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Sample records for mobile messenger dell

  1. To Be Connected or Not To Be Connected? Mobile Messenger Overload, Fatigue, and Mobile Shunning.

    PubMed

    Shin, Jaewook; Shin, Mincheol

    2016-10-01

    With the increased adoption of mobile devices, mobile communication is all around us and we are connected anywhere, anytime. Mobile communication in general and mobile messenger service in particular make interpersonal communication in Korea so frequent and convenient. However, being connected too much anywhere and anytime via mobile messenger service appears to lead an increasing number of people to feel fatigue and to decrease mobile communication under some conditions. Based on a sample of 334 respondents, this study empirically investigated the relationships among commercial, noncommercial mobile messenger overload, mobile messenger fatigue, relational self-concept, and mobile shunning behavior. The findings show that (a) the effect of noncommercial mobile messenger overload is stronger than that of commercial mobile messenger overload in increasing mobile messenger fatigue although both positively affect mobile messenger fatigue, (b) relational self-concept has moderating effects on the relationship between mobile messenger overload and mobile messenger fatigue, and that (c) mobile messenger fatigue triggers mobile communicators' shunning behavior through which the communicators increase their intention to avoid mobile communication, to change their mobile phone numbers, and to subscribe to dual number service on one mobile device. When confronted with mobile messenger fatigue caused by mobile messenger overload, mobile messaging service users are likely to shun their mobile communication. Being constantly and conveniently connected appears to be a blessing in disguise.

  2. Mobile Immersion: An Experiment Using Mobile Instant Messenger to Support Second-Language Learning

    ERIC Educational Resources Information Center

    Lai, Arthur

    2016-01-01

    Immersion has been an acclaimed approach for second-language acquisition, but is not available to most students. The idea of this study was to create a mobile immersion environment on a smartphone using a mobile instant messenger, WhatsApp™. Forty-five Form-1 (7th grade) students divided into the Mobile Group and Control Group participated in a…

  3. Mobile Immersion: An Experiment Using Mobile Instant Messenger to Support Second-Language Learning

    ERIC Educational Resources Information Center

    Lai, Arthur

    2016-01-01

    Immersion has been an acclaimed approach for second-language acquisition, but is not available to most students. The idea of this study was to create a mobile immersion environment on a smartphone using a mobile instant messenger, WhatsApp™. Forty-five Form-1 (7th grade) students divided into the Mobile Group and Control Group participated in a…

  4. The intranuclear mobility of messenger RNA binding proteins is ATP dependent and temperature sensitive

    PubMed Central

    Calapez, Alexandre; Pereira, Henrique M.; Calado, Angelo; Braga, José; Rino, José; Carvalho, Célia; Tavanez, João Paulo; Wahle, Elmar; Rosa, Agostinho C.; Carmo-Fonseca, Maria

    2002-01-01

    fAter being released from transcription sites, messenger ribonucleoprotein particles (mRNPs) must reach the nuclear pore complexes in order to be translocated to the cytoplasm. Whether the intranuclear movement of mRNPs results largely from Brownian motion or involves molecular motors remains unknown. Here we have used quantitative photobleaching techniques to monitor the intranuclear mobility of protein components of mRNPs tagged with GFP. The results show that the diffusion coefficients of the poly(A)-binding protein II (PABP2) and the export factor TAP are significantly reduced when these proteins are bound to mRNP complexes, as compared with nonbound proteins. The data further show that the mobility of wild-type PABP2 and TAP, but not of a point mutant variant of PABP2 that fails to bind to RNA, is significantly reduced when cells are ATP depleted or incubated at 22°C. Energy depletion has only minor effects on the intranuclear mobility of a 2,000-kD dextran (which corresponds approximately in size to 40S mRNP particles), suggesting that the reduced mobility of PABP2 and TAP is not caused by a general alteration of the nuclear environment. Taken together, the data suggest that the mobility of mRNPs in the living cell nucleus involves a combination of passive diffusion and ATP-dependent processes. PMID:12473688

  5. Medical Information Exchange: Pattern of Global Mobile Messenger Usage among Otolaryngologists.

    PubMed

    Siegal, Gil; Dagan, Elad; Wolf, Michael; Duvdevani, Shay; Alon, Eran E

    2016-11-01

    Information technology has revolutionized health care. However, the development of dedicated mobile health software has been lagging, leading to the use of general mobile applications to fill in the void. The use of such applications has several legal, ethical, and regulatory implications. We examined the experience and practices governing the usage of a global mobile messenger application (WhatsApp) for mobile health purposes in a national cohort of practicing otolaryngologists in Israel, a known early adaptor information technology society. Cross-sectional data were collected from practicing otolaryngologists and otolaryngology residents via self-administered questionnaire. The questionnaire was composed of a demographic section, a section surveying the practices of mobile application use, mobile health application use, and knowledge regarding institutional policies governing the transmission of medical data. The sample included 22 otolaryngology residents and 47 practicing otolaryngologists. Of the physicians, 83% worked in academic centers, and 88% and 40% of the physicians who worked in a hospital setting or a community clinic used WhatsApp for medical use, respectively. Working with residents increased the medical usage of WhatsApp from 50% to 91% (P = .006). Finally, 72% were unfamiliar with any institutional policy regarding the transfer of medical information by personal smartphones. Mobile health is becoming an integral part of modern medical systems, improving accessibility, efficiency, and possibly quality of medical care. The need to incorporate personal mobile devices in the overall information technology standards, guidelines, and regulation is becoming more acute. Nonetheless, practices must be properly instituted to prevent unwanted consequences. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

  6. The Effectiveness of Using WhatsApp Messenger as One of Mobile Learning Techniques to Develop Students' Writing Skills

    ERIC Educational Resources Information Center

    Fattah, Said Fathy El Said Abdul

    2015-01-01

    The present study was an attempt to determine the effectiveness of using a WhatsApp Messenger as one of mobile learning techniques to develop students' writing skills. Participants were 30 second year college students, English department from a private university in Saudi Arabia. The experimental group (N = 15) used WhatsApp technology to develop…

  7. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  8. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  9. Dell's Different Direction.

    PubMed

    Price, Sean

    2017-05-01

    The unique curriculum at The University of Texas at Austin Dell Medical School practically does away with traditional lectures and focuses instead on solving problems and working together with other health care professionals.

  10. Gauge Messenger Models

    SciTech Connect

    Kim, Hyung Do

    2006-11-28

    We consider gauge messenger models in which X and Y gauge bosons and gauginos are messengers of supersymmetry breaking. In simple gauge messenger models, all the soft parameters except {mu} and B{mu} are calculated in terms of a single scale parameter MSUSY which is proportional to F / MGUT. Unique prediction on dark matter in gauge messenger models is discussed. (Based on hep-ph/0601036 and hep-ph/0607169)

  11. Transmembrane Signalling: Membrane messengers

    NASA Astrophysics Data System (ADS)

    Cockroft, Scott L.

    2017-05-01

    Life has evolved elaborate means of communicating essential chemical information across cell membranes. Inspired by biology, two new artificial mechanisms have now been developed that use synthetic messenger molecules to relay chemical signals into or across lipid membranes.

  12. About The ESO Messenger

    NASA Astrophysics Data System (ADS)

    Kjär, K.

    2000-06-01

    The present Messenger is the hundredth issue to be published. This may be a good moment to look back to the beginning and to the development of this publication. The idea of an internal ESO newsletter was born in the early seventies. Using the words of Professor Blaauw, Director General of ESO at that time and the person who launched The Messenger in its orbit, the purpose of The ESO Messenger should be “first of all, to promote the participation of ESO staff in what goes on in the Organization, especially at places of duty other than our own. Moreover, The Messenger may serve to give the world outside some impression of what happens inside ESO. The need for more internal communication is felt by many of the staff. The dispersion of our resources over several countries in widely separated continents demands a special effort to keep us aware of what is going on at the other establishments...”

  13. MESSENGER Laser Altimeter

    NASA Image and Video Library

    MESSENGER's Mercury Laser Altimeter sends out laser pulses that hit the ground and return to the instrument. The amount of light that returns for each pulse gives the reflectance at that point on t...

  14. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    Daughters of NASA astronaut Alan Shepard, Laura Shepard Churchley, left, Alice Wackermann and Julie Jenkins, right, speak during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  15. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    Daughters of NASA astronaut Alan Shepard, Laura Shepard Churchley, standing left, Alice Wackermann and Julie Jenkins, standing right, speak during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  16. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    United States Postal Service Vice President of Finance Steve Masse, left, and NASA Mercury Astronaut Scott Carpenter, unveil two USPS stamps to commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  17. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    NASA Administrator Charles Boldin speaks during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  18. Messenger RNA transcripts

    Treesearch

    Dan Cullen

    2004-01-01

    In contrast to DNA, messenger RNA (mRNA) in complex substrata is rarely analyzed, in large part because labile RNA molecules are difficult to purify. Nucleic acid extractions from fungi that colonize soil are particularly difficult and plagued by humic substances that interfere with Taq polymerase (Tebbe and Vahjen 1993 and references therein). Magnetic capture...

  19. Diphosphoinositol Polyphosphates: Metabolic Messengers?

    PubMed Central

    Shears, Stephen B.

    2009-01-01

    The diphosphoinositol polyphosphates (“inositol pyrophosphates”) are a specialized subgroup of the inositol phosphate signaling family. This review proposes that many of the current data concerning the metabolic turnover and biological effects of the diphosphoinositol polyphosphates are linked by a common theme: these polyphosphates act as metabolic messengers. This review will also discuss the latest proposals concerning possible molecular mechanisms of action of this intriguing class of molecules. PMID:19439500

  20. Mercury MESSENGER Stamp Unveiling

    NASA Image and Video Library

    2011-05-03

    From left, NASA Deputy Director, Planetary Science Division, Science Mission Directorate, Jim Adams, NASA Kennedy Space Center Director of Education and External Relations Cheryl Hurst, United States Postal Service Vice President of Finance Steve Masse, NASA Mercury Astronaut Scott Carpenter, NASA Administrator Charles Boldin, Daughters of NASA astronaut Alan Shepard, Alice Wackermann, Laura Shepard Churchley, and Julie Jenkins, and NASA Kennedy Space Center Director Robert Cabana pose for a photograph during an unveiling ceremony of two USPS stamps that commemorate and celebrate 50 years of US Spaceflight and the MESSENGER program during an event, Wednesday, May 4, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Fla. One stamp commemorates NASA’s Project Mercury, America’s first manned spaceflight program, and NASA astronaut Alan Shepard’s historic flight on May 5, 1961, aboard spacecraft Freedom 7. The other stamp draws attention to NASA’s unmanned MESSENGER mission, a scientific investigation of the planet Mercury. On March 17, 2011, MESSENGER became the first spacecraft to enter into orbit around Mercury. Photo Credit: (NASA/Bill Ingalls)

  1. Who discovered messenger RNA?

    PubMed

    Cobb, Matthew

    2015-06-29

    The announcement of the discovery of messenger RNA (mRNA) and the cracking of the genetic code took place within weeks of each other in a climax of scientific excitement during the summer of 1961. Although mRNA is of decisive importance to our understanding of gene function, no Nobel Prize was awarded for its discovery. The large number of people involved, the complex nature of the results, and the tortuous path that was taken over half a century ago, all show that simple claims of priority may not reflect how science works.

  2. MESSENGER: Science payload status

    NASA Astrophysics Data System (ADS)

    McNutt, R.; Solomon, S.; Gold, R.

    2003-04-01

    MESSENGER is a NASA Discovery mission to reach Mercury and orbit that planet for an Earth year, gathering data with a miniaturized scientific payload. The MESSENGER project is now entering the integration and test phase as the spacecraft is assembled and the instruments are calibrated and delivered to the spacecraft. The Gamma-Ray and Neutron spectrometer (GRNS) and X-Ray Spectrometer (XRS) experienced detector changes in order to increase the signal-to-noise ratio (based upon more experience with similar instrumentation on the Near Earth Asteroid Rendezvous, NEAR-Shoemaker, mission and on Mars Odyssey). The gamma-ray portion of GRNS uses a high-purity germanium crystal cooled to ˜90K and surrounded by an active shield to detect characteristic gamma-rays from the planet. The neutron spectrometer uses Li-glass and plastic scintillators to detect and separate thermal, epithermal, and fast neutrons. The XRS spectrometer uses three gas-filled proportional counters looking at the planet and a solar monitor to measure X-ray fluorescence lines from the planet's surface. These instruments thus provide information on elemental abundances. The optical remote-sensing instruments map the planet in several spectral bands (Mercury Dual Imaging System -- MDIS), measure surface spectral reflectance in the visible and infra-red and exospheric emission lines in the ultraviolet and visible (Mercury Atmospheric and Surface Composition Spectrometer -- MASCS), and measure surface topography (Mercury Laser Altimeter -- MLA). The combination of altimetry with MLA and radio-science (RS) measurements will allow maps of the gravitational field of the planet and inference of the planet's obliquity and physical amplitude. The combination of boom-mounted magnetometer (MAG) and combined Energetic Particle and Plasma Spectrometer (EPPS) allows internal and external sources of magnetic field to be separated, providing knowledge of both Mercury's internal structure and its magnetosphere and

  3. Dynamical Messengers for Gauge Mediation

    SciTech Connect

    Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.

    2011-08-17

    We construct models of indirect gauge mediation where the dynamics responsible for breaking supersymmetry simultaneously generates a weakly coupled subsector of messengers. This provides a microscopic realization of messenger gauge mediation where the messenger and hidden sector fields are unified into a single sector. The UV theory is SQCD with massless and massive quarks plus singlets, and at low energies it flows to a weakly coupled quiver gauge theory. One node provides the primary source of supersymmetry breaking, which is then transmitted to the node giving rise to the messenger fields. These models break R-symmetry spontaneously, produce realistic gaugino and sfermion masses, and give a heavy gravitino.

  4. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  5. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Messenger service. 7.1012 Section 7.1012 Banks... Bank Powers § 7.1012 Messenger service. (a) Definition. For purposes of this section, a “messenger... establish and operate a messenger service, or use, with its customers, a third party messenger service....

  6. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Messenger service. 7.1012 Section 7.1012 Banks... Bank Powers § 7.1012 Messenger service. (a) Definition. For purposes of this section, a “messenger... establish and operate a messenger service, or use, with its customers, a third party messenger service....

  7. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Messenger service. 7.1012 Section 7.1012 Banks... Bank Powers § 7.1012 Messenger service. (a) Definition. For purposes of this section, a “messenger... establish and operate a messenger service, or use, with its customers, a third party messenger service....

  8. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Messenger service. 7.1012 Section 7.1012 Banks... Bank Powers § 7.1012 Messenger service. (a) Definition. For purposes of this section, a “messenger... establish and operate a messenger service, or use, with its customers, a third party messenger service....

  9. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Messenger service. 7.1012 Section 7.1012 Banks... Bank Powers § 7.1012 Messenger service. (a) Definition. For purposes of this section, a “messenger... establish and operate a messenger service, or use, with its customers, a third party messenger service....

  10. The MESSENGER science payload

    NASA Astrophysics Data System (ADS)

    Gold, Robert E.; McNutt, Ralph L., Jr.; Solomon, Sean C.; MESSENGER Team

    2003-11-01

    The MESSENGER spacecraft will orbit Mercury and gather data for one Earth year with a miniaturized scientific payload. The MESSENGER project is in the integration and test phase in mid 2003. Seven assembled and calibrated instruments are mounted on the spacecraft. The Gamma-Ray and Neutron Spectrometer has a Gamma-Ray Spectrometer to measure atomic composition with a high-purity germanium detector and a Neutron Spectrometer that uses lithium-glass and boron-loaded plastic scintillators for sensing thermal, epithermal, and fast neutrons. The X-Ray Spectrometer measures Mercury surface elemental abundances by examining solar-flare-induced X-ray fluorescence lines. Three gas-filled proportional counters detect the X-ray fluorescence lines from the planet's surface, and a solid-state solar monitor measures the X-ray input to the planet. The Mercury Dual Imaging System (MDIS) has both wide-field and narrow-field cameras to map the surface of the planet. MDIS is also multi-spectral, with a 12-position filter wheel for the wide-field camera. The Mercury Atmospheric and Surface Composition Spectrometer measures both surface spectral reflectance in the visible and near infrared and exospheric emission lines in the ultraviolet and visible. The Mercury Laser Altimeter (MLA) determines the range to the planet with a resolution of 0.3 m. MLA will be combined with the radio-science investigation to map the gravitational field of the planet and determine the obliquity and physical libration amplitude. A magnetometer, mounted on a 3.6-m boom, will map the internal and external magnetic field. The Energetic Particle and Plasma Spectrometer will measure particles accelerated in the magnetosphere and the interactions of the magnetosphere with the solar wind. MDIS has its own pivot platform. All of the other instruments are fixed to the spacecraft. Pointing is accomplished by steering the entire spacecraft. All of the instruments are designed to deal with the extreme thermal

  11. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuna, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Levi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2005-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet s miniature magnetosphere since the brief flybys of Mariner 10. Mercury s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. The characteristic time scales for wave propagation and convective transport are short and kinetic and fluid modes may be coupled. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury s interior. In addition, Mercury s magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, - 1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury s magnetic tail. Because of Mercury s proximity to the sun, 0.3 - 0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and re-cycling of neutrals and ions between the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection at the magnetopause and in the tail, and the pick-up of planetary ions all

  12. MESSENGER'S First Flyby of Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. An overview of the MESSENGER mission and its January 14th close flyby of Mercury will be provided. Primary science objectives and the science instrumentation will be described. Initial results from MESSENGER'S first flyby on January 14th, 2008 will be discussed with an emphasis on the magnetic field and charged particle measurements.

  13. The MESSENGER Spacecraft

    NASA Astrophysics Data System (ADS)

    Leary, James C.; Conde, Richard F.; Dakermanji, George; Engelbrecht, Carl S.; Ercol, Carl J.; Fielhauer, Karl B.; Grant, David G.; Hartka, Theodore J.; Hill, Tracy A.; Jaskulek, Stephen E.; Mirantes, Mary A.; Mosher, Larry E.; Paul, Michael V.; Persons, David F.; Rodberg, Elliot H.; Srinivasan, Dipak K.; Vaughan, Robin M.; Wiley, Samuel R.

    2007-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was designed and constructed to withstand the harsh environments associated with achieving and operating in Mercury orbit. The system can be divided into eight subsystems: structures and mechanisms (e.g., the composite core structure, aluminum launch vehicle adapter, and deployables), propulsion (e.g., the state-of-the-art titanium fuel tanks, thruster modules, and associated plumbing), thermal (e.g., the ceramic-cloth sunshade, heaters, and radiators), power (e.g., solar arrays, battery, and controlling electronics), avionics (e.g., the processors, solid-state recorder, and data handling electronics), software (e.g., processor-supported code that performs commanding, data handling, and spacecraft control), guidance and control (e.g., attitude sensors including star cameras and Sun sensors integrated with controllers including reaction wheels), radio frequency telecommunications (e.g., the spacecraft antenna suites and supporting electronics), and payload (e.g., the science instruments and supporting processors). This system architecture went through an extensive (nearly four-year) development and testing effort that provided the team with confidence that all mission goals will be achieved.

  14. MESSENGER Final Image

    NASA Image and Video Library

    2015-04-30

    Today, the MESSENGER spacecraft sent its final image. Originally planned to orbit Mercury for one year, the mission exceeded all expectations, lasting for over four years and acquiring extensive datasets with its seven scientific instruments and radio science investigation. This afternoon, the spacecraft succumbed to the pull of solar gravity and impacted Mercury's surface. The image shown here is the last one acquired and transmitted back to Earth by the mission. The image is located within the floor of the 93-kilometer-diameter crater Jokai. The spacecraft struck the planet just north of Shakespeare basin. Date acquired: April 30, 2015 Image Mission Elapsed Time (MET): 72716050 Image ID: 8422953 Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS) Center Latitude: 72.0° Center Longitude: 223.8° E Resolution: 2.1 meters/pixel Scale: This image is about 1 kilometers (0.6 miles) across Incidence Angle: 57.9° Emission Angle: 56.5° Phase Angle: 40.7° http://photojournal.jpl.nasa.gov/catalog/PIA19448

  15. NASA Now: MESSENGER in Orbit

    NASA Image and Video Library

    Dr. Larry Evans, Senior Scientist for MESSENGER, discusses the difficulty of getting to Mercury, the challenges of visiting a planet so close to the sun and what we hope to discover when the spacec...

  16. MESSENGER Departing Earth Artist Concept

    NASA Image and Video Library

    2004-08-03

    Artist impression of NASA MErcury Surface, Space ENvironment, GEochemistry, and Ranging MESSENGER spacecraft as it leaves Earth, following its Aug. 3, 2004 launch from Cape Canaveral Air Force Station, Fla. aboard a Delta II rocket.

  17. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuña, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Livi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2007-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury offers our first opportunity to explore this planet’s miniature magnetosphere since the brief flybys of Mariner 10. Mercury’s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only ˜1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere, allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury’s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury’s interior. In addition, Mercury’s magnetosphere is the only one with its defining magnetic flux tubes rooted beneath the solid surface as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, ˜1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury’s magnetic tail. Because of Mercury’s proximity to the sun, 0.3-0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and recycling of neutrals and ions among the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury’s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection, and pick-up of planetary ions all playing roles in the generation of field-aligned electric currents. However, these field

  18. The power of virtual integration: an interview with Dell Computer's Michael Dell. Interview by Joan Magretta.

    PubMed

    Dell, M

    1998-01-01

    Michael Dell started his computer company in 1984 with a simple business insight. He could bypass the dealer channel through which personal computers were then being sold and sell directly to customers, building products to order. Dell's direct model eliminated the dealer's markup and the risks associated with carrying large inventories of finished goods. In this interview, Michael Dell provides a detailed description of how his company is pushing that business model one step further, toward what he calls virtual integration. Dell is using technology and information to blur the traditional boundaries in the value chain between suppliers, manufacturers, and customers. The individual pieces of Dell's strategy--customer focus, supplier partnerships, mass customization, just-in-time manufacturing--may be all be familiar. But Michael Dell's business insight into how to combine them is highly innovative. Direct relationships with customers create valuable information, which in turn allows the company to coordinate its entire value chain back through manufacturing to product design. Dell describes how his company has come to achieve this tight coordination without the "drag effect" of ownership. Dell reaps the advantages of being vertically integrated without incurring the costs, all the while achieving the focus, agility, and speed of a virtual organization. As envisioned by Michael Dell, virtual integration may well become a new organizational model for the information age.

  19. The MESSENGER Spacecraft and Payload

    NASA Astrophysics Data System (ADS)

    Gold, R. E.; Solomon, S. C.; McNutt, R. L., Jr.; Santo, A. G.

    2002-01-01

    The MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission will send the first spacecraft to orbit the planet Mercury. A Mercury orbiter mission is challenging from thermal and mass perspectives. MESSENGER overcomes these challenges while avoiding esoteric technologies by using an innovative approach with commonly available materials, minimal moving parts, and maximum heritage. The key concepts are a ceramic-cloth thermal shade, an integrated lightweight structure, a high performance propulsion system, and a solar array incorporating optical solar reflectors. A miniaturized set of seven instruments, along with the spacecraft telecommunications system, satisfy all scientific objectives of the mission. The payload includes a combined wide-angle and narrow-angle imaging system; amma-ray, neutron, and X-ray spectrometers for remote geochemical sensing; a vector magnetometer; a laser altimeter; a combined ultraviolet-visible and visible-infrared spectrometer to detect atmospheric species and map mineralogical absorption features; and an energetic particle and plasma spectrometer to characterize ionized species in the magnetosphere. MESSENGER construction is nearly complete and the integration and test phase is just beginning. Launch is March 2004.

  20. Geodesy at Mercury with MESSENGER

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria t.; Peale, Stanley J.; Phillips, Roger J.; Solomon, Sean C.

    2006-01-01

    In 2011 the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft will enter Mercury orbit and begin the mapping phase of the mission. As part of its science objectives the MESSENGER mission will determine the shape and gravity field of Mercury. These observations will enable the topography and the crustal thickness to be derived for the planet and will determine the small libration of the planet about its axis, the latter critical to constraining the state of the core. These measurements require very precise positioning of the MESSENGER spacecraft in its eccentric orbit, which has a periapsis altitude as low as 200 km, an apoapsis altitude near 15,000 km, and a closest approach to the surface varying from latitude 60 to about 70 N. The X-band tracking of MESSENGER and the laser altimetry are the primary data that will be used to measure the planetary shape and gravity field. The laser altimeter, which has an expected range of 1000 to 1200 km, is expected to provide significant data only over the northern hemisphere because of MESSENGER's eccentric orbit. For the southern hemisphere, radio occultation measurements obtained as the spacecraft passes behind the planet as seen from Earth and images obtained with the imaging system will be used to provide the long-wavelength shape of the planet. Gravity, derived from the tracking data, will also have greater resolution in the northern hemisphere, but full global models for both topography and gravity will be obtained at low harmonic order and degree. The limiting factor for both gravity and topography is expected to be knowledge of the spacecraft location. Present estimations are that in a combined tracking, altimetry, and occultation solution the spacecraft position uncertainty is likely to be of order 10 m. This accuracy should be adequate for establishing an initial geodetic coordinate system for Mercury that will enable positioning of imaged features on the surface, determination of

  1. Melatonin: a universal time messenger.

    PubMed

    Erren, Thomas C; Reiter, Russel J

    2015-01-01

    Temporal organization plays a key role in humans, and presumably all species on Earth. A core building block of the chronobiological architecture is the master clock, located in the suprachi asmatic nuclei [SCN], which organizes "when" things happen in sub-cellular biochemistry, cells, organs and organisms, including humans. Conceptually, time messenging should follow a 5 step-cascade. While abundant evidence suggests how steps 1 through 4 work, step 5 of "how is central time information transmitted througout the body?" awaits elucidation. Step 1: Light provides information on environmental (external) time; Step 2: Ocular interfaces between light and biological (internal) time are intrinsically photosensitive retinal ganglion cells [ipRGS] and rods and cones; Step 3: Via the retinohypothalamic tract external time information reaches the light-dependent master clock in the brain, viz the SCN; Step 4: The SCN translate environmental time information into biological time and distribute this information to numerous brain structures via a melanopsin-based network. Step 5: Melatonin, we propose, transmits, or is a messenger of, internal time information to all parts of the body to allow temporal organization which is orchestrated by the SCN. Key reasons why we expect melatonin to have such role include: First, melatonin, as the chemical expression of darkness, is centrally involved in time- and timing-related processes such as encoding clock and calendar information in the brain; Second, melatonin travels throughout the body without limits and is thus a ubiquitous molecule. The chemial conservation of melatonin in all tested species could make this molecule a candidate for a universal time messenger, possibly constituting a legacy of an all-embracing evolutionary history.

  2. MESSENGER Observations of Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2010-01-01

    During MESSENGER's second and third flybys of Mercury on October 6, 2008 and September 29, 2009, respectively, southward interplanetary magnetic field (IMF) produced intense reconnection signatures in the dayside and nightside magnetosphere and markedly different system-level responses. The IMF during the second flyby was continuously southward and the magnetosphere appeared very active, with large magnetic field components normal to the magnetopause and the generation of flux transfer events at the magnetopause and plasmoids in the tail current sheet every 30 to 90 s. However, the strength and direction of the tail magnetic field was stable. In contrast, the IMF during the third flyby varied from north to south on timescales of minutes. Although the MESSENGER measurements were limited during that encounter to the nightside magnetosphere, numerous examples of plasmoid release in the tail were detected, but they were not periodic. Instead, plasmoid release was highly correlated with four large enhancements of the tail magnetic field (i.e. by factors > 2) with durations of approx. 2 - 3 min. The increased flaring of the magnetic field during these intervals indicates that the enhancements were caused by loading of the tail with magnetic flux transferred from the dayside magnetosphere. New analyses of the second and third flyby observations of reconnection and its system-level effects provide a basis for comparison and contrast with what is known about the response of the Earth s magnetosphere to variable versus steady southward IMF.

  3. Details of MESSENGER Impact Location

    NASA Image and Video Library

    2015-04-29

    These graphics show the current best prediction of the location and time of NASA MESSENGER impact on Mercury surface. These current best estimates are: Date: 30 April 2015 Time: 3:26:02 pm EDT 19:26:02 UTC Latitude: 54.4° N Longitude: 210.1° E. Traveling at 3.91 kilometers per second (over 8,700 miles per hour), the MESSENGER spacecraft will collide with Mercury's surface, creating a crater estimated to be 16 meters (52 feet) in diameter. View this image to learn about the named features and geology of this region on Mercury. Instruments: Mercury Dual Imaging System (MDIS) and Mercury Laser Altimeter (MLA) Top Image Latitude Range: 49°-59° N Top Image Longitude Range: 204°-217° E Topography in Top Image: Exaggerated by a factor of 5.5. Colors in Top Image: Coded by topography. The tallest regions are colored red and are roughly 3 kilometers (1.9 miles) higher than low-lying areas such as the floors of impact craters, colored blue. Scale in Top Image: The large crater on the left side of the image is Janacek, with a diameter of 48 kilometers (30 miles) http://photojournal.jpl.nasa.gov/catalog/PIA19443

  4. Nuclear Export of Messenger RNA

    PubMed Central

    Katahira, Jun

    2015-01-01

    Transport of messenger RNA (mRNA) from the nucleus to the cytoplasm is an essential step of eukaryotic gene expression. In the cell nucleus, a precursor mRNA undergoes a series of processing steps, including capping at the 5' ends, splicing and cleavage/polyadenylation at the 3' ends. During this process, the mRNA associates with a wide variety of proteins, forming a messenger ribonucleoprotein (mRNP) particle. Association with factors involved in nuclear export also occurs during transcription and processing, and thus nuclear export is fully integrated into mRNA maturation. The coupling between mRNA maturation and nuclear export is an important mechanism for providing only fully functional and competent mRNA to the cytoplasmic translational machinery, thereby ensuring accuracy and swiftness of gene expression. This review describes the molecular mechanism of nuclear mRNA export mediated by the principal transport factors, including Tap-p15 and the TREX complex. PMID:25836925

  5. Bifunctional transfer-messenger RNA

    PubMed Central

    Ramadoss, Nitya S.

    2011-01-01

    Transfer-messenger RNA (tmRNA) is a bifunctional RNA that has properties of a tRNA and an mRNA. tmRNA uses these two functions to release ribosomes stalled during translation and target the nascent polypeptides for degradation. This concerted reaction, known as trans-translation, contributes to translational quality control and regulation of gene expression in bacteria. tmRNA is conserved throughout bacteria, and is one of the most abundant RNAs in the cell, suggesting that trans-translation is of fundamental importance for bacterial fitness. Mutants lacking tmRNA activity typically have severe phenotypes, including defects in viability, virulence, and responses to environmental stresses. PMID:21664408

  6. Neutralino Dark Matter in Gauge Messenger Models

    SciTech Connect

    Bae, Kyu Jung

    2008-11-23

    The lightest neutralino is one of the best candidate for dark matter. In gauge messenger models, It is generic that bino and wino masses are almostly degenerate. Because of this, neutralino annihilation becomes more efficient. Also, gauge messenger models have squeezed mass spectrum so that there are many resonance and co-annihilation regions, and can give correct amount of neutralino relic density.

  7. Astroparticles: Messengers from Outer Space

    NASA Astrophysics Data System (ADS)

    Desiati, Paolo

    2016-07-01

    Since Galileo pointed a spyglass toward the sky, 400 years ago, observations empowered by man-made instrumentation have provided us with an enormous leap in the knowledge of how the Universe functions. More and more powerful optical telescopes made it possible for us to reach the farthest corners of space. At the same time, the advances in microphysics and the discovery of the electromagnetic spectrum, made it possible to directly look at the Universe in a way that our eyes cannot see. The discoveries of the intimate structure of matter, of subatomic particles and of how they interact with each other, have led astronomers to use the smallest objects in Nature to observe the farthest reaches of the otherwise invisible Universe. Not unlike Galileo, today we observe Outer Space with visible light and beyond, across the entire electromagnetic spectrum, from long wavelength radio waves to short wavelength gamma rays. But also with instruments detecting cosmic rays (the atomic nuclei we know on Earth) neutrinos (neutral subatomic particles that interact very weakly with matter) and gravitational waves (perturbations of spacetime predicted by General Relativity). Each cosmic messenger provides us with a unique piece of information about their source and the history of their journey to us. Modern astrophysics has the challenging goal to collect as much information as possible from all those messengers, to reconstruct the story of the Universe and how it became what it is today. This journey started with the unsettling discovery that we are only one minuscule dot in the immensity of the Universe and yet we are able to observe objects that are far in space and time. This journey is yet to complete its course, and the more we advance our knowledge, the more we need to understand. This interdisciplinary talk provides an overview of this journey and the future perspectives.

  8. Mobilization

    DTIC Science & Technology

    1987-01-01

    istic and romantic emotionalism that typifies this genre. Longino, James C., et al. “A Study of World War Procurement and Industrial Mobilization...States. Harrisburg, PA: Military Service Publishing Co., 1941. CARL 355.22 J72b. Written in rough prose , this World War II era document explains the

  9. MESSENGER: Exploring the Innermost Planet

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    2011-12-01

    One of Earth's closest planetary neighbors, Mercury remained comparatively unexplored for the more than three decades that followed the three flybys of the innermost planet by the Mariner 10 spacecraft in 1974-75. Mariner 10 imaged 45% of Mercury's surface at about 1 km/pixel average resolution, confirmed Mercury's anomalously high bulk density and implied large fractional core size, discovered Mercury's internal magnetic field, documented that H and He are present in the planet's tenuous exosphere, and made the first exploration of Mercury's magnetosphere and solar wind environment. Ground-based astronomers later reported Na, K, and Ca in Mercury's exosphere; the presence of deposits in the floors of polar craters having radar characteristics best matched by water ice; and strong evidence from the planet's forced libration amplitude that Mercury has a fluid outer core. Spacecraft exploration of Mercury resumed with the selection for flight, under NASA's Discovery Program, of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. Launched in 2004, MESSENGER flew by the innermost planet three times in 2008-2009 en route to becoming the first spacecraft to orbit Mercury in March of this year. MESSENGER's first chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction differs from those of the other inner planets, with a low-Fe surface composition intermediate between basalts and ultramafic rocks and best matched among terrestrial rocks by komatiites. Moreover, surface materials are richer in the volatile constituents S and K than predicted by most planetary formation models. Global image mosaics and targeted high-resolution images (to resolutions of 10 m/pixel) reveal that Mercury experienced globally extensive volcanism, including large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile

  10. The Mercury exosphere after MESSENGER

    NASA Astrophysics Data System (ADS)

    Killen, Rosemary; McClintock, William; Vervack, Ronald; Merkel, Aimee; Burger, Matthew; Cassidy, Timothy; Sarantos, Menelaos

    2016-07-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft observed sodium, calcium and magnesium emisison in Mercury's exosphere on a near-daily basis for >16 Mercury years. The MASCS observations showed that calcium in Mercury's exosphere is persistently concentrated in the dawn hemisphere and is of extreme temperature (>50,000 K). The column abundance varies seasonally, and is extremely repeatable each Mercury year. In addition, the calcium exhibits a persistent maximum not at perihelion but 20° after perihelion, an enhancement that was shown to be coincident with the probable intersection of Mercury's orbit with a dust stream originating at Comet Encke. Any mechanism producing the Mercurian Ca exosphere must explain the facts that the Ca is extremely hot, that it is seen almost exclusively on the dawnside of the planet, and that its content varies seasonally, not sporadically. Energization of the Ca atoms was suggested to originate through dissociation of Ca-bearing molecules ejected by meteoritic impacts. Magnesium was also observed on a daily basis throughout the MESSENGER orbital phase. Mg has its own spatial and temporal pattern, peaking at mid-morning instead of early morning like Ca, and exhibiting a warm thermal profile, about 5000 K, unlike the extreme temperature of Ca which is an order of magnitude hotter. Although Mercury's sodium exosphere has been observed from the ground for many decades, the MASCS observations showed that, like calcium, the sodium exosphere is dominated by seasonal variations, not sporadic variations. However a conundrum exists as to why ground-based observations show highly variable high-latitude variations that eluded the MASCS. The origin of a persistent south polar enhancement has not been explained. The more volatile element, Na, is again colder, about 1200 K, but not thermally accommodated to the surface temperature. A

  11. The Magnetometer Instrument on MESSENGER

    NASA Astrophysics Data System (ADS)

    Anderson, Brian J.; Acuña, Mario H.; Lohr, David A.; Scheifele, John; Raval, Asseem; Korth, Haje; Slavin, James A.

    2007-08-01

    The Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission is a low-noise, tri-axial, fluxgate instrument with its sensor mounted on a 3.6-m-long boom. The boom was deployed on March 8, 2005. The primary MAG science objectives are to determine the structure of Mercury’s intrinsic magnetic field and infer its origin. Mariner 10 observations indicate a planetary moment in the range 170 to 350 nT R {M/3} (where R M is Mercury’s mean radius). The uncertainties in the dipole moment are associated with the Mariner 10 trajectory and variability of the measured field. By orbiting Mercury, MESSENGER will significantly improve the determination of dipole and higher-order moments. The latter are essential to understanding the thermal history of the planet. MAG has a coarse range, ±51,300 nT full scale (1.6-nT resolution), for pre-flight testing, and a fine range, ±1,530 nT full scale (0.047-nT resolution), for Mercury operation. A magnetic cleanliness program was followed to minimize variable and static spacecraft-generated fields at the sensor. Observations during and after boom deployment indicate that the fixed residual field is less than a few nT at the location of the sensor, and initial observations indicate that the variable field is below 0.05 nT at least above about 3 Hz. Analog signals from the three axes are low-pass filtered (10-Hz cutoff) and sampled simultaneously by three 20-bit analog-to-digital converters every 50 ms. To accommodate variable telemetry rates, MAG provides 11 output rates from 0.01 s-1 to 20 s-1. Continuous measurement of fluctuations is provided with a digital 1-10 Hz bandpass filter. This fluctuation level is used to trigger high-time-resolution sampling in eight-minute segments to record events of interest when continuous high-rate sampling is not possible. The MAG instrument will provide accurate characterization of the intrinsic planetary field, magnetospheric structure, and

  12. MESSENGER'S First and Second Flybys of Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2009-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only approximately 1000 km above the surface. An overview of the MESSENGER mission and its January 14th and October 6th, 2008 close flybys of Mercury will be provided. Primary science objectives and the science instrumentation will be described. Initial results from MESSENGER will be discussed with an emphasis on the magnetic field and charged particle measurements.

  13. MESSENGER Team Presents Latest Science Results

    NASA Image and Video Library

    2009-04-30

    This mosaic was assembled using NAC images acquired as the MESSENGER spacecraft approached the planet during the mission second Mercury flyby The Rembrandt impact basin is seen at the center of the mosaic.

  14. The lipid messenger OEA links dietary fat intake to satiety

    PubMed Central

    Schwartz, Gary J.; Li, Xiaosong; Gaetani, Silvana; Campolongo, Patrizia; Cuomo, Vincenzo; Piomelli, Daniele

    2008-01-01

    Summary The association between fat consumption and obesity underscores the need to identify physiological signals that control fat intake. Previous studies have shown that feeding stimulates small-intestinal mucosal cells to produce the lipid messenger oleoylethanolamide (OEA) which, when administered as a drug, decreases meal frequency by engaging peroxisome proliferator-activated receptors-α (PPAR-α). Here we report that duodenal infusion of fat stimulates OEA mobilization in the proximal small intestine, whereas infusion of protein or carbohydrate does not. OEA production utilizes dietary oleic acid as a substrate and is disrupted in mutant mice lacking the membrane fatty-acid transporter CD36. Targeted disruption of CD36 or PPAR-α abrogates the satiety response induced by fat. The results suggest that activation of small-intestinal OEA mobilization, enabled by CD36-mediated uptake of dietary oleic acid, serves as a molecular sensor linking fat ingestion to satiety. PMID:18840358

  15. The lipid messenger OEA links dietary fat intake to satiety.

    PubMed

    Schwartz, Gary J; Fu, Jin; Astarita, Giuseppe; Li, Xiaosong; Gaetani, Silvana; Campolongo, Patrizia; Cuomo, Vincenzo; Piomelli, Daniele

    2008-10-01

    The association between fat consumption and obesity underscores the need to identify physiological signals that control fat intake. Previous studies have shown that feeding stimulates small-intestinal mucosal cells to produce the lipid messenger oleoylethanolamide (OEA) which, when administered as a drug, decreases meal frequency by engaging peroxisome proliferator-activated receptors-alpha (PPAR-alpha). Here, we report that duodenal infusion of fat stimulates OEA mobilization in the proximal small intestine, whereas infusion of protein or carbohydrate does not. OEA production utilizes dietary oleic acid as a substrate and is disrupted in mutant mice lacking the membrane fatty-acid transporter CD36. Targeted disruption of CD36 or PPAR-alpha abrogates the satiety response induced by fat. The results suggest that activation of small-intestinal OEA mobilization, enabled by CD36-mediated uptake of dietary oleic acid, serves as a molecular sensor linking fat ingestion to satiety.

  16. Streaking into Middle School Science: The Dell Streak Pilot Project

    ERIC Educational Resources Information Center

    Austin, Susan Eudy

    2012-01-01

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the…

  17. Streaking into Middle School Science: The Dell Streak Pilot Project

    ERIC Educational Resources Information Center

    Austin, Susan Eudy

    2012-01-01

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the…

  18. Higgs mass from neutrino-messenger mixing

    NASA Astrophysics Data System (ADS)

    Byakti, Pritibhajan; Khosa, Charanjit K.; Mummidi, V. S.; Vempati, Sudhir K.

    2017-03-01

    The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, A t , relaxing these constraints. The detailed survey of these models [1, 2] so far considered messenger mixings with only MSSM superfields. In the present work, we extend the survey to MSSM with inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass in the inverse seesaw model are not significant in the minimal gauge mediation model, unless one considers messenger-matter interaction terms. We classify all possible models with messenger-matter interactions and perform thorough numerical analysis to find out the promising models. We found that out of the 17 possible models 9 of them can lead to Higgs mass within the observed value without raising the sfermion masses significantly. The successful models have stop masses ˜1.5 TeV with small or negligible mixing and yet a light CP even Higgs at 125 GeV.

  19. Endogenous Arabidopsis messenger RNAs transported to distant tissues.

    PubMed

    Thieme, Christoph J; Rojas-Triana, Monica; Stecyk, Ewelina; Schudoma, Christian; Zhang, Wenna; Yang, Lei; Miñambres, Miguel; Walther, Dirk; Schulze, Waltraud X; Paz-Ares, Javier; Scheible, Wolf-Rüdiger; Kragler, Friedrich

    2015-03-23

    The concept that proteins and small RNAs can move to and function in distant body parts is well established. However, non-cell-autonomy of small RNA molecules raises the question: To what extent are protein-coding messenger RNAs (mRNAs) exchanged between tissues in plants? Here we report the comprehensive identification of 2,006 genes producing mobile RNAs in Arabidopsis thaliana. The analysis of variant ecotype transcripts that were present in heterografted plants allowed the identification of mRNAs moving between various organs under normal or nutrient-limiting conditions. Most of these mobile transcripts seem to follow the phloem-dependent allocation pathway transporting sugars from photosynthetic tissues to roots via the vasculature. Notably, a high number of transcripts also move in the opposite, root-to-shoot direction and are transported to specific tissues including flowers. Proteomic data on grafted plants indicate the presence of proteins from mobile RNAs, allowing the possibility that they may be translated at their destination site. The mobility of a high number of mRNAs suggests that a postulated tissue-specific gene expression profile might not be predictive for the actual plant body part in which a transcript exerts its function.

  20. Sweet spot supersymmetry and composite messengers

    NASA Astrophysics Data System (ADS)

    Ibe, Masahiro; Kitano, Ryuichiro

    2008-05-01

    Sweet spot supersymmetry is a phenomenological effective Lagrangian of weak scale supersymmetry with a certain set of natural assumptions. This framework is designed to avoid problems in low-energy phenomenology and cosmology of supersymmetric models. We discuss a class of dynamical models of supersymmetry breaking and its mediation, whose low-energy effective description falls into this framework. Hadron fields in the dynamical models play a role of the messengers of the supersymmetry breaking. As is always true in the models of the sweet spot supersymmetry, the messenger scale is predicted to be 105 GeV ≲Mmess ≲1010 GeV. Various values of the effective number of messenger fields Nmess are possible depending on the choice of the gauge group.

  1. Sweet Spot Supersymmetry and Composite Messengers

    SciTech Connect

    Ibe, Masahiro; Kitano, Ryuichiro

    2007-10-30

    Sweet spot supersymmetry is a phenomenologically and cosmologically perfect framework to realize a supersymmetric world at short distance. We discuss a class of dynamical models of supersymmetry breaking and its mediation whose low-energy effective description falls into this framework. Hadron fields in the dynamical models play a role of the messengers of the supersymmetry breaking. As is always true in the models of the sweet spot supersymmetry, the messenger scale is predicted to be 10{sup 5} GeV {approx}< M{sub mess} {approx}< 10{sup 10} GeV. Various values of the effective number of messenger fields N{sub mess} are possible depending on the choice of the gauge group.

  2. Intercultural Learning via Instant Messenger Interaction

    ERIC Educational Resources Information Center

    Jin, Li; Erben, Tony

    2007-01-01

    This paper reports on a qualitative study investigating the viability of instant messenger (IM) interaction to facilitate intercultural learning in a foreign language class. Eight students in a Chinese as a foreign language (CFL) class participated in the study. Each student was paired with a native speaker (NS) of Chinese, and each pair…

  3. Liven up Your Student Dramatics with Commedia dell' Arte.

    ERIC Educational Resources Information Center

    Potter, Jonathan

    1980-01-01

    Suggests using the ancient Commedia dell' Arte technique of establishing characters and a plot and then allowing the actors to create their own play. Indicates that this improves student performances even in more traditional plays. (TJ)

  4. 11. REPRESENTATIVE VIEW OF DELL AVENUE VEHICULAR BRIDGES, LOOKING WEST ...

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

    11. REPRESENTATIVE VIEW OF DELL AVENUE VEHICULAR BRIDGES, LOOKING WEST FROM SOUTH SIDE OF LINNIE CANAL. THIS PARTICULAR BRIDGE IS LOCATED OVER LINNIE CANAL. - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA

  5. Liven up Your Student Dramatics with Commedia dell' Arte.

    ERIC Educational Resources Information Center

    Potter, Jonathan

    1980-01-01

    Suggests using the ancient Commedia dell' Arte technique of establishing characters and a plot and then allowing the actors to create their own play. Indicates that this improves student performances even in more traditional plays. (TJ)

  6. MESSENGER Gets Closer to Mercury than Ever Before

    NASA Image and Video Library

    2014-07-28

    MESSENGER Gets Closer to Mercury than Ever Before. This image is one of the highest resolution images taken by NASA MESSENGER spacecraft to date. It features a field of secondary craters in Mercury northern smooth plains.

  7. Coulomb Interactions between Cytoplasmic Electric Fields and Phosphorylated Messenger Proteins Optimize Information Flow in Cells

    PubMed Central

    Gatenby, Robert A.; Frieden, B. Roy

    2010-01-01

    Background Normal cell function requires timely and accurate transmission of information from receptors on the cell membrane (CM) to the nucleus. Movement of messenger proteins in the cytoplasm is thought to be dependent on random walk. However, Brownian motion will disperse messenger proteins throughout the cytosol resulting in slow and highly variable transit times. We propose that a critical component of information transfer is an intracellular electric field generated by distribution of charge on the nuclear membrane (NM). While the latter has been demonstrated experimentally for decades, the role of the consequent electric field has been assumed to be minimal due to a Debye length of about 1 nanometer that results from screening by intracellular Cl− and K+. We propose inclusion of these inorganic ions in the Debye-Huckel equation is incorrect because nuclear pores allow transit through the membrane at a rate far faster than the time to thermodynamic equilibrium. In our model, only the charged, mobile messenger proteins contribute to the Debye length. Findings Using this revised model and published data, we estimate the NM possesses a Debye-Huckel length of a few microns and find this is consistent with recent measurement using intracellular nano-voltmeters. We demonstrate the field will accelerate isolated messenger proteins toward the nucleus through Coulomb interactions with negative charges added by phosphorylation. We calculate transit times as short as 0.01 sec. When large numbers of phosphorylated messenger proteins are generated by increasing concentrations of extracellular ligands, we demonstrate they generate a self-screening environment that regionally attenuates the cytoplasmic field, slowing movement but permitting greater cross talk among pathways. Preliminary experimental results with phosphorylated RAF are consistent with model predictions. Conclusion This work demonstrates that previously unrecognized Coulomb interactions between

  8. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr.; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Slavin, James A.

    2012-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA's Discovery Program, was inserted into orbit about the planet Mercury in March 2011. MESSENGER's three flybys of Mercury in 2008-2009 marked the first spacecraft visits to the innermost planet since the Mariner 10 flybys in 1974-1975. The unprecedented orbital operations are yielding new insights into the nature and evolution of Mercury. The scientific questions that frame the MESSENGER mission led to the mission measurement objectives to be achieved by the seven payload instruments and the radio science experiment. Interweaving the full set of required orbital observations in a manner that maximizes the opportunity to satisfy all mission objectives and yet meet stringent spacecraft pointing and thermal constraints was a complex optimization problem that was solved with a software tool that simulates science observations and tracks progress toward meeting each objective. The final orbital observation plan, the outcome of that optimization process, meets all mission objectives. MESSENGER's Mercury Dual Imaging System is acquiring a global monochromatic image mosaic at better than 90%coverage and at least 250 m average resolution, a global color image mosaic at better than 90%coverage and at least 1 km average resolution, and global stereo imaging at better than 80%coverage and at least 250 m average resolution. Higher-resolution images are also being acquired of targeted areas. The elemental remote sensing instruments, including the Gamma-Ray and Neutron Spectrometer and the X-Ray Spectrometer, are being operated nearly continuously and will establish the average surface abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer is acquiring a global map of spectral reflectance from 300 to 1450 nm wavelength at a range of incidence and emission angles

  9. MESSENGER at Mercury: Early orbital operations

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph L.; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Phillips, Roger J.; Prockter, Louise M.; Slavin, James A.; Zuber, Maria T.; Finnegan, Eric J.; Grant, David G.; MESSENGER Team

    2014-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA's Discovery Program, was inserted into orbit about the planet Mercury in March 2011. MESSENGER's three flybys of Mercury in 2008-2009 marked the first spacecraft visits to the innermost planet since the Mariner 10 flybys in 1974-1975. The unprecedented orbital operations are yielding new insights into the nature and evolution of Mercury. The scientific questions that frame the MESSENGER mission led to the mission measurement objectives to be achieved by the seven payload instruments and the radio science experiment. Interweaving the full set of required orbital observations in a manner that maximizes the opportunity to satisfy all mission objectives and yet meet stringent spacecraft pointing and thermal constraints was a complex optimization problem that was solved with a software tool that simulates science observations and tracks progress toward meeting each objective. The final orbital observation plan, the outcome of that optimization process, meets all mission objectives. MESSENGER's Mercury Dual Imaging System is acquiring a global monochromatic image mosaic at better than 90% coverage and at least 250 m average resolution, a global color image mosaic at better than 90% coverage and at least 1 km average resolution, and global stereo imaging at better than 80% coverage and at least 250 m average resolution. Higher-resolution images are also being acquired of targeted areas. The elemental remote sensing instruments, including the Gamma-Ray and Neutron Spectrometer and the X-Ray Spectrometer, are being operated nearly continuously and will establish the average surface abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer is acquiring a global map of spectral reflectance from 300 to 1450 nm wavelength at a range of incidence and emission

  10. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; hide

    2013-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA's Discovery Program, was inserted into orbit about the planet Mercury in March 2011. MESSENGER's three flybys of Mercury in 2008-2009 marked the first spacecraft visits to the innermost planet since the Mariner 10 flybys in 1974-1975. The unprecedented orbital operations are yielding new insights into the nature and evolution of Mercury. The scientific questions that frame the MESSENGER mission led to the mission measurement objectives to be achieved by the seven payload instruments and the radio science experiment. Interweaving the full set of required orbital observations in a manner that maximizes the opportunity to satisfy all mission objectives and yet meet stringent spacecraft pointing and thermal constraints was a complex optimization problem that was solved with a software tool that simulates science observations and tracks progress toward meeting each objective. The final orbital observation plan, the outcome of that optimization process, meets all mission objectives. MESSENGER's Mercury Dual Imaging System is acquiring a global monochromatic image mosaic at better than 90% coverage and at least 250 m average resolution, a global color image mosaic at better than 90% coverage and at least 1 km average resolution, and global stereo imaging at better than 80% coverage and at least 250 m average resolution. Higher-resolution images are also being acquired of targeted areas. The elemental remote sensing instruments, including the Gamma-Ray and Neutron Spectrometer and the X-Ray Spectrometer, are being operated nearly continuously and will establish the average surface abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer is acquiring a global map of spectral reflectance from 300 to 1450 nm wavelength at a range of incidence and emission

  11. The Sinkholes at "Piano dell'Acqua

    NASA Astrophysics Data System (ADS)

    Iovine, G. G. R.; Parise, M.; Caloiero, T.; Lanza, G.; Suriano, S.

    2012-04-01

    Five sinkholes have recently been identified in the territory of San Basile (Northern Calabria, Southern Italy), in locality "Piano dell'Acqua". The sinkholes are located in a hilly setting, where the main landform is represented by a slight valley draining toward the east. The sinkholes are limited in size, with maximum diameter of 10 m, and maximum depth of 2.5 m. Two of them are elongated, whilst the remaining three are circular. The area where the sinkholes develop is characterized by Pliocene conglomerate and sand, likely dislocated by tectonic lines. The sinkholes were initially examined by means of multi-temporal aerial photos, and the outcomes from this analysis were checked in the field through geological, structural and geomorphological surveys. At the same time, an historical analysis was started in order to collect and critically evaluate the existing information and testimonies about age of occurrence of the phenomena. At this aim, several interviews with local inhabitants were performed, and a number of archives scrutinized. As a result, the study allowed to hypothesize that two sinkholes developed during the winter 2000-2001, with likely rapid formation. Two other cases probably originated during the 70's, as also suggested by the age of the vegetation hosted within the sinkholes. The last sinkhole, eventually, opened sometime between February 2001 and November 2007. According to the collected testimonies, a further phase of sinkhole development might have occurred in the first half of the past Century, but no field evidence of this older phase has been found so far. Analysis of the seismic catalogues showed that no earthquake can be identified as possible trigger of any of the sinkholes at Piano dell'Acqua. Therefore, the origin of the studied phenomena should be related to sub-cutaneous erosion, within an area that is rich in groundwater (as also shown by the site name, meaning "Water Plain"). Local changes in the water table, both related to

  12. Attitude Sensor and Gyro Calibration for Messenger

    NASA Technical Reports Server (NTRS)

    O'Shaughnessy, Daniel; Pittelkau, Mark E.

    2007-01-01

    The Redundant Inertial Measurement Unit Attitude Determination/Calibration (RADICAL(TM)) filter was used to estimate star tracker and gyro calibration parameters using MESSENGER telemetry data from three calibration events. We present an overview of the MESSENGER attitude sensors and their configuration is given, the calibration maneuvers are described, the results are compared with previous calibrations, and variations and trends in the estimated calibration parameters are examined. The warm restart and covariance bump features of the RADICAL(TM) filter were used to estimate calibration parameters from two disjoint telemetry streams. Results show that the calibration parameters converge faster with much less transient variation during convergence than when the filter is cold-started at the start of each telemetry stream.

  13. The Energy Messenger, Number 1, Volume 4

    SciTech Connect

    Stancil, J.

    1995-01-01

    `The Energy Messenger` is a Department of Energy publication on energy activities of interest to American Indians. The first issue of 1995 (in a magazine format) includes articles on: tribes winning grants to develop energy resources, recruiting of internships for DOE, information about Title XXVI-Indian Energy Resources, American Indian Heritage Month, tribal perspective on DOE actions, joint ventures between tribes and the DOE, and brief description of recent DOE activities.

  14. MESSENGER Observations of Substorm Activity at Mercury

    NASA Astrophysics Data System (ADS)

    Sun, W. J.; Slavin, J. A.; Fu, S.; Raines, J. M.; Zong, Q. G.; Poh, G.; Jia, X.; Sundberg, T.; Gershman, D. J.; Pu, Z.; Zurbuchen, T.; Shi, Q.

    2015-12-01

    MErcury Surface, Space ENviroment, GEochemistry, and Ranging (MESSENGER) magnetic field and plasma measurements taken during crossings of Mercury's magnetotail from 2011 to 2014 have been investigated for substorms. A number of events with clear Earth-like growth phase and expansion phase signatures were found. The thinning of the plasma sheet and the increase of magnetic field intensity in the lobe were observed during the growth phase and plasma sheet was observed to thicken during the expansion phase, which are similar to the observations at Earth. But the time scale of Mercury's substorm is only several minutes comparing with the several hours at Earth [Sun et al., 2015a]. Detailed analysis of magnetic field fluctuations during the substorm expansion phase have revealed low frequency plasma waves, e.g. Pi2-like pulsations. The By fluctuations accompanying substorm dipolarizations are consistent with pulses of field-aligned currents near the high latitude edge of the plasma sheet. Further study shows that they are near-circularly polarized electromagnetic waves, most likely Alfvén waves. Soon afterwards the plasma sheet thickened and MESSENGER detected a series of compressional waves. We have also discussed their possible sources [Sun et al., 2015b]. Sun, W.-J., J. A. Slavin, S. Y. Fu, et al. (2015a), MESSENGER observations of magnetospheric substorm activity in Mercury's near magnetotail. Geophys. Res. Lett., 42, 3692-3699. doi: 10.1002/2015GL064052.Sun, W.-J., J. A. Slavin, S. Y. Fu, et al. (2015b), MESSENGER observations of Alfvénic and compressional waves during Mercury's substorms. Geophys. Res. Lett., 42, in press. doi: 10.1002/ 2015GL065452.

  15. Messenger RNA Methylation Regulates Glioblastoma Tumorigenesis.

    PubMed

    Dixit, Deobrat; Xie, Qi; Rich, Jeremy N; Zhao, Jing Crystal

    2017-04-10

    Messenger RNA (mRNA) modification provides an additional layer of gene regulation in cells. In this issue of Cancer Cell, Zhang et al. report that ALKBH5, a demethylase of the mRNA modification N(6)-methyladenosine, regulates proliferation and self-renewal of glioblastoma stem-like cells by modulating pre-mRNA stability and expression of the FOXM1 gene.

  16. Mercury's Na Exosphere from MESSENGER data

    NASA Astrophysics Data System (ADS)

    Killen, Rosemary M.; Burger, M. H.; Cassidy, T. A.; Sarantos, M.; Vervack, R. J.; McClintock, W. E.; Merkel, A. W.; Sprague, A. L.; Solomon, S. C.

    2012-10-01

    MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UVVS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft to infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The hot portion of the source appears to be highly variable. The authors acknowledge support from NASA through the MESSENGER Participating Scientist Program and Planetary Atmospheres research grants.

  17. Holographic gauge mediation via strongly coupled messengers

    SciTech Connect

    McGuirk, Paul; Shiu, Gary; Sumitomo, Yoske

    2010-01-15

    We consider a relative of semidirect gauge mediation where the hidden sector exists at large 't Hooft coupling. Such scenarios can be difficult to describe using perturbative field theory methods but may fall into the class of holographic gauge mediation scenarios, meaning that they are amenable to the techniques of gauge/gravity duality. We use a recently found gravity solution to examine one such case, where the hidden sector is a cascading gauge theory resulting in a confinement scale not much smaller than the messenger mass. In the original construction of holographic gauge mediation, as in other examples of semidirect gauge mediation at strong coupling, the primary contributions to visible sector soft terms come from weakly coupled messenger mesons. In contrast to these examples, we describe the dual of a gauge theory where there are significant contributions from scales in which the strongly coupled messenger quarks are the effective degrees of freedom. In this regime, the visible sector gaugino mass can be calculated entirely from holography.

  18. Occupational injuries among Boston bicycle messengers.

    PubMed

    Dennerlein, Jack Tigh; Meeker, John D

    2002-12-01

    Urban bicycle couriers may have a high incidence of injuries. Most messengers work as contractors and hence their injuries are not well documented. To quantify injury rates and severity among urban bicycle couriers a convenience sample of 113 couriers in the city of Boston completed a two-page self-administered survey. Most working couriers have suffered at least one injury resulting either in days lost from work (70%) and in visits to a health-care professional or hospital (55%). The annual incidence rate for injuries resulting in days away from work was 47/100-bike couriers. Bone fractures accounted for the most days lost from work, followed by dislocations, sprains, and strains. Collisions and avoiding collisions with motor vehicles, including being "doored," and collisions with pedestrians accounted for the majority (66%) of events leading to injury. Twenty-four percent of messengers reported wearing a helmet on a regular basis, and 32% have health insurance. Urban bicycle messengers are a poorly documented, largely unstudied workforce who suffer a very high rate of occupational injury. Copyright 2002 Wiley-Liss, Inc.

  19. MESSENGER: The Discovery Mission to Mercury

    NASA Astrophysics Data System (ADS)

    McNutt, R. L.; Solomon, S. C.; Gold, R. E.; Domingue, D. L.

    2004-12-01

    NASA's MErcury, Surface, Space ENvironment, GEochenistry, and Ranging (MESSENGER) spacecraft, launched on 3 August 2004, has begun its voyage to initiate a new era in our understanding of the terrestrial planets. The mission, spacecraft, and payload are designed to answer six fundamental questions regarding the innermost planet: What planetary formational processes led to Mercury's high metal/silicate ratio? What is the geological history of Mercury? What are the nature and origin of Mercury's magnetic field? What are the structure and state of Mercury's core? What are the radar-reflective materials at Mercury's poles? What are the important volatile species and their sources and sinks on and near Mercury? Planet formational hypotheses will be tested by measuring the surface abundances of major elements by X-ray and gamma-ray spectrometry. The geological history will be determined from high-resolution color imaging of the heavily cratered highlands, intercrater plains, and smooth plains. MESSENGER will provide detailed views of both the Caloris basin and its antipodal terrain. Topographic, mineralogical, and elemental abundance data will be used to seek evidence of volcanic features and units. Measurement of Mercury's magnetic field and its interaction with the solar wind will distinguish the intrinsic dipole and quadrupole components while separating these from the current systems driven by solar-wind-induced convection. The structure of the internal field will put constraints on dynamo models. Such models will also be constrained by measuring Mercury's libration to determine the extent of a fluid outer core. Both water ice and sulfur have been postulated as major constituents of the high-radar-backscatter polar deposits. MESSENGER will combine gamma-ray and neutron spectrometry of the surface with ultraviolet spectrometry and in situ particle measurements to detect both neutral and charged species originating from the surface. Such measurements will address the

  20. Unsupervised Classification of MESSENGER MASC Data

    NASA Astrophysics Data System (ADS)

    de Sanctis, M. Cristina; Capaccioni, Fabrizio; Filacchione, Gianrico; Ammannito, Eleonora

    2010-05-01

    The MESSENGER spacecraft flew by Mercury as part of its journey to Mercury orbit insertion. The Mercury At-mospheric and Surface Composition Spectrometer (MASCS) observed Mercury during the first two flybys, includ-ing high-spatial-and spectral-resolution visible to near-infrared (IR) spectra of the Mercury surface. The Visible and InfraRed Spectrograph (VIRS) component of MASCS consists of two linear photodiode arrays covering a spectral range 320-1450 nm. We applied classification method to MASCS data in order to extract information on the mineralogy of Mercury. The classification of the Messenger data will permit to obtain maps of Mercury surface, giving us indication of the different mineralogy and maturity present on the Hermean surface. The data were pre-processed applying photometric correction and the VIS and NIR data were collected in a single spectrum. The data set show very similar featureless spectra. The main differences are in the reflectance levels and in the spectral slopes. To emphasize the spectral differences we have normalized the spectra to an average reflectance spectrum for each flyby. This allows to point out variation of different regions with respect to the aver-age spectral behaviour. Two different approaches have been used to analyze MASCS data of the two Messenger flybys: ISODATA unsupervised classification and a classification based on three different spectral slopes (in the wavelengths' ranges 0.3-0.55, 0.55-0.8 and 0.95-1.49 µm). The identified classes shows differences linked with slopes and reflectance's level: the proposed methods allows to correlate the most important classes with different morphological features on Mercury's surface which differ for weathering, maturity and composition. Our analysis is done in order to test and verify these classification methods that shall be necessary to analyze similar data harvested by SIMBIO-SYS/VIHI (Visible and Infrared Hyper-spectral Imager) aboard the future ESA's BepiColombo mission

  1. Mercury's Na Exosphere from MESSENGER Data

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Burger, M. H.; Cassidy, T. A.; Sarantos, M.; Vervack, R. J.; McClintock, W. El; Merkel, A. W.; Sprague, A. L.; Solomon, S. C.

    2012-01-01

    MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UWS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft :0 infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The portion of the hot/cold source appears to be highly variable.

  2. Mercury's Na Exosphere from MESSENGER Data

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Burger, M. H.; Cassidy, T. A.; Sarantos, M.; Vervack, R. J.; McClintock, W. El; Merkel, A. W.; Sprague, A. L.; Solomon, S. C.

    2012-01-01

    MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UWS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft :0 infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The portion of the hot/cold source appears to be highly variable.

  3. [Pathophysiological implications of the chemical messengers].

    PubMed

    Blázquez Fernández, Enrique

    2009-01-01

    To maintain a physical organization and a different composition of its surroundings environment, living beings use a great part of the energy that they produce. Vital processes require an elevated number of reactions which are regulated and integrated by chemical messengers. They use autocrine, paracrine, endocrine and synaptic signals through receptors of cell surface, nuclear or associated with ionic chanels, enzymes, trimeric G proteins and to intracellular kinases. Through these mechanisms pheromones play an important role in the relationships between different individuals, and hormones are able to regulate the integrative functions of our organism. In the nervous system, neurotransmitters, neuromodulators, sensors and receptors between other messengers, play functions of great relevance, while growth factors stimulate cell proliferation and cytokines have many effects but the most important is the ones related with the control of the immflamatory process. Alterations of these messengers permit us a better understanding of the diseases and possibly of its treatments in a near future. Modifications of the expression of genes from the nuclear and mitochondrial genomas are responsible of monogenic, polygenic and mitochondrial diseases, while alterations in the activities of dopamine and serotonin neurotransmitters are related with schizophrenia, Parkinson disease and depression, respectively. Other example is the hyperthyroidism of the Graves-Bassedow disease due to the competitive interference of the LATS immunoglobulin with TSH at the level of the folicular cells producing thyroid hormones Twenty five years ago in the reviews on the mechanisms of insulin action, there was presentations in which the insulin receptor was located in the plasma membrane of the target cells while in the cytoplasm only a big interrogative was observed, that at present is replaced by chemical mediators cascades responsible of the multiple effects of insulin. This finding is similar to

  4. [Posttranscriptional messenger RNA modifications in eukaryotes].

    PubMed

    Laptev, I G; Golovina, A Ya; Sergiev, P V; Dontsova, O A

    2015-01-01

    Genomewide mapping of posttranscriptional modification in eukaryotic RNA allowed to reveal tens of thousands modification sites. Among modified nucleotides of eukaryotic RNA 6-methyladenosine, 5-methylcytidine, pseudouridine, inosine, and others. Many modification sites are conserved, many are regulated. Function is known for a small subset of modified nucleotides, while the role of majority of them is still obscure. Global character of mRNA modifications allowed scientists to coin a new term, RNA epigenetics. The review is about posttranscriptional messenger RNA modifications in eukaryotes. Main modifications, their role in cell, their mapping techniques and proteins, that are responsible for such RNA modifications are observed.

  5. Gravitational Waves and Multi-Messenger Astronomy

    NASA Technical Reports Server (NTRS)

    Centrella, Joan M.

    2010-01-01

    Gravitational waves are produced by a wide variety of sources throughout the cosmos, including the mergers of black hole and neutron star binaries/compact objects spiraling into central black holes in galactic nuclei, close compact binaries/and phase transitions and quantum fluctuations in the early universe. Observing these signals can bring new, and often very precise, information about their sources across vast stretches of cosmic time. In this talk we will focus on thee opening of this gravitational-wave window on the universe, highlighting new opportunities for discovery and multi-messenger astronomy.

  6. MESSENGER observations of Mercury's Plasma Mantle

    NASA Astrophysics Data System (ADS)

    Jasinski, J. M.; Slavin, J. A.; Raines, J. M.; DiBraccio, G. A.

    2016-12-01

    We present a survey of plasma mantle observations identified in particle and magnetic field data from four years of MESSENGER spacecraft measurements of Mercury's magnetosphere. The plasma mantle is a region of solar wind plasma entry into the nightside high-latitude magnetosphere. The two common observational signatures of this region are ion energy latitude dispersions as well as diamagnetic depressions. From these observations we estimate the contribution of plasma from the solar wind via the mantle and infer magnitude and variability in the cross-magnetospheric electric fields present at Mercury's dynamic magnetosphere.

  7. An allosteric self-splicing ribozyme triggered by a bacterial second messenger.

    PubMed

    Lee, Elaine R; Baker, Jenny L; Weinberg, Zasha; Sudarsan, Narasimhan; Breaker, Ronald R

    2010-08-13

    Group I self-splicing ribozymes commonly function as components of selfish mobile genetic elements. We identified an allosteric group I ribozyme, wherein self-splicing is regulated by a distinct riboswitch class that senses the bacterial second messenger c-di-GMP. The tandem RNA sensory system resides in the 5' untranslated region of the messenger RNA for a putative virulence gene in the pathogenic bacterium Clostridium difficile. c-di-GMP binding by the riboswitch induces folding changes at atypical splice site junctions to modulate alternative RNA processing. Our findings indicate that some self-splicing ribozymes are not selfish elements but are harnessed by cells as metabolite sensors and genetic regulators.

  8. Multi-Messenger Astronomy and Dark Matter

    NASA Astrophysics Data System (ADS)

    Bergström, Lars

    This chapter presents the elaborated lecture notes on Multi-Messenger Astronomy and Dark Matter given by Lars Bergström at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". One of the main problems of astrophysics and astro-particle physics is that the nature of dark matter remains unsolved. There are basically three complementary approaches to try to solve this problem. One is the detection of new particles with accelerators, the second is the observation of various types of messengers from radio waves to gamma-ray photons and neutrinos, and the third is the use of ingenious experiments for direct detection of dark matter particles. After giving an introduction to the particle universe, the author discusses the relic density of particles, basic cross sections for neutrinos and gamma-rays, supersymmetric dark matter, detection methods for neutralino dark matter, particular dark matter candidates, the status of dark matter detection, a detailled calculation on an hypothetical "Saas-Fee Wimp", primordial black holes, and gravitational waves.

  9. MESSENGER observations of magnetopause structure at Mercury

    NASA Astrophysics Data System (ADS)

    DiBraccio, G. A.; Slavin, J. A.; Boardsen, S. A.; Anderson, B. J.; Korth, H.; Zurbuchen, T.; Raines, J. M.; McNutt, R. L.; Solomon, S. C.

    2011-12-01

    On 18 March 2011, MESSENGER became the first spacecraft to orbit Mercury, providing a new opportunity to study the outer boundary of the innermost planet's magnetosphere - the magnetopause. The 12-hour orbital period yields a minimum of four magnetopause crossings per day, which facilitates the investigation of the effect of the interplanetary magnetic field (IMF) on the magnetopause structure. Here we use data from MESSENGER's Magnetometer (MAG) and Fast Imaging Plasma Spectrometer (FIPS) to characterize the magnetopause. A minimum variance analysis (MVA) is executed to transform the MAG data into current-sheet coordinates. In this new coordinate system we determine (1) the temporal duration and, with assumptions, the thickness of the magnetopause, (2) the magnetic shear angle across the boundary, and (3) the normal magnetic field across the current sheet, from which we infer the rate of reconnection. FIPS measurements provide a validation of the structure of the magnetopause determined from the MAG data, i.e., whether the magnetopause is magnetically open or closed, on the basis of its permeability to solar wind ions. The results of our analysis indicate that the structure of Mercury's magnetopause is highly responsive to IMF direction and, whenever the shear angle is greater than 90°, is generally open to the solar wind plasma under normal magnetic field components of order 1-10 nT.

  10. Multi-messenger aspects of cosmic neutrinos

    NASA Astrophysics Data System (ADS)

    Ahlers, Markus

    2016-04-01

    The recent observation of TeV-PeV neutrinos by IceCube has opened a new window to the high-energy Universe. I will discuss this signal in the context of multi-messenger astronomy. For extragalactic source scenarios the corresponding gamma-rays are not directly observable due to interactions with the cosmic radiation backgrounds. Nevertheless, the isotropic sub-TeV gamma ray background observed by Fermi-LAT contains indirect information from secondary emission produced in electromagnetic cascades. On the other hand, observation of PeV gamma rays would provide a smoking-gun signal for Galactic emission. Interestingly, the overall energy density of the observed neutrino flux is close to a theoretical limit for neutrino production in ultra-high energy cosmic ray sources and might indicate a common origin of these phenomena. I will highlight various multi-messenger relations and their implications for neutrino source scenarios. This article is an excerpt from an ICRC 2015 proceedings contribution [1].

  11. MESSENGER observations of Mercury's magnetic field structure

    NASA Astrophysics Data System (ADS)

    Johnson, Catherine L.; Purucker, Michael E.; Korth, Haje; Anderson, Brian J.; Winslow, Reka M.; Al Asad, Manar M. H.; Slavin, James A.; Alexeev, Igor. I.; Phillips, Roger J.; Zuber, Maria T.; Solomon, Sean C.

    2012-12-01

    We present a baseline, time-averaged model for Mercury's magnetosphere, derived from MESSENGER Magnetometer data from 24 March to 12 December 2011, comprising the spacecraft's first three Mercury years in orbit around the innermost planet. The model, constructed under the approximation that the magnetospheric shape can be represented as a paraboloid of revolution, includes two external (magnetopause and magnetotail) current systems and an internal (dipole) field and allows for reconnection. We take advantage of the geometry of the orbital Magnetometer data to estimate all but one of the model parameters, and their ranges, directly from the observations. These parameters are then used as a priori constraints in the paraboloid magnetospheric model, and the sole remaining parameter, the dipole moment, is estimated as 190 nT RM3 from a grid search. We verify that the best fit dipole moment is insensitive to changes in the other parameters within their determined ranges. The model provides an excellent first-order fit to the MESSENGER observations, with a root-mean-square misfit of less than 20 nT globally. The results show that the magnetopause field strength ranges from 10% to 50% of the dipole field strength at observation locations on the dayside and at nightside latitudes north of 60°N. Globally, the residual signatures observed to date are dominated by the results of magnetospheric processes, confirming the dynamic nature of Mercury's magnetosphere.

  12. Implementing an ROI Measurement Process at Dell Computer.

    ERIC Educational Resources Information Center

    Tesoro, Ferdinand

    1998-01-01

    This return-on-investment (ROI) evaluation study determined the business impact of the sales negotiation training course to Dell Computer Corporation. A five-step ROI measurement process was used: Plan-Develop-Analyze-Communicate-Leverage. The corporate sales information database was used to compare pre- and post-training metrics for both training…

  13. Implementing an ROI Measurement Process at Dell Computer.

    ERIC Educational Resources Information Center

    Tesoro, Ferdinand

    1998-01-01

    This return-on-investment (ROI) evaluation study determined the business impact of the sales negotiation training course to Dell Computer Corporation. A five-step ROI measurement process was used: Plan-Develop-Analyze-Communicate-Leverage. The corporate sales information database was used to compare pre- and post-training metrics for both training…

  14. Playing Funny: An Introduction to "Commedia dell' Arte."

    ERIC Educational Resources Information Center

    Grantham, Barry

    2001-01-01

    Discusses the use of "Commedia," a way of performing inspired by the historical "Commedia dell' Arte." Notes that it has proved a fertile source of inspiration for all types of physical and stylized theatre and a useful training tool for performers in many fields. Presents a series of exercises designed to introduce the student to Commedia…

  15. Playing Funny: An Introduction to "Commedia dell' Arte."

    ERIC Educational Resources Information Center

    Grantham, Barry

    2001-01-01

    Discusses the use of "Commedia," a way of performing inspired by the historical "Commedia dell' Arte." Notes that it has proved a fertile source of inspiration for all types of physical and stylized theatre and a useful training tool for performers in many fields. Presents a series of exercises designed to introduce the student to Commedia…

  16. Imaging During MESSENGER's Second Flyby of Mercury

    NASA Astrophysics Data System (ADS)

    Chabot, N. L.; Prockter, L. M.; Murchie, S. L.; Robinson, M. S.; Laslo, N. R.; Kang, H. K.; Hawkins, S. E.; Vaughan, R. M.; Head, J. W.; Solomon, S. C.; MESSENGER Team

    2008-12-01

    During MESSENGER's second flyby of Mercury on October 6, 2008, the Mercury Dual Imaging System (MDIS) will acquire 1287 images. The images will include coverage of about 30% of Mercury's surface not previously seen by spacecraft. A portion of the newly imaged terrain will be viewed during the inbound portion of the flyby. On the outbound leg, MDIS will image additional previously unseen terrain as well as regions imaged under different illumination geometry by Mariner 10. These new images, when combined with images from Mariner 10 and from MESSENGER's first Mercury flyby, will enable the first regional- resolution global view of Mercury constituting a combined total coverage of about 96% of the planet's surface. MDIS consists of both a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). During MESSENGER's second Mercury flyby, the following imaging activities are planned: about 86 minutes before the spacecraft's closest pass by the planet, the WAC will acquire images through 11 different narrow-band color filters of the approaching crescent planet at a resolution of about 5 km/pixel. At slightly less than 1 hour to closest approach, the NAC will acquire a 4-column x 11-row mosaic with an approximate resolution of 450 m/pixel. At 8 minutes after closest approach, the WAC will obtain the highest-resolution multispectral images to date of Mercury's surface, imaging a portion of the surface through 11 color filters at resolutions of about 250-600 m/pixel. A strip of high-resolution NAC images, with a resolution of approximately 100 m/pixel, will follow these WAC observations. The NAC will next acquire a 15-column x 13- row high-resolution mosaic of the northern hemisphere of the departing planet, beginning approximately 21 minutes after closest approach, with resolutions of 140-300 m/pixel; this mosaic will fill a large gore in the Mariner 10 data. At about 42 minutes following closest approach, the WAC will acquire a 3x3, 11-filter, full- planet mosaic with an

  17. 75 FR 28657 - Dell Products LP-Parmer North Location, a Subsidiary of Dell, Inc., Including On-Site Leased...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-21

    ...., Including On-Site Leased Workers From Belcan Services Group, Hawkins Associates, Inc., Integrated Human Capital, MagRabbit, Manpower and Spherion Corporation; Round Rock, TX; Dell Products LP--Parmer North One...., including on-site leased workers from Belcan Services Group, Hawkins Associates Inc., Integrated...

  18. The cosmic mult-messenger background field

    NASA Astrophysics Data System (ADS)

    Hartmann, Dieter

    2016-04-01

    The cosmic star formation history associated with baryon flows within the large scale structure of the expanding Universe has many important consequences, such as cosmic chemical- and galaxy evolution. Stars and accreting compact objects subsequently produce light, from the radio band to the highest photon energies, and dust within galaxies reprocesses a significant fraction of this light into the IR region. The Universe creates a radiation background that adds to the relic field from the big bang, the CMB. In addition, Cosmic Rays are created on variouys scales, and interact with this diffuse radiation field, and neutrinos are added as well. A multi-messenger field is created whose evolution with redshift contains a tremendous amount of cosmological information. We discuss several aspects of this story, emphasizing the background in the HE regime and the neutrino sector, and disccus the use of gamma-ray sources as probes.

  19. Messenger RNA modifications: Form, distribution, and function.

    PubMed

    Gilbert, Wendy V; Bell, Tristan A; Schaening, Cassandra

    2016-06-17

    RNA contains more than 100 distinct modifications that promote the functions of stable noncoding RNAs in translation and splicing. Recent technical advances have revealed widespread and sparse modification of messenger RNAs with N(6)-methyladenosine (m(6)A), 5-methylcytosine (m(5)C), and pseudouridine (Ψ). Here we discuss the rapidly evolving understanding of the location, regulation, and function of these dynamic mRNA marks, collectively termed the epitranscriptome. We highlight differences among modifications and between species that could instruct ongoing efforts to understand how specific mRNA target sites are selected and how their modification is regulated. Diverse molecular consequences of individual m(6)A modifications are beginning to be revealed, but the effects of m(5)C and Ψ remain largely unknown. Future work linking molecular effects to organismal phenotypes will broaden our understanding of mRNA modifications as cell and developmental regulators. Copyright © 2016, American Association for the Advancement of Science.

  20. Gauge mediation models with adjoint messengers

    NASA Astrophysics Data System (ADS)

    Gogoladze, Ilia; Mustafayev, Azar; Shafi, Qaisar; Ün, Cem Salih

    2016-10-01

    We present a class of models in the framework of gauge mediation supersymmetry breaking where the messenger fields transform in the adjoint representation of the standard model gauge symmetry. To avoid unacceptably light right-handed sleptons in the spectrum we introduce a nonzero U (1 )B-L D-term. This leads to an additional contribution to the soft supersymmetry breaking mass terms which makes the right-handed slepton masses compatible with the current experimental bounds. We show that in this framework the observed 125 GeV Higgs boson mass can be accommodated with the sleptons accessible at the LHC, while the squarks and gluinos lie in the multi-TeV range. We also discuss the issue of the fine-tuning and show that the desired relic dark matter abundance can also be accommodated.

  1. Mercury's magnetosphere after MESSENGER's first flyby.

    PubMed

    Slavin, James A; Acuña, Mario H; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Gloeckler, George; Gold, Robert E; Ho, George C; Killen, Rosemary M; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Nittler, Larry R; Raines, Jim M; Schriver, David; Solomon, Sean C; Starr, Richard D; Trávnícek, Pavel; Zurbuchen, Thomas H

    2008-07-04

    Observations by MESSENGER show that Mercury's magnetosphere is immersed in a comet-like cloud of planetary ions. The most abundant, Na+, is broadly distributed but exhibits flux maxima in the magnetosheath, where the local plasma flow speed is high, and near the spacecraft's closest approach, where atmospheric density should peak. The magnetic field showed reconnection signatures in the form of flux transfer events, azimuthal rotations consistent with Kelvin-Helmholtz waves along the magnetopause, and extensive ultralow-frequency wave activity. Two outbound current sheet boundaries were observed, across which the magnetic field decreased in a manner suggestive of a double magnetopause. The separation of these current layers, comparable to the gyro-radius of a Na+ pickup ion entering the magnetosphere after being accelerated in the magnetosheath, may indicate a planetary ion boundary layer.

  2. Cosmic muons, as messengers from the Universe

    SciTech Connect

    Brancus, I. M.; Rebel, H.

    2015-02-24

    Penetrating from the outer space into the Earth atmosphere, primary cosmic rays are producing secondary radiation by the collisions with the air target subsequently decaying in hadrons, pions, muons, electrons and photons, phenomenon called Extensive air Shower (EAS). The muons, considered as the “penetrating” component, survive the propagation to the Earth and even they are no direct messenger of the Universe, they reflect the features of the primary particles. The talk gives a description of the development of the extensive air showers generating the secondary particles, especially the muon component. Results of the muon flux and of the muon charge ratio, (the ratio between the positive and the negative muons), obtained in different laboratories and in WILLI experiment, are shown. At the end, the contribution of the muons measured in EAS to the investigation of the nature of the primary cosmic rays is emphasized in KASCADE and WILLI-EAS experiments.

  3. [Irisin: a messenger from the gods?].

    PubMed

    Moreno, María; Moreno-Navarrete, José María; Fernández-Real, José Manuel

    2014-01-01

    Due to the need to understand the basis of the metabolic benefits of exercise, irisin was discovered a few years ago. This cytokine, secreted by skeletal muscle due to exercise, should have positive effects on energetic metabolism. In particular, it could act as a messenger on white adipose tissue, modifying its phenotype into the beige adipocyte, and increasing its thermogenic capacity. Since it was described, there have been numerous studies led to depict its function, with the aim of determining if irisin could become a therapeutic target in the context of diseases associated with a caloric excess, such as obesity and diabetes. In this review, the irisin discovery is summarized, along with its in vitro and in vivo effects described up until now.

  4. MESSENGER Observations of Mercury's Dynamic Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2009-01-01

    MESSENGER's 14 January and 6 October 2008 encounters with Mercury have provided new measurements dynamic variations in the coupled atmosphere magnetosphere system. The two flybys took place under very different interplanetary magnetic field (IMF) conditions. The northward IMF during the first encounter produced a very quiet, stable magnetosphere. Neutral sodium atoms and photo-ions were observed to high altitudes ; > 2000 km, even in the subsolar region demonstrating the important role played by more energetic neutral atom production processes such as sputtering. Consistent with predictions of magnetospheric models for northward IMF, the neutral atmosphere was observed to have its strongest sources in the high latitude northern hemisphere for the first flyby. The southward IMF for the second encounter revealed a highly dynamic magnetosphere. Reconnection between the interplanetary and planetary magnetic fields is known to control the rate of energy transfer from the solar wind and to drive magnetospheric convection. The MESSENGER magnetic field measurements revealed that the rate at which interplanetary magnetic fields were reconnecting to planetary fields was a factor of 10 greater than is usually observed at Earth. This extremely high reconnection results in a large magnetic field component normal to the magnetopause and the formation of flux transfer events that are much larger relative to the size of the forward magnetosphere than is observed at Earth. The resulting magnetospheric configuration allows the solar wind access to much of the dayside surface of the Mercury. This widespread impingement of the solar wind on Mercury's surface is a likely source of the less structured sodium exosphere imaged during the second flyby and quite possibly the high degree of exospheric temporal variability observed by ground-based telescopes.

  5. Current Understanding of Mercury's Magnetosphere before MESSENGER

    NASA Astrophysics Data System (ADS)

    Krimigis, S. M.

    The MESSENGER spacecraft is scheduled to be launched mid-May, 2004 on a trajectory that includes two flybys (October 07, July 08) and eventual orbit insertion in July 2009 around the planet Mercury. Embedded in its payload are instruments to examine the basic properties of the planet's magnetosphere, including magnetometer, plasma, and energetic particle measurements (Gold et al, 2001). Our present knowledge of Mercury's magnetosphere is derived from two nightside Mariner 10 flybys in 1974, 1975 that established the presence of an intrinsic magnetic field and some energetic particles. Unfortunately not even the magnetic dipole term was well-resolved, and the fluxes and identity of energetic particles have been a subject of extensive discussion and varying interpretations (e.g. Armstrong et al, 1975, Christon, 1989). There has been evidence of field-aligned currents (e.g. Slavin et al, 1997), but alternative interpretations of magnetic signatures suggest that the magnetosphere may be driven by changing external boundary conditions (Luhman et al, 1998). These uncertainties, coupled with the observed presence of volatiles (H, He, O, Na, K, Ca) raise obvious questions on current closure, hot plasma injection and acceleration, the frequency with which the planetary surface is exposed to the solar wind, and potential sputtering of material due to particle impingement on the regolith. The talk will review our current knowledge and describe the measurements expected from MESSENGER that will address some of the key science questions. Armstrong et al, JGR, 80, 4015, 1975 Gold et al, Planet and Space Sci, 49, 1467, 2001 Christon, S.P., JGR, 94, 6481, 1989 Slavin et al, Planet and Space Sci, 45, 133, 1997 Luhman et al, JGR, 103, 9113, 1998

  6. WhatsApp Messenger as an Adjunctive Tool for Telemedicine: An Overview

    PubMed Central

    2017-01-01

    Background The advent of telemedicine has allowed physicians to deliver medical treatment to patients from a distance. Mobile apps such as WhatsApp Messenger, an instant messaging service, came as a novel concept in all fields of social life, including medicine. The use of instant messaging services has been shown to improve communication within medical teams by providing means for quick teleconsultation, information sharing, and starting treatment as soon as possible. Objective The aim of this study was to perform a comprehensive systematic review of present literature on the use of the WhatsApp Messenger app as an adjunctive health care tool for medical doctors. Methods Searches were performed in PubMed, EMBASE, and the Cochrane Library using the term “whatsapp*” in articles published before January 2016. A bibliography of all relevant original articles that used the WhatsApp Messenger app was created. The level of evidence of each study was determined according to the Oxford Levels of Evidence ranking system produced by the Oxford Centre for Evidence-Based Medicine. The impact and the indications of WhatsApp Messenger are discussed in order to understand the extent to which this app currently functions as an adjunctive tool for telemedicine. Results The database search identified a total of 30 studies in which the term “whatsapp*” was used. Each article’s list of references was evaluated item-by-item. After literature reviews, letters to the editor, and low-quality studies were excluded, a total of 10 studies were found to be eligible for inclusion. Of these studies, 9 had been published in the English language and 1 had been published in Spanish. Five were published by medical doctors. Conclusions The pooled data presents compelling evidence that the WhatsApp Messenger app is a promising system, whether used as a communication tool between health care professionals, as a means of communication between health care professionals and the general public

  7. WhatsApp Messenger as an Adjunctive Tool for Telemedicine: An Overview.

    PubMed

    Giordano, Vincenzo; Koch, Hilton; Godoy-Santos, Alexandre; Dias Belangero, William; Esteves Santos Pires, Robinson; Labronici, Pedro

    2017-07-21

    The advent of telemedicine has allowed physicians to deliver medical treatment to patients from a distance. Mobile apps such as WhatsApp Messenger, an instant messaging service, came as a novel concept in all fields of social life, including medicine. The use of instant messaging services has been shown to improve communication within medical teams by providing means for quick teleconsultation, information sharing, and starting treatment as soon as possible. The aim of this study was to perform a comprehensive systematic review of present literature on the use of the WhatsApp Messenger app as an adjunctive health care tool for medical doctors. Searches were performed in PubMed, EMBASE, and the Cochrane Library using the term "whatsapp*" in articles published before January 2016. A bibliography of all relevant original articles that used the WhatsApp Messenger app was created. The level of evidence of each study was determined according to the Oxford Levels of Evidence ranking system produced by the Oxford Centre for Evidence-Based Medicine. The impact and the indications of WhatsApp Messenger are discussed in order to understand the extent to which this app currently functions as an adjunctive tool for telemedicine. The database search identified a total of 30 studies in which the term "whatsapp*" was used. Each article's list of references was evaluated item-by-item. After literature reviews, letters to the editor, and low-quality studies were excluded, a total of 10 studies were found to be eligible for inclusion. Of these studies, 9 had been published in the English language and 1 had been published in Spanish. Five were published by medical doctors. The pooled data presents compelling evidence that the WhatsApp Messenger app is a promising system, whether used as a communication tool between health care professionals, as a means of communication between health care professionals and the general public, or as a learning tool for providing health care information

  8. Mercury's interior from MESSENGER geodetic measurements

    NASA Astrophysics Data System (ADS)

    Genova, Antonio; Mazarico, Erwan; Goossens, Sander; Lemoine, Frank G.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.

    2016-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft completed more than 4 years of operations in orbit about Mercury. One of the main mission goals was the determination of the interior structure of Mercury enabled by geodetic observations of the topography, gravity field, rotation, and tides by the Mercury Laser Altimeter (MLA) and radio science system. MLA acquired over 25 million individual measurements of Mercury's shape that are mostly limited to the northern hemisphere because of MESSENGER's eccentric orbit. However, the lack of laser altimetry in the southern hemisphere has been partly compensated by ˜400 occultations of spacecraft radio signals. X-band radio tracking data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, the planet's obliquity, and the Love number k2. The combination of altimetry and radio measurements provides a powerful tool for the investigation of Mercury's orientation and tides, which enable a better understanding of the interior structure of the planet. The MLA measurements have been assembled into a digital elevation model (DEM) of the northern hemisphere. We then used individual altimetric measurements from the spacecraft for orbit determination, together with the radio tracking, over a continuous span of time using a batch least-squares filter. All observations were combined to recover directly the gravity field coefficients, obliquity, librations, and tides by minimizing the discrepancies between the computed observables and actual measurements. We will present the estimated 100×100 gravity field model, the obliquity, the Love number k2, and, for the first time, the tidal phase lag φ and the amplitude of the longitudinal libration from radio and altimetry data. The k2 phase provides information on Mercury's dissipation and mantle viscosity and allows a determination of the Q factor. A refinement of

  9. Calcium in Mercury's Exosphere: Modeling MESSENGER Data

    NASA Technical Reports Server (NTRS)

    Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Merkel, Aimee; Vervack, Ronald J.; Sarantos, Menelaos; Sprague, Ann L.

    2011-01-01

    Mercury is surrounded by a surface-bounded exosphere comprised of atomic species including hydrogen, sodium, potassium, calcium, magnesium, and likely oxygen. Because it is collisionless. the exosphere's composition represents a balance of the active source and loss processes. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface. Space ENvironment. GEochemistry. and Ranging (MESSENGER) spacecraft has made high spatial-resolution observations of sodium, calcium, and magnesium near Mercury's surface and in the extended, anti-sunward direction. The most striking feature of these data has been the substantial differences in the spatial distribution of each species, Our modeling demonstrates that these differences cannot be due to post-ejection dynamics such as differences in photo-ionization rate and radiation pressure. but instead point to differences in the source mechanisms and regions on the surface from which each is ejected. The observations of calcium have revealed a strong dawn/dusk asymmetry. with the abundance over the dawn hemisphere significantly greater than over the dusk. To understand this asymmetry, we use a Monte Carlo model of Mercury's exosphere that we developed to track the motions of exospheric neutrals under the influence of gravity and radiation pressure. Ca atoms can be ejected directly from the surface or produced in a molecular exosphere (e.g., one consisting of CaO). Particles are removed from the system if they stick to the surface or escape from the model region of interest (within 15 Mercury radii). Photoionization reduces the final weighting given to each particle when simulating the Ca radiance. Preliminary results suggest a high temperature ( I-2x 10(exp 4) K) source of atomic Ca concentrated over the dawn hemisphere. The high temperature is consistent with the dissociation of CaO in a near-surface exosphere with scale height <= 100 km, which imparts 2 eV to the freshly produced Ca atom. This

  10. Calcium in Mercury's Exosphere: Modeling MESSENGER Data

    NASA Astrophysics Data System (ADS)

    Burger, M. H.; Killen, R. M.; McClintock, W. E.; Merkel, A. W.; Vervack, R. J.; Sarantos, M.; Sprague, A. L.

    2011-12-01

    Mercury is surrounded by a surface-bounded exosphere known to contain hydrogen, sodium, potassium, calcium, and magnesium. Because the exosphere is collisionless, its composition represents a balance of active source and loss processes. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has made high-spatial-resolution observations of sodium, calcium, and magnesium near Mercury's surface and in the extended, anti-sunward direction. The most striking feature of these data is the substantial differences among species, which was detected during three close flybys of the planet and has been persistantly present during MESSENGER's orbital phase. Our modeling demonstrates that these differences are not because of post-ejection dynamics such as differences in photo-ionization rate and radiation pressure, but rather result from differences in the source mechanisms and regions on the surface from which each species is ejected. The observations of calcium have revealed a strong dawn/dusk asymmetry, with the abundance over the dawn hemisphere substantially greater than that on the dusk side. To understand this asymmetry, we use a Monte Carlo model of Mercury's exosphere that we developed to track the motions of exospheric neutrals under the influence of gravity and radiation pressure. In this model, Ca atoms can be ejected directly from the surface or produced by ejection of CaO followed by dissociation to produce Ca and O. Particles are removed from the system if they stick to the surface or escape from the model region of interest (within 15 Mercury radii). Photoionization reduces the final weighting given to each particle when simulating the Ca radiance. Data from the flybys are consistent with a high temperature (~1-2 x 104 K) source of atomic Ca concentrated over the dawn hemisphere. Such a high temperature resutls from dissociation of CaO in a near

  11. Messenger Observations of Mercury's Bow Shock and Magnetopause

    NASA Technical Reports Server (NTRS)

    Slavin J. A.; Acuna, M. H.; Anderson, B. J.; Benna, M.; Gloeckler, G.; Krimigis, S. M.; Raines, M.; Schriver, D.; Travnicek, P.; Zurbuchen, T. H.

    2008-01-01

    The MESSENGER spacecraft made the first of three flybys of Mercury on January 14.2008 (1). New observations of solar wind interaction with Mercury were made with MESSENGER'S Magnetometer (MAG) (2.3) and Energetic Particle and Plasma Spectrometer (EPPS) - composed of the Energetic Particle Spectrometer (EPS) and Fast Imaging Plasma Spectrometer (FIPS) (3,4). These MESSENGER observations show that Mercury's magnetosphere has a large-scale structure that is distinctly Earth-like, but it is immersed in a comet-like cloud of planetary ions [5]. Fig. 1 provides a schematic view of the coupled solar wind - magnetosphere - neutral atmosphere - solid planet system at Mercury.

  12. Messenger RNA processing in Methanocaldococcus (Methanococcus) jannaschii

    PubMed Central

    Zhang, Jian; Olsen, Gary J.

    2009-01-01

    Messenger RNA (mRNA) processing plays important roles in gene expression in all domains of life. A number of cases of mRNA cleavage have been documented in Archaea, but available data are fragmentary. We have examined RNAs present in Methanocaldococcus (Methanococcus) jannaschii for evidence of RNA processing upstream of protein-coding genes. Of 123 regions covered by the data, 31 were found to be processed, with 30 including a cleavage site 12–16 nucleotides upstream of the corresponding translation start site. Analyses with 3′-RACE (rapid amplification of cDNA ends) and 5′-RACE indicate that the processing is endonucleolytic. Analyses of the sequences surrounding the processing sites for functional sites, sequence motifs, or potential RNA secondary structure elements did not reveal any recurring features except for an AUG translation start codon and (in most cases) a ribosome binding site. These properties differ from those of all previously described mRNA processing systems. Our data suggest that the processing alters the representation of various genes in the RNA pool and therefore, may play a significant role in defining the balance of proteins in the cell. PMID:19717546

  13. Neutrinos as the messengers of CPT violation

    NASA Astrophysics Data System (ADS)

    Borissov, Liubomir Anguelov

    CPT violation has the potential to explain all three existing neutrino oscillation signals without enlarging the neutrino sector. CPT violation in the Dirac mass terms of the three neutrino flavors preserves Lorentz invariance, but generates in dependent masses for neutrinos and antineutrinos. This specific signature can be motivated by braneworld scenarios with extra dimensions, where neutrinos are the natural messengers for Standard Model physics of CPT violation in the bulk. A simple model of maximal CPT violation is sufficient to explain the exisiting neutrino data, while accommodating the recent results from the KamLAND experiment and making dramatic predictions for the ongoing MiniBooNE experiment. In addition, the model fits the existing SuperKamiokande data, at least as well as the standard atmospheric neutrino oscillation models. Another attractive feature of the presented model is that it provides a new promising mechanism for baryogenesis, which obviates two of the three Sakharov conditions necessary to generate the baryon asymmetry of the universe. CPT-violating scenarios can give new insights about the possible nature of neutrinos. Majorana neutrino masses are still allowed, but in general, there are no longer Majorana neutrinos in the conventional sense. However, CPT-violating models still have interesting consequences for neutrinoless double beta decay. Compared to the usual case, while the larger mass scale (from LSND) may appear, a greater degree of suppression can also occur.

  14. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    NASA Technical Reports Server (NTRS)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.; Sarantos, Menelaos

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  15. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    NASA Technical Reports Server (NTRS)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variation but there is little or no year-to-year variation; we do not see the episodic variability reported by ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere is about 1200 K, much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  16. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    NASA Technical Reports Server (NTRS)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variation but there is little or no year-to-year variation; we do not see the episodic variability reported by ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere is about 1200 K, much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  17. ACTH Action on Messenger RNA Stability Mechanisms

    PubMed Central

    Desroches-Castan, Agnès; Feige, Jean-Jacques; Cherradi, Nadia

    2017-01-01

    The regulation of mRNA stability has emerged as a critical control step in dynamic gene expression. This process occurs in response to modifications of the cellular environment, including hormonal variations, and regulates the expression of subsets of proteins whose levels need to be rapidly adjusted. Modulation of messenger RNA stability is usually mediated by stabilizing or destabilizing RNA-binding proteins (RNA-BP) that bind to the 3′-untranslated region regulatory motifs, such as AU-rich elements (AREs). Destabilizing ARE-binding proteins enhance the decay of their target transcripts by recruiting the mRNA decay machineries. Failure of such mechanisms, in particular misexpression of RNA-BP, has been linked to several human diseases. In the adrenal cortex, the expression and activity of mRNA stability regulatory proteins are still understudied. However, ACTH- or cAMP-elicited changes in the expression/phosphorylation status of the major mRNA-destabilizing protein TIS11b/BRF1 or in the subcellular localization of the stabilizing protein Human antigen R have been reported. They suggest that this level of regulation of gene expression is also important in endocrinology. PMID:28163695

  18. Predicting poor peripheral blood stem cell collection in patients with multiple myeloma receiving pre-transplant induction therapy with novel agents and mobilized with cyclophosphamide plus granulocyte-colony stimulating factor: results from a Gruppo Italiano Malattie EMatologiche dell'Adulto Multiple Myeloma Working Party study.

    PubMed

    Musto, Pellegrino; Simeon, Vittorio; Grossi, Alberto; Gay, Francesca; Bringhen, Sara; Larocca, Alessandra; Guariglia, Roberto; Pietrantuono, Giuseppe; Villani, Oreste; D'Arena, Giovanni; Cuomo, Carmela; Musto, Clelia; Morabito, Fortunato; Petrucci, Maria Teresa; Offidani, Massimo; Zamagni, Elena; Tacchetti, Paola; Conticello, Concetta; Milone, Giuseppe; Palumbo, Antonio; Cavo, Michele; Boccadoro, Mario

    2015-04-17

    A still not well defined proportion of patients with multiple myeloma (MM) and eligible for autologous stem cell transplantation (AuSCT) fails to mobilize CD34+ peripheral blood stem cells (PBSC) at all or to collect an adequate number for a safe procedure or sufficient for multiple transplants. These so-called "poor-mobilizers" are difficult to be predicted, due to marked difference across previous heterogeneous studies. We aimed to develop a method based on simple clinical parameters for predicting unsuccessful (<2×10(6)/kg) or sub-optimal (<5×10(6)/kg) collections of CD34+ PBSC in newly diagnosed MM patients eligible for AuSCT, treated with novel agents and receiving an homogeneous mobilizing therapy with cyclophosphamide and granulocyte-colony stimulating factor (G-CSF). To this purpose, 1,348 patients enrolled in five consecutive Italian clinical trials were retrospectively analysed. Age, baseline low peripheral blood cell counts, use of lenalidomide, and haematological toxicity developed during induction were taken into account as possible factors associated with poor mobilization. Overall, 280 patients (20.8%) showed either sub-optimal (167 patients, 12.4%) or unsuccessful (113 patients, 8.4%) collections. All analysed parameters negatively influenced the procedure, but only age and haematological toxicity during induction maintained their significance at multivariate analysis. Based on ordinal logistic regression model, we constructed a risk heat-map where the four parameters were pooled and weighted according to their relevance as single or combined variables. This model was predictive for different probabilities of failure, suboptimal or optimal outcomes. We found that about one fifth of newly diagnosed MM fails to collect an adequate number of PBSC. Our model, based on a large group of patients treated frontline with novel agents and receiving the most popular mobilizing approach currently employed in Europe, is applicable in individual subjects and

  19. 3. Photocopy of photograph (from Fort Dodge Messenger, no issue ...

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

    3. Photocopy of photograph (from Fort Dodge Messenger, no issue or date known) Photographer and date unknown INTERIOR, STAIRWAY - Swain-Vincent House, 824 Third Avenue, South, Fort Dodge, Webster County, IA

  20. 5. Photocopy of photograph (from Fort Dodge Messenger, no issue ...

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

    5. Photocopy of photograph (from Fort Dodge Messenger, no issue or date known) Photographer and date unknown INTERIOR, FIRST FLOOR, SITTING ROOM, DETAIL OF FIREPLACE - Swain-Vincent House, 824 Third Avenue, South, Fort Dodge, Webster County, IA

  1. MESSENGER Observations of Mercury's Bow Shock and Magnetopause

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Boardsen, S. A.; Sarantos, M.; Acuna, M. H.; Anderson, B. J.; Baker, D. N.; Benna, M.; Gloeckler, G.; Gold, R. E.; Ho, G. C.; Korth, H.; Krimigis, S. M.; Livi, S. A.; McNutt, R. L., Jr.; Raines, J. M.; Schriver, D.; Solomon, S. C.; Travnicek, P.; Zurbuchen, T. H.

    2008-01-01

    MESSENGER'S 14 January 2008 encounter with Mercury will provide the first new observations of the solar wind interaction with this planet since the Mariner 10 flybys that took place over 30 years ago. The closest approach distance for this first MESSENGER flyby is targeted for an altitude of 200 km as compared with the 707 km and 327 km attained by Mariner 10 on 29 March 1974 and 16 March 1975, respectively. The locations of the bow shock and magnetopause boundaries observed by MESSENGER will be examined and compared against those found in the earlier Mariner 10 measurements and the predictions of theoretical models and numerical simulations. The structure of the magnetopause will be investigated for the presence of flux transfer events or other evidence of magnetic reconnection as will the more general implications of these new MESSENGER bow shock and magnetopause observations for the global solar wind interaction with Mercury.

  2. Release, Identification, and Isolation of Messenger RNA from Mammalian Ribosomes

    PubMed Central

    Blobel, Günter

    1971-01-01

    The puromycin-induced dissociation, at high ionic strength, of active ribosomes from reticulocytes resulted in the release of protein-free, apparently undegraded, messenger RNA for globin, which was identified by centrifugation on a sucrose density gradient. This procedure should make messenger RNA from various cells available for isolation on a large scale, and has several advantages over procedures that use detergents or magnesium chelators. PMID:5279524

  3. Processivity and Coupling in Messenger RNA Transcription

    PubMed Central

    Aitken, Stuart; Robert, Marie-Cécile; Alexander, Ross D.; Goryanin, Igor; Bertrand, Edouard; Beggs, Jean D.

    2010-01-01

    Background The complexity of messenger RNA processing is now being uncovered by experimental techniques that are capable of detecting individual copies of mRNA in cells, and by quantitative real-time observations that reveal the kinetics. This processing is commonly modelled by permitting mRNA to be transcribed only when the promoter is in the on state. In this simple on/off model, the many processes involved in active transcription are represented by a single reaction. These processes include elongation, which has a minimum time for completion and processing that is not captured in the model. Methodology In this paper, we explore the impact on the mRNA distribution of representing the elongation process in more detail. Consideration of the mechanisms of elongation leads to two alternative models of the coupling between the elongating polymerase and the state of the promoter: Processivity allows polymerases to complete elongation irrespective of the promoter state, whereas coupling requires the promoter to be active to produce a full-length transcript. We demonstrate that these alternatives have a significant impact on the predicted distributions. Models are simulated by the Gillespie algorithm, and the third and fourth moments of the resulting distribution are computed in order to characterise the length of the tail, and sharpness of the peak. By this methodology, we show that the moments provide a concise summary of the distribution, showing statistically-significant differences across much of the feasible parameter range. Conclusions We conclude that processivity is not fully consistent with the on/off model unless the probability of successfully completing elongation is low—as has been observed. The results also suggest that some form of coupling between the promoter and a rate-limiting step in transcription may explain the cell's inability to maintain high mRNA levels at low noise—a prediction of the on/off model that has no supporting evidence. PMID

  4. Mercury's global evolution: New views from MESSENGER

    NASA Astrophysics Data System (ADS)

    Hauck, S. A., II; Byrne, P. K.; Denevi, B. W.; Grott, M.; McCoy, T.; Stanley, S.

    2015-12-01

    MESSENGER's exploration of Mercury has revealed the planet's rich and dynamic history and provided new constraints on the processes that control its internal evolution. Mercury's surface records evidence of an extensive geological history. This evidence includes resurfacing by impacts and volcanism prior to the end of the late heavy bombardment (LHB) and a subsequent rapid waning of effusive volcanism. Volcanism is an important indicator of the history of melt production. Thousands of globally distributed, contractional tectonic landforms collectively have accommodated a decrease in Mercury's radius of 5-7 km since the end of the LHB. Such contraction results from planetary cooling and crystallization within Mercury's metallic core. Measurements of surface chemistry have provided constraints on internal radiogenic heat production necessary to understand more fully Mercury's thermal evolution. Elemental abundances also reveal that Mercury is strongly chemically reduced, suggesting that the core's iron is alloyed with silicon as well as sulfur, which constrains the dynamics and crystallization of the metallic core. Magnetometer observations show that Mercury's dynamo-generated, dominantly dipolar field is displaced ~500 km northward along the rotation axis. Low-altitude magnetic field observations late in the mission led to the discovery of crustal magnetization in Mercury's ancient crust, dating to at least 3.7 Ga, which places a new constraint on the timing of the dynamo. Monte Carlo parameterized mantle convection models, constrained by these observations, indicate that for global contraction of 7 km or less, mantle convection persists to the present ~40% of the time, with the likelihood of modern convection decreasing with less global contraction. Slow present cooling in these models indicates that dynamo generation is strongly influenced by both a static layer at the top of the core and convective motions within the core driven by compositional buoyancy.

  5. MESSENGER observations of magnetopause structure at Mercury

    NASA Astrophysics Data System (ADS)

    DiBraccio, G. A.; Slavin, J. A.; Boardsen, S. A.; Anderson, B. J.; Korth, H.; Zurbuchen, T. H.; Raines, J. M.; McNutt, R. L., Jr.; Solomon, S. C.

    2012-04-01

    MESSENGER Magnetometer (MAG) data from the first series of "hot-season" orbits at Mercury, when periapsis was positioned over the subsolar region, have been used to augment our initial studies to characterize the magnetopause structure as a function of local time. Minimum variance analysis (MVA) was applied to transform the MAG data into boundary-normal coordinates in order to determine (1) the thickness of the magnetopause, (2) the magnetic shear angle across the boundary, and (3) the normal magnetic field, BN, across the current sheet and, by inference, the rate of reconnection and the magnetosphere electric potential. We applied the MVA to all distinct magnetopause crossings within the subsolar region between 0800 and 1600 local time and within ± 25° latitude. A well-defined normal direction, specified by a ratio of the eigenvalue for intermediate variance to that for minimum variance that is greater than 8, was determined for 72 crossings. For this data set, 72.2% of the magnetopause traversals had a substantial normal component (i.e., BN > 4 nT). For a mean boundary motion velocity of 10 km s-1, the average current sheet thickness was 29 km, which is comparable to 2 gyroradii for solar wind protons. The mean ratio of the normal magnetic field component to the total field magnitude, a measure of the reconnection rate, was 0.2 and is independent of magnetic field shear angle across the magnetopause. We conclude that Mercury's magnetopause structure is generally open to the solar wind plasma under a wide range of interplanetary magnetic field shear angles.

  6. Star Messenger: Galileo at the Millennium

    NASA Astrophysics Data System (ADS)

    White, R. E.

    1999-05-01

    Smith College has recently established the Louise B. and Edmund J. Kahn Liberal Arts Institute to foster interdisciplinary scholarship among the faculty. In the 1999-2000 academic year, the Kahn Institute is sponsoring a project entitled "Star Messenger: Galileo at the Millennium." The project will explore the impact of the astronomical discoveries of Galileo and his contemporaries on the Renaissance world-view and also use Galileo's experience as a lens for examining scientific and cultural developments at the symbolic juncture represented by the year 2000. Seven faculty fellows and 10-12 student fellows will participate in a year-long colloquium pursuing these themes, aided by the participation of some five Visiting Fellows. The inaugural public event will be a symposium on the historical Galileo, with presentation by three noted scholars, each of whom will return to campus for a second meeting with the Kahn colloquium. Additional events will include an exhibit of prints, artifacts, and rare books related to Galileo and his time, an early music concert featuring music composed by Galileo's father, and a series of other events sponsored by diverse departments and programs, all related to the broad themes of the Galileo project. The culminating events will be the premiere of a new music theater work, which will encapsulate the insights of the colloquium about human reactions to novel insights about the world, and a symposium presenting the research results of faculty and student fellows. The symposium will feature a capstone lecture by an visionary scholar projecting the implication of historical and contemporary trends into the future.

  7. Neutrino-Gamma Multi-Messenger Source Detection via the Astrophysical Multi-Messenger Observatory Network

    NASA Astrophysics Data System (ADS)

    Fixelle, Josh; Miles, S.; AMON

    2014-01-01

    The idea of multi-messenger event detection has long been explored in the context of above-threshold analysis performed by the IceCube collaboration using Swift BAT and by the Amanda collaboration using BATSE. While these investigations produced null results, they left the event space of sub-threshold events untouched. This untapped event space, combined with the addition of new observatories for various bands and messenger types, provides the obvious niche for a GBN style network to exist: AMON. We consider Monte-carlo models of pair-wise detection between sub-threshold IceCube neutrino doublets, sub-threshold neutrino-gamma doublets with Swift BAT, and with sub-threshold higher multiplicity neutrino-gamma coincidences with Fermi LAT. Several detection methods were considered and compared to the status quo analyses of neutrino doublets by IceCube, demonstrating significant sensitivity gain. The MC model analysis was followed by an archival doublet analysis between IceCube-40 and Fermi LAT data within their co-temporal window of observation. Several methods for detecting statistical signal excess in the archival analysis were considered, providing an upper limit on source population parameters for the given analysis sensitivity.

  8. Ovalbumin Messenger RNA: Evidence That the Initial Product of Transcription Is the Same Size as Polysomal Ovalbumin Messenger

    PubMed Central

    McKnight, G. Stanley; Schimke, Robert T.

    1974-01-01

    The messenger RNA for ovalbumin, the major secretory protein of the chick oviduct, appears not to be made as a high-molecular-weight precursor when artifacts due to aggregation are eliminated. No ovalbumin messenger RNA sequences that will hybridize to complementary DNA made against ovalbumin mRNA are found in concentrated samples of hen oviduct RNA larger than 28 S. The sensitivity of the hybridization assay is sufficient to detect less than one molecule of ovalbumin mRNA precursor per tubular gland cell. Newly synthesized ovalbumin messenger RNA isolated from immature chicks stimulated briefly by estrogen is the same size as that found in hen polyribosomes. We conclude that ovalbumin messenger RNA does not undergo any significant change in molecular weight from its initial transcription to its incorporation into polyribosomes. PMID:4530986

  9. A Spectral Map Of Mercury From MESSENGER

    NASA Astrophysics Data System (ADS)

    Izenberg, N. R.; Pahsai, P.; Klima, R. L.; Blewett, D. T.; Goudge, T. A.; Solomon, S. C.

    2013-12-01

    We use orbital data from the Mercury Surface and Atmospheric Composition Spectrometer (MASCS) Visible and Near Infrared Spectrograph (VIRS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft to study subtle compositional variations across the surface of Mercury. VIRS reflectance spectra obtained from orbit allow identification and classification of spectral units, many of which collocate with geologic features such as pyroclastic deposits; low-reflectance material (LRM); bright, fresh-appearing impact craters; and hollows. The vast majority of the surface is composed of plains units with brightness and spectral reflectance ratios (e.g., 415 nm / 750 nm and 310 nm / 390 nm) that vary within a small range about mean values for the planet. Analysis of VIRS reflectance data in the context of Mercury Dual Imaging System (MDIS) color and high-resolution images enables identification of large regions with similar spectral properties. Our spectral map of Mercury covers approximately 70% of the planet (excluding polar regions and two regions for which calibration refinement is pending). On the basis of brightness, spectral ratio variations, and superposition relationships in the image data, we define four large-scale spectral units in Mercury plains, as well as six additional spectral units of smaller area. The four large-scale spectral units cover (1) 48.7% (brightness and spectral ratio parameters within a few percent of planetary mean values) (2) 31.6% (higher reflectance, higher 310 nm / 390 nm values than mean), (3) 12.9% (higher reflectance, lower 415 nm / 750 nm values than mean), and (4) 6.8% (lower reflectance and higher 310 nm / 390 nm values than mean) of the mapped area. Spectrally defined plains units correspond broadly to plains units defined by morphology and color imaging; e.g., unit 2 corresponds to the previously defined high-reflectance red plains (HRP), unit 3 to the northern smooth plains and the smooth plains

  10. When Poetry became Ethnography and Other Flying Pig Tales in Honor of Dell Hymes

    ERIC Educational Resources Information Center

    Cahnmann-Taylor, Melisa

    2011-01-01

    Cahnmann-Taylor remembers her first encounter with Dell Hymes at an open mic event at the annual meeting of the American Anthropological Association. She puzzles his complex stance on the role ethnographic poems might play in one's ethnographic project. In Dell Hymes's honor, she shares a poetic rendering of a speech event from her bilingual…

  11. A Literary and Linguistic Analysis of Scott O'Dell's "The Captive".

    ERIC Educational Resources Information Center

    Stewig, John Warren

    This paper carefully examines the literary elements Scott O'Dell uses in his children's novel "The Captive," that so successfully engage even a reluctant reader. The paper explores the writer's style and subtle use of detail and foreshadowing. Quoting specific examples, the paper points out O'Dell's imaginative syntax and his ability to…

  12. Enabling Customization through Web Development: An Iterative Study of the Dell Computer Corporation Website

    ERIC Educational Resources Information Center

    Liu, Chang; Mackie, Brian G.

    2008-01-01

    Throughout the last decade, companies have increased their investment in electronic commerce (EC) by developing and implementing Web-based applications on the Internet. This paper describes a class project to develop a customized computer website which is similar to Dell Computer Corporation's (Dell) website. The objective of this project is to…

  13. Enabling Customization through Web Development: An Iterative Study of the Dell Computer Corporation Website

    ERIC Educational Resources Information Center

    Liu, Chang; Mackie, Brian G.

    2008-01-01

    Throughout the last decade, companies have increased their investment in electronic commerce (EC) by developing and implementing Web-based applications on the Internet. This paper describes a class project to develop a customized computer website which is similar to Dell Computer Corporation's (Dell) website. The objective of this project is to…

  14. When Poetry became Ethnography and Other Flying Pig Tales in Honor of Dell Hymes

    ERIC Educational Resources Information Center

    Cahnmann-Taylor, Melisa

    2011-01-01

    Cahnmann-Taylor remembers her first encounter with Dell Hymes at an open mic event at the annual meeting of the American Anthropological Association. She puzzles his complex stance on the role ethnographic poems might play in one's ethnographic project. In Dell Hymes's honor, she shares a poetic rendering of a speech event from her bilingual…

  15. A Literary and Linguistic Analysis of Scott O'Dell's "The Captive".

    ERIC Educational Resources Information Center

    Stewig, John Warren

    This paper carefully examines the literary elements Scott O'Dell uses in his children's novel "The Captive," that so successfully engage even a reluctant reader. The paper explores the writer's style and subtle use of detail and foreshadowing. Quoting specific examples, the paper points out O'Dell's imaginative syntax and his ability to…

  16. 76 FR 27366 - CEVA Freight, LLC, Dell Logistics Division, Including On-Site Leased Workers From Prologistix...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-11

    ... Employment and Training Administration CEVA Freight, LLC, Dell Logistics Division, Including On-Site Leased..., LLC, Dell Logistics Division, including on-site leased workers from Prologistix, Winston-Salem, North... intent of the Department's certification is to include all workers employed at CEVA Freight, LLC, Dell...

  17. 75 FR 38128 - Ceva Freight, LLC, Dell Logistics Division, Including On-Site Leased Workers From Prologistix and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... Employment and Training Administration Ceva Freight, LLC, Dell Logistics Division, Including On-Site Leased..., LLC, Dell Logistics Division, including on-site leased workers from Prologistix, Winston-Salem, North..., Dell Logistics Division. The Department has determined that these workers were sufficiently under the...

  18. Streaking into middle school science: The Dell Streak pilot project

    NASA Astrophysics Data System (ADS)

    Austin, Susan Eudy

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the Streak could be used as an effective instructional tool, and if it could be considered an effective instructional resource for reviewing and preparing for the science assessments. A mixed method research design was used for the study to analyze both quantitative and qualitative results to determine if the Dell Streaks' utilization could achieve the following: 1. instructional strategies would change, 2. it would be an effective instructional tool, and 3. a comparison of the students' test scores and benchmark assessments' scores would provide statistically significant difference. Through the use of an ANOVA it was determined a statistically significant difference had occurred. A Post Hoc analysis was conducted to identify where the difference occurred. Finally a T-test determined was there was no statistically significance difference between the mean End-of-Grade tests and four quarterly benchmark scores of the control and the experimental groups. Qualitative research methods were used to gather results to determine if the Streaks were an effective instructional tool. Classroom observations identified that the teacher's teaching styles and new instructional strategies were implemented throughout the pilot project. Students had an opportunity to complete a questionnaire three times during the pilot project. Results revealed what the students liked about using the devices and the challenges they were facing. The teacher completed a reflective questionnaire throughout the pilot project and offered valuable reflections about the use of the devices in an educational setting. The reflection data supporting the case study was drawn

  19. Thermal evolution of Mercury as constrained by MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Michel, Nathalie C.; Hauck, Steven A.; Solomon, Sean C.; Phillips, Roger J.; Roberts, James H.; Zuber, Maria T.

    2013-05-01

    observations of Mercury by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft provide new constraints on that planet's thermal and interior evolution. Specifically, MESSENGER observations have constrained the rate of radiogenic heat production via measurement of uranium, thorium, and potassium at the surface, and identified a range of surface compositions consistent with high-temperature, high-degree partial melts of the mantle. Additionally, MESSENGER data have placed new limits on the spatial and temporal variation in volcanic and tectonic activity and enabled determination that the planet's core is larger than previously estimated. Because Mercury's mantle layer is also thinner than previously thought, this result gives greater likelihood to the possibility that mantle convection is marginally supercritical or even that the mantle is not convecting. We simulate mantle convection and magma generation within Mercury's mantle under two-dimensional axisymmetry and a broad range of conditions to understand the implications of MESSENGER observations for the thermal evolution of the planet. These models demonstrate that mantle convection can persist in such a thin mantle for a substantial portion of Mercury's history, and often to the present, as long as the mantle is thicker than ~300 km. We also find that magma generation in Mercury's convecting mantle is capable of producing widespread magmas by large-degree partial melting, consistent with MESSENGER observations of the planet's surface chemistry and geology.

  20. MESSENGER Measurements of Mercury's Magnetic Field during the First Flyby

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Boardsen, S. A.; Acuna, M. H.; Anderson, B. J.; Johnson, C. L.; Korth, H.; Krimigis, S. M.; McNutt, R. L., Jr.; Purucker, M. E.; Solomon, S. C.

    2008-01-01

    On 14 January 2008 the MESSENGER spacecraft will encounter Mercury for the first time. Depending upon the solar wind conditions, this initial flyby will return Magnetometer measurements of Mercury's magnetic field over a time interval lasting between - 30 md 60 min. Closest approach for MESSENGER is targeted for an altitude of 200 km as compared with the 707 krn and 327 km attained by Mariner 10 on 29 March 1974 and 16 March 1975, respectively. Furthermore, the differences in the MESSENGER and Mariner 10 encounter trajectories, with respect both to magnetospheric and body-fixed coordinates are highly complementary and expected to lead to significant improvements in our knowledge of Mercury's magnetic field. We present an overview of the MESSENGER magnetic field observations, an initial subtraction of the magnetic fields attributable to magnetospheric current systems from the total measured magnetic field, and an improved model of Mercury's intrinsic magnetic field. We also discuss the expected advances afforded by the two additional MESSENGER flybys, which occur in October 2008 and September 2009, as well as the orbital phase that will begin in March 201 1.

  1. Imaging second messenger dynamics in developing neural circuits

    PubMed Central

    Dunn, Timothy A.; Feller, Marla B.

    2010-01-01

    A characteristic feature of developing neural circuits is that they are spontaneously active. There are several examples, including the retina, spinal cord and hippocampus, where spontaneous activity is highly correlated amongst neighboring cells, with large depolarizing events occurring with a periodicity on the order of minutes. One likely mechanism by which neurons can “decode” these slow oscillations is through activation of second messengers cascades that either influence transcriptional activity or drive posttranslational modifications. Here we describe recent experiments where imaging has been used to characterize slow oscillations in the cAMP/PKA second messenger cascade in retinal neurons. We review the latest techniques in imaging this specific second messenger cascade, its intimate relationship with changes in intracellular calcium concentration, and several hypotheses regarding its role in neurodevelopment. PMID:18383551

  2. Interplanetary Coronal Mass Ejections from MESSENGER Orbital Observations at Mercury

    NASA Astrophysics Data System (ADS)

    Winslow, R. M.; Lugaz, N.; Philpott, L. C.; Schwadron, N.; Farrugia, C. J.; Anderson, B. J.; Smith, C. W.

    2015-12-01

    We use observations from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, in orbit around Mercury, to investigate interplanetary coronal mass ejections (ICMEs) near 0.3 AU. MESSENGER, the first spacecraft since the 1980s to make in-situ measurements at distances < 0.5 AU, presents a unique opportunity for observing the innermost heliosphere. It also allows studies of ICME evolution as they expand and propagate outward, interacting with the solar wind. In order to catalog ICME events observed by MESSENGER, we design a strict set of selection criteria to identify them based on magnetic field observations only, since reliable solar wind plasma observations are not available from MESSENGER. We identify 61 ICME events observed by the MESSENGER Magnetometer between 2011 and 2014, and present statistical analyses of ICME properties at Mercury. In addition, using existing datasets of ICMEs at 1 AU we investigate key ICME property changes from Mercury to 1 AU. We find good agreement with previous studies for the magnetic field strength dependence on heliospheric distance, r. We have also established three different lines of evidence that ICME deceleration continues beyond the orbit of Mercury: 1) we find a shallow decrease with distance of ˜r-0.45 for the ICME shock speed from Mercury to 1 AU, 2) the average transit speed from the Sun to Mercury for ICMEs in our catalog is ˜20% faster than the average speed from the Sun to 1 AU, 3) the ICME transit time to 1 AU has a weaker dependence on the CME initial coronagraphic speed, as compared to what we predict based on our MESSENGER ICME catalog. Based on our results, future ICME propagation studies should account for ICME speed changes beyond Mercury's heliocentric distances to improve ICME arrival time forecasting. Our ICME database will also prove particularly useful for multipoint spacecraft studies of recent ICMEs, as well as for model validation of ICME properties.

  3. How MESSENGER Meshes Simulations and Games with Citizen Science

    NASA Astrophysics Data System (ADS)

    Hirshon, B.; Chapman, C. R.; Edmonds, J.; Goldstein, J.; Hallau, K. G.; Solomon, S. C.; Vanhala, H.; Weir, H. M.; Messenger Education; Public Outreach (Epo) Team

    2010-12-01

    How MESSENGER Meshes Simulations and Games with Citizen Science In the film The Last Starfighter, an alien civilization grooms their future champion—a kid on Earth—using a video game. As he gains proficiency in the game, he masters the skills he needs to pilot a starship and save their civilization. The NASA MESSENGER Education and Public Outreach (EPO) Team is using the same tactic to train citizen scientists to help the Science Team explore the planet Mercury. We are building a new series of games that appear to be designed primarily for fun, but that guide players through a knowledge and skill set that they will need for future science missions in support of MESSENGER mission scientists. As players score points, they gain expertise. Once they achieve a sufficiently high score, they will be invited to become participants in Mercury Zoo, a new program being designed by Zooniverse. Zooniverse created Galaxy Zoo and Moon Zoo, programs that allow interested citizens to participate in the exploration and interpretation of galaxy and lunar data. Scientists use the citizen interpretations to further refine their exploration of the same data, thereby narrowing their focus and saving precious time. Mercury Zoo will be designed with input from the MESSENGER Science Team. This project will not only support the MESSENGER mission, but it will also add to the growing cadre of informed members of the public available to help with other citizen science projects—building on the concept that engaged, informed citizens can help scientists make new discoveries. The MESSENGER EPO Team comprises individuals from the American Association for the Advancement of Science (AAAS); Carnegie Academy for Science Education (CASE); Center for Educational Resources (CERES) at Montana State University (MSU) - Bozeman; National Center for Earth and Space Science Education (NCESSE); Johns Hopkins University Applied Physics Laboratory (JHU/APL); National Air and Space Museum (NASM); Science

  4. The Impact of Mobile Learning on ESP Learners' Performance

    ERIC Educational Resources Information Center

    Alkhezzi, Fahad; Al-Dousari, Wadha

    2016-01-01

    This study explores the impact of using mobile phone applications, namely Telegram Messenger, on teaching and learning English in an ESP context. The main objective is to test whether using mobile phone applications have an impact on ESP learners' performance by mainly investigating the influence such teaching technique can have on learning…

  5. Messenger in the Barn: Networking in a Learning Environment

    ERIC Educational Resources Information Center

    Rutter, Malcolm

    2009-01-01

    This case study describes the use of a synchronous communication application (MSN Messenger) in a large academic computing environment. It draws on data from interviews, questionnaires and student marks to examine the link between use of the application and success measured through module marks. The relationship is not simple. Total abstainers and…

  6. Instant Messenger in Enrollment Management: Evaluating Use and Effectiveness

    ERIC Educational Resources Information Center

    Zalanowski, Kevin

    2007-01-01

    This study represented a formal quantitative evaluation of the potential for instant messenger (IM) technology as an outreach tool for undergraduate college admission. Conclusions focused on the popularity of IM, and student use in a formal counselor/student relationship. (Contains 4 tables and 2 figures.)

  7. 4. Photocopy of photograph (from Fort Dodge Messenger, no issue ...

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

    4. Photocopy of photograph (from Fort Dodge Messenger, no issue or date known) Photographer and date unknown INTERIOR, FIRST FLOOR, DETAIL OF ARCHED OPENING BETWEEN LIVING ROOM AND DINING ROOM - Swain-Vincent House, 824 Third Avenue, South, Fort Dodge, Webster County, IA

  8. MESSENGER First Images of Comets Encke and ISON

    NASA Image and Video Library

    2013-11-14

    As comets C/2012 S1 ISON and the well-known short-period comet 2P/Encke both approached their closest distances to the Sun in November, 2013, they also passed close to the MESSENGER spacecraft orbiting the innermost planet Mercury.

  9. MESSENGER Observation of Mercury's Magnetopause: Structure and Dynamics

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.; Acuna, M. H.; Anderson, B. J.; Baker, D. N.; Benna, M.; Boardsen, S. A.; Gloeckler, G.; Gold, R. E.; Ho, G. C.; Korth, H.; Krimigis, S. M.; Livi, S. A.; McNutt, R. L., Jr.; Raines, J. M.; Sarantos, M.; Schriver, D.; Solomon, S. C.; Travnicek, P.

    2008-01-01

    MESSENGER'S 14 January 2008 encounter with Mercury has provided new observations of the magnetopause of this small magnetosphere, particularly concerning the effect of the direction of the interplanetary magnetic field (IMF) on the structure and dynamics of this boundary. The IMF was northward immediately prior to and following the passage of the MESSENGER spacecraft through Mercury's magnetosphere. However, several-minute episodes of southward IMF were observed in the magnetosheath during the inbound portion of the encounter. Evidence for reconnection at the dayside magnetopause in the form of well-developed flux transfer events (FTEs) was observed in the magnetosheath following some of these southward-B, intervals. The inbound magnetopause crossing seen in the magnetic field measurements is consistent with a transition from the magnetosheath into the plasma sheet. Immediately following MESSENGER'S entry into the magnetosphere, rotational perturbations in the magnetic field similar to those seen at the Earth in association with large-scale plasma sheet vortices driven by Kelvin-Helmholtz waves along the magnetotail boundary at the Earth were observed. The outbound magnetopause occurred during northward IMF B(sub z) and had the characteristics of a tangential discontinuity. These new observations by MESSENGER may be combined and compared with the magnetopause measurements collected by Mariner 10 to derive new understanding of the response of Mercury's magnetopause to IMF direction and its effect on the rate of solar wind energy and mass input to this small magnetosphere.

  10. First Laser Altimeter Measurements of Mercury from the MESSENGER Flyby

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Neumann, Gregory A.; Cavanaugh, John F.; McGarry, Jan F.; Smith, David E.; Zuber, Maria T.

    2008-01-01

    The Mercury Laser Altimeter performed the first laser ranging measurements to Mercury during the Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) flyby in January 2008. The instrument successfully ranged to 600 km at an off-nadir angle >60 and to >1600 km in the nadir direction.

  11. Surviving Rescue: A Feminist Reading of Scott O'Dell's "Island of the Blue Dolphins"

    ERIC Educational Resources Information Center

    Baecker, Diann L.

    2007-01-01

    Scott O'Dell's "Island of the Blue Dolphins" tells the archetypal story of the young, virgin, orphan girl who is vulnerable to either debauchery or rescue. That such a girl must succumb to either one or the other is a necessary element of the archetype. In O'Dell's work--one intended, after all, for children--the heroine is rescued by a…

  12. Surviving Rescue: A Feminist Reading of Scott O'Dell's "Island of the Blue Dolphins"

    ERIC Educational Resources Information Center

    Baecker, Diann L.

    2007-01-01

    Scott O'Dell's "Island of the Blue Dolphins" tells the archetypal story of the young, virgin, orphan girl who is vulnerable to either debauchery or rescue. That such a girl must succumb to either one or the other is a necessary element of the archetype. In O'Dell's work--one intended, after all, for children--the heroine is rescued by a…

  13. 29 CFR 520.400 - Who are messengers, learners, and apprentices?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Who are messengers, learners, and apprentices? 520.400... LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.400...

  14. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Learners, apprentices, messengers, students, or handicapped... the Act; Other Special Requirements § 516.30 Learners, apprentices, messengers, students, or... to persons employed as learners, apprentices, messengers or full-time students employed outside...

  15. 29 CFR 520.400 - Who are messengers, learners, and apprentices?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Who are messengers, learners, and apprentices? 520.400... LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.400...

  16. 29 CFR 520.400 - Who are messengers, learners, and apprentices?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Who are messengers, learners, and apprentices? 520.400... LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.400...

  17. 29 CFR 520.400 - Who are messengers, learners, and apprentices?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Who are messengers, learners, and apprentices? 520.400... LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.400...

  18. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Learners, apprentices, messengers, students, or handicapped... the Act; Other Special Requirements § 516.30 Learners, apprentices, messengers, students, or... to persons employed as learners, apprentices, messengers or full-time students employed outside...

  19. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Learners, apprentices, messengers, students, or handicapped... the Act; Other Special Requirements § 516.30 Learners, apprentices, messengers, students, or... to persons employed as learners, apprentices, messengers or full-time students employed outside...

  20. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Learners, apprentices, messengers, students, or handicapped... the Act; Other Special Requirements § 516.30 Learners, apprentices, messengers, students, or... to persons employed as learners, apprentices, messengers or full-time students employed outside...

  1. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Learners, apprentices, messengers, students, or handicapped... the Act; Other Special Requirements § 516.30 Learners, apprentices, messengers, students, or... to persons employed as learners, apprentices, messengers or full-time students employed outside...

  2. 29 CFR 520.400 - Who are messengers, learners, and apprentices?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Who are messengers, learners, and apprentices? 520.400... LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.400...

  3. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Use of grounded messenger wires; ungrounded... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires...

  4. 30 CFR 75.705-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Use of grounded messenger wires; ungrounded....705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such systems...

  5. 30 CFR 75.705-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Use of grounded messenger wires; ungrounded....705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such...

  6. 30 CFR 75.705-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Use of grounded messenger wires; ungrounded....705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such...

  7. 30 CFR 75.705-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Use of grounded messenger wires; ungrounded....705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such...

  8. 30 CFR 75.705-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Use of grounded messenger wires; ungrounded....705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such...

  9. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Use of grounded messenger wires; ungrounded... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger...

  10. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Use of grounded messenger wires; ungrounded... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger...

  11. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Use of grounded messenger wires; ungrounded... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger...

  12. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Use of grounded messenger wires; ungrounded... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger...

  13. MESSENGER observations of Mercury's bow shock and magnetopause

    NASA Astrophysics Data System (ADS)

    Slavin, J. A.; Acuña, M. H.; Anderson, B. J.; Benna, M.; Gloeckler, G.; Krimigis, S. M.; Raines, J. M.; Schriver, D.; Trávníček, P.; Zurbuchen, T. H.

    2008-09-01

    Abstract The MESSENGER spacecraft made the first of three flybys of Mercury on January 14, 2008 (1). New observations of solar wind interaction with Mercury were made with MESSENGER's Magnetometer (MAG) (2,3) and Energetic Particle and Plasma Spectrometer (EPPS) - composed of the Energetic Particle Spectrometer (EPS) and Fast Imaging Plasma Spectrometer (FIPS) (3,4). These MESSENGER observations show that Mercury's magnetosphere has a large-scale structure that is distinctly Earth-like, but it is immersed in a comet-like cloud of planetary ions [5]. Fig. 1 provides a schematic view of the coupled solar wind - magnetosphere - neutral atmosphere - solid planet system at Mercury. Here we present new models of bow shock and magnetopause shape and location that incorporate both the MESSENGER and earlier Mariner 10 measurements of these boundaries. A fast magnetosonic Mach number for the solar wind at Mercury's distance from the Sun of ~ 3 is derived from the shape of the bow shock. This value is consistent with earlier observations at these distances from the Sun by the Helios mission. The shape of Mercury's magnetopause and the thickness of the magnetosheath are found to be similar to that of the Earth, suggesting that the solar wind interaction is dominated by its dipolar magnetic field. MESSENGER measurements near the magnetopause do, however, indicate that internal plasma pressure does contribute to the pressure balance across this boundary. MAG and FIPS measurements are used to estimate the ratio of plasma thermal pressure to magnetic pressure at the dusk flank of the plasma sheet and dawn terminator regions, under the assumption that pressure is balanced across the inbound and outbound magnetopause crossings. To investigate the possible origins of the plasma ions in these regions, we utilize a combination of FIPS measurements and the results of 3-D hybrid [6] and magnetohydrodynamic simulations of the solar wind interaction with Mercury for the upstream conditions

  14. Mercury's Atmosphere and Magnetosphere: MESSENGER Third Flyby Observations

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Johnson, Catherine L.; Gloeckler, George; Killen, Rosemary M.; Krimigis, Stamatios M.; McClintock, William; McNutt, Ralph L., Jr.; hide

    2009-01-01

    MESSENGER's third flyby of Mercury en route to orbit insertion about the innermost planet took place on 29 September 2009. The earlier 14 January and 6 October 2008 encounters revealed that Mercury's magnetic field is highly dipolar and stable over the 35 years since its discovery by Mariner 10; that a structured, temporally variable exosphere extends to great altitudes on the dayside and forms a long tail in the anti-sunward direction; a cloud of planetary ions encompasses the magnetosphere from the dayside bow shock to the downstream magnetosheath and magnetotail; and that the magnetosphere undergoes extremely intense magnetic reconnect ion in response to variations in the interplanetary magnetic field. Here we report on new results derived from observations from MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS), Magnetometer (MAG), and Energetic Particle and Plasma Spectrometer (EPPS) taken during the third flyby.

  15. New discoveries from MESSENGER and insights into Mercury's exosphere

    NASA Astrophysics Data System (ADS)

    Vervack, R. J.; Killen, R. M.; McClintock, W. E.; Merkel, A. W.; Burger, M. H.; Cassidy, T. A.; Sarantos, M.

    2016-11-01

    For most of the orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, a regular search for weakly emitting or less abundant species in Mercury's exosphere resulted in nondetections. However, during the final Earth year of the mission, emission from multiple lines of manganese, aluminum, and ionized calcium was detected. These observations validate the detection of a single line of ionized calcium during the third MESSENGER Mercury flyby, provide definitive confirmation for weak aluminum detections in ground-based observations, and represent the discovery of manganese in Mercury's exosphere. These detections occurred over a limited range of predawn local times and Mercury true anomaly angles (0°-70°), and each has a distinct spatial distribution. Equally interesting is the absence of detectable emission from oxygen at limits well below the levels reported for Mariner 10.

  16. Mercury's Atmosphere and Magnetosphere: MESSENGER Third Flyby Observations

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Johnson, Catherine L.; Gloeckler, George; Killen, Rosemary M.; Krimigis, Stamatios M.; McClintock, William; McNutt, Ralph L., Jr.; Schriver, David; Solomon, Sean C.; Sprague, Ann L.; Vevack, Ronald J., Jr.; Zurbuchen, Thomas H.

    2009-01-01

    MESSENGER's third flyby of Mercury en route to orbit insertion about the innermost planet took place on 29 September 2009. The earlier 14 January and 6 October 2008 encounters revealed that Mercury's magnetic field is highly dipolar and stable over the 35 years since its discovery by Mariner 10; that a structured, temporally variable exosphere extends to great altitudes on the dayside and forms a long tail in the anti-sunward direction; a cloud of planetary ions encompasses the magnetosphere from the dayside bow shock to the downstream magnetosheath and magnetotail; and that the magnetosphere undergoes extremely intense magnetic reconnect ion in response to variations in the interplanetary magnetic field. Here we report on new results derived from observations from MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS), Magnetometer (MAG), and Energetic Particle and Plasma Spectrometer (EPPS) taken during the third flyby.

  17. Emerging trend in second messenger communication and myoendothelial feedback

    PubMed Central

    Tran, Cam Ha T.; Kurjiaka, David T.; Welsh, Donald G.

    2014-01-01

    Over the past decade, second messenger communication has emerged as one of the intriguing topics in the field of vasomotor control. Of particular interest has been the idea of second messenger flux from smooth muscle to endothelium initiating a feedback response that attenuates constriction. Mechanistic details of the precise signaling cascade have until recently remained elusive. In this perspective, we introduce readers to how myoendothelial gap junctions could enable sufficient inositol trisphosphate flux to initiate endothelial Ca2+ events that activate Ca2+ sensitive K+ channels. The resulting hyperpolarizing current would in turn spread back through the same myoendothelial gap junctions to moderate smooth muscle depolarization and constriction. In discussing this defined feedback mechanism, this brief manuscript will stress the importance of microdomains and of discrete cellular signaling. PMID:25071588

  18. Brain clock driven by neuropeptides and second messengers.

    PubMed

    Miro-Bueno, Jesus; Sosík, Petr

    2014-09-01

    The master circadian pacemaker in mammals is localized in a small portion of the brain called the suprachiasmatic nucleus (SCN). It is unclear how the SCN produces circadian rhythms. A common interpretation is that the SCN produces oscillations through the coupling of genetic oscillators in the neurons. The coupling is effected by a network of neuropeptides and second messengers. This network is crucial for the correct function of the SCN. However, models that study a possible oscillatory behavior of the network itself have received little attention. Here we propose and analyze a model to examine this oscillatory potential. We show that an intercellular oscillator emerges in the SCN as a result of the neuropeptide and second messenger dynamics. We find that this intercellular clock can produce circadian rhythms by itself with and without genetic clocks. We also found that the model is robust to perturbation of parameters and can be entrained by light-dark cycles.

  19. Brain clock driven by neuropeptides and second messengers

    NASA Astrophysics Data System (ADS)

    Miro-Bueno, Jesus; Sosík, Petr

    2014-09-01

    The master circadian pacemaker in mammals is localized in a small portion of the brain called the suprachiasmatic nucleus (SCN). It is unclear how the SCN produces circadian rhythms. A common interpretation is that the SCN produces oscillations through the coupling of genetic oscillators in the neurons. The coupling is effected by a network of neuropeptides and second messengers. This network is crucial for the correct function of the SCN. However, models that study a possible oscillatory behavior of the network itself have received little attention. Here we propose and analyze a model to examine this oscillatory potential. We show that an intercellular oscillator emerges in the SCN as a result of the neuropeptide and second messenger dynamics. We find that this intercellular clock can produce circadian rhythms by itself with and without genetic clocks. We also found that the model is robust to perturbation of parameters and can be entrained by light-dark cycles.

  20. MESSENGER Observations of Large Flux Transfer Events at Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Lepping, Ronald P.; Wu, Chin-Chun; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; McClintock, William E.; McNutt, Ralph L., Jr.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (M1 and M2). For M1 the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward IMF turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed approx. 32 s later by a 7 s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to determine FTE dimensions and flux content. The largest FTE observed by MESSENGER had a diameter of approx. 1 R(sub M) (where R(sub M) is Mercury s radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10 - 20 percent and contributed up to approx. 30 kV to the cross-magnetospheric electric potential.

  1. MESSENGER Observations of Large Flux Transfer Events at Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Lepping, Ronald P.; Wu, Chin-Chun; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; McClintock, William E.; McNutt, Ralph L., Jr.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (MI and M2). For MI the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward 1M F turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed approx.32 s later by a 7-s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to detem11ne PTE dimensions and flux content The largest FTE observed by MESSENGER had a diameter of approx. 1 R(sub M) (where R(sub M) is Mercury's radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10 - 20 percent and contributed up to approx.30 kV to the cross-magnetospheric electric potential.

  2. Chemical and structural effects of base modifications in messenger RNA

    NASA Astrophysics Data System (ADS)

    Harcourt, Emily M.; Kietrys, Anna M.; Kool, Eric T.

    2017-01-01

    A growing number of nucleobase modifications in messenger RNA have been revealed through advances in detection and RNA sequencing. Although some of the biochemical pathways that involve modified bases have been identified, research into the world of RNA modification -- the epitranscriptome -- is still in an early phase. A variety of chemical tools are being used to characterize base modifications, and the structural effects of known base modifications on RNA pairing, thermodynamics and folding are being determined in relation to their putative biological roles.

  3. MESSENGER Observations of Asymmetries at Mercury's Magnetotail Current Sheet

    NASA Astrophysics Data System (ADS)

    Poh, Gangkai; Slavin, James; Jia, Xianzhe; Raines, Jim; Sun, Wei-Jie; Genestreti, Kevin; Smith, Andy; Gershman, Daniel; Anderson, Brian

    2016-04-01

    Dawn-dusk asymmetries in the Earth's magnetotail current sheet have been observed and remain an active area of research. With an internal magnetic dipole field structure similar to Earth's, similar dawn-dusk asymmetries might be expected in Mercury's magnetotail current sheet. However, no observation of dawn-dusk asymmetries has been reported in the structure of Mercury's magnetotail. Using 4 years of MESSENGER's magnetic field and plasma data, we analyzed 319 current sheet crossings. From the polarity of Bz in the cross-tail current sheet, we determined that MESSENGER is on closed field lines about 90% of the time. During the other 10% MESSENGER observed negative Bz indicating that it was tailward of the Near Mercury Neutral Line (NMNL). The Bz magnetic field is also observed to be higher at the dawnside than the duskside of the magnetotail current sheet by approximately a factor of three. Further the asymmetry decreases with increasing downstream distance. A reduction (enhancement) in Bz should correspond to a more (less) stretched and thinned (thickened) current sheet. Analysis of current sheet thickness based upon MESSENGER's observations confirms this behavior with mean current sheet thickness and Bz intensity having dawn-dusk asymmetries with the same sense. Plasma β in the current sheet also exhibits a dawn-dusk asymmetry opposite to that of Bz. This is consistent with expectations based on MHD stress balance. Earlier studies had shown a dawn-dusk asymmetry in the heavy ion in Mercury's magnetotail. We suggest that this enhancement of heavy ions in the duskside current sheet, due to centrifugal acceleration of ions from the cusp and gradient-curvature drift from the NMNL, may provide a partial explanation of the dawn-dusk current sheet asymmetries found in this study.

  4. Mercury's exosphere: observations during MESSENGER's First Mercury flyby.

    PubMed

    McClintock, William E; Bradley, E Todd; Vervack, Ronald J; Killen, Rosemary M; Sprague, Ann L; Izenberg, Noam R; Solomon, Sean C

    2008-07-04

    During MESSENGER's first Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer measured Mercury's exospheric emissions, including those from the antisunward sodium tail, calcium and sodium close to the planet, and hydrogen at high altitudes on the dayside. Spatial variations indicate that multiple source and loss processes generate and maintain the exosphere. Energetic processes connected to the solar wind and magnetospheric interaction with the planet likely played an important role in determining the distributions of exospheric species during the flyby.

  5. Tomographic Reconstruction of Mercury's Exosphere from MESSENGER Flyby Data

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; McClintock, William E.; Slavin, James A.; Solomon, Sean C.; Vervack, Ronald J., Jr.

    2011-01-01

    The exosphere of Mercury is among the best-studied examples of a common type of atmosphere, a surface-bounded exosphere. Mercury's exosphere was probed in 2008-2009 with Ultraviolet and Visible Spectrometer (UVVS) measurements obtained during three planetary flybys by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft [1-3]. The measurements detailed the distribution of two previously known metallic constituents of Mercury's exosphere, Na and Ca, and indicated the presence in the gas phase of yet another metallic species, Mg. Such measurements can answer fundamental scientific questions regarding the relative importance of possible source and loss processes for exospheric species ejected from a surface boundary [4]. The trajectory of MESSENGER during the last of its three flybys provided the best spatial coverage prior to orbit insertion. The measurements by MESSENGER of Na, Ca, and Mg during the third flyby have been analyzed with a novel tomographic method. This approach maximizes the amount of information that can be extracted from line-of-sight measurements because it yields three-dimensional distributions of neutrals consistent with the data.

  6. Mercury's Sodium Exosphere: Observations during the MESSENGER Orbital Phase

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; Burger, Matthew H.; Merkel, Aimee W.; Sarantos, Menelaos; Sprague, Ann L.; McClintock, William E.; Benna, Mehdi; Solomon, Sean C.

    2012-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered into orbit about Mercury on March 18,2011. We now have approximately five Mercury years of data from orbit. Prior to the MESSENGER mission, Mercury's surface-bounded exosphere was known to contain H, He, Na. K, and Ca. The Ultraviolet and Visible Spectrometer (UVVS) began routine orbital observations of both the dayside and nightside exosphere on March 29. 2011, measuring altitude profiles for all previously detected neutral species except for He and K. We focus here on what we have learned about the sodium exosphere: its spatial, seasonal, and sporadic variation. Observations to date permit delineation of the relative roles of photon-stimulated desorption (PSD) and impact vaporization (IV) from seasonal and spatial effects, as well as of the roles of ions both as sputtering agents and in their possible role to enhance the efficiency of PSD. Correlations of Mercury's neutral sodium exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide insight into the roles of ions and electrons. Models incorporating MAG observations provide a basis for identifying the location and area of the surface exposed to solar wind plasma, and EPPS observations reveal episodic populations of energetic electrons in the magnetosphere and the presence of planetary He(+), 0(+), and Na(+),

  7. Control of dihydrofolate reductase messenger ribonucleic acid production

    SciTech Connect

    Leys, E.J.; Kellems, R.E.

    1981-11-01

    The authors used methotrexate-resistant mouse cells in which dihydrofolate reductase levels are approximately 500 times normal to study the effect of growth stimulation on dihydrofolate reductase gene expression. As a result of growth stimulation, the relative rate of dihydrofolate reductase protein synthesis increased threefold, reaching a maximum between 25 and 30 h after stimulation. The relative rate of dihydrofolate reductase messenger ribonucleic acid production (i.e., the appearance of dihydrofolate reductase messenger ribonucleic acid in the cytoplasm) increased threefold after growth stimulation and was accompanied by a corresponding increase in the relative steady-state level of dihydrofolate reductase ribonucleic acid in the nucleus. However, the increase in the nuclear level of dihydrofolate reductase ribonucleic acid was not accompanied by a significant increase in the relative rate of transcription of the dihydrofolate reductase genes. These data indicated that the relative rate of appearance of dihydrofolate reductase messenger ribonucleic acid in the cytoplasm depends on the relative stability of the dihydrofolate reductase ribonucleic acid sequences in the nucleus and is not dependent on the relative rate of transcription of the dihydrofolate reductase genes.

  8. The Morphology of Craters on Mercury: Results from MESSENGER Flybys

    NASA Technical Reports Server (NTRS)

    Barnouin, Oliver S.; Zuber, Maria T.; Smith, David E.; Neumann, Gregory A.; Herrick, Robert R.; Chappelow, John E.; Murchie, Scott L.; Prockter, Louise M.

    2012-01-01

    Topographic data measured from the Mercury Laser Altimeter (MLA) and the Mercury Dual Imaging System (MDIS) aboard the MESSENGER spacecraft were used for investigations of the relationship between depth and diameter for impact craters on Mercury. Results using data from the MESSENGER flybys of the innermost planet indicate that most of the craters measured with MLA are shallower than those previously measured by using Mariner 10 images. MDIS images of these same MLA-measured craters show that they have been modified. The use of shadow measurement techniques, which were found to be accurate relative to the MLA results, indicate that both small bowl-shaped and large complex craters that are fresh possess depth-to-diameter ratios that are in good agreement with those measured from Mariner 10 images. The preliminary data also show that the depths of modified craters are shallower relative to fresh ones, and might provide quantitative estimates of crater in-filling by subsequent volcanic or impact processes. The diameter that defines the transition from simple to complex craters on Mercury based on MESSENGER data is consistent with that reported from Mariner 10 data.

  9. Mercury's Sodium Exosphere: Observations During the MESSENGER Orbital Phase

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Cassidy, T.; Vervack, R. J.; Burger, M. H.; Merkel, A. W.; Sarantos, M.; Sprague, A. L.; McClintock, W. E.; Benna, M.; Solomon, S. C.

    2012-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered into orbit about Mercury on March 18, 2011. We now have approximately five Mercury years of data from orbit. Prior to the MESSENGER mission, Mercury's surface-bounded exosphere was known to contain H, He, Na, K, and Ca. The Ultraviolet and Visible Spectrometer (UVVS) began routine orbital observations of both the dayside and nightside exosphere on March 29, 2011, measuring altitude profiles for all previously detected neutral species except for He and K. We focus here on what we have learned about the sodium exosphere: its spatial, seasonal, and sporadic variation. Observations to date permit delineation of the relative roles of photon-stimulated desorption (PSD) and impact vaporization (IV) from seasonal and spatial effects, as well as of the roles of ions both as sputtering agents and in their possible role to enhance the efficiency of PSD. Correlations of Mercury's neutral sodium exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide insight into the roles of ions and electrons. Models incorporating MAG observations provide a basis for identifying the location and area of the surface exposed to solar wind plasma, and EPPS observations reveal episodic populations of energetic electrons in the magnetosphere and the presence of planetary He+, O+, and Na+.

  10. Ubiquitous learning model using interactive internet messenger group (IIMG) to improve engagement and behavior for smart campus

    NASA Astrophysics Data System (ADS)

    Umam, K.; Mardi, S. N. S.; Hariadi, M.

    2017-01-01

    The recent popularity of internet messenger based smartphone technologies has motivated some university lecturers to use them for educational activities. These technologies have enormous potential to enhance the teaching and ubiquitous learning experience for smart campus development. However, the design ubiquitous learning model using interactive internet messenger group (IIMG) and empirical evidence that would favor a broad application of mobile and ubiquitous learning in smart campus settings to improve engagement and behavior is still limited. In addition, the expectation that mobile learning could improve engagement and behavior on smart campus cannot be confirmed because the majority of the reviewed studies followed instructions paradigms. This article aims to present ubiquitous learning model design and showing learners’ experiences in improved engagement and behavior using IIMG for learner-learner and learner-lecturer interactions. The method applied in this paper includes design process and quantitative analysis techniques, with the purpose of identifying scenarios of ubiquitous learning and realize the impressions of learners and lecturers about engagement and behavior aspect, and its contribution to learning.

  11. 29 CFR 520.402 - How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false How do I obtain authority to employ messengers, learners... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.402 How do I obtain authority to employ messengers, learners,...

  12. 29 CFR 520.402 - How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false How do I obtain authority to employ messengers, learners... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.402 How do I obtain authority to employ messengers, learners,...

  13. 29 CFR 520.402 - How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false How do I obtain authority to employ messengers, learners... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.402 How do I obtain authority to employ messengers, learners,...

  14. 29 CFR 520.402 - How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false How do I obtain authority to employ messengers, learners... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.402 How do I obtain authority to employ messengers, learners,...

  15. 29 CFR 520.402 - How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false How do I obtain authority to employ messengers, learners... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.402 How do I obtain authority to employ messengers, learners,...

  16. The X-Ray Spectrometer for Mercury MESSENGER

    NASA Technical Reports Server (NTRS)

    Starr, R. D.; Ho, G. C.; Schlemm, C.; Gold, R. E.; Goldsten, J. O.; Boynton, W. V.; Trombka, J. I.

    2001-01-01

    Mercury is the closest planet to the Sun and because it is so close, it is difficult to study from Earth-based observatories. Its proximity to the Sun has also limited the number of spacecraft to visit this tiny planet to just one, Mariner 10, which flew by Mercury twice in 1974 and once in 1975. Mariner 10 provided a wealth of new information about Mercury, yet much still remains unknown about Mercury's geologic history and the processes that led to its formation. The origin of Mercury's metal-rich composition is just one area of investigation awaiting more and improved data to sort between competing hypotheses. Mercury plays an important role in comparative planetology, and many of the processes that were important during its formation are relevant to the Earth's early history. MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) is a Discovery mission that has been designed to fly by and orbit Mercury. It will launch in March 2004, flyby Mercury in 2007 and 2008 and enter an elliptical orbit in April 2009. During the one-year orbital phase, a suite of instruments on board the MESSENGER spacecraft will study the exosphere, magnetosphere, surface, and interior of Mercury. One of these instruments will be an X-Ray Spectrometer (XRS) that will measure surface elemental abundances. Remote X-ray spectroscopy has been accomplished before on the Apollo 15 and 16 missions, and more recently on NEAR Shoemaker. The MESSENGER XRS will measure characteristic X-ray emissions induced in the surface of Mercury by the incident solar flux. The Ka lines for the elements Mg, Al, Si, S, Ca, Ti, and Fe will be detected with spatial resolution on the order of 40 km when counting statistics are not a limiting factor. These measurements can be used to obtain quantitative information on elemental composition.

  17. MESSENGER Observations of Magnetic Reconnection in Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin. James A.

    2009-01-01

    During MESSENGER'S second flyby of Mercury on October 6,2008, very intense reconnection was observed between the planet's magnetic field and a steady southward interplanetary magnetic field (IMF). The dawn magnetopause was threaded by a strong magnetic field normal to its surface, approx.14 nT, that implies a rate of reconnection approx.10 times the typical rate at Earth and a cross-magnetospheric electric potential drop of approx.30 kV. The highest magnetic field observed during this second flyby, approx.160 nT, was found at the core of a large dayside flux transfer event (FTE). This FTE is estimated to contain magnetic flux equal to approx.5% that of Mercury's magnetic tail or approximately one order of magnitude higher fraction of the tail flux than is typically found for FTEs at Earth. Plasmoid and traveling compression region (TCR) signatures were observed throughout MESSENGER'S traversal of Mercury's magnetotail with a repetition rate comparable to the Dungey cycle time of approx.2 min. The TCR signatures changed from south-north, indicating tailward motion, to north-south, indicating sunward motion, at a distance approx.2.6 RM (where RM is Mercury's radius) behind the terminator indicating that the near-Mercury magnetotail neutral line was crossed at that point. Overall, these new MESSENGER observations suggest that magnetic reconnection at the dayside magnetopause is very intense relative to what is found at Earth and other planets, while reconnection in Mercury's tail is similar to that in other planetary magnetospheres, but with a very short Dungey cycle time.

  18. Mapping the Topography of Mercury with MESSENGER Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Smith, David E..; Zubor, Maria T.

    2012-01-01

    The Mercury Laser Altimeter onboard MESSENGER involves unique design elements that deal with the challenges of being in orbit around Mercury. The Mercury Laser Altimeter (MLA) is one of seven instruments on NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. MESSENGER was launched on 3 August 2004, and entered into orbit about Mercury on 18 March 2011 after a journey through the inner solar system. This involved six planetary flybys, including three of Mercury. MLA is designed to map the topography and landforms of Mercury's surface. It also measures the planet's forced libration (motion about the spin axis), which helps constrain the state of the core. The first science measurements from orbit taken with MLA were made on 29 March 2011 and continue to date. MLA had accumulated about 8.3 million laser ranging measurements to Mercury's surface, as of 31 July 2012, i.e., over six Mercury years (528 Earth days). Although MLA is the third planetary lidar built at the NASA Goddard Space Flight Center (GSFC), MLA must endure a much harsher thermal environment near Mercury than the previous instruments on Mars and Earth satellites. The design of MLA was derived in part from that of the Mars Orbiter Laser Altimeter on Mars Global Surveyor. However, MLA must range over greater distances and often in off-nadir directions from a highly eccentric orbit. In MLA we use a single-mode diode-pumped Nd:YAG (neodymium-doped yttrium aluminum garnet) laser that is highly collimated to maintain a small footprint on the planet. The receiver has both a narrow field of view and a narrow spectral bandwidth to minimize the amount of background light detected from the sunlit hemisphere of Mercury. We achieve the highest possible receiver sensitivity by employing the minimum receiver detection threshold.

  19. Constraints on Mercury's surface composition from MESSENGER neutron spectrometer data

    NASA Astrophysics Data System (ADS)

    Riner, M. A.; Lucey, P. G.; McCubbin, F. M.; Taylor, G. J.

    2011-08-01

    The composition of Mercury's surface is poorly known, but the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission has provided a wealth of new data from three flybys. In particular, MESSENGER Neutron Spectrometer (NS) observations reveal a surface enriched in neutron absorbing elements, consistent with interpretations of color and albedo observations suggesting a surface composition enriched in Fe-Mg-Ti oxides. In this study, we have computed the neutron absorption cross sections for all of the available proposed surface compositions of Mercury and evaluated the plausibility of each surface composition based on the neutron absorption cross section observed by MESSENGER. For identified plausible compositions, the implications for the thermal and magmatic evolution of Mercury are discussed. The measured macroscopic neutron absorption cross section of Mercury is inconsistent with a crust formed from partial melting of plausible bulk mantle compositions, flotation in a magma ocean or adiabatic melting of upwelling cumulates during magma ocean overturn. However, the observed neutron absorption is consistent with model compositions of late-stage magma-ocean cumulates and some proposed compositions from spectral modeling and equilibrium modeling. This suggests that the enrichment of neutron absorbing elements may be indicative of the processes that acted to form Mercury's crust. The enrichment in neutron absorbing elements, in combination with spectral observations that constrain FeO in silicates (< 2 wt.%), offers strong evidence of a magma ocean on Mercury since global scale melting appears to be required to concentrate the major neutron absorbing elements while minimizing Fe in silicate minerals. We also find that iron plays a secondary role in the neutron absorption of plausible surface compositions and its variations within different Fe-Mg-Ti oxide solid solution series does not cause any overlap among the various oxide series in neutron

  20. Interplanetary Coronal Mass Ejections Observed by MESSENGER and Venus Express

    NASA Astrophysics Data System (ADS)

    Good, S. W.; Forsyth, R. J.

    2016-01-01

    Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER and Venus Express spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MESSENGER data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed Venus Express data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left- and right-handed ropes were observed in almost equal numbers. In addition, data from MESSENGER, Venus Express, STEREO-A, STEREO-B and ACE were examined for multipoint signatures of the catalogued ICMEs. For spacecraft separations below 15° in heliocentric longitude, the second spacecraft observed the ICME flux rope in 82 % of cases; this percentage dropped to 49 % for separations between 15 and 30°, to 18 % for separations between 30 and 45°, and to 12 % for separations between 45 and 60°. As the spacecraft separation increased, it became increasingly likely that only the sheath and not the flux rope of the ICME was observed, in agreement with the notion that ICME flux ropes are smaller in longitudinal extent than the shocks or discontinuities that they often drive. Furthermore, this study has identified 23 ICMEs observed by pairs of spacecraft close to radial alignment. A detailed analysis of these events could lead to a better understanding of how ICMEs evolve during propagation.

  1. MESSENGER Observations of Cusp Plasma Filaments at Mercury

    NASA Astrophysics Data System (ADS)

    Poh, G. K.; Slavin, J. A.; DiBraccio, G. A.; Jia, X.; Raines, J. M.; Imber, S. M.; Anderson, B. J.; Korth, H.; Gershman, D. J.; Zurbuchen, T.; McNutt, R. L., Jr.; Solomon, S. C.

    2014-12-01

    At Mercury, MESSENGER has documented ~1-2-s-long reductions in the dayside magnetospheric magnetic field with amplitudes up to 90% of the ambient intensity. These field reductions which we have termed cusp filaments are observed from just poleward of the magnetospheric cusp to mid-latitudes. During these events, MESSENGER's Fast Imaging Plasma Spectrometer (FIPS) measured H+ ions with magnetosheath-like energies. Minimum variance analysis of the Magnetometer (MAG) data indicates that the filaments are simple two dimensional flux tubes filled with magnetosheath plasma that has a diamagnetic effect on the local background field. Here we analyze 139 filaments identified in 3 years of MESSENGER magnetic field and plasma data to determine the physical properties of these structures. Our results indicate that cusp filaments are common phenomena for all solar wind conditions. They occur over a range of magnetic latitudes from ~50 to 80oN, with durations of ~0.1-2.5s and magnetic field decreases of ~50-300 nT. If the filaments are associated with flux transfer events (FTEs) and move over the spacecraft at speeds comparable to the flank magnetosheath flow speed of 300 km/s, then these filaments have dimensions of ~30-750 km, which is larger than the gyro-radius of a 1 keV H+ ion, i.e., ~ 23 km. Correlation analyses show no obvious dependence of the duration or magnitude of the diamagnetic decrease on magnetic latitude. Overall, the MAG and FIPS observations analyzed here appear consistent with an origin for cusp plasma filaments by the inflow of magnetosheath plasma associated with the localized magnetopause reconnection process that produces FTEs. Further analysis will be required to confirm this hypothesis.

  2. An Unintentional System of Gaps: A Phenomenological Reading of Scott O'Dell's "Island of the Blue Dolphins."

    ERIC Educational Resources Information Center

    Tarr, C. Anita

    1997-01-01

    Argues that, in "Island of the Blue Dolphins," Scott O'Dell offers a skeleton main character (Karana). Contends that O'Dell has sketched Karana as a stereotype and that readers complete her characterization, filling out the skeleton by perpetuating the stereotypes. Points out this trading of stereotype for true character development in…

  3. An Unintentional System of Gaps: A Phenomenological Reading of Scott O'Dell's "Island of the Blue Dolphins."

    ERIC Educational Resources Information Center

    Tarr, C. Anita

    1997-01-01

    Argues that, in "Island of the Blue Dolphins," Scott O'Dell offers a skeleton main character (Karana). Contends that O'Dell has sketched Karana as a stereotype and that readers complete her characterization, filling out the skeleton by perpetuating the stereotypes. Points out this trading of stereotype for true character development in…

  4. A Test of General Relativity with MESSENGER Mission Data

    NASA Astrophysics Data System (ADS)

    Genova, A.; Mazarico, E.; Goossens, S. J.; Lemoine, F. G.; Neumann, G. A.; Nicholas, J. B.; Rowlands, D. D.; Smith, D. E.; Zuber, M. T.; Solomon, S. C.

    2016-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft initiated collection of scientific data from the innermost planet during its first flyby of Mercury in January 2008. After two additional Mercury flybys, MESSENGER was inserted into orbit around Mercury on 18 March 2011 and operated for more than four Earth years through 30 April 2015. Data acquired during the flyby and orbital phases have provided crucial information on the formation and evolution of Mercury. The Mercury Laser Altimeter (MLA) and the radio science system, for example, obtained geodetic observations of the topography, gravity field, orientation, and tides of Mercury, which helped constrain its surface and deep interior structure. X-band radio tracking data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, as well as refinement of the planet's obliquity and estimation of the tidal Love number k2. These geophysical parameters are derived from the range-rate observables that measure precisely the motion of the spacecraft in orbit around the planet. However, the DSN stations acquired two other kinds of radio tracking data, range and delta-differential one-way ranging, which also provided precise measurements of Mercury's ephemeris. The proximity of Mercury's orbit to the Sun leads to a significant perihelion precession, which was used by Einstein as confirmation of general relativity (GR) because of its inconsistency with the effects predicted from classical Newtonian theory. MESSENGER data allow the estimation of the GR parameterized post-Newtonian (PPN) coefficients γ and β. Furthermore, determination of Mercury's orbit also allows estimation of the gravitational parameter (GM) and the flattening (J2) of the Sun. We modified our orbit determination software, NASA GSFC's GEODYN II, to enable simultaneous orbit integration of both MESSENGER and the planet Mercury. The

  5. Mapping the messenger RNA within the elongating ribosome

    NASA Astrophysics Data System (ADS)

    Jünemann, R.; Wadzack, J.; Burkhardt, N.; Schmitt, M.; Zhao, J.; Stuhrmann, H. B.; Nierhaus, K. H.

    1997-02-01

    The method of proton-spin contrast-variation was applied for determining the position of the messenger RNA within the elongating ribosome. Using an artificial mRNA fragment the mass center of the mRNA sequence covered by the ribosome could be localized for the pre- and the post-translocational elongation states. The mass center moves about 12 ± 5 Å upon translocation. The radius of gyration was 12 ± e Å. The data give an independent contribution for refining a structural model including the RNA ligands of the elongating ribosome.

  6. Chemical and structural effects of base modifications in messenger RNA

    PubMed Central

    Harcourt, Emily M.; Kietrys, Anna M.; Kool, Eric T.

    2017-01-01

    A growing number of nucleobase modifications in messenger RNA have been revealed through advances in detection and RNA sequencing. Although some of the biochemical pathways that involve modified bases have been identified, research into the world of RNA modification — the epitranscriptome — is still in an early phase. A variety of chemical tools are being used to characterize base modifications, and the structural effects of known base modifications on RNA pairing, thermodynamics and folding are being determined in relation to their putative biological roles. PMID:28102265

  7. Mercury's Plasma Mantle - a survey of MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Jasinski, Jamie Matthew; Slavin, James A.; Raines, Jim; DiBraccio, Gina

    2016-10-01

    The plasma mantle is a region of solar wind plasma entry into the nightside high-latitude magnetosphere. We present a survey of plasma mantles identified in particle and magnetic field measurements from four years of MESSENGER spacecraft observations of Mercury's magnetosphere. The two common observational signatures of this region are ion energy latitude dispersions as well as diamagnetic depressions. From these observations we estimate the contribution of plasma from the solar wind via the mantle and infer magnitude and variability in the cross-magnetospheric electric fields present at Mercury's dynamic magnetosphere.

  8. Current status of GW experiment and multi-messenger astronomy

    NASA Astrophysics Data System (ADS)

    Rudenko, V. N.

    2016-06-01

    A limited review of the status of advanced gravitational wave interferometers is presented. In addition, a new opto-acoustical gravitational detector OGRAN in the deep underground of BNO INR RAS is described. The second part of the paper contains a short description of the "multi-messenger astronomy" approach in the context of the GW detection. Various scenarios of such strategy proposed by different authors are discussed. Special attention is paid to the "neutrino-gravity correlation" which looks more or less realistic in respect of supernova events in the Milky Way and near-by galaxies.

  9. Mercury's Complex Exosphere: Results from MESSENGER's Third Flyby

    NASA Technical Reports Server (NTRS)

    Vervack, Ronald J., Jr.; McClintock, William E.; Killen, Rosemary M.; Sprague, Ann L.; Anderson, Brian J.; Burger, Matthew H.; Bradley, E. Todd; Mouawad, Nelly; Solomon, Sean C.; Izenberg, Noam R.

    2010-01-01

    During MESSENGER's third flyby of Mercury, the Mercury Atmospheric and Surface Composition Spectrometer detected emission from ionized calcium concentrated 1 to 2 Mercury radii tailward of the planet. This measurement provides evidence for tailward magnetospheric convection of photoions produced inside the magnetosphere. Observations of neutral sodium, calcium, and magnesium above the planet's north and south poles reveal attitude distributions that are distinct for each species. A two-component sodium distribution and markedly different magnesium distributions above the two poles are direct indications that multiple processes control the distribution of even single species in Mercury's exosphere,

  10. Mercury's complex exosphere: results from MESSENGER's third flyby.

    PubMed

    Vervack, Ronald J; McClintock, William E; Killen, Rosemary M; Sprague, Ann L; Anderson, Brian J; Burger, Matthew H; Bradley, E Todd; Mouawad, Nelly; Solomon, Sean C; Izenberg, Noam R

    2010-08-06

    During MESSENGER's third flyby of Mercury, the Mercury Atmospheric and Surface Composition Spectrometer detected emission from ionized calcium concentrated 1 to 2 Mercury radii tailward of the planet. This measurement provides evidence for tailward magnetospheric convection of photoions produced inside the magnetosphere. Observations of neutral sodium, calcium, and magnesium above the planet's north and south poles reveal altitude distributions that are distinct for each species. A two-component sodium distribution and markedly different magnesium distributions above the two poles are direct indications that multiple processes control the distribution of even single species in Mercury's exosphere.

  11. Laser altimeter observations from MESSENGER's first Mercury flyby.

    PubMed

    Zuber, Maria T; Smith, David E; Solomon, Sean C; Phillips, Roger J; Peale, Stanton J; Head, James W; Hauck, Steven A; McNutt, Ralph L; Oberst, Jürgen; Neumann, Gregory A; Lemoine, Frank G; Sun, Xiaoli; Barnouin-Jha, Olivier; Harmon, John K

    2008-07-04

    A 3200-kilometers-long profile of Mercury by the Mercury Laser Altimeter on the MESSENGER spacecraft spans approximately 20% of the near-equatorial region of the planet. Topography along the profile is characterized by a 5.2-kilometer dynamic range and 930-meter root-mean-square roughness. At long wavelengths, topography slopes eastward by 0.02 degrees , implying a variation of equatorial shape that is at least partially compensated. Sampled craters on Mercury are shallower than their counterparts on the Moon, at least in part the result of Mercury's higher gravity. Crater floors vary in roughness and slope, implying complex modification over a range of length scales.

  12. Multi-messenger astronomy: gravitational waves, neutrinos, photons, and cosmic rays

    NASA Astrophysics Data System (ADS)

    Branchesi, Marica

    2016-05-01

    In the next decade, multi-messenger astronomy will probe the rich physics of transient phenomena in the sky, such as the mergers of neutron stars and/or black holes, gamma-ray bursts, and core-collapse supernovae. The first observations of gravitational waves from the inspiral and merger of a binary black-hole system by the advanced LIGO interferometers marked the onset of gravitational-wave astronomy. The advanced detectors, LIGO and Virgo, observing together with space and ground-based electromagnetic telescopes, and neutrinos and cosmic-ray detectors will offer the great opportunity to explore the Universe through all its messengers. The paper provides a review of the astrophysical sources expected to emit transient multi-messenger signals and the multi-messenger obervational startegies and analysis. Challenges and perspectives of the multi-messenger astronomy are presented highlighting gravitational waves as new messenger.

  13. Alterations in polyribosome and messenger ribonucleic acid metabolism and messenger ribonucleoprotein utilization in osmotically stressed plant seedlings

    SciTech Connect

    Mason, H.S.

    1986-01-01

    Polyribosome aggregation state in growing tissues of barley and wheat leaf of stems of pea and squash was studied in relation to seedling growth and water status of the growing tissue in plants at various levels of osmotic stress. It was found to be highly correlated with water potential and osmotic potential of the growing tissue and with leaf of stem elongation rate. Stress rapidly reduced polyribosome content and water status in growing tissues of barley leaves; changes were slow and slight in the non-growing leaf blade. Membrane-bound and free polyribosomes were equally sensitive to stress-induced disaggregation. Incorporation of /sup 32/PO/sub 4//sup 3 -/ into ribosomal RNA was rapidly inhibited by stress, but stability of poly(A)/sup +/RNA relative to ribosomal RNA was similar in stressed and unstressed tissues, with a half-life of about 12 hours. Stress also caused progressive loss of poly(A)/sup +/RNA from these tissues. Quantitation of poly(A) and in vitro messenger template activity in polysome gradient fractions showed a shift of activity from the polysomal region to the region of 20-60 S in stressed plants. Messenger RNA in the 20-60 S region coded for the same peptides as mRNA found in the polysomal fraction. Nonpolysomal and polysome-derived messenger ribonucleoprotein complexes (mRNP) were isolated, and characteristic proteins were found associated with either fraction. Polysomal mRNP from stressed or unstressed plants were translated with similar efficiency in a wheat germ cell-free system. It was concluded that no translational inhibitory activity was associated with nonpolysomal mRNP from barley prepared as described.

  14. Multi-messenger particle astrophysics with the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Vandenbroucke, Justin; Cherenkov Telescope Array Collaboration

    2017-01-01

    The Cherenkov Telescope Array (CTA) is a next-generation array of imaging atmospheric Cherenkov telescopes. Building on the success of H.E.S.S., MAGIC, and VERITAS, in an energy range complementary to that of the Fermi Large Area Telescope (LAT), CTA will investigate the particle physics of the cosmos through observations of gamma rays between tens of GeV and several hundred TeV. The observatory is especially well suited for follow-up of transient events detected in other wavelengths and messengers including neutrinos and gravitational waves. CTA will feature one array in each hemisphere for full sky coverage. The largest telescopes will have a 20 GeV energy threshold and will be able to quickly (in less than 50 seconds) slew to transient targets. The excellent effective area of CTA (thousands of times greater than that of the Fermi LAT at 20 GeV) will enable it to provide powerful and unique contributions to multi-messenger particle astrophysics.

  15. MESSENGER Observations of Reconnection and Its Effects on Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Imber, Suzanne M.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Nittler, Larry R.; Raines, Jim M.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Starr, Richard D.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's second and third flybys of Mercury on October 6, 2008 and September 29, 2009, respectively, southward interplanetary magnetic fields produced very intense reconnection signatures in the dayside and nightside magnetosphere and very different systemlevel responses. The IMF during the second flyby was continuously southward and the magnetosphere appeared very active with very large magnetic fields normal to the magnetopause and the generation of flux transfer events at the magnetopause and plasmoids in the tail current sheet every 30 s to 90 s. However, the strength and direction of the tail magnetic field was very stable. In contrast the third flyby experienced a variable IMF with it varying from north to south on timescales of minutes. Although the MESSENGER measurements were limited this time to the nightside magnetosphere, numerous examples of plasmoid release in the tail were detected, but they were not periodic. Rather, plasmoid release was highly correlated with the four large enhancements of the tail magnetic field (i.e. by factors > 2) with durations of approx. 2 - 3 min. The increased flaring of the magnetic field during these intervals indicates that the enhancements were caused by loading of the tail with magnetic flux transferred from the dayside magnetosphere. New analyses of the second and third flyby observations of reconnection and its system-level effects will be presented. The results will be examined in light of what is known about the response of the Earth's magnetosphere to variable versus steady southward IMF.

  16. Modeling MESSENGER Observations of Calcium in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Burger, Matthew Howard; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.; Merkel, Aimee W.; Sprague, Ann L.; Sarantos, Menelaos

    2012-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MESSENGER spacecraft has made the first high-spatial-resolution observations of exospheric calcium at Mercury. We use a Monte Carlo model of the exosphere to track the trajectories of calcium atoms ejected from the surface until they are photoionized, escape from the system, or stick to the surface. This model permits an exploration of exospheric source processes and interactions among neutral atoms, solar radiation, and the planetary surface. The MASCS data have suggested that a persistent, high-energy source of calcium that was enhanced in the dawn, equatorial region of Mercury was active during MESSENGER's three flybys of Mercury and during the first seven orbits for which MASCS obtained data. The total Ca source rate from the surface varied between 1.2x10(exp 23) and 2.6x10(exp 23) Ca atoms/s, if its temperature was 50,000 K. The origin of this high-energy, asymmetric source is unknown, although from this limited data set it does not appear to be consistent with micrometeoroid impact vaporization, ion sputtering, electron-stimulated desorption, or vaporization at dawn of material trapped on the cold nightside.

  17. MESSENGER observations of substorm activity in Mercury's near magnetotail

    NASA Astrophysics Data System (ADS)

    Sun, Wei-Jie; Slavin, James; Fu, Suiyan; Raines, Jim; Zong, Qiu-Gang; Yao, Zhonghua; Pu, Zuyin; Shi, Quanqi; Poh, Gangkai; Boardsen, Scott; Imber, Suzanne; Sundberg, Torbjörn; Anderson, Brian; Korth, Haje; Baker, Daniel

    2015-04-01

    MESSENGER magnetic field and plasma measurements taken during crossings of Mercury's magnetotail from 2011 to 2014 have been examined for evidence of substorm activity. A total of 32 events were found during which an Earth-like growth phase was followed by clear near-tail expansion phase signatures. During the growth phase, the lobe of the tail loads with magnetic flux while the plasma sheet thins due to the increased lobe magnetic pressure. MESSENGER is often initially in the plasma sheet and then moves into the lobe during the growth phases. The averaged time scale of the loading is around 1 min, consistent with previous observations of Mercury's Dungey cycle. The dipolarization front that marks the initiation of the substorm expansion phase is only a few seconds in duration. The spacecraft then abruptly enters the plasma sheet due to the plasma sheet expansion as reconnection-driven flow from the near-Mercury neutral line encounters the stronger magnetic fields closer to the planet. Substorm activity in the near tail of Mercury is quantitatively very similar to the Earth despite the very compressed time scale.

  18. Translation of globin messenger RNA by the mouse ovum

    PubMed Central

    Brinster, R. L.; Chen, H. Y.; Trumbauer, M. E.; Avarbock, M. R.

    2016-01-01

    It has been demonstrated that the Xenopus oocyte can translate rabbit haemoglobin messenger RNA (mRNA) following microinjection of the message into the cell1. The Xenopus oocyte has since been shown to be capable of translating a variety of messenger RNAs from different species2–4. This system has proved useful in understanding the mechanism of message translation and has also provided information about the translation capability of the Xenopus oocyte5,6. Several other cell types, including HeLa cells and fibroblasts, can also translate exogenous message injected into the cell7,8. However, there have been no reports of injection of mRNA into oocytes or fertilised one-cell ova of mammalian species. Nevertheless, the latter system could be of considerable use in studying the processing of exogenous messages in a mammalian system undergoing development, as well as providing insight into the way the early embryo processes injected messages and the protein products of such messages. We report here the results of injecting message into the fertilised one-cell mouse ovum and show that both mouse and rabbit globin mRNA are translated in this system. PMID:7352032

  19. Pseudo–Messenger RNA: Phantoms of the Transcriptome

    PubMed Central

    Frith, Martin C; Wilming, Laurens G; Forrest, Alistair; Kawaji, Hideya; Tan, Sin Lam; Wahlestedt, Claes; Bajic, Vladimir B; Kai, Chikatoshi; Kawai, Jun; Carninci, Piero; Hayashizaki, Yoshihide; Bailey, Timothy L; Huminiecki, Lukasz

    2006-01-01

    The mammalian transcriptome harbours shadowy entities that resist classification and analysis. In analogy with pseudogenes, we define pseudo–messenger RNA to be RNA molecules that resemble protein-coding mRNA, but cannot encode full-length proteins owing to disruptions of the reading frame. Using a rigorous computational pipeline, which rules out sequencing errors, we identify 10,679 pseudo–messenger RNAs (approximately half of which are transposon-associated) among the 102,801 FANTOM3 mouse cDNAs: just over 10% of the FANTOM3 transcriptome. These comprise not only transcribed pseudogenes, but also disrupted splice variants of otherwise protein-coding genes. Some may encode truncated proteins, only a minority of which appear subject to nonsense-mediated decay. The presence of an excess of transcripts whose only disruptions are opal stop codons suggests that there are more selenoproteins than currently estimated. We also describe compensatory frameshifts, where a segment of the gene has changed frame but remains translatable. In summary, we survey a large class of non-standard but potentially functional transcripts that are likely to encode genetic information and effect biological processes in novel ways. Many of these transcripts do not correspond cleanly to any identifiable object in the genome, implying fundamental limits to the goal of annotating all functional elements at the genome sequence level. PMID:16683022

  20. MESSENGER observations of Kelvin-Helmholtz waves at Mercury's magnetopause

    NASA Astrophysics Data System (ADS)

    Sundberg, T.; Boardsen, S. A.; Slavin, J. A.; Anderson, B. J.; Korth, H.; Zurbuchen, T.; Raines, J. M.; Solomon, S. C.

    2011-12-01

    We present a survey of Kelvin-Helmholtz (KH) waves at Mercury's magnetopause during MESSENGER's first Mercury year in orbit. The waves were identified on the basis of the well-established sawtooth wave signatures that are associated with non-linear KH vortices at the magnetopause. Remarkably, the results show that MESSENGER frequently observed such KH waves in the dayside region of the magnetosphere where the magnetosheath flow velocity is still sub-sonic, which implies that instability growth rates at Mercury's magnetopause are much larger than at Earth. The wave amplitude was often on the order of 100 nT or more, and the wave periods were ~10-20 s. A clear dawn-dusk asymmetry is also present in the data, with all of the observed events taking place in the post-noon and the dusk-side sectors of the magnetopause. This asymmetry is likely related to finite ion-gyroradius effects and is in agreement with the results from particle-in-cell simulations of the instability. Similar to most terrestrial events, the wave observations were made almost exclusively during periods when the north-south component of the magnetosheath magnetic field was northward. Accompanying measurements from the Fast Imaging Plasma Spectrometer (FIPS) show that the waves were associated with a substantial transport of magnetosheath plasma into the magnetosphere.

  1. Mineralogical indicators of Mercury's hollows composition in MESSENGER color observations

    NASA Astrophysics Data System (ADS)

    Vilas, Faith; Domingue, Deborah L.; Helbert, Jörn; D'Amore, Mario; Maturilli, Alessandro; Klima, Rachel L.; Stockstill-Cahill, Karen R.; Murchie, Scott L.; Izenberg, Noam R.; Blewett, David T.; Vaughan, William M.; Head, James W.

    2016-02-01

    Early during MErcury Surface Space ENvironment GEochemistry, and Ranging (MESSENGER)'s orbital mission, the Mercury Dual-Imaging System imaged the landform called hollows on the two craters Dominici and Hopper, using its Wide-Angle Camera with eight narrowband color filters ranging from 433 to 996 nm. An absorption feature centered in the MDIS 629 nm filter is evident in reflectance spectra for Dominici's south wall/rim hollows. A different absorption feature found in photometry of Dominici's center hollows extends through the MDIS 828 nm filter. Hollows in Hopper exhibit a weaker spectral absorption feature than that observed in Dominici's center. At Dominici, we postulate that fresher hollows-hosting material in the wall/rim was exposed to the space environment through a process of slumping of the overlying material. With time, local and global processes darken the hollows and change or mix the surface mineralogy, so that the spectral signature evolves. The hollows could contain low-density MgS and an opaque component, potentially derived from background material.

  2. Multi-Messenger Astronomy: White Dwarf Binaries, LISA and GAIA

    NASA Astrophysics Data System (ADS)

    Bueno, Michael; Breivik, Katelyn; Larson, Shane L.

    2017-01-01

    The discovery of gravitational waves has ushered in a new era in astronomy. The low-frequency band covered by the future LISA detector provides unprecedented opportunities for multi-messenger astronomy. With the Global Astrometric Interferometer for Astrophysics (GAIA) mission, we expect to discover about 1,000 eclipsing binary systems composed of a WD and a main sequence star - a sizeable increase from the approximately 34 currently known binaries of this type. In advance of the first GAIA data release and the launch of LISA within the next decade, we used the Binary Stellar Evolution (BSE) code simulate the evolution of White Dwarf Binaries (WDB) in a fixed galaxy population of about 196,000 sources. Our goal is to assess the detectability of a WDB by LISA and GAIA using the parameters from our population synthesis, we calculate GW strength h, and apparent GAIA magnitude G. We can then use a scale factor to make a prediction of how many multi- messenger sources we expect to be detectable by both LISA and GAIA in a galaxy the size of the Milky Way. We create binaries 10 times to ensure randomness in distance assignment and average our results. We then determined whether or not astronomical chirp is the difference between the total chirp and the GW chirp. With Astronomical chirp and simulations of mass transfer and tides, we can gather more information about the internal astrophysics of stars in ultra-compact binary systems.

  3. Impacts of Center of Mass Shifts on Messenger Spacecraft Operations

    NASA Technical Reports Server (NTRS)

    O'Shaughnessy, D. J.; Vaughan, R. M.; Chouinard, T. L., III; Jaekle, D. E.

    2007-01-01

    The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) has successfully completed its first three years of flight operations following launch on August 3, 2004. As part of NASA s Discovery Program, MESSENGER will observe Mercury during flybys in 2008 and 2009, as well as from orbit beginning in March 2011. This paper discusses the impact that center of mass (CM) location changes have had on many mission activities, particularly angular momentum management and maneuver execution. Momentum trends were altered significantly following the first deep-space maneuver, and these changes were related to a change in the CM. The CM location also impacts maneuver execution, and uncertainties in its location led to the significant direction errors experienced at trajectory correction maneuver 11. Because of the spacecraft sensitivity to CM location, efforts to estimate its position are important to momentum and maneuver prediction. This paper summarizes efforts to estimate the CM from flight data, as well as the operational strategy to handle CM uncertainties and their impact on momentum trends and maneuver execution accuracy.

  4. Role of WhatsApp Messenger in the Laboratory Management System: A Boon to Communication.

    PubMed

    Dorwal, Pranav; Sachdev, Ritesh; Gautam, Dheeraj; Jain, Dharmendra; Sharma, Pooja; Tiwari, Assem Kumar; Raina, Vimarsh

    2016-01-01

    The revolution of internet and specifically mobile internet has occurred at a blinding pace over the last decade. With the advent of smart phones, the hand held device has become much more than a medium of voice calling. Healthcare has been catching up with the digital revolution in the form of Hospital Information System and Laboratory Information System. However, the advent of instant messaging services, which are abundantly used by the youth, can be used to improve communication and coordination among the various stake holders in the healthcare sector. We have tried to look at the impact of using the WhatsApp messenger service in the laboratory management system, by forming multiple groups of the various subsections of the laboratory. A total of 35 members used this service for a period of 3 months and their response was taken on a scale of 1 to 10. There was significant improvement in the communication in the form of sharing photographic evidence, information about accidents, critical alerts, duty rosters, academic activities and getting directives from seniors. There was also some increase in the load of adding information to the application and disturbance in the routine activities; but the benefits far outweighed the minor hassles. We thereby suggest and foresee another communication revolution which will change the way information is shared in a healthcare sector, with hospital specific dedicated apps.

  5. The Geology of Mercury as Seen by the MESSENGER Mission

    NASA Astrophysics Data System (ADS)

    Head, James; Murchie, Scott L.; Prockter, Louise M.; Robinson, Mark; Solomon, Sean C.; Strom, Robert; Chapman, Clark; Watters, Thomas; Blewett, David T.; Denevi, Brett; Chabot, Nancy

    The three MESSENGER flybys of Mercury have yielded images of most of the planet's sur-face (including portions unseen by Mariner 10); these data have helped to address a series of questions related to the nature of geological process operating on the planet and its geologi-cal history. Volcanism: New observations show evidence for numerous volcanic vents, in the form of irregularly shaped rimless depressions, around the interior margin of the Caloris basin and elsewhere on the planet, mostly on impact crater floors. Several depressions appear to be sources of explosive volcanism, and one is surrounded by a shield in excess of 100 km in diame-ter. The interior of the Caloris basin is filled with plains units spectrally distinct from the basin rim deposits; impact crater stratigraphy and comparisons to the filling of the lunar Imbrium basin support a volcanic origin. Some smooth plains surrounding the rim of the Caloris basin show distinct differences in ages, color, and morphological properties from their surroundings, supporting a volcanic origin. Impact Cratering: New data show the characteristics and on-set diameters of fresh impact craters and document the nature of peak-ring and multi-ringed basins and their global distribution. The newly discovered 715 km-diameter Rembrandt basin shows an unusual sequence of structures and evidence for interior volcanic fill, and several well-preserved peak-ring basins provide insight into why they are relatively more common on Mercury. Tectonism: The new coverage provides evidence for the nature and global distribu-tion of extensive tectonic scarps and wrinkle ridges, and a set of radial graben discovered in central Caloris basin (Pantheon Fossae) reveals evidence for enigmatic basin-related extensional deformation. Geological History: Impact crater size-frequency distributions and stratigraphic relationships are providing new insight into the temporal relationships of geological processes and the comparative planetological

  6. MESSENGER's Low-Altitude Campaign: Mercury at Unprecedented Close Range

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; Nittler, L. R.; Byrne, P. K.

    2014-12-01

    In March 2013, the MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft began its Second Extended Mission (XM2) to acquire observations of Mercury's surface and interior at unprecedented spatial resolution and measurements of the planet's dynamic magnetosphere and exosphere at high temporal resolution during the peak and declining phase of the current solar cycle. XM2 is framed by six science questions, each motivated by discoveries and observations made during MESSENGER's Primary and First Extended Missions: (1) What active and recent processes have affected Mercury's surface? (2) How has the state of stress in Mercury's crust evolved over time? (3) How have compositions of volcanic materials on Mercury evolved over time? (4) What are the characteristics of volatile emplacement and sequestration in Mercury's north polar region? (5) What are the consequences of precipitating ions and energetic electrons at Mercury? (6) How do Mercury's exosphere and magnetosphere respond to both extreme and stable solar wind conditions during solar maximum and the declining phase of the solar cycle? Also since March 2013, the periapsis altitude, or closest approach distance to Mercury's surface, has declined progressively with each orbit, in response to the gravitational attraction of the Sun, although the rate of that decline depends on the angle between the Mercury-Sun line and MESSENGER's orbit plane. For the first year of XM2, no propulsive orbit-correction maneuvers (OCMs) were conducted to change the evolution of the spacecraft's orbital parameters. Because sufficient propellant remained at the end of that year to complete four periapsis-raising OCMs, a low-altitude campaign was designed to use those maneuvers to maximize the number of orbits for which the periapsis altitude is as low as 15-25 km. The periapsis altitude passed below 200 km altitude for the first time on 20 April 2014 and below 100 km altitude for the first time on 25 July 2014

  7. MESSENGER Observations of Induced Magnetic Fields at Mercury

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.; Winslow, R. M.; Anderson, B. J.; Korth, H.; Purucker, M. E.; Heyner, D.; Phillips, R. J.; Slavin, J. A.; Benna, M.; Solomon, S. C.

    2013-12-01

    We use orbital data from the Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft to study induction signals from Mercury's core. The weak dipole moment (190 nT-RM3, where RM is Mercury's radius) yields a mean subsolar magnetopause distance,RSS, from the dipole origin of 1.45 RM. Time variations in Mercury's magnetopause position, and hence in the magnetopause fields, are driven by changes in solar wind dynamic pressure, Pram, and induce currents in Mercury's interior, in particular at the top of the large, highly conductive core. Mercury's eccentric orbit leads to periodic, annual variations in Pram with an amplitude of ˜50% of the mean Pram. Shorter-timescale, higher-amplitude variations in Pram also occur due to variability in the solar wind. We use a model of Mercury's magnetosphere derived from MESSENGER observations together with a two-layer, radial conductivity model to calculate the expected geometry and magnitude of induced field signatures. The inducing field geometry is obtained via a spherical harmonic expansion of the model magnetopause field at distinct RSS values corresponding to the range observed in MESSENGER MAG data. For the two-layer model and time variations in the field with periods longer than ~1 h, the transfer function between the inducing and induced fields depends only on the spherical harmonic degree and on the ratio of the core radius to the planetary radius. We observe two lines of evidence for an annual induced signature at Mercury. First, RSS varies with heliocentric distance, Rh, as Rhb where b < 1/3. Second, a stronger planetary dipole moment is observed at perihelion than at aphelion. The magnitudes of the observed signals are consistent with the recent estimate of Mercury's core radius (2020 × 30 km) derived from gravity and spin-state data, and independently rule out a core radius less than ˜1900 km. Larger amplitude induced signals are observed in association with

  8. Gravity, Topography, and Magnetic Field of Mercury from Messenger

    NASA Technical Reports Server (NTRS)

    Neumann, Gregory A.; Solomon, Sean C.; Zuber, Maria T.; Phillips, Roger J.; Barnouin, Olivier; Ernst, Carolyn; Goosens, Sander; Hauck, Steven A., II; Head, James W., III; Johnson, Catherine L.; hide

    2012-01-01

    On 18 March 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was inserted into a 12-hour, near-polar orbit around Mercury, with an initial periapsis altitude of 200 km, initial periapse latitude of 60 deg N, and apoapsis at approximately 15,200 km altitude in the southern hemisphere. This orbit has permitted the mapping of regional gravitational structure in the northern hemisphere, and laser altimetry from the MESSENGER spacecraft has yielded a geodetically controlled elevation model for the same hemisphere. The shape of a planet combined with gravity provides fundamental information regarding its internal structure and geologic and thermal evolution. Elevations in the northern hemisphere exhibit a unimodal distribution with a dynamic range of 9.63 km, less than that of the Moon (19.9 km), but consistent with Mercury's higher surface gravitational acceleration. After one Earth-year in orbit, refined models of gravity and topography have revealed several large positive gravity anomalies that coincide with major impact basins. These candidate mascons have anomalies that exceed 100 mGal and indicate substantial crustal thinning and superisostatic uplift of underlying mantle. An additional uncompensated 1000-km-diameter gravity and topographic high at 68 deg N, 33 deg E lies within Mercury's northern volcanic plains. Mercury's northern hemisphere crust is generally thicker at low latitudes than in the polar region. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR2 = 0.353 +/- 0.017, where M=3.30 x 10(exp 23) kg and R=2440 km are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of Cm/C = 0.452 +/- 0.035. One proposed model for Mercury's radial density distribution consistent with these results includes silicate crust and mantle layers overlying a dense solid (possibly Fe-S) layer, a liquid Fe

  9. Dell H. Hymes: His Scholarship and Legacy in Anthropology and Education

    ERIC Educational Resources Information Center

    Hornberger, Nancy H., Ed.

    2011-01-01

    Dell Hathaway Hymes, linguistic anthropologist and educational visionary extraordinaire, passed away in November 2009, leaving behind a voluminous scholarship and inspirational legacy in the study of language and inequality, ethnography, sociolinguistics, Native American ethnopoetics, and education. This essay provides a brief account of Hymes's…

  10. Reflections--Dell C. Kjer: A Pioneer Teacher Educator and Association Leader.

    ERIC Educational Resources Information Center

    Gilstrap, Robert L.

    2000-01-01

    Reflects upon the role of Dell C. Kjer, a leader in teacher education and president of the Association for Childhood Education International (ACEI) from 1965-1967. Describes his early years in Wisconsin, military duties and student life at George Peabody, his contributions to teacher education, and his contributions to ACEI and other professional…

  11. Dell Hymes and the New Language Policy Studies: Update from an Underdeveloped Country

    ERIC Educational Resources Information Center

    McCarty, Teresa L.; Collins, James; Hopson, Rodney K.

    2011-01-01

    This essay updates Dell Hymes's "Report from an Underdeveloped Country" (the USA), positioning our analysis in the New Language Policy Studies. Taking up Hymes's call for comparative, critical studies of language use, we examine three cases, organizing our analysis around Hymes's questions: What "counts" as a language, a language problem, and…

  12. Dell H. Hymes: His Scholarship and Legacy in Anthropology and Education

    ERIC Educational Resources Information Center

    Hornberger, Nancy H., Ed.

    2011-01-01

    Dell Hathaway Hymes, linguistic anthropologist and educational visionary extraordinaire, passed away in November 2009, leaving behind a voluminous scholarship and inspirational legacy in the study of language and inequality, ethnography, sociolinguistics, Native American ethnopoetics, and education. This essay provides a brief account of Hymes's…

  13. Reflections--Dell C. Kjer: A Pioneer Teacher Educator and Association Leader.

    ERIC Educational Resources Information Center

    Gilstrap, Robert L.

    2000-01-01

    Reflects upon the role of Dell C. Kjer, a leader in teacher education and president of the Association for Childhood Education International (ACEI) from 1965-1967. Describes his early years in Wisconsin, military duties and student life at George Peabody, his contributions to teacher education, and his contributions to ACEI and other professional…

  14. Dell Hymes and the New Language Policy Studies: Update from an Underdeveloped Country

    ERIC Educational Resources Information Center

    McCarty, Teresa L.; Collins, James; Hopson, Rodney K.

    2011-01-01

    This essay updates Dell Hymes's "Report from an Underdeveloped Country" (the USA), positioning our analysis in the New Language Policy Studies. Taking up Hymes's call for comparative, critical studies of language use, we examine three cases, organizing our analysis around Hymes's questions: What "counts" as a language, a language problem, and…

  15. The MESSENGER mission to Mercury: spacecraft and mission design

    NASA Astrophysics Data System (ADS)

    Santo, Andrew G.; Gold, Robert E.; McNutt, Ralph L.; Solomon, Sean C.; Ercol, Carl J.; Farquhar, Robert W.; Hartka, Theodore J.; Jenkins, Jason E.; McAdams, James V.; Mosher, Larry E.; Persons, David F.; Artis, David A.; Bokulic, Robert S.; Conde, Richard F.; Dakermanji, George; Goss, Milton E.; Haley, David R.; Heeres, Kenneth J.; Maurer, Richard H.; Moore, Robert C.; Rodberg, Elliot H.; Stern, Theodore G.; Wiley, Samuel R.; Williams, Bobby G.; Yen, Chen-wan L.; Peterson, Max R.

    2001-12-01

    A Mercury orbiter mission is challenging from thermal and mass perspectives. The Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) mission overcomes these challenges while avoiding esoteric technologies by using an innovative approach with commonly available materials, minimal moving parts, and maximum heritage. This approach yields a spacecraft with good margins in all categories and low technical risk. The key concepts are a ceramic-cloth sunshade, an integrated lightweight structure and high- performance propulsion system, and a solar array incorporating optical solar reflectors (OSRs). The sunshade maintains the spacecraft at room temperature. The integrated structure and propulsion system provides ample mass margin. The solar array with OSRs, which has already undergone significant testing, provides thermal margin even if the panels are inadvertently pointed directly at the Sun at 0.3 AU. 0.3 AU.

  16. The dynamic N(1)-methyladenosine methylome in eukaryotic messenger RNA.

    PubMed

    Dominissini, Dan; Nachtergaele, Sigrid; Moshitch-Moshkovitz, Sharon; Peer, Eyal; Kol, Nitzan; Ben-Haim, Moshe Shay; Dai, Qing; Di Segni, Ayelet; Salmon-Divon, Mali; Clark, Wesley C; Zheng, Guanqun; Pan, Tao; Solomon, Oz; Eyal, Eran; Hershkovitz, Vera; Han, Dali; Doré, Louis C; Amariglio, Ninette; Rechavi, Gideon; He, Chuan

    2016-02-25

    Gene expression can be regulated post-transcriptionally through dynamic and reversible RNA modifications. A recent noteworthy example is N(6)-methyladenosine (m(6)A), which affects messenger RNA (mRNA) localization, stability, translation and splicing. Here we report on a new mRNA modification, N(1)-methyladenosine (m(1)A), that occurs on thousands of different gene transcripts in eukaryotic cells, from yeast to mammals, at an estimated average transcript stoichiometry of 20% in humans. Employing newly developed sequencing approaches, we show that m(1)A is enriched around the start codon upstream of the first splice site: it preferentially decorates more structured regions around canonical and alternative translation initiation sites, is dynamic in response to physiological conditions, and correlates positively with protein production. These unique features are highly conserved in mouse and human cells, strongly indicating a functional role for m(1)A in promoting translation of methylated mRNA.

  17. Gravitational Wave Multi-Messenger Prospects for Pulsar Timing Arrays

    NASA Astrophysics Data System (ADS)

    Simon, Joseph; Burke-Spolaor, Sarah

    2017-01-01

    Pulsar Timing Array (PTA) experiments are currently setting limits on the gravitational wave (GW) emission in the nanohertz frequency band. The primary source of GW emission in this band is expected to be a population of binary supermassive black holes (SMBHs) that form following galactic mergers. This population of binary supermassive black holes is representative of a crucial step in galaxy formation theories. During this process, there is the potential for many electromagnetic tracers to accompany the binary's evolution. In this talk, I will present recent work investigating the potential for jointly detecting a binary's electromagnetic and gravitational radiation. Such `multi-messenger' sources would provide a unique window into a pivotal stage of galaxy evolution, and would revolutionize the understanding of late-stage galaxy evolution.

  18. Gravitational Wave Multi-Messenger Prospects for Pulsar Timing Arrays

    NASA Astrophysics Data System (ADS)

    Simon, Joseph; Burke-Spolaor, Sarah

    2017-01-01

    Pulsar Timing Array (PTA) experiments are now setting limits on the gravitational wave (GW) emission in the nanohertz frequency band. The primary source of GW emission in this band is expected to be a population of binary supermassive black holes (SMBHs) that form following galactic mergers. This population of binary supermassive black holes are representative of a crucial step in galaxy formation theories. During the extended interaction between SMBHs and their host galaxy throughout inspiral, there is the potential for many electromagnetic tracers to accompany the binary's evolution. Using results from a suite of simulations, I will present an investigation of the potential for jointly detecting a binary’s electromagnetic and gravitational radiation. The detection of a single ‘multi-messenger' source would provide a unique window into a pivotal stage of galaxy evolution, and would revolutionize the understanding of late-stage galaxy evolution.

  19. MESSENGER observations of magnetic reconnection in Mercury's magnetosphere.

    PubMed

    Slavin, James A; Acuña, Mario H; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Boardsen, Scott A; Gloeckler, George; Gold, Robert E; Ho, George C; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Raines, Jim M; Sarantos, Menelaos; Schriver, David; Solomon, Sean C; Trávnícek, Pavel; Zurbuchen, Thomas H

    2009-05-01

    Solar wind energy transfer to planetary magnetospheres and ionospheres is controlled by magnetic reconnection, a process that determines the degree of connectivity between the interplanetary magnetic field (IMF) and a planet's magnetic field. During MESSENGER's second flyby of Mercury, a steady southward IMF was observed and the magnetopause was threaded by a strong magnetic field, indicating a reconnection rate ~10 times that typical at Earth. Moreover, a large flux transfer event was observed in the magnetosheath, and a plasmoid and multiple traveling compression regions were observed in Mercury's magnetotail, all products of reconnection. These observations indicate that Mercury's magnetosphere is much more responsive to IMF direction and dominated by the effects of reconnection than that of Earth or the other magnetized planets.

  20. New Understanding of Mercury's Magnetosphere from MESSENGER'S First Flyby

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Acuna, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Gloeckler, George; Gold, Robert E.; Ho, George C.; Killen, M.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Raines, James M.; Schriver, David; Somomon, Sean C.; Starr, Richard; Travnicek, Pavel; Zurbuchen, Thomas H.

    2008-01-01

    Observations by the MESSENGER spacecraft on 14 January 2008 have revealed new features of the solar system's smallest planetary magnetosphere. The interplanetary magnetic field orientation was unfavorable for large inputs of energy from the solar wind and no evidence of magnetic substorms, internal magnetic reconnection, or energetic particle acceleration was detected. Large-scale rotations of the magnetic field were measured along the dusk flank of the magnetosphere and ultra-tow frequency waves were frequently observed beginning near closest approach. Outbound the spacecraft encountered two current-sheet boundaries across which the magnetic field intensity decreased in a step-like manner. The outer current sheet is the magnetopause boundary. The inner current sheet is similar in structure, but weaker and -1000 km closer to the planet. Between these two current sheets the magnetic field intensity is depressed by the diamagnetic effect of planetary ions created by the photo-ionization of Mercury's exosphere.

  1. NO signaling in plant immunity: a tale of messengers.

    PubMed

    Trapet, Pauline; Kulik, Anna; Lamotte, Olivier; Jeandroz, Sylvain; Bourque, Stéphane; Nicolas-Francès, Valérie; Rosnoblet, Claire; Besson-Bard, Angélique; Wendehenne, David

    2015-04-01

    Nitric oxide (NO) is a free radical gas involved in a myriad of plant physiological processes including immune responses. How NO mediates its biological effects in plant facing microbial pathogen attack is an unresolved question. Insights into the molecular mechanisms by which it propagates signals reveal the contribution of this simple gas in complex signaling pathways shared with reactive oxygen species (ROS) and the second messenger Ca(2+). Understanding of the subtle cross-talks operating between these signals was greatly improved by the recent identification and the functional analysis of proteins regulated through S-nitrosylation, a major NO-dependent post-translational protein modification. Overall, these findings suggest that NO is probably an important component of the mechanism coordinating and regulating Ca(2+) and ROS signaling in plant immunity.

  2. Mercury's global color mosaic: An update from MESSENGER's orbital observations

    NASA Astrophysics Data System (ADS)

    Domingue, Deborah L.; Murchie, Scott L.; Denevi, Brett W.; Ernst, Carolyn M.; Chabot, Nancy L.

    2015-09-01

    We report an update to the photometric correction used to produce global color mosaics of Mercury, derived from an analysis of photometric observations acquired during the orbital phase of MESSENGER's primary mission. Comparisons between versions of the color mosaic produced with photometric corrections derived from flyby and orbital data indicate that areas imaged at high incidence and emission angles (>50°) are better standardized to a common illumination and viewing geometry with the orbit-derived corrections. Seams between images taken at very different illumination geometries, however, are still present at visually detectable levels. Further improvements to the photometric correction await updates to the radiometric calibration that will enable data retrieval over a larger range of photometric angles.

  3. Geology of the Caloris basin, Mercury: a view from MESSENGER.

    PubMed

    Murchie, Scott L; Watters, Thomas R; Robinson, Mark S; Head, James W; Strom, Robert G; Chapman, Clark R; Solomon, Sean C; McClintock, William E; Prockter, Louise M; Domingue, Deborah L; Blewett, David T

    2008-07-04

    The Caloris basin, the youngest known large impact basin on Mercury, is revealed in MESSENGER images to be modified by volcanism and deformation in a manner distinct from that of lunar impact basins. The morphology and spatial distribution of basin materials themselves closely match lunar counterparts. Evidence for a volcanic origin of the basin's interior plains includes embayed craters on the basin floor and diffuse deposits surrounding rimless depressions interpreted to be of pyroclastic origin. Unlike lunar maria, the volcanic plains in Caloris are higher in albedo than surrounding basin materials and lack spectral evidence for ferrous iron-bearing silicates. Tectonic landforms, contractional wrinkle ridges and extensional troughs, have distributions and age relations different from their counterparts in and around lunar basins, indicating a different stress history.

  4. Imaging Mercury's polar deposits during MESSENGER's low-altitude campaign

    NASA Astrophysics Data System (ADS)

    Chabot, Nancy L.; Ernst, Carolyn M.; Paige, David A.; Nair, Hari; Denevi, Brett W.; Blewett, David T.; Murchie, Scott L.; Deutsch, Ariel N.; Head, James W.; Solomon, Sean C.

    2016-09-01

    Images obtained during the low-altitude campaign in the final year of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission provide the highest-spatial-resolution views of Mercury's polar deposits. Images for distinct areas of permanent shadow within 35 north polar craters were successfully captured during the campaign. All of these regions of permanent shadow were found to have low-reflectance surfaces with well-defined boundaries. Additionally, brightness variations across the deposits correlate with variations in the biannual maximum surface temperature across the permanently shadowed regions, supporting the conclusion that multiple volatile organic compounds are contained in Mercury's polar deposits, in addition to water ice. A recent large impact event or ongoing bombardment by micrometeoroids could deliver water as well as many volatile organic compounds to Mercury. Either scenario is consistent with the distinctive reflectance properties and well-defined boundaries of Mercury's polar deposits and the presence of volatiles in all available cold traps.

  5. BACTERIAL IDENTIFICATION USING SSRA ENCODING TRANSFER-MESSENGER RNA.

    PubMed

    Osawa, Kayo; Shigemura, Katsumi; Shirai, Hiroki; Kato, Ayaka; Okuya, Yuma; Jikimoto, Takumi; Arakawa, Soichi; Fujisawa, Masato; Shirakawa, Toshiro

    2015-07-01

    Abstract. Ribosomal DNA (rDNA) sequences are widely used for phylogenetic and bacterial identification. However, rDNA of different species often reveals similar or identical same sequences. This study employed the bacterial stable small RNA (ssrA) gene encoding transfer-messenger RNA (tmRNA) as a tool for identification of Staphylococcus aureus, Enterococcus spp, Pseudomonas spp and Enterobacteriaceae from clinical isolates as representative groups using PCR and species specific primers. The method correctly identified 11 standard strains and 99 clinical isolates. Quantitative PCR revealed a limit of detection of 10(-5) µg of DNA for S. aureus and Enterococcus spp, and 10(-6) µg for Pseudomonas spp and Enterobacteriaceae. Further studies with a greater number of bacteria especially from clinical samples will need to be undertaken before this bacterial molecular marker can be applied in a clinical setting.

  6. Nuclear inositol lipid metabolism: more than just second messenger generation?

    PubMed

    Martelli, Alberto M; Follo, Matilde Yung; Evangelisti, Camilla; Falà, Federica; Fiume, Roberta; Billi, Anna Maria; Cocco, Lucio

    2005-10-01

    A distinct polyphosphoinositide cycle is present in the nucleus, and growing evidence suggests its importance in DNA replication, gene transcription, and apoptosis. Even though it was initially thought that nuclear inositol lipids would function as a source for second messengers, recent findings strongly indicate that lipids present in the nucleus also fulfil other roles. The scope of this review is to highlight the most intriguing advances made in the field over the last few years, such as the possibility that nuclear phosphatidylinositol (4,5) bisphosphate is involved in maintaining chromatin in a transcriptionally active conformation, the new emerging roles for intranuclear phosphatidylinositol (3,4,5) trisphosphate and phosphoinositide 3-kinase, and the evidence which suggests a tight relationship between a decreased level of nuclear phosphoinositide specific phospholipase C-beta1 and the evolution of myelodisplastic syndrome into acute myeloid leukemia.

  7. Tissue distribution of human acetylcholinesterase and butyrylcholinesterase messenger RNA

    SciTech Connect

    Jbilo, O.; Barteles, C.F.; Chatonnet, A.; Toutant, J.P.; Lockridge, O.

    1994-12-31

    Tissue distribution of human acetyicholinesterase and butyryicholinesterase messenger RNA. 1 Cholinesterase inhibitors occur naturally in the calabar bean (eserine), green potatoes (solanine), insect-resistant crab apples, the coca plant (cocaine) and snake venom (fasciculin). There are also synthetic cholinesterase inhibitors, for example man-made insecticides. These inhibitors inactivate acetyicholinesterase and butyrylcholinesterase as well as other targets. From a study of the tissue distribution of acetylcholinesterase and butyrylcholinesterase mRNA by Northern blot analysis, we have found the highest levels of butyrylcholinesterase mRNA in the liver and lungs, tissues known as the principal detoxication sites of the human body. These results indicate that butyrylcholinesterase may be a first line of defense against poisons that are eaten or inhaled.

  8. MESSENGER observations of induced magnetic fields in Mercury's core

    NASA Astrophysics Data System (ADS)

    Johnson, Catherine L.; Philpott, Lydia C.; Anderson, Brian J.; Korth, Haje; Hauck, Steven A.; Heyner, Daniel; Phillips, Roger J.; Winslow, Reka M.; Solomon, Sean C.

    2016-03-01

    Orbital data from the Magnetometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft allow investigation of magnetic fields induced at the top of Mercury's core by time-varying magnetospheric fields. We used 15 Mercury years of observations of the magnetopause position as well as the magnetic field inside the magnetosphere to establish the presence and magnitude of an annual induction signal. Our results indicate an annual change in the internal axial dipole term, g10, of 7.5 to 9.5 nT. For negligible mantle conductivity, the average annual induction signal provides an estimate of Mercury's core radius to within ±90 km, independent of geodetic results. Larger induction signals during extreme events are expected but are challenging to identify because of reconnection-driven erosion. Our results indicate that the magnetopause reaches the dayside planetary surface 1.5-4% of the time.

  9. Neuronal Chemokines: Versatile Messengers In Central Nervous System Cell Interaction

    PubMed Central

    de Haas, A. H.; van Weering, H. R. J.; de Jong, E. K.; Boddeke, H. W. G. M.

    2007-01-01

    Whereas chemokines are well known for their ability to induce cell migration, only recently it became evident that chemokines also control a variety of other cell functions and are versatile messengers in the interaction between a diversity of cell types. In the central nervous system (CNS), chemokines are generally found under both physiological and pathological conditions. Whereas many reports describe chemokine expression in astrocytes and microglia and their role in the migration of leukocytes into the CNS, only few studies describe chemokine expression in neurons. Nevertheless, the expression of neuronal chemokines and the corresponding chemokine receptors in CNS cells under physiological and pathological conditions indicates that neuronal chemokines contribute to CNS cell interaction. In this study, we review recent studies describing neuronal chemokine expression and discuss potential roles of neuronal chemokines in neuron–astrocyte, neuron–microglia, and neuron–neuron interaction. PMID:17952658

  10. The dynamic N1-methyladenosine methylome in eukaryotic messenger RNA

    PubMed Central

    Dominissini, Dan; Nachtergaele, Sigrid; Moshitch-Moshkovitz, Sharon; Peer, Eyal; Kol, Nitzan; Ben-Haim, Moshe Shay; Dai, Qing; Di Segni, Ayelet; Salmon-Divon, Mali; Clark, Wesley C.; Zheng, Guanqun; Pan, Tao; Solomon, Oz; Eyal, Eran; Hershkovitz, Vera; Han, Dali; Doré, Louis C.; Amariglio, Ninette; Rechavi, Gideon; He, Chuan

    2016-01-01

    Gene expression can be regulated post-transcriptionally through dynamic and reversible RNA modifications. A recent noteworthy example is N6-methyladenosine (m6A), which affects messenger RNA (mRNA) localization, stability, translation and splicing. Here we report on a new mRNA modification, N1-methyladenosine (m1A), that occurs on thousands of different gene transcripts in eukaryotic cells, from yeast to mammals, at an estimated average transcript stoichiometry of 20% in humans. Employing newly developed sequencing approaches, we show that m1A is enriched around the start codon upstream of the first splice site: it preferentially decorates more structured regions around canonical and alternative translation initiation sites, is dynamic in response to physiological conditions, and correlates positively with protein production. These unique features are highly conserved in mouse and human cells, strongly indicating a functional role for m1A in promoting translation of methylated mRNA. PMID:26863196

  11. Length-dependent translation of messenger RNA by ribosomes

    NASA Astrophysics Data System (ADS)

    Valleriani, Angelo; Zhang, Gong; Nagar, Apoorva; Ignatova, Zoya; Lipowsky, Reinhard

    2011-04-01

    A simple measure for the efficiency of protein synthesis by ribosomes is provided by the steady state amount of protein per messenger RNA (mRNA), the so-called translational ratio, which is proportional to the translation rate. Taking the degradation of mRNA into account, we show theoretically that both the translation rate and the translational ratio decrease with increasing mRNA length, in agreement with available experimental data for the prokaryote Escherichia coli. We also show that, compared to prokaryotes, mRNA degradation in eukaryotes leads to a less rapid decrease of the translational ratio. This finding is consistent with the fact that, compared to prokaryotes, eukaryotes tend to have longer proteins.

  12. Turnover of messenger RNA: Polysome statistics beyond the steady state

    NASA Astrophysics Data System (ADS)

    Valleriani, A.; Ignatova, Z.; Nagar, A.; Lipowsky, R.

    2010-03-01

    The interplay between turnover or degradation and ribosome loading of messenger RNA (mRNA) is studied theoretically using a stochastic model that is motivated by recent experimental results. Random mRNA degradation affects the statistics of polysomes, i.e., the statistics of the number of ribosomes per mRNA as extracted from cells. Since ribosome loading of newly created mRNA chains requires some time to reach steady state, a fraction of the extracted mRNA/ribosome complexes does not represent steady state conditions. As a consequence, the mean ribosome density obtained from the extracted complexes is found to be inversely proportional to the mRNA length. On the other hand, the ribosome density profile shows an exponential decrease along the mRNA for prokaryotes and becomes uniform in eukaryotic cells.

  13. [Deregulation of pre-messenger RNA splicing and rare diseases].

    PubMed

    de la Grange, Pierre

    2016-12-01

    Most of protein-coding human genes are subjected to alternative pre-mRNA splicing. This mechanism is highly regulated to precisely modulate detection of specific splice sites. This regulation is under control of the spliceosome and several splicing factors are also required to modulate the alternative usage of splice sites. Splicing factors and spliceosome components recognize splicing signals and regulatory sequences of the pre-mRNAs. These splicing sequences make splicing susceptible to polymorphisms and mutations. Examples of associations between human rare diseases and defects in pre-messenger RNA splicing are accumulating. Although many alterations are caused by mutations in splicing sequence (i.e., cis acting mutations), recent studies described the disruptive impact of mutations within spliceosome components or splicing factors (i.e., trans acting mutations). Following growing of knowledge regarding splicing regulation, several approaches have been developed to compensate for the effect of deleterious mutations and to restore sufficient amounts of functional protein.

  14. The Mercury Laser Altimeter Instrument for the MESSENGER Mission

    NASA Technical Reports Server (NTRS)

    Cavanaugh, John F.; Smith, James C.; Sun, Xiaoli; Bartels, Arlin E.; Ramos-Izquierdo, Luis; Krebs, Danny J.; Novo-Gradac, Anne marie; McGarry, Jan F.; Trunzo, Raymond; Britt, Jamie L.

    2006-01-01

    The Mercury Laser Altimeter (MLA) is one of the payload science instruments on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, which launched on 3 August 2004. The altimeter will measure the round trip time-of-flight of transmitted laser pulses reflected from the surface of the planet that, in combination with the spacecraft orbit position and pointing data, gives a high-precision measurement of surface topography referenced to Mercury's center of mass. The altimeter measurements will be used to determine the planet's forced librations by tracking the motion of large-scale topographic features as a function of time. MLA's laser pulse energy monitor and the echo pulse energy estimate will provide an active measurement of the surface reflectivity at 1064 nm. This paper describes the instrument design, prelaunch testing, calibration, and results of post-launch testing.

  15. Lipid metabolites as metabolic messengers in inter-organ communication

    PubMed Central

    Liu, Sihao; Alexander, Ryan K.; Lee, Chih-Hao

    2014-01-01

    Metabolic homeostasis is achieved through coordinated regulation across several tissues. Studies using mouse genetic models have shown that perturbation of specific pathways of lipid metabolism in metabolically active tissues impacts systemic metabolic homeostasis. The use of metabolomic technologies combined with genetic models has helped identify several potential lipid mediators that serve as metabolic messengers to communicate energy status and modulate substrate utilization among tissues. When provided exogenously, these lipid metabolites exhibit biological effects on glucose and lipid metabolism, implicating a therapeutic potential for treating metabolic diseases. In this review, we will summarize recent advances in inter-organ communication through novel mechanisms with a focus on lipid mediators synthesized de novo or derived from dietary sources and discuss challenges and future directions. PMID:24895003

  16. Gravity field and internal structure of Mercury from MESSENGER.

    PubMed

    Smith, David E; Zuber, Maria T; Phillips, Roger J; Solomon, Sean C; Hauck, Steven A; Lemoine, Frank G; Mazarico, Erwan; Neumann, Gregory A; Peale, Stanton J; Margot, Jean-Luc; Johnson, Catherine L; Torrence, Mark H; Perry, Mark E; Rowlands, David D; Goossens, Sander; Head, James W; Taylor, Anthony H

    2012-04-13

    Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 ± 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 ± 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.

  17. The evolution of Mercury's crust: a global perspective from MESSENGER.

    PubMed

    Denevi, Brett W; Robinson, Mark S; Solomon, Sean C; Murchie, Scott L; Blewett, David T; Domingue, Deborah L; McCoy, Timothy J; Ernst, Carolyn M; Head, James W; Watters, Thomas R; Chabot, Nancy L

    2009-05-01

    Mapping the distribution and extent of major terrain types on a planet's surface helps to constrain the origin and evolution of its crust. Together, MESSENGER and Mariner 10 observations of Mercury now provide a near-global look at the planet, revealing lateral and vertical heterogeneities in the color and thus composition of Mercury's crust. Smooth plains cover approximately 40% of the surface, and evidence for the volcanic origin of large expanses of plains suggests that a substantial portion of the crust originated volcanically. A low-reflectance, relatively blue component affects at least 15% of the surface and is concentrated in crater and basin ejecta. Its spectral characteristics and likely origin at depth are consistent with its apparent excavation from a lower crust or upper mantle enriched in iron- and titanium-bearing oxides.

  18. The Global Magnetic Field of Mercury from MESSENGER Orbital Observations

    NASA Astrophysics Data System (ADS)

    Anderson, Brian J.; Johnson, Catherine L.; Korth, Haje; Purucker, Michael E.; Winslow, Reka M.; Slavin, James A.; Solomon, Sean C.; McNutt, Ralph L.; Raines, Jim M.; Zurbuchen, Thomas H.

    2011-09-01

    Magnetometer data acquired by the MESSENGER spacecraft in orbit about Mercury permit the separation of internal and external magnetic field contributions. The global planetary field is represented as a southward-directed, spin-aligned, offset dipole centered on the spin axis. Positions where the cylindrical radial magnetic field component vanishes were used to map the magnetic equator and reveal an offset of 484 ± 11 kilometers northward of the geographic equator. The magnetic axis is tilted by less than 3° from the rotation axis. A magnetopause and tail-current model was defined by using 332 magnetopause crossing locations. Residuals of the net external and offset-dipole fields from observations north of 30°N yield a best-fit planetary moment of 195 ± 10 nanotesla-RM3, where RM is Mercury’s mean radius.

  19. The Messenger Spacecraft Power System Design and Early Mission Performance

    NASA Astrophysics Data System (ADS)

    Dakermanji, G.; Person, C.; Jenkins, J.; Kennedy, L.; Temkin, D.

    2005-05-01

    The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft was launched on August 3, 2004. The spacecraft will be inserted into Mercury orbit in March 2011 for one year of orbital operation. During the mission, the spacecraft distance to the Sun will vary between approximately 1 and 0.3 Astronomical Units (AU), imposing severe requirements on the spacecraft thermal and power systems design. The spacecraft is maintained behind a sunshade. The two single-axis, gimbaled solar array panels are designed to withstand the expected high temperatures. A peak power tracking system has been selected to allow operation over the widely varying solar array I-V curves. In order to reduce cost and risk while increasing the likelihood of mission success, the approach taken in the power system design, including the solar arrays, was to use conventional design, materials, and fabrication techniques.

  20. Messenger RNA modifications – Form, distribution, and function

    PubMed Central

    Gilbert, Wendy V.; Bell, Tristan A.; Schaening, Cassandra

    2016-01-01

    RNA contains more than 100 distinct modifications that promote the functions of stable non-coding RNAs in translation and splicing. Recent technical advances have revealed widespread and sparse modification of messenger RNAs with N6-methyladenosine (m6A), 5-methylcytosine (m5C) and pseudouridine (Ψ). Here we discuss the rapidly evolving understanding of the location, regulation and function of these dynamic mRNA marks, collectively termed the epitranscriptome. We highlight differences among modifications and between species that could instruct ongoing efforts to understand how specific mRNAs target sites are selected and how their modification is regulated. Diverse molecular consequences of individual m6A modifications are beginning to be revealed but the effects of m5C and Ψ remain largely unknown. Future work linking molecular effects to organismal phenotypes will broaden our understanding of mRNA modifications as cell and developmental regulators. PMID:27313037

  1. A Study to Find Out the Most Preferred Free Messenger Service Used by University Students

    ERIC Educational Resources Information Center

    Cavus, Nadire; Bicen, Huseyin

    2010-01-01

    The aim of this study is to investigate the messenger usage of students in the technology departments of the Near East University (Cyprus), and also to learn which messenger service the participants prefer. The volunteer participants in this study consisted of 150 undergraduate students attending the technology departments of the Near East…

  2. Insights into the Nature of Mercury's Exosphere: Early Results from the MESSENGER Orbital Mission Phase

    NASA Technical Reports Server (NTRS)

    McClintock, William E.; Burger, Matthew H.; Killen, Rosemary M.; Merkel, Aimee W.; Sarantos, Menelaos; Sprague, Ann L.; Solomon, Sean C.; Vervack, Ronald J., Jr.

    2011-01-01

    The Ultraviolet and Visible Spectrometer aboard the MESSENGER spacecraft has been making routine observations of Mercury's exosphere since March 29, 2011. Correlations of the spatial distributions of Ca, Mg, and Na with MESSENGER magnetic field and energetic particle distribution data provide insight into the processes that populate the neutral exosphere

  3. One Small Collection of Images, Many Giant Strides Forward for MESSENGER

    NASA Image and Video Library

    2012-07-23

    This image compilation shows some of the most exciting images taken thus far on the MESSENGER mission. A mural-sized copy hangs next to the MESSENGER Science Operations Center at the Johns Hopkins University Applied Physics Laboratory. http://photojournal.jpl.nasa.gov/catalog/PIA16364

  4. Using an Instant Messenger to Learn a Foreign Language in a Peer-Tutoring Environment

    ERIC Educational Resources Information Center

    Baek, Joeun; Yoo, Yungtai; Lee, Kyungsuk; Jung, Bokmoon; Baek, Youngkyun

    2017-01-01

    This study explores useful ways of using an instant messenger in a peer-tutoring environment when two students exchange their mother languages. Seven learners of Korean and seven Korean students learning English were paired randomly to conduct language exchange via an instant messenger, KakaoTalk. The pairs (five of male and female pair and two of…

  5. "There's a Pony in the Hallway!" A Look at Messages and Messengers.

    ERIC Educational Resources Information Center

    Zingher, Gary

    1995-01-01

    Discusses childrens' interest in messages and messengers; describes the role and impact of messages in a variety of books; and presents ideas for activities for elementary and secondary school students that suggest imaginative ways of using words, symbols, and language to offer children the chance to become messengers and communicators. (36…

  6. Messenger RNA-based vaccines: progress, challenges, applications.

    PubMed

    Kramps, Thomas; Probst, Jochen

    2013-01-01

    Twenty years after the demonstration that messenger RNA (mRNA) was expressed and immunogenic upon direct injection in mice, the first successful proof-of-concept of specific protection against viral infection in small and large animals was reported. These data indicate wider applicability to infectious disease and should encourage continued translation of mRNA-based prophylactic vaccines into human clinical trials. At the conceptual level, mRNA-based vaccines-more than other genetic vectors-combine the simplicity, safety, and focused immunogenicity of subunit vaccines with favorable immunological properties of live viral vaccines: (1) mRNA vaccines are molecularly defined and carry no excess information. In the environment and upon physical contact, RNA is rapidly degraded by ubiquitous RNases and cannot persist. These characteristics also guarantee tight control over their immunogenic profile (including avoidance of vector-specific immune responses that could interfere with repeated administration), pharmacokinetics, and dosing. (2) mRNA vaccines are synthetically produced by an enzymatic process, just requiring information about the nucleic acid sequence of the desired antigen. This greatly reduces general complications associated with biological vaccine production, such as handling of infectious agents, genetic variability, environmental risks, or restrictions to vaccine distribution. (3) RNA can be tailored to provide potent adjuvant stimuli to the innate immune system by direct activation of RNA-specific receptors; this may reduce the need for additional adjuvants. The formation of native antigen in situ affords great versatility, including intracellular localization, membrane association, posttranslational modification, supra-molecular assembly, or targeted structural optimization of delivered antigen. Messenger RNA vaccines induce balanced immune responses including B cells, helper T cells, and cytotoxic T lymphocytes, rendering them an extremely adaptable

  7. MESSENGER Observations of ULF Waves in Mercury's Foreshock Region

    NASA Technical Reports Server (NTRS)

    Le, Guan; Chi, Peter J.; Bardsen, Scott; Blanco-Cano, Xochitl; Slavin, James A.; Korth, Haje

    2012-01-01

    The region upstream from a planetary bow shock is a natural plasma laboratory containing a variety of wave particle phenomena. The study of foreshocks other than the Earth s is important for extending our understanding of collisionless shocks and foreshock physics since the bow shock strength varies with heliocentric distance from the Sun, and the sizes of the bow shocks are different at different planets. The Mercury s bow shock is unique in our solar system as it is produced by low Mach number solar wind blowing over a small magnetized body with a predominately radial interplanetary magnetic field. Previous observations of Mercury upstream ultra-low frequency (ULF) waves came exclusively from two Mercury flybys of Mariner 10. The MESSENGER orbiter data enable us to study of upstream waves in the Mercury s foreshock in depth. This paper reports an overview of upstream ULF waves in the Mercury s foreshock using high-time resolution magnetic field data, 20 samples per second, from the MESSENGER spacecraft. The most common foreshock waves have frequencies near 2 Hz, with properties similar to the 1-Hz waves in the Earth s foreshock. They are present in both the flyby data and in every orbit of the orbital data we have surveyed. The most common wave phenomenon in the Earth s foreshock is the large-amplitude 30-s waves, but similar waves at Mercury have frequencies at 0.1 Hz and occur only sporadically with short durations (a few wave cycles). Superposed on the "30-s" waves, there are spectral peaks at 0.6 Hz, not reported previously in Mariner 10 data. We will discuss wave properties and their occurrence characteristics in this paper.

  8. Mercury's Dynamic Magnetosphere: What Have We Learned from MESSENGER?

    NASA Astrophysics Data System (ADS)

    Slavin, James A.

    2016-04-01

    Mercury's magnetosphere is created by the solar wind interaction with its dipolar, spin-axis aligned, northward offset intrinsic magnetic field. Structurally it resembles that of the Earth in many respects, but the magnetic field intensities and plasma densities are all higher at Mercury due to conditions in the inner solar system. Magnetospheric plasma at Mercury appears to be primarily of solar wind origin, i.e. H+ and He++, but with 10% Na+ derived from the exosphere. Solar wind sputtering and other processes promote neutrals from the regolith into the exosphere where they may be ionized and incorporated into the magnetospheric plasma population. At this point in time, about one year after MESSENGER's impact and one year prior to BepiColombo's launch, we review MESSENGER's observations of magnetospheric dynamics and structure. In doing so we will provide our best answers to the following six questions: Question #1: How do magnetosheath conditions at Mercury differ from what is found at the other planets? Question #2: How do conditions in Mercury's magnetosheath contribute to the dynamic nature of Mercury's magnetosphere? How does magnetopause reconnection at Mercury differ from what is seen at Earth? Are flux transfer events (FTEs) a major driver of magnetospheric convection at Mercury? Question #3: Does reconnection ever erode the dayside magnetosphere to the point where the subsolar region of the surface is exposed to direct solar wind impact? To what extent do induction currents driven in Mercury's interior limit the solar wind flux to the surface? Do FTEs contribute significantly to the solar wind flux reaching the surface? Question #4: What effects do heavy planetary ions have on Mercury's magnetosphere? Question #5: Does Mercury's magnetotail store and dissipate magnetic energy in a manner analogous to substorms at Earth? How is the process affected by the lack of an ionosphere and the expected high electrical resistivity of the crust? Question #6: How

  9. MESSENGER Magnetometer Observations of the Plasma Distribution in Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Korth, H.; Anderson, B. J.; Raines, J. M.; Slavin, J. A.; Johnson, C. L.; Purucker, M. E.; Winslow, R. M.; Zurbuchen, T.; Solomon, S. C.; McNutt, R. L.

    2011-12-01

    Since insertion of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft into orbit around Mercury on 18 March 2011, the Magnetometer (MAG) has routinely observed localized reductions of the magnetic field magnitude below the level predicted by a planetary dipole model corrected for magnetospheric magnetic fields. These magnetic depressions are observed on almost every orbit, and the latitude at which they are observed is local-time dependent. The depression signatures are indicators for the presence of enhanced plasma populations, which inflate the magnetic field locally to maintain pressure balance, thus lowering the magnetic flux density. Mapping the magnetic depressions in local time and latitude, the MAG observations provide comprehensive insight into the plasma distribution near the planet, which is complementary to that provided by MESSENGER's Fast Imaging Plasma Spectrometer (FIPS). The spatial distribution shows that magnetic depressions are concentrated in two distinct regions. First, there is a population in the nightside equatorial region extending from dusk to dawn, which is offset northward from the planetary geographic equator by about 10°, commensurate with the offset of the planetary dipole. The extent of this population is indicative of the plasma sheet located in the equatorial magnetotail. A second concentration of magnetic depressions is found at high latitudes, predominantly on the dayside, and is associated with the magnetospheric cusp. The magnitude of the pressures associated with the depressions ranges from 0.1 to 3 nPa in the equatorial region, shows a systematic gradient from dusk to dawn, and reaches 10 nPa at high latitudes. We discuss the MAG observations and interpret the dusk-to-dawn gradient in the derived pressure distribution with a simple paradigm of particle drifts within Mercury's magnetosphere.

  10. MESSENGER observations of the plasma depletion layer in Mercury's magnetosphere

    NASA Astrophysics Data System (ADS)

    Gershman, D. J.; Slavin, J. A.; Raines, J. M.; Zurbuchen, T.; Anderson, B. J.; Korth, H.; Baker, D. N.; Solomon, S. C.

    2012-12-01

    Measurements made with the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft's Fast Imaging Plasma Spectrometer (FIPS) and Magnetometer (MAG) are used to determine the properties of the plasma depletion layer (PDL) that is found just exterior to Mercury's dayside magnetopause. PDLs form when interplanetary magnetic flux tubes drape around and are compressed against an obstacle to the solar wind. Such obstacles include not only planetary magnetic fields such as that of Mercury, but also the ionospheres of comets and planets without internal fields such as Venus. It is this compression of the draped flux tubes against the magnetopause that causes the solar wind plasma to flow away from the subsolar region and deplete the flux tubes of plasma. Observations of the PDL at Earth have shown that such properties of this layer as its thickness and its reduction in density are strong functions of the solar wind Alfvénic Mach number and the orientation of the interplanetary magnetic field (IMF). The MESSENGER measurements show that a PDL is indeed present at Mercury and confirm the theoretical prediction that the thickness and degree of depletion is enhanced for the very low Alfvénic Mach numbers in the inner Solar System, on average a factor of ~2 smaller than those at Earth. For several transits of the spacecraft through the magnetosheath near local noon, each lasting only a few minutes, the plasma and magnetic field of the PDL have been sampled, capturing a snapshot of the shocked solar wind near the stagnation point. The relative density reduction and thickness of the PDL are examined for each magnetospheric pass and placed into context with the set of available solar wind forcing conditions and IMF orientations in order to study the formation of these layers at Mercury with and without the presence of dayside magnetic reconnection.

  11. A comprehensive study of Mercury and MESSENGER orbit determination

    NASA Astrophysics Data System (ADS)

    Genova, Antonio; Mazarico, Erwan; Goossens, Sander; Lemoine, Frank G.; Neumann, Gregory A.; Nicholas, Joseph B.; Rowlands, David D.; Smith, David E.; Zuber, Maria; Solomon, Sean C.

    2016-10-01

    The MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury for more than 4 years. The probe started its science mission in orbit around Mercury on 18 March 2011. The Mercury Laser Altimeter (MLA) and radio science system were the instruments dedicated to geodetic observations of the topography, gravity field, orientation, and tides of Mercury. X-band radio-tracking range-rate data collected by the NASA Deep Space Network (DSN) allowed the determination of Mercury's gravity field to spherical harmonic degree and order 100, the planet's obliquity, and the Love number k2.The extensive range data acquired in orbit around Mercury during the science mission (from April 2011 to April 2015), and during the three flybys of the planet in 2008 and 2009, provide a powerful dataset for the investigation of Mercury's ephemeris. The proximity of Mercury's orbit to the Sun leads to a significant perihelion precession attributable to the gravitational flattening of the Sun (J2) and the Parameterized Post-Newtonian (PPN) coefficients γ and β, which describe the space curvature produced by a unit rest mass and the nonlinearity in superposition of gravity, respectively. Therefore, the estimation of Mercury's ephemeris can provide crucial information on the interior structure of the Sun and Einstein's general theory of relativity. However, the high correlation among J2, γ, and β complicates the combined recovery of these parameters, so additional assumptions are required, such as the Nordtvedt relationship η = 4β - γ - 3.We have modified our orbit determination software, GEODYN II, to enable the simultaneous integration of the spacecraft and central body trajectories. The combined estimation of the MESSENGER and Mercury orbits allowed us to determine a more accurate gravity field, orientation, and tides of Mercury, and the values of GM and J2 for the Sun, where G is the gravitational constant and M is the solar mass

  12. The multi-messenger search programme and results of the ANTARES neutrino telescope

    NASA Astrophysics Data System (ADS)

    De Bonis, Giulia

    2016-07-01

    The key-word of modern astronomy and astrophysics is multi-messenger: not only photons used as probes for the investigation of the Universe, but also cosmic-rays, neutrinos and gravitational waves. The multi-messenger approach is important in particular for neutrino detectors: potential astrophysical sources are predicted to emit a very faint neutrino signal and the presence of an isotropic flux of atmospheric background requires the development of effective search strategies. The multi-messenger approach can increase the discovery potential, the statistical significance of the observations and the efficiency of the detection. The advantages of the multi-messenger approach are evident, in particular, when looking at transient or flaring sources. In ANTARES, a wide programme of multi-messenger searches is active; the most relevant results will be presented in this contribution.

  13. The Na exosphere reservoir for Mercury and the Moon: Models constrained by MESSENGER and LADEE data

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Killen, R. M.

    2014-12-01

    The Na exosphere of Mercury is flux-limited, and a careful accounting of the surface reservoir is necessary in order to understand the relative importance of proposed source mechanisms for this exosphere. At the Moon, a similar analysis has not yet been performed, but recent data acquired by the Kaguya spacecraft suggest an analogous depletion of the dayside reservoir for exospheric Na. New measurements of the lunar exosphere obtained by the Lunar Atmosphere and Dust Environment Explorer (LADEE) and of Mercury's exosphere by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft provide the opportunity to constrain the main parameters determining the reservoirs for these exospheres. We present a model of the exosphere-surface system that attempts to unify these two datasets. We have developed a simulator that accepts as input partially constrained microphysical parameters of the gas-surface interaction (e.g., source rates/cross sections for different source processes, degree of thermal accommodation) to make testable predictions regarding the exosphere and uppermost surface (top 10-10 m). These flux-balance simulations demonstrate that the lunar exosphere is limited by the recycling rate of Na atoms mobilized by micrometeoroid vaporization. An important consequence is that, to obtain consistency with ground-based observations of the Na exosphere, the inferred impact vapor at the Moon must peak near the equator and decrease towards the poles because of migration of surface particles toward the poles through exospheric transport. Micrometeoroid streams can have a long-term effect on the lunar exosphere because, as shown in our model, particles introduced by such streams survive in the soil and exosphere for at least two lunations. Important but secondary effects must be provided by the solar wind in order to account for the variations observed within one lunation by LADEE. In its application to Mercury, the code uses new estimates of

  14. Mobile Learning Using Mobile Phones

    ERIC Educational Resources Information Center

    Vicente, Paula

    2013-01-01

    The participation in mobile learning programs is conditioned by having/using mobile communication technology. Those who do not have or use such technology cannot participate in mobile learning programs. This study evaluates who are the most likely participants of mobile learning programs by examining the demographic profile and mobile phone usage…

  15. 29 CFR 520.411 - Does a certificate authorizing payment of subminimum wages to messengers and/or learners remain...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... to messengers and/or learners remain in effect during the renewal process? 520.411 Section 520.411... EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.411 Does a certificate...

  16. 29 CFR 520.410 - How long does a messenger, learner, or apprentice certificate remain in effect?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false How long does a messenger, learner, or apprentice... HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding...

  17. 29 CFR 520.411 - Does a certificate authorizing payment of subminimum wages to messengers and/or learners remain...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... to messengers and/or learners remain in effect during the renewal process? 520.411 Section 520.411... EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.411 Does a certificate...

  18. 29 CFR 520.411 - Does a certificate authorizing payment of subminimum wages to messengers and/or learners remain...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to messengers and/or learners remain in effect during the renewal process? 520.411 Section 520.411... EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.411 Does a certificate...

  19. 29 CFR 520.406 - What happens once I have submitted my request for authorization to pay messengers, learners, or...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... authorization to pay messengers, learners, or apprentices subminimum wages? 520.406 Section 520.406 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.406 What happens once I...

  20. 29 CFR 520.404 - What must I demonstrate in my application for a messenger, learner, or apprentice certificate to...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false What must I demonstrate in my application for a messenger... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in...

  1. 29 CFR 520.404 - What must I demonstrate in my application for a messenger, learner, or apprentice certificate to...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false What must I demonstrate in my application for a messenger... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in...

  2. 29 CFR 520.406 - What happens once I have submitted my request for authorization to pay messengers, learners, or...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... authorization to pay messengers, learners, or apprentices subminimum wages? 520.406 Section 520.406 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.406 What happens once I...

  3. 29 CFR 520.410 - How long does a messenger, learner, or apprentice certificate remain in effect?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false How long does a messenger, learner, or apprentice... HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding...

  4. 29 CFR 520.406 - What happens once I have submitted my request for authorization to pay messengers, learners, or...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... authorization to pay messengers, learners, or apprentices subminimum wages? 520.406 Section 520.406 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.406 What happens once I...

  5. 29 CFR 520.404 - What must I demonstrate in my application for a messenger, learner, or apprentice certificate to...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false What must I demonstrate in my application for a messenger... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in...

  6. 29 CFR 520.410 - How long does a messenger, learner, or apprentice certificate remain in effect?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false How long does a messenger, learner, or apprentice... HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding...

  7. 29 CFR 520.406 - What happens once I have submitted my request for authorization to pay messengers, learners, or...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... authorization to pay messengers, learners, or apprentices subminimum wages? 520.406 Section 520.406 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.406 What happens once I...

  8. 29 CFR 520.411 - Does a certificate authorizing payment of subminimum wages to messengers and/or learners remain...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... to messengers and/or learners remain in effect during the renewal process? 520.411 Section 520.411... EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.411 Does a certificate...

  9. 29 CFR 520.410 - How long does a messenger, learner, or apprentice certificate remain in effect?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false How long does a messenger, learner, or apprentice... HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding...

  10. 29 CFR 520.404 - What must I demonstrate in my application for a messenger, learner, or apprentice certificate to...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false What must I demonstrate in my application for a messenger... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in...

  11. 29 CFR 520.410 - How long does a messenger, learner, or apprentice certificate remain in effect?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false How long does a messenger, learner, or apprentice... HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding...

  12. 29 CFR 520.411 - Does a certificate authorizing payment of subminimum wages to messengers and/or learners remain...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... to messengers and/or learners remain in effect during the renewal process? 520.411 Section 520.411... EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.411 Does a certificate...

  13. 29 CFR 520.406 - What happens once I have submitted my request for authorization to pay messengers, learners, or...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... authorization to pay messengers, learners, or apprentices subminimum wages? 520.406 Section 520.406 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.406 What happens once I...

  14. Extracellular ATP and other nucleotides-ubiquitous triggers of intercellular messenger release.

    PubMed

    Zimmermann, Herbert

    2016-03-01

    Extracellular nucleotides, and ATP in particular, are cellular signal substances involved in the control of numerous (patho)physiological mechanisms. They provoke nucleotide receptor-mediated mechanisms in select target cells. But nucleotides can considerably expand their range of action. They function as primary messengers in intercellular communication by stimulating the release of other extracellular messenger substances. These in turn activate additional cellular mechanisms through their own receptors. While this applies also to other extracellular messengers, its omnipresence in the vertebrate organism is an outstanding feature of nucleotide signaling. Intercellular messenger substances released by nucleotides include neurotransmitters, hormones, growth factors, a considerable variety of other proteins including enzymes, numerous cytokines, lipid mediators, nitric oxide, and reactive oxygen species. Moreover, nucleotides activate or co-activate growth factor receptors. In the case of hormone release, the initially paracrine or autocrine nucleotide-mediated signal spreads through to the entire organism. The examples highlighted in this commentary suggest that acting as ubiquitous triggers of intercellular messenger release is one of the major functional roles of extracellular nucleotides. While initiation of messenger release by nucleotides has been unraveled in many contexts, it may have been overlooked in others. It can be anticipated that additional nucleotide-driven messenger functions will be uncovered with relevance for both understanding physiology and development of therapy.

  15. Navigating the MESSENGER Spacecraft through End of Mission

    NASA Astrophysics Data System (ADS)

    Bryan, C. G.; Williams, B. G.; Williams, K. E.; Taylor, A. H.; Carranza, E.; Page, B. R.; Stanbridge, D. R.; Mazarico, E.; Neumann, G. A.; O'Shaughnessy, D. J.; McAdams, J. V.; Calloway, A. B.

    2015-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury from March 2011 until the end of April 2015, when it impacted the planetary surface after propellant reserves used to maintain the orbit were depleted. This highly successful mission was led by the principal investigator, Sean C. Solomon, of Columbia University. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) designed and assembled the spacecraft and served as the home for spacecraft operations. Spacecraft navigation for the entirety of the mission was provided by the Space Navigation and Flight Dynamics Practice (SNAFD) of KinetX Aerospace. Orbit determination (OD) solutions were generated through processing of radiometric tracking data provided by NASA's Deep Space Network (DSN) using the MIRAGE suite of orbital analysis tools. The MESSENGER orbit was highly eccentric, with periapsis at a high northern latitude and periapsis altitude in the range 200-500 km for most of the orbital mission phase. In a low-altitude "hover campaign" during the final two months of the mission, periapsis altitudes were maintained within a narrow range between about 35 km and 5 km. Navigating a spacecraft so near a planetary surface presented special challenges. Tasks required to meet those challenges included the modeling and estimation of Mercury's gravity field and of solar and planetary radiation pressure, and the design of frequent orbit-correction maneuvers. Superior solar conjunction also presented observational modeling issues. One key to the overall success of the low-altitude hover campaign was a strategy to utilize data from an onboard laser altimeter as a cross-check on the navigation team's reconstructed and predicted estimates of periapsis altitude. Data obtained from the Mercury Laser Altimeter (MLA) on a daily basis provided near-real-time feedback that proved invaluable in evaluating alternative orbit estimation strategies, and

  16. Results and prospects in multi-messenger particle astrophysics

    NASA Astrophysics Data System (ADS)

    Mostafa, Miguel

    2017-01-01

    In high-energy particle astrophysics the old days were certainly not better than these. Our field has thrived in the past decade with experiments covering thousands of square kilometers to measure the suppression in the flux of the highest energy cosmic rays ever observed, instrumenting a cubic kilometer of Antarctic ice to discover astrophysical neutrinos, and measuring a change in arm length as small as 10-19 m for the ground-breaking direct observation of gravitational waves. Additionally, the current generation of space-borne and ground-based gamma-ray experiments have revealed a plethora of gamma-ray sources, including pulsars, compact binaries, the galactic center, and extragalactic sources such as starburst galaxies and radio galaxies. Before the next generation of instruments bring us yet another order of magnitude in sensitivity, we can combine current observations to probe physics beyond the standard model, and to extend the high-energy frontier well above the energies accessible to laboratory accelerators. One example of this potential is the search for dark-matter annihilation and decay products. To use the multi-messenger approach effectively for probing dark-matter signatures and physics beyond the LHC energy requires understanding the origin (or acceleration mechanism) and the propagation processes. High energy protons and nuclei, neutrinos, gamma-rays, X-rays, and gravitational waves bring new and complementary views of the astrophysical sources. By comparing observations through different windows, we can use the sites of violent phenomena as a laboratory to probe the physical processes under extreme conditions throughout the Universe, and to test the fundamental laws of particle physics and gravitation. As a community we need to engage in a bold synergistic approach to understanding the violent processes that give rise to the high-energy cosmic phenomena in the Universe. In this invited talk, I will present on-going multi-messenger studies to

  17. MESSENGER Observations of Magnetopause Structure and Dynamics at Mercury

    NASA Astrophysics Data System (ADS)

    DiBraccio, G. A.; Slavin, J. A.; Boardsen, S. A.; Anderson, B. J.; Korth, H.; Zurbuchen, T.; Raines, J. M.; Baker, D. N.; McNutt, R. L.; Solomon, S. C.

    2012-12-01

    MESSENGER observations during the first three Mercury years of orbit (one Mercury year equals 88 Earth days) have been used to characterize the structure of Mercury's dayside magnetopause as a function of magnetic field properties in the incident magnetosheath. Measurements collected by MESSENGER's Magnetometer and Fast Imaging Plasma Spectrometer yielded a minimum of two dayside magnetopause encounters per day due to the 12-h orbit of the spacecraft during this interval. After applying a minimum variance analysis (MVA) to all distinct boundary crossings, we further examined only those with an intermediate to minimum eigenvalue ratio greater than 5. For the 43 events meeting this criterion, we determined (1) the normal component of the magnetic field across the current sheet, from which we inferred the rate of reconnection, (2) the temporal duration and, with certain assumptions, the speed and thickness of the magnetopause, and (3) the reconnection rate as a function of magnetic shear angle and plasma beta (the ratio of total thermal pressure to magnetic pressure) across the boundary. In boundary-normal coordinates we identified an average normal magnetic field component of 20 nT, enabling the entry of solar wind plasma into the magnetosphere. The magnetopause velocity is estimated to be on the order of 10 km/s by assuming a current sheet thickness of 7 times the gyroradius of a 1 keV solar wind proton. From this result we infer the average boundary thickness to be 49 ± 7 km, which is comparable to ~3 proton gyroradii. For a magnetosheath flow of 200 km/s and a reconnection X-line length of 3 RM, we calculate an average electric potential drop of 29 kV at the magnetopause. The rate of reconnection, the ratio of the normal magnetic field component to the total field magnitude just inside the magnetopause, is measured to be 0.15 ± 0.02. This rate, which is approximately one order of magnitude larger than typical Earth observations, is determined to be independent

  18. Observations of Mercury's Northern Cusp Region with MESSENGER's Magnetometer

    NASA Astrophysics Data System (ADS)

    Winslow, R. M.; Johnson, C. L.; Anderson, B. J.; Korth, H.; Slavin, J. A.; Purucker, M. E.; Solomon, S. C.

    2011-12-01

    We have identified Mercury's northern cusp region from orbital observations with the Magnetometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The cusp is identified from the dayside depression in the total magnetic field after removing the field predicted by a paraboloid magnetospheric model from the data. The model includes long-wavelength fields due to the internal dipole, the magnetopause, and the magnetotail, parameterized by a dipole moment of 195 nT-RM3 (where RM is Mercury's radius), offset northward from the planetary center by 484 km and aligned with the planet's spin axis, a paraboloidal magnetopause with a subsolar standoff distance of 1.4 RM, a distance to the inner edge of the tail current sheet of 1.43 RM, a tail current sheet half-width of 0.1 RM, and tail lobe field of 100 nT. We have confirmed that the cusp identification is robust with respect to changes in the parameters in the baseline magnetospheric model. An increase in the high-frequency (1-10 Hz) variability of the magnetic field is also observed on each pass at these times. A superposed epoch analysis, in which individual profiles are aligned in time on their respective cusp midpoints and stacked, indicates that on average the latitudinal extent of the cusp region is 11°, centered on 71.2° N. Cusp observations extend in local time from 7.1 hr to 17.1 hr. The minimum southerly latitude of the cusp observed to date is 56.5° N, and the maximum is 83.1° N. The general location and dimensions of the high-latitude cusp region are in agreement with those indicated by observations with MESSENGER'S Fast Imaging Plasma Spectrometer. To date, no clear correlation is observed between the cusp traversal time or the magnitude of the magnetic field depression and the interplanetary magnetic field (IMF) direction, solar wind density, or solar wind velocity. However, the largest-amplitude magnetic field depressions associated with the cusp are observed

  19. Relaxing a constraint on the number of messengers in a low-scale gauge mediation

    SciTech Connect

    Sato, Ryosuke; Yonekura, Kazuya; Yanagida, T. T.

    2010-02-15

    We propose a mechanism for relaxing a constraint on the number of messengers in low-scale gauge mediation models. The Landau pole problem for the standard-model gauge coupling constants in the low-scale gauge mediation can be circumvented by using our mechanism. An essential ingredient is a large positive anomalous dimension of messenger fields given by a large Yukawa coupling in a conformal field theory at high energies. The positive anomalous dimension reduces the contribution of the messengers to the beta function of the standard-model gauge couplings.

  20. A discontinuous hammerhead ribozyme embedded in a mammalian messenger RNA

    PubMed Central

    Martick, Monika; Horan, Lucas H.; Noller, Harry F.; Scott, William G.

    2008-01-01

    Structured RNAs embedded in the untranslated regions (UTRs) of messenger RNAs can regulate gene expression. In bacteria, control of a metabolite gene is mediated by the self-cleaving activity of a ribozyme embedded in its 5′ UTR1. This discovery has raised the question of whether gene-regulating ribozymes also exist in eukaryotic mRNAs. Here we show that highly active hammerhead ribozymes2,3 are present in the 3′ UTRs of rodent C-type lectin type II (Clec2) genes4–7. Using a hammerhead RNA motif search with relaxed delimitation of the non-conserved regions, we detected ribozyme sequences in which the invariant regions, in contrast to the previously identified continuous hammerheads8–10, occur as two fragments separated by hundreds of nucleotides. Notably, a fragment pair can assemble to form an active hammerhead ribozyme structure between the translation termination and the poly-adenylation signals within the 3′ UTR. We demonstrate that this hammerhead structure can self-cleave both in vitro and in vivo, and is able to reduce protein expression in mouse cells. These results indicate that an unrecognized mechanism of post-transcriptional gene regulation involving association of discontinuous ribozyme sequences within an mRNA may be modulating the expression of several CLEC2 proteins that function in bone remodelling and the immune response of several mammals. PMID:18615019

  1. Multifunctional triblock copolymers for intracellular messenger RNA delivery.

    PubMed

    Cheng, Connie; Convertine, Anthony J; Stayton, Patrick S; Bryers, James D

    2012-10-01

    Messenger RNA (mRNA) is a promising alternative to plasmid DNA (pDNA) for gene vaccination applications, but safe and effective delivery systems are rare. Reversible addition-fragmentation chain transfer (RAFT) polymerization was employed to synthesize a series of triblock copolymers designed to enhance the intracellular delivery of mRNA. These materials are composed of a cationic dimethylaminoethyl methacrylate (DMAEMA) segment to mediate mRNA condensation, a hydrophilic poly(ethylene glycol) methyl ether methacrylate (PEGMA) segment to enhance stability and biocompatibility, and a pH-responsive endosomolytic copolymer of diethylaminoethyl methacrylate (DEAEMA) and butyl methacrylate (BMA) designed to facilitate cytosolic entry. The blocking order and PEGMA segment length were systematically varied to investigate the effect of different polymer architectures on mRNA delivery efficacy. These polymers were monodisperse, exhibited pH-dependent hemolytic activity, and condensed mRNA into 86-216 nm particles. mRNA polyplexes formed from polymers with the PEGMA segment in the center of the polymer chain displayed the greatest stability to heparin displacement and were associated with the highest transfection efficiencies in two immune cell lines, RAW 264.7 macrophages (77%) and DC2.4 dendritic cells (50%). Transfected DC2.4 cells were shown to be capable of subsequently activating antigen-specific T cells, demonstrating the potential of these multifunctional triblock copolymers for mRNA-based vaccination strategies.

  2. Multi-messenger tests of the IceCube excess

    SciTech Connect

    Ahlers, Markus

    2014-11-18

    The IceCube Collaboration has recently found evidence for an excess of high energy neutrinos above atmospheric backgrounds. The origin of this “IceCube excess” is unknown, but multi-messenger relations with cosmic rays (CRs) and γ-rays can help to pinpoint possible candidate sources. The primary CRs associated with the signal are expected to reach energies of about 40 PeV per nucleon which can be satisfied by (extreme) Galactic or extragalactic sources. I discuss possible relations of the IceCube excess with the sources of ultra-high energy CRs and implications of γ-ray observations for various Galactic or extragalactic candidate sources. The contribution of Galactic sources can be tested via primary TeV-PeV γ-rays from the decay of neutral pions produced by the same CRs responsible for the neutrino emission. Hadronuclear interactions of CRs in extragalactic sources can be constrained by the GeV-TeV diffuse extragalactic γ-ray background.

  3. MESSENGER observations of energetic electron acceleration in Mercury's magnetotail

    NASA Astrophysics Data System (ADS)

    Dewey, Ryan; Slavin, James A.; Baker, Daniel; Raines, Jim; Lawrence, David

    2016-10-01

    Energetic particle bursts within Mercury's magnetosphere have been a source of curiosity and controversy since Mariner 10's flybys. Unfortunately, instrumental effects prevent an unambiguous determination of species, flux, and energy spectrum for the Mariner 10 events. MESSENGER data taken by the Energetic Particle Spectrometer (EPS) have now shown that these energetic particle bursts are composed entirely of electrons. EPS made directional measurements of these electrons from ~30 to 300 keV at 3 s resolution, and while the energy of these electrons sometimes exceeded 200 keV, the energy distributions usually exhibited a cutoff near 100 keV. The Gamma Ray Spectrometer (GRS) has also provided measurements of these electron events, at higher time resolution (10 ms) and energetic threshold (> 50 keV) compared to EPS. We focus on GRS electron events near the plasma sheet in Mercury's magnetotail to identify reconnection-associated acceleration mechanisms. We present observations of acceleration associated with dipolarization events (betratron acceleration), flux ropes (Fermi acceleration), and tail loading/unloading (X-line acceleration). We find that the most common source of energetic electron events in Mercury's magnetosphere are dipolarization events similar to those first observed by Mariner 10. Further, a significant dawn-dusk asymmetry is found with dipolarization-associated energetic particle bursts being more common on the dawn side of the magnetotail.

  4. Mercury's gravity, tides, and spin from MESSENGER radio science data

    NASA Astrophysics Data System (ADS)

    Verma, Ashok Kumar; Margot, Jean-Luc

    2016-09-01

    We analyze radio tracking data obtained during 1311 orbits of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in the period March 2011 to April 2014. A least squares minimization of the residuals between observed and computed values of two-way range and Doppler allows us to solve for a model describing Mercury's gravity, tidal response, and spin state. We use a spherical harmonic representation of the gravity field to degree and order 40 and report error bars corresponding to 10 times the formal uncertainties of the fit. Our estimate of the product of Mercury's mass and the gravitational constant, GM = (22031.87404 ± 9×10-4) km3 s-2, is in excellent agreement with published results. Our solution for the geophysically important second-degree coefficients (C¯2,0=-2.25100×10-5±1.3×10-9, C¯2,2=1.24973×10-5±1.2×10-9) confirms previous estimates to better than 0.4% and, therefore, inferences about Mercury's moment of inertia and interior structure. Our estimate of the tidal Love number k2 = 0.464 ± 0.023 indicates that Mercury's mantle may be hotter and weaker than previously thought. Our spin state solution suggests that gravity-based estimates of Mercury's spin axis orientation are marginally consistent with previous measurements of the orientation of the crust.

  5. Internet messenger based smart virtual class learning using ubiquitous computing

    NASA Astrophysics Data System (ADS)

    Umam, K.; Mardi, S. N. S.; Hariadi, M.

    2017-06-01

    Internet messenger (IM) has become an important educational technology component in college education, IM makes it possible for students to engage in learning and collaborating at smart virtual class learning (SVCL) using ubiquitous computing. However, the model of IM-based smart virtual class learning using ubiquitous computing and empirical evidence that would favor a broad application to improve engagement and behavior are still limited. In addition, the expectation that IM based SVCL using ubiquitous computing could improve engagement and behavior on smart class cannot be confirmed because the majority of the reviewed studies followed instructions paradigms. This article aims to present the model of IM-based SVCL using ubiquitous computing and showing learners’ experiences in improved engagement and behavior for learner-learner and learner-lecturer interactions. The method applied in this paper includes design process and quantitative analysis techniques, with the purpose of identifying scenarios of ubiquitous computing and realize the impressions of learners and lecturers about engagement and behavior aspect and its contribution to learning

  6. Topicality and Impact in Social Media: Diverse Messages, Focused Messengers

    PubMed Central

    Weng, Lilian; Menczer, Filippo

    2015-01-01

    We have a limited understanding of the factors that make people influential and topics popular in social media. Are users who comment on a variety of matters more likely to achieve high influence than those who stay focused? Do general subjects tend to be more popular than specific ones? Questions like these demand a way to detect the topics hidden behind messages associated with an individual or a keyword, and a gauge of similarity among these topics. Here we develop such an approach to identify clusters of similar hashtags in Twitter by detecting communities in the hashtag co-occurrence network. Then the topical diversity of a user’s interests is quantified by the entropy of her hashtags across different topic clusters. A similar measure is applied to hashtags, based on co-occurring tags. We find that high topical diversity of early adopters or co-occurring tags implies high future popularity of hashtags. In contrast, low diversity helps an individual accumulate social influence. In short, diverse messages and focused messengers are more likely to gain impact. PMID:25710685

  7. Purification of Messenger Ribonucleoprotein Particles via a Tagged Nascent Polypeptide

    PubMed Central

    Inchaustegui Gil, Diana P.; Clayton, Christine

    2016-01-01

    The cytoplasmic fates of mRNAs are influenced by interactions between RNA-binding proteins and cis regulatory motifs. In the cytoplasm, mRNAs are present as messenger ribonucleoprotein particles, which include not only proteins that bind directly to the mRNA, but also additional proteins that are recruited via protein-protein interactions. Many labs have sought to purify such particles from cells, with limited success. We here describe a simple two-step procedure to purify actively translated mRNAs, with their associated proteins, from polysomes. We use a reporter mRNA that encodes a protein with three streptavidin binding peptides at the N-terminus. The polysomal reporter mRNA, with associated proteins, is purified via binding to a streptavidin matrix. The method takes four days, and can be applied in any cell that can be genetically manipulated. Using Trypanosoma brucei as a model system, we routinely purified 8% of the input reporter mRNA, with roughly 22-fold enrichment relative to un-tagged mRNAs, a final reporter-mRNA:total-mRNA ratio of about 1:10, and a protein purification factor of slightly over 1000-fold. Although the overall reporter mRNP composition is masked by the presence of proteins that are associated with many polysomal mRNAs, our method can be used to detect association of an RNA-binding protein that binds to specifically to a reporter mRNA. PMID:26808308

  8. Second Messenger-Operated Calcium Entry Through TRPC6.

    PubMed

    Bouron, Alexandre; Chauvet, Sylvain; Dryer, Stuart; Rosado, Juan A

    2016-01-01

    Canonical transient receptor potential 6 (TRPC6) proteins assemble into heteromultimeric structures forming non-selective cation channels. In addition, many TRPC6-interacting proteins have been identified like some enzymes, channels, pumps, cytoskeleton-associated proteins, immunophilins, or cholesterol-binding proteins, indicating that TRPC6 are engaged into macromolecular complexes. Depending on the cell type and the experimental conditions used, TRPC6 activity has been reported to be controlled by diverse modalities. For instance, the second messenger diacylglycerol, store-depletion, the plant extract hyperforin or H2O2 have all been shown to trigger the opening of TRPC6 channels. A well-characterized consequence of TRPC6 activation is the elevation of the cytosolic concentration of Ca(2+). This latter response can reflect the entry of Ca(2+) through open TRPC6 channels but it can also be due to the Na(+)/Ca(2+) exchanger (operating in its reverse mode) or voltage-gated Ca(2+) channels (recruited in response to a TRPC6-mediated depolarization). Although TRPC6 controls a diverse array of biological functions in many tissues and cell types, its pathophysiological functions are far from being fully understood. This chapter covers some key features of TRPC6, with a special emphasis on their biological significance in kidney and blood cells.

  9. Gravity Field and Internal Structure of Mercury from MESSENGER

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.; Hauck, Steven A., II; Lemoine, Frank G.; Mazarico, Erwan; Neumann, Gregory A.; Peale, Stanton J.; Margot, Jean-Luc; hide

    2012-01-01

    Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/M(R(exp 2) = 0.353 +/- 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(sub m)/C = 0.452 +/- 0.035. A model for Mercury s radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.

  10. MESSENGER Observations of the Plasma Environment near Mercury

    NASA Astrophysics Data System (ADS)

    Raines, J. M.; Zurbuchen, T.; Gloeckler, G.; Slavin, J. A.; Krimigis, S. M.; McNutt, R. L.; Solomon, S. C.

    2009-12-01

    The MESSENGER spacecraft measured the bulk plasma characteristics of Mercury’s magnetosphere and solar wind environment with the Fast Imaging Plasma Spectrometer (FIPS) sensor during three flybys of the planet on 14 January 2008, 6 October 2008, and 29 September 2009. FIPS has a near-hemispheric instantaneous field of view and provides plasma and compositional parameters for particles from 100 eV to 13 keV energy per charge at 8-s time resolution. In combination with magnetic field data, we first identified macroscopic features of Mercury's plasma environment observed during the three flybys, including bow-shock and magnetopause crossings as well as the magnetospheric plasma sheet and lobe. We then devised procedures to recover density and temperature through use of a software instrument model that includes the time-dependent instrument field of view, as well as spacecraft position and velocity coordinates. Finally, we recovered parameters from flow-breaking regions, where magnetospheric flow stagnates. In these regions, recovery is greatly simplified by the assumption of zero plasma velocity toward the planet, thus providing a good place for the first application of our recovery procedure.

  11. Protein secondary structural types are differentially coded on messenger RNA.

    PubMed Central

    Thanaraj, T. A.; Argos, P.

    1996-01-01

    Tricodon regions on messenger RNAs corresponding to a set of proteins from Escherichia coli were scrutinized for their translation speed. The fractional frequency values of the individual codons as they occur in mRNAs of highly expressed genes from Escherichia coli were taken as an indicative measure of the translation speed. The tricodons were classified by the sum of the frequency values of the constituent codons. Examination of the conformation of the encoded amino acid residues in the corresponding protein tertiary structures revealed a correlation between codon usage in mRNA and topological features of the encoded proteins. Alpha helices on proteins tend to be preferentially coded by translationally fast mRNA regions while the slow segments often code for beta strands and coil regions. Fast regions correspondingly avoid coding for beta strands and coil regions while the slow regions similarly move away from encoding alpha helices. Structural and mechanistic aspects of the ribosome peptide channel support the relevance of sequence fragment translation and subsequent conformation. A discussion is presented relating the observation to the reported kinetic data on the formation and stabilization of protein secondary structural types during protein folding. The observed absence of such strong positive selection for codons in non-highly expressed genes is compatible with existing theories that mutation pressure may well dominate codon selection in non-highly expressed genes. PMID:8897597

  12. Topicality and impact in social media: diverse messages, focused messengers.

    PubMed

    Weng, Lilian; Menczer, Filippo

    2015-01-01

    We have a limited understanding of the factors that make people influential and topics popular in social media. Are users who comment on a variety of matters more likely to achieve high influence than those who stay focused? Do general subjects tend to be more popular than specific ones? Questions like these demand a way to detect the topics hidden behind messages associated with an individual or a keyword, and a gauge of similarity among these topics. Here we develop such an approach to identify clusters of similar hashtags in Twitter by detecting communities in the hashtag co-occurrence network. Then the topical diversity of a user's interests is quantified by the entropy of her hashtags across different topic clusters. A similar measure is applied to hashtags, based on co-occurring tags. We find that high topical diversity of early adopters or co-occurring tags implies high future popularity of hashtags. In contrast, low diversity helps an individual accumulate social influence. In short, diverse messages and focused messengers are more likely to gain impact.

  13. Gravity Field and Internal Structure of Mercury from MESSENGER

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.; Hauck, Steven A., II; Lemoine, Frank G.; Mazarico, Erwan; Neumann, Gregory A.; Peale, Stanton J.; Margot, Jean-Luc; Johnson, Catherine L.; Torrence, Mark H.; Perry, Mark E.; Rowlands, David D.; Goossens, Sander; Head, James W.; Taylor, Anthony H.

    2012-01-01

    Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/M(R(exp 2) = 0.353 +/- 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(sub m)/C = 0.452 +/- 0.035. A model for Mercury s radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.

  14. Mobility management in mobile IP

    NASA Astrophysics Data System (ADS)

    Medidi, Sirisha; Golshani, Forouzan

    2002-07-01

    There is an emerging interest in integrating mobile wireless communication with the Internet based on the Ipv6 technology. Many issues introduced by the mobility of users arise when such an integration is attempted. This paper addresses the problem of mobility management, i.e., that of tracking the current IP addresses of mobile terminals and sustaining active IP connections as mobiles move. The paper presents some architectural and mobility management options for integrating wireless access to the Internet. We then present performance results for Mobile IPv4, route optimization and Mobile IPv6.

  15. Seismic refraction studies at the Painter Street bridge site, Rio Dell, California

    SciTech Connect

    Heuze, F.E.; Swift, R.P.

    1991-09-01

    This report summarizes the results of seismic refraction P- and S-wave measurements, at the site of the Painter Street bridge, in Rio Dell, California. The bridge is spanning highway US 101, 4 miles south of Fortuna, in northwestern California. This study was performed to provide an estimate of material properties for the foundation of the bridge, in support of a seismic stability analysis of the bridge performed at LLNL by D. McCallen. The Rio Dell region is seismically active and the Painter Street bridge is one of only 2 bridges of its type in California, instrumented for strong motion recordings. Measurements were made using a 12-channel Geometric/Nimbus ES 1210 Signal Enhancement Seismograph. 3 refs., 21 figs., 1 tab.

  16. A Protein of Molecular Weight 78,000 Bound to the Polyadenylate Region of Eukaryotic Messenger RNAs

    PubMed Central

    Blobel, Günter

    1973-01-01

    Two distinct proteins were found to be tightly bound to the heterogeneous messenger RNAs associated with polysomes in mouse L cells and rat hepatocytes. The molecular weight (78,000) of the larger of these two proteins is identical to that of the protein previously found associated with rabbit globin messenger RNA. This protein is shown to be bound to the adenylate-rich region of messenger RNA. The molecular weight of the smaller protein associated with messenger RNAs from hepatic and L-cell polysomes is similar to that found in globin messenger ribonucleoprotein. Images PMID:4515002

  17. Mechanical forces and their second messengers in stimulating cell growth in vitro

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman H.

    1992-01-01

    Mechanical forces play an important role in modulating the growth of a number of different tissues including skeletal muscle, smooth muscle, cardiac muscle, bone, endothelium, epithelium, and lung. As interest increases in the molecular mechanisms by which mechanical forces are transduced into growth alterations, model systems are being developed to study these processes in tissue culture. This paper reviews the current methods available for mechanically stimulating tissue cultured cells. It then outlines some of the putative 'mechanogenic' second messengers involved in altering cell growth. Not surprisingly, many mechanogenic second messengers are the same as those involved in growth factor-induced cell growth. It is hypothesized that from an evolutionary standpoint, some second messenger systems may have initially evolved for unicellular organisms to respond to physical forces such as gravity and mechanical perturbation in their environment. As multicellular organisms came into existence, they appropriated these mechanogenic second messenger cascades for cellular regulation by growth factors.

  18. Mechanical forces and their second messengers in stimulating cell growth in vitro

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman H.

    1992-01-01

    Mechanical forces play an important role in modulating the growth of a number of different tissues including skeletal muscle, smooth muscle, cardiac muscle, bone, endothelium, epithelium, and lung. As interest increases in the molecular mechanisms by which mechanical forces are transduced into growth alterations, model systems are being developed to study these processes in tissue culture. This paper reviews the current methods available for mechanically stimulating tissue cultured cells. It then outlines some of the putative 'mechanogenic' second messengers involved in altering cell growth. Not surprisingly, many mechanogenic second messengers are the same as those involved in growth factor-induced cell growth. It is hypothesized that from an evolutionary standpoint, some second messenger systems may have initially evolved for unicellular organisms to respond to physical forces such as gravity and mechanical perturbation in their environment. As multicellular organisms came into existence, they appropriated these mechanogenic second messenger cascades for cellular regulation by growth factors.

  19. Planetary ephemeris construction and general relativity tests of PPN-formalism with MESSENGER radioscience data

    NASA Astrophysics Data System (ADS)

    Verma, Ashok Kumar; Fienga, A.; Laskar, J.; Manche, H.; Gastineau, M.

    2013-10-01

    Current knowledge of Mercury orbit is mainly brought by the direct radar ranging obtained from the 60s to 1998 and five Mercury flybys made by Mariner 10 in the 70s, and MESSENGER made in 2008 and 2009. On March 18, 2011, MESSENGER became the first spacecraft orbiting Mercury. The radioscience observations acquired during the orbital phase of MESSENGER drastically improved our knowledge of the Mercury orbit. An accurate MESSENGER orbit is obtained by fitting one-and-half years of tracking data using GINS orbit determination software. The systematic error in the Earth-Mercury geometric positions, also called range bias, obtained from GINS are then used to fit the INPOP dynamical modeling of the planet motions. An improved ephemeris of the planets is then obtained, INPOP13a, and used to perform general relativity test of PPN-formalism. Our estimations of PPN parameters (β and γ) are most stringent than previous results.

  20. Early MESSENGER Results for Less Abundant or Weakly Emitting Species in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Vervack, Ronald J., Jr.; McClintock, William E.; Killen, Rosemary M.; Sprague, Ann L.; Burger, Matthew H.; Merkel, Aimee W.; Sarantos, Menelaos

    2011-01-01

    Now that the Messenger spacecraft is in orbit about Mercury, the extended observing time enables searches for exospheric species that are less abundant or weakly emitting compared with those for which emission has previously been detected. Many of these species cannot be observed from the ground because of terrestrial atmospheric absorption. We report here on the status of MESSENGER orbital-phase searches for additional species in Mercury's exosphere.

  1. m6A-dependent regulation of messenger RNA stability

    PubMed Central

    Wang, Xiao; Lu, Zhike; Gomez, Adrian; Hon, Gary C.; Yue, Yanan; Han, Dali; Fu, Ye; Parisien, Marc; Dai, Qing; Jia, Guifang; Ren, Bing; Pan, Tao; He, Chuan

    2013-01-01

    N6-methyladenosine (m6A) is the most prevalent internal (non-cap) modification present in the messenger RNA (mRNA) of all higher eukaryotes1,2. Although essential to cell viability and development3–5, the exact role of m6A modification remains to be determined. The recent discovery of two m6A demethylases in mammalian cells highlighted the importance of m6A in basic biological functions and disease6–8. Here we show that m6A is selectively recognized by the human YTH domain family 2 (YTHDF2) protein to regulate mRNA degradation. We identified over 3,000 cellular RNA targets of YTHDF2, most of which are mRNAs, but which also include non-coding RNAs, with a conserved core motif of G(m6A)C. We further establish the role of YTHDF2 in RNA metabolism, showing that binding of YTHDF2 results in the localization of bound mRNA from the translatable pool to mRNA decay sites, such as processing bodies9. The C-terminal domain of YTHDF2 selectively binds to m6A-containing mRNA whereas the N-terminal domain is responsible for the localization of the YTHDF2-mRNA complex to cellular RNA decay sites. Our results indicate that the dynamic m6A modification is recognized by selective-binding proteins to affect the translation status and lifetime of mRNA. PMID:24284625

  2. Opioid modulation of immunocompetence: Receptor characterization and second messenger involvement

    SciTech Connect

    Hemmick, L.M.

    1989-01-01

    The purpose of this thesis was to examine the effects of opioids on several indices of immunocompetence, determined the receptor specificity of these effects, and ascertain whether the actions of opioids on lymphocytes could be correlated with activation of second messenger systems. By measuring {sup 45}Ca{sup 2+} uptake into lymphocytes, it was demonstrated that {beta}-endorphin 1-31 ({beta}-END 1-31) enhanced rat thymocyte Ca{sup 2+} uptake in response to concanavalin A (Con A) but not phytohemagglutinin (PHA). Related opioid peptides and alkaloids were unable to mimic the effect, and naloxone did not block it, suggesting that {beta}-END 1-31 acted by binding to specific, non-opioid receptors on the thymocytes. Rat splenocyte Con A-stimulated Ca{sup 2+} uptake was not affected by {beta}-END 1-31. {beta}-END 1-31 did not affect basal Ca{sup 2+} uptake by either cell type. Using ({sup 3}H)thymidine uptake as an index of lymphocyte proliferation, {beta}-END 1-31 and several related opioid peptides reversed prostaglandin E{sub 1} (PGE{sub 1}) suppression of rat lymph node cell Con A- and PHA-stimulated proliferation. Naloxone did not block the reversal. {beta}-END 1-31 was unable to reverse forskolin and cholera toxin suppression of proliferation, indicating that the lowering of cyclic AMP levels was not the mechanism involved. Verapamil inhibition of proliferation was also not reversed by {beta}-END 1-31, suggesting that promotion of Ca{sup 2+} influx was not a major mechanism involved.

  3. Basin Formation and Cratering on Mercury Revealed by MESSENGER

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Fassett, C.; Marchi, S.; Merline, W. J.; Ostrach, L. R.; Prockter, L. M.

    2015-12-01

    Mercury has been bombarded by asteroids and comets throughout its history. The resulting craters and basins are the dominant topographic features on the planet. Although visible basins contain some of the most interesting tectonic features, plains, and evidence of vertical stratigraphy, they fall far short of saturating the surface. Nevertheless, Mercury has a greater spatial density of peak-ring basins and protobasins than any other Solar System body, partly because these morphologies begin at smaller sizes than on most bodies. Cratering at approximately three times the cratering rate on the Moon, combined with likely plains-forming volcanism, prevents recognition of surface features older than 4.0 to 4.1 Ga. Severe losses of craters <50 km in diameter (<20 km in some places) are ascribed to extensive formation of intercrater plains. Estimates of the cratering chronology of Mercury suggest that most plains formation ended about 3.6 to 3.7 Ga, though activity has continued in a few small regions until much more recently (e.g., inside the Rachmaninoff basin). Mercury, compared with other terrestrial bodies, is struck by projectiles impacting at much higher velocities, which is probably responsible for the formation of abundant secondary craters that dominate the numbers of craters <10 km diameter on older plains surfaces. The history of high-velocity bombardment has resulted in the production of abundant impact melts and has churned and processed the regolith, and eroded older topography, more thoroughly than on other Solar System bodies. Although the possible role of Mercury-specific impactors ("vulcanoids") cannot be excluded, imaging searches by MESSENGER have revealed no remaining vulcanoids and no other evidence suggests that Mercury has been bombarded by anything other than the same populations of asteroids and comets that have impacted the Moon and other terrestrial planets from the end of the period of heavy bombardment 3.8 to 3.9 Ga to the present.

  4. Human Bocavirus Capsid Messenger RNA Detection in Children With Pneumonia.

    PubMed

    Schlaberg, Robert; Ampofo, Krow; Tardif, Keith D; Stockmann, Chris; Simmon, Keith E; Hymas, Weston; Flygare, Steven; Kennedy, Brett; Blaschke, Anne; Eilbeck, Karen; Yandell, Mark; McCullers, Jon A; Williams, Derek J; Edwards, Kathryn; Arnold, Sandra R; Bramley, Anna; Jain, Seema; Pavia, Andrew T

    2017-09-15

    The role of human bocavirus (HBoV) in respiratory illness is uncertain. HBoV genomic DNA is frequently detected in both ill and healthy children. We hypothesized that spliced viral capsid messenger RNA (mRNA) produced during active replication might be a better marker for acute infection. As part of the Etiology of Pneumonia in the Community (EPIC) study, children aged <18 years who were hospitalized with community-acquired pneumonia (CAP) and children asymptomatic at the time of elective outpatient surgery (controls) were enrolled. Nasopharyngeal/oropharyngeal specimens were tested for HBoV mRNA and genomic DNA by quantitative polymerase chain reaction. HBoV DNA was detected in 10.4% of 1295 patients with CAP and 7.5% of 721 controls (odds ratio [OR], 1.4 [95% confidence interval {CI}, 1.0-2.0]); HBoV mRNA was detected in 2.1% and 0.4%, respectively (OR, 5.1 [95% CI, 1.6-26]). When adjusted for age, enrollment month, and detection of other respiratory viruses, HBoV mRNA detection (adjusted OR, 7.6 [95% CI, 1.5-38.4]) but not DNA (adjusted OR, 1.2 [95% CI, .6-2.4]) was associated with CAP. Among children with no other pathogens detected, HBoV mRNA (OR, 9.6 [95% CI, 1.9-82]) was strongly associated with CAP. Detection of HBoV mRNA but not DNA was associated with CAP, supporting a pathogenic role for HBoV in CAP. HBoV mRNA could be a useful target for diagnostic testing.

  5. In-Flight performance of MESSENGER's Mercury dual imaging system

    USGS Publications Warehouse

    Hawkins, S.E.; Murchie, S.L.; Becker, K.J.; Selby, C.M.; Turner, F.S.; Noble, M.W.; Chabot, N.L.; Choo, T.H.; Darlington, E.H.; Denevi, B.W.; Domingue, D.L.; Ernst, C.M.; Holsclaw, G.M.; Laslo, N.R.; Mcclintock, W.E.; Prockter, L.M.; Robinson, M.S.; Solomon, S.C.; Sterner, R.E.

    2009-01-01

    The Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 and planned for insertion into orbit around Mercury in 2011, has already completed two flybys of the innermost planet. The Mercury Dual Imaging System (MDIS) acquired nearly 2500 images from the first two flybys and viewed portions of Mercury's surface not viewed by Mariner 10 in 1974-1975. Mercury's proximity to the Sun and its slow rotation present challenges to the thermal design for a camera on an orbital mission around Mercury. In addition, strict limitations on spacecraft pointing and the highly elliptical orbit create challenges in attaining coverage at desired geometries and relatively uniform spatial resolution. The instrument designed to meet these challenges consists of dual imagers, a monochrome narrow-angle camera (NAC) with a 1.5?? field of view (FOV) and a multispectral wide-angle camera (WAC) with a 10.5?? FOV, co-aligned on a pivoting platform. The focal-plane electronics of each camera are identical and use a 1024??1024 charge-coupled device detector. The cameras are passively cooled but use diode heat pipes and phase-change-material thermal reservoirs to maintain the thermal configuration during the hot portions of the orbit. Here we present an overview of the instrument design and how the design meets its technical challenges. We also review results from the first two flybys, discuss the quality of MDIS data from the initial periods of data acquisition and how that compares with requirements, and summarize how in-flight tests are being used to improve the quality of the instrument calibration. ?? 2009 SPIE.

  6. Limits to Mercury's Magnesium Exosphere from MESSENGER Second Flyby Observations

    NASA Technical Reports Server (NTRS)

    Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Bradley, E. Todd; Vervack, Ronald J., Jr.; Benna, Mehdi; Slavin, James A.

    2011-01-01

    The discovery measurements of Mercury's exospheric magnesium, obtained by the MErcury Surface. Space ENvironment, GEochemistry. and Ranging (MESSENGER) probe during its second Mercury flyby, are modeled to constrain the source and loss processes for this neutral species. Fits to a Chamberlain exosphere reveal that at least two source temperatures are required to reconcile the distribution of magnesium measured far from and near the planet: a hot ejection process at the equivalent temperature of several tens of thousands of degrees K, and a competing, cooler source at temperatures as low as 400 K. For the energetic component, our models indicate that the column abundance that can be attributed to sputtering under constant southward interplanetary magnetic field (IMF) conditions is at least a factor of five less than the rate dictated by the measurements, Although highly uncertain, this result suggests that another energetic process, such as the rapid dissociation of exospheric MgO, may be the main source of the distant neutral component. If meteoroid and micrometeoroid impacts eject mainly molecules, the total amount of magnesium at altitudes exceeding approximately 100 km is found to be consistent with predictions by impact vaporization models for molecule lifetimes of no more than two minutes. Though a sharp increase in emission observed near the dawn terminator region can be reproduced if a single meteoroid enhanced the impact vapor at equatorial dawn, it is much more likely that observations in this region, which probe heights increasingly near the surface, indicate a reservoir of volatile Mg being acted upon by lower-energy source processes.

  7. MESSENGER observations of flux ropes in Mercury's magnetotail

    NASA Astrophysics Data System (ADS)

    DiBraccio, Gina A.; Slavin, James A.; Imber, Suzanne M.; Gershman, Daniel J.; Raines, Jim M.; Jackman, Caitriona M.; Boardsen, Scott A.; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; McNutt, Ralph L.; Solomon, Sean C.

    2015-09-01

    We report an investigation of magnetic reconnection in Mercury's magnetotail conducted with MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer measurements during seven "hot seasons" when the periapsis of the spacecraft orbit is on Mercury's dayside. Flux ropes are formed in the cross-tail current sheet by reconnection. We have analyzed 49 flux ropes observed between 1.7 RM and 2.8 RM (where RM is Mercury's radius, or 2440 km) down the tail from the center of the planet, for which minimum variance analysis indicates that the spacecraft passed near the central axis of the structure. An average Alfvén speed of 465 km s-1 is measured in the plasma sheet surrounding these flux ropes. Under the assumption that the flux ropes moved at the local Alfvén speed, the mean duration of 0.74±0.15 s determined for these structures implies a typical diameter of ~345 km, or ~0.14 RM, which is comparable to a proton gyroradius in the plasma sheet of ~380 km. We successfully fit the magnetic signatures of 16 flux ropes to a force-free model. The mean radius and core field determined in this manner were ~450 km, or ~0.18 RM, and ~40 nT, respectively. A superposed epoch analysis of the magnetic field during these events shows variations similar to those observed at Earth, including the presence of a post-plasmoid plasma sheet, filled with disconnected magnetic flux, but the timescales are 40 times shorter at Mercury. The results of this flux rope survey indicate that intense magnetic reconnection occurs frequently in the cross-tail current layer of this small but extremely dynamic magnetosphere.

  8. Limits to Mercury's magnesium exosphere from MESSENGER second flyby observations

    NASA Astrophysics Data System (ADS)

    Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Todd Bradley, E.; Vervack, Ronald J.; Benna, Mehdi; Slavin, James A.

    2011-12-01

    The discovery measurements of Mercury's exospheric magnesium, obtained by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) probe during its second Mercury flyby, are modeled to constrain the source and loss processes for this neutral species. Fits to a Chamberlain exosphere reveal that at least two source temperatures are required to reconcile the distribution of magnesium measured far from and near the planet: a hot ejection process at the equivalent temperature of several tens of thousands of degrees K, and a competing, cooler source at temperatures as low as 400 K. For the energetic component, our models indicate that the column abundance that can be attributed to sputtering under constant southward interplanetary magnetic field conditions is at least a factor of five less than the rate dictated by the measurements. Although highly uncertain, this result suggests that another energetic process, such as the rapid dissociation of exospheric MgO, may be the main source of the distant neutral component. If meteoroid and micrometeoroid impacts eject mainly molecules, the total amount of magnesium at altitudes exceeding ˜100 km is found to be consistent with predictions by impact vaporization models for molecule lifetimes of no more than two minutes. Though a sharp increase in emission observed near the dawn terminator region can be reproduced if a single meteoroid enhanced the impact vapor at equatorial dawn, it is much more likely that observations in this region, which probe heights increasingly near the surface, indicate a reservoir of volatile Mg being acted upon by lower-energy source processes.

  9. Mercury's magnetopause and bow shock from MESSENGER Magnetometer observations

    NASA Astrophysics Data System (ADS)

    Winslow, Reka M.; Anderson, Brian J.; Johnson, Catherine L.; Slavin, James A.; Korth, Haje; Purucker, Michael E.; Baker, Daniel N.; Solomon, Sean C.

    2013-05-01

    We have established the average shape and location of Mercury's magnetopause and bow shock from orbital observations by the MESSENGER Magnetometer. We fit empirical models to midpoints of boundary crossings and probability density maps of the magnetopause and bow shock positions. The magnetopause was fit by a surface for which the position R from the planetary dipole varies as [1 + cos(θ)]-α, where θ is the angle between R and the dipole-Sun line, the subsolar standoff distance Rss is 1.45 RM (where RM is Mercury's radius), and the flaring parameter α = 0.5. The average magnetopause shape and location were determined under a mean solar wind ram pressure PRam of 14.3 nPa. The best fit bow shock shape established under an average Alfvén Mach number (MA) of 6.6 is described by a hyperboloid having Rss = 1.96 RM and an eccentricity of 1.02. These boundaries move as PRam and MA vary, but their shapes remain unchanged. The magnetopause Rss varies from 1.55 to 1.35 RM for PRam in the range of 8.8-21.6 nPa. The bow shock Rss varies from 2.29 to 1.89 RM for MA in the range of 4.12-11.8. The boundaries are well approximated by figures of revolution. Additional quantifiable effects of the interplanetary magnetic field are masked by the large dynamic variability of these boundaries. The magnetotail surface is nearly cylindrical, with a radius of ~2.7 RM at a distance of 3 RM downstream of Mercury. By comparison, Earth's magnetotail flaring continues until a downstream distance of ~10 Rss.

  10. Reference surfaces of the planet Mercury from MESSENGER

    NASA Astrophysics Data System (ADS)

    Karimi, Roohollah; Ardalan, Alireza A.; Farahani, Soheil Vasheghani

    2016-01-01

    The aim of this work is to study the reference surfaces of the planet Mercury obtained by the MESSENGER mission in order to provide a geodetic reference system (GRS) for the planet. The reference surfaces under consideration are the geoid and the reference ellipsoid. The reference ellipsoid is a triaxial planetocentric equipotential ellipsoid that best fits the geoid. To determine the reference surfaces, two methods are presented. In this line, the shape of the planet is sampled by expanding the global shape model (GSM) GTMES_125V03_SHA only up to the degree strength of the global gravity model (GGM) GGMES_50V06_SHA. The spatial resolution of the sampling points is selected based on the degree strength and the latitude of the location. According to our preferred method, we estimate the values for the semi-major equatorial axis, semi-minor equatorial axis, and polar axis of the reference ellipsoid equal to 2, 439, 422 ± 368m , 2, 439, 304 ± 368m , and 2, 439, 178 ± 368m , respectively. Moreover, we estimate the geoid potential value equal to 9, 032, 044 ± 1361m2 /s2 . The three axes of the reference ellipsoid give the polar and equatorial flattenings equal to (100 ± 213) ×10-6 and (48 ± 213) ×10-6 , respectively. However, we show that the best-fitting ellipsoid gives the polar and equatorial flattenings equal to (896 ± 213) ×10-6 and (426 ± 213) ×10-6 , respectively. The best-fitting ellipsoid is a triaxial ellipsoid that fits the shape of Mercury in a least-squares sense. The significant discrepancy observed between the flattenings of the two ellipsoids is a consequence of Mercury's geophysical characteristics together with its non-hydrostatic equilibrium. The results provided in the present work prove adequate for defining a promised GRS for the planet Mercury.

  11. Survival Strategies in the Aquatic and Terrestrial World: The Impact of Second Messengers on Cyanobacterial Processes

    PubMed Central

    Agostoni, Marco; Montgomery, Beronda L.

    2014-01-01

    Second messengers are intracellular substances regulated by specific external stimuli globally known as first messengers. Cells rely on second messengers to generate rapid responses to environmental changes and the importance of their roles is becoming increasingly realized in cellular signaling research. Cyanobacteria are photooxygenic bacteria that inhabit most of Earth’s environments. The ability of cyanobacteria to survive in ecologically diverse habitats is due to their capacity to adapt and respond to environmental changes. This article reviews known second messenger-controlled physiological processes in cyanobacteria. Second messengers used in these systems include the element calcium (Ca2+), nucleotide-based guanosine tetraphosphate or pentaphosphate (ppGpp or pppGpp, represented as (p)ppGpp), cyclic adenosine 3’,5’-monophosphate (cAMP), cyclic dimeric GMP (c-di-GMP), cyclic guanosine 3’,5’-monophosphate (cGMP), and cyclic dimeric AMP (c-di-AMP), and the gaseous nitric oxide (NO). The discussion focuses on processes central to cyanobacteria, such as nitrogen fixation, light perception, photosynthesis-related processes, and gliding motility. In addition, we address future research trajectories needed to better understand the signaling networks and cross talk in the signaling pathways of these molecules in cyanobacteria. Second messengers have significant potential to be adapted as technological tools and we highlight possible novel and practical applications based on our understanding of these molecules and the signaling networks that they control. PMID:25411927

  12. 29 CFR 520.407 - What is the subminimum wage for messengers and what must I do to comply with the terms of my...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false What is the subminimum wage for messengers and what must I... CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.407 What is the subminimum wage for messengers and...

  13. 29 CFR 520.407 - What is the subminimum wage for messengers and what must I do to comply with the terms of my...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false What is the subminimum wage for messengers and what must I... CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.407 What is the subminimum wage for messengers and...

  14. 29 CFR 520.407 - What is the subminimum wage for messengers and what must I do to comply with the terms of my...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false What is the subminimum wage for messengers and what must I... CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.407 What is the subminimum wage for messengers and...

  15. 29 CFR 520.407 - What is the subminimum wage for messengers and what must I do to comply with the terms of my...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false What is the subminimum wage for messengers and what must I... CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.407 What is the subminimum wage for messengers and...

  16. 29 CFR 520.407 - What is the subminimum wage for messengers and what must I do to comply with the terms of my...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false What is the subminimum wage for messengers and what must I... CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.407 What is the subminimum wage for messengers and...

  17. Evolution and structure of Mercury's interior from MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Tosi, Nicola

    2015-04-01

    During the past four years, the MESSENGER mission (MErcury Surface, Space Environment, GEochemistry and Ranging) has delivered a wealth of information that has been dramatically advancing the understanding of the geological, chemical, and physical state of Mercury. Taking into account the latest constraints on the interior structure, surface composition, volcanic and tectonic history, we employed numerical models to simulate the thermo-chemical evolution of the planet's interior [1]. Typical evolution scenarios that allow the observational constraints to be satisfied consist of an initial phase of mantle heating accompanied by planetary expansion and the production of a substantial amount of partial melt. The evolution subsequent to 2 Ga is characterised by secular cooling that proceeds approximately at a constant rate and implies that contraction should be still ongoing. Most of the models also predict mantle convection to cease after 3-4 Ga, indicating that Mercury may be no longer dynamically active. In addition, the topography, measured by laser altimetry and the gravity field, obtained from radio-tracking, represent fundamental observations that can be interpreted in terms of the chemical and mechanical structure of the interior. The observed geoid-to-topography ratios at intermediate wavelengths are well explained by the isostatic compensation of the topography associated with lateral variations of the crustal thickness, whose mean value can be estimated to be ~35 km, broadly confirming the predictions of the evolution simulations [2]. Finally, we will show that the degree-2 and 4 of the topography and geoid spectra can be explained in terms of the long-wavelength deformation of the lithosphere resulting from deep thermal anomalies caused by the large latitudinal and longitudinal variations in temperature experienced by Mercury's surface. [1] Tosi N., M. Grott, A.-C. Plesa and D. Breuer (2013). Thermo-chemical evolution of Mercury's interior. Journal of

  18. Mercury's magnetopause and bow shock from MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Winslow, R. M.; Anderson, B. J.; Johnson, C. L.; Slavin, J. A.; Korth, H.; Purucker, M. E.; Baker, D. N.; Solomon, S. C.

    2012-12-01

    We establish the time-averaged shape and location of Mercury's magnetopause and bow shock from orbital observations by the MESSENGER Magnetometer. We fit empirical models to the midpoints of boundary crossings as well as to probability density maps of the magnetopause and bow shock positions. The magnetopause is fit by two different surfaces: (1) a paraboloid, and (2) a surface for which the position R from the planetary dipole varies as [1+cos(θ)]-α, where θ is the angle between R and the dipole-Sun line, and α is a flaring parameter that governs whether the magnetotail is closed (α < 0.5) or open (α ≥ 0.5). The paraboloid magnetopause model is not able to fit simultaneously both the dayside and nightside magnetopause crossings, but the second surface gives the best-fit overall shape to the observations with a subsolar stand-off distance, Rss, of 1.45 RM (where RM is Mercury's radius), and a flaring parameter α = 0.5. The average magnetopause shape and location were determined under a mean solar wind ram pressure, PRam, of 14.3 nPa. The best-fit bow shock shape established under an average Alfvén Mach number (MA ) of 6.6 is described by a hyperboloid having Rss = 1.96 RM and an eccentricity of 1.02. These boundaries move as PRam and MA vary, but their shape remains unchanged. The magnetopause Rss varies from 1.55 RM to 1.35 RM for PRam in the range 8.8 to 21.6 nPa. The bow shock Rss varies from 2.29 RM to 1.89 RM for MA in the range 4.12 to 11.8. To first order, the boundaries are well approximated by figures of revolution. Additional effects of the interplanetary magnetic field are masked by the large dynamic variability of these boundaries. Despite the moderate average magnetic shear conditions at Mercury, the magnetotail surface is nearly cylindrical, with a radius of ~2.7 RM at a distance 3 RM downstream of Mercury. By comparison, Earth's magnetotail flaring continues until a downstream distance of ~10 Rss. This result may indicate that reconnection

  19. MESSENGER Observations of Internal and External Magnetic Fields at Mercury

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.; Anderson, B. J.; Purucker, M. E.; Alexeev, I. I.; Al Asad, M.; Korth, H.; Phillips, R. J.; Slavin, J. A.; Solomon, S. C.; Winslow, R. M.; Zuber, M. T.

    2011-12-01

    Orbital observations with the Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft allow global-scale modeling of Mercury's internal and external magnetic fields. We use a paraboloid model with a cross-tail current sheet to quantify the external magnetic fields and examine possible origins for any residual long-wavelength signals. Observations inside the magnetosphere extend from ~60°S to 86°N; those below 1000 km altitude are confined to the northern hemisphere, with global coverage in body-fixed longitude and in local time. We use MAG data to constrain the magnetopause sub-solar standoff distance, the dipole tilt and offset along the rotation axis, the tail field, and the distance to the inner edge of the tail current sheet. Additional parameters, including the dipole moment, are constrained by the goodness of fit of the model to the MAG data. Inbound and outbound magnetopause crossings are identified on each magnetosphere pass. The mean magnetopause shape for the first 120 days in orbit is modeled by a paraboloid of revolution having a subsolar standoff distance of 1.4 RM (where RM is Mercury's radius). Observations of Mercury's magnetic equator indicate a southward-directed dipole, offset northward along the rotation axis from the planetary center by 484 km, with a tilt of less than 2.5°. These observations constrain the dipole moment to be 195 ± 10 nT-RM3. The paraboloid model successfully matches the first-order global signature of the field, with residual amplitudes typically less than 50 nT. Residuals contain signatures from several different sources: (1) variations in the long-wavelength field that are slow relative to the magnetospheric transit time and which correspond to differences in the baseline magnetospheric currents; (2) multipolar contributions to the internal field of either core or crustal origin; (3) plasma and current systems within the magnetosphere that are not captured in the

  20. MESSENGER Education and Public Outreach Arranges a Ride to the Innermost Planet

    NASA Astrophysics Data System (ADS)

    Weir, H. M.; Chapman, C. R.; Edmonds, J.; Goldstein, J.; Hallau, K. G.; Hirshon, B.; Vanhala, H.; Solomon, S. C.; Messenger Education; Public Outreach Team

    2010-12-01

    Exploration of the mysterious planet Mercury offers an unprecedented opportunity for teachers, students, and citizens to tag along for the ride, and the Education and Public Outreach (EPO) Team for MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is making sure the public gets quite a show. Since 2004, when MESSENGER was launched, MESSENGER has been gathering intriguing data and information about the Solar System's innermost planet. That journey will continue at a quickened pace after March 18, 2011, when MESSENGER enters into orbit around Mercury for one year of observations of the planet and its environment. The EPO Team - an extensive network of individuals and institutions - has sought to convey the excitement and complexity of the mission as MESSENGER's team overcomes challenges, achieves triumphs, and shares the adventure of space exploration with the American and global public. The EPO Team has developed a broad and comprehensive set of educational and outreach activities, ranging from curricular materials, teacher training, and unique mission-related student investigations to museum displays and special outreach to underserved communities and minority students. One of the most visible aspects of this effort is the MESSENGER Educator Fellows program: master science educators who conduct teacher training workshops throughout the nation for pre-K-12 educators. Educator Fellows train teachers on the EPO Team's MESSENGER Education Modules, which are also relevant to other NASA missions reaching important milestones this year (see http://www.messenger-education.org/teachers/educ_modules.php). By the time MESSENGER goes into orbit, Educator Fellows will have trained an estimated 18,000 teachers, who in turn, facilitate classroom experiences to over 1.8 million students. The EPO Team comprises individuals from the American Association for the Advancement of Science (AAAS); Carnegie Academy for Science Education (CASE); Center for

  1. Bacterial Signal Transduction by Cyclic Di-GMP and Other Nucleotide Second Messengers

    PubMed Central

    Gründling, Angelika; Jenal, Urs; Ryan, Robert; Yildiz, Fitnat

    2015-01-01

    The first International Symposium on c-Di-GMP Signaling in Bacteria (22 to 25 March 2015, Harnack-Haus, Berlin, Germany) brought together 131 molecular microbiologists from 17 countries to discuss recent progress in our knowledge of bacterial nucleotide second messenger signaling. While the focus was on signal input, synthesis, degradation, and the striking diversity of the modes of action of the current second messenger paradigm, i.e., cyclic di-GMP (c-di-GMP), “classics” like cAMP and (p)ppGpp were also presented, in novel facets, and more recent “newcomers,” such as c-di-AMP and c-AMP-GMP, made an impressive appearance. A number of clear trends emerged during the 30 talks, on the 71 posters, and in the lively discussions, including (i) c-di-GMP control of the activities of various ATPases and phosphorylation cascades, (ii) extensive cross talk between c-di-GMP and other nucleotide second messenger signaling pathways, and (iii) a stunning number of novel effectors for nucleotide second messengers that surprisingly include some long-known master regulators of developmental pathways. Overall, the conference made it amply clear that second messenger signaling is currently one of the most dynamic fields within molecular microbiology, with major impacts in research fields ranging from human health to microbial ecology. PMID:26055111

  2. Mid-year Status of MESSENGER SciBox Science Planning and Commanding

    NASA Astrophysics Data System (ADS)

    Nguyen, L.; Choo, T. H.; Steele, R. J.; Lucks, M.; Nair, H.; Perry, M. E.; Anderson, B. J.; Berman, A. F.; Solomon, S. C.

    2011-12-01

    More than halfway into its primary orbital mission, MESSENGER has successfully exploited the SciBox planning and commanding system to automate science observation scheduling and command generation for its full instrument suite, as well as its radio-frequency communication and guidance and control systems. MESSENGER's SciBox software coordinates instrument observations to determine the optimal conflict-free science schedule for the entire orbital mission and generates weekly command sequences for submission to mission operations. SciBox maximizes science return by filling all available observing opportunities and fully utilizing onboard storage and downlink bandwidth. As of four months into its one-year orbital mission, MESSENGER SciBox had scheduled the acquisition and downlink of nearly 40,000 images and comparable data sets from the spacecraft's six other instruments. The flexibility of MESSENGER SciBox allows for rapid re-optimization of schedules in the event of unforeseen circumstances. It has also allowed the science and planning teams to analyze rapidly the effects of modifying operational parameters and adding new observations. Within two hours, the entire mission can be re-optimized, schedules and command sequences generated, and a full set of plots and reports produced. The effects on resource usage, observational coverage, and compliance with operational constraints may be quickly assessed. This rapid turnaround ensures that optimal schedules are produced regardless of circumstances. We present an overview of the MESSENGER SciBox design and its operation.

  3. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus: A Dual Spacecraft Study

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Acuna, M. H.; Anderson, B. J.; Barabash, S.; Benna, M.; Boardsen, S. A.; Fraenz, M.; Gloeckler, G.; Gold, R. E.; Ho, G. C.; Korth, H.; Krimigis, S. M.; McNutt, R. L., Jr.; Raines, J. M.; Sarantos, M.; Solomon, S. C.; Zhang, T.; Zurbuchen, T. H.

    2007-01-01

    At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 krn) during its second flyby of Venus en route to its 201 1 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. Pioneer Venus Orbiter measurements have shown that this interaction affects the upper atmosphere and ionosphere down to altitudes of - 150 km. Here we present an initial overview of the MESSENGER observations during the - 4 hrs that the spacecraft spent within 10 planet radii of Venus and, together with Venus Express measurements, examine the influence of solar wind plasma and interplanetary magnetic field conditions on the solar wind interaction at solar minimum.

  4. Involvement of the second messenger cAMP in gravity-signal transduction in physarum

    NASA Astrophysics Data System (ADS)

    Block, I.; Rabien, H.; Ivanova, K.

    The aim of the investigation was to clarify, whether cellular signal processing following graviperception involves second messenger pathways. The test object was a most gravisensitive free-living ameboid cell, the myxomycete (acellular slime mold) Physarum polycephalum. It was demonstrated that the motor response is related to acceleration-dependent changes in the levels of the cellular second messenger cyclic adenosine monophosphate (cAMP). Rotating Physarum plasmodia in the gravity field of the Earth about a horizontal axis increased their cAMP concentration. Depriving the cells for a few days of the acceleration stimulus (near weightlessness in a space experiment on STS-69) slightly lowered plasmodial cAMP levels. Thus, the results provide first indications that the acceleration-stimulus signal transduction chain of Physarum uses an ubiquitous second messenger pathway.

  5. Nuclear networking fashions pre-messenger RNA and primary microRNA transcripts for function

    PubMed Central

    Pawlicki, Jan M.; Steitz, Joan A.

    2010-01-01

    The expression of protein-coding genes is enhanced by the exquisite coupling of transcription by RNA polymerase II with pre-messenger RNA processing reactions, such as 5′-end capping, splicing and 3′-end formation. Integration between cotranscriptional processing events extends beyond the nucleus, as proteins that bind cotranscriptionally can affect the localization, translation and degradation of the mature messenger RNA. MicroRNAs are RNA polymerase II transcripts with crucial roles in the regulation of gene expression. Recent data demonstrate that processing of primary microRNA transcripts might be yet another cotranscriptional event that is woven into this elaborate nuclear network. This review discusses the extensive molecular interactions that couple the earliest steps in gene expression and therefore influence the final fate and function of the mature messenger RNA or microRNA produced. PMID:20004579

  6. TIPE3 Is The Transfer Protein Of Lipid Second Messengers That Promote Cancer

    PubMed Central

    Fayngerts, Svetlana A.; Wu, Jianping; Oxley, Camilla L.; Liu, Xianglan; Vourekas, Anastassios; Cathopoulis, Terry; Wang, Zhaojun; Cui, Jian; Liu, Suxia; Sun, Honghong; Lemmon, Mark A.; Zhang, Lining

    2014-01-01

    Summary More than half of human cancers have aberrantly upregulated phosphoinositide signals; yet how phospholipid signals are controlled during tumorigenesis is not fully understood. We report here that TIPE3 (TNFAIP8L3) is the transfer protein of phosphoinositide second messengers that promote cancer. High-resolution crystal structure of TIPE3 shows a large hydrophobic cavity that is occupied by a phospholipid-like molecule. TIPE3 preferentially captures and shuttles two lipid second messengers, i.e., phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate, and increases their levels in the plasma membrane. Importantly, human cancers have markedly upregulated TIPE3 expression. Knocking out TIPE3 diminishes tumorigenesis whereas enforced TIPE3 expression enhances it in vivo. Thus, the function and metabolism of phosphoinositide second messengers are controlled by a specific transfer protein during tumorigenesis. PMID:25242044

  7. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Acuna, Mario H.; Anderson, Brian J.; Barabash, Stas; Benna, Mehdi; Boardsen, Scott A.; Fraenz, Markus; Gloeckler, George; Gold, Robert E.; Ho,George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Raines, Jim M.; Sarantos, Menelaos; Solomon, Sean C.; Zhang, Tielong; Zurbuchen, Thomas H.

    2009-01-01

    At 23:08 UTC on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude of 338 kin during its final flyby of Venus en route to its 2011 orbit insertion at Mercury. The availability of the simultaneous Venus Express solar wind and interplanetary magnetic field measurements provides a rare opportunity to examine the influence of upstream conditions on this planet's solar wind interaction. We present MESSENGER observations of new features of the Venus - solar wind interaction including hot flow anomalies upstream of the bow shock, a flux rope in the near-tail and a two-point determination of the timescale for magnetic flux transport through this induced magnetosphere. Citation: Stavin, J. A., et al. (2009), MESSENGER and Venus Express observations of the solar wind interaction with Venus,

  8. The gravity field and orientation of Mercury after the MESSENGER mission

    NASA Astrophysics Data System (ADS)

    Mazarico, E.; Genova, A.; Goossens, S. J.; Lemoine, F. G.; Neumann, G. A.; Zuber, M. T.; Smith, D. E.; Solomon, S. C.

    2015-12-01

    After more than four years in orbit about Mercury, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft impacted the planet's surface north of Shakespeare crater (54.44° N, 210.12° E,) on 30 April 2015. One of the main goals of the mission was to determine the gravity field of Mercury in order to learn about Mercury's interior. Together with ground-based radar measurements of the obliquity and forced librations, MESSENGER-derived gravity models helped revise models of Mercury's interior. Nevertheless, the refinement of Mercury's orientation with the latest data from MESSENGER can further improve the interior modeling of the planet. The last eight months of the mission provided a special opportunity to conduct low-altitude measurements, with extensive radio tracking coverage below 200 km altitude north of ~30°N. MESSENGER's Mercury Laser Altimeter (MLA) mapped the topography of Mercury's northern hemisphere with a sub-meter vertical precision, an along-track sampling of ~500 m, and a longitudinal resolution (~0.1°) limited by the number of spacecraft orbits (~4,000). The combination of gravity and topography helps determine crustal thickness and interior properties. Altimetric ranges provide geodetic constraints to improve the spacecraft orbit determination, and thus the gravity field model. In particular, whereas the MESSENGER spacecraft was not tracked at each periapsis passage, MLA operated nearly continuously (outside of thermally challenging periods). From an analysis of the entire radiometric and altimetric datasets acquired by MESSENGER, a new gravity field to degree and order 100 has been obtained, resolving features down to ~75 km horizontal scale. The altimetric data help reduce the uncertainties in the determination of the pole position. A reanalysis of the Mercury flybys also constrains the spin rate over the longest available time span.

  9. Astronomy's New Messengers: A traveling exhibit on gravitational-wave physics

    NASA Astrophysics Data System (ADS)

    Cavaglià, Marco; Hendry, Martin; Márka, Szabolcs; Reitze, David H.; Riles, Keith

    2010-01-01

    The Laser Interferometer Gravitational-wave Observatory exhibit Astronomy's New Messengers: Listening to the Universe with Gravitational Waves is traveling to colleges, universities, museums and other public institutions throughout the United States. Astronomy's New Messengers primarily communicates with an adolescent and young adult audience, potentially inspiring them into the field of science. Acknowledging that this audience is traditionally a difficult one to attract, the exhibit publicly announces itself in a charismatic fashion to reach its principal goals of broadening the community of people interested in science and encouraging interest in science among young people.

  10. Linking the Universe to the Community: Students as Starry Messengers for IYA2009---Puerto Rico

    NASA Astrophysics Data System (ADS)

    Pantoja, C. A.; Lebrón Santos, M. E.

    2008-11-01

    This poster presents a project to establish a working team of undergraduate students (``Starry Messengers'') to promote and experience the wonders of space science and education with all the senses. The students are expected to assist during the activities of the IYA2009. During 2008 the students will receive the appropriate instruction on observational astronomy through two workshops. An innovative model of inclusion will be developed, adapting all materials to include the visually impaired. We will encourage the participation of at least one visually impaired student or teacher on the Starry Messenger team. The workshops will serve as templates for future K--12 teacher workshops.

  11. Solid-phase synthesis of branched oligoribonucleotides related to messenger RNA splicing intermediates.

    PubMed Central

    Damha, M J; Ganeshan, K; Hudson, R H; Zabarylo, S V

    1992-01-01

    The chemical synthesis of oligoribonucleotides containing vicinal (2'-5')- and (3'-5')-phosphodiester linkages is described. The solid-phase method, based on silyl-phosphoramidite chemistry, was applied to the synthesis of a series of branched RNA [(Xp)nA2' (pN)n3'(pN)n] related to the splicing intermediates derived from Saccharomyces cerevisiae rp51a pre-messenger RNA. The branched oligonucleotides have been thoroughly characterized by nucleoside and branched nucleotide composition analysis. Branched oligoribonucleotides will be useful in the study of messenger RNA splicing and in determining the biological role of RNA 'lariats' and 'forks' in vivo. Images PMID:1480476

  12. Mercury's Exosphere During MESSENGER's Second Flyby: Detection of Magnesium and Distinct Distributions of Neutral Species

    NASA Technical Reports Server (NTRS)

    McClintock, William E.; Vervack, Ronald J., Jr.; Bradley, E. Todd; Killen, Rosemary M.; Mouawad, Nelly; Sprague, Ann L.; Burger, Matthew H.; Solomon, Sean C.; Izenberg, Noam R.

    2009-01-01

    During MESSENGER's second Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer observed emission from Mercury's neutral exosphere. These observations include the first detection of emission from magnesium. Differing spatial distributions for sodium, calcium, and magnesium were revealed by observations beginning in Mercury's tail region, approximately 8 Mercury radii anti-sunward of the planet, continuing past the nightside, and ending near the dawn terminator. Analysis of these observations, supplemented by observations during the first Mercury flyby as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes.

  13. [Valutazione delle guardie di sicurezza privata attraverso la Suicide Probability Scale e la Brief Symptom Inventory].

    PubMed

    Dogan, Bulent; Canturk, Gurol; Canturk, Nergis; Guney, Sevgi; Özcan, Ebru

    2016-01-01

    RIASSUNTO. Scopo. Lo scopo di questo studio è stato quello di investigare l'influenza della probabilità di suicidio, con le sue caratteristiche sociodemografiche, e di procurare i dati per la prevenzione del suicidio tra le guardie di sicurezza privata che lavorano in condizioni di stress, essendo a contatto ininterrottamente con eventi negativi e traumatici di vita durante il loro lavoro. Metodi. Hanno partecipato allo studio 200 guardie di sicurezza privata e 200 persone dell'Università di Ankara. Per raccogliere i dati sono stati utilizzati un questionario riguardante le condizioni sociodemografiche dei partecipanti, la Suicide Probability Scale (SPS) e la Brief Symptom Inventory (BSI). Risultati. Genere, stato civile, stipendio, credenze religiose, vivere una situazione di pericolo di vita, passato di tentativi di suicidio, fumare e non avere una malattia cronica hanno causato statisticamente una differenza significativa sui punteggi di SPS tra il gruppo di guardie di sicurezza privata e quello di controllo. In aggiunta, c'è stata una correlazione positiva statisticamente significativa tra i punteggi totali delle sottoscale di SPS e quelli di BSI. Conclusioni. Allo stesso modo degli agenti di polizia e dei gendarmi, le guardie di sicurezza privata sono ad alto rischio di commettere e tentare il suicidio trovandosi in condizioni stressanti di lavoro e anche soffrendo del trauma secondario. È necessario che essi siano consapevoli della propria tendenza al suicidio e avere controlli psichiatrici regolari.

  14. Students Engaging the Public in Exciting Discoveries by NASA's MESSENGER Mission

    NASA Astrophysics Data System (ADS)

    Hallau, K. G.; Morison, J.; Schuele, H.

    2012-12-01

    In March 2011, NASA's MESSENGER spacecraft entered into orbit around Mercury, the closest planet to the Sun. As the first mission to orbit and study Mercury in depth, MESSENGER sought to answer six primary scientific questions: why is Mercury so dense; what is the geologic history of Mercury; what is the nature of Mercury's magnetic field; what is the structure of Mercury's core; what are the unusual materials at Mercury's poles; and what volatiles are important at Mercury? In the first year of orbit, MESSENGER answered all of these questions, and also made several surprising discoveries. Student interns working with the MESSENGER Education and Public Outreach (EPO) team are using MESSENGER Mosaic Postcards (MPC) in both print and digital formats to present this new information to a broad audience. These MPCs, in conjunction with the rest of the MESSENGER EPO tools, present a unified and global resource for the public. By creating this resource in a variety of media, from printable cards to interactive features on the EPO website (http://www.messenger-education.org/), the EPO team can reach a larger audience, further the goal of the MPC project to share newly discovered features and phenomena with the general public, and thereby generate increased interest in and excitement about science and planetary exploration. One side of each MPC shows a MESSENGER image of a portion of Mercury's surface, and together the postcards can be arranged to form a complete image of the planet. On the reverse side of some cards is information pertaining to an item of interest in view on the image-side. One of us (physics undergraduate JEM) researches interesting features on the surface of Mercury and creates descriptions for the informational side of the postcards, and another (computer science undergraduate HCS) creates the digital versions of cards and associated resources for the Surface Interactive, an interactive tool on the MESSENGER EPO website. Postcards already in distribution

  15. μ and κ Opioid Receptors Activate ERK/MAPK via Different Protein Kinase C Isoforms and Secondary Messengers in Astrocytes*

    PubMed Central

    Belcheva, Mariana M.; Clark, Amy L.; Haas, Paul D.; Serna, Jannie S.; Hahn, Jason W.; Kiss, Alexi; Coscia, Carmine J.

    2005-01-01

    Acute μ and κ opioids activate the ERK/MAPK phosphorylation cascade that represents an integral part of the signaling pathway of growth factors in astrocytes. By this cross-talk, opioids may impact neural development and plasticity among other basic neurobiological processes in vivo. The μ agonist, [D-ala2, mephe4, gly-ol5]enkephalin (DAMGO), induces a transient stimulation of ERK phosphorylation, whereas κ agonist, U69,593, engenders sustained ERK activation. Here we demonstrate that acute U69,593 and DAMGO stimulate ERK phosphorylation by utilization of different secondary messengers and protein kinase C (PKC) isoforms upstream of the growth factor pathway. Immortalized astrocytes transfected with either antisense calmodulin (CaM), a mutant μ opioid receptor that binds CaM poorly or a dominant negative mutant of PKCε were used as a model system to study μ signaling. Evidence was gained to implicate CaM and PKCε in DAMGO stimulation of ERK. DAMGO activation of PKCε and/or ERK was insensitive to selective inhibitors of Ca2+ mobilization, but it was blocked upon phospholipase C inhibition. These results suggest a novel mechanism wherein, upon DAMGO binding, CaM is released from the μ receptor and activates phospholipase C. Subsequently, phospholipase C generates diacylglycerides that activate PKCε. In contrast, U69,593 appears to act via phosphoinositide 3-kinase, PKCζ, and Ca2+ mobilization. These signaling components were implicated based on studies with specific inhibitors and a dominant negative mutant of PKCζ. Collectively, our findings on acute opioid effects suggest that differences in their mechanism of signaling may contribute to the distinct outcomes on ERK modulation induced by chronic μ and κ opioids. PMID:15944153

  16. Viewing Indians: Native Encounters with Power, Tourism, and the Camera in the Wisconsin Dells, 1866-1907

    ERIC Educational Resources Information Center

    Hoelscher, Steven

    2003-01-01

    In the winter of 1883, the photographer H. H. Bennett decided to spice up his descriptive catalogue of stereo views with something new. Several years earlier, a simple listing of his photographs--mostly landscape views of the area surrounding the Wisconsin River Dells--brought the small-town studio photographer considerable renown and enhanced…

  17. Viewing Indians: Native Encounters with Power, Tourism, and the Camera in the Wisconsin Dells, 1866-1907

    ERIC Educational Resources Information Center

    Hoelscher, Steven

    2003-01-01

    In the winter of 1883, the photographer H. H. Bennett decided to spice up his descriptive catalogue of stereo views with something new. Several years earlier, a simple listing of his photographs--mostly landscape views of the area surrounding the Wisconsin River Dells--brought the small-town studio photographer considerable renown and enhanced…

  18. Reach a New Threshold of Freedom and Control with Dell's Flexible Computing Solution: On-Demand Desktop Streaming

    ERIC Educational Resources Information Center

    Technology & Learning, 2008

    2008-01-01

    When it comes to IT, there has always been an important link between data center control and client flexibility. As computing power increases, so do the potentially crippling threats to security, productivity and financial stability. This article talks about Dell's On-Demand Desktop Streaming solution which is designed to centralize complete…

  19. Reach a New Threshold of Freedom and Control with Dell's Flexible Computing Solution: On-Demand Desktop Streaming

    ERIC Educational Resources Information Center

    Technology & Learning, 2008

    2008-01-01

    When it comes to IT, there has always been an important link between data center control and client flexibility. As computing power increases, so do the potentially crippling threats to security, productivity and financial stability. This article talks about Dell's On-Demand Desktop Streaming solution which is designed to centralize complete…

  20. Realising effective theories of tribrid inflation: are there effects from messenger fields?

    NASA Astrophysics Data System (ADS)

    Antusch, Stefan; Nolde, David

    2015-09-01

    Tribrid inflation is a variant of supersymmetric hybrid inflation in which the inflaton is a matter field (which can be charged under gauge symmetries) and inflation ends by a GUT-scale phase transition of a waterfall field. These features make tribrid inflation a promising framework for realising inflation with particularly close connections to particle physics. Superpotentials of tribrid inflation involve effective operators suppressed by some cutoff scale, which is often taken as the Planck scale. However, these operators may also be generated by integrating out messenger superfields with masses below the Planck scale, which is in fact quite common in GUT and/or flavour models. The values of the inflaton field during inflation can then lie above this mass scale, which means that for reliably calculating the model predictions one has to go beyond the effective theory description. We therefore discuss realisations of effective theories of tribrid inflation and specify in which cases effects from the messenger fields are expected, and under which conditions they can safely be neglected. In particular, we point out how to construct realisations where, despite the fact that the inflaton field values are above the messenger mass scale, the predictions for the observables are (to a good approximation) identical to the ones calculated in the effective theory treatment where the messenger mass scale is identified with the (apparent) cutoff scale.

  1. Integrating Instant Messenger into Online Office Hours to Enhance Synchronous Online Interaction in Teacher Education

    ERIC Educational Resources Information Center

    Lih-Ching, Chen Wang; Beasley, William

    2006-01-01

    Modern communication technologies have modified the tradition of instructor's office hours in numerous ways. This article explores the use of Instant Messenger (IM) software in the context of "online office hours". The authors discuss strengths and weaknesses of IM interactions for instructor/student communication, and examine a sample of such…

  2. Audience and Witnessing: Research into Dramatherapy using Vignettes and aMSN Messenger

    ERIC Educational Resources Information Center

    Jones, Phil

    2008-01-01

    This article describes the process of research undertaken to examine therapists' responses to the concept of the core processes of change in dramatherapy. The research uses a combination of vignette description and analysis using aMSN messenger. The article describes the theoretical underpinning and rationale to the approach, and the…

  3. Social and Virtual Networks: Evaluating Synchronous Online Interviewing Using Instant Messenger

    ERIC Educational Resources Information Center

    Hinchcliffe, Vanessa; Gavin, Helen

    2009-01-01

    This paper describes an evaluation of the quality and utility of synchronous online interviewing for data collection in social network research. Synchronous online interviews facilitated by Instant Messenger as the communication medium, were undertaken with ten final year university students. Quantitative and qualitative content analysis of…

  4. Shoot the Messenger and Disregard the Message? Children's Attitudes toward Spelling.

    ERIC Educational Resources Information Center

    Varnhagen, Connie K.

    2000-01-01

    Assesses children's attitudes toward spelling using a person perception paradigm. Indicates that even second graders had a negative attitude toward both the message and the messenger as a function of misspellings, and that children's negative attitudes increased across grades. Finds that attitude was related to spelling ability; better…

  5. Realising effective theories of tribrid inflation: are there effects from messenger fields?

    SciTech Connect

    Antusch, Stefan; Nolde, David E-mail: david.nolde@unibas.ch

    2015-09-01

    Tribrid inflation is a variant of supersymmetric hybrid inflation in which the inflaton is a matter field (which can be charged under gauge symmetries) and inflation ends by a GUT-scale phase transition of a waterfall field. These features make tribrid inflation a promising framework for realising inflation with particularly close connections to particle physics. Superpotentials of tribrid inflation involve effective operators suppressed by some cutoff scale, which is often taken as the Planck scale. However, these operators may also be generated by integrating out messenger superfields with masses below the Planck scale, which is in fact quite common in GUT and/or flavour models. The values of the inflaton field during inflation can then lie above this mass scale, which means that for reliably calculating the model predictions one has to go beyond the effective theory description. We therefore discuss realisations of effective theories of tribrid inflation and specify in which cases effects from the messenger fields are expected, and under which conditions they can safely be neglected. In particular, we point out how to construct realisations where, despite the fact that the inflaton field values are above the messenger mass scale, the predictions for the observables are (to a good approximation) identical to the ones calculated in the effective theory treatment where the messenger mass scale is identified with the (apparent) cutoff scale.

  6. Recognition of the bacterial second messenger cyclic diguanylate by its cognate riboswitch

    SciTech Connect

    Kulshina, Nadia; Baird, Nathan J.; Ferré-D'Amaré, Adrian R.

    2009-12-03

    The cyclic diguanylate (bis-(3'-5')-cyclic dimeric guanosine monophosphate, c-di-GMP) riboswitch is the first known example of a gene-regulatory RNA that binds a second messenger. c-di-GMP is widely used by bacteria to regulate processes ranging from biofilm formation to the expression of virulence genes. The cocrystal structure of the c-di-GMP responsive GEMM riboswitch upstream of the tfoX gene of Vibrio cholerae reveals the second messenger binding the RNA at a three-helix junction. The two-fold symmetric second messenger is recognized asymmetrically by the monomeric riboswitch using canonical and noncanonical base-pairing as well as intercalation. These interactions explain how the RNA discriminates against cyclic diadenylate (c-di-AMP), a putative bacterial second messenger. Small-angle X-ray scattering and biochemical analyses indicate that the RNA undergoes compaction and large-scale structural rearrangement in response to ligand binding, consistent with organization of the core three-helix junction of the riboswitch concomitant with binding of c-di-GMP.

  7. Corrective Feedback via Instant Messenger Learning Activities in NS-NNS and NNS-NNS Dyads

    ERIC Educational Resources Information Center

    Sotillo, Susana

    2005-01-01

    This exploratory study examines corrective feedback in native speaker-nonnative speaker (NS-NNS) and NNS-NNS dyads while participants were engaged in communicative and problem-solving activities via "Yahoo! Instant Messenger" (YIM). As "negotiation of meaning" studies of the 1990s have shown, linguistic items which learners negotiate in…

  8. Radioautographic localization of prolactin messenger RNA on histological sections by in situ hybridization.

    PubMed

    Pochet, R; Brocas, H; Vassart, G; Toubeau, G; Seo, H; Refetoff, S; Dumont, J E; Pasteels, J L

    1981-05-04

    In situ hybridization of complementary [H3]DNA ([H3]cDNA) synthetized from purified rat prolactin messenger RNA (rPRL mRNA) was performed to specifically identify on histologic sections of rat hypophysis cells expressing the PRL gene. Radioautographic labelling occurred over weakly acidophilic cells, while other acidophils, with darker cytoplasm did not contain more silver grains than blood vessels.

  9. The Gravity Field of Mercury After the Messenger Low-Altitude Campaign

    NASA Technical Reports Server (NTRS)

    Mazarico, Erwan; Genova, Antonio; Goossens, Sander; Lemoine, Frank G.; Smith, David E.; Zuber, Maria T.; Neumann, Gary A.; Solomon, Sean C.

    2015-01-01

    The final year of the MESSENGER mission was designed to take advantage of the remaining propellant onboard to provide a series of lowaltitude observation campaigns and acquire novel scientific data about the innermost planet. The lower periapsis altitude greatly enhances the sensitivity to the short-wavelength gravity field, but only when the spacecraft is in view of Earth. After more than 3 years in orbit around Mercury, the MESSENGER spacecraft was tracked for the first time below 200-km altitude on 5 May 2014 by the NASA Deep Space Network (DSN). Between August and October, periapsis passages down to 25-km altitude were routinely tracked. These periods considerably improved the quality of the data coverage. Before the end of its mission, MESSENGER will fly at very low altitudes for extended periods of time. Given the orbital geometry, however the periapses will not be visible from Earth and so no new tracking data will be available for altitudes lower than 75 km. Nevertheless, the continuous tracking of MESSENGER in the northern hemisphere will help improve the uniformity of the spatial coverage at altitudes lower than 150 km, which will further improve the overall quality of the Mercury gravity field.

  10. Social and Virtual Networks: Evaluating Synchronous Online Interviewing Using Instant Messenger

    ERIC Educational Resources Information Center

    Hinchcliffe, Vanessa; Gavin, Helen

    2009-01-01

    This paper describes an evaluation of the quality and utility of synchronous online interviewing for data collection in social network research. Synchronous online interviews facilitated by Instant Messenger as the communication medium, were undertaken with ten final year university students. Quantitative and qualitative content analysis of…

  11. Comparison of methods of extracting messenger Ribonucleic Acid from ejaculated Porcine (Sus Scrofa) Spermatozoa

    USDA-ARS?s Scientific Manuscript database

    H. D. Guthrie, G.R. Welch, and L. A. Blomberg. Comparison of Methods of Extracting Messenger Ribonucleic Acid from Ejaculated Porcine (Sus Scrofa) Spermatozoa. Biotechnology and Germplasm Laboratory, Agricultural Research Service U. S. Department of Agriculture, Beltsville, MD 20705 The purpos...

  12. Corrective Feedback via Instant Messenger Learning Activities in NS-NNS and NNS-NNS Dyads

    ERIC Educational Resources Information Center

    Sotillo, Susana

    2005-01-01

    This exploratory study examines corrective feedback in native speaker-nonnative speaker (NS-NNS) and NNS-NNS dyads while participants were engaged in communicative and problem-solving activities via "Yahoo! Instant Messenger" (YIM). As "negotiation of meaning" studies of the 1990s have shown, linguistic items which learners negotiate in…

  13. Realising effective theories of tribrid inflation: are there effects from messenger fields?

    SciTech Connect

    Antusch, Stefan; Nolde, David

    2015-09-22

    Tribrid inflation is a variant of supersymmetric hybrid inflation in which the inflaton is a matter field (which can be charged under gauge symmetries) and inflation ends by a GUT-scale phase transition of a waterfall field. These features make tribrid inflation a promising framework for realising inflation with particularly close connections to particle physics. Superpotentials of tribrid inflation involve effective operators suppressed by some cutoff scale, which is often taken as the Planck scale. However, these operators may also be generated by integrating out messenger superfields with masses below the Planck scale, which is in fact quite common in GUT and/or flavour models. The values of the inflaton field during inflation can then lie above this mass scale, which means that for reliably calculating the model predictions one has to go beyond the effective theory description. We therefore discuss realisations of effective theories of tribrid inflation and specify in which cases effects from the messenger fields are expected, and under which conditions they can safely be neglected. In particular, we point out how to construct realisations where, despite the fact that the inflaton field values are above the messenger mass scale, the predictions for the observables are (to a good approximation) identical to the ones calculated in the effective theory treatment where the messenger mass scale is identified with the (apparent) cutoff scale.

  14. A Contemporary, Laboratory-Intensive Course on Messenger RNA Transcription and Processing

    ERIC Educational Resources Information Center

    Carson, Sue; Miller, Heather

    2012-01-01

    Messenger ribonucleic acid (mRNA) plays a pivotal role in the central dogma of molecular biology. Importantly, molecular events occurring during and after mRNA synthesis have the potential to create multiple proteins from one gene, leading to some of the remarkable protein diversity that genomes hold. The North Carolina State University…

  15. Farm Women, Solidarity, and "The Suffrage Messenger": Nebraska Suffrage Activism on the Plains, 1915-1917

    ERIC Educational Resources Information Center

    Heider, Carmen

    2012-01-01

    In 1914 Nebraska men once again voted against the amendment that would have granted full suffrage to Nebraska women. This article focuses on the three years immediately after that defeat. It explores the remaining seventeen issues of the "Suffrage Messenger" and asks the following question: how did the suffrage newspaper portray and…

  16. Unit Messengers, First Trial Materials, Inspection Set, [Australian Science Education Project].

    ERIC Educational Resources Information Center

    Australian Council for Educational Research, Hawthorn.

    The Australian Science Education Project is producing material designed for use in grades 7-10 of Australian schools. This is the first trial version of a unit concerned with sight, hearing, touch, taste, and smell. The teacher's guide outlines the use of the two booklets ("Messengers" and "Use of the Senses") intended for all…

  17. Unit Messengers, First Trial Materials, Inspection Set, [Australian Science Education Project].

    ERIC Educational Resources Information Center

    Australian Council for Educational Research, Hawthorn.

    The Australian Science Education Project is producing material designed for use in grades 7-10 of Australian schools. This is the first trial version of a unit concerned with sight, hearing, touch, taste, and smell. The teacher's guide outlines the use of the two booklets ("Messengers" and "Use of the Senses") intended for all…

  18. Farm Women, Solidarity, and "The Suffrage Messenger": Nebraska Suffrage Activism on the Plains, 1915-1917

    ERIC Educational Resources Information Center

    Heider, Carmen

    2012-01-01

    In 1914 Nebraska men once again voted against the amendment that would have granted full suffrage to Nebraska women. This article focuses on the three years immediately after that defeat. It explores the remaining seventeen issues of the "Suffrage Messenger" and asks the following question: how did the suffrage newspaper portray and…

  19. A Contemporary, Laboratory-Intensive Course on Messenger RNA Transcription and Processing

    ERIC Educational Resources Information Center

    Carson, Sue; Miller, Heather

    2012-01-01

    Messenger ribonucleic acid (mRNA) plays a pivotal role in the central dogma of molecular biology. Importantly, molecular events occurring during and after mRNA synthesis have the potential to create multiple proteins from one gene, leading to some of the remarkable protein diversity that genomes hold. The North Carolina State University…

  20. Messenger RNA patterns in rat liver nuclei before and after treat-ment with growth hormone.

    PubMed

    Drews, J; Brawerman, G

    1967-06-09

    Like cortisol, growth hormone enhances RNA synthesis in rat liver nuclei. However, DNA-RNA hybridization experiments show that the application of growth hormone does not stimulate the formation of new species of messenger RNA. The latter phenomenon was observed after treatment with cortisol.

  1. Use of MESSENGER radioscience data to improve planetary ephemeris and to test general relativity

    NASA Astrophysics Data System (ADS)

    Verma, A. K.; Fienga, A.; Laskar, J.; Manche, H.; Gastineau, M.

    2014-01-01

    The current knowledge of Mercury's orbit has mainly been gained by direct radar ranging obtained from the 60s to 1998 and by five Mercury flybys made with Mariner 10 in the 70s, and with MESSENGER made in 2008 and 2009. On March 18, 2011, MESSENGER became the first spacecraft to orbit Mercury. The radioscience observations acquired during the orbital phase of MESSENGER drastically improved our knowledge of the orbit of Mercury. An accurate MESSENGER orbit is obtained by fitting one-and-half years of tracking data using GINS orbit determination software. The systematic error in the Earth-Mercury geometric positions, also called range bias, obtained from GINS are then used to fit the INPOP dynamical modeling of the planet motions. An improved ephemeris of the planets is then obtained, INPOP13a, and used to perform general relativity tests of the parametrized post-Newtonian (PPN) formalism. Our estimations of PPN parameters (γ and β) are more stringent than previous results.

  2. An international program for Mercury exploration: synergy of MESSENGER and BepiColombo

    NASA Astrophysics Data System (ADS)

    McNutt, R.; Solomon, S.; Grard, R.; Novara, M.; Mukai, T.

    Mariner 10 has been the only spacecraft to visit the innermost planet Mercury. Its visits, more than 25 years ago, used three rapid flybys to yield the first view of this little-understood world. With advances in spacecraft technology and a growing realization of how important Mercury is to our understanding of the solar system and its formation, two missions are now in development for more intensive Mercury exploration. The first is the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission, competitively selected under the NASA Discovery Program, that will send a spacecraft to fly by Mercury in 2007 and 2008 and to orbit Mercury for one Earth year beginning in April 2009. The second is the more comprehensive BepiColombo mission, consisting of three elements: the Mercury Planetary Orbiter (MPO), the Mercury Magnetospheric Orbiter (MMO), and the Mercury Surface Element (MSE). Still in final definition stage, BepiColombo is a partnership between the European Space Agency ESA and the Japanese space agency ISAS. With one or two launches (depending upon the final architecture) BepiColombo will use solar electric propulsion to launch two orbiters (MPO from ESA and MMO from ISAS) and a lander (MSE) to Mercury as early as 2009. The BepiColombo orbiters, in orbits complementary to that of MESSENGER, will extend geochemical, spectral, and photometric mapping of the planet. With its factor-of-ten larger downlink, BepiColombo will complete the intensive study of Mercury begun with the exploration by MESSENGER. Synergistic strategies of exploration will enable efficient use of BepiColombo resources in a more detailed study of the planet than can be accomplished by MESSENGER alone. For example, the earlier MESSENGER mission can help identify appropriate landing sites for the MSE, while BepiColombo can provide complementary orbital measurements of surface features from different phase angles and exploit MESSENGER observations to target high

  3. An international program for Mercury exploration: synergy of MESSENGER and BepiColombo

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph L.; Solomon, Sean C.; Grard, Réjean; Novara, Mauro; Mukai, Toshifumi

    2004-01-01

    Mariner 10 has been the only spacecraft to visit the innermost planet Mercury. Its three flybys, more than 25 years ago, yielded the first view of this little-understood world. With advances in spacecraft technology and a growing realization of how important Mercury is to our understanding of the solar system and its formation, two missions are now in development for more intensive Mercury exploration. The first is the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission, competitively selected under the NASA Discovery Program, that will send a spacecraft to fly by Mercury in 2007 and 2008 and to orbit Mercury for one Earth year beginning in April 2009. The second is the more comprehensive BepiColombo mission, consisting of three elements: the Mercury Planetary Orbiter (MPO), the Mercury Magnetospheric Orbiter (MMO), and the Mercury Surface Element (MSE). Still in final definition stage, BepiColombo is a partnership between the European Space Agency (ESA) and the Japanese Institute of Space and Astronautical Science (ISAS). With one or two launches (depending upon the final mission architecture) BepiColombo will use solar electric propulsion to send two orbiters (MPO from ESA and MMO from ISAS) and a lander (MSE) to Mercury as early as 2011. The BepiColombo orbiters, in orbits complementary to that of MESSENGER, will extend geochemical, spectral, and photometric mapping of the planet. With its factor-of-ten larger downlink, BepiColombo will complete the intensive study of Mercury begun with the exploration by MESSENGER. Synergistic strategies of exploration will enable efficient use of BepiColombo resources in a more detailed study of the planet than can be accomplished by MESSENGER alone. For example, the earlier MESSENGER mission can help identify appropriate landing sites for the MSE, while BepiColombo can provide complementary orbital measurements of surface features from different phase angles and exploit MESSENGER observations to

  4. 29 CFR 520.405 - Must I notify my employees that I am applying for a certificate to employ messengers and/or...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... certificate to employ messengers and/or learners at subminimum wages? 520.405 Section 520.405 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.405 Must I notify my employees...

  5. 29 CFR 520.405 - Must I notify my employees that I am applying for a certificate to employ messengers and/or...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... certificate to employ messengers and/or learners at subminimum wages? 520.405 Section 520.405 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.405 Must I notify my employees...

  6. 29 CFR 520.405 - Must I notify my employees that I am applying for a certificate to employ messengers and/or...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... certificate to employ messengers and/or learners at subminimum wages? 520.405 Section 520.405 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.405 Must I notify my employees...

  7. 29 CFR 520.405 - Must I notify my employees that I am applying for a certificate to employ messengers and/or...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... certificate to employ messengers and/or learners at subminimum wages? 520.405 Section 520.405 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.405 Must I notify my employees...

  8. 29 CFR 520.405 - Must I notify my employees that I am applying for a certificate to employ messengers and/or...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... certificate to employ messengers and/or learners at subminimum wages? 520.405 Section 520.405 Labor... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.405 Must I notify my employees...

  9. Engaging the Public in the MESSENGER Spacecraft's Confirmation of Water Ice on Mercury by Using Actual Data

    NASA Astrophysics Data System (ADS)

    Hallau, K.; Chapman, C. R.; Edmonds, J. P.; Goldstein, J. J.; Hamel, S.; Hirshon, B.; Malaret, E.; Nittler, L. R.; Solomon, S. C.; Weir, H. M.

    2013-12-01

    Observations by the MESSENGER spacecraft have provided compelling support for the 20-year-old hypothesis that Mercury hosts abundant water ice and other frozen volatile materials in its permanently shadowed polar craters. MESSENGER's Education and Public Outreach (EPO) team is creating a suite of materials to engage the public in the scientific process that led to this discovery. The Water Ice Data Exploration (WIDE) suite will consist of a video presentation from a mission scientist and engineer, a pencil-and-paper activity, and a web-based interactive data-mapping tool. Each of these individual parts will examine Mariner 10 flyby data from the 1970s, Earth-based radar data from the early 1990s, and MESSENGER flyby and orbital data from various instruments to help show the progression of evidence in support of this conclusion. The QuickMap interactive data mapping tool will be customized for this project and will also serve as an introduction to the larger QuickMap tool, with which publicly released MESSENGER data can be viewed (http://messenger-act.actgate.com/msgr_public_released/react_quickmap.html). The WIDE suite of materials will be accessible from a dedicated HTML page on the MESSENGER EPO website (temporary draft: http://www.messenger-education.org/workshops/cod.php), enabling free and simple dissemination to broad audiences.

  10. Mercury Conditions for the MESSENGER Mission Simulated in High- Solar-Radiation Vacuum Tests

    NASA Technical Reports Server (NTRS)

    Wong, Wayne A.

    2003-01-01

    The MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) spacecraft, planned for launch in March 2004, will perform two flybys of Mercury before entering a year-long orbit of the planet in September 2009. The mission will provide opportunities for detailed characterization of the surface, interior, atmosphere, and magnetosphere of the closest planet to the Sun. The NASA Glenn Research Center and the MESSENGER spacecraft integrator, the Johns Hopkins University Applied Physics Laboratory, have partnered under a Space Act Agreement to characterize a variety of critical components and materials under simulated conditions expected near Mercury. Glenn's Vacuum Facility 6, which is equipped with a solar simulator, can simulate the vacuum and high solar radiation anticipated in Mercury orbit. The MESSENGER test hardware includes a variety of materials and components that are being characterized during the Tank 6 vacuum tests, where the hardware will be exposed to up to 11 suns insolation, simulating conditions expected in Mercury orbit. In 2002, ten solar vacuum tests were conducted, including beginning of life, end of life, backside exposure, and solar panel thermal shock cycling tests. Components tested include candidate solar array panels, sensors, thermal shielding materials, and communication devices. As an example, for the solar panel thermal shock cycling test, two candidate solar array panels were suspended on a lift mechanism that lowered the panels into a liquid-nitrogen-cooled box. After reaching -140 C, the panels were then lifted out of the box and exposed to the equivalent of 6 suns (8.1 kilowatts per square meters). After five cold soak/heating cycles were completed successfully, there was no apparent degradation in panel performance. An anticipated 100-hr thermal shield life test is planned for autumn, followed by solar panel flight qualification tests in winter. Glenn's ongoing support to the MESSENGER program has been instrumental in

  11. Involvement of secondary messengers and small organic molecules in auxin perception and signaling.

    PubMed

    Di, Dong-Wei; Zhang, Caiguo; Guo, Guang-Qin

    2015-06-01

    Auxin is a major phytohormone involved in most aspects of plant growth and development. Generally, auxin is perceived by three distinct receptors: TRANSPORT INHIBITOR RESISTANT1-Auxin/INDOLE ACETIC ACID, S-Phase Kinase-Associated Protein 2A and AUXIN-BINDING PROTEIN1. The auxin perception is regulated by a variety of secondary messenger molecules, including nitric oxide, reactive oxygen species, calcium, cyclic GMP, cyclic AMP, inositol triphosphate, diacylglycerol and by physiological pH. In addition, some small organic molecules, including inositol hexakisphosphate, yokonolide B, p-chlorophenoxyisobutyric acid, toyocamycin and terfestatin A, are involved in auxin signaling. In this review, we summarize and discuss the recent progress in understanding the functions of these secondary messengers and small organic molecules, which are now thoroughly demonstrated to be pervasive and important in auxin perception and signal transduction.

  12. Global Distribution of Mercury's Neutrals from MESSENGER Measurements Combined with a Tomographic Method

    NASA Technical Reports Server (NTRS)

    Sarantos, Menelaos; McClintock, Bill; Vervack, Ron, Jr.; Killen, Rosemary; Merkel, Aimee; Slavin, James; Solomon, Sean C.

    2011-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UVVS) onboard this spacecraft has been observing Mercury's collisionless exosphere. We present measurements by MESSENGER UVVS of the sodium, calcium, and magnesium distributions that were obtained during multiple passes through the tail over a period of one month. Global maps of the exosphere were constructed daily from such measurements using a recently developed tomographic technique. During this period, Mercury moved towards the Sun from being about 0.44 astronomical units (AU) to approximately 0.32 AU from the Sun. Hence, our reconstructions provide information about the three-dimensional structure of the exosphere, the source processes for these species, and their dependence with orbital distance during the entire in-leg of Mercury's orbit.

  13. Low-altitude magnetic field measurements by MESSENGER reveal Mercury’s ancient crustal field

    NASA Astrophysics Data System (ADS)

    Johnson, Catherine L.; Phillips, Roger J.; Purucker, Michael E.; Anderson, Brian J.; Byrne, Paul K.; Denevi, Brett W.; Feinberg, Joshua M.; Hauck, Steven A.; Head, James W.; Korth, Haje; James, Peter B.; Mazarico, Erwan; Neumann, Gregory A.; Philpott, Lydia C.; Siegler, Matthew A.; Tsyganenko, Nikolai A.; Solomon, Sean C.

    2015-05-01

    Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury’s crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury’s history. Ancient field strengths that range from those similar to Mercury’s present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury’s crust inferred from MESSENGER elemental composition data.

  14. Is the Pharmacological Mode of Action of Chromium(III) as a Second Messenger?

    PubMed

    Vincent, John B

    2015-07-01

    Although recent studies have shown that chromium (as the trivalent ion) is not an essential trace element, it has been demonstrated to generate beneficial effects at pharmacologically relevant doses on insulin sensitivity and cholesterol levels of rodent models of insulin insensitivity, including models of type 2 diabetes. The mode of action of Cr(III) at a molecular level is still an area of active debate; however, the movement of Cr(III) in the body, particularly in response to changes in insulin concentration, suggests that Cr(III) could act as a second messenger, amplifying insulin signaling. The evidence for the pharmacological mechanism of Cr(III)'s ability to increase insulin sensitivity by acting as a second messenger is reviewed, and proposals for testing this hypothesis are described.

  15. Astronomy's New Messengers: A traveling exhibit to reach out to a young adult audience

    NASA Astrophysics Data System (ADS)

    Cavaglià, Marco; Hendry, Martin; Márka, Szabolcs; Reitze, David H.; Riles, Keith

    2010-05-01

    The Laser Interferometer Gravitational-wave Observatory exhibit Astronomy's New Messengers: Listening to the Universe with Gravitational Waves is traveling to colleges, universities, museums and other public institutions throughout the United States. In 2010, an extended version of this exhibit will appear in a New York City venue that is accessible to a large and diverse cross section of the general public. Astronomy's New Messengers primarily communicates with an adolescent and young adult audience, potentially inspiring them into the field of science. Acknowledging that this audience is traditionally a difficult one to attract, the exhibit publicly announces itself in a charismatic fashion to reach its principal goals of broadening the community of people interested in science and encouraging interest in science among young people.

  16. MESSENGER Observations of Extreme Loading and Unloading of Mercury's Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Nittler, Larry R.; Raines, Jim M.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Starr, Richard D.; Travnicek, Pavel M.; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's third flyby of Mercury, the magnetic field in the planet's magnetotail increased by factors of 2 to 3.5 over intervals of 2 to 3 min. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is approx.10 times less and typical durations are approx.1 hour. The extreme tail loading observed at Mercury implies that the relative intensity of sub storms must be much larger than at Earth. The correspondence between the duration of tail field enhancements and the characteristic time for the Dungey cycle, which describes plasma circulation through Mercury's magnetosphere. suggests that such circulation determines substorm timescale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles, but no acceleration signatures were seen during the MESSENGER flyby.

  17. Mercury's rotational state from combined MESSENGER laser altimeter and image data

    NASA Astrophysics Data System (ADS)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Margot, Jean-Luc; Phillips, Roger J.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.

    2016-04-01

    With orbital data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, we measured the rotational state of Mercury. We developed a novel approach that combined digital terrain models from stereo images (stereo DTMs) and laser altimeter data, and we applied it to 3 years of MESSENGER observations. We find a large libration amplitude, which in combination with the measured obliquity confirms that Mercury possesses a liquid outer core. Our results confirm previous Earth-based observations of Mercury's rotational state. However, we measured a rotation rate that deviates significantly from the mean resonant rotation rate. The larger rotation rate can be interpreted as the signature of a long-period libration cycle. From these findings we derived new constraints on the interior structure of Mercury. The measured rotational parameters define Mercury's body-fixed frame and are critical for the coordinate system of the planet as well as for planning the future BepiColombo spacecraft mission.

  18. Effect of Thymine Starvation on Messenger Ribonucleic Acid Synthesis in Escherichia coli

    PubMed Central

    Luzzati, Denise

    1966-01-01

    Luzzati, Denise (Institut de Biologie Physico-Chimique, Paris, France). Effect of thymine starvation on messenger ribonucleic acid synthesis in Escherichia coli. J. Bacteriol. 92:1435–1446. 1966.—During the course of thymine starvation, the rate of synthesis of messenger ribonucleic acid (mRNA, the rapidly labeled fraction of the RNA which decays in the presence of dinitrophenol or which hybridizes with deoxyribonucleic acid) decreases exponentially, in parallel with the viability of the thymine-starved bacteria. The ability of cell-free extracts of starved bacteria to incorporate ribonucleoside triphosphates into RNA was determined; it was found to be inferior to that of extracts from control cells. The analysis of the properties of cell-free extracts of starved cells shows that their decreased RNA polymerase activity is the consequence of a modification of their deoxyribonucleic acid, the ability of which to serve as a template for RNA polymerase decreases during starvation. PMID:5332402

  19. MESSENGER observations of extreme loading and unloading of Mercury's magnetic tail.

    PubMed

    Slavin, James A; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Boardsen, Scott A; Gloeckler, George; Gold, Robert E; Ho, George C; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Nittler, Larry R; Raines, Jim M; Sarantos, Menelaos; Schriver, David; Solomon, Sean C; Starr, Richard D; Trávnícek, Pavel M; Zurbuchen, Thomas H

    2010-08-06

    During MESSENGER's third flyby of Mercury, the magnetic field in the planet's magnetic tail increased by factors of 2 to 3.5 over intervals of 2 to 3 minutes. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is lower by a factor of approximately 10 and typical durations are approximately 1 hour. The extreme tail loading observed at Mercury implies that the relative intensity of substorms must be much larger than at Earth. The correspondence between the duration of tail field enhancements and the characteristic time for the Dungey cycle, which describes plasma circulation through Mercury's magnetosphere, suggests that such circulation determines the substorm time scale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles, but no acceleration signatures were seen during the MESSENGER flyby.

  20. MESSENGER Observations of Extreme Loading and Unloading of Mercury's Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L.; Nittler, Larry R.; Raines, Jim M.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Starr, Richard D.; Travnicek, Pavel M.; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's third flyby of Mercury, a series of 2-3 minute long enhancements of the magnetic field in the planet's magnetotail were observed. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is approximately 10 times less and the durations are 1 hr. These observations of extreme loading imply that the relative intensity of substorms at Mercury must be much larger than at Earth. The correspondence between the duration of tail enhancements and the calculated approximately 2 min Dungey cycle, which describes plasma circulation through Mercury's magnetosphere, suggests that such circulation determines substorm timescale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles. Such signatures are puzzlingly absent from the MESSENGER flyby measurements.

  1. Return to Mercury: a global perspective on MESSENGER's first Mercury flyby.

    PubMed

    Solomon, Sean C; McNutt, Ralph L; Watters, Thomas R; Lawrence, David J; Feldman, William C; Head, James W; Krimigis, Stamatios M; Murchie, Scott L; Phillips, Roger J; Slavin, James A; Zuber, Maria T

    2008-07-04

    In January 2008, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft became the first probe to fly past the planet Mercury in 33 years. The encounter revealed that Mercury is a dynamic system; its liquid iron-rich outer core is coupled through a dominantly dipolar magnetic field to the surface, exosphere, and magnetosphere, all of which interact with the solar wind. MESSENGER images confirm that lobate scarps are the dominant tectonic landform and record global contraction associated with cooling of the planet. The history of contraction can be related to the history of volcanism and cratering, and the total contractional strain is at least one-third greater than inferred from Mariner 10 images. On the basis of measurements of thermal neutrons made during the flyby, the average abundance of iron in Mercury's surface material is less than 6% by weight.

  2. Evidence for young volcanism on Mercury from the third MESSENGER flyby.

    PubMed

    Prockter, Louise M; Ernst, Carolyn M; Denevi, Brett W; Chapman, Clark R; Head, James W; Fassett, Caleb I; Merline, William J; Solomon, Sean C; Watters, Thomas R; Strom, Robert G; Cremonese, Gabriele; Marchi, Simone; Massironi, Matteo

    2010-08-06

    During its first two flybys of Mercury, the MESSENGER spacecraft acquired images confirming that pervasive volcanism occurred early in the planet's history. MESSENGER's third Mercury flyby revealed a 290-kilometer-diameter peak-ring impact basin, among the youngest basins yet seen, having an inner floor filled with spectrally distinct smooth plains. These plains are sparsely cratered, postdate the formation of the basin, apparently formed from material that once flowed across the surface, and are therefore interpreted to be volcanic in origin. An irregular depression surrounded by a halo of bright deposits northeast of the basin marks a candidate explosive volcanic vent larger than any previously identified on Mercury. Volcanism on the planet thus spanned a considerable duration, perhaps extending well into the second half of solar system history.

  3. Planetary science. Low-altitude magnetic field measurements by MESSENGER reveal Mercury's ancient crustal field.

    PubMed

    Johnson, Catherine L; Phillips, Roger J; Purucker, Michael E; Anderson, Brian J; Byrne, Paul K; Denevi, Brett W; Feinberg, Joshua M; Hauck, Steven A; Head, James W; Korth, Haje; James, Peter B; Mazarico, Erwan; Neumann, Gregory A; Philpott, Lydia C; Siegler, Matthew A; Tsyganenko, Nikolai A; Solomon, Sean C

    2015-05-22

    Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data.

  4. MESSENGER observations of Mercury's exosphere: detection of magnesium and distribution of constituents.

    PubMed

    McClintock, William E; Vervack, Ronald J; Bradley, E Todd; Killen, Rosemary M; Mouawad, Nelly; Sprague, Ann L; Burger, Matthew H; Solomon, Sean C; Izenberg, Noam R

    2009-05-01

    Mercury is surrounded by a tenuous exosphere that is supplied primarily by the planet's surface materials and is known to contain sodium, potassium, and calcium. Observations by the Mercury Atmospheric and Surface Composition Spectrometer during MESSENGER's second Mercury flyby revealed the presence of neutral magnesium in the tail (anti-sunward) region of the exosphere, as well as differing spatial distributions of magnesium, calcium, and sodium atoms in both the tail and the nightside, near-planet exosphere. Analysis of these observations, supplemented by observations during the first Mercury flyby, as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes.

  5. Expected Geochemical and Mineralogical Properties of Meteorites from Mercury: Inferences from Messenger Data

    NASA Technical Reports Server (NTRS)

    McCubbin, F. M.; McCoy, T. J.

    2016-01-01

    Meteorites from the Moon, Mars, and many types of asteroid bodies have been identified among our global inventory of meteorites, however samples of Mercury and Venus have not been identified. The absence of mercurian and venusian meteorites could be attributed to an inability to recognize them in our collections due to a paucity of geochemical information for Venus and Mercury. In the case of mercurian meteorites, this possibility is further supported by dynamical calculations that suggest mercurian meteorites should be present on Earth at a factor of 2-3 less than meteorites from Mars [1]. In the present study, we focus on the putative mineralogy of mercurian meteorites using data obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which has provided us with our first quantitative constraints on the geochemistry of planet Mercury. We have used the MESSENGER data to compile a list of mineralogical and geochemical characteristics that a meteorite from Mercury is likely to exhibit.

  6. Mobile healthcare.

    PubMed

    Morgan, Stephen A; Agee, Nancy Howell

    2012-01-01

    Mobile technology's presence in healthcare has exploded over the past five years. The increased use of mobile devices by all segments of the US population has driven healthcare systems, providers, and payers to accept this new form of communication and to develop strategies to implement and leverage the use of mobile healthcare (mHealth) within their organizations and practices. As healthcare systems move toward a more value-driven model of care, patient centeredness and engagement are the keys to success. Mobile healthcare will provide the medium to allow patients to participate more in their care. Financially, mHealth brings to providers the ability to improve efficiency and deliver savings to both them and the healthcare consumer. However, mHealth is not without challenges. Healthcare IT departments have been reluctant to embrace this shift in technology without fully addressing security and privacy concerns. Providers have been hesitant to adopt mHealth as a form of communication with patients because it breaks with traditional models. Our healthcare system has just started the journey toward the development of mHealth. We offer an overview of the mobile healthcare environment and our approach to solving the challenges it brings to healthcare organizations.

  7. Defective control of pre-messenger RNA splicing in human disease.

    PubMed

    Chabot, Benoit; Shkreta, Lulzim

    2016-01-04

    Examples of associations between human disease and defects in pre-messenger RNA splicing/alternative splicing are accumulating. Although many alterations are caused by mutations in splicing signals or regulatory sequence elements, recent studies have noted the disruptive impact of mutated generic spliceosome components and splicing regulatory proteins. This review highlights recent progress in our understanding of how the altered splicing function of RNA-binding proteins contributes to myelodysplastic syndromes, cancer, and neuropathologies.

  8. Defective control of pre–messenger RNA splicing in human disease

    PubMed Central

    Shkreta, Lulzim

    2016-01-01

    Examples of associations between human disease and defects in pre–messenger RNA splicing/alternative splicing are accumulating. Although many alterations are caused by mutations in splicing signals or regulatory sequence elements, recent studies have noted the disruptive impact of mutated generic spliceosome components and splicing regulatory proteins. This review highlights recent progress in our understanding of how the altered splicing function of RNA-binding proteins contributes to myelodysplastic syndromes, cancer, and neuropathologies. PMID:26728853

  9. Comparison of MESSENGER Optical Images with Thermal and Radar Data for the Surface of MERCURY

    NASA Astrophysics Data System (ADS)

    Blewett, D. T.; Coman, E. I.; Chabot, N. L.; Izenberg, N. R.; Harmon, J. K.; Neish, C.

    2010-12-01

    Images collected by the MESSENGER spacecraft during its three Mercury flybys cover nearly the entire surface of the planet that was not imaged by Mariner 10. The MESSENGER data now allow us to observe features at optical wavelengths that were previously known only through remote sensing in other portions of the electromagnetic spectrum. For example, the Mariner 10 infrared (IR) radiometer made measurements along a track on the night side of Mercury during the spacecraft's first encounter in 1974. Analysis of the IR radiometer data identified several thermal anomalies that we have correlated to craters with extensive rays or ejecta deposits, including Xiao Zhao and Eminescu. The thermal properties are consistent with a greater exposure of bare rock (exposed in steep walls or as boulders and cobbles) in and around these craters compared with the lower-thermal-inertia, finer-grained regolith of the surrounding older surface. The portion of Mercury not viewed by Mariner 10 has also been imaged by Earth-based radar. The radar backscatter gives information on the wavelength-scale surface roughness. Arecibo S-band (12.6-cm wavelength) radar observations have produced images of Eminescu and also revealed two spectacular rayed craters (Debussy and Hokusai) that have since been imaged by MESSENGER. We are examining radial profiles for these craters, extracted from both the radar images and MESSENGER narrow-angle camera mosaics, that extend from the crater center outwards to a distance of several crater diameters. Comparison of optical and radar profiles for the craters, as well as similar profiles for lunar craters, can provide insight into ejecta deposition, the effect of surface gravity on the cratering process, and space weathering.

  10. Report from the Multi-Messenger Working Group at UHECR-2014 Conference

    NASA Astrophysics Data System (ADS)

    Karg, Timo; Alvarez-Muñiz, Jaime; Kuempel, Daniel; Settimo, Mariangela; Rubtsov, Grigory; Troitsky, Sergey

    The IceCube, Pierre Auger and Telescope Array Collaborations have recently reported results on neutral particles (neutrons, photons and neutrinos) which complement the measurements on charged primary cosmic rays at ultra-high energy. The complementarity between these messengers and between their detections are outlined. The current status of their search is reviewed and a cross-correlation analysis between the available results is performed. The expectations for photon and neutrino detections in the near future are also presented.

  11. Radial Evolution of a Magnetic Cloud: MESSENGER, STEREO, and Venus Express Observations

    NASA Astrophysics Data System (ADS)

    Good, S. W.; Forsyth, R. J.; Raines, J. M.; Gershman, D. J.; Slavin, J. A.; Zurbuchen, T. H.

    2015-07-01

    The Solar Orbiter and Solar Probe Plus missions will provide observations of magnetic clouds closer to the Sun than ever before, and it will be good preparation for these missions to make full use of the most recent in situ data sets from the inner heliosphere—namely, those provided by MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Venus Express—for magnetic cloud studies. We present observations of the same magnetic cloud made by MESSENGER at Mercury and later by Solar TErrestrial RElations Observatory-B (STEREO-B), while the spacecraft were radially aligned in 2011 November. Few such radial observations of magnetic clouds have been previously reported. Estimates of the solar wind speed at MESSENGER are also presented, calculated through the application of a previously established technique. The cloud's flux rope has been analyzed using force-free fitting; the rope diameter increased from 0.18 to 0.41 AU (corresponding to an {r}{{H}}0.94 dependence on heliocentric distance, rH), and the axial magnetic field strength dropped from 46.0 to 8.7 nT (an {r}{{H}}-1.84 dependence) between the spacecraft, clear indications of an expanding structure. The axial magnetic flux was ˜0.50 nT AU2 at both spacecraft, suggesting that the rope underwent no significant erosion through magnetic reconnection between MESSENGER and STEREO-B. Further, we estimate the change in the cloud's angular width by assuming helicity conservation. It has also been found that the rope axis rotated by 30° between the spacecraft to lie close to the solar equatorial plane at STEREO-B. Such a rotation, if it is a common feature of coronal mass ejection propagation, would have important implications for space weather forecasting.

  12. The Mercury Surface Interactive: Exploring MESSENGER data and images from orbit

    NASA Astrophysics Data System (ADS)

    Hallau, K. G.; Chapman, C. R.; Edmonds, J. P.; Goldstein, J. J.; Hirshon, B.; Solomon, S. C.; Vanhala, H. A.; Weir, H. M.

    2011-12-01

    In anticipation of NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entering orbit around Mercury, the mission's Education and Public Outreach team wanted to create materials in a format that would be engaging and easy to update as new data and images were obtained in the course of orbital operations. To achieve these goals, the team produced print materials, an online interactive Surface Explorer, and a blog-like feature, all of which are available from a central website (http://www.messenger-education.org/mosaic/). The print materials are large-format "Mosaic Postcards from Mercury" that highlight small sections of Mercury using flyby data. The postcards can be assembled into a partial mosaic image of Mercury, which will be gradually expanded with orbital data. The Mercury Surface Interactive employs Flash animation and interactivity to explore features on Mercury's surface; the interactive is visually compelling, but this format is difficult to update regularly. Since MESSENGER entered orbit around Mercury on March 18, 2011, the team has used a blog feature to quickly add links to new findings and to leverage other outreach resources created by the mission's science and engineering teams. Together, these three formats of outreach materials have helped engage students, teachers, and communities in anticipation of orbit and during the rapidly advancing unveiling of Mercury from orbit.

  13. Monte Carlo Modeling of Sodium in Mercury's Exosphere During the First Two MESSENGER Flybys

    NASA Technical Reports Server (NTRS)

    Burger, Matthew H.; Killen, Rosemary M.; Vervack, Ronald J., Jr.; Bradley, E. Todd; McClintock, William E.; Sarantos, Menelaos; Benna, Mehdi; Mouawad, Nelly

    2010-01-01

    We present a Monte Carlo model of the distribution of neutral sodium in Mercury's exosphere and tail using data from the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft during the first two flybys of the planet in January and September 2008. We show that the dominant source mechanism for ejecting sodium from the surface is photon-stimulated desorption (PSD) and that the desorption rate is limited by the diffusion rate of sodium from the interior of grains in the regolith to the topmost few monolayers where PSD is effective. In the absence of ion precipitation, we find that the sodium source rate is limited to approximately 10(exp 6) - 10(exp 7) per square centimeter per second, depending on the sticking efficiency of exospheric sodium that returns to the surface. The diffusion rate must be at least a factor of 5 higher in regions of ion precipitation to explain the MASCS observations during the second MESSENGER f1yby. We estimate that impact vaporization of micrometeoroids may provide up to 15% of the total sodium source rate in the regions observed. Although sputtering by precipitating ions was found not to be a significant source of sodium during the MESSENGER flybys, ion precipitation is responsible for increasing the source rate at high latitudes through ion-enhanced diffusion.

  14. Monte Carlo Modeling of Sodium in Mercury's Exosphere During the First Two MESSENGER Flybys

    NASA Technical Reports Server (NTRS)

    Burger, Matthew H.; Killen, Rosemary M.; Vervack, Ronald J., Jr.; Bradley, E. Todd; McClintock, William E.; Sarantos, Menelaos; Benna, Mehdi; Mouawad, Nelly

    2010-01-01

    We present a Monte Carlo model of the distribution of neutral sodium in Mercury's exosphere and tail using data from the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft during the first two flybys of the planet in January and September 2008. We show that the dominant source mechanism for ejecting sodium from the surface is photon-stimulated desorption (PSD) and that the desorption rate is limited by the diffusion rate of sodium from the interior of grains in the regolith to the topmost few monolayers where PSD is effective. In the absence of ion precipitation, we find that the sodium source rate is limited to approximately 10(exp 6) - 10(exp 7) per square centimeter per second, depending on the sticking efficiency of exospheric sodium that returns to the surface. The diffusion rate must be at least a factor of 5 higher in regions of ion precipitation to explain the MASCS observations during the second MESSENGER f1yby. We estimate that impact vaporization of micrometeoroids may provide up to 15% of the total sodium source rate in the regions observed. Although sputtering by precipitating ions was found not to be a significant source of sodium during the MESSENGER flybys, ion precipitation is responsible for increasing the source rate at high latitudes through ion-enhanced diffusion.

  15. Second Messenger Signaling in Bacillus subtilis: Accumulation of Cyclic di-AMP Inhibits Biofilm Formation

    PubMed Central

    Gundlach, Jan; Rath, Hermann; Herzberg, Christina; Mäder, Ulrike; Stülke, Jörg

    2016-01-01

    The Gram-positive model organism Bacillus subtilis produces the essential second messenger signaling nucleotide cyclic di-AMP. In B. subtilis and other bacteria, c-di-AMP has been implicated in diverse functions such as control of metabolism, cell division and cell wall synthesis, and potassium transport. To enhance our understanding of the multiple functions of this second messenger, we have studied the consequences of c-di-AMP accumulation at a global level by a transcriptome analysis. C-di-AMP accumulation affected the expression of about 700 genes, among them the two major operons required for biofilm formation. The expression of both operons was severely reduced both in the laboratory and a non-domesticated strain upon accumulation of c-di-AMP. In excellent agreement, the corresponding strain was unable to form complex colonies. In B. subtilis, the transcription factor SinR controls the expression of biofilm genes by binding to their promoter regions resulting in transcription repression. Inactivation of the sinR gene restored biofilm formation even at high intracellular c-di-AMP concentrations suggesting that the second messenger acts upstream of SinR in the signal transduction pathway. As c-di-AMP accumulation did not affect the intracellular levels of SinR, we conclude that the nucleotide affects the activity of SinR. PMID:27252699

  16. MESSENGER X-ray observations of magnetosphere-surface interaction on the nightside of Mercury

    NASA Astrophysics Data System (ADS)

    Lindsay, S. T.; James, M. K.; Bunce, E. J.; Imber, S. M.; Korth, H.; Martindale, A.; Yeoman, T. K.

    2016-06-01

    The recently completed MESSENGER mission to Mercury has detected X-ray fluorescence events on the nightside surface of the planet, induced by the precipitation of electrons. We expand upon previously reported catalogues of such events, using a filter based on elemental fluorescence lines to construct a catalogue covering the full five years of the MESSENGER mission. We find that the locations of the majority of these events are ordered in two clear latitudinal bands on the dawn side of the planet centred at ~50°N and ~20°S. Electron precipitation is implied to be either stable or occurring repeatedly on timescales of up to several minutes, long in relation to characteristic times of the Mercury magnetospheric environment. Conversely, X-ray fluorescence events are observed on only ~40% of MESSENGER orbits, although we note that some events are inevitably lost during the filtering process. We suggest that the regions of most intense precipitation are determined by the location of the relevant magnetic field line footprints on the surface. We are able to place speculative limits on the energies of electrons precipitating in this manner based on fluorescence lines in the observed X-ray spectra. The poleward boundaries of the regions of most intense precipitation are found to be collocated with the open-closed field line boundary. We use a magnetic field model to trace field lines from these fluorescence sites to implied locations of origin in the magnetotail.

  17. Isoleucine and Valine Metabolism in Escherichia coli K-12: Detection and Measurement of ilv-Specific Messenger Ribonucleic Acid

    PubMed Central

    Haar, R. A. Vonder; Umbarger, H. E.

    1974-01-01

    Ribonucleic acid-deoxyribonucleic acid (RNA-DNA) hybridization was employed for the determination of messenger RNA transcribed from the ilv gene cluster of Escherichia coli K-12. Strains with derepressed levels of the isoleucine and valine biosynthetic enzymes owing to linked or unlinked genetic lesions were found to exhibit ilv messenger RNA levels from 1.5- to 4-fold higher than did their isogenic parents. When grown under conditions that specifically repressed the synthesis of isoleucine- and valine-forming enzymes, most strains exhibited drastically reduced ilv messenger RNA levels. Hybridization performed with the separated strands of ilv DNA showed that all the ilv genes are transcribed from the same strand, the “l strand” of λφ80CI857St68dilv DNA. Sucrose gradient analyses of RNA extracted from cells starved for isoleucine, valine, or leucine resulted in the detection of at least two distinct types of ilv messenger RNA. PMID:4616946

  18. The Calcium-mobilizing Messenger Nicotinic Acid Adenine Dinucleotide Phosphate Participates in Sperm Activation by Mediating the Acrosome Reaction*

    PubMed Central

    Vasudevan, Sridhar R.; Lewis, Alexander M.; Chan, Jennifer W.; Machin, Claire L.; Sinha, Debroshi; Galione, Antony; Churchill, Grant C.

    2010-01-01

    Before a sperm can fertilize an egg it must undergo a final activation step induced by the egg termed the acrosome reaction. During the acrosome reaction a lysosome-related organelle, the acrosome, fuses with the plasma membrane to release hydrolytic enzymes and expose an egg-binding protein. Because NAADP (nicotinic acid adenine dinucleotide phosphate) releases Ca2+ from acidic lysosome-related organelles in other cell types, we investigated a possible role for NAADP in mediating the acrosome reaction. We report that NAADP binds with high affinity to permeabilized sea urchin sperm. Moreover, we used Mn2+ quenching of luminal fura-2 and 45Ca2+ to directly demonstrate NAADP regulation of a cation channel on the acrosome. Additionally, we show that NAADP synthesis occurs through base exchange and is driven by an increase in Ca2+. We propose a new model for acrosome reaction signaling in which Ca2+ influx initiated by egg jelly stimulates NAADP synthesis and that this NAADP acts on its receptor/channel on the acrosome to release Ca2+ to drive acrosomal exocytosis. PMID:20400502

  19. Exploring Mercury's Surface-bound Exosphere: An Overview of Observations During the MESSENGER Orbital Phase

    NASA Astrophysics Data System (ADS)

    McClintock, W. E.; Benna, M.; Burger, M. H.; Cassidy, T. A.; Killen, R. M.; Merkel, A. W.; Sarantos, M.; Solomon, S. C.; Sprague, A. L.; Vervack, R. J.

    2011-12-01

    Prior to the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, Mercury's surface-bounded exosphere was known to contain H, He, Na, K, and Ca. During three flybys en route to orbit, the Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on MESSENGER detected Ca+ in a narrow region 2.5 Mercury radii behind the planet's terminator, mapped Na, Ca, and Mg in the tail region, and measured altitude profiles of H on the dayside. UVVS began routine orbital observations of both the dayside and nightside exosphere on March 29, 2011, measuring altitude profiles for all previously detected neutrals except for He and K. The former has no emission features within the UVVS wavelength range (115 - 600 nm), and the latter has only one relatively weak feature there. Distributions of all species are variable and do not correlate with each other, consistent with flyby results. UVVS also scans for species that are known or are predicted to be present in the surface materials (e.g., Si, Al, S, Mn, Fe, and OH), but these emissions are not sufficiently bright for routine observation under current operational scenarios. Targeted sequences, scheduled for MESSENGER's third and fourth Mercury years, will measure the average exosphere content of species that are detected and substantially reduce the detection limits for the rest. The UVVS team uses a variety of techniques to relate exosphereic composition and structure to source processes, including tomographic inversion and Monte Carlo modeling. In addition, correlations of Mercury's neutral exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide additional insight. Models incorporating MAG observations identify the location and area of the surface exposed to solar wind plasma, while EPPS observations reveal episodic populations of energetic electrons in the

  20. Mobile Customer Relationship Management and Mobile Security

    NASA Astrophysics Data System (ADS)

    Sanayei, Ali; Mirzaei, Abas

    The purpose of this study is twofold. First, in order to guarantee a coherent discussion about mobile customer relationship management (mCRM), this paper presents a conceptualization of mCRM delineating its unique characteristics because of Among the variety of mobile services, considerable attention has been devoted to mobile marketing and in particular to mobile customer relationship management services. Second, the authors discusses the security risks in mobile computing in different level(user, mobile device, wireless network,...) and finally we focus on enterprise mobile security and it's subgroups with a series of suggestion and solution for improve mobile computing security.

  1. Going mobile

    NASA Astrophysics Data System (ADS)

    Brus, Eric

    1987-12-01

    By 1990, all metropolitan areas in the U.S. and rural areas close to major cities or towns are expected to have cellular telephone service; 22 Canadian cities also feature cellular service. To supply mobile telecommunication services to sparsely-populated rural areas, a mobile satellite service (MSS) is now being developed. In this paper the projected possibilities of the MSS system are discussed, including a possibility that a piggyback-MSS payload be added to the GSTAR-4 satellite which is scheduled for a launch in 1988 or 1989; one in which some of the hardware from aborted direct-broadcast satellites would be used; and the possibility of building a new MSS satellite with large servicing capacity. Canada is planning to launch its own mobile satellite, MSAT, in the early 1990s. The MSS is expected to be 'generic', serving not only people on land but maritime and aeronautical users as well. It will also offer major benefits to truck and automobile drivers, making it possible for them to conduct business or to call for assistance from locations beyond the range of cellular systems.

  2. The MESSENGER Earth Flyby: Results from the Mercury Dual Imaging System

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Murchie, S. L.; Hawkins, S. E.; Robinson, M. S.; Shelton, R. G.; Vaughan, R. M.; Solomon, S. C.

    2005-12-01

    The MESSENGER (MErcury Surface, Space ENvironment, Geochemistry, and Ranging) spacecraft was launched from Cape Canaveral Air Force Station, Fla., on 3 August 2004. It returned to Earth for a gravity assist on 2 August 2005, providing an exceptional opportunity for the Science Team to perform instrument calibrations and to test some of the data acquisition sequences that will be used to meet Mercury science goals. The Mercury Dual Imaging System (MDIS), one of seven science instruments on MESSENGER, consists of a wide-angle and a narrow-angle imager that together can map landforms, track variations in surface color, and carry out stereogrammetry. The two imagers are mounted on a pivot platform that enables the instrument to point in a different direction from the spacecraft boresight, allowing great flexibility and increased imaging coverage. During the week prior to the closest approach to Earth, MDIS acquired a number of images of the Moon for radiometric calibration and to test optical navigation sequences that will be used to target planetary flybys. Twenty-four hours before closest approach, images of the Earth were acquired with 11 filters of the wide-angle camera. After MDIS flew over the nightside of the Earth, additional color images centered on South America were obtained at sufficiently high resolution to discriminate small-scale features such as the Amazon River and Lake Titicaca. During its departure from Earth, MDIS acquired a sequence of images taken in three filters every 4 minutes over a period of 24 hours. These images have been assembled into a movie of a crescent Earth that begins as South America slides across the terminator into darkness and continues for one full Earth rotation. This movie and the other images have provided a successful test of the sequences that will be used during the MESSENGER Mercury flybys in 2008 and 2009 and have demonstrated the high quality of the MDIS wide-angle camera.

  3. Exploring the recovery and detection of messenger RNA and DNA from enhanced fingermarks in blood.

    PubMed

    Fox, A; Gittos, M; Harbison, S A; Fleming, R; Wivell, R

    2014-05-01

    Often in the examination of bloodstained fingermarks discussion occurs around whether to prioritise the fingerprint evidence or focus on the biological evidence. Collecting a sample for genetic profiling may result in the loss of ridge detail that could have been used for fingerprint comparison. Fingermark enhancement and recovery methods along with sample collection methods could also compromise downstream genetic analysis. Previous forensic casework has highlighted circumstances where, after enhancement had been performed, it would have been extremely valuable to both identify the body fluid and generate a DNA profile from the same sample. We enhanced depletion series of fingermarks made in blood, using single treatments consisting of aqueous amido black, methanol-based amido black, acid yellow and leucocrystal violet, and exposure to long wave UV light. We then extracted the DNA and RNA for profiling, to assess the recovery and detection of genetic material from the enhanced fingermarks. We have shown that genetic profiling of bloodstained fingermarks can be successful after chemical enhancement; however it may still be necessary to prioritise evidence types in certain circumstances. From our results it appears that even with visible bloodstained fingermarks, leucocrystal violet can reduce the effectiveness of subsequent messenger RNA profiling. Aqueous amido black and acid yellow also have adverse effects on messenger RNA profiling of depleted fingermarks with low levels of cellular material. These results help with forensic decision-making by expanding knowledge of the extent of the detrimental effects of blood-enhancement reagents on both DNA profiling and body fluid identification using messenger RNA profiling. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  4. Radiative transfer modeling of MESSENGER VIRS spectra: Detection and mapping of submicroscopic iron and carbon

    NASA Astrophysics Data System (ADS)

    Trang, David; Lucey, Paul G.; Izenberg, Noam R.

    2017-09-01

    We model the spectral effects of submicroscopic Fe and submicroscopic C particles within a transparent mineral host in order to investigate whether such materials could reproduce the major spectral characteristics of Mercury's reflectance spectra (i.e., low reflectance relative to the Moon, a lack of Fe absorption features in the near infrared, and an increasing continuum slope between visible and near-infrared wavelengths). By using the radiative transfer technique to model the VIRS (Visible and Infrared Spectrograph) spectral dataset obtained from the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission, we found that our spectral models based on nanophase and microphase Fe and C consistently fit the VIRS data (except of regions of Mercury's low-reflectance material). Our models show that the mean global submicroscopic Fe abundance is 2.5 wt%, which exceeds the total Fe abundances obtained from the MESSENGER Gamma-Ray Spectrometer (GRS) and the X-Ray Spectrometer (XRS) and the global average submicroscopic C abundance is 1.9 wt%, which is within the three-standard-deviation level of the MESSENGER GRS C measurements for Mercury's northern hemisphere. We also produced nanophase and microphase Fe and C abundance maps that show: (1) submicroscopic C is present at percent levels across the surface, (2) the spatial variations of submicroscopic particle abundances are correlated to the maximum surface temperature, (3) lower concentrations of nanophase Fe in fresh craters and their ejecta, (4) the submicroscopic Fe abundance is lower in the northern volcanic plains and Caloris basin than the global average, (5) the submicroscopic C and Fe abundances are very low around NE Rachmaninoff, a pyroclastic deposit, and (6) the submicroscopic particle abundances vary between low-reflectance material (LRM) deposits. In correlating these maps to geology and surface temperatures, we concluded that Ostwald ripening is responsible for the longitudinal and

  5. MESSENGER Searches for Less Abundant or Weakly Emitting Species in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Vervack, Ronald J., Jr.; McClintock, William E.; Killen, Rosemary M.; Sprague, Ann L.; Burger, Matthew H.; Merkel, Aimee W.; Sarantos, Menelaos

    2011-01-01

    Mercury's exosphere is composed of material that originates at the planet's surface, whether that material is native or delivered by the solar wind and micrometeoroids. Many exospheric species have been detected by remote sensing, including H and He by Mariner 10, Na, K, and Ca by ground-based observations, and H, Na, Ca, Mg, and Ca+ by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Other exospheric species, including Fe, AI, Si, 0, S, Mn, CI, Ti, OH, and their ions, are expected to be present on the basis of MESSENGER surface measurements and models of Mercury's surface chemistry. Here we report on searches for these species made with the Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). No obvious signatures of the listed species have yet been observed in Mercury's exosphere by the UVVS as of this writing. It is possible that detections are elusive because the optimum regions of the exosphere have not been sampled. The Sun-avoidance constraints on MESSENGER place tight limits on instrument boresight directions, and some regions are probed infrequently. If there are strong spatial gradients in the distribution of weakly emitting species, a high-resolution sampling of specific regions may be required to detect them. Summing spectra over time will also aid in the ability to detect weaker emission. Observations to date nonetheless permit strong upper limits to be placed on the abundances of many undetected species, in some cases as functions of time and space. As those limits are lowered with time, the absence of detections can provide insight into surface composition and the potential source mechanisms of exospheric material.

  6. Messenger molecules of the phospholipase signaling system have dual effects on vascular smooth muscle contraction.

    PubMed

    Vidulescu, Cristina; Mironneau, J.; Mironneau, Chantal; Popescu, L. M.

    2000-01-01

    Background and methods. In order to investigate the role of phospholipases and their immediately derived messengers in agonist-induced contraction of portal vein smooth muscle, we used the addition in the organ bath of exogenous molecules such as: phospholipases C, A(2), and D, diacylglycerol, arachidonic acid, phosphatidic acid, choline. We also used substances modulating activity of downstream molecules like protein kinase C, phosphatidic acid phosphohydrolase, or cyclooxygenase. Results. a) Exogenous phospholipases C or A(2), respectively, induced small agonist-like contractions, while exogenous phospholipase D did not. Moreover, phospholipase D inhibited spontaneous contractions. However, when added during noradrenaline-induced plateau, phospholipase D shortly potentiated it. b) The protein kinase C activator, phorbol dibutyrate potentiated both the exogenous phospholipase C-induced contraction and the noradrenaline-induced plateau, while the protein kinase C inhibitor 1-(-5-isoquinolinesulfonyl)-2-methyl-piperazine relaxed the plateau. c) When added before noradrenaline, indomethacin inhibited both phasic and tonic contractions, but when added during the tonic contraction shortly potentiated it. Arachidonic acid strongly potentiated both spontaneous and noradrenaline-induced contractions, irrespective of the moment of its addition. d) In contrast, phosphatidic acid inhibited spontaneous contractile activity, nevertheless it was occasionally capable of inducing small contractions, and when repetitively added during the agonist-induced tonic contraction, produced short potentiations of the plateau. Pretreatment with propranolol inhibited noradrenaline-induced contractions and further addition of phosphatidic acid augmented this inhibition. Choline augmented the duration and amplitude of noradrenaline-induced tonic contraction and final contractile oscillations. Conclusions. These data suggest that messengers produced by phospholipase C and phospholipase A(2

  7. The Mercury Gravity Field after the MESSENGER Low-Altitude Gravity Campaign

    NASA Astrophysics Data System (ADS)

    Mazarico, E.; Genova, A.; Goossens, S. J.; Lemoine, F. G.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.; Solomon, S. C.

    2014-12-01

    NASA's MESSENGER spacecraft has collected more than 3.5 years of X-band radio tracking data in orbit around the planet Mercury. During its one-year primary mission, which started in March 2011, MESSENGER was in an eccentric, near-polar orbit of 12-hour period, and the periapsis altitude was actively maintained between 200 and 500 km. For its extended mission, the orbit period was reduced to 8 hours. As the orbit naturally evolved, in large part due to the third-body gravitational perturbation of the Sun, the periapsis altitude reached a maximum of ~450 km in March 2013 and then began to decrease. An ambitious end of mission was designed to use the remaining fuel to delay impact and to observe the northern hemisphere for nearly a year at periapsis altitudes lower than 200 km, including four intervals of exceptionally low altitude (25-100 km). Periapsis passages are visible from Earth only for two of these intervals, in August and October 2014. These new data, the lowest-altitude radio tracking measurements to be acquired by MESSENGER, prompt an updated solution for the gravity field of Mercury. In preparation for acquisition of the low-altitude (<100 km) data, we have reprocessed tracking data through 14 July 2014. These data already provide good coverage below 200 km over most longitudes. A preliminary gravity solution to degree and order 50 shows stronger gravity anomalies near the periapsis latitudes than in the most recent global solution, HgM005. To best capture the shorter-wavelength signals expected from the lowest-altitude passes, we are estimating a large number of local surface anomalies (arranged on a 1°x1° grid) in addition to a harmonic field. We are also using the resulting gravity anomalies to update crustal thickness models and to explore the implications for gravity anomalies over basins and topographic rises and the modes of compensation of these features.

  8. Protein Kinase Target Discovery From Genome-Wide Messenger RNA Expression Profiling

    PubMed Central

    Ma’ayan, Avi; He, John C.

    2010-01-01

    Genome-wide messenger RNA profiling provides a snapshot of the global state of the cell under different experimental conditions such as diseased versus normal cellular states. However, because measurements are in the form of quantitative changes in messenger RNA levels, such experimental data does not provide direct understanding of the regulatory molecular mechanisms responsible for the observed changes. Identifying potential cell signaling regulatory mechanisms responsible for changes in gene expression under different experimental conditions or in different tissues has been the focus of many computational systems biology studies. Most popular approaches include promoter analysis, gene ontology, or pathway enrichment analysis, as well as reverse engineering of networks from messenger RNA expression data. Here we present a rational approach for identifying and ranking protein kinases that are likely responsible for observed changes in gene expression. By combining promoter analysis; data from various chromatin immunoprecipitation studies such as chromatin immunoprecipitation sequencing, chromatin immunoprecipitation coupled with paired-end ditag, and chromatin immunoprecipitation-on-chip; protein-protein interactions; and kinase-protein phosphorylation reactions collected from the literature, we can identify and rank candidate protein kinases for knock-down, or other types of functional validations, based on genome-wide changes in gene expression. We describe how protein kinase candidate identification and ranking can be made robust by cross-validation with phosphoproteomics data as well as through a literature-based text-mining approach. In conclusion, data integration can produce robust candidate rankings for understanding cell regulation through identification of protein kinases responsible for gene expression changes, and thus rapidly advancing drug target discovery and unraveling drug mechanisms of action. PMID:20687179

  9. Mercury's Internal Magnetic Field: Results from MESSENGER's Search for Remanent Crustal Magnetization Associated with Impact Basins

    NASA Astrophysics Data System (ADS)

    Purucker, M. E.; Johnson, C. L.; Nicholas, J. B.; Philpott, L. C.; Korth, H.; Anderson, B. J.; Head, J. W., III; Phillips, R. J.; Solomon, S. C.

    2014-12-01

    Magnetic field measurements obtained by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in orbit around Mercury have entered a new phase since April 2014, with periapsis altitudes below 200 km. MESSENGER is now obtaining magnetic profiles across large impact features at altitudes less than the horizontal scale of those features. We use data from this latest phase to investigate evidence for remanent crustal magnetization specifically associated with impact basins and large craters. The spatial resolution of magnetic field measurements for investigating crustal magnetization is approximately equal to the altitude of the observations. We focus on large impact features because their relative ages provide a powerful chronological tool for interpreting any associated magnetic signatures. We examine profiles across large impact basins such as Caloris, Shakespeare, Budh-Sobkou and Goethe. For example, coverage over Caloris during the last year of the mission will be largely at night and will comprise 18 profiles with altitudes between 125 and 200 km and 12 profiles with altitudes between 50 and 125 km over the northern part of the basin. We use large-scale magnetospheric models developed with MESSENGER data to remove contributions from the offset axial dipole, magnetopause, and magnetotail. The residual magnetic fields above 200 km are still dominated by poorly understood magnetospheric fields such as those from the cusp and from Birkeland currents. We empirically average, or exclude observations from these local times, in order to search for repeatable internal field signals. We use local basis functions such as equivalent source dipoles, applied with regularization tools, in order to map the altitude-normalized magnetic field from internal sources. These internal sources may comprise both crustal and core contributions, and we use the information from the along-track magnetic gradient in order to separate these contributions.

  10. Pharmacological characterization of the phosphoinositide second messenger system in the rabbit kidney

    SciTech Connect

    McArdle, S.

    1988-01-01

    The cellular response to hormones and neurotransmitters is a result of receptor activation of a second messenger system to initiate the intracellular cascade. In several tissues, such as brain and liver, one of the second messenger systems involves the hydrolysis of phosphoinositides (PIs) for the formation of inositol phosphate and diacylglycerol as the intracellular messengers. In the present study, they examined the effect of various agents on the hydrolysis of PIs in the rabbit kidney. In the kidney, the effect of the various hormones and neurotransmitters was region specific. Hydrolysis of PIs was stimulated in the inner medulla by (arg{sup 8})-vasopressin, angiotensin II, and atriopeptin I, and in the outer medulla by histamine, adenosine, and secretin. Only carbachol was able to stimulate the hydrolysis of PIs in both the inner and outer medulla. None of the substances tested were able to stimulate this response in the cortex. The following agents did not have an effect in any of the three zones of the kidney: norepinephrine, dopamine, atriopeptins II, and III. They have directly demonstrated the presence of a high affinity saturable binding site on inner medullary collecting duct (IMCD) cells with studies of binding characteristics of the radiolabelled muscarinic antagonist, 1-quinuclidinyl (phenyl-4-{sup 3}H) benzilate (({sup 3}H)QNB). The K{sub d} of 0.27 nM and the B{sub max} of 27.5 fmol/mg protein were determined from Scatchard analysis of the saturation data. In summary, they have demonstrated that cholinergic muscarinic receptors are present in the rabbit kidney, specifically in the IMCD cells. These receptors, which are coupled to the hydrolysis of phosphoinositides, may be involved in the vasodilatory and/or diuretic effects of cholinergic agents.

  11. Key science issues after MESSENGER and current observation plans of BepiColombo MMO

    NASA Astrophysics Data System (ADS)

    Murakami, Go; Hayakawa, Hajime; Fujimoto, Masaki

    2017-04-01

    Little had been known about the Hermean magnetosphere until MESSENGER explored the region. The region is formed as the weak planetary magnetic field stands against the intense solar wind in the close proximity of the Sun. Various prediction had been given by noting the difference in the parameters from the well-studied terrestiral magnetosphere of a similar setting and scaling the well-knowns to the Hermean environment. MESSENGER results, however, show a wide varieity of phenomena that are out of the scope of what one could have reasonably argued. The micro-magnetosphere of Mercury is much more dynamic than one had predicted. BepiColombo MMO, the JAXA spacecraft of the BepiColombo Mercury exploration mission which will be launched in 2018 and will arrive at Mercury in 2025, is equipped to study the space environment of the planet Mercury. BepiColombo MMO is mainly designed for plasma observations and is expected to extract essential elements of space plasma physics that become visible in the Hermean environment. MMO has large constraints on science operations, such as thermal issue and limited telemetry rate. Due to the thermal issue each science instrument cannot always be turned on. In addition, due to the low telemetry rate in average, only a part ( 20-30%) of science mission data with high resolution can be downlinked. Therefore, in order to maximize the scientific results and outcomes to be achieved by MMO, we are now working to optimize the science observation and downlink plans in detail. Here we review MESSENGER results and how MMO will contribute to deepen our understanding of space plasmas by addressing the puzzles raised by MESSEGNER.

  12. Performance Assessment of the Mercury Laser Altimeter on MESSENGER from Mercury Orbit

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Mazarico, Edward M.

    2009-01-01

    The Mercury Laser Altimeter (MLA) is one of seven instruments on the MErcury Surface, Space ENvironment GEochemistry, and Ranging (MESSENGER) spacecraft,a mission in NASA's Discovery Program. MESSENGER was launched on August 3, 2004, and entered into orbit about Mercury on March 29, 2011. As of June 30, 2011 MLA started to collect science Measurements on March 29, 2011. As of June 30, 2011 MLA had accumulated about 3 million laser ranging measurements to the Mercury surface through one Mercury year, i.e ., one complete cycle of the spacecraft thermal environment. The average MLA laser output-pulse energy remained steady despite the harsh thermal environment, in which the laser bench temperature changed by as much as 15 C over a 35 min operating period . The laser beam-collimating telescope experienced a 30 C temperature swing over the same period, and the thermal cycling repeated every 12 hours. Nonetheless, MLA receiver optics appeared to be aligned and in focus throughout these temperature excursions. The maximum ranging distance of MLA was 1500 km at near-zero laser-beam incidence angle (and emission angle) and 600 km at 60 deg incidence angle. The MLA instrument performance in Mercury orbit has been consistent with the performance demonstrated during MESSENGER's Mercury flybys in January and October 2008 and during pre-launch testing. In addition to range measurements, MLA data are being used to estimate the surface reflectance of Mercury at 1064 nm wavelength, including regions of permanent shadow on the floors of polar craters. MLA also provides a measurement of the surface reflectance of sunlight at 1064 nm wavelength by its noise counters, for which output is a monotonic function of the background light.

  13. Gamma-Ray Bursts and Fast Transients. Multi-wavelength Observations and Multi-messenger Signals

    NASA Astrophysics Data System (ADS)

    Willingale, R.; Mészáros, P.

    2017-07-01

    The current status of observations and theoretical models of gamma-ray bursts and some other related transients, including ultra-long bursts and tidal disruption events, is reviewed. We consider the impact of multi-wavelength data on the formulation and development of theoretical models for the prompt and afterglow emission including the standard fireball model utilizing internal shocks and external shocks, photospheric emission, the role of the magnetic field and hadronic processes. In addition, we discuss some of the prospects for non-photonic multi-messenger detection and for future instrumentation, and comment on some of the outstanding issues in the field.

  14. Second messengers and membrane trafficking direct and organize growth cone steering

    PubMed Central

    Tojima, Takuro; Hines, Jacob H.; Henley, John R.; Kamiguchi, Hiroyuki

    2011-01-01

    Graded distributions of extracellular cues guide developing axons toward their targets. A network of second messengers, Ca2+ and cyclic nucleotides, shapes cue-derived information into either attractive or repulsive signals that steer growth cones bidirectionally. Emerging evidence suggests that such guidance signals create a localized imbalance between exocytosis and endocytosis, which in turn redirects membrane, adhesion and cytoskeletal components asymmetrically across the growth cone to bias the direction of axon extension. These recent advances allow us to propose a unifying model of how the growth cone translates shallow gradients of environmental information into polarized activity of the steering machinery for axon guidance. PMID:21386859

  15. MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

    NASA Technical Reports Server (NTRS)

    Zurbuchen, Thomas H.; Raines, Jim M.; Slavin, James A.; Gershman, Daniel J.; Gilbert, Jason A.; Gloeckler, George; Anderson, Brian J.; Baker, Daniel N.; Korth, Haje; Krimigis, Stamatios M.; hide

    2011-01-01

    Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.

  16. Putative Key Role of Inositol Messengers in Endothelial Cells in Preeclampsia

    PubMed Central

    Kunjara, Sirilaksana; McLean, Patricia; Rademacher, Laurens; Rademacher, Thomas W.; Fascilla, Fabiana; Bettocchi, Stefano

    2016-01-01

    Immunological alterations, endothelial dysfunction, and insulin resistance characterize preeclampsia. Endothelial cells hold the key role in the pathogenesis of this disease. The signaling pathways mediating these biological abnormalities converge on PKB/Akt, an intracellular kinase regulating cell survival, proliferation, and metabolism. Inositol second messengers are involved in metabolic and cell signaling pathways and are highly expressed during preeclampsia. Intracellular action of these molecules is deeply affected by zinc, manganese, and calcium. To evaluate the pathophysiological significance, we present the response of the intracellular pathways of inositol phosphoglycans involved in cellular metabolism and propose a link with the disease. PMID:27738431

  17. MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

    NASA Technical Reports Server (NTRS)

    Zurbuchen, Thomas H.; Raines, Jim M.; Slavin, James A.; Gershman, Daniel J.; Gilbert, Jason A.; Gloeckler, George; Anderson, Brian J.; Baker, Daniel N.; Korth, Haje; Krimigis, Stamatios M.; Sarantos, Menelaos; Schriver, David; McNutt, Ralph L., Jr.; Solomon, Sean C.

    2011-01-01

    Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.

  18. On Hydrogen at Mercury's North Pole: Analysis of MESSENGER Neutron Spectrometer Data

    NASA Astrophysics Data System (ADS)

    Lawrence, D. J.; Feldman, W. C.; Goldsten, J. O.; Peplowski, P. N.; Maurice, S.; Anderson, B. J.; Bazell, D.; McNutt, R. L.; Nittler, L. R.; Prettyman, T. H.; Rodgers, D. J.; Solomon, S. C.; Weider, S. Z.

    2012-12-01

    Determining the nature of radar-bright material in permanently shadowed craters near Mercury's poles is a major goal of the MESSENGER mission. The leading explanation is that these deposits, located inside permanently shadowed craters near both poles, contain large amounts of frozen water ice. A Neutron Spectrometer (NS) was included on the MESSENGER spacecraft to measure hydrogen concentrations near Mercury's north pole to determine if large amounts of hydrogen, and by inference water ice, are responsible for the radar-bright signatures. Measurements of fast neutrons (En > 500 keV, where En is the neutron kinetic energy) and epithermal neutrons (0.4 eV < En < 500 keV) can provide independent information about the concentration and burial depth (up to 100 cm) of hydrogen within a planetary regolith. Calculations of neutron signals expected for several possible models of water ice in the radar-bright craters at Mercury's north pole indicate that if there exist concentrations of water ice in excess of 50 wt.% distributed uniformly in the radar-bright regions, the NS should detect statistically significant reductions in the count rates of both epithermal and fast neutrons from polar regions relative to more equatorward dry regions. The analysis of MESSENGER NS data has required time both to build up adequate statistics and to develop the analysis procedures required for detecting a relatively small (<4%) expected hydrogen signal. Due to mission operational requirements, the MESSENGER spacecraft is in a highly eccentric orbit about Mercury with a periapsis altitude of a few hundred km in the northern hemisphere and an apoapsis altitude of ~15,200 km. As a consequence, substantial corrections must be made to the data to compensate for the constantly changing spacecraft altitude. In addition, when close to the planet, the NS acquires data at a variety of spacecraft attitudes relative to nadir, which requires the development of corrections not needed for measurements

  19. Mercury's Hollows: New Information on Distribution and Morphology from MESSENGER Observations at Low Altitude

    NASA Astrophysics Data System (ADS)

    Blewett, D. T.; Stadermann, A. C.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.; Peplowski, P. N.

    2014-12-01

    MESSENGER's orbital mission at Mercury led to the discovery of an unusual landform not known from other airless rocky bodies of the Solar System. Hollows are irregularly shaped, shallow, rimless depressions, often occurring in clusters and with high-reflectance interiors and halos. The fresh appearance of hollows suggests that they are relatively young features. For example, hollows are uncratered, and talus aprons downslope of hollows in certain cases appear to be covering small impact craters (100-200 in diameter). Hence, some hollows may be actively forming at present. The characteristics of hollows are suggestive of formation via destruction of a volatile-bearing phase (possibly one or more sulfides) through solar heating, micrometeoroid bombardment, and/or ion impact. Previous analysis showed that hollows are associated with low-reflectance material (LRM), a color unit identified from global color images. The material hosting hollows has often been excavated from depth by basin or crater impacts. Hollows are small features (tens of meters to several kilometers), so their detection and characterization with MESSENGER's global maps have been limited. MESSENGER's low-altitude orbits provide opportunities for collection of images at high spatial resolutions, which reveal new occurrences of hollows and offer views of hollows with unprecedented detail. As of this writing, we have examined more than 21,000 images with pixel sizes <20 m and incidence angles <85°. Hollows were found in 559 images. Locations of the hollows (e.g., crater floor, rim, central peak, plains) were recorded. Shadow-length measurements were made on 280 images, yielding the depths of 1343 individual hollows. The mean depth is 30 m, with a standard deviation of 17 m. We also explored correlations between the geographic locations of hollows and maps provided by the MESSENGER geochemical sensors (X-Ray, Gamma-Ray, and Neutron Spectrometers), including the abundances of Al/Si, Ca/Si, Fe/Si, K, Mg

  20. Use of Eukaryotic Native Small Ribosomal Subunits for the Translation of Globin Messenger RNA

    PubMed Central

    Freienstein, Christoph; Blobel, Günter

    1974-01-01

    A highly active in vitro system for the translation of globin mRNA, resulting in more than 10 rounds of translation, is described. The reconstituted system consists of native small ribosomal subunits of rabbit reticulocytes (as a source of initiation factors as well as small ribosomal subunits), large subunits derived from rat liver polysomes by the puromycin-KCl procedure, and a pH 5 fraction obtained from a Krebs ascites cell high speed supernatant. In this system no differences were found between globin messenger ribonucleoprotein and globin mRNA. Images PMID:4530315

  1. The bacterial second messenger c-di-GMP: probing interactions with protein and RNA binding partners using cyclic dinucleotide analogs.

    PubMed

    Shanahan, Carly A; Strobel, Scott A

    2012-12-14

    The ability of bacteria to adapt to a changing environment is essential for their survival. One mechanism used to facilitate behavioral adaptations is the second messenger signaling molecule bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). c-di-GMP is widespread throughout the bacterial domain and plays a vital role in regulating the transition between the motile planktonic lifestyle and the sessile biofilm forming state. This second messenger also controls the virulence response of pathogenic organisms and is thought to be connected to quorum sensing, the process by which bacteria communicate with each other. The intracellular concentration of c-di-GMP is tightly regulated by the opposing enzymatic activities of diguanlyate cyclases and phosphodiesterases, which synthesize and degrade the second messenger, respectively. The change in the intracellular concentration of c-di-GMP is directly sensed by downstream targets of the second messenger, both protein and RNA, which induce the appropriate phenotypic response. This review will summarize our current state of knowledge of c-di-GMP signaling in bacteria with a focus on protein and RNA binding partners of the second messenger. Efforts towards the synthesis of c-di-GMP and its analogs are discussed as well as studies aimed at targeting these macromolecular effectors with chemically synthesized cyclic dinucleotide analogs.

  2. The bacterial second messenger c-di-GMP: Probing interactions with protein and RNA binding partners using cyclic dinucleotide analogs

    PubMed Central

    Shanahan, Carly A.; Strobel, Scott A.

    2013-01-01

    The ability of bacteria to adapt to a changing environment is essential for their survival. One mechanism used to facilitate behavioral adaptations is the second messenger signaling molecule bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP). c-di-GMP is widespread throughout the bacterial domain and plays a vital role in regulating the transition between the motile planktonic lifestyle and the sessile biofilm forming state. This second messenger also controls the virulence response of pathogenic organisms and is thought to be connected to quorum sensing, the process by which bacteria communicate with each other. The intracellular concentration of c-di-GMP is tightly regulated by the opposing enzymatic activities of diguanlyate cyclases and phosphodiesterases, which synthesize and degrade the second messenger, respectively. The change in the intracellular concentration of c-di-GMP is directly sensed by downstream targets of the second messenger, both protein and RNA, which induce the appropriate phenotypic response. This review will summarize our current state of knowledge of c-di-GMP signaling in bacteria with a focus on protein and RNA binding partners of the second messenger. Efforts towards the synthesis of c-di-GMP and its analogs are discussed as well as studies aimed at targeting these macromolecular effectors with chemically synthesized cyclic dinucleotide analogs. PMID:23108253

  3. MESSENGER Orbital Observations of Large-Amplitude Kelvin-Helmholtz Waves at Mercury's Magnetopause

    NASA Technical Reports Server (NTRS)

    Sundberg, Torbjorn; Boardsen, Scott A.; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Raines, Jim M.; Solomon, Sean C.

    2012-01-01

    We present a survey of Kelvi\\ n-Helmholtz (KH) waves at Mercury's magnetopause during MESSENGER's first Mercury year in orb it. The waves were identified on the basis of the well-established sawtooth wave signatures that are associated with non-linear KH vortices at the magnetopause. MESSENGER frequently observed such KH waves in the dayside region of the magnetosphere where the magnetosheath flow velocity is still sub -sonic, which implies that instability growth rates at Mercury's magnetopau are much larger than at Earth. We attribute these greater rates to the limited wave energy dissipation in Mercury's highly resistive regolith. The wave amplitude was often on the order of ' 00 nT or more, and the wave periods were - 10- 20 s. A clear dawn-dusk asymmetry is present in the data, in that all of the observed wave events occurred in the post-noon and dusk-side sectors of the magnetopause. This asymmetry is like ly related to finite Larmor-radius effects and is in agreement with results from particle-in-cell simulations of the instability. The waves were observed almost exclusively during periods when the north-south component of the magnetosheath magnetic field was northward, a pattern similar to that for most terrestrial KH wave events. Accompanying plasma measurements show that the waves were associated with the transport of magnetosheath plasma into the magnetosphere.

  4. Identification and sequencing of remnant messenger RNAs found in domestic swine (Sus scrofa) fresh ejaculated spermatozoa.

    PubMed

    Yang, C C; Lin, Y S; Hsu, C C; Wu, S C; Lin, E C; Cheng, W T K

    2009-07-01

    The existence of specific messenger RNA remnants contained within freshly ejaculated spermatozoa was described in several species. Those investigations, using high-throughput techniques to screen the population of transcripts in ejaculated spermatozoa, were limited to the probes which mostly derived from nucleic acids of testicular tissues of either human or mice. The objective of this study was to investigate mRNA remnants from ejaculated spermatozoa of the domestic swine (Sus scrofa), a valuable model for biomedical research. A non-redundant 5'-end complementary DNA library was generated from swine ejaculated spermatozoa. After sequence quality verification, 4562 clones remained. These clones were then clustered and assembled into 514 unique sequences including 188 contigs (36.58%) and 326 singletons (63.42%), representing those clusters containing at least two clones and those clusters without having enough similarity with other clones. These unique gene sequences were annotated in Gene Ontology (GO) hierarchy; they included biological processes (38.7%), molecular functions (39.1%) and cellular components (40.3%). Based on the analysis, a broad spectrum of messenger RNAs existed in swine ejaculated spermatozoa and was closely correlated with nucleic acid binding, structural modifications, and transcriptional regulation. All of these categories are considered to have profound effects on the male reproductive system. Therefore, our work provides initial results on potential spermatozoal gene expression for future studies regarding the tightly regulated spermiogenic processes and later fertilization events.

  5. Role of Auf1 in elimination of oxidatively damaged messenger RNA in human cells.

    PubMed

    Ishii, Takashi; Hayakawa, Hiroshi; Sekiguchi, Takeshi; Adachi, Noritaka; Sekiguchi, Mutsuo

    2015-02-01

    In aerobically growing cells, in which reactive oxygen species are produced, the guanine base of RNA is oxidized to 8-oxo-7,8-dihydroguanine, which induces alterations in gene expression. Here we show that the human Auf1 protein, also called HNRNPD, binds specifically to RNA containing this oxidized base and may be involved in cellular processes associated with managing the problems caused by RNA oxidation. Auf1-deficient cells were constructed from human HeLa and Nalm-6 lines using two different targeting procedures. Both types of Auf1-deficient cells are viable, but exhibit growth retardation. The stability of messenger RNA for four different housekeeping genes was determined in Auf1-deficient and -proficient cells, treated with or without hydrogen peroxide. The level of oxidized messenger RNA was considerably higher in Auf1-deficient cells than in Auf1-proficient cells. Auf1 may play a role in the elimination of oxidized RNA, which is required for the maintenance of proper gene expression under conditions of oxidative stress.

  6. Labelling and imaging of single endogenous messenger RNA particles in vivo.

    PubMed

    Spille, Jan-Hendrik; Kubitscheck, Ulrich

    2015-10-15

    RNA molecules carry out widely diverse functions in numerous different physiological processes in living cells. The RNA life cycle from transcription, through the processing of nascent RNA, to the regulatory function of non-coding RNA and cytoplasmic translation of messenger RNA has been studied extensively using biochemical and molecular biology techniques. In this Commentary, we highlight how single molecule imaging and particle tracking can yield further insight into the dynamics of RNA particles in living cells. In the past few years, a variety of bright and photo-stable labelling techniques have been developed to generate sufficient contrast for imaging of single endogenous RNAs in vivo. New imaging modalities allow determination of not only lateral but also axial positions with high precision within the cellular context, and across a wide range of specimen from yeast and bacteria to cultured cells, and even multicellular organisms or live animals. A whole range of methods to locate and track single particles, and to analyze trajectory data are available to yield detailed information about the kinetics of all parts of the RNA life cycle. Although the concepts presented are applicable to all types of RNA, we showcase here the wealth of information gained from in vivo imaging of single particles by discussing studies investigating dynamics of intranuclear trafficking, nuclear pore transport and cytoplasmic transport of endogenous messenger RNA.

  7. Mercury's gravity field from the first six months of MESSENGER data

    NASA Astrophysics Data System (ADS)

    Genova, Antonio; Iess, Luciano; Marabucci, Manuela

    2013-06-01

    The Mercury Surface, Space Environment, GEochemestry, and Ranging (MESSENGER) spacecraft, launched on August 3, 2004, was inserted in a highly elliptical polar orbit around the planet on March 18, 2011. One of the main mission goals is the determination of the interior structure of the planet, enabled by a suite of instruments that includes the radio system and a laser altimeter. Thanks to altimetric and radio observables, the topography and the gravity field of the planet have been retrieved with good accuracy, especially in the north polar region, where the spacecraft altitude is lower. In September, 2011, the radio tracking data of the first 6 months of operations were published with the ancillary information necessary for the MESSENGER orbit determination. This data set offers an excellent opportunity to test the orbit determination procedures developed in view of a similar, but more accurate, experiment hosted onboard BepiColombo, the ESA mission to Mercury. We present here the results of our analysis, which provide the spacecraft orbit, a 20×20 gravity field and a linear update of Mercury's ephemeris. The estimated gravity field is fully compatible with the one published by Smith et al. (2012).

  8. Plasma Distribution in Mercury's Magnetosphere Derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer Observations

    NASA Technical Reports Server (NTRS)

    Korth, Haje; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.; McNutt, Ralph L.

    2014-01-01

    We assess the statistical spatial distribution of plasma in Mercury's magnetosphere from observations of magnetic pressure deficits and plasma characteristics by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The statistical distributions of proton flux and pressure were derived from 10months of Fast Imaging Plasma Spectrometer (FIPS) observations obtained during the orbital phase of the MESSENGER mission. The Magnetometer-derived pressure distributions compare favorably with those deduced from the FIPS observations at locations where depressions in the magnetic field associated with the presence of enhanced plasma pressures are discernible in the Magnetometer data. The magnitudes of the magnetic pressure deficit and the plasma pressure agree on average, although the two measures of plasma pressure may deviate for individual events by as much as a factor of approximately 3. The FIPS distributions provide better statistics in regions where the plasma is more tenuous and reveal an enhanced plasma population near the magnetopause flanks resulting from direct entry of magnetosheath plasma into the low-latitude boundary layer of the magnetosphere. The plasma observations also exhibit a pronounced north-south asymmetry on the nightside, with markedly lower fluxes at low altitudes in the northern hemisphere than at higher altitudes in the south on the same field line. This asymmetry is consistent with particle loss to the southern hemisphere surface during bounce motion in Mercury's offset dipole magnetic field.

  9. Modeling of the Magnetosphere of Mercury at the Time of the First MESSENGER Flyby

    NASA Technical Reports Server (NTRS)

    Benna, Mehdi; Anderson, Brian J.; Baker, Daniel N.; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; Purucker, Michael E.; McNutt, Ralph L.; Raines, Jim M.; McClintock, William E.; Sarantos, Menelaos; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2010-01-01

    The MESSENGER spacecraft flyby of Mercury on 14 January 2008 provided a new opportunity to study the intrinsic magnetic field of the innermost planet and its interaction with the solar wind, The model presented in this paper is based on the solution of the three-dimensional, bi-f1uid equations for solar wind protons and electrons in the absence of mass loading, In this study we provide new estimates of Mercury's intrinsic magnetic field and the solar wind conditions that prevailed at the time of the flyby. We show that the location of the boundary layers and the strength of the magnetic field along the spacecraft trajectory can be reproduced with a solar wind ram pressure P(sub sw) = 6.8 nPa and a planetary magnetic dipole having a magnitude of 210 R(sub M)(exp 3)- nT and an offset of 0.18 R(sub M) to the north of the equator, where R(sub M) is Mercury's radius. Analysis of the plasma flow reveals the existence of a stable drift belt around the planet; such a belt can account for the locations of diamagnetic decreases observed by the MESSENGER Magnetometer. Moreover, we determine that the ion impact rate at the n011hern cusp was four times higher than at the southern cusp, a result that provides a possible explanation for the observed north-south asymmetry in exospheric sodium in the neutral tail.

  10. Thermal Design and Performance of the Gamma-Ray Spectrometer for the MESSENGER Spacecraft

    SciTech Connect

    Burks, M; Cork, C P; Eckels, D; Hull, E; Madden, N W; Miller, W; Goldsten, J; Rhodes, E; Williams, B

    2004-10-13

    A gamma-ray spectrometer (GRS) has been built and delivered to the Mercury MESSENGER spacecraft which launched on August 3, 2004, from Cape Canaveral, Florida. The GRS, a part of seven scientific instruments on board MESSENGER, is based on a coaxial high-purity germanium detector. Gamma-ray detectors based on germanium have the advantage of providing excellent energy resolution, which is critical to achieving the science goals of the mission. However, germanium has the disadvantage that it must operate at cryogenic temperatures (typically {approx}80 K). This requirement is easy to satisfy in the laboratory but difficult near Mercury, which has an extremely hot thermal radiation environment. To cool the detector, a Stirling cycle mechanical cooler is employed. In addition, radiation and conduction techniques a are used to reduce the GRS heat load. Before delivering the flight sensor, a complete thermal prototype was built and tested. The results of these test, including thermal design, radiative and conductive heat loads, and cooler performance are described.

  11. The Calcium Ion Is a Second Messenger in the Nitrate Signaling Pathway of Arabidopsis1

    PubMed Central

    Riveras, Eleodoro; Alvarez, José M.; Vidal, Elena A.; Oses, Carolina; Vega, Andrea; Gutiérrez, Rodrigo A.

    2015-01-01

    Understanding how plants sense and respond to changes in nitrogen availability is the first step toward developing strategies for biotechnological applications, such as improvement of nitrogen use efficiency. However, components involved in nitrogen signaling pathways remain poorly characterized. Calcium is a second messenger in signal transduction pathways in plants, and it has been indirectly implicated in nitrate responses. Using aequorin reporter plants, we show that nitrate treatments transiently increase cytoplasmic Ca2+ concentration. We found that nitrate also induces cytoplasmic concentration of inositol 1,4,5-trisphosphate. Increases in inositol 1,4,5-trisphosphate and cytoplasmic Ca2+ levels in response to nitrate treatments were blocked by U73122, a pharmacological inhibitor of phospholipase C, but not by the nonfunctional phospholipase C inhibitor analog U73343. In addition, increase in cytoplasmic Ca2+ levels in response to nitrate treatments was abolished in mutants of the nitrate transceptor NITRATE TRANSPORTER1.1/Arabidopsis (Arabidopsis thaliana) NITRATE TRANSPORTER1 PEPTIDE TRANSPORTER FAMILY6.3. Gene expression of nitrate-responsive genes was severely affected by pretreatments with Ca2+ channel blockers or phospholipase C inhibitors. These results indicate that Ca2+ acts as a second messenger in the nitrate signaling pathway of Arabidopsis. Our results suggest a model where NRT1.1/AtNPF6.3 and a phospholipase C activity mediate the increase of Ca2+ in response to nitrate required for changes in expression of prototypical nitrate-responsive genes. PMID:26304850

  12. Active site structure and catalytic mechanism of phosphodiesterase for degradation of intracellular second messengers

    NASA Astrophysics Data System (ADS)

    Zhan, Chang-Guo

    2002-03-01

    Phosphodiesterases are clinical targets for a variety of biological disorders, because this superfamily of enzymes regulate intracellular concentration of cyclic nucleotides that serve as the second messengers playing a critical role in a variety of physiological processes. Understanding structure and mechanism of a phosphodiesterase will provide a solid basis for rational design of the more efficient therapeutics. Although a three-dimensional X-ray crystal structure of the catalytic domain of human phosphodiesterase 4B2B was recently reported, it was uncertain whether a critical bridging ligand in the active site is a water molecule or a hydroxide ion. The identity of this bridging ligand has been determined by performing first-principles quantum chemical calculations on models of the active site. All the results obtained indicate that this critical bridging ligand in the active site of the reported X-ray crystal structure is a hydroxide ion, rather than a water molecule, expected to serve as the nucleophile to initialize the catalytic degradation of the intracellular second messengers.

  13. MESSENGER Observation on Reconnection and Structure of Mercury's Magnetotail Lobes and Plasma Sheet

    NASA Astrophysics Data System (ADS)

    Poh, G. K.; Slavin, J. A.; Jia, X.; Raines, J. M.; Sun, W. J.; Gershman, D. J.; Anderson, B. J.

    2014-12-01

    Magnetic reconnection is known to be the most important process for plasma transport and energy conversion in space plasma. MESSENGER observations taken at Mercury have shown that magnetic reconnection is the dominant driver of magnetospheric dynamics and that it is significantly more intense than at Earth. Hence, Mercury provides a perfect natural laboratory to study the structure and reconnection at Mercury's magnetotail as signatures of magnetic reconnections are expected to be more intense and prominent as compared to Earth and the outer planets. Using 4 years of MESSENGER's magnetic field and plasma data, we analyzed 356 plasma sheet crossings. We determined that the B-field magnitude in the magnetotail lobe and plasma sheet follows a power law relation as a function of downstream distance |XMSM|. Statistical studies on the direction of Bz in the plasma sheet suggest that reconnection X-lines are most likely to occur at distance |XMSM| < 2.5RM. Assuming simple pressure balance, we have estimated the plasma beta β in the plasma sheet as a function of |XMSM|. Our results indicate that the beta is higher in the region where X-lines are usually found. Finally, we compared our results at Mercury with previous studies on the terrestrial magnetotail. Our results are consistent with the canonical idea that Mercury's magnetotail is structurally similar to Earth's but with shorter timescale due to more intense reconnection at Mercury.

  14. RG invariants, unification and the role of the messenger scale in General Gauge Mediation

    NASA Astrophysics Data System (ADS)

    Jaeckel, Joerg; Khoze, Valentin V.; Wymant, Chris

    2011-05-01

    In General Gauge Mediation (GGM) all MSSM soft sfermion masses at a high scale Mmess can be parameterised by three a priori independent scales Λ S; 1,2,3( M mess). (Similarly the gaugino masses are given by Λ G; 1,2,3( M mess).) For the first two generations this parameterisation in terms of a set of running Λ S; 1,2,3( μ) — conveniently obtained from appropriate RG invariants — continues to hold all the way down to the electroweak scale. This is not the case for the third generation because of the large Yukawa couplings. Together these two observations imply that the messenger scale is an additional parameter of GGM models. In models where all messengers are in complete GUT multiplets (without significant mass splittings), all Λ S, r are equal at M mess. Starting from the observable mass spectrum at the electroweak scale we present a strategy to determine if this unification occurs and at which scale. This approach uses data accessible at colliders to gain insight into high scale unification physics beyond the unification of gauge couplings.

  15. Time Domain Astronomy with Fermi GBM in the Multi-messenger Era

    NASA Astrophysics Data System (ADS)

    Wilson-Hodge, Colleen A.

    2017-08-01

    As the Multi-Messenger era begins with detections of gravitational waves with LIGO and neutrinos with IceCube, the Fermi Gamma-ray Burst Monitor provides context observations of gamma-ray transients between 8 keV and 40 MeV. Fermi GBM has a wide field of view, high uptime, and both in-orbit triggering and high time resolution continuous data enabling offline searches for weaker transients. GBM detects numerous gamma-ray bursts (GRBs), soft gamma-ray repeaters, X-ray bursters, solar flares and terrestrial gamma-ray flashes. Longer timescale transients, predominantly in our galaxy so far, are detected using the Earth occultation technique and epoch-folding for periodic sources. The GBM team has developed two ground-based searches to enhance detections of faint transients, especially short GRBs. The targeted search uses the time and location of an event detected with another instrument to coherently search the GBM data, increasing the sensitivity to a transient. The untargeted search agnostically searches the GBM data for all directions and times to find weaker transients. This search finds about 80 short GRBs per year, in addition to the 40 per year triggered on-orbit. With its large field of view, high duty cycle and increasingly sophisticated detection methods, Fermi GBM is expected to have a major role in the Multi-Messenger era.

  16. Mercury's High-Latitude Sodium Exosphere: Observations During MESSENGER's Orbital Phase

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Cassidy, T. A.; Vervack, R. J.; Burger, M. H.; Merkel, A. W.; Sarantos, M.; Sprague, A. L.; McClintock, W. E.; Benna, M.; Solomon, S. C.

    2013-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered into orbit about Mercury on March 18, 2011. We now have approximately nine Mercury years of data from orbit. The Ultraviolet and Visible Spectrometer (UVVS) began routine orbital observations of both the dayside and nightside exosphere on March 29, 2011, measuring altitude profiles for all previously detected neutral species except for He and K. We focus here on what we have learned about the sodium exosphere in the polar and high-latitude regions: its spatial, seasonal, and sporadic variation. Observations to date permit delineation of the relative roles of photon-stimulated desorption (PSD) and impact vaporization (IV) from seasonal and spatial effects, as well as of the roles of ions both as sputtering agents and in their possible role to enhance the efficiency of PSD. Correlations of Mercury's neutral sodium exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide insight into the roles of ions and electrons. Models incorporating MAG observations provide a basis for identifying the location and area of the surface exposed to solar wind plasma. Observed scale heights are shown to be due to a mixture of source processes interacting with gravitational and radiation forces.

  17. Expression of P450c17 messenger ribonucleic acid in postmenopausal human ovary tissues.

    PubMed

    José, M; Puche, C; Cabero, A; Cabero, L; Meseguer, A

    1999-03-01

    To investigate the expression of the P450c17 gene in postmenopausal human ovaries compared with normal cycling ovaries. Prospective nonrandomized clinical research study. Servei de Medicina Reproductiva and Centre d'Investigacions en Bioquimica i Biologia Molecular, Hospitals Vall d'Hebron, Barcelona, Spain. Six premenopausal women and four postmenopausal women undergoing bilateral oophorectomy for nonovarian gynecologic disease. Extraction of 10 mL of peripheral venous blood for hormone measurements. Extraction of RNA from surgically removed ovaries for Northern blot, ribonuclease protection, and reverse transcriptase polymerase chain reaction Southern blot assays. Definition of the reproductive cycle state of each patient and determination of the level of P450c17 gene expression in all samples with the use of the semiquantitative reverse transcriptase polymerase chain reaction Southern blot assay. P450c17 messenger RNA levels in postmenopausal ovaries varied considerably between samples. Although the levels were similar to those detected in the early follicular phase, one of the samples had levels as high as those observed in the late follicular phase. Although the degree varied from one sample to another, all the postmenopausal ovaries studied expressed the P450c17 gene at the messenger RNA level. In a sample from a patient with endometrial adenocarcinoma, the level was as high as the levels observed in the late follicular phase.

  18. Compositional variability across Mercury's surface revealed by MESSENGER measurements of variations in thermal neutron count rates

    NASA Astrophysics Data System (ADS)

    Peplowski, P. N.; Lawrence, D. J.; Goldsten, J. O.; Nittler, L. R.; Solomon, S. C.

    2013-12-01

    Measurements by MESSENGER's Gamma-Ray and Neutron Spectrometer (GRNS) have revealed variations in the flux of thermal neutrons across Mercury's northern hemisphere. These variations are interpreted to originate from spatial variations in surface elemental composition. In particular, the measurements are sensitive to the near-surface abundances of elements that absorb thermal neutrons, including major rock-forming elements such as Fe and Ti, minor elements such as Mn and Cl, and rare-earth elements such as Gd and Sm. We have constructed a map of thermal neutron variability across the surface and compared it with known variations in elemental composition and with the distribution of geologic units. Development of the map included the derivation of the macroscopic thermal neutron absorption cross section across the surface, a quantity whose value and variability provides useful constraints on the formation and geochemical evolution of Mercury's crust. Finally, by combining the thermal neutron measurements with previously reported elemental measurements from the GRNS and MESSENGER's X-Ray Spectrometer, we have derived constraints on the abundances of neutron-absorbing elements, including previously unreported limits for some minor and rare-earth elements.

  19. Messenger RNA fluctuations and regulatory RNAs shape the dynamics of a negative feedback loop

    NASA Astrophysics Data System (ADS)

    Rodríguez Martínez, María; Soriano, Jordi; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay

    2010-03-01

    Single-cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single-cell level. As opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of noncoding regulatory RNAs in post-transcription regulation, we also consider the possibility that a regulatory RNA transcript could bind to the messenger RNA and repress translation. Our findings show that the regulatory transcript helps reducing gene expression variability both at the single-cell level and at the cell population level.

  20. Seeing is Believing: Visualizing In Vivo Gene Expression and Secondary Messengers by Magnetic Resonance Imaging.

    NASA Astrophysics Data System (ADS)

    Meade, Thomas J.

    2001-03-01

    MRI offers a non-invasive means to map brain structure and function by sampling the amount, flow or environment of water protons in vivo. Such intrinsic contrast can be augmented by the use of paramagnetic contrast agents in both clinical and experimental settings; however, these agents are little more than anatomical reporters which can at best label individual fluid compartments or distinguish tissues that are magnetically similar but histologically distinct. To permit a more direct imaging of the physiological state of cells or organs, we have prepared and tested several new classes of ``smart" MRI contrast agents that change their influence on nearby water protons in a conditional fashion. The agents modulate fast water exchange with the paramagnetic center, yielding distinct ``strong" and ``weak" relaxivity states. The modualtion is triggered by two types of biological events: i. enzymatic processing of the agent and, ii. binding of an intracelluar messenger. These agents represent the first examples of direct, three dimensional visualization of gene expression and intracellular second messenger concentration in the form of a 3D MR image.

  1. Exosomes as divine messengers: are they the Hermes of modern molecular oncology?

    PubMed Central

    Braicu, C; Tomuleasa, C; Monroig, P; Cucuianu, A; Berindan-Neagoe, I; Calin, G A

    2015-01-01

    Exosomes are cell-derived vesicles that convey key elements with the potential to modulate intercellular communication. They are known to be secreted from all types of cells, and are crucial messengers that can regulate cellular processes by ‘trafficking' molecules from cells of one tissue to another. The exosomal content has been shown to be broad, composed of different types of cytokines, growth factors, proteins, or nucleic acids. Besides messenger RNA (mRNA) they can also contain noncoding transcripts such as microRNAs (miRNAs), which are small endogenous cellular regulators of protein expression. In diseases such as cancer, exosomes can facilitate tumor progression by altering their vesicular content and supplying the tumor niche with molecules that favor the progression of oncogenic processes such as proliferation, invasion and metastasis, or even drug resistance. The packaging of their molecular content is known to be tissue specific, a fact that makes them interesting tools in clinical diagnostics and ideal candidates for biomarkers. In the current report, we describe the main properties of exosomes and explain their involvement in processes such as cell differentiation and cell death. Furthermore, we emphasize the need of developing patient-targeted treatments by applying the conceptualization of exosomal-derived miRNA-based therapeutics. PMID:25236394

  2. Rotation of a Magnetic Cloud: MESSENGER and STEREO-B Observations

    NASA Astrophysics Data System (ADS)

    Good, S. W.; Forsyth, R. J.

    2014-12-01

    Magnetic clouds are a magnetically well ordered subset of CMEs observed in interplanetary space. We report observations of the same magnetic cloud made by the MESSENGER spacecraft at Mercury (then at 0.44 AU) and later by STEREO-B at 1.09 AU, while the two spacecraft were radially aligned in November 2011. Observation with two radially aligned spacecraft allows sampling of approximately the same region of a magnetic cloud, and so allows any evolution that may have occurred within that region during propagation between the two spacecraft to be determined. The flux rope within the November 2011 cloud has been analysed using force-free fitting and minimum variance analysis: it has been estimated that the rope axis rotated from an inclination of approximately 25° relative to the solar equatorial plane at MESSENGER to lie within a few degrees of the plane at STEREO-B. We investigate the hypothesis that this rotation and alignment with the solar equatorial plane is driven by interactions of the cloud with the heliospheric current sheet.

  3. Modeling of the Magnetosphere of Mercury at the Time of the First MESSENGER Flyby

    NASA Technical Reports Server (NTRS)

    Benna, Mehdi; Anderson, Brian J.; Baker, Daniel N.; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; hide

    2010-01-01

    The MESSENGER spacecraft flyby of Mercury on 14 January 2008 provided a new opportunity to study the intrinsic magnetic field of the innermost planet and its interaction with the solar wind, The model presented in this paper is based on the solution of the three-dimensional, bi-f1uid equations for solar wind protons and electrons in the absence of mass loading, In this study we provide new estimates of Mercury's intrinsic magnetic field and the solar wind conditions that prevailed at the time of the flyby. We show that the location of the boundary layers and the strength of the magnetic field along the spacecraft trajectory can be reproduced with a solar wind ram pressure P(sub sw) = 6.8 nPa and a planetary magnetic dipole having a magnitude of 210 R(sub M)(exp 3)- nT and an offset of 0.18 R(sub M) to the north of the equator, where R(sub M) is Mercury's radius. Analysis of the plasma flow reveals the existence of a stable drift belt around the planet; such a belt can account for the locations of diamagnetic decreases observed by the MESSENGER Magnetometer. Moreover, we determine that the ion impact rate at the n011hern cusp was four times higher than at the southern cusp, a result that provides a possible explanation for the observed north-south asymmetry in exospheric sodium in the neutral tail.

  4. The rotational state of Mercury after four years of MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Hussmann, Hauke

    2017-04-01

    We measured the rotational state of Mercury with orbital data from NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. We use accurate co-registration of digital terrain models from stereo images (stereo DTMs) and laser altimeter data to measure the orientation of the rotation axis, the libration amplitude and the mean rotation rate with improved precision. In contrast to our previous study, we use the full four years of near-continuous Mercury Laser Altimeter (MLA) observations and stereo DTMs with a higher spatial coverage. We confirm a large libration amplitude and a mean rotation rate which is significantly higher than the assumed resonant rotation rate based on a perfect 3:2 spin orbit resonance. The estimated orientation of the rotation axis is consistent with the assumption that Mercury occupies a Cassini state. We compare our estimates with values based on Earth-based observations and MESSENGER radio science. Our results confirm that Mercury possesses a liquid outer core and we discuss further implications of our estimates on the interior structure of the planet.

  5. Interplanetary Magnetic Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study

    NASA Technical Reports Server (NTRS)

    Szabo, Adam; Koval, A.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare magnetic field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER magnetic fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

  6. Multi-Messenger Time-Domain Astronomy with the Fermi Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Goldstein, Adam; Fermi GBM Team

    2017-01-01

    With exciting new detections of gravitational waves by LIGO and astrophysical neutrinos by IceCube and ANTARES, the era of multi-messenger time-domain astronomy has arrived. The Fermi Gamma-ray Burst Monitor (GBM) continuously observes the entire sky that is not occulted by the Earth in gamma-rays from 8 keV - 40 MeV with 2 microsecond temporal resolution, and that continuous data is downlinked every few hours. This wealth of near-real-time all-sky data has lead to the development of continuous data searches for gamma-ray events, such as Gamma-Ray Bursts (GRBs), in coincidence with astrophysical neutrinos and gravitational wave events. Additionally, GBM has the ability to localize triggered and un-triggered transient events to a few-degree accuracy, rapidly disseminate the alerts and localization sky maps, and there have been several successful follow-up attempts by wide-field optical telescopes, such as the Palomar Transient Factory, to catch the fading optical afterglow of GBM-triggered GRBs. We discuss the current applications and importance of Fermi GBM in leading multi-messenger time-domain astronomy in the gamma-ray regime.

  7. Multi-Messenger Time-Domain Astronomy with the Fermi Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Connaughton, Valerie; Goldstein, Adam; Fermi GBM - LIGO Group

    2017-01-01

    With exciting new detections of gravitational waves by LIGO and astrophysical neutrinos by IceCube and ANTARES, the era of multi-messenger time-domain astronomy has arrived. The Fermi Gamma-ray Burst Monitor (GBM) continuously observes the entire sky that is not occulted by the Earth in gamma-rays from 8 keV - 40 MeV with 2 microsecond temporal resolution, with regular data downlinks every few hours. This wealth of near-realtime all-sky data has lead to the development of continuous data searches for gamma-ray events, such as Gamma-Ray Bursts (GRBs), in coincidence with astrophysical neutrinos and gravitational wave events. Additionally, GBM has the ability to localize triggered and untriggered transient events to a few-degree accuracy, rapidly disseminate the alerts and localization sky maps within tens of seconds, and there have been several successful follow-up attempts by wide-field optical telescopes, such as the Palomar Transient Factory, to catch the fading optical afterglow of GBM-triggered GRBs. We discuss the current applications and importance of Fermi GBM in leading multi-messenger time-domain astronomy in the gamma-ray regime.

  8. Measurement of the radius of Mercury by radio occultation during the MESSENGER flybys

    NASA Astrophysics Data System (ADS)

    Perry, Mark E.; Kahan, Daniel S.; Barnouin, Olivier S.; Ernst, Carolyn M.; Solomon, Sean C.; Zuber, Maria T.; Smith, David E.; Phillips, Roger J.; Srinivasan, Dipak K.; Oberst, Jürgen; Asmar, Sami W.

    2011-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft completed three flybys of Mercury in 2008-2009. During the first and third of those flybys, MESSENGER passed behind the planet from the perspective of Earth, occulting the radio-frequency (RF) transmissions. The occultation start and end times, recovered with 0.1 s accuracy or better by fitting edge-diffraction patterns to the RF power history, are used to estimate Mercury's radius at the tangent point of the RF path. To relate the measured radius to the planet shape, we evaluate local topography using images to identify the high-elevation feature that defines the RF path or using altimeter data to quantify surface roughness. Radius measurements are accurate to 150 m, and uncertainty in the average radius of the surrounding terrain, after adjustments are made from the local high at the tangent point of the RF path, is 350 m. The results are consistent with Mercury's equatorial shape as inferred from observations by the Mercury Laser Altimeter and ground-based radar. The three independent estimates of radius from occultation events collectively yield a mean radius for Mercury of 2439.2±0.5 km.

  9. Mercury's thermo-chemical evolution from numerical models constrained by Messenger observations

    NASA Astrophysics Data System (ADS)

    Tosi, N.; Breuer, D.; Plesa, A. C.; Wagner, F.; Laneuville, M.

    2012-04-01

    The Messenger spacecraft, in orbit around Mercury for almost one year, has been delivering a great deal of new information that is changing dramatically our understanding of the solar system's innermost planet. Tracking data of the Radio Science experiment yielded improved estimates of the first coefficients of the gravity field that permit to determine the normalized polar moment of inertia of the planet (C/MR2) and the ratio of the moment of inertia of the mantle to that of the whole planet (Cm/C). These two parameters provide a strong constraint on the internal mass distribution and, in particular, on the core mass fraction. With C/MR2 = 0.353 and Cm/C = 0.452 [1], interior structure models predict a core radius as large as 2000 km [2], leaving room for a silicate mantle shell with a thickness of only ~ 400 km, a value significantly smaller than that of 600 km usually assumed in parametrized [3] as well as in numerical models of Mercury's mantle dynamics and evolution [4]. Furthermore, the Gamma-Ray Spectrometer measured the surface abundance of radioactive elements, revealing, besides uranium and thorium, the presence of potassium. The latter, being moderately volatile, rules out traditional formation scenarios from highly refractory materials, favoring instead a composition not much dissimilar from a chondritic model. Considering a 400 km thick mantle, we carry out a large series of 2D and 3D numerical simulations of the thermo-chemical evolution of Mercury's mantle. We model in a self-consistent way the formation of crust through partial melting using Lagrangian tracers to account for the partitioning of radioactive heat sources between mantle and crust and variations of thermal conductivity. Assuming the relative surface abundance of radiogenic elements observed by Messenger to be representative of the bulk mantle composition, we attempt at constraining the degree to which uranium, thorium and potassium are concentrated in the silicate mantle through a broad

  10. Combining MESSENGER Data in Production and Analysis of Digital Elevation Models

    NASA Astrophysics Data System (ADS)

    Becker, K. J.; Howington-Kraus, E.; Thomas, O. H.; Neumann, G. A.; Mazarico, E.; Kirk, R. L.; Weller, L. A.; Edmundson, K. L.; Stephens, J. S.; Sawyers, R. J.; Robinson, M. S.; Solomon, S. C.

    2012-12-01

    The U.S. Geological Survey is combining image and laser altimetry data of Mercury acquired from instruments on the MESSENGER [1] spacecraft for the production and analysis of digital elevation models (DEMs). Precise image measurements that tie Mercury Laser Altimeter (MLA) [2] point data to Mercury Dual Imaging System (MDIS) [3] stereo pairs are obtained using the SOCET SET (®BAE Systems) digital photogrammetry software suite. These measurements will be added to existing Integrated Software for Imagers and Spectrometers [4] control networks used to produce global cartographic basemaps and a global DEM [5]. The MLA points serve as three-dimensional control points in a least-squares bundle adjustment [6] that improves image attitude and/or position parameters and generates improved triangulated ground coordinates for all tie and control points. The resulting point cloud is used to create an updated global DEM controlled to the MLA data. The MLA-to-MDIS image comparison also provides the boresight relationship between the two instruments. For quality assurance, several regional DEMs are created with SOCET SET for selected sites on Mercury that provide variation in terrain and observation conditions. These sites are used in the analysis and comparison of DEMs produced with a variety of methods and data sources (photogrammetry, photoclinometry, stereo techniques, and MLA), similar to comparisons that have been done for HRSC [7] and LRO [8] DEMs. Ultimately orthorectified cartographic products will be created by projecting MDIS images using the highest quality shape model available. [1] Solomon, S.C. et al., 2001. The MESSENGER mission to Mercury: Scientific objectives and implementation, Planet. Space Sci., 49, 1445-1465. [2] Zuber, M.T. et al., 2011. Orbital observations of Mercury with the Mercury Laser Altimeter, EPSC-DPS Joint Meeting, 6, abstract EPSC-DPS2011-278. [3] Hawkins, S.E. III et al., 2007. The Mercury Dual Imaging System on the MESSENGER spacecraft

  11. Electron spin resonance (ESR) dating of hominid-bearing deposits in the Caverna delle Fate, Ligure, Italy

    NASA Astrophysics Data System (ADS)

    Falgueres, Christophe; Yokoyama, Yuji; Bibron, Roland

    1990-07-01

    Stalagmitic floors interstratified with Mousterian deposits from the Caverna delle Fate (Italy) have been dated by the electron spin resonance (ESR) method. Three samples dated fall between 60,000 and 74,000 yr and indicate the age of the Mousterian deposits. They are in good agreement with ages determined by nondestructive γ-ray spectrometry of the human remains from 231Pa/ 235U and 230Th /234U ratios, which are, respectively, 75,000 -14,000+21,000 and 82,000 -25,000+36,000 yr. These dates are consistent with the morphological characteristics of the bones as Neanderthal remains.

  12. Social Mobilization.

    PubMed

    Rogers, Todd; Goldstein, Noah J; Fox, Craig R

    2017-09-25

    This article reviews research from several behavioral disciplines to derive strategies for prompting people to perform behaviors that are individually costly and provide negligible individual or social benefits but are meaningful when performed by a large number of individuals. Whereas the term social influence encompasses all the ways in which people influence other people, social mobilization refers specifically to principles that can be used to influence a large number of individuals to participate in an activity. The motivational force of social mobilization is amplified by the fact that others benefit from the encouraged behaviors, and its overall impact is enhanced by the fact that people are embedded within social networks. This article may be useful to those interested in the provision of public goods, collective action, and prosocial behavior, and we give special attention to field experiments on election participation, environmentally sustainable behaviors, and charitable giving. Expected final online publication date for the Annual Review of Psychology Volume 69 is January 4, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  13. Mobile Transporter

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Space Shuttle Atlantis, STS-110 mission, deployed this railcar, called the Mobile Transporter, and an initial 43-foot section of track, the S0 (S-zero) truss, preparing the International Space Station (ISS) for future spacewalks. The first railroad in space, the Mobile Transporter will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The 27,000-pound S0 truss is the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. The Space Shuttle Orbiter Atlantis, STS-110 mission, was launched April 8, 2002 and returned to Earth April 19, 2002. STS-110's Extravehicular Activity (EVA) marked the first use of the Station's robotic arm to maneuver spacewalkers around the Station.

  14. Follow-up of GW150914 and multi-messenger studies of transient astrophysical sources with the ANTARES neutrino telescope

    NASA Astrophysics Data System (ADS)

    Coleiro, Alexis

    2017-03-01

    By constantly monitoring at least one complete hemisphere of the sky, neutrino telescopes are well designed to detect neutrinos emitted by transient astrophysical sources. In particular, the ANTARES telescope is currently the largest high-energy neutrino detector in the Northern Hemisphere. Searches for ANTARES neutrino candidates coincident with multi-wavelength and multi-messenger transient phenomena are performed by triggering optical, X-ray and radio observations immediately after the detection of an interesting ANTARES event and also by looking for neutrino emission spatially and temporally coincident with transient astrophysical events detected across the electromagnetic spectrum or with new messengers as gravitational-wave signals. The latest results of the multi-messenger analyses performed with ANTARES will be presented in this contribution. In particular, we will focus on the neutrino follow-up performed after the detection of the first gravitation-wave event, GW150914.

  15. Serotonin transporter messenger RNA expression in neural crest-derived structures and sensory pathways of the developing rat embryo.

    PubMed

    Hansson, S R; Mezey, E; Hoffman, B J

    1999-03-01

    A growing body of evidence suggests that serotonin plays an important role in the early development of both neural and non-neural tissues from vertebrate and invertebrate species. Serotonin is removed from the extracellular space by the cocaine- and antidepressant-sensitive serotonin transporter, thereby limiting its action on receptors. In situ hybridization histochemistry was used to delineate serotonin transporter messenger RNA expression during rat embryonic development. Serotonin transporter messenger RNA was widely expressed beginning prior to organogenesis and throughout the second half of gestation. Strikingly, serotonin transporter messenger RNA was detected in neural crest cells, some of which respond to serotonin in vitro, and neural crest-derived tissues, such as autonomic ganglia, tooth primordia, adrenal medulla, chondrocytes and neuroepithelial cells, in the skin, heart, intestine and lung. Within the peripheral sensory pathways, two major cells types were serotonin transporter messenger RNA-positive: (i) sensory ganglionic neurons and (ii) neuroepithelial cells which serve as targets for the outgrowing sensory neurons. Several sensory organs (cochlear and retinal ganglionic cells, taste buds, whisker and hair follicles) contained serotonin transporter messenger RNA by late gestation. The expression of serotonin transporter messenger RNA throughout the sensory pathways from central nervous system relay stations [Hansson S. R. et al. (1997) Neuroscience 83, 1185-1201; Lebrand C. et al. (1996) Neuron 17, 823-835] to sensory nerves and target organs as shown in this study suggests that serotonin may regulate peripheral synaptogenesis, and thereby influence later processing of sensory stimuli. If the early detection of serotonin transporter messenger RNA in skin and gastrointestinal and airway epithelia correlates with protein activity, it may permit establishment of a serotonin concentration gradient across epithelia, either from serotonin in the

  16. Overview of Mercury's ionized exosphere and plasma environment: Results from the first MESSENGER flyby

    NASA Astrophysics Data System (ADS)

    Zurbuchen, Thomas H.; Raines, Jim M.; Gloeckler, George; Krimigis, Stamatios M.; Slavin, James A.; Koehn, Patrick L.; Killen, Rosemary M.; Sprague, Ann L.; McNutt, Ralph L., Jr.; Solomon, Sean C.

    2008-09-01

    Introduction The MESSENGER Fast Imaging Plasma Spectrometer (FIPS) [1] operated during the 14 January 2008 flyby of Mercury (M1) and provided the first composition measurements of Mercury's ionized exosphere and the ion plasma measurements of Mercury's magnetosphere. Ions in the mass/charge range 1 to ~60 amu/e were detected during the flyby period with a time-resolution of 8 s and within an energy range 0.1-13.5 keV/e. We will focus on three key results from this data set. First on the composition measurements of the ionized exosphere. The exosphere is found to be compositionally rich, with five key components in specific ranges of mass/charge. The identification of the specific elements is not unique because of limits to the FIPS counting statistics as well as the finite mass-resolution of FIPS. Second, we focus on the observations of multiply charged C and O observed in the magnetosphere. These particles are likely the result of impact ionization of hot electrons in the magnetosphere, and hence they provide an important indirect characterization of the magnetosphere. Third, we present an overview of the magnetospheric plasma properties as revealed by FIPS. Plasma moments are computed from what are at times partially obstructed velocity distributions. Our plasma moments are compared with magnetohydrodynamic simulations [2] of the magnetosphere. Exosphere Composition The exospheric composition is dominated by components in five ranges of mass/charge (m/q=23- 24, 32-35, 28, 39-40, and 17-19 amu/e) [3]. Even though the identification of the individual components is at times not unambiguous, FIPS measurements provide a rich set of constraints for the violent interactions of the space environment with Mercury's surface. The ionized exosphere is dominated by Na+ and Mg+, with a relative abundance that remains uncertain at this time due to limited counting statistics. The second mass/charge range most likely includes S+, O2 +, and/or H2S+, providing a first possible

  17. MESSENGER Measurements of Radioactive Elements on Mercury: Implications for the Planet's Formation and Evolution

    NASA Astrophysics Data System (ADS)

    Evans, L. G.; Peplowski, P. N.; Hauck, S. A.; McCoy, T. J.; Boynton, W. V.; Ebel, D. S.; Goldsten, J. O.; Hamara, D. K.; Lawrence, D. J.; McNutt, R. L.; Rhodes, E. A.; Nittler, L. R.; Sprague, A. L.; Solomon, S. C.; Starr, R. D.

    2011-12-01

    Measurements of the surface composition of Mercury offers a window into the epoch of planet formation in the inner solar system. Mercury likely preserves a more complete record of early crustal formation than do Venus, Earth, or Mars, each of which experienced extensive and prolonged resurfacing and near-surface alteration since earliest crustal formation. The MErcury Surface, Space ENvironment, GEochemisty, and Ranging (MESSENGER) spacecraft was inserted into Mercury orbit on 18 March 2011 and carries a suite of instruments designed for remote sensing of elemental and mineralogical composition including a Gamma-Ray Spectrometer (GRS). We report measured surface abundances of radioactive elements on Mercury and their implications for hypotheses regarding the planet's formation and thermal evolution. The average surface abundances of radioactive elements over the region of Mercury measured by the GRS are 1150 ± 220 ppm K, 220 ± 60 ppb Th, and 90 ± 20 ppb U. Ratios of the moderately volatile incompatible element K to the refractory incompatible elements Th and U provide insights into the volatile inventory of planetary bodies. The measured K/Th ratio for Mercury (5200 ± 1800) is comparable to values for the other terrestrial planets. By contrast, the lunar K/Th value (360) is an order of magnitude lower, indicative of the depletion of lunar volatiles relative to Earth. Mercury's K/Th ratio, combined with the high abundance of the volatile element sulfur measured by the MESSENGER X-Ray Spectrometer, indicates that the planet has a volatile inventory similar to those of the other terrestrial planets. Hypotheses proposed to explain the unusually high ratio of metal to silicate on Mercury also carry predictions for the ratios of volatile to refractory elements that can be tested against the K, Th, and U abundances measured by MESSENGER. The abundance of K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme

  18. NASA's MESSENGER Finds New Evidence for Water Ice at Mercury's Poles

    NASA Image and Video Library

    2017-09-27

    New observations by the MESSENGER spacecraft provide compelling support for the long-held hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed polar craters. Three independent lines of evidence support this conclusion: the first measurements of excess hydrogen at Mercury's north pole with MESSENGER's Neutron Spectrometer, the first measurements of the reflectance of Mercury's polar deposits at near-infrared wavelengths with the Mercury Laser Altimeter (MLA), and the first detailed models of the surface and near-surface temperatures of Mercury's north polar regions that utilize the actual topography of Mercury's surface measured by the MLA. These findings are presented in three papers published online today in Science Express. Given its proximity to the Sun, Mercury would seem to be an unlikely place to find ice. But the tilt of Mercury's rotational axis is almost zero — less than one degree — so there are pockets at the planet's poles that never see sunlight. Scientists suggested decades ago that there might be water ice and other frozen volatiles trapped at Mercury's poles. The idea received a boost in 1991, when the Arecibo radio telescope in Puerto Rico detected unusually radar-bright patches at Mercury's poles, spots that reflected radio waves in the way one would expect if there were water ice. Many of these patches corresponded to the location of large impact craters mapped by the Mariner 10 spacecraft in the 1970s. But because Mariner saw less than 50 percent of the planet, planetary scientists lacked a complete diagram of the poles to compare with the images. MESSENGER's arrival at Mercury last year changed that. Images from the spacecraft's Mercury Dual Imaging System taken in 2011 and earlier this year confirmed that radar-bright features at Mercury's north and south poles are within shadowed regions on Mercury's surface, findings that are consistent with the water-ice hypothesis. To read

  19. The New View of Mercury after MESSENGER's first year in orbit

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Solomon, S. C.; McNutt, R. L.; Anderson, B. J.; Blewett, D. T.; Evans, L. G.; Gold, R. E.; Murchie, S. L.; Nittler, L. R.; Phillips, R. J.; Slavin, J. A.; Vervack, R. J.; Zuber, M. T.

    2012-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has been making measurements of the innermost planet and its environment nearly continuously since its successful insertion into orbit about Mercury in March 2011. Extensive data from orbit have enabled discoveries about Mercury's composition, geology, interior, magnetic field, and interaction with the solar wind. MESSENGER's first chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction differs from those of the other inner planets and is richer in volatile constituents than predicted by most planetary formation models. Global image mosaics and targeted high-resolution images (to resolutions of 10 m/pixel) reveal that Mercury experienced globally extensive volcanism, including widespread examples of both flood lava and pyroclastic deposits. The tectonic history of Mercury, although dominated by global contractional deformation as first seen by Mariner 10, is more complex than first appreciated, with numerous examples of extensional deformation tied to impact crater and basin modification. Long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history. Several large gravity anomalies, including one candidate mascon, are found in Mercury's northern hemisphere. Crustal thickness in this hemisphere is greater at low latitudes and lessens near the pole, and there is evidence for thinning beneath some impact basins. Measurements of Mercury's moments of inertia require either (i) a mantle density that is too high to be compatible with evidence from elemental remote sensing of Mercury's surface for low mantle abundances of Fe, Al, and Ti or (ii) a solid high-density layer between the silicate mantle and fluid outer core that may be a solidified FeS layer at the top of an Fe-S-Si core. Mercury's magnetic field is dominantly dipolar, but the field is axially symmetric and

  20. New Crater Depth Data for Mercury Derived From MESSENGER Flyby 1 Imagery

    NASA Astrophysics Data System (ADS)

    Herman, M. W.; Chappelow, J. E.; Herrick, R. R.

    2008-12-01

    For small (D < 10 km) craters on Mercury, shadow measurements and photoclinometry are the only viable methods for assessing crater rim-floor depth (d) with the Mariner and MESSENGER Flyby data. A limitation of past shadow measurements was the requirement for simple craters that the shadow pass through crater center in order to get a reliable depth estimate. This restriction means that shadow measurements from the Mariner 10 data were taken along the two narrow longitude bands with acceptable sun angles. Recently, Chappelow (LPSC 2008, Abs. #1441) developed a generalized shadow method that allows determination of crater shape and rim-floor depth for any crater with a conic section of revolution. The boundary of the interior shadow defines a portion of an ellipse. The shape of that ellipse and its offset relative to crater center can be used to solve for crater depth and interior shape (cone, ellipse, parabola, hyperbola). The method does not require that the shadow cross the crater center, but it does require that the viewing angle is close enough to nadir that the rim outline is circular. We are using this method with MESSENGER and Mariner data to expand the amount and areal coverage of depth data for small craters, and to determine the interior shapes of those craters. So far we have estimated depths and shapes for 133 craters (1.0 km < D < 8.0 km) in twelve of the frames from MESSENGER Flyby 1 NAC Mosaic #1 (images range from 117 to 150 m/pixel). Mean d/D is 0.17 (sd 0.04) with a range from 0.09 to 0.29. An exponential fit (in km) is d = (0.178±0.08) D0.89±0.04. Pike's previous results with Mariner data (Mercury, UA Press, 165- 273, 1988) show a unity exponent with a d/D ratio of 0.2, and are reasonably consistent with our work. The shapes of the crater interiors are slightly more conical than parabolic. We have observed some spatial clusters of craters with d/D ratios significantly different than the global mean, and we are investigating whether these areas

  1. Stable isotope variations in the Quaternary epithermal calcite-fluorite deposit at Monte delle Fate near Cerveteri (Latium, central Italy)

    USGS Publications Warehouse

    Masi, U.; O'Neil, J.R.

    1980-01-01

    Carbon, oxygen and hydrogen isotope variations have been measured in samples from the epithermal fluorite vein deposit at Monte delle Fate, Latium. The ranges in ?? 13C and ??18O of calcite are -1.3 to 3.4 and 9.5 to 17.3, respectively. ??D values of water extracted from fluid inclusions are -49 to -39 for calcite and -41 to -34 for fluorite. Fluid inclusion filling temperatures (225??-240??C) and salinites (3.75) are nearly the same for both fluorite and sparry calcite. An elongated form of calcite, of minor abundance, precipitated at lower temperatures. The data indicate that (1) the CO2 involved in the mineralization was provided by the local marine limestones, (2) the waters were meteoric in origin and underwent an 18O shift of ??? 10 permil by exchange with marine country rocks, and (3) all geochemical features can be explained by the action of two hydrothermal fluids. Hot brines recently discovered in the Cesano geothermal area, 30 km to the east, have temperatures and some chemical characteristics similar to the hydrothermal fluids at Monte delle Fate. ?? 1980 Springer-Verlag.

  2. Geophysical investigations at the Paleolitic site Grotta delle Veneri near Parabita (Lecce, Italy)

    NASA Astrophysics Data System (ADS)

    Carrozzo, M. T.; Leucci, G.; Negri, S.; Nuzzo, L.

    2003-04-01

    The human presence in Apulia (southern Italy) is documented since 80.000 years before present. In 1966 near Parabita (Lecce, Italy) in a cave subsequently named "Grotta delle Veneri" human remains belonging to Homo Sapiens Neanderthalensis (Neanderthal) and Homo Sapiens-Sapiens (Cro-Magnon) were recovered together with two small statues of pregnant women ("Veneri") referable to 12.000--10.000 b.C. The local Archaeological Superintendence was interested in assessing the possibility to reconstruct by means of geophysical methods the planimetric position of the cave and further development of its burrows beyond those accessible to speleologists and reported in the underground topographic survey. Both electromagnetic (EM) and electric methods were tested using Ground Penetrating Radar (GPR) with 200 and 500 MHz antennas, GEM300 multi-frequency EM induction device and 2D Electrical Resistivity Tomography (ERT). Despite the rough surface and the presence of numerous obstacles (trees, stone walls and stone piles) limiting the accessible survey area and often preventing a good ground-coupling, the GPR survey successfully located the top of the karstic cave and identified zones of high density of diffraction hyperbolas, interpreted as highly fractured and karstified limestone, in a layer ranging from about 2 m to 6 m below ground. Zones characterised by high density of diffractions due to presence of voids were found also outside the known development of the cave. By means of the GEM 300, both in-phase and quadrature components of the induced EM signal were simultaneously collected at 8 frequencies, from 2025 to 19975 Hz, respectively related to the magnetic susceptibility and apparent conductivity of the soil down to a depth decreasing as the frequency increase. A presumable low contrast in the sought parameter between the highly fractured rock and karstic voids or refilled cavities as well as the presence of metallic debris on the ground allowed a difficult identification

  3. Mobile Support For Logistics

    DTIC Science & Technology

    2016-03-01

    2014, p. 51. .................................................................................9 Figure 3. GCSS-MC Mobile App Architecture...21 Figure 4. GCSS-MC Mobile App Modules...............................................................22...Figure 5. GCSS-MC Mobile App Login Screen .......................................................23 Figure 6. GCSS-MC App Main Screen

  4. Quicklook Air Mobility Modeling

    DTIC Science & Technology

    2002-03-01

    mobility system in AMPCALC. We discussed formulation logic of the mobility cycle. We presented ramp use optimization and tanker optimization...VB)............................................ 10 Visual Basic for Applications ( VBA ...22 The Mobility System In AMPCALC ....................................................................... 22 Tanker Optimization

  5. Volume 4 - Mobile Sources

    EPA Pesticide Factsheets

    Mobile source reference material for activity data collection from the Emissions Inventory Improvement Program (EIIP). Provides complete methods for collecting key inputs to onroad mobile and nonroad mobile emissions models.

  6. Extracts of ECL-cell granules/vesicles and of isolated ECL cells from rat oxyntic mucosa evoke a Ca2+ second messenger response in osteoblastic cells.

    PubMed

    Larsson, B; Gritli-Linde, A; Norlén, P; Lindström, E; Håkanson, R; Linde, A

    2001-03-02

    Surgical removal of the acid-producing part of the stomach (oxyntic mucosa) reduces bone mass through mechanisms not yet fully understood. The existence of an osteotropic hormone produced by the so-called ECL cells has been suggested. These cells, which are numerous in the oxyntic mucosa, operate under the control of circulating gastrin. Both gastrin and an extract of the oxyntic mucosa decrease blood calcium and stimulate Ca2+ uptake into bone. Conceivably, gastrin lowers blood calcium indirectly by releasing a hypothetical hormone from the ECL cells. The present study investigated, by means of fura-2 fluorometry, the effect of extracts of preparations enriched in ECL cell granules/vesicles from rat oxyntic mucosa on mobilization of intracellular Ca2+ in three osteoblast-like cell lines, UMR-106.01, MC3T3-E1 and Saos-2, and of extracts of isolated ECL cells in UMR-106.01 cells. The extracts were found to induce a dose-related rapid increase in intracellular Ca2+ concentrations in the osteoblast-like cells. The response was not due to histamine or pancreastatin, known ECL cell constituents, and could be abolished by pre-digesting the extracts with exo-aminopeptidase. The results show that the increase in [Ca2+](i) reflects a mobilization of Ca2+ from the endoplasmic reticulum. The observation of an increase in [Ca2+](i) also in murine embryonic fibroblasts show that the response is not limited to osteoblastic cells. The finding that the extracts evoked a typical Ca2+ -mediated second messenger response in osteoblastic cells provides evidence for the existence of a novel osteotropic peptide hormone (gastrocalcin), produced in the ECL cells, and supports the view that gastrectomy-induced osteopathy may reflect a lack of this hormone.

  7. Short-Duration Gamma-Ray Burst in the Multi-Messenger Era

    NASA Astrophysics Data System (ADS)

    Lazzati, Davide

    2016-12-01

    The detection of gravitational waves (GW) from binary black hole mergers has been an historical, transformative event in physics and astronomy, heralded by most as the beginning of multi-messenger astronomy. With the increase of sensitivity over the next few years, LIGO and Virgo are predicted to detect mergers from neutron-star (NS) binaries. These are expected to be the first true multi-messenger sources, being the progenitors of short-duration gamma-ray burst (SGRB). The simultaneous detection of a gravitational, electromagnetic, and possibly neutrino signals from the same source would dramatically enhance the scientific output of each individual detection. Important details of the connection between SGRBs and NS binary mergers are however poorly known. These include the nature of the merging compact objects, their equation of state, the physics of SGRB jets - such as their Lorentz factors and opening angles, and the possibility of small temporal delays among the GW, n! eutrino, and gamma-ray signals. In view of the expected increased sensitivity of LIGO during the upcoming observing period and beyond, there is urgent need of improving our understanding of the physics of SGRBs to support the detection of GWs (and possibly neutrinos) and to develop a context in which the expected multi-messenger signal can be properly interpreted and its potential fully exploited. To achieve such goals, we propose to carry out a comprehensive study of relativistic jets from compact binary mergers, exploiting the most recent advances in numerical techniques developed within this research group. The ansatz of this study will be that within a short time after a compact merger a relativistic jet is created. Subsequently, the jet interacts with the merger environment, imprinting a signature that can be detected in the temporal and spectral properties of the prompt radiation, both in its electromagnetic and neutrino components. Analogous dynamical effects have been observed and studied

  8. Effects of local structural transformation of lipid-like compounds on delivery of messenger RNA.

    PubMed

    Li, Bin; Luo, Xiao; Deng, Binbin; Giancola, JoLynn B; McComb, David W; Schmittgen, Thomas D; Dong, Yizhou

    2016-02-26

    Lipid-like nanoparticles (LLNs) have shown great potential for RNA delivery. Lipid-like compounds are key components in LLNs. In this study, we investigated the effects of local structural transformation of lipid-like compounds on delivery of messenger RNA. Our results showed that position change of functional groups on lipid-like compounds can dramatically improve delivery efficiency. We then optimized formulation ratios of TNT-b10 LLNs, a lead material, increasing delivery efficiency over 2-fold. More importantly, pegylated TNT-b10 LLNs is stable for over four weeks and is over 10-fold more efficient than that of its counterpart TNT-a10 LLNs. Additionally, the optimal formulation O-TNT-b10 LLNs is capable of delivering mRNA encoding luciferase in vivo. These results provide useful insights into the design of next generation LLNs for mRNA delivery.

  9. MESSENGER Observations of Extreme Magnetic Tail Loading and Unloading During its Third Flyby of Mercury: Substorms?

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Gloeckler, George; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Schriver, David; Solomon, Sean C.; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's third flyby of Mercury on September 29, 2009, a variable interplanetary magnetic field produced a series of several minute enhancements of the tail magnetic field hy factors of approx. 2 to 3.5. The magnetic field flaring during these intervals indicates that they result from loading of the tail with magnetic flux transferred from the dayside magnetosphere. The unloading intervals were associated with plasmoids and traveling compression regions, signatures of tail reconnection. The peak tail magnetic flux during the smallest loading events equaled 30% of the magnetic flux emanating from Mercury, and may have reached 100% for the largest event. In this case the dayside magnetic shielding is reduced and solar wind flux impacting the surface may be greatly enhanced. Despite the intensity of these events and their similarity to terrestrial substorm magnetic flux dynamics, no energetic charged particles with energies greater than 36 keV were observed.

  10. MESSENGER observations of transient bursts of energetic electrons in Mercury's magnetosphere.

    PubMed

    Ho, George C; Krimigis, Stamatios M; Gold, Robert E; Baker, Daniel N; Slavin, James A; Anderson, Brian J; Korth, Haje; Starr, Richard D; Lawrence, David J; McNutt, Ralph L; Solomon, Sean C

    2011-09-30

    The MESSENGER spacecraft began detecting energetic electrons with energies greater than 30 kilo-electron volts (keV) shortly after its insertion into orbit about Mercury. In contrast, no energetic protons were observed. The energetic electrons arrive as bursts lasting from seconds to hours and are most intense close to the planet, distributed in latitude from the equator to the north pole, and present at most local times. Energies can exceed 200 keV but often exhibit cutoffs near 100 keV. Angular distributions of the electrons about the magnetic field suggest that they do not execute complete drift paths around the planet. This set of characteristics demonstrates that Mercury's weak magnetic field does not support Van Allen-type radiation belts, unlike all other planets in the solar system with internal magnetic fields.

  11. Developmental regulation of a proinsulin messenger RNA generated by intron retention

    PubMed Central

    Mansilla, Alicia; López-Sánchez, Carmen; de la Rosa, Enrique J; García-Martínez, Virginio; Martínez-Salas, Encarna; de Pablo, Flora; Hernández-Sánchez, Catalina

    2005-01-01

    Proinsulin gene expression regulation and function during early embryonic development differ remarkably from those found in postnatal organisms. The embryonic proinsulin protein content decreased from gastrulation to neurulation in contrast with the overall proinsulin messenger RNA increase. This is due to increasing levels of a proinsulin mRNA variant generated by intron 1 retention in the 5′ untranslated region. Inclusion of intron 1 inhibited proinsulin translation almost completely without affecting nuclear export or cytoplasmic decay. The novel proinsulin mRNA isoform expression was developmentally regulated and tissue specific. The proportion of intron retention increased from gastrulation to organogenesis, was highest in the heart tube and presomitic region, and could not be detected in the pancreas. Notably, proinsulin addition induced cardiac marker gene expression in the early embryonic stages when the translationally active transcript was expressed. We propose that regulated unproductive splicing and translation is a mechanism that regulates proinsulin expression in accordance with specific requirements in developing vertebrates. PMID:16179943

  12. Subgenomic messenger RNAs: mastering regulation of (+)-strand RNA virus life cycle.

    PubMed

    Sztuba-Solińska, Joanna; Stollar, Victor; Bujarski, Jozef J

    2011-04-10

    Many (+)-strand RNA viruses use subgenomic (SG) RNAs as messengers for protein expression, or to regulate their viral life cycle. Three different mechanisms have been described for the synthesis of SG RNAs. The first mechanism involves internal initiation on a (-)-strand RNA template and requires an internal SGP promoter. The second mechanism makes a prematurely terminated (-)-strand RNA which is used as template to make the SG RNA. The third mechanism uses discontinuous RNA synthesis while making the (-)-strand RNA templates. Most SG RNAs are translated into structural proteins or proteins related to pathogenesis: however other SG RNAs regulate the transition between translation and replication, function as riboregulators of replication or translation, or support RNA-RNA recombination. In this review we discuss these functions of SG RNAs and how they influence viral replication, translation and recombination. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Ring finger protein 10 is a novel synaptonuclear messenger encoding activation of NMDA receptors in hippocampus

    PubMed Central

    Dinamarca, Margarita C; Guzzetti, Francesca; Karpova, Anna; Lim, Dmitry; Mitro, Nico; Musardo, Stefano; Mellone, Manuela; Marcello, Elena; Stanic, Jennifer; Samaddar, Tanmoy; Burguière, Adeline; Caldarelli, Antonio; Genazzani, Armando A; Perroy, Julie; Fagni, Laurent; Canonico, Pier Luigi; Kreutz, Michael R; Gardoni, Fabrizio; Luca, Monica Di

    2016-01-01

    Synapses and nuclei are connected by bidirectional communication mechanisms that enable information transfer encoded by macromolecules. Here, we identified RNF10 as a novel synaptonuclear protein messenger. RNF10 is activated by calcium signals at the postsynaptic compartment and elicits discrete changes at the transcriptional level. RNF10 is enriched at the excitatory synapse where it associates with the GluN2A subunit of NMDA receptors (NMDARs). Activation of synaptic GluN2A-containing NMDARs and induction of long term potentiation (LTP) lead to the translocation of RNF10 from dendritic segments and dendritic spines to the nucleus. In particular, we provide evidence for importin-dependent long-distance transport from synapto-dendritic compartments to the nucleus. Notably, RNF10 silencing prevents the maintenance of LTP as well as LTP-dependent structural modifications of dendritic spines. DOI: http://dx.doi.org/10.7554/eLife.12430.001 PMID:26977767

  14. Light is a Messenger - The Life and Science of William Lawrence Bragg

    NASA Astrophysics Data System (ADS)

    Hunter, Graeme K.

    2004-10-01

    Light is a Messenger , is the first biography of William Lawrence Bragg, who was only 25 when he won the 1915 Nobel Prize in Physics-the youngest person ever to win a Nobel Prize. It describes how bragg discovered how to use X-rays to determine the arrangement of atoms in crystals and his pivotal role in developing this technique to the point that the structures of the most complex molecules known to man-the proteins and nucelic acids-could be solved. Although Bragg's Nobel Prize was for Physics, his research profoundly affected chemistry and the new field of molecular biology, of which he became a founding figure. This book explains how these revolutionary scientific events occurred while Bragg struggled to emerge from the shadow of his father, Sir William Bragg, and amidst a career-long rivalry with the brilliant American chemist, Linus Pauling.

  15. Interactions of the c-di-GMP riboswitch with its second messenger ligand

    PubMed Central

    Smith, Kathryn D.; Strobel, Scott A.

    2013-01-01

    The c-di-GMP riboswitch is a macromolecular target in the c-di-GMP second messenger signaling pathway. It regulates many genes related to c-di-GMP metabolism as well as genes involved in bacterial motility, virulence and biofilm formation. The riboswitch makes asymmetric contacts to the bases and phosphate backbone of this symmetric dinucleotide. The phylogenetics suggested and mutagenesis has confirmed that this is a flexible motif where variants can make alternative interactions with each of the guanine bases of c-di-GMP. A mutant riboswitch has been designed that can bind a related molecule, c-di-AMP, confirming the most important contacts made to the ligand. The binding kinetics reveal that this is a kinetically controlled riboswitch and mutations to the riboswitch lead to increases in the off-rate. This riboswitch is therefore flexible in sequence as well as kinetic properties. PMID:21428955

  16. Air Force Tests of Sperry Messenger Model with Six Sets of Wings

    NASA Technical Reports Server (NTRS)

    Shoemaker, James M

    1928-01-01

    The purpose of this test was to compare six well-known airfoils, the R.A.F 15, U.S.A. 5, U.S.A. 27, U.S.A. 35-B, Clark Y, and Gottingen 387, fitted to the Sperry Messenger model, at full scale Reynolds number as obtained in the variable density wind tunnel of the National Advisory Committee for Aeronautics; and to determine the scale effect on the model equipped with all the details of the actual airplane. The results show a large decrease in minimum drag coefficient upon increasing the Reynolds number from about one-twentieth scale to full scale. Maximum lift coefficient was increased with increasing scale for all the airfoils except the Gottingen 387, for which it was slightly decreased. A comparison is made between the results of these tests and those obtained from tests made in this tunnel on airfoils alone. (author)

  17. State of the Venus Atmosphere from Venus Express at the time of MESSENGER FLy- By

    NASA Astrophysics Data System (ADS)

    Limaye, S. S.; Markiewicz, W. J.; Titov, D.; Piccione, G.; Baines, K. H.; Robinson, M.

    2007-12-01

    The Venus Monitoring Camera (VMC) and the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instruments on Venus Express spacecraft have been observing Venus since orbit insertion in April 2006. The state of the atmosphere in 2006 was in the form of a hemispheric vortex centered over the south pole, and presumably, another one in the northen hemisphere. The VMC and VIRTIS data have been used to determine cloud motions as well as the structure and organization of the atmospheric circulation from the the data collected since June 2006. In June 2007, the MESSENGER spacecraft flew-past Venus and also observed Venus on approach and departure from Venus. We report on the atmosphere of Venus as it appeared during this period.

  18. Signalling at membrane contact sites: two membranes come together to handle second messengers.

    PubMed

    Levine, Tim P; Patel, Sandip

    2016-04-01

    It is now clear that many intracellular signals result from multiple membrane-bound compartments acting in concert. Membrane contact sites, regions of close apposition between organelles, have emerged as major points of convergence during signalling, as these are places where material is exchanged. The material exchanged can be either water-insoluble molecules such as membrane lipids that are passed directly between organelles, or ions such as Ca(2+). Here we highlight new insights into the role of contacts in signalling by second messengers, including lipid traffic that underpins re-generation of IP3, the regulation of NAADP and store-operated Ca(2+) signals, and possible involvement in cyclic AMP signalling.

  19. Avoiding anomalous newborns: preemptive abortion, treatment thresholds and the case of baby Messenger.

    PubMed

    Gross, M L

    2000-08-01

    In its American context the case of baby Messenger, a preterm infant disconnected from life-support by his father and allowed to die has generated debate about neonatal treatment protocols. Limited by the legal and ethical norms of the United States, this case did not consider treatment protocols that might be available in other countries such as Denmark and Israel: threshold protocols whereby certain classes of newborns are not treated, and preemptive abortion allowing one to choose late-term abortion rather than risk delivery. Each offers a viable and ethically sound avenue for dealing with the economic and social expense of anomalous newborns by aborting or not treating those most likely to burden the health care system. Objections that these protocols are antithetical to American bioethical principles are considered but rejected as each policy answers to economic justice, utility and respect for autonomy.

  20. Messenger Ribonucleic Acid Synthesis and Degradation in Escherichia coli During Inhibition of Translation

    PubMed Central

    Pato, Martin L.; Bennett, Peter M.; Von Meyenburg, Kaspar

    1973-01-01

    Various aspects of the coupling between the movement of ribosomes along messenger ribonucleic acids (mRNA) and the synthesis and degradation of mRNA have been investigated. Decreasing the rate of movement of ribosomes along an mRNA does not affect the rate of movement of some, and possibly most, of the RNA polymerases transcribing the gene coding for that mRNA. Inhibiting translation with antibiotics such as chloramphenicol, tetracycline, or fusidic acid protects extant mRNA from degradation, presumably by immobilizing ribosomes, whereas puromycin exposes mRNA to more rapid degradation than normal. The promoter distal (3′) portion of mRNA, synthesized after ribosomes have been immobilized by chloramphenicol on the promoter proximal (5′) portion of the mRNA, is subsequently degraded. PMID:4583248