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Sample records for mobile messenger dell

  1. 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…

  2. The Monitoring Messenger: Mobile Patient Monitoring for the Pediatric Intensive Care Unit

    ClinicalTrials.gov

    2016-05-24

    To Guide the Design of the Mobile Device Using a Participatory Design Process With PICU Nurses, Respiratory Therapists and Physicians.; To Evaluate the Efficacy of the Mobile Messenger in Helping Nurses, Respiratory Therapists and Physicians Triage Simulated Patients.

  3. Phloem-mobile messenger RNAs and root development

    PubMed Central

    Hannapel, David J.; Sharma, Pooja; Lin, Tian

    2013-01-01

    Numerous signal molecules move through the phloem to regulate development, including proteins, secondary metabolites, small RNAs and full-length transcripts. Several full-length mRNAs have been identified that move long distances in a shootward or rootward direction through the plant vasculature to modulate both floral and vegetative processes of growth. Here we discuss two recently discovered examples of long-distance transport of full-length mRNAs into roots and the potential target genes and pathways for these mobile signals. In both cases, the mobile RNAs regulate root growth. Previously, RNA movement assays demonstrated that transcripts of StBEL5, a transcription factor from the three-amino-loop-extension superclass, move through the phloem to stolon tips to enhance tuber formation in potato (Solanum tuberosum L.). StBEL5 mRNA originates in the leaf and its movement to stolons is induced by a short-day photoperiod. Movement of StBEL5 RNA to roots correlated with increased growth and the accumulation of several transcripts associated with hormone metabolism, including GA2-oxidase1, YUCCA1a and -c, several Aux/IAA types, and PIN1, -2, and -4 was observed. In another example, heterografting techniques were used to identify phloem-mobile Aux/IAA transcripts in Arabidopsis. Movement assays confirmed that these Aux/IAA transcripts are transported into the root system where they suppress lateral root formation. Phloem transport of both StBEL5 and Aux/IAA RNAs are linked to hormone metabolism and both target auxin synthesis genes or auxin signaling processes. The mechanisms of transport for these mobile RNAs, the impact they have on controlling root growth, and a potential transcriptional connection between the BEL1/KNOX complex and Aux/IAA genes are discussed. PMID:23882275

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

    PubMed

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

    2002-12-01

    After 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 degrees 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.

  5. 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

  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. Second Messengers.

    PubMed

    Newton, Alexandra C; Bootman, Martin D; Scott, John D

    2016-01-01

    Second messengers are small molecules and ions that relay signals received by cell-surface receptors to effector proteins. They include a wide variety of chemical species and have diverse properties that allow them to signal within membranes (e.g., hydrophobic molecules such as lipids and lipid derivatives), within the cytosol (e.g., polar molecules such as nucleotides and ions), or between the two (e.g., gases and free radicals). Second messengers are typically present at low concentrations in resting cells and can be rapidly produced or released when cells are stimulated. The levels of second messengers are exquisitely controlled temporally and spatially, and, during signaling, enzymatic reactions or opening of ion channels ensure that they are highly amplified. These messengers then diffuse rapidly from the source and bind to target proteins to alter their properties (activity, localization, stability, etc.) to propagate signaling. PMID:27481708

  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. Second messengers in renin secretion.

    PubMed

    Churchill, P C

    1985-08-01

    The renin-angiotensin-aldosterone system plays a central role in electrolyte homeostasis and in the regulation of arterial blood pressure. The level of activity of this system is determined primarily by the rate at which the kidneys secrete renin into the blood. Although many factors affect renin secretion in vivo, it is certain that all extracellular first messengers affect the activity of the renin-secreting cell by altering its intracellular concentrations of only a few second messengers. The thesis of this review is that free ionic calcium (Ca2+) and cAMP are inhibitory and stimulatory second messengers in renin secretion and that Ca2+ is preeminent. In general, intracellular Ca2+ is controlled by two mechanisms of Ca2+ efflux (Na-Ca exchange; primary active Ca2+ transport) and two mechanisms of Ca2+ influx and/or mobilization (voltage-sensitive Ca channels; receptor-operated channels). There is evidence to suggest that first messengers affect intracellular Ca2+, and therefore renin secretion, by affecting these efflux, influx, and mobilization pathways.

  10. Design, Synthesis, and Identification of 4″α-Azidoethyl-cyclic ADP-Carbocyclic-ribose as a Highly Potent Analogue of Cyclic ADP-Ribose, a Ca(2+)-Mobilizing Second Messenger.

    PubMed

    Sato, Takatoshi; Watanabe, Mizuki; Tsuzuki, Takayoshi; Takano, Satoshi; Murayama, Takashi; Sakurai, Takashi; Kameda, Tomoshi; Fukuda, Hayato; Arisawa, Mitsuhiro; Shuto, Satoshi

    2016-08-11

    Cyclic adenosine diphosphate-carbocyclic-ribose (cADPcR, 2) is a stable equivalent of cyclic adenosine diphosphate-ribose (cADPR, 1), a Ca(2+)-mobilizing second messenger. On the basis of the structure-activity relationship of cADPR-related compounds and three-dimensional structural modeling of cADPcR, we designed and synthesized cyclic-ADP-4″α-azidoethyl carbocyclic-ribose (N3-cADPcR, 3) to demonstrate that it has a highly potent Ca(2+)-mobilizing activity (EC50 = 24 nM). N3-cADPcR will be a useful precursor for the preparation of biological tools effective to investigate cADPR-mediated signaling pathways. PMID:27391373

  11. MESSENGER Laser Altimeter

    NASA Video Gallery

    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...

  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. 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.

  14. 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.

  15. 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

  16. NASA Now: MESSENGER in Orbit

    NASA Video Gallery

    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...

  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. PMID:10177868

  19. 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.

  20. Mercury after three MESSENGER flybys

    NASA Astrophysics Data System (ADS)

    Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Prockter, Louise M.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Murchie, Scott L.; Nittler, Larry R.; Phillips, Roger J.; Zuber, Maria T.

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) space-craft, developed under NASA's Discovery Program, is the first space probe to visit the planet Mercury in more than 30 years. MESSENGER flew by the innermost planet twice in 2008 and once last fall. The flybys confirmed that Mercury's internal magnetic field is dominantly dipolar, with a vector moment closely aligned with the spin axis. MESSENGER detected mag-nesium in Mercury's exosphere, demonstrated that Mercury's anti-sunward neutral tail contains multiple species, and revealed that the distributions of sodium, calcium, and magnesium in the exosphere and tail vary differently with latitude, time of day, and Mercury's position in or-bit, signatures of multiple source processes. MESSENGER's laser altimeter showed that the equatorial topographic relief of Mercury exceeds 5 km, revealed an equatorial ellipticity aligned with the ellipticity in Mercury's gravitational potential, and documented the form of numer-ous impact craters and fault scarps. MESSENGER images provided evidence for widespread volcanism, and candidate sites for volcanic centers were identified. In addition, newly imaged lobate scarps and other tectonic landforms support the hypothesis that Mercury contracted globally in response to interior cooling. The ˜1500-km-diameter Caloris basin, viewed in its entirety for the first time by MESSENGER, was the focus for concentrations of volcanic cen-ters, some with evidence of pyroclastic deposits, and widespread contractional and extensional deformation; smooth plains interior and exterior to the basin are demonstrably younger than the basin-forming event. The ˜700-km-diameter Rembrandt basin, less volcanically infilled than Caloris, was likewise a focus for concentrated magmatic and deformational activity. A ˜290-km-diameter basin contains interior plains that are among the youngest volcanic material on the planet. The nearly global observations of Mercury surface units

  1. 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.

  2. 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

  3. 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.

  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. 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.

  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. Inositol trisphosphate, a novel second messenger in cellular signal transduction

    NASA Astrophysics Data System (ADS)

    Berridge, Michael J.; Irvine, Robin F.

    1984-11-01

    There has recently been rapid progress in understanding receptors that generate intracellular signals from inositol lipids. One of these lipids, phosphatidylinositol 4,5-bisphosphate, is hydrolysed to diacylglycerol and inositol trisphosphate as part of a signal transduction mechanism for controlling a variety of cellular processes including secretion, metabolism, phototransduction and cell proliferation. Diacylglycerol operates within the plane of the membrane to activate protein kinase C, whereas inositol trisphosphate is released into the cytoplasm to function as a second messenger for mobilizing intracellular calcium.

  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. Attenuation of diacylglycerol second messengers

    SciTech Connect

    Bishop, W.R.; Ganong, B.R.; Bell, R.M.

    1986-05-01

    Diacylglycerol(DAG) derived from phosphatidylinositol activates protein kinase C in agonist-stimulated cells. At least two pathways may contribute to the attenuation of the DAG signal: (1) phosphorylation to phosphatidic acid(PA) by DAG kinase(DGK), and (2) deacylation by DAG and monoacylglycerol lipases. A number of DAG analogs were tested as substrates and inhibitors of partially purified pig brain DGK. Two analogs were potent inhibitors in vitro, 1-monooleoylglycerol(MOG,K/sub I/ = 91 ..mu..M) and diotanoylethyleneglycol (diC/sub 8/EG, K/sub I/ = 58 ..mu..M). These compounds were tested in human platelets. DiC/sub 8/EG inhibited (70 - 100%) (/sup 32/P/sub i/) incorporation into PA in thrombin-stimulated platelets. Under these conditions the DAG signal was somewhat long-lived but was still metabolized, presumably by the lipase pathway. MOG treatment elevated DAG levels up to 4-fold in unstimulated platelets. The DAG formed was in a pool where it did not activate protein kinase C. Thrombin-stimulation of MOG-treated platelets resulted in DAG levels 10-fold higher than control platelets. This appears to be due to the inability of these platelets to metabolize agonist-linked DAG via the lipase pathway. The development of specific inhibitors of DAG kinase and DAG lipase, in conjunction with mass quantification of DAG levels as used here, will provide further insights into the regulation of DAG second messengers.

  12. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY BANK ACTIVITIES AND OPERATIONS...) The messenger service maintains ultimate responsibility for scheduling, movement, and routing; (iv... approval to establish a branch pursuant to 12 CFR 5.30....

  13. 12 CFR 7.1012 - Messenger service.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY BANK ACTIVITIES AND OPERATIONS...) The messenger service maintains ultimate responsibility for scheduling, movement, and routing; (iv... approval to establish a branch pursuant to 12 CFR 5.30....

  14. Hydrogen peroxide is a true first messenger.

    PubMed

    Holmquist, L; Stuchbury, G; Steele, M; Münch, G

    2007-01-01

    Hydrogen peroxide has been shown to act as a second messenger mediating intracellular redox-sensitive signal transduction. Here we show that hydrogen peroxide is also able to transmit pro-inflammatory signals from one cell to the other and that this action can be inhibited by extracellularly added catalase. If these data can be further substantiated, hydrogen peroxide might become as important as nitric oxide as a small molecule intercellular (first) messenger.

  15. 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…

  16. File-based data processing on MESSENGER

    NASA Astrophysics Data System (ADS)

    Krupiarz, Christopher J.; Artis, David A.; Calloway, Andrew B.; Frangos, Constantine M.; Heggestad, Brian K.; Holland, Douglas B.; Stratton, William C.

    2006-10-01

    As part of the system software, MESSENGER will be using a file-based system for the transfer and processing of instrument and spacecraft data. The flow of files within the MESSENGER software architecture begins with the receipt of science data by the main processor and the creation of files containing these data by the flight software. The files are then autonomously selected for downlink via a priority-based algorithm, packaged for transmittal via the CCSDS File Delivery Protocol (CFDP), and radiated to the ground. The ground software reconstructs the files via its implementation of CFDP, performs further processing on the file, and sends it to the operations data archive and the Science Operations Center. The MESSENGER spacecraft operations team manages the overall handling of these files through interaction with both the flight and ground systems.

  17. File-based data processing on MESSENGER

    NASA Astrophysics Data System (ADS)

    Krupiarz, Christopher J.; Artis, David A.; Calloway, Andrew B.; Frangos, Constantine M.; Heggestad, Brian K.; Holland, Douglas B.; Stratton, William C.

    2003-11-01

    As part of the system software, MESSENGER will be using a file-based system for the transfer and processing of instrument and spacecraft data. The flow of files within the MESSENGER software architecture begins with the receipt of science data by the main processor and the creation of files containing these data by the flight software. The files are then autonomously selected for downlink via a priority-based algorithm, packaged for transmittal via the CCSDS File Delivery Protocol (CFDP), and radiated to the ground. The ground software reconstructs the files via its implementation of CFDP, performs further processing on the file, and sends it to the operations data archive and the Science Operations Center. The MESSENGER spacecraft operations team manages the overall handling of these files through interaction with both the flight and ground systems.

  18. Nitric oxide: a synchronizing chemical messenger.

    PubMed

    Anbar, M

    1995-06-14

    Nitric oxide (NO) has been recognized as a ubiquitous chemical messenger in a large number of different biological systems. Its chemical properties make it less specific and less controllable than practically any other neurotransmitter or hormone. In view of this, its extensive biological role as a chemical messenger seems surprising. It is suggested that the biological function of NO evolved early in the anaerobic stage of evolution. In view of its low molecular weight, limited interaction with water, and its electrical neutrality, which allow it to diffuse rapidly through the cytoplasm and biomembranes, it is suggested that the need for NO has been retained by and maintained in eukaryote cells because of its ability to affect many biochemical functions simultaneously, acting primarily as an intracellular synchronizing chemical messenger.

  19. Generation of free radicals and messenger function.

    PubMed

    Carlson, J C; Sawada, M

    1995-09-01

    Free radicals are toxic agents that are produced as by-products of metabolic activity. A number of antioxidant mechanisms work to protect cells from damage. Recent evidence indicates, however, that free radicals and related oxidants such as hydrogen peroxide may also have a beneficial role, working as messengers to control cell function. These agents are generated in response to agonists, production is regulated by intracellular signal pathways, and they appear to be used to control particular cellular processes. Free radicals may perform these functions in a number of cell types. Also, they are produced in muscles and there is evidence that they may work as messengers in smooth muscle cells.

  20. 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

  1. 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

  2. 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.; Philips, Roger J.; Prockter, Louise M.; Slavin, James A.; Zuber, M. T.; Finnegan, Eric J.; Grant, David G.

    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

  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. 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.

  5. The Little Spacecraft That Could: MESSENGER and the Messenger Teacher Ambassador Program

    NASA Astrophysics Data System (ADS)

    Garay, D.

    2011-12-01

    For the first time ever, a spacecraft is in orbit around the planet closest to the Sun: Mercury. After a voyage that spanned 5.247 billion miles (8.445 km) with 6 planetary flybys , and 15 laps around the Solar System, The MESSENGER Spacecraft, a NASA Discovery Mission, achieved orbital insertion around Mercury on March 17, 2011. And the science has begun! As a MESSENGER Education Fellow, I have been involved in the program since the mission launched in 2003. The experience has not only empowered my ability to teach space science more effectively, but has also generated an incredible network of scientists, engineers, and educators working together to translate this experience into classroom curricula. As a classroom teacher, I bring my experiences as both a Messenger Fellow and as a PolarTREK teacher back to my classroom. The most current data from MESSENGER's discoveries is available for educational use. I would like to share how The MESSENGER Mission Education Modules can be integrated as successful STEM -related lessons, rich in inquiry and the scientific processes.

  6. 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

  7. 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.

  8. 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.

  9. A mathematical analysis of second messenger compartmentalization

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Levine, Herbert; Rappel, Wouter-Jan

    2008-12-01

    Intracellular compartmentalization of second messengers can lead to microdomains of elevated concentration that are thought to be involved in ensuring signaling specificity. Most experimental evidence for this compartmentalization involves the second messenger adenosine monophosphate (cAMP), which is degraded by phosphodiesterases (PDEs). One possible way of creating these compartments, supported by recent experiments, is to spatially separate the source of cAMP from regions of elevated PDE concentration. To quantify this possibility, we study here a simplified geometry in two dimensions (2D) and in three dimensions (3D), containing a cAMP point source and regions with different degradation constants. Using the symmetry of our geometry, we are able to derive steady state solutions for the cAMP concentration as a function of the system parameters. Furthermore, we show, using analytics as well as direct numerical simulations, that for physiologically relevant time scales the steady state solution has been reached. Our results indicate that elevating the degradation constant throughout the cell, except for a small microdomain surrounding the source, requires an unphysiologically high cellular PDE concentration. On the other hand, a tight spatial relationship of localized PDEs with the cAMP source can result in functional microdomains while maintaining a physiologically plausible cellular PDE concentration.

  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 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. PMID:27313037

  12. [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.

  13. 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

    2008-07-01

    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. PMID:18599776

  14. 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.

  15. 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.

  16. 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

    2008-07-01

    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.

  17. 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.

  18. 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…

  19. 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... in the Federal Register on March 5, 2010 (75 FR 10321). The workers are engaged in employment...

  20. Mercury: A Synthesis from MESSENGER's Extended Mission

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; Nittler, L. R.; McNutt, R. L.

    2012-12-01

    Launched in 2004, MESSENGER flew by Mercury three times in 2008-2009 en route to becoming the first spacecraft to orbit the solar system's innermost planet in March 2011. Orbital observations over the subsequent 21 months have provided the first global view of this nearby but heretofore little studied world. MESSENGER's chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction, low in Fe and high in Mg, differs from those of the other inner planets. Moreover, surface materials are richer in the moderately volatile constituents S and K than predicted by most current models for inner planet formation. Global image mosaics and targeted high-resolution images reveal that Mercury experienced globally extensive volcanism, with large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile-bearing magmas. Bright deposits within impact craters host fresh-appearing, rimless depressions or hollows, often with high-reflectance interiors and halos and likely formed through processes involving the geologically recent loss of volatiles. The large-scale deformational history of Mercury, although dominated by near-global contractional deformation as first seen by Mariner 10, is more complex than first appreciated, with numerous examples of extensional deformation that accompanied impact crater and basin modification. Mercury's magnetic field is dominantly dipolar, but the field is axially symmetric and equatorially asymmetric, a geometry that poses challenges to dynamo models for field generation. The interaction between the solar wind and Mercury's magnetosphere, among the most dynamic in the solar system, serves both to replenish the exosphere and space weather the planet's surface. Plasma ions of planetary origin are seen throughout the sampled volume of Mercury's magnetosphere, with maxima in heavy-ion fluxes in the planet's magnetic

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Exploration of Mercury: The MESSENGER Mission

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA’s Discovery Program, has been collecting orbital observations of Mercury since March 2011. Elemental remote sensing of Mercury’s surface indicates that the moderately volatile elements Na, K, and S are not depleted relative to other terrestrial planets. Orbital images document widespread evidence for ancient volcanic activity ranging from effusive to explosive eruptions. High-resolution images have revealed the presence of irregular rimless depressions or “hollows” likely produced by the loss to diurnal heating or sputtering of some volatile-rich material. Polar deposits in permanently shadowed high-latitude regions are dominated by water ice on the basis of neutron spectrometry, surface reflectance, and thermal modeling with measured topography; in most locations the ice is covered by 10-30 cm of anomalously dark volatile material postulated to consist of complex organic compounds. The tectonic history of Mercury is dominated by greater planetary contraction than previously recognized; long-wavelength changes in topography postdated the emplacement of large expanses of volcanic plains. Gravity and topography measurements indicate that mascons and crustal thinning are associated with some impact basins. Mercury’s internal magnetic field is that of a dipole offset from the planet’s center by ~0.2 Mercury radii, a geometry difficult to reconcile with existing dynamo models. Magnetospheric measurements have revealed a highly time-variable and spatially structured particle environment. Despite complex feedbacks among the exosphere, magnetosphere, and surface, the large-scale structure of the exosphere - dominated by Na, Ca, and Mg - shows seasonal variations in general agreement with those expected from variations in solar flux with Mercury true anomaly but little variation with changing solar conditions. Energetic electron events are

  8. 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.

  9. 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.

  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. 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…

  12. 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

  13. 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…

  14. 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

  15. 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…

  16. 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.

  17. The MESSENGER Venus Flybys: Opportunities for Synergy with Venus Express

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; McNutt, R. L.; Domingue, D. L.; Gold, R. E.; Svedhem, H.; Titov, D.; Helbert, J.

    2006-12-01

    The trajectory of the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, launched by NASA on 3 August 2004 and destined to be the first probe to orbit Mercury, includes two flybys of Venus during the period that the ESA Venus Express mission is operational in Venus orbit. MESSENGER's first Venus flyby occurred on 24 October 2006, at a closest approach distance of 3140 km, but no scientific observations were made because Venus was at superior conjunction and no direct communication with the MESSENGER spacecraft (or with Venus Express) was possible for an extended period. All MESSENGER instruments, however, will be trained on Venus during the spacecraft's second flyby on 6 June 2007, when closest approach will be at 300 km altitude over 12°S, 107°E, in the uplands of Ovda Regio. The Mercury Dual Imaging System will image the night side in near-infrared bands, and color and higher-resolution monochrome mosaics will be made of both the approaching and departing hemispheres. The Ultraviolet and Visible Spectrometer on the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) instrument will make profiles of atmospheric species on the day and night sides as well as observations of the exospheric tail on departure. The Visible and Infrared Spectrograph on MASCS will observe the planet near closest approach to sense cloud chemical properties and near-infrared returns from the lower atmosphere and surface. The laser altimeter will serve as a passive 1064-nm radiometer and will measure the range to one or more cloud decks for several minutes near closest approach. The combined observations of Venus Express and MESSENGER will permit simultaneous and complementary observations of particular value for characterization of the particle and field environment at Venus. MESSENGER's Energetic Particle and Plasma Spectrometer (EPPS) will observe charged particle acceleration at the Venus bow shock and elsewhere. The Magnetometer will

  18. 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

  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. Improving naturalness in gauge mediation with nonunified messenger sectors

    NASA Astrophysics Data System (ADS)

    Calibbi, Lorenzo; Li, Tianjun; Mustafayev, Azar; Raza, Shabbar

    2016-06-01

    We study models of gauge-mediated supersymmetry breaking with messengers that do not belong to complete representations of grand-unified gauge groups. We show that certain setups characterized by a heavy Wino can greatly improve the fine-tuning with respect to models with unified messengers, such as minimal gauge mediation. The typical models with low-tuning feature multi-TeV superparticles, with the exception of the Higgsinos and possibly Bino and right-handed sleptons. As a consequence, the absence of signals for supersymmetry at the LHC is trivially accommodated in our framework. On the other hand, testing these models will be challenging at the LHC. We finally show that the gravitino can be a consistent candidate for cold dark matter, provided a rather low reheating temperature, if a standard thermal history of the Universe is assumed.

  1. Messenger Functions of the Bacterial Cell Wall-derived Muropeptides

    PubMed Central

    Boudreau, Marc A.; Fisher, Jed. F.; Mobashery, Shahriar

    2012-01-01

    Bacterial muropeptides are soluble peptidoglycan structures central to recycling of the bacterial cell wall, and messengers in diverse cell-signaling events. Bacteria sense muropeptides as signals that antibiotics targeting cell-wall biosynthesis are present, and eukaryotes detect muropeptides during the innate immune response to bacterial infection. This review summarizes the roles of bacterial muropeptides as messengers, with a special emphasis on bacterial muropeptide structures and the relationship of structure to the biochemical events that the muropeptides elicit. Muropeptide sensing and recycling in both Gram-positive and Gram-negative bacteria is discussed, followed by muropeptide sensing by eukaryotes as a crucial event to the innate immune response of insects (via peptidoglycan-recognition proteins) and mammals (through Nod-like receptors) to bacterial invasion. PMID:22409164

  2. 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.

  3. Zebrafish Melanophores: A Model for Teaching Second Messenger Systems.

    PubMed

    Jensen, Brian H

    2016-08-01

    A strong literature base supports the notion that active learning improves retention in the science classroom. To that end, a course was designed to allow students to develop their own experiments around a central biological question. The model system used in this particular course is control of melanosome dispersal via second messenger systems in zebrafish (Danio rerio) scales. Students start by applying agonists and antagonists to the cAMP and Ca(2+) second messenger systems, and then can progress to more refined questions with the model system. This project is advantageous because it could be easily adapted to fit the needs of many different courses and ability levels; it is relatively easy to perform; it is enjoyable to teach; and students can be largely given a free reign to decide upon the design of their experiments. PMID:27294411

  4. 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. PMID:25314471

  5. 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.

  6. 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.

  7. 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.

  8. 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

    2008-07-01

    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. PMID:18599778

  9. Activity-Dependent Regulation of Synapses by Retrograde Messengers

    PubMed Central

    Regehr, Wade G.; Carey, Megan R.; Best, Aaron R.

    2011-01-01

    Summary Throughout the brain postsynaptic neurons release substances from their cell bodies and dendrites that regulate the strength of the synapses they receive. Diverse chemical messengers have been implicated in retrograde signaling from postsynaptic neurons to presynaptic boutons. Here we provide an overview of the signaling systems that lead to rapid changes in synaptic strength. We consider the capabilities, specializations and physiological roles of each type of signaling system. PMID:19640475

  10. 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…

  11. 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.

  12. 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(+),

  13. 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.

  14. 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.

  15. MESSENGER's first Mercury flyby: A summary of scientific observations

    NASA Astrophysics Data System (ADS)

    Solomon, Sean C.; McNutt, Ralph L.; Boynton, William V.; Evans, Larry G.; Head, James W.; Krimigis, Stamatios M.; Murchie, Scott; Phillips, Roger J.; Slavin, James A.; Zuber, Maria T.

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, will be the first probe to orbit the planet Mercury in March 2011. Launched in August 2004, MESSENGER successfully completed the first of three flybys of Mercury in January 2008. The Mercury Dual Imaging System acquired an 11-color mosaic of part of the hemisphere not seen by Mariner 10, including the entire Caloris basin; several large monochrome mosaics at a range of resolutions; a series of color frames designed for photometric analysis; and inbound and outbound movies. The Mercury Atmospheric and Surface Composition Spectrometer obtained the first high-resolution spectral reflectance measurements (at ultraviolet to near-infrared wavelengths) of surface composition, conducted limb scans of exospheric species, and mapped the composition and structure of the tail region. The Magnetometer measured Mercury's internal field at low latitudes and documented the major plasma boundaries of Mercury's magnetosphere. The Energetic Particle and Plasma Spectrometer made the first measurements of low-energy ions in Mercury's magnetosphere. The Mercury Laser Altimeter carried out the first space altimetric profile of the planet. Other instruments in the payload provided baseline measurements that will aid in the interpretation of data from the mission orbital phase. Together, the MESSENGER flyby observations have begun to advance our understanding of the innermost planet.

  16. MESSENGER's First Mercury Flyby: A Summary of Scientific Observations

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; McNutt, R. L.; Anderson, B. J.; Boynton, W. V.; Domingue, D. L.; Evans, L. G.; Gold, R. E.; Head, J. W.; Krimigis, S. M.; Murchie, S. L.; Phillips, R. J.; Slavin, J. A.; Zuber, M. T.

    2008-05-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, will be the first probe to orbit the planet Mercury in March 2011. Launched in August 2004, MESSENGER successfully completed the first of three flybys of Mercury in January 2008. The Mercury Dual Imaging System acquired an 11-color mosaic of part of the hemisphere not seen by Mariner 10, including the entire Caloris basin; several large monochrome mosaics at a range of resolutions; a series of color frames designed for photometric analysis; and inbound and outbound movies. The Mercury Atmospheric and Surface Composition Spectrometer obtained the first high-resolution spectral reflectance measurements (at ultraviolet to near-infrared wavelengths) of surface composition, conducted limb scans of exospheric species, and mapped the composition and structure of the tail region. The Magnetometer measured Mercury's internal field at low latitudes and documented the major plasma boundaries of Mercury's magnetosphere. The Energetic Particle and Plasma Spectrometer made the first measurements of low-energy ions in Mercury's magnetosphere. The Mercury Laser Altimeter carried out the first space altimetric profile of the planet. Other instruments in the payload provided baseline measurements that will aid in the interpretation of data from the mission orbital phase. Together, the MESSENGER flyby observations have begun to advance our understanding of the innermost planet.

  17. 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.

  18. 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.

  19. 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.

  20. Ion Transport in Mercury's Magnetosphere during the MESSENGER Flyby

    NASA Astrophysics Data System (ADS)

    Schriver, David; Travnicek, Pavel; Paral, Jan; Slavin, James A.; Sarantos, Menelaos; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Baker, Daniel N.; Killen, Rosemary M.

    2008-09-01

    Abstract Heavy ions including sodium (Na+) are known to populate Mercury's magnetosphere and were observed in situ during the first MESSENGER flyby on January 14, 2008 [1]. A study has been undertaken to examine the transport, distribution, and energization of ions during solar wind conditions corresponding approximately to those that occurred during the MESSENGER flyby. Three-dimensional global hybrid simulations of Mercury's magnetosphere, which provide a realistic self-consistent electric and magnetic field configuration at the time of the flyby [2], are used to trace heavy-ion particle trajectories throughout the system. Because electrons are included only as a massless fluid in the hybrid simulations, electron transport can be examined as well using this technique. To examine solar-wind sputtering as a source for ion ejection from the planet, heavy ions are launched outward from regions near the planet where hybrid simulations show strong particle precipitation, and their trajectories are followed until they either hit the planet or are picked up by the solar wind and lost downstream. The heavy ions can be transported throughout the magnetosphere of Mercury and become accelerated by non-adiabatic processes in the magnetotail current sheet, as well as near reconnection regions. Ions will also be launched from the magnetosheath and other regions to model planetary ion sources as a result of photon-stimulated desorption from the dayside surface of Mercury. The simulated heavy-ion distribution and the energy profile of such ions in Mercury's magnetosphere provide a basis for comparison with MESSENGER flyby data. References [1] Zurbuchen T. H. et al. (2008) Science, in press. [2] Travnicek P. et al. (2007), Geophys. Res. Lett., 34, L05104, doi:10.1029/2006GL028518.

  1. 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

    2010-08-01

    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 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. PMID:20647427

  2. Messenger RNA in early sea-urchin embryos: size classes.

    PubMed

    Nemer, M; Infante, A A

    1965-10-01

    Rapidly labeled RNA from four-cell embryos and blastulae of sea urchins was analyzed by sedimentation and for ability to form DNA-RNA hybrids. The RNA was derived from polyribosomes and from the "gel interphase," an extraction compartment resulting from treatment of whole embryos with phenol and known to be enriched with nuclei. The RNA from both sources displayed a high degree of structural complementarity to DNA. This DNA-like RNA of the polyribosomes sedimented in discrete classes, rather than in the sedimentation continuum demonstrable for the labeled RNA of the gel interphase. Thus messenger RNA appears to emerge in the cytoplasm in discrete size classes. PMID:5837338

  3. 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.

  4. 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,

  5. Phosphatidic acid: an emerging plant lipid second messenger.

    PubMed

    Munnik, T

    2001-05-01

    Evidence is accumulating that phosphatidic acid is a second messenger. Its level increases within minutes of a wide variety of stress treatments including ethylene, wounding, pathogen elicitors, osmotic and oxidative stress, and abscisic acid. Enhanced signal levels are rapidly attenuated by phosphorylating phosphatidic acid to diacylglycerol pyrophosphate. Phosphatidic acid is the product of two signalling pathways, those of phospholipases C and D, the former in combination with diacylglycerol kinase. Families of these genes are now being cloned from plants. Several downstream targets of phosphatidic acid have been identified, including protein kinases and ion channels.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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 his other…

  13. 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

    ..., LLC, Dell Logistics Division, including on-site leased workers from Prologistix, Winston-Salem, North Carolina. The notice was published in the Federal Register on April 23, 2010 (75 FR 21357). At the request... Employment and Training Administration Ceva Freight, LLC, Dell Logistics Division, Including On-Site...

  14. 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.

  15. 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. PMID:26573651

  16. 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

  17. 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.; Lemoine, Frank G.; Margot, Jean-Luc; McNutt, Ralph; Mazarico, Erwan M.; Oberst, Jurgen; Peale, Stanley J.; Perry, Mark; Purucker, Michael E.; Rowlands, David D.; Torrence, Mark H.

    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

  18. 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…

  19. Using Li(+) as the electrochemical messenger to fabricate an aqueous rechargeable Zn-Cu battery.

    PubMed

    Zhang, Hanping; Yang, Tao; Wu, Xin; Zhou, Yisen; Yang, Chao; Zhu, Tian; Dong, Rulin

    2015-04-30

    We propose an aqueous rechargeable Zn-Cu Daniell-type battery. In this system, Li(+) prefers to conduct currents rather than react with the electrodes, while the Zn-Cu electrode couples engage in their electrochemical reactions free from conducting currents. Here Li(+) performs like a messenger and thus could be called the electrochemical messenger.

  20. 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

  1. 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.

  2. 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

    2008-07-01

    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. PMID:18599773

  3. 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.

  4. 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. PMID:19407194

  5. 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. PMID:19407196

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

    2008-07-01

    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. PMID:18599772

  13. 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

  14. 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. PMID:26863196

  15. Hydrogen peroxide as second messenger in lymphocyte activation.

    PubMed

    Reth, Michael

    2002-12-01

    Oxidants such as H2O2 are connected to lymphocyte activation, but the molecular mechanisms behind this phenomenon are less clear. Here, I review data suggesting that by inhibiting protein tyrosine phosphatases, H2O2 plays an important role as a secondary messenger in the initiation and amplification of signaling at the antigen receptor. These findings explain why exposure of lymphocytes to H2O2 can mimic the effect of antigen. In addition, more recent data show that antigen receptors themselves are H2O2-generating enzymes and that the oxidative burst in macrophages seems to play a role not only in pathogen killing but also in the activation of these as well as neighboring cells. Thus, by controlling the activity of the negative regulatory phosphatases inside the cell, H2O2 can set and influence critical thresholds for lymphocyte activation.

  16. 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.

  17. 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.

  18. MESSENGER Multispectral Imaging of the Surface of Mercury

    NASA Astrophysics Data System (ADS)

    Blewett, D. T.; Robinson, M. S.; Denevi, B. W.; Prockter, L. M.; Murchie, S. L.; Gillis-Davis, J. J.; Head, J. W.; Domingue, D. L.; Izenberg, N. R.; McClintock, W. E.; Holsclaw, G. M.; Sprague, A. L.; Vilas, F.

    2008-05-01

    The January 2008 flyby of Mercury by the MESSENGER spacecraft provided the first close-up images of the planet since the Mariner 10 observations of 1974-75. MESSENGER's Mercury Dual Imaging System (MDIS) collected high signal-to-noise-ratio images with two cameras: a high-spatial-resolution broadband visible Narrow Angle Camera (NAC), and a lower-spatial- resolution multispectral Wide Angle Camera (WAC). The WAC has 11 narrow-band color filters with center wavelengths in the range 430 to 1020 nm. A spot spectrometer, the Visible and Infrared Spectrograph (VIRS) component of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS), collected spectra over the range 350 to 1450 nm. The MESSENGER observations cover portions of the planet seen by Mariner 10, as well as new regions not previously imaged by spacecraft. Studies of the Moon over the past forty years — via spectral analysis of returned lunar samples, Earth-based telescopic reflectance spectra, and imaging by the Galileo and Clementine spacecraft, along with theoretical work on the interaction of light with a silicate regolith — provide a framework for interpreting spectra of Mercury. Ferrous iron in silicate minerals (primarily pyroxene and olivine) and glasses has a strong influence on lunar reflectance spectra, producing diagnostic absorption features. "Space weathering," the response of a regolith to micrometeorite bombardment and solar-wind sputtering, tends to reduce the contrast of absorption bands and introduces an overall strong positive ("red") slope to the spectrum. These spectral effects are attributed to tiny metallic iron particles created by vapor deposition during space weathering. Spectrally neutral opaque phases are dark with a flat "bluish" spectral slope and lack strong absorptions. Ilmenite, an iron-titanium oxide, is the key opaque phase in lunar samples. The MESSENGER multispectral observations validate and greatly extend the knowledge gained from analysis of Mariner 10

  19. 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.

  20. 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

  1. Thickness of Mercury's crust from MESSENGER gravity and altimetry data

    NASA Astrophysics Data System (ADS)

    Padovan, S.; Wieczorek, M. A.; Margot, J. L.; Tosi, N.; Solomon, S. C.

    2014-12-01

    The major igneous events that form and shape the crust of a rocky body, such as magma ocean solidification and volcanism, affect the interior thermo-chemical evolution through control on the bulk volatile content, partitioning of heat-producing elements, and heat loss. Therefore, characterizing the crust of a body provides information on that object's origin, differentiation, and subsequent geologic evolution. For Mercury, the crust may hold clues in particular to the still poorly understood processes of formation of this planet. Analysis of geoid-to-topography ratios (GTRs) has been previously applied to infer the thickness of the crust of the Moon, Mars, and Venus. We perform a similar analysis for Mercury with the gravity and altimetry data acquired by the MESSENGER spacecraft. We consider only the northern hemisphere, where the gravity field and topography are well constrained. We assume that Airy isostasy is the principal mechanism of support of variations in topography, and we therefore exclude from the analysis regions that might not be compatible with this assumption, such as large expanses of smooth plains and large impact basins. For a conservative range of densities of the crust, we infer a crustal thickness of 35±18 km (one standard deviation). This new mean value is substantially less than earlier estimates that were based on viscous relaxation of topography, on the relation between the low-degree gravity field and equatorial ellipticity, and on the depth of the brittle-ductile transition as constrained by models of thrust faulting and thermal evolution. This relatively thin crust allows for the possibility of excavation of mantle material during the formation of large impact basins (such as Caloris). Such material might be observed with instruments on MESSENGER and the BepiColombo spacecraft now in development.

  2. First Observations of Mercury's Plasma Mantle As Seen By MESSENGER

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    We present the first observations of Mercury's plasma mantle, a major source for solar wind entry into the planet's magnetosphere. The plasma mantle is created when reconnected magnetic flux tubes at the dayside magnetopause convect anti-sunward with the magnetosheath flow. As these flux tubes are assimilated into the lobes they carry solar wind plasma into the magnetotail. MESSENGER Fast Imaging Plasma Spectrometer (FIPS) and Magnetometer observations have been analyzed for two orbits when the FIPS field of view was well oriented to measure the field-aligned plasma flowing just inside the high-latitude tail magnetopause. For both events, frequent flux transfer events are observed in the magnetosheath, cusp, and nightside magnetopause, indicating that magnetic flux was being added to the magnetotail during these two intervals. The main plasma mantle features at Mercury are similar to those found at Earth: (1) a decrease in plasma density as MESSENGER moves from the magnetopause deeper into the tail lobes; and (2) a clear dispersion in the proton energy distribution, indicating that low-energy protons are being transported equatorward and much deeper into the magnetotail than the higher energy particles that escape by streaming tailward along the lobe field lines before they can E×B drift to the plasma sheet, where E and B are the electric and magnetic fields, respectively. The three-dimensional FIPS plasma distributions confirm that the solar wind protons entering the magnetosphere are indeed flowing anti-sunward with weighted average energies of 0.27 and 0.28 keV, corresponding to a velocity of ~230 km s-1. Diamagnetic depressions, indicating the presence of plasma, are observed in the magnetic field data, and the total field magnitude increases throughout the plasma mantle as the plasma disperses. The proton energy dispersion implies a cross-magnetosphere electric potential of ~20-30 kV, which supports the estimates made from the measurement of dayside

  3. 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

  4. MESSENGER Observations of Suprathermal Electrons in Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Ho, G. C.; Krimigis, S. M.; Starr, R. D.; Vandegriff, J. D.; Baker, D. N.; Gold, R. E.; Anderson, B. J.; Korth, H.; Schriver, D.; McNutt, R. L., Jr.; Solomon, S. C.

    2015-12-01

    The X-Ray Spectrometer (XRS) on the MESSENGER spacecraft, in orbit about Mercury from March 2011 to April 2015, routinely detected fluorescent X-rays induced by low-energy (1-10 keV) electrons. These electrons are in general below the threshold energy response of the Energetic Particle Spectrometer (EPS), one of two sensors on MESSENGER's Energetic Particle and Plasma Spectrometer (EPPS) instrument that measures electrons at energies above 35 keV. Hence, the XRS provided a measure of this lower-energy suprathermal electron population at Mercury. We devised an automated algorithm to select these events from the XRS data set from April 2011 to March 2015 on the basis of the duration, location, and spectral slope of the events. We identified 3102 events in 3900 orbits around Mercury, sampling all Mercury longitudes multiple times over the four-year period. It is evident that these suprathermal electrons were present near the planet at all local times, but the majority were on the nightside of the planet, and a dawn-dusk asymmetry is clearly seen in the data. When the event locations are plotted in simplified B versus L coordinates (where B is the magnitude of the magnetic field, L defines an axisymmetric surface of those lines of magnetic force from the dipole component of Mercury's internal field that intersect the magnetic equator at a distance L RM from the dipole center, and RM is Mercury's radius), several distinct clusters of events can be seen. We infer that all of these are signatures of accelerated electrons being injected from Mercury's tail region to form a quasi-trapped electron distribution at Mercury.

  5. 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

  6. 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

  7. 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…

  8. 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…

  9. Global Controlled Mosaic of Mercury from MESSENGER Orbital Images

    NASA Astrophysics Data System (ADS)

    Becker, K. J.; Weller, L. A.; Edmundson, K. L.; Becker, T. L.; Robinson, M. S.; Solomon, S. C.

    2011-12-01

    The MESSENGER spacecraft entered orbit around Mercury in March 2011. Since then, the Mercury Dual Imaging System (MDIS) has been steadily acquiring images from the monochrome, narrow-angle camera (NAC) and the multispectral, wide-angle camera (WAC). With these images, the U.S. Geological Survey (USGS) is constructing a global, controlled monochrome base map of the planet using the Integrated Software for Imagers and Spectrometers (ISIS3) [1]. Although the characterization of MESSENGER spacecraft's navigation and attitude data has proven to be reliable to date, an element of uncertainty in these parameters is unavoidable. This leads to registration offsets between images in the base map. To minimize these errors, images are controlled using a least-squares bundle adjustment that provides refined spacecraft attitude and position parameters plus triangulated ground coordinates of image tie points. As a first effort, 4542 images (2781 NAC, 1761 WAC G filter) have been controlled with a root mean squared error of 0.25 pixels in image space [2]. A preliminary digital elevation model (DEM) is also being produced from the large number of ground points (~ 47,000) triangulated in this adjustment. The region defined by these points ranges from 80°S to 86°N latitude and 158°E to 358°E longitude. A symmetric, unimodal distribution and a dynamic range of 10.5 km characterize the hypsometry of this area. Minimum, maximum, and mean elevations are -5.0, 5.5, and -0.2 km relative to the mean radius of Mercury (2440 km) as defined by the mission. The USGS will use the DEM and base map for the construction of a registered color (WAC) map of high spatial integrity essential for reliable scientific interpretation of the color data. Ongoing improvements to the base map will be made as new images from MDIS become available, providing continuity in resolution, illumination, and viewing conditions. Additional bundle adjustments will further improve spacecraft attitude. The results from

  10. Mercury's thermo-chemical evolution constrained by MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Tosi, Nicola; Grott, Matthias; Breuer, Doris; Plesa, Ana-Catalina

    2013-04-01

    Low-degree coefficients of Mercury's gravity field as obtained from the MESSENGER's Radio Science experiment combined with estimates of Mercury's spin state permit to compute the normalized polar moment of inertia of the planet (C-MR2) as well as the ratio of the moment of inertia of the mantle to that of the planet (Cm-C). These two parameters provide a strong constraint on the internal mass distribution. With C-MR2 = 0.346 and Cm-C = 0.431 [1], interior structure models predict a large core radius but also a large mantle density. The latter requirement can be met with a relatively standard composition of the silicate mantle for which a core radius of ~ 2000 km is expected [2]. Alternatively, the large density of the silicate shell has been interpreted as a consequence of the presence of a solid FeS layer that could form atop the liquid core under suitable temperature conditions [3]. According to this hypothesis, the thickness of the mantle would be reduced to ~ 300 km only. Additionally, the Gamma-Ray Spectrometer measured a surface abundance of U, Th and K, which hints at a bulk mantle composition comparable to other terrestrial planets [4]. Geological evidence also suggests that volcanism was a globally extensive process even after the late heavy bombardment (LHB) and that northern plains were likely emplaced in a flood lava mode by high-temperature, low-viscosity lava. Finally, the analysis of previously unrecognized compressional tectonic features as revealed by recent MESSENGER images yielded revised estimates of the global planetary contraction, which is calculated to be as high as 4-5 km [5]. We employed the above pieces of information to constrain the thermal and magmatic history of Mercury with numerical simulations. Using 1D-parameterized thermo-chemical evolution models, we ran a large set of Monte-Carlo simulations (~ 10000) in which we varied systematically the thickness of the silicate shell, intial mantle and CMB temperatures, mantle rheology

  11. 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…

  12. 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

  13. 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

  14. 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.

  15. 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

  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. PMID:22438509

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Is inositol (1,3,4,5)-tetrakisphosphate a new second messenger

    SciTech Connect

    Hansen, C.A.; Williamson, J.R.

    1986-05-01

    Hormone-stimulated hydrolysis of inositol (Ins) lipids results in the rapid formation of Ins(1,4,5)P/sub 3/, the second messenger for intracellular Ca/sup 2 +/ mobilization. Recently, a more polar inositol phosphate, Ins(1,3,4,5)P/sub 4/ as well as its probable hydrolysis product Ins(1,3,4)P/sub 3/ have been reported to accumulate in carbachol-stimulated brain slices. Vasopressin addition to hepatocytes prelabeled with (/sup 3/H)-Ins also showed a rapid increase of Ins(1,3,4,5)P/sub 4/, which was similar to that of Ins(1,4,5)P/sub 3/, while the accumulation of Ins(1,3,4)P/sub 3/ was slower. In order to examine whether Ins(1,3,4,5)P/sub 4/ has any functional effects on Ca/sup 2 +/ homeostasis, it was synthesized enzymatically from (/sup 3/H)-Ins(1,4,5)P/sub 3/ using a partially purified phosphoinositol kinase activity from rat brain cortex. (/sup 3/H)-labeled inositol phosphates were separated by anion exchange chromatography and analyzed by HPLC using ammonium formate/phosphoric acid gradient elution. Preliminary experiments indicate that Ins(1,3,4,5)P/sub 4/ up to 10 ..mu..M does not release Ca/sup 2 +/ from vesicular pools in saponin-permeabilized hepatocytes. It has a slight inhibitory effect on Ins(1,4,5)P/sub 3/-induced Ca/sup 2 +/ release. The effect of Ins(1,3,4,5)P/sub 4/ on plasma membrane Ca/sup 2 +/ fluxes are presently being investigated.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    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 orbitalphase searches for additional species in Mercury's exosphere.

  6. 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.

  7. Orbital Normalization of MESSENGER Gamma-Ray Spectrometer Data

    NASA Astrophysics Data System (ADS)

    Rhodes, E. A.; Peplowski, P. N.; Evans, L. G.; Hamara, D. K.; Boynton, W. V.; Solomon, S. C.

    2011-12-01

    The MESSENGER Gamma-Ray Spectrometer (GRS) measures energy spectra of gamma rays emanating from the surface of Mercury. Analysis of these spectra provides elemental abundances of surface material. The MESSENGER mission necessarily provides some data normalization challenges for GRS analysis. So as to keep the spacecraft cool while orbiting the dayside of the planet, the orbits are highly eccentric, with altitudes varying from 200-500 km to ~ 15,000 km. A small fraction of time is spent at the low altitudes where gamma-ray signals are largest, requiring a large number of orbits to yield sufficient counting statistics for elemental analysis. Also, the sunshade must always shield the spacecraft from the Sun, which causes the orientation of the GRS often to be far from nadir-pointing, so the detector efficiency and attenuation of gamma rays from the planet must be known for a wide range of off-nadir orientations. An efficiency/attenuation map for the expected ranges of orientations and energies was constructed in a ground calibration experiment for a limited range of orientations using a nuclear reactor and radioisotope sources, and those results were extended to other orientations by radiation transport computations using as input a computer-aided design model of the spacecraft and its composition. This normalization has allowed abundance determinations of elements K, Th, and U from radioisotopes of these elements in the Mercury regolith during the first quarter of the year-long mission. These results provide constraints on models of Mercury's chemical and thermal evolution. The normalization of gamma-ray spectra for surface elements not having radioisotopes is considerably more complex; these gamma rays come from neutron inelastic-scatter and capture reactions in the regolith, where the neutrons are generated by cosmic ray impact onto the planet. A radiation transport computation was performed to generate the expected count rates in the neutron-generated gamma

  8. 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

  9. Survival strategies in the aquatic and terrestrial world: the impact of second messengers on cyanobacterial processes.

    PubMed

    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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. Exploring the Planet Mercury: One Year of MESSENGER Orbital Observations

    NASA Astrophysics Data System (ADS)

    Solomon, Sean C.

    2012-05-01

    Launched in 2004, MESSENGER flew by Mercury three times in 2008-2009 en route to becoming the first spacecraft to orbit the solar system’s innermost planet in March 2011. MESSENGER’s chemical remote sensing measurements of Mercury’s surface indicate that the planet’s bulk silicate fraction, low in Fe and high in Mg, differs from those of the other inner planets. Moreover, surface materials are richer in the moderately volatile constituents S and K than predicted by most current models for inner planet formation. Global image mosaics and targeted high-resolution images 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-bearing magmas. Bright deposits within impact craters host fresh-appearing, rimless depressions or hollows, often with high-reflectance interiors and halos and likely formed through processes involving the geologically recent loss of volatiles. The large-scale deformational history of Mercury, although dominated by near-global contractional deformation as first seen by Mariner 10, is more complex than first appreciated, with numerous examples of extensional deformation that accompanied impact crater and basin modification. Mercury’s magnetic field is dominantly dipolar, but the field is axially symmetric and equatorially asymmetric, a geometry that poses challenges to dynamo models for field generation. The interaction between the solar wind and Mercury’s magnetosphere, among the most dynamic in the solar system, serves both to replenish the exosphere and space weather the planet’s surface. Plasma ions of planetary origin are seen throughout the sampled volume of Mercury’s magnetosphere, with maxima in heavy-ion fluxes in the planet’s magnetic-cusp regions. Bursts of energetic electrons, seen at most local times, point to an efficient acceleration mechanism

  17. The Mercury Dual Imaging System on the MESSENGER Spacecraft

    NASA Astrophysics Data System (ADS)

    Hawkins, S. Edward; Boldt, John D.; Darlington, Edward H.; Espiritu, Raymond; Gold, Robert E.; Gotwols, Bruce; Grey, Matthew P.; Hash, Christopher D.; Hayes, John R.; Jaskulek, Steven E.; Kardian, Charles J.; Keller, Mary R.; Malaret, Erick R.; Murchie, Scott L.; Murphy, Patricia K.; Peacock, Keith; Prockter, Louise M.; Reiter, R. Alan; Robinson, Mark S.; Schaefer, Edward D.; Shelton, Richard G.; Sterner, Raymond E.; Taylor, Howard W.; Watters, Thomas R.; Williams, Bruce D.

    2007-08-01

    The Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft will provide critical measurements tracing Mercury’s origin and evolution. MDIS consists of a monochrome narrow-angle camera (NAC) and a multispectral wide-angle camera (WAC). The NAC is a 1.5° field-of-view (FOV) off-axis reflector, coaligned with the WAC, a four-element refractor with a 10.5° FOV and 12-color filter wheel. The focal plane electronics of each camera are identical and use a 1,024×1,024 Atmel (Thomson) TH7888A charge-coupled device detector. Only one camera operates at a time, allowing them to share a common set of control electronics. The NAC and the WAC are mounted on a pivoting platform that provides a 90° field-of-regard, extending 40° sunward and 50° anti-sunward from the spacecraft + Z-axis—the boresight direction of most of MESSENGER’s instruments. Onboard data compression provides capabilities for pixel binning, remapping of 12-bit data into 8 bits, and lossless or lossy compression. MDIS will acquire four main data sets at Mercury during three flybys and the two-Mercury-solar-day nominal mission: a monochrome global image mosaic at near-zero emission angles and moderate incidence angles, a stereo-complement map at off-nadir geometry and near-identical lighting, multicolor images at low incidence angles, and targeted high-resolution images of key surface features. These data will be used to construct a global image base map, a digital terrain model, global maps of color properties, and mosaics of high-resolution image strips. Analysis of these data will provide information on Mercury’s impact history, tectonic processes, the composition and emplacement history of volcanic materials, and the thickness distribution and compositional variations of crustal materials. This paper summarizes MDIS’s science objectives and technical design, including the common payload design of the MDIS data processing units, as well as detailed results from ground and early flight

  18. Mercury's Tail Current Sheet from MESSENGER Magnetic Field Measurements

    NASA Astrophysics Data System (ADS)

    Al Asad, M.; Johnson, C. L.; Philpott, L. C.; Anderson, B. J.; Korth, H.; Slavin, J. A.; Solomon, S. C.

    2014-12-01

    We have estimated the spatial variations in the position and average thickness of Mercury's magnetospheric tail current sheet from orbital magnetic field data collected by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. We have investigated the changes in these average properties with varying solar wind conditions and magnetospheric activity. The time-averaged thickness of the current sheet was obtained from superposed epoch analysis (SEA) of the 1-s-averaged vector magnetic field data within ± 10 min of the identified magnetic equator position at different down-tail distances. The average thickness was then estimated from a given SEA by identifying the time interval during which the field completed a rotation from the sunward to the anti-sunward direction, or vice versa, accompanied by a depression in the field magnitude. We have found that the current sheet has a thickness of ~0.8 RM (where RM is Mercury's radius, or 2440 km) close to the planet (~ 1.1 RM) and thins to ~0.2 RM in the far tail region (~2.8 RM). We examined individual orbits to catalogue the existence and number of current sheet crossings encountered on each orbit. These data allow us to (1) determine whether the thickness obtained from the SEA is an actual thickness or an apparent thickness controlled by rapid motions of the current sheet, and (2) estimate the statistical likelihood of observing the current sheet as a function of down-tail distance. For example, some magnetically quiet orbits that cross the magnetic equator at down-tail distances greater than 2 RM do not record a current sheet crossing and appear to cross closed field lines in the vicinity of the magnetic equator, even though they lie in a region in which the tail current sheet is usually observed. This result suggests that the inner (near-planet) edge of the current sheet is not stationary but may move anti-sunward (or sunward) under quiet (or active) magnetospheric conditions.

  19. 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

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

    PubMed

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

    2016-01-01

    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

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

    PubMed

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

    2016-01-01

    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.

  3. 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.

  4. 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,

  5. The Effects of Fasting and Feeding on Preproinsulin Messenger RNA in Rats

    PubMed Central

    Giddings, Stephen J.; Chirgwin, John; Permutt, M. Alan

    1981-01-01

    The purpose of these experiments was to determine whether alterations in preproinsulin messenger (m)RNA activity could account for changes in insulin biosynthesis during fasting and refeeding. Rats were fasted 4 d and then fed for 6, 8, 24, or 48 h. With fasting, body weight decreased 25%, plasma glucose decreased from 6.1 to 2.2 mM, and pancreatic insulin content fell to 40% that of fed animals. Islet RNA decreased to 50% and protein to 55% that of control animals, while islet DNA content remained unchanged. After 6 h of refeeding, islet RNA content increased and was not significantly different from controls. Total islet and preproinsulin mRNA activity was estimated with an mRNA-dependent wheat germ cell-free protein synthesizing system. Preproinsulin and total protein synthesis was linearly dependent upon added RNA at concentrations up to 3 μg. Preproinsulin was identified by its mobility on SDS polyacrylamide gel electrophoresis and by hybrid arrested translation of preproinsulin mRNA. After an 18-h fast, islet mRNA activity decreased 33%; after 4 d mRNA activity decreased to 66% below that of control fed animals. Preproinsulin mRNA activity was decreased, but to a lesser extent, accounting for 20% of total islet protein in fed animals and 46% in the 4-d fasted animals. Total mRNA activity returned to control values after 8 h of refeeding and increased to 150% of controls at 24 and 48 h. Preproinsulin mRNA activity increased more rapidly on refeeding. By 8 h it was 160% of controls. To determine whether changes in preproinsulin mRNA activity were associated with changes in the amount of preproinsulin mRNA, nucleic acid hybridization analysis was performed. Pancreatic RNA from fed and fasted animals was electrophoresed on agarose gels, transferred to diazophenylthio paper, and hybridized to 32P-labeled preproinsulin complementary (c)-DNA. This analysis demonstrated that changes in mRNA activity were associated with changes in the amount of hybridizable m

  6. Messages about the Messengers: Reception and Review of ``Astronomy's New Messengers,'' The Laser Interferometer Gravitational-wave Observatory's Interactive Public Exhibition

    NASA Astrophysics Data System (ADS)

    Rankins, Brooke; Cavagliá, Marco

    2010-10-01

    The Laser Interferometer Gravitational-wave Observatory (LIGO) is an endeavor to directly confirm the existence of gravitational waves, funded by the National Science Foundation. As a publicly funded research project, it is both within its directive and within its best interest to educate and inform the public at large of its efforts. The Education and Public Outreach (EPO) group within LIGO, under the direction of Marco Cavaglià, has developed an interactive exhibit to educate, explain and showcase LIGO to the general public. The exhibit, entitled ``Astronomy's New Messengers,'' debuted at the World Science Festival in New York City, and includes features to explain gravitational waves and their possible sources, an interferometer, the space-time fabric model, and the difficulties in identifying a gravitational wave. The exhibit visitors were asked to complete a survey about their experience at ``Astronomy's New Messengers,'' and the presentation will report the survey results, and explore the full exhibit's reception by the general public.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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... Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in my... application must demonstrate that a certificate is necessary in order to prevent the curtailment...

  12. 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... Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in my... application must demonstrate that a certificate is necessary in order to prevent the curtailment...

  13. 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 appeal to farm…

  14. 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 students, where…

  15. MESSENGER soft X-ray observations of the quiet solar corona

    NASA Astrophysics Data System (ADS)

    Schwartz, Richard A.; Hudson, Hugh S.; Tolbert, Anne K; Dennis, Brian R.

    2014-06-01

    In a remarkable result from their "SphinX" experiment, Sylwester et al. (2012) found a non-varying base level of soft X-ray emission at the quietest times in 2009. We describe comparable data from the soft X-ray monitor on board MESSENGER (en route to Mercury) which had excellent coverage both in 2009 and during the true solar minimum of 2008. These observations overlap SphinX's and also are often exactly at Sun-MESSENGER-Earth conjunctions. During solar minimum the Sun-MESSENGER distance varied substantially, allowing us to use the inverse-square law to help distinguish the aperture flux (ie, solar X-rays) from that due to sources of background in the 2-5 keV range. The MESSENGER data show a non-varying background level for many months in 2008 when no active regions were present. We compare these data in detail with those from SphinX. Both sets of data reveal a different behavior when magnetic active regions are present on the Sun, and when they are not.Reference: Sylwester et al., ApJ 751, 111 (2012)

  16. 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…

  17. 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.

  18. 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... handicapped workers employed under special certificates as provided in section 14 of the Act. (a) With respect... education, or handicapped workers employed at special minimum hourly rates under Special...

  19. 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 systems. 77.704-11 Section 77.704-11 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding...

  20. 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.

  1. Topography of Mercury from stereo images: Regional terrain models from MESSENGER orbital mapping

    NASA Astrophysics Data System (ADS)

    Preusker, F.; Oberst, J.; Head, J. W.; Robinson, M. S.; Watters, T. R.; Solomon, S. C.

    2012-09-01

    In March 2011 the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered orbit about Mercury [1]. The spacecraft is equipped with the Mercury Dual Imaging System (MDIS) [2] consisting of a wide-angle camera (WAC) and a narrow-angle camera (NAC) coaligned on a pivot platform. During its first Mercury solar day (~176 Earth days), MESSENGER acquired several thousand images to create a monochrome base map using the WAC for the northern hemisphere and NAC for the southern hemisphere, respectively, from its highly eccentric near-polar orbit. In September 2011, with the beginning of the second Mercury day, MESSENGER started acquiring a complementary image dataset under high emission angles (by tilting the camera) but similar Sun elevation and azimuth. The combination of both base maps enables us to analyze the images stereoscopically and to generate digital terrain models (DTMs). The DTMs are particularly important for the southern hemisphere, most parts of which are out of range of MESSENGER's Mercury Laser Altimeter (MLA).

  2. 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.

  3. 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…

  4. [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.

  5. [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. PMID:27183512

  6. Distribution of angiotensin type-1 receptor messenger RNA expression in the adult rat brain.

    PubMed

    Lenkei, Z; Palkovits, M; Corvol, P; Llorens-Cortes, C

    1998-02-01

    Angiotensin II and angiotensin III in the brain exert their various effects by acting on two pharmacologically well-defined receptors, the type-1 (AT1) and the type-2 (AT2) receptors. Receptor binding autoradiography has revealed the dominant presence of AT1 in brain nuclei involved in cardiovascular, body fluid and neuroendocrine control. The cloning of the AT1 complementary DNA has revealed the existence of two receptor subtypes in rodents, AT1A and AT1B. Using specific riboprobes for in situ hybridization, we have previously shown that the AT1A messenger RNA is predominantly expressed in the rat forebrain; in contrast the AT1B subtype predominates in the anterior pituitary. Using a similar technical approach, the aim of the present study was to establish the precise anatomical localization of cells synthetising the AT1A receptor in the adult rat brain. High AT1A messenger RNA expression was found in the vascular organ of the lamina terminalis, the median preoptic nucleus, the subfornical organ, the hypothalamic periventricular nucleus, the parvocellular parts of the paraventricular nucleus, the nucleus of the solitary tract and the area postrema, in agreement with previous autoradiographic studies, describing a high density of AT1 binding sites in these nuclei. In addition, AT1A messenger RNA expression was detected in several brain areas, where no AT1 binding was reported previously. Thus, we identify strong expression of AT1A messenger RNA expression in scattered cells of the lateral parts of the preoptic region, the lateral hypothalamus and several brainstem nuclei. In none of these structures was the AT1B messenger RNA detectable at the microscopic level. In conclusion, it is suggested that angiotensins may exert their central effects on body fluid and cardiovascular homeostasis mainly via the AT1A receptor subtype. PMID:9483539

  7. 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…

  8. 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…

  9. 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

    ... Carolina. The notice was published in the Federal Register on April 23, 2010 (75 FR 21357). The notice was... notice was published in the Federal Register on July 1, 2010 (75 FR 38128-38129). At the request of the... Employment and Training Administration CEVA Freight, LLC, Dell Logistics Division, Including On-Site...

  10. 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.

  11. Modeling Mobility

    NASA Astrophysics Data System (ADS)

    Berl, Andras

    In wireless networks, communication can take place based on an infrastructure (e.g. WLAN access point or GPRS base station) or it can take place in adhoc mode, where mobile devices are connected directly to each other and care for the routing by themselves (mobile ad-hoc networks). When such wireless networks are investigated and simulations are performed, it is often necessary to consider the movement of entities within the simulated environment.

  12. 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.

  13. 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.

  14. 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. PMID:25693494

  15. 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. PMID:25953822

  16. 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. PMID:19407195

  17. 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

    2008-07-01

    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. PMID:18599768

  18. 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

    2010-08-01

    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. PMID:20647421

  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

    2010-08-01

    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. PMID:20647422

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  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. 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.

  7. Heterogeneity of the 5' terminus of hen ovalbumin messenger ribonucleic acid.

    PubMed Central

    Malek, L T; Eschenfeldt, W H; Munns, T W; Rhoads, R E

    1981-01-01

    The 5'-terminal sequence of hen ovalbumin mRNA was investigated using a novel labeling method. Ovalbumin mRNA was purified by hybridization to complementary DNA coupled to cellulose. The mRNA thus purified was shown to be 97.9% pure by hybridization with plasmid DNA containing sequences to the messengers coding for conalbumin and ovomucoid, the next two most abundant messengers of oviduct. After digestion with RNase T1 and alkaline phosphatase, 5'-terminal capped oligonucleotides were selected by binding to anti-m7G-Sepharose. These were then labeled using RNA ligase and [5'-32P]pCp, separated by two-dimensional gel electrophoresis, and sequenced by partial digestion with base-specific ribonucleases. A nested set of three capped oligonucleotides was identified. Their structures and relative abundances were m7GpppAUACAG, 3% m7GpppACAUACAG, 61+; and m7GpppGUACAUACAG, 36%. Images PMID:6785728

  8. 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 cloudʼs 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 cloudʼs 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.

  9. Mercury's Internal Magnetic Field: Results from MESSENGER's Low-altitude Campaign

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.; Purucker, M. E.; Philpott, L. C.; Korth, H.; Anderson, B. J.; Winslow, R. M.; Al Asad, M.; Nicholas, J. B.; Tsyganenko, N. A.; Hauck, S. A., II; Head, J. W., III; Phillips, R. J.; Solomon, S. C.

    2014-12-01

    Magnetic field measurements made by the MESSENGER spacecraft in orbit around Mercury have shown that, to first order, Mercury's internal field can be described by an axially aligned dipole, offset by 479 km north of the geographic equator (the offset axial dipole, hereafter OAD). Near-periapsis MESSENGER magnetic field measurements at altitudes less than 200 km have been obtained since April 2014. We use these observations, together with higher altitude data from orbits that have been characterized with low magnetic activity , to identify non-OAD internal field structure and to establish whether it is of crustal and/or core origin. Magnetospheric models developed with MESSENGER data allow estimated contributions from magnetopause, magnetotail, and OAD fields to be subtracted from vector magnetic field measurements, and the sources of residual signatures to be examined. For measurements made at spacecraft altitudes above 200 km, determining the magnitude and sources of additional regional and global-scale contributions to the internal field has been challenging because of MESSENGER's orbit geometry and because the residuals are dominated by additional external fields that are organized in the local time frame and that vary with magnetospheric activity. After accounting for the large-scale magnetospheric fields, any additional external field contributions to the residual fields are estimated empirically in the local time frame. We investigate crustal and core contributions to the remaining signals, in particular to the low altitude signals, by examining repeatability in the body-fixed frame and using global (spherical harmonic) and local (equivalent source dipole) basis functions with regularization. Crustal sources associated with large-scale regional geological provinces such as the northern lowlands, the northern rise, and major impact basins are investigated and equivalent spherical harmonic core/crustal field spectra computed.

  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. Longitudinal spread of second messenger signals in isolated rod outer segments of lizards

    PubMed Central

    Gray-Keller, Mark; Denk, Winfried; Shraiman, Boris; Detwiler, Peter B

    1999-01-01

    In vertebrate rods activation of the phototransduction cascade by light triggers changes in the concentrations of at least two diffusible intracellular second messengers (cGMP and Ca2+) whose actions depend on how far they spread from their site of production or entry. To address questions about their spatial spread, cell-attached patch current recording and fluorescence imaging of Calcium Green-dextran were used to measure the longitudinal spread of cGMP and Ca2+, respectively, in functionally intact isolated Gecko gecko lizard rod outer segments under whole-cell voltage clamp. The light-evoked changes in cGMP and Ca2+ concentrations decayed with distance from a site of steady focal activation by two-photon absorption of 1064 nm light with similar decay lengths of ≈3.5 μm. These results can be understood on the basis of a quantitative model of coupled diffusible intracellular messengers, which is likely to have broad relevance for second messenger signalling pathways in general. The decay length for the spread of adaptation from a site of steady local illumination was about 8 μm, i.e. substantially longer than the decay lengths measured for the spread of cGMP and Ca2+. There are a number of factors, however, that could broaden the apparent relationship between functional changes in the light response and the concentration of a diffusible messenger. For these reasons the measured decay length is an upper limit estimate of the spread of adaptation and does not rule out the possibility that Ca2+ and/or cGMP carry the adaptation signal. PMID:10457083

  12. 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.

  13. A study of magnetic clouds observed by MESSENGER and Venus Express

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    We present an analysis of a recently compiled list of magnetic clouds observed by the MESSENGER and Venus Express spacecraft. Despite their planetary focus, both spacecraft spent significant amounts of time in the solar wind, allowing transient solar wind structures such as magnetic clouds to be observed. The clouds were observed at a range of heliocentric distances (at 0.72 AU by Venus Express, and from 1 to 0.3 AU by MESSENGER) over the course of a significant fraction of a solar cycle (2006 to 2013 by Venus Express, and 2007 to 2012 by MESSENGER). Neither spacecraft carried a dedicated solar wind plasma instrument, and so the clouds have been identified using magnetic field data only: a coherent rotation of the magnetic field direction lasting for at least four hours that coincides with a field strength above that of the ambient solar wind were the primary identification criteria. The approximate orientations of the magnetic clouds relative to the solar equatorial plane have been found. We consider the frequency distribution of these orientations, and their dependence on heliocentric distance and the solar magnetic field configuration. We also use these observations, in conjunction with observations at 1 AU, to estimate the likelihood that two spacecraft will encounter the same magnetic cloud as a function of the spacecraft's azimuthal separation.

  14. 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.

  15. A hybrid simulation of Mercury’s magnetosphere for the MESSENGER encounters in year 2008

    NASA Astrophysics Data System (ADS)

    Wang, Y.-C.; Mueller, J.; Motschmann, U.; Ip, W.-H.

    2010-09-01

    The latest measurements from the two encounters of the MESSENGER spacecraft in year 2008 have discovered several interesting features of the magnetosphere of Mercury. We have performed high-resolution 3D hybrid model calculations to simulate the solar wind interaction with the Hermean magnetosphere during the first two Mercury encounters of the MESSENGER spacecraft in 2008. It is found that the global structure of the Hermean magnetosphere is significantly controlled by the direction of the interplanetary magnetic field. The bow shock size and shape and the magnetotail configuration have very large differences in these two encounters with northward-pointing and southward-pointing interplanetary magnetic field, respectively. Comparisons are also given with the observed magnetic field profiles and the computational results. In general, good agreement can be found including the interesting feature of the relatively thick magnetopause current layer at outbound measurements. Our work shows that 3D hybrid simulation is a promising method to study in detail the Hermean magnetosphere in parallel with the post-MOI observations of the MESSENGER spacecraft and the Bepi-Colombo mission in future.

  16. Control of a Salmonella virulence locus by an ATP-sensing leader messenger RNA.

    PubMed

    Lee, Eun-Jin; Groisman, Eduardo A

    2012-06-13

    The facultative intracellular pathogen Salmonella enterica resides within a membrane-bound compartment inside macrophages. This compartment must be acidified for Salmonella to survive within macrophages, possibly because acidic pH promotes expression of Salmonella virulence proteins. We reasoned that Salmonella might sense its surroundings have turned acidic not only upon protonation of the extracytoplasmic domain of a protein sensor but also by an increase in cytosolic ATP levels, because conditions that enhance the proton gradient across the bacterial inner membrane stimulate ATP synthesis. Here we report that an increase in cytosolic ATP promotes transcription of the coding region for the virulence gene mgtC, which is the most highly induced horizontally acquired gene when Salmonella is inside macrophages. This transcript is induced both upon media acidification and by physiological conditions that increase ATP levels independently of acidification. ATP is sensed by the coupling/uncoupling of transcription of the unusually long mgtC leader messenger RNA and translation of a short open reading frame located in this region. A mutation in the mgtC leader messenger RNA that eliminates the response to ATP hinders mgtC expression inside macrophages and attenuates Salmonella virulence in mice. Our results define a singular example of an ATP-sensing leader messenger RNA. Moreover, they indicate that pathogens can interpret extracellular cues by the impact they have on cellular metabolites.

  17. Focus point gauge mediation with incomplete adjoint messengers and gauge coupling unification

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Gautam; Yanagida, Tsutomu T.; Yokozaki, Norimi

    2015-10-01

    As the mass limits on supersymmetric particles are gradually pushed to higher values due to their continuing non-observation at the CERN LHC, looking for focus point regions in the supersymmetric parameter space, which shows considerably reduced fine-tuning, is increasingly more important than ever. We explore this in the context of gauge mediated supersymmetry breaking with messengers transforming in the adjoint representation of the gauge group, namely, octet of color SU(3) and triplet of weak SU(2). A distinctive feature of this scenario is that the focus point is achieved by fixing a single combination of parameters in the messenger sector, which is invariant under the renormalization group evolution. Because of this invariance, the focus point behavior is well under control once the relevant parameters are fixed by a more fundamental theory. The observed Higgs boson mass is explained with a relatively mild fine-tuning Δ = 60- 150. Interestingly, even in the presence of incomplete messenger multiplets of the SU(5) GUT group, the gauge couplings still unify perfectly, but at a scale which is one or two orders of magnitude above the conventional GUT scale. Because of this larger unification scale, the colored Higgs multiplets become too heavy to trigger proton decay at a rate larger than the experimentally allowed limit.

  18. 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.

  19. Decreased expression of myotonin-protein kinase messenger RNA and protein in adult form of myotonic dystropy

    SciTech Connect

    Yinghui Fu; Friedman, D.L.; Richards, S.; Pearlman, J.A.; Gibbs, R.A.; Pizzuti, A.; Perryman, M.B.; Fenwick, R.G. Jr.; Caskey, C.T. ); Ashizawa, Tetsuo Veterans Administration Medical Center, Houston, TX ); Scarlato, G. )

    1993-04-09

    The myotonic dystrophy mutation has recently been identified; however, the molecular mechanism of the disease is still unknown. The sequence of the myotonin-protein kinase gene was determined, and messenger RNA spliced forms were identified in various tissues. Antisera were developed for analytical studies. Quantitative reverse transcription-polymerase chain reaction and radioimmunoassay were used to demonstrate that decreased levels of the messenger RNA and protein expression are associated with adult form of myotonic dystropy. 12 refs., 5 figs.

  20. Mercury's gravity field and ephemeris after 3 years of MESSENGER orbital observations

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    18 March 2014 will be the third anniversary of MESSENGER's insertion into orbit about Mercury. The initial orbit was highly eccentric and nearly polar, with a 12-h period and a periapsis at 200 km altitude and ~60°N latitude. The third-body perturbation of the Sun combined with the high eccentricity of the orbit led to a substantial evolution of the periapsis, which drifted slowly northward and reached an altitude of 500 km several times before orbit-corrections maneuvers returned the periapsis altitude to ~200 km. In March 2012, the mission orbital phase was extended for a second year, and the spacecraft transitioned to an 8-h orbit period one month later. A second extended mission started in March 2013, will last for another two years, and will eventually allow observations at very low altitudes (<100 km), starting in September 2014. One of the main mission goals is the determination of the interior structure of Mercury, enabled by a suite of instruments that includes the radio system and a laser altimeter. The X-band tracking system and NASA's Deep Space Network (DSN) were used to determine the gravity field of Mercury. The effective spatial resolution of the gravity field is strongly dependent on latitude, however, because of MESSENGER's eccentric orbit and its high apoapsis over the southern hemisphere (~15,000 km in the first year, ~10,000 km subsequently). The gravity field of the southern hemisphere remains largely unconstrained at short wavelengths, although the global long-wavelength field has been determined robustly. Furthermore, MESSENGER radio tracking data represent an excellent opportunity to improve Mercury's ephemeris. The current knowledge of the orbit of Mercury around the Sun has been mainly defined by direct ranging. Range measurements from the three Mercury flybys and orbital phase of MESSENGER provide a strong data set to measure the motion of Mercury's center of mass. The 1-m range accuracy potentially allows the recovery of the

  1. 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.

  2. 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.

  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.

  4. 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.

  5. MESSENGER Searches for Less Abundant or Weakly Emitting Species in Mercury's Exosphere

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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, Al, Si, O, S, Mn, Cl, 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. Protein kinase target discovery from genome-wide messenger RNA expression profiling.

    PubMed

    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.

  7. 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

  8. High-temperature laboratory measurements in support of a statistical analysis of spectral data from MESSENGER

    NASA Astrophysics Data System (ADS)

    Helbert, J.; D'Amore, M.; Maturilli, A.; Izenberg, N. R.; Klima, R. L.; Holsclaw, G. M.; McClintock, W. E.; Sprague, A. L.; Vilas, F.; Domingue, D. L.; D'Incecco, P.; Head, J. W.; Gillis-Davis, J. J.; Solomon, S. C.

    2011-12-01

    We assess compositional heterogeneity on the surface of Mercury with data from MESSENGER'S Mercury Atmospheric and Surface Composition Spectrometer (MASCS). The data were obtained during the spacecraft's early orbital phase and cover nearly a pole-to-pole portion of the planet from about 0° to -45°E longitude. Under the hypothesis that surface compositional information can be efficiently derived from spectral reflectance measurements with the use of statistical techniques, we have employed principal component and clustering analyses to identify and characterize spectral units from observations by MASCS. This method proved successful with the interpretation of MASCS data obtained during MESSENGER's Mercury flybys despite the absence of a photometric correction. The statistical technique allows the extraction of underlying relationships among compositional units. We were able to cluster surface observations into distinct classes that correspond well to geomorphological units identified from MESSENGER images, such as plains and heavily cratered terrain. We also identified areas where the geometry of spectral observations matches that of the biconical reflectance attachment used at the DLR Planetary Emissivity Laboratory (PEL). For comparison with spectra from these areas we obtained spectra for a wide range of candidate minerals. The minerals were thermally processed in the Mercury simulation chamber at PEL, by heating them to Mercury peak temperatures under vacuum conditions. This procedure is a first step in the development at PEL of a capability to measure the near-infrared spectra directly at Mercury temperatures. Although such thermal processing cannot capture all spectral changes induced by the high temperatures, it allows an assessment of some of the effects of exposure to Mercury's harsh environment, providing a more realistic comparison than with standard unheated terrestrial minerals. We are therefore able to make inferences on possible mineralogical

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Second messengers, steroids and signaling cascades: Crosstalk in sperm development and function.

    PubMed

    Lackey, B R; Gray, S L

    2015-12-01

    Signaling cascades control numerous aspects of sperm physiology, ranging from creation to fertilization. Novel aspects of several kinases and their influence on sperm development will be discussed in the first section and cover proliferation, chromatin remodeling and morphology. In the second section, protein kinases (A, B and C) that affect sperm function and their regulation by second messengers, cyclic-AMP and phosphoinositides, as well as steroids will be featured. Key areas of integration will be presented on the topics of sperm motility, capacitation, acrosome reaction and fertilization.

  14. 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.

  15. Antidepressants regulate glucocorticoid receptor messenger RNA concentrations in primary neuronal cultures.

    PubMed

    Pepin, M C; Beaulieu, S; Barden, N

    1989-07-01

    Increased cortisol secretion, caused by hyperactivity of the brain-pituitary-adrenal axis, and non-suppression of cortisol secretion following dexamethasone administration are two characteristics frequently associated with major depression or the depressed phase of bipolar illness. Antidepressants, irrespective of their selective inhibitory actions on the re-uptake of serotonin or of norepinephrine, modify glucocorticoid receptor messenger RNA concentrations in primary cultures of rat hypothalamic or amygdaloid neurons in a biphasic manner, with predominant stimulatory effects. This suggests a mechanism whereby antidepressants, by restoring the sensitivity of the limbic-hypothalamic system to glucocorticoid feedback inhibition, reverse the hyperactivity of the brain-pituitary-adrenal axis.

  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. In vitro selection of allosteric ribozymes that sense the bacterial second messenger c-di-GMP.

    PubMed

    Furukawa, Kazuhiro; Gu, Hongzhou; Breaker, Ronald R

    2014-01-01

    Recently, a number of study have shown the ligand-dependent allosteric ribozymes can be harnessed as biosensors, high-throughput screening, and agents for the control of gene expression in vivo, called artificial riboswitches. In this chapter, we describe how in vitro selection can be used to create an allosteric ribozyme that senses bacterial second messenger cyclic-di-GMP (c-di-GMP). A hammerhead ribozyme was joined to a natural c-di-GMP class I riboswitch aptamer via communication modules. Both c-di-GMP-activating and -inhibiting ribozyme can be obtained by this approach. PMID:24549622

  18. Mercury's gravity field, orientation, and ephemeris after MESSENGER's Low-Altitude Campaign

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    In April 2015, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft will complete more than 4 years of operations in orbit around Mercury. In its last year, as part of MESSENGER's Second Extended Mission (XM2) started in March 2013, the spacecraft has been collecting radio tracking data at unprecedented low altitudes in Mercury's northern hemisphere. During the first two years in orbit, the spacecraft periapsis altitude was kept between 200 and 500 km, while its location drifted slowly northward from 60˚N to 84˚N. The orbital period initially was 12 h, but it was decreased to 8 h in April 2012. The remaining fuel onboard the spacecraft enabled two extended missions, the last of which will end with an impact expected on or before 28 April 2015. During the second extended mission, the periapsis altitude has been as low as 15-25 km. NASA's Deep Space Network (DSN) tracked the spacecraft during periapsis passages from April to October 2014, when the spacecraft periapsis altitude was between 25 and 100 km. In the last six months of the mission, the closest approaches of MESSENGER were occulted by Mercury and were thus not visible from Earth. However, additional radio tracking data have been collected at altitudes (75-100 km) that are still substantially below the initial periapsis altitude. The new low-altitude radio tracking data have enabled an updated model of the gravity field of Mercury. With these data, the resolution of the field in the northern hemisphere has been improved, revealing features that were previously undetectable and that correlate well with topography. The zonal harmonics are in good agreement with those in previous models of the gravity field. We also focused our study on the determination of other geophysical parameters, such as the orientation of Mercury. The new data were acquired not only at lower altitudes but also at latitudes closer to the equator, so they provide important information on tides, the

  19. Neonatal 6-hydroxydopamine lesions lead to opposing changes in the levels of dopamine receptors and their messenger RNAs.

    PubMed

    Frohna, P A; Neal-Beliveau, B S; Joyce, J N

    1995-09-01

    Previous studies have established that selective damage to the early-developing components of the mesostriatal dopamine system produces profound changes in dopamine D1 receptor-mediated behaviors, while decreasing D1 receptor density. In order to better understand the effects of early intrastriatal 6-hydroxydopamine lesions, we studied the ontogenetic expression (postnatal days 7, 14, 35 and 90) of D1 and D2 receptors, and their corresponding messenger RNAs, in rats that had received intrastriatal 6-hydroxydopamine or vehicle lesions on postnatal day 1. Using receptor autoradiography, significant (P < 0.05) decreases in [3H]SCH 23390 binding to D1 receptors in the rostral and caudal dorsomedial and ventromedial caudate of 6-hydroxydopamine-lesioned animals were evident by postnatal day 7, and remained depressed at all future time points. A significant decrease in D1 receptor concentration occurred in the dorsolateral caudate at later time points (postnatal days 35 and 90). [3H]Spiperone binding to D2 receptor sites was unchanged throughout the entire study. In situ hybridization for D1 and D2 messenger RNA expression showed contrasting results. 6-Hydroxydopamine induced significant decreases of D1 messenger RNA levels in the dorsolateral and dorsomedial caudate by postnatal day 7. By postnatal day 14, messenger RNA expression was significantly elevated in the dorsomedial and ventromedial caudate of the 6-hydroxydopamine group, and remained elevated thereafter. D1 messenger RNA levels became elevated in the lateral caudate at later time points (postnatal days 35 and 90). The opposing changes in D1 receptor concentrations and the messenger RNA encoding the protein did not occur as a consequence of increased transport of D1 receptors to striatonigral terminals. D2 messenger RNA levels in the dorsal caudate were significantly decreased on postnatal day 7, and became higher than controls at postnatal day 14, but were unchanged from controls at later time points

  20. 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.

  1. Lyman-α Models for LRO LAMP from MESSENGER MASCS and SOHO SWAN Data

    NASA Astrophysics Data System (ADS)

    Pryor, Wayne R.; Holsclaw, Gregory M.; McClintock, William E.; Snow, Martin; Vervack, Ronald J.; Gladstone, G. Randall; Stern, S. Alan; Retherford, Kurt D.; Miles, Paul F.

    From models of the interplanetary Lyman-α glow derived from observations by the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) interplanetary Lyman-α data obtained in 2009-2011 on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft mission, daily all-sky Lyman-α maps were generated for use by the Lunar Reconnaissance Orbiter (LRO) LAMP Lyman-Alpha Mapping Project (LAMP) experiment. These models were then compared with Solar and Heliospheric Observatory (SOHO) Solar Wind ANistropy (SWAN) Lyman-α maps when available. Although the empirical agreement across the sky between the scaled model and the SWAN maps is adequate for LAMP mapping purposes, the model brightness values best agree with the SWAN values in 2008 and 2009. SWAN's observations show a systematic decline in 2010 and 2011 relative to the model. It is not clear if the decline represents a failure of the model or a decline in sensitivity in SWAN in 2010 and 2011. MESSENGER MASCS and SOHO SWAN Lyman-α calibrations systematically differ in comparison with the model, with MASCS reporting Lyman-α values some 30 % lower than SWAN.

  2. The Rapid Turnover of RNA Polymerase of Rat Liver Nucleolus, and of Its Messenger RNA

    PubMed Central

    Yu, Fu-Li; Feigelson, Philip

    1972-01-01

    Turnover rates of the components of systems for RNA synthesis of rat-liver nucleus, nucleolus, and nucleoplasm were investigated. Cycloheximide administered in vivo selectively diminished nucleolar RNA synthesis in vitro. In contrast to the relatively stable nucleoplasmic RNA polymerase, nucleolar RNA polymerase (polymerase I) from rat liver decays rapidly upon cycloheximide administration, following pseudo-first order kinetics with a half-life of about 1.3 hr. Cycloheximide elicits this effect not through direct interaction with nucleolar RNA polymerase itself, nor by alteration of template function, but rather by inhibition of de novo synthesis of one or more of the protein components of nucleolar RNA polymerase. Similarly, when actinomycin-D was administered in vivo to inhibit RNA synthesis, the rate of decay of nucleolar RNA polymerase, assayed in the presence of exogenous poly d(A-T) template, was similar to that observed after cycloheximide administration. Thus, the messenger RNA(s) that codes for one or more of the catalytically essential polypeptide components of this enzyme turn over very rapidly with a half-life considerably shorter than 1.3 hr. The rapidity of turnover of both the enzyme protein and its messenger RNA(s) renders nucleolar RNA polymerase highly responsive to altered transcriptional, translational, or post-translational modulation. The marked differences in turnover rates of nucleolar and nucleoplasmic RNA polymerases indicate that at least certain of the protomeric components of nucleolar RNA polymerase I are distinct from those of nucleoplasmic RNA polymerases II and III. PMID:4507607

  3. The Calcium Ion Is a Second Messenger in the Nitrate Signaling Pathway of Arabidopsis.

    PubMed

    Riveras, Eleodoro; Alvarez, José M; Vidal, Elena A; Oses, Carolina; Vega, Andrea; Gutiérrez, Rodrigo A

    2015-10-01

    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 Ca(2+) concentration. We found that nitrate also induces cytoplasmic concentration of inositol 1,4,5-trisphosphate. Increases in inositol 1,4,5-trisphosphate and cytoplasmic Ca(2+) 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 Ca(2+) 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 Ca(2+) channel blockers or phospholipase C inhibitors. These results indicate that Ca(2+) 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 Ca(2+) in response to nitrate required for changes in expression of prototypical nitrate-responsive genes. PMID:26304850

  4. 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.

  5. 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

  6. Light scalar as the messenger of electroweak and flavor symmetry breaking

    SciTech Connect

    Lykken, J. D.; Murdock, Z.; Nandi, S.

    2009-04-01

    We propose a new framework for understanding the hierarchies of fermion masses and mixings. The masses and mixings of all standard model (SM) charged fermions other than top arise from higher dimensional operators involving a messenger scalar S and flavon scalars F{sub i}. The flavons spontaneously break SM flavor symmetries at around the TeV scale. The SM singlet scalar S couples directly to the Higgs H and spontaneously breaks another U(1) at the electroweak scale. At the TeV scale, SM quarks and charged leptons have renormalizable couplings to S, but not to H or F{sub i}. These couplings involve new heavy vectorlike fermions. Integrating out these fermions produces a pattern of higher dimensional operators that reproduce the observed hierarchies of the SM masses and mixings in terms of powers of the 'little hierarchy': the ratio of the electroweak scale to the flavor-breaking scale. The framework has important phenomenological implications. Flavor-changing neutral currents are within experimental limits but D{sup 0}-D{sup 0} mixing and B{sub s}{yields}{mu}{sup +}{mu}{sup -} could be close to current sensitivities. The neutral scalar s of the messenger field mixes with the light Higgs of the SM, which can have strong effects on Higgs decay branching fractions. The s mass eigenstate may be lighter than the Higgs, and could be detected at the Tevatron or the LHC.

  7. 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

  8. Plasma distribution in Mercury's magnetosphere derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer observations

    NASA Astrophysics Data System (ADS)

    Korth, Haje; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.; McNutt, Ralph L.

    2014-04-01

    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 10 months 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 ~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. Reactive oxygen species and alpha,beta-unsaturated aldehydes as second messengers in signal transduction.

    PubMed

    Forman, Henry Jay

    2010-08-01

    Signaling by H(2)O(2), alpha,beta-unsaturated aldehydes, such as 4-hydroxy-2-nonenal (HNE) and related chemical species, is thought to differ from signaling by other second messengers because the oxidants and other electrophiles can readily undergo nonenzymatic reactions and are therefore classified as "reactive." This brief review will describe how and when the chemistry of signaling is similar or differs from classic second messengers, such as cyclic AMP, or posttranslational signaling, such as farnesylation or ubiquitination. The chemistry of cysteine provides a common factor that underlies signaling by H(2)O(2) and HNE. Nonetheless, as H(2)O(2) and HNE are rapidly metabolized in vivo, spatial considerations are extremely important in their actions. Therefore, the locations of sources of H(2)O(2) and alpha,beta-unsaturated aldehydes, the NADPH oxidases, mitochondria, membrane lipids, and redox cycling toxicants, as well as their targets, are key factors. The activation of the JNK pathway by HNE and endogenously generated H(2)O(2) illustrates these principles.

  10. 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.

  11. Messenger RNA profiling: a prototype method to supplant conventional methods for body fluid identification.

    PubMed

    Juusola, Jane; Ballantyne, Jack

    2003-08-12

    Conventional methods of body fluid identification use a variety of labor-intensive, technologically diverse techniques that are performed in a series, not parallel, manner and are costly in terms of time and sample. Theoretically, the identification of a body fluid may be made by determining a sufficient number of mRNAs that are expressed exclusively in cells that collectively comprise that body fluid. Advantages of an mRNA-based approach, compared to conventional biochemical methods of analysis, include greater specificity, simultaneous and semi-automatic analysis through a common assay format, improved timeliness, decreased sample consumption and compatibility with DNA extraction methodologies. In this report, we demonstrate that RNA is stable in biological stains and can be recovered in sufficient quantity and quality for analysis. Messenger RNA from the housekeeping genes S15, beta-actin and GAPDH was detected in blood, semen and saliva stains using a sensitive reverse transcriptase-polymerase chain reaction assay (RT-PCR). Additionally, we have identified a number of candidate tissue-specific genes, statherin, histatin 3, PRB1, PRB2 and PRB3 that may be useful for the positive identification of saliva. Messenger RNAs from these genes were detectable in saliva stains but not in blood or semen stains. Collectively these findings constitute the basis of a prototype RNA based assay system that may eventually supplant conventional methods for body fluid identification.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. Oligonucleotide-conjugated thiazole orange probes as "light-up" probes for messenger ribonucleic acid molecules in living cells.

    PubMed

    Privat, E; Melvin, T; Asseline, U; Vigny, P

    2001-10-01

    "Light-up" probes, icosa-alpha-thymidylate-thiazole orange conjugates, for the in situ time-resolved detection of messenger ribonucleic acid (mRNA) in living cells are evaluated. Upon annealing with polyA in aqueous solutions, the icosa-alpha-thymidylate-thiazole orange conjugates were shown to be up to 15 times more fluorescent. Microinjection of these probes into adherent fibroblasts resulted in high yields of hybridization and fluorescent signals. Incubation of cells in the presence of these probes resulted in facile internalization of the probe and similar painting of the messenger RNA in the nuclear and cytosolic regions.

  19. Mobile shearography

    NASA Astrophysics Data System (ADS)

    Kalms, Michael; Jueptner, Werner

    2005-04-01

    By reason of their sensitivity, accuracy and non-contact as well as non-destructive characteristics, modern optical methods such as digital speckle shearography have found an increasing interest for NDT applications on the factory floor. With new carbon filter technologies and other lightweight constructions in aircraft and automotive manufacturing, adapted examination designs and especially developed testing methods are necessary. Shearography as a coherent optical method has been widely accepted as an useful NDT tool. It is a robust interferometric method to determine locations with maximum stress on various material structures. However, limitations of this technique can be found in the bulky equipment components, the interpretation of the complex sherographic result images and at the work with non-cooperative surfaces (dark absorber, bright shining reflectors). We report a mobile shearography system that was especially designed for investigations at aircraft and automotive constructions.

  20. The equatorial shape and gravity field of Mercury from MESSENGER flybys 1 and 2

    NASA Astrophysics Data System (ADS)

    Smith, David E.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.; Neumann, Gregory A.; Lemoine, Frank G.; Peale, Stanton J.; Margot, Jean-Luc; Torrence, Mark H.; Talpe, Matthieu J.; Head, James W.; Hauck, Steven A.; Johnson, Catherine L.; Perry, Mark E.; Barnouin, Olivier S.; McNutt, Ralph L.; Oberst, Jürgen

    2010-09-01

    On 14 January and 6 October 2008 the MESSENGER spacecraft passed within 200 km of the surface of Mercury. These flybys by MESSENGER provided the first observations of Mercury from a spacecraft since the Mariner 10 flybys in 1974 and 1975. Data from the Mercury Laser Altimeter (MLA) provided new information on the equatorial shape of Mercury, and Doppler tracking of the spacecraft through the flybys provided new data on the planet's gravity field. The MLA passes were on opposite hemispheres of the planet and span collectively ˜40% of the equatorial circumference. The mean elevation of topography observed during flyby 1, in the longitude range 0-90°E, is greater than that seen during flyby 2 in the longitude range 180-270°E, indicating an offset between centers of mass and figure having a magnitude and phase in general agreement with topography determined by Earth-based radar. Both MLA profiles are characterized by slopes of ˜0.015° downward to the east, which is consistent with a long-wavelength equatorial shape defined by a best-fitting ellipse. The Doppler tracking data show sensitivity to the gravitational structure of Mercury. The equatorial ellipticity of the gravitational field , C2,2, is well determined and correlates with the equatorial shape. The S2,2 coefficient is ˜0, as would be expected if Mercury's coordinate system, defined by its rotational state, is aligned along its principal axes of inertia. The recovered value of the polar flattening of the gravitational potential, J2, is considerably lower in magnitude than the value obtained from Mariner 10 tracking, a result that is problematic for internal structure models. This parameter is not as well constrained as the equatorial ellipticity because the flyby trajectories were nearly in the planet's equatorial plane. The residuals from the Doppler tracking data suggest the possibility of mascons on Mercury, but flyby observations are of insufficient resolution for confident recovery. For a range of

  1. Mapping Mercury's Surface Composition at High Spatial Resolution with the MESSENGER X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Nittler, L. R.; Weider, S. Z.; Starr, R. D.; Vorburger, A.; Solomon, S. C.

    2014-12-01

    Previous global maps of Mg/Si and Al/Si and partial maps of S/Si, Ca/Si, and Fe/Si on Mercury's surface derived from orbital data acquired by the MESSENGER X-Ray Spectrometer (XRS) have been highly variable in resolution because of MESSENGER's eccentric orbit and high northern periapsis. The typical spatial resolution at northern latitudes in earlier maps was 200-500 km, a scale that allowed large geochemical terranes to be defined and chemical measurements to be made of features hundreds of kilometers in extent, but so far there have been very few analyses at smaller scales. MESSENGER is now orbiting at the lowest periapsis altitudes so far in the mission, and XRS measurements can thus be made at substantially improved resolution. For example, measurements with resolutions <100 km constituted 1% of the northern-hemisphere observations that were used to make the previous maps, but they make up 31% of those obtained in May and June of 2014. Preliminary analysis of these higher-resolution XRS data confirms the broad-scale geochemical features that have already been identified, but also reveals smaller-scale chemical heterogeneities. For instance, targeted XRS measurements indicate that the high-reflectance smooth plains deposit, about 125 km in extent, at the center of the Rachmaninoff basin has Mg/Si=0.6, higher than for other smooth plains deposits with similar reflectance characteristics (for which Mg/Si is typically <0.4), but similar to the darker material surrounding the unit. Although the high-resolution maps that we continue to generate have limited coverage, they reveal substantial chemical heterogeneity at the 100-km scale both within the northern volcanic plains and within the large high-Mg region that has been previously identified. In many cases, the chemical heterogeneity we observe is closely associated with spatial variations in spectral reflectance properties. Continued observations at ever lower altitudes will allow chemical mapping on Mercury at

  2. MESSENGER observations of the response of Mercury's magnetosphere to northward and southward interplanetary magnetic fields

    NASA Astrophysics Data System (ADS)

    Slavin, James

    M. H. Acũa (2), B. J. Anderson (3), D. N. Baker (4), M. Benna (2), S. A. Boardsen (1), G. n Gloeckler (5), R. E. Gold (3), G. C. Ho (3), H. Korth (3), S. M. Krimigis (3), S. A. Livi (6), R. L. McNutt Jr. (3), J. M. Raines (5), M. Sarantos (1), D. Schriver (7), S. C. Solomon (8), P. Travnicek (9), and T. H. Zurbuchen (5) (1) Heliophysics Science Division, NASA GSFC, Greenbelt, MD 20771, USA, (2) Solar System Exploration Division, NASA GSFC, Greenbelt, MD 20771, USA, (3) The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA, (4) Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA, (5) Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, USA (6) Southwest Research Institute, San Antonio, TX 28510, USA, (7) Institute for Geophysics and Planetary Physics, University of California, Los Angeles, CA 90024, USA, (8) Department of Terrestrial Magnetism, Carnegie Institution of Washington, DC 20015, USA, and (9) Institute of Atmospheric Physics, Prague, Czech Republic, 14131 MESSENGER's 14 January 2008 encounter with Mercury has provided new observations of the solar wind interaction with this planet. Here we report initial results concerning this miniature magnetosphere's response to the north-south component of the interplanetary magnetic field (IMF). This is the component of the IMF that is expected to exert the greatest influence over the structure of the magnetopause and the processes responsible for energy transfer into the magnetosphere. The IMF was northward immediately prior to and following the passage of the MESSENGER spacecraft through this small 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 welldeveloped flux transfer events (FTEs) was observed in the magnetosheath following some of

  3. 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.

  4. Means to an end: mechanisms of alternative polyadenylation of messenger RNA precursors

    PubMed Central

    Gruber, Andreas R; Martin, Georges; Keller, Walter; Zavolan, Mihaela

    2014-01-01

    Expression of mature messenger RNAs (mRNAs) requires appropriate transcription initiation and termination, as well as pre-mRNA processing by capping, splicing, cleavage, and polyadenylation. A core 3′-end processing complex carries out the cleavage and polyadenylation reactions, but many proteins have been implicated in the selection of polyadenylation sites among the multiple alternatives that eukaryotic genes typically have. In recent years, high-throughput approaches to map both the 3′-end processing sites as well as the binding sites of proteins that are involved in the selection of cleavage sites and in the processing reactions have been developed. Here, we review these approaches as well as the insights into the mechanisms of polyadenylation that emerged from genome-wide studies of polyadenylation across a range of cell types and states. WIREs RNA 2014, 5:183–196. doi: 10.1002/wrna.1206 PMID:24243805

  5. The Air Forces on a Model of the Sperry Messenger Airplane Without Propeller

    NASA Technical Reports Server (NTRS)

    Munk, Max M; Diehl, Walter S

    1926-01-01

    This is a report on a scale effect research which was made in the variable-density wind tunnel of the National Advisory Committee for Aeronautics at the request of the Army Air Service. A 1/10 scale model of the sperry messenger airplane with USA-5 wings was tested without a propeller at various Reynolds numbers up to the full scale value. Two series of tests were: the first on the original model which was of the usual simplified construction, and the second on a modified model embodying a great amount of detail. The experimental results show that the scale effect is almost entirely confined to the drag. It was also found that the model should be geometrically similar to the full-scale airplane if the test data are to be directly applicable to full scale.

  6. Neutrons and the structural biology of second messenger signaling and regulation

    SciTech Connect

    Trewhella, J.

    2004-03-28

    Neutron contrast variation is a powerful technique for studying biomolecular complexes and the conformational flexibility that is inherent in bio-molecular signaling and regulation. We use this technique to study intra-cellular signaling and regulatory mechanisms mediated by second messengers such as calcium and cyclic nucleotides. Our recent results on the multifunctional, multi-subunit cyclic nucleotide-dependent protein kinases as well as kinases that play a role in regulating muscle mechanics will be presented. From this work we see common mechanistic themes in kinase activation as well as distinctive attributes that provide for specificity and functional diversity in this important class of enzymes that catalyze the most common type of reversible protein modification used to modulate protein function.

  7. Viruses transfer the antiviral second messenger cGAMP between cells

    PubMed Central

    Bridgeman, A.; Maelfait, J.; Davenne, T.; Partridge, T.; Peng, Y.; Mayer, A.; Dong, T.; Kaever, V.; Borrow, P.; Rehwinkel, J.

    2015-01-01

    Cyclic GMP-AMP synthase (cGAS) detects cytosolic DNA during virus infection and induces an antiviral state. cGAS signals by synthesis of a second messenger, cyclic GMP-AMP (cGAMP), which activates stimulator of interferon genes (STING). We show that cGAMP is incorporated into viral particles, including lentivirus and herpesvirus virions, when these are produced in cGAS-expressing cells. Virions transferred cGAMP to newly infected cells and triggered a STING-dependent antiviral program. These effects were independent of exosomes and viral nucleic acids. Our results reveal a way by which a signal for innate immunity is transferred between cells, potentially accelerating and broadening antiviral responses. Moreover, infection of dendritic cells with cGAMP-loaded lentiviruses enhanced their activation. Loading viral vectors with cGAMP therefore holds promise for vaccine development. PMID:26229117

  8. The Evolution of Mercury’s Crust: A Global Perspective from MESSENGER

    NASA Astrophysics Data System (ADS)

    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.

  9. Flood Volcanism in the Northern High Latitudes of Mercury Revealed by MESSENGER

    NASA Astrophysics Data System (ADS)

    Head, James W.; Chapman, Clark R.; Strom, Robert G.; Fassett, Caleb I.; Denevi, Brett W.; Blewett, David T.; Ernst, Carolyn M.; Watters, Thomas R.; Solomon, Sean C.; Murchie, Scott L.; Prockter, Louise M.; Chabot, Nancy L.; Gillis-Davis, Jeffrey J.; Whitten, Jennifer L.; Goudge, Timothy A.; Baker, David M. H.; Hurwitz, Debra M.; Ostrach, Lillian R.; Xiao, Zhiyong; Merline, William J.; Kerber, Laura; Dickson, James L.; Oberst, Jürgen; Byrne, Paul K.; Klimczak, Christian; Nittler, Larry R.

    2011-09-01

    MESSENGER observations from Mercury orbit reveal that a large contiguous expanse of smooth plains covers much of Mercury’s high northern latitudes and occupies more than 6% of the planet’s surface area. These plains are smooth, embay other landforms, are distinct in color, show several flow features, and partially or completely bury impact craters, the sizes of which indicate plains thicknesses of more than 1 kilometer and multiple phases of emplacement. These characteristics, as well as associated features, interpreted to have formed by thermal erosion, indicate emplacement in a flood-basalt style, consistent with x-ray spectrometric data indicating surface compositions intermediate between those of basalts and komatiites. The plains formed after the Caloris impact basin, confirming that volcanism was a globally extensive process in Mercury’s post-heavy bombardment era.

  10. Effects of local structural transformation of lipid-like compounds on delivery of messenger RNA

    PubMed Central

    Li, Bin; Luo, Xiao; Deng, Binbin; Giancola, JoLynn B.; McComb, David W.; Schmittgen, Thomas D.; Dong, Yizhou

    2016-01-01

    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. PMID:26916931

  11. Evidence for water ice near Mercury's north pole from MESSENGER Neutron Spectrometer measurements.

    PubMed

    Lawrence, David J; Feldman, William C; Goldsten, John O; Maurice, Sylvestre; Peplowski, Patrick N; Anderson, Brian J; Bazell, David; McNutt, Ralph L; Nittler, Larry R; Prettyman, Thomas H; Rodgers, Douglas J; Solomon, Sean C; Weider, Shoshana Z

    2013-01-18

    Measurements by the Neutron Spectrometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show decreases in the flux of epithermal and fast neutrons from Mercury's north polar region that are consistent with the presence of water ice in permanently shadowed regions. The neutron data indicate that Mercury's radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 30 cm thick that is less rich in hydrogen. Combined neutron and radar data are best matched if the buried layer consists of nearly pure water ice. The upper layer contains less than 25 weight % water-equivalent hydrogen. The total mass of water at Mercury's poles is inferred to be 2 × 10(16) to 10(18) grams and is consistent with delivery by comets or volatile-rich asteroids. PMID:23196909

  12. The major-element composition of Mercury's surface from MESSENGER X-ray spectrometry.

    PubMed

    Nittler, Larry R; Starr, Richard D; Weider, Shoshana Z; McCoy, Timothy J; Boynton, William V; Ebel, Denton S; Ernst, Carolyn M; Evans, Larry G; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Schlemm, Charles E; Solomon, Sean C; Sprague, Ann L

    2011-09-30

    X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance. PMID:21960623

  13. 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. PMID:21960629

  14. Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution.

    PubMed

    Peplowski, Patrick N; Evans, Larry G; Hauck, Steven A; McCoy, Timothy J; Boynton, William V; Gillis-Davis, Jeffery J; Ebel, Denton S; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Nittler, Larry R; Solomon, Sean C; Rhodes, Edgar A; Sprague, Ann L; Starr, Richard D; Stockstill-Cahill, Karen R

    2011-09-30

    The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since. PMID:21960624

  15. Properties of Hermean plasma belt: Numerical simulations and comparison with MESSENGER data

    NASA Astrophysics Data System (ADS)

    Herčík, David; Trávníček, Pavel M.; Å tverák, Å. těpán.; Hellinger, Petr

    2016-01-01

    Using a global hybrid model and test particle simulations we present a detailed analysis of the Hermean plasma belt structure. We investigate characteristic properties of quasi-trapped particle population characteristics and its behavior under different orientations of the interplanetary magnetic field. The plasma belt region is constantly supplied with solar wind protons via magnetospheric flanks and tail current sheet region. Protons inside the plasma belt region are quasi-trapped in the magnetic field of Mercury and perform westward drift along the planet. This region is well separated by a magnetic shell and has higher average temperatures and lower bulk proton current densities than the surrounding area. On the dayside the population exhibits loss cone distribution function matching the theoretical loss cone angle. The simulation results are in good agreement with in situ observations of MESSENGER's (MErcury Surface Space ENvironment GEochemistry, and Ranging) MAG and FIPS instruments.

  16. The major-element composition of Mercury's surface from MESSENGER X-ray spectrometry.

    PubMed

    Nittler, Larry R; Starr, Richard D; Weider, Shoshana Z; McCoy, Timothy J; Boynton, William V; Ebel, Denton S; Ernst, Carolyn M; Evans, Larry G; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Schlemm, Charles E; Solomon, Sean C; Sprague, Ann L

    2011-09-30

    X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance.

  17. [Antiviral activity of murine interferons produced by bacterial and animal cell translation of messenger RNA].

    PubMed

    Mamontova, T V; Mentkevich, L M; Orlova, T G

    1980-01-01

    Interferon was produced by E. Coli bacteria and animal cell messenger-RNA--interferon translation (mRNA--IF). The activity of the interferon produced by simultaneous mRNA--IF translation in these two cellular systems was, approximately, similar. The interferons translated by bacteria and animal cells inhibited the cytopathic effect, reproduction and plaque-formation of vesicular stomatitis virus, and, to a greater extent, of mouse encephalomyocarditis virus. The virus titration was carried out by the dye-uptake method. The bacteria-translated interferon (BTIF) was more susceptible to the indicator-virus dose variation and had antiviral effect of shorter duration than the virus-induced and animal cell-translated interferon. The BTIF, probably, due to the action of bacterial proteolytic enzymes proved nonstable on storage.

  18. Quantum: may be a new-found messenger in biological systems.

    PubMed

    Han, Jinxiang; Yang, Meina; Chen, Yu

    2011-01-01

    Current studies on biological communications mainly focus on chemical signals. Since organisms are extremely complex, different kinds of signals may exist in the process of cell communication. The most probable candidate for alternative forms of organism communications is electromagnetic radiation, as many experiments have confirmed that electromagnetic radiation widely exists in cells, tissues, organisms and even between organisms and their surroundings. The well-known connection between electromagnetic radiation and quantization of the energy transfer makes us to suggest a bold, but fresh view that quantum can serve as a biological messenger. This view also coincides with the medium of Qi in the human body according to traditional Chinese medicine (TCM). Relating Qi with quantum may further explain a number of phenomena that cannot be explained solely by conventional chemical signaling systems.

  19. 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

  20. Postage for the messenger: Designating routes for Nuclear mRNA Export

    PubMed Central

    Natalizio, Barbara J.; Wente, Susan R.

    2013-01-01

    Transcription of messenger(m) RNA occurs in the nucleus, making the translocation of mRNA across the nuclear envelope (NE) boundary a critical determinant of proper gene expression and cell survival. A major mRNA export route occurs via the NXF1-dependent pathway through the nuclear pore complexes (NPCs) embedded in the NE. However, recent findings have discovered new evidence supporting the existence of multiple mechanisms for crossing the NE, including both NPC-mediated and NE budding-mediated pathways. An analysis of the trans-acting factors and cis components that define these pathways reveals shared elements as well as mechanistic differences. We review here the current understanding of the mechanisms that characterize each pathway and highlight the determinants that influence mRNA transport fate. PMID:23583578

  1. 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.

  2. Flood volcanism in the northern high latitudes of Mercury revealed by MESSENGER.

    PubMed

    Head, James W; Chapman, Clark R; Strom, Robert G; Fassett, Caleb I; Denevi, Brett W; Blewett, David T; Ernst, Carolyn M; Watters, Thomas R; Solomon, Sean C; Murchie, Scott L; Prockter, Louise M; Chabot, Nancy L; Gillis-Davis, Jeffrey J; Whitten, Jennifer L; Goudge, Timothy A; Baker, David M H; Hurwitz, Debra M; Ostrach, Lillian R; Xiao, Zhiyong; Merline, William J; Kerber, Laura; Dickson, James L; Oberst, Jürgen; Byrne, Paul K; Klimczak, Christian; Nittler, Larry R

    2011-09-30

    MESSENGER observations from Mercury orbit reveal that a large contiguous expanse of smooth plains covers much of Mercury's high northern latitudes and occupies more than 6% of the planet's surface area. These plains are smooth, embay other landforms, are distinct in color, show several flow features, and partially or completely bury impact craters, the sizes of which indicate plains thicknesses of more than 1 kilometer and multiple phases of emplacement. These characteristics, as well as associated features, interpreted to have formed by thermal erosion, indicate emplacement in a flood-basalt style, consistent with x-ray spectrometric data indicating surface compositions intermediate between those of basalts and komatiites. The plains formed after the Caloris impact basin, confirming that volcanism was a globally extensive process in Mercury's post-heavy bombardment era. PMID:21960625

  3. Topography of the northern hemisphere of Mercury from MESSENGER laser altimetry.

    PubMed

    Zuber, Maria T; Smith, David E; Phillips, Roger J; Solomon, Sean C; Neumann, Gregory A; Hauck, Steven A; Peale, Stanton J; Barnouin, Olivier S; Head, James W; Johnson, Catherine L; Lemoine, Frank G; Mazarico, Erwan; Sun, Xiaoli; Torrence, Mark H; Freed, Andrew M; Klimczak, Christian; Margot, Jean-Luc; Oberst, Jürgen; Perry, Mark E; McNutt, Ralph L; Balcerski, Jeffrey A; Michel, Nathalie; Talpe, Matthieu J; Yang, Di

    2012-04-13

    Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history. PMID:22438510

  4. 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.

  5. Areas of permanent shadow in Mercury's south polar region ascertained by MESSENGER orbital imaging

    NASA Astrophysics Data System (ADS)

    Chabot, Nancy L.; Ernst, Carolyn M.; Denevi, Brett W.; Harmon, John K.; Murchie, Scott L.; Blewett, David T.; Solomon, Sean C.; Zhong, Ellen D.

    2012-05-01

    Radar-bright features near Mercury's poles have been postulated to be deposits of water ice trapped in cold, permanently shadowed interiors of impact craters. From its orbit about Mercury, MESSENGER repeatedly imaged the planet's south polar region over one Mercury solar day, providing a complete view of the terrain near the south pole and enabling the identification of areas of permanent shadow larger in horizontal extent than approximately 4 km. In Mercury's south polar region, all radar-bright features correspond to areas of permanent shadow. Application of previous thermal models suggests that the radar-bright deposits in Mercury's south polar cold traps are in locations consistent with a composition dominated by water ice provided that some manner of insulation, such as a thin layer of regolith, covers many of the deposits.

  6. Topography of the Northern Hemisphere of Mercury from MESSENGER Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Zuber,Maria T.; Smith, David E.; Phillips, Roger J.; Solomon, Sean C.; Neumann, Gregory A.; Hauck, Steven A., Jr.; Peale, Stanton J.; Barnouin, Oliver S.; Head, James W.; Johnson, Catherine L.; Lemoine, Frank G.; Mazarico, Erwan; Sun, Xiaoli; Torrence, Mark H.; Freed, Andrew M.; Klimczak, Christian; Margot, Jean-Luc; Oberst, Juergen; Perry, Mark E.; McNutt, Ralph L., Jr.; Balcerski, Jeffrey A.; Michel, Nathalie; Talpe, Matthieu J.; Yang, Di

    2012-01-01

    Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury s topography occurred after the earliest phases of the planet s geological history.

  7. 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.

  8. Common observations of solar X-rays from SPHINX/CORONAS-PHOTON and XRS/MESSENGER

    NASA Astrophysics Data System (ADS)

    Kepa, Anna; Sylwester, Janusz; Sylwester, Barbara; Siarkowski, Marek; Mrozek, Tomasz; Gryciuk, Magdalena; Phillips, Kenneth

    SphinX was a soft X-ray spectrophotometer constructed in the Space Research Centre of Polish Academy of Sciences. The instrument was launched on 30 January 2009 aboard CORONAS-PHOTON satellite as a part of TESIS instrument package. SphinX measured total solar X-ray flux in the energy range from 1 to 15 keV during the period of very low solar activity from 20 February to 29 November 2009. For these times the solar detector (X-ray Spectrometer - XRS) onboard MESSENGER also observed the solar X-rays from a different vantage point. XRS measured the radiation in similar energy range. We present results of the comparison of observations from both instruments and show the preliminary results of physical analysis of spectra for selected flares.

  9. 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.

  10. Effects of local structural transformation of lipid-like compounds on delivery of messenger RNA

    NASA Astrophysics Data System (ADS)

    Li, Bin; Luo, Xiao; Deng, Binbin; Giancola, Jolynn B.; McComb, David W.; Schmittgen, Thomas D.; Dong, Yizhou

    2016-02-01

    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.

  11. 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

  12. HHSMT observations of the Venusian mesospheric temperature, winds, and CO abundance around the MESSENGER flyby

    NASA Astrophysics Data System (ADS)

    Rengel, Miriam; Hartogh, Paul; Jarchow, Christopher

    2008-11-01

    We present submillimeter observations of 12CO J=3-2 and 2-1, and 13CO J=2-1 lines of the Venusian mesosphere and lower thermosphere with the Heinrich Hertz Submillimeter Telescope (HHSMT) taken around the second MESSENGER flyby of Venus on 5 June 2007. The observations cover a range of Venus solar elongations with different fractional disk illuminations. Preliminary results like temperature and CO abundance profiles are presented. These data are part of a coordinated observational campaign in support of the ESA Venus Express mission. Furthermore, this study attempts to contribute to cross-calibrate space- and ground-based observations, to constrain radiative transfer and retrieval algorithms for planetary atmospheres, and to a more thorough understanding of the global patters of circulation of the Venusian atmosphere.

  13. Mercury's Crustal Magnetic Field from Low-Altitude Measurements by MESSENGER.

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.; Phillips, R. J.; Purucker, M. E.; Anderson, B. J.; Byrne, P. K.; Denevi, B. W.; Fan, K. A.; Feinberg, J. M.; Hauck, S. A., II; Head, J. W., III; Korth, H.; James, P. B.; Mazarico, E.; Neumann, G. A.; Philpott, L. C.; Siegler, M. A.; Strauss, B. E.; Tsyganenko, N. A.; Solomon, S. C.

    2015-12-01

    Magnetized rocks can record the history of a planet's magnetic field, a key constraint for understanding interior evolution. From orbital vector magnetic field measurements of Mercury taken by the MESSENGER spacecraft at altitudes below 150 km, we have detected fields indicative of crustal magnetization. Fields from non-crustal sources, which dominate the observations even at low altitudes, were estimated and subtracted from the observations using both magnetospheric models and signal filtering. The resulting high-pass filtered fields have amplitudes of a few to 20 nT. The first low-altitude signals were detected over the Suisei Planitia region and were confirmed by upward continuation to be of crustal origin. At least some contribution from thermoremanent magnetization is required to account for these signals, and we infer a lower bound on the average age of magnetization of 3.7-3.9 Ga on the basis of correlation of crustal magnetic fields with volcanic units of that age range. 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 derived from MESSENGER elemental composition data. Here, we extend these initial results with observations obtained at spacecraft altitudes below 60 km at all body-fixed longitudes from ~40°N to ~75°N. The strongest crustal fields occur in the region 120°E to 210°E, and weaker signals characterize the northern volcanic plains. We test the hypothesis that the longest-wavelength crustal field signals in this region reflect magnetization contrasts between the Caloris basin and the surrounding intercrater plains and circum-Caloris plains. We report the spatial distribution of observed crustal fields, together with magnetization models derived from them and the implications of these models, particularly for the depth distribution of sources compatible with the observations.

  14. MESSENGER Magnetic Field Observations of Upstream Ultra-Low Frequency Waves at Mercury

    NASA Technical Reports Server (NTRS)

    Le, G.; Chi, P. J.; Boardsen, S.; Blanco-Cano, X.; Anderosn, B. J.; Korth, H.

    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 I-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 near 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 near 0.6 Hz, not reported previously in Mariner 10 data. We will discuss wave properties and their occurrence characteristics in this paper.

  15. Long-Duration Neutron Production in Solar Eruptive Events Detected with the MESSENGER Neutron Spectrometer

    NASA Astrophysics Data System (ADS)

    Feldman, W. C.; Lawrence, D. J.; Vestrand, W. T.; Peplowski, P. N.

    2014-12-01

    Nine long-duration neutron solar eruptive events (SEEs) between 31 December 2007 and 16 March 2013 appear to be excellent candidates for detection of fast neutrons from the Sun by the MESSENGER Neutron Spectrometer (NS). One event (on 4 June 2011) is the cleanest example, because it was not accompanied by energetic ions at MESSENGER having energies greater than 50±10 MeV/nuc. The purpose of this study is to assemble a set of conditions common to all events that can help identify the physical conditions at their origin. We classified the nine events into three categories: (1) those having tight magnetic connection to the Sun as well as to spacecraft at 1 AU that can separately measure the energetic proton, alpha particle, and electron flux spectra, (2) those with sufficiently close connection that the energetic flux spectra can be compared, (3) those that have only marginal connections, and (4) those that are also seen at Earth. Four events fall into category (1), three into category (2), two into category (3), and parts of four events overlapped neutron events also seen by the scintillation FIBer solar neutron telescope (FIB) detector placed on the International Space Station in 2009. Seven of the nine events that have either tight or marginal magnetic connection have alpha particle abundances less than 2%. For each event, we modeled expected fast neutron count rates from the 1 AU ion spectrum, a process that accounts for the transport of the neutrons through the spacecraft to the NS. The ratios of measured to predicted fast-neutron counts range between 2.0 and 12.1.

  16. Using Space Weather Forecast Tools for Understanding Planetary Magnetospheres: MESSENGER Experience Applied to MAVEN Studies

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Dewey, R. M.; Brain, D. A.; Jakosky, Bruce; Halekas, Jasper; Connerney, Jack; Odstrcil, Dusan; Mays, M. Leila; Luhmann, Janet

    2015-04-01

    The Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool has been used to calculate the values of interplanetary magnetic field (IMF) strength (B), solar wind speed (V), density (n), ram pressure (~nV2), cross-magnetosphere electric field (VxB), Alfvén Mach number (MA), and other derived quantities of relevance for space weather purposes at Earth. Such parameters as solar wind dynamic pressure can be key for estimating the magnetopause standoff distance, as just one example. The interplanetary electric field drives many magnetospheric dynamical processes and can be compared with general magnetic activity indices and with the occurrence of energetic particle bursts within the Earth’s magnetosphere. Such parameters also serve as input to the global magnetohydrodynamic and kinetic magnetosphere models that are used to forecast magnetospheric and ionospheric processes. Such modeling done for Earth space weather forecasting has helped assess near-real-time magnetospheric behavior for MESSENGER at Mercury (as well as other mission analysis and Mercury ground-based observational campaigns). This solar-wind forcing knowledge has provided a crucial continuing step toward bringing heliospheric science expertise to bear on solar-planetary interaction studies. The experience gained from MESSENGER at Mercury is now being applied to the new observations from the MAVEN (Mars Atmosphere and Volatile Evolution) mission at Mars. We compare the continuous WSA-ENLIL results derived from modeling to the MAVEN SWIA and MAG data from mid-December 2014 to the present time. This provides a broader contextual view of solar wind forcing at Mars and also allows a broader validation of the ENLIL model results throughout the inner heliosphere.

  17. The Velocity Distribution Of Pickup He+ Measured at 0.3 AU by MESSENGER

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Fisk, Lennard A.; Gloeckler, George; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.

    2014-06-01

    During its interplanetary trajectory in 2007-2009, the MErcury Surface, Space ENvrionment, GEochemistry, and Ranging (MESSENGER) spacecraft passed through the gravitational focusing cone for interstellar helium multiple times at a heliocentric distance R ≈ 0.3 AU. Observations of He+ interstellar pickup ions made by the Fast Imaging Plasma Spectrometer sensor on MESSENGER during these transits provide a glimpse into the structure of newly formed inner heliospheric pickup-ion distributions. This close to the Sun, these ions are picked up in a nearly radial interplanetary magnetic field. Compared with the near-Earth environment, pickup ions observed near 0.3 AU will not have had sufficient time to be energized substantially. Such an environment results in a nearly pristine velocity distribution function that should depend only on pickup-ion injection velocities (related to the interstellar gas), pitch-angle scattering, and cooling processes. From measured energy-per-charge spectra obtained during multiple spacecraft observational geometries, we have deduced the phase-space density of He+ as a function of magnetic pitch angle. Our measurements are most consistent with a distribution that decreases nearly monotonically with increasing pitch angle, rather than the more commonly modeled isotropic or hemispherically symmetric forms. These results imply that pitch-angle scattering of He+ may not be instantaneous, as is often assumed, and instead may reflect the velocity distribution of initially injected particles. In a slow solar wind stream, we find a parallel-scattering mean free path of λ || ~ 0.1 AU and a He+ production rate of ~0.05 m-3 s-1 within 0.3 AU.

  18. MESSENGER observations of the dayside low-latitude boundary layer in Mercury's magnetosphere

    NASA Astrophysics Data System (ADS)

    Liljeblad, Elisabet; Karlsson, Tomas; Raines, Jim M.; Slavin, James A.; Kullen, Anita; Sundberg, T.; Zurbuchen, Thomas H.

    2015-10-01

    Observations from MErcury Surface Space ENvironment GEochemistry, and Ranging (MESSENGER)'s Magnetometer and Fast Imaging Plasma Spectrometer instruments during the first orbital year have resulted in the identification of 25 magnetopause crossings in Mercury's magnetosphere with significant low-latitude boundary layers (LLBLs). Of these crossings 72% are observed dawnside and 65% for northward interplanetary magnetic field. The estimated LLBL thickness is 450 ± 56 km and increases with distance to noon. The Na+ group ion is sporadically present in 14 of the boundary layers, with an observed average number density of 22 ± 11% of the proton density. Furthermore, the average Na+ group gyroradii in the layers is 220 ± 34 km, the same order of magnitude as the LLBL thickness. Magnetic shear, plasma β and reconnection rates have been estimated for the LLBL crossings and compared to those of a control group (non-LLBL) of 61 distinct magnetopause crossings which show signs of nearly no plasma inside the magnetopause. The results indicate that reconnection is significantly slower, or even suppressed, for the LLBL crossings compared to the non-LLBL cases. Possible processes that form or impact the LLBL are discussed. Protons injected through the cusp or flank may be important for the formation of the LLBL. Furthermore, the opposite asymmetry in the Kelvin-Helmholtz instability (KHI) as compared to the LLBL rules out the KHI as a dominant formation mechanism. However, the KHI and LLBL could be related to each other, either by the impact of sodium ions gyrating across the magnetopause or by the LLBL preventing the growth of KH waves on the dawnside.

  19. Estrogen-induced mitochondrial reactive oxygen species as signal-transducing messengers.

    PubMed

    Felty, Quentin; Xiong, Wen-Cheng; Sun, Dongmei; Sarkar, Shubhashish; Singh, Kamaleshwar P; Parkash, Jai; Roy, Deodutta

    2005-05-10

    We report here evidence in support of the role of 17beta-estradiol- (E2-) induced mitochondrial (mt) reactive oxygen species (ROS) as signal-transducing messengers. On the basis of monitoring the oxidation of 2',7'-dichlorofluorescin by spectrofluorometry, flow cytometry, and confocal microscopy, we have identified that exposure of E2 triggers the immediate rapid production of intracellular ROS ranging from a 1- to severalfold increase in a variety of cells. E2-stimulated ROS production does not correlate with the activity of the estrogen receptor (ER) in the cells. The ROS is most likely hydrogen peroxide based on its inhibition by antioxidants and catalase and lack of any effects of E2 on O(2)(*)(-) or NO(*) formation. Confocal microscopy showed that ROS is localized in the perinuclear mitochondria. E2 through anchorage- and integrin-dependent signaling to mitochondria increased ROS generation. Increased intracellular ROS formation identified here for the first time may explain the mechanism of previously reported oxidative damage and subsequent genetic alterations including mutations produced by elevated concentrations of estrogens. The functional consequences of E2-induced ROS formation included the enhanced cell motility as shown by the increase in cdc42 and activation of Pyk2 and the increased phosphorylation of signaling proteins c-jun and CREB. E2-induced ROS activated the binding of three oxidant-sensitive transcription factors: AP-1, CREB, and nuclear respiratory factor 1. In addition to ERs as signaling molecules, our findings further revealed that E2-induced mt ROS also act as signal transducing messengers and suggest new targets for the development of antioxidant-based drugs or antioxidant gene therapy for the prevention and treatment of estrogen-dependent cancer.

  20. Cyclic di-GMP: the First 25 Years of a Universal Bacterial Second Messenger

    PubMed Central

    Galperin, Michael Y.; Gomelsky, Mark

    2013-01-01

    SUMMARY Twenty-five years have passed since the discovery of cyclic dimeric (3′→5′) GMP (cyclic di-GMP or c-di-GMP). From the relative obscurity of an allosteric activator of a bacterial cellulose synthase, c-di-GMP has emerged as one of the most common and important bacterial second messengers. Cyclic di-GMP has been shown to regulate biofilm formation, motility, virulence, the cell cycle, differentiation, and other processes. Most c-di-GMP-dependent signaling pathways control the ability of bacteria to interact with abiotic surfaces or with other bacterial and eukaryotic cells. Cyclic di-GMP plays key roles in lifestyle changes of many bacteria, including transition from the motile to the sessile state, which aids in the establishment of multicellular biofilm communities, and from the virulent state in acute infections to the less virulent but more resilient state characteristic of chronic infectious diseases. From a practical standpoint, modulating c-di-GMP signaling pathways in bacteria could represent a new way of controlling formation and dispersal of biofilms in medical and industrial settings. Cyclic di-GMP participates in interkingdom signaling. It is recognized by mammalian immune systems as a uniquely bacterial molecule and therefore is considered a promising vaccine adjuvant. The purpose of this review is not to overview the whole body of data in the burgeoning field of c-di-GMP-dependent signaling. Instead, we provide a historic perspective on the development of the field, emphasize common trends, and illustrate them with the best available examples. We also identify unresolved questions and highlight new directions in c-di-GMP research that will give us a deeper understanding of this truly universal bacterial second messenger. PMID:23471616

  1. The Topography and Gravity of Mercury from the MESSENGER Flybys of 2008

    NASA Astrophysics Data System (ADS)

    Zuber, M. T.; Smith, D. E.; Phillips, R. J.; Solomon, S. C.; Neumann, G. A.; Lemoine, F. G.; Torrence, M. H.; McNutt., R. L., Jr.

    2009-04-01

    In January and October 2008, the MESSENGER spacecraft passed within 200 km of the surface of Mercury en route to Mercury orbit insertion in March 2011. Data acquired by the laser altimeter and Doppler signals from tracking the spacecraft have provided new information on the planet's equatorial shape, near-surface structure, and gravity field. During both flybys the laser altimeter made range measurements to the surface for approximately 10 minutes along ground tracks 3000 to 4000 km long just south of the planet's equator. The two ground tracks, on opposite sides of the planet, both revealed a crater-studded surface with a long-wavelength slope that we believe to be a global feature of the planet and not inconsistent with earlier radar measurements. In addition to craters, the altimeter sampled scarps and ridges - dominantly products of planet-wide contraction that accompanied cooling of the interior - whose topographic profiles provide fresh constraints on mechanical models for lithospheric deformation on Mercury. The tracking of MESSENGER provided new information about Mercury's mass and gravity field. For periods of approximately 30 minutes on both flybys the spacecraft was sensitive to the non-sphericity of the planet's gravity field. On both occasions the perturbations were larger than anticipated on the basis of the gravity field inferred from observations made during the Mariner 10 flybys of 1974-75 and could not be modeled fully by adjustments only to the planet's mass, gravitational flattening, and equatorial ellipticity. Changes in the position of Mercury and errors in the Doppler tracking data can be ruled out. The possibility that Mercury has uncompensated lunar-like mascon anomalies centered on major impact basins appears consistent with the observations.

  2. Hydrogen atoms in the inner heliosphere: SWAN-SOHO and MASCS-MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Quémerais, Eric; McClintock, Bill; Holsclaw, Greg; Katushkina, Olga; Izmodenov, Vlad

    2014-10-01

    We present here a study made by two instruments, Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Solar Wind Anisotropy (SWAN) on SOHO that observed the interplanetary background in 2010. The combination of these two data sets allows us to perform the first study of the distribution of hydrogen atoms inside the Earth's orbit. Triangulation of the position of the maximum emissivity region (MER) was performed for the data of the Ultraviolet and Visible Spectrometer (UVVS) channel of the MASCS-MESSENGER instrument. We find that the ecliptic longitude of the MER is 253.2°±2.0°. This is the same value that was found from the analysis of the SWAN-SOHO H cell data obtained in 1996. This strongly suggests that the direction of the interstellar hydrogen wind has not changed between 1996 and 2010. We have also determined the distance of the MER to the Sun. We find that the volume emission rate peaks at 2.37 AU ± 0.2 AU from the Sun. This value is a good test for the solar parameters for total H ionization and radiation pressure used in models. Comparison between the two data sets obtained by the UVVS-MASCS channel and SWAN on SOHO allow to derive the intensity between the two spacecraft at peak emission. Based on the SWAN-SOHO calibration, we find an intensity of 80 R ± 36 R. This corresponds to a column density of 1540 m-3 AU × 2.3 ×1014m-2. When divided by the distance between the two spacecraft, we find an average number density of 2300 m-3.

  3. Linking The Universe To The Community: Students As Starry Messengers For IYA2009-Puerto Rico.

    NASA Astrophysics Data System (ADS)

    Pantoja, Carmen; Lebrón, M.

    2008-05-01

    This poster presents a project at Puerto Rico 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 International Year of Astronomy 2009 (IYA2009). During 2008 the students will receive the appropriate instruction on observational astronomy through two workshops. These workshops follow the active learning model and therefore prepare students for outreach activities in astronomy. An innovative model of inclusion will be developed, adapting all the activities and material to include blind or visually impaired. We will encourage the participation of at least one visually impaired student or teacher on the Starry Messengers team. The greatest challenge in this project will be to develop adequate accessible activities in astronomy. The workshops will be held at the Arecibo Observatory and "El Parque de las Ciencias" Planetarium. These two centers have the facilities to develop the workshops and have the adequate settings for the participants to gain experience with astronomy research and outreach. This project targets underrepresented groups in science and engineering: hispanic students and students with visual impairments. The inquiry-based learning activities and material designed as part of the program will also be made available to the public to further promote excellence in astronomy. The workshops will serve as templates for future K-12 teacher workshops. This work has been funded by the NASA IDEAS-ER program. We would like to acknowledge the support from the Arecibo Observatory. The Arecibo Observatory is part of the National Astronomy and Ionospheric Center, which is operated by Cornell University under a Cooperative agreement with the National Science Foundation.

  4. Cooperating mobile robots

    DOEpatents

    Harrington, John J.; Eskridge, Steven E.; Hurtado, John E.; Byrne, Raymond H.

    2004-02-03

    A miniature mobile robot provides a relatively inexpensive mobile robot. A mobile robot for searching an area provides a way for multiple mobile robots in cooperating teams. A robotic system with a team of mobile robots communicating information among each other provides a way to locate a source in cooperation. A mobile robot with a sensor, a communication system, and a processor, provides a way to execute a strategy for searching an area.

  5. Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Navajo Code Talker Joe Morris, Sr. shared insights from his time as a secret World War Two messenger with his audience at NASA's Dryden Flight Research Center on Nov. 26, 2002. NASA Dryden is located on Edwards Air Force Base in California's Mojave Desert.

  6. Gene Expression in Archaea: Studies of Transcriptional Promoters, Messenger RNA Processing, and Five Prime Untranslated Regions in "Methanocaldococcus Jannashchii"

    ERIC Educational Resources Information Center

    Zhang, Jian

    2009-01-01

    Gene expression in Archaea is less understood than those in Bacteria and Eucarya. In general, three steps are involved in gene expression--transcription, RNA processing, and translation. To expand our knowledge of these processes in Archaea, I have studied transcriptional promoters, messenger RNA processing, and 5'-untranslated regions in…

  7. The Effects of a Synchronous Communication Tool (Yahoo Messenger) on Online Learners' Sense of Community and Their Multimedia Authoring Skills

    ERIC Educational Resources Information Center

    Wang, Shiang-Kwei

    2008-01-01

    Literature suggests that developing a community of learners is the key to a successful online-learning experience. In this study, the instructor of a multimedia authoring course adopted a synchronous communication tool (Yahoo Messenger) to interact with learners orally on a weekly basis and, thereby, to establish a sense among the learners that…

  8. The Message or the Messenger: Reflection on the Volatility of Evoking Novice Teachers' Courageous Conversations on Race

    ERIC Educational Resources Information Center

    Amobi, Funmi A.

    2007-01-01

    Every teacher is a messenger. The message that a teacher communicates and portrays is acquired formally and informally through systematic study, and environmental and socialization processes. While formal study happens consciously within a particular period of time, experiential learning that impinges on the development of the message happens all…

  9. Models and Messengers of Resilience: A Theoretical Model of College Students' Resilience, Regulatory Strategy Use, and Academic Achievement

    ERIC Educational Resources Information Center

    Johnson, Marcus L.; Taasoobshirazi, Gita; Kestler, Jessica L.; Cordova, Jackie R.

    2015-01-01

    We tested a theoretical model of college students' ratings of messengers of resilience and models of resilience, students' own perceived resilience, regulatory strategy use and achievement. A total of 116 undergraduates participated in this study. The results of a path analysis indicated that ratings of models of resilience had a direct effect on…

  10. Just How Important Is the Messenger versus the Message? The Case of Framing Physician-Assisted Suicide

    ERIC Educational Resources Information Center

    Haider-Markel, Donald P.; Joslyn, Mark R.

    2004-01-01

    As a political issue, death and dying topics only sometimes reach the political agenda. However, some issues, such as physician-assisted suicide (PAS) have been highly salient. This article explores attitudes toward PAS by examining the malleability of opinion when respondents are exposed to issue frames and when specific messengers present those…

  11. Mobile Schools for a Mobile World

    ERIC Educational Resources Information Center

    Booth, Susan

    2013-01-01

    Overwhelmingly, independent schools are embracing mobile devices--laptops, iPads or other tablets, and smartphones--to enhance teaching and learning. This article describes the results of the "NAIS 2012 Mobile Learning Survey." Among its findings were that 75 percent of NAIS-member schools currently use mobile learning devices in at…

  12. Sharing Planetary Exploration: The Education and Public Outreach Program for the NASA MESSENGER Mission to Orbit Mercury

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; Stockman, S.; Chapman, C. R.; Leary, J. C.; McNutt, R. L.

    2003-12-01

    The Education and Public Outreach (EPO) Program of the MESSENGER mission to the planet Mercury, supported by the NASA Discovery Program, is a full partnership between the project's science and engineering teams and a team of professionals from the EPO community. The Challenger Center for Space Science Education (CCSSE) and the Carnegie Academy for Science Education (CASE) are developing sets of MESSENGER Education Modules targeting grade-specific education levels across K-12. These modules are being disseminated through a MESSENGER EPO Website developed at Montana State University, an Educator Fellowship Program managed by CCSSE to train Fellows to conduct educator workshops, additional workshops planned for NASA educators and members of the Minority University - SPace Interdisciplinary Network (MU-SPIN), and existing inner-city science education programs (e.g., the CASE Summer Science Institute in Washington, D.C.). All lessons are mapped to national standards and benchmarks by MESSENGER EPO team members trained by the American Association for the Advancement of Science (AAAS) Project 2061, all involve user input and feedback and quality control by the EPO team, and all are thoroughly screened by members of the project science and engineering teams. At the college level, internships in science and engineering are provided to students at minority institutions through a program managed by MU-SPIN, and additional opportunities for student participation across the country are planned as the mission proceeds. Outreach efforts include radio spots (AAAS), museum displays (National Air and Space Museum), posters and traveling exhibits (CASE), general language books (AAAS), programs targeting underserved communities (AAAS, CCSSE, and MU-SPIN), and a documentary highlighting the scientific and technical challenges involved in exploring Mercury and how the MESSENGER team has been meeting these challenges. As with the educational elements, science and engineering team members

  13. Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis.

    PubMed

    Fridlyand, Leonid E; Philipson, Louis H

    2016-01-01

    Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger

  14. Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis

    PubMed Central

    Fridlyand, Leonid E.; Philipson, Louis H.

    2016-01-01

    Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger

  15. 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.

  16. 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

  17. Mobility of University Staff.

    ERIC Educational Resources Information Center

    Council for Cultural Cooperation, Strasbourg (France).

    This study deals with interuniversity mobility. Part I examines the harmonization of action taken to encourage mobility, the removal of legislative and statutory obstacles to mobility, the simplification of university staff regulations and careers, and incentives to mobility. Part II describes the ideas and activities of UNESCO, the Council of…

  18. [Funzioni esecutive metacognitive ed emozionali/motivazionali nel disturbo dello spettro dell'autismo e nel disturbo da deficit di attenzione con iperattività: risultati preliminari].

    PubMed

    Panerai, Simonetta; Tasca, Domenica; Ferri, Raffaele; Catania, Valentina; Genitori D'Arrigo, Valentina; Di Giorgio, Rosa; Zingale, Marinella; Trubia, Grazia; Torrisi, Anna; Elia, Maurizio

    2016-01-01

    RIASSUNTO. Scopo. I deficit delle funzioni esecutive (FE) sono frequentemente osservati nei disturbi dello spettro dell'autismo (ASD) e nel disturbo da deficit di attenzione con iperattività (ADHD). Lo scopo di questo studio è quello di valutare e confrontare le funzioni esecutive metacognitive ed emozionali/motivazionali di bambini con ASD e ADHD, sia fra di loro che con un gruppo di controllo. Metodi. Il campione è costituito da un totale di 58 soggetti, di cui 17 con ASD senza disabilità intellettiva, 18 con ADHD-manifestazione combinata e 23 con sviluppo tipico, abbinati per genere, età cronologica e livello intellettivo. Le valutazioni hanno riguardato alcune aree del funzionamento esecutivo, nello specifico pianificazione, flessibilità mentale, generatività e inibizione della risposta, che rappresentano sia le funzioni esecutive metacognitive sia quelle emozionali/motivazionali. Risultati. I risultati hanno rilevato un'ampia sovrapposizione delle disfunzioni esecutive nei due gruppi clinici con ASD e ADHD, e non sono stati indicativi della presenza di due profili realmente distinti del funzionamento esecutivo. Tuttavia, nell'ADHD è stato trovato un deficit più severo nell'inibizione della risposta prepotente (funzione emozionale/motivazionale). Conclusioni. I risultati del nostro studio sono parzialmente in accordo con quelli della letteratura. Ulteriori ricerche con gruppi più numerosi potranno chiarire più approfonditamente quali punti di forza e debolezza, nell'ampio spettro delle funzioni esecutive, differenzino fra loro le prestazioni di persone con ASD e ADHD. PMID:27362821

  19. [Funzioni esecutive metacognitive ed emozionali/motivazionali nel disturbo dello spettro dell'autismo e nel disturbo da deficit di attenzione con iperattività: risultati preliminari].

    PubMed

    Panerai, Simonetta; Tasca, Domenica; Ferri, Raffaele; Catania, Valentina; Genitori D'Arrigo, Valentina; Di Giorgio, Rosa; Zingale, Marinella; Trubia, Grazia; Torrisi, Anna; Elia, Maurizio

    2016-01-01

    RIASSUNTO. Scopo. I deficit delle funzioni esecutive (FE) sono frequentemente osservati nei disturbi dello spettro dell'autismo (ASD) e nel disturbo da deficit di attenzione con iperattività (ADHD). Lo scopo di questo studio è quello di valutare e confrontare le funzioni esecutive metacognitive ed emozionali/motivazionali di bambini con ASD e ADHD, sia fra di loro che con un gruppo di controllo. Metodi. Il campione è costituito da un totale di 58 soggetti, di cui 17 con ASD senza disabilità intellettiva, 18 con ADHD-manifestazione combinata e 23 con sviluppo tipico, abbinati per genere, età cronologica e livello intellettivo. Le valutazioni hanno riguardato alcune aree del funzionamento esecutivo, nello specifico pianificazione, flessibilità mentale, generatività e inibizione della risposta, che rappresentano sia le funzioni esecutive metacognitive sia quelle emozionali/motivazionali. Risultati. I risultati hanno rilevato un'ampia sovrapposizione delle disfunzioni esecutive nei due gruppi clinici con ASD e ADHD, e non sono stati indicativi della presenza di due profili realmente distinti del funzionamento esecutivo. Tuttavia, nell'ADHD è stato trovato un deficit più severo nell'inibizione della risposta prepotente (funzione emozionale/motivazionale). Conclusioni. I risultati del nostro studio sono parzialmente in accordo con quelli della letteratura. Ulteriori ricerche con gruppi più numerosi potranno chiarire più approfonditamente quali punti di forza e debolezza, nell'ampio spettro delle funzioni esecutive, differenzino fra loro le prestazioni di persone con ASD e ADHD.

  20. Mercury surface composition: how the new insights from MESSENGER can drive the future exploration

    NASA Astrophysics Data System (ADS)

    Carli, Cristian; Capaccioni, Fabrizio; Filacchione, Gianrico; Zambon, Francesca; Serventi, Giovanna; Altieri, Francesca; De Sanctis, MariaCristina; Sgavetti, Maria

    2016-04-01

    The surface composition of Mercury, as well as the relationship between morphological expressions and lithologies, is one of the most interesting goal to be still explored. After Mariner10, despite relevant differences observed in geophysical characteristics, Mercury surface composition was compared to the Moon (Murray et al, 1974, Science), and, subsequently, lunar surface was considered as analogue (e.g., Blewett et al., 2002, Meteor.Planet.Sci.). After MESSENGER, Mercury surface appeared mainly volcanic in origin. Plains (intercrater and smooth) seem to have a primary flood effusive origin, and even cratered terrains could have the same origin with a higher crater concentration. These volcanic units range from high reflectance red plains to low reflectance blue plains (Denevi et al., 2009, Science). No absorption is present in the visible and near-infrared spectra, indicating very low abundance of transitional elements in silicates (i.e. very low iron and titanium, e.g. FeO < 1%, Klima et al., 2014, Whispers). XRS and GRS, onboard MESSENGER, confirmed a very low Fe/Si ratio in the surface material (Weider et al., 2014, Icarus), not only in silicates, differently from the volcanic compositions present in all the other planetary surfaces. K, Th, U GRS-based are consistent with chondritic source but with greater volatile abundances (Peplowski et al., 2011, Science; 2012, JGR). Moreover, XRS measured high volatile abundances (i.e., S, Na, K) (Evans et al., 2012, JGR; Weider et al., 2012, JGR), with a variable distribution on the surface. The presence of high level of volatiles is in agreement with the evidence of pyroclastic materials (Kerber et al., 2009, EPSL). Mg/Si shows relative high values, with a high variability on the surface. Higher values of Mg/Si are detected in some terrains related to high concentration of Ca/Si, and low Al/Si, indicating ultramafic composition, a relative high degree of partial melting and high temperature, in particular in older

  1. Cell-Free Transcription of Mammalian Chromatin: Transcription of Globin Messenger RNA Sequences from Bone-Marrow Chromatin with Mammalian RNA Polymerase

    PubMed Central

    Steggles, A. W.; Wilson, G. N.; Kantor, J. A.; Picciano, D. J.; Falvey, A. K.; Anderson, W. F.

    1974-01-01

    A mammalian cell-free transcriptional system was developed in which mammalian RNA polymerase synthesizes globin messenger RNA sequences from bone-marrow chromatin. The messenger RNA sequences are detected by measurement of the ability of the transcribed RNA to hybridize with globin complementary DNA. The globin complementary DNA is synthesized by the enzyme from avian myeloblastosis virus, RNA-directed DNA polymerase, with purified globin messenger RNA as template. The specificity of the globin complementary DNA in annealing reactions was verified by preparing DNA complementary to liver messenger RNA and showing that the globin and liver complementary DNAs are specific for their own messenger RNAs. Both DNA-dependent RNA polymerase II from sheep liver and RNA polymerase from Escherichia coli can transcribe globin messenger RNA sequences from rabbit bone-marrow chromatin; however, the mammalian enzyme appears to be more specific in that globin gene sequences represent a higher proportion of the RNA synthesized. Neither polymerase can transcribe globin messenger RNA sequences from rabbit-liver chromatin. This cell-free assay system should be useful in searching for mammalian transcriptional regulatory factors. PMID:4364529

  2. What Might We Learn About Magnetospheric Substorms at the Earth from the MESSENGER Measurements at Mercury?

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    Satellite observations at the Earth, supported by theory and modeling, have established a close connection between the episodes of intense magnetospheric convection termed substorms and the occurrence of magnetic reconnection. Magnetic reconnection at the dayside magnetopause results in strong energy input to the magnetosphere. This energy can either be stored or used immediately to power the magnetospheric convection that produces the phenomena that collectively define the 'substorm.' However, many aspects of magnetic reconnection and the dynamic response of the coupled solar wind - magnetosphere - ionosphere system at the Earth during substorms remain poorly understood. For example, the rate of magnetic reconnection is thought to be proportional to the local Alfven speed, but the limited range of changes in this solar wind parameter at 1 AU have made it difficult to detect its influence over energy input to the Earth's magnetosphere. In addition, the electrical conductance of the ionosphere and how it changes in response to auroral charged particle precipitation are hypothesized to play a critical role in the development of substorms, but the nature of this electrodynamic interaction remain difficult to deduce from Earth observations alone. The amount of energy the terrestrial magnetosphere can store in its tail, the duration of the storage, and the trigger(s) for its dissipation are all thought to be determined by not only the microphysics of the cross-tail current layer, but also the properties of the coupled magnetosphere - ionosphere system. Again, the separation of microphysics effects from system response has proved very difficult using measurements taken only at the Earth. If MESSENGER'S charged particle and magnetic field measurements confirm the occurrence of terrestrial-style substorms in Mercury's miniature magnetosphere, then it may be possible to determine how magnetospheric convection, field-aligned currents, charged particle acceleration

  3. Prostanoid-induced expression of matrix metalloproteinase-1 messenger ribonucleic acid in rat osteosarcoma cells

    NASA Technical Reports Server (NTRS)

    Clohisy, J. C.; Connolly, T. J.; Bergman, K. D.; Quinn, C. O.; Partridge, N. C.

    1994-01-01

    Individual prostanoids have distinct potencies in activating intracellular signaling pathways and regulating gene expression in osteoblastic cells. The E-series prostaglandins (PGs) are known to stimulate matrix metalloproteinase-1 (MMP-1) synthesis and secretion in certain rodent and human osteoblastic cells, yet the intracellular events involved remain unclear. To further characterize this response and its signal transduction pathway(s), we examined prostanoid-induced expression of the MMP-1 gene in the rat osteoblastic osteosarcoma cell line UMR 106-01. Northern blot analysis demonstrated that prostaglandin E2 (PGE2) and PGE1 were very potent stimulators (40-fold) of MMP-1 transcript abundance, PGF2 alpha and prostacyclin were weak stimulators (4-fold), and thromboxane-B2 had no effect. The marked increase in MMP-1 transcript abundance after PGE2 treatment was first detected at 2 h, became maximal at 4 h, and persisted beyond 24 h. This response was dose dependent and elicited maximal and half-maximal effects with concentrations of 10(-6) and 0.6 x 10(-7) M, respectively. Cycloheximide, a protein synthesis inhibitor, completely blocked this effect of PGE2, suggesting that the expression of other genes is required. Nuclear run-on experiments demonstrated that PGE2 rapidly activates MMP-1 gene transcription, with a maximal increase at 2-4 h. The second messenger analog, 8-bromo-cAMP, mimicked the effects of PGE2 by stimulating a dose-dependent increase in MMP-1 messenger RNA (mRNA) levels, with a maximal effect quantitatively similar to that observed with PGE2. Thus, in UMR 106-01 cells, different prostanoids have distinct potencies in stimulating MMP-1 mRNA abundance. Our data suggest that PGE2 stimulation of MMP-1 synthesis is due to activation of MMP-1 gene transcription and a subsequent marked increase in MMP-1 mRNA abundance. This effect is dependent on de novo protein synthesis and is mimicked by protein kinase-A activation.

  4. The effect of 648 nm diode laser irradiation on second messengers in senescent human keratinocytes

    NASA Astrophysics Data System (ADS)

    Hawkins Evans, D.; Abrahamse, H.

    2009-02-01

    Background/purpose: Stress induced premature senescence (SIPS) is defined as the long-term effect of subcytotoxic stress on proliferative cell types. Cells in SIPS display differences at the level of protein expression which affect energy metabolism, defense systems, redox potential, cell morphology and transduction pathways. This study aimed to determine the effect of laser irradiation on second messengers in senescent cells and to establish if that effect can be directly linked to changes in cellular function such as cell viability or proliferation. Materials and Methods: Human keratinocyte cell cultures were modified to induce premature senescence using repeated sub-lethal stresses of 200 uM H2O2 or 5% OH every day for four days with two days recovery. SIPS was confirmed by senescence-associated β-galactosidase staining. Control conditions included normal, repeated stress of 500 uM H2O2 to induce apoptosis and 200 uM PBN as an anti-oxidant or free radical scavenger. Cells were irradiated with 1.5 J/cm2 on day 1 and 4 using a 648 nm diode laser (3.3 mW/cm2) and cellular responses were measured 1 h post irradiation. The affect on second messengers was assessed by measuring cAMP, cGMP, nitric oxide and intracellular calcium (Ca2+) while functional changes were assessed using cell morphology, ATP cell viability, LDH membrane integrity and WST-1 cell proliferation. Results: Results indicate an increase in NO and a decrease in cGMP and Ca2+ in 200 uM H2O2 irradiated cells while PBN irradiated cells showed a decrease in cAMP and an increase in ATP viability and cell proliferation. Conclusion: Laser irradiation influences cell signaling which ultimately changes the biological function of senescent cells. If laser therapy can stimulate the biological function of senescent cells it may be beneficial to conditions such as immune senescence, skin ageing, muscle atrophy, premature ageing of arteries in patients with advanced heart disease, neurodegenerative disorders and

  5. Major-element composition of Mercury's surface from MESSENGER X-ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Weider, S. Z.; Nittler, L. R.; Starr, R. D.; McCoy, T. J.; Boynton, W. V.; Ebel, D. S.; Ernst, C. M.; Evans, L. G.; Goldsten, J. O.; Hamara, D. K.; Lawrence, D. J.; McNutt, R. L.; Schlemm, C. E., II; Solomon, S. C.; Sprague, A. L.

    2011-12-01

    The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission has been in orbit around Mercury since 18 March 2011. The X-Ray Spectrometer (XRS) onboard is revealing the abundances of major elements in the planet's surface for the first time and is thus providing fresh information on Mercury's accretional, differentiation, impact, and geological history. X-rays that emanate from the solar corona during flares excite fluorescent X-rays with characteristic energies from the top ~100 μm of Mercury's surface that are measured by XRS. Forward modelling of the resulting spectra allows elemental abundances for major-elements (Mg, Al, Si, S, Ca, Ti and Fe) to be determined. The data so far show that Mercury's bulk surface composition is distinct from those of the other terrestrial planets, with relatively high Mg/Si and low Al/Si and Ca/Si ratios that lie between those typical of basaltic and ultramafic compositions and are comparable to those for terrestrial komatiites. Derived sulfur abundances are at least ten times higher (up to ~4 wt %) than for the silicate portions of the Earth or Moon, whereas Ti and Fe abundances are low (~0.8 wt % and ~4 wt % respectively). Although the individual footprints for much of the flare data are large, there is compositional heterogeneity across the planet that can be correlated with surface reflectance and geological units. These results, together with the low Fe abundance, indicate that Mercury does not possess a feldspathic flotation crust such as that of the Moon. Rather, it suggests the surface is more likely dominated by lava flows that are products of high-degree partial melting of the mantle. The observations also support the idea that Mercury accreted from highly reduced, but not strongly volatile depleted, precursor materials similar to enstatite chondrites or anhydrous cometary dust particles. The low Fe and Ti abundances seen by XRS do not support the proposal that opaque oxides of these elements are

  6. MESSENGER Educator Fellows Taking the Nation on a Ride to the Innermost Planet

    NASA Astrophysics Data System (ADS)

    Vanhala, H. A.; Goldstein, J. J.; Chapman, C. R.; Edmonds, J. P.; Hallau, K. G.; Hirshon, B.; Weir, H. M.; Solomon, S. C.

    2011-12-01

    Exploration of the mysterious planet Mercury offers an unprecedented opportunity for teachers, students, and citizens to tag along for the ride, and the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) Educator Fellows are making sure classrooms across the U.S. are treated to quite a show. The Fellows, a nationally selected team of 30 master science educator volunteers, conduct workshops to teachers on how to bring educational materials developed in support of the mission into the classroom. The goal of the program is to provide teachers and school districts with exceptional educational materials and professional development strongly tied to the space science curriculum, and the materials are designed to inspire the next generation of America's scientists and engineers through NASA missions. Since the program's inception in 2003, more than 17,000 educators have been trained by the Fellows. On the basis of data gathered from the Fellows, this figure could translate to over two million student experiences. The success of the Fellowship program can also be gauged by determining how well it has maintained its volunteer corps over the years. The Fellows, selected to the program through a national announcement of opportunity every two years, reflect a geographically and institutionally diverse mix of individuals from a variety of settings such as science centers, museums, school districts, and universities. The Fellows sign up to the program for two years at a time, and at the end of their term they have the option to reapply. To keep the number of Fellows at 30 in each cadre, new Fellows are recruited to replace those who have retired. The current, fourth cadre of Fellows includes 30 individuals in 19 states and territories. Of these, seven have been in the program since the first cadre, and the other 23 include Fellows from the second, third, and fourth recruitment campaigns in 2006, 2008, and 2010. The current cadre is conducting its work

  7. Survey of Coherent Approximately 1 Hz Waves in Mercury's Inner Magnetosphere from MESSENGER Observations

    NASA Technical Reports Server (NTRS)

    Boardsen, Scott A.; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Schriver, David; Solomon, Sean C.

    2012-01-01

    We summarize observations by the MESSENGER spacecraft of highly coherent waves at frequencies between 0.4 and 5 Hz in Mercury's inner magnetosphere. This survey covers the time period from 24 March to 25 September 2011, or 2.1 Mercury years. These waves typically exhibit banded harmonic structure that drifts in frequency as the spacecraft traverses the magnetic equator. The waves are seen at all magnetic local times, but their observed rate of occurrence is much less on the dayside, at least in part the result of MESSENGER's orbit. On the nightside, on average, wave power is maximum near the equator and decreases with increasing magnetic latitude, consistent with an equatorial source. When the spacecraft traverses the plasma sheet during its equatorial crossings, wave power is a factor of 2 larger than for equatorial crossings that do not cross the plasma sheet. The waves are highly transverse at large magnetic latitudes but are more compressional near the equator. However, at the equator the transverse component of these waves increases relative to the compressional component as the degree of polarization decreases. Also, there is a substantial minority of events that are transverse at all magnetic latitudes, including the equator. A few of these latter events could be interpreted as ion cyclotron waves. In general, the waves tend to be strongly linear and characterized by values of the ellipticity less than 0.3 and wave-normal angles peaked near 90 deg. Their maxima in wave power at the equator coupled with their narrow-band character suggests that these waves might be generated locally in loss cone plasma characterized by high values of the ratio beta of plasma pressure to magnetic pressure. Presumably both electromagnetic ion cyclotron waves and electromagnetic ion Bernstein waves can be generated by ion loss cone distributions. If proton beta decreases with increasing magnetic latitude along a field line, then electromagnetic ion Bernstein waves are predicted

  8. Messenger RNA profiling for forensic body fluid identification: research and applications.

    PubMed

    Wang, Zheng; Zhang, Su-hua; Di, Zhou; Zhao, Shu-min; Li, Cheng-tao

    2013-10-01

    Identifying the origin of body fluids left at a crime scene can give a significant insight into crime scene reconstruction by supporting a link between sample donors and actual criminal acts. However, the conventional body fluid identification methods are prone to various limitations, such as time consumption, intensive labor, nonparallel manner, varying degrees of sensitivity and limited specificity. Recently, the analysis of cell-specific messenger RNA expression (mRNA profiling) has been proposed to supplant conventional methods for body fluid identification. Since 2011, the collaborative exercises have been organized by the European DNA Profiling Group (EDNAP) in order to evaluate the robustness and reproducibility of mRNA profiling for body fluid identification. The major advantages of mRNA profiling, compared to the conventional methods, include higher sensitivity, greater specificity, the ability of detecting several body fluids in one multiplex reaction, and compatibility with current DNA extraction and analysis procedure. In the current review, we provided an overview of the present knowledge and detection methodologies of mRNA profiling for forensic body fluid identification and discussed its possible practical application to forensic casework. PMID:24466779

  9. The Riia Gene of Bacteriophage T4. II. Regulation of Its Messenger RNA Synthesis

    PubMed Central

    Daegelen, P.; Brody, E.

    1990-01-01

    When the rII genes are first introduced into cells which had been previously infected by T4 phage deleted for these genes, the kinetics of synthesis of rIIA and rIIB RNA are rapid and identical. We show that this rapid synthesis depends on a functional motA gene for rIIB, but not for rIIA, RNA synthesis. By primer-extension mapping of T4 messenger RNA, we find three promoters close to the rIIA gene. One of them is an early promoter just before the rIIA.1 gene; it is used under all conditions tested. Another is in the coding portion of the rIIA.1 gene; it is weak, primarily because of a 19-bp spacing between the -10 and -35 elements, and its use is stimulated by T4 functions. The third is a motA-dependent (middle) promoter which has an unusual CCCGCTT box at -33. We present results which suggest that none of these promoters is likely to be the site at which the motB and motC gene products exercise their major influence on rIIA RNA synthesis. PMID:2379818

  10. Triacontanol and Its Second Messenger 9-β-l(+)-Adenosine as Plant Growth Substances

    PubMed Central

    Ries, Stanley

    1991-01-01

    Triacontanol (TRIA), a common constituent of plant waxes, was first shown in 1977 to be an active growth substance which at nanomolar concentrations increased the growth and yield of crops. TRIA is used to increase crop yields on millions of hectares, particularly in Asia. Many investigators have shown that it affects several basic metabolic processes including photosynthesis, nutrient uptake, and enzyme activity. However, the initial site of action has not been elucidated. TRIA rapidly elicits a second messenger (TRIM) in rice (Oryza sativa L.), which at nanomolar concentrations causes plants to respond in a manner similar to TRIA. TRIM has been identified as 9-β-l(+)-adenosine (9H-purin-6-amine, 9-β-l-ribofuranosyl). During the process of isolating and identifying 9-β-l(+)-adenosine, it was shown that this enantiomer, which previously has not been reported as occurring in nature, made up about 1% of the total adenosine pool in roots from untreated rice seedlings. PMID:16668132

  11. Return to Mercury: A Comparison of Solar Simulation and Flight Data for the MESSENGER Spacecraft

    NASA Technical Reports Server (NTRS)

    Ercol, Carl J.

    2008-01-01

    The MErcury, Surface, Space, ENvironment GEochemistry and Ranging (MESSENGER) spacecraft is a NASA Discovery Mission spacecraft developed and operated by the Johns Hopkins University Applied Physics Laboratory. It was launched on August 3, 2004 and is currently on a course for Mercury orbit insertion in March 2011. To date the mission trajectory has taken the spacecraft to minimum solar distances of 0.332 and 0.313 AU and on January 14, 2008 the first flyby of Mercury in 33 years. From launch through the latest perihelion passage temperature performance data has been collected for the sun facing Digital Sun Sensors (DSS), the sun facing phased array and low gain (omni) antennas, the solar arrays, the sunshade and the two sun facing attitude control 4.4 N thrusters. Prior to launch, extensive solar simulation testing was conducted at the Glenn Research Center, Tank 6 solar simulation facility in Cleveland Ohio. Flight hardware qualification units representing these Sun exposed components were tested in solar environments that represented near mission minimum solar distance as to verify the thermal designs and the material used in fabrication. The paper will review the thermal designs of these components and their thermal performance to date as compared to the solar simulation testing.

  12. Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation

    NASA Technical Reports Server (NTRS)

    Vandenburgh, H. H.; Shansky, J.; Karlisch, P.; Solerssi, R. L.

    1993-01-01

    Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins (PG) E2 and F2 alpha which regulate protein turnover rates and muscle cell growth. These stretch-induced PG increases are reduced in low extracellular calcium medium and by specific phospholipase inhibitors. Mechanical stimulation increases the breakdown rate of 3H-arachidonic acid labelled phospholipids, releasing free 3H-arachidonic acid, the rate-limiting precursor of PG synthesis. Mechanical stimulation also increases 3H-arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo-[2-3H]inositol labelled phospholipids. Phospholipase A2 (PLA2), phosphatidylinositol-specific phospholipase C (PLC), and phospholipase D (PLD) are all activated by stretch. The stretch-induced increases in PG production, 3H-arachidonic acid labelled phospholipid breakdown, and 3H-arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitive) whereas the formation of inositol phosphates from myo-[2-3H]inositol labelled phospholipids is dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid-related second messengers arachidonic acid, diacylglycerol, and PG through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol-specific PLC.

  13. Inherent regulation of EAL domain-catalyzed hydrolysis of second messenger cyclic di-GMP.

    PubMed

    Sundriyal, Amit; Massa, Claudia; Samoray, Dietrich; Zehender, Fabian; Sharpe, Timothy; Jenal, Urs; Schirmer, Tilman

    2014-03-01

    The universal second messenger cyclic di-GMP (cdG) is involved in the regulation of a diverse range of cellular processes in bacteria. The intracellular concentration of the dinucleotide is determined by the opposing actions of diguanylate cyclases and cdG-specific phosphodiesterases (PDEs). Whereas most PDEs have accessory domains that are involved in the regulation of their activity, the regulatory mechanism of this class of enzymes has remained unclear. Here, we use biophysical and functional analyses to show that the isolated EAL domain of a PDE from Escherichia coli (YahA) is in a fast thermodynamic monomer-dimer equilibrium, and that the domain is active only in its dimeric state. Furthermore, our data indicate thermodynamic coupling between substrate binding and EAL dimerization with the dimerization affinity being increased about 100-fold upon substrate binding. Crystal structures of the YahA-EAL domain determined under various conditions (apo, Mg(2+), cdG·Ca(2+) complex) confirm structural coupling between the dimer interface and the catalytic center. The built-in regulatory properties of the EAL domain probably facilitate its modular, functional combination with the diverse repertoire of accessory domains.

  14. Multi-frequency, multi-messenger astrophysics with blazars at ASDC and BSDC

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2015-12-01

    In this contribution I discuss the impact that blazars are having on today's multi-frequency and time-domain astrophysics, as well as how they are contributing to the opening of the era of multi-messenger astronomy. In this context I report some preliminary results from a systematic spectral and timing analysis carried out at ASDC on a very large number of X-ray observations of blazars. I also describe some of the on-going activities dedicated to the set up a new research oriented data center within ICRANet, called the Brazilian Science Data Center or BSDC, capitalising on the extensive experience on scientific data management of the ASDC, on the theoretical astrophysics background of ICRANet, and on local specific expertise. Both the ASDC and BSDC are actively accumulating "science ready" data products on blazars, which will be made available through the ASDC "SED builder" tool (https://tools.asdc.asi.it/SED) and by means of interactive tables reachable at the web sites of both centers.

  15. Messenger RNA- Versus Retrovirus-Based Induced Pluripotent Stem Cell Reprogramming Strategies: Analysis of Genomic Integrity

    PubMed Central

    Steichen, Clara; Luce, Eléanor; Maluenda, Jérôme; Tosca, Lucie; Moreno-Gimeno, Inmaculada; Desterke, Christophe; Dianat, Noushin; Goulinet-Mainot, Sylvie; Awan-Toor, Sarah; Burks, Deborah; Marie, Joëlle; Weber, Anne; Tachdjian, Gérard; Melki, Judith

    2014-01-01

    The use of synthetic messenger RNAs to generate human induced pluripotent stem cells (iPSCs) is particularly appealing for potential regenerative medicine applications, because it overcomes the common drawbacks of DNA-based or virus-based reprogramming strategies, including transgene integration in particular. We compared the genomic integrity of mRNA-derived iPSCs with that of retrovirus-derived iPSCs generated in strictly comparable conditions, by single-nucleotide polymorphism (SNP) and copy number variation (CNV) analyses. We showed that mRNA-derived iPSCs do not differ significantly from the parental fibroblasts in SNP analysis, whereas retrovirus-derived iPSCs do. We found that the number of CNVs seemed independent of the reprogramming method, instead appearing to be clone-dependent. Furthermore, differentiation studies indicated that mRNA-derived iPSCs differentiated efficiently into hepatoblasts and that these cells did not load additional CNVs during differentiation. The integration-free hepatoblasts that were generated constitute a new tool for the study of diseased hepatocytes derived from patients’ iPSCs and their use in the context of stem cell-derived hepatocyte transplantation. Our findings also highlight the need to conduct careful studies on genome integrity for the selection of iPSC lines before using them for further applications. PMID:24736403

  16. Messenger RNA- versus retrovirus-based induced pluripotent stem cell reprogramming strategies: analysis of genomic integrity.

    PubMed

    Steichen, Clara; Luce, Eléanor; Maluenda, Jérôme; Tosca, Lucie; Moreno-Gimeno, Inmaculada; Desterke, Christophe; Dianat, Noushin; Goulinet-Mainot, Sylvie; Awan-Toor, Sarah; Burks, Deborah; Marie, Joëlle; Weber, Anne; Tachdjian, Gérard; Melki, Judith; Dubart-Kupperschmitt, Anne

    2014-06-01

    The use of synthetic messenger RNAs to generate human induced pluripotent stem cells (iPSCs) is particularly appealing for potential regenerative medicine applications, because it overcomes the common drawbacks of DNA-based or virus-based reprogramming strategies, including transgene integration in particular. We compared the genomic integrity of mRNA-derived iPSCs with that of retrovirus-derived iPSCs generated in strictly comparable conditions, by single-nucleotide polymorphism (SNP) and copy number variation (CNV) analyses. We showed that mRNA-derived iPSCs do not differ significantly from the parental fibroblasts in SNP analysis, whereas retrovirus-derived iPSCs do. We found that the number of CNVs seemed independent of the reprogramming method, instead appearing to be clone-dependent. Furthermore, differentiation studies indicated that mRNA-derived iPSCs differentiated efficiently into hepatoblasts and that these cells did not load additional CNVs during differentiation. The integration-free hepatoblasts that were generated constitute a new tool for the study of diseased hepatocytes derived from patients' iPSCs and their use in the context of stem cell-derived hepatocyte transplantation. Our findings also highlight the need to conduct careful studies on genome integrity for the selection of iPSC lines before using them for further applications.

  17. Investigating the origin of candidate lava channels on Mercury with MESSENGER data: Theory and observations

    NASA Astrophysics Data System (ADS)

    Hurwitz, Debra M.; Head, James W.; Byrne, Paul K.; Xiao, Zhiyong; Solomon, Sean C.; Zuber, Maria T.; Smith, David E.; Neumann, Gregory A.

    2013-03-01

    Volcanic plains identified on Mercury are morphologically similar to lunar mare plains but lack constructional and erosional features that are prevalent on other terrestrial planetary bodies. We analyzed images acquired by the MESSENGER spacecraft to identify features on Mercury that may have formed by lava erosion. We used analytical models to estimate eruption flux, erosion rate, and eruption duration to characterize the formation of candidate erosional features, and we compared results with analyses of similar features observed on Earth, the Moon, and Mars. Results suggest that lava erupting at high effusion rates similar to those required to form the Teepee Butte Member of the Columbia River flood basalts (0.1-1.2 × 106 m3 s-1) would have been necessary to form wide valleys (>15 km wide) observed in Mercury's northern hemisphere, first by mechanical erosion to remove an upper regolith layer, then by thermal erosion once a lower rigid layer was encountered. Alternatively, results suggest that lava erupting at lower effusion rates similar to those predicted to have formed Rima Prinz on the Moon (4400 m3 s-1) would have been required to form, via thermal erosion, narrower channels (<7 km wide) observed on Mercury. Although these results indicate how erosion might have occurred on Mercury, the observed features may have formed by other processes, including lava flooding terrain sculpted during the formation of the Caloris basin in the case of the wide valleys, or impact melt carving channels into impact ejecta in the case of the narrower channels.

  18. The Gravity Field, Orientation, and Ephemeris of Mercury from MESSENGER Observations After Three Years in Orbit

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    We have analyzed three years of radio tracking data from the MESSENGER spacecraft in orbit around Mercury and determined the gravity field, planetary orientation, and ephemeris of the innermost planet. With improvements in spatial coverage, force modeling, and data weighting, we refined an earlier global gravity field both in quality and resolution, and we present here a spherical harmonic solution to degree and order 50. In this field, termed HgM005, uncertainties in low-degree coefficients are reduced by an order of magnitude relative to the earlier global field, and we obtained a preliminary value of the tidal Love number k(sub 2) of 0.451+/-0.014. We also estimated Mercury's pole position, and we obtained an obliquity value of 2.06 +/- 0.16 arcmin, in good agreement with analysis of Earth-based radar observations. From our updated rotation period (58.646146 +/- 0.000011 days) and Mercury ephemeris, we verified experimentally the planet's 3: 2 spin-orbit resonance to greater accuracy than previously possible. We present a detailed analysis of the HgM005 covariance matrix, and we describe some near-circular frozen orbits around Mercury that could be advantageous for future exploration.

  19. Mercury crater statistics from MESSENGER flybys: Implications for stratigraphy and resurfacing history

    NASA Astrophysics Data System (ADS)

    Strom, Robert G.; Banks, Maria E.; Chapman, Clark R.; Fassett, Caleb I.; Forde, Jeffrey A.; Head, James W.; Merline, William J.; Prockter, Louise M.; Solomon, Sean C.

    2011-12-01

    The primary crater population on Mercury has been modified by volcanism and secondary craters. Two phases of volcanism are recognized. One volcanic episode that produced widespread intercrater plains occurred during the period of the Late Heavy Bombardment and markedly altered the surface in many areas. The second episode is typified by the smooth plains interior and exterior to the Caloris basin, both of which have a different crater size-frequency distribution than the intercrater plains, consistent with a cratering record dominated by a younger population of impactors. These two phases may have overlapped as parts of a continuous period of volcanism during which the volcanic flux tended to decrease with time. The youngest age of smooth plains volcanism cannot yet be determined, but at least small expanses of plains are substantially younger than the plains associated with the Caloris basin. The spatial and temporal variations of volcanic resurfacing events can be used to reconstruct Mercury's geologic history from images and compositional and topographic data to be acquired during the orbital phase of the MESSENGER mission.

  20. Topographic roughness of the northern high latitudes of Mercury from MESSENGER Laser Altimeter data

    NASA Astrophysics Data System (ADS)

    Fa, Wenzhe; Cai, Yuzhen; Xiao, Zhiyong; Tian, Wei

    2016-04-01

    We investigated topographic roughness for the northern hemisphere (>45°N) of Mercury using high-resolution topography data acquired by the Mercury Laser Altimeter (MLA) on board the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Our results show that there are distinct differences in the bidirectional slope and root-mean-square (RMS) height among smooth plains (SP), intercrater plains (ICP), and heavily cratered terrain (HCT), and that the ratios of the bidirectional slope and RMS height among the three geologic units are both about 1:2:2.4. Most of Mercury's surface exhibits fractal-like behavior on the basis of the linearity in the deviograms, with median Hurst exponents of 0.66, 0.80, and 0.81 for SP, ICP, and HCT, respectively. The median differential slope map shows that smooth plains are smooth at kilometer scale and become rough at hectometer scale, but they are always rougher than lunar maria at the scales studied. In contrast, intercrater plains and heavily cratered terrain are rough at kilometer scale and smooth at hectometer scale, and they are rougher than lunar highlands at scale <˜2 km but smoother at >˜2 km. We suggest that these scale-dependent roughness characteristics are mainly caused by the difference in density and shape of impact craters between Mercury and the Moon.

  1. Lithium affects REM sleep occurrence, autonomic activity and brain second messengers in the rat.

    PubMed

    Jones, Christine Ann; Perez, Emanuele; Amici, Roberto; Luppi, Marco; Baracchi, Francesca; Cerri, Matteo; Dentico, Daniela; Zamboni, Giovanni

    2008-03-01

    The effects of a single intraperitoneal administration of lithium, a drug used to prevent the recurrence of mania in bipolar disorders, were determined in the rat by studying changes in: (i) the wake-sleep cycle; (ii) autonomic parameters (hypothalamic and tail temperature, heart rate); (iii) the capacity to accumulate cAMP and IP(3) in the preoptic-anterior hypothalamic region (PO-AH) and in the cerebral cortex (CC) under an hypoxic stimulation at normal laboratory and at low ambient temperature (T(a)). In the immediate hours following the injection, lithium induced: (i) a significant reduction in REM sleep; (ii) a non-significant reduction in the delta power density of the EEG in NREM sleep; (iii) a significant decrease in the concentration of cAMP in PO-AH at normal laboratory T(a); (iv) a significant increase of IP(3) concentration in CC following exposure to low T(a). The earliest and most sensitive effects of lithium appear to be those concerning sleep. These changes are concomitant with biochemical effects that, in spite of a systemic administration of the substance, may be differentiated according to the second messenger involved, the brain region and the ambient condition.

  2. Unusual Stability of Messenger RNA in Snake Venom Reveals Gene Expression Dynamics of Venom Replenishment

    PubMed Central

    Currier, Rachel B.; Calvete, Juan J.; Sanz, Libia; Harrison, Robert A.; Rowley, Paul D.; Wagstaff, Simon C.

    2012-01-01

    Venom is a critical evolutionary innovation enabling venomous snakes to become successful limbless predators; it is therefore vital that venomous snakes possess a highly efficient venom production and delivery system to maintain their predatory arsenal. Here, we exploit the unusual stability of messenger RNA in venom to conduct, for the first time, quantitative PCR to characterise the dynamics of gene expression of newly synthesised venom proteins following venom depletion. Quantitative PCR directly from venom enables real-time dynamic studies of gene expression in the same animals because it circumvents the conventional requirement to sacrifice snakes to extract mRNA from dissected venom glands. Using qPCR and proteomic analysis, we show that gene expression and protein re-synthesis triggered by venom expulsion peaks between days 3–7 of the cycle of venom replenishment, with different protein families expressed in parallel. We demonstrate that venom re-synthesis occurs very rapidly following depletion of venom stores, presumably to ensure venomous snakes retain their ability to efficiently predate and remain defended from predators. The stability of mRNA in venom is biologically fascinating, and could significantly empower venom research by expanding opportunities to produce transcriptomes from historical venom stocks and rare or endangered venomous species, for new therapeutic, diagnostic and evolutionary studies. PMID:22879897

  3. MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment.

    PubMed

    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; Solomon, Sean C

    2008-07-01

    The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 +/- 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 +/- 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere. PMID:18599777

  4. Serine protease inhibitor antithrombin III and its messenger RNA in the pathogenesis of Alzheimer's disease.

    PubMed Central

    Kalaria, R. N.; Golde, T.; Kroon, S. N.; Perry, G.

    1993-01-01

    The classical plasma protein antithrombin III (ATIII), an inhibitor of the blood coagulation cascade, is a member of the serpins that are gaining import in the nervous system. In this study, we examined the presence of ATIII in the pathological lesions of Alzheimer's disease (AD). Antibodies to ATIII consistently detected approximately 58-kd protein(s) on immunoblots of cerebral cortex and brain microvessels. Immunocytochemical studies showed ATIII reactivity within amyloid deposits, neurites associated with plaques, and neurofibrillary tangles in neocortex and hippocampus of virtually all the AD cases examined. In some cases, astrocytes were also stained, suggesting ATIII in these cells. ATIII immunoreactivity in neurofibrillary tangles was further defined by electron microscopy, which showed it to be associated with paired helical filaments. Using the polymerase chain reaction technique to amplify ATIII complementary DNA, we found low levels of messenger RNA expression, relative to liver, in control human brain samples, and these were increased in AD samples, particularly in the white matter. Our results suggest the increased presence of ATIII commensurate with astrogliosis and association with the neurofibrillary pathology of AD. We conclude that in concert with other amyloid-associated serine protease inhibitors, ATIII may play a role in the pathogenesis of cerebral amyloidosis. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8362984

  5. RNA-Based Fluorescent Biosensors for Live Cell Imaging of Second Messenger Cyclic di-AMP.

    PubMed

    Kellenberger, Colleen A; Chen, Chen; Whiteley, Aaron T; Portnoy, Daniel A; Hammond, Ming C

    2015-05-27

    Cyclic di-AMP (cdiA) is a second messenger predicted to be widespread in Gram-positive bacteria, some Gram-negative bacteria, and Archaea. In the human pathogen Listeria monocytogenes, cdiA is an essential molecule that regulates metabolic function and cell wall homeostasis, and decreased levels of cdiA result in increased antibiotic susceptibility. We have generated fluorescent biosensors for cdiA through fusion of the Spinach2 aptamer to ligand-binding domains of cdiA riboswitches. The biosensor was used to visualize intracellular cdiA levels in live L. monocytogenes strains and to determine the catalytic domain of the phosphodiesterase PdeA. Furthermore, a flow cytometry assay based on this biosensor was used to screen for diadenylate cyclase activity and confirmed the enzymatic activity of DisA-like proteins from Clostridium difficile and Methanocaldococcus jannaschii. Thus, we have expanded the development of RNA-based biosensors for in vivo metabolite imaging in Gram-positive bacteria and have validated the first dinucleotide cyclase from Archaea.

  6. Mercury's Atmosphere in the Age of Messenger: Calcium and New Species

    NASA Astrophysics Data System (ADS)

    Bida, Thomas

    2011-02-01

    We propose to observe Mercury?s atmosphere using HIRES in order map the temporal and spatial variability of Ca which has been measured in our previous NASA-allocated observations, and to make a deep search for the refractory elements Al and Fe. Observations of Ca are required to define the temporal and spatial variability, density, velocity distribution, and line profile of Ca. Our objectives are to determine its source process, motion, and loss from the exosphere; to explore the effect of solar cycle variations on the exosphere; and to provide a global view of the exosphere to aid in the interpretation of the more targeted MESSENGER observations. Detection of Al and/or Fe in addition to Ca in the atmosphere can be used to derive the Ca/Al and Ca/Fe ratios in the surface, both key compositional diagnostics. A wide range of compositional models, from refractory to volatile-rich, predict significant mantle abundances for Al and Fe (Goettel, 1988). We are now reporting strin! gent upper limits based on 4-sigma detections with Keck/HIRES of an Al tangent column of 1.5e+07 cm-2, and an Fe tangent column of 1.6e+08 cm-2 (Bida and Killen, 2010). We believe that it is essential to confirm these upper limits for Al and Fe and to push hard for a confirmed detection of both, as well as Ca+.

  7. Mercury's Atmosphere in the Age of Messenger: Calcium and New Species

    NASA Astrophysics Data System (ADS)

    Bida, Thomas

    2011-08-01

    We propose to observe Mercury?s atmosphere using HIRES in order map the temporal and spatial variability of Ca which has been measured in our previous NASA-allocated observations, and to make a deep search for the refractory elements Al and Fe. Observations of Ca are required to define the temporal and spatial variability, density, velocity distribution, and line profile of Ca. Our objectives are to determine its source process, motion, and loss from the exosphere; to explore the effect of solar cycle variations on the exosphere; and to provide a global view of the exosphere to aid in the interpretation of the more targeted MESSENGER observations. Detection of Al and/or Fe in addition to Ca in the atmosphere can be used to derive the Ca/Al and Ca/Fe ratios in the surface, both key compositional diagnostics. A wide range of compositional models, from refractory to volatile-rich, predict significant mantle abundances for Al and Fe (Goettel, 1988). We are now reporting strin! gent upper limits based on 4-sigma detections with Keck/HIRES of an Al tangent column of 1.5e+07 cm-2, and an Fe tangent column of 1.6e+08 cm-2 (Bida and Killen, 2010). We believe that it is essential to confirm these upper limits for Al and Fe and to push hard for a confirmed detection of both, as well as Ca+.

  8. The formation of internal 6-methyladenine residues in eucaryotic messenger RNA.

    PubMed

    Tuck, M T

    1992-03-01

    1. The formation of internal 6-methyladenine (m6A) residues in eucaryotic messenger RNA (mRNA) is a postsynthetic modification in which S-adenosyl-L-methionine (SAM) serves as the methyl donor. 2. Of the methyl groups incorporated into mature mRNA 30-50% occur in m6A residues. 3. Although most cellular and certain viral mRNAs contain at least one m6A residue, some transcripts such as those coding for histone and globin are completely lacking in this modification. 4. 6-Methyladenine residues have also been localized to heterogeneous nuclear RNA (HnRNA), and for the most part these residues are conserved during mRNA processing. 5. In all known cases, the m6A residues are also found in a strict consensus sequence, Gm6AC or Am6AC, within the transcript. 6. Although the biological significance of internal adenine methylation in eucaryotic mRNA remains unclear, a great deal of research has indicated that this modification may be required for mRNA transport to the cytoplasm, the selection of splice sites or other RNA processing reactions. PMID:1551452

  9. An intercistronic region and ribosome-binding site in bacterial messenger RNA.

    PubMed Central

    Platt, T; Yanofsky, C

    1975-01-01

    A messenger RNA fragment about 220 nucleotides long has been isolated from 32-P-labeled tryptophan operon mRNA of Escherichia coli. When point mutations at the end of trpB and the beginning of trpA were introduced, the resulting nucleotide changes were found; hence the mRNA fragment must include the trpB-trpA intercistronic region. Most of the nucleotide sequences can be assigned to specific locations in the structural genes, based on the amino-acid sequences of the trpB and trpA proteins. In vitro, ribosomes bind to this piece of mRNA and protect from nuclease attack a region about 40 nucleotides long, containing a central AUG codon. The triplet codons to the 3' side of this AUG correspond to the first seven amino acids of the trpA protein; the codons to the 5' side correspond to the last six amino acids of the trpB protein. Translation of trpB is terminated by single UGA codon, which overlaps the trpA AUG initiation codon: UGAUG. Thus the untranslated "intercistronic" region consists of only two nucleotides. The RNA sequence spanning this region undoubtedly fulfills two functions, specifying ribosome recognition signals as well as encoding amino-acid sequences. Images PMID:1094468

  10. Hypophosphorylated ASF/SF2 binds TAP and is present in messenger ribonucleoproteins.

    PubMed

    Lai, Ming-Chih; Tarn, Woan-Yuh

    2004-07-23

    Serine/arginine-rich proteins (SR proteins) function in precursor mRNA (pre-mRNA) splicing and may also act as adaptors for mRNA export. SR proteins are dynamically phosphorylated in their RS domain, and differential phosphorylation modulates their splicing activity and subcellular localization. In this study, we investigated the influence of phosphorylation on the function of SR proteins in events occurring during mRNA maturation. Immunoprecipitation experiments showed that the mRNA export receptor TAP associates preferentially with the hypophosphorylated form of shuttling SR proteins, including ASF/SF2. Overexpression of ASF induced subnuclear relocalization of TAP to SR protein-enriched nuclear speckles, suggesting their interaction in vivo. Moreover, the ASF found in a nucleoplasmic fraction rich in heterogeneous nuclear ribonucleoprotein (hnRNP) complexes is hyperphosphorylated, whereas mature messenger RNP (mRNP)-bound ASF is hypophosphorylated. Therefore, hypophosphorylation of ASF in mRNPs coincides with its higher affinity for TAP, suggesting that dephosphorylation of ASF promotes both its incorporation into mRNPs and recruitment of TAP for mRNA export. Thus, the phosphorylation state of RS domains may modulate the function of mammalian shuttling SR proteins during mRNA maturation or export. PMID:15184380

  11. Biogenesis, assembly, and export of viral messenger ribonucleoproteins in the influenza A virus infected cell

    PubMed Central

    York, Ashley; Fodor, Ervin

    2013-01-01

    The flow of genetic information from sites of transcription within the nucleus to the cytoplasmic translational machinery of eukaryotic cells is obstructed by a physical blockade, the nuclear double membrane, which must be overcome in order to adhere to the central dogma of molecular biology, DNA makes RNA makes protein. Advancement in the field of cellular and molecular biology has painted a detailed picture of the molecular mechanisms from transcription of genes to mRNAs and their processing that is closely coupled to export from the nucleus. The rules that govern delivering messenger transcripts from the nucleus must be obeyed by influenza A virus, a member of the Orthomyxoviridae that has adopted a nuclear replication cycle. The negative-sense genome of influenza A virus is segmented into eight individual viral ribonucleoprotein (vRNP) complexes containing the viral RNA-dependent RNA polymerase and single-stranded RNA encapsidated in viral nucleoprotein. Influenza A virus mRNAs fall into three major categories, intronless, intron-containing unspliced and spliced. During evolutionary history, influenza A virus has conceived a way of negotiating the passage of viral transcripts from the nucleus to cytoplasmic sites of protein synthesis. The major mRNA nuclear export NXF1 pathway is increasingly implicated in viral mRNA export and this review considers and discusses the current understanding of how influenza A virus exploits the host mRNA export pathway for replication. PMID:23807439

  12. A Bayesian approach to multi-messenger astronomy: identification of gravitational-wave host galaxies

    SciTech Connect

    Fan, XiLong; Messenger, Christopher; Heng, Ik Siong

    2014-11-01

    We present a general framework for incorporating astrophysical information into Bayesian parameter estimation techniques used by gravitational wave data analysis to facilitate multi-messenger astronomy. Since the progenitors of transient gravitational wave events, such as compact binary coalescences, are likely to be associated with a host galaxy, improvements to the source sky location estimates through the use of host galaxy information are explored. To demonstrate how host galaxy properties can be included, we simulate a population of compact binary coalescences and show that for ∼8.5% of simulations within 200 Mpc, the top 10 most likely galaxies account for a ∼50% of the total probability of hosting a gravitational wave source. The true gravitational wave source host galaxy is in the top 10 galaxy candidates ∼10% of the time. Furthermore, we show that by including host galaxy information, a better estimate of the inclination angle of a compact binary gravitational wave source can be obtained. We also demonstrate the flexibility of our method by incorporating the use of either the B or K band into our analysis.

  13. Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation

    NASA Technical Reports Server (NTRS)

    Vandenburgh, Herman H.; Shansky, Janet; Karlisch, Patricia; Solerssi, Rosa Lopez

    1991-01-01

    Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins E2 and F2(alpha) which regulate protein turnover rates and muscle cell growth. Mechnical stimulation significantly increases the breakdown rate of (3)H-arachidonic acid labelled phospholipids, releasing free (3)H-arachidonic acid, and the rate-limiting precursor of prostaglandin synthesis. Mechanical stimulation also significantly increases (3)H-arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo-2-(3)H inositol labelled phospholipids. Phospholipase A2, phosphatidylinositol-specific phospholipase C (PLC), and phospholipase D (PLD) are activated by stretch. The lipase inhibitors bromophenacylbromide and RHC80267 together reduce stretch-induced prostaglandin production by 73-83 percent. The stretch-induced increases in prostaglandin production, (3)H-arachidonic acid labelled phospholipid breakdown, and (3)H-arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitive) whereas the formation of inositol phosphates from myo-2-(3)H inositol labelled phospholipids are dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid-related second messengers arachidonic acid, diacylglycerol, and prostaglandins through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol-specific PLC.

  14. Messenger RNA sequence and the translation process --a particle transport perspective

    NASA Astrophysics Data System (ADS)

    Dong, Jiajia; Schmittmann, Beate; Zia, Royce K. P.

    2008-03-01

    The translation process in bacteria has been under intensive study. A key question concerns the quantitative effect of different elongation rates, associated with different codons, on the overall translation efficiency. Starting with a simple particle transport model, the totally asymmetric simple exclusion process (TASEP), we incorporate the essential components of the translation process: Ribosomes, cognate tRNA concentrations, and messenger RNA (mRNA) templates correspond to particles, hopping rates, and the underlying lattice, respectively. Using simulations and mean-field approximations to obtain the stationary currents (the protein production rates) associated with different mRNA sequences, we are especially interested in the effect of slow codons, i.e., codons which are associated with rare tRNAs and are therefore translated very slowly. As the first step, we look at a ``designed sequence'' with one and two slow codons and quantify the marked impact of their spatial distribution to the currents. Extending the results to several mRNA sequences taken from real genes, we argue that an effective translation rate including the information from the vicinity of each codon needs to be taken into consideration when seeking an efficient strategy to optimize the protein production.

  15. Comment on ``Length-dependent translation of messenger RNA by ribosomes''

    NASA Astrophysics Data System (ADS)

    Zhang, Yunxin

    2012-02-01

    In a recent paper by Valleriani [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.042903 83, 042903 (2011)], a simple model for the translation of messenger RNA (mRNA) is presented. Using this model, the protein translational ratio r, defined as the ratio of protein translation rate ωtl from mRNA to protein degradation rate ωp, is obtained. The key point in obtaining the translational ratio r is to get the protein translation rate ωtl. In Valleriani 's paper, ωtl is obtained as the mean value of the measured translation rate, which is the ratio of the synthesized protein number to the mRNA lifetime. However, in experiments, different methods might be used to obtain the value of ωtl. Therefore, to apply Valleriani 's model to more general experiments, in this Comment three methods to obtain the translation rate ωtl, and consequently the translational ratio r, are presented. Based on one of the methods which might be employed in most of the experiments, we find that the translational ratio r decays exponentially with mRNA length in prokaryotic cells, and decays reciprocally with mRNA length in eukaryotic cells. This result is slight different from that which was obtained in Valleriani 's paper.

  16. Direct detection of green fluorescent protein messenger RNA expressed in Escherichia coli by rolling circle amplification.

    PubMed

    Takahashi, Hirokazu; Matsumoto, Atsuko; Sugiyama, Shigeru; Kobori, Toshiro

    2010-06-15

    Prevailing conventional microbial detection methods depend largely on microbial cultivation in selective media that requires several days. Polymerase chain reaction (PCR)-based methods, including quantitative reverse transcription PCR, are also rapid and useful methods for identification of target microbes, although for practical use they still suffer from disadvantages such as contamination problems and cost. Here we demonstrate that RNA-primed rolling circle amplification (RPRCA) using phi29 DNA polymerase, a precircularized probe, and SYBR Green II achieved real-time detection of specific messenger RNA (mRNA) from living microbes. The precircularized DNA probe was prepared by intramolecular ligation using CircLigase and treated by exonuclease I to eliminate uncircularized oligonucleotide, thereby significantly reducing potential noise by nonspecific amplified DNA by-products that affect successive RPRCA. When in vitro transcribed green fluorescent protein (GFP) mRNA was used as a primer, RPRCA could specifically detect at least 1 fmol of this mRNA in the presence of a precircularized probe that had a sequence complementary to the 3' terminus of mRNA without reverse transcription. This method could also detect expressed GFP mRNA present in 10 ng of total RNA isolated from Escherichia coli without DNase treatment. These data suggest that RPRCA has the potential to be a direct, rapid, and convenient method for detecting microbial mRNA.

  17. Chemical heterogeneity on Mercury's surface revealed by the MESSENGER X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Stockstill-Cahill, Karen R.; Byrne, Paul K.; Denevi, Brett W.; Head, James W.; Solomon, Sean C.

    2012-10-01

    We present the analysis of 205 spatially resolved measurements of the surface composition of Mercury from MESSENGER's X-Ray Spectrometer. The surface footprints of these measurements are categorized according to geological terrain. Northern smooth plains deposits and the plains interior to the Caloris basin differ compositionally from older terrain on Mercury. The older terrain generally has higher Mg/Si, S/Si, and Ca/Si ratios, and a lower Al/Si ratio than the smooth plains. Mercury's surface mineralogy is likely dominated by high-Mg mafic minerals (e.g., enstatite), plagioclase feldspar, and lesser amounts of Ca, Mg, and/or Fe sulfides (e.g., oldhamite). The compositional difference between the volcanic smooth plains and the older terrain reflects different abundances of these minerals and points to the crystallization of the smooth plains from a more chemically evolved magma source. High-degree partial melts of enstatite chondrite material provide a generally good compositional and mineralogical match for much of the surface of Mercury. An exception is Fe, for which the low surface abundance on Mercury is still higher than that of melts from enstatite chondrites and may indicate an exogenous contribution from meteoroid impacts.

  18. Messenger RNA-based therapeutics for the treatment of apoptosis-associated diseases.

    PubMed

    Matsui, Akitsugu; Uchida, Satoshi; Ishii, Takehiko; Itaka, Keiji; Kataoka, Kazunori

    2015-10-28

    Gene therapy is a promising approach for treating diseases that are closely associated with excessive apoptosis, because the gene can effectively and sustainably introduce anti-apoptotic factors into cells. However, DNA delivery poses the risk of random genomic integration, leading to overexpression of the delivered gene and cancer development. Messenger RNA (mRNA) can evade integration events in target cells. We examined the use of mRNA-based therapeutics for introducing anti-apoptotic factors by using a mouse model of fulminant hepatitis. For introducing mRNA into the liver, a synthesised polymer-based carrier of polyplex nanomicelles was used for hydrodynamic intravenous injection. Using GFP as a reporter, we demonstrate that mRNA delivery induced efficient protein expression in almost 100% of liver cells, while plasmid DNA (pDNA) delivery provided a smaller percentage of GFP-positive cells. Analyses using Cy5-labelled mRNA and pDNA revealed that efficient expression by mRNA was attributed to a simple intracellular mechanism, without the need for nuclear entry. Consistent with this observation, Bcl-2 mRNA was more effective on reducing apoptosis in the liver of mice with fulminant hepatitis than Bcl-2 pDNA. Therefore, mRNA-based therapeutics combined with an effective delivery system such as polyplex nanomicelles is a promising treatment for intractable diseases associated with excessive apoptosis.

  19. Support of long-wavelength topography on Mercury inferred from MESSENGER measurements of gravity and topography

    NASA Astrophysics Data System (ADS)

    James, Peter B.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.

    2015-02-01

    To explore the mechanisms of support of surface topography on Mercury, we have determined the admittances and correlations of topography and gravity in Mercury's northern hemisphere from measurements obtained by NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. These admittances and correlations can be interpreted in the context of a number of theoretical scenarios, including flexural loading and dynamic flow. We find that long-wavelength (spherical harmonic degree l < 15) surface topography on Mercury is primarily supported through a combination of crustal thickness variations and deep mass anomalies. The deep mass anomalies may be interpreted either as lateral variations in mantle density or as relief on compositional interfaces. Domical topographic swells are associated with high admittances and are compensated at 300-400 km depth in the lower reaches of Mercury's mantle. Quasi-linear topographic rises are primarily associated with shallow crustal compensation and are weakly correlated with positive mass anomalies in the mantle. The center of the Caloris basin features some of the thinnest crust on the planet, and the basin is underlain by a large negative mass anomaly. We also explore models of dynamic flow in the presence of compositional stratification above the liquid core. If there is substantial compositional stratification in Mercury's solid outer shell, relaxation of perturbed compositional interfaces may be capable of creating and sustaining long-wavelength topography.

  20. Messenger RNA profiling for forensic body fluid identification: research and applications.

    PubMed

    Wang, Zheng; Zhang, Su-hua; Di, Zhou; Zhao, Shu-min; Li, Cheng-tao

    2013-10-01

    Identifying the origin of body fluids left at a crime scene can give a significant insight into crime scene reconstruction by supporting a link between sample donors and actual criminal acts. However, the conventional body fluid identification methods are prone to various limitations, such as time consumption, intensive labor, nonparallel manner, varying degrees of sensitivity and limited specificity. Recently, the analysis of cell-specific messenger RNA expression (mRNA profiling) has been proposed to supplant conventional methods for body fluid identification. Since 2011, the collaborative exercises have been organized by the European DNA Profiling Group (EDNAP) in order to evaluate the robustness and reproducibility of mRNA profiling for body fluid identification. The major advantages of mRNA profiling, compared to the conventional methods, include higher sensitivity, greater specificity, the ability of detecting several body fluids in one multiplex reaction, and compatibility with current DNA extraction and analysis procedure. In the current review, we provided an overview of the present knowledge and detection methodologies of mRNA profiling for forensic body fluid identification and discussed its possible practical application to forensic casework.

  1. Involvement of second messengers in regulation of the low-density lipoprotein receptor gene

    SciTech Connect

    Auwerx, J.H. . ECHEM Labs.); Chait, A.; Wolfbauer, G.; Deeb, S.S. . Dept. of Medicine)

    1989-06-01

    Transcription of the low-density lipoprotein receptor (LDL-R) gene in the human monocytic leukemic cell line THP-1 and in the human hepatocarcinoma cell line Hep-G2 is regulated by second messengers of the diacylglycerol-protein kinase C (DAG-PKC), inositol 1,4,5-triphosphate-Ca/sup 2+/, and cyclic AMP pathways. Exogeneous phospholipase C (which releases DAG and inositol 1,4,5-triphosphate), PKC activators (phorbol esters and DAG), Ca/sup 2+/ ionophores, and a cyclic AMP analog all transiently induced accumulation of LDL-R mRNA. The effects of these three signal-transducing pathways were to a large extend additive. Furthermore, PKC stimulation effected an increase in LDL binding, which suggested that the increase in LDL-R mRNA resulted in an increase in functional cell surface receptor activity. These results suggest that uptake of cholesterol by these cells is under control of both intracellular cholesterol levels and external signals.

  2. Large Impact Basins on Mercury: Global Distribution, Characteristics, and Modification History from MESSENGER Orbital Data

    NASA Technical Reports Server (NTRS)

    Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Zuber, Maria T.; Neumann, Gregory A.; Solomon, Sean C.; Klimczak, Christian; Strom, Robert G.; Chapman, Clark R.; Prockter, Louise M.; Phillips, Roger J.; Oberst, Juergen; Preusker, Frank

    2012-01-01

    The formation of large impact basins (diameter D greater than or equal to 300 km) was an important process in the early evolution of Mercury and influenced the planet's topography, stratigraphy, and crustal structure. We catalog and characterize this basin population on Mercury from global observations by the MESSENGER spacecraft, and we use the new data to evaluate basins suggested on the basis of the Mariner 10 flybys. Forty-two certain or probable impact basins are recognized a few additional basins that may have been degraded to the point of ambiguity are plausible on the basis of new data but are classified as uncertain. The spatial density of large basins (D greater than or equal to 500 km) on Mercury is lower than that on the Moon. Morphological characteristics of basins on Mercury suggest that on average they are more degraded than lunar basins. These observations are consistent with more efficient modification, degradation, and obliteration of the largest basins on Mercury than on the Moon. This distinction may be a result of differences in the basin formation process (producing fewer rings), greater relaxation of topography after basin formation (subduing relief), and/or higher rates of volcanism during the period of heavy bombardment on Mercury compared to the Moon (burying basin rings and interiors).

  3. Chemical Heterogeneity on Mercury's Surface Revealed by the MESSENGER X-ray Spectrometer

    NASA Technical Reports Server (NTRS)

    Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Stockstill-Cahill, Karen R.; Byrne, Paul K.; Denevi, Brett W.; Head, James W.; Solomon, Sean C.

    2012-01-01

    We present the analysis of 205 spatially resolved measurements of the surfacecomposition of Mercury from MESSENGERs X-Ray Spectrometer. The surfacefootprints of these measurements are categorized according to geological terrain. Northernsmooth plains deposits and the plains interior to the Caloris basin differ compositionallyfrom older terrain on Mercury. The older terrain generally has higher MgSi, SSi, andCaSi ratios, and a lower AlSi ratio than the smooth plains. Mercurys surface mineralogyis likely dominated by high-Mg mafic minerals (e.g., enstatite), plagioclase feldspar, andlesser amounts of Ca, Mg, andor Fe sulfides (e.g., oldhamite). The compositionaldifference between the volcanic smooth plains and the older terrain reflects differentabundances of these minerals and points to the crystallization of the smooth plains from amore chemically evolved magma source. High-degree partial melts of enstatite chondritematerial provide a generally good compositional and mineralogical match for much ofthe surface of Mercury. An exception is Fe, for which the low surface abundance onMercury is still higher than that of melts from enstatite chondrites and may indicate anexogenous contribution from meteoroid impacts.

  4. The gravity field, orientation, and ephemeris of Mercury from MESSENGER observations after three years in orbit

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    We have analyzed 3 years of radio tracking data from the MESSENGER spacecraft in orbit around Mercury and determined the gravity field, planetary orientation, and ephemeris of the innermost planet. With improvements in spatial coverage, force modeling, and data weighting, we refined an earlier global gravity field both in quality and resolution, and we present here a spherical harmonic solution to degree and order 50. In this field, termed HgM005, uncertainties in low-degree coefficients are reduced by an order of magnitude relative to earlier global fields, and we obtained a preliminary value of the tidal Love number k2 of 0.451 ± 0.014. We also estimated Mercury's pole position, and we obtained an obliquity value of 2.06 ± 0.16 arcmin, in good agreement with analysis of Earth-based radar observations. From our updated rotation period (58.646146 ± 0.000011 days) and Mercury ephemeris, we verified experimentally the planet's 3:2 spin-orbit resonance to greater accuracy than previously possible. We present a detailed analysis of the HgM005 covariance matrix, and we describe some near-circular frozen orbits around Mercury that could be advantageous for future exploration.

  5. Multi-D Core-Collapse Supernova Explosions and the Multi-Messenger Signatures

    NASA Astrophysics Data System (ADS)

    Kotake, Kei

    Based on multi-dimensional neutrino-radiation hydrodynamic simulations, we report several cutting-edge issues about the long-veiled explosion mechanism of core-collapse supernovae (CCSNe). In this contribution, we pay particular attention to whether three-dimensional (3D) hydrodynamics and/or general relativity (GR) would or would not help the onset of explosions. By performing 3D simulations with spectral neutrino transport, we show that it is more difficult to obtain an explosion in 3D than in 2D. In addition, our results from the first generation of full general relativistic 3D simulations including approximate neutrino transport indicate that GR can foster the onset of neutrino-driven explosions. Based on our recent parametric studies using a light-bulb scheme, we discuss impacts of nuclear energy deposition behind the supernova shock and stellar rotation on the neutrino-driven mechanism, both of which have yet to be included in the self-consistent 3D supernova models. Finally we give an outlook with a summary of the most urgent tasks to extract the information about the explosion mechanisms from multi-messenger CCSN observables.

  6. Messenger RNA translation state: the second dimension of high-throughput expression screening.

    PubMed

    Zong, Q; Schummer, M; Hood, L; Morris, D R

    1999-09-14

    Technological advances over the past 10 years have generated powerful tools for parallel analysis of complex biological problems. Among these new technologies, DNA arrays have provided an important experimental approach for identifying changes in the levels of individual mRNA molecules during important cellular transitions. However, cellular behavior is dictated not by mRNA levels, but by the proteins translated from the individual mRNA species. We report a high-throughput method for simultaneously monitoring the translation state and level of individual mRNA species. Messenger RNAs from resting and mitogenically activated fibroblasts were separated, according to degree of ribosome loading, into well-translated and under-translated pools. cDNA probes generated from these fractions were used to interrogate cDNA arrays. Among approximately 1,200 genes analyzed, less than 1% were found to be translationally regulated in response to mitogenic activation, demonstrating the strong selectivity of this regulatory mechanism. This high-throughput approach is shown to be an effective tool for superimposing translation profile on mRNA level for large numbers of genes, as well as for identifying translationally regulated genes for further study.

  7. Second messenger-dependent protein kinases and protein synthesis regulate endogenous secretin receptor responsiveness

    PubMed Central

    Ghadessy, Roxana S; Kelly, Eamonn

    2002-01-01

    The present study investigated the role of second messenger-dependent protein kinase A (PKA) and C (PKC) in the regulation of endogenous secretin receptor responsiveness in NG108-15 mouse neuroblastoma×rat glioma hybrid cells. In whole cell cyclic AMP accumulation studies, activation of PKC either by phorbol 12-myristate 13-acetate (PMA) or by purinoceptor stimulation using uridine 5′-triphosphate (UTP) decreased secretin receptor responsiveness. PKC activation also inhibited forskolin-stimulated cyclic AMP accumulation but did not affect cyclic AMP responses mediated by the prostanoid-IP receptor agonist iloprost, or the A2 adenosine receptor agonist 5′-(N-ethylcarboxamido) adenosine (NECA). In additivity experiments, saturating concentrations of secretin and iloprost were found to be additive in terms of cyclic AMP accumulation, whereas saturating concentrations of NECA and iloprost together were not. This suggests compartmentalization of Gs-coupling components in NG108-15 cells and possible heterologous regulation of secretin receptor responsiveness at the level of adenylyl cyclase activation. Cells exposed to the PKA inhibitor H-89, exhibited a time-dependent increase in secretin receptor responsiveness compared to control cells. This effect was selective since cyclic AMP responses to forskolin, iloprost and NECA were not affected by H-89 treatment. Furthermore, treatment with the protein synthesis inhibitor cycloheximide produced a time-dependent increase in secretin receptor responsiveness. Together these results indicate that endogenous secretin receptor responsiveness is regulated by PKC, PKA and protein neosynthesis in NG108-15 cells. PMID:11959806

  8. Evidence from MESSENGER for sulfur- and carbon-driven explosive volcanism on Mercury

    NASA Astrophysics Data System (ADS)

    Weider, Shoshana Z.; Nittler, Larry R.; Murchie, Scott L.; Peplowski, Patrick N.; McCoy, Timothy J.; Kerber, Laura; Klimczak, Christian; Ernst, Carolyn M.; Goudge, Timothy A.; Starr, Richard D.; Izenberg, Noam R.; Klima, Rachel L.; Solomon, Sean C.

    2016-04-01

    Targeted MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) X-Ray Spectrometer measurements of Mercury's largest identified pyroclastic deposit are combined with neutron and reflectance spectroscopy data to constrain the composition of volatiles involved in the eruption that emplaced the pyroclastic material. The deposit, northeast of the Rachmaninoff basin, is depleted in S (relative to Ca and Si) and C, compared with the rest of Mercury's surface. Spectral reflectance measurements of the deposit indicate relatively high overall reflectance and an oxygen-metal charge transfer (OMCT) absorption band at ultraviolet wavelengths. These results are consistent with oxidation of graphite and sulfides during magma ascent, via reaction with oxides in the magma or assimilated country rock, and the formation of S- and C-bearing volatile species. Consumption of graphite during oxidation could account for the elevated reflectance of the pyroclastic material, and the strength of the OMCT band is consistent with ~0.03-0.1 wt % FeO in the deposit.

  9. The MESSENGER mission to Mercury: new insights into geological processes and evolution

    NASA Astrophysics Data System (ADS)

    Head, James W., III; Solomon, Sean C.; McNutt, Ralph L., Jr.; Blewett, David T.; Chapman, Clark R.; Domingue, Deborah L.; Evans, Larry G.; Gillis-Davis, Jeffrey J.; Hawkins, S. Edward, III; Helbert, Jörn; Holsclaw, Gregory M.; Izenberg, Noam R.; McClintock, William E.; McCoy, Timothy J.; Merline, William J.; Murchie, Scott L.; Nittler, Larrz R.; Phillips, Roger J.; Prockter, Louise M.; Robinson, Mark S.; Sprague, Ann L.; Strom, Robert G.; Vilas, Faith; Watters, Thomas R.; Zuber, Maria T.

    2008-09-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, a part of NASA's Discovery Program, was designed to answer six questions [1]: (1) What planetary formational processes led to Mercury's high ratio of metal to silicate? (2) What is the geological history of Mercury? (3) What are the nature and origin of Mercury's magnetic field? (4) What are the structure and state of Mercury's core? (5) What are the radar-reflective materials at Mercury's poles? (6) What are the important volatile species and their sources and sinks near Mercury? MESSENGER is currently midway through a complex interplanetary cruise phase that involves three flybys of Mercury. The first of these, on 14 January 2008, provided important new information relating to several of the questions above [2-13]. Here we summarize observations made during the flyby that are most relevant to new insights about geological processes that have operated on Mercury and implications for the planet's history [3, 8-13]. The instruments that provided the most direct information on the geological history of Mercury during this first encounter were the Mercury Dual Imaging System (MDIS) [14], the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) [15], and the Mercury Laser Altimeter (MLA) [16]. Among the many specific questions remaining following the Mariner 10 mission to Mercury (1974- 1975) were (1) the level of mineralogical and compositional diversity of the crust, which appeared relatively bland in Mariner 10 data, (2) the nature of the rest of the huge Caloris impact basin seen only partially in Mariner 10 images, (3) the origin of the extensive plains observed on the surface (ponded impact ejecta or extrusive lava flows?), (4) the diversity and global distribution of tectonic features that have deformed the crust and their implications for strain as a function of time, and (5) the bombardment chronology and geological history of Mercury [1, 17-19]. The viewing

  10. Virus-Specific Messenger RNA and Nascent Polypeptides in Polyribosomes of Cells Replicating Murine Sarcoma-Leukemia Viruses

    PubMed Central

    Vecchio, G.; Tsuchida, N.; Shanmugam, G.; Green, M.

    1973-01-01

    We present evidence that virus-specific RNA is present in polyribosomes of transformed cells replicating the murine sarcoma-leukemia virus complex and that it serves as messenger RNA for the synthesis of viral-coded proteins. Both virus-specific RNA (detected by hybridization with the [3H]DNA product of the viral RNA-directed DNA polymerase) and nascent viral polypeptides (measured by precipitation with antiserum to purified virus) were found in membrane-bound and free polyribosomes. Membrane-bound polyribosomes contained a higher content of both virus-specific RNA and nascent viral polypeptides. From 60 to 70% of viral RNA sequences were released from polyribosomes with EDTA, consistent with a function as messenger RNA. Maximum amounts of both virus-specific RNA and nascent viral polypeptides were found in the polyribosome region sedimenting at about 350 S. PMID:4352969

  11. A Functional Assay to Assess Connexin 43-Mediated Cell-to-Cell Communication of Second Messengers in Cultured Bone Cells.

    PubMed

    Stains, Joseph P; Civitelli, Roberto

    2016-01-01

    Cell-to-cell transfer of small molecules is a fundamental way by which multicellular organisms coordinate function. Recent work has highlighted the complexity of biologic responses downstream of gap junctions. As the connexin-regulated effectors are coming into focus, there is a need to develop functional assays that allow specific testing of biologically relevant second messengers. Here, we describe a modification of the classic gap junction parachute assay to assess biologically relevant molecules passed through gap junctions. PMID:27207296

  12. Mobile Router Technology Development

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Stewart, David H.; Bell, Terry L.; Kachmar, Brian A.; Shell, Dan; Leung, Kent

    2002-01-01

    Cisco Systems and NASA have been performing joint research on mobile routing technology under a NASA Space Act Agreement. Cisco developed mobile router technology and provided that technology to NASA for applications to aeronautic and space-based missions. NASA has performed stringent performance testing of the mobile router, including the interaction of routing and transport-level protocols. This paper describes mobile routing, the mobile router, and some key configuration parameters. In addition, the paper describes the mobile routing test network and test results documenting the performance of transport protocols in dynamic routing environments.

  13. Interconnect Performance Evaluation of SGI Altix 3700 BX2, Cray X1, Cray Opteron Cluster, and Dell PowerEdge

    NASA Technical Reports Server (NTRS)

    Fatoohi, Rod; Saini, Subbash; Ciotti, Robert

    2006-01-01

    We study the performance of inter-process communication on four high-speed multiprocessor systems using a set of communication benchmarks. The goal is to identify certain limiting factors and bottlenecks with the interconnect of these systems as well as to compare these interconnects. We measured network bandwidth using different number of communicating processors and communication patterns, such as point-to-point communication, collective communication, and dense communication patterns. The four platforms are: a 512-processor SGI Altix 3700 BX2 shared-memory machine with 3.2 GB/s links; a 64-processor (single-streaming) Cray XI shared-memory machine with 32 1.6 GB/s links; a 128-processor Cray Opteron cluster using a Myrinet network; and a 1280-node Dell PowerEdge cluster with an InfiniBand network. Our, results show the impact of the network bandwidth and topology on the overall performance of each interconnect.

  14. MESSENGER, MErcury: Surface, Space ENvironment, GEochemistry, and Ranging; A Mission to Orbit and Explore the Planet Mercury

    NASA Technical Reports Server (NTRS)

    1999-01-01

    MESSENGER is a scientific mission to Mercury. Understanding this extraordinary planet and the forces that have shaped it is fundamental to understanding the processes that have governed the formation, evolution, and dynamics of the terrestrial planets. MESSENGER is a MErcury Surface, Space ENvironment, GEochemistry and Ranging mission to orbit Mercury for one Earth year after completing two flybys of that planet following two flybys of Venus. The necessary flybys return significant new data early in the mission, while the orbital phase, guided by the flyby data, enables a focused scientific investigation of this least-studied terrestrial planet. Answers to key questions about Mercury's high density, crustal composition and structure, volcanic history, core structure, magnetic field generation, polar deposits, exosphere, overall volatile inventory, and magnetosphere are provided by an optimized set of miniaturized space instruments. Our goal is to gain new insight into the formation and evolution of the solar system, including Earth. By traveling to the inner edge of the solar system and exploring a poorly known world, MESSENGER fulfills this quest.

  15. Insight into the messenger role of reactive oxygen intermediates in immunostimulated hemocytes from the scallop Argopecten purpuratus.

    PubMed

    Oyanedel, Daniel; Gonzalez, Roxana; Brokordt, Katherina; Schmitt, Paulina; Mercado, Luis

    2016-12-01

    Reactive oxygen intermediates (ROI) are metabolites produced by aerobic cells which have been linked to oxidative stress. Evidence reported in vertebrates indicates that ROI can also act as messengers in a variety of cellular signaling pathways, including those involved in innate immunity. In a recent study, an inhibitor of NF-kB transcription factors was identified in the scallop Argopecten purpuratus, and its functional characterization suggested that it may regulate the expression of the big defensin antimicrobial peptide ApBD1. In order to give new insights into the messenger role of ROI in the immune response of bivalve mollusks, the effect of ROI production on gene transcription of ApBD1 was assessed in A. purpuratus. The results showed that 48 h-cultured hemocytes were able to display phagocytic activity and ROI production in response to the β-glucan zymosan. The immune stimulation also induced the transcription of ApBD1, which was upregulated in cultured hemocytes. After neutralizing the ROI produced by the stimulated hemocytes with the antioxidant trolox, the transcription of ApBD1 was reduced near to base levels. The results suggest a potential messenger role of intracellular ROI on the regulation of ApBD1 transcription during the immune response of scallops.

  16. Compounds of the sphingomyelin-ceramide-glycosphingolipid pathways as secondary messenger molecules: new targets for novel therapies for fatty liver disease and insulin resistance.

    PubMed

    Ilan, Yaron

    2016-06-01

    The compounds of sphingomyelin-ceramide-glycosphingolipid pathways have been studied as potential secondary messenger molecules in various systems, along with liver function and insulin resistance. Secondary messenger molecules act directly or indirectly to affect cell organelles and intercellular interactions. Their potential role in the pathogenesis of steatohepatitis and diabetes has been suggested. Data samples collected from patients with Gaucher's disease, who had high levels of glucocerebroside, support a role for compounds from these pathways as a messenger molecules in the pathogenesis of fatty liver disease and diabetes. The present review summarizes some of the recent data on the role of glycosphingolipid molecules as messenger molecules in various physiological and pathological conditions, more specifically including insulin resistance and fatty liver disease. PMID:27173510

  17. Ion mobility sensor system

    DOEpatents

    Xu, Jun; Watson, David B.; Whitten, William B.

    2013-01-22

    An ion mobility sensor system including an ion mobility spectrometer and a differential mobility spectrometer coupled to the ion mobility spectrometer. The ion mobility spectrometer has a first chamber having first end and a second end extending along a first direction, and a first electrode system that generates a constant electric field parallel to the first direction. The differential mobility spectrometer includes a second chamber having a third end and a fourth end configured such that a fluid may flow in a second direction from the third end to the fourth end, and a second electrode system that generates an asymmetric electric field within an interior of the second chamber. Additionally, the ion mobility spectrometer and the differential mobility spectrometer form an interface region. Also, the first end and the third end are positioned facing one another so that the constant electric field enters the third end and overlaps the fluid flowing in the second direction.

  18. Tandem mobile robot system

    DOEpatents

    Buttz, James H.; Shirey, David L.; Hayward, David R.

    2003-01-01

    A robotic vehicle system for terrain navigation mobility provides a way to climb stairs, cross crevices, and navigate across difficult terrain by coupling two or more mobile robots with a coupling device and controlling the robots cooperatively in tandem.

  19. Physics of gamma-ray bursts and multi-messenger signals from double neutron star mergers

    NASA Astrophysics Data System (ADS)

    Gao, He

    My dissertation includes two parts: Physics of Gamma-Ray Bursts (GRBs): Gamma-ray bursts are multi-wavelength transients, with both prompt gamma-ray emission and late time afterglow emission observed by telescopes in different wavelengths. I have carried out three investigations to understand GRB prompt emission and afterglow. Chapter 2 develops a new method, namely, "Stepwise Filter Correlation" method, to decompose the variability components in a light curve. After proving its reliability through simulations, we apply this method to 266 bright GRBs and find that the majority of the bursts have clear evidence of superposition of fast and slow variability components. Chapter 3 gives a complete presentation of the analytical approximations for synchrotron self-compton emission for all possible orders of the characteristic synchrotron spectral breaks (nua, nu m, and nuc). We identify a "strong absorption" regime whennua > nuc, and derive the critical condition for this regime. The external shock theory is an elegant theory to model GRB afterglows. It invokes a limit number of model parameters, and has well predicted spectral and temporal properties. Chapter 4 gives a complete reference of all the analytical synchrotron external shock afterglow models by deriving the temporal and spectral indices of all the models in all spectral regimes. This complete reference will serve as a useful tool for afterglow observers to quickly identify relevant models to interpret their data and identify new physics when the models fail. Milti-messenger signals from double neutron star merger: As the multi-messenger era of astronomy ushers in, the second part of the dissertation studies the possible electromagnetic (EM) and neutrino emission counterparts of double neutron star mergers. Chapter 6 suggests that if double neutron star mergers leave behind a massive magnetar rather than a black hole, the magnetar wind could push the ejecta launched during the merger process, and under

  20. Mercury: a final prediction for internal thermal and physical structure, prior to MESSENGER data

    NASA Astrophysics Data System (ADS)

    Prentice, A. J.

    2008-05-01

    The confirmation by the NASA MESSENGER spacecraft that Mercury has an internal magnetic field that is well described by a dipole nearly aligned with the spin axis strongly suggests that the planet may have an outer core of molten metal (S. Solomon, MESSENGER news release of 30 January 2008). The existence of an internal layer of liquid has also been invoked to explain radar measurements of the large amplitude of the longitudinal libration of Mercury relative to the value expected for a wholly solid planet (J.L. Margot et al 2007 Science 316 710). The existence of molten metal in the planet`s interior is surprising since previous numerical models for the thermal evolution of the planet, calculated on the basis of the heat released by the decay of the radioactive isotopes of U and Th, indicated that the present temperature at the edge of the metal core is only ~ 1200 K (cf. Siegfried & Solomon 1974 Icarus 23 192) . This value is well below the melting temperature Tm = 2030 K of Fe-Ni alloy at the core/mantle boundary (CMB) pressure of ~ 70 kbar. Those earlier thermal calculations were, however, based on low abundances of U and Th found in lunar samples. Prentice (2008 LPSC 2008 abs. # 1945.pdf - see URL below) has put forward a new model for the bulk chemical composition of Mercury. It is based on the idea that this planet condensed from a gas ring that was cast off by the protosolar cloud close to the planet`s present orbit. The temperature of the gas ring Tn at the moment of detachment from the cloud is 1628 K and the pressure on the mean orbit of the ring is 0.168 bar. Because Tn is so high, the condensate contains a much reduced proportion of magnesium silicates relative to metals. This is because metals have a much lower vapour pressure than those silicates. The condensate consists mostly of Fe-Ni-Cr-Co-V (mass fraction 0.671), gehlenite (0.190) and Mg-silicates (0.081). What is really important in the gas ring model of solar system origin, however, is that the

  1. The first Messenger data supporting main theses of the wave planetology

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    2008-09-01

    The first fundamental statement of the wave planetology [1-6 & others] is about ubiquity of tectonic dichotomy. All celestial bodies move, as it was established by I. Kepler, in non-round but elliptical orbits. This means that they all notwithstanding their sizes, masses, physical states and chemical compositions have alternating increasing and decreasing accelerations producing forces (Newton: F = m·a) warping celestial bodies. This wave warping rotating bodies (but all bodies rotate!) is decomposed into four orthogonal and diagonal directions of standing waves. An interference of these directions gives tectonic blocks of three kinds: uplifting (+), subsiding (-) and neutral (0). The block sizes depend on warping wavelengths. The fundamental wave long 2πR (R - a body radius) is present in all bodies thus making one hemisphere rising and the opposite one falling (more precise relation is 1/3 to 2/3 or 2/3 to 1/3). A geometrical proof of this relation is given in [6] where two famous tectonic dichotomies of Earth and Mars were explained by one wave reason. This ubiquitous phenomenon was described as the first theorem of the wave planetology: "Celestial bodies are dichotomous". There are many examples proving it among planets, satellites and asteroids, even Sun is dichotomous. But up to recent time the studied partially Mercury's surface was not a good example of this phenomenon as not fully visible Caloris basin didn't show its real dimension. Now, after the Messenger flyby we know that it is about 1500 km in diameter, that is about 1/3 of the Mercury's diameter and the rule is not violated. The third theorem of the wave planetary tectonics states: "Celestial bodies are granular". This means that celestial bodies are warped by individual waves lengths of which are inversely proportional to their orbital frequencies: higher frequency - finer granules, lower frequency - larger granules (Fig. 1). Observations fully support it not only in sense of granules diameters

  2. MESSENGER and Mariner 10 Flyby Observations of Magnetotail Structure and Dynamics at Mercury

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    The first (M1), second (M2), and third (M3) MESSENGER flybys of Mercury traversed the planet's magnetotail from 1.25 to 3.25 RM downstream of the planet, where R(sub M) is Mercury's radius (2440 km). The encounters took place under northward, southward, and variable-polarity interplanetary magnetic field (IMF), respectively. The magnetic field strength B in Mercury's magnetotail follows a power law decrease with increasing antisunward distance |X|, B approximately |X|(sup G), with G varying from -5.4 for northward to -1.6 for southward IMF. Low-latitude boundary layers (LLBLs) containing strong northward magnetic field were detected at the tail flanks during two of the flybys. The observed thickness of the LLBL was 33% and 16% of the radius of the tail during M1 and M3, respectively, but the boundary layer was completely absent during M2. Clear signatures of tail reconnection are evident in the M2 and M3 magnetic field measurements. Plasmoids and traveling compression regions were observed during M2 and M3 with typical durations of approximately 1-3 s, suggesting diameters of approximately 500-1500 km. Overall, the response of Mercury's magnetotail to the steady southward IMF during M2 appeared very similar to steady magnetospheric convection events at Earth, which are believed to be driven by quasi-continuous reconnection. In contrast, the M3 measurements are dominated by tail loading and unloading events that resemble the large-scale magnetic field reconfigurations observed during magnetospheric substorms at Earth.

  3. Element Abundances in High-temperature Solar Flare Plasma from MESSENGER SAX Observations

    NASA Astrophysics Data System (ADS)

    Dennis, Brian R.; Nittler, Larry R.; Phillips, Kenneth; Schwartz, Richard A.; Starr, Richard D.; Tolbert, Anne K

    2014-06-01

    X-ray spectral measurements of many solar flares made with the MESSENGER SAX instrument have been used to determine the abundances of Fe, Ca, Ar, S, and Si in the high temperature plasma. All available data from launch in 2004 to date have been used to obtain spectral fits to the SAX data from 2.3 to 8.5 keV for all time intervals with a detectable count rate in the Fe-line complex at 6.7 keV. For each time interval, OSPEX, our object-oriented IDL spectral analysis program, is used to obtain values of the emission measure, temperature distribution, and abundances that give the best-fit of the corresponding CHIANTI photon spectrum folded through the instrument response matrix to the measured count-rate spectrum above background. Distributions will be presented of element abundances for each flare and for all flares detected during each year of observations. Variations in measured abundances will be discussed as to whether they reflect real differences from the mean or differences due to statistical and/or systematic uncertainties. Comparisons will be made with abundance measurements made from other data sets, in particular by Phillips and Dennis (2012) using data from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and by Warren et al. (2013) using data from the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO).Phillips, K. J. H. and Dennis, B. R., “The Solar Flare Iron Abundance,” 2012, ApJ, 748, 52.Warren, H. “Measurements of Absolute Abundances in Solar Flares,” 2013, arXiv, 2013arXiv1310.4765W

  4. An Overview of Ultraviolet Through Infrared Reflectance Spectroscopic Observations of Mercury During the First MESSENGER Flyby

    NASA Astrophysics Data System (ADS)

    Izenberg, N. R.; McClintock, W. E.; Holsclaw, G. M.; Robinson, M. S.; Blewett, D. T.; Domingue, D. L.; Head, J. W.; Jensen, E. A.; Kochte, M. C.; Lankton, M. R.; Murchie, S. L.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2008-05-01

    During the first MESSENGER flyby of Mercury on January 14, 2008, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) measured reflectance spectra from Mercury's surface over the wavelength range 220-1450 nm. These are the first high-spatial-resolution (<10 km) spectra at any wavelength and the first reported ultraviolet (UV, wavelength < 360 nm) observations of the surface. MASCS observed the sunlit surface for approximately 14 minutes after closest approach, acquiring over 650 spectra with the Visible and Infrared Spectrograph (VIRS) detectors of MASCS sensitive to wavelengths of 350-1450 nm. MASCS also obtained just under four grating scans in the middle ultraviolet (220-320 nm) using MASCS's Ultraviolet and Visible Spectrometer (UVVS) component. Most of the near-equatorial ground track of the observation covered terrain in the previously unseen hemisphere of Mercury but also crossed into the hemisphere viewed by Mariner 10 south of Mozart crater and in Tir Planitia. Ground-based observations of Mercury reveal a surface with a red, nearly featureless spectrum in the visible and near-infrared (wavelengths greater than ~ 500 nm) that has been interpreted as evidence for a largely iron-poor feldspathic composition. Initial analyses of VIRS spectra also show strongly red-sloped, near featureless spectra, appearing to support contentions of low iron abundance in surface materials. However, interpretation of Mercury's spectral reflectance is complicated by our lack of knowledge about the effects on its surface materials of space weathering, which both suppresses the strength of spectral absorption features and reddens the spectrum. Brightness variations and absorption bands in ultraviolet reflectance may help determine both the nature and extent of processes that modify observed reflectance at longer wavelengths. MASCS surface observation data demonstrate spectral variations across the Mercury surface that can be related to previous telescopic

  5. Multi-messenger Tests for Fast-spinning Newborn Pulsars Embedded in Stripped-envelope Supernovae

    NASA Astrophysics Data System (ADS)

    Kashiyama, Kazumi; Murase, Kohta; Bartos, Imre; Kiuchi, Kenta; Margutti, Raffaella

    2016-02-01

    Fast-spinning strongly magnetized newborn neutron stars (NSs), including nascent magnetars, are popularly implemented as the engine of luminous stellar explosions. Here, we consider the scenario that they power various stripped-envelope (SE) supernovae (SNe), not only superluminous SNe Ic but also broad-line (BL) SNe Ibc and possibly some ordinary SNe Ibc. This scenario is also motivated by the hypothesis that Galactic magnetars largely originate from fast-spinning NSs as remnants of SE SNe. By consistently modeling the energy injection from magnetized wind and {}56{Ni} decay, we show that proto-NSs with ≳ 10 {ms} rotation and a poloidal magnetic field of {B}{{dip}}≳ 5× {10}14 {{G}} can be harbored in ordinary SNe Ibc. On the other hand, millisecond proto-NSs can solely power BL SNe Ibc if they are born with {B}{{dip}}≳ 5× {10}14 {{G}} and superluminous SNe Ic with {B}{{dip}}≳ {10}13 {{G}}. Then, we study how multi-messenger emission can be used to discriminate such pulsar-driven SN models from other competitive scenarios. First, high-energy X-ray and gamma-ray emission from embryonic pulsar wind nebulae can probe the underlying newborn pulsar. Follow-up observations of SE SNe using NuSTAR ∼ 50{--}100 {days} after the explosion are strongly encouraged for nearby objects. We also discuss possible effects of gravitational waves (GWs) on the spin-down of proto-NSs. If millisecond proto-NSs with {B}{{dip}}\\lt {{a}} {few}× {10}13 {{G}} emit GWs through, e.g., non-axisymmetric rotation deformed by the inner toroidal fields of {B}{{t}}≳ {10}16 {{G}}, the GW signal can be detectable from ordinary SNe Ibc in the Virgo cluster by Advanced LIGO, Advanced Virgo, and KAGRA.

  6. MESSENGER Observations of the Dayside Low-Latitude Boundary Layer in Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Liljeblad, E. I.; Karlsson, T.; Raines, J. M.; Slavin, J. A.; Kullen, A.; Sundberg, T.; Zurbuchen, T.

    2015-12-01

    Observations from MESSENGER's MAG and FIPS instruments during the first orbital year have resulted in the identification of 25 magnetopause crossings in Mercury's magnetosphere with significant low-latitude boundary layers (LLBLs). The large majority of these crossings are observed on the dawnside and for northward interplanetary magnetic field. The estimated LLBL thickness is 450±56 km, and increases with distance to noon. The Na+-group ion is sporadically present in 14 of the boundary layers, with an observed average number density of 22±11 % of the proton density. Furthermore, the average Na+-group gyroradii in the layers is 220±34 km, the same order of magnitude as the LLBL thickness. Magnetic shear, plasma β and reconnection rates have been estimated for the LLBL crossings, and compared to those of a control group (non-LLBL) of 61 distinct magnetopause crossings which show signs of nearly no plasma inside the magnetopause. The results indicate that reconnection is significantly slower, or even suppressed, for the LLBL crossings compared to the non-LLBL cases. Possible processes that form or impact the LLBL are discussed. Protons injected through the cusp or flank may be important for the formation of the LLBL. Furthermore, the opposite asymmetry in the Kelvin-Helmholtz instability (KHI) as compared to the LLBL, rules out the KHI as a dominant formation mechanism. However, the KHI and LLBL could be related to each other, either by the impact of sodium ions gyrating across the magnetopause, or by the LLBL preventing the growth of KH waves on the dawnside.

  7. Morphometry of impact craters on Mercury from MESSENGER altimetry and imaging

    NASA Astrophysics Data System (ADS)

    Susorney, Hannah C. M.; Barnouin, Olivier S.; Ernst, Carolyn M.; Johnson, Catherine L.

    2016-06-01

    Data acquired by the Mercury Laser Altimeter and the Mercury Dual Imaging System on the MESSENGER spacecraft in orbit about Mercury provide a means to measure the geometry of many of the impact craters in Mercury's northern hemisphere in detail for the first time. The combination of topographic and imaging data permit a systematic evaluation of impact crater morphometry on Mercury, a new calculation of the diameter Dt at which craters transition with increasing diameter from simple to complex forms, and an exploration of the role of target properties and impact velocity on final crater size and shape. Measurements of impact crater depth on Mercury confirm results from previous studies, with the exception that the depths of large complex craters are typically shallower at a given diameter than reported from Mariner 10 data. Secondary craters on Mercury are generally shallower than primary craters of the same diameter. No significant differences are observed between the depths of craters within heavily cratered terrain and those of craters within smooth plains. The morphological attributes of craters that reflect the transition from simple to complex craters do not appear at the same diameter; instead flat floors first appear with increasing diameter in craters at the smallest diameters, followed with increasing diameter by reduced crater depth and rim height, and then collapse and terracing of crater walls. Differences reported by others in Dt between Mercury and Mars (despite the similar surface gravitational acceleration on the two bodies) are confirmed in this study. The variations in Dt between Mercury and Mars cannot be adequately attributed to differences in either surface properties or mean projectile velocity.

  8. RNomics in Drosophila melanogaster: identification of 66 candidates for novel non-messenger RNAs

    PubMed Central

    Yuan, Guozhong; Klämbt, Christian; Bachellerie, Jean-Pierre; Brosius, Jürgen; Hüttenhofer, Alexander

    2003-01-01

    By generating a specialised cDNA library from four different developmental stages of Drosophila melanogaster, we have identified 66 candidates for small non-messenger RNAs (snmRNAs) and have confirmed their expression by northern blot analysis. Thirteen of them were expressed at certain stages of D.melanogaster development, only. Thirty-five species belong to the class of small nucleolar RNAs (snoRNAs), divided into 15 members from the C/D subclass and 20 members from the H/ACA subclass, which mostly guide 2′-O-methylation and pseudouridylation, respectively, of rRNA and snRNAs. These also include two outstanding C/D snoRNAs, U3 and U14, both functioning as pre-rRNA chaperones. Surprisingly, the sequence of the Drosophila U14 snoRNA reflects a major change of function of this snoRNA in Diptera relative to yeast and vertebrates. Among the 22 snmRNAs lacking known sequence and structure motifs, five were located in intergenic regions, two in introns, five in untranslated regions of mRNAs, eight were derived from open reading frames, and two were transcribed opposite to an intron. Interestingly, detection of two RNA species from this group implies that certain snmRNA species are processed from alternatively spliced pre-mRNAs. Surprisingly, a few snmRNA sequences could not be found on the published D.melanogaster genome, which might suggest that more snmRNA genes (as well as mRNAs) are hidden in unsequenced regions of the genome. PMID:12736298

  9. Parathyroid hormone induces c-fos and c-jun messenger RNA in rat osteoblastic cells

    NASA Technical Reports Server (NTRS)

    Clohisy, J. C.; Scott, D. K.; Brakenhoff, K. D.; Quinn, C. O.; Partridge, N. C.

    1992-01-01

    PTH is a potent regulator of osteoblast gene expression, yet the nuclear events that mediate PTH action are poorly understood. We were interested in identifying immediate early genes which may regulate PTH-altered gene expression in the osteoblast. Therefore, we examined the effects of PTH on c-fos and c-jun gene expression in a rat osteoblastic cell line (UMR 106-01). Under control conditions, c-fos and c-jun mRNAs were present at low basal levels. After PTH treatment, c-fos mRNA abundance dramatically increased, with a maximal and transient response at 30 min. PTH also stimulated an increase in c-jun mRNA, but in a biphasic manner, with maximal levels at 30 min and 2 h. These responses were dose dependent, not altered by cotreatment with the protein synthesis inhibitor cycloheximide, and preceded PTH-induced expression of matrix metallo-proteinase-1 mRNA. Nuclear run-on assays demonstrated an increased rate of c-fos and c-jun transcription after PTH exposure. To determine the signal transduction pathways involved, second messenger analogs were tested for their ability to mimic the effects of PTH. 8-Bromo-cAMP and phorbol 12-myristate 13-acetate (PMA) caused increases in the abundance of c-fos and c-jun transcripts. Ionomycin had no effect on the expression of these genes. Pretreatment of the cells with PMA resulted in a decrease in basal c-jun expression, but did not alter the PTH-mediated increase in c-fos, c-jun, or matrix metalloproteinase-1 mRNAs.(ABSTRACT TRUNCATED AT 250 WORDS).

  10. Proteobacterial ArfA peptides are synthesized from non-stop messenger RNAs.

    PubMed

    Schaub, Ryan E; Poole, Stephen J; Garza-Sánchez, Fernando; Benbow, Sarah; Hayes, Christopher S

    2012-08-24

    The translation of non-stop mRNA (which lack in-frame stop codons) represents a significant quality control problem for all organisms. In eubacteria, the transfer-messenger RNA (tmRNA) system facilitates recycling of stalled ribosomes from non-stop mRNA in a process termed trans-translation or ribosome rescue. During rescue, the nascent chain is tagged with the tmRNA-encoded ssrA peptide, which promotes polypeptide degradation after release from the stalled ribosome. Escherichia coli possesses an additional ribosome rescue pathway mediated by the ArfA peptide. The E. coli arfA message contains a hairpin structure that is cleaved by RNase III to produce a non-stop transcript. Therefore, ArfA levels are controlled by tmRNA through ssrA-peptide tagging and proteolysis. Here, we examine whether ArfA homologues from other bacteria are also regulated by RNase III and tmRNA. We searched 431 arfA coding sequences for mRNA secondary structures and found that 82.8% of the transcripts contain predicted hairpins in their 3'-coding regions. The arfA hairpins from Haemophilus influenzae, Proteus mirabilis, Vibrio fischeri, and Pasteurella multocida are all cleaved by RNase III as predicted, whereas the hairpin from Neisseria gonorrhoeae functions as an intrinsic transcription terminator to generate non-stop mRNA. Each ArfA homologue is ssrA-tagged and degraded when expressed in wild-type E. coli cells, but accumulates in mutants lacking tmRNA. Together, these findings show that ArfA synthesis from non-stop mRNA is a conserved mechanism to regulate the alternative ribosome rescue pathway. This strategy ensures that ArfA homologues are only deployed when the tmRNA system is incapacitated or overwhelmed by stalled ribosomes. PMID:22791716

  11. Spatial distribution of Mercury's flux ropes and reconnection fronts: MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Sun, W. J.; Fu, S. Y.; Slavin, J. A.; Raines, J. M.; Zong, Q. G.; Poh, G. K.; Zurbuchen, T. H.

    2016-08-01

    We perform a statistical study of flux ropes and reconnection fronts based on MErcury Surface, Space ENviroment, GEochemistry, and Ranging (MESSENGER) magnetic field and plasma observations to study the implications for the spatial distribution of reconnection sites in Mercury's near magnetotail. The results show important differences of temporal and spatial distributions as compared to Earth. We have surveyed the plasma sheet crossings between -2 RM and -3 RM downtail from the planet, i.e., the location of Near-Mercury Neutral Line (NMNL). Plasma sheets were defined to be regions with β ≥ 0.5. Using this definition, 39 flux ropes and 86 reconnection fronts were identified in the plasma sheet. At Mercury, the distributions of flux ropes and reconnection fronts show clear dawn-dusk asymmetry with much higher occurrence rate on the dawnside plasma sheet than on the duskside. This suggests that magnetic reconnection in Mercury's magnetotail occurs more frequently in the dawnside than in the duskside plasma sheet, which is different than the observations in Earth's magnetotail showing more reconnection signatures in the duskside plasma sheet. The distribution of plasma sheet thickness shows that plasma sheet near the midnight is the thinnest part and does not show obvious asymmetry. Thus, the reasons that cause magnetic reconnection to preferentially occur on the dawnside of the magnetotail at Mercury may not be the plasma sheet thickness and require further study. The peak occurrence rates of flux ropes and reconnection fronts in Mercury's plasma sheet are ~ 60 times higher than that of Earth's values, which we interpret to be due to the highly variable magnetospheric conditions at Mercury. Such higher occurrence rate of magnetic reconnection would generate more plasma flows in the dawnside plasma sheet than in the duskside. These plasma flows would mostly brake and initiate the substorm dipolarization on the postmidnight sector at Mercury rather than the

  12. A Novel Route Controlling Begomovirus Resistance by the Messenger RNA Surveillance Factor Pelota.

    PubMed

    Lapidot, Moshe; Karniel, Uri; Gelbart, Dana; Fogel, Doron; Evenor, Dalia; Kutsher, Yaarit; Makhbash, Zion; Nahon, Sahadia; Shlomo, Haviva; Chen, Lea; Reuveni, Moshe; Levin, Ilan

    2015-10-01

    Tomato yellow leaf curl virus (TYLCV) is a devastating disease of tomato (Solanum lycopersicum) that can be effectively controlled by the deployment of resistant cultivars. The TYLCV-resistant line TY172 carries a major recessive locus for TYLCV resistance, designated ty-5, on chromosome 4. In this study, the association between 27 polymorphic DNA markers, spanning the ty-5 locus, and the resistance characteristics of individual plants inoculated with TYLCV in 51 segregating recombinant populations were analyzed. These analyses localized ty-5 into a 425 bp region containing two transversions: one in the first exon of a gene encoding the tomato homolog of the messenger RNA surveillance factor Pelota (Pelo), and a second in its proximal promoter. Analyses of susceptible and resistant lines revealed that the relative transcript level of the gene remained unchanged, regardless of whether the plants were infected with TYLCV or not. This suggests that the polymorphism discovered in the coding region of the gene controls the resistance. Silencing of Pelo in a susceptible line rendered the transgenic plants highly resistant, while in the resistant line TY172 had no effect on symptom development. In addition, over-expression of the susceptible allele of the gene in the resistant TY172 line rendered it susceptible, while over-expression of the resistant allele in susceptible plants had no effect. These results confirm that Pelo is the gene controlling resistance at the ty-5 locus. Pelo, implicated in the ribosome recycling-phase of protein synthesis, offers an alternative route to promote resistance to TYLCV and other viruses. PMID:26448569

  13. Analysis of MESSENGER high-resolution images of Mercury's hollows and implications for hollow formation

    NASA Astrophysics Data System (ADS)

    Blewett, David T.; Stadermann, Amanda C.; Susorney, Hannah C.; Ernst, Carolyn M.; Xiao, Zhiyong; Chabot, Nancy L.; Denevi, Brett W.; Murchie, Scott L.; McCubbin, Francis M.; Kinczyk, Mallory J.; Gillis-Davis, Jeffrey J.; Solomon, Sean C.

    2016-09-01

    High-resolution images from MESSENGER provide morphological information on the nature and origin of Mercury's hollows, small depressions that likely formed when a volatile constituent was lost from the surface. Because graphite may be a component of the low-reflectance material that hosts hollows, we suggest that loss of carbon by ion sputtering or conversion to methane by proton irradiation could contribute to hollows formation. Measurements of widespread hollows in 565 images with pixel scales <20 m indicate that the average depth of hollows is 24 ± 16 m. We propose that hollows cease to increase in depth when a volatile-depleted lag deposit becomes sufficiently thick to protect the underlying surface. The difficulty of developing a lag on steep topography may account for the common occurrence of hollows on crater central peaks and walls. Disruption of the lag, e.g., by secondary cratering, could restart growth of hollows in a location that had been dormant. Images at extremely high resolution (~3 m/pixel) show that the edges of hollows are straight, as expected if the margins formed by scarp retreat. These highest-resolution images reveal no superposed impact craters, implying that hollows are very young. The width of hollows within rayed crater Balanchine suggests that the maximum time for lateral growth by 1 cm is ~10,000 yr. A process other than entrainment of dust by gases evolved in a steady-state sublimation-like process is likely required to explain the high-reflectance haloes that surround many hollows.

  14. A Novel Route Controlling Begomovirus Resistance by the Messenger RNA Surveillance Factor Pelota

    PubMed Central

    Lapidot, Moshe; Karniel, Uri; Gelbart, Dana; Fogel, Doron; Evenor, Dalia; Kutsher, Yaarit; Makhbash, Zion; Nahon, Sahadia; Shlomo, Haviva; Chen, Lea; Reuveni, Moshe; Levin, Ilan

    2015-01-01

    Tomato yellow leaf curl virus (TYLCV) is a devastating disease of tomato (Solanum lycopersicum) that can be effectively controlled by the deployment of resistant cultivars. The TYLCV-resistant line TY172 carries a major recessive locus for TYLCV resistance, designated ty-5, on chromosome 4. In this study, the association between 27 polymorphic DNA markers, spanning the ty-5 locus, and the resistance characteristics of individual plants inoculated with TYLCV in 51 segregating recombinant populations were analyzed. These analyses localized ty-5 into a 425 bp region containing two transversions: one in the first exon of a gene encoding the tomato homolog of the messenger RNA surveillance factor Pelota (Pelo), and a second in its proximal promoter. Analyses of susceptible and resistant lines revealed that the relative transcript level of the gene remained unchanged, regardless of whether the plants were infected with TYLCV or not. This suggests that the polymorphism discovered in the coding region of the gene controls the resistance. Silencing of Pelo in a susceptible line rendered the transgenic plants highly resistant, while in the resistant line TY172 had no effect on symptom development. In addition, over-expression of the susceptible allele of the gene in the resistant TY172 line rendered it susceptible, while over-expression of the resistant allele in susceptible plants had no effect. These results confirm that Pelo is the gene controlling resistance at the ty-5 locus. Pelo, implicated in the ribosome recycling-phase of protein synthesis, offers an alternative route to promote resistance to TYLCV and other viruses. PMID:26448569

  15. The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation.

    PubMed

    Wang, S; Leonard, S S; Ye, J; Ding, M; Shi, X

    2000-09-01

    The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (.OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O(2)(-).), hydrogen peroxide (H(2)O(2)), and.OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H(2)O(2) from O(2)(-). radicals, increased p53 activity. Catalase, an H(2)O(2) scavenger, eliminated.OH radical generation and inhibited p53 activation. Sodium formate and aspirin,.OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H(2)O(2). NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased.OH radical generation, dramatically enhanced p53 activation. Thus.OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation.

  16. The Determination of the Gravity Field of Mercury from MESSENGER data

    NASA Astrophysics Data System (ADS)

    Lemoine, F. G.; Mazarico, E.; Rowlands, D. D.; Torrence, M. H.; Perry, M. E.; Smith, D. E.; Zuber, M. T.

    2011-12-01

    The MESSENGER spacecraft entered orbit about Mercury in March 2011, becoming the first spacecraft to orbit the innermost planet. The spacecraft is in a highly eccentric, near-polar orbit with an inclination near 82.5 deg., a period of nearly 12 hrs, a periapsis latitude near 60 deg.N, and a periapsis altitude that varies between 200 and 500 km. The spacecraft is tracked by the antennae of the Deep Space Network (DSN), and the X band data have been analyzed to determine spherical harmonic models of the gravity field of Mercury to degree and order 20. The a priori modeling includes the Margot (2010) orientation model for Mercury and the DE421 set of planetary ephemerides. A detailed non-conservative model has been developed to account for the radiation pressure perturbations on the spacecraft, including both the solar radiation pressure and the planetary radiation pressure. This last analysis includes a box-wing model, use of quaternions to model the spacecraft attitude, and a model of the planet's thermal emission. The data have been analyzed primarily in one-day arcs. The data coverage, which now span several Mercury sidereal days, includes direct Doppler observations below 1500 km altitude throughout the northern hemisphere to just south of the equator. In this paper, we discuss the quality of the DSN tracking data and the details of the force and measurement models used in the analyses, and we show how the solutions have been refined as additional data have been obtained. We show the stability of the solutions for the lower-degree harmonics, including C20, C22, S22, and C30.

  17. Bacterial rotary export ATPases are allosterically regulated by the nucleotide second messenger cyclic-di-GMP.

    PubMed

    Trampari, Eleftheria; Stevenson, Clare E M; Little, Richard H; Wilhelm, Thomas; Lawson, David M; Malone, Jacob G

    2015-10-01

    The widespread second messenger molecule cyclic di-GMP (cdG) regulates the transition from motile and virulent lifestyles to sessile, biofilm-forming ones in a wide range of bacteria. Many pathogenic and commensal bacterial-host interactions are known to be controlled by cdG signaling. Although the biochemistry of cyclic dinucleotide metabolism is well understood, much remains to be discovered about the downstream signaling pathways that induce bacterial responses upon cdG binding. As part of our ongoing research into the role of cdG signaling in plant-associated Pseudomonas species, we carried out an affinity capture screen for cdG binding proteins in the model organism Pseudomonas fluorescens SBW25. The flagella export AAA+ ATPase FliI was identified as a result of this screen and subsequently shown to bind specifically to the cdG molecule, with a KD in the low micromolar range. The interaction between FliI and cdG appears to be very widespread. In addition to FliI homologs from diverse bacterial species, high affinity binding was also observed for the type III secretion system homolog HrcN and the type VI ATPase ClpB2. The addition of cdG was shown to inhibit FliI and HrcN ATPase activity in vitro. Finally, a combination of site-specific mutagenesis, mass spectrometry, and in silico analysis was used to predict that cdG binds to FliI in a pocket of highly conserved residues at the interface between two FliI subunits. Our results suggest a novel, fundamental role for cdG in controlling the function of multiple important bacterial export pathways, through direct allosteric control of export ATPase proteins.

  18. Constraints on Mercury's Na Exosphere: Combined MESSENGER and Ground-Based Data

    NASA Technical Reports Server (NTRS)

    Mouawad, Nelly; Burger, Matthew H.; Killen, Rosemary M.; Potter, Andrew E.; McClintock, William E.; Vervack, Ronald J., Jr.; Bradley, E. Todd; Benna, Mehdi; Naidu, Shantanu

    2010-01-01

    We have used observations of sodium emission obtained with the McMath-Pierce solar telescope and MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) to constrain models of Mercury's sodium exosphere, The distribution of sodium in Mercury's exosphere during the period January 12-15. 2008. was mapped using the McMath-Pierce solar telescope with the 5" X 5" image slicer to observe the D-line emission. On January 14, 2008, the Ultraviolet and Visible Spectrometer (UVVS) channel on MASCS sampled the sodium in Mercury's anti-sunward tail region. We find that the bound exosphere has an equivalent temperature of 900-1200 K, and that this temperature can be achieved if the sodium is ejected either by photon-stimulated desorption (PSD) with a 1200 K Maxwellian velocity distribution, or by thermal accommodation of a hotter source. We were not able to discriminate between the two assumed velocity distributions of the ejected particles for the PSD. but the velocity distributions require different values of the thermal accommodation coefficient and result in different upper limits on impact vaporization, We were able to place a strong constraint on the impact vaporization rate that results in the release of neutral Na atoms with an upper limit of 2.1 x 10(exp 6) sq cm/s, The variability of the week-long ground-based observations can be explained by variations in the sources, including both PSD and ion-enhanced PSD, as well as possible temporal enhancements in meteoroid vaporization. Knowledge of both dayside and anti-sunward tail morphologies and radiances are necessary to correctly deduce the exospheric source rates, processes, velocity distribution, and surface interaction.

  19. Cellular localization of type 1 plasminogen activator inhibitor messenger RNA and protein in murine renal tissue.

    PubMed Central

    Keeton, M.; Eguchi, Y.; Sawdey, M.; Ahn, C.; Loskutoff, D. J.

    1993-01-01

    Type 1 plasminogen activator inhibitor (PAI-1) may be markedly increased in the plasma of patients with endotoxemia and/or renal disease. To investigate renal PAI-1 production during acute endotoxemia, a murine model system was used. Mice were injected with either saline alone or saline containing 50 micrograms endotoxin, and sacrificed 3 hours later and their tissues analyzed for PAI-1 messenger RNA (mRNA) and antigen. Northern blot analysis confirmed that the level of renal PAI-1 mRNA was greatly increased in the endotoxemic mice relative to the saline controls. In situ hybridization was then performed to determine the cellular localization of PAI-1 mRNA within the renal tissues. In the control kidneys, low levels of PAI-1 mRNA were detected in the renal papilla and in the muscular walls of renal arteries. However, in the endotoxemic mice, an intense hybridization signal for PAI-1 mRNA was observed in glomerular and peritubular cells. These cells also stained positively for von Willebrand factor antigen, an endothelial cell-specific marker. The PAI-1 mRNA hybridization signal could further be observed in peritubular endothelial cells in the medulla and in endothelial cells of veins and arteries throughout the kidney. Immunochemical analysis revealed that PAI-1 antigen co-localized to the cytoplasm of cells expressing PAI-1 mRNA. This study provides the first direct evidence that PAI-1 is induced in endothelial cells of the kidney during endotoxemia in vivo and suggests a role for PAI-1 in the pathogenesis of renal disease. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:8424466

  20. Differential messenger RNA gradients in the unicellular alga Acetabularia acetabulum. Role of the cytoskeleton.

    PubMed

    Vogel, Heiko; Grieninger, Gerd E; Zetsche, Klaus H

    2002-07-01

    The unicellular green alga Acetabularia acetabulum has proven itself to be a superior model for studies of morphogenesis because of its large size and distinctive polar morphology. The giant cell forms an elongated tube (a stalk of up to 60 mm in length), which at its apical pole makes whorls of hairs, followed by one whorl of gametophores in the shape of a cap. At its basal pole, the cell extends into a rhizoid wherein the single nucleus is positioned. In this study, we have determined the level of specific messenger RNAs in the apical, middle, and basal regions using reverse transcriptase-PCR methodology. Four mRNA classes were distinguished: those that were uniformly distributed (small subunit of Rubisco, actin-1, ADP-glucose, centrin, and alpha- and beta-tubulin), those that expressed apical/basal (calmodulin-4) or basal/apical gradients (calmodulin-2 and a Ran-G protein), and those with development-specific patterns of distribution (mitogen-activated protein kinase, actin-2, and UDP-glucose-epimerase). Restoration of the apical/basal calmodulin-4 mRNA gradient after amputation of the apical region of the cell requires the nucleus and was abolished by cytochalasin D. Accumulation of actin-1 mRNA in the vicinity of the wound set by the amputation needs, likewise, the presence of the nucleus and was also inhibited by cytochalasin. This suggests that actin microfilaments of the cytoskeleton are involved in directed transport and/or anchoring of these mRNAs.

  1. Superintendent Vulnerability and Mobility.

    ERIC Educational Resources Information Center

    Parker, Phyllis

    1996-01-01

    Examined Callahan's vulnerability thesis to determine its ability to explain the mobility of superintendents in Texas between 1985 and 1990. Questionnaire and interview data indicated that, at least in Texas where superintendent mobility reached 50% in that time period, vulnerability did not appear to account for much of superintendent mobility.…

  2. Mobility and Young Children.

    ERIC Educational Resources Information Center

    Bernard van Leer Foundation Newsletter, 1994

    1994-01-01

    This newsletter theme issue deals with the phenomenon of mobility or transience in India, Kenya, Greece, Ireland, Malaysia, Thailand and Israel. The primary focus is on mobility's effect on young children, specifically their health and education; some of the broader concerns also addressed by the newsletter are the causes of mobility and its…

  3. Mobile Student Information System

    ERIC Educational Resources Information Center

    Asif, Muhammad; Krogstie, John

    2011-01-01

    Purpose: A mobile student information system (MSIS) based on mobile computing and context-aware application concepts can provide more user-centric information services to students. The purpose of this paper is to describe a system for providing relevant information to students on a mobile platform. Design/methodology/approach: The research…

  4. Ion mobility sensor

    DOEpatents

    Koo, Jackson C.; Yu, Conrad M.

    2005-08-23

    An ion mobility sensor which can detect both ion and molecules simultaneously. Thus, one can measure the relative arrival times between various ions and molecules. Different ions have different mobility in air, and the ion sensor enables measurement of ion mobility, from which one can identify the various ions and molecules. The ion mobility sensor which utilizes a pair of glow discharge devices may be designed for coupling with an existing gas chromatograph, where various gas molecules are already separated, but numbers of each kind of molecules are relatively small, and in such cases a conventional ion mobility sensor cannot be utilized.

  5. Mobile Virtual Private Networking

    NASA Astrophysics Data System (ADS)

    Pulkkis, Göran; Grahn, Kaj; Mårtens, Mathias; Mattsson, Jonny

    Mobile Virtual Private Networking (VPN) solutions based on the Internet Security Protocol (IPSec), Transport Layer Security/Secure Socket Layer (SSL/TLS), Secure Shell (SSH), 3G/GPRS cellular networks, Mobile IP, and the presently experimental Host Identity Protocol (HIP) are described, compared and evaluated. Mobile VPN solutions based on HIP are recommended for future networking because of superior processing efficiency and network capacity demand features. Mobile VPN implementation issues associated with the IP protocol versions IPv4 and IPv6 are also evaluated. Mobile VPN implementation experiences are presented and discussed.

  6. Messenger Services on Smartphone: Changing Trends of Communication in Dental Practice.

    PubMed

    Sarode, Gargi S; Sarode, Sachin C; Patil, Shankargouda

    2016-01-01

    A smartphone has become an integral part of human life. It is estimated that there will be 200 million smartphone users in India by the end of 2016 and India will become the second largest smartphone market in the world.(1) Accordingly, Internet use on mobile has also flourished extraordinarily, and by the end of 2017, there will be 314 million Internet users in India.(2). PMID:27340158

  7. Exploring the Planet Mercury: 1.5 Years of MESSENGER Orbital Observations

    NASA Astrophysics Data System (ADS)

    Solomon, Sean C.; Nittler, L. R.; McNutt, R. L., Jr.

    2012-10-01

    Launched in 2004, MESSENGER flew by Mercury three times in 2008-2009 en route to becoming the first spacecraft to orbit the solar system’s innermost planet in March 2011. MESSENGER’s chemical remote sensing measurements of Mercury’s surface indicate that the planet’s bulk silicate fraction, low in Fe and high in Mg, differs from those of the other inner planets. Moreover, surface materials are richer in the moderately volatile constituents S and K than predicted by most current models for inner planet formation. Global image mosaics and targeted high-resolution images reveal that Mercury experienced globally extensive volcanism, with large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile-bearing magmas. Bright deposits within impact craters host fresh-appearing, rimless depressions or hollows, often with high-reflectance interiors and halos and likely formed through processes involving the geologically recent loss of volatiles. The large-scale deformational history of Mercury, although dominated by near-global contractional deformation as first seen by Mariner 10, is more complex than first appreciated, with numerous examples of extensional deformation that accompanied impact crater and basin modification. Mercury’s magnetic field is dominantly dipolar, but the field is axially symmetric and equatorially asymmetric, a geometry that poses challenges to dynamo models for field generation. The interaction between the solar wind and Mercury’s magnetosphere, among the most dynamic in the solar system, serves both to replenish the exosphere and space weather the planet’s surface. Plasma ions of planetary origin are seen throughout the sampled volume of Mercury’s magnetosphere, with maxima in heavy-ion fluxes in the planet’s magnetic-cusp regions. Bursts of energetic electrons, seen at most local times, point to an efficient acceleration mechanism operating

  8. Nitric oxide in guard cells as an important secondary messenger during stomatal closure.

    PubMed

    Gayatri, Gunja; Agurla, Srinivas; Raghavendra, Agepati S

    2013-10-29

    The modulation of guard cell function is the basis of stomatal closure, essential for optimizing water use and CO2 uptake by leaves. Nitric oxide (NO) in guard cells plays a very important role as a secondary messenger during stomatal closure induced by effectors, including hormones. For example, exposure to abscisic acid (ABA) triggers a marked increase in NO of guard cells, well before stomatal closure. In guard cells of multiple species, like Arabidopsis, Vicia and pea, exposure to ABA or methyl jasmonate or even microbial elicitors (e.g., chitosan) induces production of NO as well as reactive oxygen species (ROS). The role of NO in stomatal closure has been confirmed by using NO donors (e.g., SNP) and NO scavengers (like cPTIO) and inhibitors of NOS (L-NAME) or NR (tungstate). Two enzymes: a L-NAME-sensitive, nitric oxide synthase (NOS)-like enzyme and a tungstate-sensitive nitrate reductase (NR), can mediate ABA-induced NO rise in guard cells. However, the existence of true NOS in plant tissues and its role in guard cell NO-production are still a matter of intense debate. Guard cell signal transduction leading to stomatal closure involves the participation of several components, besides NO, such as cytosolic pH, ROS, free Ca(2+), and phospholipids. Use of fluorescent dyes has revealed that the rise in NO of guard cells occurs after the increase in cytoplasmic pH and ROS. The rise in NO causes an elevation in cytosolic free Ca(2+) and promotes the efflux of cations as well as anions from guard cells. Stomatal guard cells have become a model system to study the signaling cascade mechanisms in plants, particularly with NO as a dominant component. The interrelationships and interactions of NO with cytosolic pH, ROS, and free Ca(2+) are quite complex and need further detailed examination. While assessing critically the available literature, the present review projects possible areas of further work related to NO-action in stomatal guard cells.

  9. Venus upper clouds and the UV-absorber from MESSENGER/MASCS observations

    NASA Astrophysics Data System (ADS)

    Perez-Hoyos, Santiago; Sanchez-Lavega, Agustin; Garcia Munoz, Antonio; Irwin, Patrick; Peralta, Javier; Holsclaw, Greg; McClintock, William

    2014-11-01

    In June 2007, the MESSENGER spacecraft performed its second Venus flyby on its route to Mercury. The spacecraft’s MASCS instrument (VIRS channel) acquired numerous spectra of the sunlight reflected from the equatorial region of the planet at wavelengths from the near ultraviolet (300nm) to the near infrared (1450 nm). In this work we present an analysis of the data and their spectral and spatial variability following the mission footprint on the Venus disk. In order to reproduce the observed reflectivity and obtain information on the upper clouds and the unknown UV absorber, we use the NEMESIS retrieval code, including SO2 , CO2 and H2O absorption together with absorption and scattering by mode-1, -2 and -3 cloud particles. This spectral range provides sensitivity to the uppermost cloud levels, above 60 km. Vertical profiles of the mode-1 and mode-2 particles have been retrieved along the equatorial region of Venus, with average retrieved sounding levels of 70 +/- 2 km at 1 micron, in good agreement with previous investigations. This spectral range is also very interesting because of the existence of a mysterious absorber in the blue and UV side of the reflected spectra, whose origin remains as one of the key questions about the Venus atmosphere. Here we report a comparison with some of the previously proposed absorbers: (1) sulfur-related compounds (amorphous and liquid sulfur, S3, S4, S8, S2O); (2) chlorine related species (Cl2, FeCl3); (3) organics (C3O2, Croconic acid). Preliminary results show that the first group provides better fits to the data, although combinations of the proposed agents might be required in order to produce better results. Acknowledgements: This work was supported by the Spanish MICIIN projects AYA2009- 10701, AYA2012-38897-C02-01, and AYA2012-36666 with FEDER support, PRICIT-S2009/ESP-1496, Grupos Gobierno Vasco IT765-13, and UPV/EHU UFI11/55. S.P.-H. acknowledges support from the Jose Castillejo Program funded by Ministerio de Educaci

  10. Nitric oxide in guard cells as an important secondary messenger during stomatal closure

    PubMed Central

    Gayatri, Gunja; Agurla, Srinivas; Raghavendra, Agepati S.

    2013-01-01

    The modulation of guard cell function is the basis of stomatal closure, essential for optimizing water use and CO2 uptake by leaves. Nitric oxide (NO) in guard cells plays a very important role as a secondary messenger during stomatal closure induced by effectors, including hormones. For example, exposure to abscisic acid (ABA) triggers a marked increase in NO of guard cells, well before stomatal closure. In guard cells of multiple species, like Arabidopsis, Vicia and pea, exposure to ABA or methyl jasmonate or even microbial elicitors (e.g., chitosan) induces production of NO as well as reactive oxygen species (ROS). The role of NO in stomatal closure has been confirmed by using NO donors (e.g., SNP) and NO scavengers (like cPTIO) and inhibitors of NOS (L-NAME) or NR (tungstate). Two enzymes: a L-NAME-sensitive, nitric oxide synthase (NOS)-like enzyme and a tungstate-sensitive nitrate reductase (NR), can mediate ABA-induced NO rise in guard cells. However, the existence of true NOS in plant tissues and its role in guard cell NO-production are still a matter of intense debate. Guard cell signal transduction leading to stomatal closure involves the participation of several components, besides NO, such as cytosolic pH, ROS, free Ca2+, and phospholipids. Use of fluorescent dyes has revealed that the rise in NO of guard cells occurs after the increase in cytoplasmic pH and ROS. The rise in NO causes an elevation in cytosolic free Ca2+ and promotes the efflux of cations as well as anions from guard cells. Stomatal guard cells have become a model system to study the signaling cascade mechanisms in plants, particularly with NO as a dominant component. The interrelationships and interactions of NO with cytosolic pH, ROS, and free Ca2+ are quite complex and need further detailed examination. While assessing critically the available literature, the present review projects possible areas of further work related to NO-action in stomatal guard cells. PMID:24194741

  11. Faraday Rotation Fluctuations of MESSENGER radio signals through the Corona during the 2009 Solar Minimum.

    NASA Astrophysics Data System (ADS)

    Wexler, David; Vierinen, Juha; Coster, Anthea; Jensen, Elizabeth A.

    2015-04-01

    Faraday rotation (FR) techniques have been used to probe variations of coronal plasma velocity, density and magnetic field. The plane of polarization for an electromagnetic wave rotates in proportion to the integrated product of parallel magnetic field components and electron density along the radio signal line-of-sight as directed towards the receiving antenna. Fluctuations in FR through the corona thus represent the evolution of these line-integrated plasma parameters, providing a unique measurement of regional corona physics. The MESSENGER spacecraft radio 8 GHz radio beacon, transmitting through the corona at offsets 1.6 to 1.9 solar radii and near-equatorial heliolatitude, was recorded on the Green Bank radio telescope during the solar minimum of 2009. Here we reanalyze at higher temporal resolution the data previously published (Jensen et al 2013, Solar Physics 285:83-95). Combinations of coherent and incoherent integration were used to estimate Stokes parameters, from which the FR phase differences were obtained for serial one-second frames. Results were concatenated and corrected for phase wrap-around to produce a continuous FR phase curve. The general FR phase curve was broad and sweeping, with greatest spectral power observed in periods of hours. Also, finer wave-like fluctuations were noted with periods on the order of 100's of seconds. With the lowest-frequency components removed by detrending techniques, spectral analysis revealed a power spectrum of form P=kνα with spectral index α = -2.25 over frequencies ν = 2-20 milliHertz (mHz), and a flat noise spectrum at higher frequencies. Imposed upon the general power spectrum were trends of enhanced spectral power around 3.5 and 6 mHz, corresponding to approximately 5- and 3-minute period waves. Temporal evolution plots demonstrated that the increased power in these spectral bands appeared intermittently and irregularly. Our results reinforce the findings of prior coronal FR studies, and now extend the

  12. 33 CFR 165.835 - Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL. 165.835 Section 165.835 Navigation and Navigable Waters COAST GUARD... § 165.835 Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL. (a) Definition. As used...

  13. 33 CFR 165.835 - Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL. 165.835 Section 165.835 Navigation and Navigable Waters COAST GUARD... § 165.835 Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL. (a) Definition. As used...

  14. Mercury's Surface-Bounded Exosphere as Seen from Orbit during the MESSENGER Mission: Mercury Atmospheric and Surface Composition Spectrometer Results

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS), on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, conducted orbital observations of Mercury's dayside and nightside exosphere from 29 March 2011 to the end of the mission on 30 April 2015. Over slightly more than four Earth-years, MASCS measured emission profiles versus altitude for calcium (Ca), sodium (Na), and magnesium (Mg) at a daily cadence. These species exhibit different spatial distributions, suggesting distinct source processes. MASCS observed seasonal variations in all three species that are remarkably repeatable from one Mercury year to the next, and did so consistently during the entire 17-Mercury-year duration of the orbital phase of the mission. Whereas MASCS has characterized the seasonal variation, it has provided, at best, only weak evidence for the episodic behavior observed in ground-based studies of Na. Joint analyses of MASCS observations and surface precipitation patterns for energetic particles inferred from observations by the Energetic Particle Spectrometer (EPS) and the Fast Imaging Plasma Spectrometer (FIPS) on MESSENGER have not yielded clear correlations. This lack of correlation may be due in part to the MASCS observational geometries. MASCS has conducted a number of searches for other, weakly emitting species. Hydrogen data from the orbital phase are consistent with profiles observed during MESSENGER's flybys of Mercury. Oxygen detections have proven elusive, and the previously reported observation with a brightness of 4 R may only be an upper limit. Recent analysis of weak species data indicates that manganese (Mn), aluminum (Al), and ionized calcium (Ca+) are present in the exosphere.

  15. Analysis of p60 and p80 tumor necrosis factor-alpha receptor messenger RNA and protein in human placentas.

    PubMed Central

    Yelavarthi, K. K.; Hunt, J. S.

    1993-01-01

    Tumor necrosis factor-alpha (TNF), a pleiotrophic, multifunctional polypeptide factor, has been reported in both normal and infected human placentas. To identify potential targets for this cytokine, the cells in early and late gestation placentas and extraplacental membranes that express the two TNF receptor (TNF-R) genes, p60 and p80, were identified by using in situ hybridization and immunocytochemistry. Gestation-related, cell lineage-specific differences in steady-state levels of p60 and p80 TNF-R messenger RNA were observed. p60 TNF-R messenger RNA predominated at both early and late stages of gestation, being high in both mesenchymal and trophoblastic cell lineages. By contrast, p80 TNF-R messenger RNA was abundant only in intermittent stretches of first trimester syncytiotrophoblast and term placental mesenchymal cells. Overall, intensities of the TNF-R hybridization signals were stronger in term than in first trimester tissues. Transcription of the two TNF-R genes was confirmed by Northern blot hybridization. Translation was verified in all samples by immunohistology using polyclonal antibodies specific for the receptor proteins. p60 and p80 TNF-R proteins were identified both intracellularly and in maternal and fetal blood. Because TNF-Rs exist in both membrane-bound and soluble forms, the results of this study are consistent with the postulate that placental TNF-R have two critical functions: 1) modulation of TNF utilization by specific placental cell lineages during the course of pregnancy; and 2) protection against excessive TNF produced during infections. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:8214007

  16. Compact, Passively Q-Switched Nd:YAG Laser for the MESSENGER Mission to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    Krebs, Danny J.; Novo-Gradac, Anne-Marie; Li, Steven X.; Lindauer, Steven J.; Afzal, Robert S.; Yu, Antony

    2004-01-01

    A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter (MLA) instrument which is an instrument on the MESSENGER mission to the planet Mercury. The laser achieves 5.4 percent efficiency with a near diffraction limited beam. It has passed all space flight environmental tests at system, instrument, and satellite integration. The laser design draws on a heritage of previous laser altimetry missions, specifically ISESAT and Mars Global Surveyor; but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

  17. Cancer-Associated Perturbations in Alternative Pre-messenger RNA Splicing.

    PubMed

    Shkreta, Lulzim; Bell, Brendan; Revil, Timothée; Venables, Julian P; Prinos, Panagiotis; Elela, Sherif Abou; Chabot, Benoit

    2013-01-01

    For most of our 25,000 genes, the removal of introns by pre-messenger RNA (pre-mRNA) splicing represents an essential step toward the production of functional messenger RNAs (mRNAs). Alternative splicing of a single pre-mRNA results in the production of different mRNAs. Although complex organisms use alternative splicing to expand protein function and phenotypic diversity, patterns of alternative splicing are often altered in cancer cells. Alternative splicing contributes to tumorigenesis by producing splice isoforms that can stimulate cell proliferation and cell migration or induce resistance to apoptosis and anticancer agents. Cancer-specific changes in splicing profiles can occur through mutations that are affecting splice sites and splicing control elements, and also by alterations in the expression of proteins that control splicing decisions. Recent progress in global approaches that interrogate splicing diversity should help to obtain specific splicing signatures for cancer types. The development of innovative approaches for annotating and reprogramming splicing events will more fully establish the essential contribution of alternative splicing to the biology of cancer and will hopefully provide novel targets and anticancer strategies. Metazoan genes are usually made up of several exons interrupted by introns. The introns are removed from the pre-mRNA by RNA splicing. In conjunction with other maturation steps, such as capping and polyadenylation, the spliced mRNA is then transported to the cytoplasm to be translated into a functional protein. The basic mechanism of splicing requires accurate recognition of each extremity of each intron by the spliceosome. Introns are identified by the binding of U1 snRNP to the 5' splice site and the U2AF65/U2AF35 complex to the 3' splice site. Following these interactions, other proteins and snRNPs are recruited to generate the complete spliceosomal complex needed to excise the intron. While many introns are constitutively

  18. The first Messenger data supporting main theses of the wave planetology

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    2008-09-01

    The first fundamental statement of the wave planetology [1-6 & others] is about ubiquity of tectonic dichotomy. All celestial bodies move, as it was established by I. Kepler, in non-round but elliptical orbits. This means that they all notwithstanding their sizes, masses, physical states and chemical compositions have alternating increasing and decreasing accelerations producing forces (Newton: F = m·a) warping celestial bodies. This wave warping rotating bodies (but all bodies rotate!) is decomposed into four orthogonal and diagonal directions of standing waves. An interference of these directions gives tectonic blocks of three kinds: uplifting (+), subsiding (-) and neutral (0). The block sizes depend on warping wavelengths. The fundamental wave long 2πR (R - a body radius) is present in all bodies thus making one hemisphere rising and the opposite one falling (more precise relation is 1/3 to 2/3 or 2/3 to 1/3). A geometrical proof of this relation is given in [6] where two famous tectonic dichotomies of Earth and Mars were explained by one wave reason. This ubiquitous phenomenon was described as the first theorem of the wave planetology: "Celestial bodies are dichotomous". There are many examples proving it among planets, satellites and asteroids, even Sun is dichotomous. But up to recent time the studied partially Mercury's surface was not a good example of this phenomenon as not fully visible Caloris basin didn't show its real dimension. Now, after the Messenger flyby we know that it is about 1500 km in diameter, that is about 1/3 of the Mercury's diameter and the rule is not violated. The third theorem of the wave planetary tectonics states: "Celestial bodies are granular". This means that celestial bodies are warped by individual waves lengths of which are inversely proportional to their orbital frequencies: higher frequency - finer granules, lower frequency - larger granules (Fig. 1). Observations fully support it not only in sense of granules diameters

  19. ACTS mobile SATCOM experiments

    NASA Technical Reports Server (NTRS)

    Abbe, Brian S.; Frye, Robert E.; Jedrey, Thomas C.

    1993-01-01

    Over the last decade, the demand for reliable mobile satellite communications (satcom) for voice, data, and video applications has increased dramatically. As consumer demand grows, the current spectrum allocation at L-band could become saturated. For this reason, NASA and the Jet Propulsion Laboratory are developing the Advanced Communications Technology Satellites (ACTS) mobile terminal (AMT) and are evaluating the feasibility of K/Ka-band (20/30 GHz) mobile satcom to meet these growing needs. U.S. industry and government, acting as co-partners, will evaluate K/Ka-band mobile satcom and develop new technologies by conducting a series of applications-oriented experiments. The ACTS and the AMT testbed will be used to conduct these mobile satcom experiments. The goals of the ACTS Mobile Experiments Program and the individual experiment configurations and objectives are further presented.

  20. Mobile learning in medicine

    NASA Astrophysics Data System (ADS)

    Serkan Güllüoüǧlu, Sabri

    2013-03-01

    This paper outlines the main infrastructure for implicating mobile learning in medicine and present a sample mobile learning application for medical learning within the framework of mobile learning systems. Mobile technology is developing nowadays. In this case it will be useful to develop different learning environments using these innovations in internet based distance education. M-learning makes the most of being on location, providing immediate access, being connected, and acknowledges learning that occurs beyond formal learning settings, in places such as the workplace, home, and outdoors. Central to m-learning is the principle that it is the learner who is mobile rather than the device used to deliver m learning. The integration of mobile technologies into training has made learning more accessible and portable. Mobile technologies make it possible for a learner to have access to a computer and subsequently learning material and activities; at any time and in any place. Mobile devices can include: mobile phone, personal digital assistants (PDAs), personal digital media players (eg iPods, MP3 players), portable digital media players, portable digital multimedia players. Mobile learning (m-learning) is particularly important in medical education, and the major users of mobile devices are in the field of medicine. The contexts and environment in which learning occurs necessitates m-learning. Medical students are placed in hospital/clinical settings very early in training and require access to course information and to record and reflect on their experiences while on the move. As a result of this paper, this paper strives to compare and contrast mobile learning with normal learning in medicine from various perspectives and give insights and advises into the essential characteristics of both for sustaining medical education.

  1. Exploring the mobility of mobile phone users

    NASA Astrophysics Data System (ADS)

    Csáji, Balázs Cs.; Browet, Arnaud; Traag, V. A.; Delvenne, Jean-Charles; Huens, Etienne; Van Dooren, Paul; Smoreda, Zbigniew; Blondel, Vincent D.

    2013-03-01

    Mobile phone datasets allow for the analysis of human behavior on an unprecedented scale. The social network, temporal dynamics and mobile behavior of mobile phone users have often been analyzed independently from each other using mobile phone datasets. In this article, we explore the connections between various features of human behavior extracted from a large mobile phone dataset. Our observations are based on the analysis of communication data of 100,000 anonymized and randomly chosen individuals in a dataset of communications in Portugal. We show that clustering and principal component analysis allow for a significant dimension reduction with limited loss of information. The most important features are related to geographical location. In particular, we observe that most people spend most of their time at only a few locations. With the help of clustering methods, we then robustly identify home and office locations and compare the results with official census data. Finally, we analyze the geographic spread of users’ frequent locations and show that commuting distances can be reasonably well explained by a gravity model.

  2. Temperature of Mercury's plasma electron environment: limits from the first MESSENGER flyby

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph L., Jr.; Zurbuchen, Thomas H.; Raines, Jim M.; Gloeckler, George; Krimigis, Stamatios M.; Anderson, Brian J.; Slavin, James A.; Koehn, Patrick L.; Killen, Rosemary M.; Solomon, Sean C.

    2008-09-01

    Introduction The Fast Imaging Plasma Spectrometer (FIPS) component of the Energetic Particle and Plasma Spectrometer (EPPS) [1] on the MESSENGER spacecraft has provided evidence of a multi-species magnetospheric plasma at Mercury [2]. In addition, relatively low values of mass-per-charge in the compositional spectrogram are indicative of multiple ionizations of some species, in turn, a feature diagnostic of relatively high electron temperatures. While there is no means of directly assessing how closely the conditions of local thermodynamic equilibrium (LTE) apply, testing this assumption for consistency with the measured data can potentially help advance our understanding of both the composition and temperature of this plasma. Poor particle statistics (low counting rates) necessitated the summing of data over the entire magnetospheric pass to provide a statistically significant mass-per-charge spectrum. Hence, we make the ab initio assumption that time-aliasing is not an issue, i.e., the ionic composition of the magnetosphere is approximately constant along the spacecraft trajectory. Such multicomponent plasmas, with multiply charged but kinetically cold ions, are well known in Jupiter's magnetosphere, with their compositional origins at Io and their (multiple) charge states resulting from the electrons in the hot, Io plasma torus [3,4,5]. Observations FIPS provides both energy-per-charge and velocity measurements, allowing for the mass per charge of detected components to be determined. Within Mercury's magnetosphere, ions in the mass/charge range 1-56 amu/e were detected with a time resolution of 8 s and within an energy range 0.1-13.5 keV/e. An overview of the data and compositional inferences from the signals corresponding to singly ionized species have already been discussed [2]. The multiply charged ions (mass-per-charge ~12 amu/e and less) are likely the result of impact ionization by hot electrons in the magnetosphere, most likely from the plasma sheet

  3. Affleck-Dine baryogenesis, condensate fragmentation and gravitino dark matter in gauge-mediation with a large messenger mass

    SciTech Connect

    Doddato, Francesca; McDonald, John E-mail: j.mcdonald@lancaster.ac.uk

    2011-06-01

    We study the conditions for successful Affleck-Dine baryogenesis and the origin of gravitino dark matter in GMSB models. AD baryogenesis in GMSB models is ruled out by neutron star stability unless Q-balls are unstable and decay before nucleosynthesis. Unstable Q-balls can form if the messenger mass scale is larger than the flat-direction field Φ when the condensate fragments. We provide an example based on AD baryogenesis along a d = 6 flat direction for the case where m{sub 3/2} ≈ 2GeV, as predicted by gravitino dark matter from Q-ball decay. Using a phenomenological GMSB potential which models the Φ dependence of the SUSY breaking terms, we numerically solve for the evolution of Φ and show that the messenger mass can be sufficiently close to the flat-direction field when the condensate fragments. We compute the corresponding reheating temperature and the baryonic charge of the condensate fragments and show that the charge is large enough to produce late-decaying Q-balls which can be the origin of gravitino dark matter.

  4. MESSENGER's special delivery: Comets 2P/Encke and C/2012 S1 (ISON) at small heliocentric distances

    NASA Astrophysics Data System (ADS)

    Fernandez, Yanga R.; Vervack, Ronald J., Jr.; Knight, Matthew M.; McCandliss, Stephan R.; Dello Russo, Neil; Feldman, Paul D.; Lisse, Casey M.; Tamblyn, Peter

    2016-10-01

    Observations of comets when they are close to the Sun can potentially reveal interesting aspects of their behavior thanks to the rapid change of both seasons on the nucleus and the local insolation environment. However this is typically the most difficult time to make observations from Earth because the solar elongation is small, so studies of comets that are near the Sun generally require special facilities. In autumn 2013, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft observed comets 2P/Encke and C/2012 S1 (ISON) from its orbital perch around Mercury when both comets were poorly located for most Earth-based telescopes. The observations included visible-wavelength, multi-filter imaging as well as ultraviolet spectroscopy. Both comets were observed down to about 0.3 AU from the Sun; in Encke's case it was followed through perihelion, which has rarely been done before. The data provide us with a look at the behavior of the dust and gas (e.g., OH, CO, OI, CI, SI, HI) production rates over several weeks, and we can investigate how the rates change with time, rotational phase, and heliocentric distance. In this poster we will present preliminary analyses of the time-series photometry and spectroscopy of these MESSENGER-observed comets, and place their behaviors into context.

  5. Subsurface carbon-bearing material on Mercury revealed by the MESSENGER Gamma-Ray and Neutron Spectrometer

    NASA Astrophysics Data System (ADS)

    Peplowski, P. N.; Klima, R. L.; Lawrence, D. J.; Ernst, C. M.; Denevi, B. W.; Goldsten, J. O.; Murchie, S. L.; Nittler, L. R.; Solomon, S. C.

    2015-12-01

    Mercury's surface is markedly darker than is predicted from its major element composition. The major spectral unit lowest in reflectance, known as low-reflectance material (LRM), is typically seen in material excavated by impact craters. This observation has been taken as evidence that Mercury's darkening phase is endogenous. The MESSENGER Gamma-Ray and Neutron Spectrometer (GRNS) acquired spatially resolved measurements of three distinct LRM deposits during the low-altitude campaign that was conducted near the end of MESSENGER's orbital mission. The GRNS data reveal increases in thermal neutron count rates that are spatially correlated with the LRM deposits. The only element consistent with the neutron measurements and with the spectral reflectance of LRM at visible to near-infrared wavelengths is graphitic carbon, at an abundance that is 1-3 wt% higher than in surrounding non-LRM material. We infer that C is the primary darkening agent on Mercury, and that the LRM sampled C-bearing material within the crust. This interpretation supports the hypothesis that a graphite floatation crust formed on Mercury from an early global magma ocean, and we propose that its impact-gardened remains persist beneath the volcanic plains units that comprise the planet's present upper crust. The distribution of LRM on Mercury's surface requires numerous, discontinuous LRM source regions, as would be expected for the remains of the primordial crust given the disruptive effects of the late heavy bombardment and eons of intrusive magmatism.

  6. Germination Potential of Dormant and Nondormant Arabidopsis Seeds Is Driven by Distinct Recruitment of Messenger RNAs to Polysomes.

    PubMed

    Basbouss-Serhal, Isabelle; Soubigou-Taconnat, Ludivine; Bailly, Christophe; Leymarie, Juliette

    2015-07-01

    Dormancy is a complex evolutionary trait that temporally prevents seed germination, thus allowing seedling growth at a favorable season. High-throughput analyses of transcriptomes have led to significant progress in understanding the molecular regulation of this process, but the role of posttranscriptional mechanisms has received little attention. In this work, we have studied the dynamics of messenger RNA association with polysomes and compared the transcriptome with the translatome in dormant and nondormant seeds of Arabidopsis (Arabidopsis thaliana) during their imbibition at 25 °C in darkness, a temperature preventing germination of dormant seeds only. DNA microarray analysis revealed that 4,670 and 7,028 transcripts were differentially abundant in dormant and nondormant seeds in the transcriptome and the translatome, respectively. We show that there is no correlation between transcriptome and translatome and that germination regulation is also largely translational, implying a selective and dynamic recruitment of messenger RNAs to polysomes in both dormant and nondormant seeds. The study of 5' untranslated region features revealed that GC content and the number of upstream open reading frames could play a role in selective translation occurring during germination. Gene Ontology clustering showed that the functions of polysome-associated transcripts differed between dormant and nondormant seeds and revealed actors in seed dormancy and germination. In conclusion, our results demonstrate the essential role of selective polysome loading in this biological process.

  7. Germination Potential of Dormant and Nondormant Arabidopsis Seeds Is Driven by Distinct Recruitment of Messenger RNAs to Polysomes

    PubMed Central

    Basbouss-Serhal, Isabelle; Soubigou-Taconnat, Ludivine; Bailly, Christophe; Leymarie, Juliette

    2015-01-01

    Dormancy is a complex evolutionary trait that temporally prevents seed germination, thus allowing seedling growth at a favorable season. High-throughput analyses of transcriptomes have led to significant progress in understanding the molecular regulation of this process, but the role of posttranscriptional mechanisms has received little attention. In this work, we have studied the dynamics of messenger RNA association with polysomes and compared the transcriptome with the translatome in dormant and nondormant seeds of Arabidopsis (Arabidopsis thaliana) during their imbibition at 25°C in darkness, a temperature preventing germination of dormant seeds only. DNA microarray analysis revealed that 4,670 and 7,028 transcripts were differentially abundant in dormant and nondormant seeds in the transcriptome and the translatome, respectively. We show that there is no correlation between transcriptome and translatome and that germination regulation is also largely translational, implying a selective and dynamic recruitment of messenger RNAs to polysomes in both dormant and nondormant seeds. The study of 5′ untranslated region features revealed that GC content and the number of upstream open reading frames could play a role in selective translation occurring during germination. Gene Ontology clustering showed that the functions of polysome-associated transcripts differed between dormant and nondormant seeds and revealed actors in seed dormancy and germination. In conclusion, our results demonstrate the essential role of selective polysome loading in this biological process. PMID:26019300

  8. Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Dewey, Ryan M.; Lawrence, David J.; Goldsten, John O.; Peplowski, Patrick N.; Korth, Haje; Slavin, James A.; Krimigis, Stamatios M.; Anderson, Brian J.; Ho, George C.; McNutt, Ralph L.; Raines, Jim M.; Schriver, David; Solomon, Sean C.

    2016-03-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer, as well as data arising from energetic electrons recorded by the X-Ray Spectrometer and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary nightside. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and prenoon sectors, at times executing multiple complete drifts around the planet to form "quasi-trapped" populations.

  9. Energetic-electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.

    2016-04-01

    The MESSENGER mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer (EPS), as well as data arising from energetic electrons recorded by the X-Ray Spectrometer (XRS) and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary night side. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and pre-noon sectors, at time executing multiple complete drifts around the planet to form "quasi-trapped" populations.

  10. Observations of Kelvin-Helmholtz Waves Along the Dusk-Side Boundary of Mercury's Magnetosphere During MESSENGER's Third Flyby

    NASA Technical Reports Server (NTRS)

    Boardsen, Scott A.; Sundberg, Torgjoern; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Solomon, Sean C.; Blomberg, Lars G.

    2010-01-01

    During the third MESSENGER flyby of Mercury on 29 September 2009, 15 crossings of the dusk-side magnetopause were observed in the magnetic field data over a 2-min period, during which the spacecraft traveled a distance of 0.2 R(sub M) (where R(sub M) is Mercury's radius). The quasi-periodic nature of the magnetic field variations during the crossings, the characteristic time separations of approx.16 s between pairs of crossings, and the variations of the magnetopause normal directions indicate that the signals are likely the signature of surface waves highly steepened at their leading edge that arose from the Kelvin-Helmholtz instability. At Earth, the Kelvin- Helmholtz instability is believed to lead to the turbulent transport of solar wind plasma into Earth's plasma sheet. This solar wind entry mechanism could also be important at Mercury. Citation: Boardsen, S. A., T. Sundberg, J. A.Slavin, B. J. Anderson, H. Korth, S. C. Solomon, and L. G. Blomberg (2010), Observations of Kelvin-Helmholtz waves along the dusk-side boundary of Mercury s magnetosphere during MESSENGER's third flyby,

  11. Structural Analysis of the Victoria Quadrangle (H2) of Mercury based on NASA MESSENGER Data

    NASA Astrophysics Data System (ADS)

    Galluzzi, Valentina

    2015-04-01

    Objective of this thesis is the mapping and structural analysis of the H2 quadrangle, “Victoria”, and a reconnaissance study of the geometry and kinematics of lobate scarps on Mercury. To this end, I produced a 1:3,000,000 geologic map of the area using the images provided by the NASA spacecraft MESSENGER, which has been orbiting the planet since March, 2011. The geologic map shows the distribution of smooth plains, intermediate plains, intercrater plains units and a classification of crater materials based on an empirical distinction among three stages of degradation. Structural mapping shows that the H2 quadrangle is dominated by N-S faults (here grouped into the Victoria system) to the east and NE-SW faults (Larrocha system) to the west, with the secondary existence of NW-SE-trending faults (Carnegie system) in the north-western area of the quadrangle. A systematic analysis of these systems has led to the following results. 1) The Victoria system is characterized by a main array of faults located along Victoria Rupes - Endeavour Rupes - Antoniadi Dorsum. The segmentation of this array into three different sectors changes from north to south and is spatially linked to the presence of three volcanic vents located at the boundaries between each sector and at the northern end of the Victoria Rupes sector, suggesting that volcanism and faulting are interrelated. 2) The main array of Carnegie system is kinematically linked and antithetical to the Victoria system. Both systems have arguably controlled the growth of a longitudinal, fault-free, crustal and gravimetric bulge in the central area of the Victoria quadrangle, which is interpreted as a regional contractional pop-up. 3) The Larrocha system is interrupted against the central bulge and thus is probably older than the Victoria and Carnegie systems. Buffered crater counting performed on the Victoria system confirms the young relative age of its fault segments with respect to the map units. The faults of the

  12. Mercury: a prediction for bulk chemical composition and internal structure in readiness for new MESSENGER data

    NASA Astrophysics Data System (ADS)

    Prentice, A. J.

    2008-12-01

    The MESSENGER spacecraft has confirmed that Mercury's magnetic field is dominantly dipolar and due to an active dynamo in a molten outer core (Solomon et al, 2008 Science 321 59). An energy source is needed to maintain this dynamo. Either liquid iron is freezing at the surface of an inner solid core (as proposed here) or solid iron is precipitating within an outer sulphur-rich core (Chen et al, 2008 GRL 35 L07201). If the outer core does not contain sulphur and consists solely of pure metal (Fe, Ni, Cr,..), then an active dynamo is inconsistent with previous numerical models for the radiogenic thermal evolution of the planet. Those earlier models found that the present temperature at the core/mantle boundary (CMB) is ~ 500 K below the melting temperature of metal ~ 2030 K for a CMB pressure of 70 kbar. The earlier calculations were based on low lunar abundances of U and Th. Here I present a new model for the bulk chemical composition, thermal evolution and current internal structure of Mercury. The model is based on the modern Laplacian theory of solar system origin (Prentice, 1978 Moon Planets 19 341; 2001 Earth Moon & Planets 87 11; 2006 Publ. Astron. Soc. Aust. (PASA) 23 1; 2008 - URL below). A key feature of this theory is that the planets formed from a concentric system of gas rings (n = 0, 1, 2,..) that were shed by the contracting protosolar cloud. The temperatures Tn of the rings scale with mean orbital radius Rn closely as Tn ~ Rn-0.9. Mercury plays a crucial role in calibrating this relationship because of a condensation process of metal/silicate fractionation (Lewis, 1972 EPSL 15 286). Choosing Tn ~ 1630 K for mean orbit gas ring pressure of 0.17 bar, the condensate consists mostly of Fe-Ni-Cr (mass fraction 0.671), gehlenite (0.190) and Mg-silicates (0.081). It has mean density 5.30 g/cm3. Na, K and S are absent. The mass fractions of U and Th, namely 5.66 × 10-8 & 2.08 × 10-7, are a factor of 4.3 times greater than those of the proto-Earth condensate

  13. Mobility control agent

    SciTech Connect

    Argabright, P.A.; Phillips, B.L.; Rhudy, J.S.

    1983-05-17

    Polymer mobility control agents useful in supplemental oil recovery processes, which give improved reciprocal relative mobilities, are prepared by initiating the polymerization of a monomer containing a vinyl group with a catalyst comprising a persulfate and ferrous ammonium sulfate. The vinyl monomer is an acrylyl, a vinyl cyanide, a styryl and water soluble salts thereof.

  14. Mobile Apps for Librarians

    ERIC Educational Resources Information Center

    Power, June L.

    2013-01-01

    In an increasing mobile environment, library and reading-related activities often take place on a phone or tablet device. Not only does this mean that library Web sites must keep mobile navigability in mind, but also develop and utilize apps that allow patrons to interact with information and with libraries. While apps do not serve every purpose,…

  15. Mobile Learning Anytime, Anywhere

    ERIC Educational Resources Information Center

    Hlodan, Oksana

    2010-01-01

    Some educational institutions are taking the leap to mobile learning (m-learning) by giving out free iPods. For example, Abilene Christian University gave iPods or iPhones to freshman students and developed 15 Web applications specifically for the mobile devices. The iPod is not the only ubiquitous m-learning device. Any technology that connects…

  16. Mastering Mobile Security

    ERIC Educational Resources Information Center

    Panettieri, Joseph C.

    2007-01-01

    Without proper security, mobile devices are easy targets for worms, viruses, and so-called robot ("bot") networks. Hackers increasingly use bot networks to launch massive attacks against eCommerce websites--potentially targeting one's online tuition payment or fundraising/financial development systems. How can one defend his mobile systems against…

  17. Mobility and Reading Achievement.

    ERIC Educational Resources Information Center

    Waters, Theresa Z.

    A study examined the effect of geographic mobility on elementary school students' achievement. Although such mobility, which requires students to make multiple moves among schools, can have a negative impact on academic achievement, the hypothesis for the study was that it was not a determining factor in reading achievement test scores. Subjects…

  18. Mobile Goes Mainstream

    ERIC Educational Resources Information Center

    Eisele-Dyrli, Kurt

    2011-01-01

    Mobile learning--the use of mobile devices for educational purposes by students--is rapidly moving from an experimental initiative by a few innovative districts over the last five years to a broadly accepted concept in K12. The latest research and surveys, results of pilot programs, and analysis of trends in both public education and the broader…

  19. [Cognition and mobility].

    PubMed

    Bridenbaugh, Stephanie A

    2015-04-01

    Felix Platter Hospital, University Center for Medicine of Aging, Basel, Switzerland; There is a strong association between cognition and mobility. Older adults with gait deficits have an increased risk of developing cognitive deficits, even dementia. Cognitive deficits, on the other hand, are associated with worsening gait. Cognitive as well as mobility deficits are associated with an increased fall risk. Assessments of cognition, particularly the executive functions, and functional mobility should therefore be an integral part of every comprehensive geriatric assessment. Some quick screening tests for mobility disorders can be performed in a clinical praxis. If those assessments provide pathological results, then consider patient referral for an in-depth gait analysis. Gait analyses that utilize dual task paradigms (walking and simultaneously performing a second task) are particularly meaningful for early detection of mobility and cognitive deficits. Early detection permits timely implementation of targeted interventions to improve gait and brain function. PMID:25791044

  20. Skylab mobile laboratory

    NASA Technical Reports Server (NTRS)

    Primeaux, G. R.; Larue, M. A.

    1975-01-01

    The Skylab mobile laboratory was designed to provide the capability to obtain necessary data on the Skylab crewmen 30 days before lift-off, within 1 hour after recovery, and until preflight physiological baselines were reattained. The mobile laboratory complex consisted of six laboratories that supported cardiovascular, metabolic, nutrition and endocrinology, operational medicine, blood, and microbiology experiments; a utility package; and two shipping containers. The objectives and equipment requirements of the Skylab mobile laboratory and the data acquisition systems are discussed along with processes such as permanently mounting equipment in the individual laboratories and methods of testing and transporting the units. The operational performance, in terms of amounts of data collected, and the concept of mobile laboratories for medical and scientific experiments are evaluated. The Skylab mobile laboratory succeeded in facilitating the data collection and sample preservation associated with the three Skylab manned flights.

  1. Gone Mobile? (Mobile Libraries Survey 2010)

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2010-01-01

    Librarians, like patrons and researchers, are caught between traditional library service models and the promise of evolving information technologies. In recent years, professional conferences have strategically featured programs and presentations geared toward building a mobile agenda and adapting or adopting services to meet new demands of mobile…

  2. Fecal bile acid excretion and messenger RNA expression levels of ileal transporters in high risk gallstone patients

    PubMed Central

    2009-01-01

    Background Cholesterol gallstone disease (GS) is highly prevalent among Hispanics and American Indians. In GS, the pool of bile acids (BA) is decreased, suggesting that BA absorption is impaired. In Caucasian GS patients, mRNA levels for ileal BA transporters are decreased. We aimed to determine fecal BA excretion rates, mRNA levels for ileal BA transporter genes and of regulatory genes of BA synthesis in Hispanic GS patients. Results Excretion of fecal BA was measured in seven GS females and in ten GS-free individuals, all with a body mass index < 29. Participants ingested the stool marker Cr2O3 (300 mg/day) for 10 days, and fecal specimens were collected on the last 3 days. Chromium was measured by a colorimetric method, and BA was quantitated by gas chromatography/mass spectroscopy. Intake of calories, nutrients, fiber and cholesterol were similar in the GS and GS-free subjects. Mean BA excretion levels were 520 ± 80 mg/day for the GS-free group, and 461 ± 105 mg/day for the GS group. Messenger RNA expression levels were determined by RT-PCR on biopsy samples obtained from ileum during diagnostic colonoscopy (14 GS-free controls and 16 GS patients) and from liver during surgery performed at 8 and 10 AM (12 GS and 10 GS-free patients operated on for gastrointestinal malignancies), all with a body mass index < 29. Messenger RNA level of the BA transporter genes for ileal lipid binding protein, multidrug resistance-associated protein 3, organic solute transporter alpha, and organic solute transporter beta were similar in GS and GS-free subjects. Messenger RNA level of Cyp27A1, encoding the enzyme 27α-hydroxylase, the short heterodimer partner and farnesoid X receptor remained unchanged, whereas the mRNA level of Cyp7A1, the rate limiting step of BA synthesis, was increased more than 400% (p < 0.01) in the liver of GS compared to GS-free subjects. Conclusion Hispanics with GS have fecal BA excretion rates and mRNA levels of genes for ileal BA transporters that

  3. Limits of social mobilization.

    PubMed

    Rutherford, Alex; Cebrian, Manuel; Dsouza, Sohan; Moro, Esteban; Pentland, Alex; Rahwan, Iyad

    2013-04-16

    The Internet and social media have enabled the mobilization of large crowds to achieve time-critical feats, ranging from mapping crises in real time, to organizing mass rallies, to conducting search-and-rescue operations over large geographies. Despite significant success, selection bias may lead to inflated expectations of the efficacy of social mobilization for these tasks. What are the limits of social mobilization, and how reliable is it in operating at these limits? We build on recent results on the spatiotemporal structure of social and information networks to elucidate the constraints they pose on social mobilization. We use the DARPA Network Challenge as our working scenario, in which social media were used to locate 10 balloons across the United States. We conduct high-resolution simulations for referral-based crowdsourcing and obtain a statistical characterization of the population recruited, geography covered, and time to completion. Our results demonstrate that the outcome is plausible without the presence of mass media but lies at the limit of what time-critical social mobilization can achieve. Success relies critically on highly connected individuals willing to mobilize people in distant locations, overcoming the local trapping of diffusion in highly dense areas. However, even under these highly favorable conditions, the risk of unsuccessful search remains significant. These findings have implications for the design of better incentive schemes for social mobilization. They also call for caution in estimating the reliability of this capability. PMID:23576719

  4. Limits of social mobilization.

    PubMed

    Rutherford, Alex; Cebrian, Manuel; Dsouza, Sohan; Moro, Esteban; Pentland, Alex; Rahwan, Iyad

    2013-04-16

    The Internet and social media have enabled the mobilization of large crowds to achieve time-critical feats, ranging from mapping crises in real time, to organizing mass rallies, to conducting search-and-rescue operations over large geographies. Despite significant success, selection bias may lead to inflated expectations of the efficacy of social mobilization for these tasks. What are the limits of social mobilization, and how reliable is it in operating at these limits? We build on recent results on the spatiotemporal structure of social and information networks to elucidate the constraints they pose on social mobilization. We use the DARPA Network Challenge as our working scenario, in which social media were used to locate 10 balloons across the United States. We conduct high-resolution simulations for referral-based crowdsourcing and obtain a statistical characterization of the population recruited, geography covered, and time to completion. Our results demonstrate that the outcome is plausible without the presence of mass media but lies at the limit of what time-critical social mobilization can achieve. Success relies critically on highly connected individuals willing to mobilize people in distant locations, overcoming the local trapping of diffusion in highly dense areas. However, even under these highly favorable conditions, the risk of unsuccessful search remains significant. These findings have implications for the design of better incentive schemes for social mobilization. They also call for caution in estimating the reliability of this capability.

  5. Mobile sensing systems.

    PubMed

    Macias, Elsa; Suarez, Alvaro; Lloret, Jaime

    2013-12-16

    Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular… Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high.

  6. Mobile Sensing Systems

    PubMed Central

    Macias, Elsa; Suarez, Alvaro; Lloret, Jaime

    2013-01-01

    Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular… Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high. PMID:24351637

  7. Limits of social mobilization

    PubMed Central

    Rutherford, Alex; Cebrian, Manuel; Dsouza, Sohan; Moro, Esteban; Pentland, Alex; Rahwan, Iyad

    2013-01-01

    The Internet and social media have enabled the mobilization of large crowds to achieve time-critical feats, ranging from mapping crises in real time, to organizing mass rallies, to conducting search-and-rescue operations over large geographies. Despite significant success, selection bias may lead to inflated expectations of the efficacy of social mobilization for these tasks. What are the limits of social mobilization, and how reliable is it in operating at these limits? We build on recent results on the spatiotemporal structure of social and information networks to elucidate the constraints they pose on social mobilization. We use the DARPA Network Challenge as our working scenario, in which social media were used to locate 10 balloons across the United States. We conduct high-resolution simulations for referral-based crowdsourcing and obtain a statistical characterization of the population recruited, geography covered, and time to completion. Our results demonstrate that the outcome is plausible without the presence of mass media but lies at the limit of what time-critical social mobilization can achieve. Success relies critically on highly connected individuals willing to mobilize people in distant locations, overcoming the local trapping of diffusion in highly dense areas. However, even under these highly favorable conditions, the risk of unsuccessful search remains significant. These findings have implications for the design of better incentive schemes for social mobilization. They also call for caution in estimating the reliability of this capability. PMID:23576719

  8. Mobile sensing systems.

    PubMed

    Macias, Elsa; Suarez, Alvaro; Lloret, Jaime

    2013-01-01

    Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular… Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high. PMID:24351637

  9. Displays enabling mobile multimedia

    NASA Astrophysics Data System (ADS)

    Kimmel, Jyrki

    2007-02-01

    With the rapid advances in telecommunications networks, mobile multimedia delivery to handsets is now a reality. While a truly immersive multimedia experience is still far ahead in the mobile world, significant advances have been made in the constituent audio-visual technologies to make this become possible. One of the critical components in multimedia delivery is the mobile handset display. While such alternatives as headset-style near-to-eye displays, autostereoscopic displays, mini-projectors, and roll-out flexible displays can deliver either a larger virtual screen size than the pocketable dimensions of the mobile device can offer, or an added degree of immersion by adding the illusion of the third dimension in the viewing experience, there are still challenges in the full deployment of such displays in real-life mobile communication terminals. Meanwhile, direct-view display technologies have developed steadily, and can provide a development platform for an even better viewing experience for multimedia in the near future. The paper presents an overview of the mobile display technology space with an emphasis on the advances and potential in developing direct-view displays further to meet the goal of enabling multimedia in the mobile domain.

  10. Mobile sociology. 2000.

    PubMed

    Urry, John

    2010-01-01

    This article seeks to develop a manifesto for a sociology concerned with the diverse mobilities of peoples, objects, images, information, and wastes; and of the complex interdependencies between, and social consequences of, such diverse mobilities. A number of key concepts relevant for such a sociology are elaborated: 'gamekeeping', networks, fluids, scapes, flows, complexity and iteration. The article concludes by suggesting that a 'global civil society' might constitute the social base of a sociology of mobilities as we move into the twenty-first century.

  11. Cantico Delle Creature: A microtonal original composition for soprano and string quartet to a text by St. Francis of Assisi, including analytical commentary

    NASA Astrophysics Data System (ADS)

    Sabol, Jason A.

    Cantico delle Creature is an original piece of music for soprano and string quartet composed in 72 tone per octave equal temperament, dividing each semitone into six equal parts called twelfth-tones. This system of tuning makes it possible to combine just intonation and spectral principles based on the harmonic series with real imitation, modulation, and polyphony. Supplemental text discusses several aspects of microtonal structure and pedagogy, including the representation of the first 64 partials of the harmonic series in 72 tone equal temperament, performance of natural string harmonics, the relationship between interval size and vibration ratio, pitch to frequency conversion, and analysis of several passages in the musical score.

  12. In vitro transcription and translational efficiency of chimeric SP6 messenger RNAs devoid of 5' vector nucleotides.

    PubMed Central

    Jobling, S A; Cuthbert, C M; Rogers, S G; Fraley, R T; Gehrke, L

    1988-01-01

    A plasmid containing the bacteriophage SP6 promoter, designated pHSTO, permits in vitro transcription of RNAs devoid of vector-derived nucleotides. This vector has been characterized for relative transcriptional activity using constructs which alter the conserved nucleotides extending beyond the SP6 transcriptional initiation site. SP6 polymerase efficiently transcribes cDNA inserts which contain a guanosine (G) nucleotide at position +1 relative to the SP6 promoter; however, inserts with an adenosine (A) or pyrimidine at position +1 are not transcribed. Several cellular and viral cDNAs have been transcribed into translatable messenger RNA using this vector; however, SP6 polymerase will not transcribe the A-T rich untranslated leader from alfalfa mosaic virus RNA 4 efficiently unless the viral mRNA cap site is separated from the transcriptional initiation site by twelve base pairs of vector DNA. Chimeric messenger RNAs were created by linking the untranslated leader sequence of several viral mRNAs to the coding region of barley alpha-amylase, and the resultant mRNAs were translated in a wheat germ extract to determine relative translational efficiencies. The untranslated leader sequences of turnip yellow mosaic virus coat protein mRNA and black beetle virus RNA 2 did not increase translational efficiency, while the tobacco mosaic virus leader stimulated translation significantly. The results indicate that substitution of a cognate untranslated leader sequence with a leader derived from a highly efficient mRNA does not necessarily predict enhanced translational efficiency of the chimeric mRNA. Images PMID:3260027

  13. Role of a neuronal small non-messenger RNA: behavioural alterations in BC1 RNA-deleted mice.

    PubMed

    Lewejohann, L; Skryabin, B V; Sachser, N; Prehn, C; Heiduschka, P; Thanos, S; Jordan, U; Dell'Omo, G; Vyssotski, A L; Pleskacheva, M G; Lipp, H-P; Tiedge, H; Brosius, J; Prior, H

    2004-09-23

    BC1 RNA is a small non-messenger RNA common in dendritic microdomains of neurons in rodents. In order to investigate its possible role in learning and behaviour, we compared controls and knockout mice from three independent founder lines established from separate embryonic stem cells. Mutant mice were healthy with normal brain morphology and appeared to have no neurological deficits. A series of tests for exploration and spatial memory was carried out in three different laboratories. The tests were chosen as to ensure that different aspects of spatial memory and exploration could be separated and that possible effects of confounding variables could be minimised. Exploration was studied in a barrier test, in an open-field test, and in an elevated plus-maze test. Spatial memory was investigated in a Barnes maze and in a Morris water maze (memory for a single location), in a multiple T-maze and in a complex alley maze (route learning), and in a radial maze (working memory). In addition to these laboratory tasks, exploratory behaviour and spatial memory were assessed under semi-naturalistic conditions in a large outdoor pen. The combined results indicate that BC1 RNA-deficient animals show behavioural changes best interpreted in terms of reduced exploration and increased anxiety. In contrast, spatial memory was not affected. In the outdoor pen, the survival rates of BC1-depleted mice were lower than in controls. Thus, we conclude that the neuron-specific non-messenger BC1 RNA contributes to the aptive modulation of behaviour.

  14. Carbon monoxide: a critical quantitative analysis and review of the extent and limitations of its second messenger function

    PubMed Central

    Levitt, David G; Levitt, Michael D

    2015-01-01

    Endogenously produced carbon monoxide (CO) is commonly believed to be a ubiquitous second messenger involved in a wide range of physiological and pathological responses. The major evidence supporting this concept is that CO is produced endogenously via heme oxygenase-catalyzed breakdown of heme and that experimental exposure to CO alters tissue function. However, it remains to be conclusively demonstrated that there are specific receptors for CO and that endogenous CO production is sufficient to alter tissue function. Unlike other signaling molecules, CO is not significantly metabolized, and it is removed from cells solely via rapid diffusion into blood, which serves as a near infinite sink. This non-metabolizable nature of CO renders the physiology of this gas uniquely susceptible to quantitative modeling. This review analyzes each of the steps involved in CO signaling: 1) the background CO partial pressure (PCO) and the blood and tissue CO binding; 2) the affinity of the putative CO receptors; 3) the rate of endogenous tissue CO production; and 4) the tissue PCO that results from the balance between this endogenous CO production and diffusion to the blood sink. Because existing data demonstrate that virtually all endogenous CO production results from the routine “housekeeping” turnover of heme, only a small fraction can play a signaling role. The novel aspect of the present report is to demonstrate via physiological modeling that this small fraction of CO production is seemingly insufficient to raise intracellular PCO to the levels required for the conventional, specific messenger receptor activation. It is concluded that the many physiological alterations observed with exogenous CO administration are probably produced by the non-specific CO inhibition of cytochrome C oxidase activity, with release of reactive oxygen species (ROS) and that this ROS signaling pathway is a potential effector mechanism for endogenously produced CO. PMID:25750547

  15. An MHD simulation of the inner heliosphere during Carrington rotations 2060 and 2068: Comparison with MESSENGER and ACE spacecraft observations

    NASA Astrophysics Data System (ADS)

    Pahud, D. M.; Merkin, V. G.; Arge, C. N.; Hughes, W. J.; McGregor, S. M.

    2012-07-01

    We present results from a new magnetohydrodynamic (MHD) model of the inner heliosphere. The model is adapted from the well-established Lyon-Fedder-Mobarry (LFM) MHD simulation code, which until recently mostly applied to studies of the terrestrial magnetosphere. We perform quasi steady-state simulations of two Carrington rotations: 2060 and 2068. During both of these periods, the heliosphere remained quiet and undisturbed by transient phenomena, making them well-suited for simulation studies of Corotating Interaction Regions (CIRs). The MHD model of the solar wind is driven at the inner boundary by the Wang-Sheeley-Arge (WSA) model of the corona augmented with empirical relations to infer the solar wind velocity, density, and temperature. Here we report on a validation exercise whereby LFM-helio simulation results are compared with in situ data from the Advanced Composition Explorer (ACE) and MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft. We find that the model successfully reproduces the large-scale configuration of the inner heliosphere, namely timing and duration of high-speed streams and heliospheric current sheet crossings, as reflected in ACE and MESSENGER observations. Discrepancies between in situ measurements and simulations, such as 1-2 day errors in the time of arrival of a CIR or the strength of the simulated magnetic field at the spacecraft, are attributed to the uncertainty in the specification of the coronal conditions, rather than a poor performance of the solar wind model. More comparisons between different inner heliosphere models driven with identical coronal conditions are suggested as a way to explore their comparative strengths and weaknesses.

  16. Intense energetic-electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER

    NASA Astrophysics Data System (ADS)

    Dewey, R. M.; Baker, D. N.; Slavin, J. A.; Raines, J. M.; Lawrence, D. J.; Goldsten, J. O.; Peplowski, P. N.; Korth, H.; Krimigis, S. M.; Anderson, B. J.; Ho, G. C.; McNutt, R. L., Jr.; Schriver, D.; Solomon, S. C.

    2015-12-01

    One of the surprising observations by Mariner 10 during its March 1974 flyby of Mercury was the detection of intense bursts of energetic particles in Mercury's magnetosphere in association with substorm-like magnetic field reconfigurations. A full understanding of where, when, and how such particle bursts occur was not possible from the limited Mariner 10 data. The MESSENGER mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer (EPS), as well as data arising from energetic electrons recorded by the X-Ray Spectrometer (XRS) and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work has greatly extended our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary night side. The electrons evidently fill the plasma sheet volume and drift rapidly eastward toward the dawn and pre-noon sectors, at time executing multiple complete drifts around the planet to form "quasi-trapped" populations.

  17. Craters hosting radar-bright deposits in Mercury's north polar region: Areas of persistent shadow determined from MESSENGER images

    NASA Astrophysics Data System (ADS)

    Chabot, Nancy L.; Ernst, Carolyn M.; Harmon, John K.; Murchie, Scott L.; Solomon, Sean C.; Blewett, David T.; Denevi, Brett W.

    2013-01-01

    Radar-bright features near Mercury's poles were discovered in Earth-based radar images and proposed to be water ice present in permanently shadowed areas. Images from MESSENGER's one-year primary orbital mission provide the first nearly complete view of Mercury's north polar region, as well as multiple images of the surface under a range of illumination conditions. We find that radar-bright features near Mercury's north pole are associated with locations persistently shadowed in MESSENGER images. Within 10° of the pole, almost all craters larger than 10 km in diameter host radar-bright deposits. There are several craters located near Mercury's north pole with sufficiently large diameters to enable long-lived water ice to be thermally stable at the surface within regions of permanent shadow. Craters located farther south also host radar-bright deposits and show a preference for cold-pole longitudes; thermal models suggest that a thin insulating layer is required to cover these deposits if the radar-bright material consists predominantly of long-lived water ice. Many small (<10 km diameter) and low-latitude (extending southward to 66°N) craters host radar-bright material, and water ice may not be thermally stable in these craters for ~1 Gy, even beneath an insulating layer. The correlation of radar-bright features with persistently shadowed areas is consistent with the deposits being composed of water ice, and future thermal modeling of small and low-latitude craters has the potential to further constrain the nature, source, and timing of emplacement of the radar-bright material.

  18. LONGITUDINAL AND RADIAL DEPENDENCE OF SOLAR ENERGETIC PARTICLE PEAK INTENSITIES: STEREO, ACE, SOHO, GOES, AND MESSENGER OBSERVATIONS

    SciTech Connect

    Lario, D.; Ho, G. C.; Decker, R. B.; Roelof, E. C.; Aran, A.; Gomez-Herrero, R.; Dresing, N.; Heber, B.

    2013-04-10

    Simultaneous measurements of solar energetic particle (SEP) events by two or more of the spacecraft located near 1 AU during the rising phase of solar cycle 24 (i.e., STEREO-A, STEREO-B, and near-Earth spacecraft such as ACE, SOHO, and GOES) are used to determine the longitudinal dependence of 71-112 keV electron, 0.7-3 MeV electron, 15-40 MeV proton, and 25-53 MeV proton peak intensities measured in the prompt component of SEP events. Distributions of the peak intensities for the selected 35 events with identifiable solar origin are approximated by the form exp [ - ({phi} - {phi}{sub 0}){sup 2}/2{sigma}{sup 2}], where {phi} is the longitudinal separation between the parent active region and the footpoint of the nominal interplanetary magnetic field (IMF) line connecting each spacecraft with the Sun, {phi}{sub 0} is the distribution centroid, and {sigma} determines the longitudinal gradient. The MESSENGER spacecraft, at helioradii R < 1 AU, allows us to determine a lower limit to the radial dependence of the 71-112 keV electron peak intensities measured along IMF lines. We find five events for which the nominal magnetic footpoint of MESSENGER was less than 20 Degree-Sign apart from the nominal footpoint of a spacecraft near 1 AU. Although the expected theoretical radial dependence for the peak intensity of the events observed along the same field line can be approximated by a functional form R {sup -{alpha}} with {alpha} < 3, we find two events for which {alpha} > 3. These two cases correspond to SEP events occurring in a complex interplanetary medium that favored the enhancement of peak intensities near Mercury but hindered the SEP transport to 1 AU.

  19. AUSSAT mobile satellite services

    NASA Technical Reports Server (NTRS)

    Nowland, Wayne L.; Wagg, Michael; Simpson, Daniel

    1988-01-01

    An overview of AUSSAT's planned mobile satellite system is given. The development program which is being undertaken to achieve the 1992 service date is described. Both business and technical aspects of the development program are addressed.

  20. Understanding Mobile Apps

    MedlinePlus

    ... a device, you’re committed to using the operating system and the type of apps that go with it. The Android, Apple, Microsoft and BlackBerry mobile operating systems have app stores online where you can look ...

  1. Persuasive Mobile Health Applications

    NASA Astrophysics Data System (ADS)

    Garcia Wylie, Carlos; Coulton, Paul

    With many industrialized societies bearing the cost of an increasingly sedentary lifestyle on the health of their populations there is a need to find new ways of encouraging physical activity to promote better health and well being. With the increasing power of mobile phones and the recent emergence of personal heart rate monitors, aimed at dedicated amateur runners, there is now a possibility to develop “Persuasive Mobile Health Applications” to promote well being through the use of real-time physiological data and persuade users to adopt a healthier lifestyle. In this paper we present a novel general health monitoring software for mobile phones called Heart Angel. This software is aimed at helping users monitor, record, as well as improve their fitness level through built-in cardio-respiratory tests, a location tracking application for analyzing heart rate exertion over time and location, and a fun mobile-exergame called Health Defender.

  2. Mobile multiple access study

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Multiple access techniques (FDMA, CDMA, TDMA) for the mobile user and attempts to identify the current best technique are discussed. Traffic loading is considered as well as voice and data modulation and spacecraft and system design. Emphasis is placed on developing mobile terminal cost estimates for the selected design. In addition, design examples are presented for the alternative techniques of multiple access in order to compare with the selected technique.

  3. Libraries and the Mobile Web

    ERIC Educational Resources Information Center

    Hanson, Cody

    2011-01-01

    In 2011, cell phones and mobile devices are ubiquitous. The vast majority of Americans now own cell phones, and over half of them have mobile access to the Internet through a phone or other mobile device. For libraries to stay relevant, they must be able to offer content and services through the mobile web. In this issue of "Library Technology…

  4. Mobility. Snapshot Report, Fall 2011

    ERIC Educational Resources Information Center

    National Student Clearinghouse, 2011

    2011-01-01

    This paper presents information on student mobility for 2011. It offers data on the following: (1) Mobility Rates by Student Enrollment Status; (2) Mobile Student Enrollment at 2-/4-Year Institutions; and (3) Mobile Student Enrollment at Public/Private Institutions.

  5. Efficient Mobility Management Signalling in Network Mobility Supported PMIPV6

    PubMed Central

    Jebaseeli Samuelraj, Ananthi; Jayapal, Sundararajan

    2015-01-01

    Proxy Mobile IPV6 (PMIPV6) is a network based mobility management protocol which supports node's mobility without the contribution from the respective mobile node. PMIPV6 is initially designed to support individual node mobility and it should be enhanced to support mobile network movement. NEMO-BSP is an existing protocol to support network mobility (NEMO) in PMIPV6 network. Due to the underlying differences in basic protocols, NEMO-BSP cannot be directly applied to PMIPV6 network. Mobility management signaling and data structures used for individual node's mobility should be modified to support group nodes' mobility management efficiently. Though a lot of research work is in progress to implement mobile network movement in PMIPV6, it is not yet standardized and each suffers with different shortcomings. This research work proposes modifications in NEMO-BSP and PMIPV6 to achieve NEMO support in PMIPV6. It mainly concentrates on optimizing the number and size of mobility signaling exchanged while mobile network or mobile network node changes its access point. PMID:26366431

  6. Efficient Mobility Management Signalling in Network Mobility Supported PMIPV6.

    PubMed

    Samuelraj, Ananthi Jebaseeli; Jayapal, Sundararajan

    2015-01-01

    Proxy Mobile IPV6 (PMIPV6) is a network based mobility management protocol which supports node's mobility without the contribution from the respective mobile node. PMIPV6 is initially designed to support individual node mobility and it should be enhanced to support mobile network movement. NEMO-BSP is an existing protocol to support network mobility (NEMO) in PMIPV6 network. Due to the underlying differences in basic protocols, NEMO-BSP cannot be directly applied to PMIPV6 network. Mobility management signaling and data structures used for individual node's mobility should be modified to support group nodes' mobility management efficiently. Though a lot of research work is in progress to implement mobile network movement in PMIPV6, it is not yet standardized and each suffers with different shortcomings. This research work proposes modifications in NEMO-BSP and PMIPV6 to achieve NEMO support in PMIPV6. It mainly concentrates on optimizing the number and size of mobility signaling exchanged while mobile network or mobile network node changes its access point.

  7. Efficient Mobility Management Signalling in Network Mobility Supported PMIPV6.

    PubMed

    Samuelraj, Ananthi Jebaseeli; Jayapal, Sundararajan

    2015-01-01

    Proxy Mobile IPV6 (PMIPV6) is a network based mobility management protocol which supports node's mobility without the contribution from the respective mobile node. PMIPV6 is initially designed to support individual node mobility and it should be enhanced to support mobile network movement. NEMO-BSP is an existing protocol to support network mobility (NEMO) in PMIPV6 network. Due to the underlying differences in basic protocols, NEMO-BSP cannot be directly applied to PMIPV6 network. Mobility management signaling and data structures used for individual node's mobility should be modified to support group nodes' mobility management efficiently. Though a lot of research work is in progress to implement mobile network movement in PMIPV6, it is not yet standardized and each suffers with different shortcomings. This research work proposes modifications in NEMO-BSP and PMIPV6 to achieve NEMO support in PMIPV6. It mainly concentrates on optimizing the number and size of mobility signaling exchanged while mobile network or mobile network node changes its access point. PMID:26366431

  8. Mobile propeller dynamometer validation

    NASA Astrophysics Data System (ADS)

    Morris, Mason Wade

    With growing interest in UAVs and OSU's interest in propeller performance and manufacturing, evaluating UAV propeller and propulsion system performance has become essential. In attempts to evaluate these propellers a mobile propeller dynamometer has been designed, built, and tested. The mobile dyno has been designed to be cost effective through the ability to load it into the back of a test vehicle to create simulated forward flight characteristics. This allows much larger propellers to be dynamically tested without the use of large and expensive wind tunnels. While evaluating the accuracy of the dyno, several improvements had to be made to get accurate results. The decisions made to design and improve the mobile propeller dyno will be discussed along with attempts to validate the dyno by comparing its results against known sources. Another large part of assuring the accuracy of the mobile dyno is determining if the test vehicle will influence the flow going into the propellers being tested. The flow into the propeller needs to be as smooth and uniform as possible. This is determined by characterizing the boundary layer and accelerated flow over the vehicle. This evaluation was accomplished with extensive vehicle aerodynamic measurements with the use of full-scale tests using a pitot-rake and the actual test vehicle. Additional tests were conducted in Oklahoma State University's low speed wind tunnel with a 1/8-scale model using qualitative flow visualization with smoke. Continuing research on the mobile dyno will be discussed, along with other potential uses for the dyno.

  9. Autonomous mobile communication relays

    NASA Astrophysics Data System (ADS)

    Nguyen, Hoa G.; Everett, Hobart R.; Manouk, Narek; Verma, Ambrish

    2002-07-01

    Maintaining a solid radio communication link between a mobile robot entering a building and an external base station is a well-recognized problem. Modern digital radios, while affording high bandwidth and Internet-protocol-based automatic routing capabilities, tend to operate on line-of-sight links. The communication link degrades quickly as a robot penetrates deeper into the interior of a building. This project investigates the use of mobile autonomous communication relay nodes to extend the effective range of a mobile robot exploring a complex interior environment. Each relay node is a small mobile slave robot equipped with sonar, ladar, and 802.11b radio repeater. For demonstration purposes, four Pioneer 2-DX robots are used as autonomous mobile relays, with SSC-San Diego's ROBART III acting as the lead robot. The relay robots follow the lead robot into a building and are automatically deployed at various locations to maintain a networked communication link back to the remote operator. With their on-board external sensors, they also act as rearguards to secure areas already explored by the lead robot. As the lead robot advances and RF shortcuts are detected, relay nodes that become unnecessary will be reclaimed and reused, all transparent to the operator. This project takes advantage of recent research results from several DARPA-funded tasks at various institutions in the areas of robotic simulation, ad hoc wireless networking, route planning, and navigation. This paper describes the progress of the first six months of the project.

  10. Mobile systems capability plan

    SciTech Connect

    1996-09-01

    This plan was prepared to initiate contracting for and deployment of these mobile system services. 102,000 cubic meters of retrievable, contact-handled TRU waste are stored at many sites around the country. Also, an estimated 38,000 cubic meters of TRU waste will be generated in the course of waste inventory workoff and continuing DOE operations. All the defense TRU waste is destined for disposal in WIPP near Carlsbad NM. To ship TRU waste there, sites must first certify that the waste meets WIPP waste acceptance criteria. The waste must be characterized, and if not acceptable, subjected to additional processing, including repackaging. Most sites plan to use existing fixed facilities or open new ones between FY1997-2006 to perform these functions; small-quantity sites lack this capability. An alternative to fixed facilities is the use of mobile systems mounted in trailers or skids, and transported to sites. Mobile systems will be used for all characterization and certification at small sites; large sites can also use them. The Carlsbad Area Office plans to pursue a strategy of privatization of mobile system services, since this offers a number of advantages. To indicate the possible magnitude of the costs of deploying mobile systems, preliminary estimates of equipment, maintenance, and operating costs over a 10-year period were prepared and options for purchase, lease, and privatization through fixed-price contracts considered.

  11. Mobile Phone Terminal

    NASA Technical Reports Server (NTRS)

    1978-01-01

    In the photo, an employee of a real estate firm is contacting his office by means of HICOM, an advanced central terminal for mobile telephones. Developed by the Orlando Division of Martin Marietta Aerospace, Orlando, Florida, and manufactured by Harris Corporation's RF Division, Rochester, N.Y., HICOM upgrades service to users, provides better system management to telephone companies, and makes more efficient use of available mobile telephone channels through a computerized central control terminal. The real estate man, for example, was able to dial his office and he could also have direct-dialed a long distance number. Mobile phones in most areas not yet served by HICOM require an operator's assistance for both local and long distance calls. HICOM improves system management by automatically recording information on all calls for accurate billing, running continual performance checks on its own operation, and reporting any malfunctions to a central office.

  12. Mobility of Plasmids†

    PubMed Central

    Smillie, Chris; Garcillán-Barcia, M. Pilar; Francia, M. Victoria; Rocha, Eduardo P. C.; de la Cruz, Fernando

    2010-01-01

    Summary: Plasmids are key vectors of horizontal gene transfer and essential genetic engineering tools. They code for genes involved in many aspects of microbial biology, including detoxication, virulence, ecological interactions, and antibiotic resistance. While many studies have decorticated the mechanisms of mobility in model plasmids, the identification and characterization of plasmid mobility from genome data are unexplored. By reviewing the available data and literature, we established a computational protocol to identify and classify conjugation and mobilization genetic modules in 1,730 plasmids. This allowed the accurate classification of proteobacterial conjugative or mobilizable systems in a combination of four mating pair formation and six relaxase families. The available evidence suggests that half of the plasmids are nonmobilizable and that half of the remaining plasmids are conjugative. Some conjugative systems are much more abundant than others and preferably associated with some clades or plasmid sizes. Most very large plasmids are nonmobilizable, with evidence of ongoing domestication into secondary chromosomes. The evolution of conjugation elements shows ancient divergence between mobility systems, with relaxases and type IV coupling proteins (T4CPs) often following separate paths from type IV secretion systems. Phylogenetic patterns of mobility proteins are consistent with the phylogeny of the host prokaryotes, suggesting that plasmid mobility is in general circumscribed within large clades. Our survey suggests the existence of unsuspected new relaxases in archaea and new conjugation systems in cyanobacteria and actinobacteria. Few genes, e.g., T4CPs, relaxases, and VirB4, are at the core of plasmid conjugation, and together with accessory genes, they have evolved into specific systems adapted to specific physiological and ecological contexts. PMID:20805406

  13. Autonomous mobile robot teams

    NASA Technical Reports Server (NTRS)

    Agah, Arvin; Bekey, George A.

    1994-01-01

    This paper describes autonomous mobile robot teams performing tasks in unstructured environments. The behavior and the intelligence of the group is distributed, and the system does not include a central command base or leader. The novel concept of the Tropism-Based Cognitive Architecture is introduced, which is used by the robots in order to produce behavior transforming their sensory information to proper action. The results of a number of simulation experiments are presented. These experiments include worlds where the robot teams must locate, decompose, and gather objects, and defend themselves against hostile predators, while navigating around stationary and mobile obstacles.

  14. Correlation ion mobility spectroscopy

    DOEpatents

    Pfeifer, Kent B.; Rohde, Steven B.

    2008-08-26

    Correlation ion mobility spectrometry (CIMS) uses gating modulation and correlation signal processing to improve IMS instrument performance. Closely spaced ion peaks can be resolved by adding discriminating codes to the gate and matched filtering for the received ion current signal, thereby improving sensitivity and resolution of an ion mobility spectrometer. CIMS can be used to improve the signal-to-noise ratio even for transient chemical samples. CIMS is especially advantageous for small geometry IMS drift tubes that can otherwise have poor resolution due to their small size.

  15. Segway robotic mobility platform

    NASA Astrophysics Data System (ADS)

    Nguyen, Hoa G.; Morrell, John; Mullens, Katherine D.; Burmeister, Aaron B.; Miles, Susan; Farrington, Nathan; Thomas, Kari M.; Gage, Douglas W.

    2004-12-01

    The Segway Robotic Mobility Platform (RMP) is a new mobile robotic platform based on the self-balancing Segway Human Transporter (HT). The Segway RMP is faster, cheaper, and more agile than existing comparable platforms. It is also rugged, has a small footprint, a zero turning radius, and yet can carry a greater payload. The new geometry of the platform presents researchers with an opportunity to examine novel topics, including people-height sensing and actuation modalities. This paper describes the history and development of the platform, its characteristics, and a summary of current research projects involving the platform at various institutions across the United States.

  16. Mobile transporter path planning

    NASA Technical Reports Server (NTRS)

    Baffes, Paul; Wang, Lui

    1990-01-01

    The use of a genetic algorithm (GA) for solving the mobile transporter path planning problem is investigated. The mobile transporter is a traveling robotic vehicle proposed for the space station which must be able to reach any point of the structure autonomously. Elements of the genetic algorithm are explored in both a theoretical and experimental sense. Specifically, double crossover, greedy crossover, and tournament selection techniques are examined. Additionally, the use of local optimization techniques working in concert with the GA are also explored. Recent developments in genetic algorithm theory are shown to be particularly effective in a path planning problem domain, though problem areas can be cited which require more research.

  17. The Distribution of Magnesium on Mercury’s Surface as Measured by the MESSENGER X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Nittler, Larry R.; Weider, S. Z.; Starr, R. D.; Crapster-Pregont, E. J.; Byrne, P. K.; Denevi, B. W.; Blewett, D. T.; Solomon, S. C.

    2013-10-01

    We have used >6000 individual measurements acquired over two years by MESSENGER’s X-Ray Spectrometer (XRS) to construct a global map of the Mg/Si ratio across Mercury’s surface. In the northern hemisphere, both spatial coverage and resolution are sufficient to compare our map with geologic features. The global Mg/Si ratio varies from 0.15 to 0.90, which we attribute mainly to variations in Mg given that MESSENGER gamma-ray measurements indicate little variation in Si. Our work supports earlier results showing that large expanses of volcanic smooth plains at northern latitudes and in the interior of the Caloris basin have relatively uniform and low Mg/Si. In contrast, older intercrater plains and heavily cratered terrain (IcP-HCT) show striking variability in Mg/Si. The highest Mg/Si ratios (> 0.7) are seen in low-reflectance ejecta deposits that surround the Rachmaninoff impact basin, and in a large (>5×106 km2), relatively homogeneous region that is centered at ~30°N, 290°E. This region also has the lowest Al and highest Ca and S abundances derived from XRS data. Comparison with a map of crustal thickness (derived from MESSENGER geophysical data) shows that the large Mg-rich region coincides with an area of relatively thin crust. The shared boundaries (between high and low Mg, and between thick and thin crust) are particularly sharp along the northern and eastern edges; the latter is also near a major north-south-oriented fold-and-thrust belt and a region with a high density of observed hollows. There may also be a correlation between the Mg content and age of Mercury’s surface. The large Mg-rich region overlaps partly with some of Mercury’s oldest terrain as inferred from crater densities. Younger parts of the IcP-HCT (e.g., around Amaral crater) have significantly lower Mg/Si than the planetary average. Mercury’s surface is likely to have been extensively resurfaced by volcanism early in the planet’s history, so Mg/Si variations within regions of

  18. Evaluation of messenger plant activator as a preharvest and postharvest treatment of sweet cherry fruit under a controlled atmosphere.

    PubMed

    Akbudak, Bulent; Tezcan, Himmet; Eris, Atilla

    2009-08-01

    The preservation methods as an alternative to chemical control to prevent postharvest quality losses of sweet cherry were examined. The efficacy of preharvest and postharvest messenger (M) treatments on sweet cherry cv. '0900 Ziraat' was tested under a controlled atmosphere in 2004 and 2005. The factors investigated included the separate or combined effect of low oxygen, high carbon dioxide and M on the quality and fungal pathogens of sweet cherries in a normal atmosphere (NA) and in a controlled atmosphere (CA). Cherries were placed at six different atmosphere combinations (0.03%:21% [NA, control], 5%:5%, 10%:5%, 15%:5%, 20%:5% and 25%:5% CO(2):O(2)) at 0°C and 90% relative humidity for up to 8 weeks. Mass values were higher in cherries stored under NA compared with CA. Initial firmness was 1.45 kg and 1.41 kg in fruits without messenger (WM) and in M fruits, respectively; and was measured as 0.30-0.59 kg in WM and 0.57-0.95 kg in M at the end of the trials. The highest acidity and ascorbic acid values were recorded at the end of storage from the fruit stored under CA + M. The CA + M treatment proved the most effective with regard to delaying the maturity and preserving the fruit quality in sweet cherries during storage. Moreover, the CA + M treatments reduced the rotten fruit from 24.06% to 3.80% in cv. '0900 Ziraat'. Better fruit quality was obtained under CA + M compared with NA and CA. The fungi most frequently isolated from sweet cherries were Botrytis cinerea, Penicillium expansum, Monilinia fructicola, Alternaria alternata and Rhizopus stolonifer. It was concluded that sweet cherry cv. '0900 Ziraat' could be stored successfully under CA (20%:5%) + M, and partially under CA (25%:5%) + M, conditions for more than 60 days. Thus, it is recommended that CO(2) levels for sweet cherry storage can be increased above 15% with M.

  19. An aeronautical mobile satellite experiment

    NASA Technical Reports Server (NTRS)

    Jedrey, T. C.; Dessouky, K. I.; Lay, N. E.

    1990-01-01

    The various activities and findings of a NASA/FAA/COMSAT/INMARSAT collaborative aeronautical mobile satellite experiment are detailed. The primary objective of the experiment was to demonstrate and evaluate an advanced digital mobile satellite terminal developed at the Jet Propulsion Laboratory under the NASA Mobile Satellite Program. The experiment was a significant milestone for NASA/JPL, since it was the first test of the mobile terminal in a true mobile satellite environment. The results were also of interest to the general mobile satellite community because of the advanced nature of the technologies employed in the terminal.

  20. ATHLETE: A Mobility and Manipulation System for Mobile Lunar Habitats

    NASA Astrophysics Data System (ADS)

    Wilcox, B. H.

    2008-03-01

    ATHLETE is a mobility and manipulation system considered by recent Lunar Architecture Teams. This presentation will discuss the possible use of ATHLETE-based mobile habitats for global-scale scientific exploration of the moon.