 crew members aboard the International Space Station, flying 226 nautical miles above the Indian Ocean, south of Australia, recorded this image of Aurora Australis or the Southern Lights on July 7, 2014.

  18. Proyecto Aurora: Building a Community of Women.

    ERIC Educational Resources Information Center

    Noya, Gladys R. Capella

    1997-01-01

    Describes the development of Proyecto Aurora, a program to develop and implement educational, support, and research programs to benefit low-income women in Puerto Rico. Portraits of some clients illustrate the rewards and challenges of working with this community and furthering their educational experiences and opportunities. (SLD)

  19. Learning with East Aurora Families. Project Evaluation.

    ERIC Educational Resources Information Center

    Bercovitz, Laura

    The Learning with East Aurora Families (LEAF) Project was a 1-year family literacy program developed and implemented by Waubonsee Community College in Sugar Grove, Illinois. It recruited 51 parents and other significant adults of 4- and 5-year-olds enrolled in at-risk programs. Each of the 4-week sessions were divided into 5 components: adult…

  20. Flickering aurora studies using high speed cameras

    NASA Astrophysics Data System (ADS)

    McHarg, M. G.; Stenbaek-Nielsen, H. C.; Samara, M.; Michell, R.; Hampton, D. L.; Haaland, R. K.

    2009-12-01

    We report on observations of flickering aurora using two different digital camera systems. The first, a high speed Phantom 7 camera with a Video Scope HS 1845 HS image intensifier coupled with an 50mm lens provides fast frame rates with data recorded at 200 and 400 frames per second with a 512x384 pixel, 11.8x8.8 degree FOV. The second system is an Andor Electron-Multiplying Charge Couple Device (EMCCD) running at 33 frames per second using a 256 by 256 format covering 16x16 degrees field of view. Both systems made observations of flickering aurora in the magnetic zenith, using optical filters transmitting the prompt blue and red emissions of nitrogen. The Andor system was deployed at the Poker Flat rocket range near Fairbanks AK, while the Phantom system was deployed approximately 400 miles north of Poker Flat at Toolik Lake observatory. We find both narrow band low frequency (~5-10 Hz) and wider band, higher frequency (50- 70 Hz) oscillations in the optical intensity of flickering aurora. Direct comparison of the optical data and the dispersion relation for ion cyclotron waves thought to be responsible for the modulation of electrons causing the intensity fluctuations seen in flickering aurora are presented.

  1. Aurora Australis as seen from STS-62

    NASA Image and Video Library

    1994-03-05

    STS062-58-025 (4-18 March) --- This photo shows the aurora australis or souther lights. The multi-hued shafts of light, extending upward to 200 miles above the earth's surface, are caused by beams of energetic electrons colliding with the oxygen and nitrogen in the earth's upper atmosphere. The strong red glow occurs at the highest altitude where the air is least dense and composed mostly of oxygen. At lower altitudes, the greater density favors the green color, also produced by atomic oxygen. Sometimes at the bottom (the lowest altitude of the aurora) a pink border is produced by nitrogen. The aurora usually can be seen only in Arctic regions. However, because of the tilt of the magnetic axis of the space shuttle mission orbits. One of these regions is over eastern North American, and the second one is south of Australia. Since most shuttle launches occur in daytime, the North American region is in daylight, and the only auroras that can be seen are usually in the Southern Hemisphere.

  2. Numerical Simulation for Generalized Aurora Computed Tomography

    NASA Astrophysics Data System (ADS)

    Tanaka, Y.; Aso, T.; Gustavsson, B.; Tanabe, K.; Kadokura, A.; Ogawa, Y.

    2007-12-01

    The conventional method of aurora tomographic inversion is extended to a more generalized aurora computed tomography (CT). The generalized aurora CT is the method to reconstruct energy distribution of auroral precipitating electrons from multimodal data, such as electron density enhancement from the EISCAT radar and cosmic noise absorption (CNA) from imaging riometer, as well as auroral images. In this study, we evaluate the feasibility of the generalized aurora CT by numerical simulation. The forward problem is based on model calculation of auroral emission and electron density enhancement for incident electrons and the mapping of the results to the instruments. Assuming the energy and spatial distributions of the incident electrons, the three-dimensional (3D) distributions of volume emission rate and electron density are calculated. The data observed with the ALIS (Auroral Large Imaging System) cameras, the EISCAT radar, and the imaging riometer are obtained by mapping the volume emission rate and electron density to each instrument. We attempt to retrieve the initial distribution of precipitating electrons from the simulated observational data. The inversion analysis is based on the Bayesian inference, in which the problem is formulated as the maximization problem of posterior probability. The results are compared between the reconstruction from only auroral images and that from multimodal data.

  3. Proyecto Aurora: Building a Community of Women.

    ERIC Educational Resources Information Center

    Noya, Gladys R. Capella

    1997-01-01

    Describes the development of Proyecto Aurora, a program to develop and implement educational, support, and research programs to benefit low-income women in Puerto Rico. Portraits of some clients illustrate the rewards and challenges of working with this community and furthering their educational experiences and opportunities. (SLD)

  4. The effect of midday moderate-intensity exercise on postexercise hypoglycemia risk in individuals with type 1 diabetes.

    PubMed

    Davey, Raymond J; Howe, Warwick; Paramalingam, Nirubasini; Ferreira, Luis D; Davis, Elizabeth A; Fournier, Paul A; Jones, Timothy W

    2013-07-01

    Exercise increases the risk of hypoglycemia in type 1 diabetes. Recently we reported a biphasic increase in glucose requirements to maintain euglycemia after late-afternoon exercise, suggesting a unique pattern of delayed risk for nocturnal hypoglycemia. This study examined whether this pattern of glucose requirements occurs if exercise is performed earlier in the day. Ten adolescents with type 1 diabetes underwent a hyperinsulinemic euglycemic glucose clamp on 2 different occasions during which they either rested or performed 45 minutes of moderate-intensity exercise at midday. Glucose was infused to maintain euglycemia for 17 hours after exercise. The glucose infusion rate (GIR) to maintain euglycemia, glucose rates of appearance and disappearance, and levels of counterregulatory hormones were compared between conditions. GIRs to maintain euglycemia were not significantly different between groups at baseline (9.8 ± 1.4 and 9.5 ± 1.6 g/h before the exercise and rest conditions, respectively) and did not change in the rest condition throughout the study. In contrast, GIR increased more than 3-fold during exercise (from 9.8 ± 1.4 to 30.6 ± 4.7 g/h), fell within the first hour of recovery, but remained elevated until 11 hours after exercise before returning to baseline levels. The pattern of glucose requirements to maintain euglycemia in response to moderate-intensity exercise performed at midday suggests that the risk of exercise-mediated hypoglycemia increases during and for several hours after moderate-intensity exercise, with no evidence of a biphasic pattern of postexercise risk of hypoglycemia.

  5. Longer Sleep Duration and Midday Napping Are Associated with a Higher Risk of CHD Incidence in Middle-Aged and Older Chinese: the Dongfeng-Tongji Cohort Study.

    PubMed

    Yang, Liangle; Yang, Handong; He, Meian; Pan, An; Li, Xiulou; Min, Xinwen; Zhang, Ce; Xu, Chengwei; Zhu, Xiaoyan; Yuan, Jing; Wei, Sheng; Miao, Xiaoping; Hu, Frank B; Wu, Tangchun; Zhang, Xiaomin

    2016-03-01

    To analyze the independent and combined relations of sleep duration and midday napping with coronary heart diseases (CHD) incidence along with the underlying changes of cardiovascular disease (CVD) risk factors among Chinese adults. We included 19,370 individuals aged 62.8 years at baseline from September 2008 to June 2010, and they were followed until October 2013. Cox proportional hazards models and general linear models were used for multivariate longitudinal analyses. Compared with sleeping 7- < 8 h/night, the hazard ratio (HR) of CHD incidence was 1.33 (95% CI = 1.10 to 1.62) for sleeping ≥ 10 h/night. The association was particularly evident among individuals who were normal weight and without diabetes. Similarly, the HR of incident CHD was 1.25 (95% CI = 1.05 to 1.49) for midday napping > 90 min compared with 1-30 min. When sleep duration and midday napping were combined, individuals having sleep duration ≥ 10 h and midday napping > 90 min were at a greater risk of CHD than those with sleeping 7- < 8 h and napping 1-30 min: the HR was 1.67 (95% CI = 1.04 to 2.66; P for trend = 0.017). In addition, longer sleep duration ≥ 10 h was significantly associated with increases in triglycerides and waist circumference, and a reduction in HDL-cholesterol; while longer midday napping > 90 min was related to increased waist circumference. Both longer sleep duration and midday napping were independently and jointly associated with a higher risk of CHD incidence, and altered lipid profile and waist circumference may partially explain the relationships. © 2016 Associated Professional Sleep Societies, LLC.

  6. Polo-like kinase-activating kinases: Aurora A, Aurora B and what else?

    PubMed

    Archambault, Vincent; Carmena, Mar

    2012-04-15

    The events of cell division are regulated by a complex interplay between kinases and phosphatases. Cyclin-dependent kinases (Cdks), polo-like kinases (Plks) and Aurora kinases play central roles in this process. Polo kinase (Plk1 in humans) regulates a wide range of events in mitosis and cytokinesis. To ensure the accuracy of these processes, polo activity itself is subject to complex regulation. Phosphorylation of polo in its T loop (or activation loop) increases its kinase activity several-fold. It has been shown that Aurora A kinase, with its co-factor Bora, activates Plk1 in G(2), and that this is essential for recovery from cell cycle arrest induced by DNA damage. In a recent article published in PLoS Biology, we report that Drosophila polo is activated by Aurora B kinase at centromeres, and that this is crucial for polo function in regulating chromosome dynamics in prometaphase. Our results suggest that this regulatory pathway is conserved in humans. Here, we propose a model for the collaboration between Aurora B and polo in the regulation of kinetochore attachment to microtubules in early mitosis. Moreover, we suggest that Aurora B could also function to activate Polo/Plk1 in cytokinesis. Finally, we discuss recent findings and open questions regarding the activation of polo and polo-like kinases by different kinases in mitosis, cytokinesis and other processes.

  7. Aurora A's Functions During Mitotic Exit: The Guess Who Game.

    PubMed

    Reboutier, David; Benaud, Christelle; Prigent, Claude

    2015-01-01

    Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog-specific version of Aurora A and small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms.

  8. Quercetin suppresses lung cancer growth by targeting Aurora B kinase.

    PubMed

    Xingyu, Zhu; Peijie, Ma; Dan, Peng; Youg, Wang; Daojun, Wang; Xinzheng, Chen; Xijun, Zhang; Yangrong, Song

    2016-11-01

    aurora B kinase is highly expressed in several cancer cells and promotes tumorigenesis and progression, and therefore, it is an important target for drug to treat tumors. Quercetin was identified to be an antitumor agent. Herein, we report for the first time that quercetin inhibited aurora B activities by directly binding with aurora B in vitro and in vivo. Ex vivo studies showed that quercetin inhibited aurora B activities in JB6 Cl41 cells and A549 lung cancer cells. Moreover, knockdown of aurora B in A549 cells decreased their sensitivities to quercetin. In vivo study demonstrated that injection of quercetin in A549 tumor-bearing mice effectively suppressed cancer growth. The phosphorylation of histone 3 in tumor tissues was also decreased after quercetin treatment. In short, quercetin can suppress growth of lung cancer cells as an aurora B inhibitor both in vitro and in vivo.

  9. Phosphoproteomic Analysis of Aurora Kinase Inhibition in Monopolar Cytokinesis.

    PubMed

    Polat, Ayse Nur; Karayel, Özge; Giese, Sven H; Harmanda, Büşra; Sanal, Erdem; Hu, Chi-Kuo; Renard, Bernhard Y; Özlü, Nurhan

    2015-09-04

    Cytokinesis is the last step of the cell cycle that requires coordinated activities of the microtubule cytoskeleton, actin cytoskeleton, and membrane compartments. Aurora B kinase is one of the master regulatory kinases that orchestrate multiple events during cytokinesis. To reveal targets of the Aurora B kinase, we combined quantitative mass spectrometry with chemical genetics. Using the quantitative proteomic approach, SILAC (stable isotope labeling with amino acids in cell culture), we analyzed the phosphoproteome of monopolar cytokinesis upon VX680- or AZD1152-mediated aurora kinase inhibition. In total, our analysis quantified over 20 000 phosphopeptides in response to the Aurora-B kinase inhibition; 246 unique phosphopeptides were significantly down-regulated and 74 were up-regulated. Our data provide a broad analysis of downstream effectors of Aurora kinase and offer insights into how Aurora kinase regulates cytokinesis.

  10. Jung's quest for the Aurora consurgens.

    PubMed

    Haaning, Aksel

    2014-02-01

    The paper focuses on the year 1929 when Jung published 'A European commentary' to Richard Wilhelm's German translation of the Taoist text The Secret of the Golden Flower. This shows that Jung had already started on the track of European alchemy by following up Conrad Waldkirch's preface in Artis Auriferae (1593); and it raises the question of whether this could be the possible missing link to Jung's subsequent research in Alchemy and Hermetic Philosophy in the years to come. It is argued that here was the beginning of Jung's quest for the Aurora consurgens, the publication of which concludes the Mysterium Conuinctionis more than twenty years later. It is further maintained that this choice of the Aurora is a profound expression of Jung's ambition to revitalize the past from within the individual, and helps explain Jung's deep concern with the welfare and future of modern society.

  11. Small-scale Features in Pulsating Aurora

    NASA Astrophysics Data System (ADS)

    Jones, S.; Jaynes, A. N.; Knudsen, D. J.; Trondsen, T.; Lessard, M.

    2011-12-01

    A field study was conducted from March 12-16, 2002 using a narrow-field intensified CCD camera installed at Churchill, Manitoba. The camera was oriented along the local magnetic zenith where small-scale black auroral forms are often visible. This analysis focuses on such forms occurring within a region of pulsating aurora. The observations show black forms with irregular shape and nonuniform drift with respect to the relatively stationary pulsating patches. The pulsating patches occur within a diffuse auroral background as a modulation of the auroral brightness in a localized region. The images analyzed show a decrease in the brightness of the diffuse background in the region of the pulsating patch at the beginning of the 'off' phase of the modulation. Throughout the off phase the brightness of the diffuse aurora gradually increases back to the average intensity. The time constant for this increase is measured as the first step toward determining the physical process.

  12. Small-Scale Features in Pulsating Aurora

    NASA Technical Reports Server (NTRS)

    Jones, Sarah; Jaynes, Allison N.; Knudsen, David J.; Trondsen, Trond; Lessard, Marc

    2011-01-01

    A field study was conducted from March 12-16, 2002 using a narrow-field intensified CCD camera installed at Churchill, Manitoba. The camera was oriented along the local magnetic zenith where small-scale black auroral forms are often visible. This analysis focuses on such forms occurring within a region of pulsating aurora. The observations show black forms with irregular shape and nonuniform drift with respect to the relatively stationary pulsating patches. The pulsating patches occur within a diffuse auroral background as a modulation of the auroral brightness in a localized region. The images analyzed show a decrease in the brightness of the diffuse background in the region of the pulsating patch at the beginning of the offphase of the modulation. Throughout the off phase the brightness of the diffuse aurora gradually increases back to the average intensity. The time constant for this increase is measured as the first step toward determining the physical process.

  13. Aurora Australis, Spiked, Sinuous Green Airglow

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This distant view of the Aurora Australis or Southern Lights (location unknown) shows a spiked and sinuous band of green airglow above the Earth Limb. Calculated to be in the 80 - 120 km altitude region, auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  14. Aurora Australis, Spiked, Sinuous Green Airglow

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This distant view of the Aurora Australis or Southern Lights (location unknown) shows a spiked and sinuous band of green airglow above the Earth Limb. Calculated to be in the 80 - 120 km altitude region, auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  15. Powerful Auroras Found at Brown Dwarf

    NASA Image and Video Library

    2017-09-28

    This artist's concept shows an auroral display on a brown dwarf. If you could see an aurora on a brown dwarf, it would be a million times brighter than an aurora on Earth. Credits: Chuck Carter and Gregg Hallinan/Caltech --- Mysterious objects called brown dwarfs are sometimes called "failed stars." They are too small to fuse hydrogen in their cores, the way most stars do, but also too large to be classified as planets. But a new study in the journal Nature suggests they succeed in creating powerful auroral displays, similar to the kind seen around the magnetic poles on Earth. "This is a whole new manifestation of magnetic activity for that kind of object," said Leon Harding, a technologist at NASA's Jet Propulsion Laboratory, Pasadena, California, and co-author on the study. On Earth, auroras are created when charged particles from the solar wind enter our planet's magnetosphere, a region where Earth's magnetic field accelerates and sends them toward the poles. There, they collide with atoms of gas in the atmosphere, resulting in a brilliant display of colors in the sky. Read more: www.nasa.gov/jpl/powerful-auroras-found-at-brown-dwarf NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  16. Complex structure within Saturn's infrared aurora

    USGS Publications Warehouse

    Stallard, T.; Miller, S.; Lystrup, M.; Achilleos, N.; Bunce, E.J.; Arridge, C.S.; Dougherty, M.K.; Cowley, S.W.H.; Badman, S.V.; Talboys, D.L.; Brown, R.H.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Sotin, Christophe; Nicholson, P.D.; Drossart, P.

    2008-01-01

    The majority of planetary aurorae are produced by electrical currents flowing between the ionosphere and the magnetosphere which accelerate energetic charged particles that hit the upper atmosphere. At Saturn, these processes collisionally excite hydrogen, causing ultraviolet emission, and ionize the hydrogen, leading to H3+ infrared emission. Although the morphology of these aurorae is affected by changes in the solar wind, the source of the currents which produce them is a matter of debate. Recent models predict only weak emission away from the main auroral oval. Here we report images that show emission both poleward and equatorward of the main oval (separated by a region of low emission). The extensive polar emission is highly variable with time, and disappears when the main oval has a spiral morphology; this suggests that although the polar emission may be associated with minor increases in the dynamic pressure from the solar wind, it is not directly linked to strong magnetospheric compressions. This aurora appears to be unique to Saturn and cannot be explained using our current understanding of Saturn's magnetosphere. The equatorward arc of emission exists only on the nightside of the planet, and arises from internal magnetospheric processes that are currently unknown. ??2008 Macmillan Publishers Limited. All rights reserved.

  17. Auroral kilometric radiation/aurora correlation

    NASA Technical Reports Server (NTRS)

    Benson, R. F.; Akasofu, S. I.

    1983-01-01

    Auroral kilometric radiation (AKR) observations from the ISIS 1 topside sounder receiver were compared with visual auroral observations from the network of Alaskan all-sky camera stations. The goal was to relate AKR source region encounters to specific auroral forms on the same magnetic field line. Thirty-eight simultaneous data sets were identified and analyzed. In general, intense AKR was associated with bright auroral arcs and conditions of weak or no AKR corresponded to times when either no aurora or only a faint arc or weak diffuse aurora were observed. Five cases, when both intense AKR and bright visual aurora were present, were analyzed in detail. Complete electron density N sub e contours, from the satellite altitude down to the F region ionization peak, were obtained along N-S traversals of the AKR source region. In addition, the ISIS 1 orbital tracks were projected down the magnetic field lines to the auroral altitude and compared to auroral features on a map derived from the all sky camera images. Density cavities (regions where N sub e 100/cu cm) were encountered on each of these passes.

  18. The aurorae of Uranus past equinox

    NASA Astrophysics Data System (ADS)

    Lamy, L.; Prangé, R.; Hansen, K. C.; Tao, C.; Cowley, S. W. H.; Stallard, T. S.; Melin, H.; Achilleos, N.; Guio, P.; Badman, S. V.; Kim, T.; Pogorelov, N.

    2017-04-01

    The aurorae of Uranus were recently detected in the far ultraviolet with the Hubble Space Telescope (HST) providing a new, so far unique, means to remotely study the asymmetric Uranian magnetosphere from Earth. We analyze here two new HST Uranus campaigns executed in September 2012 and November 2014 with different temporal coverage and under variable solar wind conditions numerically predicted by three different MHD codes. Overall, the HST images taken with the Space Telescope Imaging Spectrograph reveal auroral emissions in three pairs of successive images (one pair acquired in 2012 and two in 2014), hence 6 additional auroral detections in total, including the most intense Uranian aurorae ever seen with HST. The detected emissions occur close the expected arrival of interplanetary shocks. They appear as extended spots at southern latitudes, rotating with the planet. They radiate 5-24 kR and 1.3-8.8 GW of ultraviolet emission from H2, last for tens of minutes and vary on timescales down to a few seconds. Fitting the 2014 observations with model auroral ovals constrains the longitude of the southern (northern) magnetic pole to 104 ± 26° (284 ± 26°) in the Uranian Longitude System. We suggest that the Uranian near-equinoctial aurorae are pulsed cusp emissions possibly triggered by large-scale magnetospheric compressions.

  19. Hubble Provides Complete View of Jupiter's Auroras

    NASA Technical Reports Server (NTRS)

    1998-01-01

    NASA's Hubble Space Telescope has captured a complete view of Jupiter's northern and southern auroras.

    Images taken in ultraviolet light by the Space Telescope Imaging Spectrograph (STIS) show both auroras, the oval-shaped objects in the inset photos. While the Hubble telescope has obtained images of Jupiter's northern and southern lights since 1990, the new STIS instrument is 10 times more sensitive than earlier cameras. This allows for short exposures, reducing the blurring of the image caused by Jupiter's rotation and providing two to five times higher resolution than earlier cameras. The resolution in these images is sufficient to show the 'curtain' of auroral light extending several hundred miles above Jupiter's limb (edge). Images of Earth's auroral curtains, taken from the space shuttle, have a similar appearance. Jupiter's auroral images are superimposed on a Wide Field and Planetary Camera 2 image of the entire planet. The auroras are brilliant curtains of light in Jupiter's upper atmosphere. Jovian auroral storms, like Earth's, develop when electrically charged particles trapped in the magnetic field surrounding the planet spiral inward at high energies toward the north and south magnetic poles. When these particles hit the upper atmosphere, they excite atoms and molecules there, causing them to glow (the same process acting in street lights).

    The electrons that strike Earth's atmosphere come from the sun, and the auroral lights remain concentrated above the night sky in response to the 'solar wind.'

  20. Polar Embedding for Aurora Image Retrieval.

    PubMed

    Yang, Xi; Gao, Xinbo; Tian, Qi

    2015-11-01

    Exploring the multimedia techniques to assist scientists for their research is an interesting and meaningful topic. In this paper, we focus on the large-scale aurora image retrieval by leveraging the bag-of-visual words (BoVW) framework. To refine the unsuitable representation and improve the retrieval performance, the BoVW model is modified by embedding the polar information. The superiority of the proposed polar embedding method lies in two aspects. On the one hand, the polar meshing scheme is conducted to determine the interest points, which is more suitable for images captured by circular fisheye lens. Especially for the aurora image, the extracted polar scale-invariant feature transform (polar-SIFT) feature can also reflect the geomagnetic longitude and latitude, and thus facilitates the further data analysis. On the other hand, a binary polar deep local binary pattern (polar-DLBP) descriptor is proposed to enhance the discriminative power of visual words. Together with the 64-bit polar-SIFT code obtained via Hamming embedding, the multifeature index is performed to reduce the impact of false positive matches. Extensive experiments are conducted on the large-scale aurora image data set. The experimental result indicates that the proposed method improves the retrieval accuracy significantly with acceptable efficiency and memory cost. In addition, the effectiveness of the polar-SIFT scheme and polar-DLBP integration are separately demonstrated.

  1. Structure-based design of Aurora A & B inhibitors

    NASA Astrophysics Data System (ADS)

    Poulsen, Anders; William, Anthony; Lee, Angeline; Blanchard, Stéphanie; Teo, Eeling; Deng, Weiping; Tu, Noah; Tan, Evelyn; Sun, Eric; Goh, Kay Lin; Ong, Wai Chung; Ng, Chee Pang; Goh, Kee Chuan; Bonday, Zahid

    2008-12-01

    The Aurora family of serine/threonine kinases are mitotic regulators involved in centrosome duplication, formation of the bipolar mitotic spindle and the alignment of the chromosomes along the spindle. These proteins are frequently overexpressed in tumor cells as compared to normal cells and are therefore potential therapeutic oncology targets. An Aurora A high throughput screen revealed a promising sub-micromolar indazole-benzimidazole lead. Modification of the benzimidazole portion of the lead to a C2 linker with a phenyl ring was proposed to achieve novelty. Docking revealed that a conjugated linker was optimal and the resulting compounds were equipotent with the lead. Further structure-guided optimization of substituents on the 5 & 6 position of the indazole led to single digit nanomolar potency. The homology between the Aurora A & Aurora B kinase domains is 71% but their binding sites only differ at residues 212 & 217 (Aurora A numbering). However interactions with only the latter residue may be used for obtaining selectivity. An analysis of published Aurora A and Aurora B X-ray structures reveals subtle differences in the shape of the binding sites. This was exploited by introduction of appropriately sized substituents in the 4 & 6 position of the indazole leading to Aurora B selective inhibitors. Finally we calculate the conformational energy penalty of the putative bioactive conformation of our inhibitors and show that this property correlates well with the Aurora A binding affinity.

  2. Martian Aurora 25 Times Brighter Than Prior Brightest

    NASA Image and Video Library

    2017-09-29

    These profiles show the brightness of aurora emission in Mars' atmosphere at different altitudes. The data are from observations by the Imaging Ultraviolet Spectrograph instrument (IUVS) on NASA's Mars Atmosphere and Volatile Evolution orbiter, or MAVEN. The solid black profile on the right shows the aurora during a September 2017 solar storm. Barely visible along the vertical axis is a dashed profile representing the previous brightest aurora seen by MAVEN, which occurred in March 2015. The recent event is more than 25 times brighter than the previous brightest aurora seen by MAVEN, which has been orbiting Mars since September 2014. https://photojournal.jpl.nasa.gov/catalog/PIA21857

  3. Phosphorylation at serine 331 is required for Aurora B activation

    PubMed Central

    Petsalaki, Eleni; Akoumianaki, Tonia; Black, Elizabeth J.; Gillespie, David A.F.

    2011-01-01

    Aurora B kinase activity is required for successful cell division. In this paper, we show that Aurora B is phosphorylated at serine 331 (Ser331) during mitosis and that phosphorylated Aurora B localizes to kinetochores in prometaphase cells. Chk1 kinase is essential for Ser331 phosphorylation during unperturbed prometaphase or during spindle disruption by taxol but not nocodazole. Phosphorylation at Ser331 is required for optimal phosphorylation of INCENP at TSS residues, for Survivin association with the chromosomal passenger complex, and for complete Aurora B activation, but it is dispensable for Aurora B localization to centromeres, for autophosphorylation at threonine 232, and for association with INCENP. Overexpression of Aurora BS331A, in which Ser331 is mutated to alanine, results in spontaneous chromosome missegregation, cell multinucleation, unstable binding of BubR1 to kinetochores, and impaired mitotic delay in the presence of taxol. We propose that Chk1 phosphorylates Aurora B at Ser331 to fully induce Aurora B kinase activity. These results indicate that phosphorylation at Ser331 is an essential mechanism for Aurora B activation. PMID:22024163

  4. Longer Sleep Duration and Midday Napping Are Associated with a Higher Risk of CHD Incidence in Middle-Aged and Older Chinese: the Dongfeng-Tongji Cohort Study

    PubMed Central

    Yang, Liangle; Yang, Handong; He, Meian; Pan, An; Li, Xiulou; Min, Xinwen; Zhang, Ce; Xu, Chengwei; Zhu, Xiaoyan; Yuan, Jing; Wei, Sheng; Miao, Xiaoping; Hu, Frank B.; Wu, Tangchun; Zhang, Xiaomin

    2016-01-01

    Study Objectives: To analyze the independent and combined relations of sleep duration and midday napping with coronary heart diseases (CHD) incidence along with the underlying changes of cardiovascular disease (CVD) risk factors among Chinese adults. Methods: We included 19,370 individuals aged 62.8 years at baseline from September 2008 to June 2010, and they were followed until October 2013. Cox proportional hazards models and general linear models were used for multivariate longitudinal analyses. Results: Compared with sleeping 7– < 8 h/night, the hazard ratio (HR) of CHD incidence was 1.33 (95% CI = 1.10 to 1.62) for sleeping ≥ 10 h/night. The association was particularly evident among individuals who were normal weight and without diabetes. Similarly, the HR of incident CHD was 1.25 (95% CI = 1.05 to 1.49) for midday napping > 90 min compared with 1–30 min. When sleep duration and midday napping were combined, individuals having sleep duration ≥ 10 h and midday napping > 90 min were at a greater risk of CHD than those with sleeping 7– < 8 h and napping 1–30 min: the HR was 1.67 (95% CI = 1.04 to 2.66; P for trend = 0.017). In addition, longer sleep duration ≥ 10 h was significantly associated with increases in triglycerides and waist circumference, and a reduction in HDL-cholesterol; while longer midday napping > 90 min was related to increased waist circumference. Conclusions: Both longer sleep duration and midday napping were independently and jointly associated with a higher risk of CHD incidence, and altered lipid profile and waist circumference may partially explain the relationships. Citation: Yang L, Yang H, He M, Pan A, Li X, Min X, Zhang C, Xu C, Zhu X, Yuan J, Wei S, Miao X, Hu FB, Wu T, Zhang X. Longer sleep duration and midday napping are associated with a higher risk of CHD incidence in middle-aged and older Chinese: the Dongfeng-Tongji Cohort Study. SLEEP 2016;39(3):645–652. PMID:26564127

  5. Antiproliferative effect of Aurora kinase targeting in mesothelioma.

    PubMed

    Crispi, Stefania; Fagliarone, Claudia; Biroccio, Annamaria; D'Angelo, Carmen; Galati, Rossella; Sacchi, Ada; Vincenzi, Bruno; Baldi, Alfonso; Verdina, Alessandra

    2010-12-01

    The Aurora proteins are a small family of serine/threonine kinase that function in various stages of mitosis. Current interest in Aurora kinase relates to its role in tumours, and its potential as a therapeutic target. In this work we studied the expression of Aurora kinases A and B and related genes in human mesothelioma tissues and in five mesothelioma cell lines. Moreover, we analyzed the effects of ZM447439 (ZM), an Aurora kinase inhibitor, on cellular growth. Results evidenced an over-expression of Aurora kinase A and related genes in human mesothelioma tissues and an over-expression of Aurora kinases A and B in all cell lines. Moreover, we demonstrated that ZM447439 was able to inhibit cell growth in all cell lines and that this inhibition was due to a specific effect as demonstrated by the reduction in the level of Histone H3 phosphorylation. Our findings support a role of Aurora kinase in mesothelioma and the possibility of using Aurora kinase inhibitors in therapeutic modalities.

  6. Chromosome dynamics: new light on Aurora B kinase function.

    PubMed

    Shannon, Katie B; Salmon, E D

    2002-07-09

    Aurora B family kinases play an essential role in chromosome segregation and cytokinesis. Recent work suggests that the kinase activity is required for bipolar chromosome orientation, kinetochore assembly, spindle checkpoint and microtubule dynamics. Aurora B also has additional functions in chromosome condensation and cohesion.

  7. PKCɛ switches Aurora B specificity to exit the abscission checkpoint

    PubMed Central

    Pike, Tanya; Brownlow, Nicola; Kjaer, Svend; Carlton, Jeremy; Parker, Peter J.

    2016-01-01

    The ‘NoCut', or Aurora B abscission checkpoint can be activated if DNA is retained in the cleavage furrow after completion of anaphase. Checkpoint failure leads to incomplete abscission and a binucleate outcome. These phenotypes are also observed after loss of PKCɛ in transformed cell models. Here we show that PKCɛ directly modulates the Aurora B-dependent abscission checkpoint by phosphorylating Aurora B at S227. This phosphorylation invokes a switch in Aurora B specificity, with increased phosphorylation of a subset of target substrates, including the CPC subunit Borealin. This switch is essential for abscission checkpoint exit. Preventing the phosphorylation of Borealin leads to abscission failure, as does expression of a non-phosphorylatable Aurora B S227A mutant. Further, depletion of the ESCRT-III component and Aurora B substrate CHMP4C enables abscission, bypassing the PKCɛ–Aurora B exit pathway. Thus, we demonstrate that PKCɛ signals through Aurora B to exit the abscission checkpoint and complete cell division. PMID:28004745

  8. PKCɛ switches Aurora B specificity to exit the abscission checkpoint.

    PubMed

    Pike, Tanya; Brownlow, Nicola; Kjaer, Svend; Carlton, Jeremy; Parker, Peter J

    2016-12-22

    The 'NoCut', or Aurora B abscission checkpoint can be activated if DNA is retained in the cleavage furrow after completion of anaphase. Checkpoint failure leads to incomplete abscission and a binucleate outcome. These phenotypes are also observed after loss of PKCɛ in transformed cell models. Here we show that PKCɛ directly modulates the Aurora B-dependent abscission checkpoint by phosphorylating Aurora B at S227. This phosphorylation invokes a switch in Aurora B specificity, with increased phosphorylation of a subset of target substrates, including the CPC subunit Borealin. This switch is essential for abscission checkpoint exit. Preventing the phosphorylation of Borealin leads to abscission failure, as does expression of a non-phosphorylatable Aurora B S227A mutant. Further, depletion of the ESCRT-III component and Aurora B substrate CHMP4C enables abscission, bypassing the PKCɛ-Aurora B exit pathway. Thus, we demonstrate that PKCɛ signals through Aurora B to exit the abscission checkpoint and complete cell division.

  9. In Vitro Characterization of Derrone as an Aurora Kinase Inhibitor.

    PubMed

    Hoang, Nhung Thi My; Phuong, Thuong Thien; Nguyen, Trang Thi Nhu; Tran, Yen Thi Hai; Nguyen, Anh Thi Ngoc; Nguyen, Thanh Lai; Bui, Khanh Thi Van

    2016-06-01

    Among mitotic kinases, Aurora kinases are the most widely studied, since their expression is restricted to mitosis. They play a key role in chromosome segregation and cell polyploidy. Aurora kinases are important therapeutic targets, and several research groups have directed their efforts toward the identification of kinase inhibitors. The aim of this study is to screen and characterize Aurora kinase inhibitors from natural substances extracted from plants that are used in the Vietnamese pharmacopoeia. We have characterized in vitro Derrone, extracted from Erythrina orientalis L. MURR, as a novel Aurora kinase inhibitor. This compound exhibited an ability to inhibit the phosphorylation of histone H3 at ser10 both in kinase assay and at the cellular level. The compound was more effective against Aurora kinase B, with a lower IC50 value as compared to Aurora A. Moreover, it impaired the mitotic spindle checkpoint and led to endoreduplication in cancer cells, a phenomenon caused by an Aurora B inhibitor. Interestingly, using the xCelligence system and real-time cell analysis (RTCA) software, we set up a comparison of cell proliferation profiles between cancer cells treated with Derrone and VX680-a well-known Aurora kinase inhibitor-and we found that these profiles exhibited considerable similarity in cell morphology, growth, and death. Additionally, Derrone significantly inhibited the formation and growth of MCF7 tumor spheroids.

  10. Magnetosphere-ionosphere coupling during active aurora

    NASA Astrophysics Data System (ADS)

    Grubbs, Guy, II

    In this work, processes which couple the Earth's magnetosphere and ionosphere are examined using observations of aurora from ground-based imaging, in situ electron measurements, and electron transport modeling. The coupling of these regions relies heavily on the energy transport between the two and the ionospheric conductances, which regulate the location and magnitude of the transport. The combination of the datasets described are used to derive the conductances and electron energy populations at the upper boundary of the ionosphere. These values are constrained using error analysis of the observation and measurement techniques and made available to the global magnetosphere modeling community for inclusion as boundary conditions at the magnetosphere and ionosphere coupling region. A comparative study of the active aurora and incident electron distributions was conducted using ground-based measurements and in-situ sounding rocket data. Three narrow-field (47 degree field-of-view) electron-multiplying charge-coupled device (EMCCD) imagers were located at Venetie, AK which took high spatio-temporal resolution measurements of the aurora using different wavelength filters (427.8 nm, 557.7 nm, and 844.6 nm). The measured emission line ratios were combined with atmospheric modeling in order to predict the total electron energy flux and characteristic electron energy incident on the atmosphere. These predictions were compared with in-situ measurements made by the Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment (GREECE) sounding rocket launched in early 2014. The GREECE particle instruments were modeled using a ray-tracing program, SIMION, in order to predict the instrument responses for different incident particles. Each instrument model was compared with data taken in the lab in order to compare and update the models appropriately. A rocket emulation system was constructed for lab testing prior to and during instrument integration into the rocket and

  11. Analysis of Aurora's Performance Simulation Engine for Three Systems

    SciTech Connect

    Freeman, Janine; Simon, Joseph

    2015-07-07

    Aurora Solar Inc. is building a cloud-based optimization platform to automate the design, engineering, and permit generation process of solar photovoltaic (PV) installations. They requested that the National Renewable Energy Laboratory (NREL) validate the performance of the PV system performance simulation engine of Aurora Solar’s solar design platform, Aurora. In previous work, NREL performed a validation of multiple other PV modeling tools 1, so this study builds upon that work by examining all of the same fixed-tilt systems with available module datasheets that NREL selected and used in the aforementioned study. Aurora Solar set up these three operating PV systems in their modeling platform using NREL-provided system specifications and concurrent weather data. NREL then verified the setup of these systems, ran the simulations, and compared the Aurora-predicted performance data to measured performance data for those three systems, as well as to performance data predicted by other PV modeling tools.

  12. Source of the dayside cusp aurora

    PubMed Central

    Frey, H. U.; Angelopoulos, V.

    2016-01-01

    Abstract Monochromatic all‐sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko‐96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N2 + 427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N2 + 427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave‐accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard‐electron precipitation zone originating inside the magnetosphere. PMID:27867797

  13. Source of the dayside cusp aurora

    NASA Astrophysics Data System (ADS)

    Mende, S. B.; Frey, H. U.; Angelopoulos, V.

    2016-08-01

    Monochromatic all-sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko-96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N2+ 427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N2+ 427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave-accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard-electron precipitation zone originating inside the magnetosphere.

  14. Source of the dayside cusp aurora.

    PubMed

    Mende, S B; Frey, H U; Angelopoulos, V

    2016-08-01

    Monochromatic all-sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko-96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N2(+) 427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N2(+) 427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave-accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard-electron precipitation zone originating inside the magnetosphere.

  15. Aurora Australis, Spiked, Sinuous Green Airglow

    NASA Image and Video Library

    1991-05-06

    STS039-25-006 (28 April-6 May 1991) --- A 35mm frame of the Aurora Australis, also known as the Southern Lights, photographed from the Space Shuttle Discovery's flight deck by one of its seven crew members. One of the mission objectives was to measure the spectral and spatial characteristics of auroral emissions. While passing over the sunlighted portion of Earth, the crew was able to take a number of photos of the various geographic points on the planet; much of the time on nightside passes was devoted to a thorough study and documentation of auroral displays.

  16. Swedish Small Satellites Investigate the Aurora

    NASA Astrophysics Data System (ADS)

    Marklund, Göran; André, Mats; Lundin, Rickard

    2004-04-01

    The Swedish small satellite program-which began in the mid-1980s-has been recognized internationally as cost-efficient and scientifically successful, and the results have contributed significantly to the progress in auroral research. The program comprises six research satellites to date, five of which were auroral or space plasma missions. Viking and Freja made substantial and sometimes pioneering contributions to the understanding of the aurora. The smaller satellites Astrid, Astrid-2, and Munin proved powerful both for testing new space technologies and instruments and for providing high-quality scientific data.

  17. Multifunctional human transcriptional coactivator protein PC4 is a substrate of Aurora kinases and activates the Aurora enzymes.

    PubMed

    Dhanasekaran, Karthigeyan; Kumari, Sujata; Boopathi, Ramachandran; Shima, Hiroki; Swaminathan, Amrutha; Bachu, Mahesh; Ranga, Udaykumar; Igarashi, Kazuhiko; Kundu, Tapas K

    2016-03-01

    Positive coactivator 4 (PC4), a human transcriptional coactivator, is involved in diverse processes like chromatin organization and transcription regulation. It is hyperphosphorylated during mitosis, with unknown significance. For the first time, we demonstrate the function of PC4 outside the nucleus upon nuclear envelope breakdown. A fraction of PC4 associates with Aurora A and Aurora B and undergoes phosphorylation, following which PC4 activates both Aurora A and B to sustain optimal kinase activity to maintain the phosphorylation gradient for the proper functioning of the mitotic machinery. This mitotic role is evident in PC4 knockdown cells where the defects are rescued only by the catalytically active Aurora kinases, but not the kinase-dead mutants. Similarly, the PC4 phosphodeficient mutant failed to rescue such defects. Hence, our observations establish a novel mitotic function of PC4 that might be dependent on Aurora kinase-mediated phosphorylation.

  18. What's so Bor(a)ing about Aurora-A activation?

    PubMed

    Wiese, Christiane; O'Brien, Lori L

    2006-08-01

    Aurora-A kinases are highly conserved mitotic kinases required for cell division. The regulation of Aurora-A activity is less highly conserved and currently poorly understood. Work by Knoblich and coworkers in this issue of Developmental Cell identifies the conserved protein, Aurora Borealis (Bora), as a key regulator of Aurora-A activity during mitosis.

  19. Combined effects of wind and solar irradiance on the spatial variation of midday air temperature over a mountainous terrain

    NASA Astrophysics Data System (ADS)

    Kim, Soo-Ock; Kim, Jin-Hee; Kim, Dae-Jun; Shim, Kyo Moon; Yun, Jin I.

    2015-08-01

    When the midday temperature distribution in a mountainous region was estimated using data from a nearby weather station, the correction of elevation difference based on temperature lapse caused a large error. An empirical approach reflecting the effects of solar irradiance and advection was suggested in order to increase the reliability of the results. The normalized slope irradiance, which was determined by normalizing the solar irradiance difference between a horizontal surface and a sloping surface from 1100 to 1500 LST on a clear day, and the deviation relationship between the horizontal surface and the sloping surface at the 1500 LST temperature on each day were presented as simple empirical formulas. In order to simulate the phenomenon that causes immigrant air parcels to push out or mix with the existing air parcels in order to decrease the solar radiation effects, an advection correction factor was added to exponentially reduce the solar radiation effect with an increase in wind speed. In order to validate this technique, we estimated the 1500 LST air temperatures on 177 clear days in 2012 and 2013 at 10 sites with different slope aspects in a mountainous catchment and compared these values to the actual measured data. The results showed that this technique greatly improved the error bias and the overestimation of the solar radiation effect in comparison with the existing methods. By applying this technique to the Korea Meteorological Administration's 5-km grid data, it was possible to determine the temperature distribution at a 30-m resolution over a mountainous rural area south of Jiri Mountain National Park, Korea.

  20. Optical properties of the Martian aerosols as derived from Imager for Mars Pathfinder midday sky brightness data

    NASA Astrophysics Data System (ADS)

    Shalygina, O. S.; Markiewicz, W. J.; Hviid, S. F.

    2012-09-01

    It is well known that the aerosol play a major role in the energy budget of the Martian atmosphere. The importance of the aerosols for the radiative loading of the atmosphere has hence, direct impact on the Martian present weather and its seasonal cycle as well as consequences for its long term climate. Very accurate models of the sky brightness are required to separate the atmospheric illumination from the spectrum of the Martian surface, and hence to understand the mineralogy of the surface rocks and soil. Such accurate models are only possible if the optical properties of the Martian aerosols are known. In this work we analyze the images of the brightness of the Martian sky at midday acquired from the surface of the Mars during the Mars Pathfinder mission. The Imager for Mars Pathfinder (IMP) obtained data in filters centered at 443.6, 481.0, 670.8, 896.1 and 965.3 nm. Useful data sets were returned on sols 27, 40, 56, 65, 68, 74 and 82. Although the coverage in scattering angles of this sequence is limited to about 100°, having the Sun near zenith minimizes multiple scattering. This property should help in accuracy of constraining the size distribution and material properties. The shape of the particles can be expected to be less well constrained, as scattering events at angles around 150° are only present through multiple scattering. Data from sol 56 (Figure 1) were fitted with multiple scattering radiative transfer calculations to extract the size distribution, optical properties, and shape of the aerosols suspended in the atmosphere [1].

  1. Artificial Aurora Generated by HAARP (Invited)

    NASA Astrophysics Data System (ADS)

    Streltsov, A. V.; Kendall, E. A.

    2013-12-01

    We present results from the ionospheric heating experiment conducted on March 12, 2013 at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. During the experiment HAARP transmitted X-mode 4.57 MHz waves modulated with the frequency 0.9 mHz and pointed in the direction of the magnetic zenith. The beam was focused to ~20 km spot at the altitude 100 km. The heating produces two effects: First, it generates magnetic field-aligned currents producing D and H components of the magnetic field with frequency 0.9 mHz detected by fluxgate magnetometer in Gakona. Second, the heating produced bright luminous structures in the heated region detected with the SRI telescope in 427.8 nm, 557.7 nm, 630.0 nm wavelengths. We emphasize, that for the best of our knowledge, this is the first experiment where the heating of the ionosphere with X-mode produces luminous structures in the ionosphere. We classify this luminosity as an 'artificial aurora', because it correlate with the intensity of the magnetic field-aligned currents, and such correlation is constantly seen in the natural aurora.

  2. Juno Listens to Jupiter Auroras Sing

    NASA Image and Video Library

    2016-09-02

    During its close flyby of Jupiter on August 27, 2016, the Waves instrument on NASA's Juno spacecraft received radio signals associated with the giant planet's very intense auroras. This video displays these radio emissions in a format similar to a voiceprint, showing the intensity of radio waves as a function of frequency and time. The largest intensities are indicated in warmer colors. The frequency range of these signals is from 7 to 140 kilohertz. Radio astronomers call these "kilometric emissions" because their wavelengths are about a kilometer long. The time span of this data is 13 hours, beginning shortly after Juno's closest approach to Jupiter. Accompanying this data display is an audio rendition of the radio emissions, shifted into a lower register since the radio waves are well above the audio frequency range. In the video, a cursor moves from left to right to mark the time as the sounds are heard. These radio emissions were among the first observed by early radio astronomers in the 1950s. However, until now, they had not been observed from closely above the auroras themselves. From its polar orbit vantage point, Juno has -- for the first time -- enabled observations of these emissions from very close range. The Juno team believes that Juno flew directly through the source regions for some of these emissions during this flyby, which was Juno's first with its sensors actively collecting data. A movie is available at http://photojournal.jpl.nasa.gov/catalog/PIA21037

  3. HUBBLE PROVIDES COMPLETE VIEW OF JUPITER'S AURORAS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's Hubble Space Telescope has captured a complete view of Jupiter's northern and southern auroras. Images taken in ultraviolet light by the Space Telescope Imaging Spectrograph (STIS) show both auroras, the oval- shaped objects in the inset photos. While the Hubble telescope has obtained images of Jupiter's northern and southern lights since 1990, the new STIS instrument is 10 times more sensitive than earlier cameras. This allows for short exposures, reducing the blurring of the image caused by Jupiter's rotation and providing two to five times higher resolution than earlier cameras. The resolution in these images is sufficient to show the 'curtain' of auroral light extending several hundred miles above Jupiter's limb (edge). Images of Earth's auroral curtains, taken from the space shuttle, have a similar appearance. Jupiter's auroral images are superimposed on a Wide Field and Planetary Camera 2 image of the entire planet. The auroras are brilliant curtains of light in Jupiter's upper atmosphere. Jovian auroral storms, like Earth's, develop when electrically charged particles trapped in the magnetic field surrounding the planet spiral inward at high energies toward the north and south magnetic poles. When these particles hit the upper atmosphere, they excite atoms and molecules there, causing them to glow (the same process acting in street lights). The electrons that strike Earth's atmosphere come from the sun, and the auroral lights remain concentrated above the night sky in response to the 'solar wind,' as Earth rotates underneath. Earth's auroras exhibit storms that extend to lower latitudes in response to solar activity, which can be easily seen from the northern U. S. But Jupiter's auroras are caused by particles spewed out by volcanoes on Io, one of Jupiter's moons. These charged particles are then magnetically trapped and begin to rotate with Jupiter, producing ovals of auroral light centered on Jupiter's magnetic poles in both the day and night skies

  4. Jovian-like aurorae on Saturn.

    PubMed

    Stallard, Tom; Miller, Steve; Melin, Henrik; Lystrup, Makenzie; Cowley, Stan W H; Bunce, Emma J; Achilleos, Nicholas; Dougherty, Michele

    2008-06-19

    Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same.

  5. The Aurora, Magnetosphere, and the IGY

    NASA Astrophysics Data System (ADS)

    McKim Malville, J.

    2007-12-01

    This retrospective of auroral research during the IGY will be from the perspective of the auroral observers in the Antarctic from 1956-58. The IGY served as a watershed divide in our understanding of auroral physics. Prior to the IGY the role of "solar corpuscular radiation” in exciting auroral radiation was the pre-eminent research question. The mechanisms for the acceleration of solar protons and electrons had not been resolved, nor had the role of plasma instabilities been envisioned. The spectroscopic research program during the IGY was dominated by the work of Aden Meinel and Joseph W. Chamberlain at Yerkes Observatory. The dynamics of precipitating solar protons into a dilute gas was a major research focus. The changes brought about by the discoveries of the radiation belts, the solar wind, and the magnetosphere resulted in a remarkable transformation and a paradigm shift in our understanding of the physics of the aurora. Antarctic observations during the IGY revealed the auroral oval, which is a signature of radiation belts distorted by the solar wind. High auroral rays could be explained by pitch angle distributions of trapped electrons. Sudden accelerations of electrons, resulting in red lower borders of aurora deep in the atmosphere, revealed the serious deficiencies of available theory. Whistlers, first detected in the Antarctic at Ellsworth Station in 1957, proved to be valuable probes of the magnetosphere.

  6. The Jovian aurora: Electron or ion precipitation

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr.; Clarke, J. T.; Cravens, T. E.

    1986-01-01

    High signal-to-noise spectra of the Jovian aurora at UV wavelengths obtained using the International Ultraviolet Explorer Observatory (including the brightest Jovian aurora observed to date) set strigent upper limits for sulfur and oxygen emissions, which would be associated with the precipitation of energetic heavy ions in the upper Jovian atmosphere if they were solely responsible for Jovian auroral processes. Model calculations of heavy ion precipitation and corresponding estimates of the associated sulfur and oxygen UV emissions previously carried out suggest emission values for 1304 A OI emission that are at least 30 times larger than the upper limit values set by the IUE observations reported. On the other hand the observed (feature of SII at 1256 A of 2 kR) is quite comparable to the theoretically predicted emission intensity. Taken together these observations and calculations suggest that electron as well as ion precipitation play a role in Jovian auroral processes. In light of earlier X-ray observations and in-situ plasma observations that suggest energetic heavy ion precipitation in the Jovian auroral zone, a scenario is suggested where heavy ion auroral energy deposition is concentrated at altitudes below the homopause. Electrons with energies of 10 to 30 keV are responsible for the bulk of the observable UV and EUV emissions since they deposit their energy above the methane absorbing layer defined by the homopause.

  7. Targeting aurora kinases as therapy in multiple myeloma

    PubMed Central

    Shi, Yijiang; Reiman, Tony; Li, Weiqun; Maxwell, Christopher A.; Sen, Subrata; Pilarski, Linda; Daniels, Tracy R.; Penichet, Manuel L.; Feldman, Rick

    2007-01-01

    The aurora kinases facilitate transit from G2 through cytokinesis and, thus, are targets in cancer therapy. Multiple myeloma (MM) is a malignancy characterized by genetic instability, suggesting a disruption of checkpoints that arrest cells at G2M when injury to the mitotic machinery occurs. Since deficient checkpoints would prevent cell cycle arrest and may render cells susceptible to apoptosis in mitosis and since aurora kinases are intermediaries in checkpoint pathways, we tested antimyeloma effects of 2 agents that inhibit aurora kinases. Both inhibited growth of MM lines and primary myeloma samples at nanomolar concentrations while having less of an effect on proliferating lymphocytes and hematopoietic cells. MM cells were not protected by IL-6 or activating mutations of Ras. Antimyeloma effects included induction of tetraploidy followed by apoptosis. Apoptosis correlated with inhibition of aurora activity as shown by reduction of histone 3B phosphorylation. Ectopic expression of aurora A protected MM cells against aurora inhibitors but had no effect on apoptosis induced by bortezomib. As expression of RHAMM in MM contributes to genetic instability, we tested effects of RHAMM. RHAMM overexpression enhanced sensitivity to apoptosis and RHAMM silencing decreased sensitivity. These results suggest potential for aurora kinase inhibitors in MM especially in patients in whom RHAMM is overexpressed. PMID:17213289

  8. Large-Scale Aspects and Temporal Evolution of Pulsating Aurora

    NASA Technical Reports Server (NTRS)

    Jones, S. L.; Lessard, M. R.; Rychert, K.; Spanswick, E.; Donovan, E.

    2010-01-01

    Pulsating aurora is a common phenomenon generally believed to occur mainly in the aftermath of a, substorm, where dim long-period pulsating patches appear. The study determines the temporal and spatial evolution of pulsating events using two THEN IIIS ASI stations, at Gillam (66.18 mlat, 332.78 mlon, magnetic midnight at 0634 UT) and Fort Smith, (67.38 mlat, 306.64 mlon, magnetic midnight at, 0806 UT) along roughly the same invariant latitude. Parameters have been calculated from a database of 74 pulsating aurora events from 119 days of good optical data within the period from September 2007 through March 2008 as identified with the Gillam camera. It is shown that the source region of pulsating aurora drifts or expands eastward, away from magnetic midnight, for pre-midnight onsets and that the spatial evolution is more complicated for post midnight onsets, which has implications for the source mechanism. The most probable duration of a pulsating aurora event is roughly 1.5 hours while the distribution of possible event durations includes many long (several hours) events. This may suggest that pulsating aurora is not strictly a substorm recovery phase phenomenon but rather a persistent, long-lived phenomenon that may be temporarily disrupted by auroral substorms. Observations from the Gillam station show that in fact, pulsating aurora is quite common with the occurrence rate increasing to around 60% for morning hours, with 6910 of pulsating aurora onsets occurring after substorm breakup.

  9. Saturn's Aurora Observed by Cassini Camera in Visible Wavelengths

    NASA Astrophysics Data System (ADS)

    Dyudina, U.; Ingersoll, A. P.; Ewald, S.; Wellington, D. F.

    2014-12-01

    Cassini camera's movies in 2009-2013 show Saturn's aurora in both the northern and southern hemispheres. The color of the aurora changes from pink at a few hundreds of km above the cloud tops to purple at 1000-1500 km above the cloud tops. The spectrum observed in 9 lters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with the laboratory simulated auroras [1]. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs, sometimes a spiral around the pole, and sometimes double arcs at 70-75 both north and south latitude. 10,000-km-scale longitudinal brightness structures can persist for more than 100 hours. This structures rotate together with Saturn. Besides the steady structure, the auroras brighten suddenly on the timescales of few minutes. 1000-km-scale disturbances may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The persistence of the longitudinal structure of the aurora in two long observations in 2009 and 2012 allowed us to estimate its period of rotation of 10.65±0.15 h for 2009 and 10.8±0.1 h for 2012. The 2009 north aurora period is close to the north branch of Saturn Kilometric Radiation (SKR) detected at that time. The 2012 south aurora period is longer than the SKR periods detected at the time. These periods are also close to the rotation period of the lightning storms on Saturn. We discuss those periodicities and their relevance to Saturn's internal rotation. [1] Aguilar, A. et al. The Electron-Excited Mid-Ultraviolet to Near-Infrared Spectrum of H2:Cross Sections and Transition Probabilities. Astrophys. J. Supp. Ser. 177, 388-407 (2008).

  10. Saturn's aurora observed by Cassini camera in visible wavelengths

    NASA Astrophysics Data System (ADS)

    Dyudina, Ulyana; Porco, Carolyn; Ingersoll, Andrew; Ewald, Shawn; Wellington, Danika

    Cassini camera's movies in 2009-2013 show Saturn's aurora in both the northern and southern hemispheres. The color of the aurora changes from pink at a few hundreds of km above the cloud tops to purple at 1000-1500 km above the cloud tops. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with the laboratory simulated auroras [1]. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs, sometimes a spiral around the pole, and sometimes double arcs at 70-75(°) both north and south latitude. 10,000-km-scale longitudinal brightness structures can persist for more than 100 hours. This structures rotate together with Saturn. Besides the steady structure, the auroras brighten suddenly on the timescales of few minutes. 1000-km-scale disturbances may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The persistence of the longitudinal structure of the aurora in two long observations in 2009 and 2012 allowed us to estimate its period of rotation of 10.65 ± 0.15 h for 2009 and 10.8± 0.1 h for 2012. The 2009 north aurora period is close to the north branch of Saturn Kilometric Radiation (SKR) detected at that time. The 2012 south aurora period is longer than any SKR periods detected at the time, but it is similar to the SKR period of the south branch of SKR periods in 2004-2008. These periods are also close to the rotation period of the lightning storms on Saturn. We discuss those periodicities and their relevance to Saturn's internal rotation. [1] Aguilar, A. et al. The Electron-Excited Mid-Ultraviolet to Near-Infrared Spectrum of H_2: Cross Sections and Transition Probabilities. Astrophys. J. Supp. Ser. 177, 388-407 (2008).

  11. Meal patterns in the SENECA study of nutrition and the elderly in Europe: assessment method and preliminary results on the role of the midday meal.

    PubMed

    Schlettwein-gsell, D; Decarli, B; de Groot, L

    1999-02-01

    The paper discusses the assessment method for meal patterns in the course of the SENECA follow-up survey in 1993 in eight study towns across Europe and relates the percentage of energy intake at the midday meal to geographical latitude, total energy intake, energy intake as snacks, number of cooked meals, time spent at the main meal and intake of milk products, fat and leafy vegetables. A questionnaire for the assessment of meal patterns in western Europe has to include the possibility to assess more than three meals per day as well as a variety of meals at any time of the day. Meal structures vary between cooked meals, bread- or soup-based meals, but may also consist of spoon food, salads or fruit. Positive correlations were found between the percentage of energy intake at the midday meal and the number of cooked meals consumed per day, negative relations were found between the percentage of energy intake at the midday meal and the geographical latitude as well as total energy intake, energy intake in form of snacks and consumption of milk products. Copyright 1999 Academic Press.

  12. SAR156497, an exquisitely selective inhibitor of aurora kinases.

    PubMed

    Carry, Jean-Christophe; Clerc, François; Minoux, Hervé; Schio, Laurent; Mauger, Jacques; Nair, Anil; Parmantier, Eric; Le Moigne, Ronan; Delorme, Cécile; Nicolas, Jean-Paul; Krick, Alain; Abécassis, Pierre-Yves; Crocq-Stuerga, Véronique; Pouzieux, Stéphanie; Delarbre, Laure; Maignan, Sébastien; Bertrand, Thomas; Bjergarde, Kirsten; Ma, Nina; Lachaud, Sylvette; Guizani, Houlfa; Lebel, Rémi; Doerflinger, Gilles; Monget, Sylvie; Perron, Sébastien; Gasse, Francis; Angouillant-Boniface, Odile; Filoche-Rommé, Bruno; Murer, Michel; Gontier, Sylvie; Prévost, Céline; Monteiro, Marie-Line; Combeau, Cécile

    2015-01-08

    The Aurora family of serine/threonine kinases is essential for mitosis. Their crucial role in cell cycle regulation and aberrant expression in a broad range of malignancies have been demonstrated and have prompted intensive search for small molecule Aurora inhibitors. Indeed, over 10 of them have reached the clinic as potential anticancer therapies. We report herein the discovery and optimization of a novel series of tricyclic molecules that has led to SAR156497, an exquisitely selective Aurora A, B, and C inhibitor with in vitro and in vivo efficacy. We also provide insights into its mode of binding to its target proteins, which could explain its selectivity.

  13. The horse-collar aurora - A frequent pattern of the aurora in quiet times

    NASA Technical Reports Server (NTRS)

    Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Evans, D. S.; Newell, P. T.

    1989-01-01

    The frequent appearance of the 'horse-collar aurora' pattern in quiet-time DE 1 images is reported, presenting a two-hour image sequence that displays the basic features and shows that it sometimes evolves toward the theta configuration. There is some evidence for interplanetary magnetic field B(y) influence on the temporal development of the pattern. A preliminary statistical analysis finds the pattern appearing in one-third or more of the image sequences recorded during quiet times.

  14. The horse-collar aurora - A frequent pattern of the aurora in quiet times

    NASA Technical Reports Server (NTRS)

    Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Evans, D. S.; Newell, P. T.

    1989-01-01

    The frequent appearance of the 'horse-collar aurora' pattern in quiet-time DE 1 images is reported, presenting a two-hour image sequence that displays the basic features and shows that it sometimes evolves toward the theta configuration. There is some evidence for interplanetary magnetic field B(y) influence on the temporal development of the pattern. A preliminary statistical analysis finds the pattern appearing in one-third or more of the image sequences recorded during quiet times.

  15. Auroras light up the Antarctic night

    NASA Image and Video Library

    2017-09-27

    NASA acquired July 15, 2012 On July 15, 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this nighttime view of the aurora australis, or “southern lights,” over Antartica’s Queen Maud Land and the Princess Ragnhild Coast. The image was captured by the VIIRS “day-night band,” which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as city lights, auroras, wildfires, and reflected moonlight. In the case of the image above, the sensor detected the visible auroral light emissions as energetic particles rained down from Earth’s magnetosphere and into the gases of the upper atmosphere. The slightly jagged appearance of the auroral lines is a function of the rapid dance of the energetic particles at the same time that the satellite is moving and the VIIRS sensor is scanning. The yellow box in the top image depicts the area shown in the lower close-up image. Light from the aurora was bright enough to illuminate the ice edge between the ice shelf and the Southern Ocean. At the time, Antarctica was locked in midwinter darkness and the Moon was a waning crescent that provided little light. NASA Earth Observatory image by Jesse Allen and Robert Simmon, using VIIRS Day-Night Band data from the Suomi National Polar-orbiting Partnership. Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense. Caption by Mike Carlowicz. Instrument: Suomi NPP - VIIRS Credit: NASA Earth Observatory Click here to view all of the Earth at Night 2012 images Click here to read more about this image NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to

  16. Observation and Theory of the Radar Aurora

    NASA Astrophysics Data System (ADS)

    Sahr, John David

    1990-01-01

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. The scattering is so strong that a small radar, such a the Cornell University Portable Radar Interferometer (CUPRI), can easily detect this "radar aurora." Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. We present observations of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, we introduce a simple nonlinear fluid theory of electrojet ion-acoustic waves, and reduce it to a form of the "three-wave interaction" equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able account for "type 3" waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of our research we have generated a simple new radar transmitting mode and signal processing algorithm which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies when a single-pulse spectral mode is used. Several new radar data analysis routines have been developed, including principally the "cross-beam image" and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that "type 3" waves originate at ordinary electrojet altitudes, not in the upper E region, from which we conclude that the electrostatic ion-cyclotron mode does not generate "type 3" waves. The measured height of type 3 waves and other spectral analyses provide support for our pure ion -acoustic theory of type 3 waves. In closing, we offer suggestions for hardware improvements to the

  17. Observation and theory of the radar aurora

    NASA Astrophysics Data System (ADS)

    Sahr, John David

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. The scattering is so strong that a small radar, such as the Cornell University Portable Radar Interferometer (CUPRI), can easily detect this radar aurora. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies when a single-pulse spectral mode is used. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new

  18. Storm-time Convection Dynamics Viewed from Optical Auroras: from Streamer to Patchy Pulsating Aurora

    NASA Astrophysics Data System (ADS)

    Yang, B.; Donovan, E.; Liang, J.; Grono, E.

    2016-12-01

    In a series of statistical and event studies we have demonstrated that the motion of patches in regions of Patchy Pulsating Aurora (PPA) is very close to if not exactly convection. Thus, 2D maps of PPA motion provides us the opportunity to remote sense magnetospheric convection with relatively high space and time resolution, subject to uncertainties associated with mapping between the ionosphere and magnetosphere. In this study, we use THEMIS ASI aurora observations (streamers and patchy pulsating aurora) combined with SuperDARN convection measurements, Swarm ion drift velocity measurements, and RBSP electric field measurements to explore the convection dynamics in storm time. From 0500 UT to 0600 UT on March 19 2015, convection observations across 5 magnetic local time (MLT) inferred from the motion of PPA patches and SuperDARN measurements show that a westward SAPS (Subauroral Polarized Streams) enhancement occurs after an auroral streamer. This suggests that plasma sheet fast flows can affect the inner magnetospheric convection, and possibly trigger very fast flows in the inner magnetosphere.

  19. Aurora-C Interactions with Survivin and INCENP Reveal Shared and Distinct Features Compared with Aurora-B Chromosome Passenger Protein Complex.

    PubMed

    Sasai, Kaori; Katayama, Hiroshi; Hawke, David H; Sen, Subrata

    2016-01-01

    Aurora-C, a member of the Aurora kinase family that can complement Aurora-B function in mitosis is either moderately expressed or repressed in most adult somatic tissues but is active in early embryonic development and expressed at elevated levels in multiple human cancers. Aurora-C overexpression reportedly plays a role in tumorigenic transformation. We performed detailed characterization of Aurora-C interactions with members of the Chromosome Passenger Complex (CPC), Survivin and Inner Centromere Protein (INCENP) in reference to known Aurora-B interactions to understand the functional significance of Aurora-C overexpression in human cancer cells. The results revealed that silencing of Aurora-C or -B individually does not affect localization of the other kinase and the two kinases exist predominantly in independent complexes in vivo. Presence of Aurora-C and -B in molecular complexes of varying as well as overlapping sizes and co-existence in INCENP overexpressing cells indicated oligomerization of ternary complexes under different physiological conditions in vivo. Furthermore, Aurora-C and -B stabilized INCENP through interaction with and phosphorylation of the IN box domain while Aurora-C was activated following Survivin phosphorylation on Serine 20. Phosphorylation of Survivin residue Serine 20 by Aurora-C and -B appears important for proper chromosome segregation. Taken together, our study suggests that Aurora-C, expressed at low levels in somatic cells, functions as a catalytic component of the CPC together with Aurora-B through mitosis. Elevated expression of Aurora-C in cancer cells alters the structural and functional characteristics of the Aurora-B-CPC leading to chromosomal instability.

  20. Aurora-A kinase phosphorylation of Aurora-A kinase interacting protein (AIP) and stabilization of the enzyme-substrate complex.

    PubMed

    Katayama, Hiroshi; Sasai, Kaori; Czerniak, Bogdan A; Carter, Jennifer L; Sen, Subrata

    2007-12-01

    Aurora-A is an oncogenic kinase that plays essential roles in mitosis as well as cell survival. Aurora-A interacting protein (AIP) was identified as a negative regulator of Aurora-A with its ectopic over expression inducing destabilization of Aurora-A protein. Here we present evidence that in human cells, contrary to the earlier report, AIP functions in stabilizing rather than destabilizing Aurora-A. Furthermore, AIP is phosphorylated on Serine 70 by Aurora-A but not Aurora-B and expression of phosphorylation mimic mutant of AIP results in prolonged protein stability compared to unphosphorylatable mutant. We observed that when co-expressed with AIP, protein levels of both Aurora-A and Aurora-B are markedly elevated regardless of their kinase activities and phosphorylation state of AIP. Interaction of Aurora kinases with AIP is necessary for this elevated stability. This phenomenon is commonly detected in several human cancer cell lines used in this study. Depletion of AIP by RNA interference decreased Aurora-A but not Aurora-B in two of the three cell lines analyzed, indicating that under physiological condition, AIP functions in stabilization of Aurora-A but not Aurora-B, though this regulation may be dependent on additional factors as well. Further, AIP siRNA induced cell cycle arrest at G2/M, which is consistent with anticipated loss of function of Aurora-A in these cells. Thus, our study provides the first evidence of a role for AIP in G2/M cell cycle progression by cooperatively regulating protein stabilization of its up-stream regulator, Aurora-A kinase through protein-protein interaction as well as protein phosphorylation.

  1. Aurora-C Interactions with Survivin and INCENP Reveal Shared and Distinct Features Compared with Aurora-B Chromosome Passenger Protein Complex

    PubMed Central

    Sasai, Kaori; Katayama, Hiroshi; Hawke, David H.; Sen, Subrata

    2016-01-01

    Aurora-C, a member of the Aurora kinase family that can complement Aurora-B function in mitosis is either moderately expressed or repressed in most adult somatic tissues but is active in early embryonic development and expressed at elevated levels in multiple human cancers. Aurora-C overexpression reportedly plays a role in tumorigenic transformation. We performed detailed characterization of Aurora-C interactions with members of the Chromosome Passenger Complex (CPC), Survivin and Inner Centromere Protein (INCENP) in reference to known Aurora-B interactions to understand the functional significance of Aurora-C overexpression in human cancer cells. The results revealed that silencing of Aurora-C or -B individually does not affect localization of the other kinase and the two kinases exist predominantly in independent complexes in vivo. Presence of Aurora-C and -B in molecular complexes of varying as well as overlapping sizes and co-existence in INCENP overexpressing cells indicated oligomerization of ternary complexes under different physiological conditions in vivo. Furthermore, Aurora-C and -B stabilized INCENP through interaction with and phosphorylation of the IN box domain while Aurora-C was activated following Survivin phosphorylation on Serine 20. Phosphorylation of Survivin residue Serine 20 by Aurora-C and –B appears important for proper chromosome segregation. Taken together, our study suggests that Aurora-C, expressed at low levels in somatic cells, functions as a catalytic component of the CPC together with Aurora-B through mitosis. Elevated expression of Aurora-C in cancer cells alters the structural and functional characteristics of the Aurora-B-CPC leading to chromosomal instability. PMID:27332895

  2. The Phenomenon of the Polar Aurora

    NASA Astrophysics Data System (ADS)

    Landsberg, H. E.

    The eerie flickers of auroras have inspired awe since times immemorial. They kindled the fears and superstitions of people in the prescientific era and the curiosity of inquiring minds since. Yet it is only since the arrival of the space age that a full physical understanding has been reached. This has probably stimulated not only substantial journal literature but a number of books which trace the development of that understanding from the supernatural to phenomenology to a reasonably complete physical model. AGU published the work of Eather [1980], and the Nordic experience and contribution is superbly reflected in the treatise of Brekke and Egeland [1983]. A somewhat more theoretical framework is offered by Volland [1984].

  3. The excitation of O2 in auroras

    NASA Technical Reports Server (NTRS)

    Cartwright, D. C.; Trajmar, S.; Williams, W., Jr.

    1972-01-01

    Newly measured electron impact cross sections for excitation of the a 1 Delta g and b 1 Sigma g+ electronic states of O2 were employed to predict the absolute volume emission rates from these states under auroral conditions. A secondary electron electron flux typical of an IBC II nighttime aurora was used and the most important quenching processes were included in the calculations. The new excitation cross sections for the a 1 Delta g and b 1 Sigma g+ states are more than an order of magnitude larger than previous estimates, and lead to correspondingly greater intensities in the atmospheric and IR-atmospheric band systems. The calculated intensity ratios of the volume emission rates of 7621 A and 1.27 microns to that for 3914 A are smaller than obtained from aircraft observations and recent rocket experiments.

  4. Global magnetic anomaly and aurora of Neptune

    NASA Technical Reports Server (NTRS)

    Cheng, Andrew F.

    1990-01-01

    The large offset and tilt of Neptune's dipole magnetic field combine to create a global magnetic anomaly, analogous to but much more important than earth's South Atlantic Anomaly. Energetic particle precipitation loss within the Neptune anomaly creates 'atmospheric drift shadows' within which particle fluxes are greatly reduced. The energetic particle dropout observed by Voyager near closest approach occurred near the predicted times when Voyager passed within the atmospheric drift shadow. Extremely soft, structured bursts of ions and electrons within the drift shadow may result from plasma wave-induced pitch angle scattering of trapped particles confined near the magnetic equator. The dropout does not necessarily imply that Voyager passed through an earth-like discrete auroral zone, as earlier reported. The ion and electron fluxes observed within the dropout period correspond to particles that must precipitate to Neptune's atmosphere within the anomaly region. This anomaly precipitation can account for a major portion of the ultraviolet emissions previously identified as Neptune aurora.

  5. BAA Observers' Workshops: Observing the aurora

    NASA Astrophysics Data System (ADS)

    Gavine, D.

    2004-10-01

    Although auroral and upper-atmosphere research is carried out mainly in polar regions by professional scientists, it is still worthwhile for the amateur to observe this beautiful and sometimes spectacular phenomenon for its own sake. Occasionally, however, the BAA Aurora Section is called upon to supply information on displays to a variety of professional organisations, and so it has become important to receive reports, to log them in a standardised method and to maintain a continuous archive which can be consulted by interested persons. Through the kindness and foresight of the late Dr Michael Gadsden this has been done - all our auroral and noctilucent cloud data from the time of Director James Paton in the 1940s up to the present is preserved in the special Balfour Stewart Archive at the Library of Aberdeen University.

  6. NASA Launches Rocket Into Active Auroras

    NASA Image and Video Library

    2017-09-28

    A test rocket is launched the night of Feb. 17 from the Poker Flat Research Range in Alaska. Test rockets are launched as part of the countdown to test out the radar tracking systems. NASA is launching five sounding rockets from the Poker Range into active auroras to explore the Earth's magnetic environment and its impact on Earth’s upper atmosphere and ionosphere. The launch window for the four remaining rockets runs through March 3. Credit: NASA/Terry Zaperach NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  7. Were Greek temples oriented towards aurorae?

    NASA Astrophysics Data System (ADS)

    Liritzis, Ioannis; Vassiliou, Helen

    2006-02-01

    Two ancient Greek temples of Apollo at Bassae (Phigaleia, western Peloponnese, Greece), and Thermon at Aetolia, (Aetoloacarnania, western central Greece), have a north-south orientation of their main entrances. This is a rather rare alignment of temples in general and specifically of Apollo in classical Greece, where most of them have broadly an east-west orientation. Based on historical and mythological accounts, as well as astronomical orientation measurements, the northern direction orientation of these constructions may relate to the rare, albeit impressive, occurrence of aurorae borealis, the northern lights. These strong lights are attributed to god Apollo by the epithet ``hyperborean'', meaning to the northern lands. Attribution is supported by archaeomagnetic directional data accompanied by auroral occurrence during those times.

  8. Inter-hemispheric asymmetries in Saturn's aurora

    NASA Astrophysics Data System (ADS)

    Badman, Sarah; Lamy, Laurent; Bunce, Emma; Cecconi, Baptiste; Clarke, John; Crary, Frank; Dougherty, Michele; Dyudina, Ulyana; Kinrade, Joe; Kurth, Bill; Melin, Henrik; Mitchell, Don; Nichols, Jonathan; Prange, Renee; Pryor, Wayne; Radioti, Katerina; Schippers, Patricia; Zarka, Philippe

    2017-04-01

    During two intervals in 2016 Saturn's UV aurorae were observed simultaneously in the northern, summer hemisphere by the Hubble Space Telescope and the southern, winter hemisphere by Cassini. For the first time the full auroral region was visible in both hemispheres allowing the nightside auroral morphology to be examined as well as the dayside. We find significant differences in the relative auroral intensities between the two hemispheres, particularly in the most poleward arcs observed under more active magnetospheric conditions. We propose that these asymmetries could be driven by inter-hemispheric field-aligned currents, or, considering the high latitude extent of some features, in association with enhanced auroral precipitation on newly-reconnected field lines. In the latter scenario, the lifetime of the high latitude auroral feature suggests that enhanced precipitation persists for at least 4 hours, longer than previously estimated, as the arc rotates to the nightside.

  9. Study of artificially generated and natural auroras

    NASA Technical Reports Server (NTRS)

    Davis, T. N.

    1973-01-01

    The feasibility of generating artificial auroras by injecting electrons into the upper atmosphere was investigated by using an electron accelerator aboard an Aerobee 350 rocket. Four of the artificial auroral rays were detected and recorded by two geophysical sites separated enough to enable the spatial coordinates of the rays to be determined by triangulation. It was found that (1) the beam remained well collimated; (2) most of the initial beam energy was deposited in the atmosphere; (3) plasma instabilities did not play a significant role; and (4) the orientations of the rays were determined with sufficient accuracy to improve the knowledge of the earth's magnetic field over the Virginia coast. The publications resulting from this research are listed.

  10. The excitation of O2 in auroras.

    NASA Technical Reports Server (NTRS)

    Cartwright, D. C.; Trajmar, S.; Williams, W.

    1972-01-01

    Newly measured electron impact cross sections for excitation of the a super 1 Delta sub g and b super 1 Sigma (plus) sub g electronic states of O2 have been employed to predict the absolute volume emission rates from these states under auroral conditions. A secondary electron flux typical of an IBC II nighttime aurora was used, and the most important quenching processes were included in the calculations. The new excitation cross sections for the a super 1 Delta sub g and b super 1 Sigma (plus) sub g states are more than an order of magnitude larger than previous estimates and lead to correspondingly greater intensities in the atmospheric and IR atmospheric band systems. The calculated intensity ratios of the volume emission rates of 7621 A and 1.27 micron to that for 3914 A are smaller than those obtained from aircraft observations and recent rocket experiments.

  11. Hyperspectral all-sky imaging of auroras.

    PubMed

    Sigernes, Fred; Ivanov, Yuriy; Chernouss, Sergey; Trondsen, Trond; Roldugin, Alexey; Fedorenko, Yury; Kozelov, Boris; Kirillov, Andrey; Kornilov, Ilia; Safargaleev, Vladimir; Holmen, Silje; Dyrland, Margit; Lorentzen, Dag; Baddeley, Lisa

    2012-12-03

    A prototype auroral hyperspectral all-sky camera has been constructed and tested. It uses electro-optical tunable filters to image the night sky as a function of wavelength throughout the visible spectrum with no moving mechanical parts. The core optical system includes a new high power all-sky lens with F-number equal to f/1.1. The camera has been tested at the Kjell Henriksen Observatory (KHO) during the auroral season of 2011/2012. It detects all sub classes of aurora above ~½ of the sub visual 1kR green intensity threshold at an exposure time of only one second. Supervised classification of the hyperspectral data shows promise as a new method to process and identify auroral forms.

  12. The Aurora Project: A new sail layout

    NASA Astrophysics Data System (ADS)

    Genta, Giancarlo; Brusa, Eugenio

    1999-05-01

    Aurora spacecraft is a scientific probe propelled by a "fast" solar sail whose first goal is to perform a technology assessment mission. The main characteristic of the sail is its low mass, which implies the absence of a plastic backing of the aluminum film and the lightness of the whole structure. In previous structural studies the limiting factor has been shown to be the elastic stability of a number of structural members subject to compressive loads. An alternative structural layout is here suggested: an inflatable beam, which is kept pressurized also after the deployment, relieves all compressive stresses, allowing a very simple configuration and a straightforward deployment procedure. However, as the mission profile requires a trajectory passing close to the Sun, a configuration different from the 'parachute' sail proposed in another paper, must be used.

  13. The AURORA initiative for metastatic breast cancer.

    PubMed

    Zardavas, D; Maetens, M; Irrthum, A; Goulioti, T; Engelen, K; Fumagalli, D; Salgado, R; Aftimos, P; Saini, K S; Sotiriou, C; Campbell, P; Dinh, P; von Minckwitz, G; Gelber, R D; Dowsett, M; Di Leo, A; Cameron, D; Baselga, J; Gnant, M; Goldhirsch, A; Norton, L; Piccart, M

    2014-11-11

    Metastatic breast cancer is one of the leading causes of cancer-related mortality among women in the Western world. To date most research efforts have focused on the molecular analysis of the primary tumour to dissect the genotypes of the disease. However, accumulating evidence supports a molecular evolution of breast cancer during its life cycle, with metastatic lesions acquiring new molecular aberrations. Recognising this critical gap of knowledge, the Breast International Group is launching AURORA, a large, multinational, collaborative metastatic breast cancer molecular screening programme. Approximately 1300 patients with metastatic breast cancer who have received no more than one line of systemic treatment for advanced disease will, after giving informed consent, donate archived primary tumour tissue, as well as will donate tissue collected prospectively from the biopsy of metastatic lesions and blood. Both tumour tissue types, together with a blood sample, will then be subjected to next generation sequencing for a panel of cancer-related genes. The patients will be treated at the discretion of their treating physicians per standard local practice, and they will be followed for clinical outcome for 10 years. Alternatively, depending on the molecular profiles found, patients will be directed to innovative clinical trials assessing molecularly targeted agents. Samples of outlier patients considered as 'exceptional responders' or as 'rapid progressors' based on the clinical follow-up will be subjected to deeper molecular characterisation in order to identify new prognostic and predictive biomarkers. AURORA, through its innovative design, will shed light onto some of the unknown areas of metastatic breast cancer, helping to improve the clinical outcome of breast cancer patients.

  14. A Panchromatic View of Brown Dwarf Aurorae

    NASA Astrophysics Data System (ADS)

    Pineda, J. Sebastian; Hallinan, Gregg; Kao, Melodie M.

    2017-09-01

    Stellar coronal activity has been shown to persist into the low-mass star regime, down to late M-dwarf spectral types. However, there is now an accumulation of evidence suggesting that at the end of the main sequence, there is a transition in the nature of the magnetic activity from chromospheric and coronal to planet-like and auroral, from local impulsive heating via flares and MHD wave dissipation to energy dissipation from strong large-scale magnetospheric current systems. We examine this transition and the prevalence of auroral activity in brown dwarfs through a compilation of multiwavelength surveys of magnetic activity, including radio, X-ray, and optical. We compile the results of those surveys and place their conclusions in the context of auroral emission as a consequence of large-scale magnetospheric current systems that accelerate energetic electron beams and drive the particles to impact the cool atmospheric gas. We explore the different manifestations of auroral phenomena, like Hα, in brown dwarf atmospheres and define their distinguishing characteristics. We conclude that large-amplitude photometric variability in the near-infrared is most likely a consequence of clouds in brown dwarf atmospheres, but that auroral activity may be responsible for long-lived stable surface features. We report a connection between auroral Hα emission and quiescent radio emission in electron cyclotron maser instability pulsing brown dwarfs, suggesting a potential underlying physical connection between quiescent and auroral emissions. We also discuss the electrodynamic engines powering brown dwarf aurorae and the possible role of satellites around these systems both to power the aurorae and seed the magnetosphere with plasma.

  15. Observation and theory of the radar aurora

    SciTech Connect

    Sahr, J.D.

    1990-01-01

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new experiments to test new and existing theories.

  16. SPICAM observations and modeling of Mars aurorae

    NASA Astrophysics Data System (ADS)

    Soret, Lauriane; Gérard, Jean-Claude; Libert, Ludivine; Shematovich, Valery I.; Bisikalo, Dmitry V.; Stiepen, Arnaud; Bertaux, Jean-Loup

    2016-01-01

    Martian aurorae have been detected with the SPICAM instrument on board Mars Express both in the nadir and the limb viewing modes. In this study, we focus on three limb observations to determine both the altitudes and the intensities of the auroral emissions. The CO (a3Π-X1Σ) Cameron bands between 190 and 270 nm, the CO (A1Π-X1Σ+) Fourth Positive system (CO 4P) between 135 and 170 nm, the CO2+ (B2Σu+-X2Πg) doublet at 289 nm, the OI at 297.2 nm and the 130.4 nm OI triplet emissions have been identified in the spectra and in the time variations of the signals. The intensities of these auroral emissions have been quantified and the altitude of the strongest emission of the CO Cameron bands has been estimated to be 137 ± 27 km. The locations of these auroral events have also been determined and correspond to the statistical boundary of open-closed magnetic field lines, in cusp-like structures. The observed altitudes of the auroral emissions are reproduced by a Monte-Carlo model of electron transport in the Martian thermosphere for mono-energetic electrons between 40 and 200 eV. No correlation between electron fluxes measured in the upper thermosphere and nadir auroral intensity has been found. Here, we simulate auroral emissions observed both at the limb and at the nadir using electron energy spectra simultaneously measured with the ASPERA-3/ELS instrument. The simulated altitudes are in very good agreement with the observations. We find that predicted vertically integrated intensities for the various auroral emissions are overestimated, probably as a consequence of the inclination and curvature of the magnetic field line threading the aurora. However, the relative brightness of the CO and CO2+ emissions is in good agreement with the observations.

  17. Aurora Isoform Selectivity: Design and Synthesis of Imidazo[4,5-b]pyridine Derivatives as Highly Selective Inhibitors of Aurora-A Kinase in Cells

    PubMed Central

    2013-01-01

    Aurora-A differs from Aurora-B/C at three positions in the ATP-binding pocket (L215, T217, and R220). Exploiting these differences, crystal structures of ligand–Aurora protein interactions formed the basis of a design principle for imidazo[4,5-b]pyridine-derived Aurora-A-selective inhibitors. Guided by a computational modeling approach, appropriate C7-imidazo[4,5-b]pyridine derivatization led to the discovery of highly selective inhibitors, such as compound 28c, of Aurora-A over Aurora-B. In HCT116 human colon carcinoma cells, 28c and 40f inhibited the Aurora-A L215R and R220K mutants with IC50 values similar to those seen for the Aurora-A wild type. However, the Aurora-A T217E mutant was significantly less sensitive to inhibition by 28c and 40f compared to the Aurora-A wild type, suggesting that the T217 residue plays a critical role in governing the observed isoform selectivity for Aurora-A inhibition. These compounds are useful small-molecule chemical tools to further explore the function of Aurora-A in cells. PMID:24195668

  18. Are Accurins the cure for Aurora kinase inhibitors?

    PubMed

    Bearss, David J

    2016-02-10

    A nanoparticle formulation of an Aurora B inhibitor increases antitumor efficacy and reduces toxicity, which may be a precedent for the use of this technology with other small molecules (Ashton et al., this issue).

  19. Canine osteosarcoma cells exhibit resistance to aurora kinase inhibitors.

    PubMed

    Cannon, C M; Pozniak, J; Scott, M C; Ito, D; Gorden, B H; Graef, A J; Modiano, J F

    2015-03-01

    We evaluated the effect of Aurora kinase inhibitors AZD1152 and VX680 on canine osteosarcoma cells. Cytotoxicity was seen in all four cell lines; however, half-maximal inhibitory concentrations were significantly higher than in human leukaemia and canine lymphoma cells. AZD1152 reduced Aurora kinase B phosphorylation, indicating resistance was not because of failure of target recognition. Efflux mediated by ABCB1 and ABCG2 transporters is one known mechanism of resistance against these drugs and verapamil enhanced AZD1152-induced apoptosis; however, these transporters were only expressed by a small percentage of cells in each line and the effects of verapamil were modest, suggesting other mechanisms contribute to resistance. Our results indicate that canine osteosarcoma cells are resistant to Aurora kinase inhibitors and suggest that these compounds are unlikely to be useful as single agents for this disease. Further investigation of these resistance mechanisms and the potential utility of Aurora kinase inhibitors in multi-agent protocols is warranted.

  20. A new Director for the BAA Aurora Section

    NASA Astrophysics Data System (ADS)

    Gavine, D.

    2011-02-01

    from 2011 January 1, Dr Dave Gavine handed over the Aurora Section Directorship to Ken Kennedy, who has been Assistant Director for the last five years, with special responsibility for Noctilucent Clouds, currently the Section's most important work.

  1. 5. Aurora Borealis Pass over the United States at Night

    NASA Image and Video Library

    This video of the United States at night and the Aurora Borealis was taken by the crew of Expedition 29 on board the International Space Station. This sequence of shots was taken September 29, 2011...

  2. Solar Storm Triggers Whole-Planet Aurora at Mars

    NASA Image and Video Library

    2017-09-29

    These images show the sudden appearance of a bright aurora on Mars during a solar storm in September 2017. The purple-white color scheme shows the intensity of ultraviolet light seen on Mars' night side before (left) and during (right) the event. A simulated image of Mars for the same time and orientation has been added, with the dayside crescent visible on the right. The auroral emission appears brightest at the edges of the planet where the line of sight passes along the length of the glowing atmosphere layer. The data are from observations by the Imaging Ultraviolet Spectrograph instrument (IUVS) on NASA's Mars Atmosphere and Volatile Evolution orbiter, or MAVEN. Note that, unlike auroras on Earth, the Martian aurora is not concentrated at the planet's polar regions. This is because Mars has no strong magnetic field like Earth's to concentrate the aurora near the poles. https://photojournal.jpl.nasa.gov/catalog/PIA21855

  3. ISS Expedition 42 Time Lapse Video of Earth and Aurora

    NASA Image and Video Library

    2015-05-18

    This time lapse video taken during ISS Expedition 42 is assembled from JSC still photo collection (still photos iss042e214317 - iss042e215156). Shows Earth views and aurora. Solar Array Wing (SAW) in foreground.

  4. Drugging MYCN through an allosteric transition in Aurora Kinase A

    PubMed Central

    Gustafson, William Clay; Meyerowitz, Justin Gabriel; Nekritz, Erin A.; Chen, Justin; Benes, Cyril; Charron, Elise; Simonds, Erin Fitzgerald; Seeger, Robert; Matthay, Katherine; Hertz, Nicholas T.; Eilers, Martin; Shokat, Kevan M.; Weiss, William A.

    2014-01-01

    Summary MYC proteins are major drivers of cancer, yet are considered undruggable, as their DNA binding domains are composed of two extended alpha helices with no apparent surfaces for small molecule binding. Proteolytic degradation of MYCN protein is regulated in part by a kinase-independent function of Aurora A. We describe a class of inhibitors that disrupts the native conformation of Aurora A, and drives degradation of MYCN protein across MYCN-driven cancers. Comparison of co-crystal structures with structure-activity relationships across multiple inhibitors and chemotypes, coupled with mechanistic studies and biochemical assays, delineates an Aurora A conformation-specific effect on proteolytic degradation of MYCN, rather than simple nanomolar-level inhibition of Aurora A kinase activity. PMID:25175806

  5. Equatorward and poleward expansion of the auroras during auroral substorms

    NASA Technical Reports Server (NTRS)

    Nakamura, Rumi; Oguti, Takasi; Yamamoto, Tatsundo; Kokubun, Susumu

    1993-01-01

    The formation of the auroral bulge is investigated on the basis of all-sky TV auroral data with high spatial and temporal resolution. Ways in which the discrete auroral structures within the poleward expanding bulge develop systematically toward the west, the east, and also equatorward from a localized breakup region are shown. Auroral structure at the western end of the bulge (a surge) develops with clockwise rotation as viewed along the magnetic field direction. At the eastern part of the bulge, thin auroral features propagate eastward from the breakup region. Around the central meridian of the bulge, auroral features expand equatorward and become north-south aligned (the N-S aurora). The N-S aurora and the eastward propagating aurora develop into diffuse and pulsating aurora after the expansion. It is suggested that these discrete auroral structures in the bulge develop along the plasma streamlines in a localized distorted two-cell equipotential distribution.

  6. RadNet Air Data From Aurora, IL

    EPA Pesticide Factsheets

    This page presents radiation air monitoring and air filter analysis data for Aurora, IL from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  7. IK-guided PP2A suppresses Aurora B activity in the interphase of tumor cells.

    PubMed

    Lee, Sunyi; Jeong, Ae Lee; Park, Jeong Su; Han, Sora; Jang, Chang-Young; Kim, Keun Il; Kim, Yonghwan; Park, Jong Hoon; Lim, Jong-Seok; Lee, Myung Sok; Yang, Young

    2016-09-01

    Aurora B activation is triggered at the mitotic entry and required for proper microtubule-kinetochore attachment at mitotic phase. Therefore, Aurora B should be in inactive form in interphase to prevent aberrant cell cycle progression. However, it is unclear how the inactivation of Aurora B is sustained during interphase. In this study, we find that IK depletion-induced mitotic arrest leads to G2 arrest by Aurora B inhibition, indicating that IK depletion enhances Aurora B activation before mitotic entry. IK binds to Aurora B, and colocalizes on the nuclear foci during interphase. Our data further show that IK inhibits Aurora B activation through recruiting PP2A into IK and Aurora B complex. It is thus believed that IK, as a scaffold protein, guides PP2A into Aurora B to suppress its activity in interphase until mitotic entry.

  8. Aurora Kinase Inhibitors in Oncology Clinical Trials: Current State of the Progress.

    PubMed

    Falchook, Gerald S; Bastida, Christel C; Kurzrock, Razelle

    2015-12-01

    The Aurora kinase family of kinases (Aurora A, B, and C) are involved in multiple mitotic events, and aberrant expression of these kinases is associated with tumorigenesis. Aurora A and Aurora B are validated anticancer targets, and the development of Aurora kinase inhibitors has progressed from preclinical to clinical studies. A variety of Aurora A, B and pan-Aurora kinase inhibitors have entered the clinic. The main side effects include febrile neutropenia, stomatitis, gastrointestinal toxicity, hypertension, and fatigue. Responses including complete remissions have been described in diverse, advanced malignancies, most notably ovarian cancer and acute myelogenous leukemia. This review highlights the biologic rationale for Aurora kinase as a target, and clinical trials involving Aurora kinase inhibitors, with particular emphasis on published early phase studies, and the observed anti-tumor activity of these agents.

  9. The role and targeting of Aurora kinases in head and neck cancer

    PubMed Central

    Mehra, Ranee; Serebriiskii, Ilya G.; Burtness, Barbara; Astsaturov, Igor; Golemis, Erica A.

    2014-01-01

    Summary Controlled activation of the Aurora kinases regulates mitotic progression in normal cells. Overexpression and hyperactivation of the Aurora-A and -B kinases play a leading role in tumorigenesis, inducing aneuploidy and genomic instability. In squamous cell carcinomas of the head and neck (SCCHN), overexpression of Aurora-A is associated with decreased survival, and reduction of Aurora-A and -B expression inhibits SCCHN cell growth and increases apoptosis. In this article, we provide a basic overview of the biological functions of Aurora kinases in normal cells and in cancer, and review both small studies and high throughput datasets that implicate Aurora-A, particularly, in the pathogenesis of SCCHN. Early phase clinical trials are beginning to evaluate the activity of small molecule inhibitors of the Aurora kinases. We summarize the state of current trials evaluating Aurora inhibitors in SCCHN, and discuss rational directions for future drug combination trials and biomarkers for use with Aurora-inhibiting agents. PMID:23993387

  10. Aurora kinase inhibition: a new light in the sky?

    PubMed

    Linardopoulos, Spiros; Blagg, Julian

    2015-07-09

    The quest for potent and selective small molecule inhibitors of the Aurora kinases has been long and resource intensive with multiple agents progressed to the clinic. To definitively explore the potential for clinical efficacy at well-tolerated dosing schedules requires a well-characterized, selective inhibitor with pharmacokinetic properties, flexible dosing regimen, and suite of target engagement biomarkers suitable for clinical use. AMG900 is a promising opportunity to definitively test the clinical benefit of dual Aurora kinase A and B inhibition.

  11. Saturn's aurora observed by the Cassini camera at visible wavelengths

    NASA Astrophysics Data System (ADS)

    Dyudina, Ulyana A.; Ingersoll, Andrew P.; Ewald, Shawn P.; Wellington, Danika

    2016-01-01

    The first observations of Saturn's visible-wavelength aurora were made by the Cassini camera. The aurora was observed between 2006 and 2013 in the northern and southern hemispheres. The color of the aurora changes from pink at a few hundred km above the horizon to purple at 1000-1500 km above the horizon. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with laboratory simulated auroras. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs between 70° and 80° latitude north and between 65° and 80° latitude south, which sometimes spiral around the pole, and sometimes form double arcs. A large 10,000-km-scale longitudinal brightness structure persists for more than 100 h. This structure rotates approximately together with Saturn. On top of the large steady structure, the auroras brighten suddenly on the timescales of a few minutes. These brightenings repeat with a period of ∼1 h. Smaller, 1000-km-scale structures may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The persistence of nearly-corotating large bright longitudinal structure in the auroral oval seen in two movies spanning 8 and 11 rotations gives an estimate on the period of 10.65 ± 0.15 h for 2009 in the northern oval and 10.8 ± 0.1 h for 2012 in the southern oval. The 2009 north aurora period is close to the north branch of Saturn Kilometric Radiation (SKR) detected at that time.

  12. Morphology of Omega band aurora observed by THEMIS all-sky imagers

    NASA Astrophysics Data System (ADS)

    Sato, N.; Yukimatu, A. S.; Tanaka, Y.; Hori, T.

    2016-12-01

    We examined Omega band auroras observed with the THEMIS ground based all-sky imager network. Using 8 years data from January 2007 we found a large number of events ( 330) that showed characteristics of omega band aurora. We examined optical signatures on the generation of omega band aurora from the growth to the declining through expansion period. We found that Omega band aurora can be classified into the following three sub-types: 1) Classical Omega band, 2) Tongue/torch, and combined type of 3) Omega band and Tongue/torch. The interesting features for the growth of omega band aurora are as follows: the omega band aurora grew from a faint seed, not via distortion of pre-existing east-west band aurora. The aurora did not show any shear motion during the growth of auroral activity. A black hole-like dark aurora was found during growth and expansion period. Eastern boundary on omega aurora shows a clear contrast between light and darkness. Omega band aurora generally consists with intense pulsating auroras. In this study we show morphological features on the generation of optical omega auroras and also show statistical results on the occurrences of three different type of aurora, eastward drift speed, duration and recurrent frequency of the event. Then we attempt to provide insight into the generation of these auroral forms in the magnetosphere-ionosphere system.

  13. Aurora-A Kinase: A Potent Oncogene and Target for Cancer Therapy.

    PubMed

    Yan, Min; Wang, Chunli; He, Bin; Yang, Mengying; Tong, Mengying; Long, Zijie; Liu, Bing; Peng, Fei; Xu, Lingzhi; Zhang, Yan; Liang, Dapeng; Lei, Haixin; Subrata, Sen; Kelley, Keith W; Lam, Eric W-F; Jin, Bilian; Liu, Quentin

    2016-11-01

    The Aurora kinase family is comprised of three serine/threonine kinases, Aurora-A, Aurora-B, and Aurora-C. Among these, Aurora-A and Aurora-B play central roles in mitosis, whereas Aurora-C executes unique roles in meiosis. Overexpression or gene amplification of Aurora kinases has been reported in a broad range of human malignancies, pointing to their role as potent oncogenes in tumorigenesis. Aurora kinases therefore represent promising targets for anticancer therapeutics. A number of Aurora kinase inhibitors (AKIs) have been generated; some of which are currently undergoing clinical evaluation. Recent studies have unveiled novel unexpected functions of Aurora kinases during cancer development and the mechanisms underlying the anticancer actions of AKIs. In this review, we discuss the most recent advances in Aurora-A kinase research and targeted cancer therapy, focusing on the oncogenic roles and signaling pathways of Aurora-A kinases in promoting tumorigenesis, the recent preclinical and clinical AKI data, and potential alternative routes for Aurora-A kinase inhibition.

  14. Evolutionary relationships of Aurora kinases: implications for model organism studies and the development of anti-cancer drugs.

    PubMed

    Brown, James R; Koretke, Kristin K; Birkeland, Marian L; Sanseau, Philippe; Patrick, Denis R

    2004-10-12

    As key regulators of mitotic chromosome segregation, the Aurora family of serine/threonine kinases play an important role in cell division. Abnormalities in Aurora kinases have been strongly linked with cancer, which has lead to the recent development of new classes of anti-cancer drugs that specifically target the ATP-binding domain of these kinases. From an evolutionary perspective, the species distribution of the Aurora kinase family is complex. Mammals uniquely have three Aurora kinases, Aurora-A, Aurora-B, and Aurora-C, while for other metazoans, including the frog, fruitfly and nematode, only Aurora-A and Aurora-B kinases are known. The fungi have a single Aurora-like homolog. Based on the tacit assumption of orthology to human counterparts, model organism studies have been central to the functional characterization of Aurora kinases. However, the ortholog and paralog relationships of these kinases across various species have not been rigorously examined. Here, we present comprehensive evolutionary analyses of the Aurora kinase family. Phylogenetic trees suggest that all three vertebrate Auroras evolved from a single urochordate ancestor. Specifically, Aurora-A is an orthologous lineage in cold-blooded vertebrates and mammals, while structurally similar Aurora-B and Aurora-C evolved more recently in mammals from a duplication of an ancestral Aurora-B/C gene found in cold-blooded vertebrates. All so-called Aurora-A and Aurora-B kinases of non-chordates are ancestral to the clade of chordate Auroras and, therefore, are not strictly orthologous to vertebrate counterparts. Comparisons of human Aurora-B and Aurora-C sequences to the resolved 3D structure of human Aurora-A lends further support to the evolutionary scenario that vertebrate Aurora-B and Aurora-C are closely related paralogs. Of the 26 residues lining the ATP-binding active site, only three were variant and all were specific to Aurora-A. In this study, we found that invertebrate Aurora-A and Aurora

  15. Equatorward evolution of auroras from the poleward auroral boundary

    NASA Astrophysics Data System (ADS)

    Saka, O.; Hayashi, K.; Thomsen, M. F.

    2016-07-01

    An all-sky imager installed at the midnight sector in Dawson City (66.0° in geomagnetic latitude) recorded the equatorward evolution of auroras from the auroral poleward boundary. The auroras evolved as shear layers expanding southeastward with velocities of 1-4 km/s, referred to as N-S auroras, and occurred during the transient intensification of the convection electric fields in the nighttime magnetosphere, as inferred from an electron spectrogram at geosynchronous altitudes. A continuous increase in the inclination angle of the field lines and magnetic field perturbations associated with propagating ionospheric loop currents were observed in the auroral zone during the N-S auroras. Simultaneously, Pc4 pulsations were observed at low latitudes from night to day sectors. We conclude the following: (1) the N-S auroras are an auroral manifestation of the earthward drift of plasma sheet electrons in the equatorial plane associated with transient and localized convection electric fields; (2) the Pc4 pulsations are produced in the magnetosphere by plasma sheet ions in the plasmasphere. The localized convection fields produce a vortical motion of plasmas in the equatorial plane, which may initiate the N-S auroras and ionospheric loop currents in the auroral zone.

  16. A Note on the Height of Auroras by Leonhard Euler

    NASA Astrophysics Data System (ADS)

    Schröder, Wilfried

    In former times, mostly before the end of the 19th century, many speculations were made about the height of the Earth's atmosphere. Scientists also discussed the height of the auroras, which were often observed in middle Europe. Mostly, people thought the auroras were manifestations of the lower Earth's atmosphere, and that they formed a circle inside of it. Only a few speculations were devoted to the exact height and nature of these phenomena. They were thought to be signs from God, until the appearance of the aurora on 17 March 1716 (for detail, see Schröder [2001]). An interesting letter written by Leonhard Euler (1707-1783), a Swiss mathematician and member of the Berlin Academy of Sciences, to the theologian and scholar Johann Esaias Silberschlag (1716-1791)-also a member of the Berlin Academy of Sciences- gives some insight into the discussion that took place in the 18th century. Euler wrote in his letter that the auroras, similar to the great meteors or fireballs, must be placed in the high atmosphere, mostly above the height of the meteors. For Euler, it was clear that meteors, fireballs, and auroras were all objects associated with the Earth's atmosphere. In those days, the idea that the auroral phenomena were caused in the atmosphere and were part of its constitution was new. Following the 17 March 1716 event, scientists of the day concluded that the height of the aurora was above that of the normally observed clouds.

  17. Saturn's northern auroras as observed using the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Nichols, J. D.; Badman, S. V.; Bunce, E. J.; Clarke, J. T.; Cowley, S. W. H.; Hunt, G. J.; Provan, G.

    2016-01-01

    We discuss the features of Saturn's northern FUV auroras as observed during a program of Hubble Space Telescope observations which executed over 2011-2013 and culminated, along with Cassini observations, in a comprehensive multi-spectral observing campaign. Our 2011-2013 observations of the northern aurora are also compared with those from our 2007-2008 observation of the southern aurora. We show that the variety of morphologies of the northern auroras is broadly consistent with the southern, and determine the statistical equatorward and poleward boundary locations. We find that our boundaries are overall consistent with previous observations, although a modest poleward displacement of the poleward boundaries is due to the increased prevalence of poleward auroral patches in the noon and afternoon sectors during this program, likely due to the solar wind interaction. We also show that the northern auroral oval oscillates with the northern planetary period oscillation (PPO) phase in an elongated ellipse with semi-major axis ∼1.6° oriented along the post-dawn/post-dusk direction. We further show that the northern auroras exhibit dawn-side brightenings at zero northern magnetic PPO phase, although there is mixed evidence of auroral emissions fixed in the rotating frame of the northern PPO current system, such that overall the dependence of the auroras on northern magnetic phase is somewhat weak.

  18. A New Aurora in Anaplastic Thyroid Cancer Therapy

    PubMed Central

    Baldini, Enke; D'Armiento, Massimino

    2014-01-01

    Anaplastic thyroid cancers (ATC) are among the most aggressive human neoplasms with a dire prognosis and a median survival time of few months from the diagnosis. The complete absence of effective therapies for ATC renders the identification of novel therapeutic approaches sorely needed. Chromosomal instability, a feature of all human cancers, is thought to represent a major driving force in thyroid cancer progression and a number of mitotic kinases showing a deregulated expression in malignant thyroid tissues are now held responsible for thyroid tumor aneuploidy. These include the three members of the Aurora family (Aurora-A, Aurora-B, and Aurora-C), serine/threonine kinases that regulate multiple aspects of chromosome segregation and cytokinesis. Over the last few years, several small molecule inhibitors targeting Aurora kinases were developed, which showed promising antitumor effects against a variety of human cancers, including ATC, in preclinical studies. Several of these molecules are now being evaluated in phase I/II clinical trials against advanced solid and hematological malignancies. In the present review we will describe the structure, expression, and mitotic functions of the Aurora kinases, their implications in human cancer progression, with particular regard to ATC, and the effects of their functional inhibition on malignant cell proliferation. PMID:25097550

  19. Solar activity around AD 775 from aurorae and radiocarbon

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Neuhäuser, D. L.

    2015-04-01

    A large variation in 14C around AD 775 has been considered to be caused by one or more solar super-flares within one year. We critically review all known aurora reports from Europe as well as the Near, Middle, and Far East from AD 731 to 825 and find 39 likely true aurorae plus four more potential aurorae and 24 other reports about halos, meteors, thunderstorms etc., which were previously misinterpreted as aurorae or misdated; we assign probabilities for all events according to five aurora criteria. We find very likely true aurorae in AD 743, 745, 762, 765, 772, 773, 793, 796, 807, and 817. There were two aurorae in the early 770s observed near Amida (now Diyarbak\\i r in Turkey near the Turkish-Syrian border), which were not only red, but also green-yellow - being at a relatively low geomagnetic latitude, they indicate a relatively strong solar storm. However, it cannot be argued that those aurorae (geomagnetic latitude 43 to 50°, considering five different reconstructions of the geomagnetic pole) could be connected to one or more solar super-flares causing the 14C increase around AD 775: There are several reports about low- to mid-latitude aurorae at 32 to 44° geomagnetic latitude in China and Iraq; some of them were likely observed (quasi-)simultaneously in two of three areas (Europe, Byzantium/Arabia, East Asia), one lasted several nights, and some indicate a particularly strong geomagnetic storm (red colour and dynamics), namely in AD 745, 762, 793, 807, and 817 - always without 14C peaks. We use 39 likely true aurorae as well as historic reports about sunspots together with the radiocarbon content from tree rings to reconstruct the solar activity: From AD {˜ 733} to {˜ 823}, we see at least nine Schwabe cycles; instead of one of those cycles, there could be two short, weak cycles - reflecting the rapid increase to a high 14C level since AD 775, which lies at the end of a strong cycle. In order to show the end of the dearth of naked-eye sunspots, we

  20. The effects of a mid-day nap on the neurocognitive performance of first-year medical residents: a controlled interventional pilot study.

    PubMed

    Amin, Mohammad M; Graber, Mark; Ahmad, Khalid; Manta, Dragos; Hossain, Sayeed; Belisova, Zuzana; Cheney, William; Gold, Morris S; Gold, Avram R

    2012-10-01

    Despite shorter duty hours, fatigue remains a problem among medical residents. The authors tested the effect of a short, mid-day nap on the cognitive functioning and alertness of first-year internal medicine (IM) residents during normal duty hours. This was a controlled, interventional study performed between July 2008 and April 2010. The authors recruited a nap group of 18 residents and a rest (control) group of 11 residents. Investigators connected all participants to an ambulatory sleep monitor before the beginning of their shifts in order to monitor rolling eye movements, a proxy for attention failures. At mid-day, both groups took Conner's Continuous Performance Test (CPT II) to evaluate their cognitive functioning and then were placed in a reclining chair designed for napping. The authors instructed nap group residents to nap for up to 20 minutes and chatted with control group residents to prevent them from napping. All residents took the CPT II again immediately after the intervention. Residents' attention failures were recorded until the end of the workday. The authors compared the mean outcome parameters of the two groups through analysis of variance, using effect-of-treatment and baseline covariates. Nap group participants slept a mean of 8.4±3.0 minutes. Compared with controls whose cognitive functioning and number of attention failures did not change from morning to afternoon, the nap group's cognitive functioning improved and their number of attention failures decreased. A short, mid-day nap can improve cognitive functioning and alertness among first-year IM residents.

  1. A genetic variant of Aurora Kinase A promotes genomic instability leading to highly malignant skin tumors

    PubMed Central

    Torchia, Enrique C.; Chen, Yiyun; Sheng, Hong; Katayama, Hiroshi; Fitzpatrick, James; Brinkley, William R.; Sen, Subrata; Roop, Dennis R.

    2009-01-01

    Aurora Kinase A (Aurora-A) belongs to a highly conserved family of mitotis-regulating serine/threonine kinases implicated in epithelial cancers. Initially we examined Aurora-A expression levels at different stages of human skin cancer. Nuclear Aurora-A was detected in benign lesions, and became more diffused but broadly expressed in well and poorly differentiated SCC, indicating that Aurora-A deregulation may contribute to SCC development. To mimic the overexpression of Aurora-A observed in human skin cancers, we established a gene-switch (GS) mouse model in which the human variant of Aurora-A (Phe31Ile) was expressed in the epidermis upon topical application of the inducer, RU486 (Aurora-AGS). Overexpression of Aurora-A alone or in combination with the tumor promoter, TPA, did not result in SCC formation in Aurora-AGS mice. Moreover, Aurora-A overexpression in naive keratinocytes resulted in spindle defects in vitro and marked cell death in vivo, suggesting that the failure of Aurora-A to initiate tumorigenesis was due to induction of catastrophic cell death. However, Aurora-A overexpression combined with exposure to TPA and the mutagen, DMBA, accelerated SCC development with greater metastastic activity than control mice, indicating that Aurora-A cannot initiate skin carcinogenesis, but rather promotes the malignant conversion of skin papillomas. Further characterization of SCCs revealed centrosome amplification and genomic alterations by array CGH analysis, indicating that Aurora-A overexpression induces a high level of genomic instability that favors the development of aggressive and metastatic tumors. Our findings strongly implicate Aurora-A overexpression in the malignant progression of skin tumors and suggest that Aurora-Amay be an important therapeutic target. PMID:19738056

  2. Aurora kinase inhibition overcomes cetuximab resistance in squamous cell cancer of the head and neck.

    PubMed

    Hoellein, Alexander; Pickhard, Anja; von Keitz, Fabienne; Schoeffmann, Stephanie; Piontek, Guido; Rudelius, Martina; Baumgart, Anja; Wagenpfeil, Stefan; Peschel, Christian; Dechow, Tobias; Bier, Henning; Keller, Ulrich

    2011-08-01

    Squamous cell cancer of the head and neck (SCCHN) is the sixth leading cause for cancer deaths worldwide. Despite extense knowledge of risk factors and pathogenesis about 50 percent of all patients and essentially every patient with metastatic SCCHN eventually die from this disease. We analyzed the clinical data and performed immunohistochemistry for Epidermal growth factor receptor (EGFR) and Aurora kinase A (Aurora-A) expression in 180 SCCHN patients. Patients characterized by elevated EGFR and elevated Aurora-A protein expression in tumor tissue represent a risk group with poor disease-free and overall survival (EGFR(low)Aurora-A(low) versus EGFR(high)Aurora-A(high), p = 0.024). Treating SCCHN cell lines with a pan-Aurora kinase inhibitor resulted in defective cytokinesis, polyploidy and apoptosis, which was effective irrespective of the EGFR status. Combined Aurora kinase and EGFR targeting using a monoclonal anti-EGFR antibody was more effective compared to single EGFR and Aurora kinase inhibition. Comparing pan-Aurora kinase and Aurora-A targeting hints towards a strong and clinically relevant biological effect mediated via Aurora kinase B. Taken together, our findings characterize a new poor risk group in SCCHN patients defined by elevated EGFR and Aurora-A protein expression. Our results demonstrate that combined targeting of EGFR and Aurora kinases represents a therapeutic means to activate cell cycle checkpoints and apoptosis in SCCHN.

  3. Sporadic aurorae observed in East Asia

    NASA Astrophysics Data System (ADS)

    Willis, D. M.; Stephenson, F. R.; Fang, Huiping

    2007-03-01

    All the accessible auroral observations recorded in Chinese and Japanese histories during the interval AD 1840-1911 are investigated in detail. Most of these auroral records have never been translated into a Western language before. The East Asian auroral reports provide information on the date and approximate location of each auroral observation, together with limited scientific information on the characteristics of the auroral luminosity such as colour, duration, extent, position in the sky and approximate time of occurrence. The full translations of the original Chinese and Japanese auroral records are presented in an appendix, which contains bibliographic details of the various historical sources. (There are no known reliable Korean observations during this interval.) A second appendix discusses a few implausible "auroral" records, which have been rejected. The salient scientific properties of all exactly dated and reliable East Asian auroral observations in the interval AD 1840-1911 are summarised succinctly. By comparing the relevant scientific information on exactly dated auroral observations with the lists of great geomagnetic storms compiled by the Royal Greenwich Observatory, and also the tabulated values of the Ak (Helsinki) and aa (Greenwich and Melbourne) magnetic indices, it is found that 5 of the great geomagnetic storms (aa>150 or Ak>50) during either the second half of the nineteenth century or the first decade of the twentieth century are clearly identified by extensive auroral displays observed in China or Japan. Indeed, two of these great storms produced auroral displays observed in both countries on the same night. Conversely, at least 29 (69%) of the 42 Chinese and Japanese auroral observations occurred at times of weak-to-moderate geomagnetic activity (aa or Ak≤50). It is shown that these latter auroral displays are very similar to the more numerous (about 50) examples of sporadic aurorae observed in the United States during the interval AD

  4. Solar Aurora and a White Light Flare

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard

    2016-07-01

    A white light flare analyzed by Krucker et al. (2011) poses a severe challenge to the solar physicist because of the high energy fluxes implied by a hitherto not achieved spatial resolution of simultaneous observations with Hinode and RHESSI. A scenario based on the auroral acceleration mechanism applied to flare conditions, 'Solar Aurora', is able to reproduce the observations, but implies several far-reaching assumptions on the mechanism as well as on the environmental parameters. Unavoidable consequences exist with regard to the spatial and temporal scales. They are extremely short because of the high density of the corona and the need for an energy conversion process involving some kind of anomalous resistivity, i.e. extremely high electric current densities. A further postulate is that of spontaneous propagation of an energy conversion front (ENF), once established, in three dimensions. It is assumed that about one half of the converted energy appears in form of runaway electrons. Obliqueness of the ENFs prevents the existence of a return current problem for the emerging runaway electrons. The key flare parameters are formulated quantitatively in terms of the environmental properties. Transverse length scales turn out to be in the ten centimeter range, time-scales in the range of one millisecond. The energy conversion occurs in 10E3 -10E4 ENFs just above the transition region in a background field of the order of 2000 G. Observational consequences are being discussed.

  5. Dancing Lights: Creating the Aurora Story

    NASA Astrophysics Data System (ADS)

    Wood, E. L.; Cobabe-Ammann, E. A.

    2009-12-01

    Science tells a story about our world, our existence, our history, and the larger environment our planet occupies. Bearing this in mind, we created a series of lessons for 3rd-5th grades using a cross-disciplinary approach to teaching about the aurora by incorporating stories, photos, movies, and geography into the science in order to paint a broad picture and answer the question, “why do we care?” The fundamental backbone of the program is literacy. Students write and illustrate fiction and non-fiction work, poetry, and brochures that solidify both language arts skills and science content. In a time when elementary teachers relegate science to less than one hour per week, we have developed a novel science program that can be easily integrated with other topics during the typical school day to increase the amount of science taught in a school year. We are inspiring students to take an interest in the natural world with this program, a stepping-stone for larger things.

  6. Solar wind influence on Jupiter's aurora

    NASA Astrophysics Data System (ADS)

    Gyalay, Szilard; Vogt, Marissa F.; Withers, Paul; Bunce, Emma J.

    2016-10-01

    Jupiter's main auroral emission is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma and is not due to the magnetosphere-solar wind interaction like at Earth. The solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora compared to the influence of rotational stresses due to the planet's rapid rotation. However, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter we have identified intervals of high and low solar wind dynamic pressure in the Galileo dataset, and use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration. We have developed separate spatial fits to the compressed and nominal magnetic field data, accounting for variations with radial distance and local time. These two fits can be used to update the flux equivalence mapping model of Vogt et al. (2011), which links auroral features to source regions in the middle and outer magnetosphere. The updated version accounts for changing solar wind conditions and provides a way to quantify the expected solar wind-induced variability in the ionospheric mapping of the main auroral emission, satellite footprints, and other auroral features. Our results are highly relevant to interpretation of the new auroral observations from the Juno mission.

  7. Skp2 is required for Aurora B activation in cell mitosis and spindle checkpoint.

    PubMed

    Wu, Juan; Huang, Yu-Fan; Zhou, Xin-Ke; Zhang, Wei; Lian, Yi-Fan; Lv, Xiao-Bin; Gao, Xiu-Rong; Lin, Hui-Kuan; Zeng, Yi-Xin; Huang, Jian-Qing

    2015-01-01

    The Aurora B kinase plays a critical role in cell mitosis and spindle checkpoint. Here, we showed that the ubiquitin E3-ligase protein Skp2, also as a cell-cycle regulatory protein, was required for the activation of Aurora B and its downstream protein. When we restored Skp2 knockdown Hela cells with Skp2 and Skp2-LRR E3 ligase dead mutant we found that Skp2 could rescue the defect in the activation of Aurora B, but the mutant failed to do so. Furthermore, we discovered that Skp2 could interact with Aurora B and trigger Aurora B Lysine (K) 63-linked ubiquitination. Finally, we demonstrated the essential role of Skp2 in cell mitosis progression and spindle checkpoint, which was Aurora B dependent. Our results identified a novel ubiquitinated substrate of Skp2, and also indicated that Aurora B ubiquitination might serve as an important event for Aurora B activation in cell mitosis and spindle checkpoint.

  8. Aurora A drives early signalling and vesicle dynamics during T-cell activation.

    PubMed

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Pérez de Castro, Ignacio; de Cárcer, Guillermo; Borroto, Aldo; Camafeita, Emilio; Jorge, Inmaculada; Vázquez, Jesús; Alarcón, Balbino; Malumbres, Marcos; Martín-Cófreces, Noa B; Sánchez-Madrid, Francisco

    2016-04-19

    Aurora A is a serine/threonine kinase that contributes to the progression of mitosis by inducing microtubule nucleation. Here we have identified an unexpected role for Aurora A kinase in antigen-driven T-cell activation. We find that Aurora A is phosphorylated at the immunological synapse (IS) during TCR-driven cell contact. Inhibition of Aurora A with pharmacological agents or genetic deletion in human or mouse T cells severely disrupts the dynamics of microtubules and CD3ζ-bearing vesicles at the IS. The absence of Aurora A activity also impairs the activation of early signalling molecules downstream of the TCR and the expression of IL-2, CD25 and CD69. Aurora A inhibition causes delocalized clustering of Lck at the IS and decreases phosphorylation levels of tyrosine kinase Lck, thus indicating Aurora A is required for maintaining Lck active. These findings implicate Aurora A in the propagation of the TCR activation signal.

  9. Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy of an undated lithograph based on an ambrotype by D.C. Pratt, C. 1857 - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

  10. Aurora A drives early signalling and vesicle dynamics during T-cell activation

    PubMed Central

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Pérez de Castro, Ignacio; de Cárcer, Guillermo; Borroto, Aldo; Camafeita, Emilio; Jorge, Inmaculada; Vázquez, Jesús; Alarcón, Balbino; Malumbres, Marcos; Martín-Cófreces, Noa B.; Sánchez-Madrid, Francisco

    2016-01-01

    Aurora A is a serine/threonine kinase that contributes to the progression of mitosis by inducing microtubule nucleation. Here we have identified an unexpected role for Aurora A kinase in antigen-driven T-cell activation. We find that Aurora A is phosphorylated at the immunological synapse (IS) during TCR-driven cell contact. Inhibition of Aurora A with pharmacological agents or genetic deletion in human or mouse T cells severely disrupts the dynamics of microtubules and CD3ζ-bearing vesicles at the IS. The absence of Aurora A activity also impairs the activation of early signalling molecules downstream of the TCR and the expression of IL-2, CD25 and CD69. Aurora A inhibition causes delocalized clustering of Lck at the IS and decreases phosphorylation levels of tyrosine kinase Lck, thus indicating Aurora A is required for maintaining Lck active. These findings implicate Aurora A in the propagation of the TCR activation signal. PMID:27091106

  11. 77 FR 13694 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel AURORA B; Invitation for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Requested Administrative Waiver of the Coastwise Trade Laws: Vessel AURORA B... the vessel AURORA B is: Intended Commercial Use of Vessel: ``Will provide special chartering...

  12. 77 FR 43703 - Honoring the Victims of the Tragedy in Aurora, Colorado

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-25

    ... Documents#0;#0; ] Proclamation 8842 of July 20, 2012 Honoring the Victims of the Tragedy in Aurora, Colorado... of the senseless acts of violence perpetrated on July 20, 2012, in Aurora, Colorado, by the...

  13. Prediction of blue, red and green aurorae at Mars

    NASA Astrophysics Data System (ADS)

    Lilensten, J.; Bernard, D.; Barthélémy, M.; Gronoff, G.; Simon Wedlund, C.; Opitz, A.

    2015-09-01

    The upper atmosphere of Mars is a laboratory for better understanding the planetary atmosphere evolution, and is an example of the interaction of the solar wind with an unmagnetized planet that has only patches of crustal magnetic field. In that context, several space missions were launched to study the Martian environment and its aurorae, notably ESA's Mars Express discovered the first aurora-like structures, and more recently NASA's MAVEN, which is dedicated to understand the atmospheric escape. However, none of the existing missions have spectrometers in the visible spectral range for the observation of the upper atmosphere and the aurorae, but there are UV spectrometer which can be used to infer visible aurora emission. The UV aurorae on Mars have a counterpart in the visible spectral range which should be detectable under the right conditions. We discuss what are the most favorable conditions to observe these aurorae discernible with the naked eye. In this paper, we simulate the Martian aurora in the visible spectral range both with an experimental setup (the Planeterrella, which we use to measure intensity with respect to the naked eye) and with a numerical ionosphere simulation model (Trans*/Aeroplanets). We show that the electron impact on CO2 produces strong emissions at 412 nm and 434 nm, i.e., in the blue part of the visible spectrum which are due to the CO2+(A) Fox-Duffendack-Barker bands. The modeling of the electron transport at Mars shows that these blue emissions as well as the emissions of the 630 nm (red) and 557.7 nm (green) lines of atomic oxygen may be observable several times during a solar cycle during strong solar events. The absence of visible spectrometers dedicated to these observations onboard existing space missions and the location of the different Martian rovers, far from the vertically aligned crustal magnetic field lines of Mars, have prevented so far the observations of such an aurora. In the foreseeable future, two missions may

  14. Aurora Kinases and Potential Medical Applications of Aurora Kinase Inhibitors: A Review

    PubMed Central

    Gavriilidis, Paschalis; Giakoustidis, Alexandros; Giakoustidis, Dimitrios

    2015-01-01

    Aurora kinases (AKs) represent a novel group of serine/threonine kinases. They were originally described in 1995 by David Glover in the course of studies of mutant alleles characterized with unusual spindle pole configuration in Drosophila melanogaster. Thus far, three AKs A, B, and C have been discovered in human healthy and neoplastic cells. Each one locates in different subcellular locations and they are all nuclear proteins. AKs are playing an essential role in mitotic events such as monitoring of the mitotic checkpoint, creation of bipolar mitotic spindle and alignment of centrosomes on it, also regulating centrosome separation, bio-orientation of chromosomes and cytokinesis. Any inactivation of them can have catastrophic consequences on mitotic events of spindle formation, alignment of centrosomes and cytokinesis, resulting in apoptosis. Overexpression of AKs has been detected in diverse solid and hematological cancers and has been linked with a dismal prognosis. After discovery and identification of the first aurora kinase inhibitor (AKI) ZM447439 as a potential drug for targeted therapy in cancer treatment, approximately 30 AKIs have been introduced in cancer treatment. PMID:26345296

  15. A Cell Biologist’s Field Guide to Aurora Kinase Inhibitors

    PubMed Central

    de Groot, Christian O.; Hsia, Judy E.; Anzola, John V.; Motamedi, Amir; Yoon, Michelle; Wong, Yao Liang; Jenkins, David; Lee, Hyun J.; Martinez, Mallory B.; Davis, Robert L.; Gahman, Timothy C.; Desai, Arshad; Shiau, Andrew K.

    2015-01-01

    Aurora kinases are essential for cell division and are frequently misregulated in human cancers. Based on their potential as cancer therapeutics, a plethora of small molecule Aurora kinase inhibitors have been developed, with a subset having been adopted as tools in cell biology. Here, we fill a gap in the characterization of Aurora kinase inhibitors by using biochemical and cell-based assays to systematically profile a panel of 10 commercially available compounds with reported selectivity for Aurora A (MLN8054, MLN8237, MK-5108, MK-8745, Genentech Aurora Inhibitor 1), Aurora B (Hesperadin, ZM447439, AZD1152-HQPA, GSK1070916), or Aurora A/B (VX-680). We quantify the in vitro effect of each inhibitor on the activity of Aurora A alone, as well as Aurora A and Aurora B bound to fragments of their activators, TPX2 and INCENP, respectively. We also report kinome profiling results for a subset of these compounds to highlight potential off-target effects. In a cellular context, we demonstrate that immunofluorescence-based detection of LATS2 and histone H3 phospho-epitopes provides a facile and reliable means to assess potency and specificity of Aurora A versus Aurora B inhibition, and that G2 duration measured in a live imaging assay is a specific readout of Aurora A activity. Our analysis also highlights variation between HeLa, U2OS, and hTERT-RPE1 cells that impacts selective Aurora A inhibition. For Aurora B, all four tested compounds exhibit excellent selectivity and do not significantly inhibit Aurora A at effective doses. For Aurora A, MK-5108 and MK-8745 are significantly more selective than the commonly used inhibitors MLN8054 and MLN8237. A crystal structure of an Aurora A/MK-5108 complex that we determined suggests the chemical basis for this higher specificity. Taken together, our quantitative biochemical and cell-based analyses indicate that AZD1152-HQPA and MK-8745 are the best current tools for selectively inhibiting Aurora B and Aurora A, respectively

  16. Aurora kinase inhibitors--rising stars in cancer therapeutics?

    PubMed

    Dar, Altaf A; Goff, Laura W; Majid, Shahana; Berlin, Jordan; El-Rifai, Wael

    2010-02-01

    Standard therapeutic approaches of cytotoxics and radiation in cancer are not only highly toxic, but also of limited efficacy in treatment of a significant number of cancer patients. The molecular analysis of the cancer genomes have shown a remarkable complexity and pointed to key genomic and epigenomic alterations in cancer. These discoveries are paving the way for targeted therapy approaches. However, although there are a large number of potential targets, only a few can regulate key cellular functions and intersect multiple signaling networks. The Aurora kinase family members (A, B, and C) are a collection of highly related and conserved serine-threonine kinases that fulfill these criteria, being key regulators of mitosis and multiple signaling pathways. Alterations in Aurora kinase signaling are associated with mitotic errors and have been closely linked to chromosomal aneuploidy in cancer cells. Several studies have shown amplification and/or overexpression of Aurora kinase A and B in hematologic malignancies and solid tumors. Over the past several years, Aurora kinases have become attractive targets. Several ongoing clinical trials and bench-based research are assessing the unique therapeutic potential of Aurora-based targeted therapy.

  17. Aurora Borealis, A Painting by Frederic Edwin Church

    NASA Astrophysics Data System (ADS)

    Love, J. J.

    2015-12-01

    This year marks the sesquicentennial anniversary of the end of the American Civil War. In 1865, the same year as the War's end, the great American landscape artist, Frederic Edwin Church, unveiled Aurora Borealis, a painting that depicts a fantastic, far-northern place, an auroral arch stretched across a quiet night-time sky, above dark mountains and a frozen sea. Church was born in Connecticut, lived in New York, and traveled to Labrador; he would have often seen the northern lights. Church might have also been influenced by the spectacular displays of aurora that were caused by some unusually intense magnetic storms in 1859. Aurora Borealis can certainly be interpreted in terms of 19th-century romanticism, scientific philosophy, and Arctic missions of exploration, all subjects of interest to Church. As with so many of his paintings, Church's meticulous attention to detail in Aurora Borealis reveals his deep admiration of nature. But his depiction of auroral light is a curious and possibly intentional departure from natural verisimilitude. Some art historians have suggested that Church painted Aurora Borealis as a subdued tribute to the end of the Civil War, with the drapery of auroral light forming an abstract representation of the American flag. If so, then colors of the flag have been unfurled across a cold and barren landscape, not in extravagant celebration, but in somber recognition of the reality of post-war desolation and an uncertain future.

  18. Preclinical validation of Aurora kinases-targeting drugs in osteosarcoma

    PubMed Central

    Tavanti, E; Sero, V; Vella, S; Fanelli, M; Michelacci, F; Landuzzi, L; Magagnoli, G; Versteeg, R; Picci, P; Hattinger, C M; Serra, M

    2013-01-01

    Background: Aurora kinases are key regulators of cell cycle and represent new promising therapeutic targets in several human tumours. Methods: Biological relevance of Aurora kinase-A and -B was assessed on osteosarcoma clinical samples and by silencing these genes with specific siRNA in three human osteosarcoma cell lines. In vitro efficacy of two Aurora kinases-targeting drugs (VX-680 and ZM447439) was evaluated on a panel of four drug-sensitive and six drug-resistant human osteosarcoma cell lines. Results: Human osteosarcoma cell lines proved to be highly sensitive to both drugs. A decreased drug sensitivity was observed in doxorubicin-resistant cell lines, most probably related to ABCB1/MDR1 overexpression. Both drugs variably induced hyperploidy and apoptosis in the majority of cell lines. VX-680 also reduced in vitro cell motility and soft-agar cloning efficiency. Drug association experiments showed that VX-680 positively interacts with all conventional drugs used in osteosarcoma chemotherapy, overcoming the cross-resistance observed in the single-drug treatments. Conclusion: Aurora kinase-A and -B represent new candidate therapeutic targets for osteosarcoma. In vitro analysis of the Aurora kinases inhibitors VX-680 and ZM447439 indicated in VX-680 a new promising drug of potential clinical usefulness in association with conventional osteosarcoma chemotherapeutic agents. PMID:24129234

  19. Fast DPCM scheme for lossless compression of aurora spectral images

    NASA Astrophysics Data System (ADS)

    Kong, Wanqiu; Wu, Jiaji

    2016-10-01

    Aurora has abundant information to be stored. Aurora spectral image electronically preserves spectral information and visual observation of aurora during a period to be studied later. These images are helpful for the research of earth-solar activities and to understand the aurora phenomenon itself. However, the images are produced with a quite high sampling frequency, which leads to the challenging transmission load. In order to solve the problem, lossless compression turns out to be required. Indeed, each frame of aurora spectral images differs from the classical natural image and also from the frame of hyperspectral image. Existing lossless compression algorithms are not quite applicable. On the other hand, the key of compression is to decorrelate between pixels. We consider exploiting a DPCM-based scheme for the lossless compression because DPCM is effective for decorrelation. Such scheme makes use of two-dimensional redundancy both in the spatial and spectral domain with a relatively low complexity. Besides, we also parallel it for a faster computation speed. All codes are implemented on a structure consists of nested for loops of which the outer and the inner loops are respectively designed for spectral and spatial decorrelation. And the parallel version is represented on CPU platform using different numbers of cores. Experimental results show that compared to traditional lossless compression methods, the DPCM scheme has great advantage in compression gain and meets the requirement of real-time transmission. Besides, the parallel version has expected computation performance with a high CPU utilization.

  20. Identification of Ski as a target for Aurora A kinase

    PubMed Central

    Mosquera, Jocelyn; Armisen, Ricardo; Zhao, Hong Ling; Rojas, Diego A.; Maldonado, Edio; Tapia, Julio C; Colombo, Alicia; Hayman, Michael J; Marcelain, Katherine

    2011-01-01

    Ski is a negative regulator of the transforming growth factor-β and other signalling pathways. The absence of SKI in mouse fibroblasts leads to chromosome segregation defects and genomic instability, suggesting a role for Ski during mitosis. At this stage, Ski is phosphorylated but to date little is known about the kinases involved in this process. Here, we show that Aurora A kinase is able to phosphorylate Ski in vitro. In vivo, Aurora A and Ski co-localized at the centrosomes and co-immunoprecipitated. Conversely, a C-terminal truncation mutant of Ski (SkiΔ491–728) lacking a coiled-coil domain, displayed decreased centrosomal localization. This mutant no longer co-immunoprecipitated with Aurora-A in vivo, but was still phosphorylated in vitro, indicating that the Ski-Aurora A interaction takes place at the centrosomes. These data identify Ski as a novel target of Aurora A and contribute to an understanding of the role of these proteins in the mitotic process. PMID:21600873

  1. AURORA: The Next Generation Space Weather Sensor for NPOESS

    NASA Astrophysics Data System (ADS)

    Paxton, L.; Morrison, D.; Santo, A.; Ogorzalek, B.; Goldsten, J.; Boldt, J.; Kil, H.; Zhang, Y.; Demajistre, R.; Wolven, B.; Meng, C.

    2005-12-01

    The AURORA sensor slated for flight on the NPOESS satellites represents the culmination of over 20 years of experience at JHU/APL in the design, manufacture, flight, operation and analysis of compact, cost-effective far ultraviolet sensors for space weather data collection. The far ultraviolet covers the spectral range from about 115 to 185 nm. This region is ideal for observations of the upper atmosphere because, at these wavelengths, the lower atmosphere and Earth's surface are black. AURORA will observe the mid- and low-latitude F-region ionosphere, the auroral E-region ionosphere, the day thermosphere composition, auroral energy deposition and map ionospheric irregularities. AURORA implements the flight-proven design derived from SSUSI on the DMSP Block 5D spacecraft and GUVI on the NASA TIMED spacecraft. These instruments have provided the instrument and algorithm heritage for NPOESS/AURORA. In this talk the performance capabilities of the AURORA instrument will be summarized along with the design of the instrument and algorithms. Example products will be shown for each of the measurement regimes. We acknowldge support from DMSP and NASA and the collaboration with our science colleagues at the Aerospace Corporation (Paul Straus, Jim Hecht, Dave McKenzie, and Andy Christensen) and Computational Physics (Doug Strickland, Hal Knight, and Scott Evans) and Naval Research Laboratory (Robert Meier, Mike Picone, Stefan Thonnard, Pat Dandenault, and Andy Stefan) and our colleagues at APL (Michele Weiss, Doug Holland, Bill Wood, and Jim Eichert) among others.

  2. Aurora B Interaction of Centrosomal Nlp Regulates Cytokinesis*

    PubMed Central

    Yan, Jie; Jin, Shunqian; Li, Jia; Zhan, Qimin

    2010-01-01

    Cytokinesis is a fundamental cellular process, which ensures equal abscission and fosters diploid progenies. Aberrant cytokinesis may result in genomic instability and cell transformation. However, the underlying regulatory machinery of cytokinesis is largely undefined. Here, we demonstrate that Nlp (Ninein-like protein), a recently identified BRCA1-associated centrosomal protein that is required for centrosomes maturation at interphase and spindle formation in mitosis, also contributes to the accomplishment of cytokinesis. Through immunofluorescent analysis, Nlp is found to localize at midbody during cytokinesis. Depletion of endogenous Nlp triggers aborted division and subsequently leads to multinucleated phenotypes. Nlp can be recruited by Aurora B to the midbody apparatus via their physical association at the late stage of mitosis. Disruption of their interaction induces aborted cytokinesis. Importantly, Nlp is characterized as a novel substrate of Aurora B and can be phosphorylated by Aurora B. The specific phosphorylation sites are mapped at Ser-185, Ser-448, and Ser-585. The phosphorylation at Ser-448 and Ser-585 is likely required for Nlp association with Aurora B and localization at midbody. Meanwhile, the phosphorylation at Ser-185 is vital to Nlp protein stability. Disruptions of these phosphorylation sites abolish cytokinesis and lead to chromosomal instability. Collectively, these observations demonstrate that regulation of Nlp by Aurora B is critical for the completion of cytokinesis, providing novel insights into understanding the machinery of cell cycle progression. PMID:20864540

  3. Identification of Ski as a target for Aurora A kinase.

    PubMed

    Mosquera, Jocelyn; Armisen, Ricardo; Zhao, Hongling; Rojas, Diego A; Maldonado, Edio; Tapia, Julio C; Colombo, Alicia; Hayman, Michael J; Marcelain, Katherine

    2011-06-10

    Ski is a negative regulator of the transforming growth factor-β and other signalling pathways. The absence of SKI in mouse fibroblasts leads to chromosome segregation defects and genomic instability, suggesting a role for Ski during mitosis. At this stage, Ski is phosphorylated but to date little is known about the kinases involved in this process. Here, we show that Aurora A kinase is able to phosphorylate Ski in vitro. In vivo, Aurora A and Ski co-localized at the centrosomes and co-immunoprecipitated. Conversely, a C-terminal truncation mutant of Ski (SkiΔ491-728) lacking a coiled-coil domain, displayed decreased centrosomal localization. This mutant no longer co-immunoprecipitated with Aurora-A in vivo, but was still phosphorylated in vitro, indicating that the Ski-Aurora A interaction takes place at the centrosomes. These data identify Ski as a novel target of Aurora A and contribute to an understanding of the role of these proteins in the mitotic process.

  4. Solar Storm Triggers Whole-Planet Aurora at Mars (Video)

    NASA Image and Video Library

    2017-09-29

    This frame from an animation shows the sudden appearance of a bright aurora on Mars during a solar storm. The purple-white color scheme shows the intensity of ultraviolet light seen on Mars' night side over the course of the event. The data are from observations on Sept. 12 and 13, 2017, by the Imaging Ultraviolet Spectrograph instrument (IUVS) on NASA's Mars Atmosphere and Volatile Evolution orbiter, or MAVEN. The aurora is occurring because energetic particles from the solar storm are bombarding gases in the planet's atmosphere, causing them to glow. A simulated image of the Mars surface for the same time and orientation is also shown, with the dayside crescent visible on the right. The auroral emission appears brightest at the edges of the planet where the line of sight passes along the length of the glowing atmosphere layer. Note that, unlike auroras on Earth, the Martian aurora is not concentrated at the planet's polar regions. This is because Mars has no strong magnetic field like Earth's to concentrate the aurora near the poles. An animation is available at https://photojournal.jpl.nasa.gov/catalog/PIA21854

  5. Aurora B prevents premature removal of spindle assembly checkpoint proteins from the kinetochore: A key role for Aurora B in mitosis.

    PubMed

    Gurden, Mark D; Anderhub, Simon J; Faisal, Amir; Linardopoulos, Spiros

    2016-07-18

    Accurate chromosome segregation is dependent on the spindle assembly checkpoint (SAC). In current models, the key direct role of Aurora B in the SAC has been suggested to be to promote rapid kinetochore localisation of MPS1, allowing MPS1 to generate the checkpoint signal. However, Aurora B is also thought to play an indirect role in the SAC through the destabilisation of kinetochore-microtubule (KT-MT) attachments. Here, we demonstrate that Aurora B activity is not required for the kinetochore recruitment of the majority of SAC proteins. More importantly, we show that the primary role of Aurora B in the SAC is to prevent the premature removal of SAC proteins from the kinetochore, which is strictly dependent on KT-MT interactions. Moreover, in the presence of KT-MT interactions, Aurora B inhibition silences a persistent SAC induced by tethering MPS1 to the kinetochore. This explains the highly synergistic interaction between Aurora B and MPS1 inhibitors to override the SAC, which is lost when cells are pre-arrested in nocodazole. Furthermore, we show that Aurora B and MPS1 inhibitors synergistically kill a panel of breast and colon cancer cell lines, including cells that are otherwise insensitive to Aurora B inhibitors alone. These data demonstrate that the major role of Aurora B in SAC is to prevent the removal of SAC proteins from tensionless kinetochores, thus inhibiting premature SAC silencing, and highlights a therapeutic strategy through combination of Aurora B and MPS1 inhibitors.

  6. Issues in interpreting the in vivo activity of Aurora-A inhibitors

    PubMed Central

    Shagisultanova, Elena; Dunbrack, Roland L.; Golemis, Erica A.

    2014-01-01

    Introduction Based on its role as a mitotic regulatory kinase, overexpressed and associated with aneuploidy in cancer, small molecule inhibitors have been developed for Aurora-A (AURKA) kinase. In preclinical and clinical assessments, these agents have shown efficacy in inducing stable disease or therapeutic response. In optimizing the use of Aurora-A inhibitors, it is critical to have robust capacity to measure the kinase activity of Aurora-A in tumors. Areas covered we provide an overview of molecular mechanisms of mitotic and non-mitotic activation of Aurora-A kinase, and interaction of Aurora-A with its regulatory partners. Typically, Aurora-A activity is measured by use of phospho-antibodies targeting an auto-phosphorylated T288 epitope. However, recent studies have identified alternative means of Aurora-A activation control, including allosteric regulation by partners, phosphorylation on alternative activating residues (S51, S98), dephosphorylation on inhibitory sites (S342), and T288 phosphorylation by alternative kinases such as Pak enzymes. Additional work has shown that the relative abundance of Aurora-A partners can affect the activity of Aurora-A inhibitors, and that Aurora-A activation also occurs in interphase cells. Expert opinion Taken together, this work suggests the need for comprehensive analysis of Aurora-A activity and expression of Aurora-A partners in order to stratify patients for likely therapeutic response. PMID:25384454

  7. A mathematical model of Aurora B activity in prophase and metaphase.

    PubMed

    Doherty, Kevin; Meere, Martin; Piiroinen, Petri T

    2016-07-01

    Aurora B kinase is a protein that controls several processes in mitosis when it is found associated with INCENP, Survivin and Borealin in a complex known as the Chromosomal Passenger Complex. Aurora B in complex with INCENP is phosphorylated on three sites, resulting in the full activation of Aurora B. In prophase and metaphase, Aurora B is activated at centromeres, the region of chromatin linking sister chromatids, due to an autophosphorylation mechanism, and it has been hypothesised that Aurora B is activated throughout the cytoplasm due to its concentration at centromeres. In this article, we first develop a time-dependent model of Aurora B activation that does not incorporate spatial variation. This model is used to demonstrate the various qualitative behaviours that the activation of Aurora B is capable of displaying for different model parameters. Next, we develop a spatio-temporal model of Aurora B activation that includes diffusion of soluble Aurora B and binding of Aurora B to immobile centromeric binding sites. This model describes the activation of Aurora B throughout the cytoplasm due to its concentration-dependent activation at centromeres. The models demonstrate the effects that a soluble phosphatase concentration, multisite phosphorylation and diffusion have on the activation of Aurora B.

  8. Aurora kinase inhibitor patents and agents in clinical testing: an update (2011 - 2013).

    PubMed

    Cheung, Chun Hei Antonio; Sarvagalla, Sailu; Lee, Jane Ying-Chieh; Huang, Yi-Chun; Coumar, Mohane Selvaraj

    2014-09-01

    Aurora kinase A, B and C, members of serine/threonine kinase family, are key regulators of mitosis. As Aurora kinases are overexpressed in many of the human cancers, small-molecule inhibitors of Aurora kinase have emerged as a possible treatment option for cancer. In 2009 and 2011, the literature pertaining to Aurora kinase inhibitors and their patents was reviewed. Here, the aim is to update the information for Aurora kinase inhibitors in clinical trials and the patents filed between the years 2011 and 2013. Pubmed, Scopus®, Scifinder®, USPTO, EPO and www.clinicaltrials.gov databases were used for searching the literature and patents for Aurora kinase inhibitors. Even though both Aurora sub-type selective as well as pan-selective inhibitors show preclinical and clinical efficacy, so far no Aurora kinase inhibitor has been approved for clinical use. Particularly, dose-limiting toxicity (neutropenia) is a key issue that needs to be addressed. Preliminary evidence suggests that the use of selective Aurora A inhibitors could avoid Aurora B-mediated neutropenia in clinical settings. Also, use of adjunctive agents such as granulocyte stimulating factor to overcome neutropenia associated with Aurora B inhibition could be an answer to overcome the toxicity and bring Aurora inhibitors to market in the future.

  9. Aurora A, Aurora B and survivin are novel targets of transcriptional regulation by histone deacetylase inhibitors in non-small cell lung cancer.

    PubMed

    Zhang, Xu-Hui; Rao, Mahadev; Loprieato, Joseph A; Hong, Julie A; Zhao, Ming; Chen, Guo-Zhu; Humphries, Ashley E; Nguyen, Dao M; Trepel, Jane B; Yu, Xiaodan; Schrump, David S

    2008-09-01

    Analysis of biopsies from a recent clinical trial suggested that Depsipeptide FK228 (DP) inhibits Aurora kinase expression in lung cancer cells. The present study was undertaken to confirm and extend these observations. Aurora A and B mRNA levels in lung cancer cells were considerably higher than levels in normal pulmonary epithelia. DP, TSA and SAHA inhibited Aurora A, Aurora B and survivin expression with kinetics that were remarkably similar within individual cell lines, and appeared to coincide with p53 expression status. These effects were not observed following treatment with geldanamycins. Inhibition of Aurora B transcription coincided with decreased H3K9Ac and H3K4Me2 activation marks, and accumulation of H3K9Me3, as well as MBD1, MBD2 and MBD3 repression marks within the minimal Aurora B promoter. Knockdown of MBD1, -2 or -3 did not reproducibly abrogate inhibition of Aurora or survivin expression by DP or TSA. DP and TSA decreased expression and altered localization of Aurora kinases and survivin, resulting in mitotic catastrophe in lung cancer cells. Aurora A, and Aurora B levels in lung cancer cells and normal respiratory epithelia were assessed using quantitative RT-PCR techniques. These methods, as well as as Western blots were used to examine expression of Auroras A/B, and several related genes/proteins in lung cancer cells exposed to DP, TSA, SAHA and geldanamycins. Transient transfection promoter-reporter assays, and chromatin immunoprecipitation (ChIP) techniques were used to examine DP-mediated changes in activity and chromatin structure of the Aurora B promoter. Confocal imaging techniques were used to examine the effects of DP and TSA on mitotic progression in lung cancer cells. Novel transcriptional regulatory mechanisms involving Aurora kinase and survivin appear to contribute to cytotoxicity mediated by HDAC inhibitors in lung cancer cells.

  10. Io's atmospheric response to eclipse: UV aurorae observations.

    PubMed

    Retherford, K D; Spencer, J R; Stern, S A; Saur, J; Strobel, D F; Steffl, A J; Gladstone, G R; Weaver, H A; Cheng, A F; Parker, J Wm; Slater, D C; Versteeg, M H; Davis, M W; Bagenal, F; Throop, H B; Lopes, R M C; Reuter, D C; Lunsford, A; Conard, S J; Young, L A; Moore, J M

    2007-10-12

    The New Horizons (NH) spacecraft observed Io's aurora in eclipse on four occasions during spring 2007. NH Alice ultraviolet spectroscopy and concurrent Hubble Space Telescope ultraviolet imaging in eclipse investigate the relative contribution of volcanoes to Io's atmosphere and its interaction with Jupiter's magnetosphere. Auroral brightness and morphology variations after eclipse ingress and egress reveal changes in the relative contribution of sublimation and volcanic sources to the atmosphere. Brightnesses viewed at different geometries are best explained by a dramatic difference between the dayside and nightside atmospheric density. Far-ultraviolet aurora morphology reveals the influence of plumes on Io's electrodynamic interaction with Jupiter's magnetosphere. Comparisons to detailed simulations of Io's aurora indicate that volcanoes supply 1 to 3% of the dayside atmosphere.

  11. Aurora Borealis Experiment (ABX): A Planeterrella for Education and Outreach

    NASA Astrophysics Data System (ADS)

    McNulty, Michael; Carpe, Andy; Zwicker, Andrew

    2013-10-01

    The Planeterrella is an experiment invented by Jean Lilensten of the Laboratoire de Planetologie de Grenoble in France designed to simulate aurorae of various planets. It is done by placing two differently sized aluminum spheres in a bell jar with a pressure of approximately 75 mTorr. Each sphere has magnets inside and is electrically biased. An electrode with the opposite electrical bias is inserted into the bell jar so that the voltage between them is on the order of 300 V. A plasma is then created and an aurora is formed around the magnetic poles of the spheres or near the edge of the electrode. We have made a modified version of the planeterrella, called the Aurora Borealis Experiment (ABX), based upon Lilensten's plans. We will present the technical details of the experiment and preliminary results of its use with a variety of different audiences.

  12. Simulation of Sub Aurora Polarization Stream in the storm time

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Guo, J.; Deng, Y.; Sheng, C.; Lin, C. Y. T.

    2016-12-01

    Ion velocity in the dusk Sub Aurora region observed by Satellites often shows a significant westward convetion (up to 1000- 2000km/s). The high speed westward stream is distinguished with the two-cell convection pattern. This kind of events are called Sub Aurora Polarization Stream (SAPS). In March 17th 2013 storm, DMSP F18 satellite observed several SAPS cases when crossing the Sub Aurora region. The real particle precipitation data and electric field data from DMSP F18 satellite have been applied to drive the Global Ionosphere Thermosphere Model (GITM) along the satellite trajectory. Cases with different specifications of forcing have been compared to illustrate the influence SAPS on the ionosphere/thermosphere.

  13. Applications to particle transport in the Earth`s aurora

    SciTech Connect

    Jasperse, J.R.

    1994-12-31

    The visual display of light called the aurora borealis occurs when energetic (1 to 100-keV) electrons, protons, and hydrogen atoms from the Earth`s magnetosphere enter the Earth`s upper atmosphere and collide with the ambient neutral particles. Two kinds of auroras occur in nature: those excited by incident electrons and those excited by incident protons and hydrogen atoms. In this paper, we consider only the latter. The proton-hydrogen aurora may be divided into two altitude regions: high altitudes ({approximately}250 to {approximately}600 km) where charge-changing collisions dominate and energy-loss collisions may be neglected and low altitudes ({approximately}100 to {approximately}250 km) where energy-loss collisions also become important and cause rapid energy degradation. The focus of this review is on the high-altitude region where the one-group approximation is valid.

  14. Combined Cancer Immunotherapy Against Aurora Kinase A.

    PubMed

    Kaštánková, Iva; Poláková, Ingrid; Dušková, Martina; Šmahel, Michal

    2016-05-01

    Aurora kinase A (AURKA) is a centrosomal protein that is overexpressed in a number of human malignancies and can contribute to tumor progression. As we used this protein as a target of DNA immunization, we increased its immunogenicity by the addition of the PADRE helper epitope and decreased its potential oncogenicity by mutagenesis of the kinase domain. For in vitro analysis of induced immune responses in mice, we identified the Aurka(220-228) nonapeptide representing an H-2Kb epitope. As DNA vaccination against the Aurka self-antigen by a gene gun did not show any antitumor effect, we combined DNA immunization with anti-CD25 treatment that depletes mainly regulatory T cells. Whereas 1 anti-CD25 dose injected before DNA vaccination did not enhance the activation of Aurka-specific splenocytes, 3 doses administered on days of immunizations augmented about 10-fold immunity against Aurka. However, an opposite effect was found for antitumor immunity-only 1 anti-CD25 dose combined with DNA vaccination reduced tumor growth. Moreover, the administration of 3 doses of anti-CD25 antibody alone accelerated tumor growth. Analysis of tumor-infiltrating cells showed that 3 anti-CD25 doses not only efficiently depleted regulatory T cells but also activated helper T cells and CD3(-)CD25(+) cells. Next, we found that blockade of the PD-1 receptor initiated 1 week after the first immunization was necessary for significant inhibition of tumor growth with therapeutic DNA vaccination against Aurka combined with depletion of CD25 cells. Our results suggest that combined cancer immunotherapy should be carefully evaluated to achieve the optimal antitumor effect.

  15. The Aurora and Magnetic Field of Uranus

    NASA Astrophysics Data System (ADS)

    Herbert, F.

    2008-12-01

    Resolution of the details of a planetary magnetic field from magnetometer measurements made during a single flyby can be limited by the incomplete geometrical sampling of the trajectory. This problem was especially severe for the only spacecraft visit to Uranus, that of Voyager 2 in 1986. Fortunately, auroral footprints serve as additional constraints that may be used to determine the higher multipole moments of the planetary field. This approach has been used by Connerney (JGR 103:11,929, 1998) to improve the magnetic field model of Jupiter. In the present work, this approach is applied to improving the resolution of the magnetic field of Uranus. The earlier determination of Uranus' auroral emission distribution (Herbert JGR 99:4143, 1994) from scans by the Voyager 2 Ultraviolet Spectrometer (UVS) has been improved by incorporating more observations and using more powerful analysis techniques. However, the resulting new estimate of the locus of the auroral oval does not match the expectations derived from the Voyager magnetometer (Connerney et al., JGR 92:15,329, 1987, Q3 model). Accordingly, a search has been initiated for planetary magnetic field model coefficients that agree both with the new auroral locus and also with the magnetic field observations. This search is more ambiguous than that at Jupiter, because the source of the aurora is not clearly defined, but a reasonable starting assumption is that it lies at constant L shell (maximum field-line distance from Uranus). Based on this assumption, preliminary results confirm the Q3 model quadrupole moment's large magnitude but disagree slightly with its orientation. Further analysis will be presented at the meeting. Support from the NASA Outer Planets Program made this work possible, and is gratefully acknowledged. Part of this work was done while a guest investigator at l'Institut d'Astrophysique de Paris (IAP/CNRS), whose hospitality is appreciated.

  16. Nonlinear Plasma Effects in Natural and Artificial Aurora

    SciTech Connect

    Mishin, E. V.

    2011-01-04

    This report describes common features of natural ('Enhanced') aurora and 'artificial aurora'(AA) created by electron beams injected from sounding rockets. These features cannot be explained solely by col-lisional degradation of energetic electrons, thereby pointing to collisionless plasma effects. The fundamental role in electron beam-ionosphere interactions belongs to Langmuir turbulence. Its development in the (weakly-ionized) ionosphere is significantly affected by electron-neutral collisions, so that the heating and acceleration of plasma electrons proceed more efficiently than in collisionless plasmas. As a result, a narrow layer of enhanced auroral glow/ionization is formed above the standard collisional peak.

  17. Aurora painting pays tribute to Civil War's end

    USGS Publications Warehouse

    Love, Jeffrey J.

    2015-01-01

    In 1865, the same year the war ended, the American landscape artist Frederic Edwin Church unveiledAurora Borealis (pictured above), a dramatic and mysterious painting that can be interpreted in terms of 19th century romanticism, scientific philosophy, and Arctic missions of exploration. Aurora Borealiscan also be viewed as a restrained tribute to the end of the Civil War—a moving example of how science and current events served as the muses of late romantic artists [e.g., Carr, 1994, p. 277; Avery, 2011; Harvey, 2012].

  18. Artificial aurora conjugate to a rocket-borne electron accelerator

    NASA Technical Reports Server (NTRS)

    Davis, T. N.; Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Hess, W. N.; Trichel, M. C.; Maier, E. J. R.

    1980-01-01

    An accelerator intended to send electron beams upward along an L = 1.24 magnetic field line was flown from a rocket launched from Kauai, Hawaii, on October 15, 1972. Though the intent was to produce several hundred observable auroral streaks in the Southern Hemisphere, imaging instruments operated there aboard jet aircraft detected only a single aurora. Produced by a 0.155-A beam of energy 22.8 keV, the aurora was of expected brightness and had a diameter (210 + or - 50 m) somewhat larger than expected and an altitude (top 116 + or - 2 km; bottom 92 + or - 2 km) higher than expected.

  19. Expression of aurora kinases: Predictor of tumor dissemination in uterine carcinosarcoma.

    PubMed

    Han, Kyung Hee; Kim, Min A; Park, Noh Hyun

    2016-10-25

    Uterine carcinosarcoma is a rare, aggressive, and biphasic tumor. It comprises carcinomatous and sarcomatous components, and mitosis-associated factors are thought to discriminate these two lesions. Aurora kinases are mitotic enzymes that are highly expressed in uterine malignancies. To identify the clinical significance of aurora kinase expression, we performed immunohistochemistry on tissue microarrays using cores selected from areas with typical carcinomatous and sarcomatous characteristics. A total of 24 samples were included, from patients at Seoul National University Hospital diagnosed with uterine carcinosarcoma, and who undergone a staging operation between 1997 and 2012. Patients' clinical and pathological data were analyzed, and expression patterns of aurora kinases were investigated. Aurora kinases A and B were dominantly expressed in the cytoplasm, and phospho-aurora kinases A and B were expressed in the nuclei. Phospho-aurora kinase A and aurora kinase B showed significantly higher expression in the carcinomatous component (P=0.012 and 0.008). High expression of phospho-aurora kinase A was associated with lymphatic metastasis such as positive pelvic lymph node and omental involvement (P=0.012 and 0.037). Overexpression of aurora kinase B was related to vascular invasion (P=0.011). High expression of both phospho-aurora kinase A and aurora kinase B was a prognostic factor for progression-free survival in uterine carcinosarcoma (P=0.049). In conclusion, expression of aurora kinases is associated with bidirectional tumor dissemination into the lymphatic and hematogenous pathways. In addition, high expression of phospho-aurora kinase A and aurora kinase B is a predictor of progression-free survival. Therefore, inhibitors of aurora kinases might be a prospective therapeutic options for uterine carcinosarcoma.

  20. Chandra Probes High-Voltage Auroras on Jupiter

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Scientists have obtained new insight into the unique power source for many of Jupiter's auroras, the most spectacular and active auroras in the Solar System. Extended monitoring of the giant planet with NASA's Chandra X-ray Observatory detected the presence of highly charged particles crashing into the atmosphere above its poles. X-ray spectra measured by Chandra showed that the auroral activity was produced by ions of oxygen and other elements that were stripped of most of their electrons. This implies that these particles were accelerated to high energies in a multimillion-volt environment above the planet's poles. The presence of these energetic ions indicates that the cause of many of Jupiter's auroras is different from auroras produced on Earth or Saturn. Chandra X-ray Image of Jupiter Chandra X-ray Image of Jupiter "Spacecraft have not explored the region above the poles of Jupiter, so X-ray observations provide one of the few ways to probe that environment," said Ron Elsner of the NASA Marshall Space Flight Center in Huntsville, Alabama, and lead author on a recently published paper describing these results in the Journal for Geophysical Research. "These results will help scientists to understand the mechanism for the power output from Jupiter's auroras, which are a thousand times more powerful than those on Earth." Electric voltages of about 10 million volts, and currents of 10 million amps - a hundred times greater than the most powerful lightning bolts - are required to explain the X-ray observations. These voltages would also explain the radio emission from energetic electrons observed near Jupiter by the Ulysses spacecraft. Schematic of Jupiter's Auroral Activity Production Schematic of Jupiter's Auroral Activity Production On Earth, auroras are triggered by solar storms of energetic particles, which disturb Earth's magnetic field. Gusts of particles from the Sun can also produce auroras on Jupiter, but unlike Earth, Jupiter has another way of producing

  1. Aurora-A promotes the establishment of spindle assembly checkpoint by priming the Haspin-Aurora-B feedback loop in late G2 phase.

    PubMed

    Yu, Fazhi; Jiang, Ya; Lu, Lucy; Cao, Mimi; Qiao, Yulong; Liu, Xing; Liu, Dan; Van Dyke, Terry; Wang, Fangwei; Yao, Xuebiao; Guo, Jing; Yang, Zhenye

    2017-01-01

    Aurora-A kinase functions mainly in centrosome maturation, separation and spindle formation. It has also been found to be amplified or overexpressed in a range of solid tumors, which is linked with tumor progression and poor prognosis. Importantly, Aurora-A inhibitors are being studied in a number of ongoing clinical trials. However, whether and how Aurora-A has a role in the regulation of the mitotic checkpoint is controversial. Additionally, the function of nuclear-accumulated Aurora-A in late G2 phase is not clear. Here we show that knockout, inhibition or blockade of the nuclear entry of Aurora-A severely decreased the centromere localization of Aurora-B and the phosphorylation of histone H3 threonine 3 (H3T3-ph) mediated by the kinase Haspin in late G2 phase. We further reveal that nuclear-accumulated Aurora-A phosphorylates Haspin at multiple sites at its N-terminus and that this promotes H3T3-ph and the rapid recruitment to the centromere of the chromosomal passenger complex. In addition, Aurora-A facilitates the association of Aurora-B with their common substrates: Haspin and Plk1. Notably, these functions of Aurora-A are mostly independent of Plk1. Thus we demonstrate that, in late G2 and prophase, Aurora-A phosphorylates Haspin to trigger the Haspin-H3T3-ph-Aurora-B positive feedback loop that supports the timely establishment of the chromosomal passenger complex and the mitotic checkpoint before spindle assembly.

  2. Aurora-A promotes the establishment of spindle assembly checkpoint by priming the Haspin-Aurora-B feedback loop in late G2 phase

    PubMed Central

    Yu, Fazhi; Jiang, Ya; Lu, Lucy; Cao, Mimi; Qiao, Yulong; Liu, Xing; Liu, Dan; Van Dyke, Terry; Wang, Fangwei; Yao, Xuebiao; Guo, Jing; Yang, Zhenye

    2017-01-01

    Aurora-A kinase functions mainly in centrosome maturation, separation and spindle formation. It has also been found to be amplified or overexpressed in a range of solid tumors, which is linked with tumor progression and poor prognosis. Importantly, Aurora-A inhibitors are being studied in a number of ongoing clinical trials. However, whether and how Aurora-A has a role in the regulation of the mitotic checkpoint is controversial. Additionally, the function of nuclear-accumulated Aurora-A in late G2 phase is not clear. Here we show that knockout, inhibition or blockade of the nuclear entry of Aurora-A severely decreased the centromere localization of Aurora-B and the phosphorylation of histone H3 threonine 3 (H3T3-ph) mediated by the kinase Haspin in late G2 phase. We further reveal that nuclear-accumulated Aurora-A phosphorylates Haspin at multiple sites at its N-terminus and that this promotes H3T3-ph and the rapid recruitment to the centromere of the chromosomal passenger complex. In addition, Aurora-A facilitates the association of Aurora-B with their common substrates: Haspin and Plk1. Notably, these functions of Aurora-A are mostly independent of Plk1. Thus we demonstrate that, in late G2 and prophase, Aurora-A phosphorylates Haspin to trigger the Haspin-H3T3-ph-Aurora-B positive feedback loop that supports the timely establishment of the chromosomal passenger complex and the mitotic checkpoint before spindle assembly. PMID:28101375

  3. Altered expression of Aurora kinases in Arabidopsis results in aneu- and polyploidization.

    PubMed

    Demidov, Dmitri; Lermontova, Inna; Weiss, Oda; Fuchs, Joerg; Rutten, Twan; Kumke, Katrin; Sharbel, Timothy F; Van Damme, Daniel; De Storme, Nico; Geelen, Danny; Houben, Andreas

    2014-11-01

    Aurora is an evolutionary conserved protein kinase family involved in monitoring of chromosome segregation via phosphorylation of different substrates. In plants, however, the involvement of Aurora proteins in meiosis and in sensing microtubule attachment remains to be proven, although the downstream components leading to the targeting of spindle assembly checkpoint signals to anaphase-promoting complex have been described. To analyze the three members of Aurora family (AtAurora1, -2, and -3) of Arabidopsis we employed different combinations of T-DNA insertion mutants and/or RNAi transformants. Meiotic defects and the formation of unreduced pollen were revealed including plants with an increased ploidy level. The effect of reduced expression of Aurora was mimicked by application of the ATP-competitive Aurora inhibitor II. In addition, strong overexpression of any member of the AtAurora family is not possible. Only tagged or truncated forms of Aurora kinases can be overexpressed. Expression of truncated AtAurora1 resulted in a high number of aneuploids in Arabidopsis, while expression of AtAurora1-TAPi construct in tobacco resulted in 4C (possible tetraploid) progeny. In conclusion, our data demonstrate an essential role of Aurora kinases in the monitoring of meiosis in plants.

  4. Aurora-A Kinase as a Promising Therapeutic Target in Cancer.

    PubMed

    D'Assoro, Antonino B; Haddad, Tufia; Galanis, Evanthia

    2015-01-01

    Mammalian Aurora family of serine/threonine kinases are master regulators of mitotic progression and are frequently overexpressed in human cancers. Among the three members of the Aurora kinase family (Aurora-A, -B, and -C), Aurora-A and Aurora-B are expressed at detectable levels in somatic cells undergoing mitotic cell division. Aberrant Aurora-A kinase activity has been implicated in oncogenic transformation through the development of chromosomal instability and tumor cell heterogeneity. Recent studies also reveal a novel non-mitotic role of Aurora-A activity in promoting tumor progression through activation of epithelial-mesenchymal transition reprograming resulting in the genesis of tumor-initiating cells. Therefore, Aurora-A kinase represents an attractive target for cancer therapeutics, and the development of small molecule inhibitors of Aurora-A oncogenic activity may improve the clinical outcomes of cancer patients. In the present review, we will discuss mitotic and non-mitotic functions of Aurora-A activity in oncogenic transformation and tumor progression. We will also review the current clinical studies, evaluating small molecule inhibitors of Aurora-A activity and their efficacy in the management of cancer patients.

  5. Haspin inhibitors reveal centromeric functions of Aurora B in chromosome segregation

    PubMed Central

    Wang, Fangwei; Ulyanova, Natalia P.; Daum, John R.; Patnaik, Debasis; Kateneva, Anna V.; Gorbsky, Gary J.

    2012-01-01

    Haspin phosphorylates histone H3 at threonine-3 (H3T3ph), providing a docking site for the Aurora B complex at centromeres. Aurora B functions to correct improper kinetochore–microtubule attachments and alert the spindle checkpoint to the presence of misaligned chromosomes. We show that Haspin inhibitors decreased H3T3ph, resulting in loss of centromeric Aurora B and reduced phosphorylation of centromere and kinetochore Aurora B substrates. Consequently, metaphase chromosome alignment and spindle checkpoint signaling were compromised. These effects were phenocopied by microinjection of anti-H3T3ph antibodies. Retargeting Aurora B to centromeres partially restored checkpoint signaling and Aurora B–dependent phosphorylation at centromeres and kinetochores, bypassing the need for Haspin activity. Haspin inhibitors did not obviously affect phosphorylation of histone H3 at serine-10 (H3S10ph) by Aurora B on chromosome arms but, in Aurora B reactivation assays, recovery of H3S10ph was delayed. Haspin inhibitors did not block Aurora B localization to the spindle midzone in anaphase or Aurora B function in cytokinesis. Thus, Haspin inhibitors reveal centromeric roles of Aurora B in chromosome movement and spindle checkpoint signaling. PMID:23071152

  6. Aurora-A Kinase as a Promising Therapeutic Target in Cancer

    PubMed Central

    D’Assoro, Antonino B.; Haddad, Tufia; Galanis, Evanthia

    2016-01-01

    Mammalian Aurora family of serine/threonine kinases are master regulators of mitotic progression and are frequently overexpressed in human cancers. Among the three members of the Aurora kinase family (Aurora-A, -B, and -C), Aurora-A and Aurora-B are expressed at detectable levels in somatic cells undergoing mitotic cell division. Aberrant Aurora-A kinase activity has been implicated in oncogenic transformation through the development of chromosomal instability and tumor cell heterogeneity. Recent studies also reveal a novel non-mitotic role of Aurora-A activity in promoting tumor progression through activation of epithelial–mesenchymal transition reprograming resulting in the genesis of tumor-initiating cells. Therefore, Aurora-A kinase represents an attractive target for cancer therapeutics, and the development of small molecule inhibitors of Aurora-A oncogenic activity may improve the clinical outcomes of cancer patients. In the present review, we will discuss mitotic and non-mitotic functions of Aurora-A activity in oncogenic transformation and tumor progression. We will also review the current clinical studies, evaluating small molecule inhibitors of Aurora-A activity and their efficacy in the management of cancer patients. PMID:26779440

  7. Aurora kinase A interacts with H-Ras and potentiates Ras-MAPK signaling.

    PubMed

    Umstead, MaKendra; Xiong, Jinglin; Qi, Qi; Du, Yuhong; Fu, Haian

    2017-02-03

    In cancer, upregulated Ras promotes cellular transformation and proliferation in part through activation of oncogenic Ras-MAPK signaling. While directly inhibiting Ras has proven challenging, new insights into Ras regulation through protein-protein interactions may offer unique opportunities for therapeutic intervention. Here we report the identification and validation of Aurora kinase A (Aurora A) as a novel Ras binding protein. We demonstrate that the kinase domain of Aurora A mediates the interaction with the N-terminal domain of H-Ras. Further more, the interaction of Aurora A and H-Ras exists in a protein complex with Raf-1. We show that binding of H-Ras to Raf-1 and subsequent MAPK signaling is enhanced by Aurora A, and requires active H-Ras. Thus, the functional linkage between Aurora A and the H-Ras/Raf-1 protein complex may provide a mechanism for Aurora A's oncogenic activity through direct activation of the Ras/MAPK pathway.

  8. A small molecule identified through an in silico screen inhibits Aurora B-INCENP interaction.

    PubMed

    Unsal, Esra; Degirmenci, Bahar; Harmanda, Büşra; Erman, Burak; Ozlu, Nurhan

    2016-12-01

    Aurora B is a serine/threonine kinase that has a central role in the regulation of mitosis. The observation of Aurora B overexpression in cancer makes it a promising target to develop antitumoral inhibitors. We describe a new potential inhibitor that exclusively targets the interaction site of Aurora B and its activator INCENP. We performed a structure-based virtual screening and determined five potential candidates of 200 000 compounds, which selectively bind to the Aurora B::INCENP interaction site, but not to the ATP-binding site (kinase pocket) of Aurora B or other related kinases. Further characterization in vivo validated the inhibitory role of one of these five compounds in Aurora B::INCENP complex formation and exhibited hallmarks of Aurora inhibition such as chromosome congression and segregation defects that interfere with the progression into cytokinesis and result in multinuclear cells. Our results provide an alternative approach on the way of exploring specific kinase inhibitors.

  9. A Pentacyclic Aurora Kinase Inhibitor (AKI-001) With High in Vivo Potency And Oral Bioavailability

    SciTech Connect

    Rawson, T.E.; Ruth, M.; Blackwood, E.; Burdick, D.; Corson, L.; Dotson, J.; Drummond, J.; Fields, C.; Georges, G.J.; Goller, B.; Halladay, J.; Hunsaker, T.; Kleinheinz, T.; Krell, H.-W.; Li, J.; Liang, J.; Limberg, A.; McNutt, A.; Moffat, J.; Phillips, G.; Ran, Y.

    2009-05-21

    Aurora kinase inhibitors have attracted a great deal of interest as a new class of antimitotic agents. We report a novel class of Aurora inhibitors based on a pentacyclic scaffold. A prototype pentacyclic inhibitor 32 (AKI-001) derived from two early lead structures improves upon the best properties of each parent and compares favorably to a previously reported Aurora inhibitor, 39 (VX-680). The inhibitor exhibits low nanomolar potency against both Aurora A and Aurora B enzymes, excellent cellular potency (IC{sub 50} < 100 nM), and good oral bioavailability. Phenotypic cellular assays show that both Aurora A and Aurora B are inhibited at inhibitor concentrations sufficient to block proliferation. Importantly, the cellular activity translates to potent inhibition of tumor growth in vivo. An oral dose of 5 mg/kg QD is well tolerated and results in near stasis (92% TGI) in an HCT116 mouse xenograft model.

  10. CODA: Coordinated Observations of Dynamics in Aurora

    NASA Technical Reports Server (NTRS)

    Larsen, M. F.

    2003-01-01

    The grant funds were provided to carry out chemical tracer wind and turbulence measurements in the mesosphere and lower thermosphere as part of the Coordinated Observations of Dynamics in Aurora (CODA) experiment for which Dr. Andy Christensen of the Aerospace Corp. was the Principal Investigator. Clemson University was a co-investigator institution on the project and was tasked with designing, building, and testing a total of four chemical tracer release payloads which were used to release trimethyl aluminum (TMA) to measure the winds and turbulent diffusion. All four payloads were flown from the rocket range at Poker Flat, Alaska, in support of instrumented payloads flown from the same location. The CODA experiment was designed to investigate the changes in the chemical composition in the lower thermosphere during an auroral substorm event. In particular, the objective was to determine the relative importance of two competing mechanisms. The first mechanism is associated with the advection of air from the polar cap into the auroral oval. A flow in that direction is typical in the postmidnight sector of the oval. As the air moves from the region of negligible forcing in the polar cap to the region of strong forcing and heating in the oval, changes in the composition are expected to occur. Alternatively, enhanced local mixing will also cause such changes. Since the auroral forcing accelerates the neutral winds in the lower E region, but not at lower altitudes, the forcing results in large shears that can be large enough to be unstable in the Richardson number sense. The unstable shears are expected to generate turbulence and therefore enhanced mixing. Such mixing will also create composition changes similar to what is observed. In the CODA experiment an instrumented payload designed and built by the Aerospace Corporation was used to measure the composition and plasma parameters needed to define the auroral forcing. In addition, three chemical tracer payloads were

  11. CODA: Coordinated Observations of Dynamics in Aurora

    NASA Technical Reports Server (NTRS)

    Larsen, M. F.

    2003-01-01

    The grant funds were provided to carry out chemical tracer wind and turbulence measurements in the mesosphere and lower thermosphere as part of the Coordinated Observations of Dynamics in Aurora (CODA) experiment for which Dr. Andy Christensen of the Aerospace Corp. was the Principal Investigator. Clemson University was a co-investigator institution on the project and was tasked with designing, building, and testing a total of four chemical tracer release payloads which were used to release trimethyl aluminum (TMA) to measure the winds and turbulent diffusion. All four payloads were flown from the rocket range at Poker Flat, Alaska, in support of instrumented payloads flown from the same location. The CODA experiment was designed to investigate the changes in the chemical composition in the lower thermosphere during an auroral substorm event. In particular, the objective was to determine the relative importance of two competing mechanisms. The first mechanism is associated with the advection of air from the polar cap into the auroral oval. A flow in that direction is typical in the postmidnight sector of the oval. As the air moves from the region of negligible forcing in the polar cap to the region of strong forcing and heating in the oval, changes in the composition are expected to occur. Alternatively, enhanced local mixing will also cause such changes. Since the auroral forcing accelerates the neutral winds in the lower E region, but not at lower altitudes, the forcing results in large shears that can be large enough to be unstable in the Richardson number sense. The unstable shears are expected to generate turbulence and therefore enhanced mixing. Such mixing will also create composition changes similar to what is observed. In the CODA experiment an instrumented payload designed and built by the Aerospace Corporation was used to measure the composition and plasma parameters needed to define the auroral forcing. In addition, three chemical tracer payloads were

  12. Midday depression of leaf CO2 exchange within the crown of Dipterocarpus sublamellatus in a lowland dipterocarp forest in Peninsular Malaysia.

    PubMed

    Kosugi, Yoshiko; Takanashi, Satoru; Matsuo, Naoko; Nik, Abdul Rahim

    2009-04-01

    We observed diurnal and seasonal patterns of leaf-scale gas exchange within the crown of a Dipterocarpus sublamellatus Foxw. tree growing in a lowland dipterocarp forest at Pasoh, Peninsular Malaysia. Observations were carried out nine times over 6 years, from September 2002 to December 2007. Observation periods included both wet and mild-dry periods, and natural and saturated photosynthetic photon flux density (PPFD) light conditions. In situ measurements of the diurnal change in net photosynthetic rate and in stomatal conductance were carried out on canopy leaves of a 40-m-tall D. sublamellatus tree, which was accessed from a canopy corridor. A diurnal change in electron transport rate was observed under saturated PPFD conditions. The maximum net assimilation rate was approximately 10 micromol m(-2) s(-1). There was a clear inhibition of the net assimilation rate coupled with stomatal closure after late morning and this inhibition occurred year-round. Although the electron transport rate decreased alongside this inhibition, it sometimes followed on. Numerical analysis showed that the main factor in the inhibition of the net assimilation rate was patchy bimodal stomatal closure, which occurred in both mild-dry and wet periods. The midday depression occurred year-round, though there are fluctuations in soil moisture during the mild-dry and wet periods. The magnitude of the inhibition was not related to soil water content but was related to vapor pressure deficit (VPD): that is, whether the days were sunny and hot or cloudy and cool. On cloudy, cool days in the wet period, the net photosynthesis was only moderately inhibited, but it still decreased in the afternoon and was coupled with patchy stomatal closure, even in quite moderate VPD, leaf temperature and PPFD conditions. Our results suggest that patchy stomatal closure signaled by the increase in VPD, in transpiration and by circadian rhythms, was the key factor in constraining midday leaf gas exchange of the D

  13. Comparison of nutritional status of rural and urban school students receiving midday meals in schools of Bengaluru, India: a cross sectional study.

    PubMed

    Shalini, C N; Murthy, N S; Shalini, S; Dinesh, R; Shivaraj, N S; Suryanarayana, S P

    2014-01-01

    The objective of the study was to assess the impact of the mid day meal program by assessing the nutritional status of school students aged 5-15 years receiving midday meals in rural schools and compare them with those in urban schools in Bengaluru, India. This cross sectional study involved a sample of 4378 students from government and aided schools. Weight and height were measured and compared with ''means'' and ''percentiles'' of expected standards as endorsed by the Indian Association of Pediatrics. Regression coefficients were also estimated to assess the rate of growth. In all age groups and in both sexes, the observed mean weight and height were below the expected standards. The study findings showed that 13.8% and 13.1% of the studied students were underweight and stunted, respectively (below the third percentile for weight and height for age). A higher proportion of rural students were below the third percentile for both weight and height compared with urban students (weight: 16.3% and 11.5%; height: 17.0% and 10.0%; P < 0.05 for both weight and height). Only 2.4% and 3.1% were above 97 th percentile for weight and height. The rate of growth of height for weight showed a declining trend with increasing age in all the groups. The authors believe that the magnitude of the burden of undernourished students as seen in this study would have been much greater in the absence of the midday meal program. Greater involvement of the private sector to assist the government would help augment nutrition in children and indirectly impact school performance, attendance and literacy.

  14. Structural Biology Insight for the Design of Sub-type Selective Aurora Kinase Inhibitors.

    PubMed

    Sarvagalla, Sailu; Coumar, Mohane Selvaraj

    2015-01-01

    Aurora kinase A, B and C, are key regulators of mitosis and are over expressed in many of the human cancers, making them an ideal drug target for cancer chemotherapy. Currently, over a dozen of Aurora kinase inhibitors are in various phases of clinical development. The majority of the inhibitors (VX-680/MK-0457, PHA-739358, CYC116, SNS-314, AMG 900, AT-9283, SCH- 1473759, ABT-348, PF-03814735, R-763/AS-703569, KW-2449 and TAK-901) are pan-selective (isoform non-selective) and few are Aurora A (MLN8054, MLN8237, VX-689/MK5108 and ENMD 2076) and Aurora B (AZD1152 and GSK1070916) sub-type selective. Despite the intensive research efforts in the past decade, no Aurora kinase inhibitor has reached the market. Recent evidence suggests that the sub-type selective Aurora kinase A inhibitor could possess advantages over pan-selective Aurora inhibitors, by avoiding Aurora B mediated neutropenia. However, sub-type selective Aurora kinase A inhibitor design is very challenging due to the similarity in the active site among the isoforms. Structural biology and computational aspects pertaining to the design of Aurora kinase inhibitors were analyzed and found that a possible means to develop sub-type selective inhibitor is by targeting Aurora A specific residues (Leu215, Thr217 and Arg220) or Aurora B specific residues (Arg159, Glu161 and Lys164), near the solvent exposed region of the protein. Particularly, a useful strategy for the design of sub-type selective Aurora A inhibitor could be by targeting Thr217 residue as in the case of MLN8054. Further preclinical and clinical studies with the sub-type selective Aurora inhibitors could help bring them to the market for the treatment of cancer.

  15. Identification and dynamics of two classes of aurora-like kinases in Arabidopsis and other plants.

    PubMed

    Demidov, Dmitri; Van Damme, Daniël; Geelen, Danny; Blattner, Frank R; Houben, Andreas

    2005-03-01

    Aurora-like kinases play key roles in chromosome segregation and cytokinesis in yeast, plant, and animal systems. Here, we characterize three Arabidopsis thaliana protein kinases, designated AtAurora1, AtAurora2, and AtAurora3, which share high amino acid identities with the Ser/Thr kinase domain of yeast Ipl1 and animal Auroras. Structure and expression of AtAurora1 and AtAurora2 suggest that these genes arose by a recent gene duplication, whereas the diversification of plant alpha and beta Aurora kinases predates the origin of land plants. The transcripts and proteins of all three kinases are most abundant in tissues containing dividing cells. Intracellular localization of green fluorescent protein-tagged AtAuroras revealed an AtAurora-type specific association mainly with dynamic mitotic structures, such as microtubule spindles and centromeres, and with the emerging cell plate of dividing tobacco (Nicotiana tabacum) BY-2 cells. Immunolabeling using AtAurora antibodies yielded specific signals at the centromeres that are coincident with histone H3 that is phosphorylated at Ser position10 during mitosis. An in vitro kinase assay demonstrated that AtAurora1 preferentially phosphorylates histone H3 at Ser 10 but not at Ser 28 or Thr 3, 11, and 32. The phylogenetic analysis of available Aurora sequences from different eukaryotic origins suggests that, although a plant Aurora gene has been duplicated early in the evolution of plants, the paralogs nevertheless maintained a role in cell cycle-related signal transduction pathways.

  16. Functions of Aurora kinase C in meiosis and cancer.

    PubMed

    Quartuccio, Suzanne M; Schindler, Karen

    2015-01-01

    The mammalian genome encodes three Aurora kinase protein family members: A, B, and C. While Aurora kinase A (AURKA) and B (AURKB) are found in cells throughout the body, significant protein levels of Aurora kinase C (AURKC) are limited to cells that undergo meiosis (sperm and oocyte). Despite its discovery nearly 20 years ago, we know little about the function of AURKC compared to that of the other 2 Aurora kinases. This lack of understanding can be attributed to the high sequence homology between AURKB and AURKC preventing the use of standard approaches to understand non-overlapping and meiosis I (MI)-specific functions of the two kinases. Recent evidence has revealed distinct functions of AURKC in meiosis and may aid in our understanding of why chromosome segregation during MI often goes awry in oocytes. Many cancers aberrantly express AURKC, but because we do not fully understand AURKC function in its normal cellular context, it is difficult to predict the biological significance of this expression on the disease. Here, we consolidate and update what is known about AURKC signaling in meiotic cells to better understand why it has oncogenic potential.

  17. Regulation of Aurora-A kinase on the mitotic spindle.

    PubMed

    Kufer, Thomas A; Nigg, Erich A; Silljé, Herman H W

    2003-12-01

    The error-free segregation of duplicated chromosomes during cell division is essential for the maintenance of an intact genome. This process is brought about by a highly dynamic bipolar array of microtubules, the mitotic spindle. The formation and function of the mitotic spindle during M-phase of the cell cycle is regulated by protein phosphorylation, involving multiple protein kinases and phosphatases. Prominent among the enzymes implicated in spindle assembly is the serine/threonine-specific protein kinase Aurora-A. In several common human tumors, Aurora-A is overexpressed, and deregulation of this kinase was shown to result in mitotic defects and aneuploidy. Moreover, recent genetic evidence directly links the human Aurora-A gene to cancer susceptibility. Several of the physiological substrates of Aurora-A presumably await identification, but recent studies are beginning to shed light on the regulation of this critical mitotic kinase. Here, we review these findings with particular emphasis on the role of TPX2, a prominent spindle component implicated in a Ran-GTP-mediated spindle assembly pathway.

  18. Discrete and broadband electron acceleration in Jupiter's powerful aurora

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.; Haggerty, D. K.; Paranicas, C.; Clark, G.; Kollmann, P.; Rymer, A. M.; Bolton, S. J.; Levin, S. M.; Adriani, A.; Allegrini, F.; Bagenal, F.; Bonfond, B.; Connerney, J. E. P.; Gladstone, G. R.; Kurth, W. S.; McComas, D. J.; Valek, P.

    2017-09-01

    The most intense auroral emissions from Earth's polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth's space environment to its polar regions. In contrast, Earth's less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvénic aurora). Jupiter's relatively steady main aurora has a power density that is so much larger than Earth's that it has been taken for granted that it must be generated primarily by the discrete auroral process. However, preliminary in situ measurements of Jupiter's auroral regions yielded no evidence of such a process. Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter's auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth. Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.

  19. HPV16 E6 upregulates Aurora A expression

    PubMed Central

    Guo, Yi; Ma, Jiaming; Zheng, Yahong; Li, Lu; Gui, Xiaowei; Wang, Qian; Meng, Xiangkai; Shang, Hong

    2016-01-01

    Overexpression of Aurora A kinase occurs in certain types of cancer, and therefore results in chromosome instability and phosphorylation-mediated ubiquitylation and degradation of p53 for tumorigenesis. The high-risk subtype human papillomavirus (HPV)16 early oncoprotein E6 is a major contributor inducing host cell immortalization and transformation through interaction with a number of cellular factors. In the present study, co-immunoprecipitation, glutathione S-transferase pull-down and immunostaining were used to show that HPV16 E6 and Aurora A bind to each other in vivo and in vitro. Western blotting and reverse transcription-polymerase chain reaction were used to reveal that HPV16 E6 inhibited cell apoptosis by stabilizing Aurora A expression. The present study may report a new mechanism for the involvement of HPV16 E6 in carcinogenesis, as HPV16 E6 elevates Aurora A expression and the latter may be a common target for oncogenic viruses that result in cell carcinogenesis. PMID:27446442

  20. Aurora Australis view taken by the Expedition 29 crew

    NASA Image and Video Library

    2011-09-18

    ISS029-E-006404 (18 Sept. 2011) --- This is one of a series of night time images photographed by one of the Expedition 29 crew members from the International Space Station. It features Aurora Australis and parts of the southeastern Indian Ocean. Nadir coordinates are 49.42 degrees south latitude and 121.01 degrees east longitude.

  1. Aurora Astralis taken by the Expedition Seven crew

    NASA Image and Video Library

    2003-06-03

    ISS007-E-06083 (3 June 2003) --- This view featuring the Aurora Australis or “southern lights” was photographed by astronaut Edward T. Lu, Expedition 7 NASA ISS science officer and flight engineer aboard the International Space Station (ISS). The four stars hanging above Earth’s limb are the brightest stars of the southern constellation Corvus.

  2. Aurora Australis view taken by the Expedition 29 crew

    NASA Image and Video Library

    2011-09-18

    ISS029-E-006406 (18 Sept. 2011) --- This is one of a series of night time images photographed by one of the Expedition 29 crew members from the International Space Station. It features Aurora Australis and parts of the southeastern Indian Ocean. Nadir coordinates are 49.30 degrees south latitude and 121.56 degrees east longitude.

  3. Aurora City Schools Kindergarten Math Readiness Course of Study.

    ERIC Educational Resources Information Center

    Aurora City Schools, OH.

    The program goals and objectives for Kindergarten mathematics readiness in Aurora City Schools are listed and described. Consideration of Kindergarten Philosophy, the diverse population of students, the organizational design of adopted textbooks, child development and learning styles, are all assessed in establishing scope and sequence. The…

  4. View of Aurora near Earth's limb taken during Expedition Six

    NASA Image and Video Library

    2003-03-01

    ISS006-327-027 (March 2003) --- The Aurora Borealis, also known as “northern lights”, is featured in this photograph taken by astronaut Donald R. Pettit, Expedition 6 NASA ISS science officer, onboard the International Space Station (ISS).

  5. The grand aurorae borealis seen in Colombia in 1859

    NASA Astrophysics Data System (ADS)

    Cárdenas, Freddy Moreno; Sánchez, Sergio Cristancho; Domínguez, Santiago Vargas

    2016-01-01

    On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9°N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia allowed the identification of a narrative from Montería, Colombia (8° 45‧N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event.

  6. View of Aurora near Earth's limb taken during Expedition Six

    NASA Image and Video Library

    2003-03-01

    ISS006-327-026 (March 2003) --- The Aurora Borealis, also known as “northern lights”, is featured in this photograph taken by astronaut Donald R. Pettit, Expedition 6 NASA ISS science officer, onboard the International Space Station (ISS).

  7. QSAR studies on imidazopyrazine derivatives as Aurora A kinase inhibitors.

    PubMed

    Leng, Y; Lu, T; Yuan, H L; Liu, H C; Lu, S; Zhang, W W; Jiang, Y L; Chen, Y D

    2012-10-01

    Aurora kinases have emerged as attractive targets for the development of novel anti-cancer agents. A combined study of molecular docking, pharmacophore modelling and 3D-QSAR was performed on a series of imidazo [1, 2-a] pyrazines as novel Aurora kinase inhibitors to gain insights into the structural determinants and their structure-activity relationship. An ensemble of conformations based on molecular docking was used for PHASE pharmacophore studies. The developed best-fitted pharmacophore model was validated by diverse chemotypes of Aurora A kinase inhibitors and was consistent with the structural requirements for the docked binding mechanism. Subsequently, the pharmacophore-based alignment was used to develop PHASE and comparative molecular similarity indices analysis (CoMSIA) 3D-QSAR models. The best CoMSIA model showed good statistics (q (2 )= 0.567, r (2 )= 0.992), and the predictive ability of the model was validated using an external test set of 13 compounds giving a satisfactory prediction ([Formula: see text]). The 3D contour maps provided insight into the binding mechanism and highlighted key structural features that are essential to the inhibitory activity. Based on the PHASE and CoMSIA 3D-QSAR results, a set of novel Aurora A inhibitors were designed that showed excellent potencies.

  8. Astronaut Scott Carpenter inserted into Aurora 7 spacecraft

    NASA Technical Reports Server (NTRS)

    1962-01-01

    Astronaut M. Scott Carpenter, pilot of the Mercury-Atlas 7 space flight, is inserted into Aurora 7 spacecraft during the prelaunch countdown. Carpenter is assisted into the spacecraft by Astronaut John Glenn and Gunter Vendt, McDonnell Douglas pad capsule test conducter.

  9. Discrete and broadband electron acceleration in Jupiter's powerful aurora.

    PubMed

    Mauk, B H; Haggerty, D K; Paranicas, C; Clark, G; Kollmann, P; Rymer, A M; Bolton, S J; Levin, S M; Adriani, A; Allegrini, F; Bagenal, F; Bonfond, B; Connerney, J E P; Gladstone, G R; Kurth, W S; McComas, D J; Valek, P

    2017-09-06

    The most intense auroral emissions from Earth's polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth's space environment to its polar regions. In contrast, Earth's less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvénic aurora). Jupiter's relatively steady main aurora has a power density that is so much larger than Earth's that it has been taken for granted that it must be generated primarily by the discrete auroral process. However, preliminary in situ measurements of Jupiter's auroral regions yielded no evidence of such a process. Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter's auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth. Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.

  10. The grand aurorae borealis seen in Colombia in 1859

    NASA Astrophysics Data System (ADS)

    Moreno Cárdenas, Freddy; Cristancho Sánchez, Sergio; Vargas Domínguez, Santiago

    2016-01-01

    On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9°N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia allowed the identification of a narrative from Montería, Colombia (8° 45‧N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event.

  11. Aurora City Schools Kindergarten Math Readiness Course of Study.

    ERIC Educational Resources Information Center

    Aurora City Schools, OH.

    The program goals and objectives for Kindergarten mathematics readiness in Aurora City Schools are listed and described. Consideration of Kindergarten Philosophy, the diverse population of students, the organizational design of adopted textbooks, child development and learning styles, are all assessed in establishing scope and sequence. The…

  12. Traditional Knowledge: An Implementation Workplan for Aurora College.

    ERIC Educational Resources Information Center

    Aurora Coll., Fort Smith (Northwest Territories).

    Prepared as part of an effort to make Aurora College, in the Northwest Territories, Canada, more responsive to the Native American communities that form its primary student base, this plan outline strategies for infusing traditional knowledge into the college's day-to-day operations. Following introductory sections describing traditional knowledge…

  13. Hubble Captures Vivid Auroras in Jupiter’s Atmosphere

    NASA Image and Video Library

    2016-06-30

    Astronomers are using the NASA/ESA Hubble Space Telescope to study auroras — stunning light shows in a planet’s atmosphere — on the poles of the largest planet in the solar system, Jupiter. This observation program is supported by measurements made by NASA’s Juno spacecraft, currently on its way to Jupiter. Jupiter, the largest planet in the solar system, is best known for its colorful storms, the most famous being the Great Red Spot. Now astronomers have focused on another beautiful feature of the planet, using Hubble's ultraviolet capabilities. The extraordinary vivid glows shown in the new observations are known as auroras. They are created when high-energy particles enter a planet’s atmosphere near its magnetic poles and collide with atoms of gas. As well as producing beautiful images, this program aims to determine how various components of Jupiter’s auroras respond to different conditions in the solar wind, a stream of charged particles ejected from the sun. This observation program is perfectly timed as NASA’s Juno spacecraft is currently in the solar wind near Jupiter and will enter the orbit of the planet in early July 2016. While Hubble is observing and measuring the auroras on Jupiter, Juno is measuring the properties of the solar wind itself; a perfect collaboration between a telescope and a space probe. “These auroras are very dramatic and among the most active I have ever seen”, said Jonathan Nichols from the University of Leicester, U.K., and principal investigator of the study. “It almost seems as if Jupiter is throwing a firework party for the imminent arrival of Juno.” Credits: NASA, ESA, and J. Nichols (University of Leicester)

  14. Hubble Captures Vivid Auroras in Jupiter’s Atmosphere

    NASA Image and Video Library

    2017-09-28

    Astronomers are using the NASA/ESA Hubble Space Telescope to study auroras — stunning light shows in a planet’s atmosphere — on the poles of the largest planet in the solar system, Jupiter. This observation program is supported by measurements made by NASA’s Juno spacecraft, currently on its way to Jupiter. Jupiter, the largest planet in the solar system, is best known for its colorful storms, the most famous being the Great Red Spot. Now astronomers have focused on another beautiful feature of the planet, using Hubble's ultraviolet capabilities. The extraordinary vivid glows shown in the new observations are known as auroras. They are created when high-energy particles enter a planet’s atmosphere near its magnetic poles and collide with atoms of gas. As well as producing beautiful images, this program aims to determine how various components of Jupiter’s auroras respond to different conditions in the solar wind, a stream of charged particles ejected from the sun. This observation program is perfectly timed as NASA’s Juno spacecraft is currently in the solar wind near Jupiter and will enter the orbit of the planet in early July 2016. While Hubble is observing and measuring the auroras on Jupiter, Juno is measuring the properties of the solar wind itself; a perfect collaboration between a telescope and a space probe. “These auroras are very dramatic and among the most active I have ever seen”, said Jonathan Nichols from the University of Leicester, U.K., and principal investigator of the study. “It almost seems as if Jupiter is throwing a firework party for the imminent arrival of Juno.” Read more: go.nasa.gov/294QswK Credits: NASA, ESA, and J. Nichols (University of Leicester)

  15. Response of the night aurora to a negative sudden impulse

    NASA Astrophysics Data System (ADS)

    Belakhovsky, V. B.; Vorobjev, V. G.

    2016-11-01

    Data from the meridian scanning photometers of the NORSTAR network and all-sky cameras of the THEMIS network were used for a detailed study of the response of night auroras to the sharp decrease of the solar wind dynamic pressure on September 28, 2009. The decrease in dynamic pressure was accompanied by a corresponding depression of the magnetic field in the SYM-H index and the origin of a negative sudden impulse ( SI) with a duration of 5-8 min and amplitude of 150-200 nT in the horizontal component of the magnetic field at stations of the night sector of the auroral zone. The magnetic impulse was preceded by a long calm magnetic period, although the IMF Bz-component was negative for 1.5 hour before the SI -. The commencement of the SI -, which was determined by variations in the magnetic field at 0650 UT, was accompanied by a sharp increase in the intensity of discrete forms of polar auroras in the midnight sector of the auroral zone and their fast propagation to the pole. Approximately 6-8 min after the SI -, the auroral intensity in the emissions, which were excited by the fluxes of precipitated electrons and protons, quickly began to decrease in the night sector. Analysis of the optical observations showed the two-stage character of the response of the night auroras to the SI - in the considered event: first, fast movement of the discrete aurora forms to the pole with a significant increase in their intensity, and a further fast decrease in auroral intensity with a delay of 6-8 min relative to the SI -. The possible reasons for such aurora behavior are discussed.

  16. Solar wind signatures in the dayside aurora. (Invited)

    NASA Astrophysics Data System (ADS)

    Mende, S. B.; Frey, H. U.

    2013-12-01

    The THEMIS satellite configuration allows monitoring the solar wind directly in front of the magnetosphere thereby removing ambiguities due to long propagation delays from distant satellites. This situation provides an unprecedented opportunity to monitor the dayside magnetospheric boundary by THEMIS while observing the magnetically conjugate auroras at South Pole and at other Antarctic stations of the US Automatic Geophysical Observatories (AGO) chain. In the dayside magnetosphere field line mapping is expected to be relatively accurate because the field is relatively strong and the distance to the magnetopause is relatively short. Mapping the location of THEMIS crossings of the magnetopause to the aurora shows that cusp auroras tend to occur on open field lines. In most cases the THEMIS satellites show multiple crossings of the magnetopause due to the wavelike radial motion of the magnetopause. These motions are likely to be spontaneous resonances of the field because it was not possible to correlate these motions with latitude movements of the dayside aurora at the magnetic foot point or with variations in pressure or magnetic field of the solar wind immediately in front of the magnetosphere. Persistently occurring dayside transients in the aurora are Pole-ward Moving Auroral Forms (PMAF-s) which occur regularly regardless of the direction of the IMF Bz component. These features generally dissipate quickly within the all-sky imager FOV but there are examples when faint emissions persist while traveling pole-ward and across the entire FOV indicating anti-sunward flow in the polar cap. The movement of polar patches seen inside the polar cap also shows this anti-sunward flow. In some cases the timing and appearance of the patches near the night-side auroral boundary and the observation of subsequent pole-ward substorm surge are consistent with 'substorm triggering' through polar patch associated Polar Boundary Intensifications (PBI-s) and subsequent substorm onsets.

  17. Dual Aurora A and JAK2 kinase blockade effectively suppresses malignant transformation

    PubMed Central

    Yang, Hua; Lawrence, Harshani R.; Kazi, Aslamuzzaman; Gevariya, Harsukh; Patel, Ronil; Luo, Yunting; Rix, Uwe; Schonbrunn, Ernst; Lawrence, Nicholas J.; Sebti, Said M.

    2014-01-01

    Aurora A and JAK2 kinases are involved in cell division and tumor cell survival, respectively. Here we demonstrate that ectopic expression of Aurora A and JAK2 together is more effective than each alone at inducing non-transformed cells to grow in an anchorage-independent manner and to invade. Furthermore, siRNA silencing or pharmacological inhibition of Aurora A and JAK2 with Alisertib and Ruxolitinib, respectively, is more effective than blocking each kinase alone at suppressing anchorage-dependent and –independent growth and invasion as well as at inducing apoptosis. Importantly, we have developed dual Aurora and JAK inhibitors, AJI-214 and AJI-100, which potently inhibit Aurora A, Aurora B and JAK2 in vitro. In human cancer cells, these dual inhibitors block the auto-phosphorylation of Aurora A (Thr-288) and the phosphorylation of the Aurora B substrate histone H3 (Ser-10) and the JAK2 substrate STAT3 (Tyr-705). Furthermore, AJI-214 and AJI-100 inhibit anchorage dependent and independent cell growth and invasion and induce G2/M cell cycle accumulation and apoptosis. Finally, AJI-100 caused regression of human tumor xenografts in mice. Taken together, our genetic and pharmacological studies indicate that targeting Aurora A and JAK2 together is a more effective approach than each kinase alone at inhibiting malignant transformation and warrant further advanced pre clinical investigations of dual Aurora A/JAK2 inhibitors as potential anti tumor agents. PMID:24930769

  18. Elevated Aurora B expression contributes to chemoresistance and poor prognosis in breast cancer.

    PubMed

    Zhang, Yiqian; Jiang, Chunling; Li, Huilan; Lv, Feng; Li, Xiaoyan; Qian, Xiaolong; Fu, Li; Xu, Bo; Guo, Xiaojing

    2015-01-01

    Aurora-B is a major kinase responsible for appropriate mitotic progression. Elevated expression of Aurora-B has been frequently associated with several types of cancer, including breast cancer. However, it is not clear whether the alteration contributes to tumor responses to therapies and prognosis. In this study, we conducted immunohistochemistry using antibodies against Aurora-B, S1981p-ATM, Ki67, and p53 in paraffin-embedded tumor tissues from 312 invasive breast cancer patients. The correlation between disease-free-survival (DFS) and Aurora-B expression was analyzed using the Kaplan-Meier method and log-rank test. A Cox proportional hazards regression analysis was used to determine whether Aurora-B was an independent prognostic factor for breast cancer. We found that Aurora-B expression was correlated with the proliferation index (P < 0.001) and p53 expression (P = 0.014) in breast cancer tissues. Further we found that Aurora-B expression was associated with lymph node metastasis (P = 0.002) and histological grade (P = 0.001). Multivariate analyses indicated that elevated Aurora-B expression predicted a poor survival. In a subgroup of patients that received neoadjuvant chemotherapy, we found that elevated Aurora-B contributed to chemoresistance (P = 0.011). In conclusion, elevated Aurora-B expression in breast cancer patients contributes to chemoresistance and predicts poor prognosis.

  19. Observational properties of dayside throat aurora and implications on the possible generation mechanisms

    NASA Astrophysics Data System (ADS)

    Han, D.-S.; Hietala, H.; Chen, X.-C.; Nishimura, Y.; Lyons, L. R.; Liu, J.-J.; Hu, H.-Q.; Yang, H.-G.

    2017-02-01

    Observational properties of throat aurora are investigated in detail by using 7 year continuous auroral observations obtained at Yellow River Station (magnetic latitude 76.24°N). From our inspection, throat aurora is often observed under the condition of stripy diffuse aurora contacting with the persistent discrete auroral oval, and the long-period throat aurora observations generally consist of intermittent subsequences of throat aurora brightening followed by poleward moving auroral form and throat aurora dimming. We also noticed that the orientation of throat aurora is aligned along the ionospheric convection flow, and its local time distribution shows clear dependence on the interplanetary magnetic field (IMF) By component. These observational results indicate that factors inside the magnetosphere may play important role on occurrence of throat aurora. We thus suggest that throat aurora may present the ionospheric signature of redistribution of reconnection rate on the magnetopause by cold magnetospheric plasma flowing into the reconnection site. In addition, we also found that the occurrence rate of throat aurora clearly decreases with increase of the IMF cone angle (arccos(|Bx|/B)), which is very similar with the occurrence rate of high-speed jet (HSJ) observed in magnetosheath depending on the IMF cone angle. This is suggested as that the HSJs occurred outside the magnetosphere may also play important role for generation of throat aurora by triggering magnetopause reconnection or by direct impacting. Although further studies are needed to clarify how the throat auroras are generated in detail, the relevant observations about throat aurora have presented important implications on a variety open questions, such as distribution and generation of cold plasma structures in the outer magnetosphere, magnetopause deformation, and possible relation between HSJ and reconnection.

  20. Preclinical testing of selective Aurora kinase inhibitors on a medullary thyroid carcinoma-derived cell line.

    PubMed

    Tuccilli, Chiara; Baldini, Enke; Prinzi, Natalie; Morrone, Stefania; Sorrenti, Salvatore; Filippini, Angelo; Catania, Antonio; Alessandrini, Stefania; Rendina, Roberta; Coccaro, Carmela; D'Armiento, Massimino; Ulisse, Salvatore

    2016-05-01

    Deregulated expression of the Aurora kinases (Aurora-A, B, and C) is thought to be involved in cell malignant transformation and genomic instability in several cancer types. Over the last decade, a number of small-molecule inhibitors of Aurora kinases have been developed, which have proved to efficiently restrain malignant cell growth and tumorigenicity. Regarding medullary thyroid carcinoma (MTC), we previously showed the efficacy of a pan-Aurora kinase inhibitor (MK-0457) in impairing growth and survival of the MTC-derived cell line TT. In the present study, we sought to establish if one of the Aurora kinases might represent a preferential target for MTC therapy. The effects of selective inhibitors of Aurora-A (MLN8237) and Aurora-B (AZD1152) were analyzed on TT cell proliferation, apoptosis, cell cycle, and ploidy. The two inhibitors reduced TT cell proliferation in a time- and dose-dependent manner, with IC50 of 19.0 ± 2.4 nM for MLN8237 and 401.6 ± 44.1 nM for AZD1152. Immunofluorescence experiments confirmed that AZD1152 inhibited phosphorylation of histone H3 (Ser10) by Aurora-B, while it did not affect Aurora-A autophosphorylation. MLN8237 inhibited Aurora-A autophosphorylation as expected, but at concentrations required to achieve the maximum antiproliferative effects it also abolished H3 (Ser10) phosphorylation. Cytofluorimetry experiments showed that both inhibitors induced accumulation of cells in G2/M phase and increased the subG0/G1 fraction and polyploidy. Finally, both inhibitors triggered apoptosis. We demonstrated that inhibition of either Aurora-A or Aurora-B has antiproliferative effects on TT cells, and thus it would be worthwhile to further investigate the therapeutical potential of Aurora kinase inhibitors in MTC treatment.

  1. IQGAP1 interacts with Aurora-A and enhances its stability and its role in cancer

    SciTech Connect

    Yin, Ning; Shi, Ji; Wang, Dapeng; Tong, Tong; Wang, Mingrong; Fan, Feiyue; Zhan, Qimin

    2012-04-27

    Highlights: Black-Right-Pointing-Pointer IQGAP1 interacts with Aurora-A through its RGCt domain. Black-Right-Pointing-Pointer Overexpression of IQGAP1 prevents ubiquitination of Aurora-A. Black-Right-Pointing-Pointer Overexpression of IQGAP1 enhances the protein stability of Aurora-A. Black-Right-Pointing-Pointer Overexpression of IQGAP1 promotes the kinase activity of Aurora-A. -- Abstract: IQGAP1, a ubiquitously expressed scaffold protein, has been identified in a wide range of organisms. It participates in multiple aspects of cellular events by binding to and regulating numerous interacting proteins. In our present study, we identified a new IQGAP1 binding protein named Aurora-A which is an oncogenic protein and overexpressed in various types of human tumors. In vitro analysis with GST-Aurora-A fusion proteins showed a physical interaction between Aurora-A and IQGAP1. Moreover, the binding also occurred in HeLa cells as endogenous Aurora-A co-immunoprecipitated with IQGAP1 from the cell lysates. Overexpression of IQGAP1 resulted in an elevation of both expression and activity of Aurora-A kinase. Endogenous IQGAP1 knockdown by siRNA promoted Aurora-A degradation whereas IQGAP1 overexpression enhanced the stability of Aurora-A. Additionally, we documented that the IQGAP1-induced cell proliferation was suppressed by knocking down Aurora-A expression. Taken together, our results showed an unidentified relationship between Aurora-A and IQGAP1, and provided a new insight into the molecular mechanism by which IQGAP1 played a regulatory role in cancer.

  2. Microtubules Accelerate the Kinase Activity of Aurora-B by a Reduction in Dimensionality

    PubMed Central

    Noujaim, Michael; Bechstedt, Susanne; Wieczorek, Michal; Brouhard, Gary J.

    2014-01-01

    Aurora-B is the kinase subunit of the Chromosome Passenger Complex (CPC), a key regulator of mitotic progression that corrects improper kinetochore attachments and establishes the spindle midzone. Recent work has demonstrated that the CPC is a microtubule-associated protein complex and that microtubules are able to activate the CPC by contributing to Aurora-B auto-phosphorylation in trans. Aurora-B activation is thought to occur when the local concentration of Aurora-B is high, as occurs when Aurora-B is enriched at centromeres. It is not clear, however, whether distributed binding to large structures such as microtubules would increase the local concentration of Aurora-B. Here we show that microtubules accelerate the kinase activity of Aurora-B by a “reduction in dimensionality.” We find that microtubules increase the kinase activity of Aurora-B toward microtubule-associated substrates while reducing the phosphorylation levels of substrates not associated to microtubules. Using the single molecule assay for microtubule-associated proteins, we show that a minimal CPC construct binds to microtubules and diffuses in a one-dimensional (1D) random walk. The binding of Aurora-B to microtubules is salt-dependent and requires the C-terminal tails of tubulin, indicating that the interaction is electrostatic. We show that the rate of Aurora-B auto-activation is faster with increasing concentrations of microtubules. Finally, we demonstrate that microtubules lose their ability to stimulate Aurora-B when their C-terminal tails are removed by proteolysis. We propose a model in which microtubules act as scaffolds for the enzymatic activity of Aurora-B. The scaffolding activity of microtubules enables rapid Aurora-B activation and efficient phosphorylation of microtubule-associated substrates. PMID:24498282

  3. The Uranian aurora and its relationship to the magnetosphere

    NASA Technical Reports Server (NTRS)

    Herbert, Floyd; Sandel, B. R.

    1994-01-01

    About 32 h of Voyager Ultraviolet Spectrometer (UVS) observations of Uranus H2 band airglow emission (875 less than or equal to lambda less than or equal to 1115 A) have been analyzed using the singular value decomposition (SVD) approach to inversion, producing an intensity map showing aurora at both magnetic poles. An H Lyman alpha aurora may also be present but is difficult to separate from scattered solar and local interstellar medium components. SVD analysis of variance shows that the intensity estimate is significantly larger than the error estimate over both Uranographic poles and part of the equatorial region, fortuitously including both magnetic polar regions. The Goddard Space Flight Center Q(sub 3) magnetic field model correctly predicts that the aurora should be larger in area and emit more power at the weaker N magnetic pole than at the stronger S magnetic pole. However, the auroral emissions are quite localized in magnetic longitude and so do not form complete auroral ovals. The brightest auroral emission at each magnetic pole is confined to a range of approximately 90 deg of magnetic longitude centered on the magnetotail direction, at moderate magnetic L parameter (5 less than or equal to L less than or equal to 10), but some emission at each pole is distributed over a range of more than 180 deg of longitude. The magnetic longitudes of the aurora are completely inconsistent with the 'windshield wiper' effect for either ions or electrons, indicating that some other effect, such as rapid depletion of the population of precipitating particles of highly localized strong pitch-angle diffusion, may be acting to localize emission. The low apparent L of the precipitating particles indicates that their energies may be less than or equal to 10 keV. Hence magnetospheric convection is likely to be important, and thus particles exciting the aurora may not remain on constant L shells. The precipitating particles may be a relatively low-energy population at high L

  4. The Uranian aurora and its relationship to the magnetosphere

    NASA Astrophysics Data System (ADS)

    Herbert, F.; Sandel, B. R.

    1994-03-01

    About 32 h of Voyager Ultraviolet Spectrometer (UVS) observations of Uranus H2 band airglow emission (875 less than or equal to lambda less than or equal to 1115 A) have been analyzed using the singular value decomposition (SVD) approach to inversion, producing an intensity map showing aurora at both magnetic poles. An H Lyman alpha aurora may also be present but is difficult to separate from scattered solar and local interstellar medium components. SVD analysis of variance shows that the intensity estimate is significantly larger than the error estimate over both Uranographic poles and part of the equatorial region, fortuitously including both magnetic polar regions. The Goddard Space Flight Center Q3 magnetic field model correctly predicts that the aurora should be larger in area and emit more power at the weaker N magnetic pole than at the stronger S magnetic pole. However, the auroral emissions are quite localized in magnetic longitude and so do not form complete auroral ovals. The brightest auroral emission at each magnetic pole is confined to a range of approximately 90 deg of magnetic longitude centered on the magnetotail direction, at moderate magnetic L parameter (5 less than or equal to L less than or equal to 10), but some emission at each pole is distributed over a range of more than 180 deg of longitude. The magnetic longitudes of the aurora are completely inconsistent with the 'windshield wiper' effect for either ions or electrons, indicating that some other effect, such as rapid depletion of the population of precipitating particles of highly localized strong pitch-angle diffusion, may be acting to localize emission. The low apparent L of the precipitating particles indicates that their energies may be less than or equal to 10 keV. Hence magnetospheric convection is likely to be important, and thus particles exciting the aurora may not remain on constant L shells. The precipitating particles may be a relatively low-energy population at high L that is

  5. Synthesis and biological evaluation of 2,4-diaminopyrimidines as selective Aurora A kinase inhibitors.

    PubMed

    Qin, Wen-Wen; Sang, Chun-Yan; Zhang, Lin-Lin; Wei, Wei; Tian, Heng-Zhi; Liu, Huan-Xiang; Chen, Shi-Wu; Hui, Ling

    2015-05-05

    The Aurora kinases are a family of serine/threonine kinases that interact with components of the mitotic apparatus and serve as potential therapeutic targets in oncology. Here we synthesized 15 2,4-diaminopyrimidines and evaluated their biological activities, including antiproliferation, inhibition against Aurora kinases and cell cycle effects. These compounds generally exhibited more potent cytotoxicity against tumor cell lines compared with the VX-680 control, especially compound 11c, which showed the highest cytotoxicities, with IC50 values of 0.5-4.0 μM. Compound 11c had more than 35-fold more selectivity for Aurora A over Aurora B, and molecular docking analysis indicated that compound 11c form better interaction with Aurora A both from the perspective of structure and energy. Furthermore, compound 11c induced G2/M cell cycle arrest in HeLa cells. This series of compounds has the potential for further development as selective Aurora A inhibitors for anticancer activity.

  6. Aurorasaurus: A citizen science platform for viewing and reporting the aurora

    NASA Astrophysics Data System (ADS)

    MacDonald, E. A.; Case, N. A.; Clayton, J. H.; Hall, M. K.; Heavner, M.; Lalone, N.; Patel, K. G.; Tapia, A.

    2015-09-01

    A new, citizen science-based, aurora observing and reporting platform has been developed with the primary aim of collecting auroral observations made by the general public to further improve the modeling of the aurora. In addition, the real-time ability of this platform facilitates the combination of citizen science observations with auroral oval models to improve auroral visibility nowcasting. Aurorasaurus provides easily understandable aurora information, basic gamification, and real-time location-based notification of verified aurora activity to engage citizen scientists. The Aurorasaurus project is one of only a handful of space weather citizen science projects and can provide useful results for the space weather and citizen science communities. Early results are promising with over 2000 registered users submitting over 1000 aurora observations and verifying over 1700 aurora sightings posted on Twitter.

  7. Aurora-A regulates MCRS1 function during mitosis.

    PubMed

    Meunier, Sylvain; Timón, Krystal; Vernos, Isabelle

    2016-07-02

    The mitotic spindle is made of microtubules (MTs) nucleated through different pathways involving the centrosomes, the chromosomes or the walls of pre-existing MTs. MCRS1 is a RanGTP target that specifically associates with the chromosome-driven MTs protecting them from MT depolymerases. MCRS1 is also needed for the control of kinetochore fiber (K-fiber) MT minus-ends dynamics in metaphase. Here, we investigated the regulation of MCRS1 activity in M-phase. We show that MCRS1 is phosphorylated by the Aurora-A kinase in mitosis on Ser35/36. Although this phosphorylation has no role on MCRS1 localization to chromosomal MTs and K-fiber minus-ends, we show that it regulates MCRS1 activity in mitosis. We conclude that Aurora-A activity is particularly important in the tuning of K-fiber minus-ends dynamics in mitosis.

  8. Pulsating aurora induced by upper atmospheric barium releases

    NASA Technical Reports Server (NTRS)

    Deehr, C.; Romick, G.

    1977-01-01

    The paper reports the apparent generation of pulsating aurora by explosive releases of barium vapor near 250 km altitude. This effect occurred only when the explosions were in the path of precipitating electrons associated with the visible aurora. Each explosive charge was a standard 1.5 kg thermite mixture of Ba and CuO with an excess of Ba metal which was vaporized and dispersed by the thermite explosion. Traces of Sr, Na, and Li were added to some of the charges, and monitoring was achieved by ground-based spectrophotometric observations. On March 28, 1976, an increase in emission at 5577 A and at 4278 A was observed in association with the first two bursts, these emissions pulsating with roughly a 10 sec period for approximately 60 to 100 sec after the burst.

  9. Rapid ray motions in barium plasma clouds and auroras

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Swift, D. W.; Wallis, D. D.

    1993-01-01

    On two evenings in 1968, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly through three different Ba(+) clouds over Andoya, Norway. Similar effects were observed in Ba(+) clouds released from rockets launched from Poker Flat, Alaska, on March 21, 1973 and on March 22, 1980. On these occasions, auroras on or near the Ba(+) L shell also exhibited active rapid ray motions, which prompts the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba(+) clouds would lead to a better understanding of the physics of auroral ray motions and the auroral atmosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. The observations provide strong evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions.

  10. Aurora Australis, Spiked and Sinuous Red and Green Airglow

    NASA Image and Video Library

    1991-05-06

    STS039-342-026 (28 April-6 May 1991) --- This view of the Aurora Australis, or Southern Lights, shows a band of airglow above the limb of Earth. Photo experts at NASA studying the mission photography identify the airglow as being in the 80-120 kilometer altitude region and attribute its existence to atomic oxygen (wavelength of 5,577 Angstroms), although other atoms can also contribute. The atomic oxygen airglow is usually most intense at altitudes around 65 degrees north and south latitude, and is most intense in the spring and fall of the year. The aurora phenomena is due to atmospheric oxygen and nitrogen being excited by the particles from the Van Allen Radiation belts which extend between the two geomagnetic poles. The red and green rays appear to extend upward to 200-300 kilometers, much higher than the usual upper limits of about 110 kilometers.

  11. Jupiter's UV Aurora:Energy Input to the Polar Stratosphere

    NASA Astrophysics Data System (ADS)

    Livengood, Timothy A.

    The proposed research will use IUE observations of electron-impact excited H2 emission from the Jovian aurora to investigate the energy input to the polar stratosphere by charged particle precipitation. The effects of the particle precipitation on thermal profile and chemical abundances will be measured using coordinated ground-based observations of polar infrared emissions from atmospheric hydrocarbons. Limb spectra will investigate the partitioning of energy deposition above and below the CH4 homopause at the time of the intensity measurements. A related proposal by Harris et al. will investigate possible localtime dependence which may affect the limb measurements. These observations will be coordinated with other ground-based observers and with HST observations through the International Jupiter Watch. Spectra acquired in this program will be included in our database of previous observations to contribute to investigations of long-term trends in auroral activity and investigations of magnetospheric phenomena controlling the aurora.

  12. Rapid ray motions in barium plasma clouds and auroras

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Swift, D. W.; Wallis, D. D.

    1993-01-01

    On two evenings in 1968, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly through three different Ba(+) clouds over Andoya, Norway. Similar effects were observed in Ba(+) clouds released from rockets launched from Poker Flat, Alaska, on March 21, 1973 and on March 22, 1980. On these occasions, auroras on or near the Ba(+) L shell also exhibited active rapid ray motions, which prompts the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba(+) clouds would lead to a better understanding of the physics of auroral ray motions and the auroral atmosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. The observations provide strong evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions.

  13. Red Aurora as Seen From the International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Auroras are caused when high-energy electrons pour down from the Earth's magnetosphere and collide with atoms. Red aurora, as captured here by a still digital camera aboard the International Space Station (ISS), occurs from 200 km to as high as 500 km altitude and is caused by the emission of 6300 Angstrom wavelength light from oxygen atoms. The light is emitted when the atoms return to their original unexcited state. The white spot in the image is from a light on inside of the ISS that is reflected off the inside of the window. The pale blue arch on the left side of the frame is sunlight reflecting off the atmospheric limb of the Earth. At times of peaks in solar activity, there are more geomagnetic storms and this increases the auroral activity viewed on Earth and by astronauts from orbit.

  14. Using the Aurora to Remote Sense Near-Earth Space

    NASA Astrophysics Data System (ADS)

    Donovan, Eric

    2012-10-01

    The Earth's magnetosphere is formed by the interaction of the solar wind and Earth's magnetic field. Sitting like a giant wind sock in the solar wind, the magnetosphere is an enormous and dynamic region. The processes at work within the magnetosphere serve as exemplars of phenomena that happen throughout the cosmos, and have consequences in the upper atmosphere. One of those is the aurora, a truly global and multi-scale phenomenon that we are only beginning to understand. Of all the countries on Earth, Canada has the largest region of land under the auroral zone, something Canadian scientists have capitalized on for more than fifty years. In this talk, I will outline how we use observations of the aurora to remote sense the magnetosphere, focusing on Canadian ground-based and space-based programs that provide remarkable images of this beautiful natural phenomenon.

  15. Response of dayside aurora on closed field lines to solar wind driving

    NASA Astrophysics Data System (ADS)

    Wang, B.; Nishimura, T.; Han, D.; Bortnik, J.; Li, W.; Lyons, L. R.; Angelopoulos, V.; Ebihara, Y.

    2016-12-01

    Diffuse aurora and throat aurora are two major forms of aurora that are observed equatorward of the dayside discrete auroral oval on closed field lines. Dayside diffuse aurora is driven by pitch angle scattering of energetic electrons in the dayside magnetosphere by whistler mode waves, and often show transient brightenings. Throat aurora is transient discrete auroral brightening in the dayside region with roughly north-south orientation, extending equatorward of the discrete auroral oval. Throat aurora is associated with enhanced precipitation of low-energy electrons with 100 eV. However, the magnetospheric signatures and the upstream drivers of these localized aurora variations are still open questions. With conjunction observations by multiple Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites (TH-A, TH-B, TH-C, TH-D, TH-E) and South Pole station all-sky imager (ASI), 4 cases of auroral brightenings (2 diffuse aurora and 2 throat aurora) are identified on Jun. 25th, 2008. In 2 diffuse aurora brightening cases, foreshock ions are found to have a roughly one-to-one relation with brightenings of diffuse auroral intensity. Simultaneously, the localized magnetopause compression signatures and magnetosheath particle penetration are observed around those brightening times, indicating localized magnetosphere compression by foreshock effects and magnetosheath particle penetration to dayside outer magnetosphere for driving diffuse auroral brightening. In the 2 cases with throat aurora, pulses of low-energy ions flowing earthward were found in the dayside magnetosphere, and FTE-like signatures were found in the magnetosheath. These connections suggest that throat aurora reflects transient and localized reconnection, magnetosheath particle penetration, and flow burst.

  16. The Aurora at Quiet Magnetospheric Conditions: Repeatability and Dipole Tilt Angle Dependence

    DTIC Science & Technology

    1993-03-01

    A tial to variation of the dipole tilt angle. Wu et al. [1991] images of the aurora borealis obtained by Polar BEAR at studied the substorm westward... Aurora at Quiet Magnetospheric Conditions: SRepeatability and Dipole Tilt Angle Dependence PE 62101F _PR 4643 6. AUTHCR(S) TA 11 I. Oznovich*, R.W...tilt angle at quiet magnetospheric conditions? In order to address these questions, northern hemisphere images of the aurora at 1356 A, obtained by

  17. Character of the correlation between the geographic distribution of auroras and the anomalous geomagnetic field

    NASA Astrophysics Data System (ADS)

    Degtiarev, V. I.; Nadubovich, Iu. A.; Platonov, O. I.; Shumilova, N. A.; Mishurinskii, B. E.

    1987-06-01

    Photographic measurements obtained on Taimyr and in the Iakutsk region are used in a statistical correlation of the distributions of the relative occurrence probability of auroras along the auroral zone and the magnitude of the anomalous geomagnetic field (AGF). A negative correlation between the AGF and the geographic distribution of auroras is established. Using topside sounding data, the characteristic dimensions of ionospheric irregularities in the auroral zone are determined which coincide with the regional scale of aurora distribution.

  18. Altitude of Mars aurorae deduced from SPICAM limb detections

    NASA Astrophysics Data System (ADS)

    Soret, L.; Gérard, J.-C.; Libert, L.; Shematovich, V. I.; Bisikalo, D. V.; Stiepen, A.; Bertaux, J.-L.

    2015-10-01

    Martian aurorae have been detected with the SPICAM instrument on board Mars Express both in the nadir and the limb viewing modes. In this study, we focus on three limb detections to determine the altitudes of the auroral emissions and their intensities.We then use a model of electron transport in the Martian thermosphere based on a Monte-Carlo method to simulate and to understand the excitation processes leading to these auroral emissions.

  19. Abscission checkpoint control: stuck in the middle with Aurora B.

    PubMed

    Carmena, Mar

    2012-07-01

    At the end of cell division, the cytoplasmic bridge joining the daughter cells is severed through a process that involves scission of the plasma membrane. The presence of chromatin bridges 'stuck' in the division plane is sensed by the chromosomal passenger complex (CPC) component Aurora B kinase, triggering a checkpoint that delays abscission until the chromatin bridges have been resolved. Recent work has started to shed some light on the molecular mechanism by which the CPC controls the timing of abscission.

  20. Aurora Australis, Spiked and Sinuous Red and Green Airglow

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the Aurora Australis or Southern Lights, in the 80 - 120 km altitude region, (location unknown) shows a spiked and sinuous band of red and green airglow above the Earth Limb and a charged plasma glow around the orbiter. Auroral activity is due to exitation of atomic oxygen in the upper atmosphere by the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  1. Aurora Australis, Spiked and Sinuous Red and Green Airglow

    NASA Technical Reports Server (NTRS)

    1991-01-01

    In This distant view of the Aurora Australis or Southern Lights (location unknown), a spiked and sinuous band of red and green airglow above the Earth Limb is highlighted by moonglow. Auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  2. A short dive into the complexity of Jupiter's aurorae - invited

    NASA Astrophysics Data System (ADS)

    Bonfond, Bertrand

    2015-04-01

    Aurorae are the atmospheric signatures of energetic processes taking place far in the magnetosphere. One of the most important results brought by high resolution imaging of the UV aurorae at Jupiter is the realization that there isn't such a thing as «the aurora» at Jupiter; as these light emissions appear to arise from a variety of processes. Some are related to the interaction of the magnetospheric plasma with the moons (the satellite footprints). Others are linked with the radial motion of flux tubes through centrifugal instabilities (the injection auroral signatures). Some diffuse emissions are connected with wave-particle interaction (the equatorward diffuse emissions). Another feature is associated with the magnetosphere-ionosphere coupling (the main emission/oval). Some auroral spots are related to internally driven reconnection (the polar dawn spots). Finally, the polar-most emissions remain to be understood and this list is still incomplete. In order to illustrate the discrepancies between these various features, I will show a set of recent results derived from the analysis of Hubble Space Telescope observations. For example, I will compare the vertical profile of satellite footprints and the main emissions, and show that the energy population of the precipitating particles varies from feature to feature. Moreover, even within a single feature, spatial variations do exist. As an example, I will characterize the dawn-dusk brightness discrepancy of the main emissions and discuss its implication regarding the magnetospheric currents. And finally, the dynamics of the features also helps differentiating one type of aurora from another. This will be shown through the description of the morphological evolution of the transient flares in the polar region.

  3. Aurora Australis, Spiked and Sinuous Red and Green Airglow

    NASA Technical Reports Server (NTRS)

    1991-01-01

    In This distant view of the Aurora Australis or Southern Lights (location unknown), a spiked and sinuous band of red and green airglow above the Earth Limb is highlighted by moonglow. Auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  4. Aurora Australis, Spiked and Sinuous Red and Green Airglow

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the Aurora Australis or Southern Lights, in the 80 - 120 km altitude region, (location unknown) shows a spiked and sinuous band of red and green airglow above the Earth Limb and a charged plasma glow around the orbiter. Auroral activity is due to exitation of atomic oxygen in the upper atmosphere by the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  5. Aurora Australis view taken by the Expedition 29 crew

    NASA Image and Video Library

    2011-09-17

    ISS029-E-008433 (17 Sept. 2011) --- This is one of a series of night time images photographed by one of the Expedition 29 crew members from the International Space Station. It features Aurora Australis, seen from a point over the southeast Tasman Sea near southern New Zealand. The station was located at 46.65 degrees south latitude and 169.10 degrees east longitude.

  6. Aurora Astralis taken by the Expedition Seven crew

    NASA Image and Video Library

    2003-06-03

    ISS007-E-06077 (3 June 2003) --- This view featuring the Aurora Australis or “southern lights” was photographed by astronaut Edward T. Lu, Expedition 7 NASA ISS science officer and flight engineer aboard the International Space Station (ISS). When this was taken, the Station was in a position over the Indian Ocean, southwest of Australia. The four stars hanging above Earth’s limb are the brightest stars of the southern constellation Corvus.

  7. Regulation and Function of the Ipl1/Aurora Kinase

    DTIC Science & Technology

    2004-05-01

    S., et al., The Budding Yeast Iplip/Aurora Protein Kinase Regulates Mitotic Spindle Disassembly. I. Cell Biol., 2003. 160: 329-339. 9. Desai, A., et...Two Sacchromyces cerevisiae kinesin-related gene-products required for mitotic spindle assembly. J. Cell Biol., 1992. 118:109-120 9 Appendix Training ...destabilizing kinesin, are delayed in spindle breakdown similar to ipll mutants. It is possible that Ipllp regulates spindle breakdown by directly regulating

  8. Planetary protection in the framework of the Aurora exploration program

    NASA Astrophysics Data System (ADS)

    Kminek, G.

    The Aurora Exploration Program will give ESA new responsibilities in the field of planetary protection. Until now, ESA had only limited exposure to planetary protection from its own missions. With the proposed ExoMars and MSR missions, however, ESA will enter the realm of the highest planetary protection categories. As a consequence, the Aurora Exploration Program has initiated a number of activities in the field of planetary protection. The first and most important step was to establish a Planetary Protection Working Group (PPWG) that is advising the Exploration Program Advisory Committee (EPAC) on all matters concerning planetary protection. The main task of the PPWG is to provide recommendations regarding: Planetary protection for robotic missions to Mars; Planetary protection for a potential human mission to Mars; Review/evaluate standards & procedures for planetary protection; Identify research needs in the field of planetary protection. As a result of the PPWG deliberations, a number of activities have been initiated: Evaluation of the Microbial Diversity in SC Facilities; Working paper on legal issues of planetary protection and astrobiology; Feasibility study on a Mars Sample Return Containment Facility; Research activities on sterilization procedures; Training course on planetary protection (May, 2004); Workshop on sterilization techniques (fall 2004). In parallel to the PPWG, the Aurora Exploration Program has established an Ethical Working Group (EWG). This working group will address ethical issues related to astrobiology, planetary protection, and manned interplanetary missions. The recommendations of the working groups and the results of the R&D activities form the basis for defining planetary protection specification for Aurora mission studies, and for proposing modification and new inputs to the COSPAR planetary protection policy. Close cooperation and free exchange of relevant information with the NASA planetary protection program is strongly

  9. Evolutionary relationships of Aurora kinases: Implications for model organism studies and the development of anti-cancer drugs

    PubMed Central

    Brown, James R; Koretke, Kristin K; Birkeland, Marian L; Sanseau, Philippe; Patrick, Denis R

    2004-01-01

    Background As key regulators of mitotic chromosome segregation, the Aurora family of serine/threonine kinases play an important role in cell division. Abnormalities in Aurora kinases have been strongly linked with cancer, which has lead to the recent development of new classes of anti-cancer drugs that specifically target the ATP-binding domain of these kinases. From an evolutionary perspective, the species distribution of the Aurora kinase family is complex. Mammals uniquely have three Aurora kinases, Aurora-A, Aurora-B, and Aurora-C, while for other metazoans, including the frog, fruitfly and nematode, only Aurora-A and Aurora-B kinases are known. The fungi have a single Aurora-like homolog. Based on the tacit assumption of orthology to human counterparts, model organism studies have been central to the functional characterization of Aurora kinases. However, the ortholog and paralog relationships of these kinases across various species have not been rigorously examined. Here, we present comprehensive evolutionary analyses of the Aurora kinase family. Results Phylogenetic trees suggest that all three vertebrate Auroras evolved from a single urochordate ancestor. Specifically, Aurora-A is an orthologous lineage in cold-blooded vertebrates and mammals, while structurally similar Aurora-B and Aurora-C evolved more recently in mammals from a duplication of an ancestral Aurora-B/C gene found in cold-blooded vertebrates. All so-called Aurora-A and Aurora-B kinases of non-chordates are ancestral to the clade of chordate Auroras and, therefore, are not strictly orthologous to vertebrate counterparts. Comparisons of human Aurora-B and Aurora-C sequences to the resolved 3D structure of human Aurora-A lends further support to the evolutionary scenario that vertebrate Aurora-B and Aurora-C are closely related paralogs. Of the 26 residues lining the ATP-binding active site, only three were variant and all were specific to Aurora-A. Conclusions In this study, we found that

  10. Is Diffuse Aurora Driven from Above or Below?

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Sibeck, D. G.; Zesta, E.

    2017-01-01

    Abstract In the diffuse aurora, magnetospheric electrons, initially precipitated from the inner plasma sheet via wave-particle interaction processes, degrade in the atmosphere toward lower energies, and produce secondary electrons via impact ionization of the neutral atmosphere. These initially precipitating electrons of magnetospheric origin can also be additionally reflected back into the magnetosphere, leading to a series of multiple reactions by the two magnetically conjugate atmospheres that can greatly impact the initially precipitating flux at the upper ionospheric boundary (700-800 km). The resultant population of secondary and primary electrons cascades toward lower energies and escape back to the magnetosphere. Escaping upward electrons traveling from the ionosphere can be trapped in the magnetosphere, as they travel inside the loss cone, via Coulomb collisions with the cold plasma, or by interactions with various plasma waves. Even though this scenario is intuitively transparent, this magnetosphere-ionosphere coupling element is not considered in any of the existing diffuse aurora research. Nevertheless, as we demonstrate in this letter, this process has the potential to dramatically affect the formation of electron precipitated fluxes in the regions of diffuse auroras.

  11. Juno/JIRAM infrared observations of Jupiter Aurorae

    NASA Astrophysics Data System (ADS)

    Mura, Alessandro; Adriani, Alberto; Altieri, Francesca; Dinelli, Bianca Maria; Moriconi, Maria Luisa; Migliorini, Alessandra; Bolton, Scott J.; Connerney, Jack E. P.; Atreya, Sushil; Bagenal, Fran; Gladstone, Randy; Hansen-Koharcheck, Candy; Kurth, William S.; Levin, Steven M.; Lunine, Jonathan; Mauk, Barry H.; McComas, David J.; Amoroso, Marilena

    2017-04-01

    The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer to study the jovian aurorae on board the NASA mission Juno. Jupiter's aurorae, the most powerful among the planets in the Solar System, are the results of high-energy electrons falling along the planet's magnetic field lines into the upper atmosphere, exciting the atmospheric gases, which then emit at different wavelengths. JIRAM, specifically, is designed to observe the intense emission of H3+, which is mainly possible in a spectral interval (3.2 to 4.0 μm) where the solar and thermal radiance emitted by the planet is very low due to intense atmospheric methane absorption band, resulting in high auroral contrast against Jupiter's dark disk. Hence, JIRAM is composed of two IR imager channels and one spectrometer in the range 2-5 um, with a spectral resolution of less than 10 nm and surface resolution as low as 50 km. One of the two imager channels is centered at 3.455 μm (in the H3+ emission region), to give a context information of auroral emission, for better understanding the spectrometer detailed measurement. In this presentation we show latest results on JIRAM's observations of the H3+ infrared emission. Taking advantage of optimal point of view given by the polar orbit of the Juno spacecraft, these observations provide spatial, spectral and temporal distribution of the Jovian auroras; the footprints of Io, Europa and Ganymede are also observed and studied.

  12. Fine-scale transient arcs seen in a shock aurora

    NASA Astrophysics Data System (ADS)

    Motoba, T.; Ebihara, Y.; Kadokura, A.; Weatherwax, A. T.

    2014-08-01

    We report, for the first time, fine-scale transient arcs that emerged successively within the initial 1-2 min evolutionary interval of a postnoon shock aurora on 14 July 2012. Data were acquired from ~2 Hz temporal resolution imaging of dayside aurora with a white light all-sky camera (ASC) at South Pole Station (magnetic latitude = -74.3°, magnetic local time = UT -3.5 h). Just after 1809:50 UT at which the initial response to an interplanetary (IP) shock was detected in the postnoon geosynchronous magnetic field, the ASC observed three successive transient arcs of which the locations shifted equatorward with an abrupt jump by ~0.2° in latitude. All of the transient arcs occurred in a closed field line region, ~1.0°-1.5° equatorward of the polar cap or open/closed field line boundary inferred from the intensity ratio of I630.0/I557.7 but just poleward of the shock-induced proton and diffuse-type electron aurorae. Each of the transient arcs had a latitudinal width of ~0.1° and a short lifetime of ~20-30 s. Although the obvious mechanism has still remained unclear, possible interpretations of the fine-scale transient arc features are discussed in terms of a local process of each of the magnetospheric origin (mode conversion) and ionospheric origin (feedback interaction) that may be induced by IP shock.

  13. Is diffuse aurora driven from above or below?

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Sibeck, D. G.; Zesta, E.

    2017-01-01

    In the diffuse aurora, magnetospheric electrons, initially precipitated from the inner plasma sheet via wave-particle interaction processes, degrade in the atmosphere toward lower energies, and produce secondary electrons via impact ionization of the neutral atmosphere. These initially precipitating electrons of magnetospheric origin can also be additionally reflected back into the magnetosphere, leading to a series of multiple reflections by the two magnetically conjugate atmospheres that can greatly impact the initially precipitating flux at the upper ionospheric boundary (700-800 km). The resultant population of secondary and primary electrons cascades toward lower energies and escape back to the magnetosphere. Escaping upward electrons traveling from the ionosphere can be trapped in the magnetosphere, as they travel inside the loss cone, via Coulomb collisions with the cold plasma, or by interactions with various plasma waves. Even though this scenario is intuitively transparent, this magnetosphere-ionosphere coupling element is not considered in any of the existing diffuse aurora research. Nevertheless, as we demonstrate in this letter, this process has the potential to dramatically affect the formation of electron precipitated fluxes in the regions of diffuse auroras.

  14. Aurora kinase inhibition induces PUMA via NF-κB to kill colon cancer cells.

    PubMed

    Sun, Jing; Knickelbein, Kyle; He, Kan; Chen, Dongshi; Dudgeon, Crissy; Shu, Yongqian; Yu, Jian; Zhang, Lin

    2014-05-01

    Aurora kinases play a key role in mitosis and are frequently overexpressed in a variety of tumor cells. Inhibition of aurora kinases results in mitotic arrest and death of cancer cells, and has been explored as an anticancer strategy. However, how aurora inhibition kills cancer cells is poorly understood. In this study, we found that inhibition of aurora kinases by siRNA or small-molecule inhibitors led to induction of p53 upregulated modulator of apoptosis (PUMA), a BH3-only Bcl-2 family protein, in colorectal cancer cells irrespective of p53 status. Deficiency in PUMA increased polyploidy, improved cell survival, and abrogated mitochondria-mediated apoptosis induced by aurora kinase inhibitors. In response to aurora kinase inhibition, PUMA was directly activated by p65 through the canonical NF-κB pathway following AKT inhibition. Furthermore, PUMA was necessary for the chemosensitization and in vivo antitumor effects of aurora kinase inhibitors in colon cancer cells. These results suggest that PUMA induction mediates the apoptotic response to mitotic arrest imposed by aurora kinase inhibition, and may be a useful indicator for the anticancer activity of aurora kinase inhibitors.

  15. Earliest datable records of aurora-like phenomena in the astronomical diaries from Babylonia

    NASA Astrophysics Data System (ADS)

    Hayakawa, Hisashi; Mitsuma, Yasuyuki; Ebihara, Yusuke; Kawamura, Akito Davis; Miyahara, Hiroko; Tamazawa, Harufumi; Isobe, Hiroaki

    2016-11-01

    The astronomical diaries from Babylonia (ADB) are excellent sources of information of natural phenomena, including astronomical ones, in pre-Christ era because it contains the record of highly continuous and systematic observations. In this article, we present results of a survey of aurora-like phenomena in ADB, spanning from BCE 652 to BCE 61. We have found nine records of aurora-like phenomena. Philological and scientific examinations suggest that five of them can be considered as likely candidate for aurora observations. They provide unique information about the solar and aurora activities in the first millennium BCE. [Figure not available: see fulltext.

  16. Ancient writings reveal presence of aurora in 13th-century Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Silverman, Sam

    Modern Norway, Iceland, and Greenland are subject to frequent displays of the aurora borealis. The aurora can be viewed on almost every clear night in the northern part of Iceland and southern Greenland, which lie in or near the auroral oval. Thus, it is surprising to find almost no mention of the aurora in medieval Norse chronicles or in the extensive Icelandic saga literature. Only one paragraph, in the "King's Mirror," a Norwegian writing dating to about 1250 C.E., notes the occurrence of the aurora in Greenland. The author reports this as hearsay and not from personal knowledge. For a fuller discussion of the Norse literature, see Brekke and Egeland [1983].

  17. The Ska complex promotes Aurora B activity to ensure chromosome biorientation.

    PubMed

    Redli, Patrick M; Gasic, Ivana; Meraldi, Patrick; Nigg, Erich A; Santamaria, Anna

    2016-10-10

    Chromosome biorientation and accurate segregation rely on the plasticity of kinetochore-microtubule (KT-MT) attachments. Aurora B facilitates KT-MT dynamics by phosphorylating kinetochore proteins that are critical for KT-MT interactions. Among the substrates whose microtubule and kinetochore binding is curtailed by Aurora B is the spindle and kinetochore-associated (Ska) complex, a key factor for KT-MT stability. Here, we show that Ska is not only a substrate of Aurora B, but is also required for Aurora B activity. Ska-deficient cells fail to biorient and display chromosome segregation errors underlying suppressed KT-MT turnover. These defects coincide with KNL1-Mis12-Ndc80 network hypophosphorylation, reduced mitotic centromere-associated kinesin localization, and Aurora B T-loop phosphorylation at kinetochores. We further show that Ska requires its microtubule-binding capability to promote Aurora B activity in cells and stimulates Aurora B catalytic activity in vitro. Finally, we show that protein phosphatase 1 counteracts Aurora B activity to enable Ska kinetochore accumulation once biorientation is achieved. We propose that Ska promotes Aurora B activity to limit its own microtubule and kinetochore association and to ensure that KT-MT dynamics and stability fall within an optimal balance for biorientation.

  18. Earliest datable records of aurora-like phenomena in the astronomical diaries from Babylonia.

    PubMed

    Hayakawa, Hisashi; Mitsuma, Yasuyuki; Ebihara, Yusuke; Kawamura, Akito Davis; Miyahara, Hiroko; Tamazawa, Harufumi; Isobe, Hiroaki

    2016-01-01

    The astronomical diaries from Babylonia (ADB) are excellent sources of information of natural phenomena, including astronomical ones, in pre-Christ era because it contains the record of highly continuous and systematic observations. In this article, we present results of a survey of aurora-like phenomena in ADB, spanning from BCE 652 to BCE 61. We have found nine records of aurora-like phenomena. Philological and scientific examinations suggest that five of them can be considered as likely candidate for aurora observations. They provide unique information about the solar and aurora activities in the first millennium BCE. Graphical abstract.

  19. Phosphorylation of MAP65-1 by Arabidopsis Aurora Kinases Is Required for Efficient Cell Cycle Progression1[OPEN

    PubMed Central

    Weimer, Annika K.; Stoppin-Mellet, Virginie; Kosetsu, Ken; Cedeño, Cesyen; Jaquinod, Michel; Njo, Maria; De Milde, Liesbeth; Tompa, Peter; Inzé, Dirk; Beeckman, Tom; Vantard, Marylin

    2017-01-01

    Aurora kinases are key effectors of mitosis. Plant Auroras are functionally divided into two clades. The alpha Auroras (Aurora1 and Aurora2) associate with the spindle and the cell plate and are implicated in controlling formative divisions throughout plant development. The beta Aurora (Aurora3) localizes to centromeres and likely functions in chromosome separation. In contrast to the wealth of data available on the role of Aurora in other kingdoms, knowledge on their function in plants is merely emerging. This is exemplified by the fact that only histone H3 and the plant homolog of TPX2 have been identified as Aurora substrates in plants. Here we provide biochemical, genetic, and cell biological evidence that the microtubule-bundling protein MAP65-1—a member of the MAP65/Ase1/PRC1 protein family, implicated in central spindle formation and cytokinesis in animals, yeasts, and plants—is a genuine substrate of alpha Aurora kinases. MAP65-1 interacts with Aurora1 in vivo and is phosphorylated on two residues at its unfolded tail domain. Its overexpression and down-regulation antagonistically affect the alpha Aurora double mutant phenotypes. Phospho-mutant analysis shows that Aurora contributes to the microtubule bundling capacity of MAP65-1 in concert with other mitotic kinases. PMID:27879390

  20. Phosphorylation of MAP65-1 by Arabidopsis Aurora Kinases Is Required for Efficient Cell Cycle Progression.

    PubMed

    Boruc, Joanna; Weimer, Annika K; Stoppin-Mellet, Virginie; Mylle, Evelien; Kosetsu, Ken; Cedeño, Cesyen; Jaquinod, Michel; Njo, Maria; De Milde, Liesbeth; Tompa, Peter; Gonzalez, Nathalie; Inzé, Dirk; Beeckman, Tom; Vantard, Marylin; Van Damme, Daniël

    2017-01-01

    Aurora kinases are key effectors of mitosis. Plant Auroras are functionally divided into two clades. The alpha Auroras (Aurora1 and Aurora2) associate with the spindle and the cell plate and are implicated in controlling formative divisions throughout plant development. The beta Aurora (Aurora3) localizes to centromeres and likely functions in chromosome separation. In contrast to the wealth of data available on the role of Aurora in other kingdoms, knowledge on their function in plants is merely emerging. This is exemplified by the fact that only histone H3 and the plant homolog of TPX2 have been identified as Aurora substrates in plants. Here we provide biochemical, genetic, and cell biological evidence that the microtubule-bundling protein MAP65-1-a member of the MAP65/Ase1/PRC1 protein family, implicated in central spindle formation and cytokinesis in animals, yeasts, and plants-is a genuine substrate of alpha Aurora kinases. MAP65-1 interacts with Aurora1 in vivo and is phosphorylated on two residues at its unfolded tail domain. Its overexpression and down-regulation antagonistically affect the alpha Aurora double mutant phenotypes. Phospho-mutant analysis shows that Aurora contributes to the microtubule bundling capacity of MAP65-1 in concert with other mitotic kinases. © 2017 American Society of Plant Biologists. All Rights Reserved.

  1. Non-conjugate aurora and inter hemispheric currents

    NASA Astrophysics Data System (ADS)

    Reistad, J. P.; Østgaard, N.; Laundal, K. M.; Oksavik, K.

    2012-04-01

    We look at large scale auroral features using global imagers to obtain simultaneous pictures of both the southern and northern auroral ovals in the ultra violet part of the spectra. During the years 2001 and 2002 the IMAGE satellite was in a favourable position for imaging the aurora borealis (Northern Hemisphere) and the POLAR satellite with its large field-of-view VIS Earth camera had a sporadic coverage of the aurora australis (Southern Hemisphere). In total 19 hours of simultaneous global imaging from different seasons are analysed searching for non-conjugacy in the night side sector. By non-conjugate aurora we mean auroral features appearing in one hemisphere only, or significant differences in intensity between the hemispheres for the same auroral feature. We suggest that our observed large scale asymmetries can be explained in terms of inter hemispheric currents (IHC). Coherent with our earlier findings, we list three possible candidates for producing such inter hemispheric currents based on observations. 1) Hemispherical differences in the solar wind dynamo due to IMF Bx and tilt angle producing different strength of region 1 currents in the conjugate he mispheres, 2) Hemispherical differences in conductivity controlled by the tilt angle only giving rise to IHC on closed field lines, and 3) Field-aligned current components induced by the penetration of the IMF By into the closed magnetosphere. Most of the observed non-conjugate aurora in our dataset can be explained by these candidates only. The IMF By penetration candidate is considered closer. We search for evidence in our data that IMF By < 0 (By > 0) can induce an IHC producing stronger aurora on the polar boundary in the Northern (Southern) Hemisphere. Also a second IHC component are predicted from the theory, mapping to the equatorward part of the oval and opposite directed along the magnetic field lines. Using a much larger dataset for one hemisphere only, we show whether these predicted currents can

  2. Urban Air Quality Modelling with AURORA: Prague and Bratislava

    NASA Astrophysics Data System (ADS)

    Veldeman, N.; Viaene, P.; De Ridder, K.; Peelaerts, W.; Lauwaet, D.; Muhammad, N.; Blyth, L.

    2012-04-01

    The European Commission, in its strategy to protect the health of the European citizens, states that in order to assess the impact of air pollution on public health, information on long-term exposure to air pollution should be available. Currently, indicators of air quality are often being generated using measured pollutant concentrations. While air quality monitoring stations data provide accurate time series information at specific locations, air quality models have the advantage of being able to assess the spatial variability of air quality (for different resolutions) and predict air quality in the future based on different scenarios. When running such air quality models at a high spatial and temporal resolution, one can simulate the actual situation as closely as possible, allowing for a detailed assessment of the risk of exposure to citizens from different pollutants. AURORA (Air quality modelling in Urban Regions using an Optimal Resolution Approach), a prognostic 3-dimensional Eulerian chemistry-transport model, is designed to simulate urban- to regional-scale atmospheric pollutant concentration and exposure fields. The AURORA model also allows to calculate the impact of changes in land use (e.g. planting of trees) or of emission reduction scenario's on air quality. AURORA is currently being applied within the ESA atmospheric GMES service, PASODOBLE (http://www.myair-eu.org), that delivers information on air quality, greenhouse gases, stratospheric ozone, … At present there are two operational AURORA services within PASODOBLE. Within the "Air quality forecast service" VITO delivers daily air quality forecasts for Belgium at a resolution of 5 km and for the major Belgian cities: Brussels, Ghent, Antwerp, Liege and Charleroi. Furthermore forecast services are provided for Prague, Czech Republic and Bratislava, Slovakia, both at a resolution of 1 km. The "Urban/regional air quality assessment service" provides urban- and regional-scale maps (hourly resolution

  3. Jupiter Night-Side Auroras, North and South

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Oval-shaped auroras glow in night-side areas near Jupiter's north and south poles in these images taken by NASA's Cassini spacecraft on Jan. 13, 2001. The lower frame is the first to capture the southern aurora on the planet's night side. Blue lines of longitude and latitude have been added in each frame to indicate position of the glows.

    Jupiter's auroral ovals are similar to Earth's auroras, often called the northern lights or southern lights, although fluctuations in solar activity play a more important role in the auroras at Earth than at Jupiter. Energetic particles are constantly streaming towards Jupiter on magnetic field lines that intersect the planet's atmosphere on a ring around the magnetic pole. Where the energetic particles hit the upper atmosphere, they cause emission of light, similar to the glow in a fluorescent bulb. In the north (upper image), the magnetic pole is offset from the rotational pole, which is where the blue longitude lines converge, just to the left of the imaged area. The auroral oval appears like a draped necklace that is carried around by the rotation of the planet. In the south (lower image), the magnetic and rotational poles are nearly coincident, so no significant offset is visible.

    Cassini had passed its closest to Jupiter about two weeks before taking these pictures, so it was in position to see the night side of the planet. It was about 16.5 million kilometers (10.3 million miles) from the planet and about 2.5 degrees below the plane of Jupiter's equator. The smallest features visible are about 100 kilometers (about 60 miles) across. The images were taken by Cassini's narrow-band camera through a filter centered on a light-wave frequency at which hydrogen emits light when it is excited. They have been processed to remove scattered light from the overexposed sunlit crescent of the planet. Hydrogen is a major ingredient of Jupiter's atmosphere.

    It is not understood why the auroral oval rings are so thin. Cassini

  4. AURORA on MEGSAT 1: a photon counting observatory for the Earth UV night-sky background and Aurora emission

    NASA Astrophysics Data System (ADS)

    Monfardini, A.; Trampus, P.; Stalio, R.; Mahne, N.; Battiston, R.; Menichelli, M.; Mazzinghi, P.

    2001-08-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed ``Notte'' and the Aurora emission with ``Alba''. AURORA, this is the name of the experiment, will determine, with the ``Notte'' channel, the overall night-side photon background in the 300-400nm spectral range, together with a particular 2+N2 line (λc=337nm). The ``Alba'' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6nm) centered on: 367nm (continuum evaluation), 391nm (1-N+2), 535nm (continuum evaluation), 560nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 ``Satan'' rocket. The satellite orbit is nearly circular (hapogee=648km, /e=0.0022), and the inclination of the orbital plane is 64.56°. An overview of the techniques adopted is given in this paper.

  5. Host-defense peptides isolated from the skin secretions of the Northern red-legged frog Rana aurora aurora.

    PubMed

    Conlon, J Michael; Sonnevend, Agnes; Davidson, Carlos; Demandt, Anni; Jouenne, Thierry

    2005-01-01

    Antimicrobial peptides in the skin secretions of anurans constitute a component of the innate immunity that protects the organism against invading pathogens. Four peptides with antimicrobial activity were isolated in high yield from norepinephrine-stimulated skin secretions of the Northern red-legged frog Rana aurora aurora and their primary structures determined. Ranatuerin-2AUa (GILSSFKGVAKGVAKNLAGKLLDELKCKITGC) showed potent growth-inhibitory activity against a range of Gram-positive and Gram-negative bacteria (minimum inhibitory concentrations < 20 microM) but low hemolytic activity against human erythrocytes (50% hemolysis at 290 microM). Brevinin-1AUa (FLPILAGLAAKLVPKVFCSITKKC) and brevinin-1AUb (FLPILAGLAANILPKVFCSITKKC) also showed potent antimicrobial activity but were strongly hemolytic (HC50 < 10 microM). Temporin-1AUa (FLPIIGQLLSGLL.NH2) atypically lacked a basic amino acid residue and showed very weak antimicrobial and hemolytic activity. Its biological function remains to be established. The primary structures of the antimicrobial peptides are consistent with a close phylogenetic relationship between R. aurora, Rana boylii and Rana luteiventris. Copyright 2004 Elsevier Ltd.

  6. Auroras over North America as Seen from Space

    NASA Image and Video Library

    2017-09-27

    Overnight on October 4-5, 2012, a mass of energetic particles from the atmosphere of the Sun were flung out into space, a phenomenon known as a coronal mass ejection. Three days later, the storm from the Sun stirred up the magnetic field around Earth and produced gorgeous displays of northern lights. NASA satellites track such storms from their origin to their crossing of interplanetary space to their arrival in the atmosphere of Earth. Using the “day-night band” (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS), the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite acquired this view of the aurora borealis early on the morning of October 8, 2012. The northern lights stretch across Canada’s Quebec and Ontario provinces in the image, and are part of the auroral oval that expanded to middle latitudes because of a geomagnetic storm. The DNB sensor detects dim light signals such as auroras, airglow, gas flares, city lights, and reflected moonlight. In the case of the image above, the sensor detected the visible light emissions as energetic particles rained down from Earth’s magnetosphere and into the gases of the upper atmosphere. The images are similar to those collected by the Operational Linescan System flown on U.S. Defense Meteorological Satellite Program (DMSP) satellites for the past three decades. “When I first saw images like this as a graduate student, I was immediately struck by the fluid dynamic characteristics of the aurora,” said Tom Moore, a space physicist at NASA's Goddard Space Flight Center. “Viewing the aurora in this way makes it immediately clear that space weather is an interaction of fluids from the Sun with those of the Earth's upper atmosphere. The electrodynamics make for important differences between plasmas and ordinary fluids, but familiar behaviors (for example, waves and vortices) are still very apparent. It makes me wonder at the ability of apparently empty space to behave like a fluid

  7. Aurora kinase A is a possible target of OSU‑03012 to destabilize MYC family proteins.

    PubMed

    Silva, Andres; Wang, Jennie; Lomahan, Sarah; Tran, Tuan-Anh; Grenlin, Laura; Suganami, Akiko; Tamura, Yutaka; Ikegaki, Naohiko

    2014-09-01

    OSU-03012, a 3-phosphoinositide-dependent kinase-1 (PDK1) inhibitor, destabilizes MYCN and MYC proteins in neuroblastoma cells. However, AKT phosphorylation is barely detectable in neuroblastoma cells under normal culture conditions whether treated with OSU-03012 or not. This observation suggests that PDK1 is not the main target of OSU-03012 to destabilize MYC and MYCN in neuroblastoma cells. In the present study, we explored one of the possible mechanisms by which OSU-03012 destabilizes MYC and MYCN. Since Aurora kinase A is reported to phosphorylate GSK3β, leading to its inactivation, we hypothesized that one of the targets of OSU-03012 is Aurora kinase A. Comparative analysis of OSU-03012 and VX-680, a potent and specific inhibitor of Aurora kinases, showed that both inhibitors destabilized MYC and MYCN and were significantly growth suppressive to neuroblastoma cell lines. In silico molecular docking analysis further showed that the calculated interaction energy between Aurora kinase A and OSU-03012 was -109.901 kcal/mol, which was lower than that (-89.273 kcal/mol) between Aurora kinase A and FXG, an Aurora kinase-specific inhibitor. Finally, an in vitro Aurora kinase A inhibition assay using a recombinant Aurora kinase A showed that OSU-03012 significantly inhibited Aurora kinase A, although it was weaker in potency than that of VX-680. Thus, OSU-03012 has a likelihood of binding to and inhibiting Aurora kinase A in vivo. These results suggest that OSU-03012 affects multiple cellular targets, including Aurora kinase A, to exhibit its growth suppressive and MYC and MYCN-destabilizing effects on neuroblastoma and other cancer cells.

  8. Plant Aurora kinases play a role in maintenance of primary meristems and control of endoreduplication.

    PubMed

    Petrovská, Beáta; Cenklová, Věra; Pochylová, Zaneta; Kourová, Hana; Doskočilová, Anna; Plíhal, Ondřej; Binarová, Lenka; Binarová, Pavla

    2012-02-01

    • The conserved family of Aurora kinases has multiple functions during mitosis. The roles of plant Aurora kinases have been characterized using inhibitor treatments. • We down-regulated Aurora kinases in Arabidopsis thaliana using RNA interference (RNAi). We carried out a detailed phenotypic analysis of Aurora RNAi plants, biochemical and microscopic studies of AtAurora1 kinase together with AtTPX2 (targeting protein for Xklp2) and γ-tubulin. • Cell division defects were observed in plants with reduced expression of Aurora kinases. Furthermore, the maintenance of primary meristems was compromised and RNAi seedlings entered endoreduplication prematurely. AtAurora1, its activator AtTPX2, and γ-tubulin were associated with microtubules in vitro; they were attached to regrowing kinetochore microtubules and colocalized on spindle microtubules and with a subset of early phragmoplast microtubules. Only the AtAurora1 kinase was translocated to the area of the cell plate. • RNAi silencing of Aurora kinases showed that, in addition to their function in regulating mitosis, the kinases are required for maintaining meristematic activity and controlling the switch from meristematic cell proliferation to differentiation and endoreduplication. The colocalization and co-fractionation of AtAurora1 with AtTPX2, and γ-tubulin on microtubules in a cell cycle-specific manner suggests that AtAurora1 kinase may function to phosphorylate substrates that are critical to the spatiotemporal regulation of acentrosomal microtubule formation and organization. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  9. Nutritional status of Mid-Day Meal programme beneficiaries: A cross-sectional study among primary schoolchildren in Kottayam district, Kerala, India.

    PubMed

    Jayalakshmi, Rajeev; Jissa, Vinoda Thulaseedharan

    2017-01-01

    The efficiency of Mid-Day Meal (MDM) Programme in India to ensure the optimum nutritional status of its beneficiaries is rarely studied. This study assessed the nutritional status of 6-10-year-old schoolchildren who were the beneficiaries of MDM and the child-related factors affecting their nutritional status. A cross-sectional study was performed among 322 children from 12 randomly selected primary schools in one block panchayat of Kerala state. The background information was collected from children and their parents, and anthropometric measurements of the children were observed. The prevalence of undernutrition was estimated using conventional indices (stunting, underweight, and wasting) and composite index of anthropometric failure (CIAF). Logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). The prevalence of CIAF was 45.7% (95% CI: 40.3%-51.1%) and that of stunting, underweight, and wasting were 13.4% (9.7%-17.1%), 38.8% (33.5%-44.1%), and 30.7% (25.7%-35.7%), respectively. The prevalence of wasting (42.6% vs. 28.4%, P = 0.039) and severe underweight (20.4% vs. 7.1%, P = 0.002) was statistically significantly high among occasional/never users compared to regular users of MDM Programme. Children born with <2.5 kg showed an OR of 1.76 (95% CI: 0.99-3.11) for being undernourished compared to children born with normal weight (≥2.5 kg) when adjusted for age, sex, birth order, and illness in the past 2 weeks. This study showed a higher prevalence of undernutrition among school-age children who were the beneficiaries of MDM Programme, and this indicates the need for continuous nutritional interventions and surveillance among these children.

  10. Therapeutic potential of mitotic interaction between the nucleoporin Tpr and aurora kinase A.

    PubMed

    Kobayashi, Akiko; Hashizume, Chieko; Dowaki, Takayuki; Wong, Richard W

    2015-01-01

    Spindle poles are defined by centrosomes; therefore, an abnormal number or defective structural organization of centrosomes can lead to loss of spindle bipolarity and genetic integrity. Previously, we showed that Tpr (translocated promoter region), a component of the nuclear pore complex (NPC), interacts with Mad1 and dynein to promote proper chromosome segregation during mitosis. Tpr also associates with p53 to induce autophagy. Here, we report that Tpr depletion induces mitotic catastrophe and enhances the rate of tetraploidy and polyploidy. Mechanistically, Tpr interacts, via its central domain, with Aurora A but not Aurora B kinase. In Tpr-depleted cells, the expression levels, centrosomal localization and phosphorylation of Aurora A were all reduced. Surprisingly, an Aurora A inhibitor, Alisertib (MLN8237), also disrupted centrosomal localization of Tpr and induced mitotic catastrophe and cell death in a time- and dose-dependent manner. Strikingly, over-expression of Aurora A disrupted Tpr centrosomal localization only in cells with supernumerary centrosomes but not in bipolar cells. Our results highlight the mutual regulation between Tpr and Aurora A and further confirm the importance of nucleoporin function in spindle pole organization, bipolar spindle assembly, and mitosis; functions that are beyond the conventional nucleocytoplasmic transport and NPC structural roles of nucleoporins. Furthermore, the central coiled-coil domain of Tpr binds to and sequesters extra Aurora A to safeguard bipolarity. This Tpr domain merits further investigation for its ability to inhibit Aurora kinase and as a potential therapeutic agent in cancer treatment.

  11. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The green appearing auroral activity engulfs the thin blue line on the Earth's limb. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  12. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The STS-45 crewmembers note the interesting spiralling or corkscrew appearance of this particular sighting. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  13. Therapeutic potential of mitotic interaction between the nucleoporin Tpr and aurora kinase A

    PubMed Central

    Kobayashi, Akiko; Hashizume, Chieko; Dowaki, Takayuki; Wong, Richard W

    2015-01-01

    Spindle poles are defined by centrosomes; therefore, an abnormal number or defective structural organization of centrosomes can lead to loss of spindle bipolarity and genetic integrity. Previously, we showed that Tpr (translocated promoter region), a component of the nuclear pore complex (NPC), interacts with Mad1 and dynein to promote proper chromosome segregation during mitosis. Tpr also associates with p53 to induce autophagy. Here, we report that Tpr depletion induces mitotic catastrophe and enhances the rate of tetraploidy and polyploidy. Mechanistically, Tpr interacts, via its central domain, with Aurora A but not Aurora B kinase. In Tpr-depleted cells, the expression levels, centrosomal localization and phosphorylation of Aurora A were all reduced. Surprisingly, an Aurora A inhibitor, Alisertib (MLN8237), also disrupted centrosomal localization of Tpr and induced mitotic catastrophe and cell death in a time- and dose-dependent manner. Strikingly, over-expression of Aurora A disrupted Tpr centrosomal localization only in cells with supernumerary centrosomes but not in bipolar cells. Our results highlight the mutual regulation between Tpr and Aurora A and further confirm the importance of nucleoporin function in spindle pole organization, bipolar spindle assembly, and mitosis; functions that are beyond the conventional nucleocytoplasmic transport and NPC structural roles of nucleoporins. Furthermore, the central coiled-coil domain of Tpr binds to and sequesters extra Aurora A to safeguard bipolarity. This Tpr domain merits further investigation for its ability to inhibit Aurora kinase and as a potential therapeutic agent in cancer treatment. PMID:25789545

  14. Bora and Aurora-A continue to activate Plk1 in mitosis.

    PubMed

    Bruinsma, Wytse; Macurek, Libor; Freire, Raimundo; Lindqvist, Arne; Medema, René H

    2014-02-15

    Polo-like kinase-1 (Plk1) is required for proper cell division. Activation of Plk1 requires phosphorylation on a conserved threonine in the T-loop of the kinase domain (T210). Plk1 is first phosphorylated on T210 in G2 phase by the kinase Aurora-A, in concert with its cofactor Bora. However, Bora was shown to be degraded prior to entry into mitosis, and it is currently unclear how Plk1 activity is sustained in mitosis. Here we show that the Bora-Aurora-A complex remains the major activator of Plk1 in mitosis. We show that a small amount of Aurora-A activity is sufficient to phosphorylate and activate Plk1 in mitosis. In addition, a fraction of Bora is retained in mitosis, which is essential for continued Aurora-A-dependent T210 phosphorylation of Plk1. We find that once Plk1 is activated, minimal amounts of the Bora-Aurora-A complex are sufficient to sustain Plk1 activity. Thus, the activation of Plk1 by Aurora-A may function as a bistable switch; highly sensitive to inhibition of Aurora-A in its initial activation, but refractory to fluctuations in Aurora-A activity once Plk1 is fully activated. This provides a cell with robust Plk1 activity once it has committed to mitosis.

  15. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The STS-45 crewmembers note the interesting spiralling or corkscrew appearance of this particular sighting. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  16. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Image and Video Library

    1992-04-02

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The STS-45 crewmembers note the interesting spiralling or corkscrew appearance of this particular sighting. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  17. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Image and Video Library

    1992-04-02

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The green appearing auroral activity engulfs the thin blue line on the Earth's limb. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  18. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The green appearing auroral activity engulfs the thin blue line on the Earth's limb. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  19. Aurora-A kinase (AURKA) in normal and pathological cell growth

    PubMed Central

    Nikonova, Anna S.; Astsaturov, Igor; Serebriiskii, Ilya G.; Dunbrack, Roland L.; Golemis, Erica A.

    2013-01-01

    Temporally and spatially controlled activation of the Aurora-A kinase (AURKA) is regulates centrosome maturation, entry into mitosis, formation and function of the bipolar spindle, and cytokinesis. Genetic amplification, and mRNA and protein overexpression of Aurora-A are common in many types of solid tumor, and associated with aneuploidy, supernumerary centrosomes, defective mitotic spindles, and resistance to apoptosis. These properties have led Aurora-A to be considered a high value target for development of cancer therapeutics, with multiple agents currently in early phase clinical trials. More recently, identification of additional, non-mitotic functions and means of activation of Aurora-A during interphase neurite elongation and ciliary resorption have significantly expanded understanding of its function, and may offer insights into clinical performance of Aurora-A inhibitors. We here review mitotic and non-mitotic functions of Aurora-A, discuss Aurora-A regulation in the context of protein structural information, and evaluate progress in understanding and inhibiting Aurora-A in cancer. PMID:22864622

  20. 76 FR 65216 - Beacon Medical Services, LLC, Aurora, CO; Notice of Negative Determination Regarding Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... Employment and Training Administration Beacon Medical Services, LLC, Aurora, CO; Notice of Negative... apply for Trade Adjustment Assistance (TAA) applicable to workers and former workers of Beacon Medical Services, LLC, Aurora, Colorado (Beacon Medical Services). The negative determination was issued on June 22...

  1. Dynamic Phosphorylation of NudC by Aurora B in Cytokinesis.

    PubMed

    Weiderhold, Kimberly N; Fadri-Moskwik, Maria; Pan, Jing; Nishino, Michiya; Chuang, Carol; Deeraksa, Arpaporn; Lin, Sue-Hwa; Yu-Lee, Li-Yuan

    2016-01-01

    Nuclear distribution protein C (NudC) is a mitotic regulator that plays a role in cytokinesis. However, how NudC is regulated during cytokinesis remains unclear. Here, we show that NudC is phosphorylated by Aurora B, a kinase critical for cell abscission. NudC is co-localized with Aurora B at the midbody and co-immunoprecipitated with Aurora B in mitosis. Inhibition of Aurora B by ZM447439 reduced NudC phosphorylation, suggesting that NudC is an Aurora B substrate in vivo. We identified T40 on NudC as an Aurora B phosphorylation site. NudC depletion resulted in cytokinesis failure with a dramatic elongation of the intercellular bridge between daughter cells, sustained Aurora B activity at the midbody, and reduced cell abscission. These cytokinetic defects can be rescued by the ectopic expression of wild-type NudC. Reconstitution with T40A phospho-defective NudC was found to rescue the cytokinesis defect. In contrast, reconstitution with the T40D phospho-mimetic NudC was inefficient in supporting the completion of cytokinesis. These results suggest that that dynamic phosphorylation of NudC by Aurora B regulates cytokinesis.

  2. Aurora B Overexpression Causes Aneuploidy and p21Cip1 Repression during Tumor Development.

    PubMed

    González-Loyola, Alejandra; Fernández-Miranda, Gonzalo; Trakala, Marianna; Partida, David; Samejima, Kumiko; Ogawa, Hiromi; Cañamero, Marta; de Martino, Alba; Martínez-Ramírez, Ángel; de Cárcer, Guillermo; Pérez de Castro, Ignacio; Earnshaw, William C; Malumbres, Marcos

    2015-10-01

    Aurora kinase B, one of the three members of the mammalian Aurora kinase family, is the catalytic component of the chromosomal passenger complex, an essential regulator of chromosome segregation in mitosis. Aurora B is overexpressed in human tumors although whether this kinase may function as an oncogene in vivo is not established. Here, we report a new mouse model in which expression of the endogenous Aurkb locus can be induced in vitro and in vivo. Overexpression of Aurora B in cultured cells induces defective chromosome segregation and aneuploidy. Long-term overexpression of Aurora B in vivo results in aneuploidy and the development of multiple spontaneous tumors in adult mice, including a high incidence of lymphomas. Overexpression of Aurora B also results in a reduced DNA damage response and decreased levels of the p53 target p21(Cip1) in vitro and in vivo, in line with an inverse correlation between Aurora B and p21(Cip1) expression in human leukemias. Thus, overexpression of Aurora B may contribute to tumor formation not only by inducing chromosomal instability but also by suppressing the function of the cell cycle inhibitor p21(Cip1).

  3. Saturn's Hydrogen Aurora, WFPC2 Imaging from the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Trauger, J. T.; Clarke, J. T.; Ballester, G. E.; Evans, R. W.; Burrows, C. J.; Crisp, D.; Gallagher, J. S.; Griffiths, R. E.; Hester, J. Jeff; Hoessel, J. G.; hide

    1998-01-01

    WFPC2/HST images of Saturn's far-ultraviolet aurora reveal emissions confined to a narrow band of latitudes near Saturn's north and south poles. The aurorae are most prominent in the morning sector with patterns that appear fixed in local time.

  4. Saturn's Hydrogen Aurora, WFPC2 Imaging from the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Trauger, J. T.; Clarke, J. T.; Ballester, G. E.; Evans, R. W.; Burrows, C. J.; Crisp, D.; Gallagher, J. S.; Griffiths, R. E.; Hester, J. Jeff; Hoessel, J. G.; Holtzman, J. A.; Mould, J. R.; Sahai, R.; Scowen, P. A.; Stapelfeldt, K. R.; Watson, A. M.

    1998-01-01

    WFPC2/HST images of Saturn's far-ultraviolet aurora reveal emissions confined to a narrow band of latitudes near Saturn's north and south poles. The aurorae are most prominent in the morning sector with patterns that appear fixed in local time.

  5. Low-Latitude Auroras: The Magnetic Storm of 14-15 May 1921

    NASA Technical Reports Server (NTRS)

    Silverman, S. M.; Cliver, E. W.

    2001-01-01

    We review solar geophysical data relating to the great magnetic storm of 14-15 May 1921, with emphasis on observations of the low-latitude visual aurora. From the reports we have gathered for this event the lowest geomagnetic latitude of definite overhead aurora (coronal form) was 40 deg and the lowest geomagnetic latitude from which auroras were observed on the poleward horizon in the northern hemisphere was 30 deg. For comparison, corresponding overhead/low-latitude values of 48 deg/32 deg and 41 deg/20 deg were reported for the great auroras on 28-29 August and 1-2 September 1859, respectively. However for the 1921 event, there is a report of aurora from Apia, Samoa, in the southern hemisphere, within 13 deg of the geomagnetic equator. This report by professional observers appears to be credible, based on the aurora description and timing, but is puzzling because of the discrepancy with the lowest latitude of observation in the northern hemisphere and the great implied aurora height (approximately 2000 km, assuming overhead aurora at Auckland, New Zealand). We discuss various possibilities that might account for this observation.

  6. 78 FR 64196 - Approval of Subzone Status: Pillow Kingdom, Inc., Aurora, Colorado

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Approval of Subzone Status: Pillow Kingdom, Inc., Aurora, Colorado On August 21... existing activation limit of FTZ 123, on behalf of Pillow Kingdom, Inc., in Aurora, Colorado....

  7. Dynamic Phosphorylation of NudC by Aurora B in Cytokinesis

    PubMed Central

    Weiderhold, Kimberly N.; Fadri-Moskwik, Maria; Pan, Jing; Nishino, Michiya; Chuang, Carol; Deeraksa, Arpaporn; Lin, Sue-Hwa; Yu-Lee, Li-Yuan

    2016-01-01

    Nuclear distribution protein C (NudC) is a mitotic regulator that plays a role in cytokinesis. However, how NudC is regulated during cytokinesis remains unclear. Here, we show that NudC is phosphorylated by Aurora B, a kinase critical for cell abscission. NudC is co-localized with Aurora B at the midbody and co-immunoprecipitated with Aurora B in mitosis. Inhibition of Aurora B by ZM447439 reduced NudC phosphorylation, suggesting that NudC is an Aurora B substrate in vivo. We identified T40 on NudC as an Aurora B phosphorylation site. NudC depletion resulted in cytokinesis failure with a dramatic elongation of the intercellular bridge between daughter cells, sustained Aurora B activity at the midbody, and reduced cell abscission. These cytokinetic defects can be rescued by the ectopic expression of wild-type NudC. Reconstitution with T40A phospho-defective NudC was found to rescue the cytokinesis defect. In contrast, reconstitution with the T40D phospho-mimetic NudC was inefficient in supporting the completion of cytokinesis. These results suggest that that dynamic phosphorylation of NudC by Aurora B regulates cytokinesis. PMID:27074040

  8. 77 FR 23673 - Notice of Intent To Grant Exclusive Patent License; Aurora Technologies, LLC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Navy Notice of Intent To Grant Exclusive Patent License; Aurora Technologies, LLC AGENCY... intent to grant to Aurora Technologies, LLC a revocable, nonassignable, exclusive license to practice...

  9. Aurora B Overexpression Causes Aneuploidy and p21Cip1 Repression during Tumor Development

    PubMed Central

    González-Loyola, Alejandra; Fernández-Miranda, Gonzalo; Trakala, Marianna; Partida, David; Samejima, Kumiko; Ogawa, Hiromi; Cañamero, Marta; de Martino, Alba; Martínez-Ramírez, Ángel; de Cárcer, Guillermo; Pérez de Castro, Ignacio; Earnshaw, William C.

    2015-01-01

    Aurora kinase B, one of the three members of the mammalian Aurora kinase family, is the catalytic component of the chromosomal passenger complex, an essential regulator of chromosome segregation in mitosis. Aurora B is overexpressed in human tumors although whether this kinase may function as an oncogene in vivo is not established. Here, we report a new mouse model in which expression of the endogenous Aurkb locus can be induced in vitro and in vivo. Overexpression of Aurora B in cultured cells induces defective chromosome segregation and aneuploidy. Long-term overexpression of Aurora B in vivo results in aneuploidy and the development of multiple spontaneous tumors in adult mice, including a high incidence of lymphomas. Overexpression of Aurora B also results in a reduced DNA damage response and decreased levels of the p53 target p21Cip1 in vitro and in vivo, in line with an inverse correlation between Aurora B and p21Cip1 expression in human leukemias. Thus, overexpression of Aurora B may contribute to tumor formation not only by inducing chromosomal instability but also by suppressing the function of the cell cycle inhibitor p21Cip1. PMID:26240282

  10. 3 CFR 8842 - Proclamation 8842 of July 20, 2012. Honoring the Victims of the Tragedy in Aurora, Colorado

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Victims of the Tragedy in Aurora, Colorado 8842 Proclamation 8842 Presidential Documents Proclamations Proclamation 8842 of July 20, 2012 Proc. 8842 Honoring the Victims of the Tragedy in Aurora, ColoradoBy the... senseless acts of violence perpetrated on July 20, 2012, in Aurora, Colorado, by the authority vested in me...

  11. 78 FR 52758 - Foreign-Trade Zone 123-Denver, Colorado; Application for Subzone, Pillow Kingdom, Inc., Aurora...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-26

    ... Kingdom, Inc., Aurora, Colorado An application has been submitted to the Foreign-Trade Zones (FTZ) Board... Pillow Kingdom, Inc. (Pillow Kingdom), located in Aurora, Colorado. The application was submitted... subzone would consist of the following site: Site 1 (34.66 acres) 24000 E. 19th Avenue, Aurora....

  12. 76 FR 61742 - Unimin Corporation Including On-Site Leased Workers From Staffmark and Elwood Staffing Aurora, IN...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-05

    ... Elwood Staffing Aurora, IN; Amended Certification Regarding Eligibility To Apply for Worker Adjustment..., including on-site leased workers from Staffmark, Aurora, Indiana. The workers are engaged in activities... on-site at the Aurora, Indiana location of Unimin Corporation. The Department has determined...

  13. The Dawn of Aurora Kinase Research: From Fly Genetics to the Clinic.

    PubMed

    Carmena, Mar; Earnshaw, William C; Glover, David M

    2015-01-01

    Aurora kinases comprise a family of highly conserved serine-threonine protein kinases that play a pivotal role in the regulation of cell cycle. Aurora kinases are not only involved in the control of multiple processes during cell division but also coordinate chromosomal and cytoskeletal events, contributing to the regulation of checkpoints and ensuring the smooth progression of the cell cycle. Because of their fundamental contribution to cell cycle regulation, Aurora kinases were originally identified in independent genetic screens designed to find genes involved in the regulation of cell division. The first aurora mutant was part of a collection of mutants isolated in C. Nusslein-Volhard's laboratory. This collection was screened in D. M. Glover's laboratory in search for mutations disrupting the centrosome cycle in embryos derived from homozygous mutant mothers. The mutants identified were given names related to the "polar regions," and included not only aurora but also the equally famous polo. Ipl1, the only Aurora in yeast, was identified in a genetic screen looking for mutations that caused chromosome segregation defects. The discovery of a second Aurora-like kinase in mammals opened a new chapter in the research of Aurora kinases. The rat kinase AIM was found to be highly homologous to the fly and yeast proteins, but localized at the midzone and midbody and was proposed to have a role in cytokinesis. Homologs of the equatorial Aurora (Aurora B) were identified in metazoans ranging from flies to humans. Xenopus Aurora B was found to be in a complex with the chromosomal passenger INCENP, and both proteins were shown to be essential in flies for chromosome structure, segregation, central spindle formation and cytokinesis. Fifteen years on, Aurora kinase research is an active field of research. After the successful introduction of the first anti-mitotic agents in cancer therapy, both Auroras have become the focus of attention as targets for the development of new

  14. The Dawn of Aurora Kinase Research: From Fly Genetics to the Clinic

    PubMed Central

    Carmena, Mar; Earnshaw, William C.; Glover, David M.

    2015-01-01

    Aurora kinases comprise a family of highly conserved serine-threonine protein kinases that play a pivotal role in the regulation of cell cycle. Aurora kinases are not only involved in the control of multiple processes during cell division but also coordinate chromosomal and cytoskeletal events, contributing to the regulation of checkpoints and ensuring the smooth progression of the cell cycle. Because of their fundamental contribution to cell cycle regulation, Aurora kinases were originally identified in independent genetic screens designed to find genes involved in the regulation of cell division. The first aurora mutant was part of a collection of mutants isolated in C. Nusslein-Volhard's laboratory. This collection was screened in D. M. Glover's laboratory in search for mutations disrupting the centrosome cycle in embryos derived from homozygous mutant mothers. The mutants identified were given names related to the “polar regions,” and included not only aurora but also the equally famous polo. Ipl1, the only Aurora in yeast, was identified in a genetic screen looking for mutations that caused chromosome segregation defects. The discovery of a second Aurora-like kinase in mammals opened a new chapter in the research of Aurora kinases. The rat kinase AIM was found to be highly homologous to the fly and yeast proteins, but localized at the midzone and midbody and was proposed to have a role in cytokinesis. Homologs of the equatorial Aurora (Aurora B) were identified in metazoans ranging from flies to humans. Xenopus Aurora B was found to be in a complex with the chromosomal passenger INCENP, and both proteins were shown to be essential in flies for chromosome structure, segregation, central spindle formation and cytokinesis. Fifteen years on, Aurora kinase research is an active field of research. After the successful introduction of the first anti-mitotic agents in cancer therapy, both Auroras have become the focus of attention as targets for the development of

  15. Spiral structures and regularities in magnetic field variations and auroras

    NASA Astrophysics Data System (ADS)

    Feldstein, Y. I.; Gromova, L. I.; Förster, M.; Levitin, A. E.

    2012-02-01

    The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras. We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals. We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines) currents (FACs) a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral), and later in the nighttime-evening (N-spiral) and morning (M-spiral) sectors both in the Northern and Southern

  16. Targeting Aurora Kinase A enhances radiation sensitivity of atypical teratoid rhabdoid tumor cells.

    PubMed

    Venkataraman, Sujatha; Alimova, Irina; Tello, Tiffany; Harris, Peter S; Knipstein, Jeffrey A; Donson, Andrew M; Foreman, Nicholas K; Liu, Arthur K; Vibhakar, Rajeev

    2012-05-01

    Atypical teratoid/rhabdoid tumors (ATRT) are rare, highly malignant, embryonal CNS tumors with a poor prognosis. Therapy relies on highly toxic chemotherapy and radiotherapy. To improve outcomes and decrease morbidity, more targeted therapy is required. Gene expression analysis revealed elevated expression of multiple kinases in ATRT tissues. Aurora Kinase A was one of the candidate kinases. The objective of this study was to evaluate the impact of Aurora Kinase A inhibition in ATRT cell lines. Our analysis revealed that inhibition of Aurora Kinase A induces cell death in ATRT cells and the small molecule inhibitor MLN 8237 sensitizes these cells to radiation. Furthermore, inhibition of Aurora Kinase A resulted in decreased activity of pro-proliferative signaling pathways. These data indicate that inhibition of Aurora Kinase A is a promising small molecule target for ATRT therapy.

  17. A FRET biosensor reveals spatiotemporal activation and functions of aurora kinase A in living cells.

    PubMed

    Bertolin, Giulia; Sizaire, Florian; Herbomel, Gaëtan; Reboutier, David; Prigent, Claude; Tramier, Marc

    2016-09-14

    Overexpression of AURKA is a major hallmark of epithelial cancers. It encodes the multifunctional serine/threonine kinase aurora A, which is activated at metaphase and is required for cell cycle progression; assessing its activation in living cells is mandatory for next-generation drug design. We describe here a Förster's resonance energy transfer (FRET) biosensor detecting the conformational changes of aurora kinase A induced by its autophosphorylation on Thr288. The biosensor functionally replaces the endogenous kinase in cells and allows the activation of the kinase to be followed throughout the cell cycle. Inhibiting the catalytic activity of the kinase prevents the conformational changes of the biosensor. Using this approach, we discover that aurora kinase A activates during G1 to regulate the stability of microtubules in cooperation with TPX2 and CEP192. These results demonstrate that the aurora kinase A biosensor is a powerful tool to identify new regulatory pathways controlling aurora kinase A activation.

  18. Aurora-A amplification associated with BRCA2 mutation in breast tumours.

    PubMed

    Bodvarsdottir, Sigridur K; Hilmarsdottir, Holmfridur; Birgisdottir, Valgerdur; Steinarsdottir, Margret; Jonasson, Jon G; Eyfjord, Jorunn E

    2007-04-08

    Potential interaction of Aurora-A amplification and BRCA2 mutation was examined in breast tumours from BRCA2 999del5 mutation carriers (n=20) and non-carriers (n=41). Aurora-A amplification studied by FISH was significantly more common in breast tumours from BRCA2 mutation carriers (p=0.0005). Extensive Aurora-A amplification was also detected on metaphase chromosomes in three breast epithelial cell lines with the same BRCA2 mutation. In addition, significant association was found between Aurora-A amplification and TP53 mutations in non-BRCA2 mutation carrier tumours (p=0.007). These results suggest that breast tumours with mutations in BRCA2 or TP53 could be promising candidates for Aurora-A targeted treatment.

  19. A FRET biosensor reveals spatiotemporal activation and functions of aurora kinase A in living cells

    PubMed Central

    Bertolin, Giulia; Sizaire, Florian; Herbomel, Gaëtan; Reboutier, David; Prigent, Claude; Tramier, Marc

    2016-01-01

    Overexpression of AURKA is a major hallmark of epithelial cancers. It encodes the multifunctional serine/threonine kinase aurora A, which is activated at metaphase and is required for cell cycle progression; assessing its activation in living cells is mandatory for next-generation drug design. We describe here a Förster's resonance energy transfer (FRET) biosensor detecting the conformational changes of aurora kinase A induced by its autophosphorylation on Thr288. The biosensor functionally replaces the endogenous kinase in cells and allows the activation of the kinase to be followed throughout the cell cycle. Inhibiting the catalytic activity of the kinase prevents the conformational changes of the biosensor. Using this approach, we discover that aurora kinase A activates during G1 to regulate the stability of microtubules in cooperation with TPX2 and CEP192. These results demonstrate that the aurora kinase A biosensor is a powerful tool to identify new regulatory pathways controlling aurora kinase A activation. PMID:27624869

  20. Assessment of Aurora a Kinase Expression in Breast Cancer: A Tool for Early Diagnosis?

    PubMed Central

    Ferchichi, Imen; Sassi Hannachi, Samia; Baccar, Amal; Marrakchi Triki, Raja; Cremet, Jean Yves; Ben Romdhane, Khaled; Prigent, Claude; Ben Ammar El Gaaied, Amel

    2013-01-01

    Aurora A kinase is overexpressed in many cancers but the status of this protein in the breast cancer often varies. We investigate the expression and localization of Aurora A protein in relation with tumor emergence and progression in breast cancer. Aurora A kinase status was evaluated in 107 patients using immunohistochemistry. The experimental findings showed that high expression of the Aurora A protein was correlated with elevated nuclear grade, low expression of progesterone receptor and positive nodal status. The experimental results showed also that the localization of this kinase shifts from cytoplasm in non malignant adjacent tissue to both cytoplasmic and nuclear compartments in tumoral tissue, suggesting an oncogenic role of the nuclear accumulation. We have, furthermore, detected the overexpression of this protein in non malignant adjacent tissue. The expression of the Aurora A kinase in non malignant tissue may represent an earlier diagnosis tool for breast cancer. PMID:23324574

  1. Saw-tooth substorms: Inconsistency of repetitive bay-like magnetic disturbances with behavior of aurora

    NASA Astrophysics Data System (ADS)

    Troshichev, O.; Stauning, P.; Liou, K.; Reeves, G.

    2011-02-01

    The relationships between the magnetic disturbance onsets, aurora dynamics and particles injections at the geostationary orbit have been analyzed in detail for 25 sawtooth substorms. It is shown that inconsistency between the above signatures of the substorms onset is typical of the powerful sawtooth substorms, unlike the isolated (“classical”) magnetospheric substorms. The distinguishing feature of the aurora in case of saw-tooth substorms is permanently high level of auroral activity irrespective of the magnetic disturbance onsets and the double oval structure of the aurora display. The close relationship between the aurora behavior and the particle injections at geostationary orbit is also broken. The conclusion is made, that the classical concept of the substorm development, put forward by Akasofu (1964) for isolated substorms, is not workable in cases of the sawtooth disturbances, when the powerful solar wind energy pumping into the magnetosphere provides a permanent powerful aurora particle precipitation into the auroral zone.

  2. The nucleoporin ALADIN regulates Aurora A localization to ensure robust mitotic spindle formation

    PubMed Central

    Carvalhal, Sara; Ribeiro, Susana Abreu; Arocena, Miguel; Kasciukovic, Taciana; Temme, Achim; Koehler, Katrin; Huebner, Angela; Griffis, Eric R.

    2015-01-01

    The formation of the mitotic spindle is a complex process that requires massive cellular reorganization. Regulation by mitotic kinases controls this entire process. One of these mitotic controllers is Aurora A kinase, which is itself highly regulated. In this study, we show that the nuclear pore protein ALADIN is a novel spatial regulator of Aurora A. Without ALADIN, Aurora A spreads from centrosomes onto spindle microtubules, which affects the distribution of a subset of microtubule regulators and slows spindle assembly and chromosome alignment. ALADIN interacts with inactive Aurora A and is recruited to the spindle pole after Aurora A inhibition. Of interest, mutations in ALADIN cause triple A syndrome. We find that some of the mitotic phenotypes that we observe after ALADIN depletion also occur in cells from triple A syndrome patients, which raises the possibility that mitotic errors may underlie part of the etiology of this syndrome. PMID:26246606

  3. Evolution of the Global Aurora During Positive IMP Bz and Varying IMP By Conditions

    NASA Technical Reports Server (NTRS)

    Cumnock, J. A.; Sharber, J. R.; Heelis. R. A.; Hairston, M. R.; Carven, J. D.

    1997-01-01

    The DE 1 imaging instrumentation provides a full view of the entire auroral oval every 12 min for several hours during each orbit. We examined five examples of global evolution of the aurora that occurred during the northern hemisphere winter of 1981-1982 when the z component of the interplanetary magnetic field was positive and the y component was changing sign. Evolution of an expanded auroral emission region into a theta aurora appears to require a change in the sign of By during northward interplanetary magnetic field (IMF). Theta aurora are formed both from expanded duskside emission regions (By changes from positive to negative) and dawnside emission regions (By changes from negative to positive), however the dawnside-originating and duskside-originating evolutions are not mirror images. The persistence of a theta aurora after its formation suggests that there may be no clear relationship between the theta aurora pattern and the instantaneous configuration of the IMF.

  4. The Aurora B Kinase in Chromosome Bi-Orientation and Spindle Checkpoint Signaling

    PubMed Central

    Krenn, Veronica; Musacchio, Andrea

    2015-01-01

    Aurora B, a member of the Aurora family of serine/threonine protein kinases, is a key player in chromosome segregation. As part of a macromolecular complex known as the chromosome passenger complex, Aurora B concentrates early during mitosis in the proximity of centromeres and kinetochores, the sites of attachment of chromosomes to spindle microtubules. There, it contributes to a number of processes that impart fidelity to cell division, including kinetochore stabilization, kinetochore–microtubule attachment, and the regulation of a surveillance mechanism named the spindle assembly checkpoint. In the regulation of these processes, Aurora B is the fulcrum of a remarkably complex network of interactions that feed back on its localization and activation state. In this review, we discuss the multiple roles of Aurora B during mitosis, focusing in particular on its role at centromeres and kinetochores. Many details of the network of interactions at these locations remain poorly understood, and we focus here on several crucial outstanding questions. PMID:26528436

  5. Jupiter's Mid-Infrared Aurora: Solar Connection and Minor Constituents

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore; Livengood, T.A.; Fast, K.E.; Hewagama, T.; Schmilling, F.; Sonnabend, G.; Delgado, J.

    2009-01-01

    High spectral resolution in the 12 pin region of the polar regions of Jupiter reveal unique information on auroral phenomena and upper stratospheric composition. Polar aurorae in Jupiter's atmosphere radiate; throughout the electromagnetic spectrum from X-ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based. spectroscopic measurements of Jupiter's northern mid-IR aurora acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane, emission brightness and solar 10.7-cm radar flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high scalar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. The spectra measured contain features that cannot be attributed to ethane and are most likely spectra of minor constituents whose molecular bands overlap the v9 band of ethane. Possible candidates are allene, propane, and other higher order hydrocarbons. These features appear to be enhanced in the active polar regions. Laboratory measurements at comparable spectral resolution of spectra of candidate molecules will be used to identify the constituents. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the NASA/ESA Europa Jupiter System Mission.

  6. Jupiter's Mid-Infrared Aurora: Solar Connection and Minor Constituents

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore; Livengood, T.A.; Fast, K.E.; Hewagama, T.; Schmilling, F.; Sonnabend, G.; Delgado, J.

    2009-01-01

    High spectral resolution in the 12 pin region of the polar regions of Jupiter reveal unique information on auroral phenomena and upper stratospheric composition. Polar aurorae in Jupiter's atmosphere radiate; throughout the electromagnetic spectrum from X-ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based. spectroscopic measurements of Jupiter's northern mid-IR aurora acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane, emission brightness and solar 10.7-cm radar flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high scalar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. The spectra measured contain features that cannot be attributed to ethane and are most likely spectra of minor constituents whose molecular bands overlap the v9 band of ethane. Possible candidates are allene, propane, and other higher order hydrocarbons. These features appear to be enhanced in the active polar regions. Laboratory measurements at comparable spectral resolution of spectra of candidate molecules will be used to identify the constituents. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the NASA/ESA Europa Jupiter System Mission.

  7. First Terrestrial Soft X-ray Aurora Observations by Chandra

    NASA Technical Reports Server (NTRS)

    Bhardwaj, Anil; Elsner, Ronald F.; Gladstone, G. Randall; Waite, J. Hunter, Jr.; Cravens, Thomas E.; Ostgaard, Nikolai; Chang, Shen-Wu; Metzger, Albert E.; Majeed, Tariq

    2004-01-01

    Northern polar "auroral" regions of Earth was observed by High-Resolution Camera in imaging mode (T32C-I) aboard Chandra X-Ray Observatory (CXO) during mid December 2003 - mid April 2004. Ten CXO observations, each approximately 20 min duration, were made in a non-conventional method (due to CXO technical issues), such that Chandra was aimed at a fixed point in sky and the Earth's polar cusp was allowed to drift through the HRC-I field-of-view. The observations were performed when CXO was near apogee and timed during northern winter mostly near midnight (6 hr), except two observations which occurred around 1200 UT, so that northern polar region is entirely in dark and solar fluoresced x-ray contamination can be avoided. These observations were aimed at searching the Earth's soft x-ray aurora and to do a comparative study with Jupiter's x-ray aurora, where a pulsating x-ray hot-spot near the northern magnetic pole has been observed by Chandra that implies a particle source region near Jupiter's magnetopause, and entry of heavy solar wind ions due to high-latitude reconnection as a viable explanation for the soft x-ray emissions. The first Chandra soft (0.1-2 keV) x-ray observations of Earth's aurora show that it is highly variable (intense arc, multiple arcs, diffuse, at times almost absent). In at least one of the observations an isolated blob of emission is observed where we expect cusp to be: giving indication of solar wind charge-exchange signature in x-rays. We are comparing the Chandra x-ray observations with observations at other wavelengths and particle data from Earth-orbiting satellites and solar wind measurements from near-Earth ACE and SOH0 spacecraft. Preliminary results from these unique CXO-Earth observations will be presented and discussed.

  8. The Jovian UV aurorae as seen by Juno-UVS

    NASA Astrophysics Data System (ADS)

    Bonfond, Bertrand; Gladstone, Randy; Grodent, Denis; Hue, Vincent; Gérard, Jean-Claude; Versteeg, Maarten; Greathouse, Thomas; Davis, Michael; Bolton, Scott; Levin, Steven; Connerney, John; Bagenal, Fran

    2017-04-01

    The Juno spacecraft was inserted in orbit around Jupiter on July 4th 2016. Its highly elongated polar orbit brings it <5000 km above the cloud tops every 53,5 days, allowing spectacular and unprecedented views of its polar aurorae. The Juno-UVS instrument is an imaging spectrograph observing perpendicularly to the Juno spin axis. It is equipped with a moving scan mirror at the entrance of the instrument that allows the field of view to be directed up to +/-30° away from the spin plane. The 70-205 nm bandpass comprises key UV auroral emissions such as the H2 bands and the H Lyman alpha line, as well as hydrocarbon absorption bands. We present polar maps of the aurorae at Jupiter for the first three first few periapses. These maps offer the first high resolution observations of the night-side aurorae. We will discuss the observed auroral morphology, including the satellite footprints, the outer emissions, the main emission and the polar emissions. We will also show maps of the color ratio, comparing the relative intensity of wavelengths subject to different degrees of absorption by CH4. Such measurements directly relate to the energy of the precipitating particles, since the more energetic the particles, the deeper they penetrate and the stronger the resulting methane absorption. For example, we will show evidence of longitudinal shifts between the brightness peaks and color ratio peaks in several auroral features. Such shifts may be interpreted as the result of the differential particle drift in plasma injection signatures.

  9. AURORA BOREALIS - European Research Icebreaker With Drilling Capability

    NASA Astrophysics Data System (ADS)

    Biebow, N.; Lembke-Jene, L.; Kunz-Pirrung, M.; Thiede, J.

    2008-12-01

    The polar oceans are the least known areas of the globe, in although they hold the key to many of our climate´s secrets. How does the sea ice coverage and the sea water properties change? How do plants and animals survive under the most extreme conditions of the earth? Which information of past climate change can be read from the sediments at the sea-floor and how can the future changing climate be predicted? In order to answer such and further questions, for the moment a hypermodern research vessel, the AURORA BOREALIS, is planned, which can handle the cool summers and freezing winters of the polar oceans and which can drill deep into the sea floor. AURORA BOREALIS will be the most advanced Research Icebreaker in the world with a multi-functional role of drilling in deep ocean basins and supporting climate/environmental research and decision support for stakeholder governments for the next 35-40 years. It will have a high icebreaking capacity to penetrate autonomously (single ship operation) into the central Arctic Ocean with more than 2.5 meters of ice cover, during all seasons of the year. The new technological features will include dynamic positioning in closed sea- ice cover, satellite navigation and ice-management support and the deployment and operation of Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUVs) from the twin moon-pools. A unique feature of the vessel is the deep-sea drilling rig, which will enable sampling of the ocean floor and sub-sea up to 5000 m water and 1000 m penetration at the most inhospitable places on earth. The drilling capability will be deployed in both Polar Regions on the long run and AURORA BOREALIS will be the only vessel worldwide that could undertake this type of scientific investigation.

  10. Electron distribution function formation in regions of diffuse aurora

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Tripathi, A. K.; Sibeck, D.; Himwich, E.; Glocer, A.; Singhal, R. P.

    2015-11-01

    The precipitation of high-energy magnetospheric electrons (E ˜ 600 eV-10 KeV) in the diffuse aurora contributes significant energy flux into the Earth's ionosphere. To fully understand the formation of this flux at the upper ionospheric boundary, ˜700-800 km, it is important to consider the coupled ionosphere-magnetosphere system. In the diffuse aurora, precipitating electrons initially injected from the plasma sheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These precipitating electrons can be additionally reflected upward from the two conjugate ionospheres, leading to a series of multiple reflections through the magnetosphere. These reflections greatly influence the initially precipitating flux at the upper ionospheric boundary (700-800 km) and the resultant population of secondary electrons and electrons cascading toward lower energies. In this paper, we present the solution of the Boltzman-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E < 600 eV) and its energy interplay in the magnetosphere and two conjugated ionospheres. This solution takes into account, for the first time, the formation of the electron distribution function in the diffuse auroral region, beginning with the primary injection of plasma sheet electrons via both electrostatic electron cyclotron harmonic waves and whistler mode chorus waves to the loss cone, and including their subsequent multiple atmospheric reflections in the two magnetically conjugated ionospheres. It is demonstrated that magnetosphere-ionosphere coupling is key in forming the electron distribution function in the diffuse auroral region.

  11. Exploring the Secrets of the Aurora, 2nd edition

    NASA Astrophysics Data System (ADS)

    Robinson, Robert M.

    2008-04-01

    Pioneers in science invariably have struggled with ideas that future scientists learn and accept with almost casual indifference. Perhaps the basis for progress in science is that the energy and creativity of young scientists need not be expended on rediscovering truths that earlier scientists spent whole careers uncovering. Nevertheless, an appreciation for the process by which these truths were painstakingly unveiled is a lesson from which scientists of all ages can learn. Exploring the Secrets of the Aurora, by Syun-Ichi Akasofu, should be read for that reason alone, but the book has other merits as well.

  12. STS-56 remote manipulator system (RMS) backdropped against Aurora Borealis

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-56 remote manipulator system (RMS) arm is backdropped against the 'northern lights' (Aurora Borealis) in this view exposed from the crew cabin of Discovery, Orbiter Vehicle (OV) 103. The arm was used in operations with the Shuttle Pointed Autonomous Research Tool for Astronomy 201 (SPARTAN-201). Space Shuttle astronauts have the opportunity to observe auroral activity only on 57-degree inclination missions and only in the 'night' hemisphere. Astronaut hand-held photography is the only method which is capable of documenting the detailed structure of the auroral oval.

  13. HUBBLE PROVIDES THE FIRST IMAGES OF SATURN'S AURORA (Top)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is the first image ever taken of bright aurorae at Saturn's northern and southern poles, as seen in far ultraviolet light by the Wide Field and Planetary Camera 2 aboard NASA's Hubble Space Telescope. Hubble resolves a luminous, circular band centered on the north pole, where an enormous auroral curtain rises as far as 1,200 miles (2,000 kilometers) above the cloudtops. This curtain changed rapidly in brightness and extent over the two hour period of our HST observations, though the brightest emissions remained at a position fixed in sun angle, near 'dawn' in the north auroral band. The image was taken on October 9, 1994, when Saturn was at a distance of 831 million miles (1.3 billion kilometers) from Earth. The aurora is produced as trapped charged particles precipitating from the magnetosphere collide with atmospheric gases -- molecular and atomic hydrogen in Saturn's case. As a result of the bombardment, Saturn's gases glow at far-ultraviolet wavelengths (110-160 nanometers) which are absorbed by the Earth's atmosphere, and so can only be observed from space-based telescopes. Saturn's magnetic field is nearly perfectly aligned with the planet's rotation, giving the auroral 'ring' its symmetry centered on the pole. (The southern aurora is faintly visible in this view despite the fact that Saturn's northern pole is now tilted slightly toward Earth.) The Hubble images demonstrate our capability to record from the Earth the auroral brightness and distribution about Saturn's poles, which will ultimately complement the in situ measurements of Saturn's magnetic field and charged particles to be made by the NASA/ESA Cassini spacecraft near the turn of the century. Study of the aurora on Saturn had its beginnings a few decades ago. The Pioneer 11 probe observed a far-ultraviolet brightening on Saturn's poles in 1979. Beginning in 1980, a series of spectroscopic observations by the International Ultraviolet Explorer (IUE) have sporadically detected emissions from

  14. The reflex-diode HPM source on Aurora

    SciTech Connect

    Huttlin, G.A.; Bushell, M.S.; Conrad, D.B.; Davis, D.P.; Litz, M.S.; Ruth, B.G.; Agee, F.J. ); Ebersole, K.L.; Judy, D.C.; Lezcano, P.A.; Pereira, N.R.; Weidenheimer, D.M. )

    1990-06-01

    This paper describes the most recent in a series of experiments to develop the reflex diode as a source of microwaves on the Aurora relativistic electron-beam pulser. The authors have achieved an overall output for radial extraction of {approximately} 400 J in microwave bursts from {approximately} 100 to 150 ns at frequencies below 1 GHz. The diagnostics for radial extraction have included directional couplers, card calorimeters, and free-field sensors. The authors have varied the anode/cathode spacing, downstream microwave reflector, and a second anode foil, but, within the range of variations, no strong trends have been noted.

  15. Magnetic field morphology of the jovian main aurora

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; Rachmeler, L. A.

    2006-12-01

    The main oval of the jovian aurora is thought to be associated with the breakdown of corotation of the magnetospheric plasma that occurs at equatorial distances of about 20 Rj. Mapping of the magnetic field between the equator and the polar regions is strongly affected by currents in the equatorial plasmasheet. We have investigated variations in the magnetic morphology of the auroral region using both the Connerney et al. (1998) model (that has only azimuthal currents in the equator) as well as the Khurana (2001) model (that includes both radial and azimuthal currents). We have also explored the effects of local time asymmetries of the Khurana model on the field morphology.

  16. Airglow and aurora in the atmospheres of Venus and Mars

    NASA Astrophysics Data System (ADS)

    Fox, J. L.

    Measurements and models of the luminosity that originates in the Martian and Venusian atmospheres, including dayglow, nightglow and aurora, are compared. Most of the emission features considered appear in the UV and visible regions of the spectrum and arise from electronic transitions of thermospheric species. Spatially and temporally variable intensities of the oxygen 1304 and 1356 A lines have been observed on the nightside of Venus and have been labeled 'auroral', that is, ascribed to electron precipitation. Only a future aeronomy mission to Mars could unequivocally determine whether such emissions are present on the nightside of Mars.

  17. Artificial auroras in the upper atmosphere. I - Electron beam injections

    NASA Technical Reports Server (NTRS)

    Burch, J. L.; Mende, S. B.; Kawashima, N.; Roberts, W. T.; Taylor, W. W. L.; Neubert, T.; Gibson, W. C.; Marshall, J. A.; Swenson, G. R.

    1993-01-01

    The Atlas-1 Spacelab payload's Space Experiments with Particle Accelerators generated artificial electron beams for the stimulation of auroral emissions at southern auroral latitudes. Optical measurements were made by the Shuttle Orbiter's onboard TV cameras, as well as by the Atmospheric Emissions Photometric Imager (in both white light and the 427.8 nm N2(+) emission line). Shuttle-based auroral imaging furnished a novel perspective on the artificial auroras; the emissions were traced from 295 km to the 110 km level along the curved magnetic-field lines.

  18. Pinch-Reflex-Diode Scaling on the Aurora Pulser.

    DTIC Science & Technology

    1982-06-29

    Goldstein and Roswell Lee, Phys. Rev. Lett. 35, 1079 (1975). 9. C.W. Mendel, Jr., D.M. Zagar , G.S. Mills, S . Humphries, Jr., and * S.A. Goldstein, Rev...4116 4. TITLE (and Subtitl.) S . TYPE OF REPORT & PERIOD COVERED PINCH-REFLEX-DIODE SCALING ON THE Interim report on a continuing AURORA PULSER NRL...problem. 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR() 6. CONTRACT OR GRANT NUMBER(A) R. A. Meger* and F. C. Young S . PERFORMING ORGANIZATION NAME AND

  19. Techniques for Source-Region EMP Experiments at AURORA

    DTIC Science & Technology

    1983-02-01

    field is uni- For a typicAl A1IRUPA sensor, V 0nsr LA u 3 p l ThCA 1 ore in.ý - 7777W,.t---7 -77 - " Also, if interference in the output cable is...HDL-CR-83-072-1 SFebruary 1983 - Techniques for Source-Region EMP Experiments at AURORA by V. A . J. van Lint Prepared by Mission Research...NUMSERPe) HDL Contact: V. A . J. van Lint William Scharf DMAK21-80-R-9072 9. P~ERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT. TASK

  20. Doppler shifted H Ly alpha emission from Jupiter's aurora

    NASA Technical Reports Server (NTRS)

    Clarke, John T.; Trauger, John; Waite, J. Hunter, Jr.

    1989-01-01

    High-spectral-resolution IUE observations of the aurora on Jupiter were obtained in order to search for Doppler shifted H-Ly-alpha emission produced through charge exchange by fast precipitating protons. Although no emission has been observed corresponding to proton energies greater than 200 eV, a large fraction of the H-Ly-alpha emission has appeared Doppler shifted, mainly toward the blue, by about 50 km/s. These results show that the acceleration of ionospheric plasma in an H2 atmosphere can lead to bright Ly-alpha emission, setting constraints on the production of the outer planet airglow emissions.

  1. Ground-Based Observations of Recovery Phase Aurora

    NASA Technical Reports Server (NTRS)

    Jones, Sarah L.

    2012-01-01

    This analysis focuses on spatial and temporal forms occurring after substorm breakup. The observations show irregular shapes and nonuniform drifts with respect to relatively stationary pulsating patches. The pulsating patches occur within a diffuse auroral background as a modulation of the auroral brightness in a localized region. The images analyzed show a decrease in the brightness of the diffuse background in the region of the pulsating patch at the beginning of the 'off' phase of the modulation. Throughout the off phase the brightness of the diffuse aurora gradually increases back to the average intensity. The time constant for this increase is measured as the first step toward determining the physical process.

  2. On intense diverging electric field associated with black aurora

    SciTech Connect

    Marklund, G.; Blomberg, L.; Faelthammar, C.G.; Lindqvist, P.A.

    1994-08-15

    The authors present measurements made from the double-probe electric field instrument on the Freja satellite of a very intense electric field event seen in the auroral oval. The electric field measurements are correlated with potential, charged particle, and wave activity measurements. They see two very narrow electric field events separated by approximately 5 km, having field strengths near 1 V/m. These structures are seen to be associated with an excess of positive charge, to be associated with no electron precipitation, with slight plasma depletions, and with wave activity. The authors suggest these structures are black aurorae, with a total absence of auroral emissions.

  3. Aurora-A Oncogene in Human Ovarian Cancer

    DTIC Science & Technology

    2006-11-01

    in Human Ovarian Cancer 5b. GRANT NUMBER W81XWH-05-1-0021 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Jin Q. Cheng, M.D...this project : 1) examine the clinicalpathological significance and the mechanism of Aurora-A overexpression/activation in ovarian cancer; 2) determine...kinase is required to localize D-TACC to centro- somes and to regulate astral microtubules. J Cell Biol 2002;156:437–51. 33. Castro A, Mandart E, Lorca T

  4. Artificial auroras in the upper atmosphere. I - Electron beam injections

    NASA Technical Reports Server (NTRS)

    Burch, J. L.; Mende, S. B.; Kawashima, N.; Roberts, W. T.; Taylor, W. W. L.; Neubert, T.; Gibson, W. C.; Marshall, J. A.; Swenson, G. R.

    1993-01-01

    The Atlas-1 Spacelab payload's Space Experiments with Particle Accelerators generated artificial electron beams for the stimulation of auroral emissions at southern auroral latitudes. Optical measurements were made by the Shuttle Orbiter's onboard TV cameras, as well as by the Atmospheric Emissions Photometric Imager (in both white light and the 427.8 nm N2(+) emission line). Shuttle-based auroral imaging furnished a novel perspective on the artificial auroras; the emissions were traced from 295 km to the 110 km level along the curved magnetic-field lines.

  5. Portable parallel portfolio optimization in the Aurora Financial Management System

    NASA Astrophysics Data System (ADS)

    Laure, Erwin; Moritsch, Hans

    2001-07-01

    Financial planning problems are formulated as large scale, stochastic, multiperiod, tree structured optimization problems. An efficient technique for solving this kind of problems is the nested Benders decomposition method. In this paper we present a parallel, portable, asynchronous implementation of this technique. To achieve our portability goals we elected the programming language Java for our implementation and used a high level Java based framework, called OpusJava, for expressing the parallelism potential as well as synchronization constraints. Our implementation is embedded within a modular decision support tool for portfolio and asset liability management, the Aurora Financial Management System.

  6. Basal aurora kinase B activity is sufficient for histone H3 phosphorylation in prophase.

    PubMed

    Le, Ly-Thuy-Tram; Vu, Hong-Lien; Nguyen, Chi-Hung; Molla, Annie

    2013-04-15

    Histone H3 phosphorylation is the hallmark of mitosis deposited by aurora kinase B. Benzo[e]pyridoindoles are a family of potent, broad, ATP-competitive aurora kinase inhibitors. However, benzo[e]pyridoindole C4 only inhibits histone H3 phosphorylation in prophase but not in metaphase. Under the C4 treatment, the cells enter into mitosis with dephosphorylated histone H3, assemble chromosomes normally and progress to metaphase, and then to anaphase. C4 also induces lagging chromosome in anaphase but we demonstrated that these chromosome compaction defects are not related to the absence of H3 phosphorylation in prophase. As a result of C4 action, mitosis lasts longer and the cell cycle is slowed down. We reproduced the mitotic defects with reduced concentrations of potent pan aurora kinase as well as with a specific aurora B ATP-competitive inhibitor; we therefore propose that histone H3 phosphorylation and anaphase chromosome compaction involve the basal activity of aurora kinase B. Our data suggest that aurora kinase B is progressively activated at mitosis entry and at anaphase onset. The full activation of aurora kinase B by its partners, in prometaphase, induces a shift in the catalytic domain of aurora B that modifies its affinity for ATP. These waves of activation/deactivation of aurora B correspond to different conformations of the chromosomal complex revealed by FRAP. The presence of lagging chromosomes may have deleterious consequences on the daughter cells and, unfortunately, the situation may be encountered in patients receiving treatment with aurora kinase inhibitors.

  7. Dynamic properties of throat aurora revealed by simultaneous ground and satellite observations

    NASA Astrophysics Data System (ADS)

    Chen, X.-C.; Han, D.-S.; Lorentzen, D. A.; Oksavik, K.; Moen, J. I.; Baddeley, L. J.

    2017-03-01

    Throat aurora is defined as south-north aligned auroral arcs equatorward of the dayside cusp aurora and was suggested to be the results of cold magnetospheric plasma interaction with magnetopause reconnection, but its observational properties have not yet been well established. In this paper we carefully examine a sequence of throat auroras observed over Svalbard on 27 December 2003. Observations from 630.0 nm [OI] show that poleward moving throat auroras frequently show brightening followed by dimming in auroral intensity, and sometimes, the brightening throat aurora is a precursor of poleward moving auroral forms. Simultaneous all-sky images and HF radar backscatter observations along geomagnetic meridian show that the throat aurora brightening is drifting with ionospheric E × B convection and is colocated with enhanced spectral width poleward of the convection reversal boundary (CRB), while its dimming tends to be in the vicinity of the CRB. This leads us to propose that the throat aurora brightening and dimming may be on the open and closed field lines, respectively. Particle data from NOAA 16 confirm that the dimming throat aurora is associated with precipitation of magnetosheath-like particles mixed with magnetospheric ions (>30 keV), which is characteristic of the low-latitude boundary layer. For particle data from Defense Meteorological Satellite Program F16, we notice that the dimming throat aurora is associated with lower fluxes of magnetosheath-like electrons accompanied with magnetospheric electrons, which is most likely on closed field lines. The dynamic properties of throat aurora presented in this paper are thus important to understand its generation mechanisms.

  8. Arsenic-induced Aurora-A activation contributes to chromosome instability and tumorigenesis

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Han; Tseng, Ya-Shih; Yang, Chao-Chun; Kao, Yu-Ting; Sheu, Hamm-Ming; Liu, Hsiao-Sheng

    2013-11-01

    Arsenic may cause serious environmental pollution and is a serious industrial problem. Depending on the dosage, arsenic may trigger the cells undergoing either proliferation or apoptosis-related cell death. Because of lack of the proper animal model to study arsenic induced tumorigenesis, the accurate risk level of arsenic exposure has not been determined. Arsenic shows genotoxic effect on human beings who uptake water contaminated by arsenic. Chromosome aberration is frequently detected in arsenic exposure-related diseases and is associated with increased oxidative stress and decreased DNA repairing activity, but the underlying mechanism remains elusive. Aurora-A is a mitotic kinase, over-expression of Aurora-A leads to centrosome amplification, chromosomal instability and cell transformation. We revealed that Aurora-A is over-expressed in the skin and bladder cancer patients from blackfoot-disease endemic areas. Our cell line studies reveal that arsenic exposure between 0.5 μM and 1 μM for 2-7 days are able to induce Aurora-A expression and activation based on promoter activity, RNA and protein analysis. Aurora-A overexpression further increases the frequency of unsymmetrical chromosome segregation through centrosome amplification followed by cell population accumulated at S phase in immortalized keratinocyte (HaCaT) and uroepithelial cells (E7). Furthermore, Aurora-A over-expression was sustained for 1-4 weeks by chronic treatment of immortalized bladder and skin cells with NaAsO2. Aurora-A promoter methylation and gene amplification was not detected in the long-term arsenic treated E7 cells. Furthermore, the expression level of E2F1 transcription factor (E2F1) is increased in the presence of arsenic, and arsenic-related Aurora-A over-expression is transcriptionally regulated by E2F1. We further demonstrated that overexpression of Aurora-A and mutant Ha-ras or Aurora-A and mutant p53 may act additively to trigger arsenic-related bladder and skin cancer

  9. Functional Significance of Aurora Kinases-p53 Protein Family Interactions in Cancer.

    PubMed

    Sasai, Kaori; Treekitkarnmongkol, Warapen; Kai, Kazuharu; Katayama, Hiroshi; Sen, Subrata

    2016-01-01

    Aurora kinases play critical roles in regulating spindle assembly, chromosome segregation, and cytokinesis to ensure faithful segregation of chromosomes during mitotic cell division cycle. Molecular and cell biological studies have revealed that Aurora kinases, at physiological levels, orchestrate complex sequential cellular processes at distinct subcellular locations through functional interactions with its various substrates. Aberrant expression of Aurora kinases, on the other hand, cause defects in mitotic spindle assembly, checkpoint response activation, and chromosome segregation leading to chromosomal instability. Elevated expression of Aurora kinases correlating with chromosomal instability is frequently detected in human cancers. Recent genomic profiling of about 3000 human cancer tissue specimens to identify various oncogenic signatures in The Cancer Genome Atlas project has reported that recurrent amplification and overexpression of Aurora kinase-A characterize distinct subsets of human tumors across multiple cancer types. Besides the well-characterized canonical pathway interactions of Aurora kinases in regulating assembly of the mitotic apparatus and chromosome segregation, growing evidence also supports the notion that deregulated expression of Aurora kinases in non-canonical pathways drive transformation and genomic instability by antagonizing tumor suppressor and exacerbating oncogenic signaling through direct interactions with critical proteins. Aberrant expression of the Aurora kinases-p53 protein family signaling axes appears to be critical in the abrogation of p53 protein family mediated tumor suppressor pathways frequently deregulated during oncogenic transformation process. Recent findings reveal the existence of feedback regulatory loops in mRNA expression and protein stability of these protein families and their consequences on downstream effectors involved in diverse physiological functions, such as mitotic progression, checkpoint response

  10. Functional Significance of Aurora Kinases–p53 Protein Family Interactions in Cancer

    PubMed Central

    Sasai, Kaori; Treekitkarnmongkol, Warapen; Kai, Kazuharu; Katayama, Hiroshi; Sen, Subrata

    2016-01-01

    Aurora kinases play critical roles in regulating spindle assembly, chromosome segregation, and cytokinesis to ensure faithful segregation of chromosomes during mitotic cell division cycle. Molecular and cell biological studies have revealed that Aurora kinases, at physiological levels, orchestrate complex sequential cellular processes at distinct subcellular locations through functional interactions with its various substrates. Aberrant expression of Aurora kinases, on the other hand, cause defects in mitotic spindle assembly, checkpoint response activation, and chromosome segregation leading to chromosomal instability. Elevated expression of Aurora kinases correlating with chromosomal instability is frequently detected in human cancers. Recent genomic profiling of about 3000 human cancer tissue specimens to identify various oncogenic signatures in The Cancer Genome Atlas project has reported that recurrent amplification and overexpression of Aurora kinase-A characterize distinct subsets of human tumors across multiple cancer types. Besides the well-characterized canonical pathway interactions of Aurora kinases in regulating assembly of the mitotic apparatus and chromosome segregation, growing evidence also supports the notion that deregulated expression of Aurora kinases in non-canonical pathways drive transformation and genomic instability by antagonizing tumor suppressor and exacerbating oncogenic signaling through direct interactions with critical proteins. Aberrant expression of the Aurora kinases–p53 protein family signaling axes appears to be critical in the abrogation of p53 protein family mediated tumor suppressor pathways frequently deregulated during oncogenic transformation process. Recent findings reveal the existence of feedback regulatory loops in mRNA expression and protein stability of these protein families and their consequences on downstream effectors involved in diverse physiological functions, such as mitotic progression, checkpoint response

  11. Magnetosphere-Ionosphere Energy Interchange in the Electron Diffuse Aurora

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Glocer, Alex; Himwich, E. W.

    2014-01-01

    The diffuse aurora has recently been shown to be a major contributor of energy flux into the Earth's ionosphere. Therefore, a comprehensive theoretical analysis is required to understand its role in energy redistribution in the coupled ionosphere-magnetosphere system. In previous theoretical descriptions of precipitated magnetospheric electrons (E is approximately 1 keV), the major focus has been the ionization and excitation rates of the neutral atmosphere and the energy deposition rate to thermal ionospheric electrons. However, these precipitating electrons will also produce secondary electrons via impact ionization of the neutral atmosphere. This paper presents the solution of the Boltzman-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E greater than 600 eV) and their ionosphere-magnetosphere coupling processes. In this article, we discuss for the first time how diffuse electron precipitation into the atmosphere and the associated secondary electron production participate in ionosphere-magnetosphere energy redistribution.

  12. Tracking patchy pulsating aurora through all-sky images

    NASA Astrophysics Data System (ADS)

    Grono, Eric; Donovan, Eric; Murphy, Kyle R.

    2017-07-01

    Pulsating aurora is frequently observed in the evening and morning sector auroral oval. While the precipitating electrons span a wide range of energies, there is increasing evidence that the shape of pulsating auroral patches is controlled by structures in near-equatorial cold plasma; these patches appear to move with convection, for example. Given the tremendous and rapidly increasing amount of auroral image data from which the velocity of these patches can be inferred, it is timely to develop and implement techniques for the automatic identification of pulsating auroral patch events in these data and for the automatic determination of the velocity of individual patches from that data. As a first step towards this, we have implemented an automatic technique for determining patch velocities from sequences of images from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) all-sky imager (ASI) and applied it to many pulsating aurora events. Here we demonstrate the use of this technique and present the initial results, including a comparison between ewograms (east-west keograms) and time series of patch position as determined by the algorithm. We discuss the implications of this technique for remote sensing convection in the inner magnetosphere.

  13. Neptune's inner magnetosphere and aurora: Energetic particle constraints

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Krimigis, S. M.; Acuna, M. H.

    1994-01-01

    A dramatic and peculiar dropout of greater than 500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 R(sub N) as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spehrical harmonic model 'O8'). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with maximum L excursions of the ring 1989N1R. The constraints also favor the se of the M2 magnetic field model (Selesnick, 1992) over the previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora.

  14. Imagers for the magnetosphere, aurora, and plasmasphere (IMAP)

    NASA Astrophysics Data System (ADS)

    Frank, Louis A.; Williams, Donald J.; Roelof, Edmond C.

    1993-07-01

    We propose a small Explorer (SMEX) IMAP mission to provide the first global magnetospheric images that will allow a systematic study of major regions of the magnetosphere, their dynamics and their interactions. The mission objective is to obtain simultaneous images of the inner magnetosphere (ring current and trapped particles), the plasmasphere, the aurora, and auroral upflowing ions. The four IMAP instruments are (1) a Low Energy Neutral Particle Imager (LENPI) for imaging H and O atoms, separately, in the energy range of approximately 1 - 30 keV, in several energy passbands, (2) an Energetic Neutral Particle Imager (ENPI) for imaging H atoms in the energy range approximately 15 keV - 200 keV and, separately, O atoms in the energy range approximately 60 keV - 200 keV, each in several energy passbands, (3) an Extreme-Ultraviolet Imager (EUVI) to obtain images of the plasmasphere (the distribution of cold He(superscript +)) using He(superscript +) (30.4-nm) emissions; and (4) a Far-Ultraviolet Imaging Monochromator (FUVIM) to provide images of the aurora and the geocorona. All images will be obtained with time and spatial resolutions appropriate to the global and macroscale structures to be observed. The results expected from IMAP will provide the first large-scale visualization of the ring current, the trapped ion populations, the plasmasphere, and the upflowing auroral ion population.

  15. X-ray scanning of overhead aurorae from rockets

    NASA Technical Reports Server (NTRS)

    Barcus, J. R.; Goldberg, R. A.; Gesell, L. H.

    1981-01-01

    Two Nike Tomahawk rocket payloads were launched into energetic auroral events in September, 1976 to investigate the structure of these events, as well as their effects on the atmosphere. X-ray scintillation detectors with energy discrimination in four ranges were used to measure the deposition of bremsstrahlung produced X-rays within the stratosphere and mesosphere. Iterative computer techniques were used to reconstruct X-ray source maps at 100 km, taking atmospheric absorption effects into account. Payload 18.178 was launched on September 21st into an aurora having two distinct azimuthal regions of optical brightness. The X-ray scanner detected the same features, and overlays of the X-ray source maps on all-sky photographs showed spatial coincidence of the X-ray with optical features at the lower energies (below 40 keV). Payload 18.179 was launched September 23rd into an aurora with a more diffuse character. The optical structure did not coincide as well with the measured X-ray structure. There was also an indication of a two-component spectrum for each event, with the hard component originating in the more diffuse, optically faint regions.

  16. Observation of pulsating aurora signatures in cosmic noise absorption data

    NASA Astrophysics Data System (ADS)

    Grandin, M.; Kero, A.; Partamies, N.; McKay, D.; Whiter, D.; Kozlovsky, A.; Miyoshi, Y.

    2017-06-01

    This study investigates the contribution of energetic (E > 30 keV) particle precipitation during a pulsating aurora event over Kilpisjärvi (L = 6.2) on 26 February 2014. It is based on the comparison of auroral blue-line emission (427.8 nm) data from an all-sky camera and cosmic noise absorption (CNA) data obtained from a multibeam experiment of the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) riometer. The data sets are compared for three KAIRA beams close to magnetic zenith. Results show a clear correlation between the measured CNA and the auroral blue-line emission during the event, for each beam. In addition, individual pulsations are observed for the first time in the cosmic noise absorption data measured by KAIRA and are found to be close-to-identical to the optical pulsations. This suggests that the modulation of electron precipitation during pulsating aurora takes place in a consistent way over a broad range of energies.

  17. Pulsations of the polar cusp aurora at Saturn

    NASA Astrophysics Data System (ADS)

    Palmaerts, B.; Radioti, A.; Roussos, E.; Grodent, D.; Gérard, J.-C.; Krupp, N.; Mitchell, D. G.

    2016-12-01

    The magnetospheric cusp is a region connecting the interplanetary environment to the ionosphere and enabling solar wind particles to reach the ionosphere. We report the detection of several isolated high-latitude auroral emissions with the Ultraviolet Imaging Spectrograph of the Cassini spacecraft. We suggest that these auroral spots, located in the dawn-to-noon sector and poleward of the main emission, are the ionospheric signatures of the magnetospheric cusp, in agreement with some previous observations with the Hubble Space Telescope. The high-latitude cusp auroral signature has been associated with high-latitude lobe reconnection in the presence of a southward interplanetary magnetic field. The occurrence rate of the polar cusp aurora suggests that lobe reconnection is frequent at Saturn. Several auroral imaging sequences reveal a quasiperiodic brightening of the polar cusp aurora with a period in the range of 60 to 70 min. Similar pulsations in the energetic electron fluxes and in the azimuthal component of the magnetic field are simultaneously observed by Cassini instruments, suggesting the presence of field-aligned currents. Pulsed dayside magnetopause reconnection is a likely common triggering process for the cusp auroral brightenings at Saturn and the quasiperiodic pulsations in the high-latitude energetic electron fluxes.

  18. Ultraviolet spectroscopy of the Jovian and Saturnian auroras

    NASA Technical Reports Server (NTRS)

    Durrance, S. T.; Feldman, P. D.; Moos, H. W.

    1982-01-01

    The results of a series of IUE observations of the north polar aurora obtained during a substantial fraction of one complete rotation of Jupiter are presented. From these data a spectrum of the aurora with high signal to noise ratio, and a resolution of about 8 A was obtained, making possible the identification of many H2 Lyman and Werner bands. The spectrum is of sufficient quality to provide reliable quantative data for a comparison with the model atmosphere calculations. The lack of an observable absorption signature makes it possible to set an upper limit on the column density of CH4 and C2H6 above the auroral emissions and hence an upper limit on the primary particle energies. A comparison of this spectrum with a laboratory spectrum of discharge excited H2 shows a remarkable similarity. The results of several IUE observations of the full disk of Saturn are also examined. The exposures were of approximately 2 hours each, and the H2 Lyman and Werner bands were observed near the north pole in two of them.

  19. Neptune's inner magnetosphere and aurora: Energetic particle constraints

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Krimigis, S. M.; Acuna, M. H.

    1994-01-01

    A dramatic and peculiar dropout of greater than 500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 R(sub N) as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spehrical harmonic model 'O8'). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with maximum L excursions of the ring 1989N1R. The constraints also favor the se of the M2 magnetic field model (Selesnick, 1992) over the previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora.

  20. Neptune's inner magnetosphere and aurora: Energetic particle constraints

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.; Krimigis, S. M.; Acuna, M. H.

    1994-08-01

    A dramatic and peculiar dropout of greater than 500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 RN as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spehrical harmonic model 'O8'). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with maximum L excursions of the ring 1989N1R. The constraints also favor the se of the M2 magnetic field model (Selesnick, 1992) over the previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora.

  1. Knockdown of Aurora-B inhibits the growth of non-small cell lung cancer A549 cells.

    PubMed

    Yu, Jing Jing; Zhou, Long Dian; Zhao, Tian Tian; Bai, Wei; Zhou, Jing; Zhang, Wei

    2015-09-01

    Elevated expression of Aurora-B affects cell apoptosis and proliferation in a variety of solid tumors. However, the role of Aurora-B has been poorly evaluated in non-small cell lung cancer (NSCLC). In the present study, it was found that Aurora-B was overexpressed in tissue specimens obtained from 174 patients with lung cancer. It was also demonstrated that knockdown of Aurora-B induces apoptosis and inhibits the growth of lung cancer A549 cells in vitro and in vivo. Furthermore, it was found that silencing Aurora-B decreased the activity of the phosphoinositide 3-kinase (PI3K)/AKT pathway. Therefore, it was concluded that knockdown of Aurora-B induces apoptosis and inhibits growth in NSCLC A549 cells, in addition to inhibiting the activity of the PI3K/AKT signaling pathway. Targeting Aurora-B may provide a novel target for lung cancer therapy.

  2. Aurora candidates from the chronicle of Qíng dynasty in several degrees of relevance

    NASA Astrophysics Data System (ADS)

    Kawamura, Akito D.; Hayakawa, Hisashi; Tamazawa, Harufumi; Miyahara, Hiroko; Isobe, Hiroaki

    2016-10-01

    We present the result of a survey of sunspots and auroras in Qíngshǐgǎo (清史稿), a draft chronicle of Qíng dynasty, for the period of 1559-1912 CE. This is a sequel to a series of works surveying historical sunspot and aurora records, and providing online data to the scientific community regarding the attained results. In total of this Qíngshǐgǎo survey, we found 111 records of night-sky luminous events with such keywords as vapor (氣, qì), cloud (雲, yún), and light (光, guāng), which may indicate auroras as well as some other phenomena. Similarly, a keyword survey for sunspots was conducted, but no sunspot record was found. In comparison with the aurora records in the western world, we found that 14 of the 111 records have a corresponding record of simultaneous observation in the western world, and hence are very likely to be aurora. In order to investigate the likeliness of the remainder of the record being aurora, we calculated the lunar age and the phase of a solar cycle for each record. After these calculations, a notable fraction of these records clustered near the full moon were to be found statistically doubtful in considerations with atmospheric optics; meanwhile, a few records of observations near the new moon could be more likely interpreted as being auroras, including three records during the Maunder minimum.

  3. Aurora kinase B/C inhibition impairs malignant glioma growth in vivo.

    PubMed

    Diaz, Roberto Jose; Golbourn, Brian; Shekarforoush, Maryam; Smith, Christian A; Rutka, James T

    2012-07-01

    Inhibition of Aurora kinase B has been evaluated as a therapy to block solid tumor growth in breast cancer, hepatocellular carcinoma, lung adenocarcinoma, and colorectal cancer models. Aurora kinase inhibitors are in early clinical trials for the treatment of leukemia. We hypothesized that Aurora B inhibition would reduce malignant glioma cell viability and result in impaired tumor growth in vivo. Aurora B expression is greater in cultured malignant glioma U251 cells compared to proliferating normal human astrocytes, and expression is maintained in U251 flank xenografts. Aurora B inhibition with AZD1152-HQPA blocked cell division in four different p53-mutant glioma cell lines (U251, T98G, U373, and U118). AZD1152-HQPA also inhibited Aurora C activation loop threonine autophosphorylation at the effective antiproliferative concentrations in vitro. Reduction in cell viability of U251 (p53(R273H)) cells was secondary to cytokinesis blockade and apoptosis induction following endoreplication. AZD1152-HQPA inhibited the growth of U251 tumor xenografts and resulted in an increase in tumor cell apoptosis both in vitro and in vivo. Subcutaneous administration of AZD1152-HQPA (25 mg/kg/day × 4 days; 2 cycles spaced 7 days apart) resulted in a prolongation in median survival after intracranial inoculation of U251 cells in mice (P = 0.025). This is the first demonstration that an Aurora kinase inhibitor can inhibit malignant glioma growth in vivo at drug doses that are clinically relevant.

  4. Phosphorylation of TPX2 by Plx1 enhances activation of Aurora A.

    PubMed

    Eckerdt, Frank; Pascreau, Gaetan; Phistry, Meridee; Lewellyn, Andrea L; DePaoli-Roach, Anna A; Maller, James L

    2009-08-01

    Entry into mitosis requires the activation of mitotic kinases, including Aurora A and Polo-like kinase 1 (Plk1). Increased levels of these kinases are frequently found associated with human cancers, and therefore it is imperative to understand the processes leading to their activation. We demonstrate that TPX2, but neither Ajuba nor Inhibitor-2, can activate Aurora A directly. Moreover, Plx1 can induce Aurora A T-loop phosphorylation indirectly in vivo during oocyte maturation. We identify Ser204 in TPX2 as a Plx1 phosphorylation site. Mutating Ser204 to alanine decreases activation of Aurora A, whereas a phosphomimetic Asp mutant exhibits enhanced activating ability. Finally, we show that phosphorylation of TPX2 with Plx1 increases its ability to activate Aurora A. Taken together, our data indicate that Plx1 promotes activation of Aurora A, most likely through TPX2. In light of the current literature, we propose a model in which Plx1 and Aurora A activate each other in a positive feedback loop.

  5. Proton Aurora Dynamics in Response to the IMF and Solar Wind Variations

    NASA Technical Reports Server (NTRS)

    Chang, S.; Mende, S.; Frey, H.; Gallagher, D. L.; Lepping, R. P.; Six, N. Frank (Technical Monitor)

    2002-01-01

    On May 23, 2000, proton auroras observed by IMAGE (Imager for Magnetopause to Aurora Global Exploration) FUV (Far Ultraviolet) on the dayside were very dynamic. Auroral pattern in the cusp is well correlated with Interplanetary Magnetic Field (IMF) and solar wind parameters. When IMF were northward, cusp proton aurora appeared at high latitude poleward from the auroral oval. A high-latitude proton aurora brightened after solar wind ion temperature increased and it disappeared after IMF turned southward. Under the southward IMF condition, auroral activity occurred only in the dayside auroral oval. As IMF $B_z$ reverted to northward, cusp proton aurora reappeared at high latitude. The magnetic local time of the cusp proton aurora changes with the IMF $B_y$ polarity, consistent with previous reports. These results suggest an upstream source of the high-latitude cusp proton aurora for this event. One possible explanation is that bow shock energetic ions are transported into the cusp via the high-latitude magnetic merging process to induce optical emissions in the ionosphere.

  6. A specific pharmacophore model of Aurora B kinase inhibitors and virtual screening studies based on it.

    PubMed

    Wang, Hui-Yuan; Li, Lin-Li; Cao, Zhi-Xing; Luo, Shi-Dong; Wei, Yu-Quan; Yang, Sheng-Yong

    2009-01-01

    In this study, 3D-pharmacophore models of Aurora B kinase inhibitors have been developed by using HipHop and HypoGen modules in Catalyst software package. The best pharmacophore model, Hypo1, which has the highest correlation coefficient (0.9911), consists of one hydrogen-bond acceptor, one hydrogen-bond donor, one hydrophobic aliphatic moiety and one ring aromatic feature. Hypo1 was validated by test set and cross-validation methods. And the specificity of Hypo1 to Aurora B inhibitors was examined with the use of selective inhibitors against Aurora B and its paralogue Aurora A. The results clearly indicate that Hypo1 can differentiate selective inhibitors of Aurora B from those of Aurora A, and the ring aromatic feature likely plays some important roles for the specificity of Hypo1. Then Hypo1 was used as a 3D query to screen several databases including Specs, NCI, Maybridge and Chinese Nature Product Database (CNPD) for identifying new inhibitors of Aurora B. The hit compounds were subsequently subjected to filtering by Lipinski's rule of five and docking studies to refine the retrieved hits, and some compounds selected from the top ranked hits have been suggested for further experimental assay studies.

  7. A Statistical Study of Pulsating Aurora using THEMIS All-sky Ground Imagers

    NASA Astrophysics Data System (ADS)

    Rychert, K. M.; Jones, S.; Lessard, M.; Donovan, E. F.; Spanswick, E. L.

    2009-12-01

    Pulsating aurora is a common phenomenon that occurs primarily in the aftermath of substorms where dim, long period pulsating patches appear. Previous studies on pulsating aurora have used minimal data sets to investigate pulsation periods and MLAT distribution. None of these studies were based on very large data sets, as we now have available. In this study, which includes over half a year of optical data, we determine occurrence rates of pulsating aurora in terms of magnetic latitude and local time, pulsating auroral onsets at different stations to show temporal evolution, relationship to substorms, etc. Preliminary results obtained from the Gillam All-Sky Camera (66°N, 327°E) over 119 days with good optical data beginning September 2007 through the end of March 2008, 74 of which contain pulsating aurora, include: 31.48% of all clear optical data exhibits pulsating aurora, 68.75% of all optically observed pulsating aurora onsets occur post substorm breakup, and a greater likelihood for observing pulsating aurora after midnight (54% probability versus a 14% probability before midnight)

  8. Proton Aurora Dynamics in Response to the IMF and Solar Wind Variations

    NASA Technical Reports Server (NTRS)

    Chang, S.; Mende, S.; Frey, H.; Gallagher, D. L.; Lepping, R. P.; Six, N. Frank (Technical Monitor)

    2002-01-01

    On May 23, 2000, proton auroras observed by IMAGE (Imager for Magnetopause to Aurora Global Exploration) FUV (Far Ultraviolet) on the dayside were very dynamic. Auroral pattern in the cusp is well correlated with Interplanetary Magnetic Field (IMF) and solar wind parameters. When IMF were northward, cusp proton aurora appeared at high latitude poleward from the auroral oval. A high-latitude proton aurora brightened after solar wind ion temperature increased and it disappeared after IMF turned southward. Under the southward IMF condition, auroral activity occurred only in the dayside auroral oval. As IMF $B_z$ reverted to northward, cusp proton aurora reappeared at high latitude. The magnetic local time of the cusp proton aurora changes with the IMF $B_y$ polarity, consistent with previous reports. These results suggest an upstream source of the high-latitude cusp proton aurora for this event. One possible explanation is that bow shock energetic ions are transported into the cusp via the high-latitude magnetic merging process to induce optical emissions in the ionosphere.

  9. RNA interference targeting Aurora-A sensitizes glioblastoma cells to temozolomide chemotherapy.

    PubMed

    Gan, Jing; Wang, Fangfang; Mu, Dezhi; Qu, Yi; Luo, Rong; Wang, Qiu

    2016-12-01

    Clinically, temozolomide (TMZ) is widely used in glioblastoma (GBM) treatment. However, the toxicity of TMZ may influence the quality of patient life. Thus, novel treatment options for sensitizing GBM cells to TMZ chemotherapy are necessary. Aurora-A is widely expressed in GBM and correlated with poor prognosis. It has been proven to be an effective target for gene therapy and chemotherapy. In the present study, short hairpin (sh)RNA targeting Aurora-A was employed to knockdown Aurora-A expression in GBM cells. Cell Counting Kit-8 assays, flow cytometry, colony formation assays, invasion assays and tube formation assays were used to determine the effects of Aurora-A knockdown when combined with TMZ treatment. A U251 subcutaneous cancer model was established to evaluate the efficacy of combined therapy. The results of the present study indicated that the proliferation, colony formation, invasion and angiogenesis of GBM cells were significantly inhibited by combined therapy when compared with TMZ treatment alone. In vivo results demonstrated that knockdown of Aurora-A significantly (P=0.0084) sensitizes GBM cells to TMZ chemotherapy. The results of the present study demonstrated that knockdown of Aurora-A in GBM cells enhances TMZ sensitivity in vitro and in vivo. Therefore, Aurora-A knockdown may be a novel treatment option for decreasing TMZ toxicity and improving patient quality of life.

  10. Effects of KRC-108 on the Aurora A activity and growth of colorectal cancer cells.

    PubMed

    Chung, Hye Jin; Park, Kyeong Ryang; Lee, Hyo Jeong; Lee, Jongkook; Kim, Jeong-Hyun; Kim, Yong-Chul; Han, Sun-Young

    2015-06-12

    Aurora A is involved in regulating multiple steps of mitosis. Over-expression of Aurora A is related to tumorigenesis and poor prognosis. KRC-108 is a novel multi-kinase inhibitor which has anti-tumor activity in vivo. In this study, we identified the inhibitory effects of KRC-108 on Aurora A kinase and growth-inhibitory characteristics of KRC-108. The in vitro kinase activity assay, immunoblot, and immunofluorescence analyses demonstrated that KRC-108 inhibited Aurora A activity. KRC-108 exhibited cytotoxicity against human colorectal cancer cell line HT-29. Colony formation assays showed that KRC-108 reduced the colony growth of HT-29 cells. KRC-108 also inhibited migration of HT-29 cells. The expression levels of cyclin B1 and CDC2 were decreased by KRC-108 in HT-29 cells. Cell cycle analysis and flow cytometry indicated that the inhibitory effects of KRC-108 on cell growth are due to induction of G2/M arrest and apoptosis by inhibition of Aurora A. KRC-108 induces cell-cycle arrest and apoptosis in colorectal cancer cell line by Aurora A inhibition. The reported in vivo anti-tumor effects of KRC-108 might partly be due to anti-Aurora A effects. This study suggests that KRC-108 has potential for development as an anti-tumor agent, although further studies are needed.

  11. Aurora-A shines on T cell activation through the regulation of Lck.

    PubMed

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Martín-Cófreces, Noa B; Sánchez-Madrid, Francisco

    2017-02-01

    Different protein kinases control signaling emanating from the T cell receptor (TCR) during antigen-specific T cell activation. Mitotic kinases, e.g. Aurora-A, have been widely studied in the context of mitosis due to their role during microtubule (MT) nucleation, becoming critical regulators of cell cycle progression. We have recently described a specific role for Aurora-A kinase in antigenic T cell activation. Blockade of Aurora-A in T cells severely disrupts the dynamics of MTs and CD3ζ-bearing signaling vesicles during T cell activation. Furthermore, Aurora-A deletion impairs the activation of signaling molecules downstream of the TCR. Targeting Aurora-A disturbs the activation of Lck, which is one of the first signals that drive T cell activation in an antigen-dependent manner. This work describes possible models of regulation of Lck by Aurora-A during T cell activation. We also discuss possible roles for Aurora-A in other systems similar to the IS, and its putative functions in cell polarization.

  12. A coordinated X-ray and EUV study of the Jovian aurora

    NASA Astrophysics Data System (ADS)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randall; Badman, Sarah; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen; Rodiger, Elke; Tsuchiya, Fuminori; Yamazaki, Atsushi; Yoshikawa, Ichiro; Yoshioka, Kazuo

    2015-04-01

    We present results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument and twice by XMM-Newton for roughly 12 hours per observation. The goal of this campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  13. AIP regulates stability of Aurora-A at early mitotic phase coordinately with GSK-3beta.

    PubMed

    Fumoto, K; Lee, P-C; Saya, H; Kikuchi, A

    2008-07-24

    Glycogen synthase kinase-3 (GSK-3beta) regulates microtubule dynamics and cellular polarity through phosphorylating various microtubule associating proteins and plus-end tracking proteins. Although it was also reported that GSK-3beta is inactivated by protein kinase B at the spindle poles, functions and targets of GSK-3beta in the mitotic phase are unknown. Here, we identified Aurora-A-interacting protein (AIP), a negative regulator of Aurora-A, as a binding partner of GSK-3beta. AIP was colocalized with Aurora-A and GSK-3beta to the spindle poles in metaphase, and its depletion in cells stabilized and activated Aurora-A in early mitotic phase and caused mitotic cell arrest. Treatment of the cells with a GSK-3beta inhibitor reduced the protein level of Aurora-A and this reduction was suppressed by AIP knockdown. AIP was phosphorylated by GSK-3beta, and an AIP mutant in which the GSK-3beta phosphorylation site was mutated could bind and downregulate Aurora-A more efficiently. These results suggest that GSK-3beta modulates the early mitotic Aurora-A level through binding and phosphorylating AIP.

  14. Identification and Dynamics of Two Classes of Aurora-Like Kinases in Arabidopsis and Other PlantsW⃞

    PubMed Central

    Demidov, Dmitri; Van Damme, Daniël; Geelen, Danny; Blattner, Frank R.; Houben, Andreas

    2005-01-01

    Aurora-like kinases play key roles in chromosome segregation and cytokinesis in yeast, plant, and animal systems. Here, we characterize three Arabidopsis thaliana protein kinases, designated AtAurora1, AtAurora2, and AtAurora3, which share high amino acid identities with the Ser/Thr kinase domain of yeast Ipl1 and animal Auroras. Structure and expression of AtAurora1 and AtAurora2 suggest that these genes arose by a recent gene duplication, whereas the diversification of plant α and β Aurora kinases predates the origin of land plants. The transcripts and proteins of all three kinases are most abundant in tissues containing dividing cells. Intracellular localization of green fluorescent protein–tagged AtAuroras revealed an AtAurora-type specific association mainly with dynamic mitotic structures, such as microtubule spindles and centromeres, and with the emerging cell plate of dividing tobacco (Nicotiana tabacum) BY-2 cells. Immunolabeling using AtAurora antibodies yielded specific signals at the centromeres that are coincident with histone H3 that is phosphorylated at Ser position10 during mitosis. An in vitro kinase assay demonstrated that AtAurora1 preferentially phosphorylates histone H3 at Ser 10 but not at Ser 28 or Thr 3, 11, and 32. The phylogenetic analysis of available Aurora sequences from different eukaryotic origins suggests that, although a plant Aurora gene has been duplicated early in the evolution of plants, the paralogs nevertheless maintained a role in cell cycle–related signal transduction pathways. PMID:15722465

  15. Effects of selective inhibitors of Aurora kinases on anaplastic thyroid carcinoma cell lines.

    PubMed

    Baldini, Enke; Tuccilli, Chiara; Prinzi, Natalie; Sorrenti, Salvatore; Antonelli, Alessandro; Gnessi, Lucio; Morrone, Stefania; Moretti, Costanzo; Bononi, Marco; Arlot-Bonnemains, Yannick; D'Armiento, Massimino; Ulisse, Salvatore

    2014-10-01

    Aurora kinases are serine/threonine kinases that play an essential role in cell division. Their aberrant expression and/or function induce severe mitotic abnormalities, resulting in either cell death or aneuploidy. Overexpression of Aurora kinases is often found in several malignancies, among which is anaplastic thyroid carcinoma (ATC). We have previously demonstrated the in vitro efficacy of Aurora kinase inhibitors in restraining cell growth and survival of different ATC cell lines. In this study, we sought to establish which Aurora might represent the preferential drug target for ATC. To this end, the effects of two selective inhibitors of Aurora-A (MLN8237) and Aurora-B (AZD1152) on four human ATC cell lines (CAL-62, BHT-101, 8305C, and 8505C) were analysed. Both inhibitors reduced cell proliferation in a time- and dose-dependent manner, with IC50 ranges of 44.3-134.2 nM for MLN8237 and of 9.2-461.3 nM for AZD1152. Immunofluorescence experiments and time-lapse videomicroscopy yielded evidence that each inhibitor induced distinct mitotic phenotypes, but both of them prevented the completion of cytokinesis. As a result, poliploidy increased in all AZD1152-treated cells, and in two out of four cell lines treated with MLN8237. Apoptosis was induced in all the cells by MLN8237, and in BHT-101, 8305C, and 8505C by AZD1152, while CAL-62 exposed to AZD1152 died through necrosis after multiple rounds of endoreplication. Both inhibitors were capable of blocking anchorage-independent cell growth. In conclusion, we demonstrated that either Aurora-A or Aurora-B might represent therapeutic targets for the ATC treatment, but inhibition of Aurora-A appears more effective for suppressing ATC cell proliferation and for inducing the apoptotic pathway.

  16. MLN-8237: A dual inhibitor of aurora A and B in soft tissue sarcomas.

    PubMed

    Nair, Jayasree S; Schwartz, Gary K

    2016-03-15

    Aurora kinases have become an attractive target in cancer therapy due to their deregulated expression in human tumors. Liposarcoma, a type of soft tissue sarcoma in adults, account for approximately 20% of all adult soft tissue sarcomas. There are no effective chemotherapies for majority of these tumors. Efforts made to define the molecular basis of liposarcomas lead to the finding that besides the amplifications of CDK4 and MDM2, Aurora Kinase A, also was shown to be overexpressed. Based on these as well as mathematic modeling, we have carried out a successful preclinical study using CDK4 and IGF1R inhibitors in liposarcoma. MLN8237 has been shown to be a potent and selective inhibitor of Aurora A. MLN-8237, as per our results, induces a differential inhibition of Aurora A and B in a dose dependent manner. At a low nanomolar dose, cellular effects such as induction of phospho-Histone H3 (Ser10) mimicked as that of the inhibition of Aurora kinase A followed by apoptosis. However, micromolar dose of MLN-8237 induced polyploidy, a hallmark effect of Aurora B inhibition. The dose dependent selectivity of inhibition was further confirmed by using siRNA specific inhibition of Aurora A and B. This was further tested by time lapse microscopy of GFP-H2B labelled cells treated with MLN-8237. LS141 xenograft model at a dose of 30 mg/kg also showed efficient growth suppression by selective inhibition of Aurora Kinase A. Based on our data, a dose that can target only Aurora A will be more beneficial in tumor suppression.

  17. MLN-8237: A dual inhibitor of aurora A and B in soft tissue sarcomas

    PubMed Central

    Nair, Jayasree S.; Schwartz, Gary K.

    2016-01-01

    Aurora kinases have become an attractive target in cancer therapy due to their deregulated expression in human tumors. Liposarcoma, a type of soft tissue sarcoma in adults, account for approximately 20% of all adult soft tissue sarcomas. There are no effective chemotherapies for majority of these tumors. Efforts made to define the molecular basis of liposarcomas lead to the finding that besides the amplifications of CDK4 and MDM2, Aurora Kinase A, also was shown to be overexpressed. Based on these as well as mathematic modeling, we have carried out a successful preclinical study using CDK4 and IGF1R inhibitors in liposarcoma. MLN8237 has been shown to be a potent and selective inhibitor of Aurora A. MLN-8237, as per our results, induces a differential inhibition of Aurora A and B in a dose dependent manner. At a low nanomolar dose, cellular effects such as induction of phospho-Histone H3 (Ser10) mimicked as that of the inhibition of Aurora kinase A followed by apoptosis. However, micromolar dose of MLN-8237 induced polyploidy, a hallmark effect of Aurora B inhibition. The dose dependent selectivity of inhibition was further confirmed by using siRNA specific inhibition of Aurora A and B. This was further tested by time lapse microscopy of GFP-H2B labelled cells treated with MLN-8237. LS141 xenograft model at a dose of 30 mg/kg also showed efficient growth suppression by selective inhibition of Aurora Kinase A. Based on our data, a dose that can target only Aurora A will be more beneficial in tumor suppression. PMID:26887042

  18. Disease associated with integumentary and cloacal parasites in tadpoles of northern red-legged frog Rana aurora aurora.

    PubMed

    Nieto, Nathan C; Camann, Michael A; Foley, Janet E; Reiss, John O

    2007-10-31

    A total of 6830 northern red-legged frog Rana aurora aurora tadpoles were examined under a dissecting microscope for oral disc, integumentary, and cloacal abnormalities in 13 ponds in and near Redwood National Park in northern California. Of these, 163 tadpoles were collected for histopathological investigation, including 115 randomly collected individuals, 38 collected with oral disc abnormalities, and 10 collected due to severe morbidity of unknown etiology. The tadpoles were infected with 8 parasites, including Batrachochytrium dendrobatidis (the amphibian chytrid), trematodes, leeches, and protozoa. Chytridiomycosis was detected at an overall prevalence of 6.4%, but prevalence was higher in tadpoles with oral disc lesions than in those with normal oral discs (43.5% versus 6.1%). Interestingly, infection was associated with some environmental and co-infection risk factors. Individual tadpoles possessed 0 to 5 species of parasites in varying intensities. Apiosoma sp. was the most prevalent (66%) and widespread. Tadpoles infected with B. dendrobatidis had a lower diversity of oral parasites than those uninfected. During the field portion of the study, a large number (approximately 500) of moribund and dead tadpoles was seen occurring at multiple locations within and surrounding Redwood National Park. Ten animals were collected for histological examination and a diverse protozoal infection was discovered, including some known pathogens of fish. This study is the first reporting parasitism and disease in natural populations of northern red-legged frogs.

  19. E region neutral winds in the postmidnight diffuse aurora during the Atmospheric Response in Aurora 1 rocket campaign

    NASA Astrophysics Data System (ADS)

    Brinkman, D. G.; Walterscheid, R. L.; Lyons, L. R.; Kayser, D. C.; Christensen, A. B.; Sharber, J. R.; Frahm, R. A.; Larsen, M. F.

    1995-09-01

    Measured E region neutral winds from the Atmospheric Response in Aurora (ARIA 1) rocket campaign are compared with winds predicted by a high-resolution nonhydrostatic dynamical thermosphere model. The ARIA 1 rockets were launched into the postmidnight diffuse aurora during the recovery phase of a substorm. Simulations have shown that electrodynamical coupling between the auroral ionosphere and the thermosphere was expected to be strong during active diffuse auroral conditions (Walterscheid and Lyons, 1989). This is the first time that simulations using the time history of detailed specifications of the magnitude and latitudinal variation of the auroral forcing based on measurements have been compared to simultaneous wind measurements. Model inputs included electron densities derived from ground-based airglow measurements, precipitating electron fluxes measured by the rocket, electron densities measured on the rocket, electric fields derived from magnetometer and satellite ion drift measurements, and large-scale background winds from a thermospheric general circulation model. Our model predicted a strong jet of eastward winds at E region heights. A comparison between model predicted and observed winds showed modest agreement. Above 135 km the model predicted zonal winds with the correct sense, the correct profile shape, and the correct altitude of the peak wind. However, it overpredicted the magnitude of the eastward winds by more than a factor or 2. For the meridional winds the model predicted the general sense of the winds but was unable to predict the structure or strength of the winds seen in the observations. Uncertainties in the magnitude and latitudinal structure of the electric field and in the magnitude of the background winds are the most likely sources of error contributing to the differences between model and observed winds. Between 110 and 135 km the agreement between the model and observations was poor because of a large unmodeled jetlike feature in

  20. Click approach to the discovery of 1,2,3-triazolylsalicylamides as potent Aurora kinase inhibitors.

    PubMed

    Song, Doohee; Park, Yunjeong; Yoon, Jieun; Aman, Waqar; Hah, Jung-Mi; Ryu, Jae-Sang

    2014-09-01

    A series of 1,2,3-triazolylsalicylamide derivatives has been developed from the antiproliferative agent 7 and was evaluated for their Aurora kinase inhibitory activity. The novel 1,2,3-triazolylsalicylamide scaffold could be readily assembled by Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition, allowing rapid access to the structurally diverse analogues. The synthesized 1,2,3-triazolylsalicylamide derivatives revealed a significant Aurora kinase inhibitory activity. In particular, 8g inhibited Aurora A with IC50 values of 0.37μM. The critical role of phenolic -OH in the binding was confirmed by a molecular modeling study.

  1. Arsenic treatment increase Aurora-A overexpression through E2F1 activation in bladder cells.

    PubMed

    Kao, Yu-Ting; Wu, Chin-Han; Wu, Shan-Ying; Lan, Sheng-Hui; Liu, Hsiao-Sheng; Tseng, Ya-Shih

    2017-04-18

    Arsenic is a widely distributed metalloid compound that has biphasic effects on cultured cells. In large doses, arsenic can be toxic enough to trigger cell death. In smaller amounts, non-toxic doses may promote cell proliferation and induces carcinogenesis. Aberration of chromosome is frequently detected in epithelial cells and lymphocytes of individuals from arsenic contaminated areas. Overexpression of Aurora-A, a mitotic kinase, results in chromosomal instability and cell transformation. We have reported that low concentration (≦1 μM) of arsenic treatment increases Aurora-A expression in immortalized bladder urothelial E7 cells. However, how arsenic induces carcinogenesis through Aurora-A activation remaining unclear. Bromodeoxyuridine (BrdU) staining, MTT assay, and flow cytometry assay were conducted to determine cell proliferation. Messenger RNA and protein expression levels of Aurora-A were detected by reverse transcriptional-PCR and Western blotting, respectively. Centrosome of cells was observed by immunofluorescent staining. The transcription factor of Aurora-A was investigated by promoter activity, chromosome immunoprecipitation (ChIP), and small interfering RNA (shRNA) assays. Mouse model was utilized to confirm the relationship between arsenic and Aurora-A. We reveal that low dosage of arsenic treatment increased cell proliferation is associated with accumulated cell population at S phase. We also detected increased Aurora-A expression at mRNA and protein levels in immortalized bladder urothelial E7 cells exposed to low doses of arsenic. Arsenic-treated cells displayed increased multiple centrosome which is resulted from overexpressed Aurora-A. Furthermore, the transcription factor, E2F1, is responsible for Aurora-A overexpression after arsenic treatment. We further disclosed that Aurora-A expression and cell proliferation were increased in bladder and uterus tissues of the BALB/c mice after long-term arsenic (1 mg/L) exposure for 2 months. We

  2. Overexpression of Aurora-A kinase promotes tumor cell proliferation and inhibits apoptosis in esophageal squamous cell carcinoma cell line.

    PubMed

    Wang, Xiao Xia; Liu, Rong; Jin, Shun Qian; Fan, Fei Yue; Zhan, Qi Min

    2006-04-01

    Aurora-A kinase, a serine/threonine protein kinase, is a potential oncogene. Amplification and overexpression of Aurora-A have been found in several types of human tumors, including esophageal squamous cell carcinoma (ESCC). It has been demonstrated that cells overexpressing Aurora-A are more resistant to cisplatin-induced apoptosis. However, the molecular mechanisms mediating these effects remain largely unknown. In this report, we showed that overexpression of Aurora-A through stable transfection of pEGFP-Aurora-A in human ESCC KYSE150 cells significantly promoted cell proliferation and inhibited cisplatin- or UV irradiation-induced apoptosis. Cleavages of caspase-3 and poly (ADP-ribose) polymerase (PARP) in Aurora-A overexpressing cells were substantially reduced after cisplatin or UV treatment. Furthermore, we found that silencing of endogenous Aurora-A kinase with siRNA substantially enhanced sensitivity to cisplatin- or UV-induced apoptosis in human ESCC EC9706 cells. In parallel, overexpression of Aurora-A potently upregulated the expression of Bcl-2. Moreover, the knockdown of Bcl-2 by siRNA abrogated the Aurora-A's effect on inhibiting apoptosis. Taken together, these data provide evidence that Aurora-A overexpression promoting cell proliferation and inhibiting apoptosis, suggesting a novel mechanism that is closely related to malignant phenotype and anti-cancer drugs resistance of ESCC cells.

  3. The response of head and neck squamous cell carcinoma to cetuximab treatment depends on Aurora kinase A polymorphism

    PubMed Central

    Baumann, Alexander; Huhn, Maximilian; Wirth, Markus; Reiter, Rudolf; Rudelius, Martina; Piontek, Guido; Brockhoff, Gero

    2014-01-01

    Objectives The aim of this study was to evaluate the efficiency of cetuximab-based anti-EGFR treatment and Aurora kinase A / B knockdown as a function of Aurora kinase polymorphism in HNSCC cell lines. Materials and methods First, protein expression of Aurora kinase A / B and EGFR and Aurora kinase A polymorphism were studied in tumour samples. The survival and proliferation of Aurora kinase A homo- (Cal27) and heterozygous (HN) HNSCC cell lines was evaluated using a colony formation assay and a flow cytometric assay. Also, aneuploidy was determined. EGFR signalling pathway were visualised by western blotting. Results Immunohistochemistry revealed the overexpression of Aurora kinase A / B in HNSCC. The knockdown of each kinase caused a significant decrease in clonogenic survival, independent of Aurora kinase A polymorphism. In contrast, cetuximab treatment impaired clonogenic survival only in the Aurora kinase A-homozygous cell line (Cal27). Conclusion This study provides in vitro evidence for the predictive value of Aurora kinase A polymorphism in the efficiency of cetuximab treatment. Resistance to cetuximab treatment can be overcome by simultaneous Aurora kinase A/B knockdown. PMID:24980817

  4. The charge spectrum of positive ions in a hydrogen aurora

    NASA Technical Reports Server (NTRS)

    Lynch, J.; Pulliam, D.; Leach, R.; Scherb, F.

    1976-01-01

    An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

  5. The 300- to 900-A spectrum of a nightside aurora

    NASA Technical Reports Server (NTRS)

    Paresce, F.; Chakrabarti, S.; Kimble, R.; Bowyer, S.

    1983-01-01

    Attention is given to the results of a satellite observation of a nightside aurora. The observations had been made with the aid of an instrument which was designed specifically to detect and to measure accurately the intensity of features in a wavelength range from 300 to 900 A. The considered data were acquired by an EUV spectrometer on the USAF STP 78-1 satellite launched on February 24, 1979. A bright, discrete auroral arc was selected for study, taking into account the intense O II, 834 A emission line as the most distinctive auroral diagnostic feature in the wavelength region from 300 to 900 A. There is found to be an excellent correspondence between most of the auroral features and the brightest O II laboratory discharge emission lines.

  6. Limit on rotational energy available to excite Jovian aurora

    NASA Technical Reports Server (NTRS)

    Eviatar, A.; Siscoe, G. L.

    1980-01-01

    There is a fundamental relationship between the power that is extracted from Jupiter's rotation to drive magnetospheric processes and the rate at which mass is injected into the Io plasma torus. Half of this power is consumed by bulk motion of the plasma and the other half represents an upper limit on the energy from rotation available for dissipation and in particular to excite the Jovian aurora. Since the rotation of the planet is the only plausible source of energy, the power inferred from the observed auroral intensities requires a plasma injection rate of 2.6 x 10 to the 29th AMU/sec or greater. This in turn leads to a residence time of a torus particle of 48 days or less. These results raise doubts about the applicability of equilibrium thermodynamics to the determination of plasma parameters in the Io torus.

  7. The start of the Association's aurora & noctilucent cloud observations

    NASA Astrophysics Data System (ADS)

    Paton, J.; Gadsden, M.

    2003-02-01

    This document was found in a bundle of letters surfacing in 2001 in a file cabinet in the Edinburgh University Institute for Meteorology. The letters cover the period from 1964 to 1991; this text, undated, appears to date from 1972 or 1973. It was probably an aide-mémoire for presentation before the Geophysics National Committee of the Royal Society in London. James Paton was Director of the BAA Aurora Section from 1952 to 1973. His time as Director covered the great expansion of research into the upper atmosphere brought about by the International Geophysical Year (1957(1958), the International Year of Geophysical Cooperation (1959) and the International Years of the Quiet Sun (1964(1965).

  8. Limit on rotational energy available to excite Jovian aurora

    NASA Technical Reports Server (NTRS)

    Eviatar, A.; Siscoe, G. L.

    1980-01-01

    There is a fundamental relationship between the power that is extracted from Jupiter's rotation to drive magnetospheric processes and the rate at which mass is injected into the Io plasma torus. Half of this power is consumed by bulk motion of the plasma and the other half represents an upper limit on the energy from rotation available for dissipation and in particular to excite the Jovian aurora. Since the rotation of the planet is the only plausible source of energy, the power inferred from the observed auroral intensities requires a plasma injection rate of 2.6 x 10 to the 29th AMU/sec or greater. This in turn leads to a residence time of a torus particle of 48 days or less. These results raise doubts about the applicability of equilibrium thermodynamics to the determination of plasma parameters in the Io torus.

  9. Variability of Jupiter's IR H3+ aurorae during Juno approach

    NASA Astrophysics Data System (ADS)

    Moore, L.; O'Donoghue, J.; Melin, H.; Stallard, T.; Tao, C.; Zieger, B.; Clarke, J.; Vogt, M. F.; Bhakyapaibul, T.; Opher, M.; Tóth, G.; Connerney, J. E. P.; Levin, S.; Bolton, S.

    2017-05-01

    We present ground-based observations of Jupiter's H3+ aurorae over four nights in April 2016 while the Juno spacecraft was monitoring the upstream interplanetary magnetic field. High-precision maps of auroral H3+ densities, temperatures, and radiances reveal significant variabilities in those parameters, with regions of enhanced density and emission accompanied by reduced temperature. Juno magnetometer data, combined with solar wind propagation models, suggest that a shock may have impacted Jupiter in the days preceding the observation interval but that the solar wind was quiescent thereafter. Auroral H3+ temperatures reveal a downward temporal trend, consistent with a slowly cooling upper atmosphere, such as might follow a period of shock recovery. The brightest H3+ emissions are from the end of the period, 23 April. A lack of definitive signatures in the upstream interplanetary magnetic field lends supporting evidence to the possibility that this brightening event may have been driven by internal magnetospheric processes.

  10. Aurora on Uranus - A Faraday disc dynamo mechanism

    NASA Astrophysics Data System (ADS)

    Hill, T. W.; Dessler, A. J.; Rassbach, M. E.

    1983-10-01

    A mechanism is proposed whereby the solar wind flowing past the magnetosphere of Uranus causes a Faraday disk dynamo topology to be established and power to be extracted from the kinetic energy of rotation of Uranus. An immediate consequence of this dynamo is the generation of Birkeland currents that flow in and out of the sunlit polar cap with the accompanying production of polar aurora. The power extracted from planetary rotation is calculated as a function of planetary dipole magnetic moment and the ionospheric conductivity of Uranus. For plausible values of ionospheric conductivity, the observed auroral power requires a magnetic moment corresponding to a surface equatorial field of the order of 4 Gauss, slightly larger than the value 1.8 Gauss given by the empirical 'magnetic Bodes law'.

  11. The charge spectrum of positive ions in a hydrogen aurora

    NASA Technical Reports Server (NTRS)

    Lynch, J.; Pulliam, D.; Leach, R.; Scherb, F.

    1976-01-01

    An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

  12. Juno-UVS approach observations of Jupiter's auroras

    NASA Astrophysics Data System (ADS)

    Gladstone, G. R.; Versteeg, M. H.; Greathouse, T. K.; Hue, V.; Davis, M. W.; Gérard, J.-C.; Grodent, D. C.; Bonfond, B.; Nichols, J. D.; Wilson, R. J.; Hospodarsky, G. B.; Bolton, S. J.; Levin, S. M.; Connerney, J. E. P.; Adriani, A.; Kurth, W. S.; Mauk, B. H.; Valek, P.; McComas, D. J.; Orton, G. S.; Bagenal, F.

    2017-08-01

    Juno ultraviolet spectrograph (UVS) observations of Jupiter's aurora obtained during approach are presented. Prior to the bow shock crossing on 24 June 2016, the Juno approach provided a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions are expected to be controlled or modified by local solar wind conditions. Here we compare synoptic Juno-UVS observations of Jupiter's auroral emissions, acquired during 3-29 June 2016, with in situ solar wind observations, and related Jupiter observations from Earth. Four large auroral brightening events are evident in the synoptic data, in which the total emitted auroral power increases by a factor of 3-4 for a few hours. Only one of these brightening events correlates well with large transient increases in solar wind ram pressure. The brightening events which are not associated with the solar wind generally have a risetime of 2 h and a decay time of 5 h.

  13. On the Stenbaek-Nielsen and Hallinan pulsating auroras

    SciTech Connect

    D'Angelo, N. )

    1991-02-01

    Stenbaek-Nielsen and Hallinan (1979) argued that if the pulsating auroras are caused by precipitating electrons, the data suggest that noncollisional interactions, localized in the lower E region (90-107 km), where most of the pulsations are observed, may play a dominant role in thermalizing the particles. They also stated that one type of process that comes to mind is a wave-particle interaction in the ionosphere. If, through one or more instabilities, waves grow at the expense of beam energy and, in turn, energize ambient electrons, the energized ambient electrons could ionize the background gas and, in process, produce luminosity. The exceptionally thin pulsating auroral patches observed by Stenbaek-Nielsen and Hallinan (1979) may be caused by an ionization instability occurring at the end of the range of precipitating electrons. A comparison is made to laboratory results reported by Johnson et al. (1990).

  14. Artificial auroras in the upper atmosphere. II - Imaging results

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Burch, J. L.; Swenson, G. R.; Aamodt, E. K.; Geller, S. P.; Rairden, R. L.; Hassler, P. L.

    1993-01-01

    On the ATLAS 1 mission (STS-45, launched March 24, 1992) two experiments, AEPI (Atmospheric Emissions Photometric Imaging) and SEPAC (Space Experiments with Particle Accelerators) performed the first of a series of active experiments intended to probe the atmosphere, ionosphere and magnetosphere with electron beams. The luminous artificial aurora generated by the electron beam interaction was detected and measured by AEPI both in white light and in a narrow wavelength band at 427.8 nm (peak intensity 5 kR). Modelling calculation showed that there was a significant contribution from emissions originating near the spacecraft. The spatial intensity distribution of the observed auroral patch is consistent with emission contribution from both high and low altitude regions. An extended tail in the direction of the shuttle wake was observed in the 427.8 nm channel, consistent with a decay time associated with the dissipation of the hot electron plasma.

  15. Idealized model of polar cap currents, fields, and auroras

    NASA Technical Reports Server (NTRS)

    Cornwall, J. M.

    1985-01-01

    During periods of northward Bz, the electric field applied to the magnetosphere is generally opposite to that occurring during southward Bz and complicated patterns of convection result, showing some features reversed in comparison with the southward Bz case. A study is conducted of a simple generalization of early work on idealized convection models, which allows for coexistence of sunward convection over the central polar cap and antisunward convection elsewhere in the cap. The present model, valid for By approximately 0, has a four-cell convection pattern and is based on the combination of ionospheric current conservation with a relation between parallel auroral currents and parallel potential drops. Global magnetospheric issues involving, e.g., reconnection are not considered. The central result of this paper is an expression giving the parallel potential drop for polar cap auroras (with By approximately 0) in terms of the polar cap convection field profile.

  16. Artificial auroras in the upper atmosphere: 2. Imaging results

    SciTech Connect

    Mende, S.B.; Swenson, G.R.; Aamodt, E.K.; Geller, S.P.; Rairden, R.L. ); Burch, J.L. ); Hassler, P.L. )

    1993-03-19

    On the ATLAS 1 mission (STS-45, launched March 24, 1992) two experiments, AEPI (Atmospheric Emissions Photometric Imaging) and SEPAC (Space Experiments with Particle Accelerators) performed the first experiment in a series of active experiments intended to probe the atmosphere, ionosphere and magnetosphere with electron beams. The luminous artificial aurora generated by the electron beam interaction was detected and measured by AEPI both in white light and in a narrow wavelength band at 427.8 nm (peak intensity 5 kR). Modelling calculation showed that there was a significant contribution from emissions originating near the spacecraft. The spatial intensity distribution of the observed auroral patch is consistent with emission contribution from both high and low altitude regions. An extended tail in the direction of the shuttle wake was observed in the 427.8 nm channel, consistent with a decay time associated with the dissipation of the hot electron plasma. 19 refs., 4 figs., 2 tabs.

  17. Aurora-A modulates MMP-2 expression via AKT/NF-κB pathway in esophageal squamous cell carcinoma cells.

    PubMed

    Wang, Xiaoxia; Li, Xiaozhong; Li, Chaohui; He, Chun; Ren, Benhong; Deng, Qing; Gao, Wei; Wang, Binquan

    2016-06-01

    Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies. It is necessary to identify new markers for predicting tumor progression and therapeutic molecular targets. It has been reported that overexpressions of Aurora-A and matrix metalloproteinases 2 (MMP-2) may promote the malignant development of tumor. However, the relationship between Aurora-A and MMP-2 expression in tumor patients has not been investigated. In addition, the underlying mechanisms that Aurora-A regulates MMP-2 expression are still not fully elucidated. In this study, we demonstrated that Aurora-A and MMP-2 were overexpressed in ESCC tissues compared with paired normal adjacent tissues (P < 0.0001). Overexpression of Aurora-A was associated with the lymph node metastasis of ESCC (P = 0.01). Significantly, Aurora-A protein expression was positively correlated with MMP-2 protein expression in ESCC tissues (r = 0.66, P < 0.0001) as well as in ESCC cell lines. The level of Aurora-A expression was also positively correlated with the invasion capability of ESCC cells. Furthermore, Aurora-A overexpression significantly increased ESCC cell invasion by the upregulation of MMP-2 expression. In addition, Aurora-A overexpression promoted nuclear factor-kappaB (NF-κB) activation, and Aurora-A-mediated MMP-2 upregulation was abrogated by NF-κB inhibitor. Further analysis showed that activation of NF-κB was severely attenuated by AKT inhibitor in cells overexpressing Aurora-A. Taken together, these data indicate that Aurora-A overexpression upregulates MMP-2 expression through activating AKT/NF-κB signaling pathway in ESCC cells. These findings reveal that Aurora-A may be used as an important indicator for the judgment of malignant behavior of ESCC, and may be an attractive target for cancer therapy.

  18. Forecasting auroras from regional and global magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Kauristie, Kirsti; Myllys, Minna; Partamies, Noora; Viljanen, Ari; Peitso, Pyry; Juusola, Liisa; Ahmadzai, Shabana; Singh, Vikramjit; Keil, Ralf; Martinez, Unai; Luginin, Alexej; Glover, Alexi; Navarro, Vicente; Raita, Tero

    2016-06-01

    We use the connection between auroral sightings and rapid geomagnetic field variations in a concept for a Regional Auroral Forecast (RAF) service. The service is based on statistical relationships between near-real-time alerts issued by the NOAA Space Weather Prediction Center and magnetic time derivative (dB/dt) values measured by five MIRACLE magnetometer stations located in Finland at auroral and sub-auroral latitudes. Our database contains NOAA alerts and dB/dt observations from the years 2002-2012. These data are used to create a set of conditional probabilities, which tell the service user when the probability of seeing auroras exceeds the average conditions in Fennoscandia during the coming 0-12 h. Favourable conditions for auroral displays are associated with ground magnetic field time derivative values (dB/dt) exceeding certain latitude-dependent threshold values. Our statistical analyses reveal that the probabilities of recording dB/dt exceeding the thresholds stay below 50 % after NOAA alerts on X-ray bursts or on energetic particle flux enhancements. Therefore, those alerts are not very useful for auroral forecasts if we want to keep the number of false alarms low. However, NOAA alerts on global geomagnetic storms (characterized with Kp values > 4) enable probability estimates of > 50 % with lead times of 3-12 h. RAF forecasts thus rely heavily on the well-known fact that bright auroras appear during geomagnetic storms. The additional new piece of information which RAF brings to the previous picture is the knowledge on typical storm durations at different latitudes. For example, the service users south of the Arctic Circle will learn that after a NOAA ALTK06 issuance in night, auroral spotting should be done within 12 h after the alert, while at higher latitudes conditions can remain favourable during the next night.

  19. Spectroscopic evidence for suprathermal electrons in enhanced auroras

    NASA Astrophysics Data System (ADS)

    Hallinan, T. J.; Kimball, J.; Stenbaek-Nielsen, H. C.; Deehr, C. S.

    1997-04-01

    Auroral arcs frequently exhibit bands of enhanced intensity along the bottom edge. These bands have sharp upper borders and are referred to as enhanced lower borders or auroral hems. They are thought to be related to thin layers of enhanced luminosity observed both in auroral arcs and in pulsating auroras. These anomalous distributions of intensity as a function of altitude are referred to collectively as enhanced aurora (EA) and are of interest because they suggest a more complex process for producing auroral ionization and luminosity than the collisional degradation of precipitating electrons. Spectra of eight auroral hems were obtained with an imaging spectrograph and showed consistently that within the hem, there is an enhanced ratio of N2 1st positive emissions (red) to N2+ 1st negative emissions (blue). The enhancement in the red/blue ratio ranged from 10% to 100%. There was a generally smaller and less consistent enhancement in the ratio of the O2+ 1st negative band at 5275 Å to the N2+ 1st negative. Observations of the far red spectra of several hems showed no enhancement in the ratio of N2 1st positive to N2+ Meinel emissions. There were no simultaneous measurements of the Meinel and the N2+ 1st negatives. It is argued that the enhanced spectral ratios are indicative of a population of suprathermal electrons with a sharp energy cutoff near the ionization potential of N2 and that the electrons are energized in situ through wave-particle interactions or possibly by dc electric fields. It is also noted that some but not all of the hems are type b red lower borders.

  20. Multispectral simultaneous diagnosis of Saturn's aurorae throughout a planetary rotation

    NASA Astrophysics Data System (ADS)

    Lamy, L.; Prangé, R.; Pryor, W.; Gustin, J.; Badman, S. V.; Melin, H.; Stallard, T.; Mitchell, D.-G.; Brandt, P. C.

    2013-08-01

    From 27 to 28 January 2009, the Cassini spacecraft remotely acquired combined observations of Saturn's southern aurorae at radio, ultraviolet, and infrared wavelengths, while monitoring ion injections in the middle magnetosphere from energetic neutral atoms. Simultaneous measurements included the sampling of a full planetary rotation, a relevant timescale to investigate auroral emissions driven by processes internal to the magnetosphere. In addition, this interval coincidentally matched a powerful substorm-like event in the magnetotail, which induced an overall dawnside intensification of the magnetospheric and auroral activity. We comparatively analyze this unique set of measurements to reach a comprehensive view of kronian auroral processes over the investigated timescale. We identify three source regions for the atmospheric aurorae, including a main oval associated with the bulk of Saturn Kilometric Radiation (SKR), together with polar and equatorward emissions. These observations reveal the coexistence of corotational and subcorototational dynamics of emissions associated with the main auroral oval. Precisely, we show that the atmospheric main oval hosts short-lived subcorotating isolated features together with a bright, longitudinally extended, corotating region locked at the southern SKR phase. We assign the substorm-like event to a regular, internally driven, nightside ion injection possibly triggered by a plasmoid ejection. We also investigate the total auroral energy budget, from the power input to the atmosphere, characterized by precipitating electrons up to 20 keV, to its dissipation through the various radiating processes. Finally, through simulations, we confirm the search-light nature of the SKR rotational modulation and we show that SKR arcs relate to isolated auroral spots. We characterize which radio sources are visible from the spacecraft and we estimate the fraction of visible southern power to a few percent. The resulting findings are discussed